[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI JAN 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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...

THE ITCZ AXIS IS ANALYZED ALONG 5N9W TO 2N20W CROSSING THE
EQUATOR AT 30W TO 2S44W. ISOLATED MODERATE CONVECTION S OF
THE ITCZ TO 3N BETWEEN 9W AND 11W. NO SIGNIFICANT CONVECTION
ELSEWHERE.

...DISCUSSION...

GULF OF MEXICO...
AT 28/1500 UTC...A 1025 MB HIGH CENTERED OVER THE NW GULF NEAR
27N94W DOMINATES MOST OF THE REGION PRODUCING RELATIVELY
TRANQUIL CONDITIONS. SOME STRATOCUMULUS CLOUDS ARE STILL NOTED
ACROSS PORTIONS OF THE CENTRAL AND NE GULF AS COOLER AIR RUNS
OVER THE WARMER WATER. MORE WIDESPREAD LOW-LEVEL CLOUDINESS AND
POSSIBLE ISOLATED SHOWERS REMAIN ALONG THE ERN COAST OF MEXICO.
A RE-INFORCING COLD FRONT IS MOVING ACROSS SOUTH FLORIDA AND THE
SE PORTION OF THE GULF...AND WILL EXIT THE SUNSHINE STATE LATE
THIS AFTERNOON INTO THIS EVENING. MAINLY ZONAL WLY FLOW ALOFT
DOMINATES THE REGION ADVECTING MID/UPPER LEVEL MOISTURE FROM THE
EPAC. EXPECT THE SURFACE RIDGE TO GRADUALLY DRIFT EWD ACROSS THE
BASIN REACHING FLORIDA BY EARLY SUNDAY. THE NEXT COLD FRONT IS
FORECAST TO APPROACH THE TEXAS COAST BY TUE. SLY RETURN FLOW
WILL INCREASE AHEAD OF THE FRONT.

CARIBBEAN SEA...
THE FRONT THAT WAS OVER FAR NW CARIBBEAN YESTERDAY HAS
DISSIPATED. LINGERING MOISTURE WITH EMBEDDED SHOWERS IS SEEN ON
SATELLITE PICTURES OVER THE GULF OF HONDURAS DUE TO LOW LEVEL
CONVERGENCE. SURFACE DATA AND AN EARLIER ASCAT PASS SHOW FRESH
NORTHERLY WINDS THROUGH THE YUCATAN CHANNEL AND THE WESTERN
CARIBBEAN. THESE WINDS ARE EXPECTED TO DIMINISH THROUGH THIS
EVENING AS WINDS GRADUALLY VEER MORE NE ACROSS THE W CARIBBEAN.
ANOTHER PATCH OF MOISTURE WITH SHOWERS AND ISOLATED TSTMS COVERS
THE AREA FROM 12N-16N BETWEEN 80W-84W. IT IS ALSO ASSOCIATED
WITH LOW LEVEL CONVERGENCE. FRESH TRADE WINDS WILL CONTINUE TO
BLOW FROM THE TROPICAL N ATLC THROUGH THE CENTRAL CARIBBEAN
THROUGH EARLY NEXT WEEK. PATCHES OF LOW LEVEL MOISTURE EMBEDDED
IN THE TRADE WIND FLOW ARE EXPECTED TO MOVE ACROSS THE BASIN
FROM TIME TO TIME...RESULTING IN INTERVALS OF CLOUDINESS AND A
FEW PASSING SHOWERS. THESE SHALLOW SHOWERS ARE CURRENTLY MORE
CONCENTRATED OVER THE CENTRAL CARIBBEAN FROM 14N-18N BETWEEN
72W-77W. THE BASE OF THE MAINLY ZONAL WLY FLOW ALOFT EXTENDS
FURTHER SOUTH OVER THE N PORTION OF THE CARIBBEAN SEA. WATER
VAPOR IMAGERY REVEALS MODERATE TO STRONG SUBSIDENCE OVER THE
MAJORITY OF THE BASIN BUT PARTICULARLY E OF 70W.

THE ATLANTIC OCEAN...
A DEEP LAYER TROUGH IS OVER THE EASTERN U.S. SUPPORTING A
RE-INFORCING COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR
31N74W THEN CONTINUES SW TO SOUTH FLORIDA. BASED ON THE COMPUTER
MODELS...THIS FRONT WILL BECOME ILL DEFINED IN ABOUT 24 HOURS.
ANOTHER COLD FRONT EXTENDS FROM 31N65W THE CENTRAL BAHAMAS WHERE
IT IS DISSIPATING. SOME SHOWERS AND ISOLATED TSTMS ARE NOTED
ALONG THE FRONTAL BOUNDARY. TO THE EAST OF THE SECOND FRONT...
THERE IS A RIDGE COVERING THE CENTRAL ATLC AND EXTENDING SW AND
W TO THE NE CARIBBEAN AND THE SE BAHAMAS RESPECTIVELY. THE RIDGE
IS CENTERED AROUND A 1028 MB HIGH NEAR 35N44W. THE STRONG
PRESSURE GRADIENT BETWEEN THE RIDGE AND AN OCCLUDED LOW PRESSURE
SYSTEM LOCATED NEAR 27N32W IS SUPPORTING GALE FORCE WINDS WITHIN
AROUND 320 NM NW QUADRANT OF LOW CENTER. THE 1138 UTC ASCAT PASS
CORROBORATED THESE WINDS SPEEDS. SCATTERED SHOWERS/POSSIBLE
ISOLATED THUNDERSTORMS ARE AHEAD OF THE LOW/OCCLUDED FRONT N OF
25N BETWEEN 20W-31W. ALOFT...AN UPPER LEVEL RIDGE EXTENDS FROM
THE NRN LEEWARD ISLANDS TO BEYOND 32N54W SUPPORTING THE SURFACE
RIDGE WHILE A SHARP UPPER LEVEL TROUGH ALONG 30W SUPPORTS THE
LOW PRESSURE SYSTEM.

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

$$
GR






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