000 FXUS62 KCHS 190213 AFDCHS AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 913 PM EST MON FEB 18 2008 .SYNOPSIS... COOL HIGH PRESSURE WILL BUILD INTO THE REGION TONIGHT AND WILL PERSIST THROUGH MID WEEK. ANOTHER STORM SYSTEM MAY IMPACT THE AREA BY LATE WEEK AND OVER THE WEEKEND. && .NEAR TERM /THROUGH TUESDAY/... UNDER CLEAR SKIES...A COOLER/DRIER AIRMASS CONTINUED TO SPREAD INTO THE REGION MONDAY EVENING. EVENING TEMPERATURES PERSISTED IN THE LOWER 50S INLAND TO LOWER 60S NEAR THE COAST...ADJUSTED TEMPERATURE CURVES ACCORDINGLY. ONGOING FORECAST LOWS RANGING FROM THE MID 30S ACROSS THE NORMALLY COLDER HIGHER TERRAIN OF JENKINS...SCREVEN AND ALLENDALE COUNTIES TO THE LOWER TO MID 40S ALONG THE COAST APPEARS REASONABLE AND WAS NOT CHANGED. LAKE WINDS...MONDAY EVENING PINEVILLE/SHORT STAY OBSERVATIONS SUGGESTED WINDS HAD DIMINISHED TO LESS THAN 20 KNOTS ON LAKE MOULTRIE. THUS...CANCELLED THE LAKE WIND ADVISORY...AND FORECASTED 15-20 KNOT WINDS TONIGHT AND TUESDAY. && .SHORT TERM /TUESDAY NIGHT THROUGH 6 PM TUESDAY/... SUNNY...COOLER AND MUCH DRIER WX IS ON TAP FOR TUE. TEMPS ARE A BIT TRICKY WITH INFLUENCES FROM MODERATE CAA BEING TEMPERED BY DOWNSLOPE TRAJECTORIES. ADJUSTED FCST SOUNDINGS YIELD HIGH TEMPS IN THE LWR 60S WHICH IS A FEW DEGS WARMER THAN OUR PREVIOUS FCST. GUSTY WINDS APPEAR LIKELY BY AFTN AS MIXING HEIGHTS INCR. COULD SEE WINDS GUST AS HIGH AS 25 MPH AT TIMES...ESPECIALLY ACROSS THE SC ZONES. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... A ZONAL FLOW TUE NIGHT THROUGH WED NIGHT WILL KEEP SEASONABLE TEMPS IN THE FORECAST WITH MINIMAL RAIN CHANCES. DURING THE DAY THU A BACKDOOR COLD FRONT WILL DROP THROUGH THE AREA AS HIGH PRESSURE BUILDS OVER THE MID-ATLANTIC. AN INCREASE IN CLOUDS AND CHANCES FOR RAIN WILL OCCUR ON THU AS THE COOL WEDGE OF HIGH PRESSURE IN PLACE INTERACTS WITH AN INCREASINGLY MOIST SOUTHERLY FLOW FROM THE GULF. RAIN SHOWER COVERAGE IS NOT EXPECTED TO BE ESPECIALLY HIGH THU OR THU NIGHT...BUT FRI INTO SAT MORNING THERE WILL BE A HEIGHTENED CHANCE FOR RAIN AS A SERIES OF SURFACE LOWS MOVE ALONG THE FRONT AND OFF THE COAST. CONTINENTAL HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST BEHIND THE SYSTEM SAT AFTERNOON OR SAT NIGHT. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS WILL PREVAIL THROUGH TUE. SURFACE WINDS GENERALLY 10 KNOTS OR LESS AND 30 KNOT WINDS WITHIN 2 KFT OF THE SURFACE WILL PRODUCE LOW LEVEL WIND SHEAR UNTIL 14Z TUE. WNW/NW WINDS WILL BACK TOWARD THE WEST TUE AFTERNOON. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL PREVAIL TUE NIGHT THROUGH THU. ANOTHER STORM SYSTEM COULD PRODUCE MVFR OR LOWER CONDITIONS AS EARLY AS THU NIGHT. && .MARINE... PER MONDAY EVENING OBSERVATION TRENDS...CANCELLED SMALL CRAFT ADVISORIES FOR CHARLESTON HARBOR AND FOR AMZ350. CONTINUED THE ONGOING SCA FOR AMZ374...GA COASTAL WATERS 20-60 NM...FOR A COMBINATION OF WINDS AND SEAS UNTIL 4 AM TUE. WITHIN NEARSHORE WATERS OUTSIDE CHS HARBOR...COLD ADVECTION WILL KEEP WINDS IN THE 15-20 KNOT RANGE OVERNIGHT. WEST WINDS MAY GUST CLOSE TO ADVISORY CRITERIA ON CHARLESTON HARBOR TUE AFTERNOON. TUE NIGHT THROUGH SAT...BENIGN MARINE CONDITIONS EXPECTED TUE NIGHT THROUGH WED NIGHT BEFORE A COASTAL TROUGH FORMS ON THU. A BRIEF PINCHED NORTHEAST GRADIENT IS POSSIBLE ACROSS THE SC WATERS BEFORE WINDS VEER TO SOUTHWEST THU NIGHT OR EARLY FRI. ONCE THE WARM ADVECTION PATTERN DEVELOPS ON FRI ACROSS ALL OF THE WATERS...WIND SPEEDS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA BASED ON CURRENT MODEL PROGS. HOWEVER WE MAY EVENTUALLY NEED SMALL CRAFT ADVISORIES BASED ON WAVE HEIGHTS RISING ABOVE 6 FEET OVER A PORTION OF THE WATERS AS EARLY AS THU NIGHT. AN OFFSHORE FLOW SHOULD SETUP BY SAT NIGHT BEHIND A COLD FRONT...BUT COLD ADVECTION LOOKS RELATIVELY WEAK...THUS WINDS SHOULD REMAIN IN CHECK. && .FIRE WEATHER... RELATIVE HUMIDITIES ARE EXPECTED TO BOTTOM OUT AROUND 20-24 PCNT FOR MOST AREAS TUE AFTN. WINDS COULD BECOME GUSTY AT TIMES... POSSIBLY AS HIGH AS 25 MPH...BUT THIS IS BELOW RED FLAG CRITERIA. IT APPEARS FUELS ARE LIKELY TOO WET TO SUPPORT ANY SIGNIFICANT FIRE DANGER...SO NO FIRE WEATHER WATCHES OR FIRE DANGER STATEMENTS ARE NEEDED ATTM PER COORDINATION WITH THE VARIOUS LAND MANAGEMENT AGENCIES. WILL MAINTAIN HEADLINES FOR CRITICAL RH IN THE FIRE WEATHER PLANNING FCST. && .HYDROLOGY... RUNOFF FROM RECENT RAINFALL CONTINUED TO CONTRIBUTE TO INCREASING RIVER LEVELS ACROSS THE REGION. OF GREATEST CONCERN...THE UPDATED MONDAY EVENING FORECAST HOLDS THE OHOOPEE RIVER JUST BELOW THE FLOOD STAGE OF 11 FT AT REIDSVILLE...WITH A CREST OF 10.8 FT EXPECTED BEFORE NOON TUE. BECAUSE THE EXPECTED CREST WILL BE CLOSE TO FLOOD STAGE...INTERESTS ALONG THE OHOOPEE RIVER NEAR REIDSVILLE SHOULD CAREFULLY MONITOR THE LATEST CONDITIONS AND FORECASTS. IF NECESSARY...A RIVER FLOOD WARNING MAY YET BE ISSUED FOR THIS LOCATION LATE TONIGHT OR MONDAY MORNING. MEANWHILE...THE RIVER LEVEL CONTINUED TO RISE ON THE CANOOCHEE RIVER AT CLAXTON...WHICH IS FORECAST TO CREST A BIT OVER ONE FOOT SHORT OF THE FLOOD STAGE OF 11 FEET WEDNESDAY MORNING. ALSO...THE RIVER LEVEL ON THE OGEECHEE RIVER AT MIDVILLE WAS INCREASING A BIT FASTER THAN FORECAST...AND THIS TREND MAY EVENTUALLY IMPACT THE EXPECTED CREST...CURRENTLY FORECAST LESS THAN ONE HALF FOOT UNDER THE FLOOD STAGE OF 6 FEET LATE THIS WEEK. FINALLY...THE OGEECHEE RIVER AT EDEN WAS SLOWLY RISING AND WAS EXPECTED TO CREST ABOUT ONE AND ONE HALF FEET BELOW THE FLOOD STAGE OF 11 FEET LATER THIS WEEK. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST TUESDAY FOR AMZ374. && $$