Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 120459
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1159 PM EST THU FEB 11 2016

.SYNOPSIS...
HIGH PRESSURE WILL BUILD EAST ACROSS THE REGION TONIGHT AHEAD OF
A WEAK AREA OF LOW PRESSURE THAT WILL APPROACH FROM THE WEST BY
EARLY FRIDAY. THIS CLIPPER SYSTEM WILL CROSS OUR AREA ON FRIDAY
WITH SOME LIGHT SNOW ACCUMULATIONS POSSIBLE...ESPECIALLY IN THE
MOUNTAINS. ARCTIC HIGH PRESSURE WILL BUILD IN FOR THE WEEKEND
RESULTING IN VERY COLD BUT OVERALL DRY CONDITIONS INTO SUNDAY.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 1145 PM EST THURSDAY...

00Z LARGER SCALE MODELS AND HIGH-RES MODELS BOTH COMING IN SLOWER
WITH SNOW IN THE MORNING. BASED ON UPSTREAM OBS THIS LOOKS
REASONABLE. WILL DELAY ONSET OF SNOW TIL AFTER 12Z...WITH BEST
LIFT ARRIVING TOWARD 15Z IN THE SW MTNS. THE NAM IS SHOWING ABOUT
2/10 INCH LIQUID WHICH FOR THIS AIRMASS AROUND 15-20:1 RATIO WILL
SPIT OUT CLOSE TO 3 INCHES ACROSS THE HIGHEST TERRAIN LIKE MOUNT
ROGERS...BEECH MTN AND THREE TOP MTN IN NW NC/SW VA. SHOULD QPF
INCREASE MAY HAVE TO GO WITH WINTER WX ADVISORY FOR THE NC
MTNS/GRAYSON...BUT GIVEN THAT IT IS CONFINED TO ABOVE 4000
FT...THE MAJORITY OF FOLKS WILL RECEIVE 2" OR LESS...SO NO
ADVISORY PLANNED WITH THIS UPDATE.

LOWERED TEMPS A FEW MORE DEGREES PER LATEST OBS. WITH MID/HIGH
CLOUDS STREAMING IN OVERNIGHT EXPECT TEMPS TO START TO SLOWLY
DECLINE OR STEADY OUT LATE.

PREVIOUS MID EVENING DISCUSSION...
ONLY A FEW MINOR EDITS WITH THE EVENING UPDATES. ADJUSTED SKY
COVER BASED ON CURRENT IR SIGNATURES. MID DECK LOOKS DELAYED BY AN
HOUR OR SO...AND MUCH DENSER TO THE SOUTH. THUS...ADJUSTED MINIMUM
TEMPERATURE VALUES DOWN IN THE NORTHERN PORTION OF THE FORECAST
AREA DUE TO A LONGER PERIOD OF RADIATIONAL COOLING.

PREVIOUS VALID DISCUSSION...

BRIEF LULL IN THE ACTION WILL OCCUR EARLY TONIGHT AS SURFACE HIGH
PRESSURE BUILDS IN ALLOWING WINDS TO DIMINISH UNDER MAINLY CLEAR
SKIES THIS EVENING. HOWEVER LACK OF MOISTURE WILL BE SHORT LIVED
AS A WARM ADVECTION PATTERN QUICKLY DEVELOPS ALOFT LATE TONIGHT
IN ADVANCE OF THE NEXT DIGGING UPSTREAM SHORTWAVE AHEAD OF THE
NEXT ARCTIC SHOT. GUIDANCE SHOWS THIS LEADING TO AN INCREASE IN
MID CLOUDS FROM THE NW BY MIDNIGHT WITH THIS CANOPY OVERSPREADING
THE REGION BY DAYBREAK. BOUNDARY LAYER APPEARS TOO DRY FOR ANY
PRECIP OTHER THAN MAYBE A FLURRY FAR WEST LATE SO KEEPING POPS OUT
UNTIL JUST BEFORE DAWN SW. TEMPS REMAIN VERY COLD AND WITH LOW
DEWPOINTS EXPECTING A QUICK DROP OFF AFTER SUNSET ESPCLY VALLEYS
AS WIND DIMINISH BEFORE THINGS STEADY OUT WITH CLOUDS ARRIVING.
THIS SUPPORTS GOING A LITTLE BELOW MOS WITH LOWS MOSTLY TEENS WITH
A FEW SINGLE DIGITS NW VALLEYS WHERE SNOW COVER PREVAILS.

FAST MOVING MID LEVEL WAVE AND ASSOCIATED SURFACE CLIPPER WILL PASS TO
THE SOUTH FRIDAY WITH THE SURFACE LOW QUICKLY DEEPENING UPON REACHING
THE CAROLINA COAST. LATEST MODELS BRING A SWATH OF LIFT WITH WEAK
FRONTOGENETIC FORCING INTO THE WESTERN SLOPES FRIDAY MORNING BEFORE
UPWARD MOTION JUMPS TO THE COASTAL SYSTEM. JUST HOW FAR SNOW ASSOCIATED
WITH THIS WESTERN SLUG OF MOISTURE MAKES IT REMAINS IFFY BUT APPEARS
MAY RUN OUT TO THE BLUE RIDGE BEFORE FADING/REDEVELOPING PIEDMONT PRIOR
TO ENDING. LATEST QPF OF AROUND A TENTH OF AN INCH OR LESS WESTERN
MOUNTAINS SUPPORTS AN INCH OR TWO OF SNOW PER HIGH RATIOS...WITH LESS
THAN AN INCH I-81 CORRIDOR/BLUE RIDGE...AND ONLY TRACE AMOUNTS TO THE
EAST. THEREFORE UPPED POPS A BIT FAR WEST AND EXTENDED HIGHER CHANCES
EAST GIVEN FAST MOVEMENT AND POTENTIAL FOR A BAND TO SNEAK OUT ESPCLY
IF THE SHORTWAVE IS A BIT FASTER UNDER STRONG LOW LEVEL BACKED FLOW PER
THE GFS. AMOUNTS STILL BELOW ADVISORY CRITERIA AND GIVEN TIMING OF
MOSTLY BETWEEN THE MORNING/EVENING RUSH HOURS WILL HOLD OFF ON
ANY HEADLINES FOR NOW. OTRW A BRIEF REPRIEVE IN THE ONGOING FRIGID
TEMPS WITH WEAK WARM ADVECTION LIKELY TO PUSH HIGHS INTO THE 30S
EAST...AND POSSIBLY INTO THE UPPER 20S/LOWER 30S ELSEWHERE BEFORE
THE FRONT CROSSES LATE.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
AS OF 330 PM EST THURSDAY...

UPSLOPE SNOW SHOWERS WILL BE ONGOING FRIDAY NIGHT. WINDS TURN TO THE
NORTHWEST WITH A LOW LEVEL JET PEAKING AROUND 50 KNOTS OVERNIGHT.
MUCH DRIER AIR COMES IN BEHIND THE CLIPPER. MODELS SUGGEST ONLY
ENOUGH LOW LEVEL MOISTURE FOR SNOW SHOWERS IN WESTERN GREENBRIER
COUNTY BY SATURDAY EVENING. BUFKIT SOUNDINGS...PRESSURE RISES AND
INVERSION HEIGHT ALONG THE SOUTHERN BLUE RIDGE AND INTO THE
NORTHWEST NORTH CAROLINA MOUNTAINS SUPPORT THE POSSIBILITY OF
ADVISORY LEVEL WIND GUSTS FRIDAY NIGHT. HAVE MENTIONED THIS
POTENTIAL THREAT IN THE HAZARDOUS WEATHER OUTLOOK.

COLDEST AIR WITH THIS ARCTIC AIRMASS WILL BE OVER THE REGION ON
SATURDAY AND SATURDAY NIGHT. BY SUNDAY AFTERNOON THE CENTER OF THE
SURFACE HIGH IS CROSSING THE MID ATLANTIC STATES. MINIMUM
TEMPERATURES SATURDAY NIGHT WILL BE 15 TO 25 DEGREES BELOW NORMAL.
ON SATURDAY NIGHT THE WINDS WILL NOT BE AS STRONG...BUT WITH COLDER
TEMPERATURES...THE COMBINATION WILL STILL RESULT IN DANGEROUS WIND
CHILLS ACROSS PARTS OF THE MOUNTAINS.

MID AND HIGH CLOUDS SPREAD BACK OVER THE AREA ON SUNDAY FROM THE
WEST. LOW CONFIDENCE IN HOW LONG IT WILL TAKE TO SATURATE LOWER
LAYERS ENOUGH FOR PRECIPITATION FOR SUNDAY NIGHT. NO CHANGES IN THE
ARRIVAL TIME OF THE PRECIPITATION FOR NOW.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 100 PM EST THURSDAY...

A PIECE OF THE SURFACE HIGH REMAINS WEDGED DOWN THE EAST SIDE OF THE
APPALACHIANS WITH COASTAL TROFING ALSO DEVELOPING ON MONDAY. THE GFS
AND CANADIAN BRING A SURFACE LOW FROM THE LOWER MISSISSIPPI VALLEY
SUNDAY THEN DEEPEN THE LOW AND TRACK IT NORTHEAST TO THE CAROLINAS
BY TUESDAY. THE ECMWF IS INITIALLY WEAKER WITH THE LOW THEN FASTER
TRACKING IT NORTHEAST ALONG THE COAST TUESDAY. OF COURSE THE TRACK
OF THE LOW WILL HAVE TREMENDOUS INFLUENCE ON THE RESULTING WEATHER
FOR THE COUNTY WARNING AREA. WPC FAVORING ENSEMBLES FORECASTS IN
THIS TIME FRAME. BULK OF THE PRECIPITATION WITH THIS STORMS SYSTEM
AT THIS TIME LOOKS TO BE ON LATE MONDAY THROUGH TUESDAY MORNING.
ENTIRE FORECAST AREA STAYS COLD ENOUGH AT ALL LEVEL FOR SNOW THROUGH
MONDAY MORNING. THEN VERY STRONG SOUTHERLY JET BRINGS IN WARMER AIR
ABOVE THE SURFACE. THIS WILL LIKELY CAUSE MIXED WINTER
PRECIPITATION. WITH THE WEDGE IN PLACE...MODELS MAY BE TOO AGGRESSIVE
WARMING UP THE SURFACE THROUGH 850 MB LAYER MONDAY NIGHT.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1150 PM EST THURSDAY...

VFR THROUGH 12Z WITH INCREASING MID/HIGH CLOUDS. MODELS SLOWING
TIMING OF SNOW AND LOWER CIGS DOWN UNTIL 12Z OR AFTER. STILL LOOKS
LIKE MVFR CIGS ARE LIKELY AT BLF/LWB/BCB BETWEEN 17-18Z...WITH
LIGHT SNOW/FLURRIES MOVING IN A COUPLE HOURS BEFORE THIS.
CONFIDENCE HIGH IN MVFR CIGS BUT NOT HIGH ENOUGH TO WARRANT IFR
CIGS/VSBYS BUT POSSIBLE DURING THE EARLY AFTERNOON FRIDAY.

FLURRIES ALSO EXPECTED AT DAN/ROA...WITH LOW END VFR CIGS.

WINDS LIGHT THROUGH THE DAY TOMORROW. ONCE LOW MOVES OFF THE COAST
WINDS INCREASE FROM THE WEST-NORTHWEST FRIDAY EVENING AND
ESPECIALLY OVERNIGHT. THIS WILL LEAD TO INCREASE IN SNOW SHOWERS
THROUGH SAT MORNING IN THE WEST...WITH WINDS GUSTING UP TO 30 TO
40 KTS...ESPECIALLY ROA/BCB.

EXTENDED DISCUSSION...

EXPECT VFR SAT AFTERNOON THROUGH SUNDAY WITH SUBSIDING
WINDS...THOUGH SOME MVFR INTO SAT NIGHT POSSIBLE AT BLF.

THE NEXT LOW PRESSURE SYSTEM WILL ARRIVE ON SUNDAY NIGHT.
CONFIDENCE IS HIGH THAT POOR FLYING WEATHER WILL TAKE PLACE
DURING MONDAY AND TUESDAY. THIS SYSTEM COULD BRING SOME WINTRY
PRECIPITATION...BUT FURTHER UPDATES FROM THE LONGER RANGE MODELS
MAY IMPACT THE DETAILS ON PRECIPITATION TYPE AND STORM TRACK.

&&

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

&&

$$
SYNOPSIS...JH
NEAR TERM...JH/JM/WP
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...PW/WP


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