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558
AXNT20 KNHC 200003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI DEC 19 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 THROUGH NORTHERN LIBERIA AND
CONTINUES OVER THE EASTERN ATLANTIC TO NEAR 07N12W WHERE THE
ITCZ BEGINS AND CONTINUES ALONG 05N26W TO 04N37W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 02N-07N E OF 35W.

...DISCUSSION...

GULF OF MEXICO...

MIDDLE- TO UPPER-LEVEL SW TO W FLOW CONTINUES TO MOVE ACROSS THE
BASIN AND ADVECTS MOISTURE FROM THE ITCZ IN THE EPAC TO A GREAT
PORTION OF GULF WATERS. A 1013 MB SURFACE LOW IS OVER SE TEXAS
COASTAL WATERS NEAR 28N94W FROM WHICH A COLD FRONT EXTENDS SW TO
SOUTHERN TEXAS NEAR 26N97W THEN CONTINUING OVER NORTHERN MEXICO.
A STATIONARY FRONT EXTENDS EASTWARD FROM THE LOW ALONG 28N90W TO
28N85W. LOW-LEVEL MOISTURE CONVERGENCE ASSOCIATED WITH THE LOW
AND ALONG THE STATIONARY FRONT ENHANCE ISOLATED SHOWERS N OF 26N
E OF 94W AND FOG ELSEWHERE W OF THE LOW. A BROAD SURFACE RIDGE
COVERING THE EASTERN U.S. BEING ANCHORED BY A 1028 MB HIGH OVER
CENTRAL ILLINOIS IS PROVIDING RETURN FLOW OF 5-20 KT ACROSS THE
BASIN AND ADVECT DRY COOL AIR TO SOUTHERN PORTIONS OF THE GULF
WATERS. DRY AIR SUBSIDENCE FROM ALOFT OVER THE SOUTHERN GULF
PROMOTES FAIR WEATHER AND MOSTLY CLEAR SKIES. HOWEVER...HIGH
MOISTURE ASSOCIATED WITH AN AREA OF LOW PRESSURE OVER THE NW
CARIBBEAN MOVING NW IS SUPPORTING CLOUDINESS AND ISOLATED
SHOWERS ACROSS THE YUCATAN CHANNEL. OVER THE NEXT 24 HOURS...THE
LOW WILL TRACK E-NE ALONG THE NORTHERN GULF COASTLINE WITH THE
ASSOCIATED COLD FRONT EXTENDING SW TO EASTERN-CENTRAL MEXICO
COASTAL WATERS. BY SUNDAY MORNING THE COLD FRONT IS FORECAST TO
TRANSITION INTO A STATIONARY FRONT. A LOW WILL REFORM OVER THE
NE BASIN BY SUNDAY MORNING WITH THE EASTERN PART OF THE FRONT
BECOMING A WARM FRONT. SHOWERS ARE EXPECTED TO CONTINUE ACROSS
THE NORTHERN GULF WATERS THROUGH THIS PERIOD.

CARIBBEAN SEA...

THE FOCUS ON THE CARIBBEAN IS A SURFACE 1011 MB LOW E OF BELIZE
NEAR 18N87W WITH ASSOCIATED TROUGH EXTENDING ALONG 21N85W TO THE
LOW TO 16N87W. DEEP LAYER MOISTURE IN THE FAR WESTERN BASIN
ENHANCES SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS N OF
16N W OF 80W. A MOIST AIRMASS CONTINUES TO MOVES ACROSS THE FAR
EASTERN CARIBBEAN BEING ADVECTED FROM AN AREA OF LOW PRESSURE IN
THE CENTRAL ATLC. THIS MOISTURE MAY ENHANCE ISOLATED SHOWERS
ACROSS THIS REGION OF THE BASIN...INCLUDING PUERTO RICO. FAIR
WEATHER PREVAILS ELSEWHERE ACROSS THE BASIN BEING SUPPORTED BY
DRY AIR SUBSIDENCE FROM ALOFT. OTHERWISE...TRADES OF 15 KT
DOMINATE ACROSS THE BASIN...INCREASING TO 20 KT ALONG THE COAST
OF COLOMBIA. THE LOW IS FORECAST TO MOVE NW INTO THE YUCATAN
PENINSULA BY SATURDAY AFTERNOON BUT LINGERING MOISTURE
ASSOCIATED WITH IT MAY CONTINUE TO ENHANCE SHOWERS OVER THE NW
BASIN THROUGH EARLY SUNDAY.

HISPANIOLA...

A SHALLOW MOIST AIRMASS IS MOVING ACROSS THE ISLAND SUPPORTING
CLOUDINESS AND POSSIBLE ISOLATED SHOWERS. NO DEEP CONVECTION IS
EXPECTED DUE TO STRONG DRY AIR SUBSIDENCE FROM ALOFT. FAIR
WEATHER IS FORECAST TO RESUME BY SATURDAY AFTERNOON.

ATLANTIC OCEAN...

A BROAD MIDDLE-LEVEL TROUGH OVER THE W ATLC CONTINUES TO SUPPORT
A SURFACE PRE-FRONTAL TROUGH ALONG 33N53W SW TO 28N60W TO
26N69W. SCATTERED SHOWERS ARE N OF 26N BETWEEN 55W-75W. OVER THE
CENTRAL ATLC...A MIDDLE-LEVEL CYCLONIC CIRCULATION CONTINUES TO
SUPPORT A SURFACE LOW OF 1014 MB NEAR 26N46W FROM WHICH A COLD
FRONT EXTENDS ALONG 25N43W TO 20N42W. A WARM FRONT EXTENDS FROM
THE LOW NORTHWARD ALONG 30N46W TO 37N41W. SCATTERED MODERATE
CONVECTION AND ISOLATED TSTMS ARE WITHIN 400 NM OF THE LOW
EASTERN SEMICIRCLE. OTHERWISE...SURFACE RIDGING PREVAILS OVER
THE EASTERN BASIN. OVER THE NEXT 24 HOURS THE LOW OVER THE
CENTRAL ATLANTIC WILL MOVE NW N OF THE AREA OF DISCUSSION.
CONVECTION WILL CONTINUE IN THE VICINITY OF THE LOW.

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

$$
NR




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