[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071755
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE JUL 07 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 EXTENDS FROM 15N37W TO 5N40W MOVING W AT 15-20
KT. A LOW-LEVEL INVERTED-V CLOUD SIGNATURE IS OBSERVED ON
VISIBLE SATELLITE IMAGERY AS WELL AS SAHARAN DUST E OF THE AXIS
TO THE W AFRICA COAST. THIS WAVE ALSO COINCIDES WITH AN AREA OF
DEEP LAYER MOISTURE AS SEEN ON THE TOTAL PRECIPITABLE WATER
IMAGERY. WITH A SAHARAN AIR LAYER SURROUNDING THE WAVE...ONLY
SCATTERED SHOWERS ARE OCCURRING FROM 8N-13N BETWEEN 37W-42W.

A TROPICAL WAVE EXTENDS FROM CENTRAL CUBA NEAR 21N79W ALONG
14N81W TO 4N82W MOVING W AT 20-25 KT. THIS WAVE COINCIDES WITH A
SIGNIFICANT AREA OF INCREASED PRECIPITABLE WATER ACROSS THE WRN
CARIBBEAN AND CENTRAL AMERICA. INTERACTING WITH A DIFFLUENT
ATMOSPHERE ALOFT...SCATTERED MODERATE CONVECTION IS FOUND ACROSS
THE WRN CARIBBEAN AND PORTIONS OF NICARAGUA AND HONDURAS FROM
12N-19N BETWEEN 79W-87W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 9N13W 6N24W 9N37W 10N42W 8N60W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-10N
BETWEEN 14W-20W. SCATTERED MODERATE CONVECTION IS FROM 3N-7N
BETWEEN 25W-34W.

...DISCUSSION...

GULF OF MEXICO...
MOSTLY S TO SW SURFACE WIND ARE OBSERVED ACROSS THE GULF OF
MEXICO AS A RIDGE OF HIGH PRESSURE EXTENDS FROM THE W ATLC
THROUGH THE STRAITS OF FLORIDA AND WRN CUBA TO THE COAST OF NE
MEXICO. AN EARLIER SCATTEROMETER PASS DEPICTED WINDS UP TO 15 KT
ACROSS THE GULF THAT ARE PRIMARILY CONVERGING ALONG THE NRN GULF
COAST. THIS CONVERGENCE ALONG WITH A STATIONARY FRONT POSITIONED
ACROSS THE SE CONUS IS GENERATING SCATTERED SHOWERS AND TSTMS N
OF 17N. UPPER LEVEL RIDGING ALOFT ACROSS THE NRN GULF IS ALSO
HELPING TO ENHANCE THIS ACTIVITY. ELSEWHERE ACROSS THE REMAINDER
OF THE GULF S OF 17N...MOSTLY CLEAR SKIES ARE NOTED ON SATELLITE
IMAGERY AS SURFACE RIDGING AND MODERATE SUBSIDENCE ALOFT PREVAIL.

CARIBBEAN SEA...
A TROPICAL WAVE IS TRACKING WWD ACROSS THE WRN CARIBBEAN AND
CONTINUES TO IMPACT THE NW WATERS AND CENTRAL AMERICA. THE WAVE
CONTINUES TO MOVE BENEATH AN UPPER LEVEL ANTICYCLONE CENTERED
NEAR 13N84W AND THE INTERACTION BETWEEN THESE TWO FEATURES IS
GENERATING SCATTERED SHOWERS AND TSTMS FROM 12N-19N BETWEEN
79W-87W...INCLUDING PORTIONS OF NICARAGUA AND HONDURAS. ALSO
SCATTERED SHOWERS AND TSTMS ARE ACROSS PANAMA AND THE NEARBY
ADJACENT COASTAL WATERS S OF 10N DUE TO THE PROXIMITY OF THE E
PACIFIC ITCZ. THE REMAINDER OF THE CARIBBEAN IS UNDER THE
INFLUENCE OF A SAHARAN AIR LAYER OF DUST SUSPENDED IN THE MIDDLE
LEVELS OF THE ATMOSPHERE. THE SAL IS OBSERVED ON VISIBLE
SATELLITE IMAGERY AND NUMEROUS OF THE UPPER AIR TIME SECTION
ANALYSES ACROSS THE ERN CARIBBEAN. WITH THIS DRIER AIR IN
PLACE...ONLY A FEW ISOLATED LOW-LEVEL SHOWERS ARE NOTED ACROSS
THE WINDWARD ISLANDS. FRESH TO STRONG ELY TRADE WIND FLOW
CONTINUES ACROSS THE BASIN AND IS FORECAST TO PERSIST THROUGH
THE END OF THE WEEK.

ATLANTIC OCEAN...
SCATTERED SHOWERS AND TSTMS ARE ACROSS THE SW NORTH ATLC N OF
28N W OF 65W. THIS ACTIVITY IS FUELED BY LOW-LEVEL CONVERGENCE
ALONG AND S OF A STATIONARY FRONT N OF THE DISCUSSION AREA ALONG
36N70W INTO A 1006 SURFACE LOW NEAR 34N75W AND INLAND ACROSS THE
SE CONUS. THIS ACTIVITY IS FURTHER ENHANCED BY UPPER LEVEL
DIFFLUENCE BETWEEN AN UPPER LEVEL RIDGE OVER THE NRN GULF OF
MEXICO AND BROAD UPPER LEVEL TROUGHING OVER THE ERN CONUS. A
1022 MB SURFACE HIGH IS OVER THE CENTRAL ATLC NEAR 29N48W AND
EXTENDS A RIDGE ACROSS THE REMAINDER OF THE SW NORTH ATLC...
INCLUDING THE BAHAMAS...PROVIDING GENERALLY FAIR WEATHER.
HOWEVER...A WEAKNESS IN THE SURFACE HIGH AND RIDGE IS ANALYZED
AS A 1018 MB SURFACE LOW CENTERED NEAR 25N43W. A SURFACE TROUGH
EXTENDS SW FROM THE LOW ALONG 21N47W 18N55W. POSSIBLE ISOLATED
SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE TROUGH. FARTHER TO
THE NE...A 1011 MB SURFACE LOW IS CENTERED N OF THE AREA NEAR
36N26W AND EXTENDS A SURFACE TROUGH ALONG 32N24W 28N27W 26N35W.
SCATTERED SHOWERS ARE WITHIN 90 NM E OF THE TROUGH. BOTH OF
THESE SURFACE TROUGH AND ASSOCIATED LOW PRESSURE CENTERS ARE
ASSOCIATED WITH AN UPPER LEVEL TROUGH ACROSS THE NE ATLC N OF
22N E OF 37W.

$$
HUFFMAN



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