[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI MAR 04 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION 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
1715 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM THE
COAST OF LIBERIA NEAR 05N09W TO 02N20W TO 01N30W CONTINUING S OF
THE EQUATOR TO THE COAST OF BRAZIL NEAR 02S43W. SCATTERED
MODERATE CONVECTION IS WITHIN 90 NM S OF THE AXIS BETWEEN 27W
AND 36W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 270
NM N OF THE AXIS BETWEEN 28W AND 38W. SIMILAR CONVECTION IS FROM
03N TO 07N BETWEEN 38W AND 44W.

...DISCUSSION...

GULF OF MEXICO...
A WEAK UPPER RIDGE EXTENDS ACROSS THE AREA REACHING FROM NEAR
THE COAST OF S CENTRAL LOUISIANA TO MEXICO NEAR 19N95W IN THE
BAY OF CAMPECHE. WATER VAPOR SATELLITE IMAGERY INDICATES MAINLY
DRY AND STABLE AIR ACROSS THE BASIN. THE EXCEPTION IS IN THE
CENTRAL GULF WHERE A SHEAR AXIS EXTENDS FROM JUST S OF LOUISIANA
NEAR 28N91W TO THE YUCATAN CHANNEL NEAR 22N85W. THIS SHEAR AXIS
IS THE REMNANTS OF A STATIONARY FRONT AND SURFACE LOW WHICH
DISSIPATED OVER THE AREA DURING THE OVERNIGHT HOURS. SCATTERED
SHOWERS ARE WITHIN 180-240 NM NE OF THIS AXIS WITH ISOLATED
TSTMS ALSO POSSIBLE. LIGHT TO FRESH SE WINDS EXIST TO THE W OF
THIS BOUNDARY WITH FRESH TO STRONG E OF THE BOUNDARY. THE SHEAR
AXIS WILL DISSIPATE TONIGHT WITH A COLD FRONT PUSHING INTO THE
NW GULF FROM THE TEXAS COAST SAT AFTERNOON. THE FRONT WILL REACH
FROM SE LOUISIANA TO THE BAY OF CAMPECHE SAT NIGHT AND WILL
QUICKLY WEAKEN AS IT MOVES INTO THE E GULF SUN...MOVING E OF THE
AREA BY MON MORNING. LATEST MODEL GUIDANCE IS TRENDING WEAKER
AND SLOWER WITH THE FRONT ALTHOUGH GALE FORCE WINDS ARE STILL
FORECAST BEHIND IT IN THE SW GULF BEGINNING AROUND 06Z SAT NIGHT.

CARIBBEAN SEA...
AN UPPER TROUGH REACHES FROM CENTRAL CUBA TO THE E COAST OF
NICARAGUA NEAR 12N83W. SW FLOW EXISTS AHEAD OF THE TROUGH OVER
THE REMAINDER OF THE BASIN WITH A MAINLY DRY AND STABLE
ATMOSPHERE THROUGHOUT ALOFT. THE REMNANTS OF A STATIONARY FRONT
ARE IN THE WINDWARD PASSAGE EXTENDING SW TO JAMAICA. THIS
BOUNDARY WILL CONTINUE TO DISSIPATE THIS AFTERNOON. A WEAK
SURFACE TROUGH REMAINS IN THE E CARIBBEAN FROM NEAR 16N64W TO
12N68W. SCATTERED SHOWERS ARE OCCURRING WITHIN 90-120 NM EITHER
SIDE OF THE TROUGH AXIS. THIS TROUGH WILL DISSIPATE DURING THE
NEXT 24 HOURS. ELSEWHERE WIDESPREAD SHOWERS REMAIN OVER THE W
CARIBBEAN WITH FRESH TO STRONG TRADE WINDS IN THE LEE OF CUBA.
FRESH TO STRONG WINDS ALSO EXIST NEAR THE COAST OF COLOMBIA
WHERE THERMAL LOW PRES IS DEVELOPING OVER COLOMBIA AND HIGHER
PRES EXISTS TO THE NE CREATING A TIGHT GRADIENT. WINDS WILL
DIMINISH ACROSS THE BASIN THIS WEEKEND AS HIGH PRES NE OF THE
AREA RETREATS WEAKENING THE GRADIENT.

ATLANTIC OCEAN...
A STRONG 1044 MB SURFACE HIGH IS MOVING ACROSS THE FAR NE CONUS
AND INTO MARITIME CANADA EARLY THIS AFTERNOON. A VERY TIGHT PRES
GRADIENT EXITS S OF THIS HIGH AND INTO THE NW PORTION OF THE
AREA WITH 20-30 KT WINDS OCCURRING E OF FLORIDA THROUGH THE
BAHAMAS AND NE OF CUBA. A STATIONARY FRONT EXTENDS FROM 31N57W
TO JUST NE OF HAITI NEAR 20N73W. SCATTERED SHOWERS AND ISOLATED
TSTMS ARE OCCURRING WITHIN 90-120 NM EITHER SIDE OF THE FRONT
MAINLY N OF 24N. WIDESPREAD SHOWERS ARE ALSO OCCURRING
THROUGHOUT THE AREA NW OF THE FRONT WITH COLDER AIR ALOFT MOVING
OVER THE RELATIVELY WARMER SEA SURFACE. THE FRONT WILL BECOME
LESS DEFINED ON SAT DISSIPATING BY SUN NIGHT. WINDS WILL
DIMINISH SAT NIGHT AND SUN AS THE NEXT COLD FRONT APPROACHES THE
NW PORTION FROM THE CONUS. THE FRONT WILL PUSH SE OFF THE
GEORGIA/FLORIDA COAST SUN NIGHT WEAKENING AS IT MOVES OVER THE
CENTRAL BAHAMAS MON. A WEAK SURFACE TROUGH IS NE OF THE LESSER
ANTILLES FROM NEAR 21N63W TO 18N61W JUST E OF BARBUDA. SCATTERED
SHOWERS ARE OCCURRING WITHIN 60 NM W OF THE TROUGH AND 90-120 NM
NE OF THE TROUGH.

FARTHER EAST...A WEAK SURFACE TROUGH EXTENDS FROM 30N39W TO
27N36W AND WAS CAPTURED NICELY BY A 1256Z ASCAT PASS WHICH
INDICATED ONLY 5-15 KT WINDS. THIS FEATURE WILL DISSIPATE LATER
TODAY. ELSEWHERE ACROSS THE BASIN AN UPPER ANTICYCLONE HAS
FORMED NEAR 05N31W WITH A RIDGE AXIS COVERING THE AREA ALONG
05/06N. CONVECTION ALONG THE ITCZ IS BEING ENHANCED ON THE SW
SIDE OF THE ANTICYCLONE AS DESCRIBED ABOVE.

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

$$
LEWITSKY




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