[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT AUG 11 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
2335 UTC.

...TROPICAL WAVES...

TROPICAL WAVE MOVES ACROSS THE ERN ATLANTIC EXTENDING FROM
24N28W TO 17N29W MOVING W-NW AT 10-15 KT. A WEAK 1012 MB LOW IS
EMBEDDED IN THE WAVE AXIS NEAR 20N29W. THIS SYSTEM IS EMBEDDED
IN A AREA OF LOW-MID LEVEL MOISTURE NOTED ON TOTAL PRECIPITABLE
WATER IMAGERY. THE CLOUD PATTERN ON SATELLITE IMAGERY INDICATED
BROAD LOW-LEVEL CYCLONIC FLOW AROUND THE WAVE. HOWEVER...ANY
RELATED CONVECTION REMAINS SUPPRESSED DUE TO DRY SAHARAN AIR
AROUND THE SYSTEM.

ACTIVE TROPICAL WAVE...REMNANTS OF T.D. SEVEN...MOVES ACROSS THE
LESSER ANTILLES EXTENDING FROM 17N58W TO 10N61W MOVING W NEAR 18
KT. WAVE IS EMBEDDED IN A REGION OF DEEP MOISTURE NOTED ON TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE TO HEAVY SHOWERS
AND THUNDERSTORMS ARE FROM 11N-17N BETWEEN 57W-64W. HEAVY RAINS
AND GUSTY WINDS ARE EXPECTED TO CONTINUE ACROSS PORTIONS OF THE
LESSER ANTILLES THROUGH SUNDAY.

WEAK TROPICAL WAVE MOVES ACROSS THE WRN BAY OF CAMPECHE WITH
AXIS ANALYZED FROM 23N95W TO 18N95W. THE WAVE HAS LOST MOST OF
ITS CHARACTERISTICS AND IT IS ONLY PRODUCING A FEW ISOLATED
SHOWERS NEAR THE COAST OF VERACRUZ AND COATZACOALCOS. EXPECT THE
WAVE TO MOVE WESTWARD AND INLAND INTO MEXICO WHERE IT WILL
DISSIPATE IN ABOUT 24 HOURS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH BEGINS S OF THE ERN ATLC TROPICAL WAVE NEAR
16N30W ALONG 11N36W TO 12N44W. NO ITCZ IS NOTED ACROSS THE
TROPICAL ATLC. NO SIGNIFICANT CONVECTION IS NOTED AT THIS TIME.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY SHOWS A VIGOROUS UPPER LEVEL LONGWAVE/TROUGH
AXIS EXTENDING SSW ACROSS THE ERN CONUS TO ACROSS THE WRN GULF
BASIN. THIS FEATURE SUPPORTS A NEARLY STATIONARY SURFACE TROUGH
EXTENDING ACROSS THE N CENTRAL WATERS FROM 30N86W TO 29N93W.
DOPPLER RADAR IMAGERY INDICATES SCATTERED SHOWERS AND
THUNDERSTORMS WITHIN 70 NM ON EITHER SIDE OF THE TROUGH AXIS.
THIS AREA OF SHOWERS IS FORECAST TO DRIFT ENE DURING THE NEXT 24
HOURS AS THE UPPER FEATURE MOVES OFF THE ERN CONUS. ALSO...AN
UPPER LEVEL LOW IS NOTED OVER THE NW CARIBBEAN MOVING N INTO THE
ERN GULF GENERATING SIMILAR CONVECTION S OF 26N E OF 89W...WITH
THE STRONGEST ACTIVITY NOTED OVER THE STRAITS OF FLORIDA. THE
OVERALL ACTIVITY IN THIS REGION WILL SPREAD NNW AS THE UPPER LOW
CONTINUES ITS NORTHWARD TRAJECTORY OVER THE NEXT 24 HOURS. A
WEAK TROPICAL WAVE OVER THE WRN BAY OF CAMPECHE IS GENERATING
ISOLATED SHOWERS NEAR THE COAST OF VERACRUZ AND COATZACOALCOS.
EXPECT THE WAVE TO MOVE WESTWARD AND INLAND INTO MEXICO WHERE IT
WILL DISSIPATE IN ABOUT 24 HOURS. OTHERWISE...THE REMAINDER OF
THE GULF IS UNDER WEAK SURFACE RIDGING AND MOSTLY CLEAR SKIES
WITH A A FEW ISOLATED SHOWERS DOTTING THE AREA.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IS CENTERED OVER THE NW CARIBBEAN NEAR
20N85W. MID-UPPER LEVEL MOISTURE CONVERGENCE AROUND THE BROAD
CYCLONIC FLOW ALOFT IS GENERATING SCATTERED SHOWERS AND
THUNDERSTORMS N OF 14N W OF 80W. SIMILAR ACTIVITY IS OVER THE SW
CARIBBEAN S OF 14N W OF 80W ASSOCIATED WITH THE MONSOON TROUGH
THAT EXTENDS THROUGH COSTA RICA TO NORTHERN COLOMBIA. THIS AREA
OF CONVECTION IS EXPECTED TO MOVE NNW TO THE SE GULF OF MEXICO
DURING THE NEXT 24 HOURS AS THE UPPER LOW CONTINUES ITS
TRAJECTORY NORTHWARD ACROSS THE ERN GULF. AN ACTIVE TROPICAL
WAVE...REMNANTS OF T.D. SEVEN...IS MOVING ACROSS THE LESSER
ANTILLES WITH SCATTERED MODERATE TO HEAVY SHOWERS AND
THUNDERSTORMS E OF 64W S OF 17N. THIS AREA OF CONVECTION WILL
SPREAD ACROSS THE ERN CARIBBEAN OVER THE NEXT 24 HOURS.
OTHERWISE...WATER VAPOR IMAGERY INDICATES DRY AIR ALOFT ACROSS
THE CENTRAL CARIBBEAN PRODUCING MOSTLY CLEAR SKIES AND FAIR
CONDITIONS BETWEEN 64W-80W. TRADEWIND FLOW OF 15-20 KT IS
PRESENT ACROSS MUCH OF THE EASTERN AND CENTRAL CARIBBEAN.

ATLANTIC OCEAN...
AN UPPER LEVEL LOW OVER THE NW CARIBBEAN AND AN UPPER LEVEL
LONGWAVE/TROUGH EXTENDING ACROSS THE ERN CONUS ARE PRODUCING SSW
FLOW ALOFT ACROSS MUCH OF THE WRN ATLC BASIN W OF 72W. THIS FLOW
IS DRAWING MID-UPPER LEVEL MOISTURE ACROSS THIS FAIRLY UNSTABLE
AREA...GENERATING SCATTERED SHOWERS AND THUNDERSTORMS W OF A
LINE FROM 30N70W TO 22N78W. A WEAK SURFACE TROUGH IS JUST EAST
OF THIS AREA OF CONVECTION ALSO PROVIDING FOR SIMILAR ACTIVITY
WITHIN 60 NM ON EITHER SIDE OF ITS AXIS FROM 28N71W TO 27N74W.
AN ELONGATED UPPER LEVEL LOW IS CENTERED NEAR 25N54W PRODUCING
ISOLATED SHOWERS FROM 23N-31N BETWEEN 50W-62W. OTHERWISE...A
BROAD SURFACE RIDGE AXIS ENCOMPASSES MOST OF THE EASTERN AND
CENTRAL ATLC AND REMAINS ANCHORED BY A 1025 MB HIGH CENTERED S
OF THE AZORES NEAR 35N28W. THE FAIR WEATHER CONDITIONS ARE
FURTHER ENHANCED BY A THICK LAYER OF SAHARAN DUST NOTED ACROSS
THE AREA E OF 50W ON METEOSAT-9...WITH THE HIGHEST VALUES NOTED
E OF 30W.

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

$$

GARCIA




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