[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 031735
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN MAY 03 2009

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1500 UTC.

...THE ITCZ...

THE ITCZ AXIS EXTENDS FROM OFF THE COAST OF W AFRICA NEAR 06N03E
TO 01N02W TO THE EQUATOR AT 15W TO NE BRAZIL NEAR 01S45W.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS OCCURRING
NEAR THE COAST OF AFRICA N OF THE EQUATOR AND E OF 07W AND NEAR
THE COAST OF BRAZIL FROM THE EQUATOR TO 07S W OF 30W.

...DISCUSSION...

GULF OF MEXICO...
THE COMBINATION OF A BROAD AREA OF LOW PRESSURE ALONG THE LOWER
TEXAS/MEXICAN COAST AND THE SURFACE RIDGE PUSHING UP AGAINST
FLORIDA IS PRODUCING SE WINDS FROM 15 TO 25 KT...WITH THE HIGHER
WINDS IN THE CENTRAL AND WESTERN GULF.  NO ORGANIZED AREAS OF
DEEP CONVECTION ARE OCCURRING OVER THE GULF...THOUGH SEVERE
WEATHER IS RACING ACROSS LOUISIANA AND MISSISSIPPI CURRENTLY
JUST A FEW DOZEN MILES INLAND.  UPPER LEVEL WINDS AND THE WATER
VAPOR IMAGERY INDICATE RIDGING AND SUBSIDENT FLOW OVER THE
GULF.  A BAND OF CIRRUS STRETCHES FROM THE WESTERN TO THE
NORTHEASTERN GULF ON THE NORTH SIDE OF THE UPPER RIDGE LINE.
THE WEAK FRONTAL BOUNDARY CURRENTLY OVER SOUTHERN TEXAS MAY MAKE
A BRIEF APPEARANCE OVER THE EXTREME NORTHWESTERN GULF...BUT
WOULD SOON BE REPLACED BY SOUTHEASTERLY RETURN FLOW.  THE
SOUTHEASTERLY WINDS OVER THE GULF MAY WEAKEN SLIGHTLY OVER THE
NEXT TWO DAYS AS THE BROAD LOW WEAKENS AND THE RIDGE RETREATS.

CARIBBEAN SEA...
THE TRADEWINDS HAVE SLACKENED SOMEWHAT COMPARED WITH YESTERDAY
WITH WINDS 20 KT OR LESS THROUGHOUT THE CARIBBEAN AS THE RIDGING
TO THE NORTH OF THE CARIBBEAN HAS WEAKENED.  A SURFACE TROUGH
EXISTS ALONG THE LESSER ANTILLES...WHICH APPARENTLY BROKE OFF
FROM THE PARENT TROUGH WHICH HAS CONTINUED PROGRESSING
NORTHEASTWARD TODAY.  SCATTERED SHOWERS ARE AFFECTING THE LESSER
ANTILLES AND INTO THE ATLANTIC FOR ABOUT 180 NM E OF THE TROUGH
AXIS...AS OBSERVED FROM VISIBLE SATELLITE IMAGERY AND GUADELOUPE
/MARTINIQUE RADARS.  THERE IS SCATTERED MODERATE CONVECTION
WITHIN 120 NM OF THE EASTERN PANAMA AND WESTERN COLUMBIA COAST
AS WELL AS OVER HISPANIOLA AND JUST TO THE SOUTHWEST OF THE
ISLAND.  ELSEWHERE NO ORGANIZED DEEP CONVECTION IS OBSERVED.  IN
THE UPPER LEVELS...WINDS UP TO 70 KT ARE ANTICYCLONICALLY
TURNING NORTH OF A RIDGE CENTERED NEAR 10N71W.  CIRRUS IS BEING
ADVECTED EASTWARD BY THESE WINDS FROM OUTFLOW PRODUCED BY DEEP
CONVECTION OVER THE SOUTHWESTERN CARIBBEAN...CENTRAL
AMERICA...AND THE NORTHEAST PACIFIC'S ITCZ.  MOST OF THE
CARIBBEAN SHOULD REMAIN TRANQUIL DURING THE NEXT TWO
DAYS...EXCEPT FOR THE NORTHEASTERN CARIBBEAN ISLANDS WHICH MAY
SEE SOME ENHANCED SHOWERS AND DEEP CONVECTION DUE TO THE TROUGH
AS IT MOVES NORTHWESTWARD.

ATLANTIC OCEAN...
THE ATLANTIC IS DOMINATED BY A SURFACE HIGH PRESSURE CENTERED
WAY UP AT 47N23W WITH RIDGING EXTENDING WEST-SOUTHWESTWARD TO
32N60W AND TO THE FLORIDA PENINSULA.  TWO SMALLER SCALE FEATURES
ARE OF INTEREST.  THE FIRST IS A SURFACE TROUGH NORTH OF PUERTO
RICO ALONG 65W FROM ROUGHLY 21N TO 28N.  THIS TROUGH HAS BEEN
PROGRESSING NORTHWESTWARD AND A PIECE MAY HAVE BROKEN OFF AND IS
NEAR THE LESSER ANTILLES...AS DESCRIBED ABOVE.  A MID TO UPPER
LOW EXISTS WEST OF THE SURFACE TROUGH AND IS HELPING TO ADVECT
MID LEVEL CLOUDINESS OVER THE TROUGH AND TO ITS EAST.  SCATTERED
SHOWERS ARE PRESENT WITHIN 60 NM W OF THE TROUGH AXIS AND 180 NM
E OF THE AXIS.  THE SURFACE WINDS ARE ENHANCED E OF THE TROUGH
AXIS WITH EAST TO SOUTHEAST WINDS 20 TO 25 KT.  THE SECOND
FEATURE IS A TROUGH...AN OLD FRONTAL BOUNDARY...EXTENDING FROM
25N42W TO 32N38W TO 43N35W.  SCATTERED SHOWERS ARE OCCURRING
WITHIN 180 NM E OF THE TROUGH AXIS N OF 27N.  A BOARD UPPER LOW
CENTERED NEAR 31N40W ASSOCIATED WITH THE SURFACE TROUGH
DOMINATES THE UPPER WINDS OVER MOST OF THE REGION WITH
CYCLONICALLY TURNING WINDS OBSERVED ALL THE WAY DOWN TO 10N.
FINALLY...THERE IS AN ENHANCEMENT OF NORTHEASTERLY SURFACE WINDS
OF 20-25 KT NORTHEAST OF THE CAPE VERDE ISLANDS TO THE WEST
COAST OF MAURITANIA AND WESTERN SAHARA.  OVER THE NEXT TWO
DAYS...THE SURFACE TROUGH NORTH OF PUERTO RICO SHOULD CONTINUE
MOVING NORTHWESTWARD...WHILE THE TROUGH IN THE CENTRAL ATLANTIC
SHOULD GRADUALLY FILL.

$$
LANDSEA


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