[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112357
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED APR 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
2300 UTC.

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

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
LIBERIA AT 6N11W TO THE EQUATOR AND 23W. THE ITCZ CONTINUES FROM
EQ23W TO 1S28W CONTINUING BACK NWD TO THE EQUATOR AT 38W...AND
BACK S AGAIN TO THE COAST OF BRAZIL AT 3S45W. SCATTERED
MODERATE/STRONG CONVECTION IS OFF THE COAST OF AFRICA FROM 2S-7N
BETWEEN 11W-20W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 1N-3N BETWEEN 29W-33W.

...DISCUSSION...

THE GULF OF MEXICO...
MOSTLY DRY AIR IN W-NW FLOW ALOFT COVERS THE GULF OF MEXICO THIS
EVENING AROUND THE E SIDE OF AN UPPER LEVEL RIDGE COVERING THE
CENTRAL CONUS ALONG 99W...AND THE W SIDE OF A BROAD UPPER LEVEL
TROUGH COVERING THE ERN CONUS AND W ATLC ALONG 81W. THE UPPER
RIDGE SUPPORTS A WEAK SURFACE RIDGE ACROSS THE NRN GULF AROUND A
1021 MB HIGH S OF LOUISIANA AT 28N91W. LIGHT ANTI-CYCLONIC FLOW
IS AROUND THE HIGH CENTER WITH STRONGER RETURN FLOW ALONG THE
TEXAS COAST. SKIES ARE MOSTLY CLEAR WITH A FEW WIDELY ISOLATED
LOW-LEVEL CLOUDS OVER THE SE GULF AND FAR SW GULF WITH POSSIBLE
ISOLATED SHOWERS. AN AREA OF SCATTERED SHOWERS/THUNDERSTORMS IS
ALSO OVER SRN LOUISIANA ASSOCIATED WITH A STATIONARY FRONT THAT
DRAPES ACROSS TEXAS TO LOUISIANA. EXPECT THE WEAK SURFACE HIGH
OVER THE NRN GULF TO DISSIPATE OVER THE NEXT 24 HOURS AS A
SURFACE HIGH TO THE N BUILDS S PROVIDING RIDGING ACROSS THE
AREA. RETURN FLOW ALONG THE WRN IS ALSO EXPECTED TO INCREASE TO
20-25 KTS BY THE END OF THE WEEK AND THROUGH THE WEEKEND.

THE CARIBBEAN SEA...
DRY AIR ALOFT IN ZONAL WLY FLOW IS PROVIDING FAIR CONDITIONS
ACROSS MUCH OF THE CARIBBEAN WATERS. HOWEVER...A SURFACE TROUGH
EXTENDS ACROSS THE CENTRAL CARIBBEAN FROM S OF ERN CUBA AT
19N76W ACROSS JAMAICA TO 13N79W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE MAINLY N OF THE AXIS ACROSS ERN CUBA WITH MORE
ISOLATED ACTIVITY OVER JAMAICA AND W OF JAMAICA FROM 18N-19N
BETWEEN 79W-83W. A SECOND SURFACE TROUGH TO THE N OF HISPANIOLA
IS ALSO BRINGING SHOWERS/THUNDERSTORMS TO THE ISLAND. ISOLATED
SHOWERS/POSSIBLE THUNDERSTORMS ARE ALSO MOVING THROUGH THE
LESSER ANTILLES ASSOCIATED WITH AN AREA OF LOW-LEVEL MOISTURE
ADVECTING WWD FROM THE TROPICAL ATLC. BESIDES NEAR THE SURFACE
TROUGH...THE REMAINDER OF THE AREA IS UNDER TRADEWIND FLOW OF
10-15 KTS WITH MOSTLY CLEAR SKIES. EXPECT THE SURFACE TROUGH TO
REMAIN SOMEWHAT STATIONARY AND GRADUALLY DISSIPATE WITH THE
TROUGH N OF HISPANIOLA ALSO REMAINING STATIONARY BEFORE BEING
SWEPT UP BY A FRONTAL BOUNDARY OVER THE W ATLC. ENHANCED
LOW-LEVEL MOISTURE WILL ALSO REMAIN OVER THE NRN CARIBBEAN
INCREASING THE CHANCE FOR CONTINUED RAINFALL ACROSS THE NRN
ISLANDS.

THE ATLANTIC OCEAN...
A LONGWAVE UPPER TROUGH COVERS THE ERN CONUS AND W ATLC ALONG
81W SUPPORTING A COLD FRONT THAT HAS DIPPED S INTO THE AREA
ALONG 32N73W TO THE COAST OF FLORIDA AT 28N81W TO 28N83W...AS OF
2100 UTC. A LINE OF SHOWERS/THUNDERSTORMS IS E OF THE FRONT AXIS
FROM 28N75W TO 32N70W CONTINUING N OF THE AREA. A SURFACE TROUGH
IS N OF HISPANIOLA ALONG 20N71W TO 27N69W SUPPORTING SCATTERED
SHOWERS/THUNDERSTORMS OVER HISPANIOLA WITH SIMILAR ACTIVITY N OF
THE AXIS FROM 27N-31N BETWEEN 64W-69W. AN AREA OF SCATTERED
SHOWERS/POSSIBLE THUNDERSTORMS IS ALSO E OF THE AXIS FROM
22N-28N BETWEEN 60W-69W. SOME OF THIS ACTIVITY IS ALSO
INFLUENCED BY A SECOND FRONTAL BOUNDARY TO THE E. A STATIONARY
FRONT ENTERS THE DISCUSSION AREA AT 32N53W TO 28N57W WHERE IT
CONTINUES AS A DISSIPATING WARM FRONT TO 26N62W. THE SURFACE
TROUGH IS EXPECTED TO REMAIN STATIONARY BEFORE BEING SWEPT UP BY
THE COLD FRONT TO THE W. A BROAD UPPER RIDGE COVERS MUCH OF THE
CENTRAL AND ERN ATLC WITH AXIS EXTENDING FROM E OF THE LESSER
ANTILLES TO W OF THE AZORES ISLANDS NEAR 47N33W. THE UPPER RIDGE
IS SUPPORTING SURFACE RIDGING AROUND A 1031 MB HIGH NEAR
38N37W...WHICH IS PROVIDING FAIR WEATHER ACROSS MUCH OF THE ERN
ATLC. A NARROW UPPER LEVEL TROUGH COVERS THE FAR ERN ATLC WITH
AXIS FROM PORTUGAL TO THE CANARY ISLANDS TO THE CAPE VERDE
ISLANDS. THE UPPER TROUGH IS SUPPORTING SEVERAL SURFACE LOWS
OVER LAND INCLUDING OVER NW AFRICA...SPAIN AND N OF SPAIN.

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

$$
WALTON





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