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Hurricane Hanna


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Posted
  • Location: Dorset
  • Location: Dorset

    Now named and being issued.

    This is forecast to go to hurricane strength as well by the NHC.

    THE AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE THAT HAS

    BEEN TRACKED WESTWARD ACROSS THE TROPICAL ATLANTIC FOR THE PAST

    SEVERAL DAYS HAS DEVELOPED ENOUGH SURFACE CIRCULATION AND DEEP

    ORGANIZED CONVECTION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A

    SHIP VERY NEAR THE CENTER ALSO REPORTED A PRESSURE OF 1005 MB NEAR

    THE CENTER. DVORAK T-NUMBERS FROM BOTH TAFB AND SAB ARE 2.5 AND 3.0

    RESPECTIVELY. INITIAL INTENSITY HAS BEEN SET AT 30 KNOTS. ALTHOUGH

    THE CENTER IS ESTIMATED TO BE ON THE NORTHWESTERN PORTION OF THE

    CONVECTION...THE PREVAILING NORTHWESTERLY SHEAR OVER THE CYCLONE

    HAS BEEN GRADUALLY ABATING AND THE OUTFLOW IS BECOMING ESTABLISHED

    IN ALL QUADRANTS. MOST OF THE GLOBAL MODELS SUGGEST THAT RIDGING

    WILL PREVAIL ALOFT...RESULTING IN AN ENVIRONMENT OF LIGHT SHEAR. A

    GRADUAL INTENSIFICATION IS FORECAST IN AGREEMENT WITH THE SHIPS

    INTENSITY MODEL...AND THE DEPRESSION WILL LIKELY BECOME A TROPICAL

    STORM LATER TODAY AND COULD REACH HURRICANE INTENSITY IN 3 DAYS.

    THE HWRF AND GFDL MODELS ARE MORE AGGRESSIVE...PREDICTING AN

    INTENSE HURRICANE.

    THE DEPRESSION IS MOVING TOWARD THE NORTHWEST OR 305 DEGREES AT 5

    KNOTS WHILE EMBEDDED WITHIN VERY LIGHT STEERING CURRENTS. THE LARGE

    TROUGH CURRENTLY LOCATED OVER THE WESTERN ATLANTIC IS FORECAST TO

    BE REPLACED BY A LARGE SUBTROPICAL RIDGE OVER THE NEXT FEW DAYS.

    THIS PATTERN SHOULD FORCE THE CYCLONE TO TAKE A MORE WEST-NORTHWEST

    TRACK IN A DAY OR SO. THE FLOW AROUND AN UPPER-LOW JUST NORTH OF

    PUERTO RICO COULD ALSO INDUCE SOME WESTWARD COMPONENT OVER THE NEXT

    FEW DAYS. BY THE END OF THE FORECAST PERIOD...THE STEERING FLOW IS

    EXPECTED TO WEAKEN AND THE CYCLONE COULD MEANDER FOR A WHILE. THE

    TRACK FORECAST IS BASICALLY IN THE MIDDLE OF THE GUIDANCE ENVELOPE

    WHICH INDEED SHOWS A WESTWARD TRACK BEYOND 4 DAYS.

    FORECAST POSITIONS AND MAX WINDS

    INITIAL 28/0900Z 19.8N 57.9W 30 KT

    12HR VT 28/1800Z 20.5N 58.8W 35 KT

    24HR VT 29/0600Z 22.0N 60.5W 40 KT

    36HR VT 29/1800Z 23.5N 62.5W 45 KT

    48HR VT 30/0600Z 25.0N 64.5W 55 KT

    72HR VT 31/0600Z 26.0N 67.0W 70 KT

    96HR VT 01/0600Z 27.0N 69.0W 75 KT

    120HR VT 02/0600Z 27.0N 70.5W 75 KT

    THE AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE THAT HAS

    BEEN TRACKED WESTWARD ACROSS THE TROPICAL ATLANTIC FOR THE PAST

    SEVERAL DAYS HAS DEVELOPED ENOUGH SURFACE CIRCULATION AND DEEP

    ORGANIZED CONVECTION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A

    SHIP VERY NEAR THE CENTER ALSO REPORTED A PRESSURE OF 1005 MB NEAR

    THE CENTER. DVORAK T-NUMBERS FROM BOTH TAFB AND SAB ARE 2.5 AND 3.0

    RESPECTIVELY. INITIAL INTENSITY HAS BEEN SET AT 30 KNOTS. ALTHOUGH

    THE CENTER IS ESTIMATED TO BE ON THE NORTHWESTERN PORTION OF THE

    CONVECTION...THE PREVAILING NORTHWESTERLY SHEAR OVER THE CYCLONE

    HAS BEEN GRADUALLY ABATING AND THE OUTFLOW IS BECOMING ESTABLISHED

    IN ALL QUADRANTS. MOST OF THE GLOBAL MODELS SUGGEST THAT RIDGING

    WILL PREVAIL ALOFT...RESULTING IN AN ENVIRONMENT OF LIGHT SHEAR. A

    GRADUAL INTENSIFICATION IS FORECAST IN AGREEMENT WITH THE SHIPS

    INTENSITY MODEL...AND THE DEPRESSION WILL LIKELY BECOME A TROPICAL

    STORM LATER TODAY AND COULD REACH HURRICANE INTENSITY IN 3 DAYS.

    THE HWRF AND GFDL MODELS ARE MORE AGGRESSIVE...PREDICTING AN

    INTENSE HURRICANE.

    THE DEPRESSION IS MOVING TOWARD THE NORTHWEST OR 305 DEGREES AT 5

    KNOTS WHILE EMBEDDED WITHIN VERY LIGHT STEERING CURRENTS. THE LARGE

    TROUGH CURRENTLY LOCATED OVER THE WESTERN ATLANTIC IS FORECAST TO

    BE REPLACED BY A LARGE SUBTROPICAL RIDGE OVER THE NEXT FEW DAYS.

    THIS PATTERN SHOULD FORCE THE CYCLONE TO TAKE A MORE WEST-NORTHWEST

    TRACK IN A DAY OR SO. THE FLOW AROUND AN UPPER-LOW JUST NORTH OF

    PUERTO RICO COULD ALSO INDUCE SOME WESTWARD COMPONENT OVER THE NEXT

    FEW DAYS. BY THE END OF THE FORECAST PERIOD...THE STEERING FLOW IS

    EXPECTED TO WEAKEN AND THE CYCLONE COULD MEANDER FOR A WHILE. THE

    TRACK FORECAST IS BASICALLY IN THE MIDDLE OF THE GUIDANCE ENVELOPE

    WHICH INDEED SHOWS A WESTWARD TRACK BEYOND 4 DAYS.

    FORECAST POSITIONS AND MAX WINDS

    INITIAL 28/0900Z 19.8N 57.9W 30 KT

    12HR VT 28/1800Z 20.5N 58.8W 35 KT

    24HR VT 29/0600Z 22.0N 60.5W 40 KT

    36HR VT 29/1800Z 23.5N 62.5W 45 KT

    48HR VT 30/0600Z 25.0N 64.5W 55 KT

    72HR VT 31/0600Z 26.0N 67.0W 70 KT

    96HR VT 01/0600Z 27.0N 69.0W 75 KT

    120HR VT 02/0600Z 27.0N 70.5W 75 KT

    v

    Sat picture

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    Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada

    This one will probably become Hanna then ... if memory serves me right, tonight will be the third anniversary of Katrina's landfall, so we are not that far off the pace of the record year of 2005 if by tonight we have an 8th named storm.

    Gustav and Hanna ... could be as big a power couple as the Clintons, if they deepen in phase then some comparisons to the very active map of 1 September 1950 might be in order. I think that was the date when there was the most activity on one map at one moment in time.

    I think Hanna could end up in the Carolinas about the same time that Gustav is making a run towards the Gulf coast (probably west of central LA the way things are shaping up). Two major landfalling hurricanes in the same week? Something to watch.

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    Posted
  • Location: Liphook
  • Location: Liphook

    Indeed very likely to be Hanna. There is some shear still with this system and it'll only slowly ease off I suspect but the ULL is now decaying at a deecent rate it seems.

    Track suggests NW for the enxt 72hrs then as it gets clsoe to 70W the big upper high that has forced Gustav to move WSW should force a similar sort of motion to occur with Td8. Indeed a few models have a very sharp dive which is possible given what we've seen with Gustav overnight.

    Two hurricanes threatening the USA in the space of 10 days...amazing but very possible!

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    Posted
  • Location: Boston, Lincolnshire, UK
  • Location: Boston, Lincolnshire, UK
    Gustav and Hanna ... could be as big a power couple as the Clintons

    That sounds like something Jeremy Clarkson might say! :)

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    Posted
  • Location: cotswolds
  • Location: cotswolds

    Well as Hanna is now upgraded to a tropical storm I thought we should have a new thread. I have to say the proposed current track looks a tad worrying for Florida. A very busy storm season at the moment.

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    Posted
  • Location: Warwick and Hull
  • Location: Warwick and Hull

    Very true LS. There's an entire line of systems across the atlantic at the moment (although only Gustav and Hanna are classified systems). We had the most active July for 3 years (and 2005 was the most active to begin with), this could be a very active season, but hopefully the damage won't be too severe.

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    Posted
  • Location: cotswolds
  • Location: cotswolds

    yes lets hope it wont be too bad damage wise. my concern is that hanna is heading for a similar track to katrina. a long way off and no doubt different upper level conditions. katrina slammed into southern florida and went bang when it emerged into the carribean. with gustav probably about to bomb out post jamaica, its all a bit alarming

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    Posted
  • Location: New Ash green 150M / 500 FT
  • Location: New Ash green 150M / 500 FT
    yes lets hope it wont be too bad damage wise. my concern is that hanna is heading for a similar track to katrina. a long way off and no doubt different upper level conditions. katrina slammed into southern florida and went bang when it emerged into the carribean. with gustav probably about to bomb out post jamaica, its all a bit alarming

    hanna has been sheared to bits- goodnight vienna.....

    S

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset
    hanna has been sheared to bits- goodnight vienna.....

    S

    Indeed Steve, Hanna is going to remain weak for now as shear is badly affecting her. The LLC is entirely exposed looking at latest satellite imagery as strong westerly shear continues to batter the storm.

    post-1820-1219946803_thumb.jpg

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    Posted
  • Location: ipswich <east near the a14> east weather watch
  • Location: ipswich <east near the a14> east weather watch

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

    looks like its turning and heading for melbourne/orlando area if my eye of the storm program right to-night

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    Posted
  • Location: SE London
  • Location: SE London
    hanna has been sheared to bits- goodnight vienna..... S
    The shear is due to ease up in 36-48 hrs time. She needs to hang on and rely on some good diurnal convection to last her out.

    latest discussion from NOAA agrees too

    AFTER LOOKING QUITE IMPRESSIVE IN SATELLITE IMAGERY THIS

    MORNING...VERTICAL SHEAR HAS TAKEN ITS TOLL ON HANNA AND THE

    LOW-LEVEL CIRCULATION HAS BECOME COMPLETELY EXPOSED. WHILE IT IS

    TEMPTING TO LOWER THE INTENSITY BASED ON THIS TREND...IT IS BEST TO

    KEEP HANNA AS A MINIMAL TROPICAL STORM FOR THIS ADVISORY. THE LACK

    OF ORGANIZATION NOTWITHSTANDING...THE OVERALL FORECAST PHILOSOPHY

    REMAINS UNCHANGED. DYNAMICAL MODELS INSISTS THAT THE UPPER-LEVEL

    LOW CURRENTLY IMPARTING WESTERLY SHEAR OVER HANNA WILL BEGIN TO MOVE

    WESTWARD ALLOWING A MORE FAVORABLE ENVIRONMENT FOR STRENGTHENING TO

    DEVELOP OVER THE CYCLONE. SIMILARLY...THE SHIPS AND LGEM MODELS

    ARE BASING THEIR FORECAST ON A LOW SHEAR ENVIRONMENT. ANALYSIS OF

    WATER VAPOR IMAGERY INDICATES THAT THE UPPER-LEVEL LOW HAS NOT

    BUDGED ALL DAY SO IT WOULD APPEAR THAT THE SHEAR WILL NOT RELAX IN

    THE SHORT-TERM. THIS IS THE BASIS FOR THE NEW OFFICIAL FORECAST

    WHICH IS BELOW THE INTENSITY MODEL CONSENSUS. IF THE UPPER-LOW

    DOES EVENTUALLY MOVE OUT OF HANNA'S WAY...ENVIRONMENTAL CONDITIONS

    WOULD FAVOR STRENGTHENING. BY DAY 5...UPPER-LEVEL OUTFLOW FROM

    GUSTAV COULD IMPART NORTHERLY SHEAR OVER HANNA POSSIBLY AFFECTING

    THE INTENSITY.

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    Posted
  • Location: Dorset
  • Location: Dorset

    She seems to be doing rather well in the diurnal maximum time again. Convection has flared over the centre as per the NHC's comments. It's difficult to tell whether it's purly a big flare up of convection or whether the shear has eased a little, shear was due to eas by the end of today according to GDL and HWRF anyway.

    The intensity has been upped and she is still odd's on to become a hurricane.

    AFTER WESTERLY MID- TO UPPER-LEVEL SHEAR PRODUCED AN EXPOSED

    LOW-LEVEL CIRCULATION CENTER...CONVECTION HAS REDEVELOPED WITH A

    VENGEANCE OVER OR NEAR THE CENTER CONTAINING CLOUD TOPS AS COLD AS

    -83C. HOWEVER...THE CONVECTIVE DEVELOPMENT APPEARS TO BE A BURSTING

    PATTERN...WHICH IS USUALLY SHORT-LIVED. THE ADVISORY INTENSITY IS

    45 KT BASED ON A DVORAK T-NUMBER OF T3.0/45 KT FROM TAFB AND THE

    CONTINUED CONVECTIVE DEVELOPMENT SINCE THE 00Z SATELLITE FIX TIME.

    INITIAL 29/0300Z 21.1N 60.6W 45 KT

    12HR VT 29/1200Z 21.8N 62.0W 50 KT

    24HR VT 30/0000Z 23.2N 64.2W 55 KT

    36HR VT 30/1200Z 24.6N 66.3W 60 KT

    48HR VT 31/0000Z 25.7N 68.0W 70 KT

    72HR VT 01/0000Z 26.6N 70.0W 80 KT

    96HR VT 02/0000Z 26.5N 71.2W 80 KT

    120HR VT 03/0000Z 26.0N 71.6W 75 KT

    The Meto although not the most reliable model shows what Hanna could become if she doesn't stall and enters the caribbean at day 5.

    ATCF IDENTIFIER : AL082008

    VERIFYING TIME POSITION STRENGTH TENDENCY

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

    00UTC 29.08.2008 21.5N 59.9W WEAK

    12UTC 29.08.2008 22.6N 62.0W MODERATE INTENSIFYING SLIGHTLY

    00UTC 30.08.2008 23.4N 64.3W MODERATE INTENSIFYING SLIGHTLY

    12UTC 30.08.2008 24.6N 66.7W MODERATE LITTLE CHANGE

    00UTC 31.08.2008 25.6N 68.9W MODERATE LITTLE CHANGE

    12UTC 31.08.2008 26.1N 70.5W MODERATE LITTLE CHANGE

    00UTC 01.09.2008 26.0N 71.7W MODERATE INTENSIFYING SLIGHTLY

    12UTC 01.09.2008 26.0N 72.3W MODERATE LITTLE CHANGE

    00UTC 02.09.2008 25.6N 73.0W MODERATE INTENSIFYING SLIGHTLY

    12UTC 02.09.2008 25.0N 74.4W STRONG INTENSIFYING SLIGHTLY

    00UTC 03.09.2008 24.2N 75.8W STRONG INTENSIFYING SLIGHTLY

    12UTC 03.09.2008 23.9N 77.5W INTENSE INTENSIFYING SLIGHTLY

    00UTC 04.09.2008 23.4N 79.2W INTENSE INTENSIFYING SLIGHTLY

    Intense = Major Jurricane CAT 3,4 or 5.

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    Posted
  • Location: Greenhithe, N/W Kent (home) City Of London (work)
  • Location: Greenhithe, N/W Kent (home) City Of London (work)
    HWRF produces a big hurricane sub 890 pressure and a boardline CAT 5. Probably only an outside chance at the moment, but again shows the potential.

    Strange to think that earlier shear almost done for this storm

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    Posted
  • Location: Eastbourne, East Sussex (work in Mid Sussex)
  • Location: Eastbourne, East Sussex (work in Mid Sussex)

    I don't think she's going to be a strong as Gustav and the track looks to turn to the Bahamas on Tuesday according to the NHC:

    Other models are all over the place for the track on Tuesday

    hurricane_track_models_2.jpg

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    Posted
  • Location: Warwick and Hull
  • Location: Warwick and Hull

    I have my doubts at how accurate HWRF is this year... it seems to significantly over-estimate the pressures for these storms, either that or it's under estimating the winds, which i would hope isn't the case.

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    Posted
  • Location: Dorset
  • Location: Dorset

    I'd agree with that HWRF tends to keep hurricanes small and simple and perfectly round.! which means that pressure flucuations arn't very realistic. It is a useful guide though particularly to winds as KW says.

    Looking at the latest available models for Hanna and her current condition things seem to be there for something quite extraordinary and very scary.

    She currently looks very good IMO all things considered. She obviously has good structure and the right about of instability to generate the convection. Even in a far from brill environment she looks like reaching cane status. The problems come when she reaches favourable conditions.

    The globals are all keen to bend her into the Caribbean and or the Florida straights. Once here they all make her very strong indeed, this is backed up by the 00Z HWRF and also the latest 06Z from GFDL. She also looks likely to hit Florida, or Cuba or LA again. She is forecast to be a Major hurricane by almost every model once she gets into favourable conditions.

    Both GFS and ECM bring her to hit the New Orleans kind of area again as a Major Hurricane less than a week after Gustav.

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    Posted
  • Location: Dorset
  • Location: Dorset

    She's looking 10X better than yesterday, no exposure now to the shear which seems to be easing off. Good outflow as well.

    Also the size of Hanna, her moisture field is bigger than Gustav's, her Convection field would swomp Florida. A true monster.

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