[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 312330
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 31 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2300 UTC.

...SPECIAL FEATURE...

TROPICAL STORM ZETA IS NEAR 25.7N 38.1W OR ABOUT 1070
MILES...1720 KM...SOUTHWEST OF THE AZORES ISLANDS AT 31/2100
UTC. ZETA IS CURRENTLY STATIONARY. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1000 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 45 KT
WITH GUSTS TO 55 KT. PLEASE REFER TO THE LATEST
FORECAST/ADVISORY LISTED UNDER THE AWIPS/WMO HEADERS
MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. SCATTERED MODERATE AND
ISOLATED STRONG CONVECTION IS PERSISTING...HOWEVER WESTERLY
VERTICAL WIND SHEAR IS RESTRICTING THE CONVECTION TO THE EASTERN
SEMI-CIRCLE...ESPECIALLY THE NORTHEAST QUADRANT...OF ZETA FROM
26N-29N BETWEEN 37W-38W. THERE IS ALSO SOME SCATTERED MODERATE
SHOWERS IN AN OUTER RAINBAND IN THE SOUTHEAST QUADRANT FROM
20N-25N BETWEEN 34W-37W. THE LOW-LEVEL CENTER OF ZETA APPEARS TO
BE EXPOSED AND STEADY WEAKENING IS ANTICIPATED.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N13W 4N30W 4N40W 7N52W 6N58W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 200 NM ON EITHER SIDE OF THE AXIS. THE MOST ORGANIZED
CONVECTION IS WITHIN 150 NM ON EITHER SIDE OF THE AXIS BETWEEN
29W-40W AND THE SCATTERED MODERATE TO ISOLATED STRONG CONVECTION
THAT HAS RECENTLY DEVELOPED WITHIN 100 NM SOUTH OF THE AXIS
BETWEEN 18W-22W.

...DISCUSSION...

THE GULF OF MEXICO...
A 1019 MB SURFACE HIGH OVER THE WESTERN ATLANTIC IS CONTROLLING
MUCH OF THE WEATHER OVER THE GULF OF MEXICO. GLOBAL MODELS
FORECAST SURFACE RIDGING TO CONTINUE ACROSS THE AREA THROUGH THE
NEXT COUPLE OF DAYS. A WEAK STATIONARY FRONT IS ALONG THE
NORTHERN PORTION OF THE GULF FROM THE FLORIDA PANHANDLE TO
SOUTHERN LOUISIANA.  NO CONVECTION IS NOTED ALONG THE FRONTAL
BOUNDARY. A WEAK SURFACE TROUGH HAS DEVELOPED THIS AFTERNOON IN
THE WESTERN GULF FROM 19N-24N ALONG 95W-96W. BROKEN CLOUDS AND
ONLY SOME ISOLATED SHOWERS ARE OCCURRING NEAR THE TROUGH. IN THE
UPPER LEVELS...SOUTHWESTLERY FLOW PREVAILS WEST OF 90W WITH A
MORE ZONAL WESTERLY FLOW EAST OF 90W. MID-HIGH LEVEL CLOUDS ARE
WIDESPREAD ACROSS THE GULF. GLOBAL MODELS DEVELOP A LOW IN THE
MID-WEST U.S. TOMORROW BUT THE EFFECTS OF THIS LOW SHOULD STAY
NORTH OF THE AREA...SO NO BIG CHANGES ARE EXPECTED.

THE CARIBBEAN SEA...
EASTERLY TRADES NEAR 15 KT ARE OVER THE ENTIRE CARIBBEAN SEA.
PATCHY AREAS OF LOW-LEVEL CLOUDS AND ISOLATED SHOWERS ARE
QUICKLY MOVING WESTWARD ACROSS PUERTO RICO...HISPANIOLA...AND
JAMAICA. IN THE UPPER LEVELS...AN UPPER HIGH IS CENTERED
SOUTH OF CUBA NEAR 20N79W. THIS UPPER HIGH IS PRODUCING DRY
UPPER LEVEL AIR AND STRONG SUBSIDENCE ACROSS THE ENTIRE
CARIBBEAN WITH THE DRIEST AIR EAST OF 80W.

THE ATLANTIC OCEAN WEST OF 50W...
A 1019 MB SURFACE HIGH IS CENTERED NEAR 27N65W. THIS HIGH IS
PRODUCING FAIR WEATHER ACROSS MUCH OF THE ATLANTIC OCEAN WEST OF
50W. ONE EXCEPTION IN THE FAIR WEATHER IS CAUSED BY A COLD FRONT
THAT IS DRAPED NORTH OF THE AREA TO ALONG 32N53W 28N57W. BROKEN
CLOUDS AND SCATTERED SHOWERS ARE WITHIN 100 NM AHEAD OF THE
FRONT. IN THE UPPER LEVELS...WESTERLY FLOW COVERS MOST OF THE
CENTRAL AND WESTERN ATLANTIC. DRY UPPER LEVEL AIR AND STRONG
SUBSIDENCE IS WIDESPREAD ACROSS THE AREA SOUTH OF 28N.

THE ATLANTIC OCEAN EAST OF 50W...
TROPICAL STORM ZETA...THE 27TH NAMED STORM OF THE YEAR...REMAINS
THE MAIN FEATURE OF INTEREST IN THE EASTERN ATLANTIC WATERS.
WEAK RIDGING IS PRESENT IN THE LOWER TO MIDDLE TROPOSPHERE TO
THE NORTH OF ZETA...AND THIS STEERING SHOULD PREDOMINATE FOR THE
NEXT DAY. BESIDES FOR ZETA...CONVECTION IS ONLY FOUND NEAR THE
ITCZ AXIS. IN THE UPPER LEVELS...WESTERLY FLOW COVERS A GOOD
PORTION OF THE EASTERN ATLANTIC.

$$
CANGIALOSI






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