Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 021430
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
930 AM EST MON MAR 2 2015

.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO MOVE EAST AND OFF THE COAST THIS
MORNING. HIGH PRESSURE WILL FOLLOW BEHIND THE FRONT...CROSSING THE
OHIO VALLEY TONIGHT AND EXTENDING SOUTH INTO THE MID ATLANTIC
REGION TONIGHT. A LOW PRESSURE SYSTEM OVER THE CENTRAL PLAINS ON
TUESDAY WILL MOVE NORTHEAST AND WILL PUSH A STRONG COLD FRONT
THROUGH OUR AREA ON WEDNESDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM EST MONDAY...

A COLD FRONT MOVING EAST ACROSS THE REGION THIS MORNING. IN THE
WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO OUR REGION THIS
AFTERNOON INTO TONIGHT. WSR-88D SHOWED A FEW NARROW BANDS OF SNOW
AND RAIN DIMINISHING THIS MORNING. MADE A QUICK UPDATE TO DIMINISHPOPS
THIS MORNING WITH DRY AIR PUNCH AND DOWNSLOPING EFFECT. LEANED
POPS TOWARDS RNK WRF-ARW FOR NEXT COUPLE OF HOURS. MODIFIED
TEMPERATURES FOR THIS MORNING INTO THIS AFTERNOON ACCORDING TO SFC
OBS AND MODEL TRENDS.



AS OF 500 AM EST MONDAY...

A COLD FRONT COMES THROUGH THE MORNING AND WILL BE EAST OF THE
FORECAST AREA BY NOON. MODELS HOLD A MAJORITY OF THE PRECIPITATION
ALONG AND AHEAD OF THE FRONT IN THE FAR WESTERN COUNTY WARNING AREA
THIS MORNING. PUSH OF DRIER AIR BEHIND THE FRONT WILL BE ENOUGH
TO END CHANCE OF PRECIPITATION AND CLEAR OUR MUCH OF THE FOG AND
CLOUD COVER THIS AFTERNOON. HIGH PRESSURE MOVES ACROSS THE OHIO
VALLEY TODAY AND WEDGES DOWN THE EAST SLOPES OF THE APPALACHIANS
TONIGHT.

850 MB WINDS BEHIND THE FRONT WILL BE 45 TO 55 KNOTS WITH PRESSURE
RISES 5 TO 7 MB/6 HOURS THIS MORNING. WILL HAVE WINDS GUSTING JUST
BELOW ADVISORY LEVEL...UP TO 50 MPH THIS MORNING. WINDS DIMINISH
THIS AFTERNOON AND THE TURN TO THE EAST THEN SOUTHEAST TONIGHT AS
THE WEDGE BECOMES ESTABLISHED. THE EAST TO SOUTHEAST WINDS WILL
BRING LOW LEVEL MOISTURE BACK NORTH ALONG THE BLUE RIDGE AND EASTERN
SLOPES OVERNIGHT.

COLDER AIR COMES IN BEHIND THE FRONT TODAY...BUT WITH SHRINKING
AREAL COVERAGE OF PRECIPITATION AND SOME SUN IN THE
AFTERNOON...TEMPERATURES WILL HOLD STEADY OR SLOWLY RISE. AS WIND
DROPS OFF THIS EVENING...TEMPERATURES WILL COOL BUT AS CLOUD FILL
BACK IN LATE TONIGHT DROP IN TEMPERATURES WILL BE LIMITED.

HAVE ADDED PATCHY DRIZZLE AND FREEZING DRIZZLE AFTER MIDNIGHT FOR
THE TYPICAL UPSLOPE AREA ALONG AND EAST OF THE SOUTHERN BLUE
RIDGE. BUFKIT SHOWED A WARM NOSE AROUND 3000 FT AGL AND SURFACE
TEMPERATURES DROPPING BELOW FREEZING.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
AS OF 500 AM EST MONDAY...

WE WILL START OUT TUESDAY DEALING WITH ANOTHER WEDGE SITUATION
SIMILAR TO WHAT WE JUST WENT THROUGH ON SUNDAY...BUT WITH MORE
SYNOPTIC PRECIPITATION TO DEAL WITH. COLD HIGH PRESSURE WEDGES DOWN
THE EASTERN SEABOARD WILL GET OVER RUN BY MUCH WARMER AIR AHEAD OF
AN APPROACHING COLD FRONT FROM THE WEST. SOUNDINGS ON BUFKIT SHOW
THE DEPTH OF THE COLD AIR IN THE BOUNDARY LAYER TO BE SUBSTANTIALLY
DEEP AND COLD AT THE ONSET OF PRECIPITATION. THIS WILL FAVOR SOME
SLEET AND HELP KEEP DOWN ICING ACCUMULATIONS FROM FREEZING RAIN AS
PRECIPITATION MOVES IN. AS IS TYPICALLY THE CASE...THE WARMER AIR
WILL MOVE IN FROM THE SOUTHWEST WITH GOOD WARMING AND THE LEAST
POTENTIAL FOR ICING FROM THE MOUNTAIN EMPIRE AND GRAYSON HIGHLANDS
OF VA INTO THE NW MOUNTAINS OF NC. EXPECTING THE WARMER AIR TO
INTRUDE INTO THE NEW RIVER AND ROANOKE VALLEYS DURING THE
AFTERNOON...BUT THE COLD AIR WILL MODERATE ONLY SLOWLY ACROSS THE
GREENBRIER VALLEY...ALLEGHANY HIGHLANDS...AND PIEDMONTS OF NC/VA.
HOWEVER...EVEN THIS SLIGHT TEMPERATURE MODERATION SHOULD BE ENOUGH
TO END THE THREAT OF FREEZING RAIN FOR THE VAST MAJORITY OF THE AREA
BY MID TO LATE AFTERNOON WITH TEMPS IN THE LOW TO MID 30S.

RAIN WILL CONTINUE ACROSS THE REGION AS THE FRONT APPROACHES TUESDAY
NIGHT BEFORE IT MOVES THROUGH ON WEDNESDAY. BASED ON THE LATEST QPF
FORECASTS AND EXPECTED SNOW MELT...CURRENT HYDROLOGIC MODELS DO NOT
INDICATE A SIGNIFICANT RIVER FLOOD THREAT BUT SMALLER STREAMS AND
CREEKS ARE STILL A CONCERN. HOWEVER...CONSENSUS TIMING OF THE
FRONTAL PASSAGE IS NOT CLEAR CUT AND BELIEVE IT BEST TO WAIT FOR
LATER MODEL RUNS BEFORE DECIDING IF ANY HYDRO WATCHES ARE NEEDED.

AS COLDER AIR MOVES IN BEHIND THE FRONT ON BLUSTERY NORTHWEST WINDS
CONDITIONS APPEAR FAVORABLE FOR A BURST OF SNOW AS THE COLD AIR
CATCHES UP TO THE BACK EDGE OF PRECIPITATION STARTING ON WEDNESDAY
NIGHT AND CONTINUING INTO THURSDAY AS A WAVE OF LOW PRESSURE
DEVELOPS ALONG THE FRONT. IT LOOKS TO BE A FINE LINE BETWEEN WHERE
THE AIR TEMPERATURES WILL SUPPORT SNOW AND WHERE THE HIGHEST
PRECIPITATION WILL BE. THE MOST LIKELY LOCATION TO RECEIVE SEVERAL
INCHES OF WET SNOW CURRENTLY APPEARS TO BE 30 MILES OR SO EITHER
SIDE OF THE BLUE RIDGE...BUT THIS WILL LIKELY CHANGE AS THE
SITUATION DEVELOPS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
AS OF 130 PM EST SUNDAY...

THURSDAY NIGHT...SOME LINGERING SNOW SHOWER WILL STILL BE POSSIBLE
EAST OF THE BLUE RIDGE. HOWEVER...BY MIDNIGHT...PRECIPITATION IS
EXPECTED TO COME TO AN END...AND CLOUD COVER ACROSS THE ENTIRE
REGION WILL TREND FROM CLOUDY TO PARTLY CLOUDY THROUGH THE NIGHT.
LOW TEMPERATURES WILL RANGE FROM THE SINGLE DIGITS TO THE LOWER
TEENS ACROSS THE MOUNTAINS WITH MID TO UPPER TEENS ACROSS THE
PIEDMONT.

FRIDAY INTO SATURDAY...A BROAD AREA OF HIGH PRESSURE IS EXPECTED TO
BUILD INTO...OVER...AND THEN EAST OF THE AREA. THIS WILL HAVE THE
IMPACT TO KEEP OUR REGION PRECIPITATION FREE WITH A TREND FROM
COLDER CONDITIONS TO MILDER CONDITIONS AS WE START GETTING ON THE
RETURN SIDE SW-W FLOW OF THE HIGH BY SATURDAY AFTERNOON. THE TREND
WILL CONTINUE INTO SUNDAY WITH NO PRECIPITATION AND EVEN MILDER
CONDITIONS AS A TROUGH DEEPENS IN THE CENTRAL U.S. AND A SHORTWAVE
RIDGE ALOFT BUILDS OVER THE REGION.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
AS OF 655 AM EST MONDAY...

TAF PERIOD STARTS WITH IFR TO MVFR CEILINGS ALONG A COLD FRONT
THAT WAS CROSSING THROUGH THE AREA. SCATTERED LIGHT RAIN WAS OVER
SOUTHWEST VIRGINIA AND LIGHT FREEZING RAIN...POSSIBLY MIXED WITH
SNOW WAS OVER SOUTHEAST WEST VIRGINIA. KLWB AND KBLF MAY HAVE -SN
BEFORE 14Z/9AM. KBCB MAY HAVE -RA EARLY THIS MORNING.

THE FRONT WILL BE EAST OF KLYH AND KDAN BY NOON TODAY. DRIER AIR
COMES INTO THE REGION BEHIND THE FRONT. HIGH CONFIDENCE THAT
CONDITIONS WILL IMPROVE TO VFR BY 21Z/4PM.

HIGH PRESSURE WILL ONE AGAIN WEDGE DOWN THE EAST SLOPES OF THE
APPALACHIANS TONIGHT. AS SURFACE AND LOW LEVEL WINDS TURN TO THE
EAST AND SOUTHWEST...LOW LEVEL MOISTURE WILL RETURN NORTH ALONG
THE SOUTHERN  BLUE RIDGE. HIGH CONFIDENCE OF CEILINGS LOWERING TO
MVFR AT KBCB AND KDAN AFTER 06Z/1AM. MEDIUM CONFIDENCE OF
OCCURRENCE OF LIGHT RAIN OR DRIZZLE AND FOG...ESPECIALLY ALONG THE
BLUE RIDGE.

HAVE ADDED SOME LLWS FOR THIS MORNING DUE TO A 45 TO 55 KNOT LOW
LEVEL JET. AS THE FRONT GOES THROUGH AND MIXING BEGINS...EXPECT
WIND GUSTS AS HIGH AS 30 KNOTS THIS MORNING. WINDS WILL DIMINISH
QUICKLY THIS AFTERNOON AND EVENING AS HIGH PRESSURE BUILDS IN.

EXTENDED FORECAST...

ANOTHER LOW PRESSURE SYSTEM THAT WILL IMPACT ALL OF THE REGION
WILL TRACK FROM THE CENTRAL PLAINS ON TUESDAY INTO NEW ENGLAND ON
WEDNESDAY. THIS WILL RESULT IN SUB-VFR CONDITIONS WEDNESDAY AND
THURSDAY WITH WIDESPREAD RAIN AHEAD OF THE FRONT ON WEDNESDAY AND
WINTER PRECIPITATION BEHIND THE FRONT WEDNESDAY NIGHT AND
THURSDAY.

FRIDAY SHOULD SEE A RETURN TO HIGH PRESSURE AND VFR WEATHER.

&&

.HYDROLOGY...
AS OF 500 AM EST MONDAY...

CONCERN FOR HAS BEEN POTENTIAL COMBINATION OF SNOW MELT AND HEAVY
RAINFALL ACROSS THE GREENBRIER...UPPER JAMES RIVER BASINS WHERE
UP TO TWO FEET OF SNOW HAS FALLEN DURING THE PAST COUPLE OF WEEKS.

SOME MELTING HAS OCCURRED AND MORE IS EXPECTED TODAY AND TUESDAY.
FORECAST RAIN AMOUNTS ON TUESDAY NIGHT AND WEDNESDAY MAY REACH 1.5
INCHES. THE COMBINATION OF SNOW MELT AND THIS MODERATE TO HEAVY
RAINFALL MAY RESULT IN MINOR RISES ON AREA CREEKS AND STREAMS.
MAJOR FLOODING IS NOT ANTICIPATED AT THIS TIME.

THE NEXT WAVE OF HEAVIER PRECIPITATION SHOULD TRACK ACROSS THE
PIEDMONT...WHERE THERE IS LITTLE TO NO SNOWPACK OF CONCERN. ONE
OTHER ISSUE MIGHT BE POTENTIAL ICE JAMS ON LOCAL STREAMS AND
RIVERS...GIVEN THE FACT THAT MUCH OF THE LAST THREE WEEKS HAVE
BEEN WELL BELOW FREEZING...WITH MANY DAYS BELOW 20. THIS COULD
RESULT IN MORE EXTENSIVE FLOODING IN CERTAIN SPOTS AND WILL NEED
TO BE MONITORED.

&&

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

&&

$$
SYNOPSIS...AMS
NEAR TERM...AMS/KK
SHORT TERM...MBS
LONG TERM...DS
AVIATION...AMS/PM
HYDROLOGY...AMS/RAB



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