[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 011750
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT DEC 01 2012

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN 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.

...SPECIAL FEATURES...

A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDS FROM 33N48W TO
24N39W AND SUPPORTS A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION
CENTERED ANALYZED AS A 1010 MB LOW NEAR 26N42W. SURFACE
TROUGHING EXTENDS N-NE FROM THE LOW TO 30N40W AND S-SW FROM THE
LOW TO 18N46W AS DEPICTED ON A RECENT ASCAT PASS FROM 01/1258
UTC. SCATTERED MODERATE CONVECTION IS OCCURRING FROM 26N-32N
BETWEEN 35W-45W LOCATED MOSTLY IN THE AREA OF MAXIMUM MIDDLE TO
UPPER LEVEL DIFFLUENCE EAST OF THE TROUGH AXIS. ELSEWHERE
ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 240 NM EAST OF
THE SOUTHERN SURFACE TROUGH AXIS. THIS SYSTEM IS GRADUALLY
BECOMING BETTER ORGANIZED AND FURTHER DEVELOPMENT IS POSSIBLE
OVER THE NEXT 24 TO 48 HOURS BEFORE IT MERGES WITH A FRONTAL
SYSTEM TO THE NORTHWEST. THIS SYSTEM HAS A MEDIUM CHANCE OF
BECOMING A TROPICAL CYCLONE OR A SUBTROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
10N14W TO 06N18W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 06N18W TO 04N23W TO 08N33W TO 06N40W TO 09N48W TO
07N59W. TWO SURFACE TROUGHS ARE EMBEDDED WITHIN THE ITCZ. ONE IS
ANALYZED FROM 06N35W TO 12N30W AND SHOWS UP WELL IN AN EARLIER
ASCAT PASS FROM 01/1122 UTC. THE OTHER SURFACE TROUGH EXTENDS
FROM 07N50W TO A 1010 MB LOW CENTERED NEAR 09N48W TO 12N44W. THE
LOW-LEVEL CIRCULATION IS QUITE EVIDENT ON VISIBLE SATELLITE
IMAGERY AND AN ASCAT PASS AROUND 01/1302 UTC SHOWED THE EASTERN
PORTION OF THE CYCLONIC TURNING OF THE WIND FIELD. WIDELY
SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 10N BETWEEN
09W-32W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES THE GULF IS UNDER NORTHWEST TO
WESTERLY UPPER LEVEL FLOW AND THAT A RELATIVELY DRY AND STABLE
AIRMASS REMAINS IN CONTROL. AT THE SURFACE...STABILITY REMAINS
THE OVERALL THEME AS A HIGH PRESSURE RIDGE AXIS EXTENDS FROM THE
CAROLINAS THROUGH THE MISSISSIPPI DELTA REGION TO THE EAST-
CENTRAL MEXICO COAST NEAR 20N98W WHERE A 1022 MB HIGH IS
CENTERED. MOSTLY EAST-NORTHEAST WINDS IN THE RANGE OF 10 TO 20
KT PREVAIL E OF 92W WITH FAIR CONDITIONS OBSERVED...AND EAST-
SOUTHEAST WINDS IN THE RANGE OF 5 TO 15 KT PREVAIL W OF 92W
UNDER MOSTLY CLEAR SKIES. THE ONLY AREA OF ACTIVE PRECIPITATION
IS A FEW ISOLATED SHOWERS AND TSTMS ACROSS THE FLORIDA STRAITS E
OF 84W. THIS SYNOPTIC WEATHER PATTERN IS FORECAST TO PERSIST
THROUGH WEDNESDAY.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE AXIS EXTENDS ALONG 10N BETWEEN 55W-90W THAT
PROVIDES INFLUENCE TO THE ENTIRE CARIBBEAN SEA BASIN THIS
AFTERNOON WHERE MOSTLY SOUTHWEST TO WESTERLY UPPER LEVEL FLOW
PREVAILS. WHILE EASTERN PORTIONS REMAIN DRY ALOFT...ISOLATED
LOW-LEVEL LOW-TOPPED SHOWERS CONTINUE PROGRESSING WESTWARD
EMBEDDED WITHIN E-NE TRADES IN THE RANGE OF 10 TO 15 KT. THE
WESTERN CARIBBEAN IS EXPERIENCING INCREASED CLOUD COVER OVERALL
WITH ISOLATED SHOWERS OCCURRING IN THE GULF OF HONDURAS AND
SURROUNDING REGION S OF 19N W OF 83W...AND ISOLATED SHOWERS AND
TSTMS ACROSS THE SW CARIBBEAN GENERALLY S OF 14N W OF 79W AND
WITHIN 90 NM OF THE PANAMA COAST. FINALLY...AN AREA OF LOW-LEVEL
MOISTURE CONVERGENCE IS FOUND ACROSS PORTIONS OF THE SE
CARIBBEAN AND COAST OF VENEZUELA. ISOLATED SHOWERS AND TSTMS ARE
OCCURRING S OF 13N BETWEEN 57W-66W...INCLUDING TRINIDAD AND
TOBAGO AS WELL AS NE VENEZUELA.

ATLANTIC OCEAN...
WATER VAPOR IMAGERY INDICATES VERY WEAK MIDDLE TO UPPER LEVEL
TROUGH ACROSS THE SW NORTH ATLC WITH THE TROUGH AXIS EXTENDING
FROM 36N73W TO 24N83W. WITH A LACK OF ANY SIGNIFICANT SURFACE
FRONT EAST OF THE UPPER LEVEL TROUGH AXIS...INCREASED MID-LEVEL
LIFT IS GENERATING CLOUDINESS AND ISOLATED AREAS OF LOW-TOPPED
SHOWERS N OF 21N BETWEEN 60W-80W. THE MOST CONCENTRATED AREA OF
WIDELY SCATTERED SHOWERS IS OCCURRING ALONG AND NORTH OF A SHEAR
LINE ANALYZED FROM 31N49W TO 26N60W TO 23N71W. THIS AREA IS
FOUND FROM 23N-28N BETWEEN 55W-72W. A WEAK SURFACE TROUGH IS
LOCATED SOUTH OF THE SHEAR LINE FROM 19N-23N ALONG 68W WITH
ISOLATED SHOWERS OCCURRING WITHIN 300 NM EAST OF THE BOUNDARY.
FARTHER EAST...THE SPECIAL FEATURES LOW PRESSURE SYSTEM IS
CONTINUING TO TRACK SLOWLY NORTHWARD AND IS EXPECTED TO IMPACT
THE AREA N OF 20N BETWEEN 35W-48W. OTHERWISE...THE REMAINDER OF
THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE
ANCHORED BY A 1034 MB HIGH CENTERED NE OF THE AZORES NEAR 40N25W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
HUFFMAN



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