Tropical Depression Two forms from Invest 98L

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

Share this Blog
0
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 625 - 575

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25Blog Index

625. 19N81W
3:22 AM GMT on July 18, 2011
wow bret looks impressive!....really?
Member Since: August 24, 2008 Posts: 0 Comments: 418
624. Chucktown
3:22 AM GMT on July 18, 2011
Quoting AllStar17:


I'm not arguing that but the projected path always can shift left or right a good distance. The main point is that the US coast should keep watching in case.


Even if there is a shift in the track, all the moisture is going to be on the right side of Bret. There is a tremendous amount of dry air and subsidence over the SE US, so this is not going to be an issue for anyone.
Member Since: August 27, 2006 Posts: 0 Comments: 1769
623. ProgressivePulse
3:21 AM GMT on July 18, 2011
Quoting AllStar17:
A reminder that things change:
Hurricane Ernesto initial projected path:


Actual track:


All due respect however, if you look at the actual path to the SE Cuba coast, Ernesto was on the extreme right side of that initial cone.
Member Since: August 19, 2005 Posts: 5 Comments: 5449
622. SouthDadeFish
3:20 AM GMT on July 18, 2011
Quoting philliesrock:
I don't see why some people think Bret will come up the coast. There's nothing allowing it to do that.
If the ridge over the central US isn't as strong as forecast or moves slower than forecast, Bret would move closer to the coast.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
621. AllStar17
3:19 AM GMT on July 18, 2011
Quoting SouthDadeFish:
I completely agree. The GFDL and HWRF may be onto something.


Yes and the NHC mentioned them but discounted them as of now.

" THE LATEST HWRF AND GFDL MODEL
FORECASTS SHOW A MORE NORTH-NORTHEASTWARD MOTION WITH A TRACK MUCH
CLOSER TO THE UNITED STATES THAN THE USUALLY RELIABLE ECMWF AND GFS
MODELS. THIS SCENARIO APPEARS UNLIKELY DUE TO THE STRENGTH OF THE
MID- TO UPPER-LEVEL RIDGE FORECAST OVER THE CENTRAL UNITED STATES.
FOR NOW...THE OFFICIAL FORECAST PLACES MORE WEIGHT ON THE GLOBAL
MODELS AND IS VERY SIMILAR TO THE PREVIOUS NHC TRACK."
Member Since: June 29, 2009 Posts: 13 Comments: 5313
620. coastaltugcaptain
3:18 AM GMT on July 18, 2011
Quoting 1911maker:
space shuttle cockpit 360


Link



That's awesome! My kids will love this.
Member Since: October 8, 2007 Posts: 0 Comments: 6
619. SouthDadeFish
3:18 AM GMT on July 18, 2011
Quoting AllStar17:


I'm not arguing that but the projected path always can shift left or right a good distance. The main point is that the US coast should keep watching in case.
I completely agree. The GFDL and HWRF may be onto something.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
618. extreme236
3:17 AM GMT on July 18, 2011
Quoting BahaHurican:
Wow... extreme236! Great to see u! Bret's likely to have a good night, given his location, but maybe not so good otherwise...

I'm off now, but looking to see more of u as the season progresses...


Good to see you too! And yeah the ragged ones tend to pull surprises so we could see a more impressive storm in the morning. I hope to try to spend some more time on here when I get the chance, but have a good one!
Member Since: August 2, 2007 Posts: 19 Comments: 19234
617. AllStar17
3:15 AM GMT on July 18, 2011
Quoting SouthDadeFish:
All the dynamical models unanimously forecast Bret to move NE. I think the real issue is how close he will come to the North Carolina coast.


I'm not arguing that but the projected path always can shift left or right a good distance. The main point is that the US coast should keep watching in case.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
616. philliesrock
3:15 AM GMT on July 18, 2011
I don't see why some people think Bret will come up the coast. There's nothing allowing it to do that.
Member Since: June 29, 2006 Posts: 65 Comments: 3197
615. wolftribe2009
3:14 AM GMT on July 18, 2011
Quoting AllStar17:
A reminder that things change:
Hurricane Ernesto initial projected path:


Actual track:


you should have shown Hurricane Jeanee of 2004 "She did that loopy thing"

People thought she was going out towards sea too.
Member Since: July 22, 2010 Posts: 6 Comments: 752
614. BahaHurican
3:14 AM GMT on July 18, 2011
Quoting extreme236:
Hey everybody! I've been busy so it's been a while since I've posted. Been lurking for a while though. I see Bret's looking pretty ragged. It's gonna need a good night, thats for sure.
Wow... extreme236! Great to see u! Bret's likely to have a good night, given his location, but maybe not so good otherwise...

I'm off now, but looking to see more of u as the season progresses...
Member Since: October 25, 2005 Posts: 19 Comments: 22302
613. SouthDadeFish
3:14 AM GMT on July 18, 2011
Quoting AllStar17:
A reminder that things change:
Hurricane Ernesto initial projected path:


Actual track:
All the dynamical models unanimously forecast Bret to move NE. I think the real issue is how close he will come to the North Carolina coast.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
612. weathermanwannabe
3:13 AM GMT on July 18, 2011
Interesting discussion language from this particular NHC forecaster: PEAK FLIGHT-LEVEL WINDS OF 43-45 KT WERE RECORDED ALONG WITH A FEW BELIEVABLE SFMR
SURFACE WINDS JUST ABOVE TROPICAL STORM FORCE. BASED ON THESE OBSERVATIONS AND THE DEVELOPMENT OF NEW CONVECTION JUST NORTHEAST OF THE CENTER AROUND 0000 UTC...THE DEPRESSION WAS UPGRADED TO A TROPICAL STORM AT THAT TIME
. Justifying the techinal requirements for calling the TS I but never thought they would use the term "believable"; makes you think there was a little bit of debate over there as to the call.
Member Since: August 8, 2006 Posts: 0 Comments: 9205
611. SouthDadeFish
3:12 AM GMT on July 18, 2011
Quoting extreme236:
Hey everybody! I've been busy so it's been a while since I've posted. Been lurking for a while though. I see Bret's looking pretty ragged. It's gonna need a good night, thats for sure.
Hey extreme! good to have you here. I agree, pretty ragged indeed. Needs a burst over the center to get the intensification process started.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
610. BahaHurican
3:11 AM GMT on July 18, 2011
Anyway, I'm pretty much gone for now. If I wake up, I'll look in at 2 a.m. Otherwise I'll see u guys in the a.m. and hopefully over a cup of coffee and not a hastily brewing TS... lol

night all...

Member Since: October 25, 2005 Posts: 19 Comments: 22302
609. CaicosRetiredSailor
3:11 AM GMT on July 18, 2011
Member Since: July 12, 2007 Posts: 0 Comments: 6048
608. coastaltugcaptain
3:11 AM GMT on July 18, 2011
A 2300 update as promised. I will have the baro looked at in port.

Time: 2300
Position: 29 10.00 N 80 54.47 W
4 nm ESE Daytona Beach, FL.

Course: 159 True
Speed: 6.8 Knots

Seas: 4’ – 5’
Wind: ESE 15 – 20
Baro: Malfunctioning
Member Since: October 8, 2007 Posts: 0 Comments: 6
607. AllStar17
3:10 AM GMT on July 18, 2011
A reminder that things change:
Hurricane Ernesto initial projected path:


Actual track:
Member Since: June 29, 2009 Posts: 13 Comments: 5313
606. 1911maker
3:10 AM GMT on July 18, 2011
space shuttle cockpit 360


Link
Member Since: February 25, 2011 Posts: 0 Comments: 474
605. extreme236
3:10 AM GMT on July 18, 2011
Hey everybody! I've been busy so it's been a while since I've posted. Been lurking for a while though. I see Bret's looking pretty ragged. It's gonna need a good night, thats for sure.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
604. RukusBoondocks
3:09 AM GMT on July 18, 2011
None of the reliable models predict tropical cyclone development over the remainder of the Atlantic through July 23.


oops I guess Bret didnt count
Member Since: February 13, 2011 Posts: 0 Comments: 294
603. stillwaiting
3:08 AM GMT on July 18, 2011
the most likely path imo opinion is xrtp thru 6hrs,then a path simular to the lbar..
Member Since: October 5, 2007 Posts: 20 Comments: 4970
602. BahaHurican
3:08 AM GMT on July 18, 2011
Plus it's 11 p.m. on Sunday night. Pple the NHC would call are likely asleep right now... lol

Hey, it's a small place. lol
Member Since: October 25, 2005 Posts: 19 Comments: 22302
601. KEEPEROFTHEGATE (Mod)
3:07 AM GMT on July 18, 2011
Member Since: July 15, 2006 Posts: 173 Comments: 54268
Member Since: August 2, 2010 Posts: 21 Comments: 9821
The moisture over S Fl has reached out and touched Bret...

Member Since: August 13, 2007 Posts: 0 Comments: 655
Quoting HurrikanEB:


Was wondering the same thing. According to the 11PM advisory TS winds are only about 60 miles off the coast. Still pretty close despite it's forward speed. Though at its current strength I doubt a watch/warning would make much difference for any of the islands, especially with the anticipated northward movement.
I don't think NHC expects for TS sustained winds to get far enough south to make a difference. The COC is pretty much over the northern Cays of Abaco, from what I can tell [looking @ the radar more so than the satellite] but the worst winds still seem to be to the NE of that. Unless the centre drops down south of Grand Bahama [west of Abaco] I don't see much difference between a watch and a warning for those guys...
Member Since: October 25, 2005 Posts: 19 Comments: 22302
Quoting wolftribe2009:
Poor New Orleans/Mississippi (Loop shows it's POSSIBLE direction)

Link

"Cindy might be back for Revenge"

Link

Any nervous nellie in LA/Miss ignore this. There ain't nothing coming our way, real or in theory.
Member Since: Posts: Comments:
Member Since: August 2, 2010 Posts: 21 Comments: 9821
573 hcubed "And you do know what the term [expletive deleted] means, right?

Due to the religio-machismo of the Cubans who made the twist on its origins, it's quite a bit ruder than the usual translations imply.
Member Since: Posts: Comments:
Quoting FLdewey:
MUDDER!

Don't be a stranger my man.


lol...ok..I might have a few more F5's in me.
Member Since: Posts: Comments:
As of the last observation at 02:55:00Z, the plane's...

Direction of Travel: E (90°)
Location: 25 miles (40 km) to the ESE (123°) from Mobile, AL, USA.

well on the way!
Member Since: Posts: Comments:
Check out the dry air diving in towards Bret. He may really have a hard time fighting it off unless more convection develops over the center very soon.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
590. xcool
AllStar17 - YA
Member Since: Posts: Comments:
Quoting ackee:
if bret continue to move south why is the NW Bahamas under a watch and not a warning
Any upgrade to warnings would be @ 11 p.m.... which, incidently, is only a few minutes from now. Also, at the time when the watch was issued, Bret's threat to the Bahamas seemed less. Besides, TS warning / watch are only different in that watch is "possible" and warning is "likely". Unless Bret gets 60 mph sustained overnight, it shouldn't be a problem.
Member Since: October 25, 2005 Posts: 19 Comments: 22302
The National Hurricane Center track is very much on the right side of this model guidance.

Member Since: June 29, 2009 Posts: 13 Comments: 5313
Hey MiamiHurricanes09 long time no see.

Its going to be interesting to see when Bret commence that NE movement.
Member Since: Posts: Comments:
Quoting xcool:


I see a due south motion there.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Checking on Bret before bedtime. I don't think he's one I'll pull an all-nighter for...hehehe
Member Since: Posts: Comments:
583. xcool
Member Since: Posts: Comments:
Quoting ackee:
if bret continue to move south why is the NW Bahamas under a watch and not a warning


Was wondering the same thing. According to the 11PM advisory TS winds are only about 60 miles off the coast. Still pretty close despite it's forward speed. Though at its current strength I doubt a watch/warning would make much difference for any of the islands, especially with the anticipated northward movement.
Member Since: Posts: Comments:
Quoting HurricaneHunterJoe:
Since the models missed on Bret forming, why so much emphasis on the model forecast track? With all the model input and the now closed low system, make them all that much more reliable?
They didn't really miss the storm. All models were indicating a potential system coming from a trough split at some point in time.

In the last day or so they backed off on this idea, so I guess that is "missing" the system. But its not a full blown miss, there was definitely clear indication from the models that we would have to watch the trough as it stalled over the region.
Member Since: August 24, 2010 Posts: 19 Comments: 4358
Time: 02:44:00Z
Coordinates: 30.4667N 88.6W
Acft. Static Air Press: 555.6 mb (~ 16.41 inHg)
Acft. Geopotential Hgt: 5,088 meters (~ 16,693 feet)
Extrap. Sfc. Press: -
D-value: -
Flt. Lvl. Wind (30s): From 135° at 20 knots (From the SE at ~ 23.0 mph)
Air Temp: -0.4°C* (~ 31.3°F*)
Dew Pt: -*
Peak (10s) Flt. Lvl. Wind: 21 knots (~ 24.1 mph)
SFMR Peak (10s) Sfc. Wind: -
SFMR Rain Rate: -
(*) Denotes suspect data

Mission 2 in the air. should be an interesting one!
Member Since: Posts: Comments:
Poor New Orleans/Mississippi (Loop shows it's POSSIBLE direction)

Link

"Cindy might be back for Revenge"

Link

Member Since: July 22, 2010 Posts: 6 Comments: 752
Per the latest NHC forecast Bret should start moving NNE tomorrow morning.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
000
WTNT42 KNHC 180238
TCDAT2

TROPICAL STORM BRET DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL022011
1100 PM EDT SUN JUL 17 2011


THE AIR FORCE HURRICANE HUNTER AIRCRAFT MADE TWO ADDITIONAL PASSES
THROUGH THE CENTER OF THE TROPICAL CYCLONE AFTER THE RELEASE OF THE
2100 UTC NHC ADVISORY. DURING THOSE PASSES...PEAK FLIGHT-LEVEL
WINDS OF 43-45 KT WERE RECORDED ALONG WITH A FEW BELIEVABLE SFMR
SURFACE WINDS JUST ABOVE TROPICAL STORM FORCE. BASED ON THESE
OBSERVATIONS AND THE DEVELOPMENT OF NEW CONVECTION JUST NORTHEAST
OF THE CENTER AROUND 0000 UTC...THE DEPRESSION WAS UPGRADED TO A
TROPICAL STORM AT THAT TIME. MICROWAVE AND SATELLITE IMAGERY SHOW
THAT MOST OF THE ASSOCIATED DEEP CONVECTION IS LOCATED OVER THE
EASTERN SEMICIRCLE OF THE CIRCULATION DUE TO MODERATE WESTERLY
SHEAR. THE SHEAR IS FORECAST TO DECREASE SLIGHTLY DURING THE NEXT
12-24 HOURS...WHICH SHOULD ALLOW AN OPPORTUNITY FOR SOME
STRENGTHENING. THE NHC INTENSITY FORECAST IS IN GOOD AGREEMENT
WITH THE SHIPS/LGEM GUIDANCE AND SHOWS PEAK INTENSITY OCCURRING
BETWEEN 24-36 HOURS. WEAKENING IS INDICATED BEYOND 36 HOURS WHEN
THE GLOBAL MODELS PREDICT AN INCREASE IN UPPER-LEVEL NORTHEASTERLY
WINDS OVER THE CYCLONE.

BRET HAS BEEN DRIFTING EASTWARD DURING THE PAST FEW HOURS...BUT A
LONGER-TERM MOTION YIELDS 145/2. THE TROPICAL STORM IS NOT
FORECAST TO MOVE VERY MUCH DURING THE NEXT 12-18 HOURS AS IT
REMAINS IN AN AREA OF WEAK STEERING CURRENTS. IN 24-36 HOURS...THE
RIDGE TO THE SOUTHEAST OF BRET IS FORECAST TO STRENGTHEN WHICH
SHOULD PRODUCE A NORTHEASTWARD MOTION. AS BRET GAINS LATITUDE IN
2-3 DAYS...IT SHOULD ACCELERATE EAST-NORTHEASTWARD WITHIN AN AREA
OF DEEP-LAYER WESTERLY FLOW. THE LATEST HWRF AND GFDL MODEL
FORECASTS SHOW A MORE NORTH-NORTHEASTWARD MOTION WITH A TRACK MUCH
CLOSER TO THE UNITED STATES THAN THE USUALLY RELIABLE ECMWF AND GFS
MODELS. THIS SCENARIO APPEARS UNLIKELY DUE TO THE STRENGTH OF THE
MID- TO UPPER-LEVEL RIDGE FORECAST OVER THE CENTRAL UNITED STATES.
FOR NOW...THE OFFICIAL FORECAST PLACES MORE WEIGHT ON THE GLOBAL
MODELS AND IS VERY SIMILAR TO THE PREVIOUS NHC TRACK.

FORECAST POSITIONS AND MAX WINDS

INIT 18/0300Z 27.5N 78.0W 35 KT 40 MPH
12H 18/1200Z 27.7N 77.9W 40 KT 45 MPH
24H 19/0000Z 28.5N 77.4W 50 KT 60 MPH
36H 19/1200Z 29.7N 76.7W 50 KT 60 MPH
48H 20/0000Z 30.7N 75.5W 45 KT 50 MPH
72H 21/0000Z 32.5N 71.5W 40 KT 45 MPH
96H 22/0000Z 34.5N 65.5W 35 KT 40 MPH
120H 23/0000Z 36.5N 58.5W 30 KT 35 MPH

$$
FORECASTER BROWN/BERG
Member Since: Posts: Comments:
Quoting FLdewey:
Now that's just creepy


What's creepy is ever since you mentioned it I keep seeing cashews too....
Member Since: August 13, 2007 Posts: 0 Comments: 655

Viewing: 625 - 575

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25Blog Index

Top of Page

About

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

Local Weather

Mostly Cloudy
53 °F
Mostly Cloudy