[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041736
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT NOV 04 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 IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

A FAIRLY HIGH AMPLITUDE TROPICAL WAVE IS ALONG 40W S OF 19N
MOVING W NEAR 10 KT. BROAD LOW TO MID-LEVEL CYCLONIC TURNING IS
EVIDENT IN VISIBLE SATELLITE IMAGERY. THE WAVE AXIS IS ANALYZED
NEAR THE WRN EDGE OF THE THICK CLOUDS AS STRONG W-SWLY UPPER
LEVEL WINDS...ASSOCIATED WITH A STRONG SHARP TROUGH IN THE
CENTRAL/EASTERN ATLC...IS SHEARING MUCH OF THE DEEP CONVECTION N
OF 13N AND SPREADING DEBRIS HIGH LEVEL MOISTURE WELL TO THE NE
OF THE WAVE. SCATTERED MODERATE CONVECTION IS FROM 3N-13N
BETWEEN 28W-42W.

A TROPICAL WAVE IS IN THE WRN CARIBBEAN ALONG 84W S OF 17N
MOVING W 10 TO 15 KT. THIS WAVE CONTINUES TO BE CHALLENGING TO
LOCATE AS LITTLE...IF ANY...SIGNATURE IS APPARENT IN SATELLITE
IMAGERY OR AVAILABLE SFC DATA. THEREFORE...THE POSITION IS BASED
ON EXTRAPOLATION. ONLY ISOLATED SHOWERS ARE WITHIN 180 NM EITHER
SIDE OF THE WAVE AXIS.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N12W 8N30W 10N39W 9N42W 4N52W.
BESIDES FOR THE CONVECTION ASSOCIATED WITH THE LARGE TROPICAL
WAVE...SCATTERED MODERATE IS WITHIN 240 NM EITHER SIDE OF THE
AXIS E OF 21W.

...DISCUSSION...
THE GULF OF MEXICO...
STRONG SFC HIGH PRES CENTERED OVER THE OHIO VALLEY CONTROLS THE
WEATHER ACROSS MOST OF THE GULF PRODUCING FAIR AND QUITE WINDY
CONDITIONS. THE STRONGEST WINDS ARE IN THE E GULF WHERE SEVERAL
SHIPS/BUOYS ARE REPORTING NE TO E WINDS BETWEEN 20 AND 30 KT.
THESE WINDS ARE PRODUCING SEAS TO 11 FT. FOR DETAILS REFER TO
THE OFFSHORE WATERS FORECAST FOR THE GULF OF MEXICO...MIAOFFNT4.
THERE IS STILL SOME POST-FRONTAL MOISTURE S OF 25N E OF 87W
ASSOCIATED WITH MOIST SWLY UPPER LEVEL FLOW. THE MOST ORGANIZED
SHOWER ACTIVITY IS NEAR THE YUCATAN CHANNEL. IN THE FAR WRN
GULF...A WEAKENING LOW-LEVEL CONVERGENT LINE ALONG THE COAST OF
MEXICO...ANALYZED AS A TROUGH ON THE MAP...IS TRIGGERING A FEW
SHOWERS NEAR COASTAL MEXICO AND THE SW BAY OF CAMPECHE. THE
STRONG SFC RIDGE WILL SLOWLY SLIDE EWARD WHICH WILL ALLOW THE
WINDS TO SUBSIDE EARLY NEXT WEEK...THOUGH IT WILL REMAIN BREEZY.

THE CARIBBEAN SEA...
A PLUME OF MOISTURE REMAINS IN THE WRN CARIBBEAN W OF A LINE
FROM CENTRAL CUBA TO WRN HONDURAS. THIS MOISTURE HAS
SIGNIFICANTLY THINNED OUT SINCE YESTERDAY AS THE SFC LOW THAT
WAS NEAR BELIZE DISSIPATED AND THE COLD FRONT HAS LIFTED N OF
THE AREA...HOWEVER A SHEAR AXIS STILL APPEARS EVIDENT. THE
REMNANT MOISTURE IS NOW MAINLY ASSOCIATED WITH UPPER DIFFLUENCE
AND SWLY UPPER LEVEL FLOW WHICH IS ADVECTING TROPICAL MOISTURE
FROM THE ITCZ IN THE EPAC ACROSS THE AREA. SCATTERED SHOWERS ARE
MOST ORGANIZED IN THE YUCATAN CHANNEL. THE REMAINDER OF THE
CARIBBEAN IS QUIET WITH PLENTY OF DRY STABLE AIR ALOFT ACROSS
THE AREA...ANCHORED BY AN UPPER HIGH CENTERED NEAR 16N76W...
SUPPRESSING SIGNIFICANT SHOWER ACTIVITY. IN FACT...THE ONLY AREA
OF CONVECTION EVIDENT IN IR IMAGERY IS 250 NM SW OF JAMAICA
WITHIN 30 NM FROM 15N80.5W. TRADE WINDS REMAIN MODERATE WITH
TYPICAL LOW-LEVEL MOISTURE STREAMS STEERED W BY THE FLOW.
STRONGER WINDS...20 TO 25 KT...ARE IN THE YUCATAN CHANNEL WHERE
THE PRES GRAD IS TIGHTER DUE TO STRONG HIGH PRES TO THE N.

THE ATLANTIC OCEAN...
A HIGH AMPLITUDE UPPER LEVEL PATTERN IS ESTABLISHED ACROSS THE
ATLC BASIN. STRONG SWLY UPPER LEVEL FLOW...BETWEEN A FLATTENING
TROUGH OFF THE U.S. EAST COAST AND A HIGHLY ELONGATED UPPER
LEVEL RIDGE...IS ADVECTING TROPICAL MOISTURE ACROSS THE
BAHAMAS INTO THE ATLC. AN ASSOCIATED COLD FRONT EXTENDS FROM A
1014 MB LOW NEAR 33N61W ALONG 26N67W ACROSS THE SE BAHAMAS AND
ERN CUBA. SHOWERS AND TSTMS ARE WITHIN 120 NM AHEAD OF THE FRONT
N OF 24N. A PRE-FRONTAL SFC TROUGH AND/OR SOME UPPER DIFFLUENT
AIR IS TRIGGERING A LINE OF SCATTERED SHOWERS AND TSTMS ALONG
64W FROM 21N-26N.  THERE IS NOT MUCH CLEARING BEHIND THE
FRONT...AS POST-FRONTAL MOISTURE ENHANCED BY THE MOIST SWLY
UPPER LEVEL FLOW IS LINGERING FOR A FEW HUNDRED NM BEHIND IT.
MUCH DRIER AIR ALOFT IS W OF 77W N OF 27N...SLOWLY PRESSING E.
SWIFT NE WINDS FROM 20 TO 30 KT ARE BEHIND THE FRONT PRODUCING
HIGH SEAS IN NE SWELL. A STRONGLY ELONGATED UPPER RIDGE
ORIGINATING IN THE CARIBBEAN STRETCHES NEWARD ALONG 22N68W
32N52W.  THIS PATTERN THEN FOLDS INTO A STRONG SHARP UPPER
TROUGH THAT ENCOMPASSES MUCH OF THE E ATLC. THE UPPER AXIS
EXTENDS FROM AN UPPER LOW NEAR THE AZORES AND SOUTHWESTWARD
ALONG 26N40W TO ANOTHER UPPER LOW NEAR 21N44W CONTINUING TO
15N57W. VERY DRY STABLE UPPER LEVEL AIR LIES TO THE W OF THE
TROUGH AXIS TO 60W. A FAIR AMOUNT OF MOISTURE LIES E OF THE AXIS
TO NEAR THE COAST OF W AFRICA. THE DEEPEST MOISTURE IS
ASSOCIATED WITH THE TROPICAL WAVE ALONG 40W...HOWEVER THE STRONG
W-SWLY UPPER WINDS IS SHEARING MUCH OF THE DEEP CONVECTION
ESPECIALLY ACROSS THE NRN PORTION OF THE WAVE.

$$
CANGIALOSI




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