[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 102338
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI JUL 10 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2300 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS FROM 17N32W TO 5N33W MOVING W 15-20 KT.
SATELLITE IMAGERY INDICATES LOW/MID-LEVEL CYCLONIC FLOW AROUND
THE VICINITY OF THE WAVE AXIS. SATELLITE-DERIVED WINDS INDICATE
CYCLONIC CURVATURE IN THE FLOW WITHIN THE 600-800 MB LAYER. THE
WAVE ALSO LIES JUST W OF A DEEP LAYER MOISTURE MAXIMUM OBSERVED
ON TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS
CURRENTLY ASSOCIATED WITH THE WAVE DUE TO THE PRESENCE OF A LOW
TO MIDDLE LEVEL DRY SAHARAN AIR LAYER.

A TROPICAL WAVE IS W OF  THE LESSER ANTILLES EXTENDING FROM
21N62W TO 10N65W MOVING W 20-25 KT. THIS WAVE IS EMBEDDED WITHIN
A BROAD HIGH AMPLITUDE INVERTED-V CLOUD SIGNATURE...AS WELL AS A
DEEP LAYER MOISTURE MAXIMUM OBSERVED ON TOTAL PRECIPITABLE WATER
IMAGERY. THIS WAVE CONTINUES TO BE JUST W OF THE LEADING EDGE OF
A SAHARAN AIR LAYER CONFINING DEEP CONVECTION TO INLAND OVER
VENEZUELA FROM 8N-11N BETWEEN 63W-67W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N10W 10N20W 7N36W 6N47W AND
INTO S AMERICA NEAR 9N63W. A LARGE CLUSTER OF NUMEROUS
MODERATE/SCATTERED STRONG CONVECTION IS AT THE AFRICAN COAST
FROM 8N-13N BETWEEN 13W-16W. ISOLATED MODERATE CONVECTION IS
FROM 5N-8N BETWEEN 25W-30W. SIMILAR CONVECTION IS WITHIN 150 NM
EITHER SIDE OF THE AXIS BETWEEN 48W-60W.

...DISCUSSION...

GULF OF MEXICO...
SCATTERED SHOWERS/THUNDERSTORMS REMAIN ACROSS THE ERN GULF OF
MEXICO AND THE FLORIDA PENINSULA S OF 29N E OF 87W. THIS SHOWER
ACTIVITY IS SUPPORTED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER
LEVEL HIGH OVER N TEXAS AND AN UPPER LEVEL TROUGH THAT EXTENDS
DOWN THE ERN UNITED STATES COASTLINE. THIS ACTIVITY IS ALSO
ENHANCED BY SURFACE CONVERGENCE NEAR A SURFACE TROUGH THAT
EXTENDS FROM THE WRN ATLC ACROSS THE FLORIDA PENINSULA TO LAKE
OKEECHOBEE NEAR 27N81W. THE UPPER LEVEL HIGH OVER TEXAS IS ALSO
ADVECTING DRY AIR TO THE CENTRAL AND WRN GULF SUPPORTING A
SURFACE RIDGE ALONG 27N. SURFACE CONVERGENCE NEAR A SURFACE
TROUGH IN THE SW GULF OF MEXICO EXTENDING FROM 25N95W TO 18N96W
IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE WRN BAY
OF CAMPECHE S OF 25N W OF 94W.

CARIBBEAN SEA...
THE UPPER LEVEL TROUGH DOWN THE ERN UNITED STATES COASTLINE
EXTENDS INTO THE NW CARIBBEAN TO NEAR 19N86W GENERATING
SCATTERED SHOWERS/THUNDERSTORMS N OF 17N BETWEEN 78W-86W
INCLUDING WRN CUBA. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO
OVER ERN CUBA...HISPANIOLA...AND THE CENTRAL CARIBBEAN N OF 11N
BETWEEN 70W-75W DUE TO UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER
LEVEL LOW OVER JAMAICA NEAR 18N77W AND AN UPPER LEVEL HIGH E OF
THE LESSER ANTILLES NEAR 13N56W. SURFACE CONVERGENCE NEAR THE E
PACIFIC ITCZ AND A 1009 MB SURFACE LOW OVER COLUMBIA NEAR 9N76W
IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS S OF 13N W OF 76W
INCLUDING PORTIONS OF NICARAGUA...COSTA RICA...AND PANAMA. A
TROPICAL WAVE IS IN THE ERN CARIBBEAN..SEE ABOVE. FRESH TO
STRONG TRADE WINDS ARE OCCURRING ACROSS THE MAJORITY OF THE
CARIBBEAN WITH THE STRONGEST FLOW NEAR THE COAST OF COLUMBIA.

ATLANTIC OCEAN...
A 1018 MB SURFACE LOW IS OFF THE COAST OF GEORGIA NEAR 31N79W
WITH A STATIONARY FRONT EXTENDING TO THE E ALONG 31N TO 32N72W
WHERE IT CONTINUES AS A COLD FRONT NE OUT OF THE DISCUSSION
AREA. A SURFACE TROUGH EXTENDS AHEAD OF THE FRONT FROM 31N74W TO
LAKE OKEECHOBEE NEAR 27N81W. SURFACE CONVERGENCE NEAR THESE
FEATURES AS WELL AS UPPER LEVEL SUPPORT FROM AN UPPER LEVEL
TROUGH THAT EXTENDS DOWN THE ERN UNITED STATES COASTLINE ARE
GENERATING SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE FLORIDA
PENINSULA INTO THE WRN ATLC N OF 27N W OF 70W. A SECOND SURFACE
TROUGH PROPAGATING WWD EXTENDS FROM 27N63W TO 23N70W.  SURFACE
CONVERGENCE NEAR THE TROUGH IS SUPPORTING SCATTERED
SHOWERS/THUNDERSTORMS WITHIN 100 NM N OF THE TROUGH AXIS BETWEEN
60W-67W. A BROAD SURFACE RIDGE DOMINATES THE REMAINDER OF THE
ATLC ANCHORED BY A 1026 MB HIGH NEAR 30N51W...AND A 1024 MB HIGH
NEAR 31N38W. THESE ARE SUPPORTED BY A BROAD UPPER LEVEL RIDGE
CENTERED NEAR AN UPPER LEVEL HIGH NEAR 32N40W. A MID-LEVEL DRY
SAHARAN AIR LAYER REMAINS ACROSS THE ATLC SUPPRESSING DEEP
CONVECTION ALONG THE ITCZ.

$$
WALTON





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