[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 282341
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI MAR 28 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
2245 UTC.

...SPECIAL FEATURES...

...CARIBBEAN SEA GALE WARNING...
A TIGHT PRESSURE GRADIENT IS FOUND OVER THE SOUTH CENTRAL
CARIBBEAN SEA BETWEEN A RIDGE EXTENDING FROM STRONG 1036 MB HIGH
PRESSURE CENTERED IN THE CENTRAL ATLC NEAR 36N57W TO THE GULF OF
HONDURAS AND LOWER PRESSURE ACROSS THE NORTHWESTERN SOUTH
AMERICAN CONTINENT. GALE FORCE WINDS ARE CURRENTLY FOUND ALONG
THE COAST OF COLOMBIA AS A RESULT OF THIS TIGHT PRESSURE
GRADIENT. WINDS HERE ARE EXPECTED TO DIMINISH BELOW GALE FORCE
BY SATURDAY AFTERNOON. SEE LATEST NWS HIGH SEAS FORECAST UNDER
AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS.

...ATLANTIC OCEAN GALE WARNING...
PLEASE REFER TO THE METEO-FRANCE HIGH SEAS FORECAST THAT IS
LISTED UNDER GRAND LARGE METAREA 2 FOR THE SECTIONS THAT ARE
TITLED...MADEIRA AND AGADIR. GALE CONDITIONS CAN BE FOUND IN
THOSE AREAS.

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

THE MONSOON TROUGH PASSES OFF THE COAST OF AFRICA NEAR 07N11W
AND CONTINUES SOUTHWEST TO THE EQUATOR NEAR 21W. NO SIGNIFICANT
CONVECTION CAN BE FOUND NEAR THE MONSOON TROUGH.

...DISCUSSION...

GULF OF MEXICO...
DIFFLUENT FLOW ALOFT OVER THE NORTHEAST GULF OF MEXICO IS
ENHANCING THUNDERSTORM ACTIVITY. LAND-BASED RADARS WERE USED TO
ANALYZE A SQUALL LINE ACROSS THE FLORIDA PANHANDLE ALONG 85.5W
AND INTO THE GULF NEAR 29N86W. FRESH TO STRONG SOUTHERLY WINDS
OVER THE SOUTHEASTERN GULF ARE FEEDING MOISTURE INTO THIS AREA
OF THUNDERSTORMS. THE PATTERN SHOULD CHANGE LITTLE HERE UNTIL
MIDDAY SATURDAY WHEN A COLD FRONT WILL SWING THROUGH THE AREA.
THIS COLD FRONT WILL MOVE INTO THE NW GULF OVERNIGHT
TONIGHT...BUT WINDS W OF THE FRONT ARE NOT EXPECTED TO INCREASE
TO A FRESH TO STRONG BREEZE UNTIL SAT EVENING WHEN THE UPPER
TROUGH SUPPORTING THE FRONT IS FORECAST TO AMPLIFY AS IT PASSES
N OF THE GULF OF MEXICO. THE FRONT WILL REACH FROM THE FLORIDA
BIG BEND TO THE YUCATAN PENINSULA LATE SAT AND PASS SE OF THE
AREA ON SUN. HIGH PRESSURE AND DRIER CONDITONS WILL MOVE IN
BEHIND THE FRONT.

CARIBBEAN SEA...
WEST TO NORTHWESTERLY FLOW ALOFT IS OVER THE CARIBBEAN BASIN
WITH WATER VAPOR IMAGERY INDICATING RELATIVELY DRY AIR AND A
SUBSIDENT ENVIRONMENT IN PLACE SOUTH OF 15N...WITH LINGERING
MOISTURE N OF 15N ASSOCIATED WITH A WEAKENING MID-LEVEL
CONVERGENCE ZONE STRETCHED FROM THE CENTRAL ATLC INTO THE NW
CARIBBEAN. THERE IS NO SIGNIFICANT DEEP CONVECTION NOTED OVER
THE CARIBBEAN AND ONLY ISOLATED SHOWERS FOUND MAINLY IN THE FAR
EASTERN CARIBBEAN AND FROM 17N-21N WEST OF JAMAICA TO 85W.
FARTHER SOUTH...A GALE WARNING IN EFFECT THROUGH SATURDAY
MORNING FOR THE SOUTHERN CARIBBEAN WATERS OFF THE COAST OF
COLOMBIA. SEE THE SPECIAL FEATURES SECTION ABOVE FOR DETAILS.
THE STRONG PRESSURE GRADIENT BETWEEN THE AFOREMENTIONED SURFACE
RIDGE OVER THE NW CARIBBEAN AND LOWER PRESSURE OVER NORTHWESTERN
SOUTH AMERICA IS ALSO DRIVING FRESH TO STRONG TRADE WINDS OVER
THE REMAINDER OF THE CENTRAL CARIBBEAN INCLUDING THE WINDWARD
PASSAGE. LOOK FOR THESE WINDS TO DIMINISH AS THE RIDGE WEAKENS
AHEAD OF A COLD FRONT FORECAST TO MOVE INTO THE NW CARIBBEAN SUN
AFTERNOON. THE CHANCE OF PRECIPITATION IN THE NORTHWEST
CARIBBEAN IS EXPECTED TO INCREASE BEGINNING SATURDAY NIGHT AHEAD
OF THE FRONT.

...HISPANIOLA...
CURRENTLY...ISOLATED SHOWERS ARE PRIMARILY FOUND OVER THE
NORTHERN PORTION OF HAITI AND ON THE SOUTHEASTERN SLOPES OF THE
HIGHEST TERRAIN IN THE CENTRAL DOMINICAN REPUBLIC. THESE SHOWERS
CONTINUE TO BE FUELED BY MOISTURE ASSOCIATED WITH A WEAKENING
MID-LEVEL CONVERGENCE ZONE STRETCHED FROM THE CENTRAL ATLC INTO
THE NW CARIBBEAN. ISOLATED SHOWERS ARE FORECAST TO CONTINUE
SATURDAY BUT ARE EXPECTED SHIFT EAST OF THE AREA ON SUNDAY AS
MOISTURE POOLS EASTWARD AHEAD OF THE COLD FRONT FORECAST TO MOVE
INTO THE NW CARIBBEAN SEA.

ATLANTIC OCEAN...
THE UPPER PATTERN OVER THE ATLC FEATURES WEAK TROUGHING
EXTENDING FROM JUST EAST OF BERMUDA TO JUST NORTHEAST OF THE
CENTRAL BAHAMAS AND A BROADER WEAK TROUGH CENTERED ALONG 52W.
THESE TROUGHS ARE EXPECTED TO MERGE SATURDAY...PRODUCING A MORE
AMPLIFIED PATTERN FEATURING RIDGING FROM THE BAHAMAS TO BERMUDA
AND A DEEPENING UPPER TROUGH PASSING NORTHEAST OF THE
NORTHEASTERN CARIBBEAN. BY SUNDAY...TROUGHING OVER THE EASTERN
SEABOARD OF THE U.S. ASSOCIATED WITH THE COLD FRONT DISCUSSED IN
THE GULF OF MEXICO SECTION WILL SHIFT THE RIDGE AND TROUGH
UPSTREAM FARTHER TO THE EAST. AT THE SURFACE...A WEAKENING COLD
FRONT EXTENDS FROM 32N40W TO 25N55W WHERE IT BECOMES STATIONARY
TO NEAR 20N70W. THIS FRONT WILL DISSIPATE OVER THE NEXT DAY OR
SO AND A NEW COLD FRONT WILL MOVE OFF THE U.S. EAST COAST LATE
SATURDAY NIGHT...WITH FRESH TO STRONG WINDS EXPECTED ON EITHER
SIDE OF THE FRONT NORTH OF 27N. UPPER DIFFLUENCE ASSOCIATED WITH
A SHORTWAVE SYSTEM IN ADVANCE OF THE UPPER TROUGH MAKING ITS WAY
TO THE U.S. EASTERN SEABOARD WILL ENHANCE SHOWER AND
THUNDERSTORM ACTIVITY WELL AHEAD OF THE COLD FRONT.
SOUTHEASTERLY FLOW IS ALREADY IN PLACE IN THE SW NORTH ATLC AND
IS TRANSPORTING MOISTURE INTO THE REGION OF EXPECTED ENHANCED
VERTICAL MOTION. FARTHER EAST...A SHARP UPPER TROUGH EXTENDING
ALONG THE NORTHWEST COAST OF AFRICA IS ASSOCIATED WITH A COLD
FRONT AT THE SURFACE AND GALE FORCE WINDS NEAR MADEIRA AND THE
CANARY ISLANDS. THIS GALE EVENT IS DISCUSSED IN THE SPECIAL
FEATURES SECTION ABOVE. OTHERWISE...THE REMAINDER OF THE CENTRAL
AND EASTERN ATLC IS UNDER THE INFLUENCE OF THE SURFACE RIDGE
THAT EXTENDS FROM THE AFOREMENTIONED 1036 MB HIGH CENTER NORTH
OF THE AREA TO THE CAPE VERDE ISLANDS.

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

$$
SCHAUER


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