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Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 201755
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
155 PM EDT MON MAY 20 2013

.SYNOPSIS...
UPPER TROUGH AXIS SLOWLY PASSES TODAY. NEW FRONT MOVES ACROSS
THURSDAY. COOLER HIGH PRESSURE FRIDAY AND THE WEEKEND.

.NEAR TERM /THROUGH TONIGHT/...

-- Changed Discussion --130 PM UPDATE...
SHOWERS AND EMBEDDED THUNDERSTORMS BEGINNING TO PUSH EASTWARD WITH
S/W TROUGH AND VORT MAX...AND WEAKEN AS THEY PUSH INTO REGION WITH
LESS INSTABILITY. LOWERED MAX TEMPS JUST A BIT MAINLY ACROSS
EASTERN ZONES THIS AFTERNOON WITH CONTINUED CLOUD COVER...BUT WITH
SOME BREAKS IN THOSE CLOUDS FURTHER WEST...HESITANT TO LOWER THOSE
TEMPS TOO MUCH ACROSS CENTRAL CWA WHERE SOME LATE DAY SUN MAY
RESULT IN A QUICK BUMP IN TEMPS PRIOR TO 21Z-22Z. ALSO ALLOWING
FOR FLASH FLOOD WARNING TO EXPIRE JUST BEFORE TOP OF THE HOUR WITH
HEAVY RAINS ENDING IN THOSE LOCATIONS WITH SMALL STREAMS BEGINNING
TO RECEDE.

PREV DISCUSSION...
5H RIDGE AXIS TO NUDGE NORTHEASTWARD ALONG THE OHIO RIVER VALLEY
THROUGH THE PERIOD. GENERAL FORECASTED TRENDS ARE ON TRACK. LOW TO
MID LEVEL MOISTURE WILL BE SHUNTED SLIGHTLY TO THE EAST TODAY WITH
DRYING OF THE ATMOSPHERIC COLUMN CONTINUING ON WESTERN PERIPHERY
OF UPPER RIDGE. ENOUGH MOISTURE WILL REMAIN ALONG A LINE FROM KEKN
TO KBKW AND POINTS TO THE EAST FOR ANOTHER ROUND OF DIURNALLY
DRIVEN SHOWERS AND THUNDERSTORMS. DRY AIR WILL THEN WORK ITS WAY
ACROSS MOST OF THE AREA BY TONIGHT...BRINGING AN EARLIER END TO
MOST SHOWER ACTIVITY FOR THE OVERNIGHT HOURS AS WE HAVE SEEN FOR
THE PAST FEW DAYS. DID NOT STRAY TOO FAR FROM PREVIOUS FORECAST
TEMP TRENDS AS VALUES REMAIN ON TRACK WITH EXPECTED TRENDS.-- End Changed Discussion --

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
SHORT TERM PERIOD STARTS OUT WITH THE CWA IN THE WARM SECTOR OF LOW
PRESSURE SYSTEM THAT WILL PUSH EAST ACROSS THE GREAT LAKES REGION
DURING THE PERIOD...AND UPPER LEVEL RIDGE ACROSS THE EASTERN U.S. AS
A RESULT...EXPECTING RATHER WARM TEMPERATURES TO DEVELOP ACROSS THE
REGION IN THE SHORT TERM...PARTICULARLY ON TUESDAY...WHEN 500MB
HEIGHTS AROUND 582DAM AND 850MB TEMPS AVERAGING AROUND 17-18C.
EXPECTING TEMPERATURES ON TUESDAY TO RANGE IN THE UPPER 80S TO LOWER
90S FOR MANY LOCATIONS...AND THIS COMBINED WITH DEW POINTS IN THE
60S ACROSS MUCH OF THE AREA...WILL MAKE FOR A SOMEWHAT UNPLEASANT
DAY. WITH THE HUMID...UNSTABLE AIRMASS IN PLACE...STILL EXPECT A
CHANCE FOR THUNDERSTORMS TO DEVELOP IN DAYTIME HEATING...DESPITE
UPPER RIDGING IN PLACE.

ATTENTION THEN SHIFTS TO A COLD FRONT...ASSOCIATED WITH THE
AFOREMENTIONED LOW...WHICH WILL ENTER SOUTHEAST OHIO BY THURSDAY
MORNING. OUT AHEAD OF THE FRONT...PLENTY OF INSTABILITY AND DYNAMICS
WILL HELP TO GENERATE SHOWERS AND THUNDERSTORMS...SOME OF WHICH
COULD BE STRONG...PARTICULARLY IN SOUTHEAST OHIO/EASTERN KY/WV
COUNTIES NEAR TO THE OHIO RIVER. MODELS INDICATING 0-6KM SHEAR OF
AROUND 30+ KTS...AND A FREEZING LEVEL OF AROUND 10-11K FEET. HAIL
AND STRONG WINDS WILL BE FACTORS WITH ANY STORMS THAT ARE ABLE TO
DEVELOP. WILL PUT A MENTION OF SEVERE INTO THE HWO. OF
COURSE...CLOUD COVER...AND ANY CHANGES IN THE TIMING OF THE FRONTAL
BOUNDARY/ASSOCIATED UPPER TROUGH MAY END UP MITIGATING THE THREAT.

COLD FRONT WILL CONTINUE TO PUSH THROUGH THE REGION ON
THURSDAY...FOLLOWED BY A SECONDARY COLD FRONT THURSDAY NIGHT/EARLY
FRIDAY...WHICH WILL FINALLY USHER IN COOLER AND DRIER AIR INTO THE
REGION.

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
HAVE GENERALLY FOLLOWED WPC THINKING FOR THIS PORTION OF THE FORECAST.

COLD FRONT SHOULD BE LOCATED SOUTHEAST OF THE REGION AT THE
BEGINNING OF THE PERIOD...WITH HIGH PRESSURE BUILDING IN. CHANCE
OF SHOWERS AND STORMS WILL END FROM THE NORTHWEST THURSDAY NIGHT
INTO FRIDAY. HOWEVER...A MID-LEVEL DISTURBANCE MOVING SOUTHEAST
WILL INCREASE THE CHANCES FOR PRECIPITATION ON FRIDAY....MAINLY IN
THE MOUNTAINS AND ADJACENT COUNTIES.

HIGH PRESSURE WILL THEN BE IN CONTROL OF THE AREA INTO MONDAY.
HOWEVER...A WEAK MID-LEVEL DISTURBANCE WILL SLIDE SOUTHEAST SATURDAY
NIGHT INTO SUNDAY.

A WARM FRONT WILL DEVELOP AND APPROACH THE REGION ON MONDAY. ECMWF
SUGGESTS THERE WILL BE A CHANCE OF SHOWERS AND STORMS MONDAY
AFTERNOON...ESPECIALLY ACROSS THE SOUTH. BECAUSE OF UNCERTAINTY...HAVE
LEFT THESE CHANCES OUT OF THE FORECAST FOR NOW.

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
MVFR TO LOW VFR CIGS ACROSS MUCH OF THE AREA CURRENTLY SHOULD
SCATTER WEST TO EAST AS THE AFTERNOON PROGRESSES AS THE LAST OF
THE PRECIP CONTIUES TO PUSH EASTWARD. VIS MAY ONCE AGAIN BECOME AN
ISSUE OVERNIGHT AND TOWARDS DAWN...PARTICULARLY AT LOCATIONS WHICH
RECEIVED RAINFALL TODAY SUCH AS CRW AND EKN. EARLY MORNING REDUCED
VIS/LOW STRATUS SHOULD ONCE AGAIN GIVE WAY TO VFR CONDTIONS BY
MID-MORNING. WINDS GENERALLY REMAIN LIGHT OUT OF THE S/SW THROUGH
THE VALID PERIOD.

FORECAST CONFIDENCE...MEDIUM.

ALTERNATE SCENARIOS: SOME UNCERTAINTY ON FOG DENSITY...LOW
STRATUS...AND AREAL COVERAGE OVERNIGHT AND EARLY MORNING TUESDAY.

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 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY M H H H H H H H H H H H
HTS CONSISTENCY M H H H H H H H H H H H
BKW CONSISTENCY M H H H H H H H H H H H
EKN CONSISTENCY H H H M H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY M M M H H H H H H H H H

AFTER 18Z TUESDAY...
IFR CONDITIONS POSSIBLE WEDNESDAY WITH SHOWERS AND THUNDERSTORMS.-- End Changed Discussion --

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

$$
SYNOPSIS...KMC/SL
NEAR TERM...KMC/50
SHORT TERM...SL
LONG TERM...JSH
AVIATION...50

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