[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 160004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED AUG 15 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 ERIN REMAINS POORLY ORGANIZED AS IT APPROACHES
THE TEXAS COAST. THE CENTER OF TROPICAL STORM ERIN WAS NEAR
26.5N 95.1W AT 16/0000 UTC OR ABOUT 125 NM/235 KM EAST-NORTHEAST
OF BROWNSVILLE TEXAS AND ABOUT 170 NM/310 KM SOUTH OF GALVESTON
TEXAS. ERIN IS MOVING NORTHWEST NEAR 11 KT. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 35 KT WITH GUSTS TO 45 KT. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. PLEASE SEE THE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT5/WTNT25 KNHC OR THE LATEST PUBLIC ADVISORY UNDER
MIATCPAT5/WTNT35 KNHC FOR MORE DETAILS. RAINBANDS ASSOCIATED
WITH ERIN ARE AFFECTING THE TEXAS COAST. TOTAL RAIN
ACCUMULATIONS OF 3 TO 5 INCHES ARE POSSIBLE ALONG THE MIDDLE
TEXAS COAST...WITH ISOLATED MAXIMUM AMOUNTS OF 8 INCHES. SOME
STRENGTHENING OF ERIN IS POSSIBLE BEFORE SHE MAKES LANDFALL
THURSDAY MORNING.

THE CENTER OF TROPICAL STORM DEAN WAS NEAR 13.1N 47.9W OR ABOUT
790 NM EAST OF THE LESSER ANTILLES AT 15/2100 UTC MOVING WNW 19
KT. MAXIMUM SUSTAINED WIND SPEEDS ARE 55 KT WITH GUSTS TO 65 KT.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. FURTHER
STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS AND DEAN
COULD BECOME A HURRICANE LATER TONIGHT OR EARLY THURSDAY. PLEASE
SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC OR THE LATEST PUBLIC ADVISORY UNDER
MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. ASSOCIATED MODERATE TO
STRONG CONVECTION IS FROM 10N-15N BETWEEN 47W-52W...WITH A
TIGHTLY CURVED BAND WRAPPING AROUND THE CENTER. BUOY 41041 NOW
TO THE NE OF DEAN HAS BEEN REPORTING 20-30 KT WINDS WITH SEAS
UPWARDS OF 15 FT OVER THE LAST FEW HOURS...WHICH IS SLIGHTLY
ABOVE THE NORTH ATLANTIC HURRICANE WW3 GUIDANCE.

...TROPICAL WAVES...
AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 31W SOUTH OF
19N MOVING WEST NEAR 15 KT. A 1010 MB LOW PRESSURE CENTER IS
ALONG THE WAVE NEAR 14N. THIS WAVE CONTINUES TO EXHIBIT A BROAD
AREA OF CYCLONIC TURNING IN THE SURROUNDING LOW AND MID CLOUD
FIELD...THOUGH SHOWER AND TSTM ACTIVITY REMAINS MINIMAL.

A TROPICAL WAVE IS MOVING THROUGH THE LESSER ANTILLES ALONG
60/61W MOVING W 15-20 KT. THIS WAVE CONTINUES TO EXHIBIT AN
INVERTED V SHAPE IN THE SURROUNDING LOW AND MID LEVEL CLOUDS.
DEEP CONVECTION REMAINS MINIMAL THOUGH A FEW ISOLATED SHOWERS
ARE MOVING THROUGH THE WINDWARD ISLANDS.

...THE ITCZ...
AXIS IS CENTERED ALONG 12N15W 9N27W 13N43W 9N52W 8N58W. OUTSIDE
OF THE ACTIVITY ASSOCIATED WITH T.S. DEAN AS DESCRIBED
ABOVE...LITTLE DEEP CONVECTION IS NOTED. HOWEVER...A LARGE
REGION OF CLOUDINESS AND EMBEDDED ISOLATED MODERATE CONVECTION
IS MOSTLY E OF 20W FROM 6N-18N...WHICH SEEMS ASSOCIATED WITH THE
NEXT TROPICAL WAVE ABOUT TO MOVE OFF THE AFRICAN COAST. ANOTHER
SMALL REGION OF ISOLATED MODERATE CONVECTION IS S OF THE AXIS
FROM 5N-8N BETWEEN 22W-27W.

DISCUSSION...

THE GULF OF MEXICO...
TROPICAL STORM ERIN REMAINS THE FOCUS TONIGHT...WHICH IS
PRODUCING NUMEROUS SHOWERS/ISOLATED TSTMS N OF 24N W OF 90W.
MORE DETAILS ON ERIN CAN BE FOUND IN THE SPECIAL FEATURE SECTION
ABOVE. IN ADDITION...THE SE GULF IS ALSO ACTIVE THIS EVENING
WITH NUMEROUS MODERATE/ISOLATED STRONG CONVECTION S OF 27N E OF
90W. LOW LEVEL CONFLUENCE SE OF ERIN IS SPARKING THIS
ACTIVITY...WITH FURTHER SUPPORT FROM DIFFLUENT FLOW ALOFT AROUND
THE SE PERIPHERY OF AN UPPER RIDGE. CLOUD TOPS ARE BEING
STRETCHED TO THE S TOWARDS THE CARIBBEAN WITH UPPER NLY FLOW
OVER THIS ACTIVITY. ALL OF THIS MOISTURE EXPECTED TO CONTINUE
PUSHING NW OVER THE NEXT COUPLE OF DAYS AS ERIN MOVES INLAND.

THE CARIBBEAN SEA...
SCATTERED SHOWERS AND TSTMS ARE ALSO AFFECTING THE FAR NW
CARIB/YUCATAN CHANNEL THIS EVENING AS DESCRIBED ABOVE IN THE
GULF SECTION. OTHERWISE THE CARIBBEAN REMAINS PRETTY QUIET.
ASSISTING IN THE TRANQUIL CONDITIONS IS CONFLUENT UPPER FLOW AND
DRY MID TO UPPER AIR OVER MUCH OF THE AREA EXCEPT FOR THE NW
PORTION...WHERE NE FLOW AROUND RIDGING IS SPREADING ABUNDANT
UPPER MOISTURE FROM THE GULF INTO THE AREA. AN INVERTED UPPER
TROUGH EXTENDS SSW FROM RINCON PUERTO RICO TO NEAR 12N72W. THIS
IS LIKELY ASSISTING IN THE ISOLATED SHOWERS IN THE MONA PASSAGE.
TRADES ARE MODERATE AT THE MOMENT BUT THAT IS EXPECTED TO CHANGE
LATER IN THE WEEK AND INTO THE WEEKEND AS DEAN NEARS. INTERESTS
IN THE LESSER ANTILLES SHOULD MONITOR THE PROGRESS OF DEAN.

THE ATLANTIC OCEAN...
THE WRN ATLC W OF 72W IS PRETTY QUIET TONIGHT WITH VERY DRY MID
TO UPPER AIR BEING ADVECTED SWD THROUGH THE AREA...BY UPPER NLY
FLOW AROUND AN UPPER LOW NEAR 28N72W. LIFT AHEAD OF THIS UPPER
LOW IS SUPPORTING CLOUDINESS AND A FEW SHOWERS AND TSTMS BETWEEN
62W-71W. IN ADDITION A WEAK 1015 MB SFC LOW IS NEAR 30N69W WHICH
HAS A TROUGH EXTENDING SW TO THE SE BAHAMAS NEAR 22N75W. THIS
LOW IS EXPECTED TO DISSIPATE OVER THE NEXT DAY OR SO AS RIDGING
BUILDING BACK OVER THE WRN ATLC. A MOSTLY BENIGN UPPER LOW IS
NOTED NEAR 30N45W. DEEP LAYER RIDGING IS N OF DEAN AND IS
EXPECTED TO STRENGTHEN OVERNIGHT...FORCING THE STORM ON MORE OF
A WWD COURSE TOMORROW. THE REMAINDER OF THE AREA N OF 20N E OF
55W IS DOMINATED BY FAIR WEATHER AND LIGHT TO MODERATE WINDS S
OF A 1031 MB HIGH NEAR 44N31W. THE EXCEPTION REMAINS STRONGER NE
WINDS OFF THE COAST OF NW AFRICA WHERE A STRONGER GRADIENT
EXISTS BETWEEN THE ATLC RIDGING AND THERMAL TROUGHING OVER LAND.

$$
WILLIS




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