Hurricane Hanna

[tinybill]

since her change of coarse last night will she do a sharp turn to the right and head in to the gulf of Mexico

Edited August 29, 2008 by tinybill

[Mondy]

No recon going into Hanna until Sunday.

[Somerset Squall]

Shear continues to batter Hanna. The storm is looking unimpressive this evening, with a partially exposed centre located on the western edge of some deep convection. Banding features are practically non-existant and Hanna is not expected to strengthen until this shear eases.

[Cookie]

I'm not getting any warnings either

[tinybill]

http://www.nhc.noaa.gov/graphics_at3.shtml...?large#contents

looks like the west indias are in for a hit before she get in ti the gulf of mexico

[summer blizzard]

000

WTNT43 KNHC 301447

TCDAT3

TROPICAL STORM HANNA DISCUSSION NUMBER 10

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082008

1100 AM EDT SAT AUG 30 2008

HANNA CONTINUES TO PRODUCE A LARGE AREA OF DEEP CONVECTION WITH

CLOUD TOP TEMPERATURES BELOW -80 DEGREES C. HOWEVER...THE CENTER OF

THE TROPICAL CYCLONE IS LOCATED NEAR THE SOUTHWESTERN EDGE OF THIS

CONVECTION. THE EXACT CENTER HAS BEEN DIFFICULT TO LOCATE AS A

COUPLE OF SMALL VORTICES HAVE BEEN SEEN ROTATING AROUND THE LARGER

CIRCULATION THIS MORNING. SATELLITE INTENSITY ESTIMATES REMAIN

T3.0 OR 45 KT AND AN EARLIER QUIKSCAT PASS SUGGEST MAXIMUM WINDS

WERE NEAR THAT VALUE. THERE WERE SOME STRONGER WINDS SEEN IN THE

QUIKSCAT DATA...BUT THESE WINDS WERE WELL REMOVED FROM THE CENTER

AND APPEAR TO HAVE BEEN RAIN-INFLATED.

THE SOMEWHAT UNCERTAIN INITIAL MOTION ESTIMATE IS 275/7. HANNA HAS

CONTINUED TO MOVE MORE WESTWARD DURING THE PAST 12-24 HOURS...WHICH

HAS REQUIRED A LITTLE SOUTHWARD ADJUSTMENT TO THE TRACK FORECAST IN

THE SHORT-TERM. THE TRACK GUIDANCE PREDICTS A GENERAL WEST TO

WEST-NORTHWEST MOTION DURING THE NEXT 24-36 HOURS. THEREAFTER...

THERE IS A GREAT DEAL OF SPREAD AMONG THE MODELS...AS A STRONG HIGH

PRESSURE RIDGE BUILDS OVER THE EASTERN UNITED STATES. THE GFDL AND

HWRF RESPOND BY SHOWING A VERY SLOW AND ERRATIC MOTION IN ABOUT 3

DAYS...WHILE THE UKMET TURNS HANNA SOUTHWESTWARD TOWARDS EASTERN

CUBA. VERY LATE IN THE PERIOD...THE HIGH OVER THE EASTERN U.S. IS

FORECAST TO MOVE OFF THE EAST COAST INTO THE WESTERN ATLANTIC AND

SEVERAL OF THE FORECAST MODELS NOW INDICATE A WEST-NORTHWESTWARD

AROUND DAY 5. THE NEW FORECAST WHICH IS VERY SIMILAR TO THE

PREVIOUS ADVISORY...BUT SMOOTHS THROUGH THESE POSSIBLE UNDULATIONS

AND SHOWS A SLOW WESTWARD MOTION BETWEEN 72-120 HOURS. THE NEW

TRACK IS GENERALLY ALONG OR JUST SOUTH OF THE MODEL CONSENSUS.

THE MUCH DISCUSSED UPPER-LOW JUST WEST OF THE STORM APPEARS TO HAVE

WEAKENED A LITTLE THIS MORNING. THE SHIPS GUIDANCE SUGGESTS THE

WESTERLY SHEAR MAY RELAX JUST A LITTLE OVER THE NEXT 24 HOURS.

GIVEN THE RESILIENCE OF HANNA...THE OFFICIAL FORECAST SHOWS A

LITTLE STRENGTHENING DURING THE NEXT DAY OR SO.

THEREAFTER...STRONG NORTHWEST TO NORTH UPPER-LEVEL WINDS ARE

FORECAST...SO THE OFFICIAL INTENSITY FORECAST NOW KEEPS HANNA JUST

BELOW HURRICANE STRENGTH. IT SHOULD BE NOTED ONCE AGAIN...THAT THE

NHC INTENSITY FORECAST REMAINS BELOW ALL OF THE RELIABLE GUIDANCE.

BASED ON THE NEW FORECAST TRACK...THE GOVERNMENT OF THE BAHAMAS HAS

ISSUED A TROPICAL STORM WATCH FOR THE SOUTHEASTERN BAHAMAS AND

TURKS AND CAICOS ISLANDS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 30/1500Z 21.9N 66.4W 45 KT

12HR VT 31/0000Z 22.4N 67.9W 50 KT

24HR VT 31/1200Z 22.9N 69.6W 55 KT

36HR VT 01/0000Z 23.2N 71.0W 60 KT

48HR VT 01/1200Z 23.2N 72.1W 60 KT

72HR VT 02/1200Z 23.0N 73.5W 55 KT

96HR VT 03/1200Z 23.0N 75.0W 55 KT

120HR VT 04/1200Z 23.0N 76.5W 55 KT

$$

FORECASTER BROWN

http://www.nhc.noaa.gov/refresh/graphics_a...l?5day#contents

Forget Gust, this is Rita 2005 all over again!

[Cookie]

update

Storm Alert issued at 30 Aug, 2008 15:00 GMT

Tropical Storm HANNA is forecast to strike land to the following likelihood(s) at the given lead time(s):

Green Alert Country(s) or Province(s)

the Turks & Caicos Islands

probability for TS is 45% in about 45 hours

the Bahamas

probability for TS is 40% in about 45 hours

Green Alert City(s) and Town(s)

Grand Turk (21.5 N, 71.5 W)

probability for TS is 40% in about 45 hours

Note that

Green Alert (Low) is TS to between 31% and 50% probability.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

[Somerset Squall]

The long range forecast for Hanna is very uncertain, it much depends on interaction with that upper level low and also just how close it gets to Gustav. If it gets too close, shear will remain strong. Shear is still strong over the storm now, and therefore Hanna hasn't strengthened at all today, and remains at 45kts. If the upper level low moves away, shear may ease but the NHC predict shear to be strong throughout the next 5 days. I don't think much will happen with Hanna until (if it does) it moves into the Gulf Of Mexico.

[Cookie]

yeah It dosen't look great at the moment

[summer blizzard]

Tropical Storm Hanna appears to have murged with the upper level low and has become more sub-Tropical in nature, however once Gustav makes landfall late tommorow, shear will ease and should Hannah move west, Gustav will have left an abundance of moisture, though once stalling occurs there is likely to be a north westward track so after the Florida hit, there is no gurantee of re-entry..

My punt: Florida landfall as a strengthening category 2/3 hurricane...

Don't expect to see any real development until tuesday by which time Gustav and his remains will of gotten out of the way.

[Cookie]

new update

Storm Alert issued at 31 Aug, 2008 9:00 GMT

Tropical Storm HANNA is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

the Turks & Caicos Islands

probability for TS is 55% in about 33 hours

the Bahamas

probability for TS is 55% in about 45 hours

Yellow Alert City(s) and Town(s)

Grand Turk (21.5 N, 71.5 W)

probability for TS is 55% in about 45 hours

Green Alert City(s) and Town(s)

San Salvador (24.0 N, 74.5 W)

probability for TS is 45% in about 45 hours

Note that

Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.

Green Alert (Low) is TS to between 31% and 50% probability.

CAT 1 means Hurricane strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

[Jack Wales]

Who'd have thought Hanna would become more organised than Gustav?

That's what's happening.. Hanna forecast to be a hurricane

I wouldn't say better organised plus with very strong northerly shear progged over the region, Hannah's future is very much in the balance at the moment. If she can get through the next two days or so without being sheared apart then conditions should be favourable for rapid strengthening.

[Somerset Squall]

The hostile environment continues to hinder Hanna, and intensity has decreased to 35kts, barely a tropical storm. Hanna has a couple more days to survive before there is any possibility of better conditions. Hanna looks very messy this evening and if this trend continues Hanna may even weaken to a tropical depression.

Interesting comments from NHC:

LONG-PERIOD SWELLS FROM HANNA ARE EXPECTED TO INCREASE THE RISK

OF DANGEROUS RIP CURRENTS ALONG PORTIONS OF THE SOUTHEASTERN

UNITED STATES COAST DURING THE NEXT COUPLE OF DAYS.

The Bahamas are also under a tropical storm warning as Hanna gets ever closer.

[Cookie]

The hostile environment continues to hinder Hanna, and intensity has decreased to 35kts, barely a tropical storm. Hanna has a couple more days to survive before there is any possibility of better conditions. Hanna looks very messy this evening and if this trend continues Hanna may even weaken to a tropical depression.

Interesting comments from NHC:

The Bahamas are also under a tropical storm warning as Hanna gets ever closer.

do you think she would have faired better if gustov hadn't existed?

[summer blizzard]

While Hannah is'nt well developed at the moment i think her future is not that bad, because right now she has an upper low moving east, away from her, with gustav also proving some shear, however with Gustav forecast to hit land and weaken from tommorow, this will mean less shear ahead of her and as she picks up forward momentum shear will relax from the upper low, which will mean that from tuesday onward, conditions will improve significantly for her however, unfortunately i do not see her bombing out in the GUM if she makes it past Florida as the upper low which has imparted shear over Gustav today will then make things difficult for Hannah should she reach the GUM.

In summary, i do see Hannah becoming a hurricane on wednesday, probably making landfall in Florida as a strengthening category 2 hurricane.

[Somerset Squall]

do you think she would have faired better if gustov hadn't existed?

It's hard to say. The upper level low to the north is what has hammered Hanna the most, but Gustav isn't helping either. As Hanna gets closer to Gustav, his outflow is playing a bigger role in shearing Hanna. If Gustav wasn't there, Hanna would be sheared anyway by the upper level low. Hanna might fair better in the future if Gustav wasn't there as the upper level low is forcast to weaken but the shear will remain strong for as long as Gustav remains strong.

[summer blizzard]

Indeed, i don't think it would of made much of a difference to things upto say a day or so, if Gustav was'nt there, she may have started developing.

[Jack Wales]

I think Hannah is just far enough away to avoid being affected by the outflow from Gustav, she's still experiencing northerly shear but hanging in there. Latest from NHC...

000

WTNT43 KNHC 312038

TCDAT3

TROPICAL STORM HANNA DISCUSSION NUMBER 15

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082008

500 PM EDT SUN AUG 31 2008

AN AIR FORCE RECONNAISSANCE AIRCRAFT INVESTIGATING HANNA DURING THE

LAST SEVERAL HOURS FOUND A PEAK FLIGHT LEVEL WIND OF 48 KT WHICH

REDUCES TO APPROXIMATELY 40 KT AT THE SURFACE. WHILE THERE WERE A

FEW HIGHER VALUES FROM THE SFMR...THESE WERE LIKELY RAIN INFLATED.

THE OVERALL INTENSITY FORECAST REASONING IS ESSENTIALLY UNCHANGED.

HANNA IS CURRENTLY EXPERIENCING STRONG NORTHERLY SHEAR ASSOCIATED

WITH AN UPPER-LEVEL LOW TO ITS SOUTHEAST. GLOBAL MODELS DO

FORECAST THIS UPPER-LEVEL LOW TO WEAKEN OVER THE NEXT DAY OR SO.

HOWEVER...STRONG NORTHERLY FLOW ASSOCIATED WITH GUSTAV'S

UPPER-LEVEL OUTFLOW SHOULD KEEP NORTHERLY SHEAR OVER HANNA THROUGH

DAY 3. BY DAYS 4 AND 5...DYNAMICAL MODELS FORECAST A SOMEWHAT

IMPROVED ENVIRONMENT AS A SECOND UPPER-LEVEL LOW OR CYCLONIC SHEAR

AXIS FORMS TO THE WEST OF HANNA. THIS WOULD PUT HANNA IN A MORE

FAVORABLE ENVIRONMENT FOR STRENGTHENING. HOWEVER...ACCURATELY

PREDICTING HANNA'S PROXIMITY TO LARGE-SCALE ATMOSPHERIC FEATURES AT

DAYS 4 AND 5 IS DIFFICULT...TO SAY THE LEAST. GIVEN THE

UNCERTAINTY...THE OFFICIAL FORECAST SHOWS SLOW STRENGTHENING...BUT

IS BELOW THE INTENSITY MODEL CONSENSUS.

HANNA CONTINUES TO BE STEERED BY A MID-LEVEL RIDGE OVER THE WESTERN

ATLANTIC...RESULTING IN A MOTION TOWARD THE WEST OR 280/09. GLOBAL

MODELS INDICATE THIS RIDGE WILL WEAKEN DURING THE NEXT DAY OR SO AS

A LARGE DEEP-LAYER TROUGH AMPLIFIES SOUTHWARD OVER THE WESTERN

ATLANTIC. SUCH AN EVOLUTION IN THE LARGE-SCALE PATTERN SHOULD CAUSE

THE STEERING CURRENTS TO COLLAPSE RESULTING IN A DECREASE IN

HANNA'S FORWARD SPEED. IN FACT...SOME OF THE MODELS SHOW HANNA

MEANDERING OVER OR JUST NORTHEAST OF THE CENTRAL BAHAMAS. BY DAY

3...THE DEEP-LAYER TROUGH IS FORECAST TO LIFT NORTHEASTWARD

ALLOWING THE SUBTROPICAL RIDGE TO BUILD BACK WESTWARD IN ITS WAKE.

THERE REMAINS CONSIDERABLE SPREAD AMONG THE DYNAMICAL MODELS AT THE

EXTENDED RANGE. THE GFS...GFDL...AND THE HWRF MODELS LIE ALONG THE

RIGHT SIDE OF THE MODEL ENVELOPE AND SHOW HANNA LIFTING QUICKLY

NORTHWESTWARD AROUND THE WESTERN PERIPHERY OF THE RIDGE.

CONVERSELY...THE UKMET MODEL SHOWS THE RIDGE NOSING WESTWARD TO THE

NORTH OF HANNA...PRODUCING A TRACK ALONG THE LEFT...OR

SOUTHWEST...SIDE OF THE MODEL ENVELOPE. SINCE THERE IS NO CLEAR

REASON TO FAVOR ONE SCENARIO OVER THE OTHER AT THIS TIME...I'VE

ELECTED TO LEAVE THE OFFICIAL FORECAST ESSENTIALLY UNCHANGED BEYOND

72 HOURS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 31/2100Z 23.5N 71.4W 40 KT

12HR VT 01/0600Z 23.5N 72.3W 40 KT

24HR VT 01/1800Z 23.3N 73.1W 45 KT

36HR VT 02/0600Z 23.3N 73.7W 50 KT

48HR VT 02/1800Z 23.5N 74.1W 55 KT

72HR VT 03/1800Z 24.5N 75.0W 60 KT

96HR VT 04/1800Z 27.5N 77.5W 65 KT

120HR VT 05/1800Z 31.5N 81.0W 65 KT

$$

FORECASTER RHOME

[Cookie]

thanks somerset for answering my question

Storm Alert issued at 31 Aug, 2008 21:00 GMT

Tropical Storm HANNA is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

the Bahamas

probability for TS is 80% within 9 hours

the Turks & Caicos Islands

probability for TS is 70% within 9 hours

Yellow Alert City(s) and Town(s)

San Salvador (24.0 N, 74.5 W)

probability for TS is 60% in about 21 hours

Freeport (26.6 N, 78.6 W)

probability for CAT 1 or above is 10% in about 93 hours

probability for TS is 20% in about 93 hours

Green Alert City(s) and Town(s)

Grand Turk (21.5 N, 71.5 W)

probability for TS is 40% currently

Note that

Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.

Green Alert (Low) is TS to between 31% and 50% probability.

CAT 1 means Hurricane strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

[Iceberg]

TS Hanna has been on fire today with cloud temps touching -90C, the picture shows where the centre is by the big black line, also the close bouy(the black dot).

The bouy has been measuring pressure down to 996mb and winds sustained of 37Kt and gusts to 48Kts, it's still 80 miles away from the centre and would indicate a lower centre and winds maybe 10Kt shy of a hurricane or higher.

Recon is due to go in this afternoon.

Path for Hanna is to blast the Bahamas and then shoot up to North Florida or the Carolina's as anything from a CAT 2 to a CAT 3. this really will be interesting to watch.

[kold weather]

Best track shows winds now upped to 50kts in light of a ship report showing 48kts winds sustained.

Qscat scan shows Hanna's circulation is nearly in the center of the deep convection which suggests its undergone relocation of the LLC into the massive deep burst of convection.

The key now to watch is the shear slowly decrease. The main issue for Hanna has always been Gustav's outflow causing some pretty bad shear but now Gustav is moving inland it will weaken quite quickly and the outflow will reduce with it thus reducing the shear. Indeed conditions should be favorable for decent strengthening in about 48hrs and give nthe sheer explosive qualities the convection has had in the last 36hrs I think the idea that this is a hurricane heading towards the region between North Florida and North Carolina is looking very likely, category-2 is quite possible as well over the gulf stream providing its still over water in 72hrs time when upper conditions really do get condusive.

[Iceberg]

NHC agree Kold, the LLCC might well have relocated a bit, it will be interesting to find out what recon comes back with over the next few hours.

HANNA'S OVERALL SATELLITE PRESENTATION HAS BEEN IMPROVING THIS

MORNING WITH AN IMPRESSIVE CDO FEATURE NOW COVERING THE LOW-LEVEL

CIRCULATION. DVORAK SATELLITE INTENSITY ESTIMATES HAVE INCREASED

AND SUGGEST MAX WINDS NEAR 55 KT. I'M GOING TO CONSERVATIVELY SET

THE INITIAL INTENSITY TO 50 KT SINCE AN AIR FORCE RECONNAISSANCE

AIRCRAFT IS ON ITS WAY. HAVING SAID THAT...A RECENT QUIKSCAT PASS

SUGGEST THAT THE LOW-LEVEL CIRCULATION COULD BE LOCATED A LITTLE

FARTHER INTO THE DEEP CONVECTION. THIS SUGGEST THAT HANNA COULD BE

STRONGER THAN ESTIMATED. THE INTENSITY FORECAST REMAINS TRICKY.

WATER VAPOR IMAGERY SUGGESTS THAT THE UPPER-LEVEL LOW WHICH HAD

PREVIOUSLY INHIBITED DEVELOPMENT HAS DISSIPATED...AND HANNA NOW

FINDS ITSELF IN A VERY SMALL AREA OF LOW SHEAR. HOWEVER...WATER

VAPOR IMAGERY ALSO SHOWS STRONG NORTHERLY FLOW ASSOCIATED WITH

GUSTAV'S UPPER-LEVEL OUTFLOW JUST NORTH OF HANNA...AND GLOBAL MODELS

FORECAST MODERATE TO STRONG NORTHERLY SHEAR PERSISTING DURING THE

NEXT DAY OR SO. GIVEN THE UNCERTAINTY...THE OFFICIAL INTENSITY

FORECAST IS CLOSE TO THE MODEL CONSENSUS AND SHOWS HANNA BECOMING A

HURRICANE A LITTLE SOONER THAN THE PREVIOUS ADVISORY. BY 72

HOURS...GLOBAL MODELS SUGGEST THE SHEAR COULD WEAKEN...AND HANNA

COULD FIND ITSELF IN A MORE FAVORABLE ENVIRONMENT FOR

STRENGTHENING. STILL...PREDICTING THE ATMOSPHERIC ENVIRONMENT...

AND TROPICAL CYCLONE INTENSITY...AT DAYS 3-5 IS VERY DIFFICULT.

[knightstorm]

Judging by this I'd say mainland Florida is in the firing line for this one!

[Mondy]

Storm Name: Hanna (in the North Atlantic basin)

Mission Number: 2

Observation Number: 05

A. Time of Center Fix: 1st day of the month at 15:25:20Z

B. Center Fix Coordinates: 22°37'N 72°26'W (22.6167N 72.4333W)

B. Center Fix Location: 115 miles (186 km) to the NW (314°) from Cockburn Town, Turks and Caicos Islands (GBR).

C. Minimum Height at Standard Level: 1,314m (4,311ft) at 850mb

D. Estimated (by SFMR or visually) Maximum Surface Wind: 48kts (~ 55.2mph)

E. Location of the Estimated Maximum Surface Wind: 31 nautical miles (36 statute miles) to the WNW (296°) of center fix

F. Maximum Flight Level Wind Inbound: From 54° at 59kts (From the NE at ~ 67.9mph)

G. Location of Maximum Flight Level Wind Inbound: 71 nautical miles (82 statute miles) to the NW (306°) of center fix

H. Minimum Sea Level Pressure: 986mb (29.12 inHg)

I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 17°C (63°F) at a pressure alt. of 1,521m (4,990ft)

J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 21°C (70°F) at a pressure alt. of 1,523m (4,997ft)

K. Dewpoint Temp (collected at same location as temp inside eye): 18°C (64°F)

K. Sea Surface Temp (collected at same location as temp inside eye): Not Available

L. Eye Character: Not Available

M. Eye Shape: Not Available

N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature

N. Fix Level: 850mb

O. Navigation Fix Accuracy: 0.02 nautical miles

O. Meteorological Accuracy: 2 nautical miles

Remarks Section:

Maximum Flight Level Wind: 59kts (~ 67.9mph) in the northwest quadrant at 15:03:10Z

Maximum Flight Level Temp: 22°C (72°F) which was observed 42 nautical miles (48 statute miles) to the WNW (299°) from the flight level center

[Coast]

The various model tracks have her just missing the East Florida coast and heading up to South & North Carolina