[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 290545
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST WED DEC 28 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
0535 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST OF GUINEA NEAR
10N14W TO 5N22W. THE ITCZ AXIS EXTENDS WSW FROM THIS POINT ALONG
2N33W TO THE COAST OF BRAZIL NEAR 1S47W. SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS WITHIN 120 NM ON THE NRN SIDE OF
THE ITCZ AXIS BETWEEN 20W-30W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL SHORTWAVE PROGRESSING
OVER THE N CENTRAL GULF BASIN ADVECTING MIDDLE TO UPPER LEVEL
MOISTURE ACROSS THE NE CORNER OF THE BASIN. DESPITE THE UPPER
LEVEL FEATURE...A 1022 MB HIGH IS CENTERED OVER THE COASTAL
WATERS NEAR THE WESTERN FLORIDA PANHANDLE NEAR 30N87W. IN
ADDITION TO LIGHT AND VARIABLE WINDS IN THE VICINITY AND AROUND
THE HIGH PRESSURE CENTER...LIGHT ANTICYCLONIC FLOW AND FAIR
WEATHER CONDITIONS ARE EXPERIENCED ELSEWHERE ACROSS THE AREA.
THE HIGH IS FORECAST TO SLIDE EASTWARD THROUGH SATURDAY AND MOVE
INTO THE SW NORTH ATLC BY SUNDAY. THE NEXT COLD FRONT IS THEN
EXPECTED BY SUNDAY MORNING TO ENTER THE NW GULF USHERING IN
STRONG NORTHERLY WINDS THAT WILL SPREAD EASTWARD ACROSS THE GULF
THROUGH EARLY NEXT WEEK.

CARIBBEAN SEA...
VERY DRY AIR ALOFT AND STRONG SUBSIDENCE COVERS THE CARIBBEAN
WATERS THIS LATE EVENING. THIS AIRMASS IS SUPPRESSING DEEP
CONVECTION ACROSS THE DISCUSSION AREA. HOWEVER...A SHEAR LINE IS
ANALYZED ALONG CENTRAL CUBA NEAR 22N79W TO 18N85W WITH ISOLATED
SHOWERS OCCURRING WITHIN 120 NM EITHER SIDE OF THE BOUNDARY.
MODERATE TO FRESH TRADE WIND FLOW CONTINUES ACROSS MUCH OF THE
CENTRAL AND ERN BASIN...ESPECIALLY BETWEEN 67W-77W AND NEAR THE
COAST OF COLOMBIA...WITH A FEW SMALL CLUSTERS OF LOW-TOP WEAK
SHOWERS EMBEDDED IN THE FLOW. THESE CONDITIONS ARE EXPECTED TO
PERSIST THROUGH FRIDAY AS A RIDGE WILL POSITION ITSELF IN THE SW
NORTH ATLC AND INCREASE THE TRADES DUE TO AN INCREASED PRESSURE
GRADIENT. THE TRADES WILL REMAIN STRONG BASIN-WIDE THROUGH THE
UPCOMING WEEKEND.

ATLANTIC OCEAN...
A BROAD UPPER LEVEL TROUGH IS MOVING ACROSS THE NW ATLC
SUPPORTING A COLD FRONT ANALYZED INTO THE DISCUSSION AREA ALONG
32N62W TO THE CENTRAL BAHAMAS NEAR 24N75W BECOMING A WEAK SHEAR
LINE AXIS INTO CENTRAL CUBA ALONG 22N79W. SCATTERED WEAK SHOWERS
AND POSSIBLE ISOLATED TSTMS ARE OCCURRING WITHIN 30 NM ON EITHER
SIDE OF THE FRONT. HIGH PRESSURE WILL CONTINUE TO BUILD IN
BEHIND THE FRONT FROM THE EASTERN GULF OF MEXICO ACROSS THE
REMAINDER OF THE SW NORTH ATLC THROUGH EARLY FRIDAY. FARTHER
EAST...A NARROW UPPER LEVEL TROUGH IS MOVING ACROSS THE N
CENTRAL ATLC OUTSIDE THE DISCUSSION AREA. THIS UPPER LEVEL
FEATURE SUPPORTS THE TAIL END OF A COLD FRONT THAT EXTENDS INTO
THE AREA ALONG 32N39W TO 25N43W. LOW-LEVEL MOISTURE REMAINS
LIMITED WITH THIS FRONT...WITH JUST A FEW WEAK SHOWERS WITHIN 40
EITHER SIDE OF THE FRONT. THE REMAINDER OF THE EASTERN ATLC IS
UNDER THE INFLUENCE OF A STRONG SURFACE RIDGE ANCHORED N OF THE
DISCUSSION AREA.

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

$$

GARCIA




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