[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 221207
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON AUG 22 2011

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 IRENE IS NEAR 18.8N 66.8W AT 1200 UTC AUG 22 OR ABOUT
55 MI...90 KM WNW OF SAN JUAN PUERTO RICO...OR ABOUT 105
MI...165 KM E OF PUNTA CANA DOMINICAN REPUBLIC MOVING WNW AT 13
KT. MINIMUM CENTRAL PRESSURE IS 987 MB. MAXIMUM SUSTAINED WIND
SPEED IS 65 KT WITH GUSTS 80 KT. PLEASE SEE THE LATEST
INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT4/
WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO
HEADER MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. SCATTERED STRONG
CONVECTION IS OVER PUERTO RICO AND SURROUNDING WATERS FROM
17N-23N BETWEEN 62W-68W. IRENE IS EXPECTED TO PRODUCE TOTAL
RAINFALL ACCUMULATIONS OF 5 TO 10 INCHES ACROSS PUERTO
RICO...THE VIRGIN ISLANDS...THE DOMINICAN REPUBLIC...HAITI...THE
SOUTHEASTERN BAHAMAS AND THE TURKS AND CAICOS ISLANDS.  ISOLATED
MAXIMUM AMOUNTS OF UP TO 20 INCHES ARE POSSIBLE. THESE RAINS
COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES IN
AREAS OF STEEP TERRAIN.

TROPICAL DEPRESSION HARVEY IS INLAND OVER MEXICO NEAR 18.4N
96.0W AT 0500 UTC AUG 22 OR ABOUT 90 KM SSE OF VERACRUZ MEXICO.
HARVEY IS MOVING WNW AT 10 KT. MINIMUM CENTRAL PRESSURE IS 1005
MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT GUSTS 40 KT. PLEASE
SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO
HEADER MIATCPAT3/WTNT33 KNHC AND THE FULL FORECAST/ADVISORY
UNDER AWIPS/WMO HEADER MIATCMAT3/ WTNT23 KNHC FOR MORE DETAILS.
ALTHOUGH MOST OF THE CONVECTION IS INLAND...SCATTERED MODERATE
TO STRONG CONVECTION LINGERS OVER THE BAY OF CAMPECHE S OF 23N W
OF 92W. HARVEY IS EXPECTED TO PRODUCE ADDITIONAL RAINFALL
ACCUMULATIONS OF 2 TO 4 INCHES OVER PORTIONS OF THE MEXICAN
STATES OF VERACRUZ...OAXACA...HIDALGO ...PUEBLA...AND
TIAXCALA...WITH ISOLATED MAXIMUM STORM TOTAL AMOUNTS OF 10
INCHES. THESE RAINS COULD PRODUCE LIFE-THREATENING FLASH FLOODS
AND MUD SLIDES...ESPECIALLY IN AREAS OF STEEP TERRAIN. THE
DEPRESSION IS FORECAST TO DISSIPATE BY MONDAY NIGHT.

...THE ITCZ/THE MONSOON TROUGH...

A 1010 MB LOW IS NEAR 20N31W. THIS LOW MOVING NW OVER COOLER
WATERS. AS THE SYSTEM TRACKS NW IT WILL BUILD A TIGHT PRESSURE
GRADIENT BETWEEN THE BROAD SURFACE RIDGE AND THE SURFACE LOW
THAT COULD GENERATE GUSTY WINDS TO NEAR GALE FORCE CRITERIA
DURING THE FORECAST PERIOD. THIS SYSTEM HAS ALSO CAUSED THE
MONSOON TROUGH OVER THE ATLC WATERS TO WEAKEN AND BECOME
DIFFUSE. AS THE BROAD CYCLONIC WIND FIELD ASSOCIATED TO
HURRICANE IRENE CONTINUES TO MOVE WNW...THE CONVERGENCE OF NE
AND SE TRADE WINDS SLOWLY REBUILDS BEHIND...THUS THE ITCZ CAN BE
DEPICTED FROM 11N42W TO 11N50W. THE MONSOON TROUGH IS ANALYZED
INLAND OVER WEST AFRICA ENTERING THE ATLC NEAR 18N16W TO THE
CAPE VERDE ISLANDS NEAR 16N23W. SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS WITHIN 120 NM S OF THE ITCZ. SIMILAR
CONVECTION IS MOVING OFF THE AFRICAN COAST OF
GUINEA...GUINEA-BISSAU...THE GAMBIA...AND SENEGAL FROM 8N-15N E
OF 20W ASSOCIATED TO A SURFACE LOW INLAND OVER SENEGAL NEAR
15N14W. THIS LOW WILL BE CLOSELY MONITORED FOR FUTURE
DEVELOPMENT AS IT MOVES OFFSHORE OVERNIGHT MON NIGHT.

...DISCUSSION...

GULF OF MEXICO...
TROPICAL DEPRESSION HARVEY IS INLAND OVER MEXICO. ALTHOUGH MOST
OF THE CONVECTION IS INLAND...SCATTERED MODERATE TO STRONG
CONVECTION LINGERS OVER THE BAY OF CAMPECHE S OF 23N W OF 92W.
FOR MORE INFORMATION SEE SPECIAL FEATURES ABOVE. ELSEWHERE
ACROSS THE DISCUSSION AREA...UPPER LEVEL EASTERLY FLOW COVERS
THE GULF...ON THE SOUTH SIDE OF THE BROAD UPPER OMEGA RIDGE
SETTLED ACROSS THE CONUS. WEAK SURFACE RIDGING DOMINATES THE
GULF THIS MORNING...WITH WIDELY SCATTERED WEAK SHOWERS EMBEDDED
IN THE EASTERLY FLOW INCLUDING ACROSS THE STRAITS OF FLORIDA.

CARIBBEAN SEA...
THE PRIMARY CONCERN THIS MORNING IS HURRICANE IRENE MOVING OFF
THE NORTHERN COAST OF PUERTO RICO. FOR MORE INFORMATION SEE
SPECIAL FEATURES ABOVE. OTHERWISE...WIDELY SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS REMAIN OVER THE SW BASIN S OF 15N W OF
75W DUE TO THE MONSOON TROUGH EXTENDING INLAND ACROSS COSTA RICA
TO NORTHERN COLOMBIA. THE REMAINDER OF THE CARIBBEAN IS UNDER
MOSTLY CLEAR SKIES WITH A FEW ISOLATED SHOWERS EMBEDDED IN THE
5-15 KT EASTERLY TRADE WIND FLOW. TROPICAL STORM CONDITIONS ARE
EXPECTED TO DIMINISH IN THE CARIBBEAN LATE TODAY AS IRENE TRACKS
WNW THROUGH THE NORTHERN PORTION OF HISPANIOLA AND INTO THE SW
NORTH ATLANTIC.

ATLANTIC OCEAN...
THE PRIMARY CONCERN THIS MORNING IS HURRICANE IRENE MOVING OFF
THE NORTHERN COAST OF PUERTO RICO. SYMMETRIC CONVECTIVE OUTFLOW
FROM IRENE IS NOTICED ON SATELLITE INFRA RED IMAGERY EXTENDING
INTO THE ATLANTIC TO NEAR 500 NM NE OF THE CENTER. SEE SPECIAL
FEATURES ABOVE FOR MORE INFORMATION ON IRENE. OTHERWISE...THE
REMAINDER OF THE ATLC BASIN IS DOMINATED BY A BROAD SURFACE
RIDGE ANCHORED BY A 1026 MB HIGH W OF THE AZORES NEAR
37N33W...LEAVING THE REMAINDER OF THE DISCUSSION AREA UNDER FAIR
CONDITIONS THIS MORNING. SOUTH OF THE RIDGE LIES A LOW PRES
CENTER NEAR 20N31W. THIS LOW IS EMBEDDED IN DRY AIR AND AFRICAN
DUST THAT IS INHIBITING DEEP CONVECTION. THIS LOW IS FORECAST TO
MOVE NW OVER COOLER WATERS TO THE CENTRAL ATLANTIC OVER THE NEXT
SEVERAL DAYS. AS THE SYSTEM TRACKS NW IT WILL BUILD A TIGHT
PRESSURE GRADIENT BETWEEN THE BROAD SURFACE RIDGE AND THE
SURFACE LOW THAT COULD GENERATE GUSTY WINDS TO NEAR GALE FORCE
CRITERIA DURING THE FORECAST PERIOD.

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

$$

GARCIA




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