Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 200813
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
413 AM EDT SAT SEP 20 2014

.SYNOPSIS...
HIGH PRESSURE WILL WEDGE SOUTH ALONG THE EASTERN SLOPES OF THE
APPALACHIANS TODAY. A PIECE OF THIS HIGH WILL BREAK OFF OVER THE
TENNESSEE VALLEY ON SUNDAY AS A COLD FRONT CROSSES THE REGION FROM
THE WEST...AND LOW PRESSURE MOVES UP THE SOUTHEAST COAST. MONDAY
THROUGH THURSDAY...A LARGE HIGH PRESSURE SYSTEM WILL COVER MUCH OF
THE EASTERN UNITED STATES.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 400 AM EDT SATURDAY...

RADAR PICKING UP SOME PATCHES OF LIGHT RAIN EARLY THIS MORNING
FROM CARROLL COUNTY INTO THE NORTHWEST NORTH CAROLINA MOUNTAINS.
SEVERAL OBSERVATIONS ALSO REPORTING PATCHY FOG. SATELLITE PICTURES
SHOWED A BAND OF CLOUDS ALONG THE APPALACHIANS FROM EASTERN NEW
YORK INTO NORTHEAST GEORGIA. THESE CLOUDS ALIGNS WITH HIGH
PRESSURE WEDGED DOWN THE APPALACHIANS.

BUFKIT DATA HAD FOG AND DRIZZLE ENDING AND CLOUDS BECOMING
SCATTERED IN MOST LOCATIONS...WITH UPSLOPE COMPONENT
ENDING BY LATE MORNING. LITTLE ADDITIONAL CLOUD COVER EXPECTED
THIS AFTERNOON.

SURFACE LOW PRESSURE OFF THE COAST WILL BE OFF THE NORTH CAROLINA
COAST BY SUNDAY MORNING. THE SWIRL OF CLOUDS AROUND THIS LOW MAY
REACH THE FAR SOUTHEAST COUNTY WARNING AREA TONIGHT. BETWEEN THE
NORTHEAST SURFACE WINDS AROUND THE COASTAL LOW AND THE SOUTHWEST
WINDS AHEAD OF THE COLD FRONT...LOOKING FOR LITTLE TO NO LOW
LEVEL CONVERGENCE. PRECIPITABLE WATER VALUES DROP BELOW ONE INCH
TONIGHT.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM EDT SATURDAY...

MODELS HAVE BEEN CONSISTENT OVER THE LAST 24 HOURS TAKING A GULF
STREAM DISTURBANCE ALONG THE NC/VA SHORE SUNDAY MORNING TO OFF THE
NEW ENGLAND COAST SUNDAY NIGHT. WITH THIS DISTURBANCE OUT OF THE
WAY...A COLD FRONT WILL CROSS OVER THE REGION DURING THE DAY SUNDAY.
THIS STRONG FAST-MOVING FALL FRONT WILL BE PUSHED BY AN UPPER LEVEL
TROUGH TRACKING OVER THE GREAT LAKES SUNDAY. THIS FRONT AND
ASSOCIATED SHOWERS IS EXPECTED TO MOVE OVER THE AREA SUNDAY
AFTERNOON...EXITING THE PIEDMONT DURING THE EARLY EVENING. THERE IS
A POSSIBILITY THIS FRONT WILL SLOW DOWN EAST OF THE BLUE RIDGE AS A
SIGNIFICANT SHORT WAVE IS ON THE WESTERN FLANK OF THE TROUGH. ONCE
THIS SHORT WAVE ROUNDS THE BASE OF THE TROUGH IN THE OHIO
VALLEY...ANY CONVECTION WILL BE WELL EAST OF THE AREA. THIS SHORT
WAVE WILL THEN USE ANY AVAILABLE MOISTURE TO BRING RAIN/DRIZZLE TO
WESTERN SLOPES SUNDAY NIGHT INTO MONDAY MORNING.

THE BULK OF THE RAINFALL WILL ACCOMPANY THE FRONT SUNDAY. WINDS
ALOFT WILL ALREADY BE OUT OF THE WEST...PLACING MOST OF THE RAIN
ALONG WESTERN SLOPES...UP TO A QUARTER OF AN INCH /0.25/. AS THESE
STORMS TRACK EAST...THEY WILL BE MOVING INTO DRIER AIR AND ALONG
WITH WESTERLY FLOW...RAINFALL AMOUNTS WILL BE REDUCED TO A TENTH OF
AN INCH /0.10/. THE GFS CONTINUES TO PRODUCE RAINFALL EAST OF THE
BLUE RIDGE DESPITE WESTERLY FLOW ALOFT. ALL MODELS ARE HINTING AT A
BRIEF BACKING OF LOW LEVEL WINDS TO THE SOUTHWEST. THESE BACKING
WINDS AND A LEE TROUGH SHOULD BE ENOUGH TO CARRY ISOLATED SHOWERS
EAST OF THE BLUE RIDGE. JET DYNAMIC AND MODEST INSTABILITIES MAY
PRODUCE A FEW STRONG STORMS IN THE WEST...BUT WEST WIND AND STORMS
ENTERING RELATIVELY DRY AIR...SEVERE POTENTIAL IS VERY VERY LOW.

ONCE THE FRONT TRACKS EAST OF THE AREA SUNDAY EVENING...AND THE
UPPER LEVEL TROUGH PIVOTS TO THE EAST COAST MONDAY MORNING...COOLER
DRIER AIR WILL USHER IN THE AUTUMN SEASON. AHEAD OF THE
FRONT...SUNDAY TEMPERATURES WILL VARY FROM THE MID 70S TO NEAR 80F
ACROSS THE MOUNTAINS TO MID TO UPPER 80S EAST OF THE BLUE RIDGE.
TEMPERATURES WILL BE DEPEND ON RAINFALL TIMING. BEHIND THE
FRONT...DAYTIME TEMPERATURES WILL BE AROUND 10F COOLER MONDAY
AFTERNOON COMPARED TO SUNDAY. ALSO ON MONDAY...PRESSURE RISES WILL
BRING BREEZY AND GUSTY CONDITIONS TO THE AREA...ESPECIALLY ALONG THE
HIGHER RIDGES OF THE BLUE RIDGE. THE COLDEST OF THE AIR ARRIVES
MONDAY NIGHT. WITH HIGH PRESSURE OVER THE REGION...MONDAY NIGHT
TEMPERATURES WILL DIP INTO THE 40S...POSSIBLY THE UPPER 30S IN DEEP
MOUNTAIN VALLEYS AS WINDS DECOUPLE.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 PM EDT FRIDAY...

HIGH PRESSURE WILL BE IN CONTROL OF THE FORECAST REGION ON
TUESDAY...STARTING THE DAY CENTERED OVER THE MID OHIO RIVER VALLEY.
THE HIGH WILL MAINTAIN DRY NORTHERLY WIND FLOW ACROSS OUR AREA
THAT WILL KEEP TEMPERATURES A FEW DEGREES BELOW NORMAL...WITH
HIGHS HOLDING IN THE UPPER 60S TO MID 70S. THE DRY ATMOSPHERE WILL
ALSO RESULT IN MOSTLY CLEAR SKIES.

WE CAN EXPECT SIMILAR CONDITIONS FOR THE EARLY HALF OF WEDNESDAY...
ALTHOUGH A REINFORCING COLD FRONT WILL BUILD SOUTHWARD FROM EASTERN
CANADA...CROSSING NEW ENGLAND INTO THE MID ATLANTIC DURING THE
EVENING...WHERE THE FRONT IS THEN EXPECTED TO STALL AS IT RUNS INTO
UPPER LEVEL RIDGING ACROSS THE SOUTHEAST.

WINDS WILL SHIFT MORE EASTERLY WEDNESDAY NIGHT AS HIGH PRESSURE
PUSHES OFFSHORE...DRAWING AN INCREASING AMOUNT OF MARINE AIR INTO
OUR REGION. AS SUCH...EXPECT INCREASED STRATUS ACROSS THE MOUNTAINS
WEDNESDAY NIGHT...POSSIBLY WITH PATCHY DRIZZLE. MARINE AIR WILL ALSO
SUPPORT SPOTTY LIGHT RAIN ACROSS THE PIEDMONT THURSDAY AFTERNOON.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AS OF 135 AM EDT SATURDAY...

LIGHT EASTERLY WIND WILL KEEP CLOUDS BANKED UP AGAINST THE EASTERN
SLOPES OF THE BLUE RIDGE OVERNIGHT WITH MVFR AND POSSIBLE IFR
CONDITIONS MAINLY WEST OF A LINE FROM KLYH TO KDAN. LOWER
CONFIDENCE ABOUT CEILINGS AT KLYH AND KDAN THIS MORNING SINCE THEY
ARE ON THE EDGE OF THE UPSLOPE STRATUS. CEILINGS AT THESE AIRPORTS
MAY OCCASIONALLY DROP TO MVFR BEFORE 12Z. HAVE LIFR FOG IN AT KBCB
AND KLWB BEFORE 12Z BUT STILL POSSIBLE THAT CLOUDS WILL LIMIT FOG
FORMATION.

CEILINGS WILL LIFT AND BECOME SCATTERED BY MID TO LATE MORNING.
WIDESPREAD VFR CONDITIONS ARE EXPECTED THIS AFTERNOON. FOG WILL
DEVELOP AGAIN LATE TONIGHT IN THE RIVER VALLEYS. THIS MAY BRING
MVFR TO IFR VISIBILITY TO KLWB AND KBCB AFTER MIDNIGHT.

EXTENDED AVIATION DISCUSSION...

RIVER VALLEY FOG WILL DISSIPATE SUNDAY MORNING AFTER DAYBREAK.
UPSTREAM TROUGH AND ASSOCIATED COLD FRONT WILL CROSS THE AREA
SUNDAY WITH SHOWERS ASSOCIATED WITH FROPA. PASSAGE OF THIS FRONT
WILL BRING DRIER AIR TO THE REGION FOR EARLY NEXT WEEK PROMOTING
MAINLY VFR CONDITIONS. RIVER VALLEY FOG WILL STILL BE POSSIBLE AT
NIGHT.

&&

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

&&

$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...RCS
LONG TERM...NF
AVIATION...AMS/PM



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