[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED NOV 15 2006

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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1745 UTC.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 47W SOUTH OF 14N
MOVING WEST 10 TO 15 KT. THIS WAVE CONTINUES TO EXHIBIT A BROAD
INVERTED V PATTERN. SCATTERED MODERATE CONVECTION IS FROM
10N-15N BETWEEN 41W-47W. THE ASSOCIATED CLOUD TOPS ARE BEING
STRETCHED TO THE NE WITH UPPER SW FLOW AROUND A RIDGE JUST E OF
THE AREA.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 59W SOUTH OF 15N
MOVING WEST NEAR 15 KT. VERY SMALL AREA OF CYCLONIC TURNING
NOTED IN THE LOW CLOUD FIELD JUST S OF BARBADOS...THOUGH ANOTHER
NOTED FURTHER SE NEAR 11N55W WHICH MADE THE WAVE PLACEMENT
DIFFICULT. REGARDLESS...DEEP CONVECTION IS MINIMAL WITHIN 200NM
EITHER SIDE OF THE AXIS.

A CENTRAL CARIBBEAN SEA TROPICAL WAVE IS ALONG 76W SOUTH OF 16N
MOVING WEST 10 TO 15 KT. WAS TEMPTED TO REMOVE THIS WAVE AS THE
CYCLONIC TURNING NOTED IN THE CENTRAL CARIBBEAN SEEMS MORE
RELATED TO NATURAL VARIATIONS IN THE TRADE FLOW AROUND THE
ADJACENT OROGRAPHY. HOWEVER...COULD MAKE OUT SOME SORT OF
WESTWARD PROPAGATING PERTURBATION IN THE GOES-E HOVMOLLER
DIAGRAM THROUGH S AMERICA SO DECIDED TO KEEP THE FEATURE.
SCATTERED MODERATE NOW FROM 9N-13N BETWEEN 75W-78W.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 9N13W 5N25W 11N45W 12N57W. ASIDE
FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVE ALONG 47W...SCATTERED MODERATE FROM 5N-9N BETWEEN 31W-36W.
ISOLATED SHOWERS/TSTMS NOTED ELSEWHERE WITHIN 100NM EITHER SIDE
OF THE AXIS.

...DISCUSSION...
THE GULF OF MEXICO...
MAIN FEATURE IN THE GULF IS THE STRONG FRONTAL SYSTEM THAT HAS
PUSHED INTO THE NW PORTION. AS OF 1500 UTC...THE COLD FRONT
EXTENDS FROM MARSH ISLAND OFF THE CENTRAL LOUISIANA COAST TO
JUST NORTH OF TAMPICO MEXICO. A SQUALL LINE ASSOCIATED WITH THE
FRONT IS PRODUCING HEAVY SHOWERS/TSTMS NEAR THE BOUNDARY.
ISOLATED CELLS ALSO NOTED IN THE WARM SECTOR AHEAD OF THE
FRONT...STREAMING NNE...N OF 25N BETWEEN THE FRONT AND 83W. THE
FRONT AND ASSOCIATED CONVECTION WILL CONTINUE MOVING E/SE OVER
THE NEXT 24HRS...WITH THE FRONT EXPECTED TO MOVE INTO THE FAR SE
GULF BY TOMORROW AFTERNOON. A GALE WARNING IS IN EFFECT FOR BOTH
PREFRONTAL AND POSTFRONTAL WINDS...SEE MIAOFFNT4 AND MIAHSFAT2
FOR DETAILS. FRONTAL SYSTEM IS ASSOCIATED WITH DEEP LAYER TROUGH
EXTENDING S THROUGH OKLAHOMA AND TEXAS...AND IS ADVECTING VERY
DRY AIR INTO THE FAR NW GULF BEHIND THE FRONT. UPPER RIDGE IS E
OF THE TROF EXTENDING THROUGH THE FAR ERN GULF.

THE CARIBBEAN SEA...
NEARLY ZONAL MID TO UPPER FLOW FOUND ACROSS THE CARIBBEAN N OF
13N...BUT HAS A SLIGHT ANTICYCLONIC CURVATURE WITH A HIGH ORIGIN
SOMEWHERE JUST W OF NRN COLOMBIA. THIS IS ENHANCING THE
CONVECTION DESCRIBED WITH THE TROPICAL WAVE ALONG 76W. AT THE
SFC...TRADES ARE FAIRLY LIGHT WITH A WEAK PRESSURE GRADIENT IN
TACT. LIGHT TO MODERATE TRADES TO PERSIST THROUGH THE END OF THE
WORKWEEK...WHILE A COLD FRONT MOVES INTO THE NW CARIBBEAN ON THU
THEN STALLS FROM CENTRAL CUBA TO THE GULF OF HONDURAS ON FRI.

THE ATLANTIC OCEAN...
THE STATIONARY FRONT THAT EXTENDED THROUGH THE SW NORTH ATLC THE
LAST FEW DAYS HAS DISSIPATED...WITH THE STRONG 1036 MB HIGH JUST
SE OF NEWFOUNDLAND HAVEN BUSTED THROUGH. UPPER RIDGING AND
PLENTIFUL DRY AIR ALSO NOTED IN THE SW NORTH ATLC N OF 23N AND W
OF 65W...WITH HIGH CLOUDS AND UPPER MOISTURE NOTED JUST S AND E
OF THIS BOUNDARY. NEXT INTERESTING FEATURE IS THE
BROAD...WEAKENING DEEP LAYER LOW NEAR 30N45W THAT HAS A 1011 MB
SFC LOW NEAR 29N49W. DEEP CONVECTION REMAINS MINIMAL ANYWHERE
NEAR THIS LOW. HOWEVER...AS THIS SYSTEM CONTINUES TO INTERACT
WITH THE STRONG BLOCKING HIGH TO ITS NORTH NEAR
NEWFOUNDLAND...IT WILL SEND A SMALL TO MODERATE ENE SWELL TO
EXPOSED FLORIDA AND BAHAMA BEACHES LATER THIS WEEK. SFC TROUGH
ASSOCIATED WITH THIS SYSTEM EXTENDS FROM THE LOW TO 26N47W
22N54W...MARKED BY WEAK LOW LEVEL CONFLUENCE AND A RAGGED LINE
OF LOW TO MID CLOUDS WITHIN 150 NM. PRONOUNCED UPPER RIDGING
EXTENDS THROUGH THE E ATLC ALONG 31W...THAT HAS ABUNDANT MID TO
UPPER MOISTURE STREAMING AROUND IT BETWEEN AFRICA AND 48W...THAT
LIKELY HAS ISOLATED EMBEDDED SHOWERS. SFC HIGH PRESSURE ALSO
DOMINATING THE E ATLC WITH A 1019MB CENTER NEAR
26N28W...FORECAST TO DISSIPATE IN 24HRS AS A MORE SIGNIFICANT
HIGH TAKES OVER FROM THE NNW.

$$
WILLIS




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