Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 232350 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 750 PM EDT THU APR 23 2015 .SYNOPSIS... HIGH PRESSURE ENTERS THE OHIO VALLEY THIS EVENING ALLOWING WINDS TO WEAKEN OVERNIGHT...WITH FREEZING TEMPERATURES EXPECTED FOR THE MOUNTAINS BY FRIDAY MORNING. LOW PRESSURE WILL TRACK FROM THE SOUTHERN AND CENTRAL PLAINS EAST TO OVER THE REGION BY SATURDAY MAKING FOR A WET WEEKEND. && .NEAR TERM /THROUGH FRIDAY/... AS OF 300 PM EDT THURSDAY... HIGH PRESSURE IN THE MID WEST AND A TROUGH ALONG THE MID ATLANTIC COAST CREATED A TIGHT PRESSURE GRADIENT OVER THE AREA TODAY. THIS PRESSURE GRADIENT CREATED WINDY AND GUSTY CONDITIONS OVER THE REGION. HIGH PRESSURE TRACKS TO THE SOUTHERN OHIO VALLEY THIS EVENING...ALLOWING WINDS TO CALM DOWN SOME OVERNIGHT. A SUBSIDENCE INVERSION DEVELOPS AND LOWERS ACROSS THE AREA OVERNIGHT...KEEPING THE STRONGER WINDS ALOFT. SURFACE WINDS WILL NOT COMPLETELY DECOUPLE AND RADIATIONAL COOLING CONDITIONS ARE NOT IDEAL TO PRODUCE WIDESPREAD FROST EAST OF THE BLUE RIDGE...DESPITE TEMPERATURES DROPPING INTO THE LOWER TO MID 30S. ALSO...SINCE AFTERNOON DEW POINTS ARE DOWN IN THE 10F-20F RANGE...ENOUGH MOISTURE TO FORM PATCHY FROST IS HIGHLY UNLIKELY. WITH THIS IN MIND...NO FROST ADVISORY WILL BE POSTED FOR COUNTIES EAST OF THE BLUE RIDGE. TEMPERATURES ACROSS THE MOUNTAINS ARE EXPECTED TO DROP BELOW FREEZING...UPPER 20S TO LOWER 30S. AGAIN...LACK OF MOISTURE AND MIXING WILL DETER FROST FROM FORMING...HOWEVER FREEZING TEMPERATURES CAN HURT SENSITIVE VEGETATION. IT IS ADVISED TO PROTECT SENSITIVE VEGETATION BY MOVING IT TO A SHELTERED AREA IF POSSIBLE...OR PERHAPS BY PLACING A PROTECTIVE COVER OVER THE VEGETATION. SUBSIDENCE INVERSION SHOULD BREAK BY 9AM ALLOWING WINDS TO INCREASE TO 10-20 MPH. ALSO BY 9AM...TEMPERATURES WILL HAVE WARMED ABOVE FREEZING. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... AS OF 300 PM EDT THURSDAY... EXPECT TO SEE INCREASING CLOUDS SWINGING ACROSS THE AREA FRIDAY NIGHT AHEAD OF A WARM FRONT STRETCHING FROM MO/KS ESE INTO THE SOUTHERN APPALACHIANS. SFC HIGH WILL BE MOVING FROM THE ERN GREAT LAKES SOUTH TO OFF THE SC COAST FRIDAY EVENING...TO PA TO SE NC BY SAT MORNING. MAY START TO SEE SOME LIGHT RAIN MOVING INTO THE MTNS AFTER MIDNIGHT WITH GREATER PUSH INTO THE AREA SATURDAY MORNING. BEST LIFT ARRIVES IN THE MORNING WITH A SECONDARY MAXIMUM OF LIFT SHIFTING INTO THE MTNS SAT EVENING. WILL SEE LIKELY TO CATEGORICAL POPS SATURDAY WITH OFF AND ON RAIN. INSTABILITY WILL STAY LIMITED SOUTHWEST OF US BUT COULD PUSH INTO THE MTNS OF WV/FAR SW VA AND NW NC TOWARD THE AFTERNOON...SO ADDED SCT THUNDER PER DAY 3 SPC OUTLOOK. THIS LOW WILL BE GAINING STRENGTH AS IT SHIFTS EAST TO THE OHIO VALLEY SATURDAY EVENING...THEN MAINTAINING ITSELF AS IT HEADS OVER AND EAST OF OUR AREA SAT NIGHT/EARLY SUNDAY. WILL SEE SOME DRY SLOTTING AS THIS LOW EDGES IN WITH MAIN BULK OF RAIN AFFECTING THE NRN CWA SAT NIGHT...THOUGH CANNOT RULE OUT ANYWHERE STAYING COMPLETELY DRY. THE MODELS ARE HANDLING THIS SOMEWHAT SIMILAR IN TAKING A SECONDARY SFC LOW ACROSS THE CAROLINAS SUNDAY AS ANOTHER SHORTWAVE SWINGS BY...AND THINK SUNDAY WILL STAY ON THE DAMP SIDE...BUT SATURDAY LOOKS WETTER AT THIS POINT. BY SUNDAY NIGHT...AXIS OF TROUGH SHIFTS EAST AS WE GET A NORTHERLY FLOW FEEDING DRIER AIR IN. WITH UPPER TROUGH AND RAIN TEMPS THIS PERIOD SHOULD STAY BELOW NORMAL...ESPECIALLY DURING THE DAY SATURDAY...WITH HIGHS RANGING FROM THE UPPER 40S HIGHLANDS...TO LOWER TO MID 50S SOUTH...AND POSSIBLY AROUND 60 SW VA OUTSIDE THE MODEST WEDGE...WITH POSSIBLE BREAKS IN THE OVC. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 230 PM EDT THURSDAY... MODELS MAKING A SHIFT TO OUR SOUTH WITH THE NEXT WEATHER MAKE FOR MID WEEK. STILL WILL NOT COMPLETELY GO DRY AS THIS IS ONE RUN...AND WILL HAVE TO WAIT AS THE PACIFIC ENERGY PUSHES THE SYSTEM ONSHORE OUT WEST TO SEE IF THIS SETS UP FURTHER SOUTH THAN PREVIOUSLY FORECASTED. SPLIT FLOW WILL ALSO KEEP CONFIDENCE IN FORECAST BEYOND THE SHORT TERM LOW. WILL ALLOW FOR DRY WEATHER MONDAY INTO TUESDAY WITH INCREASING CLOUDS TUESDAY THEN CHANCE OF RAIN TUESDAY NIGHT THROUGH THURSDAY. STILL OVERALL LOOKING COOLER THAN NORMAL THROUGH THE EXTENDED. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 800 PM EDT FRIDAY... SURFACE HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT...WITH VERY DRY AIR ASSOCIATED WITH THE AIRMASS SUPPORTING VFR CONDITIONS THROUGH THE TAF PERIOD. THE PRESSURE GRADIENT FOR THE FORECAST AREA WILL REMAIN TIGHT. THIS WILL MAINTAIN GUSTY RIDGETOP WINDS IN SPITE OF WINDS DECOUPLING IN THE VALLEYS. SUSTAIN WINDS SHOULD DROP BELOW 10KTS OVERNIGHT AS HIGH PRESSURE TRACKS EAST OVER THE AREA AND A SUBSIDENCE INVERSION DEVELOPS KEEPING HIGHER WINDS ALOFT. THE HIGH PRESSURE CENTER DOES NOT PASS DIRECTLY OVER THE AREA...THEREFORE ONCE THE INVERSION BREAKS FRIDAY MORNING (AROUND 14Z)...THE WINDS WILL INCREASE TO 10-15KTS WITH A FEW GUSTS IN THE 18-22KT RANGE. DRY AIR ASSOCIATED WITH THE HIGH WILL ALLOW FOR CONTINUED VFR CONDITIONS. HIGH CONFIDENCE IN VFR CIGS/VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD AND HIGH CONFIDENCE IN WIND DIR THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... OVERRUNNING CLOUDS WILL BUILD INTO THE AREA FRIDAY NIGHT AHEAD OF A WARM FRONT THAT WILL BE APPROACHING FROM THE SOUTHWEST. BY SATURDAY...MOISTURE APPEARS DEEP ENOUGH TO ALLOW FOR PERIODS OF RAIN AND MVFR...WITH BEST FORCING ACROSS THE CAROLINAS. COMPLEX LOW PRESSURE TO THE WEST WILL THEN PUSH THROUGH THE REGION SATURDAY NIGHT INTO SUNDAY...BEFORE EXITING OFFSHORE SUNDAY NIGHT. THIS WILL LIKELY KEEP SUB-VFR CONDITIONS IN LOW CLOUDS AND LINGERING RAINFALL INTO SUNDAY NIGHT. FLYING CONDITIONS SHOULD START TO IMPROVE SOME BY MONDAY AS THE LOW PULLS FARTHER OFFSHORE AND WEAK HIGH PRESSURE BUILDS IN FROM THE NORTHWEST. HOWEVER CONTINUED CYCLONIC FLOW LIKELY TO KEEP MORE MVFR CIGS OVER THE MOUNTAINS WITH IMPROVEMENT TO VFR ACROSS THE EAST ON MONDAY. && .EQUIPMENT... AS OF 330 PM EDT THURSDAY... SEVERAL EQUIPMENT ISSUES TO REPORT. THE WYTHEVILLE NOAA WEATHER RADIO BROADCAST WILL BE UNAVAILABLE INTO FRIDAY. A TECHNICIAN WILL BE OUT THERE TOMORROW TO WORK ON IT. THE DEWPOINT AT RICHLANDS VA IN TAZEWELL COUNTY VIRGINIA IS REPORTING ERRONEOUS DEWPOINTS...SO IGNORE. THE TEMPERATURES AND DEWPOINTS REPORTED FROM THE VIRGINIA TECH AIRPORT WILL BE INTERMITTENT. THE FAA HAS BEEN NOTIFIED ABOUT THIS PROBLEM. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR VAZ007-009>020-022>024. NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR NCZ001-002-018. WV...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR WVZ042>044-507-508. && $$ SYNOPSIS...NF/WP NEAR TERM...RCS SHORT TERM...WP LONG TERM...WP AVIATION...PM EQUIPMENT...WP

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