[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182338
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST MON DEC 18 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...
CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...
NORTHEASTERN 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...
ITCZ AXIS IS ALONG 6N10W 4N20W 4N30W 2N52W. PATCHES OF SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION ARE FROM 2N-6N BETWEEN
32N-45W.

...DISCUSSION...
THE GULF OF MEXICO...
A SHORTWAVE TROUGH IS OVER THE WESTERN GULF ALONG 91/92W NORTH
OF 20N. THIS TROUGH IS BETTER DEFINED NORTH OF 25N AND EXTENDS
TO A SMALL CYCLONIC CIRCULATION NOW LOCATED OVER MISSISSIPPI.
ISOLATED SHOWERS ARE AHEAD OF THIS FEATURE... WHICH IS MOVING
RAPIDLY EWD. A MID/UPPER RIDGE DOMINATES THE REMAINDER OF THE
GULF. AT THE SFC...A 1026 MB SFC HIGH PRES OVER THE SE U.S.
EXTENDS A RIDGE OVER THE ENTIRE GULF HELPING TO PRODUCE MOSTLY
FAIR WEATHER ACROSS THE REGION. ONLY PATCHES OF MAINLY LOW
CLOUDS ARE SEEN OVER THE AREA. THIS SYSTEM WILL BE REINFORCED BY
ANOTHER AREA OF HIGH PRES MOVING EWD ACROSS THE CENTRAL CONUS
TUE NIGHT GENERATING AN INCREASE IN WINDS AND SEAS OVER THE
GULF. THE NEXT COLD FRONT IS EXPECTED TO MOVE OFF THE TEXAS
COAST ON THURSDAY BRINGING SOME SHOWER/TSTM ACTIVITY TO THE NW
CORNER OF THE GULF. DOPPLER RADAR IS STILL SHOWING SOME SHOWERS
AND ISOLATED TSTMS OVER SOUTH FLORIDA AND THE KEYS.

THE CARIBBEAN SEA...
A RIDGE/TROUGH/RIDGE PATTERN COVERS THE CARIBBEAN SEA. AN UPPER
TROUGH EXTENDS ACROSS EASTERN BAHAMAS/CUBA INTO THE CARIBBEAN
THROUGH JAMAICA. UPPER DIFFLUENCE DOMINATES THE EASTERN PORTION
OF THE BASIN ENHANCING THE DEVELOPMENT OF A CLUSTER OF MODERATE
TO ISOLATED STRONG CONVECTION LOCATED NEAR 16N67W. VERY DRY AIR
ALOFT IS OVER THE BASIN WEST OF 70W. PATCHES OF LOW CLOUDS WITH
EMBEDDED SHOWERS ARE MOVING OVER CENTRAL AMERICA UNDER A NELY
WIND FLOW. TRADE WINDS ARE MOSTLY IN THE 15-20 KT RANGE AND
LITTLE CHANGE OR SOME RELAXING IS EXPECTED OVER THE NEXT FEW
DAYS. WINDS ARE FORECAST TO INCREASE AGAIN OVER THE FAR NW
CARIBBEAN LATE WED AND NE OF PUERTO RICO LATE THU THROUGH SAT AS
A STRONGER HIGH PRES RE-BUILDS N OF THE AREA.

THE ATLANTIC OCEAN...
AN UPPER RIDGE IS OVER THE FLORIDA PENINSULA AND THE W ATLC W OF
75W PRODUCING VERY DRY AIR/SUBSIDENCE. JUST E OF THE RIDGE...
THERE IS A SHARP SHORTWAVE TROUGH THAT EXTENDS FROM AN UPPER LOW
NEAR 27N69W ACROSS THE E BAHAMAS/CUBA INTO THE CARIBBEAN SEA.
SWLY WINDS AHEAD OF THIS SHORTWAVE TROUGH ARE TRANSPORTING
ABUNDANT UPPER LEVEL MOISTURE ACROSS THE W-CENTRAL ATLC JUST
NORTH OF HISPANIOLA AND PUERTO RICO INTO ANOTHER UPPER LEVEL
LOW/TROUGH THAT IS OVER THE CENTRAL ATLC NEAR 27N38W. A SFC
TROUGH REFLECTION OF THE SHORTWAVE TROUGH LIES E TO W ALONG 22N
BETWEEN 58W AND 71W. SCATTERED MODERATE CONVECTION IS RELATED TO
THE TROUGH FROM 21N-24N BETWEEN 64W-70W. THE SECOND UPPER LEVEL
TROUGH SUPPORTS A COLD FRONT THAT ENTERS THE AREA NEAR
31N40W...THEN CONTINUES SW TO 23N58W WHERE IT MERGES WITH ABOVE
MENTIONED SFC TROUGH. THE GFS MODEL INDICATES THAT A BAND OF
MOISTURE WILL PERSIST JUST NORTH OF HISPANIOLA AND PUERTO RICO
THROUGH WED WITH SOME MOISTURE ALSO LINGERING IN THE E BAHAMAS.
A RIDGE COVERS THE E ATLC E OF 36W WHILE A WEAK 1018 MB SFC HIGH
IS NEAR 21N48W. THIS SYSTEM WILL DISSIPATE PRETTY SOON. A LARGE
AREA OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS/ISOLATED TSTMS
IS AHEAD OF THE COLD FROM 20N-30N BETWEEN 28W-41W.

$$
GR




This weather bulletin was brought to you by:
www.nashvilleweather.net