000 AXNT20 KNHC 281022 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...SPECIAL FEATURES... A STRONG PRESSURE GRADIENT EXISTS ACROSS THE SW CARIBBEAN SEA BETWEEN STRONG HIGH PRESSURE CENTERED ACROSS THE WESTERN NORTH ATLC AND LOWER PRESSURE ACROSS THE NORTHWESTERN SOUTH AMERICAN CONTINENT. GALE FORCE WINDS CONTINUE ALONG THE COAST OF COLOMBIA AND ARE EXPECTED THROUGH EARLY SAT MORNING. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 06N10W TO 02N19W TO 02N28W. THE ITCZ BEGINS NEAR 02N29W TO 02N40W TO THE EQUATOR ALONG 50W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS FROM 01S-05N BETWEEN 15W-25W. ISOLATED MODERATE CONVECTION IS FROM THE EQUATOR TO 04N BETWEEN 30W-50W. ...DISCUSSION... GULF OF MEXICO... ALOFT...NEARLY ZONAL WIND CONTINUE TO FLOW ACROSS THE GULF. WATER VAPOR IMAGERY INDICATE THE SUBTROPICAL JET STREAM IS ADVECTING MID TO UPPER LEVEL MOISTURE AND CLOUDINESS FROM THE EASTERN PACIFIC OVER THE BASIN N OF 23N TO THE FLORIDA PENINSULA. AT THE SURFACE...A BROAD RIDGE ANCHORED BY A 1035 MB HIGH OVER THE W ATLC NEAR 34N65W EXTENDS INTO THE GULF AND PROVIDES SOUTHEASTERLY WIND OF 15-20 KT OVER THE WESTERN AND EASTERN BASIN WHILE A TIGHTER PRESSURE GRADIENT OVER THE CENTRAL GULF SUPPORT WINDS UP TO 25 KT. THESE STRONG WINDS ARE ADVECTING LOW LEVEL MOISTURE ALONG THE NORTH-CENTRAL GULF COAST WHICH ALONG WITH UPPER LEVEL DIFFLUENCE CONTINUE TO SUPPORT HEAVY SHOWERS AND TSTMS OVER PORTIONS OF LOUISIANA...MISSISSIPPI AND ALABAMA. SATELLITE IMAGERY AND LIGHTING DATA SHOW HEAVY RAINFALL AND TSTMS N OF 28N BETWEEN 87W-89W. SCATTERED MODERATE CONVECTION IS ELSEWHERE N OF 24N W OF 90W AND N OF 26N E OF 87W...INCLUDING THE FLORIDA PENINSULA. AS THE HIGH PRESSURE CENTER OVER THE W ATLC CONTINUES TO DRIFT NE TODAY...WINDS OVER THE GULF WILL SHIFT FROM SOUTHEASTERLY TO SOUTHERLY FLOW. BY EARLY SAT MORNING A COLD FRONT IS FORECAST TO MOVE INTO THE NORTHWESTERN GULF WHICH IS EXPECTED TO MOVE ACROSS FLORIDA SAT NIGHT INTO SUN MORNING. CARIBBEAN SEA... NORTHWESTERLY FLOW ALOFT IS OVER THE CARIBBEAN BASIN WITH WATER VAPOR IMAGERY INDICATING RELATIVELY DRY AIR SUBSIDING ACROSS THE REGION. AT THE SURFACE...A SHEAR LINE IS ANALYZED FROM NW HAITI TO NORTHERN JAMAICA NEAR 18N78W. SPEED CONVERGENCE OF THE TRADES ALONG THE SHEARLINE IS ENHANCING ISOLATED SHOWERS WITHIN 60 NM S OF IT. A GALE WARNING CONTINUES IN EFFECT FOR THE SW CARIBBEAN WATERS OFF THE COAST OF COLOMBIA. THE STRONG PRESSURE GRADIENT CREATED BETWEEN HIGH PRESSURE CENTERED ACROSS THE WESTERN NORTH ATLC AND LOWER PRESSURE ACROSS THE NORTHWESTERN SOUTH AMERICAN CONTINENT IS EXPECTED TO RELAX BY SATURDAY AS THE HIGH PRESSURE MOVES NORTHEASTWARD. SEE THE SPECIAL FEATURES SECTION ABOVE FOR DETAILS. EXCEPT FOR THE CENTRAL BASIN WHERE TRADES OF 25 KT DOMINATE...TRADES OF 15-20 KT ARE ELSEWHERE. WINDS OVER THE CENTRAL CARIBBEAN ARE EXPECTED TO SUBSIDE BY SAT MORNING. ...HISPANIOLA... CURRENTLY...A SHEAR LINE IS ANALYZED FROM 19N72W TO NORTHERN JAMAICA NEAR 18N78W. THIS SHEAR LINE IS ENHANCING ISOLATED SHOWERS ACROSS MUCH OF THE ISLAND AS WELL AS THE NORTHERN AND WESTERN ADJACENT WATERS. THE SHEAR LINE WILL GRADUALLY DISSIPATE TODAY...HOWEVER REMNANT MOISTURE WILL LIKELY ENHANCE SHOWERS OVER HISPANIOLA THROUGH SAT NIGHT. ATLANTIC OCEAN... AN UPPER RIDGE OVER THE N WESTERN ATLC SUPPORTS A BROAD SURFACE RIDGE ANCHORED BY A 1035 MB HIGH NEAR 35N65W. FARTHER EAST A DEEP LAYER TROUGH SUPPORTS A COLD FRONT OVER THE CENTRAL ATLC EXTENDING INTO THE AREA OF DISCUSSION ALONG 30N48W SW TO 25N56W WHERE IT TRANSITIONS TO A STATIONARY FRONT TO 20N68W AND THEN INTO A SHEARLINE OVER THE NW CARIBBEAN. ISOLATED SHOWERS ARE POSSIBLE WITHIN 100 NM EITHER SIDE OF THE FRONT N OF 24N. OTHERWISE...THE REMAINDER CENTRAL AND EASTERN ATLC N OF 14N IS UNDER THE INFLUENCE OF A SURFACE RIDGE. THE FRONT IS EXPECTED TO WEAKEN DURING THE DAY AND DISSIPATE LATE TONIGHT OVER THE CENTRAL ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR