[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201724
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON NOV 20 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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...
THE TROPICAL WAVE PREVIOUSLY ALONG 85W HAS BEEN DROPPED FROM THE
SFC ANALYSIS AT 12Z. THIS FEATURE IS NO LONGER DISCERNIBLE IN
SATELLITE IMAGERY OR SFC OBSERVATIONS AS IT APPEARS THAT IT WAS
ABSORBED BY A LARGE CONVECTIVE SFC TROUGH IN THE WRN CARIBBEAN.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 5N30W 4N40W 2N50W. SCATTERED
MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF THE AXIS
BETWEEN 14W-20W. ISOLATED MODERATE IS WITHIN 240 NM EITHER SIDE
BETWEEN 24W-30W.

...DISCUSSION...
THE GULF OF MEXICO...
A STRONG ELONGATED UPPER TROUGH CONTINUES TO DIG SOUTHEASTWARD
NOW LOCATED ACROSS THE OHIO VALLEY INTO THE NW GULF. MID/UPPER
LEVEL SWLY FLOW S AND E OF THE DIGGING TROUGH IS ADVECTING SOME
MOISTURE FROM THE TROPICAL EPAC...IN WHICH T.D. SERGIO IS
EMBEDDED...ACROSS THE SRN GULF SE OF A LINE ALONG 21N97W 25N87W
TO NEAR ORLANDO. THIS MOISTURE IS NOT A BIG WEATHER PRODUCER AS
IT IS MAINLY IN THE FORM OF MID-HIGH LEVEL CLOUDINESS AND
ISOLATED SHOWERS FILTERING SUNSHINE. VERY DRY STABLE AIR ALOFT
LIES N AND W OF THE LINE MENTIONED. AT THE SFC...STRONG HIGH
PRES COVERS THE ENTIRE AREA ANCHORED BY A FEW 1035 MB HIGH
CENTERS IN THE CENTRAL U.S. THE BIG STORY IS THE UNSEASONABLY
COLD/DRY AIR AND INCREASING NLY WINDS DUE TO THE THE TIGHTENED
PRES GRAD BETWEEN THIS STRONG HIGH AND A SFC LOW OFF THE GEORGIA
COAST. SFC WINDS HAVE BEEN INCREASING THIS MORNING/EARLY
AFTERNOON WITH MOST BUOYS REPORTING WINDS IN THE 15-25 KT RANGE.
THIS FLOW CONTINUES TO ADVECT COLD/DRY AIR INTO THE REGION WITH
HIGH TEMPS MAINLY IN THE 50'S AND 60'S. MODELS FORECAST THE
UPPER TROUGH TO CONTINUE TO DIG SE AND BECOME CUT OFF OVER
FLORIDA/GEORGIA LATE TOMORROW SIGNIFICANTLY LOWERING HEIGHTS.
THIS COLD AIR ALOFT ALONG WITH NLY FLOW AT THE SFC WILL CONTINUE
TO PRODUCE UNSEASONABLE COOL WEATHER ACROSS THE CENTRAL AND E
GULF OVER THE NEXT FEW DAYS.

THE CARIBBEAN SEA...
A LARGE AREA OF SCATTERED MODERATE CONVECTION EXISTS IN THE
CNTRL/WRN CARIBBEAN BETWEEN 74W-82W WHICH INCLUDES THE ISLANDS
OF JAMAICA AND ERN CUBA. THIS UNSETTLED WEATHER IS ASSOCIATED
WITH A SFC TROUGH WHICH EXTENDS FROM THE ATLC ACROSS THE BAHAMAS
ALONG 21N73W 17N79W 11N80W. A 1048 UTC QSCAT PASS INDICATED A
PRONOUNCED WIND SHIFT WHERE NLY 20-25 KT WINDS ARE COMMON W OF
THE TROUGH AXIS AND LIGHTER E TO NE WINDS ARE E OF THE AXIS. IN
ADDITION...VISIBLE IMAGES SHOW MID-LEVEL ROTATION IN THE CLOUDS
NEAR 16N80W. IT IS POSSIBLE THAT A SFC LOW PRES SYSTEM MAY BE
FORMING IN THAT VICINITY. UPPER LEVEL SWLY-WLY WINDS...NEAR AND
W OF AN UPPER RIDGE AXIS ALONG 72W...ARE SPREADING MOISTURE
AROUND THE RIDGE...BUT MUCH OF THIS IS QUICKLY DRYING OUT ON THE
DESCENT NLY BRANCH ABOVE THE ERN CARIBBEAN. ISOLATED SHOWERS ARE
N OF 15N BETWEEN 66W-74W. OTHERWISE...CONDITIONS ARE FAIRLY
QUIET ACROSS THE REMAINDER OF THE E ATLC. GFS SHOWS THE DEEP
MOISTURE SWATH LINGERING BUT SHRINKING IN SIZE OVER THE NEXT
COUPLE DAYS IN THE CNTRL/WRN CARIBBEAN.

THE ATLANTIC OCEAN...
AN AMPLIFIED PATTERN LIES ACROSS THE ATLC BASIN. A REINFORCING
COLD FRONT...ASSOCIATED WITH THE STRONG MID/UPPER TROUGH ACROSS
THE CENTRAL/ERN U.S...STRETCHES ALONG 32N79W ACROSS THE WRN-MOST
BAHAMAS TO N CUBA. NWLY WINDS ARE INCREASING BEHIND THIS
BOUNDARY. SEE GULF OF MEXICO DISCUSSION FOR DETAILS ON THE
AIRMASS BEHIND THIS FRONT. A LARGE TITLED RIDGE COVERS THE AREA
BETWEEN 55W-75W INCLUDING MOST OF THE CARIB. AN OLD FRONTAL
BOUNDARY LIES ALONG 32N63W 25N69W TO THE SE BAHAMAS. VERY ACTIVE
WEATHER IS OCCURRING ALONG THE TAIL END OF THIS BOUNDARY IN THE
CARIB BUT ONLY ISOLATED SHOWERS ARE WITHIN 180 NM EITHER SIDE OF
THE TROUGH IN THE ATLC. ANOTHER SFC TROUGH LIES ALONG 31N49W
22N54W. A WEAK LOW PRES SYSTEM HAS FORMED ALONG THIS TROUGH NEAR
26N. THIS FEATURE IS VERY WEAK WITH ONLY ISOLATED SHOWERS NOTED
WITHIN 240 NM E OF THE TROUGH AXIS N OF 25N. THIS SFC FEATURE IS
ASSOCIATED WITH A SMALL UPPER LOW NEAR 26N50W. A NARROW UPPER
RIDGE LIES TO THE E OF THE UPPER LOW/SFC TROUGH BETWEEN 35W-43W
N OF 15N. THE REMAINDER OF THE ATLC...E OF 35W...IS DOMINATED BY
A LARGE CUT OFF MID/UPPER LEVEL LOW CENTERED NEAR 26N23W.
SCATTERED SHOWERS AND TSTMS ARE MAINLY CONTAINED ON THE N SIDE
OF THE LOW FROM 26N-31W BETWEEN 17W-26W. A RELATED SFC TROUGH
EXTENDS FROM 19N25W TO 31N18W. AT THE SFC...A 1034 MB HIGH IS
CENTERED OVER THE AZORES. THIS STRONG RIDGING IS CONTAMINATED BY
THE SFC TROUGHS DESCRIBED ABOVE.

$$
CANGIALOSI




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