Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 182001
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
401 PM EDT SAT OCT 18 2014

.SYNOPSIS...
A COLD FRONT CROSSING THE AREA THIS AFTERNOON WILL PUSH EAST OF
THE AREA TONIGHT...BRINGING RAIN SHOWERS TO THE MOUNTAINS THROUGH
THE EARLY MORNING HOURS OF SUNDAY. HIGH PRESSURE WILL BUILD IN
SUNDAY AFTERNOON AND EVENING...BRINGING CLEARING CONDITIONS. ON
MONDAY AND TUESDAY LOW PRESSURE WILL TRACK FROM THE GREAT LAKES TO
OFF THE VIRGINIA COAST.

&&

.NEAR TERM /THROUGH SUNDAY/...
AS OF 345 PM EDT SATURDAY...

A REINFORCING COLD FRONT IS MAKING ITS WAY ACROSS THE MOUNTAINS
THIS AFTERNOON...AND WILL CONTINUE SOUTHEAST THROUGH THE EVENING.
WHILE WINDS ACROSS THE FORECAST REGION ARE ALREADY FROM THE
NORTHWEST...THE COLD FRONT IS BRINGING WITH IT SHOWER ACTIVITY
WHICH WILL AFFECT OUR WESTERN RIDGES THROUGH THE AFTERNOON AND
EVENING. CURRENTLY KEEPING AN EYE ON A SLUG OF MOISTURE THAT THE
NORTHWEST FLOW HAS PICKED UP FROM LAKE MICHIGAN...WHICH RAPID
UPDATE MODELS ARE IN GOOD AGREEMENT WILL MAKE IT TO OUR WESTERN
RIDGES LATE THIS EVENING. AS A RESULT...HAVE INCREASE THE RAIN
CHANCES ACROSS THE MOUNTAINS TO ADD LIKELY WORDING TO THE FORECAST
FOR THE 10 PM TO 3 AM TIMEFRAME...WITH THE HIGHEST CHANCES LOCATED
IN WESTERN GREENBRIER COUNTY.

ASIDE FROM PRECIPITATION...HIGH PRESSURE BUILDING IN FROM THE WEST
HAS TIGHTENED THE PRESSURE GRADIENT ENOUGH TO SUPPORT 20 TO 25 MPH
GUSTS FOR MUCH OF THE AREA. WINDS WILL GRADUALLY DIMINISH IN SPEED
THROUGH THE EVENING AS THE PRESSURE GRADIENT RELAXES. CLOUD COVER
IS WIDESPREAD ACROSS THE MOUNTAINS THIS AFTERNOON...TAPERING DOWN
TO MOSTLY/PARTLY CLOUDY SKIES ACROSS THE SOUTHSIDE AS CLOUDS
BREAK UP IN THE DOWNSLOPE FLOW. EXPECT LITTLE CHANGE IN CLOUD
COVER THROUGH EARLY SUNDAY. THE INCREASED CLOUDS WILL KEEP
RADIATIONAL COOLING TO A MINIMUM...AND THEREFORE EXPECT WINDS TO
REMAIN A LITTLE GUSTY THROUGH THE NIGHT...MAINLY FOR THE
MOUNTAINS. NORTHWESTERLY FLOW WILL ALSO CARRY COLDER AIR INTO THE
REGION OVERNIGHT...WITH TEMPERATURES APPROACHING FREEZING IN
WESTERN GREENBRIER COUNTY. MAY SEE A FEW SNOWFLAKES MIXED IN WITH
WHATEVER RAIN SHOWERS ARE LEFT THERE TOWARD DAWN...HOWEVER NO
ACCUMULATIONS ARE EXPECTED.

SHOWER ACTIVITY WILL DIMINISH THROUGH THE NIGHT...WITH CLOUDS
DECREASING FROM EAST TO WEST AS HIGH PRESSURE BEGINS TO SETTLE
ACROSS THE AREA. AS SUCH...LOOKING FOR MOSTLY CLEAR SKIES ACROSS
THE PIEDMONT FOR SUNDAY AFTERNOON...WITH A MIXTURE OF CLOUDS AND
SUNSHINE ACROSS THE MOUNTAINS. EXPECT HIGHS TO RANGE FROM THE
LOW/MID 50S ACROSS THE MOUNTAINS...TO THE MID 60S ACROSS THE
SOUTHSIDE.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
AS OF 230 PM EDT SATURDAY...

SUNDAY NIGHT INTO MONDAY...THE CENTER OF THE SURFACE HIGH SHIFTS TO
OUR EAST ALL WHILE SOUTHWEST FLOW INCREASES AT 850 MB AND HIGHER.
WHILE WE ARE EXPECTING ONE OF THE COLDEST NIGHTS SO FAR OF THE
SEASON FOR MOST AREA...THE THE ABOVE SCENARIO IS GOING TO MITIGATE
THE EXTENT OF THE COOL DOWN. IT MAY BE ONE OF THOSE SITUATIONS WHERE
THE RIDGE TOPS STAY MILDER THAN THE VALLEYS THANKS TO CONTINUED
MIXING OF WINDS AT THE HIGHER ELEVATIONS...AND THE ELEVATIONS
THEMSELVES COULD BE HIGHER THAN THE TOP OF THE NOCTURNAL INVERSION.
ACROSS THE PIEDMONT...THIS AREA WILL BE STILL CLOSEST TO THE CENTER
OF THE DEPARTING SURFACE HIGH...AND WINDS ALOFT WILL BE
WEAKER...PLUS HAVE LESS OF A CHANCE TO MIX TO THE SURFACE GIVEN A
MORE LAMINAR FLOW LOFT SANS STEEPER TOPOGRAPHY.

FORECAST LOWS ACROSS THE MOUNTAINS WILL RANGE FROM THE UPPER 20S IN
THE DEEPER VALLEYS TO NEARLY 40 DEGREES AT THE RIDGE TOPS. IN
BETWEEN THESE EXTREMES IS THE POTENTIAL FOR AREAS WHERE TEMPERATURES
ARE COLD ENOUGH AND WINDS ARE LIGHT ENOUGH FOR FROST FORMATION.
LIKEWISE...SOME LOCATIONS WILL EXPERIENCE FREEZING TEMPERATURES IN
THE LOWER 30S TO NEAR 30 DEGREES. A PATCHWORK OF FROST POSSIBILITIES
STILL DOTS MY FORECAST MAP. OUR HAZARDOUS WEATHER OUTLOOK WILL STILL
MENTION THIS POTENTIAL LATE SUNDAY NIGHT INTO EARLY MONDAY MORNING.
WE ARE STILL TO FAR AWAY IN THE FORECAST PACKAGE FOR THE POSTING OF
ANY FROST ADVISORIES AT THIS TIME. HOWEVER...ENOUGH OF GREENBRIER
COUNTY...BOTH WESTERN AND EASTERN SECTIONS...ARE FORECAST TO REACH
LOWS AT OR BELOW FREEZING SUNDAY NIGHT THAT A FREEZE WATCH WILL BE
ISSUED THIS AFTERNOON TO ACCOUNT FOR THAT POTENTIAL.

EAST OF THE BLUE RIDGE...THE FORECAST WILL REFLECT NO LOCATIONS
FORECAST AT OR BELOW FREEZING FOR LOW TEMPERATURES. HOWEVER...PATCHY
FROST STILL IS POSSIBLE WITHIN A CORRIDOR BETWEEN ROUGHLY
AMHERST...BEDFORD AND MARTINSVILLE VA. THERE IS LESS CONFIDENCE THAT
A FROST ADVISORY MAY EVENTUALLY BE POSTED IN THIS AREA GIVEN THE
MORE PATCHY NATURE OF THE FROST. HOWEVER...CONFIDENCE IN THE PATCHY
FROST IS STILL HIGH ENOUGH TO CONTINUE TO MENTION IT IN THE
HAZARDOUS WEATHER OUTLOOK.

BY THE LATE MORNING MONDAY...SOUTHWEST WINDS WILL HAVE MIXED NICELY
TO THE SURFACE TO HELP START THE PROCESS OF MODERATING TEMPERATURES.
ANY FROST IS UNLIKELY TO SURVIVE PAST ROUGHLY 900 AM. TEMPERATURES
WILL CONTINUE TO INCREASE TO THE LOW TO MID 60S IN THE MOUNTAIN AND
MID TO UPPER 60S ACROSS THE PIEDMONT. CLOUDS WILL START TO INCREASE
DURING THE AFTERNOON IN THE WEST IN ADVANCE OF THE NEXT APPROACHING
UPPER LEVEL TROUGH. WE CANNOT RULE OUT SOME ISOLATED SHOWERS BY
SUNSET ALONG AND EAST OF INTERSTATE 64 IN SOUTHEAST WEST VIRGINIA AND
SOUTHWEST VIRGINIA.

MONDAY NIGHT INTO TUESDAY NIGHT THE AXIS OF A DEEPENING UPPER TROUGH
WILL MOVE INTO AND THROUGH OUR REGION. THE RESULT WILL BE AN
INCREASE IN SHOWER ACTIVITY ACROSS THE ENTIRE AREA BY TUESDAY
AFTERNOON...WITH THE GREATEST POTENTIAL ACROSS THE PREFERRED UPSLOPE
REGIONS IN THE WESTERN PART OF THE FORECAST AREA. BY TUESDAY
NIGHT...MOST OF THE PRECIPITATION THAT REMAINS WILL BE CONFINED TO
THE UPSLOPE AREAS IN THE WEST...BUT BE DECREASING IN COVERAGE. EARLY
TUESDAY EVENING...THERE STILL WILL BE A CHANCE OF SHOWERS ACROSS THE
NORTHEAST PART OF THE REGION ON THE BACKSIDE OF THE CENTER OF THE
DEPARTING UPPER LOW.

TEMPERATURES DURING THIS PORTION OF THE FORECAST WILL TREND MILDER
THROUGH TUESDAY...BUT START TO SLIDE A BIT TUESDAY NIGHT ON THE WEST
SIDE OF THE DEPARTING UPPER LOW.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 245 PM EDT SATURDAY...

WEDNESDAY THROUGH THURSDAY...THE SLOWLY DEPARTING UPPER LOW WILL
CONTINUE TO DO JUST THAT...SLOWLY DEPART. THIS PATTERN WILL MAINTAIN
A GUSTY NORTHWEST FLOW ALOFT ACROSS THE AREA THAT WILL MAINTAIN SOME
CLOUD COVER AND ISOLATED SHOWERS OVER WESTERN PARTS OF SOUTHEAST
WEST VIRGINIA. THE REMAINDER OF THE AREA SHOULD EXPERIENCE LIMITED
CLOUD COVER...NEAR NORMAL TEMPERATURES...AND WINDS A BIT ON THE
GUSTY SIDE.

FRIDAY INTO SATURDAY...THE LOW DEPARTS FAR ENOUGH EAST THAT OUR
PREVAILING FLOW BECOMES NORTHERLY...THUS SHUTTING OFF THE UPSLOPE
MACHINE. A BROAD UPPER RIDGE BECOMES POSITIONED ACROSS THE MID-
MISSISSIPPI VALLEY AND BUILDS SLIGHTLY EASTWARD. DRY
CONDITIONS...LIMITED CLOUD COVER...MODERATING TEMPERATURES...AND
STILL A BIT OF A NORTH BREEZE WILL BE THE FORECAST FOR THE REGION.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
AS OF 200 PM EDT SATURDAY...

OBSERVING GUSTY NORTHWEST WINDS THIS AFTERNOON AS ONE COLD FRONT
HAS ALREADY PASSED ACROSS THE AREA. STRONGEST GUSTS ARE FOUND
ACROSS THE PIEDMONT...OCCASIONALLY TOPPING 20KT...WITH SPEEDS
TAPERING DOWN TO LESS THAN 10KT ALONG THE WESTERN RIDGES...WHERE
A SECOND COLD FRONT IS ENTERING THIS AFTERNOON. CEILINGS RANGING
2-4KFT ARE WIDESPREAD ACROSS THE MOUNTAINS...BECOMING HIGHER AND
INCREASINGLY SCATTERED EAST OF THE BLUE RIDGE.

THE COLD FRONT WILL CONTINUE TO PASS SOUTHEAST ACROSS THE AREA
THIS AFTERNOON...TRIGGERING UPSLOPE SHOWERS ALONG THE WESTERN
RIDGES. MOST LIKELY TO BE IMPACTED WITH RAINFALL WILL BE
KBLF/KLWB...AND KBCB LATER THIS EVENING. THE NORTHWESTERLY FLOW
HAS PICKED UP A SLUG OF MOISTURE FROM LAKE MICHIGAN...WHICH RAPID
UPDATE MODELS INDICATE WILL ARRIVE IN OUR AREA SHORTLY BEFORE
MIDNIGHT...AND INCREASE THE COVERAGE OF SHOWER ACTIVITY ACROSS THE
MOUNTAINS OVERNIGHT. TEMPERATURES WILL BECOME COLD ENOUGH TOWARD
DAWN THAT A FEW SNOW FLAKES WILL BE POSSIBLE AT THE TAIL END OF
THE SHOWER ACTIVITY FOR KLWB...HOWEVER NO ACCUMULATIONS ARE
EXPECTED.

IFR CEILINGS WILL BECOME WIDESPREAD ACROSS THE MOUNTAINS OVERNIGHT...
BUT WILL BREAK UP FURTHER EAST IN THE DOWNSLOPE FLOW. RAINSHOWERS
WILL ALSO LOWER VISIBILITIES FOR EXTENDED PERIODS OF TIME. TOWARD
DAWN...SHOWER ACTIVITY WILL DIMINISH AND LOW LEVEL MOISTURE WILL
BECOME INCREASINGLY SHALLOW FROM EAST TO WEST...ALLOWING CEILINGS
TO GRADUALLY BREAK UP DURING THE REMAINDER OF THE MORNING. EXPECT
VFR TO RETURN BY LATE SUNDAY MORNING FOR KROA AND POSSIBLY
KBCB...HOWEVER KBLF/KLWB WILL REMAIN AT LEAST LOW MVFR INTO SUNDAY
AFTERNOON.

MEDIUM TO HIGH CONFIDENCE IN CIG THROUGH THE TAF VALID PERIOD.
HIGH CONFIDENCE IN VSBYS THROUGH THE TAF VALID PERIOD. HIGH
CONFIDENCE IN WIND DIR/SPD THROUGH THE TAF VALID PERIOD.

EXTENDED AVIATION DISCUSSION...

VFR CONDITIONS ARE EXPECTED SUNDAY EVENING INTO MONDAY. ANOTHER
UPPER LOW WILL SETTLE INTO THE REGION FROM THE NORTH LATE MONDAY AND
LINGER THROUGH MID-WEEK WITH SCT -SHRA AND MOSTLY MVFR CEILINGS AND
BRIEF PERIODS OF MVFR VISIBILITIES IN -SHRA. IMPROVING CONDITIONS
ARE EXPECTED TOWARD THE VERY END OF THE WEEK.

&&

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

&&

$$
SYNOPSIS...NF
NEAR TERM...NF
SHORT TERM...DS
LONG TERM...
AVIATION...NF/RAB



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