878  
FXUS61 KRNK 181147  
AFDRNK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BLACKSBURG VA  
747 AM EDT THU APR 18 2019  
   
SYNOPSIS
 
 
A WARM FRONT LIFTS NORTH TODAY. A STRONG COLD FRONT MOVES INTO  
THE MID- ATLANTIC AND SOUTHEAST STATES FRIDAY. HIGH PRESSURE  
BUILDS BACK IN LATE IN THE WEEKEND.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 730 AM EDT THURSDAY...  
 
SCATTERED THUNDERSTORMS HAVE DEVELOPED RATHER UNEXPECTEDLY EARLY  
THIS MORNING ACROSS PARTS OF THE NEW RIVER VALLEY POSSIBLY  
ALONG THE WEAK FRONTAL BOUNDARY ANALYZED ACROSS THE AREA.  
STORMS ALREADY SHOWING SOME SIGNS OF WEAKENING AS THEY LIFT OFF  
TOWARD THE NORTHEAST. STILL EXPECTING AT LEAST PARTIAL CLEARING  
BY LATE MORNING ACROSS MOST OF THE AREA AS THE BOUNDARY DEPARTS  
AND SOUTHERLY FLOW INCREASES AHEAD OF THE DEEPENING TROUGH OVER  
THE LOWER MS VALLEY.  
 
PREVIOUS VALID DISCUSSION..  
 
AS OF 315 AM EDT THURSDAY...  
 
WARM FRONT LIFTS WELL NORTH OF THE AREA TODAY WITH SOME GUSTY  
SOUTHERLY WINDS DEVELOPING BY LATE AFTERNOON/EVENING. WINDS  
COULD NEAR ADVISORY CRITERIA IN THE FAR SOUTHWEST MAINLY AT  
HIGHER ELEVATIONS. THIS IS AHEAD OF A COMPLEX AND FAIRLY POTENT  
UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT APPROACHING FROM  
THE WEST. THIS SYSTEM HAS ALREADY PRODUCED SOME SEVERE WEATHER  
AND HEAVY RAINFALL OVER PARTS OF THE ARKLATEX AND LOWER MIDWEST  
THIS MORNING AND THE GENERAL THREAT FOR BOTH SEVERE AND HEAVY  
RAIN WILL BE SHIFTING EAST OVER THE NEXT 24 HOURS. CLOUDS WILL  
INCREASE LATE TODAY AND TOWARD EVENING WITH PRECIPITATION  
CHANCES INCREASING, FIRST IN THE SW MOUNTAINS OF NC AND FAR SW  
VA WITH CATEGORICAL POPS BY 8-12Z FRIDAY IN THAT AREA AND CHANCE  
POPS ELSEWHERE BUT THE BULK OF THE RAIN AND POSSIBLE STRONG TO  
SEVERE STORMS WILL BE AFTER 12Z FRIDAY. HIGHS MID 70S TO NEAR 80  
FAR SE TODAY AND REMAINING QUITE MILD OVERNIGHT WITH CLOUDS AND  
SOUTHERLY FLOW.  
 

 
   
SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/
 
 
AS OF 255 AM EDT THURSDAY...  
 
GENEROUS AMOUNT OF RAINFALL ANTICIPATED FRIDAY INTO FRIDAY EVENING  
PER SYNOPTIC MODELS AND WPC WITH TOTALS OF 1-2 INCHES LIKELY. THERE  
ARE 3 POSSIBLE IMPACTS TO THE AREA FRIDAY.  
 
1ST IS THE SEVERE THREAT: MODELS ALL SHOWING STRONG SHEAR  
ENVIRONMENT BUT LOW CAPE. EXPECT A LINE OF SHOWERS AND STORMS FRIDAY  
MORNING TO EXTEND FROM THE MID TN VALLEY TO NORTHERN GA. AHEAD OF  
THIS LINE, STRONG SOUTHEAST WINDS WILL PROVIDE ENOUGH ENHANCEMENT  
WITH GOOD MOISTURE TRANSPORT TO PRODUCE SHOWERS ACROSS THE SOUTHERN  
BLUE RIDGE INTO THE REST OF THE MOUNTAINS. THE LINE CONTINUES EAST  
INTO THE PIEDMONT THROUGH THE DAY. SEVERE PARAMETERS FAVOR BETTER  
CHANCES OF DAMAGING WINDS/ISOLATED TORNADOES EAST OF THE BLUE RIDGE.  
THE STORM PREDICTION CENTER HAS AN ENHANCED RISK ROUGHLY EAST OF  
LINE FROM FARMVILLE, VA TO REIDSVILLE, NC, WITH A SLIGHT RISK AS FAR  
WEST AS THE WV/VA BORDER. EVEN WITH PLENTY OF CLOUD COVER, A 50-60KT  
LOW LEVEL JET MAY MIX DOWN WITH ENHANCED SHOWERS/ISOLATED STORMS IN  
THE WEST, BUT OVERALL, NOT SEEING AS MUCH THUNDERSTORM THREAT IN THE  
MOUNTAINS GIVEN THE EARLY START OF THE RAIN.  
 
THE SECOND THREAT WILL BE HEAVY RAIN/FLOODING. PWATS WILL RUN 1.5 TO  
1.75 INCHES WITH DEEP SOUTHERLY FLOW, AND POTENTIAL SLOWING OF THE  
EASTWARD PROGRESSION OF THE LINE AS UPPER FLOW PARALLELS THE SURFACE  
FRONT. WPC HAS THE SLIGHT RISK FOR EXCESSIVE RAINFALL RUNNING ACROSS  
MOST OF THE FORECAST AREA. STILL A LITTLE EARLY FOR A FLOOD/FLASH  
FLOOD WATCH, BUT MAY NEED ONE IF PROGRESSION OF FRONT IS SLOWER.  
HOWEVER, SOME CONVECTIVE ALLOWING MODELS ARE NOT SHOWING AS MUCH  
COVERAGE OVERALL COMPARED TO THE SYNOPTIC MODELS. ENSEMBLE FOR THE  
RIVERS CONTINUE TO HIGHLIGHT THREAT OF MINOR TO MODERATE FLOODING  
ALONG THE DAN AND PORTIONS OF THE ROANOKE AND JAMES, BUT STILL 30  
PERCENT CHANCE OF IT HAPPENING, WITH THE DAN THE BETTER CHANCE.  
 
THE THIRD THREAT WILL BE GRADIENT WINDS AHEAD OF THE FRONT. A 50-60  
KT 8H JET MOVES FROM THE TN VALLEY EARLY FRIDAY INTO THE MOUNTAINS  
BY 12Z FRIDAY. APPEARS HIGHER RIDGES FROM THE NC MOUNTAINS TO  
SOUTHERN WV AND THE SOUTHERN BLUE RIDGE OF VA WILL SSE GUSTS  
EXCEEDING 45 MPH AS SHOWERS MOVE IN OR JUST AHEAD OF THEM. WILL LOOK  
AT ONE MORE RUN OF THE MODELS TODAY TOO SEE IF WIND HEADLINES WILL  
BE WARRANTED, OR IF WE FIND THAT CONVECTIVE WARNINGS WITH A LINE OF  
SHOWERS WILL BE NEEDED. THE STRONGEST GRADIENT WINDS WILL BE IN THE  
09Z FRIDAY TO 18Z FRIDAY TIME FRAME.  
 
CONFIDENCE IS HIGH ON SOME THREAT OF STRONG/DAMAGING WINDS AT  
SOME POINT FRIDAY WITH AVERAGE CONFIDENCE ON FLOODING.  
 
AS WE HEAD INTO FRIDAY NIGHT AND SATURDAY THE UPPER LOW PUSHES FROM  
SOUTHERN KY NORTH INTO OHIO. WILL SEE A DRY SLOT WORK ACROSS THE  
AREA, BUT WITH SUCH A STRONG SYSTEM, ALLOWING FOR SHOWER CHANCES AT  
LEAST INTO SATURDAY. COLDER AIR ALOFT WILL BE ENOUGH TO BRING A FEW  
SNOW SHOWERS TO THE HIGHER RIDGES SATURDAY MORNING, WHERE AN INCH OR  
LESS IS POSSIBLE ON GRASSY SURFACE. ENOUGH INSTABILITY WITH THE COLD  
POOL SATURDAY AFTERNOON ALLOWS FOR ISOLATED THUNDER INTO THE  
PIEDMONT AND ESPECIALLY NORTH OF A ROANOKE TO LYNCHBURG LINE.  
 
UNTIL THE UPPER LOW HEADS EAST SUNDAY WILL NEED TO KEEP SHOWER  
CHANCES IN THE AREA THROUGH SUNDAY MORNING THEN SHOULD BE DRY MOST  
AREAS SUNDAY INTO SUNDAY NIGHT, AS HIGH PRESSURE WORKS IN FROM THE  
SOUTH.  
 
TEMPS WILL BE CLOSE TO NORMAL FOR HIGHS FRIDAY WITH LOWER TO MID 60S  
WEST, TO LOWER 70S, EAST, THEN 10 DEGREES BELOW NORMAL SATURDAY WITH  
HIGHS IN THE UPPER 40S TO LOWER 50S MOUNTAINS, TO UPPER 50S TO LOWER  
60S EAST, THEN BACK TO NORMAL SUNDAY, WITH LOWER TO MID 60S WEST TO  
AROUND 70 EAST.  
 
CONFIDENCE IS AVERAGE FOR THE FORECAST SATURDAY-SUNDAY.  
 

 
   
LONG TERM /MONDAY THROUGH WEDNESDAY/
 
 
AS OF 1230 PM EDT WEDNESDAY...  
 
MODELS IN POOR AGREEMENT WITH 500MB PATTERN MONDAY THROUGH  
WEDNESDAY. OVERALL ZONAL FLOW WITH NO SIGNIFICANT SYNOPTIC SCALE  
SYSTEMS EXPECTED DURING THIS TIME FRAME. WILL BE LEANING TOWARD  
CONTINUITY AND THE WPC SOLUTION WHICH TAKES A BLEND OF  
ENSEMBLES. COLDER AIR WITH THE UPPER LOW RETREATS NORTHEAST AND  
850MB TEMPERATURES RECOVER TO ABOVE +10 FOR MONDAY THROUGH  
WEDNESDAY. SO AFTER SUNDAY TEMPERATURES RETURN TO ABOVE NORMAL.  
 

 
   
AVIATION /12Z THURSDAY THROUGH MONDAY/
 
 
AS OF 725 AM EDT THURSDAY...  
 
AS NOTED IN THE NEAR TERM DISCUSSION, A FEW THUNDERSTORMS HAVE  
DEVELOPED ACROSS THE MOUNTAINS EARLY THIS MORNING. THE UPDATED  
12Z TAFS NOW CARRYING VCTS OR TEMPO GROUPS FOR A FEW HOURS OF  
THIS ACTIVITY AT THE WESTERN TAF SITES (ALL EXCEPT LYH AND DAN).  
STILL EXPECT IFR CONDITIONS LATER AS A WARM FRONT LIFTS NORTH  
OF THE AREA ALLOWS INCREASING SOUTHERLY FLOW OUT AHEAD OF THE  
NEXT SYSTEM APPROACHING FROM THE WEST. WINDS WILLS BE GUSTING  
OVER 20 TO 30 MPH AND POSSIBLY HIGHER OVER THE ELEVATED RIDGES.  
IN ADDITION, CLOUDS ASSOCIATED WITH THIS STRONG UPPER LOW WILL  
BE ON THE INCREASE THIS EVENING, LOWERING TO MVFR TOWARD THE END  
OF THE VALID TAF PERIOD.  
 
EXTENDED AVIATION DISCUSSION...  
 
A STRONG COLD FRONT FRIDAY TRIGGERS NUMEROUS SHOWERS AND  
THUNDERSTORMS AND SUB-VFR CONDITIONS THROUGH FRIDAY NIGHT.  
SCATTERED SHOWERS WILL CONTINUE ON SATURDAY ESPECIALLY IN THE  
MOUNTAINS. WINDS WILL BE GUSTY FROM THE WEST AND NORTHWEST  
BEHIND THIS FRONT ON SATURDAY AND SATURDAY NIGHT. VFR  
ANTICIPATED FOR SUNDAY AND MONDAY.  
 

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

 
 

 
SYNOPSIS...WP  
NEAR TERM...PC  
SHORT TERM...WP  
LONG TERM...AMS  
AVIATION...KK/PC  
 
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