Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 241743 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1243 PM EST MON NOV 24 2014 .SYNOPSIS...
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A WARM SOUTHWEST FLOW OF AIR WILL PREVAIL TODAY 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.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 1230 PM EST MONDAY... RAISED HIGH TEMPERATURES UP A FEW DEGREES ESPECIALLY IN THE WEST. MADE SOME ADJUSTMENTS TO CLOUD COVER WITH LATEST SATELLITE TRENDS. AS OF 955 AM EST MONDAY... POSTED A WIND ADVISORY FOR THE WESTERN HIGH ELEVATIONS AS LOW LEVEL JET PIVOTS JUST TO OUR WEST THIS AFTERNOON INTO TONIGHT. STRONG GUSTY WINDS ARE EXPECTED FOR THE HIGHER ELEVATIONS OF SOUTHEAST WEST VIRGINIA AND MOUNTAIN EMPIRE REGION. MAY NEED TO ADD COUNTIES TO ADVISORY LATER THIS AFTERNOON. ADJUSTED TEMPERATURES AND DEW POINTS FOR LATE MORNING INTO THIS AFTERNOON. A COLD FRONT WILL MOVE EAST ACROSS THE REGION THIS AFTERNOON INTO TONIGHT. THERE IS LIMITED MOISTURE WITH THIS FRONTAL BOUNDARY. MORE CHANGES LATER THIS MORNING. 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.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 430 AM EST MONDAY... DRY CONDITIONS ARE EXPECTED TO PERSIST FOR TUESDAY AS HIGH PRESSURE REMAINS IN PLACE ACROSS THE OHIO RIVER VALLEY. EXPECT TO START THE DAY WITH WINDS OUT OF THE WEST AND SUNSHINE FILTERING THROUGH HIGH CLOUDS IN THE WAKE OF A COLD FRONT THAT PASSED ACROSS THE REGION THE PREVIOUS EVENING. EXPECT ENOUGH HEATING FOR AFTERNOON HIGHS TO RANGE FROM THE UPPER 40S/LOW 50S ACROSS SOUTHEAST WEST VIRGINIA...TO AROUND 60 ACROSS PORTIONS OF THE SOUTHSIDE. CLOUD COVER WILL INCREASE DURING THE EVENING AS A DEEP LOW PRESSURE SYSTEM DEVELOPS OFF THE FLORIDA ATLANTIC COAST ALONG THE FRONTAL BOUNDARY...AND PUSHES NORTH RAPIDLY TUESDAY NIGHT. THE LOW WILL PASS MAINLY OFF THE COAST...RADIATING ATLANTIC MOISTURE WESTWARD OVER THE APPALACHIAN CHAIN TUESDAY NIGHT. AS THE LOW DEEPENS...IT WILL CAUSE WINDS TO SHIFT MORE NORTHERLY...DRAWING COLDER AIR INTO OUR AREA FROM THE GREAT LAKES. AS SUCH...WILL BE LOOKING AT THE POTENTIAL FOR ACCUMULATING SNOWS ACROSS PORTIONS OF THE MOUNTAINS BEGINNING EARLY WEDNESDAY MORNING AND LASTING THROUGH THE EVENING. THE SNOWFALL ACCUMULATION FORECAST HAS PROVEN TO BE A CHALLENGE FOR THIS SYSTEM FOR SEVERAL REASONS. FIRST...ALTHOUGH 850MB TEMPERATURES FALL BELOW FREEZING...THEY DO NOT GET MUCH COLDER THAN -2C/-3C... WHILE SURFACE TEMPERATURES HOLD AT OR ABOVE FREEZING MANY LOCATIONS THROUGH SUNRISE. TEMPERATURES WILL THEN WARM INTO THE UPPER 30S IN THE MOUNTAINS DURING THE AFTERNOON. THE LACK OF TRULY COLDER AIR WILL KEEP THE SNOW TO LIQUID RATIO ON THE LOW SIDE. THE SECOND ISSUE WILL BE THE WARM TEMPERATURES EXPECTED FOR MONDAY AND TUESDAY THAT WILL HELP WARM THE GROUND. THIS WILL HELP SNOWFALL MELT ON CONTACT INITIALLY...BEFORE IT BEGINS TO STICK...MAINLY ON GRASSY SURFACES. THIRD WILL BE HOW MUCH MOISTURE RADIATES INTO THE MOUNTAINS AS AT LEAST ONE MODEL CALLS FOR THE AXIS OF HEAVIEST PRECIPITATION TO SET UP ACROSS THE PIEDMONT...WHERE TEMPERATURES WILL REMAIN WARM ENOUGH TO SUPPORT MAINLY RAIN. AS OF THIS FORECAST...SNOWFALL ACCUMULATIONS ARE LOOKING VERY MUCH ELEVATION BASED...WITH THE MOUNTAIN VALLEY BOTTOMS PICKING UP VERY LITTLE SNOWFALL THROUGH WEDNESDAY EVENING...WHILE A FEW OF THE RIDGETOPS ABOVE 3000 FEET MAY RECEIVE 3 TO 5 INCHES. AS SUCH... SNOWFALL AMOUNTS MAY VARY SIGNIFICANTLY OVER SHORT DISTANCES. EAST OF THE BLUE RIDGE IS EXPECTED TO REMAIN WARM ENOUGH TO MAINTAIN THE PRECIPITATION AS RAIN UNTIL THE LOW PRESSURE PASSES NORTH WEDNESDAY AFTERNOON. EVEN THEN...LITTLE TO NO SNOWFALL IS EXPECTED EAST OF THE BLUE RIDGE. THERE IS STILL A SIGNIFICANT AMOUNT OF UNCERTAINTY IN THE FORECAST FOR TUESDAY NIGHT AND WEDNESDAY...AS ANY SHIFT IN THE TRACK OR TIMING OF THE LOW MAY RESULT IN CHANGES IN PRECIPITATION TYPE AND/OR AMOUNTS. AS THE LOW PRESSURE SYSTEM PASSES TOWARD NEW ENGLAND WEDNESDAY NIGHT...WE CAN THEN EXPECT AN UPPER LEVEL DISTURBANCE TO PASS ACROSS THE CENTRAL APPALACHIANS FROM THE MID MISSISSIPPI RIVER REGION... BRINGING A SHOT OF COLDER CANADIAN AIR...IN ADDITION TO UPSLOPE SNOW SHOWERS FOR THE MOUNTAINS. && .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 /18Z MONDAY THROUGH SATURDAY/...
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AS OF 1243 AM EST MONDAY... WINDS WILL HINDER AVIATION OPERATIONS THIS AFTERNOON INTO TONIGHT. STRONG GUSTY SOUTHWEST WINDS WILL CONTINUE THIS AFTERNOON INTO TONIGHT ACROSS THE HIGHER TERRAIN. WINDS MAY GUSTS TO OVER 30 KTS ESPECIALLY FROM KBLF EAST TO KROA THIS AFTERNOON. SCT TO BKN MVFR CLOUDS EXPECTED THIS AFTERNOON. WINDS SHOULD DIMINISH BY THIS EVENING AHEAD OF A COLD FRONT TO THE WEST WITH PERHAPS SOME FILLING IN OF LOWER CIGS OVER THE EAST WHERE MIXING WILL BE LESS AND AROUND KBLF/KLWB GIVEN A DEVELOPING UPSLOPE WESTERLY TRAJECTORY. THUS WILL BE LOWERING CIGS BACK TO MVFR IN SPOTS EARLY THIS EVENING BEFORE LOW LEVEL MOISTURE FADES OUT EAST BUT PERSISTS ACROSS SE WEST VA OVERNIGHT. MOST OF THE AREA SHOULD STAY IN BETWEEN DEEPER MOISTURE ON TUESDAY WITH MORE LOWER CIGS TO THE NORTHWEST AND A CANOPY WITH THE RESIDUAL FRONT TO THE SOUTHEAST. THIS LOOKS TO ALLOW MAINLY VFR CONDITIONS UNDER HIGH/MID CLOUDS WITH POSSIBLY PERIODS OF MVFR AT KBLF/KLWB. MEDIUM TO HIGH CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS DURING THE TAF PERIOD. EXTENDED DISCUSSION... 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 INTO FRIDAY.
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&& .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...WIND ADVISORY UNTIL 9 PM EST THIS EVENING FOR VAZ007-009. NC...NONE. WV...WIND ADVISORY UNTIL 9 PM EST THIS EVENING FOR WVZ042-043-508. && $$ SYNOPSIS...JH/KK/MBS/WP NEAR TERM...JH/KK SHORT TERM...AMS/NF LONG TERM...DS AVIATION...JH/KK/WP CLIMATE...JH EQUIPMENT...JH

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