[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091129
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST FRI MAR 09 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1100 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N11W 4N20W 3N32W 1N43W TO 1S51W.
SCATTERED MODERATE CONVECTION IS WITHIN 150 NM S OF THE AXIS E
OF 13W AND FROM 1S-1N BETWEEN 39W-43W. SCATTERED SHOWERS AND
TSTMS ARE WITHIN 30 NM EITHER SIDE OF THE AXIS BETWEEN 20W-43W.

...DISCUSSION...

GULF OF MEXICO...
IT'S ANOTHER RELATIVELY QUIET MORNING IN THE GULF AS WEAK
VERTICALLY STACKED RIDGING REMAINS PARKED ACROSS THE REGION.
UPPER LEVEL SWLY FLOW ON THE WRN PERIPHERY OF THE RIDGE IS
ADVECTING HIGH LEVEL MOISTURE FROM THE EPAC ACROSS CENTRAL
MEXICO AND INTO THE GULF MAINLY BETWEEN 24N-28N. EVEN THOUGH THE
ATMOSPHERE IS A LITTLE MORE MOIST THAN THE PAST FEW
DAYS...CONDITIONS REMAIN FAIR ACROSS THE ENTIRE AREA. MODERATE
DRY AIR EXISTS BOTH S AND N OF THE UPPER MOISTURE PLUME. THE
WEAK PATTERN AT THE SFC IS KEEPING WINDS AND SEAS FAIRLY LIGHT
AND THEY ARE EXPECTED TO REMAIN THAT WAY THROUGH SAT AS THE SFC
PRES GRADIENT CHANGES LITTLE. MAINLY FAIR WEATHER IS ALSO
EXPECTED TO CONTINUE UNDER WEAK HIGH PRES. THE ONLY AREA OF
POSSIBLE DEVELOPING WEATHER IS IN THE CENTRAL GULF AS GFS HAS
BEEN HINTING AT DEVELOPING A VERY WEAK LOW-LEVEL TROUGH LATER
TODAY THAT MAY PRODUCE SOME  ORGANIZED CLOUDS/SHOWERS.

CARIBBEAN...
MUCH OF THE CARIB IS QUIET THIS MORNING WITH PLENTY OF DRY
STABLE AIR ALOFT IN PLACE. THIS DRY AIR IS BEING ENHANCED BY A
SHORTWAVE TROUGH THAT EXTENDS SWD FROM THE ATLC ACROSS PUERTO
RICO TO 14N68W. THERE IS A FAIR AMOUNT OF MID TO UPPER LEVEL
MOISTURE AND EVEN SOME SMALL POCKETS OF MODERATE CONVECTION OVER
COLOMBIA PRODUCED BY SFC LIFT ALONG THE ITCZ AND UPPER
DIFFLUENCE BETWEEN THE SHORTWAVE AND A STRONG UPPER RIDGE
CENTERED OVER NE S AMERICA. MOST OF THIS MOISTURE IS CONTAINED S
OF 13N. IN THE LOWER LEVELS...NIGHT CHANNEL VIS SHOWS VERY THIN
PATCHES OF CLOUDS DRIVEN W BY MODERATE TO FRESH TRADES. THERE IS
A LITTLE MORE ORGANIZATION TO THE CLOUDS OVER THE YUCATAN
PENINSULA AND THE CHANNEL ASSOCIATED WITH THE REMNANTS OF A WEAK
SFC TROUGH. MUCH MORE ACTIVE WEATHER LIES TO THE N OF THE REGION
E OF THE BAHAMAS AND IS DISCUSSED IN THE WESTERN ATLC SECTION
BELOW. TRANQUIL WEATHER IS EXPECTED TO CONTINUE INTO THE
WEEKEND.

WESTERN ATLANTIC...
UNLIKE THE GULF AND CARIB THERE IS MORE SIGNIFICANT WEATHER TO
TALK ABOUT IN THIS REGION. THE MAIN PLAYERS ARE AN UPPER LEVEL
SHORTWAVE TROUGH ROTATING THROUGH THE BASE OF A LARGE POLAR
VORTEX AND A SFC TROUGH ANALYZED FROM ERN CUBA TO 30N65W. A WEAK
SFC LOW HAS FORMED ALONG THIS TROUGH NEAR 25N73W. THIS FEATURE
IS WELL DEPICTED IN AN EARLIER QSCAT PASS AND SFC OBS WHICH
DISPLAY CYCLONIC TURNING ESPECIALLY ACROSS THE CENTRAL AND
EASTERN BAHAMAS. INFRARED SATELLITE IMAGES DEPICT SOME COLD
CLOUD TOPS FROM 22N-32N BETWEEN 56W-70W. SCATTERED SHOWERS
APPEAR VERY LIKELY IN THIS OUTLINED AREA...WHICH IS E OF THE SFC
TROUGH DUE TO THE STRONGLY SHEARED ENVIRONMENT. A COLD FRONT IS
LINED UP BEHIND THE TROUGH ENTERING THE AREA NEAR 32N61W TO
30N75W THEN STATIONARY TOWARD THE SE GEORGIA COAST. GFS SHOWS
THIS FRONT MERGING WITH THE TROUGH/LOW LATER TODAY LIKELY
CONTINUING TO PRODUCE UNSETTLED WEATHER FOR PARTS OF THE REGION.
BEHIND THE FRONT...STRONG HIGH PRES IS SURGING SE. THIS IS
SETTING UP A TIGHT PRES GRAD CAUSING STRONG NELY WINDS THAT WILL
SPREAD SE INTO THE AREA TODAY.


EASTERN ATLANTIC...
A STRONG 1036 MB HIGH PRES SYSTEM LOCATED BETWEEN PORTUGAL AND
THE AZORES IS DOMINATING THE SFC PATTERN ACROSS THE ATLC E OF
45W. THIS HIGH IS PRODUCING MODERATE TO STRONG TRADE WINDS
ACROSS A GOOD PORTION OF THE DISCUSSION AREA PARTICULARLY E OF
30W WHERE THE TIGHTEST PRES GRAD EXISTS. THE UPPER LEVEL TROUGH
THAT HAS BEEN DRIFTING N IN THE AREA HAS NOW JUST ABOUT
DISSIPATED. ONLY PATCHES OF MID AND HIGH LEVEL CLOUDS ARE LEFT N
OF 22N BETWEEN 20W-30W. ELSEWHERE DRY AIR ALOFT DOMINATES
PROVIDING STABLE CONDITIONS. OVER THE NEXT COUPLE OF DAYS...THE
STRONG SFC HIGH IS FORECAST TO RETREAT NE ALLOWING THE TRADES TO
RELAX SLIGHTLY THIS WEEKEND IN THE E ATLC. HOWEVER THEY ARE SET
TO PICK UP AGAIN ON SUN AND INTO NEXT WEEK AS STRONG HIGH PRES
BUILDS E ACROSS THE ATLC.

$$
CANGIALOSI




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