Tropical Storm Bonnie

[Somerset Squall]

Advisory from NHC:

TROPICAL DEPRESSION THREE DISCUSSION NUMBER 1

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032010

1100 AM EDT THU JUL 22 2010

THE TROPICAL WAVE/DISTURBANCE THAT NHC HAS BEEN TRACKING FOR THE

PAST SEVERAL DAYS ACROSS THE ATLANTIC HAS DEVELOPED A SURFACE

CIRCULATION AND ENOUGH ORGANIZED CONVECTION TO BE CLASSIFIED AS A

TROPICAL DEPRESSION. THE DEPRESSION IS SHEARED AT THIS TIME AND ITS

CENTER IS LOCATED ON THE SOUTHWEST SIDE OF A CYCLONICALLY CURVED

CONVECTIVE BAND. THE SHEAR APPEARS TO BE RELAXING A

LITTLE...HOWEVER...AS INDICATED BY THE MOTION OF THE HIGH CLOUDS ON

HIGH RESOLUTION IMAGES. THE CYCLONE IS STILL INTERACTING WITH A

STRONG WESTWARD-MOVING UPPER LOW TO THE WEST. THIS PATTERN WOULD

ONLY ALLOW THE DEPRESSION TO STRENGTHEN A LITTLE AS INDICATED IN

THE OFFICIAL FORECAST...BUT THIS FORECAST IS UNCERTAIN. IN FACT...

NONE OF THE MODELS SHOW SIGNIFICANT INTENSIFICATION.

BECAUSE THE CENTER JUST FORMED...THE INITIAL MOTION IS UNCERTAIN.

THE BEST ESTIMATE IS TOWARD THE WEST-NORTHWEST OR 295 DEGREES AT 13

KNOTS. GLOBAL MODELS FORECAST A WELL-ESTABLISHED SUBTROPICAL RIDGE

EXTENDING FROM THE ATLANTIC WESTWARD ACROSS THE SOUTHERN UNITED

STATES. THIS STEERING PATTERN SHOULD KEEP THE CYCLONE ON A GENERAL

WEST-NORTHWESTWARD TRACK THROUGH 3 TO 4 DAYS ACROSS THE FLORIDA

STRAITS AND THE KEYS AND THEN INTO THE GULF OF MEXICO. BECAUSE THE

RIDGE IS FORECAST TO STRENGTHEN...THE CYCLONE SHOULD BEGIN TO

INCREASE ITS FORWARD SPEED. THE TRACK GUIDANCE IS TIGHTLY CLUSTERED

THROUGH 4 OR 5 DAYS...ALTHOUGH SOME MODELS WEAKEN THE CYCLONE

EARLIER.

AN AIR FORCE PLANE WILL BE IN THE AREA THIS AFTERNOON AND WILL HELP

TO DETERMINE IF THE SYSTEM HAS BECOME A TROPICAL STORM.

FORECAST POSITIONS AND MAX WINDS

INITIAL 22/1500Z 21.9N 75.0W 30 KT

12HR VT 23/0000Z 22.6N 76.8W 35 KT

24HR VT 23/1200Z 23.8N 80.0W 40 KT

36HR VT 24/0000Z 25.0N 83.2W 40 KT

48HR VT 24/1200Z 26.0N 86.5W 40 KT

72HR VT 25/1200Z 28.0N 91.5W 45 KT

96HR VT 26/1200Z 31.0N 94.0W 25 KT...INLAND

120HR VT 27/1200Z 33.0N 95.0W 20 KT...POST-TROP/REMNT LOW

$$

FORECASTER AVILA/ROBERTS

[Cookie]

here we go

[Iceberg]

Wow they have it missing Florida, this is in line with the global GFS model, the hurricane models all take it further north and across Florida.

I was writing a more detailed update but work rudely got in the way and tbh NHC have said about the shear etc in their update.

Conservative on the intensity but probably right given the uncertainty.

[Iceberg]

Updated paths showing the significant shift southwards and westwards to the path over the last 6 hrs. The biggest concern now has to be that it will not hit Florida so should by rights be stronger when it finally hits the GOM underbelly.

However the storm will have to battle through Shear which is forecast to be moderate, particularly once the storm hits the GOM at 36/48 hrs +

The Shear looks to be the only moderating factor, preventing intensification to a hurricane.

[Nick L]

Updated paths showing the significant shift southwards and westwards to the path over the last 6 hrs. The biggest concern now has to be that it will not hit Florida so should by rights be stronger when it finally hits the GOM underbelly.

However the storm will have to battle through Shear which is forecast to be moderate, particularly once the storm hits the GOM at 36/48 hrs +

The Shear looks to be the only moderating factor, preventing intensification to a hurricane.

Interestingly, all local news channels here as well as TWC never showed it going through Florida, only clipping the southern edge at most. Forecasted to be showery and windy here tomorrow with sustained winds of 15-25 mph.

[Cookie]

We now Have Bonnie

[Cookie]

Interestingly, all local news channels here as well as TWC never showed it going through Florida, only clipping the southern edge at most. Forecasted to be showery and windy here tomorrow with sustained winds of 15-25 mph.

I here from a friend that they are cancelling some flights in Florida due to bonnie.

[Somerset Squall]

Bonnie has developed some impressive convection over the centre, and intensity has increased to 35kts based on recon data. The upper level low hindering Bonnie has put a bit more distance between itself and Bonnie, and this needs to be watched. The closer the ULL is to Bonnie, the higher the shear. There is a possibility the ULL could accelerate away from Bonnie, which would allow Bonnie to become much stronger than the NHC are forecasting. The current modest forecast peak of 45kts is based on the ULL moving in tandem with Bonnie across the Gulf Of Mexico.

Nice image there Cookie, shows Bonnie is developing quite rapidly from the mess the system was last night!!

[Somerset Squall]

Bonnie is a small storm with some persistant convection over the LLC, but little in the way of banding. Intensity has remained steady at 35kts. Bonnie is moving quite quickly and should make first landfall across the southern tip of Florida later this afternoon. Second landfall is still uncertain as yet, but Bonnie will remain intact to emerge in the GOM.

[Nick L]

Not even a breeze here in central Florida! The reporters on TWC in Miami and Key West showing a fairly calm scene.

[Somerset Squall]

Bonnie has accelerated over the past few hours, has made landfall and is now racing across land in Southern Florida. Bonnie is running along the southern side of a steering ridge to the north and on the northwest side of the upper level low in the GOM. Bonnie's faster track has placed the storm closer to the upper level low, which has increased the shear over Bonnie. This increase in shear has also meant that the dry air surrounding the storm has infiltrated closer to Bonnie's core, meaning the storm still only has a small convective canopy. The shear has also interupted Bonnie's circulation, which is much more distorted than before. The high shear and land interaction does actually put Bonnie at risk of dissipation, but it is likely that Bonnie will survive and take a speedy dip into the GOM then make landfall near New Orleans. Unless the shear eases, Bonnie is unlikely to get any stronger than the current 35kt intensity. Any strengthening will be very modest as long as Bonnie keeps chasing that upper level low.

[Cookie]

Poor Old Bonnie she has struggled a lot

[Katherine]

Bonnie's been downgraded to a Tropical Depression now - heard earlier of someone saying New Orleans had to prepare for a minimal hurricane!!!! A tad overhyped?

[summer blizzard]

Bonnie's been downgraded to a Tropical Depression now - heard earlier of someone saying New Orleans had to prepare for a minimal hurricane!!!! A tad overhyped?

It weakend due to land interaction, despite shear, i would be suprised if it does not strengthen to a Tropical Storm before landfall. It should make landfall in the next 18-24 hours.

[Cookie]

beautiful image of bonnie

[MAF]

latest from NOAA/NHC

DISCUSSION AND 48-HOUR OUTLOOK

------------------------------

AT 200 AM EDT...0600 UTC...THE CENTER OF TROPICAL DEPRESSION BONNIE

WAS LOCATED NEAR LATITUDE 26.7 NORTH...LONGITUDE 84.4 WEST. THE

DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST NEAR 17 MPH...

28 KM/HR. THIS GENERAL TRACK WITH A DECREASE IN FORWARD SPEED IS

EXPECTED TO CONTINUE DURING THE NEXT COUPLE OF DAYS. ON THE

FORECAST TRACK...BONNIE IS EXPECTED TO CROSS THE EASTERN GULF OF

MEXICO TODAY AND REACH THE NORTHERN GULF COAST SATURDAY NIGHT OR

EARLY SUNDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER

GUSTS. SLIGHT STRENGTHENING IS POSSIBLE TODAY...AND BONNIE

COULD REGAIN TROPICAL STORM STRENGTH BEFORE REACHING THE NORTHERN

GULF COAST.

THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY AN AIR FORCE RESERVE

HURRICANE HUNTER AIRCRAFT IS 1013 MB...29.91 INCHES.

HAZARDS AFFECTING LAND

----------------------

WIND...TROPICAL STORM FORCE WINDS MAINLY IN SQUALLS WILL LIKELY

BEGIN ALONG PORTIONS OF THE NORTHERN GULF COAST WITHIN THE WARNING

AREA LATE TODAY.

RAINFALL...BONNIE IS EXPECTED TO PRODUCE TOTAL RAINFALL

ACCUMULATIONS OF 1 TO 3 INCHES OVER PORTIONS OF SOUTHEASTERN

LOUISIANA...SOUTHERN ALABAMA...SOUTHERN MISSISSIPPI...AND THE FAR

WESTERN FLORIDA PANHANDLE...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS

OF 5 INCHES.

STORM SURGE...STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 2 TO

4 FEET ABOVE GROUND LEVEL ALONG THE IMMEDIATE COAST NEAR AND TO THE

RIGHT OF WHERE THE CENTER MAKES LANDFALL ON THE NORTHERN GULF

COAST.

[MAF]

Midday update looks like they will drop the tropical storm warning today

...BONNIE COULD DEGENERATE INTO AN AREA OF LOW PRESSURE...WARNINGS

WILL LIKELY BE DISCONTINUED LATER THIS MORNING...

SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION

----------------------------------------------

LOCATION...27.6N 86.1W

ABOUT 215 MI...345 KM ESE OF THE MOUTH OF THE MISSISSIPPI RIVER

ABOUT 160 MI...260 KM SSW OF APALACHICOLA FLORIDA

MAXIMUM SUSTAINED WINDS...30 MPH...50 KM/HR

PRESENT MOVEMENT...WNW OR 295 DEGREES AT 18 MPH...32 KM/HR

MINIMUM CENTRAL PRESSURE...1013 MB...29.91 INCHES

AT 700 AM CDT...1200 UTC...THE CENTER OF TROPICAL DEPRESSION BONNIE

WAS LOCATED NEAR LATITUDE 27.6 NORTH...LONGITUDE 86.1 WEST. THE

DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST NEAR 20 MPH...32

KM/HR. A GRADUAL DECREASE IN FORWARD SPEED IS EXPECTED TODAY WITH

LITTLE CHANGE IN THE DIRECTION OF MOTION. ON THIS TRACK...THE

CENTER OF BONNIE IS FORECAST TO APPROACH THE NORTHERN GULF COAST

TONIGHT.

SATELLITE IMAGES AND DATA FROM A RECONNAISSANCE PLANE INDICATE THAT

BONNIE HAS BECOME LESS ORGANIZED. MAXIMUM SUSTAINED WINDS HAVE

DECREASED TO ARE NEAR 30 MPH...50 KM/HR...WITH HIGHER GUSTS.

STRENGTHENING IS BECOMING LESS LIKELY.

THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY AN AIR FORCE

HURRICANE HUNTER AIRCRAFT IS 1013 MB...29.91 INCHES.

[CardiffStorm]

All warnings and watches were discontinued earlier by the NHC.

[Katherine]

Bonnie now officially dead. NHC issues final advisory.

[Cookie]

This could have been so much worse, if it wasn't for that ULL.

[Somerset Squall]

This could have been so much worse, if it wasn't for that ULL.

I agree. Bonnie was a small storm moving over very warm waters, so if the upper level enironment was favourable rapid intensification could have occured.

So, Bonnie doesn't make a second landfall and instead dissipates over the northern GOM. Bonnie's fast speed was really her downfall as it kept her close the ULL which caused persistantly high shear over the system.