[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 231118
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI APR 23 2010

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1015 UTC...

...THE ITCZ...

ITCZ AXIS IS CENTERED FROM NRN LIBERIA NEAR 7N11W ALONG 5N20W
3N30W 1N40W AND INTO NE BRAZIL TO 1N52W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 2N-6N BETWEEN
12W-19W. SIMILAR ACTIVITY IS FROM 2N-4N BETWEEN 30W-36W...FROM
2N-5N BETWEEN 38W-45W...AND FROM 3N-5N BETWEEN 48W-51W.

...DISCUSSION...

THE GULF OF MEXICO...
SURFACE RIDGING COVERS THE ERN GULF OF MEXICO TONIGHT EXTENDING
FROM A 1015 MB HIGH E OF NRN FLORIDA MAINTAINING GENERALLY FAIR
WEATHER ACROSS MUCH OF THE BASIN. HOWEVER...POSSIBLE ISOLATED
SHOWERS ARE IN THE FAR NW CARIBBEAN N OF 26N W OF 91W. THE
SURFACE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE WITH AXIS
EXTENDING FROM THE OHIO VALLEY TO THE CENTRAL GULF. UPPER LEVEL
MOISTURE BEING DRAWN FROM THE E PACIFIC AROUND THIS UPPER RIDGE
COVERS THE GULF SUPPORTING HIGH CLOUDS MOSTLY ACROSS THE WRN
HALF OF THE AREA. SURFACE OBSERVATIONS INDICATE MAINLY SE FLOW
OF 15-20 KT COVERING MOST OF THE BASIN WITH STRONGER WINDS IN
THE NW GULF. AN UPPER LEVEL TROUGH OVER THE WRN CONUS IS
FORECAST TO MOVE EWD SUPPORTING A COLD FRONT FORECAST TO MOVE
OFF THE TEXAS COAST LATE FRI.

THE CARIBBEAN SEA...
MUCH OF THE CARIBBEAN IS EXPERIENCING GENERALLY FAIR WEATHER
UNDER THE INFLUENCE OF MODERATELY DRY AIR ALOFT IN UPPER LEVEL
ZONAL WLY FLOW. A CLUSTER OF SHOWERS/THUNDERSTORMS ARE NOTED OFF
THE COAST OF COSTA RICA FROM 11N-12N BETWEEN 80W-83W. ISOLATED
SHOWERS ARE ALSO ACROSS THE NE CARIBBEAN ISLANDS INCLUDING
PUERTO RICO AND HISPANIOLA. THIS ACTIVITY IS MOST LIKELY
ASSOCIATED WITH SURFACE CONVERGENCE NEAR A FRONTAL TROUGH
REACHING THE VIRGIN ISLANDS EXTENDING FROM A COLD FRONT IN THE
CENTRAL ATLC. ISOLATED SHOWERS ARE N OF 17N BETWEEN 64W-71W.
TOTAL PRECIPITABLE WATER IMAGERY ALSO INDICATES ENHANCED
LOW-LEVEL MOISTURE OVER THE ERN CARIBBEAN. MODERATE TO FRESH
TRADEWINDS ARE ACROSS MUCH OF THE BASIN...AND ARE FORECAST TO
INCREASE AS HIGH PRESSURE BUILDS ACROSS THE W ATLC RESULTING IN
A STRONGER PRESSURE GRADIENT ACROSS THE CARIBBEAN.

THE ATLANTIC OCEAN...
THE SURFACE RIDGE OVER THE ERN GULF HAS BEGUN TO SHIFT EWD...AND
IS NOW ANCHORED BY A 1015 MB HIGH NEAR 29N78W KEEPING CONDITIONS
FAR ACROSS THE FAR W ATLC. A BROAD UPPER LEVEL TROUGH COVERS THE
REMAINDER OF THE W ATLC SUPPORTING A LOW PRESSURE SYSTEM N OF
THE AREA OFF THE NEW ENGLAND COAST. AN ASSOCIATED COLD FRONT
ENTERS THE DISCUSSION AREA NEAR 32N62W TO 27N69W. SCATTERED
SHOWERS ARE E OF THE FRONT FROM 26N-31N BETWEEN 60W-66W. A
SURFACE TROUGH IS E OF THE FRONT FROM 26N57W TO 31N60W MEETING A
WARM FRONT THAT EXTENDS OUT OF THE AREA. SCATTERED SHOWERS ARE E
OF THE TROUGH/FRONT N OF 29N BETWEEN 53W-57W. A SURFACE RIDGE
COVERS THE REMAINDER OF THE CENTRAL AND E ATLC ANCHORED BY A
1016 MB HIGH NEAR 30N43W...AND A 1017 MB HIGH NEAR 25N28W.
HOWEVER...A COLD FRONT BISECT THE SURFACE RIDGE BETWEEN THE HIGH
CENTERS ENTERING THE DISCUSSION AREA NEAR 32N29W ALONG 27N36W
23N49W CONTINUING AS A SURFACE TROUGH TO THE VIRGIN ISLANDS
ALONG 22N57W 19N64W. SCATTERED SHOWERS ARE N OF 25N BETWEEN
27W-53W. ISOLATED SHOWERS ARE FROM 20N-23N BETWEEN 48W-54W...AND
ALSO WITHIN 45NM EITHER SIDE OF THE TROUGH AXIS. THE SURFACE
RIDGE IS MAINTAINING GENERALLY FAIR WEATHER SE OF THE FRONTAL
BOUNDARY. AN UPPER LEVEL RIDGE CENTERED NEAR 12N42W DOMINATES
THE E ATLC SUPPORTING THE SURFACE RIDGE.

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

$$
WALTON








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