[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 081046
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE MAY 08 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1030 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N13W 4N20W 2N30W 2N40W 2N51W.
NUMEROUS MODERATE CONVECTION WITH EMBEDDED ISOLATED STRONG
ACTIVITY IS WITHIN 120NM EITHER SIDE OF THE AXIS BETWEEN
14W-27W. SCATTERED MODERATE TO STRONG ACTIVITY IS FROM 4S-3N
BETWEEN 27W-42W.

...SPECIAL FEATURE...

AN OCCLUDED 1001 MB SFC LOW WAS LOCATED NEAR 30.5N 76.5W AT
08/0900 UTC...OR ABOUT 250NM E OF THE FLORIDA/GEORGIA
BORDER...MOVING W AT ABOUT 10 KT. A STORM WARNING ASSOCIATED
WITH THIS SYSTEM IS IN AFFECT FOR THE OFFSHORE AREA N OF 29N W
OF 76W BUT IS EXPECTED TO RELAX TO GALE CONDITIONS THROUGH THE
DAY. THIS WAS VERIFIED BY LAST EVENINGS QUIKSCAT PASS WHICH
SHOWED 50-60 KT WINDS OFF THE SOUTHEAST COAST. THESE WINDS ARE
CONTINUING TO PRODUCE A SIGNIFICANT SWELL EVENT FOR THE
SOUTHEAST U.S. COAST AND THE BAHAMAS. BUOY 41010 HAS BEEN
REPORTING 20-25 FT SEAS AT 16 SEC OVER THE LAST SEVERAL HOURS.
THE REGIONAL WW3 MODEL NOW SEEMS ON TRACK WITH THE HEIGHTS BUT
CONTINUES TO UNDERESTIMATE THE PERIODS WHICH WILL FURTHER ADD TO
THE BREAKING WAVE HEIGHTS UPON SHOALING. LIGHTNING DATA HAS BEEN
DEPICTING SCATTERED TSTMS IN THE MODERATE CONVECTION SEEN WITHIN
150NM N AND W OF THE CENTER. THE MAIN THREAT...HOWEVER...WILL
CONTINUE TO BE THE HIGH WINDS AND WAVES ASSOCIATED WITH THE
SYSTEM. THE MODEL CONSENSUS IS TO CONTINUE MOVING THE LOW
TOWARDS NORTH FLORIDA/GEORGIA OVER THE NEXT DAY OR SO WHILE
SLOWLY WEAKENING. PLEASE REFER TO THE HIGH SEAS FORECASTS AND
STATEMENTS FROM LOCAL WEATHER FORECAST OFFICES FOR MORE DETAILS
REGARDING EXPECTED OFFSHORE AND COASTAL IMPACTS.

...DISCUSSION...

GULF OF MEXICO...
A WEAKENING BACKDOOR COLD FRONT ASSOCIATED WITH THE LARGE
OCCLUDED LOW PRES SYSTEM IN THE W ATLC CONTINUES TO SLOWLY PUSH
SW IN THE GULF. THE FRONT WAS ANALYZED FROM THE YUCATAN CHANNEL
TO SW LOUISIANA AND IS MARKED BY PATCHES OF LOW TO MID CLOUDS.
BEHIND THE FRONT...15-20 KT E/NE WINDS ARE USHERING IN FAIRLY
COMFORTABLE TEMPS AND A NOTICEABLE DROP IN HUMIDITY. WINDS AND
SEAS WILL DIMINISH THROUGH WED AS HIGH PRES BUILDS OVER THE GULF
BEHIND THE FRONT. ABUNDANT SUBSIDENCE IS KEEPING SKIES FAIR TO
MAINLY CLEAR IN THIS REGION. W OF THE FRONT...THE AIRMASS IS
MORE HUMID BUT OTHERWISE THE WEATHER CONDITIONS ARE SIMILAR WITH
FAIR SKIES AND BRISK E TO SE WINDS. THE WEATHER IS MUCH MORE
ACTIVE OVER NE MEXICO AND SRN TX WHERE STRONG TSTMS EXIST...S OF
A STALLED FRONT AND ALSO AIDED BY A DIFFLUENT PATTERN ALOFT.
UPPER MOISTURE OVER THIS CONVECTION IS SPREADING EWD INTO THE
WRN GULF AROUND AND UPPER RIDGE.

CARIBBEAN SEA...
THE LARGE LOW PRES SYSTEM IN THE WRN ATLC IS RESULTING IN A WEAK
PRESSURE PATTERN ACROSS THE CARIB WHICH IS KEEPING E/NE TRADES
FAIRLY LIGHT...MOSTLY IN THE 5-15 KT RANGE EXCEPT TO 20 KT IN
THE SE PORTION. THIS IS GENERALLY EXPECTED TO PERSIST OVER THE
NEXT DAY OR SO. THE BACKDOOR COLD FRONT ASSOCIATED WITH THE
LARGE WRN ATLC LOW IS PUSHING SLOWLY S OF CUBA INTO THE NW
CARIB. SHOWERS ARE GENERALLY ISOLATED AROUND THIS FRONT EXCEPT
FOR MORE PRONOUNCED TSTM ACTIVITY NEAR 20N83W. DEEPER CONVECTION
ASSOCIATED WITH THE ITCZ IS OVER COLOMBIA THE SW CARIBBEAN S OF
12N E OF 79W.  DEBRIS MID-HIGH LEVEL CLOUDS ARE BEING
TRANSPORTED NE FROM THIS CONVECTIVE AREA TO THE LEEWARD ISLANDS
BY STRONG WSW UPPER FLOW.

WESTERN ATLANTIC...
THE HIGHLIGHT CONTINUES TO BE A LARGE OCCLUDED LOW PRES SYSTEM
CENTERED OFF THE SE U.S...SEE SPECIAL FEATURE SECTION ABOVE FOR
MORE DETAILS. A TRAILING FRONT EXTENDS FROM A TRIPLE POINT NEAR
32N68W ACROSS THE SOUTHEAST BAHAMAS. A STATIONARY FRONT RUNS
FROM THE TRIPLE POINT TO 48W ALONG 32N/33N WHERE A FRONTAL WAVE
EXISTS. SCATTERED SHOWERS POSSIBLE WITHIN 120NM OF THE FRONT.
WEAK PREFRONTAL TROUGHING IS N OF PUERTO RICO WITH SHOWERS/TSTMS
ANTICIPATED FROM 19N-23N BETWEEN 65W-69W.

CENTRAL AND EASTERN ATLANTIC...
A 1031 MB AZORES HIGH IS IN CONTROL OF THE PATTERN ACROSS THE
ATLC E OF 45W. THIS HIGH IS PRODUCING A LARGE AREA OF MODERATE
TO FRESH TRADES...STRONGEST E OF 25W WHERE THE PRES GRADIENT IS
TIGHTENED DUE TO SOME INVERTED TROUGHING NEAR THE COAST OF
AFRICA. SCATTERED STRATOCUMULUS COVER MUCH OF THE
REGION...EXCEPT S OF 20N E OF 25W WHERE THIS LOW-LEVEL CLOUD
DECK IS ERODED BY SAHARAN DUST. AN UPPER LOW IS NW OF THE CANARY
ISLANDS NEAR 31N22W THAT HAS ASSOCIATED TROUGHING STRETCHING SWD
ALONG 24W. THIS UPPER SYSTEM IS ONLY GENERATING SCATTERED
PATCHES OF CIRRUS.

$$
WILLIS


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