Area Forecast Discussion
Issued by NWS Blacksburg, VA

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862 FXUS61 KRNK 071727 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1227 PM EST SUN FEB 7 2016 .SYNOPSIS... DEEP LOW PRESSURE OFF THE CAROLINAS WILL CONTINUE TO SHIFT SLOWLY NORTHEAST THIS AFTERNOON AND AWAY FROM THE REGION OVERNIGHT INTO EARLY MONDAY. ANOTHER AREA OF UPPER LEVEL LOW PRESSURE ACROSS THE GREAT LAKES WILL SWING A STRONG COLD FRONT ACROSS THE MID ATLANTIC MONDAY...FOLLOWED BY A SECONDARY SURGE OF ARCTIC AIR TUESDAY INTO WEDNESDAY. WEAK IMPULSES COMBINED WITH NORTHWEST FLOW AND DEEP MOISTURE WILL THEN RESULT IN A PROLONGED SNOW SHOWER EVENT ESPECIALLY OVER THE MOUNTAINS INTO MIDWEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 915 AM EST SUNDAY... MODELS DON`T SEEM TO HAVE A GOOD HANDLE ON THE WESTERN EXTENT OF THE CLOUD COVER THIS MORNING. INCREASED SKY COVER THE NEXT FEW HOURS OVER THE NRV AND THE ALLEGHANY HIGHLANDS TO ACCOUNT FOR CURRENT TREND. CURRENT OBS ARE REPORTING LIGHT RAIN ACROSS NASH AND EDGECOMBE COUNTIES IN NC...BUT STILL THINKING ITS TOO DRY ACROSS OUR FORECAST AREA FOR ANYTHING TO REACH THE SURFACE SO DIDN`T ADJUST THE POPS ACROSS THE FAR SE COUNTIES. AS OF 515 AM EST SUNDAY... DEVELOPING STORM ALONG THE SOUTHEAST U.S. COASTLINE WILL BRING RAIN TO THE COAST AND A MIX OF RAIN AND SNOW TO PORTIONS OF THE EASTERN CAROLINAS. PRECIPITATION IS NOT EXPECTED TO REACH INTO OUR FORECAST AREA PER VERY DRY AIRMASS...WHICH EXTENDS FROM THE SURFACE UP THROUGH ABOUT 700 MB...AWAITING TO SWALLOW ANYTHING THAT TRIES TO REACH THIS FAR NORTHWEST. ALL FORECAST MODELS HAVE THIS SYSTEM UNDERGOING RAPID INTENSIFICATION AS IT MOVES NORTHEAST...DEEPENING TO A 980 MB LOW AS IT PASSES WELL OFF THE VA COAST MONDAY MORNING...A WINTERCANE IN THE MAKING. PART OF THE REASON WHY THE COASTAL SYSTEM IS NOT GOING ANY FARTHER INLAND IS THE RESULT OF A KICKER TROUGH WHICH IS RAPIDLY MOVING SOUTHEAST ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST. THE POSITIVE TILT TO THE UPPER TROUGH IS GIVING THE COASTAL SYSTEM A BOOT TO THE EAST. THAT SAID...MOST OF OUR FORECAST FOR THE UPCOMING WEEK WILL HINGE ON IMPACT FROM THE APPROACHING UPPER MIDWEST TROUGH AND THE ARCTIC INTERLUDE THAT IT BRINGS WITH IT BEGINNING MONDAY. UNTIL THE THE ARRIVAL OF MONDAYS ARCTIC FRONT OUR FORECAST AREA WILL REMAIN SANDWICHED BETWEEN THE TWO AREAS OF LOW PRESSURE... SUBSIDENCE BETWEEN THE TWO SYSTEMS KEEPING OUR FORECAST FAIR/DRY THROUGH 12Z/7AM MONDAY. THERE WILL BE A VEIL OF MID/UPPER LEVEL CLOUDINESS WHICH WILL PERSIST OVER THE EASTERN 2/3RDS OF THE CWA TODAY ASSOCIATED WITH THE COASTAL SYSTEM. BIGGEST IMPACT WILL BE TO KEEP TEMPERATURES DOWN. FOR AREAS EAST OF HIGHWAY 29 SHAVED AT LEAST 5 DEGREES OFF OF MAV MOS WITH THE THINKING THAT TEMPERATURES WILL STRUGGLE WHERE THE THICKER CLOUDS PERSIST. WEST OF THE BLUE RIDGE THERE SHOULD BE MORE SUN AND AN OPPORTUNITY TO REACH FULL INSOLATION THIS AFTERNOON. FOR TONIGHT...CLOUDS WILL EXIT THE EAST...BUT THEN BEGIN TO INCREASE IN THE WEST PER THE APPROACH OF THE UPPER MIDWEST TROUGH. NO PRECIPITATION IS EXPECTED ANYWHERE IN THE FORECAST AREA TONIGHT WITH A DRY FORECAST BEING MAINTAINED THROUGH 0700 MONDAY. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 400 AM EST SUNDAY... LOW PRESSURE OFF THE VIRGINIA COAST MONDAY MORNING WILL INTENSIFY AS IT LIFTS NORTHEAST ALONG THE EAST COAST MONDAY AFTERNOON INTO MONDAY NIGHT. AS THE COASTAL LOW EXITS TO THE NORTHEAST ON MONDAY...A BROAD UPPER LEVEL TROUGH IN THE NORTHERN STREAM WILL DIG SOUTHWARD FROM THE GREAT LAKES TOWARD THE MID ATLANTIC REGION. A STRONG CLIPPER SYSTEM ALONG THE LEADING EDGE OF THIS TROUGH WILL PROVIDE LIFT TO GENERATE LIGHT SNOW WEST OF THE BLUE RIDGE DURING MONDAY. THE NAM...GFS AND ECMWF HAVE ALL SLOWED THE ARRIVAL OF THE MOISTURE ON MONDAY. DECREASED POPS FOR THE MONDAY MORNING IN THE EAST AND SPREAD MOISTURE ACROSS FORECAST AREA MONDAY AFTERNOON. PRECIPITATION TYPE IS ALSO PROBLEMATIC WITH MORE SNOW IN WEST AND RAIN IN THE EAST. FOR EXAMPLE...LOCATIONS IN THE PIEDMONT MIGHT START AS SNOW FLURRIES MONDAY MORNING BEFORE CHANGING TO RAIN WITH TEMPERATURES RISING INTO THE 40S. THE RAIN WOULD CHANGE BACK TO SNOW FLURRIES BY MONDAY EVENING INTO MONDAY NIGHT AS TEMPERATURES DROP. USED A MIXTURE OF RAIN AND SNOW FOR MONDAY...THEN TRANSITION TO SNOW SHOWERS FOR MONDAY NIGHT. THE SLOWER ARRIVAL...MIXTURE OF RAIN AND SNOW...AND TEMPERATURES WILL HINDER SNOW ACCUMULATIONS ON MONDAY. HIGH TEMPERATURES MONDAY WILL RANGE FROM THE LOWER 30S IN THE NORTHWEST MOUNTAINS TO THE MID 40S IN THE PIEDMONT. THE BROAD UPPER LEVEL TROUGH WILL BE OVERHEAD BY MONDAY NIGHT...AS A DEEP ARCTIC AIR MASS SPILLS OVER THE FORECAST AREA. WITH THE COLD AIR COMING IN...SNOW SHOWERS AND SNOW FLURRIES WILL KICK IN ESPECIALLY ALONG THE WESTERN SLOPES. LOW TEMPERATURES MONDAY NIGHT WILL VARY FROM THE TEENS IN THE MOUNTAINS TO THE MID 20S IN THE PIEDMONT. THE COMBINATION OF WIND AND TEMPERATURES MAY PRODUCE WIND CHILLS MONDAY NIGHT INTO TUESDAY MORNING INTO THE SINGLE DIGITS AND TEENS IN THE MOUNTAINS. A FEW OF THE HIGHEST ELEVATIONS IN NORTHWEST NORTH CAROLINA MAY APPROACH WIND CHILL ADVISORY LEVELS. SNOW ACCUMULATIONS ON MONDAY COULD RANGE FROM A COATING TO AROUND 5 INCHES IN NORTHWEST GREENBRIER COUNTY. WITH A LATER ONSET TIME...AND COORDINATION WITH SURROUNDING WFOS DECIDED TO HOLD OFF ON ANY SNOW ADVISORIES AT THIS TIME WITH THE PROLONG NORTHWEST SNOW EVENT. WILL MENTION THE POTENTIAL FOR WINTER WEATHER HEADLINES FOR MONDAY AFTERNOON/EVENING INTO TUESDAY...IN THE HWO. ENERGY FROM THE GREAT LAKES LOW PRESSURE SYSTEM WILL TRANSFER TO COASTAL LOW OFF THE NORTH CAROLINA COAST TUESDAY. SNOW ACCUMULATIONS OF ONE TO THERE INCHES MAY BE POSSIBLE ON TUESDAY INTO TUESDAY NIGHT IN THE WEST MOUNTAINS WITH LIGHT AMOUNTS TO THE EAST. HIGH TEMPERATURES TUESDAY WILL VARY GREATLY FROM THE LOWER 20S IN THE NORTHWEST MOUNTAINS TO THE LOWER 40S IN THE PIEDMONT. LOW TEMPERATURES TUESDAY NIGHT INTO WEDNESDAY MORNING WILL DROP INTO THE TEENS TO THE MID 20S IN THE SOUTHEAST. WIND CHILL READINGS ON TUESDAY NIGHT INTO WEDNESDAY MORNING... MAY BE AS COLD AS THE SINGLE DIGITS WEST OF THE BLUE RIDGE BY DAWN...AND POSSIBLY HIT ZERO ALONG THE WESTERN SLOPES. WILL INCLUDE MENTION OF SNOW AND WIND CHILLS IN THE HWO. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 400 AM EST SUNDAY... A DEEP ARCTIC AIR MASS SHOULD REMAIN ENTRENCHED OVER THE MID ATLANTIC DURING WEDNESDAY AND THURSDAY. PERSISTENT NORTHWEST FLOW SHOULD KEEP THE UPSLOPE SNOW MACHINE IN ACTION THROUGH WEDNESDAY ALONG THE WESTERN SLOPES...BUT THE PIEDMONT SHOULD STAY DRY FROM THE DOWNSLOPE FLOW. ALTHOUGH THE SNOWFALL THREAT WILL DECREASE LATER IN THE WORK WEEK...THE THREAT FOR LOW WIND CHILL VALUES WILL INCREASE. THE LONG RANGE MODELS PROJECT THAT THE WIND CHILL VALUES SHOULD APPROACH WIND CHILL ADVISORY CRITERIA OF -5 F IN THE WESTERN MOUNTAINS ON EARLY WEDNESDAY MORNING...AND EVEN LOWER TO -10 F BY THURSDAY MORNING. WITH LOW TEMPERATURES DIVING INTO THE TEENS AND UPPER SINGLE DIGITS AND A DECENT NORTHWEST BREEZE...THE WIND CHILL THREAT IS WORTHY ENOUGH TO NOTE IN THE HWO. TEMPERATURES SHOULD MODERATE A LITTLE BY FRIDAY AS THE UPPER LEVEL TROUGH PUSHES EASTWARD. THE TROUGH AXIS LINGERS INTO THE WEEKEND. THE ECMWF AND GFS SIGNIFICANTLY DIVERGE BEYOND FRIDAY INTO EARLY NEXT WEEK. THE TIMING AND PLACEMENT OF SEVERAL SHORTWAVE ROTATING AROUND THE UPPER TROUGH ARE DIFFERENT. THE PLACEMENT OF THE MOISTURE AND POTENTIAL DEVELOPMENT OF ANOTHER COASTAL LOW BY SATURDAY REMAIN IN QUESTION. IN GENERAL...TEMPERATURES WILL REMAIN BELOW NORMAL DURING THE MEDIUM RANGE. && .AVIATION /17Z SUNDAY THROUGH THURSDAY/... AS OF 1212 PM EST SUNDAY... MID AND HIGH LEVEL CANOPY ASSOCIATED WITH THE STORM SYSTEM OFF THE CAROLINAS WILL LINGER OVER MUCH OF THE REGION THIS AFTERNOON BEFORE FINALLY SHIFTING EAST THIS EVENING. HOWEVER STILL EXPECTING CIGS TO REMAIN VFR WITH MOST BASES ABOVE 10K FEET. WINDS WILL BE GUSTY AS THE SYSTEM DEEPENS OFFSHORE WITH NORTHERLY WINDS INCREASING TO 10-20 KTS AT TIMES. SHOULD GET IN BETWEEN THE EXITING OFFSHORE LOW TONIGHT AND THE NEXT UPSTREAM COLD FRONT WITH THE NEXT SURGE OF MOISTURE EXPECTED TO ARRIVE MONDAY. THIS SHOULD PROVIDE FOR A PERIOD OF CLEAR SKIES OVERNIGHT BEFORE ANOTHER ROUND OF MID DECK ARRIVES OVER THE WEST AFTER MIDNIGHT. AXIS OF DEEPER MOISTURE SHOULD BE NEARING KBLF/KLWB BY 12Z/7AM MONDAY WITH PERHAPS THE ONSET OF MVFR VSBYS SHORTLY THEREAFTER PENDING TIMING OF THE PRECIP. HOWEVER THINK CIGS WILL REMAIN VFR UNTIL AFTER DAYBREAK WITH MOSTLY MID/HIGH CLOUDS TO THE EAST. LOBE OF DEEPER MOISTURE WITH AN ASSOCIATED PERIOD OF SNOW/RAIN LOOKS TO CROSS THE REGION FROM WEST TO EAST AHEAD OF AN INITIAL COLD FRONT DURING MONDAY. THIS SHOULD CAUSE CIGS TO LOWER TO MVFR/IFR SE WEST VA SITES AND MVFR OUT TO THE BLUE RIDGE AROUND MIDDAY. EXPECT TO SEE MVFR TO IFR VSBYS IN SNOW ALSO AT KBLF/KLWB DURING THE MORNING WITH THIS PRECIP AND LOWER VSBYS SPREADING OUT TOWARD KBCB/KROA BY MIDDAY. SOME LIGHT RAIN ALSO POSSIBLE IN THE EAST MAINLY AFTER THE VALID TAF PERIOD ON MONDAY BUT EXPECT A BREAK FROM SUB-VFR ALONG/WEST OF THE BLUE RIDGE TO VFR CIGS OUT EAST IN THE AFTERNOON. EXTENDED DISCUSSION... SUB-VFR SHOULD BECOME MORE CONFINED TO THE WESTERN SLOPES MONDAY NIGHT INTO MIDWEEK WITH PROLONGED MVFR/IFR CONDITIONS AT KBLF/KLWB IN SNOW SHOWERS THROUGH AT LEAST WEDNESDAY NIGHT AS ARCTIC AIR ARRIVES. POTENTIAL ALSO FOR PERIODS OF MVFR AT KBCB/KROA AS IMPULSES ROTATE ACROSS THE MOUNTAINS AND BANDS DEVELOP DURING THE OVERNIGHT HOURS. ACCUMULATING SNOW IS LIKELY IN THE MOUNTAINS WEST OF THE BLUE RIDGE. FLURRIES MAY ALSO OCCUR AS FAR EAST AS THE PIEDMONT WHERE INTERVALS OF VFR TO MVFR CIGS COULD ALSO OCCUR. CONDITIONS SHOULD BRIEFLY RETURN TO MAINLY VFR THURSDAY/THURSDAY NIGHT AS WEAK HIGH PRESSURE BUILDS IN AND MOISTURE DECREASES. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/PM NEAR TERM...CF/PM SHORT TERM...KK LONG TERM...KK/PW AVIATION...JH/PM

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