Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 300526
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
126 AM EDT SAT APR 30 2016

.SYNOPSIS...
DRIER AIR LINGERS INTO TONIGHT. WARM FRONTAL SHOWERS INCREASE
SATURDAY. MORE INSTABILITY SUNDAY WITH COLD FRONT SINKING SOUTHEAST
SUNDAY NIGHT. DRIER MONDAY. WAVE PASSES TO THE SOUTHEAST TUESDAY.

&&

.NEAR TERM /THROUGH TODAY/...
650 PM UPDATE...INCREASED SKY COVER ACROSS THE CWA THIS EVENING AS
OVERCAST CIRRUS HAS TAKEN HOLD. THIS MAY HAVE AN EFFECT ON FOG
DEVELOPMENT TONIGHT ACROSS THE NORTH. OTHERWISE...PREVIOUS
FORECAST OK.

PREVIOUS DISCUSSION FOLLOWS...
AFTER YESTERDAYS SHOWERS/STORMS THAT FORMED DURING THE MID
AFTERNOON AND LINGERED INTO THE EVENING...PLUS THE LOCALIZED
HAILERS...WE WELCOME THE DRIER AIR TODAY. THE COLD AIR ADVECTION
HELPED TO HOLD THE LOW CLOUDS THE LONGEST FRIDAY IN EASTERN
OHIO...MOSTLY NORTH OF THE ROUTE 50 CORRIDOR.

BEFORE WE LOOK OUT OUR WEST AND SOUTHWEST WINDOW...STILL NEED
TO MONITOR THE MID LEVEL DISTURBANCE DROPPING SOUTHEAST THROUGH
PENNSYLVANIA THIS EVENING.  NO REASON TO REMOVE OUR SLIGHT CHANCE OF
A RAIN SHOWER IN OUR EXTREME NORTHEAST FOR EARLY THIS EVENING.

WITH CLEARING EXPECTED...DEW POINTS SHOULD LOWER SOME FOR THE REST
OF THIS AFTERNOON IN THE NORTH.  THINKING THE CIRRUS AND APPROACHING
MID DECK WILL STAY THINNER IN THESE NORTHERN COUNTIES LATE TONIGHT.
AS A RESULT...WITH THE WETTER GROUND...AND STILL A LOCAL MAXIMUM IN
DEW POINT....WILL INSERT SOME FOG AFTER 04Z IN EASTERN OHIO FROM THE
HOCKING VALLEY ON NORTH AND ALSO FOR THE ROUTE 50 CORRIDOR IN WEST
VIRGINIA...PLUS THE TYGART VALLEY AROUND ELKINS.

FURTHER SOUTH...IN THE DRIER AIR...NO FOG TONIGHT WITH
THE HIGH CLOUDS THICKENING INTO MID DECK.

WILL HAVE RAIN SHOWERS SPREADING N DURING THE 12Z TO 18Z TIME
FRAME.  MAIN CHANCE WAS TO TRY TO LOWER POPS FROM CRW ON SOUTH
TOWARD WILLIAMSON AND THE SOUTHERN COAL FIELDS AS THE PSEUDO WARM
FRONTAL LIFT SHIFTS NORTH.  WITH SOUTHEAST FLOW THOUGH...FIGURING
LOWER CLOUDS ALONG EASTERN SLOPES...WILL NOT REDUCE POPS LATE IN
THE DAY FOR THOSE EASTERN SLOPES INCLUDING POCAHONTAS COUNTY.

WILL KEEP CHANCE OF THUNDER AOB 14 PCT.  COULD NOT RULE OUT AN
EMBEDDED T IN OHIO ASSOCIATED WITH THE BEST LIFT...BUT THINK HIGHER
CHANCES ARE SATURDAY NIGHT AND SUNDAY.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
A RATHER MESSY FORECAST STILL FOR SATURDAY NIGHT THROUGH SUNDAY.
LOOKS LIKE WE MAY HAVE A DRY PERIOD SATURDAY NIGHT ACROSS THE
WEST...BUT STILL HANGING ONTO CHANCE POPS. HAVE LIKELY POPS ACROSS
THE MOUNTAINS. ENTIRE CWA SHOULD GET SOME RAIN ON SUNDAY...BUT
TIMING IS RATHER DIFFICULT. NAM SHOWS SOME BREAKS DURING THE
AFTERNOON...WITH THE MAIN SLUG IN THE MORNING...WHILE GFS AND ECMWF
HAVE LESS DEFINITION. THIS ALL MAKES IT DIFFICULT TO HIGHLIGHT WHEN
THESE DRIER PERIODS MAY BE ON SUNDAY...SO GENERALLY KEPT HIGH POPS
THROUGHOUT THE DAY...GRADUALLY TAPERING OFF SUNDAY NIGHT INTO
MONDAY. DESPITE THE SHOWERS AND CLOUDS AROUND IN THE MORNING...THE
NAM STILL INDICATED SOME DECENT INSTABILITY SUNDAY. IN
ADDITION...NAM BULK SHEAR HAS INCREASED IN RECENT RUNS -- NOW
GENERALLY 40-50KTS SUNDAY AFTERNOON. THINK THE MORNING ACTIVITY
SHOULD LIMIT INSTABILITY SOME...BUT STILL CANNOT RULE OUT SOME
STRONGER THUNDERSTORMS WITH GUSTY WINDS AND POSSIBLY HAIL.
ALONG
PWATS LOOK TO BE THE HIGHEST SATURDAY NIGHT ACROSS THE WESTERN HALF
OF THE CWA...MAXING OUT JUST OVER 1.5 IN. GENERALLY HAVE ABOUT 1
INCH OF QPF SATURDAY NIGHT THROUGH SUNDAY NIGHT. BUT ANY AREAS THAT
RECEIVE REPETITIVE DOWNPOURS COULD START EXPERIENCING MINOR WATER
ISSUES. WILL KEEP MENTION IN HWO FOR NOW.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
MODELS STILL DIFFER ON WAVE CROSSING THE MIDDLE ATLANTIC STATES
TUESDAY INTO WEDNESDAY...BUT THERE IS INCREASING CONSENSUS ITS
MOISTURE AFFECTS AT LEAST SOUTHEASTERN PORTIONS OF THE FORECAST
AREA.

MODELS ALSO REMAIN A BIT OUT OF SYNC WITH A COUPLE OF NORTHERN
STREAM SYSTEMS THAT CROSS MID TO LATE WEEK. THE GFS BRINGS COLD
FRONTS ACROSS LATE WEDNESDAY AND THEN FRIDAY NIGHT...WHILE THE
ECMWF TIMING IS EARLY THURSDAY ON THE FIRST COLD FRONT...AND THEN
IT JUST CLOSES OFF A LARGE UPPER LOW THAT THEN SLOWLY LUMBERS
THROUGH THE AREA AT LEAST THE END OF THE PERIOD. THE GFS IS
FARTHER NORTH AND DEEPER WITH THE UPPER LOW...HENCE THE MORE
DEFINED SECOND SURFACE FRONT. AS FOR THE UPPER LOWS...THIS IS A
CLASSIC CASE OF DEEPER...BY ABOUT 350M...AND FARTHER NORTH VERSUS
WEAKER AND FARTHER SOUTH.

THE CURRENT FORECAST BRINGS FRONTS AND THE ASSOCIATED CHANCE FOR
SHOWERS ACROSS WEDNESDAY AND FRIDAY NIGHTS...SIMILAR TO THE WPC
DEPICTION.

KEPT LOWS CLOSE TO PREVIOUS FORECAST AND A GUIDANCE BLEND. BLENDED
IN GFS-BASED GUIDANCE FOR HIGHS...A LITTLE LOWER THAN PREVIOUS
FORECAST FOR THE MOST PART.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
OVERNIGHT...VFR CONDITIONS WILL PREVAIL...EXCEPT AT EKN...PKB...AND
CKB THAT COULD SEE SOME MVFR/IFR FOG DURING THE PREDAWN HOURS.
SATELLITE IMAGES SHOW HIGH CLOUDS CREEPING IN FROM THE SOUTH AND
WEST...SHOULD GENERALLY PREVENT DENSE FOG DEVELOPMENT OVERNIGHT.

A WARM FRONT LIFTS NORTH ON SATURDAY...WITH SCATTERED SHOWERS AND
ISOLATED STORMS DURING THE EARLY AFTERNOON. WIDESPREAD MVFR
CONDITIONS DEVELOPING AFTER 15-18Z...PARTICULARLY ACROSS THE
EASTERN SLOPES OF THE HIGHER TERRAIN AND AT SITES SUCH AS KBKW AS
A SOUTHEASTERLY FLOW TAKES HOLD. WV LOWLANDS MAY BE SLOWER TO
DEVELOP MVFR CONDITIONS IN THE SOUTHEASTERLY DOWNSLOPING FLOW.

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

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: CLOUD COVER COULD PREVENT FOG DEVELOPMENT
TONIGHT. TIMING...COVERAGE AND DURATION OF ANY FOG OVERNIGHT
TONIGHT COULD VARY. TIMING AND DEVELOPMENT OF MVFR CONDITIONS ON
SATURDAY 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.

DATE                                             SAT 04/30/16
UTC 1HRLY       03   04   05   06   07   08   09   10   11   12   13   14
EDT 1HRLY       23   00   01   02   03   04   05   06   07   08   09   10
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    H    H    H
EKN CONSISTENCY  H    H    M    L    L    L    L    L    L    L    H    H
PKB CONSISTENCY  H    H    M    L    L    L    L    L    L    L    M    H
CKB CONSISTENCY  H    H    M    L    L    L    L    L    L    L    H    H

AFTER 06Z SUNDAY...
IFR POSSIBLE AGAIN SATURDAY NIGHT INTO SUNDAY NIGHT WITH ADDITIONAL
ROUNDS OF SHOWERS AND THUNDERSTORMS..AND IN STRATUS LINGERING INTO
MONDAY MORNING.

&&

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

&&

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


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