517
FXUS61 KRNK 081122
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
722 AM EDT WED APR 8 2020
SYNOPSIS
A NEARLY STATIONARY BOUNDARY WAS LOCATED FROM WESTERN
PENNSYLVANIA TO EASTERN VIRGINIA, WHILE A COLD FRONT WAS NOTED
ACROSS THE NORTHERN MISSOURI VALLEY. THIS COLD FRONT WILL MOVE
INTO OUR REGION WEDNESDAY AHEAD OF A STRONGER COLD FRONT THAT
WILL QUICKLY PUSH THROUGH OUR AREA THURSDAY. UNTIL THE FRONT
ARRIVES, SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS ARE
EXPECTED. BEHIND THE FRONT, LOOK FOR STRONG AND GUSTY NORTHWEST
WINDS AND MUCH COLDER TEMPERATURES WITH A FREEZE POSSIBLE THIS
WEEKEND.
NEAR TERM /THROUGH TONIGHT/
AS OF 415 AM EDT WEDNESDAY...
POTENTIAL FOR A CONVECTIVELY ACTIVE DAY AND NIGHT AS AT LEAST
TWO ROUNDS OF ORGANIZED THUNDERSTORMS ENCROACH UPON THE REGION,
FIRST THIS MORNING, AND THEN AGAIN LATER TONIGHT/EARLY THURSDAY.
IN BETWEEN, THERE IS GOOD POTENTIAL FOR REDEVELOPMENT OF
POTENTIAL IN THE PERSISTENT WARM/INCREASINGLY HUMID/UNSTABLE AIR
MASS PRESENT ACROSS THE AREA.
OUR FIRST CONCERN OF THE DAY IS A NEAR SOLID LINE OF
THUNDERSTORMS AN ATTENDANT MCS EARLY THIS MORNING MOVING
SOUTHWARD FROM NORTHERN VA AND NORTHERN WV. THE HIRES CAM MODELS
BRING THIS DOWN TO THE NORTH/NORTHWEST BORDER OF THE CWA BY 12Z,
THEN BREAK IT UP FAIRLY QUICKLY AS IT CROSSES THE ALLEGHANY
FRONT INTO THE WEST/SOUTHWEST PART OF THE CWA. THE AREA OVER
NORTHERN VA IS FORECAST TO DISSIPATE QUICKLY WITHIN THE NEXT FEW
HOURS WELL BEFORE REACHING THE I-64 CORRIDOR. IF ALL GOES
ACCORDING TO PLAN, ONLY SOME MINOR GUSTY WINDS AND RAIN
SHOWERS/POSSIBLY ISOLATED THUNDER WILL REACH AREAS FROM LWB TO
BLF BY DAYBREAK.
AFTER THIS INITIAL CONVECTION SURGE, OUR FOCUS TURNS TO HOW ANY
LINGERING OUTFLOW BOUNDARIES AROUND IN THE RELATIVELY UNSTABLE,
WARM, HUMID AIR MASS FIGURE IN THE DEVELOPMENT OF ADDITIONAL
CONVECTION LATER THIS MORNING AND INTO THE AFTERNOON. HIRES CAM
MODELS HAVE VARYING SOLUTIONS, WITH THE HRRR INDICATING STRONG
DISCRETE CONVECTION IS POSSIBLE ESPECIALLY ALONG AND EAST OF THE
BLUE RIDGE DURING THE AFTERNOON. HOWEVER, THE RAP, NAMNEST, GFS,
SREF, HREF, DO NOT SUPPORT NEARLY AS MUCH CONVECTION IN THIS
REGION. SO HAVE JUST STUCK WITH SLIGHT CHANCE TO CHANCE POPS FOR
THE AFTERNOON/EVENING AT THIS POINT AS THE REMNANTS OF THE
MORNING MCS DRIFT INTO THE EASTERN KY/WESTERN WV, SOUTHWEST VA
AREA BY AFTERNOON, WHICH IS WHERE THE HIGHEST POPS HAVE BEEN
FOCUSED FOR THE MORNING.
OVERNIGHT, THE ANTICIPATED STRONG FRONT WILL BEGIN TO MOVE
TOWARD THE REGION FROM THE MIDWEST AND OHIO VALLEY. YET ANOTHER
LINE OF STRONG CONVECTION IS EXPECTED TO DEVELOP ALONG THAT
FRONT, ONCE AGAIN REACHING OUR CWA LATE TONIGHT/EARLY THURSDAY.
THIS EVENT WILL COME FROM THE WEST AS OPPOSED TO THE NORTH, BUT
THE TIMING IS SIMILAR AND NOT OVERLY FAVORABLE FOR STRONG TO
SEVERE CONVECTION. THIS IS PARTLY THE REASON THAT SPC HAS KEPT
THE SLIGHT RISK TO OUR WEST AT THIS POINT. IT MAY WELL BE THAT
THE SEVERE THREAT TODAY ENDS UP BEING GREATER THAN THAT OF
TOMORROW.
OTHERWISE, LOOK FOR ONE MORE WARM AND RELATIVELY HUMID DAY
COMPARED TO EARLIER THIS WEEK. LOW TEMPERATURES THIS MORNING
NEAR 60 AS OPPOSED TO THE 30S AND 40S OF THE PAST FEW DAYS
REFLECTS THE INCREASED NEAR 60-DEGREE DEWPOINTS ACROSS MUCH OF
THE CWA. GUSTY SOUTHWEST WINDS SHOULD PUSH AFTERNOON
TEMPERATURES MAINLY IN THE 70S WEST AND 80S EAST. WITH THE COLD
AIR NOT ARRIVING UNTIL AFTER 12Z THURSDAY, TONIGHT WILL BE QUITE
MILD ONCE AGAIN WITH MANY AREAS REMAINING IN THE 60S FOR LOWS,
EXCEPT WHERE ANY THUNDERSTORM OUTFLOW OR RAIN ARRIVES BEFORE
12Z, WHICH COULD ALLOW TEMPERATURES TO DROP INTO THE 50S.
/CONFIDENCE IN FORECAST PARAMETERS/
TEMPERATURES - MODERATE TO HIGH,
PRECIPITATION PROBABILITIES - MODERATE,
WINDS - MODERATE TO HIGH,
THUNDERSTORM THREAT - MODERATE.
SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/
AS OF 200 AM EDT WEDNESDAY...
A STRONG COLD FRONT WILL CROSS OVERHEAD ON THURSDAY MORNING. A LINE
OF SHOWERS AND THUNDERSTORMS WILL PRECEDE THE FRONTAL BOUNDARY AND
COULD POSE A MARGINAL RISK OF SEVERE WEATHER DUE TO DAMAGING WINDS.
BEHIND THE FRONT, WINDS WILL SHARPLY INCREASE FROM THE NORTHWEST,
AND CONFIDENCE IS GROWING THAT A WIND ADVISORY MAY BE NEEDED FOR
THURSDAY AFTERNOON AND THURSDAY NIGHT ALONG THE BLUE RIDGE. FOR NOW,
THE WIND THREAT IS HIGHLIGHTED IN THE HWO. A NON-DIURNAL CURVE IN
TEMPERATURES HAS BEEN APPLIED FOR THURSDAY AS THEY WILL START TO
FALL DURING MIDDAY AND CRASH BY THE EVENING AS A MUCH COLDER AND
DRIER AIR MASS ARRIVES TO END THE UNSEASONABLE WARMTH FROM THIS
WEEK. THE DROP IN RELATIVE HUMIDITIES ALONG WITH THE GUSTY WINDS
COULD ALSO POSE FIRE DANGER ISSUES FOR LATE THURSDAY AFTERNOON AND
AGAIN ON FRIDAY AFTERNOON IF WE DO NOT GET MUCH RAIN AND THE WINDS
DO NOT SUBSIDE AS QUICKLY DURING FRIDAY.
AS TEMPERATURES PLUMMET BELOW FREEZING IN THE MOUNTAINS ON THURSDAY
NIGHT, UPSLOPE SNOW SHOWERS WILL OCCUR ACROSS THE HIGHER ELEVATIONS
OF SOUTHEAST WEST VIRGINIA WITH ONLY WESTERN GREENBRIER COUNTY
SEEING UP TO A HALF AN INCH. FLURRIES COULD ALSO BRIEFLY OCCUR IN
THE MOUNTAINS FROM BOONE TO BLUEFIELD BY FRIDAY MORNING. HIGH
PRESSURE WILL EVENTUALLY BUILD OVER THE MID ATLANTIC BY FRIDAY NIGHT
TO END THE GUSTY WINDS, BUT DECOUPLING AND GOOD RADIATIONAL COOLING
SHOULD SEND TEMPERATURES DOWNWARD AND COULD POSE FROST OR FREEZE
ISSUES FOR THE PIEDMONT AND THE SOUTHERN SHENANDOAH VALLEY. QUIET
WEATHER WILL FOLLOW FOR SATURDAY, BUT HIGH PRESSURE SHOULD HEAD
OFFSHORE ON SATURDAY NIGHT. THE GFS HAS STEERED MUCH CLOSER TO THE
MORE CONSISTENT ECMWF SOLUTION OF AN APPROACHING LOW PRESSURE SYSTEM
FROM THE LOWER MISSISSIPPI RIVER VALLEY THAT WILL BRING A SOGGY
START TO THE NEW WEEK.
LONG TERM /SUNDAY THROUGH TUESDAY/
AS OF 200 PM EDT TUESDAY...
GUIDANCE CONTINUES TO GET A BETTER HANDLE ON THE PRESSURE SYSTEM
THAT IS CURRENTLY SITTING OFF THE CALIFORNIA COAST. LATE IN THE
WEEK, THIS LOW GETS KICKED ONSHORE AND CROSSES ACROSS THE SOUTHERN
U.S., EVENTUALLY SHIFTING NORTHWARD TO THE MID-ATLANTIC. TIMING HAS
COME INTO MUCH BETTER AGREEMENT, WITH FIRST A WARM FRONT LIFTING
NORTHWARD ACROSS THE AREA EARLY TO MID DAY SUNDAY. WITH THE WARM
FRONT COMES A RETURN OF WARMER WEATHER. BY SUNDAY NIGHT, THE COLD
FRONT ASSOCIATED WITH THIS LOW WILL THEN CROSS THE REGION. TOTAL
RAINFALL WITH THIS SYSTEM LOOKS PRETTY BEEFY COMPARED TO SOME OF THE
RAIN EVENTS WE'VE HAD RECENTLY. RIGHT NOW, RAIN AMOUNTS COULD RANGE
BETWEEN 1-2".
AFTER SUNDAY'S SYSTEM EXITS, WE COOL OFF AGAIN FOR MONDAY, THOUGH
NOT LIKE WHAT HAPPENS THIS THURSDAY/FRIDAY. GUIDANCE HINTS THAT NW
FLOW WILL ESTABLISH SOME UPSLOPE SHOWERS MONDAY INTO TUESDAY. PRECIP
TYPE AT THE MOMENT REMAINS RAIN, BUT TEMPERATURE PROFILES WILL NEED
TO BE WATCHED OVER THE COMING DAYS AS NEW GUIDANCE ARRIVES. ANY AREA
THAT WOULD HAVE THE POTENTIAL FOR SNOWFALL WOULD AGAIN BE MOST
LIKELY WESTERN GREENBRIER, SIMILAR TO THIS COMING FRIDAY AM.
AVIATION /11Z WEDNESDAY THROUGH SUNDAY/
AS OF 700 AM EDT WEDNESDAY...
AN IMPRESSIVE LINE OF SHOWERS AND THUNDERSTORMS MOVED SOUTHWARD
FROM ALONG AN APPROACHING COLD FRONT NEAR THE MD/PA BORDER
OVERNIGHT AND EARLY THIS MORNING. STRONG WIND GUSTS IN THE 50 TO
60 MPH RANGE HAVE BEEN NOTED ALONG THE LINE WITH CONSIDERABLE
LIGHTNING AS WELL. THIS LINE IS NOW WEAKENING AS IT MOVES ACROSS
THE I-64 CORRIDOR. HIRES CAM MODELS SUGGEST THAT THIS LINE WILL
DISSIPATE AS IT MOVES NEAR THE VA/WV BORDER TOWARD KBLF AND KROA
THIS MORNING. FROM THAT POINT THE QUESTION WILL BE WHERE/IF IT
REDEVELOPS SOUTHEAST WITH AFTERNOON HEATING. HRRR SAYS YES,
WHILE THE OTHER MODELS (E.G., NAMNEST, HREF, SREF, GFS) ARE
LESS ROBUST WITH AFTERNOON CONVECTIVE DEVELOPMENT. THUS, HAVE
MENTIONED VCSH/VCTS FOR BLF/LWB, BUT NOT ANY FURTHER SOUTH UNTIL
AFTERNOON IF THERE IS REDEVELOPMENT ACROSS THE PIEDMONT LATER
TODAY AS NOTED ABOVE. MORNING ACTIVITY WITH STRONG GUSTY WINDS
WERE ADDRESSED IN ALL OF THE TAFS EXCEPT FOR KDAN.
MVFR CEILINGS HAVE DEVELOPED IN RAIN AREAS AND UPSLOPE AREAS
SUCH AS KBLF FROM THUNDERSTORM OUTFLOW. OTHERWISE, CEILINGS ARE
STILL VFR IN MOST OTHER AREAS. WESTERLY FLOW IS FAIRLY HEALTHY
EARLY THIS MORNING THANKS TO A LOW-LEVEL JET AS NOTED ABOVE.
MVFR CIGS WILL DEVELOP DUE TO WESTERLY UPSLOPE WINDS OVER THE
MOUNTAINS AT KLWB, KBLF AND KBCB OVERNIGHT AS WELL, WITH THE
POTENTIAL FOR SOME IFR CIGS IN AREAS LIKE KBLF. THESE MVFR CIGS
WILL CONTINUE THROUGH MUCH OF THE MORNING ON WEDNESDAY.
OCCASIONAL SHOWERS AND ISOLATED STORMS WILL ALSO IMPACT KBCB,
KROA AND KLYH ON WEDNESDAY, PERIODICALLY REDUCING CIGS AND VSBYS
TO MVFR LEVELS. MODELS HAD SHOWERS AND THUNDERSTORMS
REDEVELOPING ALONG THE FRONT AFTER 15Z/11AM. ANY STORMS WILL
REACH KDAN LATER IN THE DAY, SO HAVE NOT INCLUDED UNTIL LATE.
OVERNIGHT, A NEW SQUALL LINE IS EXPECTED TO REACH THE AREA FROM
THE WEST, BUT MOST LIKELY AFTER 06Z, SO NOT INCLUDED IN THIS
TAF SET.
/CONFIDENCE IN FORECAST PARAMETERS/
CEILINGS - MODERATE,
VISIBILITIES - MODERATE TO HIGH,
WINDS - MODERATE.
EXTENDED AVIATION DISCUSSION...
A STRONG COLD FRONT CROSSES THE AREA THURSDAY MORNING WITH
WIDESPREAD MVFR CONDITIONS DUE TO CLOUDS AND PRECIPITATION.
WINDS WILL BE STRONG AND GUSTY BEHIND THE FRONT THURSDAY NIGHT.
COLDER HIGH PRESSURE BUILDS INTO THE AREA ON FRIDAY. IN GENERAL
WINDS WILL BE DIMINISHING AND CEILINGS WILL IMPROVE TO VFR
EXCEPT SOME LINGERING MVFR IN THE MOUNTAINS.
ANOTHER SYSTEM MAY BRING RAIN OUR WAY LATER SATURDAY WITH SUB-
VFR CEILINGS, THOUGH AT THE MOMENT CONFIDENCE IS LOW.
RNK WATCHES/WARNINGS/ADVISORIES
VA...NONE.
NC...NONE.
WV...NONE.
SYNOPSIS...RAB
NEAR TERM...RAB
SHORT TERM...PW
LONG TERM...PW/RR
AVIATION...PH/RAB
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