Tropical Weather Discussion
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000
AXNT20 KNHC 201753
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT DEC 20 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE...

...GALE-FORCE WINDS IN THE EASTERN ATLANTIC OCEAN...

A 1009 MB LOW PRESSURE CENTER IS NEAR 30N45W. AN OCCLUDED FRONT
CURVES AWAY FROM THE LOW CENTER TO 29N45W 30N47W 32N46W...TO THE
TRIPLE POINT THAT IS NEAR 32N44W. A COLD FRONT CONTINUES FROM
32N44W TO 28N42W AND 22N41W. A MIDDLE LEVEL TO UPPER LEVEL
CYCLONIC CIRCULATION CENTER IS NEAR 31N45W. A TROUGH IS ALONG
32N48W...TO THE CYCLONIC CENTER...TO 26N43W AND 24N36W. ANOTHER
BRANCH OF A TROUGH PASSES THROUGH 26N43W TO 18N44W. CONVECTIVE
PRECIPITATION...NUMEROUS STRONG WITHIN A 30 NM TO 60 NM RADIUS
OF 32N46W. SCATTERED STRONG FROM 28N TO 30N BETWEEN 43W AND 45W.
WIDELY SCATTERED MODERATE TO ISOLATED STRONG ELSEWHERE FROM 21N
TO 30N BETWEEN 36W AND 42W.

EXPECT GALE-FORCE WINDS IN FORECAST WATERS WITHIN 150 NM IN THE
EAST SEMICIRCLE. SEA HEIGHTS WILL RANGE FROM 10 TO 17 FEET.
PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2/FZNT02 KNHC...FOR
MORE DETAILS.

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

THE MONSOON TROUGH REACHES THE COASTAL BORDER AREAS OF SIERRA
LEONE AND LIBERIA NEAR 7N11W. THE ITCZ CONTINUES FROM 7N11W TO
6N21W 5N32W 2N42W. CONVECTIVE PRECIPITATION...WIDELY SCATTERED
TO SCATTERED MODERATE AND ISOLATED STRONG WITHIN 120 NM ON
EITHER SIDE OF 4N15W 5N30W 7N37W 6N42W 3N46W 1N50W.

...DISCUSSION...

...FROM THE WESTERN ATLANTIC OCEAN...ACROSS FLORIDA...INTO THE
GULF OF MEXICO...AND INCLUDING THE REST OF THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N56W TO
30N58W AND 29N54W. THE TROUGH SUPPORTS A COLD FRONT THAT PASSES
THROUGH 32N58W TO 31N61W 30N70W AND 30N74W. A WARM FRONT
CONTINUES FROM 30N74W TO 31N78W AND 30N80W. A STATIONARY FRONT
CONTINUES FROM 30N80W...ACROSS FLORIDA...TO 29N84W AND 29N88W IN
THE GULF OF MEXICO...TO A 1014 MB LOW PRESSURE CENTER THAT IS
NEAR 28N89W. A COLD FRONT CONTINUES FROM THE LOW CENTER TO
25N93W...TO THE MEXICO GULF COAST NEAR 22N...CURVING INLAND TO
23N99W. A STATIONARY FRONT CONTINUES FROM 23N99W...ACROSS
MEXICO...TO THE TEXAS BIG BEND AND BEYOND. CONVECTIVE
PRECIPITATION...RAINSHOWERS ARE POSSIBLE TO THE NORTH AND
NORTHWEST OF THE LINE THAT PASSES THROUGH 30N63W TO 30N70W
28N80W 25N86W 25N90W 23N94W AND TO 18N94W.

MIDDLE LEVEL TO UPPER LEVEL SOUTHWESTERLY WIND FLOW IS MOVING
ACROSS THE ENTIRE AREA...ON TOP OF THE STATIONARY FRONT-TO-
1014 MB LOW PRESSURE CENTER NEAR 28N89W-TO COLD FRONT BOUNDARY.

FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE TO THE NORTH OF 27N
TO THE WEST OF 88W...

LOW LEVEL CLOUD CEILINGS ARE BEING REPORTED AT...KBBF...KGVX...
KXIH...KVAF...KEMK...KHQI...KGUL...KCRH...KGBK...KVQT...KGHB...
KGRY...KATP...KEIR...KSPR...KMDJ...KIPN...KVOA...KVKY...KMIS...
AND KDLP.

LOW LEVEL CLOUD CEILINGS AND WEATHER...FOR THE COASTAL PLAINS OF
THE U.S.A. FROM THE DEEP SOUTH OF TEXAS TO FLORIDA...

LOW LEVEL CLOUD CEILINGS COVER THE COASTAL PLAINS FROM THE DEEP
SOUTH OF TEXAS TO A LINE FROM MARIANNA FLORIDA TO APALACHICOLA
FLORIDA. RAIN IS BEING REPORTED BETWEEN ALABAMA AND
THE MARIANNA-TO-APALACHICOLA LINE.

...THE CARIBBEAN SEA...

A SURFACE TROUGH IS IN THE NORTHWESTERN CORNER OF THE CARIBBEAN
SEA ALONG 87W FROM 15N IN HONDURAS TO 23N IN THE SOUTHEASTERN
CORNER OF THE GULF OF MEXICO. THE TROUGH IS SPREADING BROKEN TO
OVERCAST MULTILAYERED CLOUDS INTO THE GULF OF MEXICO FROM 25N
SOUTHWARD FROM 90W EASTWARD...AND FROM CENTRAL GUATEMALA
NORTHWARD ACROSS THE YUCATAN PENINSULA OF MEXICO. CONVECTIVE
PRECIPITATION...ISOLATED MODERATE FROM COZUMEL NEAR 20N TO 24N
BETWEEN 84W AND 87W.

A MIDDLE LEVEL TO UPPER LEVEL RIDGE STARTS ALONG 80W IN
PANAMA...INTO THE WESTERN CARIBBEAN SEA NEAR 13N80W...CURVING
TOWARD THE SOUTHEASTERN CORNER OF CUBA...AND BEYOND 32N74W IN
THE ATLANTIC OCEAN.

MIDDLE LEVEL ANTICYCLONIC WIND FLOW COVERS THE CARIBBEAN SEA
FROM 76W EASTWARD.

COMPARATIVELY DRIER AIR IN SUBSIDENCE IS APPARENT IN WATER VAPOR
IMAGERY...EVERYWHERE EXCEPT FOR THAT PART THAT IS FROM 20N
NORTHWARD BETWEEN CUBA AND THE YUCATAN PENINSULA OF MEXICO.

RAINSHOWERS ARE POSSIBLE FROM 18N SOUTHWARD FROM CENTRAL
AMERICA/83W EASTWARD...IN SURFACE-TO-LOW LEVEL TRADEWIND FLOW.
THE 24-HOUR RAINFALL TOTAL IN INCHES FOR THE PERIOD ENDING AT
19/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES ARE...0.20 IN GUADELOUPE...AND 0.06 IN
CURACAO.

THE MONSOON TROUGH IS ALONG 8N75W IN COLOMBIA...BEYOND 6N82W
INTO THE EASTERN PACIFIC OCEAN. CONVECTIVE PRECIPITATION...
NUMEROUS STRONG IN THE EASTERN PACIFIC OCEAN FROM 4N TO 6N
BETWEEN COLOMBIA AND 80W.

...HISPANIOLA...

MIDDLE LEVEL TO UPPER LEVEL NORTHWESTERLY WIND FLOW IS MOVING
ACROSS HISPANIOLA. MIDDLE LEVEL EASTERLY WIND FLOW ALSO IS
MOVING ACROSS HISPANIOLA AT THE SAME TIME. COMPARATIVELY DRIER
AIR IN SUBSIDENCE IS APPARENT IN WATER VAPOR IMAGERY.

CLOUD CONDITIONS AND PREVAILING WEATHER...FOR PORT-AU-PRINCE IN
HAITI...FEW LOW LEVEL CLOUDS. FOR THE DOMINICAN REPUBLIC...FEW
LOW LEVEL CLOUDS IN BARAHONA. SCATTERED LOW LEVEL CLOUDS IN
SANTO DOMINGO...LA ROMANA...AND PUNTA CANA. FEW LOW LEVEL CLOUDS
ARE IN SANTIAGO. FEW LOW LEVEL CLOUDS AND A MIDDLE LEVEL CLOUD
CEILING ARE IN PUERTO PLATA.

THE GFS MODEL FORECAST FOR 250 MB SHOWS THAT NORTHWEST WIND FLOW
WILL CROSS HISPANIOLA DURING THE NEXT 48 HOURS. A RIDGE WILL
MOVE FROM THE WESTERN CARIBBEAN SEA...EVENTUALLY CROSSING
HISPANIOLA. THE GFS MODEL FORECAST FOR 500 MB SHOWS THAT BROAD
ANTICYCLONIC WIND FLOW WILL MOVE ACROSS HISPANIOLA. AN
ANTICYCLONIC CIRCULATION CENTER WILL START IN THE NORTHWESTERN
CORNER OF THE CARIBBEAN SEA/IN THE SOUTHERN PART OF THE YUCATAN
CHANNEL. IT IS FORECAST TO MOVE ACROSS CUBA...THE TURKS AND
CAICOS ISLANDS...AND END UP ON TOP OF PUERTO RICO. THE GFS MODEL
FORECAST FOR 700 MB SHOWS THAT BROAD ANTICYCLONIC WIND FLOW WILL
MOVE ACROSS HISPANIOLA. AN ANTICYCLONIC CIRCULATION CENTER WILL
START IN THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA. IT WILL
MOVE ACROSS NORTHWESTERN CUBA. IT WILL RE-FORM NEAR 24N71W...AND
IT WILL END UP NEAR 25N71W AT THE END OF THE 48-HOUR FORECAST
PERIOD.

...THE REST OF THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL RIDGE STARTS ALONG 80W IN
PANAMA...INTO THE WESTERN CARIBBEAN SEA NEAR 13N80W...CURVING
TOWARD THE SOUTHEASTERN CORNER OF CUBA...AND BEYOND 32N74W IN
THE ATLANTIC OCEAN. MIDDLE LEVEL TO UPPER LEVEL WESTERLY-TO-
NORTHWESTERLY WIND FLOW COVERS THE ATLANTIC OCEAN FROM 20N
NORTHWARD FROM 50W WESTWARD.

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 24N18W. CYCLONIC WIND FLOW IS MOVING AROUND THE CIRCULATION
CENTER FROM 20N NORTHWARD BETWEEN MAURITANIA AND 30W. NO
SIGNIFICANT DEEP CONVECTIVE PRECIPITATION IS APPARENT IN
SATELLITE IMAGERY.

BROAD SURFACE ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN
FROM 19N NORTHWARD BETWEEN AFRICA AND 40W. THE ANTICYCLONIC WIND
FLOW COVERS THE ATLANTIC OCEAN TO THE EAST OF THE 30N45W LOW
PRESSURE CENTER AND ASSOCIATED FRONTAL BOUNDARY.

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

$$
MT



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