[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 201749
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUL 20 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 28W S OF 13N MOVING W NEAR 15 KT.
EXAMINING THE UPPER AIR TIME SECTION ANALYSIS FROM DAKAR
SENEGAL...IT APPEARS A LOW-LEVEL...700-850 MB...CYCLONIC
CIRCULATION PASSED THROUGH DAKAR BEFORE 19/1200 UTC. WHILE THIS
WAVE REMAINS EMBEDDED WITHIN THE ITCZ...SCATTERED MODERATE
CONVECTION IS LOCATED WELL W OF THE WAVE AXIS FROM 4N-9N BETWEEN
31W-37W.

A TROPICAL WAVE IS ALONG 46W S OF 18N MOVING W NEAR 18 KT. THIS
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. WHILE ON THE LEADING EDGE OF A
DRY SAHARAN AIR TO THE EAST...DUST IS OBSERVED ON METEOSAT-9
VISIBLE IMAGERY E OF 45W. DUE TO THE PRESENCE OF THIS DRY AIR
AND A CENTRAL ATLC SURFACE RIDGE HOLDING STRONG N OF 18N...NO
SIGNIFICANT DEEP CONVECTION IS OCCURRING WITH THE WAVE.

A TROPICAL WAVE IS ALONG 58W S OF 19N MOVING W NEAR 22 KT. THIS
WAVE COINCIDES WITH A LOW TO MIDDLE LEVEL CYCLONIC TURNING IN
SATELLITE CLOUD DRIFT WINDS AS WELL AS CYCLONIC TURNING
DEPICTED ON AN EARLIER SCATTEROMETER PASS AROUND 20/1000 UTC.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 11N-16N
BETWEEN 55W-61W.

A HIGH AMPLITUDE TROPICAL WAVE EXTENDS FROM THE NW BAHAMAS NEAR
27N77W THROUGH ERN CUBA AND CENTRAL JAMAICA TO NWRN COLOMBIA
NEAR 8N76W MOVING W NEAR 20 KT. THIS WAVE COINCIDES WITH A LARGE
AREA OF MAXIMUM TOTAL PRECIPITABLE WATER ACROSS THE WRN
CARIBBEAN AND PORTIONS OF THE SW NORTH ATLC. WITH A SHARP UPPER
TROUGH LOCATED ACROSS THE NE GULF AND FLORIDA PENINSULA...THIS
WAVE IS EXPECTED TO FRACTURE A SURFACE TROUGH TRACKING N-NW
THROUGH WEDNESDAY WHILE THE REMAINING SRN PORTION OF THE WAVE
CONTINUES WWD TOWARDS CENTRAL AMERICA. SCATTERED MODERATE
CONVECTION IS HOWEVER LIMITED TO AN AREA S OF JAMAICA FROM
14N-17N BETWEEN 75W-79W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 14N17W 9N27W 7N31W 5N45W 5N48W
8N58W. SCATTERED MODERATE CONVECTION IS FROM 11N-16N BETWEEN
17W-22W. A CLUSTER OF SCATTERED MODERATE CONVECTION IS FROM
4N-9N BETWEEN 31W-37W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT EXTENDS ACROSS NE FLORIDA CONTINUING WWD AS A
STATIONARY FRONT ALONG 29N TO NEAR NEW ORLEANS LOUISIANA. A
PRE-FRONTAL TROUGH EXTENDS FROM JACKSONVILLE TO TAMPA FLORIDA
AND INTO THE E GULF NEAR 26N84W. THESE FRONTS ARE ASSOCIATED AND
SUPPORTED BY A SHARP UPPER LEVEL TROUGH THAT COVERS THE NE GULF
AND FLORIDA PENINSULA DIPPING TO 24N. AS OBSERVED ON DOPPLER
RADAR AND LIGHTNING DATA...SCATTERED SHOWERS AND TSTMS ARE
OCCURRING E OF THE SURFACE TROUGH ACROSS THE FLORIDA PENINSULA
EXTENDING INTO THE E GULF WITHIN 90 NM OF THE SURFACE TROUGH.
THE REMAINDER OF THE GULF IS UNDER A SURFACE RIDGE WITH AXIS
ALONG A NEW ORLEANS TO VERACRUZ MEXICO LINE AND ANCHORED BY A
1018 MB HIGH CENTERED NEAR 26N91W THAT IS RESULTING IN GENERALLY
FAIR WEATHER W OF 90W...INCLUDING THE YUCATAN PENINSULA.

CARIBBEAN SEA...
A TROPICAL WAVE IS MOVING ACROSS THE WRN CARIBBEAN OVER ERN CUBA
THROUGH CENTRAL JAMAICA TO NWRN COLOMBIA NEAR 8N76W. SCATTERED
SHOWERS AND ISOLATED TSTMS ON DIFFLUENT FLOW ALOFT ARE OCCURRING
FROM 14N-17N BETWEEN 75W-79W. THE UPPER LEVEL DIFFLUENCE IS
FOCUSED ON AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR
11N75W IN THE SW CARIBBEAN AND IS GENERATING SCATTERED SHOWERS
AND TSTMS S OF A LINE FROM 11N75W TO THE ERN COAST OF NICARAGUA
NEAR 14N83W. THIS ACTIVITY EXTENDS ACROSS THE SRN PORTION OF
CENTRAL AMERICA INTO THE E PACIFIC. THE AFOREMENTIONED UPPER
LEVEL RIDGE EXTENDS TO THE WINDWARD ISLANDS ALONG 13N. ON THE
NRN PERIPHERY OF THIS RIDGE...SCATTERED SHOWERS AND ISOLATED
TSTMS ARE ACROSS HISPANIOLA...PUERTO RICO AND THE ERN CARIBBEAN
E OF 71W. AS THE TROPICAL WAVE ALONG 58W IMPACTS THE LESSER
ANTILLES...EXPECT INCREASED CLOUDINESS AND SCATTERED SHOWERS/
TSTMS THROUGH THE NEXT 24-36 HOURS.

ATLANTIC OCEAN...
A UPPER LEVEL TROUGH IS ACROSS THE SE CONUS AND EXTENDS UPPER
LEVEL TROUGHING ACROSS THE FLORIDA PENINSULA EWD INTO THE SW
NORTH ATLC. MOIST SWLY DIFFLUENT FLOW ALOFT IS GENERATING
SCATTERED SHOWERS AND TSTMS ACROSS THE SRN FLORIDA PENINSULA.
THIS UPPER LEVEL TROUGHING EXTENDS E TO AN UPPER LEVEL SHORTWAVE
TROUGH CENTERED NEAR 26N75W. NUMEROUS SHOWERS AND SCATTERED
TSTMS ARE FROM 20N-29N BETWEEN 65W-75W. THE REMAINDER OF THE
CENTRAL AND ERN ATLC IS DOMINATED BY A BROAD SURFACE RIDGE
ANCHORED BY A 1028 MB HIGH CENTERED NEAR 35N56W AND A 1027 MB
HIGH CENTERED NEAR 34N41W THAT IS RESULTING IN GENERALLY FAIR
WEATHER N OF 20N E OF 63W ACROSS THE SUBTROPICAL ATLC.

$$
HUFFMAN





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