Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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567 FXUS62 KRAH 111805 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 105 PM EST THU FEB 11 2016 .SYNOPSIS...A NARROW AREA OF HIGH PRESSURE WILL EXTEND ACROSS CENTRAL NC TODAY THEN DRIFT SOUTHWARD. AN UPPER LEVEL DISTURBANCE WILL CROSS OUR REGION FRIDAY. AN ARCTIC HIGH PRESSURE SYSTEM WILL SEND SOME OF THE COLDEST AIR THIS WINTER SEASON INTO CENTRAL NC FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM THURSDAY... HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY AS A FRONTAL SYSTEM RESIDES TO OUR SOUTH. THE UPPER LEVEL EASTERN CONUS TROUGH WILL BEGIN TO WEAKEN TODAY BUT PLENTY OF COLD AIR STILL IN PLACE AS THICKNESSES SUGGEST HIGH TEMPERATURES TODAY ONLY MAKING IT INTO THE UPPER 30S ACROSS THE NORTH TO LOW 40S IN THE SOUTH. THIS PUTS DAYTIME HIGHS 10-15 DEGREES BELOW NORMAL FOR THIS TIME OF YEAR. A BIT BREEZY AGAIN THIS AFTERNOON WITH WINDS SUSTAINED IN THE 5-10 KT RANGE GUSTING TO NEAR 15 KTS OR SO THIS AFTERNOON. EXPECT LOW TEMPERATURES TONIGHT TO ONCE AGAIN BE IN THE LOW 20S ACROSS THE NORTH. CLOUDS WILL INCREASE FROM THE SOUTHWEST TONIGHT LIMITING COOLING ACROSS THE SOUTHERN COUNTIES...MID 20S IN THESE AREAS. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 350 AM THURSDAY... ...POTENTIAL INCREASING FOR A WINTRY MIX TO OCCUR ACROSS THE EASTERN THIRD OF CENTRAL NC FRIDAY... THE LATEST MODEL GUIDANCE HAS TRENDED WETTER ACROSS THE EASTERN COUNTIES OF NC FRIDAY IN ASSOCIATION WITH A SEWD MOVING UPPER DISTURBANCE. THIS UPPER FEATURE SHOULD INDUCE AN AREA OF LOW PRESSURE TO DEVELOP ALONG THE SC COAST AND MOVE NEWD ALONG/OFFSHORE OF THE NC COAST FRIDAY AFTERNOON-EARLY EVENING. RH CROSS SECTIONS DEPICT PLENTY OF MOISTURE IN THE FAVORED ICE NUCLEATION GROWTH ZONE THOUGH MOISTURE INITIALLY IS LACKING IN THE LOWER LAYERS OF THE COLUMN. THESE LAYERS EVENTUALLY MOISTEN THANKS TO PRECIP FALLING THROUGH THE COLUMN ALONG WITH LOW LEVEL WARM AND MOIST AIR ADVECTION. BY MID-LATE MORNING...ATMOSPHERE APPEARS TO BE SUFFICIENTLY MOIST TO GENERATE PRECIP. LIFT WILL BE SUPPLIED BY A COUPLE OF SOURCES: ONE BEING LOW LEVEL ISENTROPIC UPGLIDE AND THE OTHER INCREASING DIVERGENCE ALOFT IN CONJUNCTION WITH THE NOSE OF A 130KT JET. THIS LIFT APPEARS TO BE MAXIMIZED OVER THE REGION LATE MORNING THROUGH EARLY AFTERNOON. THE TEMPERATURE PROFILE SUGGEST THAT THE PRECIPITATION WILL INITIALLY START OUT AS LIGHT SNOW. AS WARMER AIR STARTS TO OVERSPREAD THE REGION FROM THE SOUTH... SHOULD SEE THE SNOW MIX WITH SLEET THEN EVENTUALLY TRANSITION TO A SLEET/RAIN/SNOW MIXTURE BEFORE ENDING LATE IN THE DAY. AT THIS TIME EXPECT MOST OF THE PRECIP TO OCCUR OVER SECTIONS OF THE SANDHILLS INTO THE COASTAL PLAIN AND THE FAR EASTERN PIEDMONT BETWEEN 10 AM AND 4 PM. OVER THE REST OF THE PIEDMONT...EXPECTING JUST A FEW PATCHES OF LIGHT SNOW OR SNOW FLURRIES. IMPACTS CURRENTLY WILL BE LIMITED TO A QUICK ACCUMULATION ON UNTREATED ROADS/PAVEMENTS WITH AMOUNTS VARYING FROM A DUSTING OVER THE EASTERN SANDHILLS...EASTERN PIEDMONT AND SOUTHERN COASTAL PLAIN...TO UP TO AN INCH OVER SECTIONS OF THE CENTRAL AND NORTHERN COASTAL PLAIN. HIGH TEMPS FRIDAY DEPENDENT ON PRECIP COVERAGE AND TYPE. HAVE LOWERED MAX TEMPS IN THE EAST A FEW DEGREES FROM PREVIOUS FORECAST IN ANTICIPATION OF BETTER PRECIP COVERAGE. HIGH TEMPS FRIDAY LOWER 30S NE TO UPEPR 30S SW. SKIES WILL CLEAR OUT WEST-EAST FRIDAY NIGHT AS THE LOW PRESSURE SYSTEM PULLS AWAY FROM THE NC COAST. NORTH-NWLY WINDS ON THE BACK SIDE OF THE LOW WILL BEGIN TO ADVECT AN ARCTIC AIR MASS INTO CENTRAL NC FRIDAY NIGHT. MIN TEMPS BY EARLY SATURDAY LOWER 20S NORTH AND MID 20S SOUTH. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 325 AM THURSDAY... ...BITTERLY COLD AIR THIS WEEKEND WITH A WINTRY WEATHER THREAT EARLY NEXT WEEK... SATURDAY THROUGH SUNDAY: ARCTIC HIGH PRESSURE WILL BUILD INTO THE REGION ON SATURDAY AS THE DEPARTING SYSTEM LIFTS WELL OFF TO THE NORTH AND EAST OF THE AREA... WHILE A MID/UPPER LOW OVER THE NORTHEAST U.S. TO START THE PERIOD SHIFTS EASTWARD AND OFFSHORE BY SATURDAY NIGHT. THIS SHOULD RESULT IN A DRY... BUT COLD WEEKEND ACROSS CENTRAL NC... WITH BREEZY CONDITIONS EXPECTED ON SATURDAY. THE SURFACE HIGH SHOULD SETTLE OVER THE REGION ON SUNDAY... AT LEAST TAKING AWAY THE ADDED CHILLY BREEZE. WITH LOW LEVEL THICKNESS VALUES EXPECTED TO BE WELL BELOW NORMAL FOR THIS WEEKEND (BOTTOMING OUT NEAR 1230 METERS ON SUNDAY MORNING) THINK TEMPS WILL BE NEAR 20 DEGREES BELOW NORMAL. HIGHS ON SATURDAY MAY STRUGGLE TO REACH FREEZING ACROSS THE NORTHERN HALF OF THE CWA... WITH HIGH TEMPS SUNDAY GENERALLY FREEZING OR BELOW FOR MOST... IF NOT ALL... OF THE CWA. EXPECT HIGH ON SATURDAY WILL RANGE FROM THE LOWER 30S NORTH TO NEAR 40 ACROSS THE FAR SOUTH. HIGHS SUNDAY ARE EXPECTED TO RANGE FROM THE UPPER 20S TO GENERALLY THE LOWER 30S. LOW SUNDAY MORNING WITH SURFACE HIGH PRESSURE JUST TO THE NORTHWEST OF THE AREA ARE EXPECTED TO RANGE FROM AROUND 10 TO 15 DEGREES. SUNDAY NIGHT THROUGH WEDNESDAY: THE NEXT SYSTEM WITH A THREAT OF WINTER WEATHER IS EXPECTED TO AFFECT THE AREA EARLY MONDAY INTO TUESDAY. MEDIUM RANGE MODELS CONTINUE TO SHOW S/W ENERGY TRACKING FROM THE PLAINS INTO THE EASTERN U.S EARLY NEXT WEEK... WHILE AMPLIFYING. THIS SHOULD HELP A SURFACE LOW DEVELOP ACROSS THE SOUTHEAST U.S... WITH PRECIP SPREADING INTO CENTRAL NC IN ADVANCE OF THE APPROACHING SYSTEM ON SUNDAY NIGHT/MONDAY MORNING. MEANWHILE... THE ARCTIC SURFACE HIGH (WHICH WILL BE OVERHEAD ON SUNDAY) WILL SHIFT OFFSHORE SUNDAY NIGHT INTO MONDAY. HOWEVER... THERE SHOULD BE AMPLE COLD DRY AIR IN PLACE TO SUPPORT EITHER SNOW OR SLEET EARLY MONDAY MORNING... FOR LOCATIONS THAT DO INDEED SEE PRECIP (BEST CHANCE ACROSS THE WESTERN/NORTHWESTERN PIEDMONT). HOWEVER... WE ARE TALKING ABOUT S/W ENERGY THAT HAS NOT MOVED ONSHORE YET ACROSS THE WESTERN U.S... WHICH HAS LED TIMING/TRACK/STRENGTH DIFFERENCES WITH THIS SYSTEM FROM RUN TO RUN ALONG WITH A LARGE SPREAD IN THE MODELS AND THE ENSEMBLES... THOUGH IT APPEARS WE SHOULD SEE SOME TYPE OF DAMMING DEVELOP ON MONDAY (IN-SITU POSSIBLY). HOW AMPLIFIED THE TROUGH IS AND THE TRACK AND CONFIGURATION OF THE SURFACE LOW/LOWS WILL GREATLY AFFECT WHAT TYPE OF PRECIP WE SEE ON MONDAY INTO TUESDAY (OUTSIDE OF THE INITIAL LEAD PRECIP WHICH WILL LIKELY BE IN THE FORM OF SNOW OR SLEET). WILL CONTINUE TO TREND THE FORECAST TO THE CLIMATOLOGICAL FAVORED AREAS FOR WINTER PRECIP... WITH MOST LOCATIONS TURNING TO ALL RAIN BY MONDAY EVENING. GIVEN THE TIMING ISSUES THERE IS SOME UNCERTAINTY WITH REGARD TO HOW FAST THE PRECIP WILL EXIT... AND IF WE COULD SEE ANY WRAP AROUND WINTER PRECIP. FOR NOW WILL CONTINUE TO SHOW TEMPS MODERATING ON TUESDAY... WITH ONLY ONE P-TYPE... RAIN. DRY WEATHER IS EXPECTED TO RETURN ON TUESDAY NIGHT AND CONTINUE FOR WEDNESDAY. HIGH AND LOW TEMPS EARLY NEXT WEEK WILL GREATLY DEPEND ON THE TIMING AND TRACK OF THE SYSTEM... THOUGH WE SHOULD SEE LOWS GENERALLY IN THE 20S FOR MONDAY MORNING. TEMPS SHOULD MODERATE BACK TO NEAR NORMAL BY MID NEXT WEEK... WITH HIGHS BACK INTO THE 50S... LOWS IN THE 30S. && .AVIATION /18Z THROUGH TUESDAY/... AS OF 100 PM THURSDAY... VFR CONDITIONS THROUGH MUCH OF THE TAF PERIOD BEFORE GIVING WAY TO MVFR CONDITIONS AT THE VERY END OF THE FORECAST PERIOD AS A LOW PRESSURE SYSTEM MOVES SOUTH OF THE AREA. WEST TO NW WINDS EXPECTED TODAY WITH SOME GUSTING UP TO 15 KTS OR SO. GUSTS WILL DIE DOWN AFTER SUNSET. SKIES WILL REMAIN MOSTLY CLEAR FOR MUCH OF THE DAY. OVERNIGHT TONIGHT EXPECT CEILINGS TO INITIALLY COME IN AROUND 5 KFT BUT THEN DROP TO 1500 FEET OR SO AS PRECIPITATION BEGINS JUST BEFORE 15Z AT KFAY AND THEN OVERSPREADS KRDU AND KRWI. TRIAD SITES MAY STAY VFR WITH THE CEILINGS AS PRECIPITATION IS NOT EXPECTED HERE BUT SOME MVFR VISIBILITIES COULD CREEP IN NEAR THE END OF THE TAF PERIOD. PRECIPITATION FOR KFAY COULD BE IN THE FORM OF A WINTERY MIX WITH SLEET AND FREEZING RAIN POSSIBLE AS WELL FOR A BRIEF PERIOD BEFORE TEMPERATURES WARM UP ENOUGH TO AVOID FREEZING RAIN. FURTHER NORTH...SNOW WILL BE THE PRIMARY FORM OF PRECIPITATION AT KRWI AND KRDU WITH SOME SLEET POTENTIALLY MIXED IN. LONG TERM: ADVERSE CONDITIONS FOR SOUTHERN AND EASTERN TERMINALS WILL CONTINUE THROUGH FRIDAY NIGHT BEFORE RETURNING TO VFR SATURDAY MORNING. CONDITIONS WILL REMAIN VFR UNTIL THE NEXT SYSTEM APPROACHES THE AREA MONDAY INTO TUESDAY. && .CLIMATE... HERE ARE THE RECORD LOWS AND RECORD LOW MAXIMUM TEMPERATURES FOR SAT FEB 13TH AND SUN FEB 14TH AT GSO... RDU... AND FAY: REC YR REC YR LOW LOW MAX ---------------------------------------------- GSO: 02/13 11 1955 31 1986 02/14 6 1905 22 1914 RDU: 02/13 4 1899 10 1899 02/14 -2 1899 27 1916 FAY: 02/13 14 1973 32 1955 02/14 12 1968 33 1916 && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...ELLIS SHORT TERM...WSS LONG TERM...BSD AVIATION...ELLIS CLIMATE...WFO RAH

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