[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 121807
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON MAR 12 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 10N13W 3N25W 1N40W CROSSING THE EQ
NEAR 47W AND INTO NE BRAZIL NEAR 1S51W. FAIRLY ACTIVE CONVECTION
ALONG THE AXIS THIS AFTERNOON...WITH CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 150 NM OF THE
AXIS BETWEEN 22W-40W. ISOLATED TSTMS ARE WITHIN 180 NM OF AXIS W
OF 40W.

...DISCUSSION...

GULF OF MEXICO...
IMPRESSIVE SQUALL LINE MOVED OFF THE TEXAS COAST EARLIER THIS
MORNING. DOPPLER RADAR CURRENTLY SHOWS NUMEROUS HEAVY SHOWERS
AND TSTMS IN THE NW GULF N OF 26N W OF 93W. THIS ACTIVITY IS
ASSOCIATED WITH INSTABILITY AHEAD OF A COLD FRONT CURRENTLY
PUSHING THROUGH ERN TEXAS AND NE MEXICO. IN ADDITION TO THE SFC
FRONT...DEEP LAYER MOISTURE AND DIFFLUENCE AHEAD OF THE MID TO
UPPER LOW OVER WRN TEXAS IS SUPPORTING THE CONVECTION. OTHERWISE
THE UPPER FLOW OVER THE GULF IS SLIGHTLY ANTICYCLONIC AROUND
RIDGING. ELSEWHERE AT THE SFC...CONDITIONS ARE MORE TRANQUIL
WITH 10-20 KT E TO SE WINDS AROUND RIDGING EXTENDING INTO THE
AREA FROM THE NE. THE SW PORTION OF THE ATLC RIDGE WILL CONTINUE
TO DOMINATE MUCH OF THE GULF OVER THE NEXT COUPLE OF
DAYS...THOUGH SHOWERS AND TSTMS AHEAD OF THE SLOW MOVING MID TO
UPPER LOW OVER W TX WILL LINGER IN THE NW PORTION.

CARIBBEAN...
BROAD UPPER RIDGE COVERS MUCH OF THE CARIBBEAN EXCEPT FOR A
SMALL EMBEDDED TROUGH IN THE FAR SW PORTION...WHICH IS ADVECTING
A NARROW BAND OF HIGH CLOUDS/MOISTURE BETWEEN PANAMA AND SW
PUERTO RICO. SIMILAR MOISTURE IS BEING ADVECTED INTO THE FAR NW
PORTION/YUCATAN CHANNEL DOWNSTREAM FROM THE EPAC. VERY
DRY/STABLE AIR NOTED ELSEWHERE IN THIS AFTEROONS WV IMAGERY. AT
THE SFC...MODERATE TO FRESH TRADES DOMINATE EXCEPT FOR MORE
VARIABLE FLOW NEAR PUERTO RICO AND LEEWARD ISLANDS...AHEAD OF
THE FRONTAL TROUGH EXTENDING INTO THE MONA PASSAGE. WITH THE
TROUGH...BROKEN TO OVERCAST LOW AND MID CLOUDS WITH EMBEDDED
SHOWERS ARE AFFECTING WRN PUERTO RICO...THE MONA PASSAGE...ERN
HISPANIOLA AND THE ADJACENT WATERS. HIGH PRES OVER THE SE U.S.
AND W ATLC KEEP STRONG TRADES OVER THE CENTRAL AND WRN CARIBBEAN
THROUGH WED. THE SFC TROUGH THROUGH THE MONA PASSAGE WILL MOVE
SE AND EXTEND FROM 22N60W 18N63W TONIGHT AND TUE...22N57W 18N60W
WED...THEN E OF THE AREA THU.

ATLANTIC...
DEEP LAYERED TROUGH COVERS THE W ATLC FROM 55W-80W WITH THE
ASSOCIATED COLD FRONT EXTENDING INTO THE AREA ALONG 32N57W TO
24N61W THEN CONTINUING AS A SURFACE TROUGH TO THE MONA PASSAGE.
BROKEN/OVERCAST LOW AND CLOUDS WITH EMBEDDED SHOWERS ARE WITHIN
30 NM OF THE BOUNDARY. THE DEEPEST MOISTURE/POSSIBLE TSTMS ARE
MAINLY N OF 30N NOW BETWEEN 50W-55W...IN THE UPPER DIFLUENT ZONE
AHEAD OF THE UPPER TROUGH. A REINFORCING...DISSIPATING COLD
FRONT IS MOVING INTO THE AREA ALONG 30N BETWEEN 67W-77W. THIS
BOUNDARY IS MARKED BY A RAGGED AREA OF BROKEN LOW CLOUDS WITH
POSSIBLE ISOLATED SHOWERS WITHIN 30 NM. FAIR WEATHER AND
MODERATE TO STRONG TRADES CONTINUE TO DOMINATE MUCH OF THE E
ATLC E OF 45W...WITH THE SRN PERIPHERY OF STRONG SFC HIGH
PRESSURE DOMINATING. BROAD RIDGING GENERALLY DOMINATES THE UPPER
LEVELS OVER THE E ATLC TOO...EXCEPT FOR A WEAK UPPER TROUGH
EMBEDDED ALONG 41W N OF 17N. ANOTHER UPPER TROUGH IS OVER THE
FAR NE PORTION THAT HAS AN ASSOCIATED COLD FRONT JUST NORTH OF
THE AREA AND JUST NW OF MADEIRA ISLAND. SFC HIGH PRES WILL
DOMINATE THE WRN AND ERN ATLC THROUGH MID WEEK. CONFLUENCE
BETWEEN THESE TWO HIGHS WILL CONTINUE TO SUPPORT THE FRONTAL
TROUGH IN THE CENTRAL ATLC...WHICH IS FORECAST TO DRIFT SLOWLY E
OVER THE NEXT COUPLE OF DAYS.

$$
WILLIS






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