[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191156
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN AUG 19 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURES...

HURRICANE GORDON IS LOCATED NEAR 35.1N 30.7W AT 19/1200 OR ABOUT
340 MI...550 KM WSW OF SAO MIGUEL ISLAND AZORES MOVING E AT 20
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 973 MB. MAXIMUM
SUSTAINED WIND SPEED IS 85 KT WITH GUSTS TO 105 KT. FIRST
SATELLITE VISIBLE PICTURES OF THE DAY REVEALED A SOMEWHAT LESS
DEFINED EYE. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS
FROM 33N-37N BETWEEN 28W-35W. GORDON IS EXPECTED TO PRODUCE
TOTAL RAINFALL AMOUNTS OF 3 TO 6 INCHES OVER THE AZORES. SEE
LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT3/WTNT33 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.

AN ACTIVE TROPICAL WAVE IS LOCATED IN THE ERN/CENTRAL TROPICAL
ATLC ALONG 34W...WITH AN ASSOCIATED 1009 MB LOW NEAR 14N35W
EMBEDDED WITHIN THE MONSOONAL GYRE. THIS SYSTEM IS MOVING
WESTWARD AROUND 20 KT. SCATTERED SHOWERS AND THUNDERSTORMS ARE
FROM 10N-18N BETWEEN 31W-38W...WITHIN THE BROAD CONVECTIVE
REGION ASSOCIATED TO THE MONSOON TROUGH. ENVIRONMENTAL CONDITIONS
APPEAR CONDUCIVE FOR A TROPICAL DEPRESSION TO FORM DURING THE
NEXT DAY OR TWO...AND THIS SYSTEM HAS A HIGH CHANCE OF BECOMING
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES WESTWARD
AT 20 KT.

...TROPICAL WAVES...

TROPICAL WAVE MOVES ACROSS THE CENTRAL TROPICAL ATLC WITH AXIS
EXTENDING FROM 17N44W TO A WEAK 1011 MB LOW NEAR 10N45W MOVING W
AT 15-20 KT. THE WAVE REMAINS EMBEDDED WITHIN A BROAD AREA OF
ENHANCED DEEP LAYER MOISTURE AS NOTED ON THE TOTAL PRECIPITABLE
WATER IMAGERY. CONVECTION AROUND THE WAVE AXIS IS LIMITED DUE TO
A LARGE DRY AIRMASS ASSOCIATED WITH THE SAHARAN AIR LAYER. ANY
SHOWER ACTIVITY IS LIKELY ASSOCIATED TO THE BROAD MONSOONAL GYRE
DISCUSSED BELOW.

TROPICAL WAVE MOVES ACROSS THE CENTRAL CARIBBEAN WITH AXIS
EXTENDING FROM ERN CUBA NEAR 20N76W TO BARANOA IN NRN COLOMBIA
NEAR 11N74W MOVING W AT 15-20 KT. THE CIRCULATION AROUND THE
AXIS HAS BROADENED COMPARED TO YESTERDAY...AND THE OVERALL
CONVECTIVE ACTIVITY HAS DECREASED ACCORDINGLY. ONLY A CLUSTER OF
SCATTERED SHOWERS AND THUNDERSTORMS IS NOTED OVER THE NRN
EXTENSION OF THE WAVE AXIS MOVING ACROSS THE SRN COASTAL WATERS
OF HAITI AND THE WINDWARD PASSAGE N OF 16N BETWEEN 71W-76W...
WHERE LOW LEVEL CONVERGENCE IS MAXIMIZED COINCIDING WITH A WEAK
UPPER LEVEL LOW PROVIDING FURTHER LIFTING.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST OF GUINEA
BISSAU NEAR 11N16W TO 15N24W. THEN...THE MONSOON TROUGH
REDEVELOPS W OF THE SPECIAL FEATURE 1009 LOW PRESSURE SYSTEM
NEAR 15N30W ALONG 10N40W TO A WEAKER 1011 MB LOW NEAR 10N45W TO
9N50W. THE ITCZ AXIS BEGINS FORM THIS POINT TO THE COAST OF
GUYANA NEAR 6N58W. A BROAD AREA CONTAINING CLUSTERS OF SCATTERED
MODERATE CONVECTION COVERS FROM 4N-16N BETWEEN 30W-50W. SIMILAR
CONVECTION IS WITHIN 120 NM N OF THE ITCZ AND FROM 8N-16N E OF
22W.

...DISCUSSION...

GULF OF MEXICO...
THE BASE OF A BROAD UPPER LEVEL TROUGH...MOVING ACROSS THE
CENTRAL AND ERN CONUS...SWINGS ACROSS THE NRN GULF OF MEXICO
PUSHING MULTIPLE SHORTWAVES ABOUT EVERY 6 HOURS. THIS IS
BRINGING SCATTERED SHOWERS AND THUNDERSTORMS OVER THE AREA N OF
27N. WHILE THE UPPER LEVEL TROUGH CONTINUES TO SLOWLY MOVE
ENE...THE FLOW AROUND THIS FEATURE WILL CONTINUE TO BRING
SEVERAL MORE WAVES OF ENERGY OVER THE NEXT 24 HOURS OVER THE NRN
AND NE BASIN. THUS EXPECT MORE SCATTERED CONVECTION IN THESE
REGIONS DURING THE FORECAST PERIOD. THE BROAD CYCLONIC WIND
FIELD RELATED TO FORMER TROPICAL STORM HELENE CONTINUES TO
GENERATE SCATTERED SHOWERS AND THUNDERSTORMS OVER THE WRN BAY OF
CAMPECHE AND COASTAL WATERS OF TAMPICO S OF 25N W OF 92W. WINDS
WILL REMAIN GENTLE TO MODERATE IN THIS REGION DURING THE NEXT 24
HOURS. LIGHT TO GENTLE SE SURFACE FLOW IS ACROSS THE REMAINDER
OF THE GULF UNDER STABLE CONDITIONS.

CARIBBEAN SEA...
INFRA-RED SATELLITE IMAGERY SHOWS A MID LEVEL MESO-CYCLONE OVER
THE SW CARIBBEAN CENTERED NEAR 12N82W. THIS COORDINATE DOES NOT
REPRESENT A SURFACE CIRCULATION AND IT IS NOT ANALYZED ON THE
0600 UTC SURFACE MAP...BUT RATHER IT IS A CENTER POSITION FOR
THE MID LEVEL FEATURE. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE WITHIN 160 NM FROM THE CENTER AT ALL
QUADRANTS. TO THE E OF THIS FEATURE...A TROPICAL WAVE IS
ANALYZED FROM ERN CUBA TO THE COAST OF COLOMBIA NEAR BARANOA.
THE CIRCULATION AROUND THE AXIS HAS BROADENED AND THE OVERALL
CONVECTIVE ACTIVITY HAS DECREASED ACCORDINGLY. ONLY A CLUSTER OF
SCATTERED SHOWERS AND THUNDERSTORMS IS NOTED OVER THE WINDWARD
PASSAGE AND SRN COASTAL WATERS OF HAITI...WHERE LOW LEVEL
CONVERGENCE IS MAXIMIZED COINCIDING WITH A WEAK UPPER LEVEL LOW
PROVIDING FURTHER LIFTING. SOME LOW-LEVEL MOISTURE IS NOW
ENTERING THE FAR SE BASIN S OF 14N E OF 64W INCLUDING THE ISLAND
OF TRINIDAD AND TOBAGO. THIS AREA OF SHOWERS WILL CONTINUE TO
SPREAD WEST ACROSS THE ERN CARIBBEAN TODAY. THE REMAINDER OF THE
CARIBBEAN IS DOMINATED BY DRY AIR AND SUBSIDENCE ALOFT NOTED ON
WATER VAPOR IMAGERY.

ATLANTIC OCEAN...
WATER VAPOR CONTINUES TO SHOW A BROAD LONGWAVE UPPER TROUGH
SLOWLY MOVING OFF THE ERN CONUS SEABOARD GENERATING WIDELY
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE WRN ATLC
DISCUSSION AREA N OF 25N BETWEEN 64W-78W. AN UPPER LEVEL LOW IS
TO THE E OF THIS CONVECTIVE AREA IS CENTERED NEAR 25N57W WITHOUT
ANY SIGNIFICANT IMPACTS. OTHERWISE...BROAD SURFACE RIDGING
DOMINATES THE REMAINDER OF THE CENTRAL AND EASTERN ATLC...
GUARDED BY A 1021 MB HIGH CENTERED NEAR 27N57W...AND A 1018 MB
HIGH AROUND 35N21W. THE FAIR WEATHER PRODUCED BY THESE SURFACE
FEATURES IS FURTHER ENHANCED ALOFT BY THE SAHARAN AIR LAYER AND
ASSOCIATED DUST ACROSS MOST OF THE DISCUSSION AREA E OF 65W. THE
HIGHEST CONCENTRATION OF SAHARAN DUST IS NOTED OVER THE FAR ERN
ATLC N OF 17N E OF 34W.

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

$$

GARCIA




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