[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 062321
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN DEC 06 2015

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...ITCZ/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N13W TO
06N25W TO 05N35W TO 02N50W. A SURFACE TROUGH IS ANALYZED NORTH
OF THE AXIS FROM 11N47W TO 07N48W. SCATTERED MODERATE CONVECTION
IS FROM 04N-10N BETWEEN 13W-21W. SCATTERED SHOWERS ARE OCCURRING
IN THE VICINITY OF THE SURFACE TROUGH FROM 07N-11N BETWEEN 43W-
50W.

...DISCUSSION...

GULF OF MEXICO...

A STATIONARY FRONT EXTENDS FROM THE STRAITS OF FLORIDA TO JUST N
OF THE YUCATAN CHANNEL TO 1019 MB LOW PRESSURE NEAR 21.5N89.5W
THEN CONTINUES ACROSS THE WESTERN YUCATAN PENINSULA TO NORTHWEST
GUATEMALA NEAR 17N91W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE
OCCURRING WITHIN 60-90 NM EITHER SIDE OF THE FRONT. A SURFACE
TROUGH HAS BECOME MORE EVIDENT SINCE 06/2100 UTC EXTENDING FROM
THE CENTRAL GULF NEAR 26.5N87W TO 23.5N87.5W. A CLUSTER OF TSTMS
HAS DEVELOPED FROM 24N-27N BETWEEN 85W-88W WITH INTENSE
LIGHTNING NOTED. BROAD SURFACE RIDGING DOMINATES THE REMAINDER
OF THE BASIN ALONG WITH FAIR WEATHER. A MODERATE TO FRESH NE
FLOW PREVAILS ACROSS THE BASIN AS NOTED IN LATEST SCATTEROMETER
DATA AND SURFACE OBSERVATIONS...EXCEPT ALONG AND JUST OFFSHORE
OF THE COAST OF VERACRUZ WHERE WINDS ARE INCREASING TO 20-30 KT
DUE TO A LOCALIZED TIGHT PRESSURE GRADIENT. A SIMILAR WEATHER
REGIME IS EXPECTED OVER THE NEXT 24-48 HOURS.

CARIBBEAN SEA...

MIDDLE TO UPPER-LEVEL RIDGING IS NOTED ON WATER VAPOR IMAGERY
OVER THE W CARIBBEAN WITH AN AXIS EXTENDING ACROSS CENTRAL CUBA
TO THE SW ACROSS THE GULF OF HONDURAS. TO THE E...A BROAD UPPER
LEVEL LOW IS CENTERED JUST S-SE OF PUERTO RICO AND THE VIRGIN
ISLANDS NEAR 16.5N66W. AT THE SURFACE...THE PROXIMITY OF A
STATIONARY FRONT EXTENDING FROM JUST N OF THE YUCATAN CHANNEL TO
OVER THE WESTERN YUCATAN PENINSULA AND DIVERGENT FLOW ALOFT IS
HELPING TO SUPPORT SCATTERED SHOWERS AND ISOLATED TSTMS W OF
85W. SHALLOW MOISTURE TRANSPORTED BY THE MODERATE TO FRESH
TRADES IS SUPPORTING ISOLATED ACTIVITY FROM 12N-18N BETWEEN 81W-
85W...WITH ADDITIONAL ISOLATED ACTIVITY OVER THE NE CARIBBEAN
ISLANDS AHEAD OF AN UPPER LEVEL TROUGH ROTATING AROUND THE UPPER
LOW. THE PRESSURE GRADIENT REMAINS RELATIVELY TIGHT OVER THE
CENTRAL PORTION OF THE BASIN BETWEEN 68W-82W WITH LOW PRESSURE
POSITIONED OVER NORTHERN COLOMBIA AND CENTRAL ATLC RIDGING
EXTENDING NE OF THE AREA. THIS PATTERN IS SUPPORTING FRESH TO
STRONG TRADES ACROSS THIS AREA...EVEN NEAR GALE JUST NW OF THE
COAST OF COLOMBIA. MODERATE TO FRESH TRADES PREVAIL E OF 68W
WITH MAINLY GENTLE N-NE FLOW W OF 82W AROUND BROAD SURFACE
TROUGHING. A SIMILAR WEATHER PATTERN WILL PREVAIL OVER THE NEXT
24 HOURS...WITH WINDS THEN GRADUALLY DIMINISHING THROUGH 48
HOURS AS THE PRESSURE GRADIENT SLACKENS.

...HISPANIOLA...

AN UPPER LEVEL LOW IS CENTERED S-SE OF PUERTO RICO AND THE
VIRGIN ISLANDS ALLOWING FOR MOSTLY CLEAR SKIES TO PREVAIL ACROSS
HISPANIOLA...EXCEPT FOR A FEW ISOLATED TSTMS THAT DEVELOPED
EARLY THIS AFTERNOON DUE TO SHALLOW MOISTURE TRANSPORTED BY
EASTERLY FLOW ENCOUNTERING OROGRAPHIC LIFTING. THE UPPER LEVEL
LOW WILL WEAKEN OVER THE NEXT 24 HOURS AS UPPER LEVEL RIDGING
SETTLES IN WHICH SHOULD RESULT IN AN OVERALL DRYING TREND.

ATLANTIC OCEAN...

A COLD FRONT EXTENDS FROM 32N40W TO 27N53W THEN CONTINUES AS A
STATIONARY FRONT TO 1020 MB LOW PRESSURE NEAR 31.5N64W. A COLD
FRONT EXTENDS FROM THIS LOW TO 1019 MB LOW PRESSURE NEAR
29N71.5W WHERE IT THEN CONTINUES AS A STATIONARY FRONT TO ACROSS
THE CENTRAL BAHAMAS THEN REACHING THE STRAITS OF FLORIDA.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 90 NM
SE OF THE BOUNDARIES W OF 60W...WITH ISOLATED TO SCATTERED
SHOWERS WITHIN 60-120 NM EITHER SIDE OF THE BOUNDARIES E OF 60W.
TO THE E...AN UPPER LEVEL TROUGH EXTENDING FROM 32N21W TO THE
CAPE VERDE ISLANDS SUPPORTS A LAGGING SURFACE TROUGH FROM 24N27W
TO 16N28W. NO CONVECTION IS NOTED WITH THE SURFACE TROUGH...
HOWEVER DIFFLUENT FLOW ALOFT SUPPORTS SCATTERED MODERATE
CONVECTION E OF THE UPPER FEATURE N OF 15N. FRESH TO STRONG NE
WINDS PREVAIL W OF THE STATIONARY FRONT IN THE SW N ATLANTIC
WITH MODERATE E-SE FLOW TO THE SE OF THE BOUNDARY. THE FRONT
WILL LINGER IN THE SAME GENERAL AREA THROUGH MONDAY WITH WINDS
DIMINISHING TO MAINLY MODERATE AS THE PRESSURE GRADIENT WEAKENS.
A DRY COLD FRONT WILL MOVE OFF THE SE U.S. COAST MONDAY NIGHT
THROUGH TUESDAY...GRADUALLY MERGING WITH THIS OLD FRONTAL
BOUNDARY BY EARLY WEDNESDAY.

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

$$
LEWITSKY
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