Tropical Depression Three forms

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

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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

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1372. Greyelf
Quoting TexasHurricane:


Hi Storm - how prepared you think we should get here in SE TX?


Lol...for some reason, I just "heard" Patrap's voice in my head saying...."you should always be prepared". Heh.
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Quoting southfla:


50mph sustained winds (the forecast max) are not fun, at least not for me. Yes, airports can be closed due to tropical storms. I think you are being a bit harsh and perhaps not fully understanding the implications. I have never understood the "it's only a tropical storm" mentality.


TS Allison is another good example.
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Why does Bonnie seem to suddenly look powerful then, just as suddenly, seems to fall apart and weaken?
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perhaps 11pm...?
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Tropical Storm Allison taught me a big lesson here in Houston. If it says tropical anything pay attention. I am in a home that flooded during IKE so I am on the alert
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Quoting FSUstormnut:
still have not seen surface winds above 36mph... thats not 40-45mph...


there were numerous ones before
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looks like based on the current movement the forecast track will be shifted north looks like a Miami-Dade county Direct hit and exit near bonita beach on the florida west coast, i really dont think we will have winds above 60 MPH and maybe in gusts .
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Whats the Navy Site . . . Lost all my favorites when I moved!
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Quoting FSUstormnut:
IMO...No way td3 will be upgraded.. it looks like she’s losing all her steam.. Storms are collapsing big time…


lol r u blind she finally has significant showers on the west and hurricane hunters r reporting ts winds lol huhhhh
Member Since: July 21, 2010 Posts: 0 Comments: 1052
still have not seen surface winds above 36mph... thats not 40-45mph...
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Quoting smmcdavid:
You know... for a bunch of people that do nothing but make fun of TWC and how wrong they are all the time, you guys sure do watch it a lot. Seems kinda strange to me.


Indeed.
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Quoting smmcdavid:
You know... for a bunch of people that do nothing but make fun of TWC and how wrong they are all the time, you guys sure do watch it a lot. Seems kinda strange to me.


Quote of the day.. Ding ding ding "what do we have for her johnny?"
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She looks emaciated bur D-max will fix her up I'm fairly certain we'll have Bonnie at the end of the day
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1359. Patrap
Member Since: July 3, 2005 Posts: 414 Comments: 125572
StormW want to see something very interesting,run the floater RGB at the nhc. I'm no meteorologist but the last two frames are a shocker thunderstorms forming ne to west of new apparent center.
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Quoting Hurricanes101:


so the numerous winds of 40-45mph and pressure of 1006 count for nothing?

Really?


I agree. No Bonnie yet. No sustained winds have been recorded to justify it.
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This system isn't looking too great, like it was earlier. Is there a reason for this?
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Do they now use that icon for a TD?
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vortex message have not seen it
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Quoting CybrTeddy:
1006.0 mb
(~ 29.71 inHg)
What are the coordinates?
Member Since: September 2, 2009 Posts: 130 Comments: 21032
1352. Skyepony (Mod)
recon hit center ~22.4N 75.1W
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Quoting Rainy Eyes:
Ok, I am still a newb, despite lurking here for 3 years. This is a question, not a whiscash..but, what is making this storm go west then turn north rather then riding the florida coast straight north to Te panhandle. It is avoiding that dry air and ULL but why not just stay east of that and go up the florida coast? can someone explain?
A ridge of high pressure to it's east keeps it moving west of FL. If the high pressure moves back toward the east (which is not forecast) then the storm could move more north along the coast. If the ridge moves more west, then the storm is pushed further west. (this is one and a main contributor to the movement of this storm)
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Quoting ecflweatherfan:
LLC according to the RGB appears to be at 22.8N 75.0W... nice blob of convection developing right near the center.


thats where i see the center based on wind direction from the HH data but I am just an amateur
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Thanks storm :)
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Tropical Storm Allison did less damage as a Tropical Storm to Houston than it did as a Tropical Depression after it turned around and engulfed the city with about 3 feet of water. I don't trust any tropical system. The winds might not be much but the rain and flooding can make for a really bad day.
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Not liking this setup. Plus, this reflects oil being pushed ashore.
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1344. angiest
Quoting southfla:


50mph sustained winds (the forecast max) are not fun, at least not for me. Yes, airports can be closed due to tropical storms. I think you are being a bit harsh and perhaps not fully understanding the implications. I have never understood the "it's only a tropical storm" mentality.


This was from "only a tropical storm":



Note, that is a 10+ lane freeway that person is canoeing down.
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Quoting cheetaking:


What I want to know is what happened to the Weather Channel? I learned a lot about weather by watching them in the old days, and would watch hurricanes develop for hours on end there. Now it's all fluff... dumbed down, a bunch of chit-chat about completely non-weather-related events, and a laughably short tropical update where they hardly talk at all about why or why not storms are developing.


What happened is they got taken over by NBC.
Member Since: March 19, 2010 Posts: 0 Comments: 1146
Quoting StormW:


A ridge in the low to mid layers is going to carry it toward the WNW, and by the end of the forecast period, as in the current forecast track, a weakness (or simply, a change in the steering layers to a more northerly component) in about 3-4 days.

CURRENT STEERING



Go here, and use the middle set of maps
FORECAST STEERING



Storm, do you think she'll be upgraded at 5?
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1341. IKE
Quoting PensacolaDoug:
Here's more Joe Bastardi.


THURSDAY:
LOOK AT THIS FROM KEY WEST:

...WINDS AND SEAS... AS TROPICAL DEPRESSION THREE APPROACHES...SUSTAINED TROPICAL STORM FORCE WINDS ARE EXPECTED TO BEGIN LATE FRIDAY MORNING. SEAS OF 8 TO 12 FEET FRIDAY MORNING MAY BUILD TO 10 TO 16 FEET BY FRIDAY AFTERNOON.

Now, there is little weather with and south of the center of this. The center is likely to go north of them. It's like what we saw with warnings on the Mexican coast with Alex and TD 2.

I expect wind gusts from Miami to Ft. Pierce to average over 35 knots but I would be surprised if I see one over 20 knots at eyw, when the storm is within 100 miles of them.

Ciao for now.


He thinks a south Florida hit.

If that verifies it seems unlikely this goes to Texas. I would think Louisiana or just east.
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Quoting ecflweatherfan:
Just a guess... but possibly issuance of TS Watch northward along the FL East Coast to Fort Pierce or possibly as far north as Sebastian Inlet... and along the West FL coast up to Anclote Key (Including Tampa Bay) at 5pm??? Just thinking with the relocation and all...
I concur - it certianly appears they will have to shift some watches warning northward.
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Model update and track shift



AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI
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He's talking about the WU tropical homepage. It's shown a TS icon on the map for the last hour.
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Recon found earlier nearly a whole page of TS/ near TS force winds.. if its not a TS its getting close.
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This blog is like a roller coaster... ups and downs but mainly downs.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting Floodman:


My, but you're easily amused...LOL


Hey - Its only 9:30 here....I have all day to get work done!
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So still TD at 5?
Member Since: September 6, 2009 Posts: 2 Comments: 3709
Quoting MiamiHurricanes09:
South Florida stretches to the keys, so it isn't gonna be put to bed. Still stickin' with my south Dade prediction. Lol.


The Coordinates are 22.5N and 73.2W which is pretty close to the NHC Track
Member Since: August 29, 2006 Posts: 22 Comments: 1339
Did yall see that big jump to the NW?
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Quoting southfla:


50mph sustained winds (the forecast max) are not fun, at least not for me. Yes, airports can be closed due to tropical storms. I think you are being a bit harsh and perhaps not fully understanding the implications. I have never understood the "it's only a tropical storm" mentality.


It's ONLY a Tropical Depression
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1006.0 mb
(~ 29.71 inHg)
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Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 22nd day of the month at 18:37Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Mission Purpose: Investigate second suspect area (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 11

Mandatory Data...

Observation Time: Thursday, 18:35Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 22.5N 74.5W
Location: 191 miles (308 km) to the NNE (27°) from Santiago de Cuba, Cuba.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 180 meters
Flight Level Wind: From 150° at 34 knots (From the SSE at ~ 39.1 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 25°C
Flight Level Dew Point: 20°C
Weather (within 30 nautical miles): Thunderstorm(s)
Mean Sea Level Pressure (MSLP): 1009 mb (extrapolated)

Optional Data...

Estimated Surface Wind: From 150° at 25 knots (From the SSE at ~ 28.7 mph)

Remarks Section...

Surface Wind Speed (likely by SFMR): 32 knots (~ 36.8mph)
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Quoting FSUstormnut:
IMO...No way td3 will be upgraded.. it looks like she’s losing all her steam.. Storms are collapsing big time…


so the numerous winds of 40-45mph and pressure of 1006 count for nothing?

Really?
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Quoting MiamiHurricanes09:
The ever so reliable TWC just said..."Recon is inside investigating tropical depression 3 to see if it has wind enough to be called Bonnie."


What I want to know is what happened to the Weather Channel? I learned a lot about weather by watching them in the old days, and would watch hurricanes develop for hours on end there. Now it's all fluff... dumbed down, a bunch of chit-chat about completely non-weather-related events, and a laughably short tropical update where they hardly talk at all about why or why not storms are developing.
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Quoting NoNamePub:
WAHOO - MY AV IS APPROVED


My, but you're easily amused...LOL
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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.