[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 120557
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE AUG 12 2008

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.

...SPECIAL FEATURES...
A TROPICAL WAVE LOCATED OVER THE CENTRAL ATLANTIC ALONG 49W/50W
OR ABOUT 650 NM EAST OF THE LESSER ANTILLES IS SUPPORTING AN
AREA OF ORGANIZED SCATTERED SHOWERS AND THUNDERSTORMS FROM
14N-19N BETWEEN 46W-53W. A 1007 MB LOW IS EMBEDDED ON THE WAVE
AXIS NEAR 13N. CONVECTIVE ACTIVITY HAS BEEN COME BETTER
ORGANIZED OVER THE PAST 6-12 HOURS AND ENVIRONMENTAL CONDITIONS
APPEAR FAVORABLE FOR GRADUAL DEVELOPMENT OF THE SYSTEM WHICH HAS
THE POTENTIAL TO BECOME A TROPICAL DEPRESSION DURING THE NEXT
COUPLE OF DAYS AS IT MOVES WEST-NORTHWESTWARD AT 15 KT.

A 1009 MB BROAD LOW PRESSURE AREA IS LOCATED OVER THE EASTERN
ATLANTIC NEAR 12N30W. SATELLITE IMAGERY SHOWS INDICATIONS OF
BETTER ORGANIZATION DURING THE PAST 12 HOURS. A LARGE AREA OF
SCATTERED SHOWERS AND THUNDERSTORMS ACCOMPANIES THIS LOW FROM
8N-15N BETWEEN 26W-34W WHICH REMAINS EMBEDDED WITHIN THE ITCZ.
A TROPICAL DEPRESSION COULD FORM WITHIN THIS AREA DURING THE
NEXT DAY OR TWO AS IT MOVES WESTWARD AT ABOUT 10 KT.

...TROPICAL WAVES...
A TROPICAL WAVE IS ACROSS THE CAPE VERDE ISLANDS. ITS AXIS IS
ALONG 24W S OF 18N MOVING W NEAR 10 KT. BROAD CYCLONIC TURNING
IS SEEN ALONG THE WAVE AXIS NEAR 13N. SCATTERED MODERATE
CONVECTION IS OBSERVED MAINLY AHEAD OF THE WAVE FROM 12N-16N
BETWEEN 25W-29W.

A TROPICAL WAVE IS ALONG 73W S OF 19N MOVING W 15-20 KT. A WEAK
INVERTED-V PATTERN IS SEEN ON SATELLITE IMAGERY. THE MIMIC-TPW
SHOWS THAT MOISTURE ASSOCIATED WITH THIS FEATURE HAS SPLIT IN
TWO PIECES. ONE REMAINS OVER THE CARIBBEAN SEA SOUTH OF
HISPANIOLA WHILE THE SECOND ONE IS MOVING NWD OVER THE W ATLC.
SCATTERED MODERATE CONVECTION IS FROM 9N-14N BETWEEN 72W-75W. A
SURGE OF AFRICAN DUST CONTINUES TO FOLLOWS THIS WAVE AS SEEN
FROM THE SAHARAN AIR LAYER PRODUCT FROM CIMSS.

A TROPICAL WAVE EXTENDS FROM WRN CUBA TO PANAMA ALONG 83W MOVING
W NEAR 15-20 KT. DEEP CONVECTION ASSOCIATED WITH THIS WAVE HAS
WANED OVER THE PAST 6 HOURS WITH ONLY SCATTERED SHOWERS COVERING
THE SW CARIBBEAN S OF 15N W OF 77W. MOISTURE WILL CONTINUE TO
SPREAD OVER CENTRAL AMERICA THROUGH WED INCREASING THE CHANCE OF
PRECIPITATION PARTICULARLY IN NICARAGUA...HONDURAS AND COSTA
RICA. A DIFFLUENT PATTERN ALOFT IS CONTINUING TO PROMOTE
CONVECTIVE DEVELOPMENT OVER THIS REGION.

...THE ITCZ...
THE ITCZ IS CENTERED ALONG 15N17W 13N23W 12N27W 11N32W 13N42W
13N48W 12N51W 6N58W. OUTSIDE OF THE CONVECTION ASSOCIATED WITH
THE TWO TROPICAL WAVES AND THE LOW NEAR 12N30W...SCATTERED
MODERATE CONVECTION IS FROM 6N-8N BETWEEN 34W-40W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER-LEVEL HIGH CENTERED OVER NE MEXICO EXTENDS RIDGING OVER
A MAJORITY OF THE GULF. MULTILAYERED CLOUDINESS IS RIDING AROUND
THIS RIDGE SEWD OFF THE SE CONUS AND RESIDES ACROSS THE NRN GULF
N OF 26N. THE GULF REMAINS RATHER TRANQUIL TONIGHT WITH A
SURFACE RIDGE ANCHORED ON A 1016 MB HIGH OVER THE SE GULF NEAR
25N86W. THE SURFACE CIRCULATION AROUND THIS HIGH IS PROVIDING
THE WRN AND CENTRAL GULF WITH LIGHT TO MODERATE SOUTHERLY RETURN
FLOW. THESE WINDS ARE EXPECTED TO GRADUALLY INCREASE THROUGH WED
AND PERSIST AS A LOW PRESSURE SYSTEM DEVELOPS OVER TEXAS AND NE
MEXICO AND SKIRTS EWD ALONG THE N GULF COAST.

CARIBBEAN SEA...
UPPER LEVEL TROUGHING EXTENDS FROM THE W ATLC THROUGH THE
BAHAMAS AND ERN CUBA TO AN UPPER LEVEL LOW LOCATED NORTH OF
PUERTO RICO NEAR 19N67W. THE REMAINDER OF THE CARIBBEAN IS UNDER
THE INFLUENCE OF AN UPPER LEVEL HIGH CENTERED OVER NRN COLOMBIA
NEAR 12N72W. UPPER DIFFLUENCE REMAINS ACROSS THE CARIBBEAN W OF
70W AND IS SUPPORTING AN AREA OF SCATTERED SHOWERS WITH EMBEDDED
TSTMS FROM 8N-15N BETWEEN 71W-76W. A SIMILAR AREA OF SHOWERS IS
WITHIN 120 NM OF THE WRN PANAMA AND COSTA RICA COASTLINE IN THE
SW CARIBBEAN. ABUNDANT MIDDLE TO UPPER LEVEL CLOUDINESS AND
MOISTURE IS NOTED OVER THE WRN CARIBBEAN S OF 19N AND W OF
70W. MODERATE TO STRONG SUBSIDENCE AND DRY AIR IS OVER THE ERN
CARIBBEAN WITH PATCHES OF SHALLOW MOISTURE CROSSING THE WINDWARD
ISLANDS. LIGHT TO MODERATE EASTERLY TRADE WINDS ARE OBSERVED
ACROSS THE BASIN WITH THE STRONGEST WINDS OFFSHORE OF THE NRN
COLOMBIAN COAST. TWO TROPICAL WAVES ARE MOVING WWD ACROSS WRN
PORTIONS OF THE BASIN...SEE TROPICAL WAVE SECTION FOR MORE
DETAILS.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS LOCATED OFF THE ERN U.S. SEABOARD AND
REACHES INTO THE W ATLC. AN UPPER-LEVEL RIDGE IS TO THE SE
CENTERED NEAR 30N64W. UPPER DIFFLUENCE BETWEEN THIS HIGH AND THE
UPPER TROUGH IS PRODUCING A 250 NM WIDE BAND OF SHOWERS AND
TSTMS FROM THE NW BAHAMAS TO BEYOND 32N70W. THIS ACTIVITY IS
ALSO ASSOCIATED WITH THE REMNANTS OF A FRONTAL BOUNDARY. MOST
CONCENTRATED AREA OF SCATTERED MODERATE CONVECTION IS FROM
27N-32N BETWEEN 64W-73W. ANOTHER UPPER LOW IS CENTERED NORTH OF
PUERTO RICO NEAR 19N67W AND IS PRODUCING LITTLE SENSIBLE
WEATHER. ELSEWHERE AN UPPER LOW IS OVER THE CENTRAL ATLC NEAR
28N52W WITH ANOTHER WEAK UPPER-LEVEL LOW OVER THE ERN ATLC NEAR
29N32W. AN UPPER-LEVEL HIGH IS LOCATED NEAR 22N25W...AND A
STRONGER ONE IS CENTERED NEAR 18N43W WITH THE RIDGE COVERING THE
DEEP TROPICS. THESE UPPER SYSTEMS ARE ENHANCING CONVECTION ALONG
THE ITCZ. OTHERWISE...THE ATLANTIC FORECAST AREA IS DOMINATED BY
A 1024 MB SURFACE HIGH CENTERED NEAR 35N48W. THIS HIGH EXTENDS A
RIDGE SW TO CUBA AND THE SE GULF AND IS FORECAST TO MOVE NEWD
DURING THE NEXT 24 HOURS OR SO.

$$
HUFFMAN




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