322
FXUS61 KRNK 230145
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
945 PM EDT WED MAY 22 2013
SYNOPSIS
A LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE CENTRAL PLAINS INTO
THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL PUSH A COLD FRONT
THROUGH THE AREA THURSDAY INTO THURSDAY EVENING...FOLLOWED BY
HIGH PRESSURE ON FRIDAY.
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
AS OF 925 PM EDT WEDNESDAY...
CONVERGENCE ZONE ASSOCIATED WITH THE BAND OF EARLIER CONVECTION
OVER THE MOUNTAINS REMAINS STUCK ALONG THE FOOTHILLS THIS EVENING
UNDER BROAD SW FLOW ALOFT PER EVENING SOUNDINGS. HOWEVER EXPECTING
A GRADUAL PROPAGATION OF SHRA/TSRA TO THE EAST VIA OUTFLOW
ALTHOUGH AN AXIS OF HEAVIER SHRA MAY CONTINUE TO REMAIN LOCKED IN
ACROSS THE SOUTH FOR A WHILE LONGER. LATEST GUIDANCE ALSO TENDING
TO KEEP POPS GOING ACROSS THE CENTRAL/EAST BEFORE ANOTHER BAND
ARRIVES FROM THE WEST AHEAD OF THE FRONT LATE. THUS HAVE UPPED
POPS TO LIKELYS FOR A FEW MORE HOURS IN ALL EXCEPT THE FAR NORTH
AND EAST WITH A CONTINUED HEAVY RAIN THREAT PER MOIST PWATS AND
SOME TRAINING OF CELLS. SEVERE THREAT LOOKS QUITE ISOLATED AT BEST
GIVEN MORE SHALLOW NATURE TO STORMS AS INSTABILITY CONTINUES TO
WANE SO WILL ADJUST THE HWO TO HIGHLIGHT MORE OF A HEAVY RAIN
THREAT. OTRW APPEARS THAT PERSISTENT CLDNS COMBO WITH LINGERING
SHRA WILL LIMIT FOG COVERAGE WITH PATCHY COVERAGE ESPCLY WEST
LATE. ADJUSTED LOW TEMPS DOWN GIVEN COOLING FROM RAINFALL/OUTFLOW
BUT STILL MUGGY WITH LOWS MAINLY UPPER 50S TO LOWER 60S.
SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/
AS OF 300 PM EDT WEDNESDAY...
ECMWF/GFS BLEND FOLLOWED THIS PERIOD...AS TIMING LOOKS GOOD FOR THE
FRONT ARRIVING IN THE AREA THURSDAY MORNING AND EXITING BY THURSDAY
EVENING IN THE EAST. MAIN FORCING WILL BE WEAKENING BUT ENOUGH LOW
LVL CONVERGENCE AND DECENT FLOW ALOFT TO MAINTAIN A BROKEN LINE OF
SHOWERS AND STORMS INTO THE MTNS THURSDAY MORNING SHIFTING EAST TO
THE PIEDMONT BY MIDDAY. DRY SLOT WORKS INTO THE SOUTHWEST AROUND
LATE EVENING WITH STRONG SHORTWAVE FOLLOWING INTO WV/VA BY FRIDAY
MORNING. THIS WILL ENHANCE THE SHOWER ACTIVITY IN THE WV MTNS
ALTHOUGH AIRMASS OVERALL WILL BE DRYING OUT.
SVR THREAT THURSDAY WILL BE EAST WHERE SOME SUN MAY OCCUR EARLY
ENOUGH TO DESTABILIZE THE AIRMASS. NOT OUTLOOKED THOUGH BUT CANNOT
RULE OUT AN ISOLATED WIND GUST OVER 50 MPH OR HAIL.
THE CHANGE IN AIRMASS WILL BE NOTICEABLE FRIDAY AS DEWPOINTS DROP
INTO THE 30S AND 8H TEMPS DROP TO NEAR ZERO. NOT SEEING MUCH CLOUD
COVER AFTER LATE MORNING SO SUNSHINE MAY WORK TO BALANCE OUT THE
CAA. STILL LEANING TOWARD THE ECMWF MOS WITH LOWER TO MID 60S
MOUNTAINS TO LOWER TO MID 70S EAST. DOWNSLOPE MAY ENHANCE THE
HEATING AS WELL...AND COULD BE SEVERAL DEGREES WARMER BUT BREEZY
CONDITIONS AT TIMES HINDERS WARM UPS.
NOT OF THE QUESTION TO SEE SOME SMALL HAIL PRODUCING SHOWERS ACROSS
THE ALLEGHANY HIGHLANDS FRIDAY AS THE UPPER TROUGH AXIS MOVES
ACROSS...BUT AGAIN APPEARS GFS/ECMWF DRY IT OUT TOO MUCH.
FRIDAY NIGHT STAYS BREEZY AS TEMPS DROP INTO THE 30S/40S. NOT SEEING
FROST/FREEZE ISSUES AT THIS POINT GIVEN WINDS BUT A FEW HIGHER
ELEVATIONS LIKE HOT SPRINGS COULD SLIP TOWARD 32F SAT MORNING.
SATURDAY WILL BE FALL LIKE WITH MOSTLY SUNNY SKIES AND NW BREEZE.
HIGHS WILL RANGE FROM THE MID 60S MOUNTAINS TO LOWER 70S EAST.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
AS OF 1245 PM EDT WEDNESDAY
EXPECT COOL TROUGH TO LINGER INTO SUNDAY BEFORE LIFTING EAST.
MEANWHILE A STRONG TROUGH DIGS INTO THE PACIFIC NORTHWEST BY MONDAY
WITH INCREASING HEIGHTS ARRIVING OVER OUR AREA NEXT WEEK. THE
WEATHER PATTERN WILL BE MAINLY DRY SAT NIGHT-MONDAY...BUT AS WE CAN
SEE WITH A WESTERLY FLOW ALOFT THE CHANCE THAT CONVECTION THAT FIRES
ALONG A WARM FRONT OVER THE OHIO/MID MISSISSIPPI VALLEY COULD SHIFT
EAST AND AFFECT OUR MOUNTAINS.
WILL LEAN TOWARD AN ECMWF/WPC BLEND SOLUTION. THIS WILL KEEP THE
CHANCE POPS IN THE AREA BY MONDAY AFTERNOON THROUGH TUESDAY. THE
WARM FRONT LIFTS NORTH TOWARD THE GREAT LAKES BY MIDWEEK WITH
HEIGHTS CONTINUING TO BUILD. AT THE SFC...HIGH PRESSURE WILL BE
SITUATED ACROSS THE MID ATLANTIC COAST THEN SHIFT OFF THE COAST
MIDWEEK. DEWPOINTS WILL BE INCREASING AGAIN BY NEXT WEEK WITH TEMPS
WARMING BACK TO NORMAL OR JUST ABOVE.
AVIATION /02Z THURSDAY THROUGH MONDAY/
AS OF 605 PM EDT WEDNESDAY...
TWO BANDS OF CONVECTION ONGOING ATTM WITH OUTFLOW DRIVEN STRONGER
STORMS NEARING KLYH/KDAN AND THE NEXT WEAKER AXIS OF MOSTLY SHRA
ALONG THE WESTERN SLOPES. IN BETWEEN MOSTLY VFR WITH A FEW LIGHTER
SHRA REMAINING IN THE RAIN COOLED AIR ALONG/WEST OF THE BLUE
RIDGE. EXPECT WILL SEE A PERIOD OF SHRA/ISOLATED TSRA AFFECT THE
EASTERN SITES WITH BRIEF MVFR IN HEAVY RAIN DURING THE NEXT HOUR
OR TWO. THINKING THAT SHRA WILL WEAKEN MORE OVER THE WEST GIVEN
LACK OF RESIDUAL INSTABILITY SO INCLUDING MORE VCTS/VCSH ACROSS
KBLF/KLWB THROUGH MIDNIGHT. ONCE SHRA COVERAGE STARTS TO
WANE...WILL SEE QUITE A BIT OF FOG AND STRATUS FILL IN BRINGING
MORE WIDESPREAD MVFR/IFR OVERNIGHT WITH STILL A FEW SHRA LIKELY
LINGERING IN SPOTS.
LOTS OF UNCERTAINTY LATE TONIGHT AND INTO THE DAY ON THURSDAY WITH
MODELS BRINGING A DECENT SWATH OF SHOWERS/THUNDER INTO THE WEST
AFTER DAYBREAK AND SLIDE THIS AREA EAST BY MIDDAY. THIS RIGHT
AHEAD OF THE ACTUAL SURFACE FRONT AND SINCE SUPPORTED BY SEVERAL
MODELS WILL INCLUDE MORE MVFR IN SHRA FROM WEST TO EAST DURING
THURSDAY. DEGREE OF DEEPER CONVECTION REMAINS IFFY PENDING AMOUNT
OF AFTERNOON HEATING BEFORE ANOTHER PIECE OF UPPER LEVEL ENERGY
STARTS TO ARRIVE ACROSS THE FAR WEST LATE IN THE DAY. THIS MAY
BRING ANOTHER BAND OF SHRA/TSRA TO THE WESTERN SITES. MVFR LOOKS
TO LINGER ACROSS THE SE WVA SITES INTO THURSDAY EVENING GIVEN
INCREASING UPSLOPE FLOW...WITH IMPROVING FLYING CONDITIONS ELSW
OVERNIGHT.
STRONG HIGH PRESSURE WILL BRING MUCH DRIER AIR BY FRIDAY WITH VFR
LIKELY TO PREVAIL THROUGH THE WEEKEND INTO EARLY NEXT WEEK.
EQUIPMENT
THE NOAA WEATHER RADIO AT ROANOKE VIRGINIA IS OFF THE AIR THIS
EVENING DUE TO A PROBLEM AT THE TRANSMITTER SITE. RESTORATION TIME
IS UNKNOWN AT THIS POINT.
RNK WATCHES/WARNINGS/ADVISORIES
VA...NONE.
NC...NONE.
WV...NONE.
SYNOPSIS...JH/KK
NEAR TERM...JH/KK
SHORT TERM...WP
LONG TERM...WP
AVIATION...JH/KK/RAB
EQUIPMENT...JH
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