Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 272004
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
404 PM EDT MON APR 27 2015

.SYNOPSIS...
AN UPPER DISTURBANCE MOVES ACROSS THE AREA THIS EVENING KEEPING
THE REGION IN A COOL AIR MASS. 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 TUESDAY/...
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 /TUESDAY NIGHT 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 /20Z MONDAY THROUGH SATURDAY/...
AS OF 210 PM EDT MONDAY...

HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE PERIOD EAST OF THE
BLUE RIDGE. SHOULD BE GOOD RAD COOLING TONIGHT BUT WITH A GOOD
DRYING DAY TODAY BELIEVE PATCHY FOG WILL NOT BE AS PREVALENT AS
LAST NIGHT DUE TO GOOD DRYING TODAY SO WILL NOT INCLUDE IN THE
TAFS. KBCB WILL ALSO BE VFR THOUGH BEING MORE FOG PRONE WILL USE A
BRIEF TEMPO FOR MVFR FOG TOWARDS DAYBREAK. KLWB/KBLF WILL BE
DEALING WITH SOME LOW LEVEL MOISTURE WORKING IN FROM THE NORTH.
WILL KEEP THESE SITES MVFR BUT INDICATE THE POSSIBILITY OF SOME
LOWER IFR CLOUDS WITH A SCT LAYER. FOG MAY BECOME AN ISSUE AT KLWB
DEPENDING ON HOW LONG CLOUDS HOLD. WOULD NOT BE SURPRISED IF NEXT
SHIFT FINDS IT NECESSARY TO INTRODUCE IFR FOG AT KLWB BASED ON
TRENDS EARLY TONIGHT. WINDS WILL SUBSIDE AFTER SUNSET AND REMAIN
LIGHT THROUGH TOMORROW.

EXTENDED AVIATION DISCUSSION...
VFR CONDITIONS ARE EXPECTED BEFORE CONDITIONS WORSEN ONCE BY LATE
TUESDAY NIGHT. MODELS WERE SPEEDING UP MOISTURE INTO THE
AREA...ESPECIALLY SOUTH OF A BLF-DAN LINE BY WED MORNING.
ATTM...THE GFS IS MOST AGGRESSIVE IN HANGING THE STORM BACK CLOSER
TO THE COAST INTO FRIDAY WHICH COULD KEEP THE AREA SOCKED INTO SUB
VFR WEATHER LONGER. THE ECMWF IS MORE PROGRESSIVE...AND ALL IN ALL
LOOKS LIKE WED-THU ARE SUB VFR DAYS...WITH SOME IMPROVEMENT
FRIDAY.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FROST ADVISORY FROM 2 AM TO 9 AM EDT TUESDAY FOR VAZ007-
     009>020-022>024.
NC...FROST ADVISORY FROM 2 AM TO 9 AM EDT TUESDAY FOR NCZ001-002-
     018.
WV...FROST ADVISORY FROM 2 AM TO 9 AM EDT TUESDAY FOR WVZ042>044-
     507-508.

&&

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



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