Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 011038
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
638 AM EDT SUN MAY 1 2016

.SYNOPSIS...
UNSTABLE TODAY WITH COLD FRONT SINKING SOUTHEAST TONIGHT. DRIER
MONDAY. WAVE CROSSES TUESDAY. LARGE UPPER TROUGH BRINGS COOL AND
UNSETTLED WEATHER TOWARD END OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
LIKELY TO CATEGORICAL POPS ARE FORECAST FOR TODAY AS A WARM FRONT
LIFTS NORTH. ALTHOUGH RAINFALL ACCUMULATIONS HAVE BEEN LIGHT...IN
THE ORDER OF 0.25 IN THREE HOURS...THIS WILL PRIME THE SOILS TO
BECOME NEARLY SATURATED BY MID DAY.

MODELS SUGGEST SFC CAPE VALUES AROUND 2000 J/KG...ABOUT 50 KNOTS
OF DEEP LAYERED SHEAR AND PRECIPITABLE WATER AROUND 1.25 INCHES.
THESE PARAMETERS ARE NEEDED FOR THUNDERSTORM DEVELOPMENT. AFTERNOON
SHOWERS AND STORMS WILL BE CAPABLE TO PRODUCE MODERATE TO HEAVY
RAIN...POSING A THREAT FOR FLASH FLOODING. UNSTABLE CONDITIONS
TOGETHER WITH FREEZING LEVELS OF ABOUT 11500 FEET CAN PRODUCE HAIL
STONES SOME SEVERE.

WENT WITH THE SUPER BLEND GUIDANCE FOR TEMPERATURES THROUGH THE
PERIOD.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
SHOWERS WILL BE WINDING DOWN MONDAY MORNING. BRIEF RIDGING BUILDS
IN AND SHOULD SHOULD HOLD OFF ANY RAINFALL UNTIL LATE MONDAY
AFTERNOON OR EVENING AS SHORTWAVE CROSSES THE REGION MONDAY NIGHT.

MODELS ARE COMING INTO BETTER AGREEMENT FOR SYSTEM OVERNIGHT
MONDAY...BUT STILL A BIT OF SPREAD ON THE TIMING AND LOCATION OF
HEAVIEST PRECIP. HOWEVER...I CONTINUED THE TREND IN INCREASING
POPS MONDAY NIGHT. THERE SHOULD BE ENOUGH INSTABILITY FOR A FEW
STORMS AS WELL MONDAY EVENING. LARGE UPPER LOW STARTS TO DROP
SOUTHWARD OUT OF CANADA AND TROUGHING AXIS WILL MOVE OVER US
TUESDAY...WITH UNSETTLED WEATHER CONTINUING WITH A CHANCE OF
SHOWERS ONCE AGAIN.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
MODELS CONCUR ON A LARGE UPPER LEVEL LOW DOMINATING THE WEATHER
PATTERN THIS PERIOD...WITH EARLIER DIFFERENCES IN LATITUDE AND
DEPTH GREATLY DIMINISHED.

THE INSTIGATING UPPER LEVEL TROUGH DIGS INTO THE AREA TUESDAY
NIGHT AND WEDNESDAY. THIS DRIVES A SURFACE COLD FRONT THROUGH THE
AREA WEDNESDAY...WITH THE CHANCE FOR SHOWERS PUSHING FROM
NORTHWEST TO SOUTHEAST. STILL HAVE NO MENTION OF THUNDER WITH THIS
FRONT AS THE AIR AHEAD OF IT SHOULD BE ON THE DRY SIDE...BUT IT IS
NOT OUT OF THE QUESTION A CHANCE MAY EVENTUALLY NEED ADDED.

ONCE THE FRONT IS THROUGH...THE UPPER LEVEL TROUGH CLOSES OFF
WEDNESDAY NIGHT INTO THURSDAY SOMEWHERE OVER THE APPALACHIANS. IT
THEN MEANDERS SLOWLY FROM PA TO THE DELMARVA / JERSEY SHORE
THROUGH SATURDAY. THIS WILL BRING ABOUT UNSEASONABLY COOL WEATHER
WITH LOTS OF CLOUDS...AND A GOOD CHANCE FOR SHOWERS. THE CHANCE
FOR SHOWERS WILL BE GREATEST OVER THE HIGHER TERRAIN BENEATH THE
LOW UPPER LEVEL HEIGHTS AND TEMPERATURES...AND ALONG THE WESTERN
SLOPES ON NORTHWEST UPSLOPE FLOW.

TEMPERATURES ALOFT ARE PROGGED TO BE LOW ENOUGH FOR SNOW TO AT
LEAST MIX IN ACROSS THE VERY HIGHEST TERRAIN WHEN SURFACE
TEMPERATURES THERE WOULD BE AT THEIR LOWEST...EARLY FRIDAY AND
SATURDAY MORNINGS.

STILL HAVE THE CHANCE FOR THUNDER OUT OF THE FORECAST...BUT SOME
AFTERNOON CHARGE SEPARATION IS NOT OUT OF THE QUESTION BENEATH THE
LOW UPPER LEVEL HEIGHTS AND TEMPERATURES IN EARLY MAY.

THE LARGE SYSTEM STARTS TO PULL OUT SATURDAY NIGHT...PROMOTING
OVERNIGHT DRYING.

TEMPERATURES THURSDAY AND FRIDAY WERE LOWERED ON THE MIDNIGHT
SHIFT IN LIGHT OF INCREASING MODEL AGREEMENT ON THE LARGE UPPER
LEVEL LOW...AND NO FURTHER CHANGES WERE NEEDED FOR THE MOST PART.
TEMPERATURES EARLIER ON WERE CLOSE TO GUIDANCE BLENDS AND
ACCEPTED...AND A GUIDANCE BLEND WAS USED FOR SATURDAY AND
SATURDAY NIGHT.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/... DOPPLER RADAR SHOWS
NUMEROUS LIGHT TO MODERATE RAIN SHOWERS MOVING NORTHEAST ACROSS
EASTERN KY...AND SOUTHERN WV THIS MORNING. BRIEF IFR/LIFR
CONDITIONS CAN BE EXPECTED UNDER THE HEAVIEST SHOWERS OR STORMS.
OTHERWISE...VFR/MVFR CONDITIONS WILL PREVAIL UNDER RAIN SHOWERS.
THIS CONDITIONS ARE PRODUCED BY A SLOWLY MOVING WARM FRONT
EXPECTED TO LIFT NORTH BY 18Z.

BRIEF ISOLATED IFR CEILINGS WILL BE POSSIBLE AT MOST SITES LATER
TODAY. WHILE IFR VISIBILITIES WILL BE BRIEF.

SPC HAS THE ENTIRE AREA UNDER A SLIGHT RISK FOR SEVERE WEATHER.
EXPECT STORMS TO DEVELOP THIS AFTERNOON WHEN SFC BASED CAPE PEAKS
AT AROUND 2000 J/KG...DEEP LAYERED SHEAR AROUND 50 KNOTS AND
PRECIPITABLE WATER ABOUT 1.37 INCHES. EXPECT HEAVY DOWNPOURS...LARGE
HAIL...AND STRONG WIND GUSTS IN VICINITY OF STORMS.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: TIMING AND INTENSITY OF SHOWERS AND STORMS
COULD VARY. TIMING OF ANY IMPROVEMENT TO VFR LATER TODAY COULD
VARY FROM 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       10   11   12   13   14   15   16   17   18   19   20   21
EDT 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
CRW CONSISTENCY  M    H    H    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  L    M    M    M    M    M    H    H    H    H    H    H
BKW CONSISTENCY  M    M    M    M    H    H    H    H    H    H    H    H
EKN CONSISTENCY  M    M    M    M    H    H    H    H    H    H    H    H
PKB CONSISTENCY  M    H    H    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  M    H    H    H    H    H    H    H    H    H    H    H

AFTER 12Z MONDAY...
IFR POSSIBLE THROUGH LATE SUNDAY NIGHT WITH ADDITIONAL ROUNDS OF
SHOWERS AND THUNDERSTORMS..AND IN STRATUS LINGERING INTO MONDAY
MORNING.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...FLASH FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR WVZ005>011-
     013>020-024>040-046-047.
OH...FLASH FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR OHZ066-067-
     075-076-083>087.
KY...FLASH FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR KYZ101>103-
     105.
VA...NONE.

&&

$$
SYNOPSIS...ARJ/MPK
NEAR TERM...ARJ
SHORT TERM...MPK
LONG TERM...TRM
AVIATION...ARJ



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