[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 141803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 14 2012

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...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC.

...SPECIAL FEATURES...
A SURFACE TROUGH IS IN THE CENTRAL ATLC ALONG 29N48W TO 22N51W.
IT ORIGINATED AS A BROKEN OFF PIECE OF A TROPICAL WAVE THAT IS
APPROACHING THE LESSER ANTILLES. CONVECTION NEAR THE TROUGH HAS
INCREASED FROM 24 HOURS AGO. CURRENTLY SCATTERED MODERATE
CONVECTION IS FROM 23N-28N BETWEEN 49W-54W. ENVIRONMENTAL
CONDITIONS ARE EXPECTED TO BECOME MORE CONDUCIVE FOR DEVELOPMENT
OVER THE NEXT COUPLE OF DAYS. THE TROUGH IS FORECAST TO MOVE NW
AROUND THE SURFACE RIDGE TO THE N.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 20N29W TO 9N29W MOVING W AT 20 KT. THE
WAVE LIES ON THE WEST SIDE OF A SURGE OF DEEP LAYER MOISTURE
PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. THERE IS ALSO A
CLEARING THE IN THE SAHARAN AIR LAYER AND AFRICAN DUST PRESENT
ACROSS MUCH OF THE EASTERN ATLC. THIS DRY AIRMASS SURROUNDING
THE WAVE IS LIMITING DEEP CONVECTION TO THE MONSOON TROUGH
REGION. SCATTERED MODERATE CONVECTION IS FROM 6N-8N BETWEEN
29W-36W. SIMILAR CONVECTION IS FROM 8N-10N BETWEEN 22W-28W.

TROPICAL WAVE EXTENDS FROM 16N52W TO 8N54W MOVING W NEAR 20 KT.
THE WAVE HAS LOST MOST OF ITS ENERGY TO THE SURFACE TROUGH TO
THE N...WHICH BROKE OFF OF THE WAVE. THE WAVE STILL ALIGNS WITH
A WEAK SURGE OF MODERATE DEEP LAYER MOISTURE PRESENT IN TOTAL
PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS CURRENTLY
ASSOCIATED WITH THE WAVE.

TROPICAL WAVE...REMNANTS OF T.D. SEVEN...IS MOVING W AT 15-20 KT
THROUGH THE WESTERN CARIBBEAN FROM 20N81W TO 10N81W. SATELLITE
IMAGERY ALONG WITH SURFACE OBSERVATIONS INDICATE SHARP CYCLONIC
SURFACE FLOW IS AROUND THE AXIS. THE WAVE ALSO LIES UNDERNEATH
AN AREA OF DIFFLUENCE ALOFT...WHICH IS HELPING PRODUCE
SHOWERS/THUNDERSTORMS NEAR THE WAVE. NUMEROUS MODERATE/SCATTERED
STRONG CONVECTION IS FROM 10N-15N BETWEEN 74W-79W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 10N-19N BETWEEN
79W-85W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
MAURITANIA AT 19N16W CONTINUING ACROSS ATLC WATERS ALONG 12N22W
8N30W 7N39W. THE ITCZ BEGINS AT 7N39W TO 8N52W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 10N-16N BETWEEN
15W-20W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE RIDGING COVERS THE MAJORITY OF THE GULF OF MEXICO
CENTERED AROUND A 1017 MB HIGH NEAR 27N86W. THE RIDGE IN
COMBINATION WITH DRY AIR ALOFT AROUND THE NORTHERN SIDE OF AN
UPPER LEVEL RIDGE CENTERED OVER CENTRAL MEXICO IS HELPING
PROVIDE FAIR CONDITIONS OVER MUCH OF THE AREA. AN AREA OF
SHOWERS/POSSIBLE THUNDERSTORMS IS OFF THE COAST OF MEXICO FROM
20N-24N BETWEEN 96W-98W. ANOTHER AREA OF STRONGER
SHOWERS/THUNDERSTORMS IS ALSO OVER THE FLORIDA PANHANDLE DUE TO
DIFFLUENCE ALOFT AROUND AN UPPER LEVEL TROUGH OVER THE EASTERN
CONUS. A FEW ISOLATED SHOWERS ARE ALSO EMBEDDED WITHIN THE LIGHT
ANTI-CYCLONIC FLOW AROUND THE SURFACE HIGH CENTER. EXPECT LITTLE
CHANGE OVER THE NEXT 24 HOURS. MOISTURE FROM A TROPICAL WAVE IN
THE WESTERN CARIBBEAN MAY BEGIN TO IMPACT THE SE GULF.

CARIBBEAN SEA...
A TROPICAL WAVE IN COMBINATION WITH DIFFLUENCE ALOFT AROUND AN
INVERTED UPPER TROUGH OVER CENTRAL AMERICA IS HELPING PRODUCE
SHOWERS/THUNDERSTORMS ACROSS MUCH OF THE WESTERN CARIBBEAN FROM
10N-19N BETWEEN 73W-84W. THE REMAINDER OF THE BASIN IS
EXPERIENCING MOSTLY FAIR WEATHER DUE TO DRY AIR ALOFT AROUND AN
UPPER LEVEL RIDGE IN THE CENTRAL CARIBBEAN. TRADEWIND FLOW OF
15-20 KT IS PRESENT ACROSS THE EASTERN AND CENTRAL CARIBBEAN.
EXPECT THE WAVE TO CONTINUE WESTWARD WITH LITTLE CHANGE
ELSEWHERE.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE COVERS THE W ATLC SUPPORTING A WEAK SURFACE
RIDGE. HOWEVER...AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS IS
SUPPORTING SHOWERS/THUNDERSTORMS N OF 27N BETWEEN 74W-79W. THE
UPPER TROUGH ALSO SUPPORTS A SURFACE TROUGH THAT ENTERS THE AREA
FROM 32N78W TO 30N79W. A NARROW UPPER TROUGH IS TO THE E ALONG
62W...BUT IS NOT CAUSING ANY SIGNIFICANT WEATHER. AN UPPER LEVEL
RIDGE COVERS THE CENTRAL ATLC CENTERED NEAR 33N48W SUPPORTING A
1025 MB HIGH NEAR 33N46W. A SURFACE TROUGH TO THE SOUTH IS
CAUSING AN AREA OF ACTIVE WEATHER. SEE SPECIAL FEATURES ABOVE
FOR MORE DETAILS ON THE TROUGH. AN UPPER LEVEL TROUGH COVERS THE
NE ATLC WITH A NARROW AXIS CONTINUING INTO THE DISCUSSION AREA
FROM THE CANARY ISLANDS TO NEAR 25N36W. THE TROUGH IS SUPPORTING
A COLD FRONT N OF THE DISCUSSION AREA...BUT NO SIGNIFICANT
WEATHER IN THE DISCUSSION AREA. VISIBLE SATELLITE IMAGERY
CONTINUES TO SHOW AN AREA OF DUST EXTENDS FROM THE COAST OF
AFRICA AROUND THE TROPICAL WAVE IN THE EASTERN TROPICAL ATLC.
THE DRY AIR MASS IS LIMITING CONVECTION NEAR THE WAVE.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALTON





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