[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 190003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI JAN 18 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 8N13W 4N20W 1N30W EQ40W 1S48W.
CLUSTERS OF SCATTERED MODERATE CONVECTION LIE NORTH OF THE ITCZ
FROM 1N-4N BETWEEN 25W-40W.

...DISCUSSION...

GULF OF MEXICO...
A VIGOROUS SRN STREAM SHORTWAVE IMPULSE ROTATING THROUGH A
LARGER-SCALE TROUGH OVER THE W CNTRL CONUS IS CAUSING THE
DEVELOPMENT OF A BROAD AREA OF SFC LOW PRESSURE OVER THE WRN
GULF OF MEXICO. AS OF 2100 UTC...THE BROAD 1008 MB SFC LOW IS
LOCATED NEAR 25N95W OVER THE W CNTRL GULF OF MEXICO AND IS
SLOWLY RIDING N/NE WHILE DRAGGING THE POLAR FRONT WITH IT.  THE
POLAR FRONT EXTENDS EAST OF THE SFC LOW TO 24N90W 25N85W TO A
PSN SOUTH OF LAKE OKEECHOBEE AND THEN N OF THE NWRN BAHAMAS.
A MODERATELY STRONG S TO SELY FLOW FROM THE NW CARIBBEAN AND
SERN GULF IS DRAWING COPIOUS MOISTURE TO THE FRONT...RESULTING
IN A WELL-DEFINED OVERRUNNING PCPN PATTERN OVER THE NWRN AND NOW
CNTRL GULF OF MEXICO. IN FACT...STRONG UPPER-LEVEL DIVERGENCE
AND POTENTIAL VORTICITY ADVECTION ACTING ON PRECIPITABLE WATER
VALUES IN EXCESS OF 1.5 INCHES OVER THE WRN AND CNTRL GULF OF
MEXICO ARE CREATING A LARGE SHIELD OF LGT/MDT PCPN IN THE COLD
SECTOR N AND W OF THE SFC LOW.  IN ADDITION...SATELLITE AND
RADAR TRENDS INDICATE A RAPIDLY EXPANDING AREA OF CONVECTION
WITHIN ABOUT 150 NM NE OF THE SFC WAVE AND N OF THE ASSOCIATED
WARM FRONT.  MODELS SUGGEST THAT THE SFC WAVE HAS THE POTENTIAL
TO DEVELOP INTO A GALE CTR AS IT TRACKS RAPIDLY ENE THROUGH THE
N CNTRL/NERN GULF OF MEXICO SAT MORNING AND AFTERNOON...BEFORE
REFORMING OFF THE SE CONUS SAT NIGHT. AS THIS OCCURS...THE POLAR
FRONT SHOULD AGAIN SWEEP THROUGH MOST OF THE GULF BY SUN
MORNING...WITH STG SFC HIGH PRESSURE FORECAST TO BUILD INTO THE
WRN/CNTRL GULF IN THE WAKE OF THE GALE BY SAT NIGHT.  THIS
SHOULD LEAD TO A STG NLY FLOW OF 2O TO POSSIBLY 40 KTS FROM THE
NWRN GULF COAST THROUGH THE BAY OF CAMPECHE.

CARIBBEAN SEA...
A STRONG MID TO UPPER LEVEL ANTICYCLONE REMAINS ANCHORED ACROSS
SRN COLOMBIA...WITH A RIDGE AXIS EXTENDING NWD ROUGHLY ALONG 75W
INTO THE CARIBBEAN BASIN.  STRONG SUBSIDENCE AND A RELATIVELY
HIGH ATMOSPHERIC STABILITY ASSOCIATED WITH THIS FEATURE
CONTINUES TO HOLD SWAY ACROSS MOST OF THE AREA ...ESPECIALLY
FROM THE SOUTHWESTERN THROUGH THE SOUTHEASTERN CARIBBEAN SEA.
DESPITE THE HIGH ATMOSPHERIC STABILITY ALOFT...A MODERATE TO
OCCASIONALLY STRONG TRADE WIND FLOW AND STRONG SHEAR OF THE
LOW-LEVEL WIND CONTINUES TO GENERATE VARIABLE CLOUDINESS AND
STREAKS OF SHOWERS FROM THE E CNTRL THROUGH THE W CNTRL
CARIBBEAN SEA.  THE MOST CONCENTRATED ACTIVITY HAS BEEN
OCCURRING IN THE VICINITY OF PUERTO RICO AND HISPANIOLA LATE
THIS AFTERNOON ...WITH MORE WIDELY SCATTERED ACTIVITY ELSEWHERE
ACROSS THE AREA. A QUIKSCAT PASS INDICATES THE STRONG WINDS LIE
FROM THE NRN COLOMBIA COAST TO ABOUT 14N BETWEEN 72W-78W.  OTHER
LESS DEFINED BANDS OF CLOUDS AND OCCASIONAL SHOWERS CONTINUE TO
AFFECT PARTS OF THE WRN AND NWRN CARIBBEAN...LIKELY RELATED TO
SHEAR OF THE LOW-LEVEL WIND AND SPEED CONVERGENCE.  GOING
FORWAR... MODEL GUIDANCE INDICATES THAT THE POLAR FRONT...
CURRENTLY OVER THE GULF OF MEXICO ...SHOULD DESCEND INTO THE
EXTREME NWRN CARIBBEAN BY SUN MORNING ...ACCOMPANIED BY STRONG N
TO NE WINDS OF UP TO 30 KTS AND BUILDING SEAS.  AS THIS
OCCURS...WINDS AHEAD OF THE FRONT SHOULD SLACKEN QUITE A BIT
OVER THE REMAINDER OF THE NWRN CARIBBEAN.  HOWEVER...AS BROAD
SFC HIGH PRESSURE OVER THE CNTRL ATLANTIC WILL BEGIN DRIFTING
EWD THROUGH THE PD...A STRONG EARLY FLOW SHOULD CONTINUE TO
PREVAIL FROM THE E CNTRL TO THE W CNTRL CARIBBEAN...AS STRONG OR
PERHAPS STRONGER THAN THE CURRENT REGIME.

ATLANTIC OCEAN...
A COLD FRONT EXTENDING ALONG A LINE FROM 30N75W 29N77W CONTINUES
MOVING SLOWLY E AND SE...WHILE THE WRN END REMAINS STATIONARY
FROM 29N77W TO JUST N OF FT PIERCE FL AND SWWD TO N OF NAPLES
FL. SCATTERED TO BROKEN CLOUDINESS AS WELL AS A FEW SHOWERS ARE
LOCATED WITHIN 90NM NW THIS FEATURE. ANOTHER COLD FRONT EXTENDS
ACROSS THE CNTRL ATLANTIC FROM 32N34W 24N45W 2160W...WITH A 1026
MB SFC HIGH NEAR 32N60W BUILDING IN BEHIND IT.  THE FRONT IS
DEFINED BY A BAND OF MOSTLY SCATTERED LOW CLOUDS SW OF
27N35W...WHILE MORE CONCENTRATED CLOUDS AND A FEW SHOWERS
ACCOMPANY THE NRN END THROUGH 32N34W.  TO THE EAST...A 1033 MB
HIGH LOCATED OVER PORTUGAL AND WRN SPAIN DOMINATES THE NE
ATLANTIC...AHEAD OF THE ABOVE MENTIONED FRONT....WITH A RIDGE
AXIS EXTENDING AS FAR S AND W AS 27N25W.  MEANWHILE...AT UPPER
LEVELS...RIDGING FROM THE WRN CARIBBEAN BUBBLES NWD THROUGH THE
SWRN ATLANTIC...WHILE A BROAD LONGWAVE TROUGH COVERS THE
REMAINDER OF THE ATL E OF ABOUT 65W.  IN THE BASE OF THE ABOVE
LONGWAVE TROUGH...A STRONG 70-90KT JET CONTINUES TO TRANSPORT
CONSIDERABLE UPPER-LEVEL MOISTURE/HIGH CLOUDS FROM NORTHERN
SOUTH AMERICA NE TO THE NWRN COAST OF AFRICA.  LOOKING
AHEAD...MODELS DRIVE THE COLD FRONT CURRENTLY OVER THE SWRN ATL
THROUGH THE BAHAMAS AND INTO THE NRN CARIBBEAN BY SUN NIGHT
...FOLLOWED BY A STRONG AND COLD SFC RIDGE BUILDING IN BEHIND IT
OVER THE ERN CONUS.  EXPECT A GENERALLY NE FLOW OF 20-30 KTS TO
COVER THE AREA W OF 70W TO THE COAST OF FL SUN AFTERNOON AND
EVENING.

$$
KIMBERLAIN




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