[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 100555
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU MAY 10 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.

...SPECIAL FEATURE...

SUBTROPICAL STORM ANDREA WAS CENTERED NEAR 30.5N 79.8W AT
10/0300 UTC OR ABOUT 135 MILES SE OF SAVANNAH GEORGIA AND 115
MILES NE OF DAYTONA BEACH FLORIDA. ANDREA IS NEARLY STATIONARY
WITH NO SIGNIFICANT MOTION EXPECTED OVER THE NEXT 24 HOURS.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED
WINDS ARE 40 KT WITH GUSTS TO 50 KT. SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/ WTNT21 KNHC
FOR MORE DETAILS. MOST OF THE SIGNIFICANT WEATHER REMAINS ON THE
EASTERN HALF OF THE CYCLONE WITH SCATTERED MODERATE CONVECTION
NOTED FROM 28N-33N BETWEEN 77W-79W. BECAUSE ANDREA IS EXPECTED
TO REMAIN OVER COOL WATERS IT SHOULD GRADUALLY WEAKEN.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N13W 6N25W 4N35W EQ50W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM EITHER SIDE
OF THE AXIS BETWEEN 19W-25W. SIMILAR ACTIVITY LIES FROM THE
1S-8N BETWEEN 25W-37W.

...DISCUSSION...

GULF OF MEXICO...
DEEP LAYER N TO NW FLOW ON THE W SIDE OF ANDREA'S LARGE
CIRCULATION IS ENHANCING SUBSIDENCE ABOVE THE ERN HALF OF THE
GULF PROVIDING WIDESPREAD CLEAR SKIES AND FAIR WEATHER. MOST OF
THE SMOKE PLUMES ORIGINATING FROM FIRES IN FLORIDA AND S GEORGIA
HAVE NOW SPREAD BOTH TOWARD THE BAY OF CAMPECHE AND INTO THE WRN
ATLC...STEERED BY THE DIFFLUENT LOW-LEVEL FLOW BETWEEN ANDREA
AND A WEAK 1016 MB HIGH PRES OFF THE COAST OF LOUISIANA. THE
HIGH IS PRODUCING MOSTLY LIGHT 5-15 KT WINDS ACROSS THE GULF
AIDING IN THE TRANQUIL CONDITIONS. SEAS HAVE ALSO CONTINUED TO
COME DOWN ACROSS THE GULF WITH MOST BUOYS/SHIPS NOW IN THE 2-3
FT RANGE. FAIRLY LIGHT WINDS AND MOSTLY FAIR WEATHER IS EXPECTED
TO CONTINUE THROUGH FRI AS WEAK HIGH PRES REMAINS STATIONARY IN
THE MID-GULF...THOUGH SCATTERED SHOWERS/TSTMS POSSIBLE IN THE NW
PORTION WITH THE DYNAMICS AHEAD OF AN APPROACHING MID TO UPPER
LOW/TROUGH.

CARIBBEAN SEA...
THE CONTINUED WEAK PRES PATTERN IN THE WRN CARIB IS ALLOWING
WINDS TO REMAIN VERY LIGHT...GENERALLY 10 KT OR LESS. THE TRADES
INCREASE TO MORE TYPICAL VALUES IN THE CENTRAL AND ERN
CARIB...15-20 KT...AS SFC RIDGING FROM THE NE HAS BUILT INTO THE
REGION. IN THE UPPER LEVELS...A TROUGH/RIDGE PATTERN PERSISTS
WITH ABUNDANT SUBSIDENCE NOTED N OF 12N W OF 78W. PRONOUNCED
UPPER DIFFLUENCE BETWEEN THE TROUGH/RIDGE IS HELPING TO SUPPORT
THE SCATTERED MODERATE CONVECTION FROM 13N-15N BETWEEN 77W-79W
AND ALSO JUST SE OF JAMAICA. SW UPPER FLOW IS TRANSPORTING A
SWATH OF MOISTURE NE THROUGH THE CENTRAL CARIB INTO THE ATLC.
MORE IMPRESSIVE CONVECTION ASSOCIATED WITH THE ITCZ HAS RECENTLY
FLARED UP IN THE SW CARIB S OF 12N E OF 81W.

ATLANTIC...
SUBTROPICAL STORM ANDREA REMAINS THE AREA OF FOCUS THIS
EVENING...FOR DETAILS REFER TO THE SPECIAL FEATURE SECTION
ABOVE. SWELL ASSOCIATED WITH ANDREA HAS CONTINUED TO OVERALL
STEADILY SUBSIDE OVER THE LAST COUPLE OF DAYS. HOWEVER...SEAS
HAVE BEEN SLOWER TO RELAX OFF THE GEORGIA THROUGH SOUTHERN NORTH
CAROLINA COAST...DOWNSTREAM FROM A MORE FAVORABLE FETCH
ASSOCIATED WITH THE INTERACTION BETWEEN ANDREA AND A 1026MB HIGH
PRES OFF THE MID ATLC COAST NEAR 37N55W. AN UPPER DIFFLUENT ZONE
TO THE E OF ANDREA...BETWEEN THE STORM'S EMBEDDED TROUGH AND
RIDGING TO THE E...IS GENERATING SCATTERED SHOWERS AND ISOLATED
TSTMS BETWEEN 62W-75W.

FARTHER E...A SFC TROUGH IS ALONG 32N41W 26N50W WITH A WEAK
1018MB LOW ON THE TROUGH NEAR 28N47W. ISOLATED SHOWERS POSSIBLE
WITHIN 90NM EITHER SIDE OF THE TROUGH. AN UPPER LOW IS OVER
THESE SFC FEATURES NEAR 26N47W. THE SRN PERIPHERY OF A
STATIONARY 1025MB HIGH SE OF THE AZORES NEAR 36N20W DOMINATES
THE E ATLC AREA E OF 40W. UW-CIMMS SAHARAN AIR ANALYSIS DEPICTS
A FAIRLY DENSE AREA OF DUST E OF ABOUT 30W. THIS VERY DRY AIR
HAS CLEARED MOST OF THE LOW TO MID LEVEL CLOUDS IN THE ERN-MOST
ATLC.

$$
WILLIS




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