[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 160846
TCDAT4

HURRICANE MARIA DISCUSSION NUMBER  39
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
500 AM AST FRI SEP 16 2011

AN 0540 UTC AMSR-E OVERPASS INDICATES THAT THE EYEWALL OF MARIA IS
OPEN IN THE SOUTHWEST QUADRANT AND THAT THE RING OF DEEP CONVECTION
IS THINNING.  HOWEVER...THE LATEST ADT ESTIMATE IS 72 KT...AND A
BLEND OF FINAL-T AND CI NUMBERS FROM TAFB AND SAB YIELDS AN
INTENSITY BETWEEN 65 AND 72 KT.  THE INITIAL INTENSITY IS THEREFORE
MAINTAINED AT 70 KT.

MARIA CONTINUES TO ACCELERATE AND NOW HAS AN INITIAL MOTION OF
035/39 KT.  THE HURRICANE IS EXPECTED TO CONTINUE ACCELERATING
NORTHEASTWARD OVER THE NEXT 24 HOURS AHEAD OF A DEEP-LAYER TROUGH
THAT CURRENTLY EXTENDS FROM NORTHERN QUEBEC INTO THE NORTHEASTERN
UNITED STATES.  THE NEW OFFICIAL TRACK FORECAST IS NEARLY IDENTICAL
TO THE PREVIOUS ONE UP UNTIL LANDFALL IN NEWFOUNDLAND...WHICH IS
FORECAST TO OCCUR IN 12 HOURS OR SO...AND ONLY DEVIATES SLIGHTLY TO
THE NORTHWEST THEREAFTER.  THIS SOLUTION IS IN THE MIDDLE OF THE
GUIDANCE ENVELOPE.

MARIA IS CROSSING THE STRONG SST GRADIENT ON THE NORTH SIDE OF THE
GULF STREAM AND IS OVER WATERS OF ABOUT 22-23 DEGREES CELSIUS.  THE
COLDER WATERS SHOULD INDUCE WEAKENING...BUT SINCE THE HURRICANE IS
MOVING SO FAST...IT PROBABLY WILL NOT WEAKEN MUCH BEFORE REACHING
NEWFOUNDLAND.  A COLD FRONT IS FAST-APPROACHING MARIA FROM THE
WEST...AND GLOBAL MODEL FIELDS SUGGEST THAT THE CYCLONE WILL BE
ALMOST FULLY EMBEDDED WITHIN THE FRONTAL ZONE NEAR OR JUST AFTER 18
UTC TODAY.  THE OFFICIAL INTENSITY FORECAST STILL SHOWS MARIA AS A
65-KT HURRICANE IN 12 HOURS AS IT APPROACHES NEWFOUNDLAND...BUT
EXTRATROPICAL TRANSITION SHOULD BE NEARING COMPLETION AT THAT TIME.
AS SHOWN BY THE INTENSITY GUIDANCE...THE POST-TROPICAL CYCLONE
SHOULD WEAKEN AFTER PASSING NEWFOUNDLAND AND THEN IS EXPECTED TO
BECOME ABSORBED WITHIN AN OCCLUDED FRONTAL ZONE BY 36 HOURS.

THE INTENSITY AND WIND RADII DURING THE POST-TROPICAL STAGE WERE
COORDINATED WITH THE NOAA OCEAN PREDICTION CENTER.  THE 12-FT SEAS
RADII HAVE BEEN TRIMMED IN THE NORTHERN SEMICIRCLE SINCE MARIA IS
OUTRUNNING THE HIGHEST WAVES.

FORECAST POSITIONS AND MAX WINDS

INIT  16/0900Z 41.7N  60.3W   70 KT  80 MPH
 12H  16/1800Z 46.8N  54.8W   65 KT  75 MPH
 24H  17/0600Z 55.0N  48.2W   55 KT  65 MPH...POST-TROP/EXTRATROP
 36H  17/1800Z...ABSORBED WITHIN A FRONTAL ZONE

$$
FORECASTER BERG/AVILA


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