[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111733
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED APR 11 2012

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
1700 UTC.

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

THE MONSOON TROUGH PASSES THROUGH THE COASTAL BORDER AREA OF
SIERRA LEONE AND LIBERIA NEAR 7N11W TO THE EQUATOR AT 27W. THE
ITCZ CONTINUES FROM 0N27W TO THE NORTHEAST COAST OF BRAZIL NEAR
4S40W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTIVE
PRECIPITATION LIES FROM 7N TO THE EQUATOR BETWEEN 10W AND 23W.
ISOLATED MODERATE CONVECTIVE PRECIPITATION IS ELSEWHERE TO THE
SOUTH OF 10N TO THE EAST OF 60W.

...DISCUSSION...

THE GULF OF MEXICO...
WEST-NORTHWESTERLY UPPER LEVEL WINDS ARE CURRENTLY OVER MUCH OF
THE GULF ARE CARRYING MID TO UPPER LEVEL MOISTURE ACROSS THE
REGION PRIMARILY N OF 23N. THESE WINDS ARE BEGINNING TO SHIFT
NORTHWESTERLY AS THE MEAN UPPER TROUGH CENTERED JUST EAST OF
FLORIDA AMPLIFIES. A COLD FRONT ASSOCIATED WITH THIS TROUGH
ALOFT IS MAKING ITS WAY THROUGH NORTH FLORIDA AND THE
NORTHEASTERN GULF OF MEXICO. A 1020 MB SURFACE HIGH IS CENTERED
NEAR 28N91W AND LIGHT TO MODERATE ANTICYCLONIC FLOW IS FOUND AT
THE SURFACE OVER THE GULF AROUND THE HIGH...WITH WINDS IN THE
NORTHEAST GULF VEERING MORE NORTHERLY BEHIND THE COLD FRONT. THE
FRONT WILL DISSIPATE ACROSS THE NORTHEASTERN GULF BY TONIGHT AND
THE SURFACE HIGH WILL MERGE WITH STRONGER HIGH PRESSURE BEHIND
THE FRONT OVER THE OHIO VALLEY. THE LIGHT TO MODERATE WIND
REGIME WITH PREVAILING WINDS FROM THE NORTHEAST IN THE EASTERN
GULF AND SOUTHEAST IN THE WESTERN GULF WILL CONTINUE FOR THE
NEXT FEW DAYS.

THE CARIBBEAN SEA...
WATER VAPOR IMAGERY SHOWS SOUTHWESTERLY WINDS ALOFT ARE
TRANSPORTING MID TO UPPER LEVEL MOISTURE FROM THE PACIFIC AND
SOUTH AMERICA ACROSS THE CARIBBEAN...WITH WIDELY SCATTERED
CIRRUS FOUND PRIMARILY SOUTH OF 14N EAST OF 80W. THE SUBTROPICAL
HIGH AT THE SURFACE IS WELL NORTHEAST OF THE CARIBBEAN NEAR
37N37W AND RIDGING IS FURTHER WEAKENED BY A SURFACE TROUGH THAT
LIES NORTH OF HISPANIOLA. WINDS ARE LIGHT OVER THE CARIBBEAN AS
A RESULT OF THE DIMINISHED PRESSURE GRADIENT BETWEEN THE
SUBTROPICAL HIGH AND TROUGHING OVER SOUTH AMERICA. A SURFACE
TROUGH LIES FROM THE WINDWARD PASSAGE NEAR 19N75W TO 13N76W.
LIGHT TO MODERATE EAST-NORTHEASTERLY TRADE WINDS CAN BE FOUND
OVER MUCH OF THE AREA...WITH NORTH-NORTHEAST WINDS FOUND EAST OF
THE TROUGH IN THE SOUTHWEST CARIBBEAN. THIS WEAK TROUGH IS
EXPECTED TO DISSIPATE OVER THE NEXT 24 HOURS. SCATTERED SHOWERS
ARE MOST PREVALENT NEAR THE CENTRAL AMERICAN COAST AS WELL AS IN
THE REGION NORTH OF 17N BETWEEN 68W AND 82W WHERE SOME ISOLATED
THUNDERSTORMS CAN ALSO BE FOUND. PRECIPITABLE WATER IMAGERY
SHOWS LOW LEVEL MOISTURE HAS POOLED IN THE CARIBBEAN NORTH OF
16N EAST OF 80W AS WELL AS NORTH OF THE CARIBBEAN NEAR THE
TROUGH FOUND NORTH OF HISPANIOLA. THE AVAILABLE MOISTURE SHOULD
BEGIN TO THIN OUT HERE ON THURSDAY AS A COLD FRONT SWEEPS
THROUGH THE BAHAMAS AND THE MOISTURE IS SPREAD NORTHWARD ALONG
THE FRONT.

THE ATLANTIC OCEAN...
A BROAD UPPER LEVEL TROUGH LIES OVER THE WESTERN ATLANTIC. THE
LEADING EDGE OF THIS TROUGH SUPPORTS A DISSIPATING STATIONARY
FRONT AT THE SURFACE FROM 32N53W TO 27N58W. SCATTERED MODERATE
CONVECTIVE PRECIPITATION LIES NORTH OF 30N NEAR THIS DISSIPATING
FRONT. A SURFACE TROUGH EXTENDS FROM 27N66W TO 20N71W. SCATTERED
MODERATE CONVECTIVE PRECIPITATION CAN GENERALLY BE FOUND WITHIN
270 NM ON EITHER SIDE OF THIS TROUGH. THE UPPER PATTERN IS
BEGINNING TO AMPLIFY AS ENERGY IS MOVING INTO THE BACKSIDE OF
THE BROAD TROUGH FROM NORTH AMERICA AND RIDGING AHEAD OF THE
TROUGH IS BUILDING OVER THE CENTRAL ATLANTIC. A NEW COLD FRONT
ASSOCIATED WITH THIS ENERGY LIES FROM 32N77W THROUGH SAINT
AUGUSTINE...FLORIDA. THE FRONT WILL SWEEP SOUTHEASTWARD INTO THE
BAHAMAS THURSDAY AND LIFT THE AFOREMENTIONED SURFACE TROUGH NEAR
EASTERN HISPANIOLA NORTHWARD. FARTHER EAST...DEEP LAYER RIDGING
IS BUILDING OVER THE CENTRAL ATLANTIC. THE 1032 MB SUBTROPICAL
HIGH CURRENTLY LIES NEAR 37N37W. THE PRESSURE GRADIENT BETWEEN
THE HIGH AND THE ITCZ TO THE SOUTH IS FORCING AN AREA OF FRESH
NORTHEASTERLY TRADE WINDS FOUND GENERALLY OVER THE AREA SOUTH OF
24N EAST OF 57W. THE HIGH IS FORECAST TO DRIFT A FEW DEGREES
EASTWARD OVER THE NEXT DAY OR TWO. ELSEWHERE...SCATTERED
MODERATE CONVECTIVE PRECIPITATION CAN BE FOUND FROM 04N TO 09N
BETWEEN 50W AND 60W INCLUDING NORTHERN GUYANA...SURINAME...AND
FRENCH GUIANA. OTHERWISE...SIGNIFICANT CONVECTIVE PRECIPITATION
IS CONFINED TO THE AREA DESCRIBED IN THE ITCZ SECTION ABOVE.

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

$$
SCHAUER




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