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 231257
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
757 AM EST SUN NOV 23 2014

.SYNOPSIS...
A WARM FRONT WILL GRADUALLY SPREAD RAIN INTO THE REGION FROM THE SOUTH INTO
EARLY THIS AFTERNOON. THE RAIN MAY BE HEAVY AT TIMES THIS EVENING AND EARLY
TONIGHT...AND WINDS WILL BECOME QUITE GUSTY ACROSS THE MOUNTAIN EMPIRE REGION
AND OTHER HIGH ELEVATIONS WEST OF THE BLUE RIDGE. UNSEASONABLY WARM CONDITIONS
ARE EXPECTED MONDAY IN THE WAKE OF THIS SYSTEM...BEFORE A COLD FRONT MOVES
THROUGH TUESDAY...RETURNING TEMPERATURES TO BELOW NORMAL FOR THE
REST OF THE WEEK. THERE IS THE POTENTIAL FOR A COASTAL STORM TO
IMPACT PARTS OF THE MID ATLANTIC FOR MID WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 330 AM EST SUNDAY...

EVERYTHING SEEMS TO BE UNFOLDING AS ADVERTISED AS PCPN TO OUR SOUTH
IS ADVANCING TOWARD THE REGION AHEAD OF A WARM FRONT ATTACHED TO A
DEVELOPING LOW IN THE MISSISSIPPI VALLEY. DRY AIR WILL HINDER PROGRESS
OF PCPN AS IT ENTERS THE REGION...BUT EXPECT IT WILL PASS THE VA/NC
LINE DURING THE MORNING AND OVERSPREAD THE REMAINDER OF THE AREA THIS
AFTERNOON. PCPN WILL BE BIASED WITH HEAVIEST AMOUNTS EXPECTED ACROSS
THE PIEDMONT AND LESSER AMOUNTS AS YOU GO FURTHER WEST OF THE BLUE RIDGE.

THE BIGGEST CONCERN THROUGH THE NEAR TERM IS THE DEVELOPING LOW LEVEL SELY
JET WHICH IS EXPECTED TO PEAK AOA 70KTS JUST TO OUR WEST ROUGHLY FROM 5PM TO
1AM. THE COUNTIES OF TAZEWELL AND SMYTH IN VA AND MERCER IS WV ARE KNOWN TO
BE SUSCEPTIBLE TO STRONG WINDS TRANSLATING TO LOWER ELEVATIONS IN THIS TYPE
OF SITUATION SO WILL RAISE A WIND ADVSY FOR THESE LOCATIONS IN ANTICIPATION
OF GUSTS AROUND 50MPH. HOWEVER...EXPECTING WINDS NOT TOO FAR BELOW CRITERIA
FOR OTHER AREAS OF THE WESTERN SLOPES SO ADVISORY MAY NEED TO BE EXPANDED IF
THE SITUATION UNFOLDS WITH SLIGHTLY STRONGER WINDS.

ONCE THE WARM FRONT SURGES THROUGH EARLY TONIGHT A PRONOUNCED DRY SLOT WILL
WORK IN FROM THE WEST AND SHOULD RAPIDLY TAPER PRECIPITATION AFTER MIDNIGHT.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 430 AM EST SUNDAY...

BROAD UPPER LEVEL 500H TROUGH WILL ENCOMPASS MUCH OF THE CENTRAL
CONUS MONDAY AND TUESDAY WITH COOLER AIR REMAINING WEST OF THE
MOUNTAINS MONDAY...THEN ADVECTING EAST OF THE MOUNTAINS TUESDAY AS
THE UPPER TROUGH PUSHES A DRY COLD FRONT OVER AND EAST OF THE
MOUNTAINS DURING THE PERIOD. BAROCLINIC ZONE WILL THEN SET-UP
ALONG THE EAST COAST AND WILL BECOME THE FOCUS FOR AREA OF LOW
PRESSURE TO DEVELOP ALONG THE GULF STREAM TUESDAY NIGHT AND MOVE
NORTHEAST NEAR THE MID ATLANTIC COAST WEDNESDAY.

IN THE WAKE OF SUNDAY NIGHTS WARM FRONTAL RAIN...FORECAST AREA
WILL BE IN THE DRY SLOT...WARM SECTOR SOUTHERLY WINDS PROVIDING A
BREEZY BUT MILD DAY MONDAY. 1000-500MB THICKNESS VALUES OF
565-570DM AND 850H TEMPS OF +10 DEG C SUPPORT SURFACE
TEMPERATURES WELL INTO THE 60S MONDAY...POSSIBLY TESTING THE LOWER
70S ACROSS SOUTHSIDE VA AND THE PIEDMONT. UNTIL SURFACE FRONT
CROSSES THE MOUNTAINS LATE IN THE DAY...FORECAST AREA SHOULD
REMAIN IN THE WARM SECTOR/DRY SLOT WITH MORE SUN THAN CLOUDS.

MONDAY NIGHT INTO TUESDAY...THICKNESSES DROP BEHIND PASSING COLD
FRONT. ASIDE FOR SOME MOUNTAIN SHOWERS...LITTLE IN THE WAY OF
MOISTURE ASSOCIATED WITH THE FRONT SO BIGGEST CHANGE WILL BE A
SHIFT IN WIND DIRECTION FROM SOUTH TO WEST...850 TEMPS TAKING
ABOUT A 10 DEGREE TUMBLE. TEMPERATURES TUESDAY WILL RETURN TO
NOVEMBER NORMALS WITH HIGHS IN THE MU40S MTNS TO LM50S SOUTHSIDE
VA AND NC PIEDMONT.

WEAK AREA OF HIGH PRESSURE OVER THE AREA TUESDAY AND TUESDAY NIGHT
WILL ENSURE MAINLY DRY CONDITIONS...ALTHOUGH MID/UPPER LEVEL
CLOUDS WILL BE ON THE INCREASE. MODELS ARE IN AGREEMENT THAT AN
AREA OF LOW PRESSURE WILL DEVELOP JUST OFF THE SOUTH CAROLINA
COAST TUESDAY NIGHT VCNTY OF THE BAROCLINIC ZONE. TRACK/STRENGTH
OF THIS FEATURE WILL DEPEND ON OVERALL RESPONSE TO DYNAMIC FORCING
FROM SHORT WAVE ENERGY ARRIVING VIA THE UPPER LEVEL TROF...MODELS
TRENDING STRONGER AND MORE AMPLIFIED WITH THIS FEATURE WITH TIME.
AT THE VERY LEAST CLOUDS WILL OVERSPREAD THE ENTIRE FORECAST BY
TUESDAY NIGHT. QUESTIONS IS WHETHER THE MOISTURE WILL BECOME DEEP
ENOUGH THIS FAR WEST FROM THE COAST FOR PRECIPITATION. ATTM IT
APPEAR GREATER THAN 50 PERCENT PROBABILITY FOR RAIN TO DEVELOP
ALONG AND EAST OF HIGHWAY 29 LATE TUESDAY NIGHT. IF PRECIPITATION
EXTENDS ALL THE WAY TO THE BLUE RIDGE...TEMPERATURES MAY BE COLD
ENOUGH ON THE WESTERN EDGE OF THIS SYSTEM TO HAVE SNOW OR A RAIN
SNOW MIX. UNTIL A BETTER FIX ON STORM TRACK CAN BE
ESTABLISHED...QPF WILL REMAIN IN QUESTION.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 130 PM EST SATURDAY...

TWO DISTINCT SYSTEMS HAVE THE POTENTIAL FOR BRING SOME PRECIPITATION
TO PARTS OF THE AREA DURING THIS SEGMENT OF THE FORECAST. THE FIRST
ITEM OF INTEREST IS A LOW PRESSURE WAVE MOVING NORTHWARD ALONG A
BAROCLINIC ZONE THAT WILL BE POSITIONED ALONG THE COAST DURING THE
WEDNESDAY AND WEDNESDAY NIGHT TIME PERIOD. THE VARIOUS MODELS ARE
STILL INCONSISTENT WITH EACH OTHER...AND WITH THEIR OWN PREVIOUS
MODEL RUNS REGARDING THE TIMING...TRACK AND ASSOCIATED PRECIPITATION
WITH THIS FEATURE. YESTERDAY...THE ECWMF WAS THE ONLY OPERATIONAL
MODEL RUN THAT HINTED AT PRECIPITATION SKIRTING THE EASTERN EXTENT
OF THE FORECAST AREA. TODAY...ITS SOLUTIONS IS MORE ROBUST ON THIS
SCENARIO WITH PRECIPITATION NOW THE WHOLE WAY WEST TO EASTERN
KENTUCKY. TODAY...THE GFS SOLUTION IS ONLY SLIGHTLY MORE ROBUST AS
COMPARED TO THE ECWMF FROM YESTERDAY...BUT STILL...HAS ALL BUT OUR
SOUTHEAST WEST VIRGINIA COUNTIES WITH AT LEAST 0.01 PRECIP. THE
CANADIAN SOLUTION KEEPS THE SYSTEM FARTHER OFF THE COAST WITH NOT A
DROP OF PRECIPITATION REACHING THE FORECAST AREA. OUR FORECAST FROM
YESTERDAY REFLECTED A MODEL BLEND CONSENSUS THAT WAS MORE IN LINE
WITH THE WETTER ECWMF SOLUTION. GIVEN BOTH THE GFS AND ECWMF ARE
WETTER FOR THE REGION...AND THE MODEL BLEND CONSENSUS IS ALSO WETTER
ACROSS THE REGION...HAVE FOLLOWED SUIT IN THE FORECAST.
PRECIPITATION CHANCES FOR WEDNESDAY HAVE BEEN INCREASED TO REFLECT 50
PERCENT IN THE EAST...WITH 20 TO 25 PERCENT IN THE WEST. SURFACE AND
LOW LEVEL THERMAL PROFILES SUGGEST MAINLY A SNOW OR RAIN/SNOW
FORECAST ACROSS THE MOUNTAINS ON TUESDAY...WITH PRIMARILY RAIN
ACROSS THE PIEDMONT. WEDNESDAY NIGHT...COLDER AIR ARRIVING ON THE
BACKSIDE OF THE DEPARTING SYSTEM WILL ALLOW FOR MORE LIGHT
SNOW...BUT WITH THE SYSTEM EXITING...MUCH LESS COVERAGE.

OUT NEXT POTENTIAL WEATHER MAKER WILL BE ASSOCIATED WITH A SHORTWAVE
TROUGH THAT ZIPS THROUGH THE OHIO VALLEY AND MID-ATLANTIC REGION
DURING THE THURSDAY AND THURSDAY NIGHT TIME PERIOD. BOTH THE GFS AND
ECWMF SOLUTIONS HAVE CHANGED COMPARED TO THEIR -24 HOUR
COUNTERPARTS. PRIOR...MODEL SOLUTIONS WERE HINTING AT A MORE
PROLONGED CLOSED LOW STRENGTHENING OVER THE CENTRAL APPALACHIANS
WITH A MORE PROFOUND SHOT OF COLDER AIR IN ITS WAKE. THE LATEST
SOLUTIONS OFFER A MORE GLANCING BLOW OF ENERGY ACROSS THE
AREA...WITH THE COLDER AIR NOT HAVING AS MUCH CHANCE TO MAKE THE
TURN SOUTH PRIOR TO ZONAL FLOW DEVELOPING IN THE WAKE OF THE PASSAGE
OF THE SHORTWAVE TROUGH. WHILE THE FORECAST WILL STILL OFFER SOME
ISOLATED TO SCATTERED RAIN/SNOW SHOWERS ACROSS PARTS OF SOUTHEAST
WEST VIRGINIA AND NEIGHBORING COUNTIES OF SOUTHWEST VIRGINIA THROUGH
THURSDAY NIGHT...THE TEMPERATURE FORECAST FROM THURSDAY THROUGH
SATURDAY WILL BE A BIT MILDER THAN WHAT AS OFFERED IN THE PREVIOUS
PACKAGE.

&&

.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
AS OF 800 AM EST SUNDAY...

MODELS IN AGREEMENT IN HANDLING OF UPCOMING WEATHER SYSTEM. STILL
ANTICIPATE VFR CONDITIONS THROUGH NOON EST TODAY BEFORE AIRMASS
SATURATES RESULTING IN RAIN ASSOCIATED WITH SUB VFR CIGS/VSBYS.
WARM FRONT OVER THE SOUTHEAST STATES WILL LIFT NORTH TODAY. RADAR
IS ALREADY INDICATING BLOSSOMING AREA OF RAIN OVER THE SOUTHEAST
STATES...MOVEMENT IS TO THE NORTHEAST. WEATHER CONDITIONS FROM
CENTRAL NORTH CAROLINA TO THE GULF COAST ARE IFR AND THESE SORT OF
CONDITIONS ARE MOVING NORTHEAST AND WILL OVERSPREAD THE VIRGINIAS
THIS AFTERNOON.

THROUGHOUT THE DAY CLOUD BASES WILL LOWER WITH MVFR CIGS
DEVELOPING AT ALL RNK TERMINAL FORECAST POINTS. ONSET OF RAIN WILL
BEGIN BETWEEN NOON-4PM AND WILL THEN RESULT IN RAPID DETERIATION
OF FLIGHT CONDITIONS TO IFR BY SUNSET WITH CONTINUATION OF LOW
CIGS/VSBYS THROUGH THE OVERNIGHT TONIGHT.

EXPECT PERIODS OF MDT AND HEAVY RAIN FROM THE BLUE RIDGE EAST
THIS EVENING INTO TONIGHT. CONTINUING TO MONITOR POTENTIAL FOR
LOW LVL WIND SHEAR AS LOW LEVEL JET INCREASES TO AOA 60KTS BY
SUNSET. WILL NOT MENTION IN THIS PACKAGE BUT MAY INCLUDE WITH THE
18Z TAF ISSUANCE IF NEEDED.


EXTENDED DISCUSSION...

A BRIEF RETURN TO VFR DURING MONDAY OUTSIDE OF THE MOUNTAINS AS A
DRY SLOT DEVELOPS BETWEEN THE EXITING FRONT FROM SUNDAY AND THE
NEXT UPSTREAM COLD FRONT. MONDAY INTO TUESDAY LOOK TO FEATURE
QUITE A BIT OF WIND. NW FLOW INTO MAY KEEP SUB VFR CIGS INTO BLF
AND POSSIBLE LWB...WITH VFR TO THE EAST. ANOTHER STORM SYSTEM IS
EXPECTED TO MOVE UP THE SOUTHEAST COAST BY WEDNESDAY WHICH MAY
BRING WINTRY PRECIP TO THE AREA ALONG WITH SUB VFR AT ALL SITES.

&&

.EQUIPMENT...
AS OF 215 PM EST FRIDAY...

THE VISIBILITY SENSOR AT KLYH...LYNCHBURG AIRPORT...WILL BE OUT
OF SERVICE UNTIL PARTS ARRIVE TO REPLACE THE SENSOR. UNTIL THEN
THE VISIBILITY WILL ONLY BE REPORTED WHEN THE CONTROL TOWER IS
STAFFED.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 1 AM EST MONDAY FOR
     VAZ007-009.
NC...NONE.
WV...WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 1 AM EST MONDAY FOR
     WVZ042.

&&

$$
SYNOPSIS...MBS
NEAR TERM...MBS
SHORT TERM...PM
LONG TERM...DS
AVIATION...PM
EQUIPMENT...RAB


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