[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 070001
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU MAR 06 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.

...SPECIAL FEATURE...

A GALE IS FORECAST TO BEGIN OVERNIGHT FRI NIGHT OVER THE SW N
ATLANTIC N OF 27N WITHIN 150 NM E OF A FRONT THAT WILL EXTEND
FROM 31N68W TO 21N78W. PLEASE SEE THE HIGH SEAS FORECAST UNDER
AWIPS/WMO HEADERS MIAHSFAT2/FZNT01 KNHC OR THE OFFSHORE FORECAST
UNDER AWIPS/WMO HEADERS MIAOFFNT3/FZNT23 KNHC FOR MORE DETAILS.

THE GALE FORECAST EARLIER FOR THE METEO FRANCE AREAS OF IRVING
AND MADIERA...N OF 30N BETWEEN 22W-35W IS NO LONGER IN EFFECT.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC
NEAR 7N12W AND CONTINUES ALONG 5N18W TO 3N20W TO 1N27W...WHERE
THE ITCZ BEGINS AND CONTINUES TO THE EQUATOR AT 39W...THEN DIPS
TO THE COAST OF SOUTH AMERICA NEAR 2S44W. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE FROM THE EQUATOR TO THE
MONSOON TROUGH BETWEEN 14W-27W.

...DISCUSSION...

GULF OF MEXICO...
AMPLIFIED PATTERN IN PLACE OVER THE E CONUS WITH A SHARP UPPER
TROUGH EXTENDING FROM A WELL DEFINED CYCLONIC CIRCULATION OVER E-
CENTRAL MISSISSIPPI NEAR 32N89W THROUGH 25N91W TO A BASE OVER
THE E PACIFIC NEAR 15N103W. VERY STRONG SUBSIDENCE WAS WRAPPING
AROUND THE BASE AND THE EAST SIDE OF THE TROUGH. AXIS OF
SUBTROPICAL JET CUT THROUGH THE BASE OF THE TROUGH THEN TURNED
NNE ACROSS THE BIG BEND/NORTHERN FLORIDA WITH CORE SPEEDS OF 120-
130 KT. THE TROUGH PROVIDED SUPPORT FOR A COLD FRONT WHICH
EXTENDED FROM COMPLEX LOW PRESSURE...1008 MB NEAR 28N85W TO THE
YUCATAN PENINSULA NEAR 21N88W. A QUASI-STATIONARY FRONT EXTENDS
FROM THE LOW NW OVER THE NORTH-CENTRAL FLORIDA TO ANOTHER LOW
PRESSURE...1006 MB NEAR GAINESVILLE. A SURFACE TROUGH EXTENDS
FROM THE LOW NORTHWEST TO NEAR MOBILE ALABAMA. FLOW BETWEEN
UPPER LEVEL RIDGE AND TROUGH WAS DIFFLUENT AND HAD PROVIDED
SUPPORT FOR A SQUALL LINE WHICH MOVED ACROSS SOUTH FLORIDA AND
IS NOW OVER THE CENTRAL BAHAMAS. WSR-88D DATA ALSO INDICATED AN
AREA OF SCATTERED SHOWERS OVER EXTREME SE
LOUISIANA...MISSISSIPPI AND ALABAMA IN PROXIMITY TO THE UPPER
LOW. ELSEWHERE...A SURFACE RIDGE IS BUILDING S FROM THE CENTRAL
PLAIN STATES OVER MEXICO AND THE W GULF WITH MODERATE TO FRESH
NORTHERLY WINDS IN ITS WAKE. BROKEN TO OVERCAST LOW AND MID
CLOUDS WERE NOTED W OF THE FRONT AND WERE MOVING CYCLONICALLY
AROUND THE S SIDE OF THE MID TO UPPER LEVEL CYCLONE. COMPLEX LOW
PRESSURE WILL MOVE NE OF THE AREA AND INTENSIFY OVER THE SW N
ATLANTIC ON FRI. THE COLD FRONT WILL MOVE OUT OF THE GULF EARLY
FRI WITH SURFACE RIDGE WILL CONTINUING TO BUILD IN THE WAKE OF
THE FRONT THROUGH SAT. A NEW COLD FRONT WILL MOVE INTO THE W
GULF SUN.

CARIBBEAN SEA...
A BROAD UPPER RIDGE REMAINS OVER THE CARIBBEAN WITH ASSOCIATED
RIDGE AXIS EXTENDING N OVER THE SW N ATLANTIC W OF 55W. WATER
VAPOR IMAGERY CONTINUES TO SHOW VERY DRY AND STABLE AIR ALOFT
ACROSS ALL BUT THE FAR NW CARIBBEAN WHERE A LINE OF SCATTERED
THUNDERSTORMS WAS NOTED WITHIN 60 NM EITHER SIDE OF A LINE FROM
EXTREME NW CUBA TO THE NE YUCATAN PENINSULA. LOCAL CONVERGENCE
IN THE EASTERLY TRADE WINDS WERE GENERATING ISOLATED LOW TOP
SHOWERS OVER WESTERN HISPANIOLA AND E CUBA AND OVER THE NE
LEEWARD ISLANDS. A 1422 UTC ASCAT PASS INDICATED FRESH TRADES
WITHIN 90-120 NM OF THE COAST OF COLOMBIA...AND MODERATE TO
FRESH TRADES ELSEWHERE OVER THE CARIBBEAN E OF 70W. LIGHT TO
MODERATE TRADES NOTED ELSEWHERE OF THE CARIBBEAN. A WEAK COLD
FRONT WILL MOVE INTO THE NW CARIBBEAN TONIGHT AND STALL FROM
CENTRAL CUBA TO THE GULF OF HONDURAS FRI NIGHT AND THEN BEGIN TO
DISSIPATE FROM THE WINDWARD PASSAGE TO THE GULF OF HONDURAS
SAT.

HISPANIOLA...
SCATTERED WARM TOP SHOWERS WERE FOCUSED OVER HAITI...THE
WINDWARD PASSAGE AND EASTERN CUBA. 1200 UTC RAWINSONDE FROM SAN
JUAN INDICATED LOW LEVEL MOISTURE UP TO 750 MB WITH VERY STRONG
CAPPING/DRYING ABOVE THAT LEVEL. PRECIPITABLE WATER VALUES WERE
WELL BELOW NORMAL AT 1.07 INCHES. THE DRY AIR WAS REFLECTED IN
WATER VAPOR IMAGERY WHICH DEPICTED STRONG SUBSIDENCE AMIDST
MODERATE WESTERLY FLOW ALOFT. THE PROXIMITY OF A DISSIPATING
COLD FRONT IN THE WINDWARD PASSAGE MAY INCREASE SHOWER ACTIVITY
IN THE AREA ON SAT.

ATLANTIC OCEAN...
A BROAD UPPER RIDGE OVER THE CARIBBEAN WITH ASSOCIATED RIDGE
AXIS EXTENDING N OVER THE SW N ATLANTIC W OF 55W. FLOW BETWEEN
UPPER LEVEL RIDGE AND TROUGH WAS DIFFLUENT AND HAD PROVIDED
SUPPORT FOR A SQUALL LINE WHICH MOVED ACROSS SOUTH FLORIDA AND
IS NOW OVER THE CENTRAL BAHAMAS. A COLD FRONT ENTERS THE SW N
ATLC NEAR 32N62W TO 29N71W WHERE IT BECOMES QUASI STATIONARY TO
A 1006 MB LOW OVER NORTH-CENTRAL FLORIDA NEAR GAINESVILLE. THE
PRE-FRONTAL SQUALL LINE NOTED ABOVE EXTENDED FROM NEAR VERO
BEACH FLORIDA TO WITHIN 45 NM OF THE COAST OF SE FLORIDA AND
ACROSS THE MID AND UPPER FLORIDA KEYS. THE THUNDERSTORM ACTIVITY
HAS RACED EASTWARD ACROSS THE NORTHERN AND CENTRAL BAHAMAS AND
EXTENDS WITHIN 45-60 NM EITHER SIDE OF A LINE FROM BIMINI TO
31N77W. EXTENDS OVER THE W AND CENTRAL ATLC PROVIDING DIFFLUENCE
ALOFT TO ENHANCE SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS OVER
THE FAR W ATLC N OF 27N W OF 75W. AN UPPER TROUGH OVER THE E
ATLC EXTENDS FROM AN UPPER LOW W OF THE CANARY ISLANDS NEAR
28N21W TO THE W ATLC NEAR 15N52W. A SURFACE RIDGE DOMINATES THE
REMAINDER OF THE ATLC ANCHORED BY A 1028 MB HIGH NEAR THE AZORES
AND A 1024 MB HIGH NEAR 28N48W. THE SW N ATLC FRONT WILL LIFT N
TONIGHT AHEAD OF AN INTENSIFYING SURFACE LOW CURRENTLY IN THE
GULF OF MEXICO...EXPECTED TO TRACK NE ALONG THE GEORGIA AND
CAROLINA COASTS. THE ASSOCIATED COLD FRONT WILL REACH FROM NEAR
31N72W TO CENTRAL CUBA BY FRI EVENING THEN FROM 31N66W TO 25N70W
THEN WEAKENING TO FAR EASTERN CUBA BY EARLY SAT AND CONTINUING
TOWARD THE CENTRAL ATLC SAT AND SUN.

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

$$
COBB

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