Tropical Storm Bill Looks Much Better than Tropical Storm Ana…Both long way out


Ana Spaghetti Model 00Z 08.16.09

Ana Spaghetti Model 00Z 08.16.09

Ana Spaghetti Intensity Model 00Z 08.16.09

Ana Spaghetti Intensity Model 00Z 08.16.09

CLICK HERE for more recent update on Ana, Bill and Claudette
After an extremely pedestrian hurricane season, suddenly everything got interesting, sorta.  I say sorta because there are a lot of things working against our two tropical cyclones.  If you recall, what is now Tropical Storm Ana came off the African coast as a very robust tropical wave.  It looked good for a time but then lost alot of its structure.   Now, it has a low level circulation and the pressure has slipped to 1004 mb.    A trof in the North Atlantic that might have influenced it north went away and a big fat ridge took its place so it is being steered westward and should continue to do so all the way across the ocean.

NHC Forecast Track Ana 11pm 08.15.09

NHC Forecast Track Ana 11pm 08.15.09

The trouble is that its moving at about 20 mph which makes it very difficult for it to develop.  Either it has to get into an extremely good environment or it has to slow down and neither of those two things appear to be in the cards at this time.  It’s just not able to get an anticyclone aloft and in order for their to be a hurricane, you have to have one of those.  But, as it moves around the ridge, it should continue toward the Southeast US but  will probably run into some of the islands.  Without much upper support, the interaction with the island, particularly Puerto Rico, Cuba or Dominica,  those islands will probably mess it up and make it just a big rain maker when it gets to the US.  Should the storm make it intact into the Gulf, then thats another story. It would be tough for this guy to get disrupted, make it into the Gulf and redevelop.  However, if this guy slows down, then its a new ballgame.   But, then again, if it does slow down it may never make it to the US.

TS Bill Spaghetti Model 00Z 08.16.09

TS Bill Spaghetti Model 00Z 08.16.09

Bill Intensity Spaghetti Model 00Z 08.16.09

Bill Intensity Spaghetti Model 00Z 08.16.09

That’s because the ridge that is steering it should break down as a trof comes to the East Coast.  That breakdown would cause it at its present speed to turn it north after it makes it to Florida.   If it slows down, then it would probably get turned in the breaking down ridge, which is what the problem is with Tropical Storm Bill.  Bill is looking better all the time and most of the models make it a pretty decent hurricane.  Four models take it to Cat 3.  It gets the good anticylone aloft that Ana will probably lack.  But, because Bill is farther behind and moving a bit slower, then it is progged by most models to start to turn well before it approaches the US coast.  Coriolis parameters will overtake the weakening steering.  This would be the scenario that may be problematic.

NHC Forecast Track Bill 11pm 08.15.09

NHC Forecast Track Bill 11pm 08.15.09

Let us say that Bill does turn…then the ridge builds back in.   If Bill doesn’t go too far north and the ridge builds in, then the ridge may be sufficient to overcome the coriolis and make Bill more of a threat.  But that scenario would be so far out, it is left strictly to my imagination at this time and there is nothing really to support that notion. Possible, not probable.

Ana Satellite 0345Z 08.16.09

Ana Satellite 0345Z 08.16.09

WTNT42 KNHC 160247
TCDAT2
TROPICAL STORM ANA DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 PM AST SAT AUG 15 2009

THE CONVECTION NEAR THE CENTER OF ANA HAS BEEN PULSATING AND AFTER
AN INCREASE FOR A FEW HOURS…THE LOW LEVEL CENTER HAS BECOME
EXPOSED AGAIN. THIS MEANS ANNA IS NOT STRENGTHENING AND THE INITIAL
INTENSITY IS KEPT AT 35 KNOTS. A NOAA JET FLEW AGAIN TONIGHT AND ONE
OF THE DROPS NEAR THE CENTER MEASURED A SURFACE PRESSURE OF 1004 MB
WHICH WAS USED FOR THIS ADVISORY. THE SHEAR IS NOT VERY STRONG AS
DIAGNOSED BY THE SHIPS MODELS BUT THE LOW-LEVEL CENTER OF ANA IS
SIMPLY MOVING TOO FAST. THIS RAPID MOTION IS PROBABLY NOT TOO
CONDUCIVE FOR INTENSIFICATION.  IN FACT…THE ONLY DYNAMICAL MODELS
THAT KEEP ANA ARE THE UK AND THE NOGAPS.  THE REST OF THEM WEAKEN
ANA TO A TROPICAL WAVE. I AM TEMPTED TO SHOW WEAKENING BUT FOR
NOW…I AM GOING TO FOLLOW THE PREVIOUS FORECAST AND SHIPS MODEL
GUIDANCE. THE OFFICIAL FORECAST SHOWS SLOW STRENGTHENING THROUGH 48
HOURS FOLLOWED BY WEAKENING AS THE CYCLONE INTERACTS WITH
HISPANIOLA AND CUBA.

THE INITIAL MOTION IS 270/15. ANA IS EMBEDDED WITHIN STRONG AND
PERSISTENT TRADE WINDS AND ONLY A SMALL TURN TO THE WEST-NORTHWEST
WITH AN INCREASE IN FORWARD SPEED IS ANTICIPATED. THE OFFICIAL
FORECAST IS A LITTLE BIT SLOWER THAN MOST OF THE GUIDANCE BUT IS
WELL INSIDE THE ENVELOPE THROUGH 48 HOURS. THEREAFTER…SOME MODELS
KEEP A WEAKER ANA SOUTH OF CUBA AND OTHERS BRING THE CYCLONE OVER
CUBA AND INTO THE GULF OF MEXICO.  THE OFFICIAL TRACK FORECAST IS
VERY SIMILAR TO THE PREVIOUS ONE AND FOLLOWS THE NORTHERNMOST GROUP
OF MODELS.

FORECAST POSITIONS AND MAX WINDS

INITIAL      16/0300Z 14.4N  51.5W    35 KT
12HR VT     16/1200Z 14.7N  54.1W    35 KT
24HR VT     17/0000Z 15.5N  57.5W    40 KT
36HR VT     17/1200Z 16.5N  61.2W    45 KT
48HR VT     18/0000Z 17.5N  65.0W    50 KT
72HR VT     19/0000Z 19.5N  73.0W    30 KT…INLAND
96HR VT     20/0000Z 22.5N  78.9W    35 KT…OVER WATER
120HR VT     21/0000Z 25.0N  83.6W    40 KT

$$
FORECASTER AVILA

TS Bill Satellite 0345Z 08.16.09

TS Bill Satellite 0345Z 08.16.09

WTNT43 KNHC 160247
TCDAT3
TROPICAL STORM BILL DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032009
1100 PM AST SAT AUG 15 2009

SATELLITE IMAGES CONTINUE TO SHOW THAT BILL IS GRADUALLY BECOMING
BETTER ORGANIZED WITH NUMEROUS CONVECTIVE BANDING FEATURES.
HOWEVER…THE CYCLONE LACKS AN INNER CORE AND DEEP CONVECTION NEAR
THE CENTER. INITIAL INTENSITY IS KEPT AT 35 KNOTS WHICH IS A BLEND
OF THE DVORAK CLASSIFICATIONS AND QUIKSCAT DATA.  WITH THE
CONDUCIVE ENVIRONMENT AHEAD…BILL IS FORECAST TO BECOME A
HURRICANE IN A COUPLE OF DAYS AND BECOME EVEN STRONGER THEREAFTER.
THIS IS CONSISTENT WITH SHIPS AND BOTH THE GFDL/HWRF MODEL PAIR.

BILL IS MOVING WESTWARD OR 270 DEGREES AT 14 KNOTS. THE CYCLONE IS
WELL-EMBEDDED IN THE TROPICAL TRADE WINDS AND WILL CONTINUE ON THIS
GENERAL TRACK WITH A GRADUAL TURN TO THE WEST-NORTHWEST. THE ECMWF
WAS THE LEADER SHOWING A GRADUAL NORTHWARD TREND AHEAD OF A TROUGH
OVER THE EASTERN UNITED STATES A FEW RUNS AGO.  NOW…THE REST OF
THE MODELS…WITH THE EXCEPTION OF THE UK MODEL…ARE FOLLOWING THE
ECMWF TUNE…AND ALL TURN BILL MORE THE WEST-NORTHWEST AND NORTHWEST
BY THE END OF THE FORECAST PERIOD. BASED ON THIS SHIFT IN THE
GUIDANCE…THE OFFICIAL FORECAST WAS ALSO SHIFTED A LITTLE
NORTHWARD AND IS IN THE MIDDLE OF THE TIGHTLY PACKED GUIDANCE
ENVELOPE.

FORECAST POSITIONS AND MAX WINDS

INITIAL      16/0300Z 11.3N  36.6W    35 KT
12HR VT     16/1200Z 11.2N  38.7W    40 KT
24HR VT     17/0000Z 12.0N  41.5W    50 KT
36HR VT     17/1200Z 12.8N  44.0W    55 KT
48HR VT     18/0000Z 14.0N  47.0W    65 KT
72HR VT     19/0000Z 15.5N  52.5W    75 KT
96HR VT     20/0000Z 18.0N  58.5W    85 KT
120HR VT     21/0000Z 21.0N  64.0W    95 KT

$$
FORECASTER AVILA

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