Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 190823
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
423 AM EDT SUN APR 19 2015

.SYNOPSIS...
WARM FRONT BRINGS SHOWERS AND STRONG WINDS TODAY...BEFORE MOVING
THROUGH TONIGHT.  COLD FRONT BRINGS SHOWERS AND STRONG STORMS
MONDAY...FOLLOWED BY AN EXTENDED PERIOD OF COOLER WEATHER.

&&

.NEAR TERM /THROUGH TONIGHT/...
WARM FRONT OVER THE TN VALLEY EARLY THIS MORNING APPROACHES TODAY
AND MOVES NEWD THROUGH THE FCST AREA TONIGHT...BRINGING ON A WET
CLOSE TO THE WEEKEND.

WRFARW APPEARED TO HAVE A GOOD HANDLE ON THE EVOLUTION OF THE RAIN
ASSOCIATED WITH THE WARM FRONT.  THE RAIN HAS MADE BETTER NWD
PROGRESS OUT TO THE W EARLY THIS MORNING...AND EVEN THERE THE
SHOWERS WERE RATHER LIGHT AND WIDELY SCATTERED BACK THROUGH CENTRAL
KY.  THEREFORE HAVE DELAYED THE ONSET OF PRECIPITATION FROM THE S
AND W EARLY THIS MORNING.  ALL NEAR TERM MODELS HAVE THE FCST AREA
DRY THROUGH 12Z.

WITH HIGH PRESSURE DRIVING A BACK DOOR DOWN THE E COAST...AND A WARM
WAVE APPROACHING FROM THE WRN TN VALLEY...THE RESULTING TIGHTENING
PRESSURE GRADIENT WILL CREATE STRONG WINDS THAT WILL MIX TO THE SFC
AS THE WARM FRONT GETS CLOSE / MOVES THROUGH. IN ADDITION TO
PRODUCING GUSTS UP TO AROUND 30 KTS TODAY...THESE STRONG WINDS...TO
THE TUNE OF 60 KTS OR BETTER AT H85...WILL CREATE THE TYPICAL
UPSLOPE DOWNSLOPE EFFECT...WITH A RAIN SHADOW JUST W OF THE
MOUNTAINS...AND ENHANCED QPF E OF THE MOUNTAINS...THE BLUE RIDGE IN
PARTICULAR.  THIS IS IN AGREEMENT WITH THE WPC SLIGHT RISK AND RNK /
LWX THINKING. THE WRFARW HAD BEEN INDICATING HEAVY PRECIPITATION
INTO POCAHONTAS COUNTY BUT NOW KEEPS THE HEAVIEST E OF THE BLUE
RIDGE THIS EVENING.  THE WRFNMM IS HITTING THE POCAHONTAS / RANDOLPH
LINE A LITTLE HARD THOUGH.

AS THE WARM FRONT MOVES INTO THE AREA...TAPERING THE RAIN SHOWERS SW
TO NE THIS EVENING...THERE WILL BE A WINDOW OF OPPORTUNITY FOR
CONVECTION TO DEVELOP SW PORTION OF FCST AREA THAT COULD THEN TAKE
ADVANTAGE OF THE STRONG FLOW...ESPECIALLY ALONG THE WARM FRONT IF
THERE IS ENOUGH DIRECTIONAL SHEAR THERE.  WILL MAINTAIN HWO MENTION
THERE PER PREVIOUS PACKAGE AND SWODY1 FOR THIS EVENING.  OTHERWISE
THE CWA WILL TREND DRIER IN THE WARM SECTOR OVERNIGHT TONIGHT.

USED A MET/MOSGUIDE/WRFARW BLEND FOR TEMPERATURES TODAY AND THIS
EVENING AND A MET/MOSGUIDE BLEND TONIGHT...NOT MUCH CHANGE OVERALL
BUT SUBTLE TIMING ADJUSTMENTS RELATIVE TO PRECIPITATION TODAY.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ACTIVE WEATHER CONTINUES IN THE SHORT TERM PERIODS AS ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS DEVELOP...AS A SURFACE COLD FRONT...AND
UPPER SHORTWAVE TROUGH AFFECT THE AREA. THERE IS THE POSSIBILITY
THAT SOME OF THE STORMS COULD BECOME SEVERE...AND IF ANY BREAKS ARE
ABLE TO FORM IN THE CLOUD COVER ON MONDAY OUT AHEAD OF THE
FRONT...THIS WILL ONLY HELP TO INCREASE THE INSTABILITY. MODELS
INDICATING 30-40 KTS 0-6KM BULK SHEAR...AND UNIDIRECTIONAL WIND
PROFILES...SUGGESTIVE OF STORMS CAPABLE OF PRODUCING DAMAGING WINDS.
IN ADDITION...FZLVS AROUND 8000-9000 FEET SUGGESTED ON MODEL
SOUNDINGS...ALONG WITH 1000-1500 J/KG CAPE...LARGE HAIL WILL ALSO BE
A FACTOR IN ANY STORMS THAT ARE ABLE TO DEVELOP. SPC HAS HIGHLIGHTED
THE EASTERN HALF OF THE CWA IN A SLIGHT RISK FOR SEVERE ON MONDAY AS
A RESULT.

COLD FRONT WILL BE TO THE EAST OF THE CWA LATE MONDAY NIGHT...WITH
CALMER...BUT COOLER...WEATHER TAKING HOLD. UPPER LOW WILL LINGER
ACROSS THE GREAT LAKES REGION FOR THE REMAINDER OF THE SHORT TERM
PERIOD...AND THIS COMBINED WITH WAVES ROTATING AROUND THE LOW AT
TIMES...WILL CREATE ADDITIONAL CHANCES FOR PRECIPITATION.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
OVERALL...WE LOOK TO BE COOLER THAN NORMAL...ESPECIALLY AT NIGHT
THROUGH THE LONG TERM. BEST CHANCE FOR A FROST/FREEZE LOOKS TO BE
FRIDAY MORNING AFTER A WEAK COLD FRONT PASSES THROUGH WEDNESDAY
NIGHT OR THURSDAY. STUCK PRETTY CLOSE TO WPC FOR POPS/SKY/HIGH
TEMPS. UNDERCUT WPC TEMPS A BIT ON OVERNIGHT LOWS. BOTH GFS AND
ECMWF SHOW 850MB TEMPS BELOW ZERO LATE THIS WEEK INTO THIS WEEKEND.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
AN APPROACHING WARM FRONT BRINGS ON WET WEATHER THIS PERIOD WITH
WIDESPREAD MVFR CONDITIONS SUNDAY AFTERNOON.  THE LOWEST CIGS WILL
BE FOUND AT BKW ON STRONG AND GU STY SE FLOW...WITH PEAK GUSTS UP
AROUND 30 KTS.  CIGS THERE COULD GET CLOSE TO IF NOT INTO IFR
RANGE.  MVFR CONDITIONS WILL BE MINIMAL IN DURATION IN THE DOWNSLOPE
AREA W OF THE MOUNTAINS...INCLUDING CRW CKB AND EKN.

THUNDER IS NOT FCST...BUT SCATTERED CONVECTION IS NOT OUT OF THE
QUESTION IN THE HTS TRI STATE AREA SUNDAY EVENING NEAR THE SFC WARM
FRONT.

LIGHT NE SFC FLOW SLOWLY INCREASING AND VEERING TO SE
OVERNIGHT...AND BECOMING GUSTY SE ON SUNDAY AND THEN DIMINISHING AND
BECOMING S TO SE SUNDAY NT.  MODERATE SE FLOW OVERNIGHT WILL BECOME
STRONG SUNDAY STARTING EARLY ON...AND THEN DIMINISH AND BECOME S TO
SW SUNDAY NT.  LOW LEVEL WIND SHEAR CAN DEVELOP SUNDAY MORNING IF
SFC WINDS DO NOT START TO PICK UP BY DAWN.

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

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: IF INCREASING LOW LEVEL FLOW DOES NOT REACH
SURFACE...THEY MAY BE A FEW HOUR WINDOW FOR LLWS HTS-CRW VCNTY
AROUND 10 TO 13Z SUNDAY. ALSO...TIMING OF ARRIVAL OF IFR CEILINGS AT
BECKLEY COULD VARY..FCST IS CURRENTLY RIGHT AT THE MVFR THRESHOLD
/1KFT/ 15Z SUNDAY TO 01Z MON.

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 04/19/15
UTC 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
EDT 1HRLY       02   03   04   05   06   07   08   09   10   11   12   13
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
HTS CONSISTENCY  H    H    H    H    H    H    H    H    M    M    M    L
BKW CONSISTENCY  H    H    H    M    M    M    M    M    M    H    H    M
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 06Z MONDAY...
IFR POSSIBLE MONDAY IN SHOWERS AND THUNDERSTORMS.

&&

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

&&

$$
SYNOPSIS...TRM/SL
NEAR TERM...TRM
SHORT TERM...SL
LONG TERM...MZ
AVIATION...TRM






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