Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 280535
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
135 AM EDT TUE APR 28 2015

.SYNOPSIS...
LOW PRESSURE OVER TEXAS WILL SHIFT EAST INTO THE GULF COAST
STATES AND TN VALLEY TO BRING OUR NEXT ROUND OF RAIN BY MIDWEEK.
SHOWERS MAY LINGER INTO FRIDAY BEFORE HIGH PRESSURE BUILDS BACK IN
FROM THE WEST WITH IMPROVING CONDITIONS FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 120 AM EDT TUESDAY...

FORECAST ON TARGET THOUGH THE RURAL/OUTLYING AREA IN THE PIEDMONT
RUNNING COOLER AND WITH LIGHT WINDS THIS AREA COULD SEE FROST AS
WELL. THIS HANDLED IN THE SPECIAL WX STATEMENT.

THE CLOUDS OVER THE WEST TO GRADUALLY SCATTER TOWARD MORNING.

PREVIOUS DISCUSSION FROM MONDAY EVENING...

REMOVED THE CHANCE POPS AND THE SMALL AMTS OF QPF THAT WE HAD
PREVIOUSLY FOR THE GREENBRIER VALLEY AS SCATTERED LIGHT SHOWERS
WERE NEVER ABLE TO MAKE IT THIS FAR SOUTH. WIND SPEEDS HAVE ALSO
BACKED OFF A FEW HOURS QUICKER THAN ANTICIPATED SO THE GRIDS HAVE
BEEN UPDATED TO REFLECT THE CURRENT TREND. STILL EXPECT
TEMPERATURES TO FALL RAPIDLY THIS EVENING THANKS TO LOW DEWPTS AND
CLEARING SKIES...WITH FROST DEVELOPING ONCE AGAIN TUESDAY MORNING
IN MANY MOUNTAIN VALLEYS.

AS OF 400 PM EDT MONDAY...

THINGS SHOULD BE RELATIVELY QUIET THROUGH THE NEAR TERM. SATELLITE
PICS SHOW A GOOD AMOUNT OF CONVECTIVE CLOUDS OVER THE AREA LATE
THIS AFTERNOON BUT SHOWERS ASSOCIATED WITH THE APPROACHING SHORT
WAVE ROTATING AROUND THE UPPER LOW OVER THE NORTHEAST US REMAIN
WELL TO THE NORTH. STILL BELIEVE THERE WILL BE A CHANCE FOR SOME
SHOWERS ACROSS THE GREENBRIER VALLEY THROUGH THE ALLEGHANY
HIGHLANDS FOR A BRIEF PERIOD EARLY THIS EVENING...BUT NOTHING
SIGNIFICANT IS EXPECTED. THEN AS WE LOSE OUR DIURNAL
HEATING...CLOUDS WILL BE ON THE DECREASE AND ALLOW FOR DECENT
RADIATIONAL COOLING OVERNIGHT. THIS SHOULD MAKE AREAS OF FROST
POSSIBLE WEST OF THE BLUE RIDGE SO A FROST ADVISORY HAS BEEN
ISSUED. THERE WILL ALSO BE PATCHY FROST POSSIBLE EAST OF THE
RIDGE BUT DO NOT EXPECT COVERAGE TO BE GREAT ENOUGH TO WARRANT AN
ADVISORY SO HAVE ISSUED AN SPS TO COVER THIS. TOMORROW LOOKS LIKE
A FAIR WEATHER DAY WITH HIGH PRESSURE RIDGING IN FROM THE
NORTHWEST.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
AS OF 400 PM EDT MONDAY...

A LOW PRESSURE SYSTEM SHOULD EMERGE FROM THE GULF COAST DURING
TUESDAY NIGHT. INCREASING HIGH CLOUDS OVER THE CWA COULD KEEP LOW
TEMPERATURES NOT DIPPING QUITE AS MUCH BY WEDNESDAY MORNING AS
REFLECTED IN THE 12Z MODEL GUIDANCE. OVERALL...THE GFS AND ECMWF
HAVE COME INTO BETTER AGREEMENT WITH A SLOWER ARRIVAL SOLUTION OF
THE LOW PRESSURE SYSTEM ARRIVING BY WEDNESDAY AFTERNOON. POPS WERE
CUT BACK A LITTLE DURING EARLY WEDNESDAY BUT INCREASED THEREAFTER TO
REFLECT THIS CHANGE. UNSEASONABLY COOL TEMPERATURES FOR LATE APRIL
SHOULD KEEP INSTABILITY TOO LOW TO MENTION ANY CHANCE OF THUNDER
THROUGHOUT THIS PERIOD.

QPF SOLUTIONS APPEAR TO BE IN THE ONE QUARTER TO HALF AN INCH RANGE
FOR WEDNESDAY AND THURSDAY...WHICH SHOULD NOT POSE ANY FLOODING
CONCERNS AT THIS TIME. HOWEVER...THE SOUTHEAST FLOW PRIOR TO THE
CENTER OF LOW PRESSURE REACHING THE NORTH CAROLINA COAST ON
THURSDAY...COULD AID IN SOME UPSLOPE ENHANCEMENT OF THE RAIN OVER
THE SOUTHERN BLUE RIDGE...SO LOCALLY HIGHER AMOUNTS ARE CERTAINLY
POSSIBLE IN THE NORTHWEST NORTH CAROLINA MOUNTAINS. AS THIS LOW
PRESSURE SYSTEM INTENSIFIES JUST OFF THE COAST...A TRAILING UPPER
LEVEL LOW WILL APPROACH FROM THE GREAT LAKES TO BRING A SECOND ROUND
OF RAIN FOR THURSDAY NIGHT. CLOUD COVER SHOULD REMAIN PREVALENT
ACROSS THE ENTIRE CWA...SO TEMPERATURES ONLY WILL VARY FROM 40S FOR
LOWS...TO MID 50S AND LOWER 60S FOR HIGHS.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 400 PM EDT SUNDAY...

THE UPPER LEVEL LOW SHOULD CROSS OVERHEAD EARLY ON FRIDAY...WHILE
ANOTHER ROUND OF RAIN SHOWERS ARRIVES OVER THE MID ATLANTIC.
NORTHWEST FLOW SHOULD PROVIDE A LITTLE UPSLOPE ENHANCEMENT ALONG THE
WESTERN SLOPES. THE OVERALL FLOW PATTERN ALOFT SHOULD FLATTEN AND
TURN MORE ZONAL BY THE UPCOMING WEEKEND...WITH STILL A HINT OF A
TROUGH OVER THE EAST COAST. SURFACE HIGH PRESSURE SHOULD PROVIDE A
DRIER AND MILDER SATURDAY...BUT CONFIDENCE WANES BY SUNDAY DUE TO
DIFFERING SOLUTIONS ON HOW FAR A WARM FRONT WILL STRETCH EASTWARD
DUE TO A DEVELOPING LOW PRESSURE SYSTEM OVER THE NORTHERN PLAINS.

ONCE HIGH PRESSURE PUSHES WELL OFFSHORE ON MONDAY...EXPECT WARMER
TEMPERATURES TO ARRIVE COURTESY OF WARM AIR ADVECTION BOTH AT THE
SURFACE AND ALOFT. BUILDING 500 MB HEIGHTS OVER THE EAST COAST
SHOULD ALLOW WARM AND MOIST SOUTHWEST FLOW FROM THE GULF OF MEXICO
TO BEGIN MOVING OVER THE APPALACHIAN MOUNTAINS. THE GFS SHOWS A FEW
SHOWERS POPPING UP WEST OF THE BLUE RIDGE FOR MONDAY...WITH MAYBE AN
ISOLATED THUNDERSTORM POSSIBLE FOR THE NORTHWEST NORTH CAROLINA
MOUNTAINS IN THE AFTERNOON. THE ECMWF IS SLOWER WITH THE LOW
PRESSURE SYSTEM IN THE NORTHERN PLAINS...AND KEEPS A STRONGER CAP
ALOFT TO PREVENT ANY CONVECTIVE ACTIVITY. IT IS TOO FAR OUT TO GIVE
ANYTHING ELSE OTHER THAN A MENTION OF SLIGHT CHANCE POPS.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 120 AM EDT TUESDAY...

HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE PERIOD. AS HIGH
PRESSURE DRIFTS OVER THE REGION TUESDAY...WINDS SPEEDS WILL REMAIN
LIGHT WHILE BECOMING NORTH-NORTHERLY.

EXTENDED AVIATION DISCUSSION...
VFR CONDITIONS ARE EXPECTED BEFORE CONDITIONS WORSEN ON WEDNESDAY.
ECMWF FASTEST NOW IN BRINGING RAINFALL INTO THE AREA WEDNESDAY
MORNING...WITH NAM/GFS SLOWER. STILL LOOKS LIKE SUB VFR BY MIDDAY
WEDNESDAY SOUTH OF A BLF-BCB LINE. THE REST OF THE AREA BY
WEDNESDAY EVENING. MODELS DIFFERING ON RAINFALL WITH GFS/NAM DRIER
NOW WED-WED NIGHT...BUT THINKING IS ONSHORE FLOW WILL KEEP
CIGS/VSBYS AT MVFR OR WORSE INTO WED NIGHT. NOT A LOT OF
CONFIDENCE INTO THU-FRI...BUT SHOULD SEE GRADUALLY IMPROVING
CONDITIONS THOUGH WIND STARTS TO PICK UP BETWEEN HIGH TO THE WEST
OF THE MTNS AND LOW OFF THE COAST...FROM THE NORTH. THE WEEKEND
LOOKS DRIER AS HIGH MOVES OVERHEAD.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR VAZ007-009>020-
     022>024.
NC...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ001-002-018.
WV...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR WVZ042>044-507-
     508.

&&

$$
SYNOPSIS...MBS
NEAR TERM...CF/MBS/WP
SHORT TERM...PW
LONG TERM...PW
AVIATION...WP



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