Danielle a hurricane; TD 7 forming off coast of Africa
Hurricane Danielle has stopped intensifying and is now looking a bit ragged this morning, but remains a respectable Category 1 hurricane with 80 mph winds. The intensity of Danielle's heavy thunderstorms has waned in the past few hours, and the organization of the storm is less impressive. This is probably due do strong upper-level winds out of the west that are creating a moderate 10 - 20 knots of wind shear, and injecting some of the dry air from the Saharan Air Layer (SAL) that surrounds Danielle. Danielle is over warm 28°C water, but is far from any land areas.
Figure 1. Morning satellite image of Tropical Storm Danielle (left side of image) and the forming Tropical Depression Seven (right side of image.)
Forecast for Danielle
A powerful trough of low pressure over the mid-Atlantic Ocean will begin to pull Danielle more to the northwest by Wednesday, keeping Danielle well to the east of Bermuda. Most of the models predict that this trough will be strong enough to fully recurve Danielle out to sea. It is possible that Danielle could eventually threaten Newfoundland, Canada, but it currently does not appear that any other land areas will be at risk from this storm. History suggests that a storm in Danielle's current location has only a 20% chance of making landfall on the U.S. East Coast. If Danielle passes east of Bermuda, as forecast, these percentages drop to less than 5%. As far as intensity goes, it is looking unlikely that Danielle will attain major hurricane status (115+ mph winds.) There is enough dry air and wind shear affecting the storm today that it will take several days for the storm to recover its strength, making it less likely the storm can hit Category 3.
The formation of Danielle is remarkable in this it was successfully forecast by the GFS model nearly two weeks in advance. The ECMWF and NOGAPS models also did a good job of predicting Danielle's formation a week in advance. The models are getting better and better each year at forecasting genesis of tropical cyclones, though a successful 1-week forecast of genesis is still a rarity. For example, none of the models foresaw the development of 96L until just 3 - 4 days ago.
Figure 2. Plot showing historically the percent chance of a tropical cyclone in a given location impacting the U.S. East Coast. For storms in Danielle's current position (orange hurricane symbol), about 20% of them go on to hit the U.S. East Coast. For storms in 96L's current location (red circle with a "?" in it), the odds are also 20%. Image credit: Bob Hart, Florida State University.
96L (soon to be Tropical Depression Seven)
Satellite images suggests that a tropical wave (96L) that emerged off the coast of Africa yesterday morning has developed a closed circulation, low-level spiral bands, and an increasing amount of heavy thunderstorms. While this morning's ASCAT pass does not show a clear closed circulation, satellite estimates of 96L's strength support calling this a 30 mph tropical depression. It is likely that this storm will be designated Tropical Depression Seven later today. 96L is already bringing heavy rain and strong, gusty winds to the southern Cape Verde Islands. Winds were sustained at 26 mph at Mindelo in the northwest Cape Verde Islands this morning, and 24 mph at Praia, the station closest to the center of 96L. Both stations were reporting widespread dust, due to strong winds blowing Saharan dust from the coast of Africa. However, water vapor satellite images show that only a modest amount of dry air is accompanying this dust, and dry air is currently not a major detriment to 96L. Wind shear is about 10 - 20 knots, and sea surface temperatures are warm, 28°C.
Forecast for 96L/Tropical Depression Seven
Wind shear is predicted to remain low, 5 - 10 knots, for the next four days. SSTs will cool a bit to 27°C by Thursday, but this is still above the 26.5°C threshold for hurricane development. Dry air will probably be the main inhibiting factor for 96L. Most of the intensity forecast models bring 96L to hurricane strength by four days from now, and this is a reasonable forecast. 96L should become Tropical Storm Earl later today or on Wednesday, and will probably bring sustained winds of 40 mph to the southernmost Cape Verdes Islands tonight and Wednesday.
The long range fate of 96L remains unclear. The storm is being steering by the same ridge of high pressure steering Danielle, and will initially follow a track similar to Danielle. 96L may encounter the cold waters stirred up by Danielle at times this week, inhibiting development. As 96L approaches the central Atlantic five days from now, the storm will encounter the same mid-Atlantic trough that will be steering Danielle, and 96L should turn more to the northwest. It is unclear at this point whether this trough will be strong enough to fully recurve 96L out to sea, east of Bermuda. This will, in part, depend upon how strong Danielle gets. A stronger Danielle is likely to create more of a break in the ridge of high pressure steering 96L, encouraging the storm to turn north and recurve out to sea. A weaker Danielle will make 96L more likely to miss recurvature, and follow a track to the west or west-northwest towards the U.S. East Coast early next week. History suggests that a storm in 96L's current location has only a 20% chance of making landfall on the U.S. East Coast.
When will the Caribbean and Gulf of Mexico get active?
The large scale atmospheric circulation over the Caribbean and Gulf of Mexico currently features relatively dry, stable, sinking air. This is due, in part, to the Madden-Julian oscillation (MJO). The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. The latest MJO forecast from the GFS model calls for the wet phase of the MJO to move into the Caribbean during the first week of September. However, keep in mind that forecasts of MJO activity 1 - 2 weeks in advance are not very skillful. The GFS model forecast of MJO activity made two weeks ago did fairly well for the first week, but poorly for the second week of the forecast.
Tropical Storm Frank spares Mexico
Over in the Eastern Pacific, Tropical Storm Frank has moved away the coast far enough from the Mexican coast to no longer pose a heavy rainfall threat, and all tropical storm warnings have been dropped.
"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. I'll focus on Danielle, Earl, and Frank, and discuss the possibilities of a hyperactive Atlantic hurricane period coming during the first week of September.
Today's show will be 30 - 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.
Jeff Masters
Reader Comments
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Winds 25.8 MPH from the SSW, Water Level 3.3 above MLLW and wave height 3-5 feet.
Happy surfing in the morning!
True...that gap could close up faster than the models are showing. Right now Danielle looks like she is getting smacked once again and i wouldn't be surprised if she gets downgraded today. I don't think she is going to get that strong imo
LATCUR = 18.5N LONCUR = 50.3W DIRCUR = 295DEG SPDCUR = 15KT
LATM12 = 17.1N LONM12 = 47.5W DIRM12 = 300DEG SPDM12 = 17KT
LATM24 = 15.7N LONM24 = 44.1W
WNDCUR = 75KT RMAXWD = 20NM WNDM12 = 65KT
CENPRS = 982MB OUTPRS = 1010MB OUTRAD = 240NM SDEPTH = D
RD34NE = 120NM RD34SE = 90NM RD34SW = 60NM RD34NW = 90NM
See if it remains, Berg went lower than a previous output yesterday.
RGB LOOP
Would you bang away at DMAX, thus keeping the cyclone from gaining too much strength, keeping in mind you want it to have some strength so that it tries its best to move poleward and go out to sea (if it's a CV cyclone)?
I know that's how I'd do it, leaving the NHC and Dr. Masters to wonder how a perfectly good eyewall, ala Monday, just collapsed as it did, and why once again Danielle seems to be failing overnight, when one could assume it should be getting stronger, perhaps.
There isn't a tropical cyclone that hasn't followed this pattern this year, btw, and the only good excuse is that they've been "monsoonal", and thus too big to ever "wrap their arms in".
Not saying that's the case for sure, mind you, but nothing in the past few years has proved this theory wrong, when one takes into account our not caring about Mexico, Bermuda, or Newfoundland so very much, really.
5:00 AM AST Wed Aug 25
Location: 18.8°N 51.0°W
Max sustained: 85 mph
Moving: WNW at 17 mph
Min pressure: 982 mb
What What What??
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010
0900 UTC WED AUG 25 2010
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.
HURRICANE CENTER LOCATED NEAR 18.8N 51.0W AT 25/0900Z
POSITION ACCURATE WITHIN 25 NM
PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 300 DEGREES AT 15 KT
ESTIMATED MINIMUM CENTRAL PRESSURE 982 MB
MAX SUSTAINED WINDS 75 KT WITH GUSTS TO 90 KT.
64 KT....... 25NE 15SE 10SW 25NW.
50 KT....... 60NE 45SE 30SW 45NW.
34 KT.......120NE 90SE 60SW 90NW.
12 FT SEAS..210NE 120SE 75SW 150NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.
REPEAT...CENTER LOCATED NEAR 18.8N 51.0W AT 25/0900Z
AT 25/0600Z CENTER WAS LOCATED NEAR 18.5N 50.3W
FORECAST VALID 25/1800Z 20.1N 52.7W
MAX WIND 70 KT...GUSTS 85 KT.
64 KT... 30NE 25SE 15SW 25NW.
50 KT... 60NE 45SE 30SW 45NW.
34 KT...120NE 90SE 60SW 105NW.
FORECAST VALID 26/0600Z 21.8N 54.5W
MAX WIND 70 KT...GUSTS 85 KT.
64 KT... 30NE 25SE 15SW 25NW.
50 KT... 60NE 45SE 30SW 45NW.
34 KT...120NE 90SE 60SW 105NW.
FORECAST VALID 26/1800Z 23.3N 56.3W
MAX WIND 75 KT...GUSTS 90 KT.
64 KT... 40NE 35SE 25SW 35NW.
50 KT... 75NE 60SE 45SW 60NW.
34 KT...135NE 120SE 90SW 105NW.
FORECAST VALID 27/0600Z 24.5N 58.0W
MAX WIND 80 KT...GUSTS 100 KT.
50 KT... 75NE 60SE 60SW 60NW.
34 KT...135NE 120SE 90SW 120NW.
FORECAST VALID 28/0600Z 27.0N 61.0W
MAX WIND 90 KT...GUSTS 110 KT.
50 KT... 90NE 75SE 60SW 75NW.
34 KT...150NE 135SE 105SW 135NW.
EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 200 NM
ON DAY 4 AND 250 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY
OUTLOOK VALID 29/0600Z 30.0N 62.0W
MAX WIND 95 KT...GUSTS 115 KT.
OUTLOOK VALID 30/0600Z 33.0N 62.0W
MAX WIND 85 KT...GUSTS 105 KT.
REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 18.8N 51.0W
NEXT ADVISORY AT 25/1500Z
$$
FORECASTER PASCH
Good morning!
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010
500 AM AST WED AUG 25 2010
ALTHOUGH THE CLOUD PATTERN OF THE HURRICANE HAS NOT BECOME MUCH
BETTER ORGANIZED ON GEOSTATIONARY IMAGERY...AN AMSR-E PASS FROM
0516 UTC SUGGESTS AN EYE WITH FAIRLY WELL-DEFINED INNER CORE
CONVECTIVE BANDING ON THE 37-GHZ CHANNEL. CIRRUS-LEVEL OUTFLOW IS
BECOMING A LITTLE BETTER DEFINED TO THE NORTHWEST. USING A BLEND
OF DVORAK CURRENT INTENSITY ESTIMATES FROM TAFB AND SAB...THE
ADVISORY INTENSITY IS SET TO 70 KT. AN UPPER-LEVEL CYCLONE TO THE
NORTH-NORTHWEST OF THE HURRICANE HAS BEEN IMPARTING MODERATE
WEST-SOUTHWESTERLY SHEAR ON DANIELLE. GLOBAL MODEL GUIDANCE
INDICATES THAT THIS UPPER-LEVEL CYCLONE SHOULD MOVE SOUTHWEST OVER
THE NEXT 24 TO 48 HOURS. THIS EVOLUTION WOULD CAUSE THE SHEAR TO
WEAKEN AND BECOME MORE SOUTHERLY OR EVEN SOUTHEASTERLY. BOTH OF
THESE ENVIRONMENTAL FACTORS SHOULD BE MORE CONDUCIVE FOR
STRENGTHENING. NEAR THE END OF THE FORECAST PERIOD...DYNAMICAL
GUIDANCE SHOWS A SIGNIFICANT INCREASE IN SHEAR SO THE HURRICANE
WILL PROBABLY BE ON A WEAKENING TREND BY DAY 5. THE OFFICIAL
INTENSITY FORECAST IS CLOSE TO THE NUMERICAL INTENSITY CONSENSUS.
THERE HAS BEEN A GRADUAL DECREASE IN FORWARD SPEED AND THE INITIAL
MOTION IS NOW ESTIMATED TO BE ABOUT 300/15. A TURN TOWARD THE
NORTHWEST IS LIKELY TO OCCUR VERY SOON IN RESPONSE TO A WEAKNESS IN
THE SUBTROPICAL RIDGE TO THE NORTH OF DANIEL. A SHORT WAVE
MID-TROPOSPHERIC RIDGE WILL BE PASSING TO THE NORTH OF THE
HURRICANE IN A COUPLE OF DAYS. THIS WOULD TEMPORARILY HALT A
FURTHER TURN TO THE RIGHT...UNTIL THE RIDGE MOVES FARTHER EAST.
LATER ON...A MORE NORTHWARD MOTION IS LIKELY AS DANIELLE MOVES
AROUND THE WESTERN PERIPHERY OF THE RIDGE AND IS INFLUENCED BY A
TROUGH MOVING OFF THE NORTHEAST U.S. COAST. THE OFFICIAL TRACK
FORECAST IS QUITE CLOSE TO THE DYNAMICAL MODEL CONSENSUS. IT
SHOULD BE NOTED THAT THE LATEST ECMWF FORECAST IS AN OUTLIER...
SHOWING A SHARPER TURN TO THE RIGHT THAN MOST OF THE MODELS...AND
IS SIGNIFICANTLY FASTER THAN THE OTHER TRACK GUIDANCE. IT WILL BE
INTERESTING TO SEE IF THAT MODEL TURNS OUT TO BE CORRECT.
FORECAST POSITIONS AND MAX WINDS
INITIAL 25/0900Z 18.8N 51.0W 75 KT
12HR VT 25/1800Z 20.1N 52.7W 70 KT
24HR VT 26/0600Z 21.8N 54.5W 70 KT
36HR VT 26/1800Z 23.3N 56.3W 75 KT
48HR VT 27/0600Z 24.5N 58.0W 80 KT
72HR VT 28/0600Z 27.0N 61.0W 90 KT
96HR VT 29/0600Z 30.0N 62.0W 95 KT
120HR VT 30/0600Z 33.0N 62.0W 85 KT
$$
FORECASTER PASCH
GUIDANCE SHOWS A SIGNIFICANT INCREASE IN SHEAR SO THE HURRICANE
WILL PROBABLY BE ON A WEAKENING TREND BY DAY 5. THE OFFICIAL
INTENSITY FORECAST IS CLOSE TO THE NUMERICAL INTENSITY CONSENSUS.
Bermuda Triangle works again?
Good morning.
I know it isn't much but my local forecast is calling for lows of 69, 66 and 67 this coming Saturday night...Sunday night and Monday night.
Highs 88-90 Friday through Tuesday.
Fall is getting closer.
You missed an amazing reaction on this board to the results of the GFS 18z run late yesterday. Whew, it was both weird and wild!! LOL
I saw the GFS run....what was said?
Your lows are higher than my highs!
Next few days...
Highs of 62, 57, 62, 59, 59.
Lows of 51, 48, 48, 50, 46.
A high of 52 yesterday.
Oh, and lows of barely 40 coming.. even a 39.
It has been truly hot the last few weeks and I will take everything I can get right now!
Those temps sound nice, if it's sunny.
Maybe in 5-6 weeks it will really start cooling off some. It's been hot here the last 2 days. Highs in the upper 90's.
Is it just me or is this been the wierdest tropical season??
Ike, are you up by Crestivew?
Defuniak Springs.
SYNOPSIS FOR THE GULF OF MEXICO
430 AM CDT WED AUG 25 2010
.SYNOPSIS...TROUGH FROM NEAR FLORIDA PANHANDLE TO S TEXAS WILL
DRIFT W AND EXTEND FROM MOBILE BAY TO 24N94W WED NIGHT THEN
MOVE ACROSS THE WESTERN GULF THROUGH THU NIGHT AND APPROACH THE
TEXAS COAST FRI AND MOVE INLAND LATE FRI INTO SAT. HIGH PRES
WILL BUILD SW ACROSS AREA BEHIND THE TROUGH LATE FRI THROUGH SUN.
Now to put it into comparison:
The smallest county in Florida is around 250sq miles (Union Co.). Smallest in Texas is Rockwall County with around 150sq miles. The smallest parish in Louisiana is somewhere between the two.
Bermuda is one of the smallest islands (countries) in the world. It is just over 20 sq miles.
And the GFS wants to hit it twice. Dead on. In a row.
If that transpired, that's really what you call unlucky.
OK, Defuniak ... that explains the better nite temps. I'm in Gulf Breeze - not even forcast below 76 this weekend.
amazingly unlucky!!
Tropical Cyclone Advisory #15
TROPICAL CYCLONE FRANK (EP092010)
9:00 AM UTC August 25 2010
================================
SUBJECT: "FRANK" Strengthens A Little And Moves Further Away From The Southwestern Coast Of Mexico
At 9:00 AM UTC, Tropical Storm Frank (991 hPa) located at 16.2N 103.6W or 175 NM south southeast of Manzanillo, Mexico has sustained winds of 60 knots with gusts of 75 knots. The cyclone is reported as moving west northwest at 8 knots.
Storm Force Winds
================
60 NM from the center
Forecast and Intensity
=========================
24 HRS: 17.1N 106.8W - 65 knots (SVR Tropical Cyclone SSHS-1)
48 HRS: 18.3N 110.3W - 60 knots (Tropical Cyclone)
72 HRS: 19.5N 112.5W - 55 knots (Tropical Cyclone)
20.0ºN 103.0ºE - 25 knots 1004 hPa
"Wheres all the downcasters now??!!!!! over and over again.....
"Look, LOL it slams into new england as a major!!! LOL!!!!!
"Storm was right all along"!!!!!!!
"OMG their all going to be driven west to the CONUS!!!!"
Anyway, these were some of the main guys making some pretty unscientific comments..LOL...if I could describe it it would be a bunch of guys in a room who jumped up and down and began to hug one another as the GFS results were announced!!!! Whew!!!
Every season I think has their own 'weird' qualities.
If it wasn't, hardly be any need for forecasters.
Same for models, if they were always correct, nobody would need forecasters.
The downcasters WILL be silenced. You say that like they won't.
Or wait, maybe you're right. You probably ARE.
I hope they're correct. That would get the dew points into the 60's.
LOL.
No comment beyond the LOL.
Was like a great touchdown pass to win the game.....lots of hype.....and of course.....going to blow NEW YORK away...lol
Amen Brother!!
from the previous heading of 9.5degrees north of NorthNorthWest.
24Aug - 09amGMT - 15.9n44.6w - - 100mph . _ . 973mb - NHC.Adv.11
24Aug - 12pmGMT - 16.1n45.8w - - 75knots . . . . 983mb - NHC-ATCF
24Aug - 03pmGMT - 16.6n46.5w - - 80mph . . . . . 985mb - NHC.Adv.12
24Aug - 06pmGMT - 17.1n47.5w - - 65knots . . . . 990mb - NHC-ATCF
H.Danielle becomes TS.Danielle
24Aug - 09pmGMT - 17.5n48.2w - - 70mph . . . . . 993mb - NHC.Adv.13
25Aug - 12amGMT - 17.9n49.1w - - 65knots . . . . 990mb - NHC-ATCF
TS.Danielle becomes H.Danielle again
25Aug - 03amGMT - 18.2n49.8w - - 75mph . . . . . 990mb - NHC.Adv.14
25Aug - 06amGMT - 18.5n50.3w - - 75knots . . . . 990mb - NHC-ATCF
25Aug - 09pmGMT - 18.8n51.0w - - 85mph . . . . . 982mb - NHC.Adv.15
_ _ _ ~65.2knots=75mph _ _ _ 75knots=~86.3mph _ _ _ ~73.9knots=85mph
NHC rounds windspeeds to the nearest 5mph or to the nearest 5knots
Copy&paste 16.6n46.5w, 17.1n47.5w, 17.5n48.2w-17.9n49.1w, 17.9n49.1w-18.2n49.8w, 18.2n49.8w-18.5n50.3w, 18.5n50.3w-18.8n51.0w, bda, jax into the GreatCircleMapper for a look at the last 12hours.
Viewing: 2651 - 2701
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