[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 291805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI 29 APR 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
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 1200 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 1715 UTC.

...THE ITCZ...

ITCZ 10N13W 6N20W 3N30W 2N40W 4N50W 5N60W. STRONG SHOWERS AND
THUNDERSTORMS ARE IN COASTAL SECTIONS WESTERN GHANA AND EASTERN
IVORY COAST. INDIVIDUAL CLUSTERS OF SHOWERS AND THUNDERSTORMS
ARE EVIDENT FROM 5N TO 10N BETWEEN 7W AND 13W FROM LIBERIA TO
GUINEA AND SIERRA LEONE. ISOLATED TO WIDELY SCATTERED MODERATE/
LOCALLY STRONG SHOWERS AND THUNDERSTORMS ELSEWHERE FROM THE
EQUATOR TO 7N BETWEEN 25W AND 54W.

...DISCUSSION...
THE GULF OF MEXICO...
BROAD MIDDLE TO UPPER LEVEL RIDGE COVERS INTERIOR MEXICO AND
THE GULF OF MEXICO...CREATING TRANQUIL WEATHER. SURFACE RIDGE
THROUGH 1021 MB HIBH PRESSURE CENTER NEAR 34N69W TO 29N78W...
ACROSS THE BAHAMAS AND CUBA TO 20N80W TO EASTERN HONDURAS NEAR
16N85W. SURFACE WIND FLOW ACROSS FLORIDA THE GULF WATERS IS FROM
THE EAST AND SOUTHEAST. EXPECT THIS OVERALL PATTERN TO REMAIN
THROUGH TONIGHT WITH THE NEXT COLD FRONT MOVING OFF THE
SOUTHEASTERN TEXAS COAST EARLY SATURDAY. THE FRONT WILL START
OFF WITH LIMITED MOISTURE AND SHOWERS AND THUNDERSTORMS AS IT
MOVES OFF THE COAST. A LINE OF SHOWERS AND THUNDERSTORMS SHOULD
DEVELOP NORTH OF 26N DURING THE DAY ON SATURDAY AS THE FRONT
MOVES ACROSS THE NORTH CENTRAL AND EASTERN GULF. THIS FRONT IS
NOT FORECAST TO MAKE AS MUCH SOUTHWARD PROGRESS...STALLING OUT
AROUND CENTRAL FLORIDA ON SUNDAY...UNLIKE THE LAST TWO
FRONTS.

THE CARIBBEAN SEA...
AN UPPER LEVEL RIDGE RUNS FROM NORTHERN COLOMBIA...OVER THE
WESTERN CARIBBEAN WATERS/THE COASTAL WATERS OF CENTRAL
AMERICA...TOWARD HONDURAS. THE UPPER LEVEL WIND FLOW ACROSS
THE OPEN CARIBBEAN SEA IS WESTERLY WEST OF 70W...AND MORE
NORTHWESTERLY EAST OF 70W. MIDDLE TO UPPER LEVEL DRY AIR REMAINS
IN THE AREA. MIDDLE TO UPPER LEVEL TROUGH MOVING EASTWARD OVER
THE WESTERN ATLANTIC CLIPS THE NORTHEASTERN CARIBBEAN SEA.
POSSIBLE SHOWERS IN LINES OF LOW CLOUDS WITH COMPARATIVELY WARM
CLOUD TOP TEMPERATURES. EXPECT MAINLY DRY CONDITIONS TO CONTINUE
INTO THE WEEKEND...EXCEPT FOR THE EXTREME NORTHEASTERN CORNER...
WHERE SHOWERS AND THUNDERSTORMS WITH THE PASSING UPPER TROUGH
AND FRONT ARE POSSIBLE DURING THE NEXT 2 DAYS. SHOWERS AND
THUNDERSTORMS ARE POSSIBLE NOW IN LOW CLOUDS WITHIN 60 TO 90 NM
ON EITHER SIDE OF 17N67W 21N61W IN THE NORTHEASTERN CARIBBEAN
SEA.

THE ATLANTIC OCEAN...
THE MIDDLE TO UPPER LEVEL TROUGH WHICH MOVED OFF THE EAST COAST
OF THE U.S.A. YESTERDAY IS NOW EAST OF BERMUDA...PASSING THROUGH
32N61W 27N61W TO 17N63W IN THE NORTHEASTERN CARIBBEAN SEA. DRY
AIR/STRONG SUBSIDENCE ON THE WESTERN SIDE OF THE TROUGH IS
CREATING VERY DRY AND STABLE CONDITIONS ALOFT AND GENERALLY
CLOUD FREE CONDITIONS. ISOLATED TO WIDELY SCATTERED MODERATE/
LOCALLY STRONG SHOWERS AND THUNDERSTORMS ARE EAST OF THE
TROUGH...IN AN AREA OF UPPER LEVEL DIFFLUENT WIND FLOW...NORTH
OF 20N BETWEEN 50W AND 61W. SHOWERS AND THUNDERSTORMS ARE
POSSIBLE WITHIN 60 TO 90 NM ON EITHER SIDE OF 17N67W 21N61W
IN THE NORTHEASTERN CARIBBEAN SEA. THIS ACTIVITY WILL CONTINUE
TO MARCH EASTWARD ACROSS THE CENTRAL ATLANTIC DURING THE NEXT
24 HOURS EVEN THOUGH THE FRONT WILL WEAKEN. EXPECT THE BEST
COVERAGE OF SHOWERS AND THUNDERSTORMS TO BE NORTH OF 20N BETWEEN
50W AND 60W TONIGHT. MIDDLE TO UPPER LEVEL ANTICYCLONIC FLOW IS
NORTH OF 20N BETWEEN 45W AND 60W. THIS RIDGE IS BEING UNDERCUT
BY A BROAD/DIFFUSE UPPER LEVEL TROUGH WHICH EXTENDS FROM THE
EASTERN ATLANTIC OCEAN JUST WEST OF THE CANARY ISLANDS NEAR
32N27W SOUTHWESTWARD ALONG 20N40W TO 10N60W. 995 MB STORM CENTER
IS NEAR 45N29W...WITH A TRAILING COLD FRONT WHICH PASSES THROUGH
32N24W TO 24N34W. FINALLY OVER THE TROPICAL ATLC....A WELL
DEFINED MIDDLE TO UPPER LEVEL ANTICYCLONE HAS DEVELOPED OFF THE
W COAST OF AFRICA NEAR 7N20W WITH ASSOCIATED RIDGE EXTENDING
WESTWARD TO 8N35W. THIS SETUP WOULD TYPICALLY FAVOR ITCZ
CONVECTION OVER THE E ATLC.  HOWEVER...VISIBLE SATELLITE IMAGERY
INDICATES AN AREA OF VERY DRY AIR AND DUST ORIGINATING FROM
AFRICA PUSHING WESTWARD WITH LEADING EDGE ALONG 32W/33W.

$$
MT


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