Tropical depression forming over the Bahamas

By: Dr. Jeff Masters , 1:29 PM GMT on July 22, 2010

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A tropical wave (Invest 97L) over the eastern Bahama Islands has developed a closed circulation at the surface, and has become a tropical depression or tropical storm. Here is the text of the Special Tropical Weather Outlook from NHC at 8:25am EDT today:

Visible satellite images and observations from the Bahamas indicate that the area of low pressure in the southeastern Bahamas has become better organized and a closed circulation has formed. Advisories on a tropical depression or a tropical storm will be initiated at 11 am EDT...1500 UTC today. This advisory will likely include tropical storm watches and warnings for portions of the Bahamas and southern Florida.

Satellite images of 97L show a modest area of heavy thunderstorms that have slowly increased in intensity and areal coverage this morning. Water vapor satellite loops show a large area of dry air lies to the west of 97L, over Florida. This dry air is associated with a large upper-level low pressure system that is moving west at about the same speed 97L is. The counter-clockwise flow of air around the upper low is bringing about 20 knots of wind shear to 97L. Surface observations in the Bahamas and several nearby ships have shown top winds in 97L 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 97L
The storm is in a fairly straightforward steering current environment, and 97L 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 97L over the next two days. The location of 97L'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 97L
The primary detriment to development of 97L 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 97L, it will bring wind shear of about 20 knots and dry air into the storm. This will limit the intensification potential of 97L to no more than about 10 - 20 mph per day. If the upper-level low picks up speed and pulls away from 97L, the storm may be able to intensify at a faster rate. None of the computer models is calling for that to happen, but it is possible. I put the odds of 97L 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.

I'll have an update after NHC releases their 11am advisory package.

Jeff Masters

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patttttttt oh wise one , please speak to us , and give us your opinion of how this storm might strengthen and where it may go ,
Member Since: Posts: Comments:
gator where are u from , are u from one of the affected areas that ike, katrina or rita hit.
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Quoting chrisdscane:
what time do u guys expect the first few outerbands will reach Sfl ima try to geta round of golf today
You'll be able to play 36 holes today if you want.
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Thanks Storm. Do you think the COC is a bit farther north than the NHC track? It looks like it is about a half degree north.
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Quoting pensacolastorm:


Fool. Then you will have oil on the western side of Lake Ponchatrain, up all the bayous and raining down on your house.

At least it keeps the LA oil off of us in FL.



AMEN~
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Quoting HoustonTxGal:
Guess it is a good thing I just stocked up on groceries... Here in my neck of the woods after Ike, all we need is a small gust of wind and we lose power. So if TD3 comes this way... we may be out of lights for a few days. UGH!! and I so love my A/C!


Nah, HTG, ain't gonna happen. And I know this 'cause my standby generator was finally installed this week guaranteeing that Galveston, Fort Bend and Harris County will not see another major storm until I move out of the house. Thank you very much. It's just one of the services I provide to the public.
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Quoting est1986:
Bonnie will come straight to louisiana. I hope!


Fool. Then you will have oil on the western side of Lake Ponchatrain, up all the bayous and raining down on your house.

At least it keeps the LA oil off of us in FL.
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They are shuting down operations in the gulf with the oil cleanup along with drilling the relief well and killing the old well. Probably a 10 day delay for all operations.
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GUYS I'M TELLING THE CONE WILL SHIFT A LITTLE FURTHER NORTH THE CENTER HAS MOVED A LITTLE NORTH OOP'S CAPS sorry about that
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NEW BLOG!!!
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I am suer glad I tested my generator last week...Houston, we have a problem.... Ready for a generator driven bbq
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Texas anyone??



AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Max Mayfield rocks!
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I have found the NHC is pretty much on target 3 days out on the track of most storms. They have it down to as science as opposed to guess work. If I lived in S Florida and the Keys I'd be making some plans. North Gulf Coast, well, good luck too.
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We're on a local weather conference call at 1 with NWS Ruskin... They'll give us the straight dope about what to expect here on Florida's west coast.

My anniversary is this Saturday... da missus will be quite upset if our beach plans get rained out!
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NEW BLOG!!!
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Quoting 7544:
cone will go north on the next update from the keys to miami
Why do you think that will happen? Your reasoning if you don't mind.
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Blog Update!

July 22, 2010 - 11:55 AM EDT - Tropical Depression #3 Is Classified - 98L Organizing
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Does someone has a link to the MJO forecasts? Per San Juan NWS, MJO will become highly unfavorable begining next week.
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Quoting HurricaneFCast:

Actually this is flawed logic, as the Maximum Sustained winds that the Hurricane Hunters record when flying through these systems already account for the impact of forward velocity. Any physical measurements taken of a tropical cyclone, or any wind, for that matter, will be accurate.. The winds they are recording are within the cyclone, and the cyclone is moving WNW at 16mph already, therefore there is no need to add 16mph to whatever value they record in the vicinity of the system. You see? It's one of those things that once you realize you respond "Ohhh yeahhh, duh!" :D


Ohhh Yeahhh, duh!

Really, thank you for the information. I was thinking of it in terms of circulation wind speed, not that flight level wind recordings would have already measured that. I appreciate your response. Learning.
Member Since: April 28, 2008 Posts: 0 Comments: 354
798. xcool
NEWWWWWWWWWWWWWWW BLOGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG
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Quoting Chigz:
I have been a member of this blog for a few years and this year lot of the new members are talking so much CRAP! Please stop...This blog ought to be a little scientific as well as people giving their opinions based on some facts - rather then PURE WISHCASTING...

Glad to folks like StormW, Levi..and others!
No doubt. The wish casting is ridiculous on here but you can generally tell who does it. Just add them to you list :)
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Quoting floridaT:
hi all. caicosrs what was the strongest wind ya had last night?


During the night, the strongest GUST registered by my anemometer was 33 mph
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Quoting Surfcropper:
I'm in Big Pine Key (mile marker 31) and we're under a TS warning now.

already??
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Doesn't look like Texas isn't going to have fun early next week. It seems like the cone is quite small, so the steering patterns must be straightforward.

any thoughts on that?
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Breaking News..........Bad news for Deepwater Horizon....I promise you will hear this 100 times over the next few days!!!
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I think the center is to the north of the nhc.
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Quoting IKE:


I just shipped 2 boxes of depressant meds to WU bloggers in and around Miami. Should be arriving about 2 EDST.


Patch form will probably be the best for them. oy. Things are sure getting interesting in the blog and in general.
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Bonnie wil be a CAT 1 for sure. No way around that, but she may have messy hair,LOL!
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guys am I crazy or is this thing starting to rap up storms around the center
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Quoting BenBIogger:


Indeed. What Lat/Lon do you see the LLC?


21.9N 74.9W
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NEW BLOG!
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Live HH Recon Data for Google Earth
Link
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hi all. caicosrs what was the strongest wind ya had last night?
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Weather for Extreme NE Dade. I'll break out a few further south.

Today
Partly sunny with isolated showers. Breezy. Highs in the lower 90s. Northeast winds 10 to 15 mph becoming 15 to 20 mph later in the afternoon. Chance of rain 20 percent.
» ZIP Code Detail
nt_chancerain
Tonight
Partly cloudy in the evening then becoming mostly cloudy. Scattered showers and isolated thunderstorms. Lows around 80. Northeast winds around 15 mph. Chance of rain 50 percent.
rain
Friday
Mostly cloudy with numerous showers and scattered thunderstorms. Highs in the upper 80s. Southeast winds around 15 mph. Chance of rain 60 percent.
» ZIP Code Detail
nt_chancerain
Friday Night
Mostly cloudy with scattered showers and thunderstorms. Lows around 80. Southeast winds 10 to 15 mph decreasing to 5 to 10 mph. Chance of rain 50 percent.
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Quoting goavs4:


http://hhrecon.com/recon/ge/Recon_Data_for_the_Atlantic_Basin.kmz


cool thanks
Member Since: May 30, 2010 Posts: 0 Comments: 111
Quoting CaicosRetiredSailor:

The COC seems to be at 75W in that image.
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Is the Shaqcane being replace by the Lebroncane?
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Quoting whs2012:
I think us up here in Alaska are going to get this one.... (sarcastic tone, but some peoples predictions are as unlikely as this) lol.


for some reason i have u on ignore?
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Quoting TexasGulf:
I mentioned this yesterday, but will say again.

TD3 (Bonnie) moving WNW over gulf at 16 mph. Winds to the North along the coast prior to landfall will be roughly one category higher than storm intensity rating.

If TD3 (Bonnie) becomes a Cat-1 @ 80 mph wind speed, North eye wall winds will be 96 mph Cat-2. If it has 100 mph Cat-2 sustained winds, North eye wall winds will be 116 mph Cat-3. Fast forward motion tends to make this a stronger storm (although not as long lasting).

Also, keep in mind that the main thrust of the storm surge will be slightly higher than normal along the coast due to the rapid movement of the storm to the WNW. Whatever the category rating... think one category higher with respect to damages at landfall just due to fast forward motion of the storm.

Even if this is projected to be a strong tropical storm... prepare for Cat-1 at landfall just due to fast forward speed.

Actually this is flawed logic, as the Maximum Sustained winds that the Hurricane Hunters record when flying through these systems already account for the impact of forward velocity. Any physical measurements taken of a tropical cyclone, or any wind, for that matter, will be accurate.. The winds they are recording are within the cyclone, and the cyclone is moving WNW at 16mph already, therefore there is no need to add 16mph to whatever value they record in the vicinity of the system. You see? It's one of those things that once you realize you respond "Ohhh yeahhh, duh!" :D
Member Since: April 20, 2007 Posts: 7 Comments: 1482
776. 7544
moving west nw at 16 seems way slower than that to me

recon will not wait its getting to close so the info will be sent to nhc asap not 3 hours latter stay tuned we still might see bonnie faster than u think
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Quoting StormW:


Be doing an update shortly.

Storm, please give some attention to the intensity forecast (as I am sure you will). I am optimistic about the official view on this, but I am not exactly comfortable with it.

Thanks!
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Quoting rossclick:
i have google earth.. how do i get to the HH info?>


http://hhrecon.com/recon/ge/Recon_Data_for_the_Atlantic_Basin.kmz
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773. RM706
Quoting Patrap:
000
NOUS42 KNHC 211500
WEATHER RECONNAISSANCE FLIGHTS

FLIGHT ONE -- TEAL 70
A. 22/1800Z
B. AFXXX 02BBA INVEST
C. 22/1430Z
D. 23.0N 76.0W
E. 22/1700Z TO 21/2300Z
F. SFC TO 10,000 FT


Teal 70 ... is this for TD3? 1PM ET?
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max winds are max winds. They are measured by the HH's. You don't have to do math upwards. YOu can subtract from the max on the weak side. They will not list a storm as a cat 1 if someone is going to get cat 2 or 3 winds.
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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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