Tropical Weather Discussion
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000
AXNT20 KNHC 190004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU DEC 18 2014

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
2345 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH CROSSES THE AFRICAN COAST NEAR 08N13W AND
CONTINUES OVER THE EASTERN ATLANTIC TO NEAR 07N15W WHERE THE
ITCZ BEGINS AND CONTINUES ALONG 04N32W TO THE NORTHERN COAST OF
BRAZIL NEAR 03N51W. ISOLATED MODERATE CONVECTION IS FROM 02N-07N
E OF 16W AND FROM 01N-06N W OF 40W. SCATTERED MODERATE
CONVECTION IS FROM 01N-07N BETWEEN 20W AND 40W.

...DISCUSSION...

GULF OF MEXICO...

MIDDLE- TO UPPER-LEVEL SW TO W FLOW MOVES ACROSS THE BASIN AND
CONTINUES TO ADVECT MOISTURE FROM THE ITCZ IN THE EPAC TO THE
NORTHERN GULF WATERS. A 1014 MB SURFACE LOW IS OVER SOUTHERN
TEXAS FROM WHICH A STATIONARY FRONT EXTENDS ALONG 29N95W SE TO
27N91W TO 25N86W. LOW-LEVEL MOISTURE CONVERGENCE ASSOCIATED WITH
THE LOW ALONG WITH MOISTURE ALOFT SUPPORT SCATTERED MODERATE
CONVECTION AND ISOLATED TSTMS N OF 26N W OF 90W. A BROAD SURFACE
RIDGE COVERING THE CENTRAL AND EASTERN U.S. BEING ANCHORED BY A
1028 MB HIGH OVER CENTRAL ILLINOIS EXTENDS SE INTO THE NE GULF
WATERS. RETURN FLOW OF 5-15 KT ASSOCIATED WITH THE RIDGE
CONTINUES TO ADVECT DRY COOL AIR ACROSS THE REMAINDER
BASIN...WHICH ALONG DRY AIR SUBSIDENCE FROM ALOFT PROMOTE FAIR
WEATHER AND CLEAR SKIES. OVER THE NEXT 48 HOURS...THE LOW OVER
SOUTHERN TEXAS WILL TRACK E-NE ALONG THE NORTHERN GULF COASTLINE
WITH AN ASSOCIATED COLD FRONT TO EXTEND FROM SOUTHERN
MISSISSIPPI SW TO EASTERN-CENTRAL MEXICO COASTAL WATERS.

CARIBBEAN SEA...

THE FOCUS ON THE CARIBBEAN REMAINS TO BE A SURFACE TROUGH OVER
THE WESTERN BASIN EXTENDING FROM 20N84W TO 15N83W TO 11N82W. A
PLUME OF HIGH LOW-LEVEL MOISTURE EXTENDS FROM THE NW BASIN NEAR
20N85W SE TO 13N67W...WHICH CONVERGES ALONG THE NORTHERN TROUGH
TO ENHANCE SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS FROM
15N-21N BETWEEN 80W-86W. ANOTHER PLUME OF MOISTURE IS ENTERING
THE EASTERN CARIBBEAN BEING ADVECTED FROM AN AREA OF LOW
PRESSURE IN THE CENTRAL ATLC. THIS MOISTURE IS ENHANCING
SCATTERED SHOWERS ACROSS THE NE CARIBBEAN...INCLUDING PUERTO
RICO AND COASTAL WATERS. FAIR WEATHER PREVAILS ELSEWHERE ACROSS
THE BASIN BEING SUPPORTED BY DRY AIR SUBSIDENCE FROM ALOFT.
OTHERWISE...TRADES OF 15 KT DOMINATE ACROSS THE BASIN. THE
SURFACE TROUGH IS FORECAST TO DISSIPATE BY FRIDAY
MORNING...HOWEVER LINGERING MOISTURE ASSOCIATED WITH IT MAY
ENHANCE ISOLATED SHOWERS OVER THE NW BASIN THROUGH LATE SATURDAY.

HISPANIOLA...

BOTH TOTAL PRECIPITABLE WATER AND WATER VAPOR IMAGERY SHOW DRY
AIR ACROSS THE ISLAND WHICH HAVE STABILIZED THE ENVIRONMENT AND
IS PROMOTING FAIR WEATHER CONDITIONS. FAIR WEATHER IS FORECAST
TO CONTINUE THROUGH FRIDAY MORNING...THEN A MOIST AIRMASS MOVES
ACROSS THE ISLAND TO ENHANCE SHOWERS THROUGH SATURDAY AFTERNOON.

ATLANTIC OCEAN...

A CYCLONIC CIRCULATION ALOFT OVER THE NW ATLC CONTINUES TO
SUPPORT A LOW PRESSURE SYSTEM FROM WHICH A COLD FRONT EXTENDS
AND ENTER THE AREA OF DISCUSSION ALONG 30N62W SW TO 28N67W TO
26N74W. ISOLATED MODERATE CONVECTION IS WITHIN 180 NM EITHER
SIDE OF THE FRONT. SE OF THE FRONT...A 1019 MB HIGH IS NEAR
26N64W WHICH IS FORECAST TO REMAIN STATIONARY WITHIN THE NEXT 24
HOURS. OVER THE CENTRAL ATLC...A MIDDLE-LEVEL CYCLONE SUPPORTS A
SURFACE LOW OF 1014 MB NEAR 24N46W FROM WHICH A COLD FRONT
EXTENDS ALONG 22N45W TO 20N47W. A STATIONARY FRONT EXTENDS FROM
THE LOW NORTHWARD ALONG 28N44W TO 32N42W TO 42N30W. SCATTERED
MODERATE CONVECTION AND ISOLATED TSTMS ARE N OF 21N BETWEEN 36W-
47W. OTHERWISE...SURFACE RIDGING PREVAILS OVER THE EASTERN
BASIN. OVER THE NEXT 48 HOURS THE LOW OVER THE CENTRAL ATLANTIC
WILL MOVE NW WHILE THE FRONTS ASSOCIATED WITH THE LOW DISSIPATE.
CONVECTION WILL CONTINUE IN THE VICINITY OF THE LOW. A COLD
FRONT WILL EXIT THE SE CONUS AND WILL ENTER THE SW N ATLC.

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

$$
NR



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