[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 050603
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT MAY 05 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0530 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N10W 1N20W 3N30W 2N50W. ISOLATED
CLUSTERS OF MODERATE CONVECTION GENERALLY DOT THE ENTIRE ATLC
AREA WITHIN 90NM EITHER SIDE OF THE AXIS BETWEEN SOUTH AMERICA
AND AFRICA. HOWEVER...THE MODERATE CONVECTION IS MORE NUMEROUS
IN NATURE WITH POCKETS OF ISOLATED STRONG CONVECTION FROM EQ-4N
BETWEEN 20W-30W.

...DISCUSSION...

GULF OF MEXICO...
MODERATE RETURN FLOW DOMINATES THE GULF AROUND A WEAK 1016MB
HIGH IN THE NE PORTION NEAR 29N85W. THE BLOW UP OF CONVECTION IN
THE NRN GULF/S OF MISSISSIPPI AND ALABAMA HAS CONTINUED TO
DIMINISH OVER THE LAST FEW HOURS. UPPER RIDGING IS BUILDING INTO
THE WRN GULF BEHIND THE TROUGHING DOMINATING THE ERN GULF. AN
EMBEDDED UPPER LOW IS NOTED IN WV IMAGERY OVER THE SE GULF NEAR
24N84W. THIS...IN ADDITION TO SEA BREEZES COLLIDING AND DAYTIME
HEATING EFFECTS...LIKELY AIDED THE CONVECTION OVER FLORIDA
DURING FRI WHICH HAS NOW DIMINISHED. LIGHT TO MODERATE E TO SE
WINDS EXPECTED E OF 90W THROUGH THE WEEKEND...AROUND THE
PERIPHERY OF SFC RIDGING. STRONGER RETURN FLOW DEVELOPS W OF 90W
WHERE A STRONGER GRADIENT IS EXPECTED IN RESPONSE TO LOWER
PRESSURE OVER MEXICO. THIS WILL ALLOW SE WIND WAVES TO BUILD
THROUGH SUN FOR THE WRN GULF...WITH WW3 GUIDANCE SHOWING SEAS
NEARING 10' BY SUNDAY AFTERNOON AT BUOY 42020.

CARIBBEAN SEA...
MODERATE TRADES DOMINATE MUCH OF THE BASIN EXCEPT FOR THE NORTH
CENTRAL PORTION...N OF 16N BETWEEN 67W-82W...WHERE LIGHTER AND
MORE VARIABLE WINDS EXIST. TRADE FLOW HAS BEEN DISRUPTED HERE
DUE TO THE TROUGHING IN THE SW NORTH ATLC. THE TRADES ARE
ADVECTING THEIR TYPICAL PATCHES OF LOW LEVEL MOISTURE WWD THIS
EVENING...THOUGH THE MAIN THING NOTED IN TONIGHTS SATELLITE
PICTURES IS THE ABUNDANT UPPER MOISTURE/HIGH CLOUDINESS
STREAMING NE ESPECIALLY E OF 80W...DOWNSTREAM FROM ITCZ
CONVECTION. AN UPPER TROUGH IS BUILDING INTO THE WRN GULF WHILE
BROAD RIDGING FROM SOUTH AMERICA GENERALLY DOMINATES THE ERN
PORTION. LIGHT TO MODERATE TRADES EXPECTED ACROSS THE CARIB
THROUGH THE WEEKEND...ALTHOUGH TROUGHING FROM THE ATLC EXPECTED
TO CONTINUE TO AFFECT THE WINDS/WEATHER IN THE NRN PORTION.

ATLANTIC...
MAIN FEATURE IN THE WRN ATLC CONTINUES TO BE THE SFC TROUGH
EXTENDING NE FROM THE TURKS AND CAICOS. THIS...ALONG WITH UPPER
DIFFLUENCE BETWEEN AN UPPER TROUGH OVER THE WRN ATLC AND AND
UPPER RIDGE OVER THE CENTRAL ATLC...IS SUPPORTING THE OVERCAST
CLOUDINESS WITH SCATTERED SHOWERS/ISOLD TSTMS N OF 20N BETWEEN
57W-72W. MODEL GUIDANCE HAS NOT BEEN HANDLING THIS SITUATION
PARTICULARLY WELL. FOR WHAT ITS WORTH...GFS LIFTS ONE LOW LEVEL
VORT MAX NE OVER THE WEEKEND WITH TROUGHING TRAILING SW TOWARDS
HISPANIOLA. GUIDANCE HAS ALSO BEEN DIVERGENT ON THE DEVELOPMENT
OF ANOTHER LOW OFF THE SE US COAST LATE SUN/EARLY NEXT
WEEK...THOUGH THE 00Z GFS SEEMS A LITTLE MORE IN LINE WITH THE
OTHER GLOBAL MODELS THAN THE 04/18Z GFS RUN WAS. OTHERWISE MUCH
OF THE REMAINDER OF THE ATLC DISCUSSION AREA IS DOMINATED BY THE
SRN PERIPHERY OF A 1030MB SFC HIGH S OF THE AZORES NEAR 36N29W.
THERE IS AN UPPER TROUGH EXTENDING S THROUGH THE ERN ATLC ALONG
35W...BUT DOES NOT APPEAR TO BE GENERATING ANY SIGNIFICANT
WEATHER.

$$
WILLIS




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