[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED MAR 07 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 7N10W 5N20W 1N35W EQ45W EQ50W.
SCATTERED MODERATE CONVECTION IS WITHIN 180 NM S OF THE AXIS E
OF 19W AND FROM 4S-4N W OF 28W.

...DISCUSSION...

GULF OF MEXICO...
SFC RIDGING ALONG THE NRN GULF COAST CONTINUES TO DOMINATE THE
GOMEX THIS AFTERNOON. THIS IS PRODUCING FAIRLY LIGHT WINDS
ACROSS THE AREA WITH SEAS CONTINUING TO SUBSIDE MOSTLY BELOW 4
FT EXCEPT THE AREA S OF 25N E OF 94W WHERE SOME LINGERING ENE
SWELL EXISTS. FAIRLY EXTENSIVE LOW LEVEL CLOUD DECK IS SEEN
OFFSHORE TEXAS AND LOUISIANA...N OF 26N BETWEEN 88W-96W. IN THE
MID AND UPPER LEVELS...THE FLOW IS MAINLY FROM THE WNW AROUND
GENTLE RIDGING BUILDING INTO THE GULF FROM MEXICO AND BEHIND THE
POLAR VORTEX EXTENDING S FROM ERN CANADA. THIS IS ADVECTING A
FEW PATCHES OF CIRRUS THROUGH THE GULF BUT OVERALL FAIRLY DRY
UPPER AIR DOMINATES. OVER THE NEXT COUPLE OF DAYS...WEAK RIDGING
WILL PERSIST ALONG THE NRN GULF COAST KEEPING WINDS LIGHT TO
MODERATE. THE MID AND UPPER PATTERN WILL LIKELY REMAIN NEARLY
ZONAL BUT MAY INCREASE IN MAGNITUDE AS SMALL IMPULSES/VORT MAXES
MOVE ACROSS THE SRN U.S.

CARIBBEAN...
A PIECE OF THE OLD FRONTAL BOUNDARY SEEMS TO HAVE REESTABLISHED
ITSELF IN THE GULF OF HONDURAS. SATELLITE IMAGERY SUGGESTS A
WEAK LOW MAY HAVE RECENTLY FORMED JUST N OF THE ISLAS DE LA
BAHIA...AND WILL REEVALUATE FOR THE 1800 MAP. BASED ON THE BROAD
ELONGATED TURNING SEEN IN THIS MORNINGS HIRES QUIKSCAT
DATA...HAVE OPTED WITH A TROUGH WHICH WAS PLACED ALONG 19N84W
15N86W AS OF 1500 UTC. SUSPECT THERE ARE SCATTERED SHOWERS
EMBEDDED IN THE ASSOCIATED BROKEN LOW TO MID CLOUD DECK SEEN
ALONG COASTAL HONDURAS AND BELIZE...AND CARIB WATERS FROM
15N-21N BETWEEN 82W-89W. GFS SUGGESTS THIS AREA WILL DRIFT
SLOWLY W OVER THE NEXT COUPLE OF DAYS...WITH SHOWERS LINGERING
BETWEEN HONDURAS...BELIZE...AND THE WRN YUCATAN. OTHER LOW LEVEL
CONFLUENT ZONES WITH POSSIBLE SHOWERS SEEN HUGGING THE COAST OF
HISPANIOLA THROUGH ERN CUBA...ALSO SOME ENERGY LEFT OVER FROM
THE FRONTAL TROUGH. A SIMILAR LOW LEVEL MOISTURE PATCH IS
BEGINNING TO AFFECT SW PUERTO RICO. ELSEWHERE MODERATE TRADES
AND FAIR WEATHER ARE DOMINATING. ALOFT...THE FLOW IS RATHER
ZONAL WITH A LARGE AMOUNT OF DRY STABLE AIR ...ESPECIALLY E OF
78W...KEEPING MOST OF THE MOISTURE PATCHES SHALLOW.

WESTERN ATLANTIC...
DEEP LAYER TROUGHING COVERS THE MAJORITY OF THE ATLC W OF 50W
EXTENDING SWD FROM A LARGE POLAR LOW. TWO COLD FRONTS ARE
ASSOCIATED WITH THE TROUGH. ONE OF THESE HAS BEEN IN THE AREA
FOR QUITE SOMETIME AND IS ANALYZED ALONG 32N48W 24N64W THEN
STATIONARY ACROSS THE SE BAHAMAS. BROKEN LOW AND MID LEVEL
CLOUDS AND EMBEDDED SHOWERS ARE WITHIN 120 NM ALONG AND AHEAD OF
THE COLD FRONT AND WITHIN 150 NM NW OF THE STATIONARY PART OF
THE BOUNDARY. A PREFRONTAL TROF LIES JUST E OF THE FRONT ALONG
25N55W 21N68W. THE SECONDARY AND WEAKER OF THE FRONTS EXTENDS
WSW FROM 32N54W TO 27N75W THEN NW TO 29N79W. A THIN ROPE CLOUD
HAS BEEN ASSOCIATED WITH THIS BOUNDARY BUT IS BECOMING RATHER
RAGGED. MODELS SHOW THE LAYERED TROUGH HOLDING ON THROUGH
MIDWEEK BEFORE PULLING NE TOWARD THE END OF THE WEEK. GFS IS
HINTING AT DEVELOPING A SFC TROUGH OR WEAK LOW IN THE BAHAMAS
LATE THU/FRI WHICH MAY PRODUCE SOME UNSETTLED WEATHER...ALONG
WITH A PROLONGED ELY SWELL EVENT FOR THE SE U.S. COAST.

EASTERN ATLANTIC...
A 1035 MB HIGH PRES SYSTEM LOCATED A FEW HUNDRED NM S OF THE
AZORES NEAR 34N24W IS DOMINATING THE SFC PATTERN ACROSS THE ATLC
E OF 45W. THIS HIGH IS PRODUCING MODERATE TO STRONG TRADES
ACROSS A GOOD PORTION OF THE DISCUSSION ZONE. THE MAIN FEATURE
IN THIS AREA IS IN THE MID TO UPPER LEVELS WHERE A FAIRLY
VIGOROUS LOW IS LOCATED NEAR 26N40W. DIFFLUENT ZONE TO THE E OF
THE UPPER LOW AND ASSOCIATED TROUGHING IS GENERATING A
FAIR AMOUNT OF MOISTURE FROM 10N-31N BETWEEN 25W-40W. MODELS
SHOW THE UPPER LOW MOVING NWD AND OPENING INTO A TROUGH THROUGH
TOMORROW. THIS WILL LIKELY REDUCE THE FETCH OF MOISTURE ACROSS
THE REGION AS UPPER RIDGING GAINS CONTROL.

$$
WILLIS




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