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Numerical Operation Model Verification...

By: Zachary Labe , 4:43 PM GMT on December 22, 2009

"Historical Blizzard of December 2009"

(Courtesy of Americanwx.com)

A historical synoptic setup appeared evident nearly a week in advance of this storm system...

My long term section issued on December 12...
As I mentioned yesterday the east-based negative NAO will be retrograding towards a more favorable west-based negative NAO with above normal geopotential heights over the northern Atlantic including Greenland. With rex blocking forming towards the Hudson Bay in northern Canada, the 500mb jet pattern looks favorable going towards the week of Christmas. During my special Middle Atlantic Winter blog last winter I mentioned quite about the favorable trend for a negative to positive trending NAO causing large storms systems over the east coast. This trend may slightly be available around the 20-22 of the month. Another interesting teleconnection is the current negative AO anomaly which is nosing towards -3. This makes it one of the lowest AO anomalies in many years and I have seen statistics proving a negative AO this low in December would allow for a colder than normal winters as patterns similar to this are very difficult to budge under a winter-time regime. With favorable upstream blocking conditions and deep troughing over the east coast under a trough axis over the east coast, I think it is suffice to say the potential for a KU storm over the region is significantly higher than normal.

Well currently the AO has dipped today to the lowest on record for the month of December with -5.668. Link. The previous lowest on record occurred in 1976. Interestingly enough, once again the winter of 1976-1977 reoccurs on my list of analogs. Anyways with a record low negative AO, the NAO is also trending towards positive the classic acknowledgment of cyclogenesis along the east coast. What was evident early up the week in advance of the system was the impressive jet streak up the coast with a favorable trough axis allowing the cyclone to travel up the coast and/or near the 40/70 benchmark. The considering factor keeping me at bay for the week's model cycles was the PV position, which began to show trends of retrograding north and west. On December 16, I began to explore the close analog of February 1983 Blizzard...

This is a very bold statement considering my conservative stance usually... This has the potential to be a major east coast snowstorm or completely swing out to sea. There does not really appear to be a middle ground in this scenario. We really have everything we could ever ask for considering a Miller A creeping up the coast very slowly with a PV to the north and a high pressure with a decent positive PNA. But it all goes back to the phases of the shortwaves to our west and the location of the PV. Trends are encouraging, but I am not jumping the gun yet too much. I am surprised there are not more people tracking this as it is definitely the greatest threat for a major snowstorm we have seen in years even though guidance currently does not portray it. 0z NAM is a huge run in my opinion, we shall see trends, so I will post another modified update then. But I will be around this evening too track it too.

0z NAM on the 17th of December began to show the classic trend northwest. Classic KU storms always trended northwest within 24-72hr range, especially PDII. 12z ECMWF on the 17th also edged significantly towards a major snowstorm...

After these few model runs, everyone began to jump on the bandwagon of a historical snowstorm that would slowly climb the coast courtesy of anomalous blocking to the north. In this research blog I will explore the mesoscale features that allowed for unique banding and localized higher snow totals, also the second half of the blog will take a look at model verification.

Mesoscale Banding vs. Dry Air (Virga)...
Mesoscale bands are unique to significant storms along the East Coast in particular due to unique moisture 700mb transfers from physical features such as the Gulf Stream from the Atlantic Ocean and the Gulf of Mexico along with the Great Lakes to the northwest. Mesoscale banding is usually associated with localized features such as surface fronts and inverted troughs. Surface fronts are typically responsible for the mesoscale banding present in KU storms and are usually located along isolated baroclinic zones. They are anomalous easterly 700mb moisture transfers associated with warmer air and PWATs ascending over the northeast flow with a 1030mb+ high to north at the surface to over 800mb aloft. Surface fronts typically run from either south to north or southwest to northeast allowing bands to remain stationary or pivot slightly northwest. These convergence zones allow for heavy precipitation totals and can usually be discerned not only by NEXRAD radar, but also by pressure falls of near 15hPa/3hr. Low level warm air advection and frontogenesis can also intensify these precipitation rates.

Around 4pm, radar composites evidently showed several of these unique mesoscale bands across the Middle Atlantic localizing snowfall rates of up to 3in/1hr. As noted above, a gravity wave is shown, which are very common in classic significant winter storms. These gravity waves can enhance precipitation rates north of the warm front near the interaction of the troposphere jet streak. The gravity waves appear as bands of convective activity allowing also for unusual cloud formations and pressure fluctuations. Unusual wind direction aloft interaction and combined rapid surface pressure troughs can be a catalyst for gravity waves in the more significant of winter storms. Gravity waves typically propagate northward. In this storm in particular the noted gravity wave caused an enhanced series of bands from Richmond to Washington DC with TSSN being reported in Richmond, VA.

Another interesting mesoscale feature of note in this historic blizzard, was the convergence zone around an inverted trough towards the New Jersey, northern Delaware, and Philadelphia region.

This inverted trough formed in response to the approach upper level trough and axis of lower surface pressure falls north of the main cyclongenesis towards the southern Delmarva. This allowed for enhanced mesoscale banding and higher QPF. Several models including the ancient MM5 and modern high resolution RUC and ARW were able to pick up on this feature a bit in advance...

(Courtesy of Americanwx.com)

Current operation models, especially global models do not have high enough resolution to pick up on the mesoscale features as listed above. This poses forecasting headaches for pinpointing where the enhanced snow totals will occur. Other synoptical forecast problems exist with precipitation gradients on the north and northwest sides of systems...

Two highly noticeable snowfall gradients occurred in this system with one locally noted around the Pennsylvania I-76 turnpike and the other occurring about 25mi south of I-80. The first cutoff was between the mesoscale banding of a surface front in northern Maryland and southern Pennsylvania allowing for heavy snow in the banding region, but only moderate totals a few miles to the north. This is evident in just one quick example of a 15mi difference in Lancaster County, Pennsylvania...

LITITZ 9.0 457 PM 12/19 SPOTTER

Northern snowfall boundaries exist courtesy of sharp, rising western boundaries of cold conveyor belts with high pressure allows for strong confluence. This was highly evident this was going to exist in this scenario in response to the Polar Vortex located over upstate New York and southern Quebec. As will be noted below several higher resolution models were able to detect the sharp cutoff to the north. Also, while trying to pinpoint snow total forecasts, I took the stance of a sharp-cutoff to the north, which paid out to be highly accurate. The only issue with my snow map below was the detection of the surface front mesoscale banding over Franklin, Adams, Lancaster, York, Chester, Philadelphia, and Delaware County. I though, was able to note the inverted trough band over Montgomery and Berks County. In general I am very pleased with my official forecast map for Pennsylvania. Here are the plotted snow totals vs. my forecast...

Also important to note are several upper level features that help distinct the location of the heavy snow axis. These old rules of thumb were actually used quite heavily before the plethora of models we have now. What is interesting to note is several model runs including the NAM and GFS suffered convective feedback problems earlier in the week, but using these techniques I was able to see the surface guidance was likely progged wrong allowing for the heavy snow axis to be farther north and west. The presence and position of 500mb chart features is critical to the location of the surface low track, 850hPa low track, jet streak location, maximum vorticity, and QPF location.

The H5 chart above details December 19 and the location of several of these important factors. 300mb and 500mb charts depict winds aloft including the jet stream allowing for us to be able to see the position of troughing, ridging, etc. First what must be present is a split flow with a dominate subtropical jet allowing for the formation of the low, and a polar jet keeping arctic air on the north side of the United States into Canada. The subtropical jet is typically the catalyst for development allowing for cyclogenesis either in the Gulf of Mexico for Miller A systems or near the southern North Carolina coast for Miller B systems. In this instance it occurred in the Gulf of Mexico deepening to near 1000mb crossing the Florida panhandle. Next on the checklist is for the presence of a shortwave embedded in the flow allowing for an increase in amplitude in the trough. In this instance you can note above is was located in Missouri. Looking at analogs a similar S/W placement occurred for the nor'easter of 19 January 1987 also located in southern Missouri. In any case this impulse is important as it spawns the primary low over the Gulf of Mexico or Atlantic Ocean and allows for increase wavelength and amplitude of the trough, hence the term amplifying trough. Also important is the presence of a closed low in either Newfoundland or across the Canadian Maritimes. This acts as an anticyclone allowing cold air advection to continue to filter down the east coast in a conveyor belt. In this instance above you can note it was located near Nova Scotia.

Also of importance is a building negative EPO ridge/positive PNA. This helps to increase wavelength and amplitude of the trough. Also typically of importance is the presence of a cutoff low in the desert southwest, but it was absent in this storm very similar to the zonal flow in the southwest during February of 1983. The term jet streak is also of importance as it allows for a higher distribution of maximum vorticity, maximum confluence, and allow for left exit regions of the cyclone. Heavy snow corridors are always confined parallel or to the west of the jet streak. The jet streak is also noticed as acting as a low level thermal field coinciding with heavy snowfall patterns along the corridor. As the trough begins to turn negatively tilted with jet stream winds near 100knots up the coastal plain (jet streak), the vorticity maximum is noted typically tracking through the Ohio Valley up through southern Virginia advecting off towards the Delmarva. In this instance it traveled a bit farther northward towards Washington DC up through central Delaware to located just south of Long Island. The location of the 500hPA vorticity is important as far as precipitation types go with locations to the south by 50mi or so likely experience precipitation changeovers from snow to rain or sleet/freezing rain. But locations from 50mi south of vortex on northward usually allow for snowfall. This was evident in the December 19th event as location about 25mi changed to rain briefly and then back to snow. Also of importance and noted above is the position of a cutoff trough over southern Canada towards Ontario. As you can see in that 500mb chart, there is an anticyclone noted just north of Lake Superior. This blocking allows for confluence over the Northeast, which acts as cold air advection in to the II quadrant of the cyclone.

Of likely most significant importance is the track of the 850hPa low...

As noted above for December 19, this tracked south of Virginia across northern North Carolina and tracked near the 40/70 benchmark. Tracks of 850hPa lows typically track east to northeast along the Middle Atlantic to New England coast allowing for ideal snow forecasting methods. December 19th allowed for geopotential heights to indicate a strengthening 850hPa low tracking as followed above. In most instances the heaviest snowfall occurs 50km-300km to the north or northeast of the 850hPa low track. This corresponds to in this instance the heavy snow falling over southern Pennsylvania to as far south as northern Virginia correlating to the I-95 corridor on eastward being impacted with the heaviest snow up the coast. The track of the 850hPa low was just too far eastward for areas over central Pennsylvania to southern New York State up through western Massachusetts to get impressive snowfall totals.

(Courtesy of Americanwx.com)

Using these techniques I was able to make a generalization forecast without really looking at surface numerical model maps such as QPF fields. These tools are general rules of thumb including the above mesoscale section of synoptic forecasting. So now that we looked at the forecasting w/o model aspect, let’s look at model verification...

Numerical Model Verification...
Model verification is highly important during the winter season in future synoptic precipitation events. Being able to pinpoint common biases will be beneficial in the long term. All model maps are courtesy of the archives located at Americanwx.com...

GFS at 84hrs...

Noted above are several errors in the surface map. First the location of the closed low in Canada was slightly progged too far east and needed to be reassessed farther towards the west coast of Nova Scotia. The idea of the precipitation sharp cutoff in quadrant II of the storm was correct in this cycle all the location was several hundred miles too far east. Important to note at this time frame is a southeast bias in the GFS. At first talk in the meteorological community was the typical northwest trend was occurring because of the Southeast ridge during the previous -SO years, but with the absence of the La Nina and Southeast ridge, we continue to see a correction of the GFS to the northwest in this time frame. What is critical to note is the abnormal use of the GFS. Most local meteorologists use the GFS almost 80% for their forecasting, this includes other weather agencies. So the reason for the lack of jumping on board for this storm for most was due to the GFS track offshore. This is interesting as in relatively the GFS has some of the worst verification scores out of the global models, but due to its easy maps to read and readily availability, it makes it very popular.

GGEM at 126hrs...

Also at 3-5 days out the GGEM had the surface low relatively far east tracking outside of the 40/70 benchmark. But interesting to note is the position of several inverted trough features over New Jersey which actually verified closer to the event. In general this GGEM run did a much better job at the medium range forecasting this system.

NAM at 78hrs...

The NAM was much more interesting at this ranging progging the low to be a good 50-100mi closer to the coast to the GFS. But using the rule of thumb techniques mentioned above, I was able to pinpoint that the NAM was suffering surface convective feedback problems allowing for the sharp-precipitation cutoff line near the Mason-Dixon Line and for the odd left exit region the cyclone took.

Closer towards the short term forecasting aspect of storms systems such as this, it is important to make use of several higher resolution models, one of which performed amazingly accurate during this storm.

SREF at 60hrs...

Despite the NWS offices infatuation with the Short Range Ensemble Forecasts, I have never quite been a fan of the mean resolution run. I find several individual ensembles are usually too extreme or opposite ends of the spectrum skewing the final results. In any case the SREF QPF appeared a bit too low in this time frame.

NAM at 27hrs...

One of the most accurate models once again was the NAM which scored highly in verification. While the sharp northern precipitation cutoff was about 25mi too far south, it did note several important mesoscale features. One of them included the abnormally dry dew points over the southern Poconos into the Lehigh Valley and Schuylkill Valley. Also it noted the surface front frontogenic forced mesoscale band over northern Maryland with QPF totals near 2in. Interestingly enough the NAM is often regarded as a wet biased model, but it performed much better in the QPF shield and amounts than the GFS did.

ETA at 51hrs...

Surprisingly enough one of the best models at this range was the ETA, which is quite unusual since the NCEP retired this model years ago. But its QPF placement was really spot on along with several mesoscale features being noted actually verifying. The ETA is the model often regarded as forecasting some of the strongest storms of the century including the 1993 Superstorm, PDII, and the Blizzard of 1996.

GFS at 6hrs...

One of the worst models even at 6hrs out was the GFS. It did a terrible job forecasting the low track, which verified closer to the coast and it also had the QPF precipitation shield well too far northwest. Again interesting to note is the GFS as being used by so many meteorological services, that is one reason the NWS issued warnings for locations such as Williamsport, PA up the Poughkeepsie, NY in which those locations saw T-1in. Lesson learned from the past three winter events I think is to stray away from the GFS, although the local meteorologists will likely never do so.

HIRES ARW at 48hrs...

The most accurate model progging of this storm verified at the 48hr forecast from the HIRES ARW run by the NCEP. Interestingly enough its brother the HIRES NMM did not verify so well, but the ARW did a wonderful job at QPF verification especially over northern Maryland through southern Pennsylvania and southern New Jersey. It also noted the sharp-cutoff just south of the I-80 corridor.

In conclusion once again in general the NAM scored the best verification out through 84hrs with only a few slightly convective feedback problems along the way through the model run cycles. Long range models, the GGEM scored the highest for medium range followed by the ECMWF, with the good ol' American GFS coming in last. Keep in mind supposedly the GFS just went under a few upgrades. Anyways as far as high resolution models, the HIRES ARW performed the highest with near spot on QPF totals and surface low track. My goal through this research blog was to expand one's horizon above just numerical model forecasting, but to look at a synoptical approach. When I analyze my forecasting methods, I do not just use what the GFS 850mb Temp/Heights/QPF looks like, but I verify to see if it looks accurate compared to the progged H5 and H3 charts. I try to use a blend of guidance to come up with a reasonable solution, with my reasonable solution typical based of some sort of analog.

(Courtesy of Americanwx.com)

"Index of /winter0910/storms/Dec1909." New York MetroWeather. Web. 22 Dec. 2009.

Kocin, P. J., and L. W. Uccellini, 2004: Northeast Snowstorms, Volume I: Overview. Meteor. Monogr., Vol. 32, No. 54, Amer. Meteor. Soc., 1-296. Print.

"Here northeast of Harrisburg 2009-2010 winter statistics"
(Snow Stats)
Current Snow Cover- 1.50in
Monthly Total- 13.0in
Seasonal Total- 13.0in
October Total- 0.0in
November Total- Trace
December Total 13.0in
Winter Weather Advisories- 3
Winter Storm Warnings- 1
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 1
Winter Storm Watches- 1

(Temperature Stats)
Lowest High Temperature- 28.0F
Lowest Low Temperature- 14.7F
Wind Chill Advisories- 0
Wind Chill Warnings- 0

(Winter Storms Stats)
Dec 5 - 1.5in - First accumulating snow of season
Dec 8-9 - 2.5in - Snow changed to plain rain
Dec 13 - .1in - Freezing rain
Dec 19 - 9.0in - Heavy snow, higher amounts to south

Update 4:30pm 29 December 2009...
Good afternoon!!! In a few days I will be approaching my third year on Wunderground. When I approached this site in December of 2007, I expected creating a blog only forecasting basically my opinions for the Harrisburg geographic region. To some it may be a surprise, my age 17, or perhaps not in some regard. I kept my age hidden in part because of the dangers of the internet, but also the reaction. How in the world would adults respect a teenager forecasting the weather and telling them information? Knowing the acceptance level across the meteorological community for teenagers being regarded as weather weenies, I was apprehensive and kept this minuscule fact hidden. Upon the creation of my blog, I was going to go above and beyond a mediocre performance.
My passion for weather is correlated back to a very young age and my interest consumes not just the actual tangible thunderstorm presence, but for the "physics" behind the mechanics of the atmosphere. I built a foundation in general with the presence of books, in my meteorological library. But as I advanced in books from "The Weather Channel Basic Comprehension Weather Book" I moved into meteorological textbooks. This correlated with my current curriculum in high school of college level honors Calculus and Physics allowed me to bridge the transition from pure weather enthusiasts and weenie to actually understanding the process of lets say "the reason driving a car on a clear night will allow for violent temperature fluctuations driving over hills and into valleys." Having pursued personal interviews with meteorologists, taking online courses, visiting different meteorological communities, and using the resources of the 21st century; I grew as a young adult. The sails of my ship were visible at a young age, which is for the definite pursuance of meteorology and this goal has not left the tip of my eyes ever since.

Information in my actual physical blog and comments have always been and will always be of my own. While I learn from others, as asking a question is key for education, I believe in credit given where it is due. Being apprehensive about being accepted on here was critical and has always been. Understanding perfectly, I can see adults being unable to accept me for being anything but a weather weenie. While yes I love the idea of monstrosity of a blizzard affecting my region; I also enjoy the physics behind the due process of the low pressure bombogenesis. All I am asking is really for no changes on the blog as really nothing is changing other than this announcement. I have been on this blog for three years and I have gained a solid reputation and a plethora of experience. Yes I love vegetable gardening, photography, PennDOT jokes, etc... I am what you would call perhaps unusual for one's age, hahaha. But my peers, family, associates, community, have continued to always encourage my passion for the science of meteorology. There is a cliche saying "you learn something new every day," this is true more than ever in the process of education. It is a constant transition and/or push or pull between educating others with adults teaching students, and students teaching adults.

In general I ask this, approach this with an open mind and not with a biased opinion and conclusion. Wunderground remains a mature and respecting community, so expect nothing to change here. While I may come off a bit conceded or mellow dramatic, this is all to prove my point that my blog is all collaboration of my knowledge and not that of others in some twisted form of plagiarism. One can consume as much education as the next if you put your mind to it. So go about this in strife as we have been the last three years here on Wunderground. Thank you to all in support of my blog over the years.

Here is to another few years!!!

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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496. synthman19872003
8:22 PM GMT on December 30, 2009
Blizz it sounds like your NWS has something again your part of the CWA LOL! I have a similar situation with mine (Raleigh), but it's the opposite, they actually like to hype up the Triad with frozen precip. I guess it's because we're in the NW corner of their coverage area, more geographically favored for CAD, but the strange thing is that they do this sometimes even when the other neighboring offices forecast nothing but rain, even for the mountains! Go figure...
Member Since: December 31, 1969 Posts: Comments:
495. Zachary Labe
7:52 PM GMT on December 30, 2009
Winter weather advisory out. But sorry CTP I do not know where they are coming from with the freezing rain. 15z SREF just came out with .25in all snow for most of Lower Susquehanna Valley. Even LWX south of us is forecasting more snow. GFS is only model forecasting freezing rain and really hardly noticeable at that, ECMWF much colder too along with high resolution models. I would not be surprised if NAM came in with higher amounts looking at the radar across the southeast. With evaporational cooling aloft and at the surface along with 2m temperature verifying colder than forecast today, sorry just do not see H85 0C warming above freezing especially north of the turnpike for the first wave. There will probably be some light freezing drizzle over York and Lancaster County, but I do not think hardly any farther north.
Member Since: December 31, 1969 Posts: Comments:
494. Zachary Labe
7:15 PM GMT on December 30, 2009
Snow will move in early morning Tomorrow and last through mid morning. It is a very quick hitting event. My blog this evening will have full details.
Member Since: December 31, 1969 Posts: Comments:
493. shipweather
7:11 PM GMT on December 30, 2009
Blizz, time frame for this is what?
Member Since: December 31, 1969 Posts: Comments:
492. MoCoMd
7:07 PM GMT on December 30, 2009
158 PM EST WED DEC 30 2009

158 PM EST WED DEC 30 2009







Member Since: December 31, 1969 Posts: Comments:
491. Zachary Labe
6:44 PM GMT on December 30, 2009
Well I am locking in my forecast of 1-4in for the Lower Susquehanna Valley. The CTP forecast of rain/freezing rain does not look valid at all. GFS is the only model advertising a mix, everything and I mean everything is colder. In any case I expect a winter weather advisory map. Snow map will be out tonight as there will be a few areas that may see 2-5in. I am trying to get a new blog out before I leave to go somewhere this afternoon, but that does not look likely. New blog definitely out by 9:30pm.
Member Since: December 31, 1969 Posts: Comments:
490. TheDawnAwakening2
6:21 PM GMT on December 30, 2009
Blizzard - models are finally agreeing with my worst fears. The PNA index is neutral and may be the reason for the more amplified further eastward solution leading to a monster blizzard for Canada and the fish. Our next threat looks to include a potential monster with the PNA index likely to go to +1-2 and the -NAO and -AO. The Blizzard of 1978 had similar teleconnections, but the NAO index was around-.5 instead of the -2 its at now. I think the period of Jan7-10 is the one that has the most potential. Unfortunately this storm for this weekend the models are now looking at the first disturbance as the stronger one, although the second one is the strongest, but the models are stronger with the first one leading to a more out to sea solution where the storm will kill NNE.
Member Since: December 31, 1969 Posts: Comments:
489. TrentonThunder
5:42 PM GMT on December 30, 2009
Yup, this is the whole baseball team reporting here! Thought it was a cool name. I'm about 3 miles northeast of the stadium so the name was already in my psyche!
Member Since: December 31, 1969 Posts: Comments:
488. TrentonThunder
5:39 PM GMT on December 30, 2009
Blizz - The emphasis is on Philadelphia but covers southern New Jersey, Northern Delaware, some Poconos, I believe as far west as Chester County, maybe Lancaster County? I'm not sure how much Harrisburg is in there, maybe some. I'll have to look at it again. It's worth getting though...
Member Since: December 31, 1969 Posts: Comments:
487. zotty
4:24 PM GMT on December 30, 2009
Blizz- I echo everyone else. While I am impressed with your math, what really sets you apart is your English- that is, your writing. You write very well. Thanks for all the hard work.

I don't know if you have spoken about these in the past, but Brian Fagan's books are a joy to read and bring real perspective on climate change, etc. I would highly recommend "The Little Ice Age" and am currently reading "Floods, Famines, and Emperors: El Nino and the Fate of Civilizations," which is pretty good, too. He has a whole bunch of other books, and I will probably try to read them all.

Thank you again!
Member Since: December 31, 1969 Posts: Comments:
486. Zachary Labe
4:06 PM GMT on December 30, 2009
TheRasberryPatch- Rain, no? The whole second wave has fizzled out with little southern stream interaction until it is too late. And really surface temperatures probably more realistically would have even been marginal for wet snow. Temperatures may get into the mid 30s on Friday or possibly Thursday, but I do not think any higher than that. Now down towards areas in Maryland and such, yes they will get pretty warm and if they get an inch tonight, it will probably wash away.
Member Since: December 31, 1969 Posts: Comments:
485. shipweather
4:05 PM GMT on December 30, 2009
I head to Miami on Sat. I'd love to see just one last little snow!

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484. TheRasberryPatch
4:02 PM GMT on December 30, 2009
TrentonThunder(TT) - The Chesapeak Bay used to freeze over as well. Back in the 70's I recall local news talking about the Coast Guard cutter breaking up the ice in the shipping lanes. I might have to investigate those books as well. I love reading about the weather back in Colonial days and how they coped.

Blizz - even if the snow comes for you this evening, won't it be washed away from the rain?
Ever find a good journal for writing down weather for the day?
Member Since: December 31, 1969 Posts: Comments:
483. cyclonebuster
4:00 PM GMT on December 30, 2009
All you have to do is look at the flow coming out of the GOM to see what will happen with this storm?????
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482. Zachary Labe
4:00 PM GMT on December 30, 2009
PalmyraPunishment- Hahaha... NAM usually does well in these scenarios with QPF and temperature profiles. Warm air advection snow is difficult to forecast becausing it typically is invading an arctic airmass with lows of mid level dry air. Low levels do not look terrible though as dewpoints have been rising all morning from the mid single digits up through the mid to upper teens.
Member Since: December 31, 1969 Posts: Comments:
481. PalmyraPunishment
3:57 PM GMT on December 30, 2009
hahahahaha and the epic swing in modelcast begins. by noon the models will show phasing, a track just west of benchmark and the big monster storm that they originally hyped lol

everyone who committed suicide last nite offed themselves for nothin'! hahaha

Member Since: December 31, 1969 Posts: Comments:
480. cyclonebuster
3:56 PM GMT on December 30, 2009
What's up with Blizzard92 why won't he answer my question? This should be right up his ally.
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479. Zachary Labe
3:52 PM GMT on December 30, 2009
12z GFS is similar to 12z NAM in the QPF field so I think it is possible for a 1-4in snowfall tonight into tomorrow morning, especially north of Mason-Dixon line.
Member Since: December 31, 1969 Posts: Comments:
478. PalmyraPunishment
3:47 PM GMT on December 30, 2009
by the way i just noticed that not only do we have the airport becoming a regular in this blog (bwi) but now we have a Minor League Baseball team as well (TrentonThunder)

this is great.
Member Since: December 31, 1969 Posts: Comments:
477. cyclonebuster
3:45 PM GMT on December 30, 2009
LOL! Is Blizzard92 ignoring me?????
Member Since: December 31, 1969 Posts: Comments:
476. Zachary Labe
3:31 PM GMT on December 30, 2009
TrentonThunder- Ah they sound interesting. I have the "Pennsylvania Weather Book" by Ben Gelber, but I would be interested in the other two. How much area does the Philadelphia weather book cover?
Member Since: December 31, 1969 Posts: Comments:
475. TrentonThunder
3:29 PM GMT on December 30, 2009
BLIZZ - I have a couple of area weather books that I found very interesting, you might have them.

One is called "Pocono Weather" by "Ben Gelber". It's a little outdated now, released in 1992, but it covers weather of Eastern Pennsylvania with a focus on The Poconos starting in the 1700's with excerpts taken from newspapers of Blizzards and such from way back when.

Another is called "The Philadelphia Area Weather Book" by "Jon Nese" and "Glenn Schwartz", released in 2002. It also covers very interesting weather reports and facts dating back to the 1700's. For instance, I learned from this book that during the end of "The Little Ice Age" (1700's) that the Delaware River in Philadelphia used to freeze over regularly, sometimes frozen solid uninterupted from December through March, which is pretty amazing considering it's rare these days to get it to freeze over completely at all, let alone for more than 1 week.

Anyway, interesting books if you do not have them...
Member Since: December 31, 1969 Posts: Comments:
474. Zachary Labe
3:02 PM GMT on December 30, 2009
TheRasberryPatch- Towards Friday and Saturday a closed low will cutoff towards Nova Scotia allowing for an extended period of time under a cyclonic flow likely causing the largest lake effect snow outbreak thus far across Ohio and Pennsylvania. Monday night I received a coating of snow from a 322 band; down towards Hershey I saw a bit more of a coating with a few drifts of 1in, lol.
Member Since: December 31, 1969 Posts: Comments:
473. TheRasberryPatch
2:57 PM GMT on December 30, 2009
Blizz - if you are doing that well in Calculus I you won't have any problems with the rest of Calculus and Diff EQ.

Thanks for the forecast. Will Ohio or PA be involved with the significant lake effect as well? I am guessing the NW flow will invade our area at some point. oh, btw - did you get any snow from Monday's lake effect?
Member Since: December 31, 1969 Posts: Comments:
472. Zachary Labe
2:53 PM GMT on December 30, 2009
mara0921- Sure, towards this weekend an arctic front is poised to move across the eastern half of the nation dropping into the deep south. Towards early next week into mid week GFS ensembles and the ECMWF hint at a disturbance developing along the Gulf Coast, but with increased upstream blocking over northern New England, this system may have a hard time moving north. While a lot of variables need to fall in place, it is possible for a southeast snowstorm particularily towards Georgia up through South and North Carolina. As for Florida, based on climatology it would be pointless calling for snow at this point. Stay tuned and thanks for stopping by!!!

breald- Guidance suggests a low pressure traveling over or near MA which will allow temperatures aloft to rise above freezing. Some of the foreign global models indicate development farther east favoring a cold scenario. It will generally be close. Thanks for stopping by!
Member Since: December 31, 1969 Posts: Comments:
471. cyclonebuster
2:51 PM GMT on December 30, 2009
What you think of my tunnel idea to weaken landfalling hurricanes and to control climate?

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470. Zachary Labe
2:50 PM GMT on December 30, 2009
originalLT- That is isentropic lift snow associated with warm air advection.

TheRasberryPatch- Hahaha... thankyou! With the ratio of meteorologists from PSU nearly 3:4, those odds are just so high. I am talking Calculus currently as junior and possibily either statistics as a senior or Calculus II. I have an mid 'A' currently in my second quarter and first quarter for Calculus, so I am not too worried yet. I do not plan on leaving wunderground during school, but I just won't be able to be on as much. As for your forecast, northwestern Indiana may see a major lake effect snow outbreak from the 31st-3rd of January. Looks like a decent northwest flow under bitter cold temperatures in the teens or below. Stay warm!

PalmyraPunishment- It does not overly surprise me considering it is pure warm air advection snow, all snow at that. But NAM typically is a bit biased on the wet side, so I lean in caution.

Finky- It would probably be 2-5in considering ice crystal growth is generally needles and columns which are not as favorable to accumulate like dendrites.
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469. breald
2:47 PM GMT on December 30, 2009
They are predicting rain/snow from Thursday thru Sunday for Southern New England. It appears more rain than snow for us at this time.
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468. mara0921
2:46 PM GMT on December 30, 2009
Good Morning Blizzard92,

On Dr. Masters blg for the last 2 days there has been ALOT of talk and speculation about snow and a historic arctic outbreak next week and continuing for a week or two in Florida, even SE Florida where I am at. I would love to hear your thoughts on this and what you think may happen in the sunshine state. Snow is so rare that it gets everyone so excited. It has only snowed in Ft Lauderdale once back in 1977 and we havent had a real freeze since Christmas 1989. Thanks
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467. PalmyraPunishment
2:45 PM GMT on December 30, 2009
i'd take it... i just don't think that's the case
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466. Finky
2:43 PM GMT on December 30, 2009
Quoting PalmyraPunishment:
wow that's definitely the little shift in opinion. would that be mixed precip or all snow/rain?

Someone on crapuweather (as you call it) said the recent model show us in the 3-6 inch range. That would be ok with me.
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465. PalmyraPunishment
2:32 PM GMT on December 30, 2009
wow that's definitely the little shift in opinion. would that be mixed precip or all snow/rain?
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464. TheRasberryPatch
2:31 PM GMT on December 30, 2009
Good morning Blizz.

I am dumbfounded. Your mentality and education in meteorology and maturity is way beyond your years. I, like most here, thought I was interacting with someone that was married with a family. I think if we were all panelists on "To Tell the Truth" we would be rolling on the floor in disbelief.

For the record, I hope you don't pick PU. UGH. Another obnoxious PU fanatic on this blog. Just kidding. As for Calc and Diff EQ, I loved those classes. That is why I got my BS in Physics. The math aspect is what I enjoyed so much. If you can do Algebra, you should be able to do Calculus. A bit different but similar. When you go to school, What shall we do? Where will we go? And do give us Frankly, I don't give...

BTW - I am in South Bend. On my way out here on Monday, I hit a lot of lake effect. From the time I got to Ship it was on and off, with heavy accumulations on the road around Cleveland. What a pain. Now they have a special weather statement for this area Friday into the weekend for lake effect with significant accumulations. Can you give me more info on this Arctic front and what to expect from it for the weekend for Ohio and Pa. There is about 3" on the ground now here from Sunday into Monday lake effect.
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463. originalLT
2:30 PM GMT on December 30, 2009
Don't see much of a low pressure system anywhere, Blizz?
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462. Zachary Labe
2:16 PM GMT on December 30, 2009
Thanks all!!!

12z NAM indicates tonight into tomorrow morning may be interesting...
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460. originalLT
1:30 PM GMT on December 30, 2009
Morning Blizz and all, my local mets, (NYC.area) are coming around to your feeling that this basically will be a non-event or should I say a minor event for Dec. 31 and Jan1.--a light snow/rain happening. As for my "gut feeling" of 3-5" by FRi. night, it must have been just"indigestion"! Looking foreward to this afternoon's Blog up-date.
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459. onoweather
7:46 AM GMT on December 30, 2009
blizz- i hope you choose PSU, although I am biased as I am a student lol. There meteorology program is very well respected. I personally would have gone to main campus for meteorology but calc II is about my limit. When I first came on to the blog it seemed you had school hours, but like Palmyra I thought you were probably a school teacher. Anyways your forecasts are much better than anyone I know and keep up the good work.
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458. shipweather
6:31 AM GMT on December 30, 2009
I will be there for the anchor drop! And I guess I was sippin' too much accu-juice. I'm cool now!
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457. upweatherdog
4:43 AM GMT on December 30, 2009
00utc NAM is forecasting a pretty intense snowband over the northcentral U.P around 7:00AM Saturday.

As winds switch a bit more northerly in the shortwave troughs rottating around the low, the heavy LES should move into my area.
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456. Zachary Labe
4:11 AM GMT on December 30, 2009
These new model prognostics are really making me laugh, I just do not know why I did not see this earlier. 4-5 S/W and vortices of energy embedded in the H5 flow just does not produce the low to close off until the Gulf of Maine allowing only Northern New England to see a heavy snow event. I was baffled all week by this system and will be glad when it is over. Toast #2 to dry, cold northwest winds for the weekend and beyond! For those with concerns across the north and west parts of the Middle Atlantic, the threat for a major lake effect snow outbreak remains very high towards the weekend.
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455. PalmyraPunishment
4:03 AM GMT on December 30, 2009
one busted storm and you're calling it, shipweather?!?!?!

i was joking then, i might mean it now lol. YOU GO STAND UNDER THE ANCHOR WHEN IT'S DROPPED, SIR! lol
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454. Zachary Labe
4:02 AM GMT on December 30, 2009
Quoting PalmyraPunishment:

sadist. haha

Hahaha... Well 0z GFS is too slow with southern jet stream interaction as is the NAM, so the low generally moves out to sea only causing a little light QPF over the region up through the Northeast; x<.25in for the most part.
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453. Zachary Labe
4:00 AM GMT on December 30, 2009
shipweather- Yea that was one of my worst busts on Wunderground, lol. Looking at the El Nino and a record negative AO and NAO, I feel extremely confident in at least one or maybe several more 6in or more events. Keep in mind December we average only 4.5in of snow in KMDT and is the least snowy month out of December, January, February, and March. Also positive SO climatology events support high snow anomalies for the months of February and March. We will do very well this winter.

TheDawnAwakening2- Perhaps downeast Maine and Cape Cod may do well, BL may be an issue, but looking at the 0z GFS I think this threat is rapidly dwindling.
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452. PalmyraPunishment
3:58 AM GMT on December 30, 2009
Quoting Blizzard92:

I hope the GFS shows a blizzard, radical mood swings are my favorite, lol.

sadist. haha
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451. TheDawnAwakening2
3:57 AM GMT on December 30, 2009
Blizzard while I think you have quite a valid point, and also the neutral PNA is on this side, but I think the sub tropical jet and the arctic jet will phase enough for a New England snowstorm, but this definitely is not a good sign. I also want to say that I have updated my blog on this storm and have a comparison to some extent with the New England Blizzard of 1978.
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450. shipweather
3:56 AM GMT on December 30, 2009
I remember that Jan.14-15th 2008 event. We had a pretty lame winter break without much snow, and I was trying to decide when to head back to Ship and you seemed pretty sure there would be good snow, so I went early. Within minutes of making it to Ship it was flurrying, but that was about it.....not 3-6".

Blizz, I am going to be honest I have a sinking feeling the 6" I saw in Kutztown and the 10" in Shippensburg are going to biggest single event of the winter.......
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449. Zachary Labe
3:54 AM GMT on December 30, 2009
Quoting PalmyraPunishment:
pretty safe to say that suicide watch is now in effect for the other sites. haha

I hope the GFS shows a blizzard, radical mood swings are my favorite, lol.
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448. PalmyraPunishment
3:51 AM GMT on December 30, 2009
pretty safe to say that suicide watch is now in effect for the other sites. haha
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447. Zachary Labe
3:16 AM GMT on December 30, 2009
Upon more analysis the 0z NAM is sort of like a revelation for me, lol. It encompases the idea that neither S/W is able to phase therefore causing a non-event. I find in past experiences these events typically end up pretty poor with two waves embedded in the flow with usually just some very light QPF. While I do not want to cancel this event prematurely, trends are unsettling. Here's to a dry arctic blast?!?

But I will add the NAM performed a stunt like this back on December 5th with a 'hiccup' run, and the 0z RGEM is coming in with a steeper trough and larger wavelength for the ridge across the western United States, so definitely all hope is not lost.

RGEM, which typically is similar to NAM, is radically different with the H5 chart of vortices of energy. The 0z NAM showed a piece of energy, another embedded shortwave, near the upper Plains allowing for flat troughing implications farther east. RGEM therefore eliminates this piece of energy allowing for more amplified mean flow. But RGEM does agree in slowing the southern stream's impacts similar to 0z NAM. So what does all of this mean??? Well basically models remain in confusion, but in general trends are not encouraging and the January 14-15, 2008 remains close in the back of my mind.

0z RGEM charts...


0z NAM...

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446. Zachary Labe
2:58 AM GMT on December 30, 2009
0z NAM correlates to a flat solution with a slow southern jet that never captures the low in the eastern periphery of the trough. This is a relatively new solution, and it is not pleasing looking at the subtropical jet. Little QPF is thrown back in the stratiform precipitation shield, or there lack of precipitation shield. Basically the low traverses harmlessly out to sea. Looking back at analogs this whole event reminds me of the January 14-15, 2008 non event. Several shortwaves were embedded in the mean flow with a weak disturbance across the Great Lakes allowing for a warm boundary layer across the east with H85 0C up to the Mason-Dixon line. Forecasts called for a low to undergo cyclogenesis slightly offshore especially towards New England with light snow accumulations in central to eastern Pennsylvania increasing to a moderate to heavy event in New England which basically turned out to a dull event with the southern stream too slow to allow for pressure falls of 3mb/2hr allowing for deepening of the low. Here is the surface map for January 14, 2008...Note the embedded shortwaves and general lack of moisture 700mb aloft...

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Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)

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