000 AXNT20 KNHC 210005 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI MAR 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2345 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 08N13W TO THE EQUATOR NEAR 23W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE TROUGH BETWEEN 21W-23W. ...DISCUSSION... GULF OF MEXICO... UPPER LEVEL RIDGING PREVAILS OVER THE BASIN THIS EVENING ANCHORED BY A LARGE UPPER LEVEL ANTICYCLONE CENTERED OVER HONDURAS. THIS SETUP CONTINUES TO PROVIDE THE GULF WITH SOUTHWEST TO WESTERLY FLOW ALOFT WITHIN A RELATIVELY DRY AND STABLE AIRMASS. THE RIDGING ALOFT SUPPORTS A WEAK SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED NEAR 29N88W THAT CONTINUES TO PROMOTE SLIGHT TO GENTLE BREEZE CONDITIONS. THE SURFACE RIDGING IS FORECAST TO CHANGE LITTLE ACROSS THE EASTERN GULF THROUGH SUN WITH THE NEXT WEAK FRONT ANTICIPATED TO EMERGE OFF THE TEXAS AND LOUISIANA COASTS EARLY SUNDAY. ABUNDANT PACIFIC MOISTURE ALOFT AHEAD OF THE UPPER TROUGH ASSOCIATED WITH THE UPCOMING FRONT WILL BEGIN TO MOVE INTO THE FAR WESTERN GULF LATE SAT INTRODUCING A CHANCE FOR SCATTERED SHOWERS AND TSTMS OVER THAT PART OF THE GULF. THIS MOISTURE ALONG WITH THE SHOWER/TSTM ACTIVITY WILL THEN SPREAD EASTWARD ACROSS THE WESTERN GULF INTO SUN AS DEPICTED IN THE GFS MODEL MOISTURE GUIDANCE. PATCHES OF DENSE FOG ARE AGAIN POSSIBLE OVERNIGHT TONIGHT INTO SAT ACROSS PORTIONS OF THE N CENTRAL AND W PORTIONS OF THE GULF AS WARM MOIST SLY AIR FLOWS OVER THE COOLER SHELF WATERS OCCURRING THERE. CARIBBEAN SEA... UPPER LEVEL NORTHWESTERLY FLOW DOMINATES THE CARIBBEAN ON THE EASTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER HONDURAS NEAR 15N86W. WATER VAPOR IMAGERY INDICATES RELATIVELY DRY AIR AND STABLE CONDITIONS ALOFT RESULTING IN MOSTLY FAIR SKIES AND CONDITIONS AT THE SURFACE FOR MUCH OF THE BASIN. ONLY ISOLATED SHOWERS ARE NOTED JUST S OF PUERTO RICO...NEAR THE NE CARIBBEAN PASSAGES...AND OVER THE SE PART OF THE CARIBBEAN IN PATCHES OF LOW-LEVEL MOISTURE MOVING WSW. WITH WEAK RIDGING TO THE N OF THE BASIN ACROSS THE SW NORTH ATLC REGION ALONG 20N...THE OVERALL PRES GRADIENT ACROSS THE CARIBBEAN REMAINS WEAK WITH MOSTLY GENTLE TO MODERATE TRADES OCCURRING OUTSIDE OF THE AREA WITHIN CLOSE PROXIMITY TO THE COAST OF COLOMBIA. LITTLE CHANGE IS EXPECTED IN THIS SYNOPTIC ENVIRONMENT THROUGH SUN. ...HISPANIOLA... GENERALLY CLEAR SKIES AND FAIR CONDITIONS UNDER VERY DRY CONDITIONS ALOFT CONTINUE TO DOMINATE THE ISLAND'S WEATHER EARLY THIS EVENING. LATEST SATELLITE IMAGERY ALONG WITH RECENT SURFACE OBSERVATIONS REVEAL SCATTERED TO OCCASIONALLY BROKEN LOW CLOUDS OVER THE INTERIOR PORTION...AND JUST INLAND THE THE COASTAL SECTIONS. ISOLATED SHOWERS TO WEAK ISOLATED TSTMS ARE POSSIBLE WITH SOME OF THESE CLOUDS. ISOLATED SHOWERS AND WEAK ISOLATED TSTMS ARE POSSIBLE WITHIN ABOUT 90 NM OFFSHORE THE SW PART OF HAITI WITH MOTION TO THE W. THE FAIR WEATHER IS EXPECTED TO PERSIST DURING THE NEXT COUPLE OF DAYS AS NW FLOW ALOFT ON THE EASTERN PERIPHERY OF THE ANTICYCLONE SITUATED OVER HONDURAS. MID/UPPER LEVEL RIDGING CONTINUES TO PROVIDE RELATIVELY DRY AND STABLE CONDITIONS ALOFT INHIBITING DEEP CONVECTIVE ACTIVITY FROM FORMING. ATLANTIC OCEAN... BROAD TROUGHING IS NOTED N OF 24N BETWEEN 45W-64W...AND SUPPORTS A STATIONARY FRONT THAT ENTERS THE REGION THROUGH 32N47W SW TO 25N57W TO 25N61W TO 26NN67W TO 28N72W...AND DISSIPATING NW TO 30N75W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE N OF THE FRONT E OF 64W AND WITHIN 75 NM SE OF THE FRONT E OF 56W....WHILE ISOLATED SHOWERS ARE N OF THE FRONT W OF 64W. A PRE-FRONTAL TROUGH IS ANALYZED FROM NEAR 32N46W SW TO 27N50W TO 22N53W. A MID-UPPER SHORTWAVE TROUGH EMBEDDED IN THE BROAD TROUGH IS NOTED ON WATER VAPOR IMAGERY MOVING QUICKLY E FROM 32N51W SE TO 26.5N49W. THIS FEATURE IS COMBINING WITH PRE-FRONTAL TROUGH AND AMPLE MOISTURE IN WESTERLY FLOW TO PRODUCE SCATTERED SHOWERS AND TSTMS WITHIN 100 NM E OF THE SURFACE TROUGH N OF 25N. THIS ACTIVITY WILL GRADUALLY SLIDE EASTWARD THROUGH SUN. ELSEWHERE...A COLD FRONT HAS MOVED INTO THE NW PART OF THE BASIN...AND IS ALONG A POSITION FROM 32N78W SW TO INLAND FLORIDA BETWEEN SAINT AGUSTINE AND DAYTONA BEACH. A SURFACE TROUGH OUT AHEAD OF THE COLD FRONT EXTENDS FROM NEAR 32N77W SW TO NEAR MELBOURNE FLORIDA. LATEST NWS RADAR DISPLAY SHOWS A PATCH OF ISOLATED SHOWERS ALONG AND OFFSHORE THE CENTRAL FLORIDA COAST FOR 50 NM FROM NEAR STUART TO CAPE CANAVERAL. THE COLD FRONT IS FORECAST TO REACH FROM NEAR 32N64W TO 27N74W TO CAPE CANAVERAL SAT NIGHT BEFORE LIFTING N AS A WARM FRONT ON SUN. ANOTHER COLD FRONT WILL ENTER THE NW WATERS SUN NIGHT WITH WEAK LOW PRES NEAR 30N76W. HIGH PRES IS EXPECTED TO BUILD IN BEHIND THE FRONT LATE SAT THROUGH SUN TO THE W OF 70W. OVER THE EASTERN PORTION...A SURFACE RIDGE ENTERS THE AREA THROUGH 32N55W AND CONTINUES TO NEAR 25N45W. PATCHES OF BROKEN TO OVERCAST STRATOCUMULUS CLOUDS MOVING WSW IN RESPONSE TO THE ANTICYCLONIC FLOW AROUND THE RIDGE ARE OBSERVED N OF ABOUT 10N AND E OF ABOUT 45W. THESE CLOUDS ARE MOST NOTICEABLE IN THE PROVING GROUND GOES-R GEOCOLOR SATELLITE ENHANCEMENT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ AGUIRRE