Tropical Depression Two forms from Invest 98L

By: Dr. Jeff Masters , 9:33 PM GMT on July 17, 2011

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Tropical Depression Two (TD2) formed from Invest 98L this afternoon. Hurricane Hunters flew into the suspect area and found a surface circulation north of the Bahamas, with maximum sustained winds of 35 mph. They also determined the system had become warm core—a characteristic that must be present in order to declare a tropical cyclone. Satellite imagery continues to show the system is becoming more organized with a stronger circulation. Wind shear is forecast to remain favorable for the system until Tuesday or Wednesday when higher shear will slide in from the north. Sea surface temperatures are warm enough to sustain a tropical storm.


Figure 1. Satellite imagery of Tropical Depression Two in the Atlantic, east of Florida. This graphic will update to the current satellite imagery.


Figure 2. Official 5-day forecast for Tropical Depression Two. This graphic will remain current.

Forecast for TD2

The models are coming into better agreement as TD2 has become more organized. In terms of dynamical forecast models, the HWRF and GFS both forecast TD2 to max out just above tropical storm strenth. HWRF intensifies TD2 to around 47 mph in the next 24 hours, whereas GFS is a bit slower to bring the system up to tropical storm status. Two statistical models, the DSHP (SHIPS model that includes land interaction) and the LGEM (Logistical Growth Equation Model) both intensify TD2 to a moderate tropical storm over the next 2-3 days.

There tends to be a lot of uncertainty involved with tropical cyclones that form under these circumstances, but our forecast remains in line with the National Hurricane Center and the reliable forecast models. TD2 will move slowly to the northeast in weak steering currents over the next few days before eventually becoming an extratropical storm. There is minimal chance that this system will cross over Florida into the Gulf of Mexico. Timing and path depend heavily on how intense the cyclone gets, as Jeff mentioned in his blog earlier today. A weaker storm will tend to stay south, whereas a stronger storm will grow taller in the atmosphere and winds at higher levels will influence it and steer it northeast.

None of the reliable models predict tropical cyclone development over the remainder of the Atlantic through July 23.

Angela

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Quoting ackee:
I know we all focusing on Bret But any thoughts on ECMWF run that show TD#3 OR possble a TS

Yup, I still doubt that would be our first hurricane.
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Good morning all.

Well, the thunder woke me up about 5 minutes ago... lol

Looks like Bret's been growing, as expected, with the approach to Dmax... I be a few Bahamians out there who haven't been following the wx are going to be so SURPRISED.... :o)




Only thing I want to add for now is... thank goodness for shear and dry air!

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973. ackee
I know we all focusing on Bret But any thoughts on ECMWF run that show TD#3 OR possble a TS
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937 Skyepony "Yay~anger & persistence pays off..you don't have to pay for this stuff even though the universities have given it to companies to sell back to us.. Ha ha despite it all my model races are back :)
Scaled this back to the last 12hr model error since Bret is so young. So who's in the lead?
GFDN out front with a ~8nm error, slight lead over AEMN & AP01 (~10). AVNO, HWRF & NGP2 chasing with ~14/15. Unfortunately I got nothing on how the BAM models are doing.. NAM is doing better than usual with ~21, rest of the majors are trailing GFDL 33, CMC & NGPS 45.
"

THANKS for the brainwork. I'm too ignorant of the workings to even begin the legwork.
Sharing your aggravation about government-funded research being sold for pennies to private companies -- or for less than nothing when speaking of publication in science journals -- then resold for many many many dollars, I'm always especially gladdened when folks break those attempts at monopolizing the public Commons, whether by individuals like yourself or by the few publishers who believe that "The truth should be free."
Member Since: August 21, 2007 Posts: 0 Comments: 4860
...BRET CENTERED JUST NORTHWEST OF GREAT ABACO ISLAND...EXPECTED TO BEGIN MOVING NORTH-NORTHEASTWARD LATER TODAY...
5:00 AM EDT Mon Jul 18
Location: 27.2°N 77.7°W
Max sustained: 50 mph
Moving: E at 3 mph
Min pressure: 1001 mb
Member Since: July 8, 2005 Posts: 259 Comments: 24579
Before I hit the hay, the ECMWF (for the last few runs), GFS, and CMC are all hinting at something developing out of the African wave train.

Of course, at this point development is not a guarantee, but divergence and shear should be low thanks to some ridging aloft. Also, plenty of moisture and convergence as the monsoon trough extends out to about 40w right now. In several days, the upper level conditions over the wave will deteriorate a bit as it nears the Caribbean/lesser Antilles. This is because it will encounter the TUTT which will increase shear.

Anyway, something to keep in mind, aside from Bret. It looks like this will be the area with the best chance of development over the next week. None of the models hint at anything else over the next week.
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Evening kori
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Quoting Vincent4989:
Poll: How do you feel when it is announced that the name "Arlene" would be retired?
A. Finally! I am tired of this name!
B. NOOOOOOOOO!!!!! THE RECORD! THE RECORD!
C. zzzzzz.......

I pick B, honestly.


B
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Quoting scott39:
Bret looks pitiful!


It looked even worse earlier. Believe it or not, it's actually on a slight strengthening trend.
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Bret looks pitiful!
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Quoting JLPR2:
Well I'm off to bed too, 4am O.o


Bret is tiny and seems to be making that turn to the NE.
agreed, nice catch there on the radar.

im off to bed as well, night all
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963. JLPR2
Well I'm off to bed too, 4am O.o


Bret is tiny and seems to be making that turn to the NE.
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Poll: How do you feel when it is announced that the name "Arlene" would be retired?
A. Finally! I am tired of this name!
B. NOOOOOOOOO!!!!! THE RECORD! THE RECORD!
C. zzzzzz.......

I pick B, honestly.
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Quoting mrsalagranny:
Well off to work I go have a bleesed day Miami and Jason.Thanks for all the info Miami.You are a very smart young man.Keep up the good work.God Bless.
Thank you. Have a great day.
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Quoting mrsalagranny:
Thanks Miami.You are right anything is possible.I feel I am correct in saying that this season will be much different from last year.Can you tell me if we are gonna have all the troughs or ridging that we had last year?My gut feeling tells me we are in for quiet a few surprises this year.
I doubt that this year's tracks mimic last year's. The synoptic pattern of ridging over the eastern United States and troughing over the western United States and north Atlantic are very similar of that of season's that had several hurricane landfalls over the U.S mainland.
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Well off to work I go have a bleesed day Miami and Jason.Thanks for all the info Miami.You are a very smart young man.Keep up the good work.God Bless.
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Quoting MiamiHurricanes09:
Yup, still here lol. Bret was definitely a surprise, to be honest I really didn't think it posed a threat to develop into a tropical cyclone, but sure enough it develops into Bret lol.

The system has definitely been strengthening at a steady pace (approximately 1mb an hour) based on the latest data from Recon. Environmental conditions appear to be relatively favorable with the warm waters of the Gulf stream below it and anticyclogenesis taking place aloft. The only detriment appears to be the lack of mid-level moisture. Nevertheless, I do think that Bret has a decent chance of achieving category 1 status before environmental conditions deteriorate as the system races into a weakness currently being made by the subtropical ridge and an upper-level ridge over the United States (which should be reinforced by a shortwave over eastern Canada).

A second scenario would be that the system intensifies into a category 2/3 hurricane, and comes under the clockwise steering of the U.S ridge, which would then bring the system westward. The chances of this scenario occurring are very slim at the moment since it is unlikely that the system intensifies into the aforementioned strength. Unfortunately, anything is possible.
Thanks Miami.You are right anything is possible.I feel I am correct in saying that this season will be much different from last year.Can you tell me if we are gonna have all the troughs or ridging that we had last year?My gut feeling tells me we are in for quiet a few surprises this year.
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Quoting mrsalagranny:
Miami are you still with us?What is your take on Bret?
Yup, still here lol. Bret was definitely a surprise, to be honest I really didn't think it posed a threat to develop into a tropical cyclone, but sure enough it develops into Bret lol.

The system has definitely been strengthening at a steady pace (approximately 1mb an hour) based on the latest data from Recon. Environmental conditions appear to be relatively favorable with the warm waters of the Gulf stream below it and anticyclogenesis taking place aloft. The only detriment appears to be the lack of mid-level moisture. Nevertheless, I do think that Bret has a decent chance of achieving category 1 status before environmental conditions deteriorate as the system races into a weakness currently being made by the subtropical ridge and an upper-level ridge over the United States (which should be reinforced by a shortwave over eastern Canada).

A second scenario would be that the system intensifies into a category 2/3 hurricane, and comes under the clockwise steering of the U.S ridge, which would then bring the system westward. The chances of this scenario occurring are very slim at the moment since it is unlikely that the system intensifies into the aforementioned strength. Unfortunately, anything is possible.
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Miami are you still with us?What is your take on Bret?
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Quoting jasonweatherman2011:
watch the end here u see a new storm by the end of next week!!
jason may I have the link please?
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Was curious whether any tropical storm force winds are occurring in the Bahamas. According to Wunderground, the Elbow Cay Abaco station reported a wind speed of 48.3 mph at 12:23 am and winds have been mostly between 25-40 mph for the last several hours.
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949. Skyepony (Mod)
Quoting cchsweatherman:
Well its time for me to get some sleep. Past 3 AM here. lol


Me too.

I'm about to get a bit of rain from Bret. Low clouds, lit somewhat red from Melbourne's lights, flying in with the occasional cloud to ground lightning strike.
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Good early morning everyone.I see we have t\TS Bret now.Boy that ne caught us all off guard.Where is Bret expected to go? TIA
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Bret was a cool surprise. I have a feeling this August and September are going to be real busy. The pot seems to be just coming to a boil.
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Well its time for me to get some sleep. Past 3 AM here. lol
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Quoting MiamiHurricanes09:
The NHC must of had the position incorrectly. Based on vortex messages, it's been moving just slightly south of due east.


My mistake. lol
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Quoting cchsweatherman:


Corrected. Thanks. lol


No problem haha
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Quoting VAbeachhurricanes:


east?


Corrected. Thanks. lol
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Quoting cchsweatherman:


In comparison to the 2AM advisory data, the storm seems to have moved to the west some.


east?
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Quoting MiamiHurricanes09:
000
URNT12 KNHC 180700
VORTEX DATA MESSAGE AL982011
A. 18/06:37:30Z
B. 27 deg 07 min N
077 deg 48 min W
C. 850 mb 1448 m
D. 45 kt
E. 334 deg 7 nm
F. 101 deg 46 kt
G. 003 deg 11 nm
H. 1001 mb
I. 15 C / 1466 m
J. 22 C / 1462 m
K. NA / NA
L. NA
M. NA
N. 12345 / 8
O. 0.02 / 5 nm
P. AF308 0202A BRET OB 08
MAX FL WIND 52 KT SE QUAD 05:16:00Z
Curvature North and East. Heavy rain inbound from NE.
;


In comparison to the 2AM advisory data, the storm seems to have moved to the east some.
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937. Skyepony (Mod)
Yay~anger & persistence pays off..you don't have to pay for this stuff even though the universities have given it to companies to sell back to us.. Ha ha despite it all my model races are back:)


Scaled this back to the last 12hr model error since Bret is so young. So who's in the lead?

GFDN out front with a ~8nm error, slight lead over AEMN & AP01 (~10). AVNO, HWRF & NGP2 chasing with ~14/15. Unfortunately I got nothing on how the BAM models are doing.. NAM is doing better than usual with ~21, rest of the majors are trailing GFDL 33, CMC & NGPS 45.
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I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 15°C (59°F) at a pressure alt. of 1,466m (4,810ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 22°C (72°F) at a pressure alt. of 1,462m (4,797ft)

Very strange for a weak TS...
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Quoting MiamiHurricanes09:
Ahhh, I remember Bonnie. Didn't stay up late for that one, just remember waking up really early lol. I'm sure I'll be doing a bunch of all-nighters this season with the more intense ones. Even though Bert isn't "a strong one" he just interests me lol.


Of course, especially with it being so close to home. I still think that Florida needs to keep a good eye on this storm since I'm not so sure about the weakness really coming in.
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000
URNT12 KNHC 180700
VORTEX DATA MESSAGE AL982011
A. 18/06:37:30Z
B. 27 deg 07 min N
077 deg 48 min W
C. 850 mb 1448 m
D. 45 kt
E. 334 deg 7 nm
F. 101 deg 46 kt
G. 003 deg 11 nm
H. 1001 mb
I. 15 C / 1466 m
J. 22 C / 1462 m
K. NA / NA
L. NA
M. NA
N. 12345 / 8
O. 0.02 / 5 nm
P. AF308 0202A BRET OB 08
MAX FL WIND 52 KT SE QUAD 05:16:00Z
Curvature North and East. Heavy rain inbound from NE.
;
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Quoting cchsweatherman:


I remember staying up through the night and into the late morning for Tropical Storm Bonnie when it came through our area last year. Screwed up my sleep cycle for weeks. lol
Ahhh, I remember Bonnie. Didn't stay up late for that one, just remember waking up really early lol. I'm sure I'll be doing a bunch of all-nighters this season with the more intense ones. Even though Bert isn't "a strong one" he just interests me lol.
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932. JRRP
Quoting Matt74:
Post 882 jrrp
I am on my blackberry and can't really make that out on my screen. What does it show? Thanks

euro 00z
is showing a strong tropical wave or tropical depression (i do not know) near PR
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Quoting MiamiHurricanes09:
Good night. I'll probably be up until the 5a.m update, lol.


I remember staying up through the night and into the late morning for Tropical Storm Bonnie when it came through our area last year. Screwed up my sleep cycle for weeks. lol
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929. JRRP
Quoting JLPR2:


El CMC muestra un pedazo de energía desprendiendose de la parte superior del disturbio y no el disturbio como tal, por eso lo pasa tan al norte.

Seems that I'll have a disturbance in my area just in time to ruin a long weekend. -.-

creo que hay que prestarle bastante atencion a esa onda
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1001mb, good call
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Quoting SouthDadeFish:
I think we're all saying the same thing just in a different way. I'm assuming there is no way in heck this thing makes it to cat 3. But I guess there is a small chance for everything.
Quoting MiamiHurricanes09:
I completely agree. Do I think it's likely that it will reach category 2 status? No. Is it possible? Certainly.
oh alright, so we are agreeing then lol

Yea, I don't think it will reach that intensity either. Maybe cat 1, but a major hurricane is extremely unlikely.
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Quoting SouthDadeFish:
1001mb... Goodnight everyone.


my eyes are crossing too, goodnite
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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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