[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161142
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...ITCZ/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N11W TO
08N17W TO 05N34W TO 07N50W. ISOLATED MODERATE CONVECTION IS FROM
05N-08N BETWEEN 21W-32W.

...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 MORNING. THE RIDGE AXIS EXTENDS FROM THE
NW CARIBBEAN SEA NEAR 20N84W NE TO BEYOND 32N78W 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 1023 MB HIGH CENTERED OVER THE
SW NORTH ATLC NEAR 33N69W WHICH EXTENDS A RIDGE AXIS WEST-
SOUTHWESTWARD ACROSS THE FLORIDA PENINSULA TO THE WESTERN GULF
WATERS NEAR 24N96W. MOSTLY E TO SE WINDS IN THE RANGE OF 10 TO
15 KT ARE OBSERVED OVER MUCH OF THE GULF THIS MORNING...WITH
WINDS VEERING SOUTHERLY OVER THE NW GULF AHEAD OF AN EMERGING
COLD FRONT ALONG THE TEXAS GULF COAST. WATER VAPOR IMAGERY ALSO
INDICATES AN UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING NE
ACROSS THE TEXAS PANHANDLE AND WESTERN OKLAHOMA WHICH IS
SUPPORTING THE WEAK COLD FRONT INTO THE NW WATERS THIS MORNING.
NORTHERLY WINDS BEHIND THE FRONT ARE EXPECTED TO INCREASE TO 20
KT AND PERSIST THROUGHOUT THE DAY 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 11N72W
NORTHWESTWARD TO OVER THE YUCATAN CHANNEL NEAR 22N87W. SOUTHWEST
OF THIS RIDGE AXIS...SOUTHERLY DIFFLUENT FLOW ALOFT CONTINUES TO
ENHANCE SCATTERED SHOWERS AND ISOLATED TSTMS S OF 14N BETWEEN
76W-84W...INCLUDING PORTIONS OF PANAMA AND COSTA RICA. MOST OF
THIS CONVECTIVE ACTIVITY IS FOCUSED IN THE VICINITY OF THE
MONSOON TROUGH AXIS WHICH EXTENDS FROM THE E PACIFIC ALONG 09N
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 REMNANT COLD FRONT...ANALYZED AS A SHEAR LINE
EXTENDS INTO THE EASTERN CARIBBEAN THROUGH THE MARTINIQUE
PASSAGE NEAR 15N61W THEN WESTWARD ALONG 14N66W TO 12N76W.
ISOLATED SHOWERS ARE OCCURRING WITHIN 75 NM EITHER SIDE OF THE
SHEAR LINE AS IT CONTINUES TO DRIFT SOUTHWARD. AN EARLIER ASCAT
PASS AROUND 16/0132 UTC INDICATED STRONG NE WINDS NORTH OF THE
SHEAR LINE AXIS 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 OVER THE CENTRAL AND EASTERN CARIBBEAN.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE CONTINUES TO SLIDE EASTWARD OVER THE SW
NORTH ATLC WITH AXIS EXTENDING FROM THE NW CARIBBEAN SEA NEAR
20N84W NE TO BEYOND 32N78W. A MOSTLY DRY AND STABLE AIRMASS IS
ASSOCIATED WITH THIS UPPER LEVEL FEATURE AND THIS CONTINUES TO
SUPPORT A 1023 MB SURFACE HIGH CENTERED NEAR 33N69W. MOSTLY NE
TO E WINDS ARE OBSERVED W OF 60W WITH A FEW FAST-MOVING ISOLATED
SHOWERS EXPECTED THROUGHOUT THE DAY FRIDAY ACROSS THE BAHAMAS...
TURKS AND CAICOS...AND AREAS OFFSHORE OF THE FLORIDA PENINSULA W
OF 78W. FARTHER EAST...A SHARP UPPER LEVEL TROUGH WITH AXIS
ALONG 55W CONTINUES TO SUPPORT A FRONTAL BOUNDARY ANALYZED INTO
THE DISCUSSION AREA NEAR 32N48W EXTENDING SOUTH INTO A 1006 MB
LOW NEAR 29N49W THEN SOUTHWARD TO A 1004 MB LOW NEAR 22N51W THEN
SOUTHWESTWARD TO THE MARTINIQUE PASSAGE NEAR 15N61W AND INTO THE
EASTERN CARIBBEAN SEA. A PRE-FRONTAL TROUGH IS LOCATED SE OF THE
FRONT ALONG 10N53W TO 17N49W TO 22N49W. LOW-LEVEL CONVERGENCE
EAST OF THE SURFACE TROUGH AND ALONG WITH STRONG MIDDLE TO UPPER
LEVEL DIFFLUENCE IS GENERATING A BROAD AREA OF SCATTERED SHOWERS
AND ISOLATED TSTMS FROM 10N-32N BETWEEN 41W-50W. A FEW ISOLATED
SHOWERS ARE ALSO OCCURRING WITHIN 75 NM EITHER SIDE OF THE COLD
FRONT S OF 20N AND WEST OF THE COLD FRONT FROM 24N-29N BETWEEN
51W-56W IN ASSOCIATION WITH THE MIDDLE TO UPPER LEVEL LOW
CENTERED NEAR 26N54W. 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 35N19W. THE RIDGE AXIS
EXTENDS SW FROM THE HIGH TO 32N24W TO 12N38W.

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

$$
HUFFMAN




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