Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 201031
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
630 AM EDT SAT SEP 20 2014

.SYNOPSIS...
HIGH PRESSURE MOVING OFF NORTHEAST COAST...ALLOWS SOUTHERLY FLOW TO
BRING WARMER...BUT STILL MAINLY DRY WEATHER TODAY.  A COLD FRONT
CROSSES SUNDAY AFTERNOON.  FALL HIGH PRESSURE DOMINATES NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...
FCST ON TRACK.

PREV DISCN...
UPSLOPE INDUCED LOW CLOUDS ALONG THE EASTERN SLOPES OF THE WV
MOUNTAINS WERE BEGINNING TO ERODE FROM THE S AND W...A TREND THAT
SHOULD CONTINUE TODAY AS THE FLOW CONTINUES TO VEER THROUGH S.

THIS WARM ADVECTION VEERING WAS ALSO ASSOCIATED WITH A STRATOCU DECK
FORMING TO THE W OF THE AREA IN THE THETA E AXIS.  THIS MAY
EVENTUALLY CONVERT AS SPOTTY SHOWERS W OF HTS LATER THIS MORNING.
MODELS SUGGESTS SPOTTY FRONTOGENETIC FORCING INTO THIS AFTERNOON
RIDING UP THE MIDDLE OHIO VALLEY WITH SUFFICIENT MOISTURE H85-H7 TO
PERHAPS STAND UP A SHOWER...ALTHOUGH NEAR TERM MODELS DO NOT OUTPUT
ANY RAINFALL AMOUNTS.  OTHERWISE WILL HAVE A SCT-BKN CU / STRATOCU
FIELD THIS AFTERNOON.

CLOUDS INCREASE AS A COLD FRONT APPROACHES TONIGHT.  LINE OF
CONVECTION WAS NEARLY CO-LOCATED WITH ASSOCIATED COLD FRONT OVER
THE MIDWEST EARLY THIS MORNING.  HAVE CHC SHRA/TSRA ENTERING THE
AREA FROM THE NW AROUND 06Z AND REACHING THE OHIO RIVER BY 12Z SUN
IN ASSOCIATION WITH THIS FEATURE.  THIS IS CLOSE TO MODELS WHICH
HAVE COME CLOSER TOGETHER FOR THE NEAR TERM PERIOD.  INSTABILITY
BECOMES ELEVATED AS THUNDER ROLLS INTO THE AREA OVERNIGHT TONIGHT.

HIGHS TODAY WERE CLOSER TO STRAIGHT GUIDANCE RATHER THAN THE LOWER
BIAS CORRECTED OUTPUT.  LITTLE CHANGE NEEDED OTHER THAN TO LOWER THE
EASTERN SLOPES A BIT...WITH DOWNSLOPE SRLY FLOW W OF THE MOUNTAINS.
BLENDED IN BIAS CORRECTED MET FOR LOWS TONIGHT AS THE MAV LOOKED TOO
LOW ALL AROUND EVEN WITH A BIT LESS FLOW COMPARED WITH THIS MORNING.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
COLD FRONT ACROSS NORTHWEST OHIO AND CENTRAL INDIANA AT BEGINNING OF
PERIOD...PUSHING EAST THROUGH THE CWA DURING THE DAY SUNDAY...AND TO
THE EAST OF THE HIGHER TERRAIN BY SUNDAY NIGHT. NAM STILL THE SLOWER
OF THE SOLUNS...BUT IS STARTING TO COME INTO BETTER AGREEMENT WITH
FASTER GFS/ECMWF. CONTINUED TO LEAN FORECAST TOWARDS GFS SOLUN.

COULD SEE ISOLATED STRONG WIND GUSTS SUNDAY AFTERNOON...MAINLY
SOUTHEAST OHIO AND NORTHERN WV COUNTIES ON SUNDAY WITH ANY
CONVECTION THAT DEVELOPS. SPC CONTINUES TO MAINTAIN A SEE TEXT OFF
TO OUR NORTHEAST.

UPPER TROUGH WILL SWING THROUGH THE AREA SUNDAY NIGHT/MONDAY...WITH
CLOUDS...AND PERHAPS SOME LIGHT PRECIPITATION OR DRIZZLE LINGERING
ACROSS THE CWA SUNDAY NIGHT INTO MONDAY...PARTICULARLY THE
WV/SOUTHWEST VA ZONES. HELD ONTO CLOUD COVER ACROSS THE
AFOREMENTIONED ZONES INTO MUCH OF THE DAY MONDAY...WITH HIGHER
TERRAIN COUNTIES LAST TO CLEAR.  HIGH PRESSURE WILL BUILD IN FOR
TUESDAY FOR A RETURN TO DRIER WEATHER.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
MODELS SHOWING A FALL HIGH PRESSURE SYSTEM OVER THE REGION THROUGH
THE PERIOD.

&&

.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
THE AREA WILL BE IN A SRLY FLOW BETWEEN HIGH PRESSURE WELL TO THE
E...AND A COLD FRONT APPROACHING FROM THE W.  THIS WILL KEEP VFR
CONDITIONS FOR THE MOST PART WITH SCT STRATOCU AOA 5 KFT...AND FLOW
JUST STRONG ENOUGH TO PRECLUDE DENSE FOG IN MOST CASES.

THERE ARE A FEW CAVEATS.

MOISTURE IN S TO SE FLOW ALONG THE EASTERN SLOPES CONTINUES TO
ERODE.  IT STILL HAS ONE LAST CHANCE TO GET INTO BKW FOR A TIME THIS
MORNING...ON MIXING AFTER SUNRISE.  CIGS WOULD BE 1-2 KFT SHOULD IT
OCCUR.

EARLY MORNING LLJ AOA 3 KFT CLOSE TO 40 KTS BUT 20 KTS AT 2 KFT FROM
RADAR.  THIS 20 KT CHANGE OVER 2 KFT MAKES LLWS CRITERIA OF 20 KTS
WITHIN A 200FT LAYER EXISTING WITHIN 2 KFT OF THE SFC VERY UNLIKELY.

DENSE FOG MAY FORM LATE OVERNIGHT TONIGHT IN THE TYGART VALLEY / EKN
/ AHEAD OF THE CLOUDS APPROACHING FROM THE W...AS OFFSHORE HIGH
PRESSURE RIDGES BACK INTO THE CENTRAL APPALACHIANS...ACTUALLY
RESULTING IN LESS FLOW COMPARED WITH THIS MORNING.

SFC FLOW WILL AVERAGE FROM THE S THROUGH THE PERIOD...A BIT GUSTY ON
THE RIDGES AND HILLTOPS TODAY.  THE WIND WILL TEND TO VEER TOWARD SW
DURING TODAY AND BACK TOWARD SE TONIGHT...EXCEPT IT WILL VEER TOWARD
SW LATE OVERNIGHT TONIGHT AS THE COLD FRONT APPROACHES.  FLOW ALOFT
WILL REMAIN MODERATE SW.

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

FORECAST CONFIDENCE: MEDIUM TO HIGH.

ALTERNATE SCENARIOS: MVFR CIGS MAY NEVER FORM AT BKW THIS MORNING.
BKW WINDS...GUSTY AT TIMES...MAY VARY FROM FCST TODAY.  THE DENSE
FOG CODED UP FOR LATE OVERNIGHT TONIGHT IN THE TYGART VALLEY / EKN /
MAY NOT BE AS DENSE AS FCST.

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 09/20/14
UTC 1HRLY       08   09   10   11   12   13   14   15   16   17   18   19
EDT 1HRLY       04   05   06   07   08   09   10   11   12   13   14   15
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  M    L    L    L    L    M    M    M    M    H    H    H
EKN CONSISTENCY  M    M    H    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  H    M    M    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 12Z SUNDAY...
BRIEF IFR CONDITIONS POSSIBLE SUNDAY IN SHOWERS/THUNDERSTORMS.

&&

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

&&

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






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