Tropical Storm Danny not impressive yet

By: Dr. Jeff Masters , 26. elokuuta 2009 klo 19:19 (GMT)

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Tropical Storm Danny is here, born from an African tropical wave that developed a closed circulation and some respectable heavy thunderstorm activity this morning. Data between 2 - 3 pm EDT from the Hurricane Hunters indicates the Danny has a central pressure of 1009 mb, and top surface winds of about 45 mph. Satellite imagery shows that Danny's circulation has gotten stretched and pulled away from the heaviest thunderstorm activity on the storm's east side. It is possible that Danny's center will reform at a different location, closer to the heaviest thunderstorms, so the model forecasts probably have a higher degree of uncertainty than usual at present. Wind shear has dropped to the low range, 5 - 10 knots. The upper-level low Danny is moving underneath has plenty of dry air in it, and this dry air is intruding into Danny's west side, keeping and heavy thunderstorm activity from developing on that side.


Figure 1. Oceanic heat content for August 25, 2009. Regions where the Sea Surface Temperature is below 80°F, or where the shallow waters of the Continental Shelf lie, do not have enough heat content to be plotted, and are shown in white colors. The oceanic heat content along the track of Tropical Storm Danny is below the threshold of 90 kJ/cm^2 typically seen with cases of rapid intensification. The storm position at 8am EDT today is given by the hurricane symbol with the "0" inside it. Subsequent hurricane symbols show the official NHC forecast points from the 11 am EDT forecast today, for 8am Thursday (24 hours), 8am Friday (48 hours), 8am Saturday (72 hours), and 8am Sunday (72 hours). The cold waters stirred up by Hurricane Bill last week will not impact Tropical Storm Danny. Image credit: RSMAS, University of Miami.

The forecast for Danny
As Danny continues to plow through the upper low, the low will weaken, but will dump dry air into the storm through Thursday afternoon, slowing down development. By Thursday night, when Danny should be several hundred miles off the coast of northern Florida, the upper-level low may be weak enough and far enough away that Danny will find itself in a region with light upper level anticyclonic winds, which would favor more rapid development. Ocean heat content (Figure 1) is high enough to support a hurricane, until Danny gets to about New Jersey's latitude. Most of the intensity models, including the GFDL, HWRF, and SHIPS model, forecast that Danny will become a hurricane by Friday. However, this favorable environment will not last long, since a strong trough of low pressure will be approaching the U.S. East Coast on Friday. This trough will bring high wind shear of 20 - 30 knots by Friday night. This trough should be strong enough to turn Danny to the north, then northeast on Saturday. The models have come into better agreement keeping Danny offshore as it passes North Carolina, though the storm is certainly capable of giving the Outer Banks a direct hit. As Danny passes North Carolina, it should start heading north-northeast, with a landfall likely Saturday afternoon or evening somewhere between Massachusetts and Nova Scotia. At that time, Danny is likely to be a strong tropical storm or weak Category 1 hurricane, with winds in the 55 - 80 mph range. The latest runs of the GFDL and GFS model have Danny tracking directly over Martha's Vineyard, where President Obama is on vacation. It will be interesting to see if the president stays on the island for Danny.

For those of you wondering about specific probabilities of getting tropical storm force or hurricane force winds, consult the NHC Wind Probability Product.


Figure 2. Tropical wave newly emerged from the coast of Africa, with some potential for development.

Elsewhere in the Atlantic
A well-organized tropical wave has exited the coast of Africa, and lies a few hundred miles southeast of the Cape Verdes Islands. None of the models are gung-ho about developing this wave, but shear is low, 10 knots, and waters are warm enough to support development. The dry Saharan Air Layer is relatively limited in extent and intensity, so dry air may have only a small inhibiting effect on the wave. Expect some slow development of this wave as it moves westward over the next few days. NHC is giving this system a low (less than 30% chance) of developing into a tropical depression by Friday afternoon.

I'll have an update Thursday.

Jeff Masters

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1351. juniort
27. elokuuta 2009 klo 19:22 (GMT)
I heard a meteorologist said today that 94l will not be problem for the lesser antilles at all as it will curve and go north long before it get near to the islands....any comments on this prediction
Member Since: 19.07.2009 Posts: 0 Comments: 69
1350. winter123
27. elokuuta 2009 klo 16:49 (GMT)
Quoting 69Viking:


Just looked at the visible with the tracking points and I certainly agree with you! Looks to be going almost due West with very little movement to the North currently.


Due west movement, if any. The COC is slowing down to try and allow the convection to move over. And the official forecast points START going NNW, but its drifting west... honestly they must not have eyes.
Member Since: 29.07.2006 Posts: 28 Comments: 1762
1349. 69Viking
27. elokuuta 2009 klo 16:34 (GMT)
Quoting VBbehr:
still moving west of the tropical points


Just looked at the visible with the tracking points and I certainly agree with you! Looks to be going almost due West with very little movement to the North currently.
Member Since: 25.08.2006 Posts: 1 Comments: 2996
1348. KEEPEROFTHEGATE (Mod)
27. elokuuta 2009 klo 16:10 (GMT)


2009 Storms
Active


Atlantic
94L.INVEST
05L.DANNY

East Pacific
12E.IGNACIO

Central Pacific
95C.INVEST
11E.HILDA

West Pacific
98W.INVEST
91W.INVEST
90W.INVEST

Indian Ocean

Southern Hemisphere


CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

1253 UTC THU AUG 27 2009



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL942009) 20090827 1200 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

090827 1200 090828 0000 090828 1200 090829 0000



LAT LON LAT LON LAT LON LAT LON

BAMS 10.5N 25.6W 11.3N 28.3W 12.1N 31.2W 12.9N 34.4W

BAMD 10.5N 25.6W 10.7N 28.1W 11.0N 30.6W 11.4N 33.0W

BAMM 10.5N 25.6W 11.0N 28.4W 11.3N 31.3W 11.6N 34.1W

LBAR 10.5N 25.6W 10.8N 28.6W 11.4N 31.9W 12.0N 35.4W

SHIP 25KTS 29KTS 36KTS 47KTS

DSHP 25KTS 29KTS 36KTS 47KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

090829 1200 090830 1200 090831 1200 090901 1200



LAT LON LAT LON LAT LON LAT LON

BAMS 13.3N 37.9W 13.4N 45.6W 13.3N 52.5W 13.4N 58.2W

BAMD 12.0N 35.3W 13.1N 39.0W 13.8N 41.8W 15.1N 44.1W

BAMM 12.0N 36.7W 12.8N 41.6W 12.9N 45.6W 12.7N 48.2W

LBAR 12.5N 38.9W 13.6N 45.3W 13.2N 44.6W 13.7N 46.3W

SHIP 58KTS 74KTS 76KTS 81KTS

DSHP 58KTS 74KTS 76KTS 81KTS



...INITIAL CONDITIONS...

LATCUR = 10.5N LONCUR = 25.6W DIRCUR = 270DEG SPDCUR = 15KT

LATM12 = 10.9N LONM12 = 22.6W DIRM12 = 263DEG SPDM12 = 15KT

LATM24 = 11.4N LONM24 = 19.5W

WNDCUR = 25KT RMAXWD = 0NM WNDM12 = 25KT

CENPRS = 1009MB OUTPRS = 1011MB OUTRAD = 200NM SDEPTH = D

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN
Member Since: 15.07.2006 Posts: 165 Comments: 52265
1347. VBbehr
27. elokuuta 2009 klo 15:32 (GMT)
I love talking to myself I will wait and see what happans w/Dman.
Member Since: 23.07.2008 Posts: 0 Comments: 12
1346. VBbehr
27. elokuuta 2009 klo 15:31 (GMT)
still moving west of the tropical points
Member Since: 23.07.2008 Posts: 0 Comments: 12
1345. VBbehr
27. elokuuta 2009 klo 15:19 (GMT)
East Coast Surf Championship is this weekend here in Va Beach. If Danny goes west,Very Bad, if east then well can REALLY have a good time
Member Since: 23.07.2008 Posts: 0 Comments: 12
1344. New2SOFLA
27. elokuuta 2009 klo 15:18 (GMT)
even if danny racks a little more left than expected hugging the coast since its pretty lopsided to the right coastal NJ and NYC should be spared the brunt of whatever danny kicks up? is that a somewhat safe assesment? any thoughts please....any storm headed this way makes me nervous but Danny doesnt seem too impressive yet which is good
1343. VBbehr
27. elokuuta 2009 klo 14:55 (GMT)
looking @ the last 2 frames of Danny (COC) it looks like it is moving west.NHC says its wobling nw i'm very confused
Member Since: 23.07.2008 Posts: 0 Comments: 12
1342. hydrus
27. elokuuta 2009 klo 14:29 (GMT)
Quoting caneluver:
A dirl devil is more impressive than Danny. What a joke of a storm.
lol..Danny is a cloud with a breeze next to it.just kidding.Who knows,if anything it is fairly large system.It could pull a fast one if conditions change quickly.
Member Since: 27.09.2007 Posts: 1 Comments: 19554
1341. stormygace
27. elokuuta 2009 klo 14:24 (GMT)
p451 - awesome graphics on 1227!! TY (I feel better now)
Member Since: 7.09.2005 Posts: 23 Comments: 1105
1340. tornadodude
27. elokuuta 2009 klo 14:15 (GMT)
Quoting ChrisCone:


i certainly don't agree with that. Dust devils don't have large areas of convection accompanying them ;) well I guess they CAN... but I see them more on sunny dry days. Of course, I am only being a kidder, I didn't really take this THAT literally.


haha good call :)
Member Since: 28.06.2006 Posts: 24 Comments: 8185
1339. ChrisCone
27. elokuuta 2009 klo 14:13 (GMT)
Quoting tornadodude:


while i agree with you right now, these type of statements could prove to be bad ha


i certainly don't agree with that. Dust devils don't have large areas of convection accompanying them ;) well I guess they CAN... but I see them more on sunny dry days. Of course, I am only being a kidder, I didn't really take this THAT literally.

edit - sorry, quoted the wrong person... meh ya'll know what i meant
1338. tornadodude
27. elokuuta 2009 klo 14:11 (GMT)
Quoting caneluver:
A dirl devil is more impressive than Danny. What a joke of a storm.


while i agree with you right now, these type of statements could prove to be bad ha
Member Since: 28.06.2006 Posts: 24 Comments: 8185
1337. jaxbeachbum
27. elokuuta 2009 klo 14:11 (GMT)
New Blog!
Member Since: 20.07.2007 Posts: 0 Comments: 41
1336. WXHam
27. elokuuta 2009 klo 14:07 (GMT)
Seems the COC just jerked to the west

Member Since: 1.07.2008 Posts: 0 Comments: 33
1335. MahFL
27. elokuuta 2009 klo 14:05 (GMT)
Danny going west atm anyone ?
Member Since: 9.06.2004 Posts: 0 Comments: 2906
1334. ChrisCone
27. elokuuta 2009 klo 14:05 (GMT)
Quoting tropicfreak:


More like a cat1.


agreed with Cat 1, for the meantime. It's kind of different though once you talk about New England. This area is extremely poorly prepared for even Cat 1 winds if they are sustained. And because of tons of excessive rainfall this year, and the last few years being flood years on rivers such as the Housatonic... many once-were dirt levies no longer exist and at the same time river levels, water table levels, and pretty much everything that has to do with moisture/water in general are way above normal. So if this thing were to strike, say... the middle of Long Island, it would only need to be a minimal tropical storm to cause hurricane like damage in terms of flooding... and it would only need to be a strong Cat 1 to cause Cat 2 like damage to property, and possibly more in terms of trees/power lines. Many homes up here are built to sustain nothing more than 90MPH winds. This is why up here when an F0 or F1 tornado hits, homes are destroyed as if it were an F3 (but the tornadoes up here are usually never bigger than a tenth of a mile wide, so wide spread damage from them is rare). That in itself is a good example of how poorly prepared this area really is for a wide spread hurricane force wind event. Also, a lot of hills so a lot of higher-elevation wind enhancement possible. I honestly believe if a large Cat 2 storm were to strike, somewhere like in my example the middle of Long Island and cut through CT - the damage would look more like a Cat 3 or 4. We have not had a Hurricane come up through in that way in decades. People bring up Hurricane Gloria, but honestly Gloria was only bad for the southeastern part of New England. I was little and living in Danbury at the time, which is only 60 or so miles west of where Gloria passed through and all we got was a 1 hour thunderstorm and the rest of the night was partly cloudy. I worry about this, because people think Gloria was a good example of the possible impacts when in reality it was a big "let down" for most of this area. The damage was great where it was greatest, but almost none existent elsewhere.
1333. hurricanejunky
27. elokuuta 2009 klo 14:02 (GMT)
Quoting CycloneOz:
The system that's freakin' me out right now is this 94L wave.

This one has a current track that is very disconcerting....and it looks like it wants to become a buzz-saw.


And it looks like it's coming off the coast of Africa moving WSW. I wonder how far down it'll go...
Member Since: 28.08.2006 Posts: 6 Comments: 2895
1332. Barbados
27. elokuuta 2009 klo 14:01 (GMT)
94L looking dangerous for us in the lesser antilles if these high pressure ridges build as expected.
Member Since: 9.08.2006 Posts: 0 Comments: 253
1331. ChrisCone
27. elokuuta 2009 klo 14:01 (GMT)
Quoting hurricanejunky:
Looking at those few frames on the visible it looks like the COC is starting to show itself again and the movement is more westward. Is anyone else noticing this or is it my untrained eyes?


we've noticed, all should keep a close eye on this trend - but it probably can not be determined yet if it is indicative of a longer term westerly track
1330. pearlandaggie
27. elokuuta 2009 klo 14:00 (GMT)
Member Since: 14.09.2007 Posts: 3 Comments: 3963
1329. tropicfreak
27. elokuuta 2009 klo 14:00 (GMT)
Quoting stormt:
Danny will be a force for new york and cape cod areas on saturday..Danny is getting his act together slowly the shear is supposed to lighten up so danny shoud take off and be approaching cat 2 status when he hits new york on saturday.stormt


More like a cat1.
Member Since: 2.09.2006 Posts: 110 Comments: 6814
1328. Orcasystems
27. elokuuta 2009 klo 14:00 (GMT)
new blog
Member Since: 1.10.2007 Posts: 81 Comments: 26493
1327. hurricanejunky
27. elokuuta 2009 klo 13:59 (GMT)
Quoting CycloneOz:


The NWS footage is awesome...like everything else!

Hey Junky! How about those frames I pulled from my video? Pretty cool, huh! Man, I busted my butt over there on that island nation! :)

Looking forward to receiving your DVD. Very important footage for the late winter series we're producing!

Oz---

Great lightning pic! So far I really like what you're turning out. The Experience Bill video should be a treat. Keep us posted!
Member Since: 28.08.2006 Posts: 6 Comments: 2895
1326. Goaskalice
27. elokuuta 2009 klo 13:59 (GMT)
You both gave me my giggle for the day! Thanks.
Very cool photo OZ

Quoting CycloneOz:


Grotto Bay is super swanky. A favorite haunt for British nobility and their mistresses! :)
Quoting ChrisCone:


at first I thought this said "Ghetto Bay" and I thought to myself "great, just what this world doesn't need.... more ghetto"
Member Since: 16.08.2009 Posts: 0 Comments: 41
1325. nrtiwlnvragn
27. elokuuta 2009 klo 13:59 (GMT)
Quoting P451:


LOL the highest winds they can find are 35kt flight level well east of the center?

Who upped this to a 55mph TS?

There's not even a 30mph surface wind within 200 miles of the LLC.....


That NOAA plane was flying at a much higher altitude (10,000-12,500 ft) than the USAF planes (1,500 ft) that have recently flown the system. Since it is not a well developed cyclone its winds don't extend upwards as high. However, if it has weakened we should see when the 18Z USAF plane flys.
Member Since: 23.09.2005 Posts: 13 Comments: 10466
1324. pearlandaggie
27. elokuuta 2009 klo 13:59 (GMT)
Member Since: 14.09.2007 Posts: 3 Comments: 3963
1323. pearlandaggie
27. elokuuta 2009 klo 13:58 (GMT)
Member Since: 14.09.2007 Posts: 3 Comments: 3963
1321. ChrisCone
27. elokuuta 2009 klo 13:57 (GMT)
Quoting P451:


LOL the highest winds they can find are 35kt flight level well east of the center?

Who upped this to a 55mph TS?

There's not even a 30mph surface wind within 200 miles of the LLC.....


definitely was a tropical storm at one point, and if this data is complete it is a big change from what they found the last couple times out. Wouldn't go critical on the NHC, they were correct for upgrading the storm. I would say this storm has been in a flip flop between sub-tropical and tropical the entire time, but imagine how much confusion it would cause if the NHC kept changing the classification? Plus computer models react different once you classify a storm as tropical or change it to sub-tropical/non-tropical. That is part of the importance of correctly classifying a storm once it IS tropical, or something close to it - because these kinds of changes are progged into the models and has an, at times, dramatic effect on their predictions.
1320. CycloneOz
27. elokuuta 2009 klo 13:56 (GMT)
The system that's freakin' me out right now is this 94L wave.

This one has a current track that is very disconcerting....and it looks like it wants to become a buzz-saw.
Member Since: 26.08.2006 Posts: 10 Comments: 3420
1319. Orcasystems
27. elokuuta 2009 klo 13:56 (GMT)


Looks like someone has faith in 94L
Member Since: 1.10.2007 Posts: 81 Comments: 26493
1318. Grothar
27. elokuuta 2009 klo 13:57 (GMT)
Quoting ackee:
HOW COMES 94lL was made an invest when the NHC has it a low chance of development ?


If you notice, the forecasts are normally based on 48 hour increments. It does not say that after 48 hours it could have a better chance of developing further. The experts have long ago decided on a more cautious approach, lest people panic too quickly and when a systems fizzles, people have a tendency to become complacent. Years ago the airports would close 2 to 3 days before an approaching storm; only to have the systems move away. They no longer do that. They declare an invest when a system has enough potential to become a threat. I hope this answer helps.
Member Since: 17.07.2009 Posts: 63 Comments: 23726
1317. TheCaneWhisperer
27. elokuuta 2009 klo 13:55 (GMT)
Quoting DestinJeff:


holy crap, you're right. i have included the link for others. that swirl looks almost due south of TFP #2 (far south of it)

Here is the link



Steering flow for a weak naked swirl is WNW.
1316. hurricanejunky
27. elokuuta 2009 klo 13:55 (GMT)
Looking at those few frames on the visible it looks like the COC is starting to show itself again and the movement is more westward. Is anyone else noticing this or is it my untrained eyes?
Member Since: 28.08.2006 Posts: 6 Comments: 2895
1314. CycloneOz
27. elokuuta 2009 klo 13:55 (GMT)
Danny is a naked swirl. He's gonna have to do better than that!
Member Since: 26.08.2006 Posts: 10 Comments: 3420
1313. TheCaneWhisperer
27. elokuuta 2009 klo 13:54 (GMT)
Quoting ackee:
94L has form well south we in the CARRB need keep good eye on this one


The pattern potentially taking shape is one that would increase the risk to the Caribbean, SE coast & GOM. Troughing has been the recurring dominant feature so I am a little skeptical of the ridging building in and breaking the current pattern. I'll believe it when I see it, basically, stay tuned.
1311. CycloneOz
27. elokuuta 2009 klo 13:54 (GMT)
Quoting hurricanejunky:


Glad you were able to make that trip worthwhile. Can't wait to see footage. I haven't looked at the Key West footage yet. How did the NWS footage turn out?


The NWS footage is awesome...like everything else!

Hey Junky! How about those frames I pulled from my video? Pretty cool, huh! Man, I busted my butt over there on that island nation! :)

Looking forward to receiving your DVD. Very important footage for the late winter series we're producing!

Oz---
Member Since: 26.08.2006 Posts: 10 Comments: 3420
1310. pearlandaggie
27. elokuuta 2009 klo 13:53 (GMT)
Member Since: 14.09.2007 Posts: 3 Comments: 3963
1309. K8eCane
27. elokuuta 2009 klo 13:53 (GMT)
Quoting ackee:
94L has form well south we in the CARRB need keep good eye on this one


i have always known plus the doctor has told me that my right eye is my good one so i'll compromise and keep my good eye on 94L and my left eye on Danny
sorry thats the best i can do as the other way around would be difficult
Member Since: 26.04.2006 Posts: 5 Comments: 3041
1308. Orcasystems
27. elokuuta 2009 klo 13:52 (GMT)
Quoting P451:


LOL the highest winds they can find are 35kt flight level well east of the center?

Who upped this to a 55mph TS?

There's not even a 30mph surface wind within 200 miles of the LLC.....


They also had to shift the centre to the NNE when they first got out there.. and even then.. its not much of a system.
Member Since: 1.10.2007 Posts: 81 Comments: 26493
1307. Elena85Vet
27. elokuuta 2009 klo 13:52 (GMT)
Quoting largeeyes:
So why does it leave the convection behind?


The storms ability to organize is being disrupted by it's surrounding environment.
Member Since: 18.08.2008 Posts: 0 Comments: 619
1306. pearlandaggie
27. elokuuta 2009 klo 13:52 (GMT)
Member Since: 14.09.2007 Posts: 3 Comments: 3963
1305. VAbeachhurricanes
27. elokuuta 2009 klo 13:52 (GMT)
Member Since: 6.09.2007 Posts: 0 Comments: 5695
1304. Orcasystems
27. elokuuta 2009 klo 13:51 (GMT)
Blog Update
Reflector site for those at work, which includes Weather456, daily update.


AOI

AOI

AOI

AOI
Member Since: 1.10.2007 Posts: 81 Comments: 26493
1303. pearlandaggie
27. elokuuta 2009 klo 13:51 (GMT)
Member Since: 14.09.2007 Posts: 3 Comments: 3963
1302. hurricanejunky
27. elokuuta 2009 klo 13:51 (GMT)
Quoting CycloneOz:


It is a great shot! :) "Epic" is exactly what I shouted when I got to work on this particular tape! :)

When I intercept, it's not fun and games...I work very hard. For this hurricane, I worked for 26-hours straight!


Glad you were able to make that trip worthwhile. Can't wait to see footage. I haven't looked at the Key West footage yet. How did the NWS footage turn out?
Member Since: 28.08.2006 Posts: 6 Comments: 2895

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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