[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191140
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST WED DEC 19 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N11W 5N25W 3N35W AND INTO SOUTH
AMERICA NEAR THE EQUATOR AT 48W. CLUSTERS OF MODERATE TO STRONG
CONVECTION ARE WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN
19W-23W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN
100 NM N OF THE AXIS BETWEEN 25W-31W. SCATTERED MODERATE
CONVECTION IS BETWEEN 32W-38W FROM 2N-4N.

DISCUSSION...
GULF OF MEXICO...
A RIDGE...ANCHORED ON A 1030 MB HIGH LOCATED OFF THE CAROLINA
COAST EXTENDS ACROSS THE ENTIRE GULF REGION. LIGHT TO MODERATE
WINDS ARE FLOWING AROUND THE RIDGE WITH THE RETURN FLOW BRINGING
INCREASED MOISTURE TO THE W GULF. ALOFT...STRONG ZONAL FLOW
DOMINATES THE REGION. A SUBTROPICAL JETSTREAM WITH CORE WINDS
NEAR 120 KT CROSSES THE N GULF WATERS TRANSPORTING UPPER-LEVEL
MOISTURE ACROSS THE AREA AND INTO THE W ATLC. THE NEXT COLD
FRONT IS FORECAST TO ENTER THE REGION THIS WEEKEND. STRONG WINDS
AND HIGH SEAS WILL BUILD IN THE GULF FOLLOWING THE FRONTAL
PASSAGE.

CARIBBEAN SEA...
A SFC TROUGH CONTINUES TO WEAKEN AS IT MOVES WEST ACROSS THE
CARIBBEAN. AS OF 09Z...THE TROUGH WAS ANALYZED AS CROSSING
CENTRAL CUBA AND ENTERING THE CARIBBEAN NEAR 21N78W THEN
STRETCHING SW TO 16N87W. MOST OF THE CONVECTIVE ACTIVITY
ASSOCIATED WITH THE TROUGH HAS DIMINISHED EXCEPT FOR A SMALL
CLUSTER OF MODERATE CONVECTION BETWEEN 18N-19N AND 83W-84W.
OTHERWISE THE WESTERN CARIBBEAN IS MARKED BY OVERCAST LOW CLOUDS.
SCATTERED MODERATE CONVECTION SUPPORTED BY UPPER LEVEL
DIFFLUENCE IS OVER THE WINDWARD ISLANDS E OF 62W. AN UPPER HIGH
CENTERED NEAR 13N75W IS CREATING STRONG SUBSIDENCE AND DRY
STABLE AIR BETWEEN 64W AND THE CENTRAL AMERICAN COASTLINE.
FRESH ELY TRADES WILL PERSIST THROUGH THURSDAY.

ATLANTIC OCEAN...
FLOW AROUND THE SFC HIGH OFF THE CAROLINA COAST CONTINUES TO
ADVECT STRATOCUMULUS CLOUDS OVER THE W ATLC. UPPER-LEVEL
MOISTURE IS BEING PUSHED OUT OVER THE W ATLC BY THE JET MAXIMA
OVER THE GULF OF MEXICO. FARTHER EAST...A COLD FRONT ENTERS THE
REGION NEAR 31N54W AND STRETCHES SW TO 27N64W WHERE IT BECOMES
STATIONARY TO 24N72W. AT THIS POINT THE FRONT CONNECTS TO THE
SFC TROUGH THAT EXTENDS ACROSS THE BAHAMAS AND CENTRAL CUBA INTO
THE CARIBBEAN. A BROKEN BAND OF LOW LEVEL MOISTURE SURROUNDS THE
FRONT. STRONGER CONVECTION WITH EMBEDDED SHOWERS AND
THUNDERSTORMS IS DEPICTED AS A PREFRONTAL TROUGH THAT EXTENDS
FROM 31N54W TO 25N59W. THE FRONT CONTINUES TO BE SUPPORTED BY A
DEEP LAYERED TROUGH OVER THE CENTRAL ATLC. STRONG SUBSIDENCE
AROUND AN UPPER-LEVEL HIGH CENTERED NEAR 25N38W IS CAUSING A
BAND OF DRY STABLE AIR TO BE WEDGED BETWEEN THE TROUGH AND A
WEAK SFC HIGH TO THE NE NEAR 32N39W. A DEEP-LAYERED TROUGH IS
OVER THE E ATLC  WITH AN ASSOCIATED COLD FRONT EXTENDING BETWEEN
THE CANARY ISLANDS AND THE AFRICAN COAST TO 20N23W WHERE IT
TURNS WESTWARD AND STARTS TO DISSIPATE ALONG 19N30W 20N40W
BECOMING STATIONARY FROM 21N43W TO 28N50W. SATELLITE IMAGERY
SHOWS STRATOCUMULUS CLOUDS MOVING IN BEHIND THE FRONT. UPPER
WESTERLY ZONAL FLOW COVERS THE TROPICS WITH A WEAK JETSTREAM
BRANCH EXTENDING WEST TO EAST ALONG 15N-16N.

$$
WADDINGTON











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