[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 142355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT MAR 14 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 3N15W CROSSING THE EQUATOR
NEAR 24W EXTENDING TO 2S34W AND INTO NE BRAZIL NEAR 4S41W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS S OF 3N BETWEEN
5N-12N...AND WITHIN 160 NM N OF AXIS BETWEEN 10W-16W. SIMILAR
CONVECTION IS FOUND WHERE THE ITCZ AXIS MEETS NE BRAZIL.

...DISCUSSION...

GULF OF MEXICO...
A QUASI-STATIONARY FRONT EXTENDS FROM SE LOUISIANA TO A 1011 MB
LOW CENTERED NEAR 20.5N96W THEN THE FRONT CONTINUES MAINLY N
ALONG THE EASTERN SLOPE OF THE SIERRA MADRE MOUNTAINS. THE FRONT
IS AT THE LEADING EDGE OF A WIDE BAND OF CLOUDINESS WITH
EMBEDDED SHOWERS AND ISOLATED TSTMS. LOW LEVEL CONVERGENCE AND
DEEP LAYERED ATMOSPHERIC LIFT ARE SUPPORTING THIS CONVECTIVE
ACTIVITY WHICH IS AFFECTING THE N GULF STATES MAINLY WEST OF THE
FLORIDA PANHANDLE AND THE WESTERN PORTION OF THE GULF. NLY
SURFACE WINDS OF 20 TO 25 KT ARE BEHIND THE FRONT PER AN EARLIER
QSCAT PASS AND SFC DATA. THE STRONGEST WINDS ARE NOTED S OF 25N.
TO THE SE OF THE FRONT...MODERATE SUBSIDENCE IS RESULTING IN
GENERALLY FAIR WEATHER CONDITIONS ACROSS MUCH OF THE S-CENTRAL
AND ERN GULF...INCLUDING THE FLORIDA PENINSULA WHERE THIS
PATTERN IS EXPECTED TO PERSIST INTO EARLY NEXT WEEK. SE-S WINDS
OF 15-20 KT ARE BLOWING AHEAD OF THE FRONT. ALOFT...A RIDGE WITH
AXIS EXTENDING FROM THE YUCATAN PENINSULA TO THE SE CONUS COVERS
MUCH OF THE GULF WATERS WHILE A CUT-OFF LOW IS OVER THE FOUR
CORNER IN THE SW U.S.. SWLY WINDS BETWEEN THESE TWO UPPER-LEVEL
FEATURES ARE TRANSPORTING ABUNDANT MID/UPPER LEVEL MOISTURE
ACROSS THE NORTHERN GULF REGION. THE FRONT WILL MOVE SLOWLY E
REACHING FROM SE LOUISIANA TO WESTERN BAY OF CAMPECHE BY SUN
NIGHT...AND FROM THE WESTERN FL PANHANDLE TO BAY OF CAMPECHE BY
MON AFTERNOON.

CARIBBEAN SEA...
THE COMBINATION OF STRONG HIGH PRES BUILDING S OVER THE WESTERN
ATLC AND LOWER SFC PRESSURE OVER N SOUTH AMERICA IS PRODUCING
FRESH TO STRONG WINDS ACROSS MUCH OF THE BASIN. THESE WEATHER
CONDITIONS ARE EXPECTED TO PERSIST THROUGH MONDAY. GENERALLY
FAIR WEATHER CONDITIONS ARE OBSERVED ACROSS MUCH OF THE
CARIBBEAN REGION...WHERE DEEP LAYERED DRY AIR IS PRESENT.
HOWEVER...SHALLOW MOISTURE EMBEDDED IN THE TRADE WIND FLOW IS
MOVING ACROSS THE REGION PRODUCING ISOLATED TO SCATTERED PASSING
SHOWERS. THESE PATCHES OF LOW LEVEL MOISTURE ARE MORE
CONCENTRATED OVER THE EASTERN CARIBBEAN...PARTICULARLY BETWEEN
12N-16N...AND JUST SOUTH OF THE CAYMAN ISLANDS. SIMILAR CLOUDS
ARE ALREADY AFFECTING THE N LEEWARD ISLANDS.

ATLANTIC OCEAN...
A STATIONARY FRONT CLIPS THE FAR NW PORTION OF THE FORECAST AREA
AND NE FLORIDA. MOST OF THE SHOWER ACTIVITY ASSOCIATED WITH THIS
FRONT IS OVER THE SE CONUS. A 1026 MB SFC HIGH IS LOCATED SW OF
BERMUDA NEAR 31N67W WITH RIDGE ENVELOPING MUCH OF THE WEST AND
CENTRAL ATLC AND THE N CARIBBEAN SEA...INCLUDING THE GREATER
ANTILLES...THE EASTERN GULF OF MEXICO AND THE STATE OF FLORIDA.
ALOFT...A RIDGE ALSO DOMINATES MUCH OF THE AREA RESULTING IN
GENERALLY FAIR WEATHER CONDITIONS. FARTHER TO THE E...AN UPPER
LEVEL LOW LOCATED NEAR 31N35W SUPPORTS A 1007 MB SFC LOW LOCATED
NEAR 30N36W. A SFC TROUGH IS ASSOCIATED WITH THIS LOW AND LIES
ALONG 30N31W 24N30W 16N37W. ATMOSPHERIC INSTABILITY...UPPER
LEVEL DIFFLUENCE...AND LOW LEVEL CONVERGENCE IN THE VICINITY OF
THE SURFACE LOW AND TROUGH ARE HELPING TO INDUCE AND AREA OF
SCATTERED SHOWERS AND ISOLATED TSTMS N OF 26N BETWEEN 25W-31W.
THE REMAINDER OF THE E ATLC AND WEST AFRICA ARE UNDER THE
INFLUENCE OF A NARROW SFC RIDGE WITH MOSTLY FAIR WEATHER. A BAND
OF TRANSVERSE HIGH CLOUDS ASSOCIATED WITH A JET-STREAM BRANCH IS
NOTED S AND SE OF THE AFOREMENTIONED UPPER-LEVEL LOW. ACROSS THE
DEEP TROPICS...A BROAD UPPER LEVEL RIDGE ANCHORED ON A HIGH
CENTERED NEAR 9N19W IS ENHANCING THE CONVECTION ASSOCIATED WITH
THE ITCZ...MAINLY E OF 16W.

$$
GR





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