[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101723
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN DEC 10 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N9W 3N27W 2N46W 2N53W. THE ITCZ IS
QUIET TODAY WITH ONLY ISOLATED MODERATE CONVECTION WITHIN 120 NM
S OF THE AXIS E OF 20W. SCATTERED SHOWER ACTIVITY LIES N OF THE
AXIS ASSOCIATED WITH STRONG SWLY UPPER LEVEL WINDS OUTLINED IN
THE ATLC SECTION.

...DISCUSSION...
THE GULF OF MEXICO...
A MID/UPPER LEVEL SHORTWAVE TROUGH EXTENDING FROM MS/AL ACROSS
THE CENTRAL PORTION OF THE GULF IS SLOWLY WEAKENING AND LIFTING
N. THE SUBTROPICAL JET HAS NOW SHIFTED S AND E OF THE AREA AND
MOST OF THE WIDESPREAD MID AND HIGH LEVEL CLOUDINESS AND SHOWER
ACTIVITY HAS DONE THE SAME. THIS IS DUE TO DRY STABLE AIR ALOFT
BEING ADVECTED ACROSS MEXICO AND INTO THE WRN GULF AS AN UPPER
RIDGE BUILDS E...NOW CENTERED ABOVE MEXICO AND TEXAS ALONG 99W.
AT THE SFC...STRONG 1035 MB HIGH NEAR THE COASTLINE OF THE
CAROLINAS CONTINUES TO KEEP RATHER WINDY CONDITIONS IN THE ERN
AND MIDDLE GULF WHERE SEVERAL BUOY AND SHIP OBS ARE REPORTING E
TO NE WINDS IN THE 20-25 KT RANGE. THERE ARE A COUPLE WEAK SFC
TROUGH OR PERTURBATIONS IN THE LOW-LEVEL FLOW ACROSS THE AREA.
THE MORE NOTABLE IS IN THE CENTRAL GULF EXTENDING ALONG 87W/88W
S OF 28N STRETCHING FAR S INTO THE WRN CARIB. THE OTHER IS IN
THE NW GULF ALONG 96W FROM 24N-29N. THE ERN-MIDDLE GULF TROUGH
IS PRODUCING BROKEN TO OVERCAST SKIES AND LIKELY ISOLATED TO
SCATTERED SHOWERS WITHIN 200 NM OF THE TROF AXIS. THE NWRN GULF
FEATURE IS MUCH WEAKER ONLY PRODUCING A NARROW LINE OF SCATTERED
SHOWERS ALONG THE TROF AXIS AS DEPICTED ON DOPPLER RADAR FROM
CORPUS CHRISTI OR HOUSTON/GALVESTON. THE STRONG HIGH WILL
CONTINUE TO RETREAT N AND E AS A WEAK COLD FRONT PUSHES OFF THE
TEXAS COAST ON TUE. THIS PATTERN WILL ALLOW WINDS TO SLACKEN
SLIGHTLY IN THE E AND CENTRAL GULF LATE MON AND TUE.

THE CARIBBEAN SEA...
WIDESPREAD CLOUDINESS AND SCATTERED SHOWERS ARE THE RULE ACROSS
A GOOD PORTION OF THE NRN AND WRN CARIBBEAN NW OF A LINE FROM
ERN HONDURAS TO HAITI. THIS WEATHER IS BEING PRODUCED BY SWIFT
SWLY UPPER LEVEL FLOW ASSOCIATED WITH A PORTION OF THE
SUBTROPICAL JET AND LOW-LEVEL LIFT NEAR A SFC TROUGH EXTENDING
FROM 15N82W TO THE YUCATAN CHANNEL CONTINUING NWD INTO THE GULF
OF MEXICO. ANOTHER CONTRIBUTING FEATURE IS THE TAIL END OF A
SLOWLY WEAKENING STATIONARY FRONT WHICH LIES FROM HAITI NE INTO
THE WRN/CENTRAL ATLC. SCATTERED MODERATE CONVECTION EXISTS IN
THE SW CARIB FROM 10N-13N BETWEEN 81W-84W ASSOCIATED WITH
UPPER DIFFLUENCE AND THE ITCZ. ELSEWHERE THE WEATHER IS FAIRLY
QUIET IN THE CENTRAL AND EASTERN CARIBBEAN UNDER THE INFLUENCE
OF A FLAT UPPER RIDGE. VERY DRY AIR ALOFT IS BEING ADVECTED FROM
THE TROPICAL ATLC....WHERE UPPER LEVEL CONFLUENCE IS PRONOUNCED
...INTO THE ERN CARIBBEAN PROVIDING A STRONG MID LEVEL CAP
PREVENTING THE TYPICAL TRADE WIND CLOUD STREAKS ACQUIRE MUCH
DEPTH. HIGH PRES TO THE N OF THE REGION WILL GRADUALLY PULL
FURTHER N AND THE SFC TROUGH IN THE W CARIB WILL WEAKEN WHICH
WILL HELP WINDS TO RELAX IN THE NW CARIB EARLY THIS WEEK.

THE ATLANTIC OCEAN...
A MID TO UPPER LEVEL TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE
SUBTROPICAL AND TROPICAL ATLANTIC. STARTING FROM W TO E...AN
UPPER TROUGH EXTENDS FROM 32N70W TOWARD THE BAHAMAS. STRONG
MID-UPPER LEVEL SWLY FLOW OR JET LIES ON THE E SIDE OF THE
TROUGH EXTENDING FROM THE SW BAHAMAS NE ALONG 29N68W 3260W. THE
ATTENDANT SFC FRONTAL SYSTEM IS STATIONARY FROM 32N48W
STRETCHING SWWARD ALONG 27N60W 23N67W TO WRN HAITI. WIDESPREAD
BROKEN TO OVERCAST MULTILAYERED CLOUDS AND EMBEDDED SCATTERED
SHOWERS/TSTMS ARE WITHIN 300 NM W OF THE STATIONARY BOUNDARY.
STRONG SFC HIGH PRESSURE...ANCHORED BY A 1035 MB HIGH NEAR THE
CAROLINA COASTLINE IS BEHIND THE FRONT GENERATING NE WINDS OF
20-30 KT ACROSS THE SW NORTH ATLC AND THE BAHAMAS. THESE STRONG
WINDS ACROSS A LONG FETCH IS CREATING HIGH SEAS WITH NE SWELL W
OF THE FRONT. THE UPPER LEVEL PATTERN IS MORE AMPLIFIED IN THE
CENTRAL AND ERN ATLC AS A STRONGLY TITLED RIDGE EXTENDS NEWARD
FROM THE CARIBBEAN ALONG 23N58W 32N45W. THE FLOW THEN FOLDS INTO
A VERY LARGE TROUGH WHICH EXTENDS FROM AN UPPER LOW OVER
MOROCCO TO ANOTHER LARGER UPPER LOW NEAR 22N33W CONTINUING SW
TO 12N55W. THE LATTER UPPER LOW HAS AN ASSOCIATED ILL-DEFINED
SFC TROUGH FROM 17N36W TO 25N34W. SCATTERED SHOWERS ARE WITHIN
300 NM EITHER SIDE OF THE TROUGH AXIS. THESE UPPER LOWS ARE JUST
ABOUT BECOMING CUT OFF AS AN UPPER RIDGE IS BUILDING BETWEEN
THEM. VERY DRY STABLE AIR ALOFT...DUE TO UPPER LEVEL
CONFLUENCE...IS WIDESPREAD BETWEEN 40W AND THE FRONTAL BOUNDARY.
THIS DRY AIR IS ALSO SPREADING INTO THE ERN CARIB. ABUNDANT
UPPER LEVEL MOISTURE ADVECTED FROM THE ITCZ AND ENHANCED BY
STRONG SWLY UPPER LEVEL WINDS ON THE E SIDE OF THE LARGE TROUGH
EXISTS SE OF A LINE ALONG 12N38W 23N21W 26N14W. THE SFC PATTERN
IS DOMINATED BY A STRONG 1039 MB HIGH JUST S OF THE AZORES NEAR
37N25W. THE TIGHT PRES GRAD IS PRODUCING A LARGE AREA OF STRONG
WINDS MOSTLY N OF 12N E OF 45W.

$$
CANGIALOSI




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