Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 250138
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
938 PM EDT SUN AUG 24 2014

.SYNOPSIS...
HIGH PRESSURE EXTENDING FROM NEW ENGLAND SOUTHWARD ALONG THE
EASTERN FACE OF THE APPALACHIANS WILL BE REINFORCED TONIGHT AS A
SURGE OF CANADIAN AIR MOVES IN FROM THE EASTERN GREAT LAKES. HIGH
PRESSURE WILL BRING COOLER AND MUCH DRIER AIR TO THE MID ATLANTIC
THROUGH MID WEEK. ANOTHER COLD FRONT WILL APPROACH THE AREA LATE
IN THE WORK WEEK...BRINGING ANOTHER CHANCE OF SHOWERS AND
THUNDERSTORMS.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 930 PM EDT SUNDAY...
ADJUSTED THE SKY COVER TO REFLECT CLOUD COVER HANGING TOUGH OUT
EAST. ALSO BUMPED UP THE SLIGHT CHANCE POPS ACROSS THE NRV AND
ROANOKE VALLEY AS A FEW LOCATIONS ARE STILL REPORTING SOME
SCATTERED LIGHT RAIN/DRIZZLE. OOZ SOUNDING SHOWS A SATURATED MID
DECK OF ONLY 3K FEET...SO A TRACE OR SO OF RAIN IS ALL THAT IS
EXPECTED TONIGHT.

AS OF 614 PM EDT SUNDAY...
MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES ACCORDING TO LAST OBS
AND TRENDS ESPECIALLY WHERE CLOUDS ARE THINNING. THE RNKWRFARW
LOOKED OVERDONE WITH CONVECTION...ELECTED TO HOLD ON TO LIGHT RAIN
AND DRIZZLE FADING TONIGHT. KEPT THE RICHEST CLOUD COVER AND
MOISTURE ALONG THE SOUTHERN BLUE RIDGE MOUNTAINS TONIGHT. HIGH
PRESSURE WILL BUILD INTO FROM THE NORTHEAST TONIGHT INTO MONDAY.

AS OF 230 PM EDT SUNDAY...

THE CENTRAL APPALACHIANS AND MID ATLANTIC REMAINS UNDER A BROAD
AREA OF LOW CLOUDS THIS AFTERNOON...ALTHOUGH SATELLITE IMAGERY
INDICATES THAT A FEW BREAKS ARE DEVELOPING ACROSS THE PIEDMONT AS
DRY AIR ASSOCIATED WITH HIGH PRESSURE BUILDS IN FROM THE
NORTHEAST. A FEW PATCHES OF VERY LIGHT RAIN OR DRIZZLE REMAIN
ALONG THE BLUE RIDGE SOUTH OF ROANOKE...BUT THESE CONTINUE TO FADE
AS DRIER AIR WORKS IN. ONLY AREA IT SEEMS THAT IS EXPERIENCING A
TRUE SUMMER DAY IN OUR FORECAST REGION IS IN PORTIONS OF THE
MOUNTAIN EMPIRE...WHERE DOWNSLOPE FLOW HAS ALLOWED THE CLOUDS TO
SCATTER SO THAT TEMPERATURES CAN WARM TO AROUND 80.

LOW CLOUDS WILL PERSIST THROUGH THE REMAINDER OF SUNDAY FOR MOST
OF THE FORECAST AREA. OVERNIGHT...WINDS WILL SHIFT MORE
NORTHEASTERLY AS A REINFORCING PUSH OF HIGH PRESSURE CROSSES THE
EASTERN GREAT LAKES AND MOVES OVER NEW ENGLAND. THE WIND SHIFT
WILL CUT OFF THE FLOW OF MARINE AIR FILTERING INTO OUR AREA IN
FAVOR OF THAT FROM THE DRIER CANADIAN AIR MASS. THAT STATED...
MODELS SEEM TO BE A LITTLE AGGRESSIVE IN ERODING THE LOW CLOUDS IN
FAVOR OF DRIER AIR...SO MAINTAINED INCREASED CLOUDS ACROSS THE
MOUNTAINS AND FOOTHILLS THROUGH MOST OF THE NIGHT. CLOUDS HAVE A
BETTER CHANCE OF SCATTERING ACROSS THE PIEDMONT...HOWEVER MAY SEE
PATCHY FOG DEVELOP BECAUSE OF THE LIGHT WINDS AND MOIST SOIL
CONDITIONS.

FOR MONDAY...UPPER LEVEL RIDGING THAT IS PROVIDING THE MID
MISSISSIPPI RIVER VALLEY WITH VERY WARM CONDITIONS WILL BUILD UP
THE OHIO RIVER VALLEY TOWARD OUR AREA. AS SUCH...STRONGER HEATING
IS EXPECTED WHICH WILL HELP ERODE ANY LOW CLOUDS AND FOG QUICKLY
AFTER 9 AM. ASIDE FROM FAIR WEATHER CLOUDS DURING THE AFTERNOON...
MOSTLY CLEAR SKIES CAN BE EXPECTED FOR THE REMAINDER OF THE DAY.
EXPECT AFTERNOON HIGHS TO BE MUCH CLOSER TO SEASONABLE...WITH
HIGHS RANGING FROM THE MID/UPPER 70S ACROSS THE MOUNTAINS...TO THE
LOW 80S ACROSS THE PIEDMONT.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 145 PM EDT SUNDAY...

FORECAST AREA WILL REMAIN UNDER A 500 MB RIDGE THROUGH THE PERIOD.
PRECIPITATION AROUND THE EDGE OF THE RIDGE WILL STAY OUT OF THE
COUNTY WARNING AREA BUT THERE MAY BE PERIODS OF MORE CLOUD COVER
FROM STORMS IN THE MISSISSIPPI AND OHIO VALLEYS.

MODELS HAVE SOME RESIDUAL LOW LEVEL MOISTURE...WELL BELOW 850
MB...ALONG THE EAST SLOPES OF THE SOUTHERN BLUE RIDGE MONDAY NIGHT.
OTHERWISE EXPECTING A DRY AIR MASS. 850 MB TEMPERATURES RISE TO
AROUND +20 BY WEDNESDAY. SO WITH ANY DECENT SUNSHINE AND
MIXING...MAXIMUM TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE NORMAL
THAT DAY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 1145 AM EDT SUNDAY...

UPPER FLOW IS ZONAL WEDNESDAY NIGHT THROUGH THURSDAY WITH STRONG
TROUGHING OVER THE GREAT LAKES AND HIGH 500 MB HEIGHTS OVER THE LOWER
MISSISSIPPI VALLEY AND SOUTHEAST UNITED STATES. ECMWF KEEPS THE
UPPER RIDGE OVER THE SOUTHEAST THROUGH SATURDAY. THE NEXT TROF DOES
NOT REACH THE OHIO VALLEY UNTIL EARLY NEXT WEEK. SURFACE FRONT OVER
THE OHIO VALLEY MAY DRIFT SOUTH INTO THE FORECAST AREA BY SATURDAY.
ANY THREAT OF PRECIPITATION WILL BE UNORGANIZED UNTIL THIS BOUNDARY
GETS CLOSER. EVEN THEN THE FORCING LOOKS WEAK.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
AS OF 720 PM EDT SUNDAY...

BULK OF THE REGION IS STUCK UNDER A LOW END VFR/HIGH END MVFR DECK
OF CLOUDS. RADAR SHOWING VERY LIGHT RETURNS HEADING THRU ROA SOUTH
TO MTV. HAVE DZ AT ROA BUT NOT EXPECTING ANY VSBY ISSUES THIS
EVENING. THE MOISTURE DEPTH PER WEB CAMS/MANUAL OBSERVATIONS
IS ABOUT 2-3KFT DEEP...AND YOU CAN SEE THIN SPOTS IN THE OVC.
HOWEVER...AS SUN SETS...USUALLY WITH WEDGES WE SEE CLOUDS
RETHICKEN. HOWEVER...DRIER AIR WILL BE POURING IN FROM THE
NORTHEAST WHICH LEADS TO A TOUGH FORECAST AVIATION WISE. WILL LEAN
TOWARD THE 18Z NAM BUFKIT SOUNDING FORECAST AND BLEND IT WITH WHAT
WE ALREADY HAVE IN THE FORECAST.

WITH THIS IN MIND...EXPECT CIGS TO DROP TO MVFR AT ALL SITES
BETWEEN 00Z-07Z...EXCEPTION BEING LYH/DAN CLOSER TO THE DRIER AIR
MOVING IN. THE ISSUE FOR THEM WILL BE THE MOISTURE ON THE
GROUND...AND WITH LIGHT EASTERLY WINDS...FOG WILL BE A
FACTOR...AND CONFIDENCE HIGH ENOUGH TO DROP LYH TO 1SM...BUT KEEP
DAN AT MVFR/4SM.

FURTHER WEST...THE CLOUDS ARE GOING TO OFFSET THE FOG SOMEWHAT BUT
STILL THINK POTENTIAL DENSE FOG AT LWB/BCB AROUND 09-12Z IS
THERE...SO MADE IT A TEMPO GROUP.

ANY FOG/LOW CLOUDS WILL ERODE BY 12-14Z...WITH VFR FORECAST FOR
MOST OF THE DAY MONDAY. EXPECT A CONTINUED LIGHT EASTERLY FLOW.
MAY SEE SOME FLAT CU IN THE MTNS.


SEE THE EQUIPMENT SECTION FOR INFORMATION CONCERNING THE KLYH
ASOS.

EXTENDED DISCUSSION...
HIGH PRESSURE STRETCHING FROM NEW ENGLAND SOUTHWARD ALONG THE
EASTERN FACE OF THE APPALACHIANS WILL MAINTAIN DRY CONDITIONS
THROUGH MIDWEEK. THE MAIN CONCERNS DURING THIS TIME WILL BE
LOCALIZED FOG DURING THE PREDAWN HOURS OF EACH MORNING DUE TO
MOIST SOILS...LIGHT WINDS AND MINIMAL CLOUD COVER. THE OFFICIAL
NHC FORECAST INDICATES THAT TROPICAL CYCLONE CRISTOBAL NEAR THE
BAHAMAS WILL REMAIN WELL OFF THE EAST COAST AND WILL NOT IMPACT
THE LOCAL WEATHER. A COLD FRONT WILL SINK SOUTHWARD FROM THE GREAT
LAKES ON THURSDAY...BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS
AS WELL AS POTENTIAL SUB VFR CIGS/VSBYS.

&&

.EQUIPMENT...
AS OF 200 PM SUNDAY...
THE ASOS TEMPERATURE AT LYNCHBURG (LYH) VA REMAINS INOP DUE TO A
BOARD FAILURE. TECHNICIANS ARE EXPECTED TO WORK ON THIS MONDAY.
TOWER OBSERVERS ARE AUGMENTING DURING NORMAL SERVICE HOURS.

&&

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

&&

$$
SYNOPSIS...NF
NEAR TERM...CF/KK/NF
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...NF/WP
EQUIPMENT...WP


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