Tropical Storm Bonnie Makes Her Debut

By: Dr. Jeff Masters , 4:32 AM GMT on July 23, 2010

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Hi everybody, this is Dr. Rob Carver filling in for Jeff on the late shift.

Based on information from Hurricane Hunters, the National Hurricane Center upgraded TD Three to Tropical Storm Bonnie. As of the 11PM EDT advisory, Bonnie was at 23.4N, 76.5W which is 285 miles southeast of Miami, Florida. Bonnie has maximum winds of 40 mph, a minimum central pressure of 1007 mb, and is moving to the northwest at 14 mph. Bonnie will pass over the Everglades/Florida Keys Friday and cross into the Gulf of Mexico Friday night/early Saturday morning. Tropical storm warnings are in effect for both Florida coasts south of Lake Okeechobee to Key West.


Fig. 1 IR satellite image of Tropical Storm Bonnie at 1216AM EDT.

Threats
NHC is expecting 2-4 inches of rain over south Florida due to Bonnie and 3-5 inches over the Bahamas. They are forecasting a storm surge of 1-2 feet. Tropical storm force winds are expected in the Bahamas starting Thursday night, and they are forecast to arrive in southern Florida Friday morning.

Impacts and Emergency Preparedness
As of 1130PDT EDT, the Key West NWS office is indicating that there are no evacuation orders in effect or planned for Monroe County (the Keys). Small craft are being advised to stay in port and be well secured to their docks. Two shelters will be opened, Key West High School and Stanley Switlik Elementary School in Marathon.

Most of the ships at the Deepwater Horizon oil spill site and other skimming ships have been ordered to seek safe harbor. In the statement, Adm. Allen said ships that operate the ROVs will be the last out and the first back to keep the wellhead observations going as long as possible.

Forecast/Model Assessment
The track models and ensemble models show remarkably good agreement for Bonnie's path across south Florida and towards southeast Louisiana. The current intensity forecast calls for Bonnie to maintain strong tropical storm force winds (40-50 knots) until it makes landfall in Louisiana, with a 15% chance of becoming a hurricane before then. However, the global models (GFS, Canadian GEM, NOGAPS) and the hurricane dynamical models (GFDL, Navy GFDL, and HWRF) do not intensify Bonnie at all. The statistical models (SHIPS and LGEM) support the intensity forecast.

I'm inclined to take the predictions of global and dynamical models with a large grain of salt. When I reviewed the latest model runs (18Z and 12Z), it was apparent that none of the models had a good initialization of Bonnie's structure. Bonnie has a relatively small circulation, so it's easy for the models' initialization to act like there isn't much of a storm there. Without accurate starting conditions, any model will have trouble producing an accurate forecast. NHC has a good summary of the different forecast models they use.

Next Update
Jeff will have an update sometime Friday morning.

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Quoting chrisdscane:



so just to the left?


South of the convection. Recon will confirm soon.
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Quoting NCHurricane2009:
Point 1: This is annoying. Where are you centered Bonnie??? LOL

Point 2: I don't think they're going to upgrade the intensity of Bonnie at 2 AM 'cause they are still waiting for the recon data at the center.


I dunno if this means that is the position or just what the models think it is. But The HPC doesn't know either.

.TROPICAL STORM BONNIE...

BASED ON THE NAM BOUNDARY LAYER WIND ANALYSIS THE MODEL PLACES THE
CENTER OF BONNIE ABOUT 40 NM FARTHER S THAN THE TPC/NHC ANALYZED
POSN. THE GFS PMSL MINIMUM IS FAIRLY CLOSE TO THE TPC POSN BUT
THE BOUNDARY LAYER WIND ANALYSIS ALSO SUGGESTS A CENTER TO THE S
OF THE OBSERVED LOCATION. THE GFS/UKMET MAINTAIN A BETTER DEFINED
SFC REFLECTION THAN THE NAM FOR MOST OF THE FCST. THRU F48 LATE
LATE SAT THE GFS-TYPE SOLN APPEARS TO BE FAIRLY CLOSE TO THE
TPC/NHC TRACK GIVEN BY THE 03Z ADVISORY... ASIDE FROM MINOR TIMING
DIFFS. THE CANADIAN GLBL STRAYS FASTER THAN THE OFFICIAL TRACK BY
F48. CONSULT THE LATEST TPC/NHC ADVISORIES/DISCUSSIONS FOR
FURTHER INFO ON BONNIE.

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295. xcool
flag 82k
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Quoting cybergrump:
recon found cat 1 winds


SFMR is malfunctioning, and the quality-control flag "03" was on meaning that SFMR readings are questionable. Use the flight-level winds in the 4th column from the right as a guide while SFMR is down. Those should always be used as a modifier to SFMR readings anyway, which tend to be unreliable a lot of the time.
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293. 7544
no way cat1 winds
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292. Murko
North Eleuthera, Bahamas here, 25º27'N 76º37'W. Moderate winds, ~15-20mph, can't really tell what direction, probably N-E, no rain.
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291. Bonz
LOL. I don't ever think I've seen my name so much in print!

Waiting for that 2 AM update and then time for bed.
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If recon finds west winds over more than a few measurements during their flight I will be surprised.
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Quoting Levi32:
The center is not centered under the convective ball based on this:




so just to the left?
Member Since: July 21, 2010 Posts: 0 Comments: 1181
Quoting cybergrump:
recon found cat 1 winds


SFMR instrument is broken.
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Evening.. or morning, guys. Where is the center of this thing? I'm looking and seeing it around 77.4W and 24.4N. Am I close?
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WTNT43 KNHC 230249
TCDAT3
TROPICAL STORM BONNIE DISCUSSION NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032010
1100 PM EDT THU JUL 22 2010

..... THE NEXT AIRCRAFT
IS SCHEDULED TO REACH BOONIE AROUND 06Z.

My "Boonie" lies over the ocean??!!

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Quoting cybergrump:
Link


Those values are suspect.

SFMR looks like its malfunctioning.
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283. xcool
gfdl call for 68 wind in gom





sorry for two posting
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The dreaded pinhole eye......not really just a hot tower but, i thought i would at least get a chuckle..
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The center is not centered under the convective ball based on this:

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Quoting txraysfan:
Long time watcher-new blogger. Am learning a lot from ya'll. If I do anything wrong, please let me know.


? lol ik to much jerks here rofl
Member Since: July 21, 2010 Posts: 0 Comments: 1181
Point 1: This is annoying. Where are you centered Bonnie??? LOL

Point 2: I don't think they're going to upgrade the intensity of Bonnie at 2 AM 'cause they are still waiting for the recon data at the center.
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Link

At the surface
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Quoting cybergrump:
recon found cat 1 winds
What ----The
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Quoting cybergrump:
recon found cat 1 winds


No they did not.

SFMR is not functioning.
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Long time watcher-new blogger. Am learning a lot from ya'll. If I do anything wrong, please let me know.
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look at the 5:15 UTZ rainbow
now tell me that doesnt look impressive
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Hurricane Hunters have found a 1007.8 mb pressure reading at 24.3N and 78.1W.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
recon found cat 1 winds
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guys look at her position wPB watch out
Member Since: July 21, 2010 Posts: 0 Comments: 1181
Quoting StSimonsIslandGAGuy:
It seems to me that if Bonnie was strengthening as much as it looks, there would be a pressure reading below 1013 mb somewhere in the Bahamas.


Exactly. Obs and RECON do not support a COC anywhere N of 24 degrees.
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Quoting TampaSpin:


Just to let everyone know......CCHS will be posting blog updates on my site as well now....he will be a very big help to many with his thoughts and updates.


Tampa, could you please check your Facebook wall? I wrote something there that I think you might find particularly interesting. Weather related.
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267. xcool


nola
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24.3N 78W and the winds are starting to become more northerly but are still out of the ENE.

000
URNT15 KNHC 230542
AF305 0403A BONNIE HDOB 18 20100723
053330 2439N 07826W 8432 01582 0117 +167 +150 074036 037 /// /// 03
053400 2438N 07825W 8430 01585 0116 +166 +156 076031 032 018 001 03
053430 2437N 07824W 8432 01596 0112 +165 //// 082028 029 /// /// 05
053500 2436N 07822W 8431 01588 0114 +165 //// 084028 028 /// /// 05
053530 2435N 07821W 8430 01582 0111 +165 //// 083030 031 /// /// 05
053600 2434N 07820W 8429 01583 0110 +169 +167 081029 029 /// /// 03
053630 2433N 07819W 8433 01568 0110 +170 +166 079029 030 /// /// 03
053700 2432N 07818W 8429 01578 0105 +171 +164 076032 033 /// /// 03
053730 2431N 07817W 8431 01579 0105 +172 +165 074031 032 /// /// 03
053800 2429N 07815W 8432 01569 0095 +174 +165 072028 029 /// /// 03
053830 2428N 07814W 8432 01563 0089 +175 +166 072029 029 /// /// 03
053900 2427N 07813W 8432 01575 0095 +176 +166 072028 028 /// /// 03
053930 2426N 07812W 8431 01577 0098 +179 +169 071028 028 022 005 03
054000 2425N 07811W 8432 01565 0093 +180 +170 070027 027 /// /// 03
054030 2424N 07809W 8432 01570 0087 +182 +167 068027 028 /// /// 03
054100 2423N 07808W 8434 01555 0080 +184 +172 065030 032 /// /// 03
054130 2422N 07807W 8431 01573 0094 +175 //// 067030 031 /// /// 05
054200 2421N 07806W 8429 01577 0096 +178 +174 067030 030 /// /// 03
054230 2420N 07805W 8432 01559 0081 +186 +169 065027 028 074 007 03
054300 2419N 07803W 8432 01570 0078 +186 +171 064028 029 /// /// 03
$$
;
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oh BTW shes prolly not going to make south dade landfall look at her position
Member Since: July 21, 2010 Posts: 0 Comments: 1181
Quoting StSimonsIslandGAGuy:
It seems to me that if Bonnie was strengthening as much as it looks, there would be a pressure reading below 1013 mb somewhere in the Bahamas.


That region needs a Buoy badly....
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Quoting StSimonsIslandGAGuy:
It seems to me that if Bonnie was strengthening as much as it looks, there would be a pressure reading below 1013 mb somewhere in the Bahamas.


I agree.
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262. xcool
Hot towers hmmm ?
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Quoting TampaSpin:
Gotta post this message sent to me on my WebSite....this is why i do what i do....I don't think this person would mind since no name is mentioned.....i posted this exactly as written....


I am a 71 year old widow with 2 small dogs living alone 20 miles north of Galveston Tx. (Boy that is a cliche if ever there was one.) I also have a horse and I run from hurricanes, taking dogs and hauling the horse with me. I have done this for 43 years since we moved here in 1967. Recent evacs, Rita 2005, Ike 2008. Alex could be my first one alone, husband died shortly after Ike. I dont understand everything I read on the blog, husband did and I tried to learn from him. I am going to need help. Thanks for your help.





Brought tears to my eyes. Thanks for that, Tampa, and for what you do.
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Quoting Hurricanes101:


actually that is incorrect as 78.4 is well to the west of the system, that is inconclusive to me

ENE winds mean they are on the WSW side of the storm


That's only 50-60 miles due W of the middle of the ball...there would be a much more N-erly component in those winds if the center was at that latitude.
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that and they are still at 5,000 feet outside the ball of convection
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Quoting Hurricanes101:


actually that is incorrect as 78.4 is well to the west of the system, that is inconclusive to me

ENE winds mean they are on the WSW side of the storm


He's actually right I believe. Although Bonnie is small, there should be more of a northerly component to the wind due west of the convection ball if the surface center really was under there. We'll see soon.
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WOULD A MID LEVEL CIRCULATION RLY PRODuce that kind of banding feature, come on
Member Since: July 21, 2010 Posts: 0 Comments: 1181
255. 7544
maybe they will relocate the center under the big ball thay done it before hmmmmm getting interesting by the hour now

cchsweatherman 1:38 AM EDT on July 23, 2010
Hurricane Hunters are now encroaching on the convective mass now.
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Quoting NCHurricane2009:


I see, extrapolate that, looks like its SE of Andros, probably the storm is 50 mph winds right now at its strongest.

Levi, what do you think about the latent heat theory in post 208 and the upper low both imparting a more northward drag than we are currently thinking. That's what concerns me.
Its concerning me too! You can see it !
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Very much hope you're right...and you usually are - good obs


Quoting Levi32:


Yeah you're talking about a relocation of the center under the deepest convection, which does happen, but I doubt so here. The area for pressure falls is favorable to the south, not north, and such a convective burst would have to be sustained very strongly for hours upon hours...at least 12, to try to pull the surface center in. Remember some of our ghost invests in May and June...91L and 92L, had MCCs for many hours but didn't succeed in pulling the surface center in even then.
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Quoting Levi32:


Key is to look at the loop....tune it back to the frame at which the ASCAT pass was taken, note the ASCAT position of the center, and then loop forward to the current frame. Extrapolate and ask yourself whether the center could be directly under the convective ball right now. It wasn't that long ago.


I understand what you're saying but I'm concerned about a center relocation since then and possibly even a reformation under the convective mass.
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Quoting cchsweatherman:


Thanks. I'll probably wait for the 2AM advisory to post a blog.


Just to let everyone know......CCHS will be posting blog updates on my site as well now....he will be a very big help to many with his thoughts and updates.
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Tampaspin that is remarkable and you are to be commended.
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Quoting atmosweather:
If the LLC was under the middle of that ball of convection, it would be around 24.6N 77.3W...RECON does not support that...ENE winds reported due W of that location...that means the center is somewhere to the S or SE of there.


LOL, good point. Looks like then I might eat another crow. I was forecasting at least 60 mph winds by the time Bonnie got to S FL. With a center S of the convection, there is a chance of that forecast failing. But hey, its more important that the storm is weaker than a forecast being right in this case.
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247. xcool
OracleDeAtlantis delete posting plz
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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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