-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRLX 011818
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
118 PM EST SUN DEC 1 2013

.SYNOPSIS...
-- Changed Discussion --
APPROACHING SYSTEM BRINGS CLOUDS AND LIGHT PRECIPITATION TONIGHT
AND MONDAY. WARMING RESUMES MID WEEK AHEAD OF A LARGER SYSTEM. IT
SLOWLY CROSSES LATE WEEK AS A COLD FRONT. COLDER SATURDAY.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH MONDAY/...
-- Changed Discussion --
NO MAJOR CHANGES WERE MADE TO THE PREVIOUS FORECAST. FRONTAL
BOUNDARY AT 18Z ASSOCIATED WITH LOW ACROSS THE GREAT LAKES
STRETCHED SOUTHWEST ACROSS CENTRAL INDIANA INTO SOUTHERN IL. THIS
FRONT WILL MOVE INTO OHIO LATER TONIGHT...AND FINALLY INTO
SOUTHEAST OHIO/VICINITY OF OHIO RIVER AROUND 12-15Z MONDAY...WHERE
IT WILL EVENTUALLY WASH OUT. INCREASING LOW LEVEL MOISTURE WITH
THIS APPROACHING FRONT...AS WELL AS A WEAK SHORTWAVE MOVING
THROUGH THE AREA ON MONDAY...WILL CREATE A SLIGHT CHANCE TO CHANCE
OF POPS ACROSS MUCH OF THE CWA. MUCH OF THIS PRECIPITATION WILL BE
IN THE FROM OF RAIN...HOWEVER...THERE COULD BE SOME PATCHY
FREEZING RAIN/DRIZZLE ACROSS PARTS OF THE NORTHERN MOUNTAIN ZONES
LATE TONIGHT/EARLY TOMORROW. NOT THINKING THERE WILL BE MUCH IN
TERMS OF COVERAGE OF FZRA...AS SURFACE TEMPERATURES WILL BE
BORDERLINE FREEZING AND PATCHY IN COVERAGE...AS WELL AS A LACK OF
SIGNIFICANT MOISTURE. IN FACT...THE LACK OF MOISTURE ABOVE ABOUT
800MB AND THUS LACK OF MOISTURE IN THE CRYSTAL GROWTH ZONE WILL
PREVENT SNOW OR A MIX.

MADE LITTLE CHANGES TO THE TEMPERATURES FOR THE PERIOD...AND
CONTINUED TO HUG THE COLDER SIDE OF GUIDANCE ON MONDAY DUE TO THE
EXPECTED CLOUDY CONDITIONS.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
ANOTHER PIECE OF ENERGY WILL BE DIVING IN ON THE BACK SIDE OF THE
MEAN UPPER TROF WITHIN THE N STREAM TO PARTIALLY PHASE WITH S
STREAM ENERGY ON MONDAY. THIS WILL HELP TO INDUCE A SURFACE LOW
ALONG THE CAROLINA COAST WITH A POSSIBLE WEAK SURFACE REFLECTION
CLOSER TO N STREAM ENERGY AS WELL. AS THE UPPER TROF GOES NEGATIVE
TILT MONDAY NIGHT...MORE IN THE WAY OF PHASING WILL OCCUR WHICH
MAY HELP TO STRENGTHEN THE COASTAL LOW. WHAT THIS MEANS FOR OUR
SENSIBLE WX IS AN ABUNDANCE OF CLOUDS WITH SPOTTY LIGHT PRECIP
WITH THE UPPER TROF AND ALONG THE OLD BAROCLINIC ZONE. MODEL
SOUNDINGS INDICATE MAINLY A LIQUID EVENT EXCEPT IN THE HIGHER
ELEVATIONS WHERE SOME LIGHT FREEZING RAIN OR FREEZING DRIZZLE IS
POSSIBLE MONDAY MORNING.

THE WX SLOWLY IMPROVES LATER TUESDAY AS BUILDING HEIGHTS AND WARM
AIR ADVECTION ON INCREASING SW FLOW REPLACES DEPARTING UPPER
TROF. DO EXPECT SOME BREAKS IN THE CLOUDS IN THE AFTERNOON. DEVELOPING
LOW LEVEL SE FLOW E OF THE MOUNTAINS MAY KEEP E SLOPES SOCKED IN
LOW CLOUDS INTO EARLY WEDNESDAY. THERE MAY EVEN BE SOME PATCHY
DRIZZLE OR LIGHT RAIN AS WELL BUT KEPT THAT AREA POP FREE FOR NOW.

GFS AND GFS ENSEMBLES CONTINUE TO INSIST ON A FAST MOVING COLD
FRONT CROSSING ON WEDNESDAY WHILE THE ECMWF AND GEM SHOW MAINLY
UPPER RIDGING. FEATURE OF CONTENTION IS TIMING OF EJECTING ENERGY
OUT OF THE N ROCKIES AS THE GFS AND ITS ENSEMBLES CONTINUE TO BE
ON THE FAST SIDE...HENCE ITS FASTER SOLUTION REGARDING COLD FRONT.
WILL DISREGARD THIS AND LEAN ON WPC PREFERRED SOLUTION CLOSER TO
ECMWF AND GEM...MUCH THE SAME AS WITH PREVIOUS SHIFTS FORECAST.
WILL GRADUALLY BRING IN POPS FROM W TO E WEDNESDAY NIGHT WITH
APPROACHING FRONTAL BOUNDARY.

FOR TEMPS...GENERALLY USED A CONSENSUS APPROACH AND INCORPORATING
A BLEND WITH PREVIOUS FORECASTED NUMBERS. DID ELECT TO GO A BIT
COOLER THAN GUIDANCE ON MONDAY GIVEN EXPECTED SOLID
OVC...ESPECIALLY IN THE MOUNTAINS AND E SLOPES. GUIDANCE FOR
TUESDAY CONTINUES TO COME IN WARMER AND NUDGED MAXT GRID UP A FEW
TICKS BUT NOT QUITE AS MUCH AS MODELS SUGGEST. WARMEST DAY SHOULD
ON WEDNESDAY AS WARM AIR ADVECTION ALLOWS A DECENT SURGE OF LOW
LEVEL WARM AIR INTO THE AREA. STILL EXPECTING SOME CLOUDS WITH
THIS WARMUP AND TEMPERED HIGHS A BIT FROM WHAT GUIDANCE IS
SUGGESTING. STILL...MOST AREAS SHOULD CLIMB INTO THE UPPER 50S TO
LOWER 60S WITH SOME 50S EVEN INTO THE MOUNTAINS. THIS TREND
CONTINUES FOR WEDNESDAY NIGHT AND MAY STILL BE TOO COLD WITH MINT
GRID GIVEN THE BOUNDARY LAYER MIXING AND CLOUDS.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
MAIN FEATURE THIS PERIOD IS A WAVY COLD FRONT THAT CROSSES THE AREA
AS A LARGE BUT PROGRESSIVE TROUGH THE MIDDLE CONUS.

GFS HAS A LEAD UPPER LEVEL LOW THAT LIFTS THROUGH THE UPPER GREAT
LAKES TUE NT AND WED WHICH THE OTHER MODELS DO NOT HAVE.  THE GFS
USES THIS FEATURE...AND ITS SFC REFLECTION...TO PUSH A COLD FRONT
INTO THE AREA WED...GIVING RISE TO RAIN SHOWERS.  OTHER MODELS HAVE
UPPER LEVEL RIDGING CROSSING THE AREA WED AFTERNOON AND
EVENING...WHICH WOULD KEEP THE WEATHER DRY THROUGH THEN AND THIS IS
IN LINE WITH WPC THINKING.

THE WPC/CMC/ECMWF SCENARIO THEN BRINGS THE COLD FRONT TOWARD THE
AREA THU...BEFORE BEING HELD UP INTO FRI BY WAVES OF LOW PRESSURE
MOVING UP ALONG IT...BENEATH THE BROAD SW FLOW ALOFT OUT AHEAD OF
THE LARGE MID CONUS TROUGH.  THIS INTRODUCES THE CHANCE FOR RAIN
SHOWERS LATE WED NT...THE CHANCE INCREASING THU TO HIGH CHANCE /
LIKELY FOR THU NT THROUGH FRI.  THIS CAPTURES THE TIME THE MAIN
CORRIDOR OF PRECIPITATION SHOULD BE OVER OR NEARLY OVER THE FCST
AREA...WHILE NOT ATTEMPTING TO TIME ANY INDIVIDUAL WAVES AT THIS
DISTANCE.

INCLUDED THE SLIGHT CHANCE FOR THUNDER FOR MAINLY THE MOUNTAINS
AHEAD OF THE FRONT LATE THU GIVEN HIGHER DEW POINTS AND STRONG FLOW.

THE FRONT PUSHES S AND E OF THE AREA FRI NT...WITH POPS GRADUALLY
WANING FRI NT AND SAT.  AN UNDERCUTTING PATTERN IS LIKELY BEHIND THE
FRONT WITH ADDITIONAL WAVES NOT OUT OF THE QUESTION.  WE MAY NEED TO
KEEP A WATCHFUL EYE ON THE LENGTH OF TIME THIS SYSTEM IS TO IMPACT
OUR AREA PER RAINFALL TOTALS...ALTHOUGH THESE WINDOWS DO TEND TO
NARROW AS THE TIME GETS CLOSER.

BLENDED IN BIAS CORRECTED VERSIONS OF THE ECMWFHIRES AND ADJMEX...AS
WELL AS WPC FOR TEMPERATURES.  HAVE IT MILDER AHEAD OF THE SYSTEM
WED AND THU...WITH A TIGHTER BAROCLINIC ZONE REFLECTED IN FCST HIGHS
FOR FRI.  COLDER...DRIER AIR SHOULD SET IN BY THE END OF THE PERIOD
/SUN MORNING/.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
18Z SUNDAY THROUGH 18Z MONDAY...
LOW VFR STRATUS DECK ACROSS THE AREA. WILL REMAIN RELATIVELY VFR
UNTIL AFTER 03-06Z...WHEN SOME LOWERING TO MVFR IS
EXPECTED. SOME LIFTING TO LOW VFR IS EXPECTED AFTER 16Z MONDAY.
PATCHY FREEZING DRIZZLE POSSIBLE MAINLY 06 TO 13Z ACROSS THE
NORTHERN MOUNTAINS. LIGHT SURFACE WINDS FOR THE PERIOD.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY...

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: MORE WIDESPREAD MVFR...OR EVEN LOCAL IFR CIGS
COULD DEVELOP OVERNIGHT THAN CURRENTLY FORECAST.

EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS
CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H =
HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M =
MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW:
TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.

UTC 1HRLY       18   19   20   21   22   23   00   01   02   03   04   05
EST 1HRLY       13   14   15   16   17   18   19   20   21   22   23   00
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    M    H    H
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 18Z MONDAY...
IFR CIGS POSSIBLE MONDAY NIGHT/EARLY TUESDAY...MAINLY ACROSS MOUNTAINS.
-- End Changed Discussion --

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.

&&

$$
SYNOPSIS...KMC/TRM/SL
NEAR TERM...SL
SHORT TERM...30
LONG TERM...TRM
AVIATION...SL