721  
FXUS61 KRNK 271122  
AFDRNK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BLACKSBURG VA  
722 AM EDT MON MAR 27 2017  
   
SYNOPSIS
 
 
LOW PRESSURE MOVING OUT OF THE MISSISSIPPI VALLEY WILL KEEP WARM  
TEMPERATURES AND A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS IN  
OUR FORECAST THROUGH TUESDAY. A LARGE AREA OF HIGH PRESSURE  
WILL WEDGE DOWN THE EAST SIDE OF THE APPALACHIANS BEHIND THE LOW  
AND BRING MUCH COOLER TEMPERATURES WITH SOME DRIZZLE FOR THE  
MIDDLE OF THE WORKWEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 715 AM EDT MONDAY...  
 
MOST OF THE FORECAST DRY WITH CLOUDY SKIES, WITH MAIN BATCH OF  
SHOWERS EXITING THE SOUTHSIDE VA PIEDMONT, WITH ISOLATED  
COVERAGE IN THE ALLEGHANYS/SOUTHERN SHENANDOAH. HI-RES MODELS  
KEEP MOST OF US DRY THIS MORNING WITH MORE SHOWERS FORMING OVER  
THE SOUTHWEST MOUNTAINS AFTER MIDDAY. NUDGED POPS FOR THE  
MORNING BACK DOWN BUT NOT COMPLETELY DRY.  
 
PREVIOUS FORECAST DISCUSSION...  
 
THE BACKDOOR FRONT SITUATED FROM NEAR EKN-FVX SHOULD LIFT BACK NORTH  
AS A WARM FRONT TODAY. SHOWERS WILL BE MAINLY ISOLATED TO SCATTERED  
MAINLY THIS MORNING, WITH BEST COVERAGE IN THE PIEDMONT THRU 12Z.  
 
A LITTLE FOG AND LOWER CLOUDS OUT THERE AS WELL THIS MORNING THANKS  
TO THE SHOWERS/WET GROUND AND EAST/SOUTHEAST WIND. SHOULD SEE ANY  
FOG DISSIPATE AFTER 9AM.  
 
WILL SEE A LULL IN THE COVERAGE BETWEEN 12-18Z, THEN SHOULD START TO  
SEE UPTICK IN SHOWERS AND SOME THUNDERSTORMS AFTER 18Z AS UPPER  
SHORTWAVE AND SFC LOW MOVING TOWARD THE LOWER OHIO AND MID MS  
VALLEYS. OUR AREA WILL BE IN SOUTHWEST FLOW IN THE LOW AND MID  
LEVELS, HOWEVER, BEST LIFT STAYS ALONG AND WEST OF THE APPALACHIANS.  
THERE IS SOME BETTER LOW LEVEL CONVERGENCE CLOSER TO THE SOUTHERN  
BLUE RIDGE SO MAY SEE BETTER COVERAGE HERE THIS AFTERNOON.  
 
TEMPERATURES WILL BE AFFECTED BY CLOUD COVER, BUT JUST ENOUGH SUN  
SHOULD SEND READINGS INTO THE 70S, EXCEPT 60S IN THE HIGHER  
ELEVATIONS.  
 
TONIGHT, THE SFC LOW AND FRONT MOVE TO THE CENTRAL APPALACHIANS,  
WITH THE 00Z GFS SLIGHTLY FASTER THAN THE 00Z ECMWF, IN TERMS OF  
RAINFALL COVERAGE. THE 00Z NAM SHOWED MORE AGREEMENT TO THE GFS.  
 
BOTH OF THESE MODELS ENHANCE LIFT ACROSS THE BLUE RIDGE INTO THE  
FOOTHILLS AFTER MIDNIGHT, WITH FRONTAL CONVECTION MOVING INTO KY/WV.  
THERE IS A MINIMUM OF RAIN DEPICTED BY THESE MODELS ALONG/WEST OF  
THE BLUE RIDE INTO THE NEW RIVER VALLEY AND FAR SOUTHWEST VA. THINK  
COVERAGE IS ENOUGH FOR ANY LIGHT QPF TO HAVE HIGHER POPS TOWARD THE  
MOUNTAINS, WITH LOW LIKELYS NEAR THE SOUTHERN BLUE RIDGE FROM  
BUFFALO MOUNTAIN TO BOONE, AND IN THE FAR WESTERN AREAS FROM  
CHILHOWIE TO MCROSS WV. AM A LITTLE SKEPTICAL IN THE FAR EASTERN CWA  
AND KEPT POPS HERE IN THE 40 PERCENT RANGE.  
 
AS FAR AS ANY STRONG OR SEVERE STORMS, NOT EXPECTING ANY AS MAIN  
DYNAMICS AND ENERGY STAY WEST OF THE APPALACHIANS OVER THE OHIO/TN  
VALLEYS AND MID MS VALLEY TODAY INTO THIS EVENING.  
 

 
   
SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/
 
 
AS OF 335 AM EDT MONDAY...  
 
A SHALLOW UPPER LEVEL TROF WILL DRIVE A WEAK SURFACE LOW ALONG A  
FRONTAL BOUNDARY THROUGH THE REGION ON TUESDAY. THIS WILL BRING A GOOD  
CHANCE OF SHOWERS AND THUNDERSTORMS TO THE APPALACHIANS AND CENTRAL MID  
ATLANTIC REGION, ESPECIALLY THROUGH THE FIRST PART OF THE DAY. GUIDANCE  
INDICATES THAT THERE WILL BE ENOUGH INSTABILITY WITH MODESTLY STEEP  
MID/UPPER LEVEL LAPSE RATES TO SUPPORT SOME THUNDERSTORMS, BUT BEST  
SHEAR IS OUT OF PHASE WITH INSTABILITY AND DOES NOT ARRIVE UNTIL  
DYNAMIC FORCING IS PUSHING OFF TO THE EAST. IT IS POSSIBLE THAT THERE  
MAY BE A WINDOW FOR PARAMETERS TO COME TOGETHER TO SUPPORT DEVELOPMENT  
OF SOME STRONG STORMS MAINLY EAST OF THE BLUE RIDGE AS INDICATED BY SPC  
DAY 2 MARGINAL RISK, BUT ALL IN ALL THE SET UP IS NOT VERY IMPRESSIVE.  
 
AFTER THE FRONTAL BOUNDARY PUSHES TO OUR EAST, A LARGE AREA OF HIGH  
PRESSURE WILL MOVE OUT OF CENTRAL CANADA AND WEDGE STRONGLY DOWN THE  
EAST SIDE OF THE MOUNTAINS. THIS WILL COOL OUR TEMPERATURES DOWN  
CONSIDERABLY BUT SOME WARM READINGS WILL STILL BE FOUND ALONG THE  
WESTERN AND SOUTHERN PERIPHERY OF THE WEDGE. THERE WILL ALSO BE A LAYER  
OF SHALLOW MOISTURE IN THE WEDGE THAT LOOKS TO KEEP A GOOD AMOUNT OF  
CLOUDS AND SOME SPRINKLES/DRIZZLE AROUND WEDNESDAY AND WEDNESDAY NIGHT  
MAINLY ALONG AND JUST EAST OF THE BLUE RIDGE.  
 
BY THURSDAY THE AXIS OF THE UPPER RIDGE WILL MOVE TO OUR EAST AND ALLOW  
AN OPENING CLOSED LOW TO APPROACH FROM THE WEST. THIS WILL BRING AN  
INCREASING CHANCE OF SHOWERS TO THE REGION AS WE GO THROUGH THURSDAY  
INTO THURSDAY NIGHT.  
 
TEMPERATURES WILL START THE PERIOD WELL ABOVE NORMAL WITH LOW/MID 70S  
EAST OF THE RIDGE AND MID 60S/AROUND 70 TO THE WEST, BUT ONCE THE WEDGE  
BECOMES FULLY ESTABLISHED TEMPERATURES ON THURSDAY LOOK TO BE 10 TO 15  
DEGREES COOLER WITH MANY LOCATIONS REMAINING IN THE LOW TO MID  
50S.  
 

 
   
LONG TERM /FRIDAY THROUGH SUNDAY/
 
 
AS OF 300 PM EDT SUNDAY...  
 
ON FRIDAY, SHOWERS WILL BE LIKELY ACROSS MOST OF THE REGION WITH  
ISOLATED THUNDERSTORM POSSIBLE ACROSS THE WESTERN AND SOUTHERN PARTS  
OF THE AREA. THE MAIN SYSTEM WILL TRACK NORTH OF THE AREA FRIDAY  
NIGHT INTO SATURDAY, WITH ITS ASSOCIATED COLD FRONT ACROSS OUR  
REGION EARLY FRIDAY NIGHT. LOOK FOR AN END OF THE SHOWER ACTIVITY  
FOR MUCH OF THE AREA BY SATURDAY MORNING. LINGERING UPSLOPE SHOWERS  
ON THE BACKSIDE OF THE SYSTEM WILL BE POSSIBLE ACROSS SOUTHEAST WEST  
VIRGINIA AND NEIGHBORING COUNTIES OF SOUTHWEST VIRGINIA.  
 
SATURDAY NIGHT INTO SUNDAY, AN UPPER LEVEL RIDGE WILL BUILD OVER THE  
AREA, ALLOWING FOR A GRADUAL DECREASE IN THE UPSLOPE SHOWERS IN THE  
WEST, AND LIMITED CLOUD COVER IN THE EAST.  
 
TEMPERATURES DURING THIS PORTION OF THE FORECAST WILL BE AROUND OR  
SLIGHTLY ABOVE NORMAL FRIDAY, BUT TREND TO READINGS ABOUT TEN  
DEGREES ABOVE NORMAL FOR SATURDAY AND SUNDAY.  
 

 
   
AVIATION /11Z MONDAY THROUGH FRIDAY/
 
 
AS OF 719 AM EDT MONDAY...  
 
GETTING LOW CIGS IN ROA/LYH THANKS TO SOUTHEAST TO EAST FLOW AND  
BACKDOOR FRONT MARITIME AIR. WILL SEE THIS FRONT LIFT NORTHEAST  
THIS MORNING, SO INCREASE IN CIGS TO MVFR THEN VFR WILL OCCUR IN  
THE 15-18Z TIME FRAME. STILL SHOULD HAVE CIGS ALL DAY WITH SOME  
BREAKS IN CLOUDS FROM TIME TO TIME.  
 
SHOWERS WILL BE ISOLATED TO SCATTERED OVER THE MOUNTAINS THIS  
AFTERNOON, BUT NOT ENOUGH FOR PREDOMINANT IN THE TAFS. BETTER  
RAIN THREAT LATER TONIGHT AHEAD OF THE FRONT, WITH CIGS DROPPING  
TO MVFR TOWARD 12Z TUESDAY.  
 
EXTENDED AVIATION DISCUSSION...  
 
FRONT MOVES INTO THE MOUNTAINS AFTER 12Z TUESDAY WITH BEST  
THREAT OF SHOWERS/SOME THUNDER AND SUB-VFR IN THE 09Z-18Z  
TUESDAY TIME FRAME. COLD FRONT EXITS THE PIEDMONT BY 00Z  
WEDNESDAY WITH LINGERING SUB-VFR CIGS IN BLF/LWB WITH VFR EAST.  
 
HIGH PRESSURE BUILDS IN FROM THE NORTH WEDNESDAY INTO THURSDAY  
WITH NEXT STORM SYSTEM MOVING INTO THE MS VALLEY. A THREAT FOR  
SUB-VFR CIGS APPEARS LIKELY AS THE HIGH WEDGES SOUTHWEST WED  
NIGHT-THURSDAY FOR MOST SITES. BETTER CHANCE OF RAIN THURSDAY  
NIGHT INTO FRIDAY.  
 

 
   
RNK WATCHES/WARNINGS/ADVISORIES
 
 
VA...NONE.  
NC...NONE.  
WV...NONE.  
 

 
 

 
SYNOPSIS...MBS  
NEAR TERM...WP  
SHORT TERM...MBS  
LONG TERM...DS  
AVIATION...AL/WP  
 
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