Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 251950 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 350 PM EDT SAT APR 25 2015 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO SHIFT OFF THE COAST TODAY AS A LOW PRESSURE SYSTEM PUSHES EAST FROM THE CENTRAL PLAINS...BRINGING RAIN TO THE CENTRAL APPALACHIANS TODAY AND TONIGHT. THE SYSTEM WILL EXIT TO THE EAST SUNDAY MORNING...WITH HIGH PRESSURE BUILDING IN FROM THE WEST DURING THE AFTERNOON. ANOTHER LOW PRESSURE SYSTEM IS EXPECTED TO AFFECT THE SOUTHEAST AND MID ATLANTIC REGION DURING THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 345 PM EDT SATURDAY... LATEST VISIBLE SATELLITE IMAGES SHOW CLEARING UPSTREAM ACROSS ERN KY AND TN. THIS IS ALLOWING TEMPS TO SURGE AND LOW LEVEL INSTABILITY IS INCREASING WITH CAPE VALUES NOW AOA 2000J/KG. THIS IS SETTING THE STAGE FOR VIGOROUS CONVECTION TO OCCUR AND MOVE IN OUR DIRECTION. COOL AND STABLE AIR ANCHORED IN A WEDGE SITUATION WILL PROHIBIT ANY STORMS FROM MOVING INTO THE REGION...THOUGH EXTREME WESTERN AND SOUTHERN AREAS MAY BE VULNERABLE IF THE EDGES OF THE WEDGE ERODE MORE THAN ANTICIPATED. THE NAM AND ITS ASSOCIATED MESO MODELS HAVE BEEN HINTING AT THIS CONVECTION FOR THE LAST FEW RUNS AND BELIEVE THIS MAY BE THE SOLUTION OF CHOICE. HIGHEST PRECIPITATION AMOUNTS WILL BE FOUND FROM THE MOUNTAIN EMPIRE REGION THROUGH NORTHWEST NORTH CAROLINA BUT WILL TEMPER QPF AMOUNTS DOWN FROM RAW MODEL OUTPUT IN ANTICIPATION OF CONVECTION WEAKENING AS IT ENCOUNTERS LESS FAVORABLE CONDITIONS. WILL HAVE TO KEEP AN EYE ON EXACTLY HOW THINGS UNFOLD TO SEE IF ANY SEVERE OR HYDRO CONCERNS WILL AFFECT EXTREME SW PORTION OF OUR AREA BUT IT CURRENTLY LOOKS LIKE WE WILL GET BY WITHOUT ANY SIGNIFICANT PROBLEMS. ALL OF THIS IS BEING DRIVEN BY A WARM FRONT DRAPED OVER THE REGION EXTENDING FROM A LOW PRESSURE SYSTEM MOVING OUT OF THE MID MISSISSIPPI VALLEY. THE LOW WILL CROSS OUR REGION TONIGHT INTO SUNDAY AND BRING AN END TO THE BULK OF THE PRECIPITATION. TEMPS SHOULD PUSH UPWARDS LATE TOMORROW IN ANTICIPATION OF SOME LATE BREAKS OF SUN BUT FOR THE MOST PART WE ARE LOOKING AT COOL AND DAMP CONDITIONS WITH TEMPS WELL BELOW NORMAL TO CLOSE OUT THE WEEKEND. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... AS OF 330 PM EDT SATURDAY... DEEP UPPER LEVEL TROUGH IS FORECAST TO REMAIN POSITIONED OVER THE WESTERN ATLANTIC THE FIRST HALF OF NEXT WEEK. THIS WILL PROMOTE COOL NORTHERLY FLOW ACROSS THE MID ATLANTIC YIELDING COOLER THAN NORMAL TEMPERATURES. A SHORT WAVE EMBEDDED WITHIN THE UPPER LOW WILL CROSS THE FORECAST AREA FROM THE NORTHWEST ON MONDAY. THIS FEATURE WILL RESULT IN MAINLY CLOUD COVER...BUT SOME INSTABILITY PER LATE APRIL SUN...CAPE OF 100-200 J/KG...MAY SPAWN A FEW SHOWERS...ESP ACROSS THE MTNS OF WV AND VA HIGHLANDS. WITH 850MB TEMPS NEAR 0C...CAN NOT TOTALLY RULE OUT A FEW FLAKES OF SNOW MIXING IN...ESPECIALLY AT ELEVATIONS ABOVE 3500 FT...BUT CERTAINLY NOTHING OF ANY CONSEQUENCE. FOR TUESDAY...THE UPPER TROUGH SHIFTS A BIT MORE OFFSHORE ALLOWING FOR LESS CLOUDS...MORE SUN AND BETTER DRYING. TEMPERATURES ALOFT WARM A FEW DEGREES WHICH SHOULD PROMOTE SLIGHTLY WARMER BOUNDARY LAYER TEMPERATURES...HIGHS TESTING 60 IN THE MOUNTAINS AND NEAR 70 IN THE PIEDMONT. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 330 PM EDT SATURDAY... AN AREA OF LOW PRESSURE WILL BE TRACKING ACROSS THE SOUTHERN PART OF THE CONUS FOR MID WEEK. MODELS HAVE BEEN IN DISAGREEMENT AS TO HOW THIS SYSTEM WILL TRACK ONCE IT REACHES OUR PART OF THE COUNTRY... SOLUTIONS RANGING FROM A WELL DEVELOPED CYCLONE TO AN OPEN WAVE. LATEST GUIDANCE SUGGESTS THE BULK OF THE UPPER LEVEL SUPPORT WILL PASS SOUTH OF OUR REGION...HOWEVER...OPPORTUNITY STILL EXISTS FOR NORTHWARD JOG OF STORM TRACK...SO WILL MAINTAIN AT LEAST A CHANCE THREAT FOR WETTING RAIN IN THE WEDNESDAY-THURSDAY TIME FRAME. IN ADDITION TO THE SOUTHERN STREAM SYSTEM...THERE IS ENERGY THAT IS FORECAST TO DIVE SOUTHEAST FROM THE GREAT LAKES PROVIDING ANOTHER OPPORTUNITY FOR COOL AIR TO INFILTRATE THE REGION FOR WEDNESDAY AND THURSDAY. RESIDENCE TIME OF THE COOL AIRMASS WILL BE DEPENDENT ON WHETHER ANY PHASING TAKES PLACE BETWEEN THE SOUTHERN/NORTHERN STREAM SHORT WAVES. IF THE ENERGY PHASES AND A FULL BLOWN CYCLONE WRAPS UP ALONG THE EAST COAST ON THURSDAY...THEN COOL NORTHERLY FLOW WILL PERSIST INTO FRIDAY AND SATURDAY. IF THE STREAMS DO NOT PHASE THEN THE WAVE WILL BE MORE PROGRESSIVE AND PASS OFF THE COAST QUICKER ALLOWING FOR CONDITIONS TO MODERATE AND DRY OUT FOR FRIDAY AND SATURDAY. FOR THIS FORECAST PACKAGE HAVE LEANED MORE TOWARD THE LESS AMPLIFIED SOLUTION CONFINING PRECIP THREAT AND COOL AIRMASS TO THE WEDNESDAY- THURSDAY PERIODS FOLLOWED BY A WARMUP FOR THE WEEKEND. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... AS OF 1215 PM EDT SATURDAY... WARM FRONT REMAINS DRAPED ACROSS THE AREA EXTENDING FROM A LOW PRESSURE SYSTEM OVER THE MID MISSISSIPPI VALLEY...WITH SHOWERS FLOWING EASTWARD ALONG THE FRONT. LOW LEVELS OF THE ATMOSPHERE HAVE BEEN SLOWER TO SATURATE THAN GUIDANCE WOULD INDICATE AND BELIEVE THIS TREND WILL CONTINUE...ESPECIALLY WITH PRECIPITATION A BIT MORE SPARSE THAN EXPECTED. HOWEVER...STILL EXPECT IFR CIGS TO BECOME ESTABLISHED ALONG WITH SOME DRIZZLE THIS EVENING AND THEN PERSIST INTO SUNDAY. GUIDANCE IS STILL LIKING THE IDEA OF DEVELOPING CONVECTIVE ACTIVITY UPSTREAM AND MOVING IT INTO THE AREA EARLY TONIGHT AND BELIEVE THIS IS A PLAUSIBLE SCENARIO WITH THE ACTIVITY WEAKENING AS IT ENCOUNTERS THE MORE STABLE AIR ENTRENCHED ACROSS THE AREA. TRACK OF EXPECTED PRECIPITATION WILL MAINLY AFFECT KBLF/KBCB/KDAN AND WILL MENTION THUNDER AT KDAN DUE TO CLOSER PROXIMITY TO UNSTABLE AIR TO THE SOUTH. THE LOW WILL BE PULLING AWAY FROM THE REGION ON SUNDAY AND THIS SHOULD ALLOW FOR A GRADUAL IMPROVEMENT LATER IN THE TAF PERIOD. DO NOT EXPECT A LOT OF WIND THROUGH THE TAF PERIOD IN E/NE FLOW. KBLF MAY SEE A LOW GUST OR TWO AND THERE WINDS WILL BECOME SWLY OVERNIGHT. THEN EXPECT A TREND TO A NORTHERLY TO NWLY COMPONENT LATER IN THE TAF PERIOD ON THE BACKSIDE OF THE DEPARTING LOW. 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...MBS NEAR TERM...MBS SHORT TERM...PM LONG TERM...PM AVIATION...MBS/RAB

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