528 
FXUS61 KRLX 211415
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1015 AM EDT FRI SEP 21 2012

.SYNOPSIS...
UPPER LEVEL LOW APPROACHES FROM NORTHWEST TODAY...WITH SURFACE
LOW SLIDING IN FROM THE WEST. COLD FRONT PASSES SATURDAY. COOLER
SUNDAY AND MONDAY.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
SENT A QUICK UPDATE FOR SKY COVER...HOURLY DEWPOINTS AND
TEMPERATURES. REST OF FORECAST CONTINUES REPRESENTATIVE OF
EXPECTED CONDITIONS. 

PREVIOUS DISCUSSION BELOW...
630 AM UPDATE...CLOUDS FROM OVERNIGHT BEGINNING TO MOVE NORTH AND
CLEAR THE AREA...BUT IT WILL NOT BE TOO LONG BEFORE NEXT
DISTURBANCE BEGINS INCREASING CLOUDS AGAIN FROM THE WEST.
CONVECTIVE COMPLEX IN SOUTHERN MO ASSOCIATED WITH VORT MAX THAT IS
EXPECTED TO TURN NORTHEAST AND CROSS CENTRAL OHIO THIS
AFTERNOON...IF IT DOES NOT START TURNING SOON...IT MAY PASS CLOSER
TO/OVER CWA WHICH WOULD REQUIRE AN INCREASE IN POPS. FOR NOW JUST
UPDATED GRIDS BASED ON CURRENT OBS AND TRENDS...BUT NO SIGNIFICANT
CHANGES MADE.

PREVIOUS DISCUSSION...UPPER LEVEL LOW WILL BE DROPPING INTO
WESTERN GREAT LAKES TODAY AND TONIGHT...AS A SURFACE LOW MOVES
TOWARDS THE OHIO RIVER VALLEY FROM THE WEST. A WARM FRONT WILL BE
IN THE AREA THIS AFTERNOON...WITH INCREASING POPS ALONG THE OHIO
RIVER TOWARDS 00Z AS FRONT/500MB RIPPLES MEANDER THROUGH. LOW
PRESSURE SYSTEM WILL MOVE ACROSS SOUTHERN OHIO OVERNIGHT...WITH
COLD FRONT JUST REACHING NW CWA BORDER AT END OF NEAR TERM PERIOD.
THIS IS A BIT SLOWER THAN PREVIOUS FORECAST...SO SLOWED ENTIRE
SYSTEM A FEW HOURS.

COOLED HIGHS FOR THIS AFTERNOON ONE TO TWO DEGREES WITH CLOUDS 
THICKENING UP. WENT WITH SEMI NON-DIURNAL LOWS OVERNIGHT...WITH 
DROPPING TEMPS THROUGH ABOUT 2AM...AND THEN NEAR STEADY FOR THE REST 
OF THE EARLY MORNING. EXPECTING TIGHTENING PRESSURE GRADIENT AHEAD 
OF THE COLD FRONT...SO WINDS SHOULD NOT DECOUPLE EXCEPT FOR POSSIBLY 
IN THE MOST SHELTERED VALLEYS.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH MONDAY/...
AS DYNAMICS IN THE MID/UPPER LEVELS LIFT QUICKLY NORTH SATURDAY 
MORNING INTO ONTARIO...LEAVING THE FRONT/WIND SHIFT TO CROSS OUR CWA 
DURING THE DAY WITH LIMITED MOISTURE AND NOT MUCH SUPPORT ALOFT.
WILL LEAVE POPS MOSTLY 30 SOUTH TO 40/50 NORTH WITH AMOUNTS MOSTLY A 
TENTH OF AN INCH OR LESS IF IT DOES OCCUR.  

A SECONDARY 500 MB VORT MAXIMUM SWINGS THROUGH THE NORTHERN HALF OF 
OHIO BY 00Z SUNDAY. DID INCREASE POPS BACK INTO THE 20 TO 30 RANGE 
FOR THE POSSIBILITY OF A FEW LIGHT SHOWERS REACHING AS FAR SOUTH AS 
EASTERN OHIO INTO NORTHERN WEST VIRGINIA SATURDAY EVENING.

850 MB THERMAL TROF OF PLUS 1C TO PLUS 3C PASSES AROUND 12Z 
MONDAY...ALONG WITH ANOTHER MID LEVEL DISTURBANCE. SO PATCHES OF 
STRATOCUMULUS CLOUDS MAY STILL BE AN ISSUE OVERNIGHT SUNDAY NIGHT 
INTO MONDAY MORNING...LIMITING THE FROST POTENTIAL IN THE MOUNTAINS. 
WILL LEAVE THE MENTION OF THAT IN THE HAZARDOUS WEATHER 
POTENTIAL...AND WILL ADD THAT SAME FROST POTENTIAL FOR MONDAY 
NIGHT/DAWN TUESDAY...WHEN CLOUDS SHOULD BE LESS AN ISSUE.

FIGURING THE LOWEST DAYTIME MAX TEMPERATURES WILL BE SUNDAY...EVEN
HOLDING SNOWSHOE IN THE 40S.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
GENERALLY FOLLOWED HPC THINKING IN THE EXTENDED. THIS WILL UPR TROF 
LIFTING OUT EARLY NEXT WEEK WITH SOME SHOWERS POSSIBLE MID WEEK FROM 
AN APPROACHING FRONT. MODERATING TEMPS WILL BE FEATURED...WITH 
READINGS CLIMBING TO SEASONABLE LEVELS.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
CLOUDS BEGINNING TO PULL NORTH...WITH CLEARING TAKING PLACE ACROSS
SOUTHERN CWA. CLOUDS HAVE REDUCED CHANCES FOR FOG AT MOST
LOCATIONS...WHERE T/TD SPREADS ARE STILL 5 DEGREES PLUS AT ALL TAF
SITES EXCEPT KEKN...WHERE DENSE FOG HAS BEEN IN AND OUT ALL NIGHT.
ALL THE FOG THAT IS LEFT WILL DISSIPATE 12-13Z WITH VFR CONDITIONS
EXPECTED FOR THE REST OF THE DAY. LOW PRESSURE APPROACHES LATER
TODAY...INCREASING CHANCE OF SHOWERS FROM LATE AFTERNOON INTO
TONIGHT...ESPECIALLY ACROSS THE NORTH. WILL SEE PRESSURE GRADIENT
STARTING TO TIGHTEN...RESULTING IN A S/SW FLOW PERSISTING TODAY
AND TONIGHT. COMBINED WITH CLOUDS...THIS SHOULD LIMIT FOG CHANCES
OVERNIGHT.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SATURDAY...
     
FORECAST CONFIDENCE: HIGH.

ALTERNATE SCENARIOS: SMALL CHANCE OF MVFR IN SHOWERS OVERNIGHT.

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       14   15   16   17   18   19   20   21   22   23   00   01
EDT 1HRLY       10   11   12   13   14   15   16   17   18   19   20   21
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    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 12Z SATURDAY...
NO WIDESPREAD IFR CONDITIONS EXPECTED.

&&

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

&&

$$
SYNOPSIS...KTB/MZ
NEAR TERM...ARJ/MZ
SHORT TERM...KTB
LONG TERM...30
AVIATION...MZ