FXUS62 KCHS 240825 AFDCHS AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 425 AM EDT FRI MAY 24 2013 .SYNOPSIS... A WEAK COLD FRONT WILL MOVE OFFSHORE THIS MORNING...FOLLOWED BY A REINFORCING COLD FRONT LATE THIS AFTERNOON AND EARLY THIS EVENING. HIGH PRESSURE WILL THEN BUILD INTO THE REGION THROUGH NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WATER VAPOR IMAGERY EARLY THIS MORNING DEPICTS A BROAD UPPER LEVEL TROUGH CENTERED OVER THE GREAT LAKES REGION. MEANWHILE AT THE SURFACE...A COLD FRONT EXTENDS ACROSS THE UPSTATE OF SOUTH CAROLINA AND NORTH-CENTRAL GEORGIA...WITH A WEAK PRE-FRONTAL TROUGH SHIFTING TOWARD THE COAST. AS THE DAY PROGRESSES...THE UPPER LEVEL TROUGH WILL DIG ACROSS THE MID-ATLANTIC REGION. THIS WILL PUSH THE PRIMARY COLD FRONT ACROSS THE AREA LATER THIS MORNING...WITH A REINFORCING COLD FRONT THEN EXPECTED TO SHIFT INTO THE AREA LATE THIS AFTERNOON AS THE TROUGH AXIS CROSSES. THE PRE-FRONTAL TROUGH WAS RESPONSIBLE FOR SOME ISOLATED SHOWERS ACROSS SOUTHEAST GEORGIA OVERNIGHT...BUT THIS ACTIVITY SHOULD END AS THE TROUGH MOVES OFFSHORE PRIOR TO DAYBREAK. THE DRY WESTERLY FLOW BEHIND THE PRE-FRONTAL TROUGH WILL PREVENT ANY ADDITIONAL SHOWERS FROM FORMING AS THE PRIMARY COLD FRONT MOVES THROUGH...WITH THE FLOW THEN VEERING NORTHWEST INTO THIS AFTERNOON. THERE COULD BE SOME SCATTERED MID LEVEL CLOUDS BENEATH THE UPPER TROUGH...ESPECIALLY OVER SOUTHEAST SOUTH CAROLINA...BUT A GOOD AMOUNT OF SUNSHINE AND A STRONG DOWNSLOPE FLOW WILL SUPPORT HIGHS IN THE MID TO UPPER 80S ACROSS THE AREA AWAY FROM THE IMMEDIATE COAST. DEEP MIXING THIS AFTERNOON WILL SUPPORT BREEZY CONDITIONS...WITH WINDS AS HIGH AS 15-20 MPH WITH GUSTS TO 25 MPH AT TIMES. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... TONIGHT...THE UPPER LEVEL TROUGH WILL BEGIN TO SHIFT OFF THE MID- ATLANTIC COAST THIS EVENING THEN PROGRESS OFFSHORE OVERNIGHT. A REINFORCING COLD FRONT WILL COMPLETE ITS PASSAGE ACROSS THE AREA DURING THE EARLY EVENING...WITH A NORTHERLY FLOW DEVELOPING IN ITS WAKE AS HIGH PRESSURE BUILDS FROM THE GREAT LAKES REGION. THE REINFORCING COLD FRONT WILL USHER IN A SIGNIFICANTLY DRIER AND COOLER AIRMASS. THE COLD AIR ADVECTION WILL CAUSE TEMPERATURES TO PLUMMET INTO THE UPPER 40S TO LOWER 50S AWAY FROM THE IMMEDIATE COAST...WITH SOME MID 40S POSSIBLE WELL INLAND IF WINDS FULLY DECOUPLE. SATURDAY THROUGH MONDAY...MEDIUM RANGE GUIDANCE IS IN PRETTY GOOD AGREEMENT THIS PERIOD SHOWING THE UPPER TROUGH SHIFTING OFFSHORE WITH THE SURFACE HIGH TO FOLLOW. THIS WILL KEEP A DRY AND COOLER THAN NORMAL AIR MASS IN PLACE. DEEP MOISTURE AND FORCING FOR ASCENT WILL BE LACKING SO RAINFALL IS NOT EXPECTED THROUGH THE PERIOD. THE BEST CHANCE OF ISOLATED SHOWERS WILL LIKELY COME MONDAY AFTERNOON...MAINLY NORTH OF CHARLESTON...AS THE SEA BREEZE PUSHES INLAND IN AN AXIS OF SLIGHTLY DEEPER MOISTURE. WITH THE VERY DRY AIRMASS IN PLACE...TEMPERATURES WILL VARY ABOUT 25-30 DEGREES FROM THE MORNING LOWS TO THE AFTERNOON HIGHS. MORNING LOWS SUNDAY COULD GET WITHIN A FEW DEGREES OF THE RECORDS AT CHARLESTON AND SAVANNAH. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... DECENT MODEL AGREEMENT THIS PERIOD WITH ABOVE AVERAGE FORECAST CONFIDENCE. UPPER HIGH PRESSURE SHOULD BUILD ACROSS THE REGION TOWARD THE MIDDLE OF NEXT WEEK LEADING TO WARMING TEMPERATURES AND SLOWLY INCREASING LOW-LEVEL MOISTURE. RAIN CHANCES WILL REMAIN LOW GIVEN THE LACK OF DEEP MOISTURE AND FORCING...MAINLY CONFINED TO INLAND AREAS DURING AFTERNOON PEAK HEATING AS THE SEA BREEZE PUSHES INLAND. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 06Z SATURDAY. EXTENDED AVIATION...VFR CONDITIONS SHOULD PREVAIL. && .MARINE... TODAY...A WEAK COLD FRONT WILL MOVE OFFSHORE THIS MORNING WITH NORTHWEST WINDS PREVAILING ACROSS THE WATERS. WIND SPEEDS WILL GENERALLY BE IN THE 10-15 KT RANGE TODAY...ALTHOUGH SOME HIGHER WINDS COULD OCCUR OVER THE OUTER GEORGIA WATERS THIS MORNING. SEAS WILL BE NO HIGHER THAN 2-4 FT WITH THE LIMITED OFFSHORE FETCH. TONIGHT...A REINFORCING COLD FRONT WILL MOVE THROUGH EARLY THIS EVENING...WITH A STRONG NORTHERLY SURGE DEVELOPING IN ITS WAKE. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE OUTER GEORGIA WATERS DUE TO THE ELEVATED WINDS/SEAS ASSOCIATED WITH THE NORTHERLY SURGE. CONDITIONS WILL BE NEAR SMALL CRAFT ADVISORY LEVELS WITHIN 20 NM OF THE COAST...ESPECIALLY IN GEORGIA...HOWEVER CONFIDENCE IS TOO LOW GIVEN THE MARGINAL CONDITIONS TO ISSUE ANY ADDITIONAL SMALL CRAFT ADVISORIES AT THIS TIME. SATURDAY THROUGH WEDNESDAY...HIGH PRESSURE WILL MOVE OFFSHORE EARLY NEXT WEEK AND PERSIST THROUGH MID WEEK. ENHANCED WINDS/SEAS EARLY SATURDAY WILL DIMINISH DURING THE DAY AS THE HIGH GAINS MORE INFLUENCE AND THE PRESSURE GRADIENT SLACKENS. A MORE TYPICAL SPRINGTIME PATTERN WILL DOMINATE THERAFTER WITH SOME WIND ENHANCEMENT DURING THE DAY NEAR THE COAST AS THE SEA BREEZE DEVELOPS AND THEN OFFSHORE OVERNIGHT WITH NOCTURNAL SURGING. HOWEVER...CONDITIONS ARE EXPECTED TO REMAIN BELOW ADVISORY LEVELS THROUGH THE PERIOD. RIP CURRENTS...THE COMBINATION OF ASTRONOMICAL INFLUENCES AND AN 8 SECOND LONG PERIOD SWELL WILL RESULT IN A MODERATE RISK OF RIP CURRENTS AT AREA BEACHES TODAY. THE ENHANCED RIP CURRENT RISK MAY PERSIST INTO SATURDAY. && .TIDES/COASTAL FLOODING... HIGH ASTRONOMICAL TIDES AND FAVORABLE NORTH/NORTHEAST WINDS COULD LEAD TO MINOR SALTWATER INUNDATION NEAR THE COAST DURING THE HIGH TIDE THIS EVENING AND AGAIN SATURDAY EVENING. BY THE TIME OF THE HIGH TIDE SUNDAY EVENING AND MONDAY EVENING...WINDS WILL NOT BE AS CONDUCIVE...YET MINOR SALTWATER FLOODING WILL STILL BE POSSIBLE AS ASTRONOMICAL FACTORS WILL CAUSE HIGHER THAN TYPICAL TIDES. && .CLIMATE... RECORD LOW TEMPERATURES FOR MAY 25TH... CHARLESTON INTERNATIONAL AIRPORT /KCHS/.....47 SET IN 1967 DOWNTOWN CHARLESTON /KCHL/..................54 SET IN 1979 SAVANNAH/HHI INTERNATIONAL AIRPORT /KSAV/...49 SET IN 1967 RECORD LOW TEMPERATURES FOR MAY 26TH... CHARLESTON INTERNATIONAL AIRPORT /KCHS/.....50 SET IN 1979 DOWNTOWN CHARLESTON /KCHL/..................50 SET IN 1979 SAVANNAH/HHI INTERNATIONAL AIRPORT /KSAV/...49 SET IN 1979 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT SATURDAY FOR AMZ374. && $$ SYNOPSIS... NEAR TERM...JAQ SHORT TERM...JAQ/RJB LONG TERM...RJB AVIATION...JAQ/RJB MARINE...JAQ/RJB TIDES/COASTAL FLOODING...JAQ/RJB CLIMATE...JAQ