Area Forecast Discussion
Issued by NWS Blacksburg, VA

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 300620
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
220 AM EDT SAT APR 30 2016

.SYNOPSIS...
LOW PRESSURE SHIFTS FROM THE SOUTHERN PLAINS INTO THE WESTERN OHIO
VALLEY THROUGH SUNDAY. A WARM FRONT WILL MOVE NORTH AHEAD OF THIS
SYSTEM AND ACROSS THE REGION BY SUNDAY...WITH THE COLD FRONT
MOVING THROUGH MONDAY.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 200 AM EDT SATURDAY...

WEDGE FRONT VERY WELL DEPICTED IN THE LAPS ANALYSIS AND GOES-R
PROVING GROUND MVFR/IFR GRAPHIC...NOW NEAR A LWB-ROA-MWK. LOW
CLOUDS SPREAD INTO THE REGION VERY QUICKLY BEHIND THE FRONT WITH A
SHARP LINE NOTED FROM JUST OVC250 CIGS AT BCB/BLF/LWB TO CIGS AOB
100 ROA/DAN/LYH. MODELS CONTINUE TO MOVE WEDGE FRONT WEST THROUGH
THE REST OF THE CWA BY THE 12Z-15Z TIME FRAME. AS THE WEDGE
DEEPENS AND MID-LEVEL MOISTURE BEGINS TO SPREAD OVER TOP OF THE
SHALLOW WEDGE...WOULD EXPECT -DZ TO EVOLVE...ESPECIALLY IN UPSLOPE
AREAS ALONG THE BLUE RIDGE AND ALLEGHANY FRONT. BONAFIDE -RA OR
-SHRA SHOULD BEGIN TO SPREAD INTO THE REGION LATER IN THE
AFTERNOON AS THE FIRST OF SEVERAL SHORT WAVES EMANATING FROM A
PERSISTENT UPPER LOW IN THE SOUTHWEST U.S. EJECT ENE-NE ACROSS THE
REGION. THE WEDGE COULD POTENTIALLY BREAK LATE IN THE DAY TOWARD
THE KBLF/KMKJ/KTNB AREA...BUT MOST LIKELY THIS WILL NOT OCCUR
UNTIL AFT 00Z.

T/TD GRIDS GENERALLY ON TARGET THIS HOUR. ADJUST POPS DOWNWARD
OVERNIGHT...THEN WENT ALONG WITH ADVERTISED LIKELY POPS BY 15Z
ACROSS MUCH OF THE REGION WEST OF THE BLUE RIDGE. EITHER HIGH OR
LOW CLOUDS ENVELOPE MUCH OF THE REGION THIS HOUR...SO HAVE
INCREASED CLOUDS TOWARD 100 PERCENT FROM THIS POINT FORWARD IN
TIME.

AS OF 845 PM EDT FRIDAY...

SQUEEZE PLAY OF CLOUDS WILL OCCUR OVERNIGHT AS LOW LEVEL MOISTURE
WITHIN THE PERSISTENT FAR EASTERN WEDGE OOZES BACK TOWARD THE BLUE
RIDGE WHILE MID/HIGH CANOPY INCREASES FROM THE WEST AHEAD OF
RETURN WARM ADVECTION TO THE SW. LATEST NAM ALSO QUITE MOIST WITH
THE WEDGE ENHANCING OVERNIGHT IN THE WAKE OF PASSING SHORTWAVE
ENERGY TO THE NORTH AND REINFORCING HIGH PRESSURE BUILDING SOUTH.
FORECAST SOUNDINGS FROM OTHER SHORT TERM SOLUTIONS ALSO SHOW QUITE
A BIT OF TRAPPED BOUNDARY LAYER MOISTURE ESPCLY NE. THEREFORE BEEFED
UP CLOUDS AND INCLUDED SOME PATCHY DRIZZLE BACK WEST TO NEAR
ROANOKE AFTER MIDNIGHT ALONG WITH PATCHY FOG. MAIN ASPECT WEST OF
THE BLUE RIDGE WILL BE WITH DEEPENING CLOUD CANOPY ALTHOUGH
APPEARS ENOUGH DRY AIR TO KEEP THINGS DRY OVERNIGHT ESPCLY GIVEN
THE UPSTREAM MCS DIVING WELL TO OUR SOUTH. LATEST HRRR ABOUT THE
ONLY GUIDANCE SHOWING ANY RAINFALL OVER THE FAR WEST LATE BUT
APPEARS OVERDONE GIVEN ONLY WEAK FORECAST SOUTH/SE FLOW AND LITTLE
SUPPORT ALOFT UNTIL SATURDAY. THUS WILL KEEP TREND OF BECOMING
MOSTLY CLOUDY OVERNIGHT...BUT MAINLY DRY OUTSIDE OF DRIZZLE...WITH
LOWS IN THE 50S...EXCEPT PERHAPS A FEW COOLER 40S WESTERN VALLEYS
IF CLOUDS STAY THIN LONGER.


PREVIOUS DISCUSSION AS OF 250 PM EDT FRIDAY...

WEDGE STILL HOLDING ON OVER THE PIEDMONT MAINLY EAST OF LYNCHBURG AS
FAR AS CLOUDS GO. TEMPERATURES RANGING WIDELY FROM AROUND 80 IN THE
FOOTHILLS OF NORTH CAROLINA...AS WELL AS PORTIONS OF THE ROANOKE AND
NEW RIVER VALLEY...TO AROUND 60 OUT TOWARD BUCKINGHAM TO KEYSVILLE.

AS WE HEAD THROUGH THIS EVENING...SKIES WILL STAY CLEAR TO PARTLY
CLOUDY EXCEPT MOSTLY CLOUDY NORTHEAST OF LYH.

MODELS ARE FAVORING SOME TURNING TO THE SOUTHEAST OF THE WINDS
OVERNIGHT WITH LOW CLOUDS MOVING WESTWARD AGAIN WELL AFTER MIDNIGHT.
SOME PATCHY DRIZZLE POSSIBLE NEAR THE BLUE RIDGE...BUT UPSLOPE
COMPONENT AND FORECAST SOUNDINGS DO NOT SUPPORT MUCH.

WILL HAVE TO SEE WHERE THE MCS OVER WRN TN THIS AFTERNOON MOVES.
MODELS TAKE IT EAST TO NORTHEAST TOWARD ERN KY BY 12Z
SATURDAY...WEAKENING IT. SHOULD START TO SEE SHOWERS MOVE INTO THE
MOUNTAINS OF WV/FAR SW VA AROUND 8-10AM...WITH LIGHT RAIN POSSIBLE
IN THE WEDGE. THINK THE HIGH OVER GREAT LAKES BEHIND SHORTWAVE
TONIGHT WILL BRING A STRONGER WEDGE TOWARD OUR AREA SATURDAY...AS
EVIDENCED BY THE SFC LI FIELD IN THE MODELS. AS SUCH SHOULD SEE A
COOLER DAY OVER MOST OF THE FORECAST AREA WITH HIGHS IN THE 60S.
OUTSIDE THE WEDGE LOOKING FOR HIGHS IN THE LOWER 70S.

MODELS FAVOR THE AFTERNOON WITH BETTER LOW LVL CONVERGENCE/UPPER
DIVERGENCE MOVE ACROSS WV/FAR WRN VA ALONG THE FRONT. THEREFORE KEPT
LIKELY TO LOW CATEGORICAL POPS GENERALLY ALONG/WEST OF THE BLUE
RIDGE TO HIGH CHANCE EAST. THUNDER THREAT WILL BE CONFINED TO A FAR
SW VA TO NW NC MTN LINE IN THE AFTERNOON...AND ISOLATED. NO SEVERE
THREAT EXPECT TOMORROW DUE TO WEDGE.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
AS OF 300 PM EDT FRIDAY...

UNSETTLED WEATHER WITH PERIOD OF SHOWERS AND THUNDERSTORMS EXPECTED
FOR WEEKEND INTO EARLY NEXT WEEK. ALOFT...AN UPPER TROUGH DEVELOPS
IN THE EAST. LOW PRESSURE WITH AN ASSOCIATED WARM FRONT EXTENDING
EASTWARD AND COLD FRONT FRONT TRAILING SOUTH WILL MOVES OUT OF THE
MISSISSIPPI VALLEY AND SLIDES INTO THE MID ATLANTIC REGION.

A WARM FRONT WILL LIFT NORTH ACROSS THE REGION SATURDAY EVENING INTO
SATURDAY NIGHT. WIDESPREAD SHOWERS AND THUNDERSTORMS WILL DAMPEN OUR
SATURDAY EVENING INTO SUNDAY MORNING. LOW TEMPERATURES SATURDAY
NIGHT WILL RANGE FROM THE LOWER 50S IN THE NORTH TO AROUND 60
DEGREES IN THE SOUTH.

LOW PRESSURE WILL MOVE TO OUR NORTH SUNDAY INTO SUNDAY NIGHT. THERE
ARE INDICATIONS THAT BY SUNDAY AFTERNOON...THE WEDGE WILL BE LOSING
ITS GRIP ON THE AREA AND WE WILL ENTER THE UNSTABLE WARM SECTOR
AHEAD OF THE COLD FRONT TRAILING THE LOW. DYNAMIC SUPPORT...WITH
HEALTHY CAPES AND SOME SHEAR MAY BE ADEQUATE TO CREATE SOME
ORGANIZED CONVECTION SUNDAY. THE DAY THREE CONVECTIVE OUTLOOK PLACED
OUR AREA UNDER MARGINAL THREAT FOR SEVERE WEATHER. THERE IS ALSO THE
POTENTIAL FOR HYDRO ISSUES AS PWATS WILL BE RUNNING WELL OVER ONE
INCH AND LOCALLY HEAVY RAIN WILL BE ADDED TO OUR RECENT WET SPELL.
TRAINING OF CELLS AND RAIN RATES WILL BE IMPORTANT WITH THESE STORMS
WITH ANY FLOODING POTENTIAL. HIGH TEMPERATURES WILL TRICKY WITH
CLOUD COVER AND PRECIPITATION. HIGHS ON SUNDAY WILL VARY FROM THE
MID 60S IN THE NORTHWEST MOUNTAINS TO THE MID 70S IN THE SOUTH.

A COLD FRONT WILL PUSH EAST THROUGH THE AREA SUNDAY NIGHT INTO
MONDAY. LOW TEMPERATURES SUNDAY NIGHT WILL GENERALLY BE IN THE LOWER
50S IN THE WEST TO NEAR 60 DEGREES IN THE EAST. BY MONDAY
AFTERNOON...THE FRONT WILL BE THROUGH THE REGION WITH GENERALLY
IMPROVING CONDITIONS EAST OF THE BLUE RIDGE...BUT SOME LINGERING
MOISTURE IN NORTHWEST UPSLOPE FLOW SUPPORTS ISOLATED SHOWERS TO THE
WEST. HIGHS ON MONDAY WILL WARM INTO THE UPPER 50S IN THE NORTHWEST
TO THE MID 70S IN THE PIEDMONT. HIGH PRESSURE WILL BUILD EAST OUT OF
THE OHIO VALLEY INTO OUR AREA MONDAY NIGHT. LOW TEMPERATURES MONDAY
NIGHT WILL DROP INTO THE LOWER 40S IN THE WEST TO THE LOWER 50S IN
THE EAST.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 300 PM EDT FRIDAY...


A WAVY FRONTAL BOUNDARY REMAINS STALLED TO OUR SOUTH TUESDAY INTO
WEDNESDAY. AS SEVERAL LOW PRESSURE CENTER RIDE NORTHWARD ALONG THE
BOUNDARY EXPECT ROUNDS OF SHOWERS AND A FEW THUNDERSTORMS. THE
TIMING OF THE SIGNIFICANT SHORTWAVES AND ASSOCIATED MOISTURE LIFTING
NORTHEAST ALONG THE UPPER FLOW REMAINS A CHALLENGE. LOOKS LIKE
DEEPER MOISTURE PUSHES FAR ENOUGH NORTH WITH A LOW ON TUESDAY TO
PROVIDE US WITH UNSETTLED WEATHER. THIS IS SUPPORTED BY GFS AND
ECMWF...DESPITE THE DIFFERENCES IN LOW PRESSURE AND ITS TIMING ALONG
WITH THE STRENGTH OF SHORTWAVE DIGGING SOUTH TO OUR WEST IN OHIO
VALLEY. HIGH TEMPERATURES TUESDAY WILL VARY FROM THE UPPER 50S IN
THE MOUNTAINS TO THE LOWER 70S IN THE PIEDMONT. DECIDED TO KEEP
SCATTERED POPS FOR TUESDAY NIGHT. LOW TEMPERATURES TUESDAY NIGHT
INTO WEDNESDAY MORNING WILL RANGE FROM THE MID 40S IN THE WEST TO
THE LOWER 50S IN THE EAST. A COLD FRONT APPROACHES FROM THE WEST ON
WEDNESDAY AND MOVES ACROSS REGION ON WEDNESDAY INTO THURSDAY. WITH
UNCERTAINTY...HELD ON TO THE ISOLATED TO SCATTERED SHOWERS WITH THIS
BOUNDARY. HIGHS ON WEDNESDAY AND THURSDAY WILL BE IN THE LOWER TO
MID 60S IN THE WEST TO THE UPPER 60S TO LOWER 70S IN THE EAST.
OVERNIGHT LOW TEMPERATURES WILL DROP TO AROUND 40 IN THE MOUNTAINS
TO NEAR 50 IN THE PIEDMONT. DRIER AIR ARRIVE THURSDAY NIGHT INTO
FRIDAY ON A WEST TO NORTHWEST FLOW.

&&

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

WEDGE FRONT VERY WELL DEPICTED IN THE LAPS ANALYSIS AND GOES-R
PROVING GROUND MVFR/IFR GRAPHIC...NOW NEAR A LWB-ROA-MWK. LOW
CLOUDS SPREAD INTO THE REGION VERY QUICKLY BEHIND THE FRONT WITH A
SHARP LINE NOTED FROM JUST OVC250 CIGS AT BCB/BLF/LWB TO CIGS AOB
100 ROA/DAN/LYH. MODELS CONTINUE TO MOVE WEDGE FRONT WEST THROUGH
THE REST OF THE CWA BY THE 12Z-15Z TIME FRAME. AS THE WEDGE
DEEPENS AND MID-LEVEL MOISTURE BEGINS TO SPREAD OVER TOP OF THE
SHALLOW WEDGE...WOULD EXPECT -DZ TO EVOLVE...ESPECIALLY IN UPSLOPE
AREAS ALONG THE BLUE RIDGE AND ALLEGHANY FRONT. BONAFIDE -RA OR
-SHRA SHOULD BEGIN TO SPREAD INTO THE REGION LATER IN THE
AFTERNOON AS THE FIRST OF SEVERAL SHORT WAVES EMANATING FROM A
PERSISTENT UPPER LOW IN THE SOUTHWEST U.S. EJECT ENE-NE ACROSS THE
REGION. THE WEDGE COULD POTENTIALLY BREAK LATE IN THE DAY TOWARD
THE KBLF/KMKJ/KTNB AREA...BUT MOST LIKELY THIS WILL NOT OCCUR
UNTIL AFT 00Z.

CIGS STILL VFR AT KBLF/KLWB/KBCB. GIVEN THAT KROA IS ALREADY
LIFR...WOULD EXPECT KBCB TO TREND THAT WAY WITHIN THE NEXT TWO
HOURS. SHOULD TAKE UNTIL 08Z-10Z TO REACH KLWB...AND PROBABLY
12Z-13Z FOR KBLF. ONE THE WEDGE EVOLVES THE REGION FROM THE
EAST...EXPECT IFR-LIFR CIGS TO HOLD UNTIL 18Z OR SO...THEN BECOME
MOSTLY LOW END MVFR. VSBYS SHOULD DROP INTO THE MVFR CATEGORY BY
DAYBREAK...EXPECT POSSIBLY KBLF...WHICH SHOULD HOLD ONTO VFR UNTIL
LATER IN THE DAY. -DZ SHOULD EVOLVE IN UPSLOPE AREAS NEAR THE BLUE
RIDGE/ALLEGHANY FRONT BY EARLY TO MID-MORNING...THEN -RA OR-SHRA
BY 18Z AND BEYOND AS NOTED ABOVE. STILL DO NOT FORESEE MUCH WORSE
THAN MVFR VSBYS THROUGH THIS TAF VALID PERIOD.

WINDS LIGHT/VARIABLE WEST OF THE WEDGE. OTHERWISE...NORTHEAST
6-9KTS EAST OF THE BLUE RIDGE...EAST-SOUTHEAST TO SOUTHEAST
7-10KTS WEST OF THE BLUE RIDGE...WITH LOW END GUSTS DEVELOPING
DURING THE MORNING KBLF VICINITY...AND POSSIBLY OTHER
LOCATIONS...ESPECIALLY EAST OF THE BLUE RIDGE.

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

EXTENDED AVIATION DISCUSSION...

WIDESPREAD SHOWERS WITH MVFR INCLUDING LOCALLY IFR CONDITIONS
PERSIST OVERNIGHT INTO SUNDAY MORNING...LIKELY IMPROVING TO
MVFR/VFR BY AFTERNOON AS THE WEDGE ERODES...SHIFTS NORTHEAST AND
THE REGION MOVES INTO THE WARM SECTOR. SUNDAY AFTERNOON BRINGS THE
POTENTIAL FOR SCATTERED CONVECTION...SOME POSSIBLY STRONG TO
SEVERE AS SHORT WAVE ENERGY TRACKS NORTHEAST ACROSS THE REGION IN
THE WARM/UNSTABLE AIR MASS. SITUATION APPEARS SOMEWHAT SIMILAR TO
WHAT WAS OBSERVED THURSDAY ACROSS THE REGION...BUT PERHAPS MORE
ACTIVITY NORTH-WEST OF THE BLUE RIDGE THIS TIME AROUND THAN WHAT
WAS OBSERVED SUNDAY. SFC LOW PRESSURE TRACKS NORTHEAST ACROSS
GA/SC/NC SUN NIGHT-TUE...LIKELY PROLONGING SUB-VFR CIGS AND
POTENTIALLY LEAVING SOME LIGHT PRECIPITATION ACROSS THE
REGION...ESPECIALLY EAST OF THE BLUE RIDGE. FOR THE MID AND LATER
PART OF NEXT WEEK...A DEEP UPPER LOW IS EXPECTED TO DROP DOWN
ACROSS THE GREAT LAKES INTO THE APPALACHIANS AND MID-ATLANTIC
REGION...WHICH WILL LEAVE THE REGION WITH VARIABLE
CLOUDINESS...SHOWERS...AND PERIODS OF SUB-VFR CONDITIONS.

&&

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

&&

$$
SYNOPSIS...JH/WP
NEAR TERM...JH/RAB/WP
SHORT TERM...KK
LONG TERM...KK
AVIATION...DS/RAB/WP



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