[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 280551
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE JUL 28 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 20W S OF 20N MOVING W NEAR 20 KT. THIS
WAVE COINCIDES WITH A BROAD MAXIMUM IN DEEP LAYER MOISTURE BASED
ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. W OF THE
WAVE AXIS A 1010 MB SURFACE LOW...LIKELY THE NORTHERN VORTICITY
MAXIMUM ASSOCIATED WITH THE TROPICAL WAVE...IS CENTERED N OF THE
CAPE VERDE ISLANDS NEAR 18N24W. WHILE THE SURFACE LOW ASSOCIATED
WITH THE WAVE LACKS ANY SIGNIFICANT DEEP CONVECTION DUE TO THE
PRESENCE OF SAHARAN DUST...SCATTERED SHOWERS ARE WITHIN 300 NM
EITHER SIDE OF THE WAVE AXIS.

A TROPICAL WAVE IS ALONG 47W S OF 16N MOVING W NEAR 18 KT. THIS
WAVE COINCIDES WITH A BROAD MAXIMUM IN DEEP LAYER MOISTURE BASED
ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. ALSO...AN
EARLIER SCATTEROMETER PASS AROUND 27/2100 UTC DEPICTED CYCLONIC
CURVATURE IN THE LOW-LEVELS NEAR THE WAVE AXIS. SCATTERED
SHOWERS ARE FROM 9N-15N BETWEEN 42W-50W.

A TROPICAL WAVE IS ALONG 72W S OF 20N MOVING W NEAR 25 KT. THIS
WAVE COINCIDES WITH A WELL-DEFINED MAXIMUM IN DEEP LAYER
MOISTURE ACROSS THE CENTRAL CARIBBEAN BASED ON THE TPW IMAGERY
FROM CIMSS. SATELLITE IMAGERY INDICATES AN INVERTED-V PATTERN IN
THE COVERAGE OF LOW LEVEL CLOUDS NEAR THIS WAVE. DRY AND STABLE
ATMOSPHERIC CONDITIONS ASSOCIATED WITH AN UPPER LEVEL RIDGE ARE
INHIBITING DEEP CONVECTION NEAR THIS WAVE. HOWEVER...SCATTERED
SHOWERS ARE FROM 15N-19N BETWEEN 64W-70W...INCLUDING THE MONA
PASSAGE...PUERTO RICO AND NEARBY ADJACENT COASTAL WATERS.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N16W 10N45W 10N49W 9N60W.
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM OF A LINE FROM
12N22W TO 7N40W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH IS OVER THE ERN GULF WITH AN AXIS
EXTENDING ACROSS THE BIG BEND REGION OF FLORIDA TO 24N90W AND
CONTINUING WWD TO AN UPPER LEVEL LOW NEAR 23N95W. ATMOSPHERIC
LIFT IN MOIST SWLY FLOW ALOFT AND ATMOSPHERIC INSTABILITY TO THE
E OF THE UPPER LEVEL TROUGH AXIS ARE SUPPORTING ISOLATED SHOWERS
OVER THE SE GULF S OF 26N E OF 90W. ADDITIONALLY...THE UPPER
LEVEL LOW ACROSS THE SW GULF IS GENERATING SCATTERED SHOWERS S
OF 26N BETWEEN 90W-97W. ACROSS THE NRN GULF WATERS...UPPER LEVEL
MOISTURE STREAMING SOUTHWARD W OF THE UPPER LEVEL TROUGH IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE
N/CENTRAL GULF N OF 28N BETWEEN 86W-92W. SELY WINDS ARE FORECAST
TO INCREASE OVER THE W GULF BY TUESDAY...AS A SURFACE RIDGE
ACROSS THE N GULF MOVES NWD DURING THE NEXT FEW DAYS AND SURFACE
LOW PRESSURE DEVELOPS OVER W TEXAS.

CARIBBEAN SEA...
AN UPPER LEVEL HIGH OVER THE NW CARIBBEAN IS CENTERED NEAR
21N84W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THIS UPPER LEVEL
RIDGE IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS FROM
20N-22N BETWEEN 78W-85W. ACROSS THE SW CARIBBEAN...UPPER LEVEL
RIDGING EXTENDS FROM THE E PACIFIC REGION AND IS LIMITING
ISOLATED SHOWERS AND TSTMS S OF 9N ACROSS NW COLOMBIA AND FAR
ERN PANAMA. ACROSS MUCH OF THE CENTRAL AND E CARIBBEAN...DEEP
LAYER DRY IS SUPPORTING GENERALLY FAIR WEATHER. HOWEVER...
CONVERGENT LOW-LEVEL ELY WINDS E OF THE TROPICAL WAVE ALONG 72W
AND UPPER LEVEL DIFFLUENCE ASSOCIATED TO THE SW OF AN UPPER
LEVEL RIDGE OVER THE CENTRAL ATLC IS SUPPORTING SCATTERED
SHOWERS FROM 15N-19N BETWEEN 64W-70W ACROSS THE NE CARIBBEAN AND
PORTIONS OF PUERTO RICO AND ADJACENT COASTAL WATERS. FRESH TO
STRONG TRADE WINDS ARE OCCURRING ACROSS THE E AND CENTRAL
CARIBBEAN S OF A SURFACE RIDGE OVER THE CENTRAL ATLC. THE
STRONGEST WINDS ARE FOUND NEAR THE COAST OF COLOMBIA...WHERE E
WINDS OF 25 TO 30 KT ARE OCCURRING.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS PRESENT OVER THE ERN U.S. AND ALONG
THE ERN SEABOARD EXTENDING ACROSS NRN FLORIDA AND THE NE GULF OF
MEXICO. ATMOSPHERIC LIFT IN MOIST SWLY FLOW ALOFT BETWEEN THIS
UPPER LEVEL TROUGH AND AN UPPER LEVEL RIDGE FARTHER TO THE E
OVER THE SW NORTH ATLC IS SUPPORTING SCATTERED SHOWERS AND
ISOLATED TSTMS N OF 23N BETWEEN 73W-79W INCLUDING PORTIONS OF
THE NW BAHAMAS. TO THE E...AN UPPER LEVEL LOW IS CENTERED NEAR
31N56W. ATMOSPHERIC INSTABILITY IN THE VICINITY OF THIS UPPER
LEVEL LOW...AND UPPER LEVEL DIFFLUENCE LOCATED E OF THE
LOW...ARE SUPPORTING ISOLATED SHOWERS FROM 28N-32N BETWEEN
51W-58W. THE REMAINDER OF THE CENTRAL AND ERN ATLC ARE DOMINATED
BY A SURFACE RIDGE ANCHORED ON A 1028 MB HIGH CENTERED NEAR
34N55W THAT IS PROVIDING GENERALLY FAIR WEATHER N OF 20N E OF
73W.

$$
HUFFMAN





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