652  
FXUS61 KRNK 180233  
AFDRNK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BLACKSBURG VA  
933 PM EST SUN FEB 17 2019  
   
SYNOPSIS
 
 
AN AREA OF LOW PRESSURE WILL PROGRESS INTO AND ACROSS THE AREA  
TONIGHT WITH ITS ASSOCIATED FRONTAL BOUNDARY CROSSING THE CAROLINAS.  
AFTER A BRIEF BREAK IN TEH WET WEATHER MONDAY NIGHT INTO EARLY  
TUESDAY, THE FORECAST TURNS VERY SOGGY FOR THE REMAINDER OF THE WEEK.  
TUESDAY NIGHT INTO WEDNESDAY, ENOUGH COLDER AIR WILL BE OVER THE  
REGION FOR THE STRONG POTENTIAL FOR A SIGNIFICANT WINTER EVENT.  
 

 
   
NEAR TERM /THROUGH MONDAY/
 
 
AS OF 930 PM EST SUNDAY...  
 
LOW PRESSURE WAS HEADING EASTWARD THROUGH CENTRAL KENTUCKY,  
ASSOCIATED WITH A LARGE SWATH OF RAIN ACROSS THE MID-ATLANTIC.  
RAIN IS EXPECT FOR MUCH OF THE OVERNIGHT UNTIL THE LOW CLEARS  
THE AREA EARLY MONDAY MORNING. IN ADVANCE OF THE LOW, A WEDGE OF  
HIGH PRESSURE ON THE EAST SIDE OF THE APPALACHIANS WAS  
MAINTAINING A COLD AIRMASS NEAR THE SURFACE. THIS WAS PRIMARILY  
RESULTING IN A COLD RAIN WITH SOME ICING NEAR THE BLUE RIDGE  
PARKWAY AND ACROSS THE HIGHLANDS OF VA/WV. AT 9PM, TEMPERATURES  
WERE STILL FLIRTING WITH 32 DEGREES IN SOME OF THESE LOCATIONS  
WHICH IS ALLOWING THE ICE ACCRETION ON THE TREES TO PERSIST.  
TEMPERATURES ARE EXPECTED TO WARM A FEW DEGREES OVERNIGHT, SO  
LITTLE OR NO ADDITIONAL ICING IS EXPECTED. THE EVENING RNK  
SOUNDING WAS +8 DEG C JUST ABOVE 850 MB... WHICH EQUATES TO 46  
DEGREES F. THE HIGHER MOUNTAIN RIDGES MAY ACTUALLY WARM INTO THE  
LOWER 40S OVERNIGHT AS THIS WARM AIR LOWERS IN ALTITUDE JUST  
AHEAD OF THE APPROACHING LOW PRESSURE. THE ACTUAL TEMPERATURE OF  
THE RAIN ALSO GETS MODIFIED A FEW DEGREES BEFORE REACHING THE  
SURFACE, SO THE MORE IT RAINS, THE WARMER IT SHOULD GET  
OVERNIGHT.  
 
OVERALL PRECIPITATION AMOUNTS RANGED FROM A QUARTER TO THREE  
QUARTERS OF AN INCH SUNDAY. THERE WERE EVEN REPORTS OF THUNDER  
DURING THE AFTERNOON, SOME OF WHICH RESULTED IN ISOLATED RAIN  
AMOUNTS OF UP TO 1 INCH. ADDITIONAL RAIN OVERNIGHT IS EXPECTED  
TO REMAIN UNDER A HALF INCH. THAT SAID, NOT OUT OF THE QUESTION  
FOR A FEW LOCATIONS TO SEE 24 HOUR AMOUNTS (ENDING 7AM MONDAY)  
TO RANGE FROM 1.0 TO 1.5. GIVE THE LOCALIZED NATURE OF THE  
HEAVIEST RAIN, FLOODING IS NOT EXPECTED. NEVER THE LESS, PONDING  
OF WATER IS A HIGH LIKELIHOOD WITH SOME POOR DRAINAGE ISSUES.  
OVERALL, THE CURRENT RAINFALL INCREASES THE SENSITIVITY OF THE  
STREAMS AND CREEKS TO FUTURE RUNOFF FROM RAIN LATER IN THE WEEK,  
BUT NOTHING OF THE LIFE THREATENING VARIETY AT THE MOMENT.  
 
ON MONDAY, WE WILL BE ON THE BACK SIDE OF THE DEPARTING SYSTEM, AND  
WINDS WILL SHIFT NORTHWEST AND BECOME GUSTY. GUSTS OF 30 TO 40 MPH  
WILL BE COMMON ACROSS THE HIGHEST TERRAIN ALONG AND WEST OF THE  
CREST OF THE BLUE RIDGE. GUSTS OF 15 TO 25 MPH WILL BE COMMON ACROSS  
THE PIEDMONT REGION. THESE SAME NORTHWEST WINDS WILL ALLOW FOR DRIER  
AIR TO ERODE CLOUD COVER ACROSS THE PIEDMONT. HOWEVER, CLOUDS WILL  
BE SLOWER TO ERODE ACROSS THE MOUNTAINS THANKS TO AN UPSLOPE  
COMPONENT. LIGHT PRECIPITATION IN THE FORM OF LIGHT RAIN/DRIZZLE OR  
LIGHT FREEZING RAIN/DRIZZLE WILL BE POSSIBLE ACROSS WESTERN  
GREENBRIER COUNTY HEADING INTO THE AFTERNOON. A FEW FLAKES OF SNOW  
ARE POSSIBLE AS THE TOP OF THE SHALLOW MOISTURE LAYER COOLS TO ABOUT  
-10C LATE IN THE DAY. HIGH TEMPERATURES TOMORROW WILL RANGE FROM THE  
LOW TO MID 40S ACROSS THE MOUNTAINS WITH LOW TO MID 50S ACROSS THE  
PIEDMONT.  
 

 
   
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/
 
 
AS OF 400 PM EST SUNDAY...  
 
VERY ACTIVE AND UNSETTLED PATTERN TO CONTINUE THROUGH THE  
PERIOD WITH SIGNIFICANT POTENTIAL FOR A WINTER STORM, WITH BOTH  
SIGNIFICANT ICE AND SNOW ACCUMULATIONS POSSIBLE, FOLLOWED BY AN  
EXTENDED PERIOD OF MODERATE TO HEAVY RAIN EVENTS. AREAL FLOODING  
AND RIVER FLOODING SEEM ALMOST CERTAIN AS WE MOVE INTO THE MID  
PART OF THE WEEK AND THE WEEKEND. THE CULPRIT WILL BE A VERY  
ACTIVE SOUTHWEST FLOW AS DEEP TROUGHING REMAINS ANCHORED ACROSS  
THE SOUTHWEST U.S. WITH AN ENDLESS SERIES OF VIGOROUS EMBEDDED  
SHORT WAVES TRACKING FROM THE SOUTHWEST U.S. INTO THE SOUTH  
CENTRAL U.S. THEN MOVING EAST-NORTHEAST TO NORTHEAST TOWARD THE  
MID-ATLANTIC. IN ESSENCE THE MAIN STORM TRACK WILL BE RIGHT  
ACROSS OUR AREA THROUGH THE ENTIRE TIME FRAME. THIS WILL SUPPLY  
PERSISTENT CLOUD COVER AND NUMEROUS ROUNDS OF PRECIPITATION.  
FLOODING FROM EXCESSIVE RAINFALL AND SATURATED GROUND WILL  
CLEARLY BE THE MAIN CONCERN, ESPECIALLY AS THE WEEK PROGRESSES  
CONTINUING INTO THE LONG TERM PERIODS.  
 
UNFORTUNATELY, WITH A CANADIAN AIR MASS LINGERING JUST TO OUR  
NORTH AND MEANDERING/OSCILLATING BACK/FORTH ACROSS OUR LATITUDE,  
THERE WILL BE A DEFINITE CONCERN FOR WINTER WEATHER. THAT  
CONCERN HAS SOLIDIFIED CONSIDERABLY FROM YESTERDAY AS THE DEPTH  
OF COLD AIR APPEARS MORE CERTAIN AND FURTHER SOUTH THAN  
INDICATED YESTERDAY, WHICH IS CONSISTENT WITH A DEEPER WEDGE  
DEVELOPING IN RESPONSE TO THE SLOW DEEPENING TROUGH IN THE SOUTH  
CENTRAL U.S. AS THE WARM NOSE FROM A STRONG SOUTHWESTERLY JET  
WORKS ITS WAY OVER THE SHALLOW COLD AIR MASS LATER IN THE  
NIGHT/WEDNESDAY MORNING, THE PRECIPITATION WILL TRANSITION TO  
SLEET AND THEN FREEZING RAIN. MODEL SIGNALS ARE STRONG FOR  
SIGNIFICANT SNOW, SLEET, AND ICE ACCUMULATIONS, AND THIS COULD  
WELL BE THE MOST SIGNIFICANT WINTER STORM IN TERMS OF TOTAL  
ACCUMULATION SINCE THE MID-DECEMBER EVENT. WITH GOOD  
COLLABORATION VIA WPC AND NEIGHBORING OFFICES THIS AFTERNOON, WE  
CONCURRED ON THE POTENTIAL FOR WINTER WEATHER WITH THIS EVENT  
AND HAVE FOLLOWED THEIR SNOW AND ICE ACCUMULATIONS CLOSELY,  
NAMELY WINTER STORM WARNING CRITERIA ICE OF .25 TO .50 INCH AND  
SNOW ACCUMULATIONS OF 4-8 INCHES ACROSS THE NORTH WITH 1-3  
INCHES IN THE SOUTH. GIVEN THAT THIS IS 72+ HOURS OUT, NO  
HEADLINES HAVE BEEN ISSUED YET, BUT WILL STRONGLY HIGHLIGHT THE  
POTENTIAL IN THE HWO/EHWO.  
 
CURRENT INDICATIONS ARE THAT THE WINTER WEATHER EVENT WILL  
TRANSITION INTO A FLOODING EVENT THROUGH THE DAY WEDNESDAY AND  
WEDNESDAY NIGHT. CURRENT QPF PROJECTIONS ARE IN THE 2-4 INCH  
RANGE FOR THE TUE-THU TIME FRAME, WHICH IS IN ADDITION TO ALL  
THE RAIN WE HAVE RECEIVED OVER THE WEEKEND AND EARLY THIS WEEK.  
WPC HAS NOTED THAT THERE ARE NUMEROUS MODELS WITH STRONG SIGNALS  
FOR FLOODING ACROSS A LARGE PORTION OF THE SOUTHEASTERN U.S., TN  
VALLEY, AND INTO THE SOUTHERN APPALACHIANS. AGAIN, BEING THAT  
THIS IS OVER 72 HOURS OUT, NO HEADLINES HAVE BEEN ISSUED AT THIS  
TIME, BUT AREAL FLOODING AND RIVER FLOODING APPEARS LIKELY.  
PLEASE PLAN ACCORDINGLY.  
 
TEMPERATURES WILL AVERAGE NEAR NORMAL DURING THIS PERIOD AS WE  
OSCILLATE BETWEEN THE COLDER CANADIAN AIR MASS PRESENT JUST TO  
OUR NORTH AND THE MUCH MILDER AIR TO OUR SOUTH. THUS, THERE WILL  
BE SOME FLUCTUATIONS ABOVE AND BELOW NORMAL THROUGH THE TIME  
PERIOD. WEDNESDAY WILL REMAIN BELOW NORMAL, BUT MUCH ABOVE  
NORMAL TEMPERATURES ARE EXPECTED AS THE WEEK PROGRESSES.  
 
/CONFIDENCE IN FORECAST PARAMETERS/  
TEMPERATURES - MODERATE TO HIGH,  
PRECIPITATION PROBABILITIES - HIGH,  
WINTER WEATHER POTENTIAL - MODERATE,  
FLOODING POTENTIAL - MODERATE TO HIGH,  
WINDS - MODERATE TO HIGH.  
 

 
   
LONG TERM /THURSDAY THROUGH SUNDAY/
 
 
AS OF 430 PM EST SUNDAY...  
 
VERY WET AND UNSETTLED WEATHER CONTINUES WITH A POSITIVELY  
TILTED MEAN TROUGH IN THE WESTERN U.S. AND A BROAD SUBTROPICAL  
RIDGE REMAINING ANCHORED OFF THE SOUTHEAST U.S. COAST. THIS WILL  
KEEP A CONVEYOR BELT OF DEEP MOISTURE ANCHORED OVER THE AREA  
ALONG WITH AN ACTIVE BAROCLINIC ZONE. TEMPERATURES WILL START  
OUT BELOW NORMAL ON WEDNESDAY, THEN CREEP TO ABOVE NORMAL LEVELS  
BY THE END OF THE WEEK AS THE BAROCLINIC ZONE IS NUDGED A TAD  
FURTHER NORTH THANKS TO THE PERISTENT SUBTROPICAL RIDGE OFF THE  
SOUTHEAST U.S. COAST. INDICATIONS ARE THAT THE BAROCLINIC ZONE  
WILL SLIP SOUTH OF THE AREA BRIEFLY AS HIGH PRESSURE BUILDS TO  
OUR NORTH ON THURSDAY, TO PROVIDE A SMALL OPPORTUNITY FOR THE  
HEAVIER RAIN TO SHIFT SOUTH OF OUR AREA. HOWEVER, ANOTHER  
SIGNIFICANT WAVE EMANATING FROM THE SOUTHWEST U.S. TROUGH IS  
PROGGED TO PUSH THE BAROCLINIC ZONE BACK NORTH INTO OUR AREA  
SATURDAY WITH MORE HEAVY RAIN AND FLOODING POSSIBLE AT THAT  
TIME.  
 
AT ANY RATE, TEMPERATURES WILL FINALLY WARM ENOUGH WITH  
SOUTHWEST FLOW TO ERODE THE RETURNING WEDGE, THAT THE MAIN  
FOCUS THROUGH THIS PERIOD WILL BE FLOODING, NOT WINTER WEATHER.  
 
WPC DAYS 1-7 PRECIP OUTLOOK CURRENTLY HIGHLIGHTS AREAS EXCEEDING  
4" MAINLY IN WESTERN NC, EASTERN TN, AND SOUTHWEST VA. AREAWIDE,  
EXPECT AT LEAST 2-3", WITH LOCAL AMOUNTS OF 4-5 INCHES LIKELY.  
PLEASE REMAIN ABREAST OF THE THREAT OF FLOODING AND RIVER  
FLOODING WITH LATER FORECASTS AS THEIR IS AN INCREASING THREAT  
FOR AREAL FLOODING AND RIVER FLOODING, ESPECIALLY DURING THE  
LATER HALF OF THE WEEK.  
 
AS NOTED ABOVE, WITH THE REGION INCREASINGLY IN THE WARM SECTOR  
DURING THIS PERIOD, TEMPERATURES WILL AVERAGE ABOVE NORMAL AND  
REMAIN MOSTLY ABOVE FREEZING.  
 

 
   
AVIATION /01Z MONDAY THROUGH FRIDAY/
 
 
AS OF 930 PM EST SUNDAY...  
 
IFR/LIFR A HIGH LIKELIHOOD OVERNIGHT. RAIN IS EXPECTED FOR MOST  
OF THE OVERNIGHT WITH LOW STRATUS AND FOG. THE AREA OF LOW  
PRESSURE RESPONSIBLE FOR THE POOR FLIGHT CONDITIONS IS FORECAST  
TO MOVE EAST OF THE AREA EARLY MONDAY. THIS WILL BEGIN A PERIOD  
OF CLEARING WITH IMPROVEMENT BACK INTO THE VFR RANGE FROM MONDAY  
AFTERNOON INTO EARLY TUESDAY. THE ONLY EXCEPTION WITH BE THE  
WESTERN SIDE OF THE APPALACHIANS FROM THE EASTERN OH VALLEY INTO  
PA/WV WHERE LOW LEVEL STRATO-CU WILL PERSIST PROMOTING MVFR.  
 
IN THE WAKE OF THIS STORM SYSTEM, WINDS WILL SHIFT NORTHWEST  
AND TREND GUSTY. WINDS GUSTS OF 15 TO 25 KTS WILL BE COMMON  
MONDAY AND EARLY MONDAY NIGHT.  
 
FORECAST CONFIDENCE IN THE ABOVE SCENARIO IS MODERATE.  
 
EXTENDED AVIATION DISCUSSION...  
 
LINGERING MOUNTAIN CLOUDINESS IS EXPECTED TO MAINTAIN MVFR CIGS  
ACROSS THE MOUNTAINS THROUGH MONDAY NIGHT.  
 
BRIEF BREAK IN THE WET WEATHER IS EXPECTED TUESDAY, CONDITIONS  
PRIMARILY VFR. TUESDAY NIGHT AND WEDNESDAY ANOTHER LOW PRESSURE  
SYSTEM WILL BRING SUB-VFR CONDITIONS AS WELL AS PROVIDING  
ANOTHER OPPORTUNITY FOR WINTER PRECIPITATION.  
 
A FRONTAL BOUNDARY WILL REMAIN CLOSE TO THE REGION THURSDAY  
INTO FRIDAY KEEPING PRECIPITATION AND THE POTENTIAL FOR SUB-VFR  
CONDITIONS IN THE FORECAST.  
 

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

 
 

 
SYNOPSIS...DS  
NEAR TERM...DS/PM  
SHORT TERM...RAB  
LONG TERM...RAB  
AVIATION...DS/PM  
 
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