[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 262343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT FEB 26 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2300 UTC.

...ITCZ...

THE ITCZ AXIS IS ANALYZED FROM THE COAST OF LIBERIA NEAR 5N9W TO
4N20W TO 2N30W TO NE BRAZIL NEAR 3S45W. SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS FROM THE EQUATOR TO 3N BETWEEN 28W
AND 35W. SIMILAR CONVECTION IS ALSO NOTED ALONG THE COASTS OF
LIBERIA AND THE IVORY COAST FROM 2N-7N BETWEEN 6W-9W...NEAR THE
EQUATOR AT 8W AND NEAR 2N14W.

...DISCUSSION...

GULF OF MEXICO...
HIGH PRES LOCATED OVER THE ATLANTIC OCEAN EXTENDS A RIDGE WWD
ACROSS THE GULF REGION. A WEAK FRONTAL BOUNDARY REMAINS OVER N
FLORIDA AND THE NE PORTION OF THE GULF. A FEW SHOWERS ARE NEAR
THIS FEATURE WHICH WILL DISSIPATE TONIGHT AS IT LIFTS N. SLY
RETURN FLOW OVER THE WESTERN GULF WILL INCREASE TO 20 KT LATE
TONIGHT AHEAD OF A COLD FRONT FORECAST TO MOVE INTO THE NW GULF
LATE SUN INTO MON. FRESH TO STRONG NLY WINDS AND BUILDING SEAS
TO AROUND 8 FT ARE EXPECTED IN THE WAKE OF THE FRONT. THE REST
OF THE GULF OF MEXICO IS ENJOYING MAINLY FAIR WEATHER AND LIGHT
TO GENTLE BREEZE. A ZONAL FLOW TO THE N OF AN ANTICYCLONE ALOFT
CENTERED OVER SE MEXICO AND GUATEMALA DOMINATES THE GULF. STRONG
SUBSIDENCE ACCOMPANIES THIS UPPER LEVEL FEATURE AS EVIDENCED IN
RECENT WATER VAPOR IMAGERY. WARM AND DRY CONDITIONS PREVAIL OVER
SOUTH FLORIDA UNDER THE INFLUENCE OF A RIDGE ALOFT AND AT THE
SURFACE.

CARIBBEAN SEA...
THE 1506 UTC ASCAT PASS SHOWED 20-30 KT TRADEWINDS OVER THE
SOUTH CENTRAL CARIBBEAN WITH THE STRONGEST WINDS AS USUAL NEAR
THE COAST OF COLOMBIA. FEW SHIP OBSERVATIONS ALSO CORROBORATED
THESE WIND SPEEDS. HIGH PRES N OF AREA WILL CONTINUE TO PRODUCE
FRESH TO STRONG TRADES ACROSS THE E AND CENTRAL CARIBBEAN
THROUGH MON. FURTHER E...A SHEAR LINE...WHICH IS THE FINAL STAGE
IN THE LIFE CYCLE OF A COLD FRONT OVER THE SUBTROPICS AND
TROPICS...ENTERS THE CARIBBEAN SEA THROUGH THE WINDWARD ISLANDS
THEN CONTINUES MAINLY WWD TO NEAR THE ABC ISLANDS. A WELL
DEFINED BAND OF LOW/MID CLOUDS WITH EMBEDDED SHOWERS IS
ASSOCIATED WITH THIS SYSTEM. LOW LEVEL MOISTURE RELATED TO THIS
SHEAR LINE WILL CONTINUE TO ENHANCE SOME SHOWER ACTIVITY FROM
THE WINDWARD ISLANDS TO THE ABC ISLANDS AND ACROSS NORTHERN
VENEZUELA THROUGH SUN. NE WINDS OF 20-25 KT ARE NOTED TO THE N
OF THE SHEAR LINE PER AN EARLIER ASCAT PASS. LOW LEVEL
CONVERGENCE IS PRODUCING CLOUDINESS WITH EMBEDDED SHOWERS ALONG
THE CARIBBEAN PLAINS OF NICARAGUA. PATCHES OF LOW-LEVEL MOISTURE
ARE ALSO SEEN ACROSS THE WESTERN CARIBBEAN W OF 84W. ONE OF THEM
IS MOVING ACROSS THE YUCATAN CHANNEL. IN THE UPPER LEVELS...A
WEST-TO-EAST RIDGE STRETCHES FROM SE MEXICO AND GUATEMALA TO THE
GREATER ANTILLES. STRONG UPPER LEVEL SUBSIDENCE AND IMPLIED DRY
AIR MASS IS NOTED WITHIN THE RIDGE AXIS. A VERY DRY AIR MASS IS
OVER THE NE CARIBBEAN LIMITING THE SHOWER ACTIVITY.

ATLANTIC OCEAN...
A 1024 MB HIGH CENTERED NEAR 27N56W EXTENDS A RIDGE WWD ACROSS
THE WESTERN ATLC AND FLORIDA INTO THE GULF OF MEXICO. A NEARLY
STATIONARY 1008 MB LOW PRES SYSTEM IS OVER THE CENTRAL ATLC NEAR
24N43W. A TROUGH EXTENDS FROM THE LOW TO NEAR 14N47W. AT THIS
POINT...A SHEAR LINE IS ANALYZED ON THE 18Z MAP ALONG 12N55W
12N62W 11N67W. A BAND OF LOW/MID CLOUDS IS ASSOCIATED WITH THE
TROUGH AND SHEAR LINE. A STATIONARY FRONT ALSO EXTENDS FROM THE
LOW TO THE N BEYOND 31N41W. A NARROW UPPER LEVEL TROUGH IS
SUPPORTING THIS FEATURE. PRES GRADIENT BETWEEN THE LOW AND THE
HIGH PRES IS PRODUCING AN AREA OF NLY WINDS IN THE 20 TO 30 KT
RANGE N OF 20N BETWEEN THE STATIONARY FRONT AND 51W. THE REST OF
THE TROPICAL N ATLANTIC TO THE EAST IS UNDER SURFACE RIDGING
FROM A 1033 MB HIGH N OF THE AREA. A BROAD UPPER RIDGE COVERS
THE TROPICAL ATLC S OF 20N AND BETWEEN THE W AFRICAN COAST AND
30W SUPPORTING DRY CONDITIONS.

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

$$
GR









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