Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 281904
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
304 PM EDT FRI AUG 28 2015

.SYNOPSIS...
HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL SLIDE SOUTH AND
REMAIN ABOUT OVERHEAD OVERNIGHT INTO SATURDAY. A WEAK UPPER LEVEL
DISTURBANCE WILL LIFT NORTH ALONG THE APPALACHIANS SUNDAY INTO
MONDAY AHEAD OF A WEAK COLD FRONT TO THE WEST. UPPER LEVEL HIGH
PRESSURE WILL STRENGTHEN IN THE WAKE OF THIS FEATURE...RESULTING
IN MORE DIURNAL NATURE SHOWERS AND STORMS INTO THE MIDDLE OF NEXT
WEEK.
&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 300 PM EDT FRIDAY...

THE MAIN WEATHER FEATURE DRIVING OUR WEATHER INTO THE FIRST PART OF THE
WEEKEND WILL CONTINUE TO BE AN AREA OF HIGH PRESSURE LINGERING OVER THE
EASTERN SEABOARD WITH ANY SIGNIFICANT SYNOPTIC SHORT WAVE ENERGY
SLIDING BY WELL TO OUR NORTH. ANY DIURNAL SHOWERS THAT DO DEVELOP WILL
BE ISOLATED AND INDUCED BY OROGRAPHIC EFFECTS IN TERRAIN WEST OF THE
BLUE RIDGE...WITH ACTIVITY FADING OUT RAPIDLY AFTER SUNSET. SKIES WILL
CLEAR THIS EVENING EAST OF THE RIDGE...BUT CLOUDS WILL LINGER THROUGH
TONIGHT FROM THE RIDGE WESTWARD WITH SOME GRADUAL CLEARING LATE AND
VALLEY FOG POSSIBLE TOWARD DAYBREAK. SATURDAY WILL HAVE A SIMILAR
FLAVOR WITH ISOLATED SHOWERS POSSIBLE WEST OF THE RIDGE. LOWS TONIGHT
WILL BE AROUND 60 ACROSS THE PIEDMONT WITH MIDDLE 50S WEST OF THE
RIDGE. HIGHS SATURDAY WILL BE IN THE MIDDLE 80S EAST TO UPPER
70S/AROUND 80 WEST.
&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 230 PM EDT FRIDAY...

RIDGING BOTH SURFACE AND ALOFT WILL LINGER INTO SATURDAY NIGHT BEFORE
GIVING WAY TO AN UPSTREAM UPPER TROUGH AND ASSOCIATED WEAK FRONTAL
BOUNDARY SUNDAY INTO MONDAY. THIS SHOULD ALLOW FOR A PLUME OF DEEPER
MOISTURE ACROSS THE SOUTHEAST TO BE PULLED NORTHWARD ALONG THE
APPALACHIANS WITH EMBEDDED SHORTWAVE ENERGY AIDING LIFT ALONG WITH
HEATING.

MODELS CONTINUE TO SHOW THE BEST FOCUS IN AN ARC ACROSS THE
MOUNTAINS WITH BETTER INSTABILITY...DIFFLUENCE AND THETA-E RIGHT ALONG
THE WESTERN SLOPES ESPECIALLY LATER SUNDAY INTO EARLY MONDAY. HOWEVER
THIS AGAIN WITHIN AN AREA OF LOW LEVEL SUBSIDENCE ENHANCED VIA WEAK
SURFACE RIDGING ACROSS THE MOUNTAINS SO EXPECTING MORE SCATTERED NATURE
COVERAGE AT THIS POINT. THUS HOLDING OFF ON GOING MUCH MORE THAN MID
CHANCE POPS...MAINLY BLUE RIDGE WEST FROM SUNDAY AFTERNOON INTO LATE
MONDAY...WITH HIGHEST ACROSS THE FAR WESTERN COUNTIES WHERE FORECAST
SOUNDINGS SHOW QUITE A MOIST/WEAKLY VEERED PROFILE BY MONDAY AFTERNOON.
WITH LOW LEVEL MOISTURE A BIT LESS EAST OF THE MOUNTAINS...APPEARS
SHOWERS MORE ISOLATED SO ONLY KEEPING A 20ISH POP OUT EAST FOR NOW.

WARMING 85H TEMPS SUPPORT RATHER WARM TEMPS EAST OF THE MOUNTAINS BOTH
SUNDAY AND MONDAY WHEN TEMPS MAY GET CLOSE TO 90 PIEDMONT PENDING
DEGREE OF CLOUDS. OTHERWISE BECOMING MORE MUGGY GIVEN INCREASING
DEWPOINTS...AND HIGHS MOSTLY IN THE 80S WITH SOME 70S POSSIBLE FAR WEST
ESPECIALLY IF SHOWERS ARE MORE WIDESPREAD SUNDAY/MONDAY.
&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 1240 PM EDT FRIDAY...

OVERALL PERSISTENCE FORECAST AT LEAST EARLY ON AS UPPER RIDGING
STRENGTHENS ACROSS THE REGION IN THE WAKE OF THE PASSING WAVE ALOFT AND
IN INCREASING SUBSIDENCE WELL NORTH OF ERIKA. THIS SHOULD RESULT IN A
MORE DIURNALLY DRIVEN TREND OF DAILY SHOWERS AND ISOLATED STORMS EACH
AFTERNOON/EVENING WITH A GRADUAL INCREASE IN COVERAGE/EXPANSE FROM
TUESDAY THROUGH THURSDAY GIVEN BETTER PWATS/MOISTURE AND SLIGHT COOLING
ALOFT. HOWEVER THINK LOW/MEDIUM CHANCE POPS CONFINED MAINLY ALONG/WEST
OF THE BLUE RIDGE PER OROGRAPHICS...AND MORE ISOLATED ELSEWHERE
ESPECIALLY GIVEN MOISTURE OVER TOP A LINGERING SURFACE RIDGE. THUS
FOLLOWED CLOSER TO TRENDS FROM WPC WITH A GRADUAL BOOST IN POPS EACH
DAY BUT LITTLE DURING THE OVERNIGHTS INTO THURSDAY. THINGS BECOME MORE
UNCERTAIN BY DAY7 WITH MODELS LOWERING HEIGHTS ACROSS THE APPALACHIANS
AND FROM THE NE WITH A POSSIBLE ASSOCIATED BACKDOOR COOL FRONT. THIS
COULD HELP FOCUS MOISTURE GIVEN A BETTER EASTERLY TRAJECTORY TO THE
NORTH OF ERIKA OR ITS REMNANTS ON FRIDAY. THEREFORE GOING WITH MORE
WIDESPREAD CHANCE POPS PER POTENTIAL TROPICAL TYPE PWATS OVER THE AREA
DURING HEATING FRIDAY AFTERNOON.

OTHERWISE LITTLE CHANGE IN DAILY TEMPS GIVEN SUCH A HUMID/WARM
AIRMASS...SUPPORTING HIGHS MOSTLY IN THE 80S AND LOWS IN THE 60S EXCEPT
PERHAPS A BIT COOLER FRIDAY PENDING CLOUDS/SHOWERS.
&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
AS OF 130 PM EDT FRIDAY...

LITTLE CHANGE IN THE SYNOPTIC PATTERN THROUGH THE TAF PERIOD WILL LEAD
TO A PERSISTENCE FORECAST. EXPECT DIURNALLY FORCED BKN/V/SCT VFR
CEILINGS AT ALL LOCATIONS THROUGH THIS AFTERNOON. ANY SHOWER
DEVELOPMENT WILL BE OROGRAPHICALLY DRIVEN WEST OF THE BLUE RIDGE AND
ISOLATED IN COVERAGE SO WILL NOT INCLUDE ANY MENTION IN TAFS.

INDICATIONS ARE THAT CLOUDS WILL NOT STAY LOCKED IN AFTER SUNSET AS
LAST NIGHT...BUT WILL LINGER CIGS FROM THE BLUE RIDGE WEST UNTIL THE
04Z/08Z TIME FRAME. THE LINGERING CLOUDS WILL KEEP FOG DEVELOPMENT IN
CHECK...THOUGH DISSIPATION/BREAKS IN THE CLOUDS WILL ALLOW FOR
DEVELOPMENT LATE. WILL KEEP THINGS TEMPO MVFR AT KBCB AND LIMIT KLWB TO
MEDIUM IFR. EXPECT PATCHY FOG EAST OF THE RIDGE AND KDAN SHOWED SOME
FOG DEVELOPMENT LAST NIGHT SO WILL GO WITH A TEMPO MVFR GROUP TOWARD
DAYBREAK THERE AS WELL. ANY FOG/STRATUS WILL BURN OFF AFTER DAYBREAK
TOMORROW AND EXPECT SCT/V/BKN VFR CLOUDS TO DEVELOP ONCE AGAIN LATE IN
THE VALID PERIOD.

EXTENDED AVIATION DISCUSSION...
AS OF 130 PM EDT FRIDAY...

EXPECT A MAINLY VFR FORECAST INTO SUNDAY. MOISTURE GRADUALLY
INCREASES...WHICH WILL INCREASE OUR CHANCES FOR DIURNAL SHOWERS AND
STORMS AS WE HEAD INTO THE FIRST PART OF NEXT WEEK. SHORT WAVE ENERGY
MOVING UP FROM THE SOUTH WILL GIVE THE BEST CHANCES FOR MORE WIDESPREAD
CONVECTIVE ACTIVITY IN THE SUNDAY/MONDAY TIME FRAME. GENERALLY EXPECT
THE BEST CHANCES FOR MVFR/IFR TO BE LATE NIGHT/EARLY MORNING DUE TO FOG
AND STRATUS DEVELOPMENT FROM THE BLUE RIDGE WEST ESPECIALLY AT KLWB/KBCB.
&&

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

&&

$$
SYNOPSIS...JH
NEAR TERM...MBS
SHORT TERM...JH
LONG TERM...JH
AVIATION...MBS/NF


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