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AXNT20 KNHC 171736
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU APR 17 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... AN AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP S OF THE LOUISIANA COAST TONIGHT...INTENSIFY AND MOVE TO NEAR 29N88W BY EARLY FRI. A GALE WARNING HAS BEEN ISSUED OVER THE FAR NE GULF WATERS WITHIN 60 IN THE NM NW SEMICIRCLE OF LOW CENTER FOR WINDS OF 30-35 KT. FOR ADDITIONAL DETAILS PLEASE REFER TO THE ATLANTIC HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC.


...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC NEAR 7N12W AND CONTINUES TO 5N15W WHERE THE ITCZ BEGINS AND CONTINUES THROUGH 2N20W TO THE EQUATOR NEAR 27W THE CONTINUES TO THE COAST OF SOUTH AMERICA NEAR 02S43W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM THE EQUATOR TO 3S BETWEEN 20W-27W. SCATTERED MODERATE CONVECTION WAS NOTED S OF 3N BETWEEN 27W-45W.


...DISCUSSION...

GULF OF MEXICO... AN AMPLIFYING MID-UPPER LEVEL SHORTWAVE TROUGH OVER TEXAS IS ENHANCING AN AREA OF SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND TO THE N OF A WEAKENING STATIONARY FRONT WHICH EXTENDED FROM THE FLORIDA COAST NEAR NAPLES THROUGH 26N87W TO 25N94W. THE CONVECTIVE ACTIVITY WAS CONFINED TO THE AREA WEST OF 90W. AN INCREASE IN LIGHTNING STRIKES WAS NOTED WITHIN 60 NM OF A LINE FROM 27.5N91W TO 25N94W. THIS MID-UPPER LEVEL TROUGH WILL SWEEP EASTWARD AND RESULT IN LOW PRESSURE DEVELOPMENT OFF THE LOUISIANA COAST TONIGHT WITH FURTHER INTENSIFICATION EXPECTED TOMORROW. GALE FORCE WINDS ARE EXPECTED WITHIN 60 NM IN THE NW SEMICIRCLE OF THE LOW BY 1200 UTC FRI. THIS LOW WILL DRAG A COLD FRONT ACROSS FLORIDA THROUGH SAT AS THE LOW MOVES NE INTO THE SW N ATLANTIC. REFER TO SPECIAL FEATURES ABOVE. ELSEWHERE OVER THE GULF A BROAD FLAT RIDGE PREVAILED MAINLY E OF 90W WITH COPIUS AMOUNTS OF MID TO UPPER LEVEL MOISTURE BEING ADVECTED EASTWARD OVER THE BASIN. A WEAK SURFACE TROUGH WAS NOTED OVER THE BAY OF CAMPECHE EXTENDING FROM 24N91W TO 18N94W. A SURFACE RIDGE OVER THE NE GULF ANCHORED BY A 1042 MB HIGH OVER MAINE WAS SHIFTING E.

CARIBBEAN SEA... BROAD UPPER RIDGE COVERS THE CARIBBEAN WITH THE AXIS EXTENDING FROM COLOMBIA ACROSS HISPANIOLA INTO THE SW N ATLANTIC. A DOWNSTREAM UPPER TROUGH CLIPPED THE FAR EASTERN CARIBBEAN AND THE WINDWARD ISLANDS. FAIR SKIES PREVAILED OVER THE CARIBBEAN WITH THE EXCEPTION OF A CLUSTER OF SCATTERED SHOWERS WITHIN 180 NM S OF HAITI AND JAMAICA ALONG 75W...AND ANOTHER CLUSTER EXTENDING FROM MARTINIQUE TO ANTIGUA AND THE VIRGIN ISLANDS. ASCAT SCATTEROMETER DATA SHOWED GENERALLY LIGHT TO MODERATE WINDS OVER THE CARIBBEAN WITH THE HIGHEST WINDS...15-20 KT FOCUSED IN THE WINDWARD PASSAGE AND ALONG THE COAST OF COLOMBIA. THE PRESSURE GRADIENT WILL WEAKEN SLIGHTLY SAT AND SUN AS A LOW PRESSURE MOVES OUT OF THE GULF AND ACROSS THE SW N ATLANTIC.


...HISPANIOLA... CURRENTLY SCATTERED SHOWERS ARE POPPING OVER OROGRAPHICALLY FAVORED AREAS IN THE DOMINICAN REPUBLIC AS DAYTIME HEATING IS NEAR A MAXIMUM. THE UPPER RIDGE EXTENDING FROM COLOMBIA ACROSS HISPANIOLA INTO THE W ATLC WILL SHIFT E THROUGH FRI WHEN NEAR ZONAL WESTERLY FLOW ALOFT WILL PREVAIL THROUGH THE WEEKEND. LOW LEVEL MOISTURE WILL PERSIST THROUGH THE WEEKEND GIVING THE ISLAND SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS TODAY THROUGH SUN.

ATLANTIC OCEAN... A FLATTENING MID-UPPER TROUGH ALONG THE EASTERN SEABOARD EXTENDS INTO THE FAR NW ATLC N OF 27N ALONG 75W IS SUPPORTING A STATIONARY FRONT WHICH ENTERS THE AREA FROM 32N72W THROUGH 28N76W TO THE FLORIDA EAST COAST NEAR PALM BEACH TO NAPLES. ISOLATED AREAS OF SHOWERS AND THUNDERSTORMS WERE NOTED WITHIN 90-120 NM E OF THE FRONT N OF 28N WITH ADDITIONAL ACTIVITY OVER SE FLORIDA IN MIAMI-DADE COUNTY. THE FRONT WILL SLIDE NORTHWARD AS A WARM FRONT BY FRI NIGHT AS SURFACE LOW DEVELOPING IN THE GULF OF MEXICO FRI MOVES INTO THE FAR NW CORNER OF THE AREA AND DRAGS A TRAILING COLD FRONT. A SURFACE RIDGE DOMINATES THE REMAINDER OF THE WESTERN AND CENTRAL ATLC ANCHORED BY A 1034 MB HIGH NEAR 37N52W. A SHARP UPPER TROUGH EXTENDS FROM NEAR THE AZORES THROUGH 32N37W TO 25N55W AND WAS DIGGING SOUTHWARD E OF A NARROW RIDGE AXIS ALONG 65W. THIS TROUGH SUPPORTED A WEAKENING STATIONARY FRONT THAT ENTERS THE REGION NEAR 32N19W AND EXTENDS TO 24N28W. A POST-FRONTAL TROUGH EXTENDS FROM 31N31W TO 25N40W.

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

$$ COBB

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