Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 210904
AFDRLX

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

.SYNOPSIS...
WEAK HIGH PRESSURE CROSSES TODAY. SYSTEM CLIPS THE MOUNTAINS MONDAY.
STRONG LOW PRESSURE SYSTEM LIFTS NORTHEAST ACROSS THE OHIO VALLEY
THROUGH CHRISTMAS EVE.

&&

.NEAR TERM /THROUGH TONIGHT/...
ONCE AGAIN...HIGH PRESSURE OVER THE AREA DOES NOT MEAN CLEAR SKIES.
A STRATUS DECK REMAINS OVER MUCH OF THE AREA THIS MORNING AND THE
MODELS ARE STRUGGLING WITH IT DUE TO THE WEAK FLOW. WILL USE A
COMBINATION OF THE RUC...HRRR...AND MES NAM. WITH THE STRATUS DECK
MOST LIKELY HOLDING LONGEST TODAY IN NORTHERN WEST VIRGINIA...WILL
GO ON THE LOWER SIDE OF MOS GUIDANCE THERE.

A SYSTEM OVER THE SOUTHEASTERN UNITED STATES PUSHES SOME MOISTURE
INTO THE AREA LATE TONIGHT. SOME PRECIPITATION IS A POSSIBILITY IN
THE MOUNTAINS. SOME TEMPERATURES COULD BE BELOW FREEZING
HOWEVER...SO SOME FREEZING RAIN OR SLEET IS A POSSIBILITY.
CONFIDENCE IS NOT HIGH ENOUGH AT THE MOMENT FOR AN ADVISORY...BUT
WILL HAVE TO MONITOR THIS SITUATION CLOSELY.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
PESKY MOISTURE FROM WEAK SURFACE LOW ALONG THE E COAST AS WELL AS
WAA WILL COMBINE FOR LIGHT PRECIP MOVING UP THE MOUNTAINS MONDAY
MORNING. THERMAL PROFILES CONTINUE TO INDICATE A BRIEF ONSET OF
FZRA WITH PSBL SLEET...BEFORE CHANGING OVER TO LIQUID BY MIDDAY
AND PULLING OUT IN THE AFTERNOON. TEMPS SHOULD RECOVER BEHIND THIS
SYSTEM FOR THE AFTERNOON WITH AID OF DEVELOPING SE DOWN SLOPE FLOW.
SOME PEAKS OF SUN IS PSBL S OF I64 LATE IN THE DAY. AS THE SE FLOW
INCREASES MONDAY NIGHT AND WAA ALOFT CONTINUES...THINK THE RIDGES
WILL SEE RISING TEMPS OVERNIGHT AMID INCREASING CLOUDS OVER THE AREA.

THERE HAS BEEN A NOTICEABLE TREND IN THE MODELS REGARDING THE
MIDWEEK SYSTEM. MOST DELAY PHASING AND RAPID PRESSURE DROPS UNTIL
INTO CANADA. WHAT THIS DOES IS TO SLOW THE FRONT/NOW ABOUT 6 HRS/ AND
LESSEN THE MAGNITUDE OF SENSIBLE WX EFFECTS FROM THIS
SYSTEM...INCLUDING POST FRONTAL CAA...SURFACE TEMPS...AND EXTENT
AND DURATION OF SHSN BEHIND THE FRONT. HAVE MODIFIED THE GRIDS TO
INCORPORATE THIS TREND IN THE MODEL SUITE AND DELAYED CHANGEOVER
TO SHSN.

WITH THE SLOWER TIMING OF THE FRONT...LOOKS LIKE CHRISTMAS EVE
MAY BE JUST AS WARM AS TUESDAY WITH LOW TO MID 60S POSSIBLE BOTH
DAYS. STILL THINKING TUESDAY THE DAYLIGHT HRS ON TUESDAY IS DRY E
OF THE OH RIVER WITH SHRA MOVING INTO SE OH AND NE KY IN THE
AFTERNOON WHICH THEN OVERSPREADS REMAINDER OF AREA TUESDAY NIGHT
AND WEDNESDAY. IT WILL BE A MILD TUESDAY NIGHT DESPITE THE SHRA AS
LOW LEVEL SE FLOW REACHES ITS MAXIMUM. WHAT STILL LOOKS LIKELY ARE
THE STRONG GUSTY WINDS CHRISTMAS EVE NIGHT AND CHRISTMAS DAY
ITSELF...WITH 30 KTS PSBL ESPECIALLY ACROSS N ZONES AND IN THE
MOUNTAINS WHERE EVEN HIGHER GUSTS ARE EXPECTED.

&&

.LONG TERM /THURSDAY 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 /09Z 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       08   09   10   11   12   13   14   15   16   17   18   19
EST 1HRLY       03   04   05   06   07   08   09   10   11   12   13   14
CRW CONSISTENCY  H    H    H    H    H    H    M    M    M    M    M    M
HTS CONSISTENCY  H    M    M    H    M    M    M    M    M    M    M    M
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  H    H    M    H    M    M    M    M    M    M    M    M
PKB CONSISTENCY  M    M    M    M    M    M    M    M    M    M    M    M
CKB CONSISTENCY  H    M    M    M    M    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...RPY/SL/30
NEAR TERM...RPY
SHORT TERM...30
LONG TERM...SL
AVIATION...RPY








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