[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 121731
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT NOV 12 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND 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...

TROPICAL WAVE LOCATED ABOUT 300 NM E OF THE WINDWARD ISLANDS
ALONG 56W/57W S OF 15N MOVING W 10-15 KT. THE WAVE CONTINUES TO
DISPLAY A FAIRLY WELL-DEFINED LOW-LEVEL CIRCULATION IN SATELLITE
IMAGERY BUT REMAINS EMBEDDED WITHIN A WESTERLY SHEAR
ENVIRONMENT. SCATTERED MODERATE CONVECTION IS BEING PUSHED
MAINLY ALONG AND TO THE E OF THE AXIS FROM 10N-19N BETWEEN
54W-57W. ON ITS CURRENT PACE...THE WAVE SHOULD REACH BARBADOS BY
THIS EVENING AND THE LEEWARD/WINDWARD ISLANDS TOMORROW...WITH
THE HEAVIEST CONVECTION THEN MOVING IN BEHIND THE AXIS.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 73W S OF 17N MOVING W 10
KT. THE WAVE IS LOCATED BENEATH STRONG UPPER LEVEL WESTERLY FLOW
WHICH IS SLOWING THE WAVE'S FORWARD MOVEMENT...AND INDUCING A
STRONG SHEARED ENVIRONMENT. THEREFORE...SATELLITE IMAGERY
DEPICTS A STRUNG OUT APPEARANCE WITH CONVECTIVE ELEMENTS FORMING
AND THE CIRRUS BEING BLOWN QUICKLY TO THE E. THE WAVE IS ALSO
BEGINNING TO INTERACT WITH AN ITCZ PROTRUSION N OF PANAMA TO
PRODUCE A LARGE AREA OF SCATTERED MODERATE FROM 11N-16N BETWEEN
72W-84W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N10W 5N20W 1N40W 12N54W...THEN
ALONG 9N58W 13N70W...THEN ALONG 10N74W 11N78W 9N84W. SCATTERED
MODERATE CONVECTION FROM 3N-9N BETWEEN 13W-18W. WIDELY SCATTERED
MODERATE N OF THE AXIS FROM 7N-12N BETWEEN 44W-51W. SCATTERED
MODERATE OVER THE W/SW CARIBBEAN PARTLY ASSOCIATED WITH THE
TROPICAL WAVE ALONG 73W...SEE ABOVE.

...DISCUSSION...

GULF OF MEXICO...
THE COLD FRONT WHICH HAS BEEN MOVING ACROSS THE GULF HAS FINALLY
CLEARED THE AREA WITH ONLY A SMALL DISSIPATING SEGMENT STILL
DRAPED FROM THE YUCATAN CHANNEL TO 23N90W. HIGH PRES HAS BUILT
IN AT THE SURFACE ANCHORED BY A PAIR OF HIGHS OVER VIRGINIA/
NORTH CAROLINA...AND AN UPPER HIGH HAS SHIFTED TO THE E GULF
WHICH CONTINUES TO FORCE THE FRONT SWD. A LARGE AREA OF
MODERATE/STRONG SUBSIDENCE HAS SETTLED IN BEHIND THE FRONT WITH
MOSTLY FAIR SKIES AND ONLY A FEW FAIR-WEATHER CLOUDS OVER THE
AREA. SOUTHERLY RETURN FLOW ON THE W SIDE OF THE SURFACE HIGH
PRES HAS BEGUN TO ADVECT MOISTURE INLAND OVER E TEXAS (WITH SOME
FOG IN THE RIO GRANDE VALLEY) AND THIS TREND IS EXPECTED TO
CONTINUE UNTIL THE NEXT COLD FRONT MOVES OFF THE COAST BY
MID-WEEK.

CARIBBEAN...
THE GULF OF MEXICO FRONT HAS SETTLED IN OVER THE FAR NW
CARIBBEAN BUT IS QUICKLY LOSING STEAM AS IT APPROACHES THE
CAYMAN ISLANDS. A FEW ISOLATED SHOWERS/TSTMS HAVE BEEN PULSING
NEAR THE FRONT...MAINLY BETWEEN GRAND CAYMAN AND COZUMEL.
FARTHER S...A TROPICAL WAVE ALONG 73W IS INTERACTING WITH A NWD
PROTRUSION OF THE ITCZ TO PRODUCE A LARGE AREA OF SCATTERED
MODERATE CONVECTION S OF 15N TO THE COAST...BETWEEN 72W AND THE
COAST OF NICARAGUA. A 60-70 KT W/SW JET AT 250 MB LIES ALONG THE
N EDGE OF THIS CONVECTION AND IS ADVECTING CIRRUS EWD TOWARDS
THE LEEWARD ISLANDS. A SLIGHT BUMP IN THIS FLOW...A SHORTWAVE
TROUGH EXTENDING FROM PUERTO RICO TO 14N63W...HAS TRIGGERED
SCATTERED SHOWERS/TSTMS FROM 12N-16N BETWEEN 63W-67W. DEEP
MOISTURE WILL REMAIN ENTRENCHED OVER MOST OF THE REGION FOR THE
NEXT SEVERAL DAYS...PRIMARILY S OF ABOUT 17N...AND WILL CONTINUE
TO INCREASE THE CHANCES FOR WIDELY SCATTERED/SCATTERED
CONVECTIVE ACTIVITY.

ATLANTIC...
A LARGE AND ROUNDED UPPER LEVEL TROUGH LIES OVER THE W ATLC THEN
HANGS UP ACROSS THE BAHAMAS...AND IS ASSOCIATED WITH A COLD
FRONT WHICH EXTENDS ALONG 32N55W 26N60W 22N70W THEN ACROSS SE
CUBA. SCATTERED/BROKEN STRATOCUMULUS EXTEND N AND NW OF THE
FRONT TO THE U.S. EAST COAST WITH ONLY A FEW ISOLATED SHOWERS
NOTED WITHIN 60 NM OF THE BOUNDARY BETWEEN 67W-72W. A
PRE-FRONTAL TROUGH IS LOCATED E OF THE FRONT FROM 24N60W 32N55W
WITH THE DEEPEST CONVECTION LYING E OF THAT. THE SWLY FLOW AHEAD
OF THE TROUGH IS CONVERGING WITH THE LOW-LEVEL EASTERLY FLOW
ASSOCIATED WITH THE SUBTROPICAL RIDGE TO PRODUCE SCATTERED
MODERATE CONVECTION N OF 23N BETWEEN 47W-55W. THIS ACTIVITY IS
ALSO BEING FORCED BY SLIGHTLY DIFFLUENT UPPER LEVEL WESTERLY
FLOW COMING OUT OF THE CARIBBEAN INTO THE CNTRL ATLC. BROAD HIGH
PRES AND A TIGHT PRES GRADIENT IS IN CONTROL E OF 50W...ANCHORED
BY A STRONG 1042 MB HIGH N OF THE AZORES. A CUT-OFF UPPER LOW IS
SPINNING SWD OVER THIS AREA NEAR 21N31W AND ALTHOUGH IT IS
SURROUNDED BY MODERATE/STRONG SUBSIDENCE...IT HAS BEEN
TRIGGERING SCATTERED SHOWERS/TSTMS NEAR ITS CENTER FROM 20N-24N
BETWEEN 27W-32W. A 90 KT JET DIPS S OF THE UPPER LOW ALONG 14N
AND THEN PROTRUDES ACROSS THE CAPE VERDE ISLANDS AND MAURITANIA
WITH CIRRUS EXTENDING UP TO 500 NM SE OF THE AXIS.

$$
BERG


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