Invest 95L Brushes Louisiana Coastline
Hi all,
Dr. Rob Carver, filling in for Jeff this week.
Midnight CDT Update
The low known as Invest 95L stopped it's northward progression and is now moving west along the Louisiana coastline. This is the oddest mesoscale convective complex/tropical feature I've seen in awhile. It's still producing a lot of rain, 2+ inches inland and 6+ inches over the ocean.
Base reflectivity from Lake Charles, LA at 11PM July 5 showing a very nice comma head. Animated loop.
Invest 95L is making landfall now in southern Louisiana near Terrebonne Bay. A CMAN station in Terrebonne Bay is currently reporting winds from the SE at 21 mph and the pressure is 1009 mb. Looking at the radar data, Invest 95L never had convection around the center of circulation. Also, it was hard to see a distinct surface circulation in the different analyses available. I believe soaking rains for southern Lousisana are going to be Invest 95L's main legacy. It's already produced 5+ inches of rain in some offshore locations according to radar-derived rainfall estimates.
Fig. 1 Meteogram for TRBL1 in Terrebonne Bay, LA. Tabular data are here.
Fig. 2 Base reflectivity from New Orleans, LA at 706PM, July 5. Animated loop.
Invest 96L
430 AM Update
In sum, the 00Z model runs don't present a different picture. It is curious to note that the Canadian Global model does not intensify 96L at all in the 00Z run, while NOGAPS has shifted towards a SE Louisiana landfall. I think the following discussion is still valid.
96L is going to be an interesting feature to forecast. It's still on the edge of a strong wind shear gradient. 40+ knots of shear are on the NE side of 96L, and <10 knots are on the SW side. The "center" of 96L is under about 15 knots of shear. This is likely inhibiting 96L. Nearly all forecast models take 96L NW through the Yucatan peninsula and into the Gulf of Mexico. Near the Yucatan itself, sea-surface temperatures are relatively cool, not the best environment for intensification. However, at 25N, 87W there is a hotspot of SST's, which would promote rapid intensification. However, there's currently 20 knots of shear over the hotspot, so the thunderstorms that do form as a result will be well ventilated, and not cause 96L to intensify.
The dynamical models have different takes on how 96L intensifies in the next 120 hours. The 18Z operational GFS strongly intensifies 96L over the hotspot and takes 96L towards Grand Isle, LA. The parallel (for testing model configuration changes) GFS has a similar track, but does not strengthen 96L as much. This indicates uncertainty on how the models are handling the upper-level winds.
The 18Z HWRF solution is much like the parallel GFS solution. The 12Z Canadian global model has a more westerly track, pushing 96L towards Port Arthur, but it strengthens 96L right before it makes landfall, not when it's over open water. NOGAPS takes the "a little from column A, a little from column B" approach, with a spinup over the hotspot (op. GFS solution), but a westerly landfall (the Canadian solution). More data to initialize the models from synoptic reconnaissance flights will help reduce uncertainty.
The bottom line, 96L will move into the Gulf of Mexico and is then shrouded by the mists of uncertainty. I also think that it's a possibility (>50%) that it will become a tropical cyclone sometime in the next 48-72 hours (leaning towards sometime in day 2-3 based on the model runs.)
Fig. 3 Plot of maximum winds (mph) for the next 120 hours from the 18Z July 5 GFS model run.Parallel GFS version.
Fig. 4 Plot of maximum winds (mph) for the next 120 hours from the 18Z July 5 HWRF model run.
Fig. 5 Plot of maximum winds (mph) for the next 120 hours from the 12Z July 5 CMC global model run.NOGAPS wind swath.
Next update
I'll probably tweak this blog later tonight as new model runs come in. I'll have a full update tomorrow afternoon (Pacific time).
Reader Comments
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The mid-level low over the Yucatan is the more dominant feature and unless something changes, it will win.
Transmitted: 6th day of the month at 21:53Z
Aircraft: Gulfstream IV-SP (G-IV) (Reg. Num. N49RF)
Mission: Non-Tasked Mission, possibly not tropical (flight in the North Atlantic basin)
Mission Identifier: Al96 (Probably storm name and mission number)
Observation Number: 15
The Yucatan Vortex is Toast..the energy is now focusing mid GOM
It has a chance but not too great of one. The mid-level low over the Yucatan, if it can work down to the surface, would be the one to develop, but it will be moving over the cold-water wake of Alex which will limit development.
Not at all. Vorticity maps show a continued decrease in vorticity in the northern part of the trof and an increase in the vort over the Yucatan.
The TCHP is back..and warmer.
EA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
347 PM CDT TUE JUL 6 2010
.DISCUSSION...
MAIN REGIONAL ITEMS OF NOTE INCLUDE THE UPPER LOW EAST OF THE
LOWER TX COAST...THE SURFACE LOW ON THE SABINE JUST SOUTH OF
KSHV...AN UPPER RIDGE OVER N TX AND THE BIG BEND...AND THE
TROPICAL WAVE OVER THE SE GULF AND W CARIBBEAN.
THE MODELS AGREE IN KEEPING THE SURFACE LOW NORTH OF THE FORECAST
AREA TONIGHT. THE UPPER RIDGE REMAINS FAIRLY STATIONARY THROUGH
FRIDAY. THE UPPER LOW WILL DRIFT INTO THE LOWER RIO GRANDE TONIGHT
AND WEDNESDAY AND WILL HELP SET UP A DEEP EASTERLY FLOW. THIS WILL
HELP STEER THE MOISTURE FROM THE TROPICAL WAVE OVER SE TX SOMETIME
ON WEDNESDAY. BOTH THE NAM AND GFS SET UP A COASTAL TROUGH BY
WEDNESDAY NIGHT. WITH THE ARRIVAL OF PW/S BETWEEN 2.5 AND 2.8
INCHES...THE HEAVIEST RAINFALL POTENTIAL LOOKS TO BE FROM
WEDNESDAY NIGHT INTO THURSDAY. AS THERE IS STILL SOME UNCERTAINTY
ON THE TIMING...DECIDED TO WAIT UNTIL THE MIDNIGHT SHIFT BEFORE
ISSUING A WATCH. WILL INSERT HEAVY RAINFALL POSSIBLE FOR LOCATIONS
HAVING LIKELY AND ABOVE POPS WEDNESDAY THROUGH THURSDAY.
wow very interisting a trough and a tropical wave together
and our African AOI nice look at wind barbs
Its gonna take another 24 to shake out seems.
The NHC will follow the Southern one till its apparent tha Mid Gulf one is dominate.
They dont trend well to er,..the Obvious sometimes.
96L
So whats new..?
pfffth
(first time posting, but have lurked since 2005)
You might wanna look at all the maps. The wake is recovering slowly but is far from gone. The cold wakes from major hurricanes can pose a limiting factor on other tropical systems for 2-3 weeks after being created. The heat content does come back but it takes a while.
and no forecasted low forming
Hi Homeless...
Said that earlier, whatever happens, just get the moisture out of here......please
Taz your sense of humor makes me scratch my head sometimes. XD
LOL!
Transmitted: 6th day of the month at 22:05Z
Aircraft: Gulfstream IV-SP (G-IV) (Reg. Num. N49RF)
Mission: Non-Tasked Mission, possibly not tropical (flight in the North Atlantic basin)
Mission Identifier: Al96 (Probably storm name and mission number)
Observation Number: 16
Try again.
Been watching this one too. There is vorticity east of Bermuda. Give it a day or 2 to percolate.
Who has the better chance of winning this battle... I have seen the mid level win in the past, when it was located over warm waters... In this case I will lean towards the central GOM surface circulation winning.
Time will tell.
Hey Reed, which GOM circ. are you referring to? Don't see it.
Welcome to the fray...
Feel free to jump in anytime .
Yeah a nice drop in progress there. This is in the central gulf in the vicinity of 96L's surface center.
Stealing some blob. In previous years we've had blob, blobette, bloob, etc.
Perhaps this year we should consider a new term.
How about glob....on account of the ongoing oil calamity.
That GOM low your seeing is *probably* the former LLC of 96L that basically said "screw you" and went racing off to the TX/LA border.
He's probably lurking and waiting.
Conditions at 42001 as of
(4:50 pm CDT)
2150 GMT on 07/06/2010:
Unit of Measure: Time Zone:
Click on the graph icon in the table below to see a time series plot of the last five days of that observation.
5-day plot - Wind Direction Wind Direction (WDIR): SSE ( 150 deg true )
5-day plot - Wind Speed Wind Speed (WSPD): 17.5 kts
5-day plot - Wind Gust Wind Gust (GST): 19.4 kts
5-day plot - Wave Height Wave Height (WVHT): 5.6 ft
5-day plot - Dominant Wave Period Dominant Wave Period (DPD): 8 sec
5-day plot - Average Period Average Period (APD): 5.6 sec
5-day plot - Atmospheric Pressure Atmospheric Pressure (PRES): 29.75 in
5-day plot - Pressure Tendency Pressure Tendency (PTDY): -0.08 in ( Falling )
5-day plot - Air Temperature Air Temperature (ATMP): 80.1 °F
5-day plot - Water Temperature Water Temperature (WTMP): 84.6 °F
5-day plot - Dew Point Dew Point (DEWP): 75.0 °F
5-day plot - Heat Index Heat Index (HEAT): 85.1 °F
It's not a low, but I do see a circulation south of LA. Patrap pointed it out earlier and I do see it as well.
Likewise, but someone throwing out bouy info has got it together....
You make a good point, but one thing you forget is that the convection associated with the Central GOM is under 20-30kts of shear because of the upper level anticyclone which is almost directly over the center of the circulation over the Yucatan. That is what will end up giving the Yucatan circulation the advantage. It is starting to make its way back over water now.
Exactly what it is.. never died, just went off into the wild blue yonder.
Viewing: 1851 - 1901
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