[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 032344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE MAR 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 1800 UTC SURFACE ANALYSIS...SATELLITE IMAGERY THROUGH
1745 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N10W 1N20W CROSSING THE EQUATOR
NEAR 22W EXTENDING TO 2S30W INTO NE BRAZIL NEAR 3S44W. A LARGE
CLUSTER OF MODERATE TO STRONG CONVECTION COVERS FROM 5N-9N
BETWEEN 5W-10W INCLUDING MUCH OF LIBERIA. SIMILAR CONVECTION IS
ALSO NOTED ALONG NORTHERN BRAZIL WHERE A 1007 MB LOW IS NEAR
3S44.5W. ISOLATED MODERATE CONVECTION IS WITHIN 60 NM EITHER
SIDE OF AXIS BETWEEN 10W-17W. ISOLATED MODERATE CONVECTION IS
ALSO FOUND ALONG THE EQUATOR BETWEEN 19W-21W...AND BETWEEN
41W-43W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF REGION IS UNDER THE INFLUENCE OF SURFACE RIDGE ANCHORED
ON A 1035 MB HIGH OVER THE OHIO VALLEY. THIS SYSTEM IS PRODUCING
MOSTLY FAIR WEATHER AND LIGHT TO MODERATE WINDS ACROSS THE GULF.
COLD AIR ADVECTION OVER THE RELATIVELY WARMER GULF WATERS IS
RESULTING IN SCATTERED STRATOCUMULUS CLOUDS ACROSS MUCH OF THE
AREA. THE SFC HIGH IS FORECAST TO MOVE SE TOWARDS THE CAROLINAS
DURING THE NEXT 24 HOURS. AS A RESULT...SLY RETURN FLOW WILL
INCREASE OVER THE W GULF BEGINNING TOMORROW. ALOFT...STRONG
NORTHERLY FLOW IS RESULTING IN SUBSIDENCE ACROSS MUCH OF THE
GULF REGION...WHERE A DEEP LAYERED DRY AIR MASS IS IN PLACE.
THESE WINDS ARE ADVECTING SOME MID/UPPER LEVEL MOISTURE ACROSS
THE NE CORNER OF THE GULF...WHERE SCATTERED HIGH LEVEL CLOUDS
ARE PRESENT.

CARIBBEAN SEA...
A DEEP LAYERED TROUGH OVER THE E CONUS AND W ATLC EXTENDS INTO
THE NW CARIBBEAN/GULF OF HONDURAS. THE ATTENDANT FRONTAL ZONE
ENTERS THE CARIBBEAN SEA...AS A STATIONARY FRONT...THROUGH
HISPANIOLA THEN CONTINUES SWWD TO COSTA RICA. MODERATE TO FRESH
NLY WINDS BEHIND THE FRONTAL BOUNDARY ARE ADVECTING LOW LEVEL
MOISTURE WITH EMBEDDED LIGHT TO OCCASIONALLY MODERATE RAIN OVER
THE CARIBBEAN SIDE OF COSTA RICA AND WESTERN PANAMA. THE FRONT
IS ALSO GENERATING ABUNDANT CLOUDINESS AND SCATTERED SHOWERS
OVER HISPANIOLA. MOISTURE AHEAD OF THIS FRONTAL SYSTEM IS ALSO
ENHANCING SOME SHOWER ACTIVITY ACROSS THE MONA PASSAGE AND
PUERTO RICO. THE FRONT IS FORECAST TO SLOWLY MOVE ACROSS PUERTO
RICO WED NIGHT AND THURSDAY AS SFC HIGH PRES CURRENTLY OVER THE
OHIO VALLEY MOVES SEWD OVER THE CAROLINAS WED AND THEN INTO THE
W ATLC WED NIGHT. THERE IS A RISK OF HEAVY RAINS WITH THE
POTENTIAL FOR FLASH FLOODING IN PUERTO RICO WED AND THU WITH THE
FRONTAL PASSAGE. ACROSS THE E CARIBBEAN...MID/UPPER LEVEL
MOISTURE CONTINUES TO BE DRAWN NORTHWARD BETWEEN A RIDGE OVER
THE TROPICAL ATLC AND THE AFOREMENTIONED DEEP LAYERED TROUGH.

ATLANTIC OCEAN...
THE DEEP LAYERED TROUGH OVER THE E CONUS AND W ATLC SUPPORTS A
COLD FRONT THAT ENTERS THE FORECAST AREA NEAR 32N63W THEN
CONTINUES SW TO NEAR 28N64W, AT THIS POINT...THE FRONT BECOMES
STATIONARY EXTENDING OVER HISPANIOLA AND THE CENTRAL CARIBBEAN
TO COSTA RICA. LOW LEVEL CONVERGENCE IS ASSISTING IN THE
DEVELOPMENT OF SCATTERED SHOWERS WITHIN 180 NM EITHER SIDE OF
THIS FRONT. THIS ACTIVITY IS BEING SUPPORTED BY STRONG UPPER
LEVEL DIVERGENCE ASSOCIATED WITH AN UPPER LEVEL JET MAXIMUM TO
THE W OF THE FRONT. IN THE WAKE OF THE FRONT...A RELATIVELY
COOLER AND DRIER AIRMASS IS PRESENT ASSOCIATED WITH THE 1035 MB
HIGH OVER THE OHIO VALLEY. FARTHER TO THE E...A 1018 MB SURFACE
LOW IS LOCATED NEAR 28N48W. A WELL DEFINED SWIRL OF LOW CLOUDS
IS ASSOCIATED WITH THE LOW FORECAST TO DISSIPATE IN ABOUT 24
HOURS OR SO. A SFC TROUGH EXTENDS FROM THE LOW TO 25N46W TO
21N48W. AN AREA OF SCATTERED SHOWERS IS AHEAD OF THE TROUGH
COVERING THE AREA N OF 24N BETWEEN 40W-44W. TIGHT PRES GRADIENT
BETWEEN THIS LOW AND STRONG 1042 SFC HIGH LOCATED JUST WEST OF
THE AZORES IS PRODUCING A SWATH OF GALE FORCE WINDS JUST N OF
AREA AND WITHIN AROUND 300 NM NE OF THE LOW CENTER. A RIDGE
EXTENDS FROM THE ABOVE MENTIONED STRONG SFC HIGH ACROSS THE
REMAINDER OF THE ATLANTIC FORECAST AREA PRODUCING MOSTLY FAIR
WEATHER AND MODERATE TO FRESH TRADE WINDS...PARTICULARLY EAST OF
40W. AN UPPER-LEVEL HIGH CENTERED NEAR 5N50W DOMINATES MUCH OF
THE DEEP TROPICS. THIS RIDGE IS HELPING TO INDUCE MODERATE TO
STRONG CONVECTION OVER N SOUTH AMERICA.

$$
GR



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