Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 010000
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
800 PM EDT THU APR 30 2015

.SYNOPSIS...
VIGOROUS MID/UPPER LOW PRESSURE CROSSES TO OUR SOUTHEAST TONIGHT.
INSTABILITY SHOWERS THEN LINGERING LOWER CLOUDS/SHOWERS OVERNIGHT.
HIGH PRESSURE FOR THE WEEKEND...WITH A WARMING TREND INTO NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
800 PM UPDATE...

NOT MUCH CHANGE IN THE FCST WITH THE EVE UPDATE. FINESSED POPS
USING LATEST HRRR AS A BASE WHICH PIVOTS BANDS OF SHRA THRU
OVERNIGHT ACROSS S ZONES.

PREVIOUS DISCUSSION BELOW...
AN UPPER LEVEL LOW PRESSURE SYSTEM DROPS SOUTH INTO OH
TONIGHT...TURNING SOUTHEAST ACROSS EASTERN KY OVERNIGHT. SCATTERED
SHOWERS ARE NOTED ALONG THE PERIPHERY OF THIS CIRCULATION WITH
EMBEDDED THUNDERSTORMS SOUTH AND WEST OF ITS CENTER. TONIGHT THE
WEATHER REMAINS UNSETTLED WITH LIGHT SHOWERS DRIFTING EAST. FEW
THUNDERSTORMS CAN BE POSSIBLE ACROSS THE EXTREME SOUTHERN PORTIONS
OF WV...NORTHEAST OH...AND SOUTHWEST VA TONIGHT. AS THE LOW EXITS
SOUTHEAST...IMPROVING CONDITIONS WILL SPREAD FROM WEST TO EAST
EARLY FRIDAY.

MODELS SUGGEST THAT ABUNDANT LINGERING MOISTURE WILL PROVIDE FOR
LOW LEVEL CLOUDS OVERNIGHT INTO EARLY FRIDAY. BUFKIT SOUNDINGS
INDICATE DRIER AIR FILTERS IN FROM THE WEST LATE FRIDAY...PERHAPS
BRINGING PERIODS OF SUNSHINE DURING THE AFTERNOON HOURS ACROSS
SOUTHEAST OH.

WITH ABUNDANT CLOUDINESS...TEMPERATURES TONIGHT WILL BE IN THE
40S. FRIDAY...TEMPERATURES WILL RANGE FROM THE MID 60S
LOWLANDS...INTO THE MID 50S HIGHEST ELEVATIONS. WENT CLOSER TO THE
COOLER BIAS CORRECTED ECMWF FOR LOWS TONIGHT...AND WITH THE
CONSENSUS RAW FOR HIGHS ON FRIDAY.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
INSTABILITY AND LOW LEVEL UPSLOPE FLOW WANE FRI EVENING WITH LOSS OF
HEATING AND UPPER LEVEL TROUGH PULLING AWAY.  ANY MOUNTAIN SHOWERS
WILL DIE OFF BY MIDNIGHT AS A RESULT.

OTHERWISE HIGH PRESSURE SAILS SLOWLY ACROSS THE AREA THIS WEEKEND TO
PROVIDE NICE WEATHER.  UPPER LEVEL RIDGING BUILDS TO THE W OF THE
FCST AREA...BUT A WEAK S/W TROUGH CROSSING LATE SAT AND AN EVEN
WEAKER ONE LATE SUNDAY WILL BRING SOME MID AND HIGH CLOUD...AND
THERE WILL ALSO BE SOME AFTERNOON CU...SO THE DAYTIME HOURS WILL
BRING A MIX OF CLOUDS AND SUNSHINE.  LEFT THE SCHC FOR A SHOWER IN
THE WV MOUNTAINS SAT AFTERNOON ON ELEVATED HEATING...ALTHOUGH THE
AREA MAY BE UNDERNEATH WEAK RIDGING BETWEEN THE EXITING UPPER LEVEL
TROUGH...AND THE S/W COMING FROM THE W WHICH CROSSES SAT AFTERNOON
AND NT.

TEMPERATURES ARE CLOSE TO GUIDANCE AND NORMAL IN THIS RELATIVELY
TRANQUIL PATTERN...EXCEPT HIGHS SAT WERE A LITTLE ABOVE GUIDANCE AND
WERE LEFT ALONE IN LIGHT OF EARLY MAY SUNSHINE.  TRIED TO TWEAK
HIGHS SUNDAY UPWARD TOWARD THE LATEST MEX...AGAIN IN TH EARLY MAY
SUN.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
USED THE ECMWF ENSEMBLE MEAN AS THE BASIS FOR THE FORECAST. THIS
WOULD HAVE HIGH PRESSURE IN CONTROL FOR SUNDAY NIGHT AND MONDAY.
WITH THE HIGH SLIDING EASTWARD...MOISTURE INCREASES. THIS MAY ALLOW
FOR SOME AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS ON TUESDAY.
BY WEDNESDAY...A FRONTAL BOUNDARY ATTEMPTS TO SLIDE INTO SOUTHEAST
OHIO AND NORTHERN WEST VIRGINIA BEFORE RETURNING BACK NORTHWARD ON
THURSDAY.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR CONDITION WILL SLOWLY DETERIORATE TO MVFR ALONG WITH SHOWERS
ASSOCIATED WITH AN UPPER LEVEL LOW PRESSURE SYSTEM PASSING THRU. THE
LINE OF MAINLY SHOWERS WILL GRADUALLY PIVOT S TONIGHT. THUNDER CAN
NOT BE RULED OUT AT BKW WHEN THE LINE PASS THROUGH THERE THIS EVE...BUT
PROBABILITIES ARE TOO LOW TO INCORPORATED IN TAF AT THIS TIME.

MODELS SUGGEST LOW STRATUS DEVELOPING OVERNIGHT TO PRODUCE
MVFR/IFR CIGS AT MOST PLACES. BOUNDARY LAYER WINDS ARE ABOUT 5
TO 10 KNOTS...THEREFORE...FOG WILL STRUGGLE TO FORM AT MOST
PLACES...EXCEPT ALONG DEEPER RIVER VALLEYS. LOW CEILINGS SHOULD
LAST THROUGH 13-14Z. IMPROVING CONDITIONS ARE EXPECTED AFTER 15Z
WITH KCRW/KBKW THE LAST TO IMPROVE TO VFR BKN CIGS.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY...

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: LOWERING CIG TONIGHT MAY TAKE LONGER TO
DEVELOP THAN 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                                                            FRI 05/01/15
UTC 1HRLY       00   01   02   03   04   05   06   07   08   09   10   11
EDT 1HRLY       20   21   22   23   00   01   02   03   04   05   06   07
CRW CONSISTENCY  H    M    H    H    H    H    M    H    H    H    H    H
HTS CONSISTENCY  H    H    H    H    H    H    H    M    M    M    H    H
BKW CONSISTENCY  M    M    M    L    L    H    H    H    M    M    H    H
EKN CONSISTENCY  H    H    M    L    L    L    L    L    L    H    H    H
PKB CONSISTENCY  H    H    H    H    H    H    H    M    L    L    L    L
CKB CONSISTENCY  H    H    M    M    H    H    M    M    M    M    L    L

AFTER 00Z SATURDAY...
NO WIDESPREAD IFR CONDITIONS EXPECTED.

&&

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

&&

$$
SYNOPSIS...ARJ/TRM/RPY
NEAR TERM...ARJ/30
SHORT TERM...TRM
LONG TERM...RPY
AVIATION...30/ARJ







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