-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRLX 171529
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1116 AM EDT FRI MAY 17 2013

.SYNOPSIS...
STATIONARY FRONT REMAINS OVER THE AREA INTO THE WEEKEND.
UPPER LEVEL SHORTWAVE PASSES SOUTH. NEW FRONT APPROACHES WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
1100 AM MESOSCALE UPDATE...

FG HAS BURNED OFF THIS MORNING...LEAVING AREAS OF ALTOCU...MAINLY
ACROSS SE OH AND THE N MTNS. LCL AND HI RES MDLS ARE IN DECENT
AGREEMENT ON DEVELOPING CONVECTION ALONG A RESIDUAL LLVL BOUNDARY
THIS AFTN AND WILL ROLL WITH THE CONSENSUS. THIS BOUNDARY IS DEPICTED
ON THE SFC MOISTURE CONVERGENCE AND LLVL WIND FIELD UP TO AT LEAST
H925. LOCATION OF THIS ALONG AND JUST S OF I64 CORRIDOR. ACTUAL
OLD COLD FRONT APPEARS TO HAVE FIZZLED OUT ACROSS N OH AND S
PA...STILL CAN SEE A GOOD DWPT GRADIENT UP THAT WAY THOUGH. WILL
HONE IN ON THE AFOREMENTIONED BOUNDARY FOR DETERMINISTIC
POPS...WITH LKLY AND SOME CAT POPS DEVELOPING. HAVE THINGS POPPING
IN EARNEST BY 18Z NE KY TO COAL FIELDS AND S WV PLATEAU. THIS
SHOULD SLOWLY PUSH TO N AND NE TO ALONG I 64 METRO CORRIDOR AND
INTO MORE OF THE MTNS BY 21Z...IF NOT A LITTLE SOONER. THIS
APPEARS TO GET ITS PUSH FROM APPROACHING UPR LVL WAVE ACROSS TN
VALLEY AMID AN OTHERWISE WEAKENING FLOW. WILL TAKE THIS INTO NORTH
CENTRAL LOWLANDS...SE OH...AND N MTNS BEFORE DISSIPATING ARND
SUNSET. WILL ONLY BE ABLE TO MAKE IT SO FAR NORTH THOUGH AND MAY SEE
ADDITIONAL DEVELOPMENT THAT SLIDES SE INTO SE WV. WILL KEEP PERRY TO
MORGAN AND EXTREME N WV LOWLANDS MAINLY DRY TDY WITH SOME DRIER AIR
PUSHING S THRU MUCH OF THE COLUMN. DECENT SFC HEATING TO EARLY AFTN
WILL AID IN SFC DESTABILIZATION ALLOW CAPE VALUES ARND 1500 J/KG TO
ACT ON IN ADDITION TO BOUNDARY FOCUS AND SOME MID LVL LIFT. PW STILL
ARND 1.5 INCHES S HALF OF CWA. SAW SOME 1 TO 2 INCHES OF STREAKY
RAIN YESTERDAY FROM GREENUP TO PUTNAM...PT PLEASANT TO N KANAWHA AND
S WV PLATEAU. 1 HR FFG HAS COME DOWN TO 1.25 TO 1.5 ACROSS MUCH OF
THE LOWLANDS AND MTNS THAT ARE EXPECTED TO GET HIT TDY. WHILE SOME
TRAINING IS POSSIBLE...THINK SLOW MOVEMENT TO NE WILL HELP TO KEEP
WATER PROBLEMS CONFINED TO ISO AREAS IN HEAVIER CONVECTION. WILL
HAVE TO KEEP A CLOSE EYE ON THOUGH.

PREVIOUS DISCUSSION FOLLOWS...
UNSETTLED WEATHER PATTERN CONTINUES IN THE NEAR TERM PERIOD. FRONTAL
BOUNDARY AT 06Z APPEARS TO BE NORTH OF THE CWA...WITH A DECENT DEW
POINT GRADIENT IN PLACE...WITH DEW POINTS GENERALLY IN THE 40S NORTH
OF THE FRONT...AND IN THE UPPER 50S TO LOWER 60S SOUTH OF THE FRONT.
AT THE SURFACE...HIGH PRESSURE...WITH CALM SURFACE WINDS...AND SOME
PARTIAL CLEARING PARTICULARLY ACROSS THE NORTHERN HALF OF THE
CWA...HAS ALLOWED FOR RATHER WIDESPREAD FOG DEVELOPMENT ACROSS THE
NORTH. THIS FOG SHOULD HANG AROUND UNTIL SHORTLY AFTER
SUNRISE...WHEN IT SHOULD GRADUALLY LIFT.

THE FRONTAL BOUNDARY WILL GRADUALLY SINK SOUTHWARD ACROSS THE CWA
AGAIN TODAY AS HIGH PRESSURE TO THE NORTH PUSHES SOUTH AND EAST.
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ONCE
AGAIN...PARTICULARLY BY AFTERNOON...DUE TO LOW LEVEL CONVERGENCE
ALONG THE FRONTAL BOUNDARY. ANY STORMS THAT ARE ABLE TO DEVELOP ARE
CAPABLE OF HEAVY DOWNPOURS IN THE MOIST...UNSTABLE ATMOSPHERE.
FRONTAL BOUNDARY SHOULD END UP SOMEWHERE ACROSS THE SOUTHERN HALF OF
THE CWA LATER TODAY...AND AS A RESULT...KEPT HIGHEST POPS HERE...AND
LOWER POPS ACROSS THE NORTH WHERE LESS ACTIVITY IS EXPECTED.

FOCUS LATER TONIGHT AND TOMORROW BEGINS TO SHIFT TO AN UPPER
LOW...LOCATED IN THE SOUTHERN STREAM BRANCH OF SPLIT FLOW PATTERN
ACROSS THE EASTERN U.S. APPEARS TO BE SOME TIMING AND TRACK
DIFFERENCES CONCERNING THIS LOW AT THIS POINT...BUT
REGARDLESS...EXPECT THE LOW TO GRADUALLY PUSH EAST TOWARDS THE
REGION LATE TONIGHT...KEEPING THE CHANCE FOR SHOWERS AND STORMS IN
THE FORECAST...WITH GREATER ACTIVITY EXPECTED DURING AFTERNOON
HOURS. KEPT AT LEAST CHANCE OF POPS INTO THE OVERNIGHT
PERIOD...ALTHOUGH DEPENDING ON THE EXACT PATH THE LOW TAKES...COULD
SEE LESS ACTIVITY IN AREAS OVERNIGHT THAN CURRENTLY FORECAST. WITH
THE OVERALL MOIST GROUND/BOUNDARY LAYER IN PLACE...WILL PROBABLY SEE
SOME AREAS OF FOG DEVELOP AGAIN TONIGHT...PARTICULARLY IF ANY AREAS
ARE ABLE TO CLEAR.

HEAVY DOWNPOURS ARE EXPECTED WITH ANY CONVECTION THAT DEVELOPS AGAIN
TODAY. WILL KEEP A MENTION OF POSSIBLE WATER ISSUES IN THE HWO. BULK
OF PRECIPITATION THAT OCCURRED ACROSS THE CWA ON THURSDAY WAS ACROSS
EASTERN KY...AND NORTH OF CRW. AT THIS POINT...EXPECTING BULK OF
CONVECTION TODAY TO OCCUR ACROSS SOUTHERN HALF OF CWA...AND WILL
ALLOW THE DAY SHIFT TO MONITOR FOR ANY POSSIBLE HEADLINES.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
MODELS DIFFER ON PLACEMENT AND TIMING OF LOW PASSING THROUGH THE
REGION BOTH SATURDAY AND SUNDAY AND THE STATIONARY FRONT CURRENTLY
JUST NORTH OF THE AREA.  WARM MOIST AIR WILL CONTINUE TO BE ADVECTED
OVER THE AREA THROUGH SUNDAY FROM THIS LOW.  GENERALLY KEPT CHC POPS
IN THROUGHOUT AND WITH SOME LIFT AND HEATING ON BOTH DAYS MENTIONED
SCT THUNDER AS WELL. POPS DIMINISH FROM WEST TO EAST ON SUNDAY AS
LOW MOVES EAST AND EXITS THE AREA. WENT WITH CONCENSUS GUIDANCE FOR
TEMPERATURES THROUGHOUT AS THERE WILL BE PLENTY OF MOISTURE AND
CLOUDS AROUND.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
EXTENDED PERIOD BEGINS WITH CWA IN NE PORTION OF AN UPPER
RIDGE...HOWEVER A SW TROUGH RESIDES ON ERN PERIPHERY OF THIS RIDGE
AND IS SLOW TO PUSH EAST. THIS SHOULD KEEP OUR AREA IN DISTURBED
WEATHER THROUGH DAY 4...WITH PRIMARILY DIURNALLY DRIVEN SHOWERS AND
THUNDERSTORMS IN THE WV MOUNTAINS. LITTLE BREAK...IF ANY...IN THE
AGITATED WEATHER PATTERN AS NEXT SYSTEM IS QUICK TO MOVE IN FROM
THE WEST TUESDAY. GFS AND ECMWF DIVERGE SOLNS WITH THE HANDLING OF
THE UPPER LEVEL LOW TRACK THROUGH THE GREAT LAKES. RELUCTANT TO GO
ANY HIGHER THAN CHC POPS WITH TIMING DIFFERENCES BETWEEN OPERATIONAL
GUIDANCE. STAYED NEAR WPC GUIDANCE WITH TEMPS THROUGH THE EXTENDED
SAVE FOR LOCAL ADJUSTMENTS.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
WIDESPREAD IFR FOG THIS MORNING WILL GRADUALLY LIFT AFTER 13Z FOR
A BRIEF RETURN TO MVFR/VFR CONDITIONS BEFORE CONVECTION RAMPS BACK
UP AGAIN AFTER 15Z. BULK OF CONVECTION ACTIVITY SHOULD GENERALLY BE
ALONG AND SOUTH OF AN AREA FROM KHTS TO KCRW TO KEKN AND SOUTH. EXPECT
MVFR/IFR CONDITIONS IN VICINITY OF STORMS.

MAJORITY OF CONVECTIVE ACTIVITY WILL DIE DOWN AFTER 00Z...WITH
ANOTHER NIGHT OF WIDESPREAD MVFR/IFR FOG EXPECTED...GENERALLY
AFTER 06Z.

OVERALL LIGHT SURFACE WINDS DURING THE TAF PERIOD.

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


FORECAST CONFIDENCE...LOW TO MEDIUM

ALTERNATE SCENARIOS: MORE CONVECTION MAY DEVELOP ACROSS THE NORTH
THAN CURRENTLY FORECAST. DEVELOPMENT OF FOG AFTER 03Z SATURDAY MAY
BE MORE WIDESPREAD AND WORSE 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.

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    M    M    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  M    M    M    H    H    H    H    H    H    H    H    H
BKW CONSISTENCY  H    H    H    H    M    H    H    M    H    H    H    H
EKN CONSISTENCY  H    M    H    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  M    M    M    M    H    H    H    H    H    H    H    H
CKB CONSISTENCY  H    H    M    M    H    H    H    H    H    H    H    H

AFTER 12Z SATURDAY...
BRIEF/INTERMITTENT IFR POSSIBLE IN HEAVIER SHOWERS/THUNDERSTORMS
THROUGH THE WEEKEND. IFR FOG POSSIBLE IN OVERNIGHT HOURS.

&&

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

&&

$$
SYNOPSIS...JS/SL
NEAR TERM...SL/30
SHORT TERM...JS
LONG TERM...TAX
AVIATION...SL