Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 290001 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 701 PM EST WED JAN 28 2015 .SYNOPSIS... HIGH PRESSURE OVER THE OHIO VALLEY THIS EVENING WILL MOVE SOUTHEAST...REACHING THE CAROLINAS ON THURSDAY MORNING. LOW PRESSURE WILL TRACK FROM NEBRASKA INTO ONTARIO BY THURSDAY EVENING. THIS SYSTEM WILL PUSH A STRONG COLD FRONT THROUGH THE MID ATLANTIC REGION ON THURSDAY NIGHT. && .NEAR TERM /THROUGH THURSDAY/... AS OF 400 PM EST WEDNESDAY... UPPER TROF PASSES OVER THE REGION TONIGHT INTO THURSDAY MORNING. 850 MB TEMPERATURES MODERATE TONIGHT AND WILL BE JUST ABOVE ZERO BY THURSDAY AFTERNOON. SURFACE HIGH PRESSURE WILL PASS OVER THE REGION TONIGHT SO WINDS WILL DECOUPLE. WITH SUCH LOW SURFACE DEW POINTS AND WITH ONLY A FEW HIGH CLOUDS COMING OVER THE RIDGE TONIGHT... TEMPERATURES WILL PLUMMET THIS EVENING. WILL STAY CLOSER TO COLDER MAV GUIDANCE FOR MINIMUM TEMPERATURES...ESPECIALLY IN THE VALLEYS. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... AS OF 400 PM EST WEDNESDAY... SERIES OF SHORT WAVES SHARPENS UPPER TROF WITH A 500MB LOW CLOSING OFF OVER NEW YORK BY LATE FRIDAY. FORECAST AREA WILL BE IN FAVORABLE LEFT EXIT REGION OF UPPER JET ON THURSDAY NIGHT. FIRST SURGE OF MUCH COLDER 850 MB AIR COMES IN THURSDAY NIGHT AND IS RE-ENFORCED ON FRIDAY. ALONG WITH THE COLD AIR ADVECTION...LOW LEVEL JET COMES AROUND TO THE NORTHWEST ON THURSDAY NIGHT WITH SPEEDS OF 45 TO 55 KNOTS INTO FRIDAY NIGHT. STRONG WINDS WILL BE ALONG THE SOUTHERN APPALACHIANS THURSDAY NIGHT AND FRIDAY THEN WILL SHIFT TO THE NORTHERN APPALACHIANS ON FRIDAY NIGHT AS THE SURFACE LOW DEEPENS OFF THE COAST. NAM/GFS SHOWED PRESSURE RISES CLOSE TO 6MB/6HR FOR THURSDAY NIGHT THROUGH FRIDAY. BUFKIT AND GUIDANCE CONTINUE TO SUPPORT ADVISORY LEVEL WINDS BEHIND THE FRONT THURSDAY INTO FRIDAY EVENING. THREAT WILL REMAIN HIGHLIGHTED IN HAZARDOUS WEATHER OUTLOOK. MOISTURE INCREASES ON THURSDAY AFTERNOON FROM THE WEST. WITH THE DEEP NORTHWEST WINDS...WILL START TO SEE CLEARING EAST OF THE BLUE RIDGE ON FRIDAY MORNING. THE REMAINING LOW LEVEL MOISTURE ON THE WESTERN SLOPES ON FRIDAY WILL ERODE LATE IN THE DAY. SATURDAY SURFACE AND LOW LEVEL WINDS WILL DIMINISH AND BACK MORE TO THE WEST. HIGH CLOUDS WILL SPREAD OVER THE SOUTHERN COUNTY WARNING AREA AHEAD OF THE SOUTHERN PLAINS SYSTEM. MODELS WERE IN SIMILAR AGREEMENT WITH THE TIMING OF THE SURFACE COLD FRONT ON THURSDAY NIGHT. WILL BE TRIMMING BACK PROBABILITY OF PRECIPITATION BEFORE 18Z/1PM THURSDAY. A BULK OF THE PRECIPITATION ASSOCIATED WITH THE SYSTEM WILL BE ALONG AND WEST OF THE BLUE RIDGE BUT EVEN THAT WILL NOT BE VERY HIGH AMOUNTS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
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AS OF 330 PM EST WEDNESDAY... TEMPERATURES BELOW NORMAL THROUGH THE EXTENDED. UPPER LEVEL PATTERN FOR THE EXTENDED WILL SEE A CHANGE AS SPLIT FLOW WITH A SOMEWHAT SHALLOW EASTERN TROF BECOMES UNIFIED AS THE CLOSED LOW OVER THE BAJA PENINSULA OPENS UP AND EJECTS EASTWARD LATE IN THE PERIOD...LEAVING US WITH A WELL AMPLIFIED RIDGE AND A BROAD FLAT EASTERN TROF EXTENDING FROM A CLOSED LOW WAY UP NEAR HUDSON BAY IN CANADA. THIS SHOULD BE A FAIRLY PROGRESSIVE PATTERN WITH SURGES OF SHORT WAVE ENERGY HEADING OUR WAY ON A FAIRLY REGULAR BASIS. WE WILL START THE PERIOD UNDER HIGH PRESSURE SATURDAY NIGHT...BUT AS THE HIGH PUSHES TO OUR EAST AND WAVES RIDE ALONG AN APPROACHING COLD FRONT WE WILL SEE OUR CHANCES FOR PRECIPITATION INCREASE FOR SUNDAY AND SUNDAY NIGHT. PTYPE WILL BE WINTRY MIX AT THE START THEN EXPECT A MOSTLY RAIN EVENT...THEN BACK TO SOME UPSLOPE SNOW SHOWERS WEST OF THE BLUE RIDGE AS WE GET ON THE BACK SIDE OF THE LOW MONDAY. COLD HIGH PRESSURE THEN BUILDS AS UPSLOPE SNOW SHOWERS WIND DOWN MONDAY NIGHT AND...AFTER A VERY COLD MORNING...QUIET WEATHER SHOULD BE THE RULE FOR TUESDAY. HEADING INTO WEDNESDAY...THE REMNANTS OF THE CLOSED UPPER LOW WILL BE EJECTING TOWARD US AS THE NRN AND SRN STREAMS PHASE. LONG RANGE MODELS ARE INDICATING THE POTENTIAL FOR A /MILLER A/ TYPE LOW TO DEVELOP OVER THE GULF COAST WEDNESDAY AND TRACK THROUGH THE SOUTHEAST US AND OFF THE MIDDLE ATLANTIC COAST WEDNESDAY NIGHT. TEMPERATURES ARE CURRENTLY EXPECTED TO BE BORDERLINE AT BEST ACROSS OUR AREA FOR WINTRY WEATHER. NOTHING TO GET EXCITED ABOUT AT THIS POINT...BUT WE WILL BE WATCHING TO SEE HOW LATER MODEL RUNS HANDLE THE EVOLUTION OF THIS SYSTEM.
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&& .AVIATION /00Z THURSDAY THROUGH MONDAY/...
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AS OF 650 PM EST WEDNESDAY... HIGH PRESSURE WILL DRIFT OVER THE REGION TONIGHT. HIGH CLOUDS WILL INCREASE FROM THE WEST...MAINLY ACROSS NORTHERN PORTIONS OF THE CWA...IN ADVANCE OF AN ALBERTA CLIPPER...THE MAIN DYNAMICS OF WHICH WILL REMAIN NORTH OF OUR CWA. SCT-BKN250 IS EXPECTED AT MOST TAF SITES AFTER MIDNIGHT...KEEPING CIGS VFR. NOT EXPECTING ANY PROBLEMS WITH VISIBILITY OVERNIGHT EITHER AS THE SFC AIR MASS IS VERY DRY. DURING THE DAY THU...THE CLIPPER WILL RACE ACROSS THE GREAT LAKES INTO WESTERN NEW YORK/QUEBEC. A NARROW BAND OF PRECIPITATION ACCOMPANIES THE ASSOCIATED FRONT...MAINLY NORTH OF U.S. 460 AND WEST OF I-81. MOISTURE IS EXPECTED TO BE TOO LIMITED FOR MUCH MORE THAN CLOUDS TO THE SOUTH. PRECIPITATION WILL BE FALLING FROM MID-BASED CLOUDS...SO VISIBILITY WILL NOT BE AN ISSUE...EXPECT POSSIBLY AT BLF/LWB WHERE DYNAMICS ARE BETTER AND CLOUD CIGS COULD LOWER TO LOW END VFR OR HIGH END MVFR DURING THIS ACTIVITY...POTENTIALLY REDUCING VSBY THEN TO MVFR CATEGORY IN -SHRA. SFC/850MB TEMPS SHOULD REMAIN WARM ENOUGH FOR ALL LIQUID THROUGH THIS TAF VALID PERIOD. WINDS WILL BECOME THE MAIN CONCERN JUST AFTER THIS TAF PERIOD AS THE CLIPPER MOVES EAST OF THE REGION AND VERY STRONG NORTHWEST WINDS IMPACT AREAS WEST OF THE BLUE RIDGE. THROUGH THE TAF VALID PERIOD...HOWEVER...EXPECT CALM OR LIGHT/VARIABLE WINDS OVERNIGHT...BECOMING SOUTHEAST 5-8 KTS AROUND DAYBREAK...THEN SSE-SSW THROUGH THE DAY THU INCREASING TO 8-12KTS WITH LOW END GUSTS TO AROUND 20KTS WEST OF THE BLUE RIDGE. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD. HIGH CONFIDENCE IN VSBYS THROUGH 12Z...THEN MEDIUM TO HIGH CONFIDENCE AFT 12Z. MEDIUM TO HIGH CONFIDENCE IN WIND DIR/SPD THROUGH THE TAF VALID PERIOD. EXTENDED DISCUSSION... BEHIND THE COLD FRONT...MVFR CIGS LIKELY TO LINGER OVER THE MOUNTAINS INTO FRIDAY WITH STRONG NW WINDS ALSO PERSISTING INTO FRIDAY EVENING. GUSTS UP TO 40 KNOTS ARE POSSIBLE IN THE HIGHER ELEVATIONS. CLOUDS WILL BEGIN TO CLEAR OUT EAST OF THE BLUE RIDGE ON FRIDAY MORNING...SO KLYH AND KDAN WILL IMPROVE BACK UP TO VFR. ANOTHER AREA OF HIGH PRESSURE SHIFTS EAST INTO THE AREA SATURDAY WITH VFR EXPECTED FOR BOTH SATURDAY AND SATURDAY NIGHT. THE NEXT LOW PRESSURE SYSTEM HEADING OUT OF THE SW STATES WILL BRING A RETURN OF CLOUDS AND SOME PRECIPITATION ON SUNDAY AND MONDAY WITH WIDESPREAD MVFR TO IFR LIKELY.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...AMS LONG TERM...MBS AVIATION...AMS/RAB

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