[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 142359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE AUG 14 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM DEAN WAS CENTERED NEAR 11.6N 41.0W...OR ABOUT
1200 NM E OF THE LESSER ANTILLES AT 14/2100 UTC MOVING W AT 18
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM
SUSTAINED WINDS ARE 35 KT WITH GUSTS TO 45 KT. SOME
STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS AS DEAN
CONTINUES MOVING W OR WNW SOUTH OF A DEEP-LAYERED RIDGE. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. SCATTERED MODERATE
CONVECTION IS MOSTLY STRETCHED TO THE W OF THE CENTER FROM
10N-12N BETWEEN 41W-45W. HOWEVER...A NEW CLUSTER OF MODERATE TO
STRONG CONVECTION HAS FORMED CLOSER TO THE CENTER WITHIN 30NM OF
11.5N41W.

A 1007 MB LOW IS OVER THE SOUTHERN GULF OF MEXICO NEAR 23N91W
MOVING WEST-NORTHWEST OR NORTHWEST NEAR 10 KT. DATA FROM AN AIR
FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT EARLIER THIS
AFTERNOON INDICATED THAT THE SYSTEM DID NOT YET HAVE A WELL
DEFINED CIRCULATION CENTER. HOWEVER...UPPER-LEVEL WINDS CONTINUE
TO BECOME MORE FAVORABLE FOR DEVELOPMENT AND A TROPICAL
DEPRESSION COULD FORM AT ANY TIME TONIGHT OR TOMORROW. AIRCRAFT
DATA INDICATE THAT MAXIMUM WINDS WITH THE LOW ARE CURRENTLY
AROUND 25 MPH. ALL INTERESTS IN THE NORTHWESTERN GULF OF
MEXICO...INCLUDING THE COASTAL AREAS OF TEXAS AND NORTHEASTERN
MEXICO...SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM...AS
TROPICAL STORM WARNINGS WOULD LIKELY BE REQUIRED IMMEDIATELY
UPON THE INITIATION OF ADVISORIES.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 26W S OF 19N MOVING W 15-20 KT. A 1010 MB
LOW IS ALONG THE WAVE AXIS NEAR 15N OR ABOUT 150 NM SW OF THE
WRN CAPE VERDE ISLANDS. THIS WAVE CONTINUES TO SHOW UP WELL IN
SATELLITE IMAGERY WITH A BROAD AREA OF CYCLONIC TURNING NOTED IN
THE SURROUNDING LOW AND MID CLOUDS. THERE IS ONE SMALL CLUSTER
OF MODERATE CONVECTION WITHIN 30NM OF 15.5N27W BUT OVERALL
SHOWER AND TSTM ACTIVITY REMAINS MINIMAL NEAR THE WAVE.

TROPICAL WAVE PREVIOUSLY ALONG 50W WAS ADJUSTED SLIGHTLY TO THE
WEST TO 54W S OF 17N...MOVING W 10-15 KT. THE RELOCATION WAS
WARRANTED DUE TO THE EVIDENCE OF AN INVERTED V SHAPE IN THE
SURROUNDING LOWER TO MID LEVEL CLOUDS. IN ADDITION THE WAVE
SHOWS UP WELL AS A WWD PROPAGATING SURGE OF MOISTURE IN THE
UW-CIMSS TPW PRODUCT. THERE DOES APPEAR TO BE A SMALL CYCLONIC
SWIRL JUST TO THE W OF T.S. DEAN NEAR 11N49W. I SUSPECT THIS IS
EITHER NORMAL VORTICITY EMBEDDED IN THE ITCZ...OR THE LOW
AMPLITUDE WAVE THAT WAS DROPPED YESTERDAY BEGINNING TO SHOW ITS
FACE AGAIN.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N16W 13N24W 13N37W 10N48W 10N56W
9N63W. ISOLATED CLUSTERS OF MODERATE CONVECTION ARE FROM 8N-13N
BETWEEN 25W-33W. OUTSIDE OF THIS ACTIVITY AND THAT ASSOCIATED
WITH T.S. DEAN...NOT MUCH ELSE IS NOTED.

DISCUSSION...

GULF OF MEXICO...
THE MAIN FOCUS CONTINUES TO BE THE SPECIAL FEATURE IN THE SRN
GULF. THIS SYSTEM...IN ADDITION TO DIFFLUENT FLOW ALOFT BETWEEN
AN UPPER LOW MOVING THROUGH DEEP SOUTH TEXAS AND AN UPPER HIGH
OVER THE NRN GULF NEAR 27N88W...IS PRODUCING WIDESPREAD
CLOUDINESS/SHOWERS AND ISOLATED TSTMS OVER MUCH OF THE GULF S OF
28N BETWEEN 85W-95W. THIS MOISTURE WILL CONTINUE MOVING WNW/NW
TOWARDS THE NE MEXICO AND TEXAS COASTS OVER THE NEXT DAY OR SO.
THE OTHER INTERESTING FEATURE THIS EVENING IS THE SQUALL LINE
MOVING QUICKLY N FROM WRN CUBA THROUGH THE STRAITS OF FLORIDA.

CARIBBEAN SEA...
THE CARIBBEAN IS QUIET IN COMPARISON TO THE GULF ALTHOUGH
ISOLATED TSTMS PERSIST IN THE FAR NW AND SW PORTIONS. TRADES ARE
MOSTLY MODERATE 10-20 KT AND BEND MORE SE IN THE NW PORTION
BEHIND THE LOW IN THE GULF. SIMILAR TRADES EXPECTED THROUGH THU
BUT T.S. DEAN MAY AFFECT THE ERN PORTION LATER IN THE WEEK AND
INTO THE WEEKEND. INTERESTS IN THE LESSER ANTILLES SHOULD
MONITOR THE PROGRESS OF DEAN. UPPER NE FLOW AROUND RIDGING FROM
THE GULF DOMINATES THE NW PORTION OF THE CARIB TONIGHT WHILE
UPPER CYCLONIC FLOW IS OVER THE ERN PORTION...AROUND AN UPPER
LOW JUST N OF PUERTO RICO.

ATLANTIC OCEAN...
A REMNANT FRONTAL TROUGH EXTENDS SW FROM 31N64W TO THE BAHAMAS
NEAR 26N78W. THIS ALONG WITH UPPER DIFFLUENCE BETWEEN AN UPPER
TROUGH OFF THE EASTERN SEABOARD AND A NARROW RIDGE EXTENDING ENE
FROM THE CENTRAL BAHAMAS TO 27N68W...IS SUPPORTING WIDESPREAD
CLOUDINESS...SCATTERED SHOWERS...AND ISOLATED TSTMS WITHIN 90NM
EITHER SIDE OF THE LINE 24N80W 26N71W 32N62W. SKIES ARE MUCH
CLEARER BEHIND THE BOUNDARY OFFSHORE NORTH FLORIDA. DEEP LAYER
RIDGING DOMINATES MUCH OF THE REMAINDER OF THE CENTRAL AND
EASTERN ATLC WHICH IS PUSHING T.S. DEAN QUICKLY TO THE W. BENIGN
UPPER LOWS NOTED NEAR 32N46W AND 26N30W. A 1024 MB SFC HIGH NEAR
33N39W HAS MODERATE TRADES AND FAIR WEATHER N OF 18N E OF 45W.
NE FLOW REMAINS A BIT STRONGER OFF THE COAST OF NW AFRICA WHERE
A TIGHTER GRADIENT EXISTS BETWEEN RIDGING AND THERMAL TROUGHING
OVER THE LAND. FIND DETAILS ON T.S. DEAN IN SPECIAL FEATURE
SECTION ABOVE.

$$
WILLIS


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