Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 250617 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 217 AM EDT SAT APR 25 2015 .SYNOPSIS... HIGH PRESSURE SHIFTS EAST OFF THE COAST TONIGHT AS LOW PRESSURE TRACKS FROM THE CENTRAL PLAINS TONIGHT...PASSING ACROSS OUR AREA SATURDAY NIGHT. THIS SYSTEM WILL LINGER INTO SUNDAY. HIGH PRESSURE WILL ARRIVE EARLY NEXT WEEK...FOLLOWED A SOUTHERN STREAM STORM SYSTEM WHICH MAY BRING WET WEATHER MIDWEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 700 PM EDT FRIDAY... MADE ONLY MINOR ADJUSTMENTS TO EXISTING GRIDS...FORECAST APPEARS TO BE ON TRACK. PREVIOUS VALID DISCUSSION... AS OF 245 PM EDT FRIDAY... LOWS TONIGHT FROM THE MID 30S OVER THE MTN VALLEYS IN THE NORTH TO LOWER 40S SOUTH. NOT EXPECTING ANY FROST/FREEZE AS CLOUDS WILL MOVE IN AND DRY AIRMASS AT FIRST WILL NOT ALLOW ANY FROST TO FORM...AND OVERNIGHT AS THE CLOUDS ARRIVE...TEMPERATURES STEADY OUT OR COULD RISE A DEGREE OR TWO. MODELS ARE CONSISTENT BRINGING MAINLY LIGHT RAIN TO THE MOUNTAINS BY 12Z SATURDAY THE QUICKLY SHIFTING BETTER LIFT ALONG/AHEAD OF A WARM FRONT THROUGH OUR AREA BY MIDDAY SATURDAY. GOOD SW FLOW AHEAD OF THE SFC LOW OVER MISSOURI INTO THE LOWER OHIO VALLEY SATURDAY WILL KEEP RAIN GOING OFF AND ON MOST OF THE DAY. QUESTION IN THE AFTERNOON IS IN SITU WEDGE WITH DEPARTING HIGH AND INSTABILITY/WEDGE FRONT OVER THE SW CWA. SPC HAS OUR FAR SW VA/NW NC/SE WV IN MARGINAL TO SLIGHT RISK FOR SVR STORMS. THE ENERGY IS THERE...BUT THINK THE OVERRUNNING RAIN AHEAD OF THIS WILL ACT TO HOLD ANY SVR THREAT OFF. THUNDERSTORM CHANCES ARE POSSIBLE FROM BKW-BLF-MKJ-TNB AND POINTS SW BY LATE AFTERNOON. WITH WEDGE IN PLACE UNDERCUT MOS IN THE TYPICAL CAD AREAS BY 5-8 DEGREES FROM MOS. THE 00Z ECMWF MOS WAS CLOSEST TO SHOWING THIS. WITH RAIN AND WEDGE TEMPERATURES SHOULD ONLY MANAGE THE LOWER TO MID 50S FROM SE WV...SOUTHEAST TO THE BLUE RIDGE OF NC AND POINTS EAST...WHILE THE MTNS OF FAR SW VA AND ALONG THE TN/NC LINE COULD SEE LOWER 60S. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... AS OF 330 PM EDT FRIDAY... WE WILL START OFF THE PERIOD SATURDAY NIGHT WITH A WARM FRONT DRAPED ACROSS THE REGION EXTENDING FROM A LOW PRESSURE AREA OVER THE MID MISSISSIPPI VALLEY WITH WAVES RIPPLING ALONG IT. THIS WILL BRING A GOOD DOSE OF RAINFALL TO THE REGION ALONG WITH SOME EMBEDDED THUNDER ESPECIALLY WEST AND SOUTH. BELIEVE ANY SIGNIFICANT CONVECTION THAT INITIATES TO OUR WEST WILL WEAKEN SUBSTANTIALLY AS IT ENCOUNTERS COOLER AND MUCH LESS FAVORABLE CONDITIONS OVER OUR AREA. THE LOW WILL CROSS OUR AREA SUNDAY MORNING AND LEAVE US WITH JUST SOME LINGERING SHOWERS WINDING DOWN DURING THE AFTERNOON. QPF TOTALS FROM SATURDAY AND EARLY SUNDAY WILL BE SIGNIFICANT WITH MANY LOCATIONS AROUND AN OE INCH...BUT LATEST ENSEMBLE RIVER GUIDANCE DOES NOT INDICATE ANY LOCATIONS EXCEEDING FLOOD STAGE. GIVEN THE WET ANTECEDENT CONDITIONS AND EXPECTED EMBEDDED THUNDER THIS SITUATION WILL BE MONITORED CLOSELY AND FLOOD WATCHES MAY BE NEEDED IF LATER GUIDANCE COMES IN WETTER. HIGH PRESSURE WILL RIDGE IN FROM THE WEST FOR MONDAY WITH CONTINUED COOL TEMPERATURES AND SOME UPSLOPE SPRINKLES FAR WEST. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 330 PM EDT FRIDAY... UPPER PATTERN WANTS TO KEEP REBUILDING AN EASTERN TROF WHICH WILL KEEP US IN COOL CONDITIONS THROUGH MID TO LATE WEEK. LATEST GUIDANCE SEEMS TO BE CONVERGING ON A SOLUTION WHICH WAS SUGGESTED BY AN EARLIER NAEFS RUN WITH SIGNIFICANT SHORT WAVE ENERGY ENTERING THE EASTERN TROF AND DRIVING DEVELOPMENT OF A SURFACE LOW OVER THE SOUTHEAST US. THERE ARE STILL SUBSTANTIAL DISPARITIES BETWEEN THE GUIDANCE BUT OUR CHANCES OF PRECIPITATION ARE LOOKING HIGHER FOR WEDNESDAY INTO THURSDAY. FRIDAY LOOKS BREEZY AND COOL WITH A FEW UPSLOPE RAIN SHOWERS. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 215 AM EDT SATURDAY... SATELLITE IMAGERY INDICATES HIGH CLOUDS OVERSPREADING THE AREA THIS MORNING...WITH MID LEVEL CLOUDS MOVING IN FROM THE WEST. RADAR ALSO INDICATING SPOTTY SHOWERS APPROACHING FROM KENTUCKY... WHICH WILL HELP TO MOISTEN THE LOW LEVELS OF THE ATMOSPHERE AS THEY PASS ACROSS THE MOUNTAINS AFTER 2 AM. LOW LEVELS REMAIN DRY ENOUGH THIS MORNING THAT GENERALLY VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH AROUND NOON...BEFORE CEILINGS QUICKLY DROP TO LOW MVFR/IFR DURING EARLY AFTERNOON FOR MUCH OF THE FORECAST REGION. THE FIRST OF TWO MAIN WAVES OF LOW PRESSURE WILL PASS ACROSS THE CENTRAL APPALACHIANS DURING LATE MORNING THROUGH MID AFTERNOON... BRINGING WIDESPREAD BUT LIGHT RAINFALL...IN ADDITION TO THE LOW CEILINGS. ONLY CONCERN FOR THUNDER WILL BE ACROSS FAR WESTERN VIRGINIA AND THE HIGHLANDS OF NORTH CAROLINA...WHERE WEDGING IS WEAKEST AND ISOLATED ACTIVITY IS POSSIBLE. RAINFALL WILL BECOME MORE SCATTERED BY EARLY EVENING AS MORE SUBTLE DISTURBANCES PASS OVERHEAD...BUT WITH HIGH PRESSURE OFF THE COAST MAINTAINING EASTERLY UPSLOPE WINDFLOW ACROSS THE CENTRAL APPALACHIANS... BELIEVE CEILINGS WILL BE PREDOMINANTLY IFR BY LATE AFTERNOON INTO THE OVERNIGHT AREAWIDE. SECOND WAVE OF LOW PRESSURE WILL FOLLOW SIMILAR PATH AS THE FIRST...PASSING ACROSS LATE TONIGHT AND EARLY SUNDAY. EXPECT RAIN TO ONCE AGAIN BECOME WIDESPREAD AFTER MIDNIGHT...PERSISTING THROUGH THE LATE MORNING HOURS OF SUNDAY. SECOND WAVE WILL DRAG A COLD FRONT ACROSS THE AREA...RESULTING IN A NORTHWESTERLY WIND SHIFT THAT WILL LEAD TO DRYING CONDITIONS AND DECREASING CLOUDS LATE SUNDAY AFTERNOON. EXTENDED AVIATION DISCUSSION... FLYING CONDITIONS WILL CONTINUE TO IMPROVE SUNDAY EVENING AS THE LOW PULLS FARTHER OFFSHORE AND WEAK HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...WITH MOST LOCATIONS BACK TO VFR BEFORE MIDNIGHT MONDAY. BREEZY NORTHWEST FLOW IS EXPECTED FOR MONDAY AND EARLY TUESDAY WITH HIGH PRESSURE BUILDING IN FROM THE NORTHWEST...SO VFR CONTINUES. BY WEDNESDAY A SOUTHERN STREAM SYSTEM APPEARS TO MAINLY AFFECT THE GULF COAST REGION TO THE CAROLINAS...BUT COULD SEE RAIN AND/OR SUB VFR CEILINGS INTO THE DAN-BCB-BLF AREA...BUT CONFIDENCE IS LOW AT THIS TIME. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...NF/WP NEAR TERM...PC/WP SHORT TERM...MBS LONG TERM...MBS AVIATION...DS/NF

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