[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 210546 CCA
TWDAT

TROPICAL WEATHER DISCUSSION...COR
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED APR 21 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0540 UTC...

...THE ITCZ...

THE ITCZ IS ANALYZED FROM THE COAST OF SIERRA LEONE NEAR
7N13W...WESTWARD ALONG 5N20W 1N30W CONTINUING ALONG THE EQUATOR
LINE TO 52W. WIDELY SCATTERED MODERATE TO STRONG CONVECTION IS
WITHIN 150 NM ON EITHER SIDE OF THE AXIS WEST OF 30W. ISOLATED
PATCHES OF MODERATE TO STRONG CONVECTION ARE WITHIN 80 NM ON
EITHER SIDE OF THE AXIS EAST OF 30W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL SHORTWAVE IS OVER THE EASTERN GULF...AND IT WILL
BE CROSSING THE FLORIDA PENINSULA OVER THE NEXT 6 TO 12 HOURS.
STRONG LIFTING AHEAD OF THIS FEATURE IS SUPPORTING A SURFACE
TROUGH ANALYZED OVER THE STATE OF FLORIDA ALONG 30N82W 27N82W
24N83W. THE CONVECTION ASSOCIATED WITH THIS TROUGH IS BETTER
DEPICTED FROM DOPPLER RADAR IMAGERY INDICATING MODERATE TO HEAVY
SHOWERS AND POSSIBLE THUNDERSTORMS FROM 23N TO 32N BETWEEN 80W
AND 85W. THIS AREA OF CONVECTION IS EXPECTED TO MOVE OUT OF THE
AREA OF DISCUSSION BY WEDNESDAY LATE MORNING. HOWEVER...EXPECT
INSTABILITY IN THIS REGION WITH SHOWERS LINGERING THROUGH
WEDNESDAY LATE AFTERNOON. BEHIND THIS TROUGH...ANOTHER SURFACE
TROUGH ENTERS THE DISCUSSION AREA THROUGH THE WESTERN FLORIDA
PANHANDLE NEAR 31N85W CONTINUING WEST-SOUTHWEST ALONG 29N87W
28N91W...JUST 30 NM SOUTH OF MORGAN CITY LOUISIANA. SCATTERED
WEAK TO MODERATE SHOWERS ARE WITHIN 50 NM ON EITHER SIDE OF THE
TROUGH. A STABLE AIRMASS DOMINATES ELSEWHERE ACROSS THE REGION.
COMPUTER MODELS INDICATED AN UPPER LEVEL RIDGE OF HIGH PRESSURE
BUILDING ACROSS THE REGION FOR THE REST OF THE WORK WEEK.

THE CARIBBEAN SEA...
WATER VAPOR IMAGERY SHOWS A BROAD AREA OF MID LEVEL MOISTURE
MOVING NORTHEAST ACROSS THE CENTRAL AND EASTERN CARIBBEAN EAST
OF 80W. BEHIND THIS AREA OF MID LEVEL MOISTURE LIES AN UPPER
LEVEL SHORTWAVE THAT SUPPORTS A RATHER WEAK SURFACE TROUGH THAT
EXTENDS SOUTHWEST FROM SOUTH CENTRAL HAITI EXTENDING TO NEAR
12N77W. SCATTERED ISOLATED WEAK SHOWERS ARE WITHIN 30 NM ON
EITHER SIDE OF THE TROUGH...BUT RATHER AFFECTING THE ISLAND OF
HISPANIOLA DUE TO TOPOGRAPHIC EFFECT. MODERATE CONVECTION IS
ALSO FOUND WITHIN 110 NM OFF THE COAST OF PANAMA COLOMBIA AND
VENEZUELA BETWEEN 65W AND 82W. THIS TROUGH IS EXPECTED TO
CONTINUE TO MOVE EASTWARD WITH CONVECTION AFFECTING MOSTLY THE
NORTHEASTERN BASIN INCLUDING HISPANIOLA...PUERTO RICO...AND THE
US/UK VIRGIN ISLANDS. COMPUTER MODELS SUGGEST THIS AREA OF
CONVECTION WILL LINGER THROUGH THURSDAY NIGHT.

THE ATLANTIC OCEAN...
WEAK TO MODERATE CONVECTION IS ALREADY ENTERING THE FAR WESTERN
ATLANTIC FROM A SURFACE TROUGH CURRENTLY OVER THE FLORIDA
PENINSULA. THIS TROUGH IS SUPPORTED BY AN UPPER LEVEL SHORTWAVE
OVER THE EASTERN GULF OF MEXICO. FARTHER EAST...AN UPPER LEVEL
SHORTWAVE IS MOVING ACROSS THE CENTRAL ATLANTIC SUPPORTING A
COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N49W
CONTINUING SOUTHWEST ALONG 27N55W 25N65W. SHOWERS ARE POSSIBLE
WITHIN 120 NM ON EITHER SIDE OF THE FRONT. TO THE EAST OF THIS
FRONT LIES A SURFACE HIGH PRESSURE SYSTEM NEAR 27N35W DOMINATING
THE EASTERN AND PART OF THE CENTRAL ATLANTIC NORTH OF 18N
BETWEEN 20W AND 50W. THIS SURFACE HIGH IS SUPPORTED BY A BROAD
UPPER LEVEL RIDGE THAT COVERS THE EAST/CENTRAL ATLANTIC FROM 20W
TO 50W. A WEAKENING COLD FRONT ENTERS THE DISCUSSION AREA OVER
THE FAR EASTERN ATLANTIC THROUGH 32N10W CONTINUING SOUTHWEST
ALONG 20N20W 16N30W 14N40W. A SHEAR AXIS/REMNANT CLOUD LINE
CONTINUES FROM 14N40W TO 17N52W. SCATTERED WEAK TO MODERATE
SHOWERS ARE WITHIN 50 NM EITHER SIDE OF THE COLD. THE SHEAR AXIS
IS GENERATING A BROAD AREA OF WEAK TO MODERATE SHOWERS COVERING
FROM 12N TO 18N BETWEEN 40W AND 52W. AS THE EASTERN ATLANTIC
COLD FRONT CONTINUES TO WEAKEN AND MOVE EASTWARD...COMPUTER
MODELS HINT THE CONVECTION GENERATED BY THE SHEAR LINE MAY
LINGER NEAR THE MENTIONED AREA THROUGH THURSDAY MORNING. ALSO
LOOK FOR MORE CONVECTION DEVELOPING OVER THE WESTERN ATLANTIC
WEST OF 72W AS THE UPPER LEVEL SHORTWAVE ENTERS THIS REGION.

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

$$

GARCIA




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