-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 011407
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
907 AM EST SUN MAR 1 2015

.SYNOPSIS...
HIGH PRESSURE TO OUR NORTH WILL MAINTAIN COLD AIR OVER THE AREA
INTO THIS AFTERNOON. MEANWHILE...AN UPPER LEVEL DISTURBANCE AND
ASSOCIATED AREA OF SURFACE LOW PRESSURE WILL MOVE ACROSS THE MID
ATLANTIC REGION BY THIS AFTERNOON BEFORE EXITING THIS EVENING. MOIST
AIR FLOWING NORTH AHEAD OF THIS DISTURBANCE WILL INTERACT WITH THE
COLD AIR RESULTING IN A WINTRY MIX OF PRECIPITATION ACROSS THE MID
ATLANTIC STATES TODAY...BEFORE A COLD FRONT ARRIVES OVERNIGHT
BRINGING DRIER AIR FOR MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 905 AM EST SUNDAY...
ISENTROPIC LIFT OVER TOP THE CAD CONTINUES TO RESULT IN WINTRY
MIX OF SNOW...SLEET AND FREEZING RAIN THIS MORNING. WINTER WEATHER
ADVISORIES WILL REMAIN AS POSTED FOR NEXT COUPLE OF HOURS BUT
WILL BE TRIMMED BACK AS THE WARMER AIR JUST TO OUR WEST PUSHES
INTO OUR REGION ENDING THE THREAT. THE HEAVIEST BAND OF SLEET AND
FREEZING RAIN LOCATED IN THE SOUTHEAST PORTION OF FORECAST AREA
WILL LIFT NORTHEAST THIS MORNING. FREEZING RAIN RATES FROM TRACE
TO AROUND A 0.10 INCH PER 3 HOURS ARE POSSIBLE THROUGH 16Z.
ADJUSTED POPS WITH A BLEND OF HIRESW-ARW...RNK WRFARW AND GFS FOR
THIS MORNING INTO THIS AFTERNOON. ADJUSTED TEMPERATURES ACCORDING
TO LATEST OBS AND MODEL TREND THIS MORNING. WILL HAVE TO ADJUST
HIGH TEMPERATURES DEPENDING ON THE PUSH OF THE WARM AIR. MORE
ADJUSTMENTS LATER THIS MORNING.


AS OF 215 AM EST SUNDAY...

AREA REMAINS UNDER THE DRY WEDGE ALONG/EAST OF THE MOUNTAINS THIS
MORNING WHICH IS BASICALLY IN BETWEEN SHORTWAVE ENERGY PASSING TO THE
NW AND RETURN FLOW DEEPER MOISTURE TO THE SOUTH. LATEST GUIDANCE HAS
TURNED A BIT LESS ENTHUSIASTIC IN REGARDS TO CONNECTING THESE AREAS OF
LIFT UNTIL THE PRECIP TURNS OUT EAST OF THE BLUE RIDGE LATER THIS
MORNING WITH MOST SHOWING MUCH LESS QPF NOW OVER THE WEST. THIS SEEN
WITH THE EASTWARD TRENDS OFF BOTH THE GFS/NAM AND ALMOST TOTAL LACK OF
PRECIP HEADING UP FROM THE SOUTH OFF THE 00Z EC GIVEN SO MUCH DRY AIR
IN PLACE.

HOWEVER APPEARS ENOUGH WEAK ISENTROPIC LIFT OVER TOP THE CAD FROM
THE SOUTH TO GENERATE SOME LIGHT QPF MOUNTAINS/SW BEFORE
DAYBREAK...WITH THE AXIS OF RETURN MOISTURE THEN TURNING MORE
EAST/NE WHILE PRIMARILY AFFECTING THE FOOTHILLS/PIEDMONT THIS
AFTERNOON WHEN TEMPS WILL BE SLOWLY RISING. THINK THE CORRIDOR OF
SNOW TO THE NW WITH THE MAIN AXIS OF DEEPER LIFT WILL PASS TO THE
NORTH BUT MAY CLIP THE NW CORNER WITH A PERIOD OF SNOW SO KEPT AN
INCH OR TWO THERE. OTRW LATEST FORECAST SOUNDINGS SUPPORT MORE
SLEET BANDS AND POCKETS OF SNOW STARTING FROM SOUTH TO NORTH EARLY
ON AIDED BY EVAPORATIVE COOLING...THEN SWITCHING TO MORE
LIQUID/FZRA AS THE LARGE WARM NOSE ALOFT WINS OUT AND WET BULBING
DECREASES ESPCLY FROM MID MORNING ON. HOWEVER PRECIP COVERAGE OVER
THE WEST MAY BE DECREASING QUICKLY BY LATE MORNING WITH PERHAPS
THE MOUNTAIN EMPIRE REGION INTO THE NW NC RIDGES SEEING ONLY
SPOTTY AMOUNTS. APPEARS BEST SHOT AT ICING WILL BE FROM THE NC
FOOTHILLS NORTH ALONG THE SOUTHERN BLUE RIDGE INITIALLY...THEN
EAST WHERE THE DEEPER LOW LEVEL COLD AIR WILL RESIDE UNTIL VERY
LATE IN THE DAY. APPEARS A GOOD TENTH OR SO ICE ACCRETION POSSIBLE
FOR MUCH OF THE AREA EAST OF THE BLUE RIDGE BUT PERHAPS LESS THAN
SEEN FROM EARLIER GUIDANCE.

THUS TRIMMED BACK TOTALS SOME PER LATEST WWD AND THE FORECAST WARMER
BOUNDARY LAYER LIKELY DUE TO LESS SIGNIFICANT PRECIP TO COOL THE COLUMN
BUT LEAVING THE GOING ADVISORY IN PLACE. HIGH TEMPS REMAIN VERY TRICKY
GIVEN MUCH WARMER MOS VALUES AND POTENTIAL FOR AN AFTERNOON DRY SLOT
ESPCLY WEST AS SEEN OFF THE LATEST HRRR/CMC AND GFS TO SOME DEGREE. FOR
NOW BUMPED UP HIGHS A GOOD CAT OR SO FAR WEST WHERE WILL BE ON THE
PERIPHERY OF THE WEDGE AND WARMED THE EAST A DEGREE OR TWO FOR MORE OF
A LATE DAY HIGH SCENARIO PENDING PRECIP COVERAGE.

WEAK SUBSIDENCE SPILLS IN BEHIND THE DEPARTING SWATH OF DEEPER MOISTURE
THIS EVENING LEAVING A RESIDUAL AXIS OF WRAP AROUND TYPE PRECIP OVER
THE NW AHEAD OF THE UPSTREAM COLD FRONT THAT WILL REACH THE WESTERN
SLOPES LATE. COULD BE SOME SPOTTY -RA/DZ/FOG AROUND DURING THE EVENING
INCLUDING POCKETS OF VALLEY -FZRA NORTH/NE OTRW MOST RAIN WILL BE
CONFINED TO THE NW. DEEPER COLD ADVECTION ARRIVES AFTER MIDNIGHT ON
INCREASING/GUSTY NW WINDS MOUNTAINS WITH THE 85H FRONT CROSSING THE
WESTERN SLOPES WHICH SHOULD ALLOW RAIN TO CHANGE TO SNOW SHOWERS BEFORE
TAPERING AROUND DAYBREAK. THIS MAY RESULT IN ANOTHER INCH OR SO OF SNOW
NW SLOPES WITH SPOTTY COVERAGE DOWN IN THE NC MOUNTAINS AND MAINLY
CLOUDS ELSEWHERE OVERNIGHT. TEMPS SHOULD STEADY IF NOT RISE AHEAD OF
THE FRONT OVERNIGHT AS THE WARM ADVECTION BOOTS THE WEDGE OUT BEFORE
COLDER AIR ARRIVES NW LATE ALLOWING TEMPS TO DROP AGAIN AROUND SUNRISE.
DID TREND TOWARD THE COLDER MAV MOS OVERNIGHT ALTHOUGH SOME SPOTS THAT
GET WARMER DURING THE DAY MAY STAY IN THE 40S OVERNIGHT.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 330 AM EST SUNDAY...

HIGH PRESSURE BUILDING IN BEHIND THE FRONT ON MONDAY WILL BRING AN
END TO UPSLOPE SNOW SHOWERS FOR THE FAR WESTERN SLOPES. THERE LOOKS
TO BE A GOOD AMOUNT OF WIND THROUGH THE FIRST PART OF MONDAY AND...
IF MODEL TRENDS CONTINUE TO SHOW A STRONG LOW LEVEL WIND FIELD...A
WIND ADVISORY MAY BE NECESSARY FROM THE BLUE RIDGE WEST.

BY MONDAY NIGHT...THE HIGH WILL CONTINUE TO SLIDE EAST AND WE WILL
FIND OUR AREA ONCE AGAIN DEALING WITH A COLD AIR WEDGE DOWN THE
EASTERN SEABOARD. WITH THE LOW LEVEL COLD AIR STILL IN PLACE AS
PRECIPITATION FROM AN APPROACHING LOW PRESSURE SYSTEM MOVES IN
TOWARD DAYBREAK TUESDAY WE CAN ONCE AGAIN LOOK FOR SOME SLEET AND
FREEZING RAIN. THE GREATEST ICING LOOKS TO BE FROM THE NEW/ROANOKE
VALLEYS NORTH THROUGH THE GREENBRIER VALLEY AND ALLEGHANY HIGHLANDS
LATE ON TUESDAY BEFORE TEMPS WARM ABOVE FREEZING AND WE GO TO PLAIN
RAIN TUESDAY NIGHT INTO WEDNESDAY.

WEDNESDAY WILL SEE LOW PRESSURE MOVE THROUGH THE GREAT LAKES AND
PUSH A STRONG COLD FRONT THROUGH THE REGION. WE WILL SEE A GOOD DOSE
OF RAIN ALONG AND AHEAD OF THE COLD FRONT ON WEDNESDAY...THEN MORE
PRECIPITATION WEDNESDAY NIGHT AS A WAVE DEVELOPS ALONG THE FRONT AND
MOVES THROUGH THE CAROLINAS TO THE MIDDLE ATLANTIC COAST. GUIDANCE
CURRENTLY INDICATES WESTERN AREAS WILL RECEIVE MOST OF THE
PRECIPITATION WITH THE FRONT ON WEDNESDAY AND EASTERN AREAS WILL
RECEIVE MOST OF THE PRECIPITATION WITH THE WAVE WEDNESDAY NIGHT.
THIS WILL SPREAD OUT THE QPF LOAD AND HOPEFULLY WORK TO ALLEVIATE
POTENTIAL FLOODING...BUT THIS IS A VERY FINE LINE AND WE WILL HAVE
TO SEE HOW THE SITUATION DEVELOPS IN LATER MODEL RUNS. ALSO...THIS
SYSTEM IS QUITE ENERGETIC AND WILL HAVE TO BE WATCHED FOR
DEVELOPMENT OF CONVECTIVE ELEMENTS SINCE THEY MAY BE CAPABLE OF
MIXING DOWN STRONG LOW LEVEL WINDS. ADDITIONALLY...AS MUCH COLDER
AIR MOVES IN BEHIND THE FRONT ON WEDNESDAY WE WILL SEE PRECIPITATION
CHANGE OVER TO SNOW WESTERN GREENBRIER COUNTY INTO NORTHERN PORTIONS
OF THE ALLEGHANY HIGHLANDS LATE IN THE AFTERNOON.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS OF 405 PM EST SATURDAY...

THE PASSAGE OF THE COLD FRONT WILL BRING WITH IT ANOTHER SHOT OF
ARCTIC AIR THAT WILL END OUR SPRING-LIKE WEATHER FOR THE TIME BEING.
AS SUCH... EXPECT RAIN TO CHANGE TO SNOW ACROSS THE MOUNTAINS
WEDNESDAY NIGHT...WITH SNOW SHOWERS EXTENDING INTO THE PIEDMONT
EARLY THURSDAY. MODELS ARE VERY AGGRESSIVE IN WORKING THE COLDER AIR
INTO THE REGION...BUT PREFER TO BE MORE CONSERVATIVE AT THIS POINT
UNTIL WE GET CLOSER IN TIME TO THE EVENT.

PRECIPITATION WILL GRADUALLY WIND DOWN DURING THURSDAY AFTERNOON AS
THE WAVE EXITS THE AREA...AND HIGH PRESSURE BUILDS IN FROM THE WEST.
HIGH PRESSURE WILL PASS ACROSS THE AREA ON FRIDAY...RESULTING IN
LIGHT WINDS AND MOSTLY CLEAR SKIES...IN ADDITION TO AFTERNOON
TEMPERATURES IN THE 30S WEST AND THE 40S EAST.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
AS OF 600 AM EST SUNDAY...

MVFR CIGS HAVE OVERSPREAD THE REGION THIS MORNING AND EXPECT
CONTINUED LOWERING OF BASES AS MOISTURE CONTINUES TO INCREASE.
HOWEVER WHERE THERE IS LITTLE PRECIP INITIALLY...EXPECT CIGS TO
STAY HIGHER AND BE SLOWER TO DROP EARLY THIS MORNING. MAIN
CORRIDOR OF PRECIP WILL BE OVER THE SOUTH AROUND KDAN WHERE A
MIXTURE OF SLEET AND -FZRA WILL OCCUR OFF AND ON THROUGH MID
MORNING. ELSEWHERE A BIT TRICKY AS TO WHEN PRECIP WILL REACH THE
SURFACE GIVEN DRY AIR AND CURRENT SPLIT IN ECHOES ON RADAR OVER
CENTRAL SECTIONS. APPEARS SITES SUCH AS KLWB MAY SEE A PERIOD OF
SNOW/SLEET WITH MVFR VSBYS AT BOTH KLWB AND KDAN.

OTHERWISE AS THE MOISTURE ENCOUNTERS THE COLD AIR OVER THE MID
ATLANTIC...EXPECT A WINTRY MIX WITH SNOW/SLEET AT THE
ONSET...CHANGING TO FREEZING RAIN THIS MORNING. KBLF MAY ONLY SEE
PLAIN RAIN GIVEN SURFACE TEMPS SO INCLUDING LESS OF A MIXTURE
THERE. VERY LITTLE SNOW/SLEET ACCUMULATION IS
EXPECTED...HOWEVER...UPWARDS OF A TENTH OF AN INCH OF ICE
ACCRETION IS EXPECTED FROM THE FREEZING RAIN. TEMPERATURES WILL
START OFF BELOW FREEZING IN THE MORNING...THEN CREEP ABOVE
FREEZING DURING THE AFTERNOON. WARMING TEMPERATURES WILL ALSO
SIGNAL DECREASE IN VSBY DUE TO DEVELOPMENT OF FOG AND LOWERING
CIGS DUE TO THE DEVELOPMENT OF LOW LEVEL STRATUS. WIDESPREAD IFR
IS ANTICIPATED BY THIS AFTERNOON IN MOST LOCATIONS.

MODELS HAVE NOT DONE A VERY GOOD JOB WITH THE CLOUD FORECAST...SO
USING PAST EXPERIENCE WITH SIMILAR PATTERN RECOGNITION TO FORECAST
CLOUD LAYERS AND P-TYPE. IN THIS SITUATION THINK INTRODUCTION OF
LOW CLOUD WILL HOLD OFF UNTIL JUST PRIOR TO PRECIP ONSET.

POOR FLYING CONDITIONS WILL CONTINUE TONIGHT WITH RESIDUAL LOW
LEVEL MOISTURE IN PLACE AHEAD OF A COLD FRONT TO THE WEST. APPEARS
WIDESPREAD MVFR/IFR CIGS AND VSBYS LIKELY OVERNIGHT WITH ANOTHER
ROUND OF DRIZZLE...THEN AN INCREASE IN RAIN/SNOW SHOWERS WEST
ALONG AND BEHIND THE FRONT.

.EXTENDED FORECAST...
A SHARP COLD FRONT WILL CROSS THE AREA MONDAY WITH NORTHWEST
WINDS INCREASING ALONG WITH UPSLOPE MVFR CIGS/VSBYS IN SNOW
SHOWERS AT KBLF/KLWB.

ON THE HEELS OF THE SUNDAY/MONDAY SYSTEM WILL BE YET ANOTHER
POTENTIALLY POTENT SYSTEM THAT MAY IMPACT ALL OR PARTS OF THE
REGION TUESDAY INTO WEDNESDAY WITH SUB-VFR DEVELOPING IN MOST
LOCATIONS LATER TUESDAY INTO WEDNESDAY...WITH POST FRONTAL MVFR TO
IFR POSSIBLE IN RAIN/SNOW ON THURSDAY.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
     VAZ010>014-016>020-022>024-032>035-043>047-058-059.
     WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
     VAZ007-009-015.
NC...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
     NCZ003>006-019-020.
     WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
     NCZ001-002-018.
WV...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
     WVZ042>044-507-508.

&&

$$
SYNOPSIS...JH/PM
NEAR TERM...JH/KK
SHORT TERM...MBS
LONG TERM...NF
AVIATION...JH/PM