Tropical Depression Three forms

By: Dr. Jeff Masters , 3:42 PM GMT on July 22, 2010

Share this Blog
1
+

Tropical Depression Three has formed over the Bahama Islands, and appears poised to become Tropical Storm Bonnie later today. Satellite images of TD 3 show a modest area of heavy thunderstorms that have slowly increased in intensity and areal coverage this morning. The surface circulation center is exposed to view, thanks to strong upper-level winds out of the southwest that are creating about 20 knots of wind shear. This wind shear is due to the counter-clockwise circulation of air around a large upper-level low pressure system over Florida that is moving west at about the same speed TD 3 is. Water vapor satellite loops show a large area of dry air is associated with the upper-level low pressure system, and this dry air is hindering development of TD 3. The storm is attempting to wrap a curved band of clouds around its center, on its west side. If TD 3 is able to do this, the center will be protected from shear and dry air, and more significant strengthening can occur. Surface observations in the Bahamas and several nearby ships have shown top winds in TD 3 of up to 35 mph, so the storm is close to the 40 mph winds needed to be classified as a tropical storm.


Figure 1. Water vapor satellite image showing dry air (brown colors) associated with the upper-level low over Florida. Image credit: NOAA/NESDIS.

Track Forecast for TD 3
The storm is in a fairly straightforward steering current environment, and TD 3 should progress steadily to the west to west-northwest through Saturday. This will bring the storm ashore over the Florida Keys or South Florida on Friday, and into the Gulf of Mexico on Saturday. The latest set of model runs from 2am EDT (6Z) had the advantage of having data from a flight of the NOAA jet last night, so we have higher confidence than usual in the track of TD 3 over the next two days. The location of TD 3's final landfall along the Gulf of Mexico coast has the usual uncertainties for 3 - 4 days, with the various models calling for landfall somewhere between the upper Texas coast and the Florida Panhandle coast. Given the uncertainties, the move halt operations in the Deepwater Horizon blowout recovery effort are probably wise.

Intensity Forecast for TD 3
The primary detriment to development of TD 3 for the next three days will be the presence of the large upper-level low to its west. As long as this low remains in its present location, relative to TD 3, it will bring wind shear of about 20 knots and dry air into the storm. This will limit the intensification potential of TD 3 to no more than about 10 - 15 mph per day. If the upper-level low slow down a bit, relative to TD 3, more shear will affect the storm, potentially weakening it. Conversely, if the upper-level low picks up speed and pulls away from TD 3, the storm may be able to intensify at a faster rate. None of the computer models is calling for that to happen, but it would not take much of an additional separation between TD 3 and the upper level low to substantially reduce shear and allow TD 3 to intensify into a hurricane on Saturday. I put the odds of TD 3 making it to hurricane strength in the Gulf of Mexico at 20%.

98L
An area of disturbed weather (98L) has developed in the Gulf of Mexico's Bay of Campeche. This system is under a low amount of shear, 5 - 10 knots, and may barely have enough time to organize into a tropical depression before making landfall along the Mexican coast a few hundred miles south of the Texas border on Friday.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Next update
I'll have an update between 3 - 4 pm, when the Hurricane Hunters will be in the storm. I'll also speculate on the possible impact the storm will have on the oil spill region.

Jeff Masters

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: 772 - 722

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 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33Blog Index

Lowest pressure found so far is 1008mb, in agreement with the 2PM advisory.

000
URNT15 KNHC 221811
AF306 02BBA INVEST HDOB 24 20100722
180230 2217N 07512W 9913 00148 0083 +236 +143 025019 021 027 004 00
180300 2216N 07511W 9912 00150 0084 +233 +142 015017 020 029 003 00
180330 2215N 07510W 9914 00148 0084 +235 +141 011017 018 027 003 00
180400 2213N 07509W 9914 00147 0084 +235 +141 002014 015 025 003 00
180430 2212N 07508W 9914 00147 0083 +235 +142 345014 015 026 002 00
180500 2210N 07507W 9914 00148 0084 +235 +144 340015 015 025 003 00
180530 2209N 07506W 9914 00147 0084 +235 +147 336014 015 026 003 00
180600 2207N 07505W 9914 00147 0084 +235 +151 338013 014 024 004 00
180630 2206N 07504W 9911 00152 0084 +235 +154 326012 013 022 003 00
180700 2205N 07503W 9913 00148 0083 +236 +157 320012 013 023 002 00
180730 2203N 07502W 9912 00149 0083 +240 +160 306011 012 022 002 00
180800 2202N 07501W 9915 00146 0083 +236 +162 303010 011 021 002 00
180830 2201N 07501W 9914 00149 0085 +238 +164 299010 010 021 003 00
180900 2159N 07500W 9901 00161 0086 +239 +166 291010 010 021 001 00
180930 2158N 07459W 9910 00157 0089 +240 +167 279009 009 018 003 00
181000 2156N 07457W 9914 00155 0091 +241 +168 276009 010 021 002 00
181030 2154N 07456W 9911 00159 0093 +241 +170 272010 010 021 001 00
181100 2153N 07455W 9914 00158 0094 +242 +171 263011 012 023 001 00
181130 2151N 07454W 9915 00157 0095 +240 +173 271011 011 021 002 00
181200 2150N 07453W 9913 00159 0095 +243 +175 280011 011 016 005 00
$$
;
Member Since: September 2, 2009 Posts: 130 Comments: 21032
771. unf97
Quoting StSimonsIslandGAGuy:
You think a special update to upgrade to TS strength will be issued, or will the NHC just wait till 5 pm?


Hey SSIGuy. I think NHC will issue a special advisory with an upgrade to Storm status. In most cases they generally do, but peopeple need to be alerted and prepared for this news, which is why the need for the special advisory.
Member Since: September 25, 2007 Posts: 0 Comments: 1193
Quoting neonlazer:
So we got Slidell, Baton Rouge, Lafayette, Lake Charles...i think one of us might get hit..hope its me!(coming from a nuthead who gets excited over storms..and another friend whose anxious to have a hurricane party..)


Yea I had a friend that got "excited " and had a hurricane party with RITA and now has severe heart trouble...LOL
Member Since: Posts: Comments:
Guys this looks like a Florida Keys Storm not South Florida. South Florida will only get the affects CHILL OUT!!!
Member Since: July 5, 2008 Posts: 0 Comments: 199
TD-3 Outermost Western Bands of Rain now on Long range..Miami.

NEXRAD Radar
Miami, Base Reflectivity 0.50 Degree Elevation Range 248 NMI

Member Since: July 3, 2005 Posts: 414 Comments: 125615
Quoting louisianaboy444:


I'm 25 miles to your West....i believe we will be right in the cross hairs of this one
i'm in mandeville from st. bernard parish
Member Since: September 10, 2008 Posts: 0 Comments: 1291
Quoting MiamiHurricanes09:
The center isn't reforming, it however is relocating.


Probably trying to avoid the dry air.
Member Since: March 19, 2009 Posts: 0 Comments: 1419
Quoting StSimonsIslandGAGuy:
You think a special update to upgrade to TS strength will be issued, or will the NHC just wait till 5 pm?
If it is a 50mph TS or stronger a special advisory should be issued, however if it is only a 40mph system they should wait.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting neonlazer:
So we got Slidell, Baton Rouge, Lafayette, Lake Charles...i think one of us might get hit..hope its me!(coming from a nuthead who gets excited over storms..and another friend whose anxious to have a hurricane party..)
I am in Braithwaite, but believe me, I am not excited at all :(
Member Since: Posts: Comments:
Quoting Tropicaddict:


then where to?
After it passes west of south Florida I'll give you a more accurate response.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting Patrap:
NEXRAD Radar
Miami, Storm Relative Mean Radial Velocity 0.50 Degree Elevation Range 124 NMI



Seen you do this a few times. What for?
Member Since: Posts: Comments:
One has to be patient with single obs..

That Convective burst has rotated NNw thru the last 2 hours,

But,

Note the Visible Surface reflection as it slides off to the WnW still..and the whole envelope.


TD-3 a tightening Storm on Tropical Stoms Status Threshold.

Floater - Visible Loop
Member Since: July 3, 2005 Posts: 414 Comments: 125615
Hey, I'm long time lurker but a relative newbie. When you guys are talking about the wind speeds from recon, are we talking gusts or 1 minute sustained winds?
Member Since: Posts: Comments:
Quoting Jeff9641:


Center keeps reforming north. Mia to West Palm better get ready because she's ah coming. Se FL to NOLA.
The center isn't reforming, it however is relocating.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting MiamiHurricanes09:
I sure do. What CCHS posted a while ago is exactly what I'm thinking, south Miami-Dade landfall.


then where to?
Member Since: Posts: Comments:
In Lakeview, New Orleans...Everyone here watching
Member Since: Posts: Comments:
Hello StormW :) Hope you are having a good day? *snickers* :)
Member Since: June 16, 2008 Posts: 0 Comments: 505
Quoting Joanie38:
Hey!! SWLA resident here! :)



Hey Joanie... I believe we need to keep a close eye on this one..
Member Since: Posts: Comments:
Quoting neonlazer:
So we got Slidell, Baton Rouge, Lafayette, Lake Charles...i think one of us might get hit..hope its me!(coming from a nuthead who gets excited over storms..and another friend whose anxious to have a hurricane party..)


Nawlins here ... and just as nervous too! Although, I must say, I am a bit more nervous about the oil impact than anything else
Member Since: Posts: Comments:
Quoting bohonkweatherman:
The good news right now is the Storm is moving pretty darn fast at 15 mph and forecasted to speed up even more.


Does not look to be moving to fast to me
Member Since: Posts: Comments:
Quoting neonlazer:
Lafayette checkin in XD
Just south of you in Vermilion Parish...Erath!
Member Since: Posts: Comments:
Quoting mikatnight:




Ya'll think the models are gonna go right (north)?
I sure do. What CCHS posted a while ago is exactly what I'm thinking, south/central Miami-Dade landfall.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Plenty of TS force winds to be Bonnie
Member Since: October 28, 2006 Posts: 57 Comments: 29714
I noticed that the winds at bouy 41009 are pretty light out of the east- 8-9 knots- perhaps the ridging at least at the lower levels is not very strong or there would be greater gradient winds by now?
Member Since: Posts: Comments:
735. xcool
move wnw at 15k
Member Since: Posts: Comments:
35.0 knots (~ 40.2 mph)
Tropical Storm
Member Since: Posts: Comments:
NEXRAD Radar
Miami, Storm Relative Mean Radial Velocity 0.50 Degree Elevation Range 124 NMI

Member Since: July 3, 2005 Posts: 414 Comments: 125615
according to those barbs on google earth, how can you tell which way its coming out of
Member Since: Posts: Comments:
NE of 11am location, lol.
Member Since: Posts: Comments:
Quoting Skyepony:
TD3 does look well north of the forecast points..


Quoting MiamiHurricanes09:
I wouldn't be surprised to see 03L be a 50_ mph system at 5PM.


Ya'll think the models are gonna go right (north)?
Member Since: Posts: Comments:
728. xcool
Hhunterwatch your mouth thanks
Member Since: Posts: Comments:
Hey!! SWLA resident here! :)
Member Since: June 16, 2008 Posts: 0 Comments: 505
Winds mainly tropical storm force.

000
URNT15 KNHC 221802
AF306 02BBA INVEST HDOB 23 20100722
175230 2245N 07531W 9766 00296 0103 231 125 043031 033 035 002 00
175300 2244N 07530W 9771 00290 0101 231 127 040031 032 033 002 00
175330 2243N 07529W 9767 00293 0101 230 129 038031 033 032 002 03
175400 2241N 07528W 9768 00292 0100 229 131 037033 034 033 003 03
175430 2240N 07527W 9770 00288 0099 230 131 034031 032 034 002 00
175500 2238N 07526W 9770 00287 0098 227 132 032032 033 035 003 00
175530 2237N 07525W 9769 00286 0097 226 133 034032 033 035 003 00
175600 2235N 07524W 9771 00284 0095 229 133 033032 033 034 003 00
175630 2234N 07523W 9766 00288 0094 229 133 031033 033 035 003 00
175700 2233N 07522W 9768 00286 0093 228 134 027033 033 034 005 00
175730 2231N 07522W 9773 00280 0092 230 136 030034 036 033 004 00
175800 2230N 07521W 9912 00155 0090 237 137 027032 035 036 002 00
175830 2228N 07520W 9950 00119 0086 242 138 026032 033 036 003 00
175900 2227N 07519W 9947 00120 0086 242 140 030028 030 034 003 00
175930 2226N 07518W 9945 00123 0085 241 141 031028 030 034 002 00
180000 2224N 07517W 9908 00156 0086 240 142 028026 028 032 004 00
180030 2223N 07516W 9916 00148 0086 239 144 029025 026 030 004 00
180100 2221N 07515W 9911 00151 0085 236 144 027025 027 033 001 00
180130 2220N 07514W 9914 00148 0084 236 145 027026 028 032 004 00
180200 2219N 07513W 9915 00146 0084 230 144 021019 019 032 004 00
$$
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting HoustonTxGal:
<------ blows up the pink balloons and begins passing out pink cigars... It's a GIRL!!! LOL

ROFLMAO
Member Since: Posts: Comments:
Quoting Jeff9641:
Hey guys look at it's movement now. It seems to wanna cross to the other side of the Bahamas or ride the eastern most islands.

http://www.wunderground.com/tropical/tracking/at201003_sat.html
still calling for that east coast of florida hit. At least you are persistent in your call. Probably wrong but you are persistent.
Member Since: Posts: Comments:
NEXRAD Radar
Miami, Velocity Azimuth Display Wind Profile Range 124 NMI

Member Since: July 3, 2005 Posts: 414 Comments: 125615
Hmmm, how can 97L become Bonnie if 97L was supposed to be "dead"? Should I continue to ignore 97L and wait until August to get my hurricane preps in place? *snark off*
Member Since: Posts: Comments:

Viewing: 772 - 722

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 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33Blog Index

Top of Page

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.