Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 011544 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1044 AM EST SUN MAR 1 2015 .SYNOPSIS... HIGH PRESSURE TO OUR NORTH WILL MAINTAIN COLD AIR OVER THE AREA INTO THIS AFTERNOON. MEANWHILE...AN UPPER LEVEL DISTURBANCE AND ASSOCIATED AREA OF SURFACE LOW PRESSURE WILL MOVE ACROSS THE MID ATLANTIC REGION BY THIS AFTERNOON BEFORE EXITING THIS EVENING. MOIST AIR FLOWING NORTH AHEAD OF THIS DISTURBANCE WILL INTERACT WITH THE COLD AIR RESULTING IN A WINTRY MIX OF PRECIPITATION ACROSS THE MID ATLANTIC STATES TODAY...BEFORE A COLD FRONT ARRIVES OVERNIGHT BRINGING DRIER AIR FOR MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1043 AM EST SUNDAY... CANCELLED THE WINTER WEATHER ADVISORY IN THE WEST AS WARMER AIR (TEMPERATURES ABOVE FREEZING) PUSHING IN WITH LACK OF PCPN. THE REST OF WINTER WEATHER ADVISORY REMAINS IN EFFECT. WILL CONTINUE TO TRIMMED HEADLINES AS WARM AIR ADVANCES. MODIFIED TEMPERATURES AND HIGHS FOR THIS AFTERNOON WITH LATEST OBS AND MODELS. AS OF 905 AM EST SUNDAY... ISENTROPIC LIFT OVER TOP THE CAD CONTINUES TO RESULT IN WINTRY MIX OF SNOW...SLEET AND FREEZING RAIN THIS MORNING. WINTER WEATHER ADVISORIES WILL REMAIN AS POSTED FOR NEXT COUPLE OF HOURS BUT WILL BE TRIMMED BACK AS THE WARMER AIR JUST TO OUR WEST PUSHES INTO OUR REGION ENDING THE THREAT. THE HEAVIEST BAND OF SLEET AND FREEZING RAIN LOCATED IN THE SOUTHEAST PORTION OF FORECAST AREA WILL LIFT NORTHEAST THIS MORNING. FREEZING RAIN RATES FROM TRACE TO AROUND A 0.10 INCH PER 3 HOURS ARE POSSIBLE THROUGH 16Z. ADJUSTED POPS WITH A BLEND OF HIRESW-ARW...RNK WRFARW AND GFS FOR THIS MORNING INTO THIS AFTERNOON. ADJUSTED TEMPERATURES ACCORDING TO LATEST OBS AND MODEL TREND THIS MORNING. WILL HAVE TO ADJUST HIGH TEMPERATURES DEPENDING ON THE PUSH OF THE WARM AIR. MORE ADJUSTMENTS LATER THIS MORNING. AS OF 215 AM EST SUNDAY... AREA REMAINS UNDER THE DRY WEDGE ALONG/EAST OF THE MOUNTAINS THIS MORNING WHICH IS BASICALLY IN BETWEEN SHORTWAVE ENERGY PASSING TO THE NW AND RETURN FLOW DEEPER MOISTURE TO THE SOUTH. LATEST GUIDANCE HAS TURNED A BIT LESS ENTHUSIASTIC IN REGARDS TO CONNECTING THESE AREAS OF LIFT UNTIL THE PRECIP TURNS OUT EAST OF THE BLUE RIDGE LATER THIS MORNING WITH MOST SHOWING MUCH LESS QPF NOW OVER THE WEST. THIS SEEN WITH THE EASTWARD TRENDS OFF BOTH THE GFS/NAM AND ALMOST TOTAL LACK OF PRECIP HEADING UP FROM THE SOUTH OFF THE 00Z EC GIVEN SO MUCH DRY AIR IN PLACE. HOWEVER APPEARS ENOUGH WEAK ISENTROPIC LIFT OVER TOP THE CAD FROM THE SOUTH TO GENERATE SOME LIGHT QPF MOUNTAINS/SW BEFORE DAYBREAK...WITH THE AXIS OF RETURN MOISTURE THEN TURNING MORE EAST/NE WHILE PRIMARILY AFFECTING THE FOOTHILLS/PIEDMONT THIS AFTERNOON WHEN TEMPS WILL BE SLOWLY RISING. THINK THE CORRIDOR OF SNOW TO THE NW WITH THE MAIN AXIS OF DEEPER LIFT WILL PASS TO THE NORTH BUT MAY CLIP THE NW CORNER WITH A PERIOD OF SNOW SO KEPT AN INCH OR TWO THERE. OTRW LATEST FORECAST SOUNDINGS SUPPORT MORE SLEET BANDS AND POCKETS OF SNOW STARTING FROM SOUTH TO NORTH EARLY ON AIDED BY EVAPORATIVE COOLING...THEN SWITCHING TO MORE LIQUID/FZRA AS THE LARGE WARM NOSE ALOFT WINS OUT AND WET BULBING DECREASES ESPCLY FROM MID MORNING ON. HOWEVER PRECIP COVERAGE OVER THE WEST MAY BE DECREASING QUICKLY BY LATE MORNING WITH PERHAPS THE MOUNTAIN EMPIRE REGION INTO THE NW NC RIDGES SEEING ONLY SPOTTY AMOUNTS. APPEARS BEST SHOT AT ICING WILL BE FROM THE NC FOOTHILLS NORTH ALONG THE SOUTHERN BLUE RIDGE INITIALLY...THEN EAST WHERE THE DEEPER LOW LEVEL COLD AIR WILL RESIDE UNTIL VERY LATE IN THE DAY. APPEARS A GOOD TENTH OR SO ICE ACCRETION POSSIBLE FOR MUCH OF THE AREA EAST OF THE BLUE RIDGE BUT PERHAPS LESS THAN SEEN FROM EARLIER GUIDANCE. THUS TRIMMED BACK TOTALS SOME PER LATEST WWD AND THE FORECAST WARMER BOUNDARY LAYER LIKELY DUE TO LESS SIGNIFICANT PRECIP TO COOL THE COLUMN BUT LEAVING THE GOING ADVISORY IN PLACE. HIGH TEMPS REMAIN VERY TRICKY GIVEN MUCH WARMER MOS VALUES AND POTENTIAL FOR AN AFTERNOON DRY SLOT ESPCLY WEST AS SEEN OFF THE LATEST HRRR/CMC AND GFS TO SOME DEGREE. FOR NOW BUMPED UP HIGHS A GOOD CAT OR SO FAR WEST WHERE WILL BE ON THE PERIPHERY OF THE WEDGE AND WARMED THE EAST A DEGREE OR TWO FOR MORE OF A LATE DAY HIGH SCENARIO PENDING PRECIP COVERAGE. WEAK SUBSIDENCE SPILLS IN BEHIND THE DEPARTING SWATH OF DEEPER MOISTURE THIS EVENING LEAVING A RESIDUAL AXIS OF WRAP AROUND TYPE PRECIP OVER THE NW AHEAD OF THE UPSTREAM COLD FRONT THAT WILL REACH THE WESTERN SLOPES LATE. COULD BE SOME SPOTTY -RA/DZ/FOG AROUND DURING THE EVENING INCLUDING POCKETS OF VALLEY -FZRA NORTH/NE OTRW MOST RAIN WILL BE CONFINED TO THE NW. DEEPER COLD ADVECTION ARRIVES AFTER MIDNIGHT ON INCREASING/GUSTY NW WINDS MOUNTAINS WITH THE 85H FRONT CROSSING THE WESTERN SLOPES WHICH SHOULD ALLOW RAIN TO CHANGE TO SNOW SHOWERS BEFORE TAPERING AROUND DAYBREAK. THIS MAY RESULT IN ANOTHER INCH OR SO OF SNOW NW SLOPES WITH SPOTTY COVERAGE DOWN IN THE NC MOUNTAINS AND MAINLY CLOUDS ELSEWHERE OVERNIGHT. TEMPS SHOULD STEADY IF NOT RISE AHEAD OF THE FRONT OVERNIGHT AS THE WARM ADVECTION BOOTS THE WEDGE OUT BEFORE COLDER AIR ARRIVES NW LATE ALLOWING TEMPS TO DROP AGAIN AROUND SUNRISE. DID TREND TOWARD THE COLDER MAV MOS OVERNIGHT ALTHOUGH SOME SPOTS THAT GET WARMER DURING THE DAY MAY STAY IN THE 40S OVERNIGHT. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... AS OF 330 AM EST SUNDAY... HIGH PRESSURE BUILDING IN BEHIND THE FRONT ON MONDAY WILL BRING AN END TO UPSLOPE SNOW SHOWERS FOR THE FAR WESTERN SLOPES. THERE LOOKS TO BE A GOOD AMOUNT OF WIND THROUGH THE FIRST PART OF MONDAY AND... IF MODEL TRENDS CONTINUE TO SHOW A STRONG LOW LEVEL WIND FIELD...A WIND ADVISORY MAY BE NECESSARY FROM THE BLUE RIDGE WEST. BY MONDAY NIGHT...THE HIGH WILL CONTINUE TO SLIDE EAST AND WE WILL FIND OUR AREA ONCE AGAIN DEALING WITH A COLD AIR WEDGE DOWN THE EASTERN SEABOARD. WITH THE LOW LEVEL COLD AIR STILL IN PLACE AS PRECIPITATION FROM AN APPROACHING LOW PRESSURE SYSTEM MOVES IN TOWARD DAYBREAK TUESDAY WE CAN ONCE AGAIN LOOK FOR SOME SLEET AND FREEZING RAIN. THE GREATEST ICING LOOKS TO BE FROM THE NEW/ROANOKE VALLEYS NORTH THROUGH THE GREENBRIER VALLEY AND ALLEGHANY HIGHLANDS LATE ON TUESDAY BEFORE TEMPS WARM ABOVE FREEZING AND WE GO TO PLAIN RAIN TUESDAY NIGHT INTO WEDNESDAY. WEDNESDAY WILL SEE LOW PRESSURE MOVE THROUGH THE GREAT LAKES AND PUSH A STRONG COLD FRONT THROUGH THE REGION. WE WILL SEE A GOOD DOSE OF RAIN ALONG AND AHEAD OF THE COLD FRONT ON WEDNESDAY...THEN MORE PRECIPITATION WEDNESDAY NIGHT AS A WAVE DEVELOPS ALONG THE FRONT AND MOVES THROUGH THE CAROLINAS TO THE MIDDLE ATLANTIC COAST. GUIDANCE CURRENTLY INDICATES WESTERN AREAS WILL RECEIVE MOST OF THE PRECIPITATION WITH THE FRONT ON WEDNESDAY AND EASTERN AREAS WILL RECEIVE MOST OF THE PRECIPITATION WITH THE WAVE WEDNESDAY NIGHT. THIS WILL SPREAD OUT THE QPF LOAD AND HOPEFULLY WORK TO ALLEVIATE POTENTIAL FLOODING...BUT THIS IS A VERY FINE LINE AND WE WILL HAVE TO SEE HOW THE SITUATION DEVELOPS IN LATER MODEL RUNS. ALSO...THIS SYSTEM IS QUITE ENERGETIC AND WILL HAVE TO BE WATCHED FOR DEVELOPMENT OF CONVECTIVE ELEMENTS SINCE THEY MAY BE CAPABLE OF MIXING DOWN STRONG LOW LEVEL WINDS. ADDITIONALLY...AS MUCH COLDER AIR MOVES IN BEHIND THE FRONT ON WEDNESDAY WE WILL SEE PRECIPITATION CHANGE OVER TO SNOW WESTERN GREENBRIER COUNTY INTO NORTHERN PORTIONS OF THE ALLEGHANY HIGHLANDS LATE IN THE AFTERNOON. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... AS OF 405 PM EST SATURDAY... THE PASSAGE OF THE COLD FRONT WILL BRING WITH IT ANOTHER SHOT OF ARCTIC AIR THAT WILL END OUR SPRING-LIKE WEATHER FOR THE TIME BEING. AS SUCH... EXPECT RAIN TO CHANGE TO SNOW ACROSS THE MOUNTAINS WEDNESDAY NIGHT...WITH SNOW SHOWERS EXTENDING INTO THE PIEDMONT EARLY THURSDAY. MODELS ARE VERY AGGRESSIVE IN WORKING THE COLDER AIR INTO THE REGION...BUT PREFER TO BE MORE CONSERVATIVE AT THIS POINT UNTIL WE GET CLOSER IN TIME TO THE EVENT. PRECIPITATION WILL GRADUALLY WIND DOWN DURING THURSDAY AFTERNOON AS THE WAVE EXITS THE AREA...AND HIGH PRESSURE BUILDS IN FROM THE WEST. HIGH PRESSURE WILL PASS ACROSS THE AREA ON FRIDAY...RESULTING IN LIGHT WINDS AND MOSTLY CLEAR SKIES...IN ADDITION TO AFTERNOON TEMPERATURES IN THE 30S WEST AND THE 40S EAST. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... AS OF 600 AM EST SUNDAY... MVFR CIGS HAVE OVERSPREAD THE REGION THIS MORNING AND EXPECT CONTINUED LOWERING OF BASES AS MOISTURE CONTINUES TO INCREASE. HOWEVER WHERE THERE IS LITTLE PRECIP INITIALLY...EXPECT CIGS TO STAY HIGHER AND BE SLOWER TO DROP EARLY THIS MORNING. MAIN CORRIDOR OF PRECIP WILL BE OVER THE SOUTH AROUND KDAN WHERE A MIXTURE OF SLEET AND -FZRA WILL OCCUR OFF AND ON THROUGH MID MORNING. ELSEWHERE A BIT TRICKY AS TO WHEN PRECIP WILL REACH THE SURFACE GIVEN DRY AIR AND CURRENT SPLIT IN ECHOES ON RADAR OVER CENTRAL SECTIONS. APPEARS SITES SUCH AS KLWB MAY SEE A PERIOD OF SNOW/SLEET WITH MVFR VSBYS AT BOTH KLWB AND KDAN. OTHERWISE AS THE MOISTURE ENCOUNTERS THE COLD AIR OVER THE MID ATLANTIC...EXPECT A WINTRY MIX WITH SNOW/SLEET AT THE ONSET...CHANGING TO FREEZING RAIN THIS MORNING. KBLF MAY ONLY SEE PLAIN RAIN GIVEN SURFACE TEMPS SO INCLUDING LESS OF A MIXTURE THERE. VERY LITTLE SNOW/SLEET ACCUMULATION IS EXPECTED...HOWEVER...UPWARDS OF A TENTH OF AN INCH OF ICE ACCRETION IS EXPECTED FROM THE FREEZING RAIN. TEMPERATURES WILL START OFF BELOW FREEZING IN THE MORNING...THEN CREEP ABOVE FREEZING DURING THE AFTERNOON. WARMING TEMPERATURES WILL ALSO SIGNAL DECREASE IN VSBY DUE TO DEVELOPMENT OF FOG AND LOWERING CIGS DUE TO THE DEVELOPMENT OF LOW LEVEL STRATUS. WIDESPREAD IFR IS ANTICIPATED BY THIS AFTERNOON IN MOST LOCATIONS. MODELS HAVE NOT DONE A VERY GOOD JOB WITH THE CLOUD FORECAST...SO USING PAST EXPERIENCE WITH SIMILAR PATTERN RECOGNITION TO FORECAST CLOUD LAYERS AND P-TYPE. IN THIS SITUATION THINK INTRODUCTION OF LOW CLOUD WILL HOLD OFF UNTIL JUST PRIOR TO PRECIP ONSET. POOR FLYING CONDITIONS WILL CONTINUE TONIGHT WITH RESIDUAL LOW LEVEL MOISTURE IN PLACE AHEAD OF A COLD FRONT TO THE WEST. APPEARS WIDESPREAD MVFR/IFR CIGS AND VSBYS LIKELY OVERNIGHT WITH ANOTHER ROUND OF DRIZZLE...THEN AN INCREASE IN RAIN/SNOW SHOWERS WEST ALONG AND BEHIND THE FRONT. .EXTENDED FORECAST... A SHARP COLD FRONT WILL CROSS THE AREA MONDAY WITH NORTHWEST WINDS INCREASING ALONG WITH UPSLOPE MVFR CIGS/VSBYS IN SNOW SHOWERS AT KBLF/KLWB. ON THE HEELS OF THE SUNDAY/MONDAY SYSTEM WILL BE YET ANOTHER POTENTIALLY POTENT SYSTEM THAT MAY IMPACT ALL OR PARTS OF THE REGION TUESDAY INTO WEDNESDAY WITH SUB-VFR DEVELOPING IN MOST LOCATIONS LATER TUESDAY INTO WEDNESDAY...WITH POST FRONTAL MVFR TO IFR POSSIBLE IN RAIN/SNOW ON THURSDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR VAZ010>014-016>020-022>024-032>035-043>047-058-059. NC...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NCZ003>006-019-020. WV...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR WVZ042>044-507-508. && $$ SYNOPSIS...JH/PM NEAR TERM...JH/KK SHORT TERM...MBS LONG TERM...NF AVIATION...JH/PM

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