549  
FXUS61 KRNK 280215  
AFDRNK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BLACKSBURG VA  
1015 PM EDT WED OCT 27 2021  
   
SYNOPSIS
 
 
AN UPPER TROUGH LOCATED ACROSS THE MIDSOUTH WILL DEEPEN AND MOVE  
SLOWLY INTO THE SOUTHERN APPALACHIANS BY FRIDAY THEN LINGER  
THROUGH THE WEEKEND. WIDESPREAD RAINFALL, SOME HEAVY, IS  
EXPECTED ACROSS THE REGION BEGINNING THURSDAY AFTERNOON THROUGH  
FRIDAY WITH SCATTERED SHOWERS CONTINUING THROUGH MUCH OF THE  
WEEKEND. HIGH PRESSURE WILL FINALLY RETURN TO THE AREA EARLY  
NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH THURSDAY/
 
 
AS OF 1015 PM EDT THURSDAY...  
 
...INCREASING CLOUDS AND STEADY TEMPERATURES OVERNIGHT GIVE WAY TO  
RAIN THURSDAY AFTERNOON...  
 
THE CALM BEFORE OUR NEXT LOW PRESSURE SYSTEM THIS EVENING WITH  
QUIET WEATHER HEADING INTO THE OVERNIGHT PERIOD. NO REAL CHANGES  
TO THE CURRENT FORECAST PACKAGE WITH JUST SOME MINOR  
ADJUSTMENTS TO LOWS TONIGHT DUE LARGELY IN PART TO HIGH CLOUD  
COVERAGE MOVING INTO THE REGION. CLOUD COVERAGE WILL CONTINUE TO  
THICKEN HEADING INTO THURSDAY MORNING AS LOW PRESSURE  
APPROACHES FROM THE MID-SOUTH. PWATS PER THE 00Z RNK SOUNDING  
THIS EVENING WERE AT 0.63" WHICH IS A SLOW CLIMB FROM THIS  
MORNING'S 12Z SOUNDING WHICH STARTED AT 0.45".  
 
MOISTURE WILL STEADILY INCREASE FROM THE SOUTH AND EAST AS HIGH  
PRESSURE DEPARTS OFF THE COAST THURSDAY AFTERNOON. WITH THAT SAID,  
MOST LOCATIONS SHOULD REMAIN DRY FOR THE FRONT HALF OF THE DAY WITH  
EVEN A FEW BREAKS OF SUNSHINE OUT EAST THURSDAY MORNING INTO EARLY  
THURSDAY AFTERNOON.  
 
CAM GUIDANCE CONTINUES TO DEPICT AN ARCING BAND OF RAIN MOVING INTO  
THE AREA FROM OUR SOUTHWEST BEFORE THE AFTERNOON COMMUTE HOME WITH  
WIDESPREAD MODERATE TO HEAVY RAIN BUILDING IN FOR THE EVENING AND  
OVERNIGHT HOURS. RAIN AMOUNTS WILL BE ON THE LOWER SIDE TO START  
WITH A HALF INCH TO THREE QUARTER OF AN INCH AMOUNTS ACROSS THE  
WESTERN NORTH CAROLINA MOUNTAINS TO A TRACE AT BEST TOWARD THE  
SOUTHERN SHENANDOAH VALLEY.  
 
WINDS WILL ALSO BE AN ISSUE BY LATE THURSDAY MORNING INTO  
THURSDAY AFTERNOON ESPECIALLY ALONG THE WESTERN FACING SLOPES.  
GUSTS IN THESE LOCATIONS WILL BE UPWARDS OF 25-35 MPH WITH  
LOCALLY HIGHER GUSTS ALONG THE RIDGES AS THE PRESSURE GRADIENT  
TIGHTENS. FURTHER EAST EXPECTED GUSTS UPWARDS OF 15 TO 25 MPH AT  
TIMES AS THE WINDS PUSH IN FROM THE SOUTHEAST.  
 
YOU COMBINE THE WINDS WITH AIR TEMPERATURES RANGING FROM THE MID TO  
UPPER 50S WEST OF THE BLUE RIDGE AND LOW 60S OVER THE PIEDMONT  
TO GET A SWEATER WEATHER THURSDAY AHEAD.  
 
PREVIOUS DISCUSSION...  
 
CLOUDS MOVE IN LATE TONIGHT, THEN RAIN BY THURSDAY AFTERNOON.  
 
BENIGN WEATHER IS EXPECTED ACROSS THE REGION TONIGHT AND THE  
FIRST PART OF THE DAY THURSDAY. WINDS HAVE BECOME LIGHT AND TO  
CALM AS THE PRESSURE GRADIENT RELAXES AND HIGH PRESSURE  
APPROACHES FROM THE OHIO VALLEY.  
 
WARM ADVECTION CLOUDS BEGIN TO ADVANCE NORTHEAST INTO THE AREA  
BEFORE DAYBREAK. EXPECT LOCATIONS SUCH AS BURKES GARDEN,  
LEWISBURG, MARTINSVILLE, AND BLACKSBURG TO FALL INTO THE UPPER  
30S BEFORE MORNING, WITH MOSTLY 40S ELSEWHERE. BECAUSE OF  
INCREASING CLOUD COVER LATE, MINIMUM TEMPERATURES MAY WELL OCCUR  
CLOSER TO MIDNIGHT THAN DAYBREAK. WINDS WILL VEER TO THE  
NORTHEAST BY MIDNIGHT IN MOST AREAS INCREASING IN SPEED TO  
AROUND 10 MPH BY DAYBREAK.  
 
FOR THURSDAY, THE DAY WILL START WITH CLOUDY SKIES WEST AND  
INCREASING CLOUDS EAST, WITH MOST AREAS OVERCAST BY MID TO LATE  
MORNING. THE CLOUDS WILL CONSIDERABLY INHIBIT NORMAL DAYTIME  
WARMING WITH TEMPERATURES STRUGGLING TO RISE INTO THE 40S AND  
50S THROUGH THE DAY. HAVE TAILORED MAX TEMPERATURES FOR THURSDAY  
BELOW GUIDANCE AND MORE ON THE ORDER OF THE 10% NBM GUIDANCE,  
WITH SOME TWEAKS UPWARD A BIT IN THE EAST WHERE SOME MORNING  
SUNSHINE/WARMING POSSIBLE.  
 
THE FIRST WAVE OF PRECIPITATION WILL ARRIVE EARLY AFTERNOON IN  
AN ARC FROM NORTHWEST TO SOUTHEAST. THE AIR MASS WILL INITIALLY  
BE RATHER DRY, SO THINKING MUCH OF THIS INITIAL ROUND OF  
PRECIPITATION MAY SIMPLY SERVE TO SATURATE THE AIR MASS AND  
LOWER THE TEMPERATURES CLOSER TO THE DEWPOINT. A MORE  
SIGNIFICANT ROUND OF PRECIPITATION WITH POTENTIALLY MODERATE TO  
HEAVY RAINFALL WILL ARRIVE TOWARD 00Z. RAINFALL THROUGH 00Z  
THURSDAY SHOULD RANGE FROM 1/2 INCH WESTERN NC MOUNTAIN TO TRACE  
AMOUNTS AT BEST TOWARD LEXINGTON AND LYNCHBURG.  
 

 
   
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/
 
 
AS OF 235 PM EDT WEDNESDAY...  
 
CONFIDENCE IS HIGH FOR A WET AND UNSETTLED END TO THIS WEEK.  
 
A DEEP CLOSED UPPER LEVEL LOW WILL SLOWLY WOBBLE EASTWARD TOWARD THE  
APPALACHIAN MOUNTAINS DURING THURSDAY NIGHT AND FRIDAY. AS A RESULT,  
RAIN SHOULD SPREAD THROUGHOUT THE MID ATLANTIC DURING THIS TIME.  
SOME HEAVY DOWNPOURS ARE POSSIBLE WITH UP TO THREE INCHES OF RAIN  
ALONG THE BLUE RIDGE, AND MODEL SOUNDINGS HINT THAT THERE COULD BE  
ELEVATED INSTABILITY THAT MAY SPARK AN ISOLATED RUMBLE OF THUNDER IN  
THE PIEDMONT. ANTECEDENT CONDITIONS ARE ACTUALLY RATHER DRY, SO ANY  
HYDRO THREAT WOULD BE DUE TO HEAVY RAIN RATES TRAINING OVER THE SAME  
LOCATIONS. THEREFORE, NO FLOOD WATCH IS BEING CONSIDERED AT THIS  
POINT, BUT IT WILL STILL BE MONITORED IN CASE FUTURE MODEL RUNS  
INCREASE THE QPF.  
 
THE CLOSED LOW SHOULD GRADUALLY TURN TOWARD THE NORTHEAST BY  
SATURDAY. ALTHOUGH THE PIEDMONT MAY START TO SEE SOME CLEARING,  
UPSLOPE CLOUDS AND SHOWERS SHOULD CONTINUE ALONG AND WEST OF THE  
BLUE RIDGE THROUGH THE DAY. IT WILL TAKE UNTIL SATURDAY NIGHT WHEN  
THE CLOSED LOW FINALLY BEGINS TO EXIT SO THAT HIGH PRESSURE CAN  
START TO BUILD FROM THE WEST. WINDS COULD BEGIN TO INCREASE FROM THE  
WEST TO NORTHWEST JUST BEFORE SUNRISE, WHILE CLOUDS AND MOISTURE  
LINGER ACROSS SOUTHEAST WEST VIRGINIA.  
 

 
   
LONG TERM /SUNDAY THROUGH WEDNESDAY/
 
 
AS OF 235 PM EDT WEDNESDAY...  
 
CONFIDENCE IS INCREASING THAT DRIER WEATHER SHOULD ARRIVE TO  
START NEXT WEEK.  
 
HIGH PRESSURE WILL MOVE EASTWARD ON SUNDAY, BUT WINDS COULD TURN  
GUSTY FROM THE NORTHWEST DUE TO THE EXISTING PRESSURE GRADIENT  
BETWEEN THE HIGH AND A DEPARTING LOW OVER SOUTHEASTERN CANADA. THOSE  
WINDS SHOULD RELAX BY SUNDAY NIGHT, AND THE LAST OF THE UPSLOPE  
CLOUDS AND MOISTURE SHOULD VANISH ACROSS SOUTHEAST WEST VIRGINIA.  
MONDAY APPEARS DRIER AND MILDER AS THE FLOW ALOFT TURNS ZONAL. BY  
TUESDAY, A BROAD UPPER LEVEL TROUGH WILL DIVE SOUTHWARD INTO THE  
NORTHERN PLAINS AND SPARK A LOW PRESSURE SYSTEM THAT COULD REACH THE  
MID ATLANTIC BY LATE TUESDAY INTO WEDNESDAY. THE MODELS ARE  
STRUGGLING WITH THE TIMING OF THIS FRONTAL BOUNDARY, SO CHANCES OF  
SHOWERS WERE KEPT LOW UNTIL BETTER CONFIDENCE CAN BE OBTAINED.  
 

 
   
AVIATION /02Z THURSDAY THROUGH MONDAY/
 
 
AS OF 820 PM EDT WEDNESDAY...  
 
CLOUDS WILL SPREAD INTO THE SOUTHWEST VIRGINIA, NORTHWEST NORTH  
CAROLINA AND SOUTHEAST WEST VIRGINIA FROM THE SOUTHWEST LATE  
TONIGHT WITH CEILINGS LOWERING BY THURSDAY MORNING. CEILINGS  
DROP TO MVFR THURSDAY MORNING, AT KROA, KBCB, KLWB AND KBLF  
AROUND 12Z/8AM BUT NOT AT KLYH AND KDAN UNTIL AFTER 14Z/10AM.  
THIS IS SLIGHTLY SLOWER THAN PREVIOUS FORECAST BASED ON CURRENT  
GLAMP AND NBM GUIDANCE.  
 
RAIN WILL ARRIVE IN THE AFTERNOON WITH MVFR VISIBILITY. AS  
CEILINGS CONTINUE TO LOWER, FOG WILL DEVELOP AT HIGHER  
ELEVATIONS AND BY THE 00Z FRIDAY END OF THE TAF FORECAST PERIOD  
THE RIDGES ALONG THE BLUE RIDGE WILL BE IN THE CLOUDS.  
 
AS LOW PRESSURE TRACKS FROM THE CENTRAL UNITED STATES TO THE MID  
ATLANTIC REGION ON THURSDAY WINDS TURN TO THE NORTHEAST TONIGHT  
THEN SOUTHEAST ON THURSDAY WITH INCREASING WIND SPEEDS. WIND  
GUSTS OF 15 TO 30 KNOTS ARE LIKELY ON THURSDAY, ESPECIALLY FROM  
WEST OF KLWB TO KBLF TO WEST OF KTNB.  
 
 
ABOVE AVERAGE CONFIDENCE FOR TIMING OF RAIN AND CEILINGS  
LOWERING TO MVFR THEN IFR.  
ABOVE AVERAGE CONFIDENCE FOR WIND AND VISIBILITY.  
 
EXTENDED AVIATION DISCUSSION...  
 
VERY POOR AVIATION CONDITIONS ARE EXPECTED FRIDAY THROUGH  
SATURDAY LOOK FOR IFR-LIFR CEILINGS AND VISIBILITIES IN RAIN,  
SOME HEAVY, AND FOG. ISOLATED THUNDERSTORMS POSSIBLE FRIDAY  
ACROSS THE PIEDMONT. GRADUAL IMPROVEMENT BACK TO VFR IS EXPECTED  
EAST OF THE BLUE RIDGE SUNDAY. LINGERING MVFR CLOUDS AND  
SCATTERED SHOWERS ARE EXPECTED TO PERSIST IN THE MOUNTAIN  
THROUGH SUNDAY. VFR CEILINGS AND VISIBILITIES WILL RETURN TO THE  
MOUNTAINS ON MONDAY.  
 

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

 
 

 
SYNOPSIS...RAB  
NEAR TERM...AMS/ET  
SHORT TERM...PW  
LONG TERM...PW  
AVIATION...AMS/RAB  
 
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