Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 240854 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 354 AM EST MON NOV 24 2014 .SYNOPSIS... A WARM FRONT WILL LIFT NORTH OF THE AREA THIS MORNING ALLOWING A WARM SOUTHWEST FLOW OF AIR TO PREVAIL AHEAD OF A COLD FRONT TO OUR WEST. THE COLD FRONT MOVES THROUGH LATER TONIGHT INTO TUESDAY...BRINGING COLDER TEMPERATURES OVER THE NEXT FEW DAYS. A STORM SYSTEM MOVING UP ALONG THE CAROLINA COAST WILL BRING THE NEXT ROUND OF PRECIPITATION FOR THE MIDDLE OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 AM EST MONDAY... SHOWERS HAVE QUICKLY EXITED EARLY THIS MORNING AHEAD OF A LARGE DRY SLOT ALOFT PER VAPOR LOOP IN ADVANCE OF THE LAGGING COLD FRONT WELL TO THE WEST. SURFACE WARM FRONT WILL LIFT NORTH OF THE AREA AS WELL THIS MORNING LEAVING A DEEP SW FLOW OF MILD AIR FOR MUCH OF THE DAY BUT WITH LITTLE ADDED FOCUS. THUS HAVE ALL BUT REMOVED POPS FOR TODAY WITH ONLY AN ISOLATED SHOWER POSSIBLE MOUNTAINS EARLY. OTRW MAIN QUESTION WITH HOW HIGH TEMPS CAN GO THIS AFTERNOON GIVEN SUCH WARMTH ALOFT TO INIT AND QUITE MILD SURFACE TEMPS PER SOME SPOTS STARTING OUT IN THE 60S. APPEARS KEY WITH JUST HOW MUCH SUNSHINE CAN BREAK THROUGH CURRENT RESIDUAL LOW CLOUDS EARLY ON ALTHOUGH THE MET MOS REMAINS THE WARMEST EVEN WITH CLOUDS. SINCE APPEARS MIXING WILL BE QUITE STRONG AND PERHAPS NEAR ADVISORY LEVEL WIND SPEEDS FAR WEST...PLAN TO LEAN TOWARD THE WARMER GUIDANCE ESPCLY EAST WHERE LOW/MID 70S POSSIBLE...WITH MID/UPPER 60S OUTSIDE OF HIGHER ELEVATIONS WEST. THIS MAY PUT A FEW SPOTS NEAR RECORD HIGHS ESPCLY IF CLOUDS MIX OUT MORE SO INCLUDED IN THE CLIMATE SECTION BELOW. INITIAL WEAK SURFACE COLD FRONT TO THE WEST WILL SLIDE ACROSS OVERNIGHT WHILE THE ACTUAL 85H BOUNDARY LOOKS TO GET STUCK ALONG/WEST OF THE BLUE RIDGE LATE. THIS MAY KEEP THE EAST QUITE WARM OVERNIGHT WITH ONLY BLEEDING IN COLD ADVECTION OVER THE WEST WHERE 85H TEMPS WILL SLOWLY FALL BELOW 0C. HOWEVER PERIODIC INFLUX OF HIGH CLOUDS UNDER THE SW FLOW ALOFT MAY HINDER LOWS FURTHER...SO TRENDED LOWS UP WITH PERHAPS SPOTS IN THE EAST STAYING IN THE 50S AND ONLY THE FAR WEST DIPPING INTO THE MID/UPPER 30S. OTRW OVERALL PC EXCEPT MORE LOW CLOUDS NW SLOPES WITH THE UPSLOPE COMPONENT BUT WITHOUT POP OVERNIGHT. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 338 PM EST SUNDAY... OVERALL PATTERN THIS TIME FRAME IS FOR SPLIT FLOW WITH AN ACTIVE NORTHERN STREAM ALONG THE CANADIAN/NORTHERN U.S. BORDER AND SOUTHERN STREAM THAT HAS A STRONG SHORT WAVE AT THE BASE OF THE TROF OVER THE LOWER MISSISSIPPI VALLEY BY LATE TUESDAY. EVOLUTION AND TIMING OF LONG WAVE TROF FROM POSITIVE TILT TO NEGATIVE TILT AND AMOUNT OF PHASING BETWEEN THE TWO JET STREAMS WILL IMPACT THE RESULTING TRACK OF THE GULF TO EAST COAST SURFACE LOW AND LOCATION OF THE HEAVIEST PRECIPITATION. AT THIS TIME SPREAD IN DIFFERENT MODELS IS LARGE. HIGHEST CONFIDENCE IS WITH THE TIMING BUT MUCH LOWER WITH THE LOCATION AND TYPE OF PRECIPITATION. WILL BE LEANING TOWARD BLEND OF THE ECMWF AND GFS AS SUGGESTED BY WPC. MODELS SHOW MID ATLANTIC REGION IN THE RIGHT REAR QUADRANT OF A 170 KNOT UPPER JET BY LATE TUESDAY NIGHT. AT THE SURFACE THE COLD FRONT MOVES OFF THE EAST COAST MONDAY NIGHT THEN HIGH PRESSURE BUILDS FROM THE TENNESSEE VALLEY INTO THE MID ATLANTIC STATES ON TUESDAY. LOW PRESSURE DEVELOPS IN THE GULF OF MEXICO ON TUESDAY...THEN TRACKS ACROSS FLORIDA TUESDAY NIGHT. THE LOW SHOULD BE OFF THE SOUTH CAROLINA COAST ON WEDNESDAY MORNING AS IT MOVES NORTHEAST AND BEGINS TO DEEPEN. ONCE THE LOCATION OF THE PRECIPITATION IS DETERMINED...TEMPERATURES WILL INFLUENCE WHAT TYPE OF PRECIPITATION WILL OCCUR. EVEN TAKING THE COOLER MET/SREF GUIDANCE FOR TEMPERATURES ON TUESDAY NIGHT AND WEDNESDAY...SURFACE VALUES MAY STILL BE TOO WARM EAST OF THE BLUE RIDGE TO SUPPORT ANYTHING BUT RAIN. HAVE USED PARTIAL THICKNESS VALUES...MAINLY FROM THE GFS/ECMWF TO PLACE RAIN/SNOW LINE. THIS WILL CHANGE AS THE EVENT DRAWS CLOSER. LOOKED AT PROBABILITY FOR SNOW AND CORRELATION WITH PAST ANALOG EVENTS. APPEARS THERE IS AT LEAST THE POTENTIAL FOR SOME WINTER PRECIPITATION. SINCE WEDNESDAY IS A MAJOR TRAVEL DAY WILL MENTION POTENTIAL FOR WINTER PRECIPITATION IN THE HAZARDOUS WEATHER OUTLOOK. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 130 PM EST SUNDAY... THIS PORTION OF THE FORECAST STARTS WITH THE AFTERMATH OF WHAT UNFOLDS TUESDAY NIGHT INTO WEDNESDAY EVENING. GIVEN THERE STILL IS GENEROUS UNCERTAINTY IN THOSE EVENTS...THE EVENTS AFTERWARDS ARE EQUALLY CHALLENGING. THE GENERAL CONSENSUS IS FOR A LOW/TROUGH TO DEEPEN ACROSS THE GREAT LAKES/OHIO VALLEY AS THE SYSTEM ALONG THE COAST HEADS NORTHEAST...AND MAKES WAY FOR THE UPSTREAM SYSTEM TO ENTER OUR REGION. THE PAST FEW DAYS...GUIDANCE HAS TRANSITIONED THIS SYSTEM FROM A SLOWER...MORE AMPLIFIED SYSTEM INTO ONE THAT IS MORE PROGRESSIVE AND THE BULK OF ITS ENERGY REMAINS NORTH OF THE REGION AS IT MOVES EASTWARD. THAT TREND CONTINUES TODAY. OUR FORECAST WILL REFLECT LITTLE CHANGE FROM THE PRIOR DURING THE THURSDAY THROUGH FRIDAY TIMEFRAME. THE HIGHLIGHTS HERE ARE UPSLOPE RAIN/SNOW SHOWERS ACROSS SOUTHEAST WEST VIRGINIA AND NEIGHBORING COUNTIES OF SOUTHWEST VIRGINIA. A DECENT NORTHWEST FLOW WILL HELP CLOUDS TO A MINIMUM EAST OF THE CREST OF THE BLUE RIDGE AND ADD A TOUCH OF A WARMING INFLUENCE. PARTLY TO MOSTLY CLOUDY SKIES AND COOLER TEMPERATURES WILL BE THE RULE FOR THE MOUNTAINS. SATURDAY INTO SUNDAY THE REGION TRANSITIONS INTO MORE OF A ZONAL PATTERN. THERE IS CONSISTENCY IN EACH MODEL CONCERNING THAT FEATURE. WHAT VARIES SIGNIFICANTLY IS THE TIMING...TRACK AND SPEED OF A DISTURBANCE MOVING WITHIN THIS ZONAL FLOW THAT MAY OR MAY NOT IMPACT OUR REGION. AT THIS TIME...HAVE PLACED THE GREATEST FORECAST WEIGHT ON A MODEL CONSENSUS THAT OFFERS A SMALL CHANCE OF LIGHT RAIN/SNOW MAINLY IN THE WESTERN PARTS OF THE AREA SATURDAY NIGHT INTO EARLY SUNDAY WITH TEMPERATURES TRENDING MILDER OVER THE WEEKEND. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... AS OF 1150 PM EST SUNDAY... RAIN HAS MOVED OUT OF THE REGION WITH SPOTTY DRIZZLE AND ISOLATED SHOWERS REMAINING INTO EARLY MORNING. OVERALL LOOKING AT MVFR/IFR CIGS WITH LOW LVL WIND SHEAR EARLY ON...THEN LLJ SHIFTS OUT BY DAWN WITH CIGS STARTING TO LIFT THROUGH LATE MONDAY MORNING AS THE SFC FLOW TURNS SSW TO SW. GUSTY WINDS AND VFR CIGS SHOULD OCCUR MOST OF THE DAY MONDAY...WITH WINDS STARTING TO WIND DOWN LATER IN THE DAY. WITH FRONTAL BOUNDARY MOVING IN CIGS SHOULD BE STAYING HOVERING NEAR MVFR/VFR HEIGHTS WITH CONFIDENCE LOW AS MODELS VARY ON DEPTH OF MOISTURE INTO MONDAY EVENING. EXTENDED DISCUSSION... WINDS WILL STAY GUSTY MONDAY NIGHT BEHIND COLD FRONT....WITH POTENTIAL FOR SUB VFR CIGS IN THE MTNS...WHILE VFR IS EXPECTED TO THE EAST. ANOTHER STORM SYSTEM IS EXPECTED TO MOVE UP THE SOUTHEAST COAST BY EARLY WEDNESDAY WHICH MAY BRING WINTRY PRECIP TO THE AREA ALONG WITH SUB VFR AT ALL SITES. LOOKS LIKE FLIGHTS WILL BE IMPACTED GREATLY ACROSS THE MID ATLANTIC INTO THE NORTHEAST WITH THIS SYSTEM WITH STRONG WINDS EXPECTED ALONG WITH WIDESPREAD PRECIPITATION. AROUND HERE LOOKS LIKE WE WILL EXPERIENCE SUB VFR AT LEAST WED INTO EARLY THANKSGIVING BEFORE HIGH PRESSURE WORKS IN FROM THE WEST...THOUGH WINDS MAY STAY UP THROUGH THU NIGHT...WITH UPSLOPE LOWER CIGS AT BLF/LWB. && .CLIMATE... RECORD HIGH TEMPERATURES FOR 11/24... ROANOKE.....77 (1973) LYNCHBURG...79 (1973) DANVILLE....75 (1979) BLACKSUBRG..69 (1998) BLUEFIELD...72 (1973) LEWISBURG...72 (1973) && .EQUIPMENT... AS OF 330 AM EST MONDAY... THE VISIBILITY SENSOR AT KLYH...LYNCHBURG AIRPORT...WILL BE OUT OF SERVICE UNTIL PARTS ARRIVE TO REPLACE THE SENSOR. UNTIL THEN THE VISIBILITY WILL ONLY BE REPORTED WHEN THE CONTROL TOWER IS STAFFED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/KK/MBS/WP NEAR TERM...JH SHORT TERM...AMS LONG TERM...DS AVIATION...KK/WP CLIMATE...JH EQUIPMENT...JH

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