[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 231740
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN DEC 23 2007

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N11W 4N25W 4N35W...EQUATOR AT 50W
INTO SOUTH AMERICA. WIDELY SCATTERED MODERATE CONVECTION IS
WITHIN 150 NM N OF THE AXIS BETWEEN 30W-50W AND WITHIN 90 NM S
OF THE AXIS BETWEEN 29W-38W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS ALONG THE EQUATOR BETWEEN THE PRIME MERIDIAN AND
8W.

...DISCUSSION...

THE GULF OF MEXICO...
A STRONG COLD FRONT IS MOVING ACROSS THE GULF THIS AFTERNOON. AS
OF 1500 UTC...THIS FEATURE STRETCHES FROM THE FLORIDA PANHANDLE
ACROSS THE CENTRAL GULF NEAR 24N90W TO THE BAY OF CAMPECHE AND
SOUTH MEXICO. GALE FORCE WINDS OF 30 TO 35 KT ARE BLOWING BEHIND
THE FRONT. AS A RESULT...A GALE WARNING HAS BEEN POSTED S OF 28N
AND WEST OF THE FRONT WITH SEAS BUILDING UP TO 12 FT. A QUIKSCAT
PASS FROM THIS MORNING CONFIRMED THESE STRONG WINDS. A WELL
DEFINED LINE OF CONVECTION MARKS THE FRONTAL BOUNDARY WITH
BROKEN TO OVERCAST COLD AIR STRATOCUMULUS CLOUDS BEHIND THE
FRONT. A DEEP LAYERED TROUGH OVER THE CENTRAL PLAINS SUPPORTS
THE FRONT WITH A MID/UPPER-LEVEL RIDGE DOMINATING THE ENTIRE
GULF. AHEAD OF THE FRONT A WARM AND HUMID AIRMASS REMAINS IN
PLACE. THE COLD FRONT WILL EXTEND FROM THE CENTRAL FLORIDA
PENINSULA TO THE YUCATAN CHANNEL LATE TONIGHT AND EXIT THE GULF
ON MONDAY. HIGH PRESSURE WILL BUILD OVER THE ENTIRE GULF MONDAY
AND TUESDAY USHERING A COOL AND DRY AIRMASS.

THE CARIBBEAN SEA...
A MID/UPPER RIDGE CONTROLS THE ENTIRE BASIN. AT MID LEVEL...
IT IS ANCHORED ON A HIGH OVER CENTRAL CUBA. SWLY WINDS ON THE
WESTERN PERIPHERY OF THE UPPER RIDGE ARE TRANSPORTING UPPER
LEVEL MOISTURE FROM THE EPAC ACROSS PANAMA/COSTA RICA INTO THE
SW CARIBBEAN. THESE WINDS...PAIRED WITH THE CLOSE PROXIMITY OF
THE EPAC ITCZ ARE ENHANCING MODERATE TO STRONG CONVECTION OVER
THE AREA...BUT PARTICULARLY OVER E PANAMA. STRONG SUBSIDENCE IS
NOTED OVER THE REMAINDER OF THE SEA PROVIDING NICE WEATHER
CONDITIONS. A WEAK SFC TROUGH IS OVER THE CENTRAL CARIBBEAN
ALONG 72W SOUTH OF 15N GENERATING SOME SHOWER ACTIVITY OVER
WESTERN VENEZUELA...INCLUDING THE AREA OF LAKE MARACAIBO. LIGHT
TO MODERATE TRADE WINDS ARE OVER THE CARIBBEAN WITH THE
STRONGEST WINDS JUST N OF THE COLOMBIAN COAST.

THE ATLANTIC OCEAN...
MAIN FEATURE IN THE W ATLC IS A 1011 MB DEVELOPING GALE CENTER
LOCATED NEAR 27N69W AT 23/1200 UTC. THIS LOW IS FORECAST TO MOVE
SE AND SLIGHTLY WEAKEN. A MID/UPPER-LEVEL TROUGH ALONG 62W/63W N
OF 16N SUPPORTS THIS LOW THAT HAS A TROUGH HANGING WSW ACROSS
THE CENTRAL BAHAMAS. MOST OF THE DEEP CLOUDINESS...SCATTERED
SHOWERS AND TSTMS ARE SITUATED TO THE E OF THE CENTER IN AN
UPPER DIFFLUENT ZONE FROM 22N-32N BETWEEN 52W-61W. THE ATTACHED
COLD FRONT EXTENDS FROM 28N65W TO 21N68W. A WARM FRONT ALSO
EXTENDS FROM THE LOW TO 27N56W. AT THIS POINT...A SFC TROUGH
CONTINUES MAINLY EWD AND CONNECTS WITH A COLD FRONT N OF AREA.
VIS SATELLITE IMAGERY SHOWS DISTINCT TURNING IN THE LOW-LEVEL
CLOUDS ASSOCIATED WITH THE LOW. ANOTHER SWIRL OF LOW CLOUDS IS
NEAR 27N72W...JUST E OF THE BAHAMAS. AN AREA OF SHOWERS WITH
EMBEDDED TSTMS HAS DEVELOPED NE OF THE LEEWARD ISLANDS NEAR
20N57W. UPPER DIFFLUENCE ASSOCIATED WITH THE ABOVE MENTIONED
TROUGH IS HELPING TO INDUCE THIS ACTIVITY.  THE E ATLC IS QUIET
UNDER THE INFLUENCE OF A SFC HIGH PRES AND ZONAL FLOW ALOFT
DOMINATING THE WX PATTERN. THIS IS PRODUCING PATCHES OF LOW/MID
CLOUD WITH MAINLY LIGHT SHOWERS...AND MODERATE NE TO E TRADES.

$$
GR



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