Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 060500
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1200 AM EST SAT FEB 6 2016

.SYNOPSIS...
HIGH PRESSURE WILL BUILD ACROSS THE AREA FROM THE WEST TONIGHT AND
REMAIN OVER THE REGION INTO SATURDAY NIGHT. A STORM SYSTEM
DEVELOPING OFF THE SOUTHEAST COAST SHOULD PASS WELL TO THE SOUTH
AND EAST LATER SATURDAY NIGHT INTO SUNDAY NIGHT. ANOTHER COMPLEX
AREA OF LOW PRESSURE WILL ARRIVE FROM THE NORTHWEST MONDAY
BRINGING COLDER TEMPERATURES ALONG WITH THE THREAT OF MORE WINTRY
PRECIPITATION INTO MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 920 PM EST FRIDAY...

UPDATED GRIDS STAYED FAIRLY CONSISTENT WITH THE PREVIOUS...ONLY CHANGED
OVER NIGHT MINIMUM TEMPERATURE SLIGHTLY COOLER DUE TO EXPECTED
RADIATIONAL COOLING WITH A TYPICAL DIURNAL TREND. THERE ARE SOME
HIGH THIN CLOUDS EXPECTED IN THE NORTH AND NORTH WEST REGION OF THE
FORECAST AREA. WINDS WILL STAY LIGHT FOR MOST OF THE NIGHT WITH CALM
CONDITIONS DOMINATING UNTIL JUST AFTER SUNRISE.

PREVIOUS AFD...

SHORTWAVE RIDGE AXIS WILL CROSS THE REGION TONIGHT ALLOWING FOR
DEEPENING SW FLOW ALOFT INTO SATURDAY AHEAD OF THE NEXT UPPER
LOW/TROUGH EJECTING EAST OUT OF THE SOUTHERN PLAINS. THIS SHOULD BEGIN
TO TAP HIGH LEVEL MOISTURE AHEAD OF THIS FEATURE LATER TONIGHT WITH
PERHAPS PERIODS OF THICKER MID/HIGH CANOPY BY MORNING OVER THE NORTH
AND WEST MAKING FOR CLEAR TO BECOMING PARTLY/MOSTLY CLOUDY LATE. THIS
ALSO PLAYS INTO JUST HOW COLD TO GO WITH LOWS OVERNIGHT GIVEN LOW
DEWPOINTS AND SURFACE HIGH PRESSURE SETTLING OVER AND TO THE SOUTH OF
THE AREA BY EARLY SATURDAY.

EXPECT MORE CLOUDS TO START SATURDAY BUT AGAIN MOSTLY OF THE MID/HIGH
VARIETY WITH MOISTURE POSSIBLY DECREASING DURING THE AFTERNOON AS
ENERGY STARTS TO TRANSLATE TOWARD THE SE COAST. OTRW DRY AND A BIT
WARMER UNDER AN ELONGATED AXIS OF SURFACE HIGH PRESSURE BENEATH
THE PASSING MID/HIGH DECK. THINK WITH GRADUAL WARMING ALOFT WILL
SEE HIGHS GET BACK INTO THE 40S...ALTHOUGH GIVEN LIGHT MIXING UNDER
SOME CLOUDS MAY SEE SOME SPOTS ALONG/WEST OF THE BLUE RIDGE GET STUCK
IN THE 30S UNTIL LATER IN THE DAY. THUS OPTED TO STAY SLIGHTLY
BELOW MOS THERE IN CASE THE CANOPY PERSISTS LONGER OR IS THICKER.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 250 PM EST FRIDAY...

SATURDAY NIGHT A CLOSED UPPER LOW CROSSES THE SOUTHEAST UNITED
STATES. ANOTHER UPPER LOW CLOSED OFF OVER THE UPPER MISSISSIPPI
VALLEY ON SUNDAY MORNING WHICH BOOTS THE SOUTHER STREAM SYSTEM EAST
AS IT DIGS INTO THE OHIO VALLEY MONDAY. AT THE SURFACE LOW PRESSURE
MOVES THROUGH THE GREAT LAKES ON OHIO VALLEY ON MONDAY WITH A
SECONDARY LOW DEVELOPING OVER THE MID ATLANTIC REGION...WHICH THEN
DEEPENS OFF THE COAST ON TUESDAY. ONCE THE COASTAL LOW MOVES FAR
ENOUGH NORTH AND EAST...THE SURFACE AND LOW LEVEL WINDS WILL BACK TO
THE SOUTH AND SOUTHEAST...BUT THIS MAY  TAKE UNTIL MONDAY AFTERNOON
AND EVENING. MODELS ALSO SHOWING A REGION OF GOOD UPPER DIFFLUENCE
CROSSING THE MID ATLANTIC REGION ON MONDAY.

CLOUD COVER AROUND THE COASTAL LOW WILL ADVANCE INTO THE FORECAST
AREA SUNDAY MORNING...WITH A MAJORITY OF THE MORE WIDESPREAD CLOUD
COVER IN THE EAST. THIS MAY KEEP THE MAXIMUM TEMPERATURES A COUPLE
OF DEGREES LOWER THAN FORECAST SUNDAY.  MORE CLOUDS WILL ARRIVE FROM
THE WEST AHEAD OF THE NORTHERN STREAM SYSTEM SUNDAY NIGHT. GFS IS
SLIGHTLY FASTER WITH BRINGING THE DEEPER MOISTURE IN THE WEST ON
MONDAY COMPARED TO THE NAM...BUT NOT ENOUGH TO NEED A CHANGE IN THE
PROBABILITY OF PRECIPITATION FOR MONDAY. NAM...GFS AND GEFS ALL
TRENDING TOWARD 0.10 TO 0.50 INCHES LIQUID EQUIVALENT FOR MONDAY AND
MONDAY NIGHT...WITH THE HIGHER AMOUNTS ACROSS THE FAR NORTHERN
COUNTY WARNING AREA.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 250 PM EST FRIDAY...

SIGNIFICANT LOWERING OF HEIGHTS AND TEMPERATURES BY TUESDAY...WITH
EASTERN 500 MB LONG WAVE TROF BEING RE-ENFORCED BY ANOTHER SHORT
WAVE ON WEDNESDAY. THE TROF AXIS MOVES EAST...HEIGHTS RISE...AND
TEMPERATURES MODERATE WEDNESDAY NIGHT AND THURSDAY. EXPECTING LONG
FETCH OF NORTHWEST FLOW...THAT MAY EVEN TAP MOISTURE FROM THE ONLY
PARTIALLY FROZEN GREAT LAKES TUESDAY NIGHT AND WEDNESDAY.
QUESTIONABLE IF THE WESTERN UPSLOPE WILL CONTINUE PAST WEDNESDAY
NIGHT SINCE SURFACE TO 850 MB WINDS BECOME MORE WEST BY THAT TIME.

COLD 850 MB AIR WITH THE EASTERN TROF REACHES THE FORECAST AREA ON
TUESDAY NIGHT AND WEDNESDAY...POTENTIALLY BOTTOMING OUT AROUND -18
BY WEDNESDAY NIGHT. WILL HIGHLIGHT POTENTIAL LOW WIND CHILL VALUES
AT HIGHER ELEVATIONS IN THE FAR WESTERN COUNTY WARNING AREA IN THE
HAZARDOUS WEATHER OUTLOOK.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 1150 PM EST FRIDAY...

VFR CONDITIONS EXPECTED THROUGH THE TAF VALID PERIOD WITH A VERY
DRY AIR MASS AND WEAK HIGH PRESSURE ACROSS THE REGION THROUGH THE
TAF VALID PERIOD. AN UPPER LOW TRACKING THROUGH THE SOUTHERN
STATES WILL SPREAD INCREASING CIRRUS THROUGH THE REGION FROM THE
WEST AND SOUTHWEST THROUGH THE PERIOD. CIGS WILL REMAIN AT OR
ABOVE 150 THROUGH THE TAF VALID PERIOD. NO RESTRICTIONS TO
VISIBILITY ARE EXPECTED.

WINDS WILL BE CHAOTIC AND LIGHT...TRENDING TOWARD MOSTLY CALM AT
NIGHT AND VARIABLE 3-6KTS DURING THE DAYLIGHT HOURS. IF ANY
TENDENCY IN THE DIRECTION CAN BE ASCERTAINED...IT WOULD BE TOWARD
THE SW-WSW.

HIGH CONFIDENCE IN VFR CIGS AND VSBYS THROUGH THE TAF VALID
PERIOD.
MEDIUM CONFIDENCE IN WIND DIRECTION THROUGH THE TAF VALID PERIOD.
HIGH CONFIDENCE IN WIND SPEED THROUGH THE TAF VALID PERIOD.

EXTENDED DISCUSSION...

VFR CONDITIONS WILL CONTINUE INTO SUNDAY AS AN UPPER LOW REMAINS
WELL SOUTHEAST OF THE REGION. AS WE MOVE INTO NEXT WEEK...A
STRONG UPPER AREA OF LOW PRESSURE WILL SINK SOUTHWARD FROM THE
GREAT LAKES BY MONDAY LEADING TO OVERALL MVFR CONDITIONS ACROSS
MOST TAF SITES. AN ASSOCIATED COLD FRONT PASSES THROUGH MONDAY
NIGHT FOLLOWED BY A SECONDARY ARCTIC BOUNDARY TUESDAY EVENING.
THESE SHOULD COMBINE TO KEEP SUB-VFR OVER THE MOUNTAINS WITH
LOWER CEILINGS CONTINUING WITH THE PRESENCE OF SNOW SHOWERS MONDAY
NIGHT...CONTINUING THROUGH WEDNESDAY AS A STRONG UPSLOPE FLOW
PATTERN KICKS IN. A MIX OF MVFR/VFR EXPECTED AT TIMES IN THE EAST
WITH DOWNSLOPE LIMITING CLOUD COVER FOR TUESDAY INTO WEDNESDAY.
SOME ALBERTA CLIPPERS WILL BE TRACKING THROUGH THE BASE OF THE
UPPER TROUGH...WHICH COULD BRING SNOW SHOWERS AND LIGHT SNOW TO
AREAS FURTHER EAST OF THE ALLEGHANYS AT TIMES.

&&

.HYDROLOGY...
AS OF 240 PM EST FRIDAY...

MINOR FLOODING CONTINUES AT SOUTH BOSTON ON THE DAN RIVER. THE RIVER HAS
CRESTED AND WILL BE DROPPING BELOW FLOOD STAGE EARLY SATURDAY. SEE THE
LATEST WBCFLSRNK PRODUCT FOR ADDED DETAILS.

&&

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

&&

$$
SYNOPSIS...JH
NEAR TERM...JH/MBS
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...JH/JM/RAB
HYDROLOGY...JH


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