Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 210522
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1207 AM EST SUN DEC 21 2014

.SYNOPSIS...
WEAK DISTURBANCE EXITS TONIGHT. WEAK HIGH PRESSURE CROSSES SUNDAY.
MID LEVEL SHORTWAVE CLIPS MOUNTAINS MONDAY. STRONG LOW PRESSURE SYSTEM
LIFTS NORTHEAST ACROSS THE OHIO VALLEY THROUGH CHRISTMAS EVE.

&&

.NEAR TERM /THROUGH TODAY/...
9:30 PM UPDATE...NOT TOO MANY CHANGES MADE TO THE CURRENT
FORECAST. UPDATED EARLIER TO ADD A FEW SNOW FLURRIES BY BECKLEY.
DON/T THINK THERE IS MUCH LEFT TOUCHING THE GROUND ON THE WEST
SIDE OF THE MOUNTAINS. HAVE NOTICED SEVERAL HOURS OF LIGHT SNOW AT
BLUEFIELD. EXPECT A SOLID STRATUS DECK ACROSS THE AREA OVERNIGHT
WITH THE SHORTWAVE.  THE CURRENT FORECAST HAS THINGS COVERED WELL.

PREVIOUS DISCUSSION...
MID LEVEL BAROCLINIC LEAF OVER THE AREA EARLY THIS AFTERNOON
DRIFTS ENEWD OUT OF THE AREA TONIGHT AS AN UPPER LEVEL S/W TROUGH
CROSSES. WEAK HIGH PRESSURE SETTLES INTO THE FCST LATE TONIGHT
BENEATH UPPER LEVEL RIDGING IN THE WAKE OF THE S/W TROUGH...AND
THEN BEGINS DRIFTING ENEWD OUT OF THE AREA SUNDAY AFTERNOON...AS
THE UPPER LEVEL FLOW STARTS TO BACK TO THE SW.

LOW LEVEL MOISTURE REMAINS IN PLACE AT PERSISTENT H8-9 INVERSION
ALTHOUGH THE STRATOCU HAD BROKEN UP ACROSS MOST OF WV.  WITH LITTLE
FLOW TO WORK WITH...THIS IS LIKELY TO REFORM TONIGHT OR AT THE
LATEST FIRST THING SUNDAY MORNING ON MIXING.  DAYTIME MIXING WILL
EVENTUALLY LEAD TO A MORE CELLULAR CU FIELD SUNDAY AFTERNOON WITH A
SIGNIFICANT DECREASE IN CLOUD AMOUNT BY THE END OF THE DAY SUNDAY.

LOWS LOOKED GOOD IN LIGHT OF LATEST GUIDANCE FOR TONIGHT ALTHOUGH
BIAS CORRECTED VALUES WERE HIGHER.  CONTINUING THE TREND OF LOWER
HIGHS WITH ANOTHER DAY OF STRATOCU FOR SUNDAY.  THE LATE DAY
CLEARING SHOULD STILL ALLOW TEMPERATURES TO BREAK 40 ACROSS MUCH OF
THE AREA.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
MID LEVEL RIDGE AXIS CROSSES SUNDAY NIGHT BRINGING A DRIER AIR
MASS TO THE AREA.  HOWEVER...BUFKIT SOUNDINGS SUGGEST UPPER LEVEL
CLOUDS WILL BLANKET THE AREA...WITH LOW LEVEL STRATUS FORMING
ALONG THE WESTERN SLOPES AND EASTERN MOUNTAINS SUNDAY NIGHT INTO
EARLY MONDAY.

MODELS INDICATE A DEVELOPING WEAK SFC LOW PRESSURE ALONG THE
SOUTHEAST COAST...MEANWHILE...AT THE MID LEVELS...A WEAK SHORTWAVE
CROSSES THE AREA ON MONDAY.  THESE TWO SYSTEMS COULD SQUEEZE SOME
MOISTURE ACROSS THE EASTERN MOUNTAINS AND PRODUCE LOW CHANCE FOR
PRECIPITATION THERE.  EXPECT LIGHT RAIN...WITH POCKETS OF LIGHT
FREEZING RAIN WHERE TEMPERATURES COULD REMAIN AT OR BELOW
FREEZING...AND SOME LIGHT SNOW WITH THIS SCENARIO.  TEMPERATURES
ACROSS THE LOWLANDS WILL BE IN THE UPPER 30S MONDAY NIGHT.

THE WEAK MID LEVEL WAVE COULD BRING LIGHT PCPN ACROSS SOUTHEAST OH
BY TUESDAY.  INCREASED POPS TO HIGH CHANCE ACROSS SOUTHEAST OH
AND SOUTHERN WV WHERE MODELS SHOW SOME AGREEMENT IN THEIR QPF
FIELDS.

WEAK FLOW BECOMES GENTLE TO MODERATE FROM THE SOUTH AND SOUTHEAST
FROM THE SFC TO H850...TO BRING WAA.  THEREFORE...TEMPERATURES
WILL BE A BIT WARMER THAN THE PAST FEW DAYS. GENERALLY...HIGHS ON
MONDAY COULD REACH INTO THE MID 50S...AND INTO THE LOWER 60S ON
TUESDAY AS WAA BECOMES STRONGER.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
ACTIVE WEATHER PATTERN CONTINUES IN THE LONG TERM PERIOD...WITH A
DEEPENING UPPER TROUGH ACROSS THE CENTRAL PLAINS AT THE BEGINNING OF
PERIOD...WITH A SURFACE LOW MOVING NORTHEAST OUT OF THE GULF STATES
TOWARDS THE REGION. STRONG SOUTHERLY WINDS WILL DEVELOP OUT AHEAD OF
THE SYSTEM...WITH GOOD MOISTURE TRANSPORT INTO THE AREA AS A RESULT.
THIS IS A STRONG SYSTEM...WITH STRONG PRESSURE FALLS/BOMBOGENESIS AS
THE LOW MOVES TOWARDS THE REGION. COLD FRONT STILL PROGGED TO MOVE
THROUGH THE AREA WEDNESDAY...WITH FALLING TEMPERATURES...STRONG
GUSTY WINDS ALONG AND BEHIND THE FRONT DUE TO TIGHT PRESSURE
GRADIENT...AND POTENTIAL FOR STRONG WINDS ALOFT TO MIX DOWN...AND EVEN A
SLIGHT CHANCE FOR THUNDER...MAINLY ACROSS THE WEST...AS THE FRONT
MOVES INTO THE REGION. STARTING TO LOOK MORE AND MORE LIKE WINTER
PRECIPITATION WILL NOT BE A HUGE HAZARD WITH THIS SYSTEM...DUE TO
THE OVERALL SPEED...AND THE FACT THAT BY THE TIME ENOUGH COLD AIR IS
IN PLACE...BULK OF MOISTURE SHOULD HAVE EXITED. IN ADDITION...STILL
QUITE A BIT OF UNCERTAINTY AS TO HOW MUCH WILL ACTUALLY BE ABLE TO
STICK TO THE GROUND IF GROUND TEMPERATURES ARE TOO WARM AS
TEMPERATURES WILL RISE INTO THE 50S OUT AHEAD OF THE SYSTEM.
HOWEVER...WILL STILL SEE A CHANGE OVER TO SNOW WEDNESDAY NIGHT INTO
THURSDAY...ALONG WITH FALLING TEMPERATURES. WILL CONTINUE TO
MAINTAIN HWO.

ON THURSDAY...UPPER LOW LIFTS NORTH ACROSS CANADA...BECOMING NEARLY
STACKED WITH SURFACE LOW. STILL A CHANCE FOR SOME LIGHT SNOW SHOWER
ACTIVITY ON THURSDAY...BUT WILL GRADUALLY SEE A DRYING TREND FROM
SOUTH TO NORTH AS THE SYSTEM PULLS AWAY.

ANOTHER FRONT APPROACHES LATE IN THE EXTENDED.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
A VFR CLOUD DECK WILL CONTINUE TO MOVE OUT OF THE REGION EARLY THIS
MORNING...BUT A PATCHY LOWER MVFR CLOUD DECK IS EXPECTED TO REMAIN.
MODELS VARY CONSIDERABLY WITH THIS DECK...SO CONFIDENCE IN PLACEMENT
IS LOW. THIS DECK SHOULD GRADUALLY ERODE TODAY. A SOUTHEAST WIND
FLOW WILL BE DEVELOPING HOWEVER...WHICH WILL ALLOW MVFR CLOUDS TO
BANK UP AGAINST THE EASTERN SLOPES OF THE MOUNTAINS SUNDAY NIGHT.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY...

FORECAST CONFIDENCE: LOW.

ALTERNATE SCENARIOS: TIMING AND LOCATION OF A MVFR STRATUS DECK
COULD VARY CONSIDERABLY.

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.

DATE                                   SUN 12/21/14
UTC 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
EST 1HRLY       01   02   03   04   05   06   07   08   09   10   11   12
CRW CONSISTENCY  H    H    H    H    H    H    H    H    M    M    M    M
HTS CONSISTENCY  M    M    H    M    M    H    M    M    M    M    M    M
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  H    H    H    H    H    H    M    M    M    M    M    M
PKB CONSISTENCY  M    M    M    H    H    H    M    M    M    M    M    M
CKB CONSISTENCY  H    H    H    H    H    M    M    M    M    M    M    M

AFTER 06Z MONDAY...
IFR POSSIBLE IN MOUNTAINS LATE SUNDAY NIGHT AND MONDAY IN A WINTRY
MIX. IFR POSSIBLE IN RAIN TUESDAY NIGHT INTO WEDNESDAY...CHANGING TO
SNOW SHOWERS LATE WEDNESDAY...AS AN INTENSE LOW PRESSURE CENTER
PASSES.

&&

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

&&

$$
SYNOPSIS...ARJ/TRM/SL
NEAR TERM...FB/TRM
SHORT TERM...ARJ
LONG TERM...SL
AVIATION...RPY









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