[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N11W 4N20W 3N35W EQ44W TO THE NE
COAST OF BRAZIL NEAR 2S46W. SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS WITHIN 150 NM S OF THE AXIS E OF 14W.
SCATTERED MODERATE IS ALSO WITHIN 60 NM EITHER SIDE OF THE AXIS
BETWEEN 27W-29W...AND WITHIN 150 NM EITHER SIDE OF AXIS W OF
34W.

...DISCUSSION...

GULF OF MEXICO...
AS INDICATED IN THE PREVIOUS DISCUSSION...A VERY WEAK TROUGH HAS
FORMED IN THE MIDDLE GULF ALONG 27N88W 23N88W. THE 1200 UTC
QUIKSCAT PASS SHOWED THIS BOUNDARY WELL...WHICH IS PRODUCING A
REGION OF LOW AND MID CLOUDS WITH POSSIBLE SHOWERS WITHIN 60 NM
OF THE AXIS. OTHERWISE THE SYNOPTIC SFC PATTERN ACROSS THE GULF
IS DOMINATED BY WEAK RIDGING...WITH A 1021 MB CENTER PLACED NEAR
THE COAST OF SRN LOUISIANA NEAR 29N92W AT 1500 UTC.  RIDGING
CONTINUES IN THE UPPER LEVELS WITH BROAD W TO WNW FLOW OVER THE
BASIN. 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 S OF 26N. MODERATE DRY AIR
EXISTS BOTH 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...THOUGH SHOWERS MAY LINGER NEAR THE WEAK
TROUGH IN THE MIDDLE GULF THROUGH SAT.

CARIBBEAN...
MUCH OF THE CARIB IS QUIET THIS AFTERNOON WITH PLENTY OF DRY
STABLE AIR ALOFT IN PLACE. UPPER RIDGING GENERALLY DOMINATES THE
BASIN W OF 70W WITH A SHORTWAVE TROUGH FROM THE ATLC TO THE E.
THERE IS A FAIR AMOUNT OF MID TO UPPER LEVEL MOISTURE AND A FEW
SMALL POCKETS OF MODERATE CONVECTION OVER COLOMBIA PRODUCED BY
SFC LIFT ALONG THE ITCZ. MOST OF THIS MOISTURE IS CONTAINED S OF
12N. AT THE SFC MODERATE TO FRESH TRADES CONTINUE TO ADVECT
THEIR TYPICAL PATCHES OF LOW LEVEL MOISTURE WWD. 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. TRANQUIL WEATHER IS EXPECTED TO CONTINUE THROUGH THE
WEEKEND WITH CONDITIONS DOMINATED BY MODERATE TRADES.

WESTERN ATLANTIC...
A COMPLEX SURFACE PATTERN AND UNSETTLED WEATHER CONTINUES TO
DOMINATE MUCH OF THE WRN ATLC. A 1013 MB LOW REMAINS NEAR THE SE
BAHAMAS NEAR 24N74W. A TROUGH EXTENDS THROUGH THIS LOW ALONG
29N63W 25N73W THEN THROUGH ERN CUBA. A COLD FRONT ENTERS THE
AREA NEAR 32N60W AND CONTINUES WSW TO NEAR 30N78W. ASSOCIATED
DEEP LAYER CLOUDINESS WITH EMBEDDED CLUSTERS OF SCATTERED
MODERATE CONVECTION ARE FROM 25=4N-31W BETWEEN 52W-74W. THE SFC
FEATURES ARE BEING OBSCURED BUT IN PART SUPPORTED BY THE UPPER
SHORTWAVE TROUGH EXTENDING S ALONG 63W. THE FRONT AND TROUGH/LOW
WILL LIKELY GRADUALLY MESH TOGETHER OVER THE NEXT DAY OR SO. THE
OVERALL PICTURE FROM THE RESULT WILL BE THAT HIGH PRESSURE
PUSHING OFF THE MID ATLANTIC COAST WILL INTERACT THE THE LOW TO
ITS SOUTH TO SET UP INCREASING WINDS/SEAS IN MUCH OF THE AREA
THROUGH EARLY SAT. THIS WILL CONTINUE TO PRODUCE UNSETTLED
WEATHER IN THE AREA THROUGH TOMORROW...AND SEND MODERATE ELY
SWELL TO THE SE U.S. COAST THROUGH EARLY NEXT WEEK.

EASTERN ATLANTIC...
A STRONG 1039 MB HIGH PRES SYSTEM LOCATED ABOUT 300 NM W OF
PORTUGAL 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-29W. ELSEWHERE FAIRLY DRY AIR ALOFT DOMINATES PROVIDING
STABLE CONDITIONS. THE WEAK TROUGH IS EMBEDDED IN LARGE SCALE
UPPER RIDGING THAT IS BEGINNING TO TAKE OVER. 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 SUN AND INTO NEXT
WEEK AS STRONG HIGH PRES REBUILDS E ACROSS THE ATLC.

$$
WILLIS




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