369  
FXUS61 KRNK 152347  
AFDRNK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BLACKSBURG VA  
747 PM EDT MON JUL 15 2019  
   
SYNOPSIS
 
 
A RIDGE OF HIGH PRESSURE WILL START SHIFTING EAST TO THE COAST  
TONIGHT INTO TUESDAY, AS A LOW PRESSURE TROUGH OVER THE OHIO VALLEY  
BEGINS HEADING EASTWARD. THIS SYSTEM WILL BRING INCREASED TROPICAL  
MOISTURE ACROSS OUR AREA WEDNESDAY INTO THURSDAY. A RIDGE OF HIGH  
PRESSURE WILL AGAIN TRY TO GAIN A FOOTHOLD OVER OUR REGION FOR THE  
WEEKEND.  
 

 
   
NEAR TERM /THROUGH TUESDAY/
 
 
AS OF 747 PM EDT MONDAY...SEVERAL STRONG, WITH A FEW SEVERE  
STORMS CONTINUE TO MAINLY AFFECT THE BLUE RIDGE AS WELL AS  
ACROSS THE NORTHERN THIRD OF THE FORECAST AREA. WHILE CONVECTION  
WHICH FIRED ACROSS BATH THROUGH BUCKINGHAM COUNTIES WAS IN  
ASSOCIATION WITH A STALLED FRONTAL ZONE OVER CENTRAL VA, APPEARS  
ACTIVITY IN THE BLUE RIDGE IS BEING SPAWNED FROM REMNANT  
OUTFLOWS. WHILE AIR MASS CONTINUES TO BE MODERATELY UNSTABLE,  
ELEVATED DCAPE VALUES DRIVEN BY STRONG DAYTIME HEATING ARE  
ESPECIALLY PREVALENT ACROSS THE BLUE RIDGE AND EASTWARD INTO THE  
PIEDMONT. UNTIL THE BOUNDARY LAYER STABILIZES AFTER SUNSET, ANY  
STORMS WHICH CAN MOVE INTO THIS DCAPE-RICH ENVIRONMENT SHOULD  
PROVE CAPABLE OF GUSTY WINDS; THOSE STORMS WHICH REFORM AND MOVE  
OVER THE SAME AREAS COULD ALSO POSE A LOCALIZED HYDRO RISK AS  
WELL. RELATIVE MIN IN STORM COVERAGE IS EXPECTED INTO THE  
FOOTHILLS AND PIEDMONT/SOUTHSIDE AREAS OF VA/NC - AND MOST OF  
THESE AREAS SHOULD STAY LARGELY DRY.  
 
THERE'S SOME QUESTION HOW LONG ONGOING SHOWERS/STORMS MAY  
LINGER, ESPECIALLY IN THE WEST. WHILE STORMS SHOULD BE GENERALLY  
FIZZLING SHORTLY AFTER SUNSET, GUIDANCE IS OFFERING MIXED  
SIGNALS ON WHEN WE GO FULLY CLEAR. BOTH THE 18Z NAM AND GFS  
SUGGEST SLIGHT/LOW CHANCE POPS MAY BE WARRANTED IN THE WEST  
UNTIL MIDNIGHT, WITH THE SUBTROPICAL RIDGE AXIS SHIFTING ENOUGH  
EAST OFF THE MOUNTAINS TO FOSTER CONTINUED SPOTTY SHOWERS. DID  
SHOW POPS A LITTLE LONGER, BUT THESE MAY STILL BE UNDERDONE.  
WILL LET TRENDS AND INCOMING 00Z DATA DICTATE ANY FURTHER  
CHANGES, THOUGH DID STRETCH SOME ISOLATED SHOWERS THROUGH 03Z IN  
THE WESTERN MOUNTAINS. SHOULD SEE FOG IN THE TYPICAL RIVER  
VALLEYS OVERNIGHT, AS WELL AS NEAR AREAS WHICH RECEIVED WETTING  
RAINS.  
 
NO CHANGES MADE ATTM TO LOWS WHICH STILL LOOK ON PACE.  
 
PREVIOUS DISCUSSION FROM 245 PM MONDAY...  
 
ISOLATED TO SCATTERED SHOWERS AND STORMS WILL CONTINUE ACROSS PARTS  
OF THE AREA THROUGH THE REMAINDER OF THE AFTERNOON, AND LINGER INTO  
THE EVENING HOURS. A FEW MAY REMAIN UNTIL MIDNIGHT. THE ACTIVITY  
CONTINUES TO BE FOCUSED NEAR AN OLD FRONTAL BOUNDARY THAT HAS BEEN  
FLUCTUATING ACROSS THE REGION THE PAST COUPLE OF DAYS. IT HAS BEEN  
STUCK UNDER A SHORTWAVE RIDGE, AND HAS HAD VERY LITTLE IN THE WAY OF  
A STEERING FLOW TO MOVE IT ALONG.  
 
OVERNIGHT, WE ARE EXPECTING ANOTHER SITUATION WHERE EASTERN SECTIONS  
OF THE REGION EXPERIENCE MORE CLEAR SKIES THAN CLOUDS, BUT WITH THE  
OPPOSITE OVER THE MOUNTAINS. A RETURN OF AREAS OF LOW LEVEL CLOUD  
COVER AND SOME PATCHY RIVER/MOUNTAIN VALLEY FOG IS EXPECTED. THE  
GREATEST CONCENTRATION WILL BE IN PARTS OF THE GREENBRIER AND NEW  
RIVER BASINS. ALSO, A CHANGE FROM LAST NIGHT, SOME EASTERN SECTIONS  
THAT RECEIVE SOME RAINFALL THIS EVENING, WILL HAVE AN INCREASED  
CHANCE OF PATCHY FOG BY MORNING. AREAS ALONG AND NORTH OF THE JAMES  
RIVER BASIN LOOK THE MOST PROMISING BASED UPON THE LATEST RADAR AND  
MESO-SCALE FORECAST TRENDS.  
 
FOR TUESDAY, WE EXPECT THE TREND OF INCREASING COVERAGE OF AFTERNOON  
SHOWERS AND STORMS TO CONTINUE. THE AXIS OF THE UPPER LEVEL  
SHORTWAVE RIDGE IS EXPECTED TO SHIFT CLOSER TO THE COAST, AND AN  
UPPER LEVEL TROUGH ACROSS THE LOWER OHIO VALLEY WILL START MAKING  
HEADWAY EASTWARD. THIS TRANSITION WILL HELP WEAKEN THE CAP ALOFT,  
INCREASE DYNAMICS, AND THUS MAKE SHOWER AND STORM DEVELOPMENT A BIT  
EASIER. PLUS, THE OLD FRONTAL BOUNDARY WILL STILL BE WASHED OUT  
ACROSS THE REGION, AND THERE WILL BE LINGERING BOUNDARIES STILL  
AROUND FROM THIS EVENING'S CONVECTION FOR DAYTIME HEATING TO USE AS  
A FOCAL POINT OF INITIATION.  
 
TEMPERATURES WILL CONTINUE TO BE ON THE MILD SIDE FOR THIS TIME OF  
YEAR. LOWS TONIGHT ARE EXPECTED TO RANGE FROM THE MID TO UPPER 60S  
ACROSS THE MOUNTAINS WITH LOWER 70S ACROSS THE PIEDMONT. HIGHS ON  
TUESDAY ARE FORECAST IN THE MID TO UPPER 80S ACROSS THE MOUNTAINS  
WITH 90 TO 95 ACROSS THE PIEDMONT.  
 

 
   
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/
 
 
AS OF 330 PM EDT MONDAY...  
 
WEATHER FOR MID-WEEK WILL FEATURE REMNANTS FROM BARRY, THE CRUX  
OF THE UPPER SUPPORT PASSING TO OUR NORTH, BUT WITH AN AXIS OF  
VORTICITY TRAILING TO THE SOUTH AS THE CLOSED FEATURE BEGINS TO  
SHEAR INTO AN OPEN WAVE. INSTABILITY FROM WEDNESDAY INTO  
THURSDAY IS EXPECTED TO BE PLENTIFUL, SO ANTICIPATE SCATTERED TO  
NUMEROUS SHOWERS WITH EMBEDDED THUNDERSTORMS.  
 
MODELS SUGGEST THE MOST FAVORABLE TIME FRAME FOR MEASURABLE  
RAINFALL DIRECTLY ASSOCIATED WITH THE TROPICAL REMNANTS WILL BE  
FROM WEDNESDAY AFTERNOON THROUGH THURSDAY MORNING... THE VORT  
AXIS PASSING OVERHEAD AT THAT TIME. QPF IS FORECAST TO BE THE  
HEAVIEST FROM THE OHIO VALLEY INTO THE WESTERN SLOPES WHERE  
WESTERLY FLOW ALOFT WILL ACT TO ENHANCE THE RAINFALL, BUT AS THE  
SYSTEM CROSSES THE APPALACHIANS, PRECIP PRODUCTION IS EXPECTED  
TO GO DOWN PER WESTERLY DOWNSLOPE FLOW. ATTM OUR 1-3 DAY  
FORECAST RAIN TOTALS AVERAGE FROM ABOUT AN INCH OF QPF ON THE  
WESTERN SLOPES TO A GENERAL QUARTER OF AN INCH ACROSS THE  
PIEDMONT. TEMPERATURES ARE EXPECTED TO BE SEASONALLY WARM,  
TEMPERED TO SOME DEGREE BY THE SHOWERS AND ANTICIPATED CLOUD  
COVER. THE HIGH DEWPOINTS HOWEVER, WITH READINGS FORECAST IN THE  
70S, WILL MAINTAIN THE MUGGINESS.  
 

 
   
LONG TERM /FRIDAY THROUGH MONDAY/
 
 
AS OF 345 PM EDT MONDAY...  
 
FOR FRIDAY AND INTO THE UPCOMING WEEKEND... THE UPPER RIDGE  
STRENGTHENS WITH POTENTIAL FOR 500 MB HEIGHTS TO TEST 595 DM.  
AS SUCH, PATTERN FAVORS SOME VERY WARM TEMPERATURES FOR THE  
WEEKEND, 85H TEMPS OF +23 TO +24 DEG C, YEILDING SURFACE  
READINGS WELL INTO THE 90S EAST OF THE BLUE RIDGE. DEWPOINTS  
ARE ALSO EXPECTED TO REMAIN ELEVATED, SO HEAT INDICES MAY  
ECLIPSE 100 FOR SEVERAL DAYS IN A ROW...POTENTIALLY TESTING 105  
DEGREES BY SATURDAY. SOME RELIEF MAY COME FROM POP-UP  
AFTERNOON/EVENING SHOWERS AND THUNDERSHOWERS, BUT COVERAGE IS  
EXPECTED TO BE LIMITED PER LACK OF ANY SIGNIFICANT FORCING  
MECHANISM AND OVERALL SUBSIDENCE FROM THE UPPER LEVEL RIDGING.  
 

 
   
AVIATION /23Z MONDAY THROUGH SATURDAY/
 
 
AS OF 747 PM EDT MONDAY...  
 
SCATTERED STRONG THUNDERSTORMS WITH BRIEF SUB-HOURLY RESTRICTIONS  
AS LOW AS IFR AND GUSTY OUTFLOW WINDS WILL REMAIN POSSIBLE  
THROUGH 02Z, AT MOST TAFS EXCEPT DANVILLE. HAVE INDICATED VCTS  
AND WILL TREAT ANY THUNDERSTORM THREAT SPECIFIC TO AN AIRFIELD  
WITH TEMPOS. STORM COVERAGE SHOULD GENERALLY DIMINISH THROUGH  
MIDNIGHT, BUT A FEW SHOWERS MAY LINGER IN THE WESTERN MOUNTAINS  
THROUGH AT LEAST THAT TIMEFRAME. SHOULD ALSO SEE PATCHY IFR OR  
LOWER FOG ACROSS THE NON-ROANOKE WESTERN TERMINALS, AS WELL AS  
IN LYNCHBURG OVERNIGHT.  
 
AFTER FOG BURNS OFF, WE SHOULD AGAIN SEE CUMULUS DEEPEN INTO  
THUNDERSTORMS IN THE MOUNTAINS BY EARLY TO MID AFTERNOON, THEN  
PROGRESS EASTWARD OFF THE BLUE RIDGE INTO THE PIEDMONT TOWARD  
THE END OF THE TAF PERIOD. SOME QUESTION ON STORM COVERAGE  
TOMORROW - IF IT WILL BE MORE THAN TODAY OR LESS SO; HAVE  
MAINTAINED VCSH AT MOST TERMINALS FOR TUESDAY AFTERNOON.  
 
CONFIDENCE IN AVIATION FORECAST ELEMENTS IS MODERATE; LOWER  
CONFIDENCE ON COVERAGE OF FOG AND WHEN PRECIPITATION ENDS  
TONIGHT, AND ON STORM COVERAGE TUESDAY.  
   
EXTENDED AVIATION DISCUSSION
 
 
THE OCCURRENCE OF SUB-VFR CONDITIONS WILL INCREASE WEDNESDAY  
INTO THURSDAY AS A SHORTWAVE TROUGH APPROACHES AND THE CROSSES  
THE AREA, BRINGING ALONG WITH IT THE TROPICAL MOISTURE  
ASSOCIATED WITH THE REMNANTS OF BARRY. EXPECT AN INCREASE IN  
SHOWER AND THUNDERSTORM COVERAGE, AND SUBSEQUENT LATE  
NIGHT/EARLY MORNING STRATUS/FOG.  
 
BY FRIDAY INTO SATURDAY, A SHORTWAVE RIDGE RETURNS OVERHEAD, AND  
THIS WILL CURTAIL, BUT NOT REMOVE THE POTENTIAL FOR DIURNALLY  
BASED SHOWERS AND STORMS, WITH THE FOCUS FOR MOST ACTIVITY  
ACROSS THE MOUNTAINS. DEPENDING UPON GROUND MOISTURE FOR THE  
DAYS HEADING INTO THE WEEKEND, LATE NIGHT/EARLY MORNING FOG  
COULD AGAIN BE A POSSIBILITY.  
 
CONFIDENCE IN THE ABOVE AVIATION SCENARIO IS MODERATE.  
 

 
   
EQUIPMENT
 
 
AS OF 400 PM EDT MONDAY...  
 
THE CEILOMETER AT LWB IS HAVING PERIODIC PROBLEMS WHICH MAY  
CAUSE INTERMITTENT LOSS OF DATA.  
 

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

 
 

 
SYNOPSIS...DS  
NEAR TERM...AL/DS  
SHORT TERM...PM  
LONG TERM...PM  
AVIATION...AL/DS  
EQUIPMENT...DS  
 
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