[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281749
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED MAR 28 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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.

...ITCZ...

AS IS USUAL FOR THIS TIME OF THE YEAR THE ITCZ AXIS IS N OF THE
EQUATOR. IT IS CENTERED ALONG 5N10W 2N25W 2N35W CROSSING THE
EQUATOR AT 48W INTO NE BRAZIL. CLUSTERS OF SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION ARE WITHIN 100-120 NM N OF THE AXIS W
OF 20W. SIMILAR CONVECTION IS NEAR 3N12W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE THAT IS ANCHORED IN THE EPAC JUST SOUTH OF
COSTA RICA COVERS THE YUCATAN PENINSULA AND THE ENTIRE GULF.
STRONG SUBSIDENCE AND DRY AIR CONTINUE TO DOMINATE MOST OF THE
REGION AND THE FLORIDA PENINSULA LIMITING ANY SHOWER ACTIVITY.
SOME UPPER LEVEL MOISTURE IS BEING TRANSPORTED FROM THE EPAC
INTO SOUTH-CENTRAL MEXICO AND THE BAY OF CAMPECHE BY STRONG SW
UPPER FLOW. A 1023 MB WRN ATLANTIC SURFACE HIGH IS PRODUCING
10-15 E TO SE WINDS OVER MOST OF THE GULF. THE SE RETURN FLOW
WILL SLIGHTLY INCREASE TONIGHT OVER THE NW CORNER OF THE GULF AS
SURFACE LOW PRES DEEPENS OVER NE MEXICO. WINDS HAVE ALREADY
DIMINISHED OVER THE STRAITS OF FLORIDA.

CARIBBEAN...
UPPER HIGH IN THE E PACIFIC ALSO COVERS THE W CARIBBEAN W OF 75W
AS THE UPPER LOW SHIFTS FURTHER E TO JUST N OF THE LEEWARD
ISLANDS WITH THE UPPER TROUGH CONTINUING MAINLY S TO NEAR
13N66W. STRONG SUBSIDENCE AND DRY AIR DOMINATES MOST OF THE
BASIN. A SURFACE REFLECTION IN THE FORM OF A SURFACE TROUGH
EXTENDS FROM NEAR 22N65W ACROSS THE MONA PASSAGE TO NEAR 15N70W.
THIS SURFACE TROUGH HAS BEEN REPOSITIONED BASED ON SURFACE DATA
AND EARLIER QUIKSCAT PASS. THIS FEATURE IS STILL GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER PUERTO RICO...THE
VIRGIN ISLANDS AND THE REGIONAL COASTAL WATERS. THE SE CARIBBEAN
IS UNDER THE INFLUENCE OF A STRONG UPPER RIDGE THAT IS ANCHORED
IN THE TROPICAL ATLC NEAR 6N36W GIVING THE AREA SW UPPER FLOW.
THESE WINDS ARE ADVECTING TROPICAL MOISTURE FROM NORTH SOUTH
AMERICA INTO THE SE CARIBBEAN AND THE TROPICAL N ATLANTIC.
MODERATE TO STRONG EASTERLY WINDS ARE OVER THE W CARIBBEAN W OF
75W WHILE THE REMAINDER OF THE CARIBBEAN IS UNDER LIGHT/MODERATE
SURFACE WINDS.

ATLANTIC...
AN UPPER LEVEL TROUGH DOMINATES THE FLOW NORTH OF 20N WEST OF
60W...WITH A SHORT WAVE TROUGH MOVING E ACROSS THE CENTRAL
BAHAMAS AND ANOTHER UPPER LEVEL TROUGH EXTENDING ACROSS THE
VIRGIN ISLES TO THE EASTERN CARIBBEAN. A SURFACE REFLECTION IN
THE FORM OF A SURFACE TROUGH LIES ACROSS THE MONA PASSAGE. AN
AREA OF SCATTERED MODERATE CONVECTION IS FOUND E OF THE TROUGH
FROM 20N-28N BETWEEN 45W-65W. A DIFFLUENT PATTERN ALOFT BETWEEN
THE UPPER TROUGH AND STRONG UPPER RIDGE THAT DOMINATES THE
EAST-CENTRAL ATLC IS ENHANCING THIS CONVECTIVE ACTIVITY. LATEST
SAT VIS IMAGERY SHOWS A SWIRL OF LOW CLOUDS FORMING NEAR 21N67W.
MODEL GUIDANCE CONTINUE TO DEVELOP A WEAK SFC LOW PROBABLY NE OF
PUERTO RICO AND MOVE IT ENE ALONG REMNANTS OF A FRONT BOUNDARY
THAT EXTENDS FROM 23N57W NE TO BEYOND 32N38W. A BAND OF MOISTURE
IS FORECAST TO PERSIST OVER THE NE CARIBBEAN DURING THE NEXT FEW
DAYS KEEPING THE CHANCES OF RAINFALL OVER THE AREA. BROAD
SURFACE RIDGE REMAINS OVER THE E ATLC E OF THE COLD FRONT
ANCHORED BY A 1030 MB HIGH SE OF THE AZORES. THIS AREA REMAINS
RATHER TRANQUIL WITH ONLY SCATTERED FRAGMENTS OF LOW LEVEL
CLOUDS.

$$
GR






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