Area Forecast Discussion
Issued by NWS Blacksburg, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KRNK 310835
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
435 AM EDT MON AUG 31 2015

.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE PASSING ACROSS THE CAROLINAS WILL
MAINTAIN SHOWER ACTIVITY ACROSS THE AREA THROUGH LATE MORNING...
WITH ADDITIONAL SHOWERS THEN DEVELOPING WITH DAYTIME HEATING.
UPPER LEVEL HIGH PRESSURE WILL THEN STRENGTHEN AND KEEP US IN A
RATHER STAGNANT PATTERN...MAINTAINING A CHANCE FOR AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS THROUGH THE MIDDLE OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 350 AM EDT MONDAY...

CURRENTLY KEEPING AN EYE ON AN UPPER LEVEL DISTURBANCE MAKING ITS
WAY EAST ACROSS THE CAROLINAS. BANDS OF LIGHT RAIN CONTINUE TO
RADIATE NORTH ACROSS OUR AREA THIS MORNING...BUT ARE GRADUALLY
FADING AS THEY ENCOUNTER THE DRIER AIR IN PLACE. AS SUCH...HAVE
ENTERED HIGH RAIN CHANCES FOR AREAS SOUTH OF HIGHWAY 460...BUT
WITH LOW RAINFALL AMOUNTS...IN MANY CASES JUST ENOUGH TO WET THE
SURFACE BUT LITTLE ELSE. OTHERWISE...WIDESPREAD CLOUD COVER IS
HELPING TO MAINTAIN WARMER TEMPERATURES THAN IN PREVIOUS NIGHTS...
WITH MID TO UPPER 60S HOLDING FOR THE REMAINDER OF THE NIGHT.

THE DISTURBANCE TRIGGERING OUR SPOTTY RAINFALL WILL PROGRESS EAST
THROUGH LATE MORNING...WITH SHOWER ACTIVITY BECOMING ISOLATED TO
WIDELY SCATTERED BY LUNCHTIME. HOWEVER...WE CAN EXPECT SPOTTY
SHOWERS TO REDEVELOP DURING THE AFTERNOON AS WE APPROACH MAXIMUM
DAYTIME HEATING. BETTER CHANCES FOR SHOWER ACTIVITY WILL BE FOUND
ACROSS THE MOUNTAINS...WHERE CONVERGENCE ALONG THE RIDGETOPS WILL
PROVIDE ADDED LIFT. RAINFALL AMOUNTS WILL REMAIN LIGHT...PERHAPS
ONE TO TWO TENTHS OF AN INCH IN SPOTS. SKIES WILL REMAIN CLOUDY
TO MOSTLY CLOUDY...WHICH WILL LIMIT AFTERNOON HIGHS TO THE UPPER
70S FOR THE MOUNTAINS...AND THE LOW 80S FOR THE PIEDMONT.

WITH THE UPPER LEVEL DISTURBANCE OUT OF OUR AREA BY MONDAY EVENING...
EXPECT SHOWERS TO END AND CLOUD COVER TO DECREASE. WE WILL HANG ON
TO THE MUGGY AIRMASS HOWEVER...WHICH WILL MAKE FOR ANOTHER WARM
NIGHT WHERE TEMPERATURES HOLD IN THE LOW TO MID 60S AREAWIDE. THE
DECREASE IN CLOUDS...COUPLED BY LIGHT WINDS...WILL ALSO SUPPORT
ANOTHER ROUND OF PATCHY FOG.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
AS OF 400 AM EDT MONDAY...

SEVERAL WEAK SYNOPTIC FEATURES TO NOTE ACROSS THE REGION
TUESDAY...ALL UNDERLYING A BROAD SUBTROPICAL UPPER RIDGE EXTENDING
FROM THE SOUTH CENTRAL U.S. INTO THE NORTHEAST U.S. REMNANTS OF
FORMER T.S. ERIKA WILL BE LOCATED OFF THE NC/VA COAST AND TRACKING
SOUTHEAST AROUND THE EASTERN PERIPHERY OF THE UPPER RIDGE.
MEANWHILE...A VERY WEAK AREA OF LOW PRESSURE ALOFT WILL PERSIST FROM
EASTERN TX INTO THE OH VALLEY. OVERALL...THERE IS LITTLE IN THE WAY
OF A FOCUSING MECHANISM FOR PRECIPITATION AND ANY CONVECTION SHOULD
BE THE RESULT OF DIFFERENTIAL HEATING AND LINGERING TROPICAL
MOISTURE ACROSS THE MOUNTAINS...MAINLY ACROSS THE ALLEGHANYS OF
EASTERN WV/WESTERN VA...AND THE BLUE RIDGE OF NORTHWEST NC.

FOR WEDNESDAY...THE PATTERN BECOMES SOMEWHAT MORE INTERESTING. A
WEAK SHORT WAVE...ORIGINALLY EMANATING FROM LOW PRESSURE IN THE
PACIFIC NORTHWEST...WILL TRACK AROUND THE NORTHERN PERIPHERY OF THE
UPPER LOW...RESULTING IN A TEMPORARY SUPPRESSING OF THE UPPER RIDGE
TO THE SOUTH. THE WEAK UPPER TROUGH WILL SLIDE SE-SSE INTO NORTHERN
VA DURING PEAK DIURNAL HEATING. WITH RESIDUAL TROPICAL MOISTURE IN
PLACE...THERE SHOULD BE AN INCREASE IN AFTERNOON/EVENING CONVECTION
AS COMPARED TO TUESDAY. CERTAINLY...ORGANIZATION AND COVERAGE
SHOULD BE BETTER THAN TUESDAY...BUT WITH WEAK DYNAMICS...STILL
PRUDENT TO KEEP POPS IN THE LOW-MID CHANCE RANGE AT THIS POINT.

THE WEAK UPPER TROUGH WILL SAG FURTHER SOUTH TO SOUTH-SOUTHWEST
THURSDAY AS A VERY HIGH AMPLITUDE RIDGE BUILDS TOWARD HUDSON BAY.
THE UPPER RIDGE WILL BE THE UNDERLYING SYNOPTIC FEATURE FOR THE
ENTIRE EASTERN U.S. THE BEST THREAT FOR CONVECTION WILL FOLLOW THE
SOUTHWARD SHIFT OF THE WEAK UPPER TROUGH...MAINLY ACROSS SOUTHWEST
VA/NORTHWEST NC...SOUTHSIDE VA...AND THE NC PIEDMONT BY AFTERNOON.
WITH VERY WEAK DYNAMICS...CONVECTION WILL AGAIN BE THE RESULT OF
DAYTIME INSTABILITY AND DIFFERENTIAL HEATING. POPS HAVE ONCE AGAIN
BEEN HELD MOSTLY IN THE 20-30 PERCENT RANGE.

UNDER THE UPPER RIDGE...850MB TEMPS WILL HOVER IN THE +18C TO +20C
RANGE MUCH OF THE PERIOD. THE HOTTEST AIR WILL REMAIN TO OUR
NORTH...HOWEVER. DEWPOINTS WILL HOVER AROUND 60F MOUNTAINS TO THE
UPPER 60S PIEDMONT. THIS WILL RESULT IN A CONTINUATION OF ABOVE
NORMAL TEMPERATURES THROUGH THE PERIOD...ESPECIALLY MIN TEMPS.
OVERALL EXPECT MIN TEMPS TO AVERAGE 10 DEGREES ABOVE NORMAL...WITH
MAX TEMPS 5 TO 7 DEGREES ABOVE NORMAL THROUGH THE PERIOD. USED A
MODEL BLEND FOR MAX/MIN TEMPS THROUGH THE PERIOD AS THE GFS
CONTINUES TO BE TOO WARM...AS IT HAS MOST OF THE SUMMER. THIS WILL
RESULT IN MAX TEMPS MOSTLY IN THE 80S...WITH 70S IN THE MOUNTAINS
AND A FEW SPOTS NEAR 90 ACROSS THE PIEDMONT.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 415 AM EDT MONDAY...

A LATE SUMMER...HIGH AMPLITUDE UPPER RIDGE REMAINS OVER THE
NORTHEAST U.S. INTO SOUTHEAST CANADA AT THE BEGINNING OF THE
PERIOD WITH A FAIRLY DEEP TROUGH IN THE NORTHWEST U.S. THIS PATTERN
WILL REMAIN IN PLACE THROUGH THE WEEKEND...THEN STILL APPEARS
DESTINED TO BREAK DOWN EARLY NEXT WEEK AS THE AFOREMENTIONED
NORTHWEST U.S. UPPER TROUGH BEGINS TO TRACK EASTWARD.

CONSEQUENTLY...UPPER HEIGHTS AND 850MB TEMPS REMAIN WELL ABOVE
NORMAL FOR EARLY SEPTEMBER AS SUMMER HANGS ON. HOWEVER...MODELS
CONTINUE TO INDICATE DEVELOPMENT OF A BACKDOOR COLD FRONT DURING
THE LATER HALF OF THE WEEK AS A LARGE 1030MB SFC HIGH DEVELOPS
UNDERNEATH THE NORTHEAST U.S. UPPER RIDGE. THIS SURFACE HIGH BUILDS
SOUTHWEST INTO THE WEEKEND...PUSHING THE ASSOCIATED BACKDOOR COLD
FRONT INTO THE REGION THURSDAY...BEFORE IT STALLS ACROSS THE SOUTH-
SOUTHWEST PART OF THE CWA. THIS FEATURE...COMBINED WITH RESIDUAL
ANTECEDENT TROPICAL MOISTURE...SHOULD SERVE TO RESULT IN AN
ENHANCEMENT OF DIURNAL CONVECTION. HOWEVER...WITH EXTREMELY WEAK
DYNAMICS ALOFT UNDERNEATH THE MAMMOTH UPPER RIDGE...CONVECTION WILL
LARGELY BE DRIVEN BY LOW-LEVEL CONVERGENCE ATTEMPTING TO OVERCOME
LARGE SCALE SUBSIDENCE. IT MAY END UP BEING MORE OF A LIGHT SHOWER
SITUATION WITH ABUNDANT CLOUD COVER BANKED UP ALONG THE EASTERN
SLOPES OF THE ALLEGHANYS. THE BEST COVERAGE OF PRECIPITATION SHOULD
BE ACROSS THE NORTHERN PARTS OF THE CWA FRI...SHIFTING TO THE
SOUTHWEST PART OF THE CWA SAT-SUN.

DESPITE THE UPPER RIDGE...THE CLOUD COVER AND INCREASING NORTHEAST
SFC WINDS WILL RESULT IN A TREND TOWARD COOLER TEMPERATURES DURING
THIS PERIOD...ESPECIALLY MAX TEMPS AND MOST NOTABLY ACROSS THE NORTH
AND EAST PARTS OF THE CWA. MAX TEMPS WILL DROP BACK FROM THE MID
AND UPPER 80S THU TO THE 70S BY THE WEEKEND. MIN TEMPS WILL BE
HARDER PRESSED TO DROP HOWEVER WITH LOWS STILL MOSTLY IN THE
60S.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
AS OF 205 AM EDT MONDAY...

RADAR INDICATES BANDS OF LIGHT RAIN PASSING NORTH ACROSS THE
HIGHLANDS AND FOOTHILLS OF NORTH CAROLINA...FALLING OUT OF
CEILINGS WITH BASES AT 6KFT AND UP. LIGHT OCCASIONAL SPRINKLES
ARE BEING REPORTED ELSEWHERE ACROSS THE AREA.

OVERNIGHT...EXPECT MAINLY VFR CEILINGS TO PERSIST...POSSIBLY WITH
HIGH END MVFR ALONG THE BLUE RIDGE TOWARD DAWN. REDUCTIONS IN
VISIBILITY WILL MAINLY OCCUR IN ANY AREAS OF HEAVIER RAIN...BUT
EXPECT THEY WILL BE FEW. WITH CLOUD COVER SO WIDESPREAD...DO NOT
ANTICIPATE MORE THAN VERY LIGHT MIST ACROSS THE REGION...HOLDING
VISIBILITIES 5SM AND UP.

MODELS FAVORING LOWERING CEILINGS ACROSS THE SOUTHEAST AFTER DAWN
MONDAY MORNING AS WEAK WAVE MOVES ACROSS THE NORTH CAROLINA
PIEDMONT. TAF FORECAST FOR DANVILLE REFLECTS THIS THINKING...BUT
DO NOT EXPECT ANY OTHER TAF SITES WILL FALL BE AFFECTED. CEILINGS
AT DANVILLE WILL IMPROVE AGAIN DURING THE AFTERNOON...WITH BASES
AREAWIDE RANGING FROM 4KFT TO 6KFT. ADDITIONAL CLEARING TAKES
PLACE AROUND SUNSET.

EXTENDED AVIATION DISCUSSION...

THE FORECAST AREA WILL REMAIN IN A WEAKLY FORCED SYNOPTIC
ENVIRONMENT THROUGH MIDWEEK...WITH CHANCES FOR DIURNAL CONVECTION
MAINLY FROM THE BLUE RIDGE WEST...AND SOME MVFR/IFR FOG/STRATUS
DEVELOPMENT AT NIGHT...ESPECIALLY AT KBCB AND KLWB.

&&

.EQUIPMENT...
AS OF 400 AM EDT MONDAY...

THE DEW POINT READING AT KJFZ...RICHLANDS VA AWOS...IS INCORRECT.
AT THIS TIME WE DO NOT KNOW WHEN THIS SENSOR WILL BE REPAIRED.

&&

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

&&

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.