[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041035
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI SEP 04 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND 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
0945 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS FROM 18N22W THROUGH A 1010 MB LOW NEAR 14.5N22W
TO 9N20W MOVING NW NEAR 15 KT. WAVE REMAINS EMBEDDED WITHIN A
BROAD AREA OF DEEP LAYERED MOISTURE MAXIMUM AS INDICATED BY THE
TOTAL PRECIPITABLE WATER IMAGERY. SATELLITE IMAGERY SHOWERS A
BROAD LOW/MID LEVEL CYCLONIC ROTATION. SCATTERED MODERATE
CONVECTION IS FROM 13N-16N BETWEEN 22-24W.

TROPICAL WAVE IS ALONG 34W/35W S OF 18N WITH A 1011 MB LOW ALONG
THE WAVE NEAR 14N MOVING W NEAR 10 KT. THE WAVE COINCIDES WITH A
DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER
IMAGERY. HOWEVER...SATELLITE IMAGERY AND THE TPW IMAGERY
INDICATE DRY SAHARAN AIR LAYER HAS BEING INJECTED INTO THE WAVE
JUST S OF THE LOW LEVEL CENTER. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 15N-17N BETWEEN 34W-36W.

TROPICAL WAVE IS ALONG 51W/52W S OF 17N MOVING W NEAR 10 KT.
WAVE REMAINS LOW-AMPLITUDE AND EMBEDDED WITHIN THE ITCZ AT THE
LEADING EDGE OF A MOISTURE MAXIMUM AS INDICATED BY TOTAL
PRECIPITABLE WATER IMAGERY. WAVE IS ALSO EMBEDDED WITHIN SAHARAN
DUST THUS LIMITING ANY SHOWERS/CONVECTION.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 16N15W 12N23W 9N31W 8N44W 9N62W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
WITHIN 90 NM OF THE ITCZ FROM 22W-28W. CLUSTERS OF SCATTERED
MODERATE CONVECTION ARE WITHIN 180 NM S OF THE ITCZ FROM
31W-53W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH THAT COVERS THE E HALF OF THE U.S. EXTENDS S
COVERING THE ENTIRE GULF TO ACROSS THE YUCATAN PENINSULA AND S
MEXICO. A REMNANT SURFACE TROUGH EXTENDS ACROSS THE FLORIDA
PENINSULA ENTERING THE GULF NEAR FORT MYERS TO 26N87W. SCATTERED
SHOWERS/THUNDERSTORMS ARE OVER THE SE GULF S OF THE SURFACE
TROUGH TO 23N E OF 86W ACROSS S FLORIDA. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE OVER THE NE GULF N OF 27N E OF 89W.
EVEN THOUGH THERE IS DRY AIR IN THE UPPER LEVELS ACROSS THE
CENTRAL GULF...THERE IS ENOUGH SURFACE MOISTURE TO GENERATE
ISOLATED SHOWERS DOTTING THE REMAINDER OF THE GULF.

CARIBBEAN SEA...
THE REMNANT 1010 MB LOW OF ERIKA IS CENTERED OVER THE NE
CARIBBEAN NEAR 17N65W AND IS CONTINUING TO GENERATE SCATTERED
SHOWERS/THUNDERSTORMS FROM 14N-19N BETWEEN 62W-66W INCLUDING THE
LEEWARD AND VIRGIN ISLANDS. THE UPPER TROUGH OVER THE GULF OF
MEXICO COVERS THE NW CARIBBEAN N OF 15N W OF 80W GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS NW OF LINE FROM CUBA
NEAR 22N81W TO THE YUCATAN PENINSULA NEAR N BELIZE. AN UPPER
RIDGE COVERS THE REMAINDER OF THE CARIBBEAN ANCHORED OVER THE SE
NEAR 13N69W DRAWING TROPICAL MOISTURE OVER THE SW CARIBBEAN AND
COUPLED WITH THE ITCZ EXTENDING ACROSS THE AREA FROM COLOMBIA TO
COSTA RICA INTO THE E PACIFIC REGION IS GENERATING SCATTERED
SHOWERS/THUNDERSTORMS S OF A LINE FROM NICARAGUA NEAR 15N84W TO
COLOMBIA NEAR 11N75W INCLUDING PORTIONS OF PANAMA AND COSTA
RICA.

ATLANTIC OCEAN...
A SURFACE TROUGH ENTERS THE REGION NEAR 32N76W EXTENDING SW TO A
1013 MB LOW OFF THE COAST OF DAYTONA BEACH FLORIDA CONTINUING
ACROSS THE FLORIDA PENINSULA INTO THE GULF OF MEXICO. BROAD
UPPER RIDGE REMAINS ANCHORED OVER THE W ATLC NEAR 31N71W
PROVIDING DIFFLUENCE ALOFT TO GENERATE CLUSTERS OF SCATTERED
SHOWERS/THUNDERSTORMS FROM 23N-29N BETWEEN 76W-80W INCLUDING THE
N BAHAMA ISLANDS. SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS DOT THE REMAINDER OF THE AREA W OF 75W. THE BROAD
UPPER TROUGH OVER THE E ATLC AND THE UPPER RIDGE OVER THE E
CARIBBEAN COMBINE TO PRODUCE AN AREA OF DIFFLUENCE ALOFT TO
GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS IN THE CENTRAL
ATLC WITHIN 90/120 NM OF LINE FROM 28N61W TO 22N48W.
OTHERWISE...THE REMAINDER OF THE ATLC IS DOMINATED BY A BROAD
SURFACE RIDGE BETWEEN 20W-70W ANCHORED BY A 1027 MB HIGH WELL N
OF THE REGION JUST S OF THE AZORES AND A 1023 MB HIGH E OF
BERMUDA NEAR 32N57W.

$$
WALLACE




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