[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 190545
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N11W 5N20W 1N40W AND INTO SOUTH
AMERICA NEAR THE EQUATOR AT 49W. A CLUSTER OF MODERATE
CONVECTION IS WITHIN 150 NM N OF THE AXIS BETWEEN 21W-23W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 NM N
OF AXIS BETWEEN 25W-31W AND BETWEEN 34W-38W.

DISCUSSION...
GULF OF MEXICO...
A RIDGE...ANCHORED ON A 1030 MB HIGH LOCATED OVER THE CAROLINAS
DOMINATES THE ENTIRE GULF. LIGHT TO MODERATE E TO SE WINDS ARE
BLOWING ACROSS THE GULF WITH THE RETURN FLOW BRING 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 ABUNDANT UPPER-LEVEL
MOISTURE ACROSS THE AREA...PARTICULARLY N OF 26N. EXPECT THE
HIGH PRESSURE TO CONTINUE SHIFTING E OVER THE CAROLINAS WITH THE
NEXT COLD FRONT FORECAST TO ENTER THE REGION BY THE WEEKEND.
STRONG WINDS AND HIGH SEAS WILL BUILD IN THE GULF FOLLOWING THE
FRONTAL PASSAGE.

CARIBBEAN SEA...
A DISSIPATING SURFACE TROUGH REMAINS OVER THE CARIBBEAN FROM
CENTRAL CUBA NEAR 21N77W TO HONDURAS NEAR 15N86W. THIS TROUGH
WILL CONTINUE TO WEAKEN AS IT MOVES WESTWARD ACROSS BELIZE AND
THE YUCATAN PENINSULA. MOSTLY LOW CLOUDS WITH A FEW LIGHT
SHOWERS/DRIZZLE COVER THE CARIBBEAN WEST OF THE TROUGH WITH A
CLUSTER OF ENHANCED CONVECTION FROM 17N-19N BETWEEN 83W-84W.
SCATTERED MODERATE CONVECTION SUPPORTED BY UPPER LEVEL
DIFFLUENCE IS OVER THE WINDWARD ISLANDS E OF 63W. AN UPPER HIGH
CENTERED NEAR 14N77W IS CREATING STRONG SUBSIDENCE AND DRY
STABLE AIR BETWEEN 63W AND 82W. FRESH ELY TRADES WILL PERSIST
THROUGH THURSDAY.

ATLANTIC OCEAN...
FLOW AROUND THE SFC HIGH OVER THE CAROLINAS IS ADVECTING
STRATOCUMULUS CLOUDS OVER THE W ATLC. THE STRONG JET OVER THE
NORTHERN PORTION OF THE GULF OF MEXICO EXTENDS ACROSS NORTHERN
FLORIDA AND INTO THE W ATLC TRANSPORTING UPPER LEVEL MOISTURE TO
THE AREA N OF 26N. FARTHER EAST... A COLD FRONT ENTERS THE
REGION NEAR 32N54W AND STRETCHES SW TO 24N69W THEN CONTINUES AS
A SFC TROUGH ACROSS THE BAHAMAS AND CENTRAL CUBA INTO THE
CARIBBEAN. A 120 NM WIDE BAND OF LOW LEVEL MOISTURE SURROUNDS
THE FRONT. A STRONGER BAND OF CONVECTION WITH EMBEDDED ISOLATED
SHOWERS/ THUNDERSTORMS EXTENDS UP TO 200 NM AHEAD OF THE FRONT N
OF 25N. A DEEP LAYERED TROUGH OVER THE W AND CENTRAL ATLC
SUPPORTS THIS FRONT. THE EXTENT OF THIS CONVECTION IS LIMITED
DUE TO STRONG SUBSIDENCE AROUND AN UPPER HIGH CENTERED NEAR
26N40W. A CUTOFF 992 MB SFC LOW IS OVER THE E ATLC WITH AN
ASSOCIATED COLD FRONT EXTENDING ACROSS THE CANARY ISLANDS TO
21N29W THEN CONTINUES MAINLY WESTWARD AS A DISSIPATING FRONT TO
23N47W WHERE IT BECOMES STATIONARY TO 28N50W. A BAND OF BROKEN
LOW CLOUDS DEFINES THE FRONTAL BOUNDARY ON SATELLITE PHOTOS WITH
STRATOCUMULUS CLOUDS MOVING IN BEHIND THE FRONT. A WEAKENING
1026 MB HIGH IS BETWEEN THE ABOVE MENTIONED FRONTS NEAR 31N41W
DOMINATING THE CENTRAL ATLC. UPPER WESTERLY ZONAL FLOW COVERS
THE TROPICS WITH A WEAK JETSTREAM BRANCH EXTENDING WEST TO EAST
ALONG 15N-16N.

$$
GR/RJW









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