000 AXNT20 KNHC 120556 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU MAR 12 2015 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... ...GALE WARNING FOR THE SW CARIBBEAN... A GALE WARNING IS IN EFFECT FOR THE COASTAL WATERS OF COLOMBIA FROM 10N TO 14N BETWEEN 74W AND 77W. UNFORTUNATELY...NO SCATTEROMETER DATA WERE AVAILABLE OVER THE AREA. HOWEVER...SHIP PBIG WAS JUST SOUTHWEST OF THE AREA AND RECORDED 30 KT NE WINDS AT 00 UTC. THE HIGH WINDS ARE BEING CAUSED BY THE STRONG PRESSURE GRADIENT BETWEEN A 1005 MB LOW OVER NORTHERN COLOMBIA AND A SURFACE RIDGE EXTENDING ALONG 30N...IN COMBINATION WITH THE TYPICAL TOPOGRAPHICAL WIND ENHANCEMENTS NORTH OF COLOMBIA. NEAR GALE TO GALE CONDITIONS SHOULD CONTINUE THROUGH FRIDAY EVENING. PLEASE SEE THE LATEST HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLANTIC NEAR 6N10W TO 4N11W WHERE THE ITCZ BEGINS AND CONTINUES ALONG THE EQUATOR NEAR 25W THEN TO SOUTH AMERICA NEAR 48W. SCATTERED MODERATE CONVECTION EXISTS WITHIN 60 NM OF THE ITCZ BETWEEN 20 AND 37W. ...DISCUSSION... GULF OF MEXICO... A 1012 MB LOW IS CENTERED AT 26N94W IN THE NORTHWESTERN GULF OF MEXICO ACCOMPANIED BY A COLD FRONT EXTENDING SOUTHWARD TO THE BAY OF CAMPECHE AND A STATIONARY FRONT EXTENDING EAST- NORTHEASTWARD TO THE LOUISIANA COAST. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS OBSERVED NORTH OF 24N TO THE LOUISIANA-MISSISSIPPI-ALABAMA COAST BETWEEN 87W TO 91W BASED UPON GEOSTATIONARY IMAGERY...LIGHTNING DATA...AND THE U.S. WSR- 88D RADAR NETWORK. ISOLATED MODERATE CONVECTION IS ALSO OCCURRING NORTH OF 27N TO THE TEXAS COAST BETWEEN 94 AND 96W. THE CONVECTION IS LIKELY SUPPORTED BY FORCING FROM A HIGH AMPLITUDE MID TO UPPER LEVEL LONGWAVE TROUGH CENTERED OVER CENTRAL MEXICO ALONG WITH AN EMBEDDED SHORTWAVE TROUGH NEAR THE SOUTH TEXAS COAST. SURFACE WINDS PEAK WEST OF THE COLD FRONT AT 30 KT...AS SEEN IN THE 0316 UTC ASCAT SCATTEROMETER PASS. WINDS IN THE EASTERN HALF OF THE GULF ARE GENERALLY 5-15 KT SE. OVER THE NEXT TWO DAYS...THE COLD FRONT MOVES SLOWLY EASTWARD TO STALL IN THE CENTRAL GULF WHILE THE WEAK LOW MOVES NORTHWARD ALONG THE FRONT AND REACHES THE TEXAS-LOUISIANA COAST LATE THURSDAY. THE ADVECTION OF ABUNDANT MOISTURE ALONG WITH FORCING BY THE UPPER LEVEL TROUGH SHOULD CONTINUE TO PROVIDE THE POTENTIAL FOR CONVECTION DURING THE NEXT COUPLE OF DAYS IN THE WESTERN AND CENTRAL GULF OF MEXICO INCLUDING THE COAST OF MEXICO FROM THE BAY OF CAMPECHE TO THE U.S. GULF COAST FROM TEXAS TO THE FLORIDA PANHANDLE. CARIBBEAN SEA... OUTSIDE OF THE GALE CONDITION DESCRIBED ABOVE...THE CARIBBEAN SEA HAS NO SURFACE FEATURES OF INTEREST NOR IS THERE ANY ORGANIZED DEEP CONVECTION. A BROAD HIGH AMPLITUDE UPPER RIDGE COVERS THE CARIBBEAN WITH AN AXIS ALONG 73W...WHICH IS PROMOTING SUBSIDENCE OVER THE CARIBBEAN. THE AFOREMENTIONED STRONG PRESSURE GRADIENT FORCING THE GALE CONDITIONS NEAR COLOMBIA ARE ALSO FORCING E TO NE TRADEWINDS OF 20 TO 30 KT ACROSS ALL OF THE CARIBBEAN EXCEPT THE NORTHWEST. LITTLE CHANGE IS EXPECTED DURING THE NEXT TWO DAYS. ...HISPANIOLA... GENERALLY FAIR SKIES WITH POSSIBLE ISOLATED FAST-MOVING SHOWERS DOMINATE THE ISLAND THIS EVENING. WINDS ALONG THE COASTS WILL BE A BRISK 20-25 KT...EXCEPT ON THE WESTWARD LEE SIDES OF THE ISLAND. THESE CONDITIONS WILL PERSIST THROUGH AT LEAST FRIDAY NIGHT. ATLANTIC OCEAN... THE MAIN SURFACE FEATURE ACROSS THE ATLANTIC IS THE RIDGING EXTENDING FROM A 1029 MB HIGH NEAR 32N19W TO A 1030 MB HIGH NEAR 35N42W TO THE GEORGIA COASTLINE. TRADEWINDS ARE GENERALLY NE 10-20 KT ACROSS MOST OF THE REGION WITH 25 KT E WINDS OCCURRING JUST NORTH OF PUERTO RICO AND HISPANIOLA. A SURFACE TROUGH EXTENDS FROM 31N36W TO 24N56W...THOUGH NO SIGNIFICANT WEATHER IS CURRENTLY ASSOCIATED WITH THIS FEATURE. IN THE UPPER LEVELS...A CUT OFF LOW IS CENTERED NEAR 22N40W. SCATTERED SHOWERS ARE OCCURRING FROM 18-24N BETWEEN 36-42W IN ASSOCIATION WITH THE LOW...THOUGH NO SURFACE COMPONENT TO THE FEATURE IS CURRENTLY PRESENT. DURING THE NEXT COUPLE OF DAYS...THE UPPER-LEVEL LOW WILL DRIFT SLOWLY EASTWARD AND OCCASIONALLY PRODUCE SOME CONVECTION...BUT NO SIGNIFICANT SURFACE FEATURES ARE ANTICIPATED TO FORM. BY THURSDAY NIGHT...A NEW COLD FRONT WILL REACH THE NORTHERN BORDER OF 32N WEST OF 70W. THIS WILL PROGRESS QUICKLY EASTWARD AND APPROACH 25N...BUT IS UNLIKELY TO CAUSE GALE CONDITIONS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LANDSEA