Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 150958
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
558 AM EDT WED APR 15 2015

.SYNOPSIS...
A FRONTAL BOUNDARY WILL REMAIN STALLED ACROSS THE CAROLINAS
TODAY INTO AT LEAST THURSDAY. WEAK WAVES OF LOW PRESSURE RIDING
NORTHEAST ALONG THE FRONT WILL COMBINE WITH A STRONG WEDGE OF HIGH
PRESSURE TO KEEP COOL AND DAMP CONDITIONS IN PLACE OVER THE NEXT
COUPLE OF DAYS. SLIGHTLY WARMER AIR RETURNS BY WEEKS END AHEAD OF
ANOTHER COLD FRONT THAT WILL CROSS THE AREA OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 550 AM EDT WEDNESDAY...

SENDING AN UPDATE TO RAISE POPS TO MORE WIDESPREAD LIKELY TO
CATEGORICAL COVERAGE ESPCLY IN THE WEST GIVEN CURRENT EXPANSE OF
RAIN SEEN TO THE SW WITH THE NEXT WAVE. APPEARS LATEST HRRR NOW
BEST IN SLIDING MUCH OF THIS ACROSS THE WESTERN HALF THIS MORNING
BEFORE COVERAGE WEAKENS AND SHIFTS SE AS THE WEDGE DEEPENS FROM
THE NE. ALSO BUMPED UP POPS JUST EAST OF THE BLUE RIDGE WHERE A
PERIOD OF RAIN ALSO LIKELY INTO THIS AFTERNOON BEFORE SOME DRYING
OCCURS FROM THE NE LATER ON. ALSO LOWERED TEMPS A LITTLE MORE
BASED ON CURRENT VALUES AND LIKELY LIMITED RISES UNDER THE
CLOUDS/RAIN INTO MUCH OF THE AFTERNOON. EXPECT SOME SPOTS WILL
ONLY RISE A FEW DEGREES AT BEST WITH HIGHS MOSTLY 50S.

PREVIOUS DISCUSSION AS OF 252 AM EDT WEDNESDAY...

FRONT NOW WELL TO THE SOUTH REMAINS THE FOCUS FOR ADDED PRECIP CHANCES
OVER THE NEXT 24 HOURS AS PIECES OF ENERGY EJECT EAST FROM THE RESIDUAL
5H LOW OVER THE PLAINS AND CAUSE WEAK SURFACE WAVES ALONG THE BOUNDARY.
THIS WHILE LOW LEVEL WEDGING ENHANCES ALONG/EAST OF THE MOUNTAINS AS
HIGH PRESSURE BUILDS TO THE NORTH AND EVENTUALLY DOWN THE MID ATLANTIC
COAST LATER TONIGHT. SQUEEZE PLAY IN BETWEEN THE TWO TO MAKE FOR ADDED
PERIODS OF RAIN ESPCLY SOUTHERN HALF TODAY AND ACROSS THE SOUTH AND
WEST OVERNIGHT.

HOWEVER JUST HOW FAR NORTH SIGNIFICANT RAIN MAKES IT TODAY STILL TRICKY
GIVEN DIFFERING MODEL SOLUTIONS ON TIMING OF THE DEVELOPING WEDGE FROM
THE NE AND STRENGTH OF OVERRUNNING/DIFFLUENCE ALOFT PER JET AXIS
OVERTOP THE CAD THROUGH THE AFTERNOON. LATEST HRRR QUITE WET
ACROSS THE REGION BUT APPEARS RATHER FAST AND PERHAPS OVERDONE
SIMILAR TO THE NAM...WHILE THE GFS/EC AND HIRES GUIDANCE BRING
DEEP MOISTURE INTO THE SOUTH/SW THIS MORNING BEFORE SHUNTING MORE
TO THE SE LATER IN THE DAY. SINCE APPEARS OFF THE LATEST OBS/MSAS
THAT THE WEDGE IS MAKING SOME INROADS FROM THE NORTH WILL FOLLOW
CLOSER TO THE LATEST SREF COMPROMISE AND RAISE POPS TO LIKELY
SOUTHERN TIER AND HIGHER CHANCES WEST WITH ONLY LOW TO SLIGHT
POPS FAR NE TODAY. DOESN`T APPEAR RAINFALL RATES OR FORECAST QPF
WILL BE HIGH ENOUGH TO CAUSE THE NEED FOR ANY FLOOD WATCHES AT
THIS TIME OVER THE SW GIVEN LESS UPSLOPE BUT ANOTHER GOOD HALF TO
AN INCH POSSIBLE NW NC MOUNTAINS. LEFT TEMPS QUITE COOL GIVEN THE
WEDGE UNDER LOW CLOUDS/RAIN WITH HIGHS ONLY RISING A BIT INTO THE
50S...TO PERHAPS AROUND 60 IN SPOTS OVER THE FAR WEST...AND NE
WHERE SOME BREAKS IN THE LOW DECK COULD OCCUR AT TIMES.

UPPER SUPPORT ELONGATES OUT OVERNIGHT AS THE REGION REMAINS STUCK
BETWEEN HIGH PRESSURE NOSING IN FROM THE NE AND RESIDUAL LOW PRESSURE
BACK ALONG THE MISSISSIPPI RIVER. THIS SHOULD ALLOW THE FLOW TO
BECOME MORE OF A SE UPSLOPE COMPONENT OVER THE SW AS ANOTHER WAVE
OF LIFT PUSHES EAST TOWARD THE MOUNTAINS FROM SHORTWAVE ENERGY
PASSING WELL TO THE NW. SOME SOLUTIONS ESPCLY THE NAM/EC BASICALLY
CONNECT THE AXIS OF DEEPER MOISTURE/LIFT FROM TODAY OVER THE SE TO
THE NEXT IMPULSE HEADING IN FROM THE WEST. THIS WOULD KEEP RAIN
GOING FROM SE WEST VA ACROSS EXTREME SW VA INTO NW NC FOR MUCH OF
THE NIGHT WHILE HAVING THINGS DRY OUT TO SOME DEGREE OVER THE NE.
AGAIN THINK THIS IS OVERDONE BUT EXPECT MORE RAIN TO ARRIVE WEST
LATE SO UPPED POPS TO HIGHER CHANCE WESTERN HALF...AND KEPT
LIKELY/CHANCE GOING SW OVERNIGHT FOR BETTER SE FLOW. LOWS MOSTLY
ON THE COOL SIDE WITH 40S MOST SPOTS UNDER THE CAD BY MORNING.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 400 AM EDT WEDNESDAY...

UNSETTLED WEATHER WILL CONTINUE INTO THE WEEKEND. A 1033 MB HIGH
PRESSURE WILL WEDGE DOWN THE EAST COAST THURSDAY AND WEAKEN AS IT
SLIDE EAST THURSDAY NIGHT INTO FRIDAY.  MODELS ARE STILL DISPLAYING
A SURFACE REFLECTIONS OFF THE SOUTHEAST COAST...WHICH INTENSIFIES
INTO A SURFACE LOW AND LIFTS NORTHWARD INTO FRIDAY.

THE PRESSURE GRADIENT BETWEEN THE HIGH PRESSURE TO THE NORTH AND LOW
PRESSURE TO SOUTH WILL BRING A STRONG FETCH OF ATLANTIC MOISTURE
TOWARDS THE SOUTH-CENTRAL APPALACHIANS. MAINTAIN HIGHEST POPS ALONG
THE BLUE RIDGE THURSDAY. UNDER PLENTY OF CLOUDS...LEANED TOWARDS THE
COOLER MOS FOR HIGH TEMPERATURES THURSDAY WITH READINGS FROM THE
UPPER 40S IN THE MOUNTAINS TO THE UPPER 50S IN THE PIEDMONT.

FOR THURSDAY NIGHT...LEANED POPS TOWARDS THE NAM WITH HIGHER POPS
ALONG THE BLUE RIDGE...THEN TAPERING OFF BY 12Z FRIDAY. LOW
TEMPERATURES THURSDAY NIGHT WILL RANGE FROM THE LOWER 40S IN THE
NORTHWEST MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT.

ON FRIDAY...THE COASTAL LOW LIFTS NORTH INTO THE ATLANTIC
OCEAN...WHILE A WHILE WEAK HIGH PRESSURE DRIFTS OVER THE REGION. A
SHORTWAVE WILL ROTATE EAST AROUND THE UPPER TROUGH FRIDAY INTO
FRIDAY NIGHT. A WEAK COLD FRONT/SURFACE TROUGH MOVES INTO THE AREA
FRIDAY AFTERNOON AND WASHES OUT. HIGH TEMPERATURES ON FRIDAY WILL BE
WARMER THAN THURSDAY WITH VALUES VARYING FROM THE UPPER 50S IN THE
MOUNTAINS TO LOWER 70S IN THE PIEDMONT. WITH DRIER AIR MOVING IN
ALOFT CUT BACK POPS FOR FRIDAY NIGHT TO SLIGHT CHANCE. LOW
TEMPERATURES FRIDAY NIGHT WILL DROP INTO THE UPPER 40S IN THE WEST
TO THE LOWER TO MID 50S IN THE EAST.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 245 PM EDT TUESDAY...

A COLD FRONT IS EXPECTED TO STALL ACROSS THE OHIO VALLEY ON SATURDAY
WITH A POSSIBLE CLOSED LOW HOVERING OVER THE OZARKS. THERE WILL
REMAIN A GOOD FLOW OF MOISTURE INTO THE REGION FROM THE GULF THROUGH
THE WEEKEND TO KEEP HIGH CHANCE POPS. THE MAIN QUESTION REGARDING
RAIN IS TIMING. HIGH PRESSURE DRIFTS OVER THE REGION EARLY NEXT
WEEK TO BRING AN END TO THE RAIN. WITH MORE CLOUDS AND RAIN IN THE
FORECAST...TEMPERATURES WILL BE COOL BUT NOT TO FAR REMOVED FROM
NORMAL.

&&

.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
AS OF 100 AM EDT WEDNESDAY...

CIGS HAVE SLOWLY IMPROVED TO AT LEAST MVFR IN MANY LOCATIONS
OVERNIGHT WITH THE EXCEPTION OF SPOTS ALONG THE RIDGES WHERE
IFR/LIFR IN STRATUS/FOG/DZ PERSISTS. HOWEVER EXPECT ANY BRIEF
DRYING BEHIND THE INITIAL EXITING WAVE TO END TOWARD DAYBREAK AS
ANOTHER IMPULSE PUSHES DEEPER MOISTURE INCLUDING -RA BACK NE INTO
THE AREA. AHEAD OF THIS EXPECTING VARYING CONDITIONS FROM MORE
MVFR/IFR IN LOW CLOUDS/FOG OVER THE MOUNTAINS TO PERHAPS MORE HIGH
END MVFR FROM KROA AND POINTS EAST AS DRY AIR UNDER HIGH PRESSURE
TO THE NORTH WEDGES IN.

SQUEEZE PLAY CONTINUES ON WEDNESDAY WITH HIGH PRESSURE
STRENGTHENING EAST OF THE BLUE RIDGE AND MOISTURE TRYING TO RIDE
IN FROM THE SW WITH THE NEXT IMPULSE. HOW FAR NORTH/NE TO TAKE
PRECIP REMAINS LOW CONFIDENCE BUT APPEARS THE BEST CHANCES OF
SEEING VSBY REDUCTIONS IN -RA ARE ALONG THE KBLF-KBCB-KDAN
CORRIDOR AND POINTS SW INTO WEDNESDAY AFTERNOON. THIS SHOULD ALSO
BE WHERE MORE IN THE WAY OF CONTINUING IFR TO MVFR CONDITIONS
PREVAIL WITH PERHAPS A PERIOD OF VFR AT KLYH WITH KROA MOSTLY MVFR
WITH ONLY SPOTTY -RA.

MODELS DISAGREE ON HOW FAST THE PRECIP ON WEDNESDAY GETS SHUNTED
TO THE SOUTH WITH THE NAM QUITE WET INTO THURSDAY WITH OTHERS
SHOWING A BREAK WED NIGHT AND THEN MORE -RA WITH ANOTHER FEATURE
ON THURSDAY. EITHER WAY APPEARS OVERALL SUB-VFR WILL BE THE RULE
WITH ONLY PERIODIC IMPROVEMENT POSSIBLY OCCURRING ACROSS NORTHERN
SECTIONS...AFFECTING THE KLWB-KLYH ROUTE.

EXTENDED AVIATION...

THE WEDGE REMAINS IN PLACE INTO FRIDAY MORNING WITH CONTINUED
IFR TO MVFR CEILINGS AND OCNL MVFR VSBYS IN -RA/DZ/FOG.

ON FRIDAY...LOW LEVEL FLOW TURNS TO THE SOUTHWEST IN ADVANCE OF A
COLD FRONT. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE
POSSIBLE IN THE AFTERNOON...ESPECIALLY ONCE THE WEDGE BREAKS.

ON SATURDAY THE FRONT COMES THROUGH SHOWERS AND THUNDERSTORMS.
EXPECTING OCCASIONAL PERIODS OF MVFR CONDITIONS UNTIL THE FRONT
PASSES.

SUNDAY A DRIER AIR MASS WILL PUSH INTO THE REGION ALONG WITH HIGH
PRESSURE BEHIND THE FRONT. THIS IS A SLOWER TIMING THAN THE PAST
FEW RUNS OF THE MODELS. ONCE THIS DRIER AIR ARRIVES...CONDITIONS
SHOULD IMPROVE BACK TO VFR.

&&

.HYDROLOGY...
AS OF 400 AM EDT WEDNESDAY...

RUNOFF FROM EARLIER HEAVY RAINFALL OF AROUND 2 INCHES IN SPOTS
ACROSS THE GREENBRIER VALLEY AND VIRGINIA HIGHLANDS WILL CONTINUE
TO FILTER INTO MAINSTEM WATERWAYS AND RESULT IN NEAR BANKFULL
CONDITIONS FOR MANY STREAMS AND CREEKS TODAY. HOWEVER LATEST
FORECASTS SUGGEST THAT MOST RIVERS INCLUDING THE GREENBRIER AT
ALDERSON AND THE JAMES DOWNSTREAM FROM LICK RUN WILL REMAIN BELOW
FLOOD STAGE BASED ON THIS EARLIER RAINFALL.

ADDITIONAL RAIN WILL SPREAD BACK ACROSS PARTS OF THE REGION TODAY
RESULTING IN ANOTHER HALF TO ONE INCH ACROSS THE MOUNTAINS OF
NORTHWEST NORTH CAROLINA AS WELL AS PORTIONS OF SOUTHWEST
VIRGINIA. HOWEVER RAINFALL RATES AND FORECASTED QPF SHOULD NOT BE
ENOUGH TO CAUSE FLOOD PROBLEMS BUT WILL NEED TO BE WATCHED GIVEN
DIFFERING FLASH FLOOD GUIDANCE ACROSS THE REGION. ELSEWHERE TOTALS
ARE EXPECTED TO REMAIN RATHER LIGHT WITH TOTALS RANGING FROM A
QUARTER/HALF INCH OVER THE SW TO LESS THAN A TENTH OF AN INCH
ALONG THE INTERSTATE 64 CORRIDOR.

&&

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

&&

$$
SYNOPSIS...AMS/JH/WP
NEAR TERM...JH
SHORT TERM...KK
LONG TERM...RCS
AVIATION...AMS/JH/MBS
HYDROLOGY...WP



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