[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 021132
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SUN DEC 02 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 6N10W 5N21W 4N35W 4N45W 2N52W.
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM OF THE AXIS
BETWEEN 27W-32W. SIMILAR CONVECTION IS BEING ENHANCED BY A
PERTURBATION OR SFC TROUGH IN THE ITCZ FROM 4N-6N BETWEEN
40W-43W AND FROM 7N-8N BETWEEN 34W-36W. SCATTERED MODERATE IS
ALSO WITHIN 90 NM S OF THE AXIS E OF 11W.

DISCUSSION...

GULF OF MEXICO...
FAIR WEATHER EXISTS ACROSS THE ENTIRE GULF THANKS IN PART TO A
SPRAWLING UPPER ANTICYCLONE CENTERED OVER THE NE WATERS NEAR
28N86W. ABUNDANT SUBSIDENCE IS EMBEDDED IN THIS HIGH
...ESPECIALLY S OF 25N PROVIDING A STABLE ATMOSPHERE. AT THE
SFC...HIGH PRES RIDGING EXTENDS SW FROM SOUTHEASTERN CANADA.
THIS PATTERN HAS ALLOWED WINDS TO BE MAINLY MODERATE OUT OF THE
E TO SE...EXCEPT SLY IN THE WRN GULF. THIS LOW-LEVEL FLOW IS
PRODUCING ABOVE NORMAL TEMPS AND HUMID CONDITIONS. A FEW PATCHES
OF LOW-LEVEL CLOUDINESS...WHICH COULD CONTAIN AN ISOLATED SHOWER
AS NOTED IN DOPPLER RADAR...IS EVIDENT ON NIGHT CHANNEL SAT
IMAGES E OF 90W. A CHANGE IN AIRMASS IS EXPECTED TO BEGIN
FILTERING IN ABOUT 24-36 HOURS AS A COLD FRONT PUSHES INTO THE
NW WATERS. THIS FRONT WILL ADVECT A COOLER AND MUCH DRIER
AIRMASS INTO THE REGION.

CARIBBEAN SEA...
LIKE THE GULF OF MEXICO...THE CARIBBEAN IS ALSO VERY QUIET THIS
MORNING WITH WATER VAPOR IMAGERY REVEALING A MID-UPPER
RIDGE/TROUGH PATTERN AND A WIDESPREAD SUBSIDENT ENVIRONMENT. AT
THE SFC...THE TAIL END OF A CENTRAL ATLC TROUGH CUTS ACROSS THE
LEEWARD ISLANDS. ENHANCED NLY FLOW TO THE W OF THE TROUGH IS
BLOWING IN STREAMS OF SHALLOW SHOWERS FROM THE ATLC ACROSS
PUERTO RICO...THE DOMINICAN REPUBLIC AND ELSEWHERE N OF 14N
BETWEEN 65W AND 71W. SIMILAR ACTIVITY IS LIKELY OCCURRING ACROSS
MUCH OF THE LESSER ANTILLES. THIS TROUGH HAS CAUSED A
SIGNIFICANT WEAKNESS IN THE SYNOPTIC PRES PATTERN WHICH HAS
ALLOWED WINDS TO BE LIGHT AND VARIABLE NEAR/OVER THE LESSER
ANTILLES AS NOTED IN SFC OBS AND A RECENT ASCAT PASS. SFC WINDS
ELSEWHERE ARE MODERATE TO STRONG GENERALLY OUT OF THE NE.

ATLANTIC OCEAN...
A COLD FRONT IS MOVING ACROSS THE W ATLC ANALYZED FROM 32N58W TO
A WEAK 1017 MB LOW NEAR 29N64W THEN DISSIPATING AS A BACK-DOOR
TYPE FRONT TO 28N78W. THE WRN PORTION HAS BROKEN OFF FROM THE
MAIN BOUNDARY AND IS PUSHING WWD STEERED BY THE PREVAILING
LOW-LEVEL WINDS. SCATTERED SHOWERS ARE LIKELY NEAR THE
FRAGMENTED TROUGH FROM 28N-32N BETWEEN 76W-80W AND ISOLATED
SHOWERS ARE POSSIBLE ELSEWHERE WITHIN 90 NM OF THE FRONT. A
LARGE AREA OF BROKEN STRATOCUMULUS CLOUDS ARE BUILDING BEHIND
THE FRONT...INDICATIVE OF THE COOLER MORE STABLE AIRMASS.

IN THE CENTRAL ATLC...THE MAIN FEATURE IS A 1011 MB LOW PRES
SYSTEM CENTERED NEAR 26N54W WITH A TRAILING TROUGH EXTENDING SW
ACROSS THE LEEWARD ISLANDS. THIS LOW HAS BEEN STRENGTHENING
OVERNIGHT WITH CONVECTION DEEPENING SOME...CONSOLIDATING AND
BECOMING MORE CIRCULAR. SCATTERED MODERATE IS FROM 24N-27N
BETWEEN 51W-54W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE
ELSEWHERE WITHIN 60 NM OF THE HANGING TROUGH. A LARGER AREA
OF CLOUDINESS AND EMBEDDED SCATTERED SHOWERS/TSTMS IS LOCATED TO
THE E OF THE SFC LOW IN AN UPPER DIFFLUENT ZONE BETWEEN 40W-51W
N OF 11N. A WEAK SFC TROUGH ALONG 56W FROM 8N-17N IS PRODUCING
SLIGHT CYCLONIC TURNING IN THE WINDS BUT OTHERWISE LITTLE
WEATHER.

THE ERN ATLC IS DOMINATED BY SFC RIDGING EXTENDING SWD FROM A
1028 MB HIGH NEAR THE AZORES. NE TO ELY TRADES ARE STRONGEST
BETWEEN THE CAPE VERDE ISLANDS AND ABOUT 25N AS REVEALED BY A
RECENT QSCAT PASS. THE MID AND UPPER FLOW IS MAINLY W TO NW
ACROSS THIS REGION BETWEEN RIDGING STRETCHING NWD FROM THE
EQUATOR...AND A LARGE UPPER TROUGH EXTENDING SW FROM EUROPE THRU
THE CANARY ISLANDS. STRONG FLOW BETWEEN THESE SYSTEMS IS
ADVECTING HIGH LEVEL CLOUDINESS MAINLY S OF 23N. A WEAK UPPER
LOW CENTERED NEAR 30N30W IS PRODUCING SIMILAR CLOUDINESS WITHIN
90 NM.

$$
CANGIALOSI




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