Area Forecast Discussion
Issued by NWS Blacksburg, VA

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071 FXUS61 KRNK 071024 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 524 AM EST SUN FEB 7 2016 .SYNOPSIS...
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LOW PRESSURE ALONG THE SOUTHEAST ATLANTIC COAST WILL SLOWLY MOVE NORTHEAST TODAY...PRECIPITATION ASSOCIATED WITH THIS FEATURE REMAINING EAST OF OUR FORECAST AREA. A SECOND AREA OF LOW PRESSURE WILL MOVE SOUTHEAST ACROSS THE UPPER MIDWEST AND INTO THE GREAT LAKES. THE ARCTIC FRONT ASSOCIATED WITH THIS FEATURE WILL CROSS OUR FORECAST AREA ON MONDAY. FOR TODAY AND TONIGHT WE WILL REMAIN SANDWICHED BETWEEN THE TWO SYSTEMS WITH FAIR/DRY WEATHER. PASSAGE OF THE ARCTIC FRONT ON MONDAY WILL BRING ONSET OF MUCH COLDER TEMPERATURES AND MOUNTAIN SNOW SHOWERS. THE BITTER COLD WILL LAST THROUGH MID WEEK WITH A MULTIDAY SNOW EVENT FOR THE MOUNTAINS.
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&& .NEAR TERM /THROUGH TONIGHT/...
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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.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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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.
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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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.
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&& .AVIATION /10Z SUNDAY THROUGH THURSDAY/... AS OF 1150 PM EST SATURDAY... VFR CONDITIONS ARE EXPECTED THROUGH THE TAF VALID PERIOD. A DEEP COASTAL LOW PRESSURE SYSTEM WILL BE DEVELOPING WELL TO OUR SOUTHEAST THROUGH THE PERIOD...THEN TRACKING NORTHEAST OFF THE SC/NC COAST. THIS SYSTEM WILL SPREAD SOME MID/HIGH CLOUDS ACROSS AREAS ALONG AND EAST OF THE BLUE RIDGE THROUGH THE PERIOD...ESPECIALLY OVERNIGHT/EARLY SUNDAY...BUT ANY CIGS BELOW MUCH BELOW 10KFT ARE EXPECTED TO REMAIN EAST OF THE RNK TAF SITES. TO THE WEST...A DEEPENING LOW WILL BE TAKING SHAPE ACROSS THE WESTERN GREAT LAKES AND MOVING SOUTHEAST. HOWEVER...THIS SYSTEM WILL NOT APPROACH OR IMPACT THE RNK CWA UNTIL JUST BEYOND THE TAF VALID PERIOD...ALTHOUGH MID/HIGH CLOUDS WILL BE APPROACHING WESTERN AREAS TOWARD THE END OF THE TAF VALID PERIOD. NO PRECIPITATION IS EXPECTED AT ANY TAF SITES THROUGH THE TAF VALID PERIOD. THE AIR MASS IS EXTREMELY DRY...SO VISIBILITIES WILL REMAIN VFR. WINDS WILL REMAIN CHAOTIC THROUGH THE PERIOD AS THE REGION FALLS BETWEEN THE DEEPENING COASTAL LOW AND THE SYSTEM APPROACHING FROM THE WEST. A GENERAL TENDENCY TOWARD NNW-NNE WINDS CAN BE EXPECTED EAST OF THE BLUE RIDGE SEEING INFLUENCE FROM THE DEVELOPING COASTAL LOW...WHILE LIGHT/VARIABLE TO LIGHT SW WINDS CAN BE EXPECTED WEST OF THE BLUE RIDGE. EAST OF THE BLUE RIDGE...WINDS WILL TRANSITION MORE TOWARD THE NNW-NW TOWARD THE END OF THE TAF VALID PERIOD. WEST OF THE BLUE RIDGE...SPEEDS SHOULD BE MOSTLY 7KTS OR LESS THROUGH THE TAF VALID PERIOD. TO THE EAST...POTENTIAL FOR 8-12KTS WITH GUSTS TO 20KTS KDAN-KLYH LATE TONIGHT THROUGH SUNDAY AFTERNOON IN RESPONSE TO THE COASTAL LOW. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD. HIGH CONFIDENCE IN VFR VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM CONFIDENCE IN WIND SPEED/DIRECTION THROUGH THE TAF VALID PERIOD. EXTENDED DISCUSSION... FOR MONDAY INTO MID WEEK...A STRONG UPPER LEVEL LOW PRESSURE SYSTEM WILL SINK SOUTHWARD FROM THE GREAT LAKES AND UPPER MIDWEST. AN ASSOCIATED COLD FRONT WILL CROSS THE REGION MONDAY FOLLOWED BY A SECOND SURGE OF ARCTIC AIR TUESDAY. NORTHWEST WINDS WILL INCREASE WITH AN INFLUX OF VERY COLD AIR AND DEEP UPSLOPE MOISTURE. SNOW SHOWERS WILL BEGIN MONDAY AND CONTINUE THROUGH WEDNESDAY EVENING RESULTING IN VISIBILITY RESTRICTIONS ACROSS THE MOUNTAINS IN ADDITION TO LOW CIGS. THIS SHOULD RESULT IN A PROLONGED PERIOD OF MVFR TO IFR AT KBLF/KLWB AND POTENTIAL PERIODS OF MVFR AT KBCB/KROA. ACCUMULATING SNOW IS LIKELY IN THE MOUNTAINS WEST OF THE BLUE RIDGE. FLURRIES MAY OCCUR AS FAR EAST AS THE PIEDMONT WHERE INTERVALS OF VFR TO MVFR CIGS WILL ALSO OCCUR. CONDITIONS SHOULD BRIEFLY RETURN TO MAINLY VFR LATER WEDNESDAY NIGHT ACROSS THE REGION BEFORE POSSIBLY RETURNING TO SUB-VFR AGAIN OVER THE MOUNTAINS DURING THURSDAY WITH ANOTHER WEAK PASSING UPPER IMPULSE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...KK LONG TERM...KK/PW AVIATION...JH/PM/RAB

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