[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 310537
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON DEC 31 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0515 UTC

...SPECIAL FEATURE...
A LARGE LOW PRES SYSTEM...PRODUCING GALE FORCE WINDS...CONTINUES
TO SPIN CENTERED NEAR 27N35W. A FORTUITOUS REPORT FROM DRIFTING
BUOY 62901...LOCATED VERY NEAR THE LOW-LEVEL CENTER...REVEALED A
PRES OF 1004.6 MB AT 00Z SO ACCORDINGLY THE MIN PRES WAS DROPPED
TO 1004 MB. THIS LOW HAS BEEN MEANDERING ABOUT FOR THE PAST
SEVERAL DAYS BUT NOW APPEARS TO BE ON A SW HEADING AS THE UPPER
SHORTWAVE IS PASSING TO THE NE ALLOWING A BUILDING MID-LEVEL
RIDGE TO BE THE MAIN STEERING ELEMENT. THE LOW IS A LITTLE MORE
ASYMMETRIC AND ELONGATED TONIGHT WITH CONVECTION CONFINED TO THE
NW QUADRANT N OF 27N BETWEEN 35W-39W AND IN A NARROW BANDED
STRUCTURE TO THE E OF THE CENTER FROM 24N-29N BETWEEN 30W-32W.
THE STRONGEST WINDS...TO 40 KT...ARE LOCATED IN THE NW
SEMICIRCLE WHERE THE PRES GRADIENT IS TIGHTEST DUE TO A 1029 MB
HIGH CENTERED NEAR 33N49W. NUMERICAL MODEL GUIDANCE IS IN
GOOD AGREEMENT IN SHOWING THIS SYSTEM MOVING OFF TO THE SW AND
WEAKENING. THIS LOW...OR WHAT EVER IS LEFT OF IT...WILL LIKELY
GET PICKED UP AND ABSORBED BY A LARGE UPPER TROUGH LATER THIS
WEEK.

...THE ITCZ...
THE ITCZ EXTENDS FROM THE LIBERIA COAST NEAR 6N10W ALONG 3N15W
1N20W 1N35W EQ40W 2S45W. SCATTERED MODERATE CONVECTION IS WITHIN
75 NM EITHER SIDE OF THE AXIS BETWEEN 12W-15W. A WEAK TROUGH
ALONG 42W IS ENHANCING SCATTERED MODERATE CONVECTION WITHIN 90
NM E OF THE AXIS FROM 2N-4N.

...DISCUSSION...
GULF OF MEXICO...
A LINGERING FRONTAL BOUNDARY REMAINS DRAPED ACROSS THE AREA
ANALYZED AS A COLD FRONT FROM THE FLORIDA PANHANDLE NEAR 30N84W
TO 24N93W THEN STATIONARY INTO THE BAY OF CAMPECHE AND NWD ALONG
THE E SLOPES OF THE SIERRA MADRE MOUNTAINS IN MEXICO ALONG
24N93W 18N94W 17N95W 22N99W. MOSAIC DOPPLER RADAR REVEALS NARROW
LINES OF TSTMS AHEAD OF THE BOUNDARY OVER N CENTRAL
FLORIDA...MAINLY N OF THE ORLANDO AREA...WHERE UPPER DIFFLUENCE
IS ONE OF THE MAIN TRIGGERS. ONLY BROKEN CLOUDS AND ISOLATED TO
SCATTERED SHOWERS ARE ANTICIPATED WITHIN 90 NM W OF THE FRONT.
ISOLATED SHOWERS AND TSTMS ARE AHEAD OF THE FRONT MAINLY E OF
90W IN STRONG SWLY FLOW ALOFT. A STRONG COLD FRONT IS EXPECTED
TO MOVE INTO THE NW WATERS MON EVENING AND MOVE RAPIDLY ACROSS
THE AREA...CLEARING THE ENTIRE REGION BY TUE EVENING. NLY GALE
FORCE WINDS ARE ANTICIPATED BEHIND THE FRONT WHICH WILL USHER A
VERY COOL AIRMASS INTO THE REGION.

CARIBBEAN SEA...
TRANQUIL CONDITIONS PREVAIL ACROSS THE CARIB BENEATH AN
AMPLIFIED MID TO UPPER HIGH CENTERED JUST S OF HAITI. WIDESPREAD
DRY STABLE AIR ALOFT IS EVIDENT ON WATER VAPOR IMAGES ESPECIALLY
E OF THE HIGH WHERE THE FLOW ALOFT IS CONFLUENT. PATCHY MID-HIGH
LEVEL CLOUDS ARE STREAMING NWD ON THE W SIDE OF THE HIGH W OF
81W. A FEW TSTMS HAVE FORMED NEAR THE YUCATAN CHANNEL ENHANCED
BY UPPER DIFFLUENCE OUT AHEAD OF A BROAD UPPER TROUGH OVER MUCH
OF THE CENTRAL U.S. TRADE WINDS ARE QUITE STRONG IN THE S
CENTRAL CARIB AND EXPECTED TO REMAIN THAT WAY OVER THE NEXT
COUPLE OF DAYS. NLY WINDS ARE ANTICIPATED TO INCREASE TO NEAR
GALE FORCE IN THE NW CARIB BEHIND A STRONG COLD FRONT ON WED.

ATLANTIC OCEAN...
BESIDES FOR THE SPECIAL FEATURE DISCUSSED ABOVE...THE ATLC
REGION IS VERY QUIET WITH HIGH PRES RIDGING DOMINATING THE SFC
PATTERN SUPPORTED BY CENTERS LOCATED N OF THE DISCUSSION AREA.
IN THE MID AND UPPER LEVELS...A SPRAWLING AMPLIFIED HIGH
CENTERED IN THE CARIB COVERS THE AREA W OF 55W. LARGE SCALE
TROUGHING COVERS A GOOD PORTION OF THE CENTRAL AND E ATLC
EXTENDING FROM THE SPECIAL FEATURE SW TO THE LESSER ANTILLES. A
SWLY JET...WITH CORE WINDS OF 100 KT OR SO...ORIGINATES FROM
JUST E OF THE TROUGH BASE NEAR 12N56W AND EXTENDS TO AFRICA THRU
23N16W. UPPER DIFFLUENCE TO THE S OF THE JET IS GENERATING AND
ADVECTING DENSE MID-HIGH LEVEL CLOUDS AND EMBEDDED SHOWERS
WITHIN 480 NM S OF THE AXIS.

$$
CANGIALOSI




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