[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 170005
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU AUG 16 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 DEPRESSION ERIN CONTINUES TO WEAKEN AND MOVE FARTHER
INLAND OVER SOUTH TEXAS. ERIN IS PRODUCING HEAVY RAINS ACROSS
SOUTH-CENTRAL AND SOUTHEAST TEXAS. FURTHER INFORMATION ON THIS
SYSTEM CAN BE FOUND IN PUBLIC ADVISORIES ISSUED BY THE
HYDROMETEOROLOGICAL PREDICTION CENTER...UNDER AWIPS HEADER
TCPAT5 AND WMO HEADER WTNT35 KWNH.

THE CENTER OF HURRICANE DEAN AT 17/0000 UTC WAS NEAR 14.0N 57.8W
OR ABOUT 175 NM/330 KM EAST OF MARTINIQUE. DEAN IS MOVING
WEST 20 KT. THE MAXIMUM SUSTAINED WIND SPEEDS ARE NEAR 85 KT
WITH GUSTS TO 100 KT...WHICH MAKES DEAN A CATEGORY TWO
HURRICANE. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 979 MB.
SOME STRENGTHENING IS FORECAST BEFORE THE HURRICANE REACHES THE
LESSER ANTILLES EARLY FRIDAY. OUTER RAINBANDS OF DEAN ARE MOVING
THROUGH THE WINDWARD ISLANDS. STORM TOTAL RAINFALLS OF 2 TO 5
INCHES...WITH ISOLATED MAXIMUM AMOUNTS OF 7 INCHES IN
MOUNTAINOUS AREAS...ARE POSSIBLE IN ASSOCIATION WITH DEAN.
THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND
MUDSLIDES. 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. NUMEROUS
MODERATE TO STRONG CONVECTION IS CURRENTLY FROM 10N-16N BETWEEN
54W-62W...BUT THIS AREA IS MOVING W FAIRLY RAPIDLY.

...TROPICAL WAVES...
TROPICAL WAVE PREVIOUSLY OFF THE AFRICAN COAST ALONG 17W WAS
ADJUSTED TO 24W S OF 20N DUE TO THE PRESENCE OF THE BROAD
REGION OF LOW TO MID LEVEL CYCLONIC TURNING IN THE VICINITY. THE
WAVE APPEARS TO BE MOVING FAIRLY QUICKLY W 15-20 KT. DEEP
CONVECTION IS MINIMAL.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 37W/38W SOUTH OF 20N
MOVING W 15-20 KT. THIS WAVE CONTINUES TO EXHIBIT CYCLONIC
TURNING IN THE SURROUNDING LOW AND MID LEVEL CLOUDS.
HOWEVER...THE OVERALL ENVELOPE OF THE WAVE APPEARS SMALLER THAN
IT WAS LAST NIGHT...AND ALSO SHIFTED MORE SW THAN IT HAS BEEN. A
FEW SMALL CLUSTERS OF MODERATE CONVECTION ARE FROM 12N-14N
BETWEEN 37W-40W.

A TROPICAL WAVE IS ALONG 69W SOUTH OF 18N MOVING WEST NEAR 20
KT. AN INVERTED V PATTERN REMAINS EVIDENT WITH THIS WAVE...WHICH
ALSO SHOWS UP WELL AS A WWD SURGE OF MOISTURE IN THE UW-CIMSS
TPW PRODUCT. SHOWER AND TSTM ACTIVITY REMAINS MINIMAL OVER THE
CARIBBEAN PORTION OF THE WAVE...THOUGH A SURGE OF SCATTERED
MODERATE CONVECTION IS NOTED INLAND OVER WRN VENEZUELA AND ERN
COLOMBIA.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N15W 11N27W 10N35W 9N42W 14N50W.
SCATTERED MODERATE CONVECTION IS S OF THE AXIS FROM 7N-11N E OF
26W. SIMILAR CLUSTERS OF MOVING OFF THE AFRICAN COAST FROM
11N-16N E OF 19W. SCATTERED MODERATE ALSO WITHIN 150NM S OF THE
AXIS BETWEEN 39W-45W.

DISCUSSION...

THE GULF OF MEXICO...
TROPICAL DEPRESSION ERIN HAS MOVED INLAND OVER SOUTH TEXAS AS
DESCRIBED ABOVE. HOWEVER...A TAIL OF MOISTURE LEFT BEHIND THE
SYSTEM IS PRODUCING NUMEROUS SHOWERS AND TSTMS IN THE NW
GULF...N OF 13N BETWEEN 92W-97W. THE E GULF IS OVERALL MUCH
QUIETER THOUGH A FEW ISOLATE SHOWERS/TSTMS EXIST ESPECIALLY FROM
23N-29N E OF 91W. AN UPPER HIGH IS NEAR THE TEXAS/LOUISIANA
BORDER WHILE WEAK INVERTED UPPER TROUGHING EXTENDS NW FROM THE
YUCATAN CHANNEL. DIFFLUENCE ALOFT BETWEEN THESE FEATURES IS ALSO
SUPPORTING THE AFOREMENTIONED CONVECTION. ELSEWHERE AT THE SFC
RIDGING IS BUILDING INTO THE N GULF BEHIND ERIN AND LOOKS TO BE
THE DOMINANT FEATURE OVER THE NEXT COUPLE OF DAYS. HURRICANE
DEAN EXPECTED TO BECOME AN ISSUE BY EARLY NEXT WEEK BUT
UNCERTAINTIES STILL EXIST IN THE SPECIFICS.

THE CARIBBEAN SEA...
HURRICANE DEAN CONTINUES TO RAPIDLY APPROACH THE LESSER ANTILLES
WITH THE ASSOCIATED CONVECTION NOW AFFECTING THE FAR SE
CARIBBEAN. OTHERWISE ONLY A FEW ISOLATED CELLS OF MODERATE
CONVECTION ARE AFFECTING THE BASIN. DEAN WILL HAVE SIGNIFICANT
IMPACTS ON THE CARIBBEAN OVER THE NEXT FEW DAYS...DETAILS CAN BE
FOUND ABOVE IN THE SPECIAL FEATURES SECTION. N TO NE UPPER FLOW
CONTINUES TO BLOW OVER THE NW CARIBBEAN...WHILE CYCLONIC FLOW IS
OVER THE CENTRAL PORTION S OF AN UPPER LOW NE OF THE BAHAMAS.
UPPER RIDGING FROM THE ATLC IS AFFECTING THE NE CARIB. ASIDE
FROM DEAN AND THE TROPICAL WAVE S OF HISPANIOLA...TRADES ARE
CURRENTLY MODERATE TO FRESH BUT WINDS AND SEAS WILL INCREASE
RAPIDLY IN THE ERN PORTION THROUGH FRI.

THE ATLANTIC OCEAN...
THE DOMINANT FEATURE IN THE WRN ATLC IS THE UPPER LOW NE OF THE
BAHAMAS NEAR 27N75W. THIS HAS BEEN GENERATING A FEW ISOLATED
TSTMS BETWEEN 66W-76W BUT OVERALL THE WRN ATLC IS QUIET. THE
UPPER LOW IS FORECAST TO MOVE W INTO THE GULF THIS WEEKEND WHILE
DEEP LAYER RIDGING REMAINS N OF DEAN...KEEPING IT ON A WWD
TRACK. A REMNANT FRONTAL TROUGH IS ALONG 32N72W 27N77W...BUT
THIS IS EXPECTED TO CONTINUE DISSIPATING THROUGH FRI AS LARGER
SCALE SFC RIDGING BUILDS W. ANOTHER UPPER LOW IS NOTED NEAR
28N47W BUT ONLY APPEARS TO BE GENERATING PATCHES OF CIRRUS.
LARGE SCALE UPPER RIDGING EXTENDS W FROM AFRICA OUT TO 30W. THE
REMAINDER OF THE SFC PATTERN ON THE LARGE SCALE IS DOMINATED BY
THE SRN PERIPHERY OF A 1030 MB HIGH NEAR 42N23W...WHICH IS
PRODUCING MODERATE TRADES AND ABUNDANT FAIR WEATHER N OF 20N E
OF 60W.

$$
WILLIS





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