Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 291121
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
721 AM EDT TUE JUL 29 2014

.SYNOPSIS...
UPPER LEVEL LOW PRESSURE WILL REMAIN CENTERED OVER EASTERN CANADA
THROUGH THE MIDDLE OF THE WEEK...WHILE COOL HIGH PRESSURE SETTLES
OVER THE REGION THROUGH WEDNESDAY. THESE COOL AIRMASSES WILL KEEP
TEMPERATURES BELOW NORMAL OVER THE NEXT FEW DAYS. DURING THE
LATTER HALF OF THE WEEK AND HEADING INTO THE WEEKEND...THE UPPER
TROUGH WILL RETROGRADE WESTWARD...ALLOWING FOR AN INCREASE IN
MOISTURE...MODERATING TEMPERATURES...AND POTENTIAL FOR SHOWERS AND
STORMS.

&&

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

FOR THE REMAINDER OF THE MORNING...WILL SEE A FEW SHOWERS DEVELOP
ALONG THE WESTERN RIDGES FROM TIME TO TIME...PERHAPS PASSING AS
FAR EAST AS THE NEW RIVER VALLEY BEFORE DISSIPATING IN THE
NORTHWESTERLY DOWNSLOPE FLOW. A FEW HUNDREDTHS OF AN INCH RAINFALL
IS LIKELY ACROSS PORTIONS OF OUR WEST VIRGINIA/MOUNTAIN EMPIRE
COUNTIES...WITH AMOUNTS TAPERING DOWN TO A TRACE FURTHER EAST.
WINDS ACROSS THE AREA APPEAR TO BE HOLDING JUST STRONG ENOUGH MOST
PLACES TO KEEP THE ATMOSPHERE MIXED...WHICH SHOULD LIMIT FOG
FORMATION TO ISOLATED POCKETS IN THE DEEPER MOUNTAIN VALLEYS.

THE MAIN STORY FOR TUESDAY WILL BE ANOTHER DAY OF COOL...EARLY
AUTUMN-LIKE WEATHER AS A DEEP UPPER LEVEL LOW CONTINUES TO DRIFT
SLOWLY NEAR HUDSON BAY CANADA. LOW CLOUDS ACROSS THE MOUNTAINS
WILL LIFT AND SCATTER BY LATE MORNING...RESULTING IN A MIX OF
CLOUDS AND SUNSHINE THROUGH THE AFTERNOON. WILL ALSO SEE MORE
SPOTTY SHOWER ACTIVITY DEVELOP ACROSS THE MOUNTAINS AS SUBTLE
DISTURBANCES PASS OVERHEAD. WITH HIGH PRESSURE BEGINNING TO SETTLE
INTO THE AREA FROM THE CENTRAL MISSISSIPPI VALLEY...WE CAN ALSO
EXPECT CALMER WIND SPEEDS THROUGH THE DAY WHICH WILL CUT DOWN ON
THE CHILL THAT THE STRONGER GUSTS PRODUCE. STILL...IF OUTDOORS FOR
EXTENDED PERIODS OF TIME TODAY ACROSS THE MOUNTAINS...YOU MAY
CONSIDER KEEPING A LIGHT JACKET HANDY AS AFTERNOON HIGHS RANGE
FROM THE MID 60S TO THE LOW 70S. HIGHS EAST OF THE BLUE RIDGE WILL
BE WARMER...CLIMBING INTO THE MID/UPPER 70S...PERHAPS TOUCHING 80
OVER THE SOUTHSIDE.

MOSTLY CLEAR SKIES AND LIGHT WINDS WILL ALLOW FOR STRONG
RADIATIONAL COOLING TUESDAY NIGHT...ALLOWING OVERNIGHT
TEMPERATURES TO FALL INTO THE 50S MOST LOCATIONS...AND IN THE LOW
TO MID 40S IN A FEW OF THE DEEPER MOUNTAIN VALLEYS. AT THIS
TIME...THINK MOST LOCATIONS WILL STAY A COUPLE DEGREES ABOVE
RECORD LOWS...ALTHOUGH IT WILL BE CLOSE FOR DANVILLE.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 230 AM EDT TUESDAY...

MODELS CONTINUE TO BE IN GOOD AGREEMENT THAT THE FULL-LATITUDE UPPER
TROF ACROSS THE EASTERN HALF OF THE UNITED STATES RELAXES SOME ON
WEDNESDAY AS AN UPPER LEVEL IMPULSE MOVES SOUTH INTO THE NORTHERN
PLAINS. THIS...COMBINED WITH THE UPPER RIDGE IN THE ATLANTIC NOSING
EAST...WILL SHIFT THE UPPER TROF AXIS TO THE WEST ON
THURSDAY...PLACING OUR AREA IN AN UPPER LEVEL SOUTHWEST FLOW ON THE
EAST SIDE OF THE TROF.

MODELS ARE TRENDING WETTER IN THE MOUNTAINS ON WEDNESDAY AFTERNOON
AS WEAK UPSLOPE FLOW AND STEEP LAPSE RATES RING OUT SHALLOW
MOISTURE. WITHOUT UPPER LEVEL SUPPORT...COVERAGE SHOULD BE
VERY LIMITED AND INSERTED ONLY A SMALL CHANCE FOR PRECIPITATION IN
THE WESTERN GREENBRIER VALLEY. TEMPERATURES BEGIN TO MODIFY ON
WEDNESDAY AS 1000-850MB THICKNESSES INCREASE. GUIDANCE HAS SHOWN
GOOD RUN TO RUN CONSISTENCY WITH FORECAST HIGHS FROM THE 70S IN THE
MOUNTAINS TO 80-85 EAST OF THE BLUE RIDGE.

CENTER OF A SFC HIGH IS FORECAST TO RESIDE OVER SOUTHERN WV/WESTERN
VA BY 12Z (8 AM THURSDAY)...LEADING TO ANOTHER COOL NIGHT.
HOWEVER...RH CROSS SECTIONS INDICATE HIGH LEVEL CLOUDS BEGIN TO
STREAM OVER THE REGION FROM THE SOUTH...WHICH COULD SLOW FALL IN
TEMPS. INCREASED LOWS A DEGREE...WHICH KEEPS ALL CLIMATE SITES AT
LEAST A FEW DEGREES ABOVE RECORDS FOR THURSDAY MORNING.

MOISTURE AND WARMER 850MB TEMPS...ALONG WITH AN INCREASE IN CLOUD
COVER SURGES NORTH OVER OUR AREA THURSDAY. INCREASED HIGHS A DEGREE
OR TWO...BUT ABUNDANT MID/HIGH CLOUDS WILL LIMIT WARMING. WEAK
SOUTHEAST UPSLOPE FLOW AND DEVELOPING ISENTROPIC LIFT MAY GENERATE
SOME SHOWERS ALONG THE BLUE RIDGE.  INCREASED COVERAGE FOR SHOWERS
THURSDAY AND THURSDAY NIGHT ALONG THE BLUE RIDGE.  LOWS FRIDAY
MORNING WILL ALSO PUSHED UP WITH ANTICIPATED WIDESPREAD CLOUDINESS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...

UPPER 500 MB TROF OVER THE NORTHEAST UNITED STATES AMPLIFIES ON
FRIDAY AND SATURDAY WITH A SIGNIFICANT SHORT WAVE OVER THE OHIO
VALLEY. MODELS SIMILAR IN SHOWING HEIGHT FALLS ON THE SOUTHERN END
OF THE TROF AND WHAT MAY EVENTUALLY BE A CUT OFF LOW OVER THE LOWER
MISSISSIPPI VALLEY OR SOUTHEAST UNITED STATES MONDAY.

MOISTURE BEGINS TO INCREASE ACROSS THE AREA ON FRIDAY BUT LITTLE IN
THE WAY OF ANY ORGANIZED LIFT TO TRIGGER ANY PRECIPITATION ASIDE
FROM DAILY THREAT OF AIRMASS TYPE SHOWERS AND THUNDERSTORMS. WITH
LITTLE CHANGE IN THE AIR MASS THERE WILL BE MINIMAL CHANGES IN HIGH
AND LOW TEMPERATURES EACH DAY. TEMPERATURES WILL BE NEAR NORMAL. NOT
ANTICIPATING ANY EXTREMES.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 715 AM EDT TUESDAY...

PATCHY MVFR FOG WAS NOTED AT KLWB AND ACROSS THE MOUNTAINS EARLY
THIS MORNING...BUT WILL LIFT SHORTLY AFTER 13Z...LEAVING VFR
SCT-BKN CLOUD COVER. AN UPPER LEVEL DISTURBANCE WILL ARRIVE FROM
THE NORTHWEST HELPING TO TRIGGER ISOLATED TO WIDELY SCATTERED
RAIN SHOWERS. INCLUDED VCSH AT ALL MOUNTAIN TAF SITES AND
KROA.

OTHERWISE...EXPECT SCT TO BKN STRATOCU LAYER TO DEVELOP BY LATE
MORNING...GREATER COVERAGE IN THE MOUNTAINS...WITH CLOUD BASES
RANGING 3KFT IN THE MOUNTAINS TO 5KFT FURTHER EAST. WINDS WILL BE
LIGHTER TODAY COMPARED TO MONDAY WITH SPEEDS GENERALLY 5-10KTS.

EXTENDED AVIATION DISCUSSION...

PERSISTENT TROUGH PATTERN IN THE EAST WILL GRADUALLY RETROGRADE
WEST BY THE END OF THE WEEK. MAINLY VFR CONDITIONS ARE EXPECTED
THROUGH AT LEAST THURSDAY SAVE FOR SOME LATE NIGHT/EARLY MORNING
PATCHY MVFR FOG IN THE MOUNTAIN AND RIVER VALLEYS. AFTER
THURSDAY...WITH THE TROUGH AXIS FARTHER WEST...THIS WILL ALLOW FOR
A RETURN OF ATLANTIC MOISTURE AND A GREATER ABUNDANCE OF
SHOWERS...AND POTENTIALLY STORMS...IN THE FORECAST HEADING INTO
THE WEEKEND. THIS ALSO WILL ALLOW FOR INCREASED CHANCES OF SUB-VFR
CONDITIONS WITHIN THE AREA OF THE SHOWERS...AND THEN AGAIN
OVERNIGHT IN THE FORM OF LIGHT FOG OR STRATUS AS BOUNDARY MOISTURE
GETS TRAPPED UNDER THE NOCTURNAL INVERSION.

&&

.CLIMATE...
JULY 30TH RECORD LOWS:

ROANOKE......54...1997
BLUEFIELD....50...1981
DANVILLE.....60...1972/81/83/2013
LEWISBURG....46...2013
LYNCHBURG....52...1997
BLACKSBURG...50...1973/81


JULY 31ST RECORD LOWS:

ROANOKE......49...1914
BLUEFIELD....49...1997
DANVILLE.....55...1966
LEWISBURG....48...1997
LYNCHBURG....49...1997
BLACKSBURG...44...1997

&&

.EQUIPMENT...
THE NOAA WEATHER RADIO AT WYTHEVILLE VA...WZ2500...BROADCASTING
ON A FREQUENCY OF 162.450 MHZ...IS OFF THE AIR...DUE TO PHONE LINE
ISSUES. PHONE COMPANY IS WORKING ON IT. NO ESTIMATED TIME FOR
RETURN TO SERVICE.

&&

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

&&

$$
SYNOPSIS...NF
NEAR TERM...NF/WP
SHORT TERM...PH
LONG TERM...AMS
AVIATION...NF/PH/WP
CLIMATE...DS/PH
EQUIPMENT...DS



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