For a more recent update for Hurricane Bill, CLICK HERE
Hurricane Bill has returned to its former stature regarding the structure but there is some impediments to it regaining its Category 4 status. While the official forecast suggests that there will be very little shear over the next few days, you can tell from the satellite imagery continues to show that the outflow is displaced a bit toward the north in reaction to the southwesterly flow ahead of a trof digging into the eastern US.
It should pick up forward speed but will run into colder water temperatures by Sunday. Also the shear should increase and the storm begin to morph in to an extra-tropical system. So, even though several models indicated on the spaghetti intensity model chart shows the storm at Category 4 level, it may be tough to do or at least remain at that status. But, you know what, it’s not relevant. That’s because Bill will remain in the Atlantic while it wanders about. Well, the strength is not totall irrelevant because as a big bopper it will create big swells and waves along the eastern seaboard and also for the Canadian Maritimes. The forecast track has shifted a shade but don’t take it as gospel. The storm may be down to about 100 mph but will significantly impact the Canadian maritime provinces, especially Nova Scotia. See the 11pm EDT August 20 National Hurricane Discussion below.
WTNT43 KNHC 210248
HURRICANE BILL DISCUSSION NUMBER 23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
1100 PM AST THU AUG 20 2009
THE SATELLITE PRESENTATION OF BILL HAS CHANGED LITTLE THIS EVENING.
THE LARGE EYE REMAINS VERY WELL-DEFINED…HOWEVER THE CLOUD TOPS
SURROUNDING THE EYE HAVE WARMED SLIGHTLY DURING THE PAST COUPLE OF
HOURS. THE NOAA RECONNAISSANCE AIRCRAFT THAT HAS BEEN SAMPLING THE
CORE OF THE HURRICANE THIS EVENING REPORTED A PEAK BELIEVABLE
FLIGHT-LEVEL WIND OF 127 KT. ALTHOUGH HIGHER WIND SPEEDS WERE
REPORTED…THE METEOROLOGISTS ON THE AIRCRAFT DID NOT CONSIDER
THOSE HIGHER WINDS TO BE VALID. DVORAK DATA T-NUMBERS HAVE
DECREASED SLIGHTLY. BASED ON ALL OF THE DATA…THE INITIAL
INTENSITY IS HELD AT 110 KT. ENVIRONMENTAL FACTORS ARE EXPECTED TO
REMAIN CONDUCIVE FOR SOME RESTRENGTHENING DURING THE NEXT 24 HOURS
OR SO. AFTERWARDS…SOME COOLING OF THE SSTS WILL LIKELY INDUCE A
SLOW WEAKENING TREND. VERTICAL WIND SHEAR IS PREDICTED BY THE
SHIPS MODEL TO REMAIN LIGHT UNTIL THE HURRICANE NEARS THE CANADIAN
MARITIMES IN ABOUT 72 HOURS. HOWEVER…SSTS ALONG THE FORECAST
TRACK WILL BEGIN TO COOL MORE RAPIDLY AROUND THAT TIME…AND SHEAR
IS FORECAST TO INCREASE SIGNIFICANTLY VERY SOON THEREAFTER. THE
OFFICIAL WIND SPEED FORECAST IS GENERALLY BETWEEN THE SHIPS AND
BILL CONTINUES TO MOVE NORTHWESTWARD OR 310/16 KT. THERE IS NOT MUCH
NEW TO SAY ABOUT THE TRACK FORECAST. BILL IS EXPECTED TO TURN
NORTHWARD AHEAD OF A STRONG MID-LATITUDE TROUGH THAT WILL MOVE INTO
THE EASTERN U.S. DURING THE NEXT COUPLE OF DAYS…AND RECURVE AHEAD
OF THAT TROUGH THEREAFTER. THE NEW TRACK FORECAST IS VIRTUALLY
UNCHANGED FROM THE PREVIOUS ADVISORY AND IS ONCE AGAIN IN EXCELLENT
AGREEMENT WITH THE TIGHTLY CLUSTERED MODEL GUIDANCE.
LARGE SWELLS GENERATED BY THIS HURRICANE ARE AFFECTING…OR WILL
AFFECT…A LARGE PORTION OF THE WESTERN NORTH ATLANTIC COASTAL AREA
DURING THE NEXT FEW DAYS. THESE SWELLS WILL LIKELY CAUSE EXTREMELY
DANGEROUS SURF AND LIFE-THREATENING RIP CURRENTS. PLEASE CONSULT
STATEMENTS ISSUED BY YOUR LOCAL WEATHER OFFICE FOR MORE DETAILS.
DATA FROM A TWO-AIRCRAFT SYNOPTIC SURVEILLANCE MISSION CONDUCTED BY
NOAA AND U.S. AIR FORCE RESERVE AIRCRAFT THIS EVENING SHOULD BE
ASSIMILATED INTO THE INITIALIZATION OF THE 0000 UTC MODEL RUNS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 21/0300Z 24.9N 64.3W 110 KT
12HR VT 21/1200Z 26.9N 66.1W 115 KT
24HR VT 22/0000Z 29.6N 67.9W 115 KT
36HR VT 22/1200Z 32.7N 68.9W 110 KT
48HR VT 23/0000Z 36.4N 68.6W 100 KT
72HR VT 24/0000Z 44.3N 62.0W 80 KT
96HR VT 25/0000Z 50.5N 43.0W 55 KT…EXTRATROPICAL
120HR VT 26/0000Z 55.0N 20.0W 50 KT…EXTRATROPICAL