[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161737
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN DEC 16 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 4N19W 2N35W 1N45W EQUATOR50W.
SCATTERED MODERATE CONVECTION IS WITHIN 240 NM S OF THE AXIS
BETWEEN 40W-46W.

DISCUSSION...
GULF OF MEXICO...
STRONG FAST MOVING COLD FRONT HAS JUST ABOUT CLEARED MOST OF THE
REGION. AS OF 15 UTC...THE BOUNDARY EXTENDED FROM NEAR NAPLES
FLORIDA TO CANCUN MEXICO THEN ACROSS THE EXTREME SRN BAY OF
CAMPECHE AND STATIONARY ALONG THE SLOPES OF THE SIERRA MADRE
MOUNTAINS IN MEXICO S OF 23N. N TO NW WINDS ARE BLOWING STRONG
BEHIND THE FRONT...TO GALE FORCE IN THE SW GULF AS NOTED IN A
RECENT QSCAT PASS. WIDESPREAD BROKEN STRATOCUMULUS CLOUDS EXIST
BEHIND THE FRONT...INDICATIVE OF THE COOL STABLE AIRMASS IN
PLACE. CURRENT TEMPS ARE AS COLD AS THE LOW 40'S F ACROSS THE N
GULF COAST AND AS WARM AS THE LOW 80'S F AHEAD OF THE FRONT IN
SE FLORIDA. SHOWERS AND TSTMS ARE MOSTLY AHEAD OF THE FRONT OVER
PORTIONS OF SE FLORIDA...THE STRAITS AND THE ADJACENT ATLC
WATERS. WINDS ARE EXPECTED TO FALL BELOW GALE FORCE WITHIN THE
NEXT 18 HOURS AS THE FRONT SLIDES FURTHER E ALLOWING THE PRES
GRADIENT TO SLACKEN. COOL AND DRY WEATHER IS EXPECTED TO BE THE
RULE FOR THE ENTIRE REGION THRU TOMORROW.

CARIBBEAN SEA...
LOW-LEVEL CONVERGENCE ALONG A PRE-FRONTAL TROUGH EXTENDING FROM
WRN CUBA TO HONDURAS AND A FAST MOVING STRONG COLD FRONT IN THE
YUCATAN CHANNEL IS GENERATING SCATTERED SHOWERS AND TSTMS WITHIN
30 NM OF THE TROUGH LINE AND ELSEWHERE N OF 19N BETWEEN 80W-85W.
THE REMAINDER OF THE REGION IS EXPERIENCING FAIRLY TRANQUIL
WEATHER WITH THE EXCEPTION OF QUICK MOVING SCATTERED SHOWERS
DRIVEN BY STRONG ELY TRADES...ESPECIALLY E OF 75W. THE MID AND
UPPER LEVEL PATTERN CONSISTS OF A RIDGE ABOVE THE WRN HALF
SUPPORTED BY AN ANTICYCLONE NEAR 18N84W AND A TROUGH OVER THE
ERN HALF. THIS PATTERN IS CREATING LITTLE SIGNIFICANT UPPER
MOISTURE AND IS ACTUALLY LEADING TO STRONG SUBSIDENCE N OF 17N E
OF 72W...WHICH IS LIKELY CAPPING THE LOW-LEVEL SHOWER ACTIVITY.

ATLANTIC OCEAN...
LINES OF SHOWERS AND TSTMS ARE SCATTERED ACROSS THE FAR WRN
PORTION OF THE AREA...W OF 75W...ASSOCIATED WITH THE STRONG COLD
FRONT PUSHING ACROSS THE STATE OF FLORIDA. S TO SW WINDS ARE
BLOWING TO GALE FORCE AHEAD OF THE APPROACHING FRONT N OF 28N W
OF 68W. LIGHTNING DATA REVEALS THE STRONGEST TSTMS IN THE FLA
STRAITS AND N OF THE AREA OFF THE CAROLINA COASTLINE. VERTICALLY
STACKED RIDGING DOMINATES THE AREA E OF THE FRONT TO ABOUT 50W.
THE SFC CENTER...ANALYZED 1024 MB NEAR 29N55W...IS TIGHTENING
THE PRES PATTERN ACROSS THE TROPICS GENERATING ELY TRADES IN THE
20-25 KT RANGE S OF 23N BETWEEN ABOUT 35W-70W. THESE STIFF WINDS
ARE CARRYING PATCHES OF LOW TO MID LEVEL CLOUDINESS...BUT NONE
OF THIS IS ACQUIRING MUCH VERTICAL DEPTH SUPPRESSED BY THE
STABLE MID AND UPPER LEVEL ENVIRONMENT.

LONGWAVE MID AND UPPER LEVEL TROUGHING DOMINATES THE FLOW ALOFT
E OF ABOUT 50W. A SERIES OF SHORTWAVES ADD TO THE COMPLEXITY OF
THE PATTERN AND ARE HELPING TO SUSTAIN THE LARGE SCALE TROUGH.
THESE SHORTWAVES HAVE A FEW SFC CONNECTIONS...TWO OF WHICH ARE
WEAK FRONTAL BOUNDARIES THAT CURRENTLY LIE JUST N OF THE AREA.
THE OTHER IS A SFC TROUGH ANALYZED FROM 32N15W ACROSS THE WRN
CANARY ISLANDS TO 22N22W. VIS IMAGES SHOW A SMALL SWIRL...WEAK
LOW...ALONG THE TROUGH AXIS NEAR 25N21W. THIS FEATURE IS ONLY
GENERATING CLOUDINESS AND POSSIBLE EMBEDDED ISOLATED SHOWERS
WITHIN 90 NM OF THE CENTER. THE COMBINATION OF THE FRONTS AND
SFC TROUGH HAS WEAKENED THE OVERALL PRES PATTERN WHICH HAS
ALLOWED THE SFC WINDS TO BE LIGHT TO MODERATE E OF 30W. AN UPPER
WLY JET...WITH CORE WINDS NEAR 90 KT OVER THE ATLC WATERS...LIES
OVER THE TROPICS EXTENDING FROM 13N46W 18N23W 20N16W. DIFFLUENCE
TO THE S/SE OF THE JET IS GENERATING ABUNDANT CLOUDINESS AND
EMBEDDED SCATTERED SHOWERS WITHIN 300 NM.

$$
CANGIALOSI


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