Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 050616
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
216 AM EDT WED AUG 5 2015

.SYNOPSIS...
A WEAK COLD FRONT WILL STALL ACROSS THE CAROLINAS WEDNESDAY. THIS
WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS TO OUR FORECAST
THROUGH MIDWEEK. AN AREA OF LOW PRESSURE IS EXPECTED TO FORM ALONG
THE FRONT THURSDAY AND MOVE NORTHEAST ACROSS THE MID ATLANTIC
REGION FRIDAY... WITH A MUCH BETTER CHANCE FOR WIDESPREAD
THUNDERSTORMS THROUGH THE END OF THE WORKWEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 815 PM EDT TUESDAY...

ISOLATED CONVECTION CONTINUES TO DEVELOP ALONG REMNANT OUTFLOW
BOUNDARIES DRIFTING IN FROM THE WEST. HAVE TWICE MASSAGED POPS TO
ADJUST TO THE LATEST TRENDS. CAPE/INSTABILITY REMAINS QUITE HIGH
WITH TEMPERATURES STILL WELL IN THE 80S AND DEWPOINTS IN THE 60S
TO LOW 70S AND THERE HAS BEEN NO GENERAL WORKOVER OF THE AREA
TODAY FROM ANY WIDESPREAD CONVECTION. THUS...WOULD EXPECT ISOLD
SHRA/TSRA TO CONTINUE TO POP UP ACROSS MUCH OF THE CWA THROUGH THE
EVENING HOURS EVEN UP UNTIL MIDNIGHT. FURTHERMORE...A WEAK FRONTAL
BOUNDARY/BAROCLINIC ZONE EXTENDS FROM SOUTHERN IL THROUGH KY/TN
INTO NORTHERN NC. THIS WILL FURTHER SERVE TO AID IN ISOLD-SCT
CONVECTION THROUGH THE EVENING. ADDITIONAL MODIFICATIONS WILL
LIKELY BE REQUIRED THROUGH THE EVENING. TEMPERATURES AND DEWPOINTS
WERE GENERALLY ON TRACK...WITH ONLY MINOR MODIFICATIONS MADE SOME
MINOR ADJUSTMENTS TO CLOUD COVER.

AS OF 330 PM EDT TUESDAY...
CONVECTION HAS DEVELOPED AHEAD OF A COLD FRONT APPROACHING FROM
THE NORTHWEST. THIS ACTIVITY WILL CONTINUE TO DEVELOP AND MOVE
ACROSS THE REGION THIS EVENING WITH THE GREATEST COVERAGE OF
STORMS EXPECTED TO BE EAST OF THE BLUE RIDGE WHERE THE INSTABILITY
IS GREATEST. SEVERE PARAMETERS ARE MARGINAL SO EXPECT SOME
STRONGER STORMS TO PULSE UP AND PRODUCE HAIL AND GUSTY WINDS. THIS
ACTIVITY WILL TAPER OFF WITH THE LOSS OF HEATING AFTER SUNSET. THE
FRONT WILL NOT PASS CLEANLY THROUGH THE REGION AND WILL SERVE AS A
TRIGGER FOR ANOTHER ROUND OF SCATTERED THUNDERSTORMS TOMORROW
AFTERNOON AS UPPER LEVEL SHORT WAVE ENERGY APPROACHES FROM THE
WEST. INSTABILITY AND DYNAMICS ARE LIMITED TOMORROW SO EXPECTING
GENERAL THUNDERSTORMS WITH A LOW SEVERE THREAT.

TEMPERATURES WILL BE QUITE SIMILAR TO READINGS WE HAVE SEEN OF
LATE WITH MINS TONIGHT AROUND 70 EAST OF THE RIDGE TO LOW/MID 60S
WEST...AND HIGHS WEDNESDAY LOWER 90S EAST TO MIDDLE 80S WEST.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
AS OF 430 AM EDT TUESDAY...

BY THURSDAY MORNING...SHORT WAVE WILL BE COMING OUT OF THE MID
MISSISSIPPI VALLEY. THIS FEATURE WILL CROSS THE FORECAST AREA ON
THURSDAY NIGHT.

SURFACE TO 850 MB BACK TO THE SOUTH AND POSSIBLY THE SOUTHEAST ON
THURSDAY AHEAD OF THE LOW PRESSURE SYSTEM TRACKING ALONG THE FRONT.
THIS FLOW WOULD BE ADVECTING IN PRECIPITABLE WATER VALUES IN THE 1.5
TO 2.0 INCH RANGE. WILL BE INCREASING PROBABILITY OF PRECIPITATION
AND FORECAST RAINFALL AMOUNTS.

BY FRIDAY MORNING...THE LOW WILL BE OVER SOUTHEAST VIRGINIA AND THE
WINDS WILL BE OUT OF THE NORTHWEST IN OUR COUNTY WARNING AREA. THIS
POSITION IS A COMPROMISE BETWEEN THE FARTHER NORTH BUT SLOWER NAM
AND THE FASTER...YET FATHER SOUTH GFS AND IS ALSO CLOSER TO ECMWF
SOLUTION.

DIFFERENCES IN TIMING ALSO SHOW UP IN GUIDANCE FOR TEMPERATURES
WEDNESDAY NIGHT THROUGH FRIDAY. WILL STAY CLOSER TO COOLER VALUES IN
THE WEST AND NORTH FOR MAXIMUM TEMPERATURES ON THURSDAY AND ACROSS
THE FORECAST AREA ON FRIDAY DUE TO ALL THE CLOUDS EXPECTED IN THE
MORNING.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 430 AM EDT TUESDAY...

OVERALL LARGE SCALE PATTERN DOES NOT CHANGE DURING THIS TIME FRAME.
UPPER TROF REMAINS OVER THE EAST. NEXT WEEK THE TROF WILL AMPLIFY
AND BRING A COLD FRONT THROUGH THE REGION AROUND DAY 7...TUESDAY.

AT THE SURFACE...HIGH PRESSURE BUILD IN BEHIND THE DEPARTING LOW ON
FRIDAY NIGHT AND SATURDAY. INCREASING SOUTHWEST FLOW RETURNS ON
MONDAY NIGHT AHEAD OF THE APPROACHING COLD FRONT. ALSO ANTICIPATING
SLIGHTLY WARMER 850 MB TEMPERATURES AHEAD OF THE FRONT ON MONDAY AND
TUESDAY. TEMPERATURES THROUGH THE PERIOD LOOK TO BE CLOSE TO
NORMAL.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 200 AM EDT WEDNESDAY...

WEAK FRONTAL BOUNDARY REMAINS OVER THE AREA. HOWEVER NO
INSTABILITY AVAILABLE FOR SHOWERS. MAIN BY-PRODUCT THROUGH THE
MORNING HOURS WILL BE SCT-BKN CLOUD BASES...MAINLY VFR...BUT CAN`T
RULE OUT SHALLOW LAYER OF MVFR CLOUD ELEMENTS OVER HIGHER RIDGES
VCNTY VA/WV HIGHLANDS.

WEAK SURFACE FRONT IS EXPECTED TO DRIFT TO ALONG THE VA/NC BORDER
TODAY BEFORE STALLING. THIS FRONT WILL THEN BECOME THE FOCUS FOR
SCATTERED TO NUMEROUS SHOWERS/STORMS WEDNESDAY NIGHT INTO
THURSDAY AS WAVE OF LOW PRESSURE MOVES ALONG BOUNDARY. MAIN FOCUS
FOR DEEP CONVECTION TODAY WILL BE OVER MO/KY/TN WHERE WAVE WILL
REACH FIRST...THEN ACTIVITY SPREADING EAST ACROSS THE CENTRAL
APPALACHIANS TONIGHT AND THURSDAY WITH OPPORTUNITY FOR WIDESPREAD
MVFR AND OCNLY IFR CONDITIONS WHICH WILL LINGER FROM THURSDAY INTO
FRIDAY.

UNTIL ARRIVAL OF LOW PRESSURE ANTICIPATE MAINLY VFR THROUGH THE
VALID 24HR TAF PERIOD...MAINLY MID/HIGH CLOUDS WITH SCT AFTERNOON
HIGH BASED CU. WINDS TODAY WILL BE OUT OF THE W-WNW 7-10KTS WITH
LOW END GUSTS WEST OF THE BLUE RIDGE. AFTER SUNSET...TENDENCY WILL
BE FOR WIND DIRECTION TO BECOME MORE NORTHERLY WITH TIME...SPEEDS
DECREASING TO LESS THAN 7 KTS.

MEDIUM TO HIGH CONFIDENCE IN CIGS AND VSBYS THROUGH THE TAF VALID
PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF
VALID PERIOD.

EXTENDED AVIATION FORECAST...
WIDESPREAD MVFR CIGS/VSBYS POSSIBLE THURSDAY AND THURSDAY NIGHT AS
A SYNOPTIC SCALE RAIN EVENT EVOLVES OVER THE REGION. AN AREA OF
LOW PRESSURE IS FORECAST TO RIPPLE EAST ALONG A STATIONARY
FRONTAL BOUNDARY. NORTHEAST WINDS WILL DEVELOP AS A RESULT OF
INDUCED SFC LOW PRESSURE WHICH WILL PASS JUST SOUTH OF THE
FORECAST AREA...THE MID-ATLANTIC REGION RESIDING ON THE COOL SIDE
OF THE FRONTAL BOUNDARY. LOW CIGS MAY LINGER INTO THE DAY FRIDAY
BEFORE THE SURFACE LOW PASSES OFF THE MID ATLANTIC COAST.

FOR THE WEEKEND...DRIER CONDITIONS RETURN WITH MOSTLY VFR
CONDITIONS OUTSIDE OF THE TYPICAL EARLY MORNING FOG IN THE USUAL
SPOTS...E.G...LWB/BCB/LYH. ANY DEEP CONVECTION OVER THE WEEKEND
WILL BE MAINLY CONFINED TO THE MOUNTAINS...COVERAGE ISOLATED.
THE NEXT SYSTEM TO BRING RETURN OF SCATTERED TO NUMEROUS SHOWERS
WILL ARRIVE MONDAY NIGHT OR TUESDAY.

&&

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

&&

$$
SYNOPSIS...MBS
NEAR TERM...MBS/RAB
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...PM


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