[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122348
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN AUG 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 11N18W TO 20N17W MOVING W AT 15-20
KT. THE WAVE EMERGED OFF THE COAST OF W AFRICA AFTER 12/1200 UTC
EARLIER THIS MORNING AND COINCIDES WITH A 700 MB LOW NEAR THE
SOUTHERN EXTENT OF THE WAVE AXIS NEAR 10N17W. THE 700 MB
TROUGHING EXTENDS NORTHWARD ALONG 18N TO 21N. ALSO...TOTAL
PRECIPITABLE WATER IMAGERY INDICATES DEEP LAYERED MOISTURE IS
LOCATED FROM 06N-17N E OF 22W. WIDELY SCATTERED MODERATE
CONVECTION IS FROM 07N-13N BETWEEN 12W-22W.

TROPICAL WAVE EXTENDS FROM 17N38W TO 25N36W MOVING WNW AT 15-20
KT. A 1013 MB LOW IS CENTERED ALONG THE WAVE AXIS NEAR 21N37W
AND COINCIDES WITH AN AREA OF MAXIMUM DEEP LAYERED MOISTURE
NOTED IN TOTAL PRECIPITABLE WATER IMAGERY FROM 18N-24N BETWEEN
35W-42W. HOWEVER...DRY AIR AND DUST SURROUND THE WAVE LIMITING
DEEP CONVECTION AT THIS TIME. ISOLATED SHOWERS ARE POSSIBLE FROM
20N-24N BETWEEN 37W-42W.

TROPICAL WAVE EXTENDS FROM 12N69W TO 18N67W MOVING W AT 20 KT.
THE REMNANTS OF T.D. SEVEN...SATELLITE PRESENTATION AND
ASSOCIATED SURFACE OBSERVATIONS INDICATE SHARP CYCLONIC FLOW IN
THE VICINITY OF THE AXIS. THIS WAS CONFIRMED EARLIER BY A
12/1438 UTC ASCAT PASS IN THE WATERS SOUTH OF PUERTO RICO ALONG
67W. SCATTERED MODERATE CONVECTION IS FROM 13N-19N BETWEEN
65W-71W...AND IS LIKELY ENHANCED DUE TO MIDDLE TO UPPER LEVEL
DIFFLUENCE MAXIMIZED OVER THE EASTERN CARIBBEAN SEA.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 11N19W TO
11N36W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
11N36W TO 10N49W TO 08N59W. NO SIGNIFICANT CONVECTION IS NOTED
AT THIS TIME.

...DISCUSSION...

GULF OF MEXICO...
SOUTHERLY FLOW ALOFT DOMINATES OVER MUCH OF THE GULF BASIN THIS
EVENING BETWEEN AN UPPER LEVEL LOW CENTERED OVER NE MEXICO NEAR
24N99W AND AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER
THE NW BAHAMAS NEAR 25N78W. THIS SYNOPTIC SETUP CONTINUES TO
ADVECT MOISTURE FROM SOUTHERN MEXICO AND THE YUCATAN PENINSULA
ACROSS THE EASTERN GULF AND FLORIDA PENINSULA. DIFFLUENCE IS
MAXIMIZED OVER THIS AREA AND CURRENTLY IS GENERATING SCATTERED
SHOWERS AND TSTMS OVER THE FLORIDA PENINSULA AND ADJACENT
COASTAL WATERS N OF 25N E OF 84W...AND OVER NORTHERN GUATEMALA
AND THE YUCATAN PENINSULA...INCLUDING ADJACENT GULF COAST
OFFSHORE WATERS. ELSEWHERE...ISOLATED SHOWERS AND TSTMS ARE
OCCURRING E OF 90W AND ACROSS THE SW GULF S OF 24N W OF 90W.
THIS ACTIVITY IS LARGELY OVERRIDING THE FACT THAT A WEAK SURFACE
RIDGE AXIS EXTENDS FROM THE SW NORTH ATLC ALONG 27N TO THE NW
GULF NEAR 27N97W. HELPING TO WEAKEN THIS RIDGE SLIGHTLY IS AN
UPPER LEVEL TROUGH AXIS MOVING OFF THE EASTERN SEABOARD THAT
SUPPORTS A STATIONARY FRONT FROM SOUTH CAROLINA NEAR 33N82W TO
THE FLORIDA PANHANDLE NEAR 30N85W TO SOUTHERN MISSISSIPPI NEAR
31N90W.

CARIBBEAN SEA...
MUCH OF THE CARIBBEAN SEA IS UNDER THE INFLUENCE OF UPPER LEVEL
TROUGHING WITH AXIS EXTENDING ALONG 76W. ALOFT W OF 76W...
NORTHEASTERLY FLOW DOMINATES AND IS PROVIDING AN OVERALL STABLE
ENVIRONMENT AND CLEAR SKIES THIS EVENING. THE DRY AIR NOTED ON
WATER VAPOR IMAGERY IS EXPECTED TO CONTINUE SPREADING WESTWARD
THROUGH LATE MONDAY INTO TUESDAY ACROSS THE WESTERN CARIBBEAN. E
OF 76W...SOUTHERLY FLOW ALOFT IS ADVECTING MOISTURE INTO THE
TROPICAL WAVE ALONG 68W. AS MENTIONED ABOVE...SCATTERED SHOWERS
AND TSTMS ARE OCCURRING OVER MUCH OF THE EASTERN CARIBBEAN N OF
13N IN ASSOCIATION WITH THE TROPICAL WAVE...BUT DUE TO UPPER
LEVEL DIFFLUENCE AND THE BASE OF UPPER LEVEL TROUGHING N OF 18N
BETWEEN 55W-66W...SCATTERED SHOWERS AND ISOLATED TSTMS CONTINUE
ACROSS THE LEEWARD ISLANDS...PUERTO RICO...AND THE US/UK VIRGIN
ISLANDS THIS EVENING.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS BEGINNING TO EMERGE OFF THE EASTERN
SEABOARD THIS EVENING AND SUPPORTS A WEAK AREA OF SURFACE
TROUGHING IN THE FORM OF A STATIONARY FRONT DRAPED FROM THE NEW
ENGLAND STATES SOUTHWARD TO THE FLORIDA PANHANDLE. MOSTLY UPPER
LEVEL DIFFLUENCE BETWEEN THIS TROUGH AXIS AND AN UPPER LEVEL
ANTICYCLONIC CIRCULATION CENTERED NEAR 25N78W IS GENERATING
SCATTERED SHOWERS AND TSTMS OVER MUCH OF THE FLORIDA PENINSULA
AND ADJACENT COASTAL ATLC WATERS FROM 26N-31N W OF 78W.
ELSEWHERE OVER THE REMAINDER OF THE SW NORTH ATLC...ISOLATED
SHOWERS AND TSTMS ARE OCCURRING N OF 23N W OF 68W. WHILE A
SURFACE RIDGE AXIS EXTENDS FROM BERMUDA NEAR 32N65W TO 27N80W
AND INTO THE GULF OF MEXICO...IT REMAINS RATHER WEAK AND
INFLUENTIAL ACROSS THE SW NORTH ATLC THIS EVENING DUE TO MAXIMUM
INSTABILITY. E OF 65W HOWEVER...THE REMAINDER OF THE CENTRAL AND
EASTERN ATLC FALL UNDER THE INFLUENCE OF A BROAD SURFACE RIDGE
ANCHORED BY A 1025 MB HIGH CENTERED NEAR 33N37W WHERE PRIMARILY
STABLE CONDITIONS AND FAIR WEATHER ARE OCCURRING. THE ONLY
WEAKNESS FOUND WORKING TO ERODE THE RIDGING IS THE TROPICAL WAVE
ALONG 37N MENTIONED ABOVE.

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

$$
HUFFMAN



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