[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 132324
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST WED DEC 13 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 6N12W 4N22W 4N40W 2N50W . SCATTERED
MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE AXIS
BETWEEN 22W-33W. ISOLATED MODERATE IS WITHIN 90 NM S OF THE
AXIS E OF 18W.

...DISCUSSION...
THE GULF OF MEXICO...
A FEW SCATTERED SHOWERS OVER THE SE GULF IN A LARGE AREA OF
CLOUDINESS. SCATTERED CLOUDS WITH AREAS OF RAIN AND A FEW
POSSIBLE SHOWERS ARE OVER THE SW GULF . A FEW PATCHES OF LOW
CLOUDS AND LIGHT SHOWERS ARE ELSEWHERE.

THE CARIBBEAN SEA...
A TROUGH ALONG THE SW PORTION IS CAUSING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS S OF 16N W OF 80W. ANOTHER TROUGH NEAR
THE YUCATAN COAST IS CAUSING SCATTERED SHOWERS. THIS TROUGH HAS
BECOME A LITTLE BETTER DEFINED WITH LOW-LEVEL CYCLONIC TURNING
IN THE WINDS EVIDENT IN SATELLITE IMAGERY AND AN EARLIER QSCAT
PASS. SOME LIFT NEAR THE SFC TROUGH ALONG WITH WEAK UPPER
DIFFLUENCE...BETWEEN A BROAD FLAT RIDGE CENTERED OVER COLOMBIA
AND STRONGER UPPER LEVEL WLY FLOW IN THE NW CARIB...IS SPARKING
SCATTERED SHOWERS AND ISOLATED TSTMS FROM 11N-17N BETWEEN
78W-84W. DEEPER MORE CONVECTIVE ACTIVITY...ASSOCIATED WITH THE
ITCZ...LIES FURTHER S OVER COLOMBIA AND THE EXTREME SW CARIB.
THE REMAINDER OF THE AREA IS QUIET UNDER MODERATELY DRY AIR
ALOFT ASSOCIATED WITH THE BROAD UPPER LEVEL RIDGE. TRADE WINDS
ARE MOSTLY IN THE 15-20 KT RANGE EXCEPT FOR SOME STRONGER WINDS
IN THE S CENTRAL CARIB DUE TO LOWER PRES OVER N SOUTH AMERICA.
NO MAJOR CHANGES IN THESE WINDS ARE EXPECTED THRU THE WEEK.

THE ATLANTIC OCEAN...
A LONGWAVE RIDGE/TROUGH/RIDGE PATTERN IS ESTABLISHED ACROSS THE
DISCUSSION AREA. VERTICALLY STACKED RIDGING EXISTS IN THE WRN
ATLC WITH THE MEAN AXIS ALONG 68W. A BAND OF STRONG MID-UPPER
LEVEL WINDS OR A WEAK JET STRETCHES FROM THE BAHAMAS EASTWARD TO
22N45W THEN RACING NWD IN RESPONSE TO THE TROUGH IN THE CENTRAL
ATLC. N OF THE WEAK JET...PLENTY OF DRY STABLE AIR ALOFT EXISTS
W OF 40W. THIS STRONG MID-LEVEL CAP IS KEEPING THE PATCHES OF
LOW-LEVEL MOISTURE DRIVEN BY FRESH NE-E WINDS SHALLOW. A BROAD
TROUGH DOMINATES THE CENTRAL ATLC WITH THE UPPER AXIS ALONG 43W.
 A PLUME OF MOISTURE ASSOCIATED WITH THE SFC FRONT AND UPPER
LEVEL JET MENTIONED IS N OF 23N BETWEEN 36W-43W.  THE
SUBTROPICAL E ATLC IS DOMINATED BY STRONG VERTICALLY STACKED
RIDGING WITH THE UPPER HIGH CENTER NEAR 31N24W AND THE 1028 MB
SFC CENTER FURTHER TO THE NE. A WEAKENING CUT OFF UPPER LEVEL
LOW IS EMBEDDED IN THE LARGE SCALE RIDGE NEAR 25N29W. THIS UPPER
LEVEL FEATURE IS ONLY PRODUCING SOME ISOLATED SHOWERS IN ITS
VICINITY. THE UPPER LOW APPEARS THAT IT WILL BE COMPLETELY
OVERTAKEN SHORTLY BY A NARROW RIDGE TO ITS W AS SUGGESTED BY
GFS.

$$
TORRES


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