[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211740
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED MAR 21 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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...

ITCZ AXIS IS CENTERED ALONG 6N AT THE PRIME MERIDIAN 3N11W 1N21W
EQ30W 1S40W TO NE BRAZIL NEAR 3S44W. SCATTERED MODERATE
CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN
18W-24W AND 31W-36W. SIMILAR ACTIVITY IS WITHIN 150 NM S OF THE
AXIS BETWEEN 24W-31W AND FROM 2N-6N BETWEEN 30W-43W.

...DISCUSSION...

GULF OF MEXICO...
FAIRLY QUIET WEATHER EXISTS IN THE GULF AS STRONG HIGH
PRES...CENTERED IN THE NE U.S...COVERS THE REGION. THE MAIN
WEATHER ELEMENT IS THE STIFF E TO SELY WINDS ON THE SW PERIPHERY
OF THE SFC RIDGE. SFC OBS AND QSCAT DATA SHOW THE WINDS
GENERALLY IN THE 15-25 KT RANGE. THESE WINDS WILL STAY ON THE
STRONG SIDE...ALTHOUGH SLIGHT RELAXING IS ANTICIPATED THU AND
FRI. ISOLATED PATCHES OF SHALLOW MOISTURE ARE BEING STEERED
ACROSS THE GULF AROUND THE SFC RIDGE LIKELY PRODUCING SOME QUICK
MOVING ISOLATED SHOWERS. IN THE UPPER LEVELS...NWLY FLOW TO THE
W OF A WRN ATLC SHORTWAVE IS COMMON WITH ONLY PATCHY LAYERED
CLOUDS AND ISOLATED SHOWERS N OF 25N BETWEEN 88W-94W. AN
INCREASE IN MOISTURE IS LIKELY ACROSS THE EXTREME SE GULF AS THE
UPPER SHORTWAVE DEEPENS SLIGHTLY. ELSEWHERE MAINLY FAIR WEATHER
IS EXPECTED TO PERSIST OVER THE NEXT COUPLE OF DAYS AS THE
REGION REMAINS ON THE SW PERIPHERY OF THE SFC HIGH AND AN UPPER
RIDGE BUILDS OVERHEAD.

CARIBBEAN...
SCATTERED SHOWERS AND ISOLATED TSTMS CONTINUE OVER PORTIONS OF
ERN CUBA...JAMAICA AND THE WINDWARD PASSAGE. THIS ACTIVITY IS
ASSOCIATED WITH A STALLED FRONTAL BOUNDARY WHICH LIES JUST TO
THE N AND AN UPPER DIFFLUENT PATTERN BETWEEN TROUGHING OVER THE
NW CARIB AND BROAD RIDGING OVER THE TROPICAL ATLC AND E CARIB.
THE REMAINDER OF THE REGION IS RELATIVELY QUIET WITH ONLY
TYPICAL PATCHES OF SHALLOW MOISTURE BEING STEERED W ACROSS THE
SEA. TRADE WINDS...THE STEERING FOR THE CLOUDS/ISOLATED
SHOWERS...ARE BLOWING GENERALLY IN THE 15-25 KT RANGE. LOOKING
AHEAD A FEW DAYS...TRADE WINDS ARE EXPECTED TO SLACKEN A LITTLE
AS THE STRONG SFC HIGH IN THE NE U.S. SHIFTS E. SCATTERED
SHOWERS AND TSTMS ARE LIKELY TO PERSIST AND INCREASE IN COVERAGE
ACROSS SIMILAR REGIONS AS TODAY AS THE WEAK LOW-LEVEL BOUNDARY
REMAINS NEARLY STATIONARY N OF THE ISLANDS AND THE UPPER TROUGH
SHARPENS OVER THE NW CARIB.

ATLANTIC...
THERE IS ONLY ONE AREA OF UNSETTLED WEATHER TO TALK ABOUT IN THE
ATLC BASIN. THE CONTRIBUTING SFC FEATURE IS A STALLED FRONT
WHICH ENTERS THE REGION NEAR 32N53W AND EXTENDS SW ALONG 26N68W
TO THE SE BAHAMAS. THIS SFC BOUNDARY IS NOT EASY TO LOCATE WITH
A MESSY STRUCTURE OF LAYERED CLOUDS AND ONLY A WIND SHIFT FROM
ELY TO NELY. LOW-LEVEL CONVERGENCE ALONG WITH UPPER LEVEL SWLY
FLOW AND DIFFLUENCE BETWEEN TROUGHING OVER THE WRN ATLC AND
RATHER STRONG RIDGING IN THE CENTRAL ATLC IS PRODUCING SCATTERED
SHOWERS AND ISOLATED TSTMS WITHIN 240 NM EITHER SIDE OF THE
FRONT N OF 25N. AN APPROACHING COLD FRONT...JUST N OF THE
AREA...IS LINED UP NW OF THE STATIONARY BOUNDARY. THESE
BOUNDARIES WILL LIKELY MERGE LATER TODAY/TONIGHT. ELSEWHERE SFC
HIGH PRES DOMINATES BOTH TO THE W AND E OF THE FRONT. IN THE W
ATLC...A VERY STRONG 1044 MB HIGH IS CENTERED IN THE NE U.S.
GENERATING SOME STIFF E/NELY WINDS W OF THE FRONT. PATCHES OF
LOW/MID LEVEL CLOUDS ARE BEING STEERED QUICKLY TOWARD THE
BAHAMAS AND FLORIDA...LIKELY PRODUCING SOME ISOLATED SHOWERS.

IN THE E ATLC...A 1034 MB HIGH CONTROLS THE SFC PATTERN. A
FAIRLY TIGHT PRES GRADIENT E OF THE HIGH IS PRODUCING STRONG
WINDS ACROSS THE NE PART OF THE DISCUSSION AREA...N OF 28N E OF
28W. IN THE UPPER LEVELS...AN UPPER LEVEL LOW CENTERED NEAR
31N26W IS ROTATING AROUND EXTENSIVE UPPER LEVEL TROUGHING. A
SWLY JET HAS BEEN SUPPRESSED S A BIT EXTENDING FROM 6N42W 13N22W
ACROSS WRN AFRICA. THIS JET IS AIDING IN THE DEVELOPMENT OF
CONVECTION IN THE ITCZ AND SPREADING WIDESPREAD HIGH LEVEL
MOISTURE SE OF THE JET AXIS. ELSEWHERE UPPER CONFLUENCE IS
LEADING TO ABUNDANT DRY STABLE AIR.

$$
CANGIALOSI


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