[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 062346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI MAR 06 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...AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N8W 2N20W CROSSING THE EQUATOR NEAR
29W EXTENDING TO 2S35W INTO NE BRAZIL NEAR 4S44W. ISOLATED MODERATE
CONVECTION IS ALONG THE ITCZ AXIS BETWEEN 12W-20W. SCATTERED MODERATE
TO ISOLATED STRONG CONVECTION IS OVER PARTS OF LIBERIA...AND WHERE THE
ITCZ MEETS NE BRAZIL.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE CONTINUES TO DOMINATE MUCH OF THE GULF REGION AND
THE SE CONUS. MODERATE TO STRONG UPPER-LEVEL SUBSIDENCE AND IMPLIED DRY
AIR MASS IS NOTED WITHIN THE RIDGE. AS A RESULT...GENERALLY FAIR
WEATHER CONDITIONS PERSIST ACROSS THE GULF WATERS. THE SUBSIDENCE IS
BEING SUPPORTED BY A SURFACE RIDGE THAT EXTENDS SOUTHWESTWARD FROM A
1034 MB SURFACE HIGH IN THE W ATLC NEAR 32N72W. THE FLOW AROUND THIS
SURFACE RIDGE IS RESULTING IN MAINLY SE WINDS OF 15-20 KT ACROSS MUCH
OF THE GULF. ELY WINDS OF 20-25 KT CONTINUE BLOWING THROUGH THE
STRAITS OF FLORIDA AND ACROSS THE SE PORTION OF THE GULF S OF 24N. THE
SFC HIGH IS EXPECTED TO MOVE SLIGHTLY SW AND REMAIN NEARLY STATIONARY
DURING THE UPCOMING WEEKEND. AS A RESULT...THE OVERALL WEATHER PATTERN
ACROSS THE GULF WILL CHANGE LITTLE THROUGH SUN NIGHT.

CARIBBEAN SEA...
THE TAIL END OF A COLD FRONT OVER THE CENTRAL ATLANTIC OCEAN REACHES
THE N LEEWARD ISLANDS GENERATING SOME CLOUDINESS AND LIGHT TO MODERATE
SHOWERS. THE FRONTAL BOUNDARY HAS BECOME ILL DEFINED ACROSS THE EASTERN
CARIBBEAN WITH SATELLITE IMAGERY INDICATING A BAND OF MAINLY LOW-LEVEL
CLOUDS ASSOCIATED WITH THE REMNANTS OF THIS FRONT WHICH EXTENDS FROM
THE N LEEWARD ISLANDS TO THE ABC ISLANDS WHERE SOME SHOWER ACTIVITY IS
OBSERVED. NE-E LOW LEVEL WINDS ASSOCIATED WITH THE SFC HIGH IN THE W
ATLC ARE TRANSPORTING PATCHES OF SHALLOW MOISTURE ACROSS CUBA AND
HISPANIOLA. FRESH TO STRONG NE-E WINDS ARE BLOWING ACROSS THE MAJORITY
OF THE BASIN ADVECTING POCKETS OF LOW LEVEL MOISTURE WITH EMBEDDED
SHOWERS ACROSS THE CARIBBEAN WATERS INTO CENTRAL AMERICA. THE GREATEST
CONCENTRATION OF THESE SHOWERS IS SOUTH OF JAMAICA FROM 14N-17N BETWEEN
74W-79W. ALSO...A GALE WARNING IS IN EFFECT FOR LOCATIONS WITHIN 90 NM
OF THE COLOMBIAN COAST WITH THE INCREASED SURFACE WINDS RESULTING FROM
THE INCREASED SURFACE PRESSURE GRADIENT ACROSS THE CARIBBEAN. ALOFT...
SUBSIDENCE RESULTING FROM CONFLUENCE IN WESTERLY FLOW ALOFT IS LIMITING
DEEP CONVECTION ACROSS MUCH OF THE REGION.

ATLANTIC OCEAN...
A DEEP LAYERED TROUGH REMAINS OVER THE W ATLC. THE ASSOCIATED COLD
FRONT EXTENDS FROM A DEVELOPING GALE CENTER NEAR 30N51W TO THE N
LEEWARD ISLANDS. LOW LEVEL CONVERGENCE IS HELPING TO INDUCE SCATTERED
SHOWERS WITHIN 70 NM EITHER SIDE OF THIS FRONT...AND IS ALSO SUPPORTING
SCATTERED SHOWERS WITHIN 80 NM EITHER SIDE OF A PRE-FRONTAL TROUGH
WHICH LIES ALONG 13N55W 19N53W 24N53W. ALL THIS ACTIVITY IS BEING
SUPPORTED BY UPPER LEVEL DIVERGENCE ASSOCIATED WITH TWO UPPER LEVEL JET
MAXIMA IN THE VICINITY OF THE SURFACE LOW. THE SURFACE LOW IS FORECAST
TO MOVE NORTHEASTWARD DURING THE NEXT DAY. IN THE WAKE OF THE FRONT...A
RELATIVELY COOLER AND DRIER AIRMASS IS PRESENT ASSOCIATED WITH A 1034
MB HIGH LOCATED NEAR 32N72W. BROKEN COLD AIR STRATOCUMULUS CLOUDS ARE
NOTED MOVING ACROSS THE W ATLC INTO THE BAHAMAS AND CUBA UNDER A
PREVAILING NE-E FLOW. ACROSS THE E ATLC...AN UPPER LOW IS LOCATED NEAR
27N24W. ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS UPPER LOW IS
SUPPORTING SCATTERED SHOWERS FROM 27N-31N BETWEEN 20W-27W. HOWEVER...
SUBSIDENCE ASSOCIATED WITH A SURFACE RIDGE IS INHIBITING DEEP
CONVECTION ACROSS MUCH OF THE E ATLC. MID/UPPER LEVEL MOISTURE IS BEING
DRAWN ACROSS THE EASTERN ATLC BETWEEN THE CANARY AND THE CAPE VERDE
ISLANDS BY STRONG SWLY WINDS ALOFT. AN UPPER-LEVEL RIDGE LOCATED NEAR
4N34W DOMINATES MUCH OF THE DEEP TROPICS.

$$
GR



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