[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121054
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...
A TROPICAL WAVE LOCATED OVER THE CENTRAL ATLANTIC ALONG 50W OR
ABOUT 650 NM EAST OF THE LESSER ANTILLES IS SUPPORTING AN AREA
OF ORGANIZED SCATTERED SHOWERS AND THUNDERSTORMS FROM 14N-20N
BETWEEN 46W-56W. A 1008 MB LOW IS EMBEDDED ON THE WAVE AXIS NEAR
14N. CONVECTIVE ACTIVITY HAS PERSISTED 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 1008 MB BROAD LOW PRESSURE AREA IS LOCATED OVER THE EASTERN
ATLANTIC NEAR 12N31W. SATELLITE IMAGERY SHOWS INDICATIONS OF
BETTER ORGANIZATION DURING THE PAST 12 HOURS. A LARGE AREA OF
SCATTERED SHOWERS AND THUNDERSTORMS ACCOMPANIES THIS LOW FROM
7N-16N BETWEEN 27W-36W 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 25W S OF 18N MOVING W NEAR 10-15 KT. BROAD CYCLONIC
TURNING IS SEEN ALONG THE WAVE AXIS NEAR 13N. SCATTERED MODERATE
CONVECTION IS OBSERVED MAINLY AHEAD OF THE WAVE FROM 13N-15N
BETWEEN 26W-31W.

A TROPICAL WAVE IS ALONG 74W/75W S OF 19N MOVING W 15-20 KT. A
WEAK INVERTED-V PATTERN IS SEEN ON SATELLITE IMAGERY. THE
MIMIC-TPW PRODUCT SHOWS A SMALL NORTHWARD MOISTURE SURGE ALONG
THE AXIS TO NEAR 15N. SCATTERED MODERATE CONVECTION IS FROM
12N-14N BETWEEN 74W-77W.

A TROPICAL WAVE EXTENDS FROM WRN CUBA TO ACROSS COSTA RICA ALONG
84W/85W MOVING W NEAR 15-20 KT. DEEP CONVECTION ASSOCIATED WITH
THIS WAVE IS PRIMARILY CONFINED TO AN AREA OVER THE E PACIFIC
REGION BUT SCATTERED SHOWERS REMAIN ACROSS THE SW CARIBBEAN S OF
15N AND W OF 78W. 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 REGENERATION OF
CONVECTIVE DEVELOPMENT OVER THIS REGION.

...THE ITCZ...
THE ITCZ IS CENTERED ALONG 16N16W 15N22W 10N34W 14N48W 13N53W
9N62W. OUTSIDE OF THE CONVECTION ASSOCIATED WITH THE TWO
TROPICAL WAVES AND THE LOW NEAR 12N31W...SCATTERED MODERATE
CONVECTION IS FROM 7N-10N BETWEEN 40W-43W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER-LEVEL HIGH CENTERED OVER N CENTRAL MEXICO EXTENDS
RIDGING OVER A MAJORITY OF THE GULF. MULTILAYERED CLOUDINESS IS
RIDING AROUND THIS RIDGE SEWD OFF THE SE CONUS AND GENERATING
SCATTERED SHOWERS ACROSS THE NRN GULF N OF 27N. OTHERWISE THE
GULF REMAINS RATHER TRANQUIL THIS MORNING WITH A SURFACE RIDGE
ANCHORED ON A 1017 MB HIGH OVER THE SE GULF NEAR 23N83W. THE
SURFACE CIRCULATION AROUND THIS HIGH IS PROVIDING THE GULF WITH
LIGHT TO MODERATE SOUTHERLY RETURN FLOW. THESE WINDS ARE
EXPECTED TO GRADUALLY INCREASE THROUGH WED AS A LOW PRESSURE
SYSTEM DEVELOPS OVER TEXAS AND SLOWLY SKIRTS ACROSS THE SERN U.S.

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 20N67W. THE REMAINDER OF THE CARIBBEAN IS UNDER
THE INFLUENCE OF AN UPPER LEVEL HIGH CENTERED OVER NRN COLOMBIA
NEAR 10N72W. UPPER DIFFLUENCE REMAINS ACROSS THE CARIBBEAN W OF
70W AND IS SUPPORTING AN AREA OF SCATTERED SHOWERS AND TSTMS
FROM 12N-15N BETWEEN 74W-77W. A SIMILAR AREA OF SHOWERS IS
WITHIN 120 NM OF THE WRN PANAMA...COSTA RICA AND NICARAGUA
COASTLINE IN THE SW CARIBBEAN. ABUNDANT MIDDLE TO UPPER LEVEL
CLOUDINESS AND MOISTURE IS NOTED OVER THE WRN CARIBBEAN S OF 18N
AND W OF 68W. 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 31N61W. 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
28N-32N BETWEEN 65W-73W. ANOTHER UPPER LOW IS CENTERED NORTH OF
PUERTO RICO NEAR 20N67W AND IS PRODUCING LITTLE SENSIBLE
WEATHER. ELSEWHERE AN UPPER LOW IS OVER THE CENTRAL ATLC NEAR
28N52W WITH ANOTHER UPPER-LEVEL LOW OVER THE ERN ATLC NEAR
29N33W. AN UPPER-LEVEL HIGH IS LOCATED NEAR 24N23W...AND A
STRONGER ONE IS CENTERED NEAR 19N43W WITH THE RIDGE COVERING THE
DEEP TROPICS. THESE UPPER SYSTEMS ARE ENHANCING CONVECTION
ASSOCIATED WITH THE TROPICAL WAVE ALONG 50W AND CONVECTIVE
ACTIVITY EMBEDDED WITHIN THE ITCZ. OTHERWISE...THE ATLANTIC
FORECAST AREA IS DOMINATED BY A 1023 MB SURFACE HIGH CENTERED
NEAR 35N40W. THIS HIGH EXTENDS A RIDGE SW TO THE TURKS AND
CAICOS ISLANDS AND INTO THE SE GULF. IT IS FORECAST TO REMAIN
STATIONARY DURING THE NEXT 24 HOURS OR SO.

$$
HUFFMAN


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