[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 160546
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST FRI DEC 16 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 11N15W TO
05N30W TO 05N41W. ISOLATED MODERATE CONVECTION IS FROM 06N-12N
BETWEEN 20W-26W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE REMAINS ANCHORED IN THE WESTERN CARIBBEAN
SEA AND EXTENDS NORTHWARD CONTINUING TO IMPACT THE GULF AND
FLORIDA PENINSULA THIS EVENING. THE RIDGE AXIS IS ALONG 80W WITH
WATER VAPOR IMAGERY INDICATING A DRY AND STABLE AIRMASS UNDER
MOSTLY SOUTHWESTERLY FLOW ALOFT. THIS UPPER LEVEL FEATURE IS
SUPPORTIVE OF A SURFACE RIDGE ANCHORED BY A 1024 MB HIGH
CENTERED OVER THE SW NORTH ATLC NEAR 32N74W WHICH EXTENDS A
RIDGE AXIS SOUTHWESTWARD ACROSS THE FLORIDA PENINSULA TO THE
WESTERN GULF WATERS NEAR 23N95W. MOSTLY E TO SE WINDS IN THE
RANGE OF 10 TO 15 KT ARE EXPECTED THROUGH THE OVERNIGHT HOURS.
ALSO ON WATER VAPOR IMAGERY...AN UPPER LEVEL SHORTWAVE TROUGH IS
PROGRESSING NE ACROSS WEST TEXAS CURRENTLY AND IS EXPECTED TO
PUSH A WEAK FRONTAL BOUNDARY INTO THE NW WATERS BY SUNRISE.
NORTHERLY WINDS ARE FORECAST TO INCREASE TO 20 KT BEHIND THE
FRONT AND PERSIST THROUGHOUT THE DAY ON FRIDAY AS THE FRONT
BECOMES DIFFUSE LATE AS THE UPPER LEVEL SHORTWAVE MOVES TO THE
NE. SURFACE HIGH PRESSURE WILL THEN BUILD ACROSS THE GULF
THROUGH THE WEEKEND WITH NORTHEASTERLY WINDS PERSISTING THROUGH
SUNDAY NIGHT.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE INFLUENCES MUCH OF THE WESTERN CARIBBEAN
WITH AN AXIS EXTENDING FROM OVER NORTHERN COLOMBIA NEAR 12N74W
NORTHWESTWARD TO OVER THE YUCATAN CHANNEL NEAR 22N87W. SOUTHWEST
OF THIS RIDGE AXIS...SOUTHERLY DIFFLUENT FLOW ALOFT CONTINUES TO
ENHANCE WIDELY SCATTERED SHOWERS AND TSTMS S OF 13N BETWEEN
73W-85W...INCLUDING PORTIONS OF PANAMA...COSTA RICA...AND
SOUTHERN NICARAGUA. MOST OF THIS CONVECTIVE ACTIVITY IS FOCUSED
IN THE VICINITY OF THE MONSOON TROUGH AXIS WHICH EXTENDS FROM
THE E PACIFIC ALONG 10N TO NORTHERN COLOMBIA. OTHERWISE THE
REMAINDER OF THE WESTERN CARIBBEAN W OF 70W IS UNDER STRONG NE
TRADES DUE TO AN INCREASED PRESSURE GRADIENT FROM BUILDING HIGH
PRESSURE OVER THE SW NORTH ATLC. FARTHER EAST...NORTHWESTERLY
FLOW ALOFT DOMINATES ON THE SOUTHWESTERN PERIPHERY OF AN UPPER
LEVEL TROUGH ACROSS THE CENTRAL ATLC. A DIFFUSE AND DISSIPATING
COLD FRONT EXTENDS INTO THE EASTERN CARIBBEAN THROUGH THE
GUADELOUPE PASSAGE NEAR 16N62W THEN WESTWARD ALONG 15N66W TO
16N71W. ISOLATED SHOWERS ARE OCCURRING WITHIN 75 NM EITHER SIDE
OF THE FRONT AS IT CONTINUES TO DRIFT SOUTHWARD. A RECENT ASCAT
PASS AROUND 16/0132 UTC INDICATED STRONG NE WINDS NORTH OF THE
FRONT IN THE RANGE OF 20 TO 25 KT. HIGH PRESSURE IS FORECAST TO
REMAIN ANCHORED NE OF THE BAHAMAS THROUGH THE REMAINDER OF THE
WEEKEND MAINTAINING AN AREA OF INCREASED E-NE TRADES.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE CONTINUES TO SLIDE EASTWARD OVER THE SW
NORTH ATLC WITH AXIS ALONG 80W. A MOSTLY DRY AND STABLE AIRMASS
IS ASSOCIATED WITH THIS UPPER LEVEL FEATURE AND THIS CONTINUES
TO SUPPORT A 1024 MB SURFACE HIGH CENTERED NEAR 32N74W. MOSTLY
NE TO E WINDS ARE OBSERVED W OF 60W WITH A FEW FAST-MOVING
ISOLATED SHOWERS EXPECTED THROUGH THE OVERNIGHT ACROSS THE
BAHAMAS...TURKS AND CAICOS...AND N OF 25N W OF 78W TO THE
FLORIDA PENINSULA COAST. FARTHER EAST...A SHARP UPPER LEVEL
TROUGH WITH AXIS ALONG 55W CONTINUES TO SUPPORT A COLD FRONT
ANALYZED INTO THE DISCUSSION AREA NEAR 32N48W EXTENDING SOUTH
THEN SOUTHWESTWARD ALONG 26N50W TO 20N55W TO THE GUADELOUPE
PASSAGE NEAR 16N62W AND INTO THE EASTERN CARIBBEAN SEA. A
PRE-FRONTAL TROUGH IS LOCATED SE OF THE FRONT ALONG 13N53W TO
20N50W TO 27N47W. LOW-LEVEL CONVERGENCE NEAR THE SURFACE TROUGH
AND FRONTAL BOUNDARIES ALONG WITH STRONG MIDDLE TO UPPER LEVEL
DIFFLUENCE IS GENERATING A BROAD AREA OF SCATTERED SHOWERS AND
ISOLATED TSTMS FROM 12N-32N BETWEEN 42W-51W. A FEW ISOLATED
SHOWERS ARE ALSO OCCURRING WEST OF THE COLD FRONT FROM 24N-30N
BETWEEN 52W-57W IN ASSOCIATED WITH THE MIDDLE TO UPPER LEVEL LOW
CENTERED NEAR 27N55W. THE REMAINDER OF THE EASTERN ATLC IS UNDER
THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1034 MB HIGH
CENTERED SW OF THE IBERIAN PENINSULA NEAR 35N16W. THE RIDGE AXIS
EXTENDS SW FROM THE HIGH TO 32N24W TO 15N40W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
HUFFMAN




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