319 
FXUS61 KRLX 111804
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
204 PM EDT FRI JUN 11 2010

.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE DRIFTS ACROSS THE FORECAST AREA
SATURDAY...LEADING TO SCATTERED THUNDERSTORMS AND LOCAL DOWNPOURS

&&

.NEAR TERM /THROUGH SATURDAY/...
S/W TRACKING ACROSS NRN PORTIONS OF THE FORECAST AREA HAS KICKED
OFF SOME CONVECTIVE SHOWERS. THESE ARE DISSIPATING AS THE REACH
INTO SE OH ZONES. ELSEWHERE...ACROSS WESTERN WV AND EASTERN
KY...NOTED SOME CONVECTIVE ACTIVITY DEVELOPING INVOF OF WARM FRONT
THAT LIES ALONG SUBTROPICAL RIDGE. HIGH PW VALUES LIE JUST TO OUR
SW AND ARE PROGGED TO CREEP INTO FORECAST AREA OVERNIGHT AS WEAK
CLOSE LOW LIFTS NE OUT OF THE OZARK PLATEAU. THIS FEATURE WILL
SERVE AS THE FOCUS FOR CONVECTIVE DEVELOPMENT FOR THE NEXT 24
HOURS ACROSS THE FORECAST AREA. BOTH NMM AND GFS MODELS SHOW
DIFFERENCES IN HANDLING THE PROGRESSION S/W WORKING NORTHEAST
ACROSS SUB-TROPICAL RIDGE...BUT THE GFS HAS SHOWN A LITTLE MORE
RUN TO RUN CONSISTANCY. FOR TIMING PRECIP ONSET USED A BLEND...BUT
LEANED CLOSER TO TIMING OFFERED BY THE GFS.

FOR TEMPS...WITH CLOUDS IN PLACE...KEEP MOST AREAS ABOVE GUIDANCE
VALUES FOR OVERNIGHT MINS. WENT SLIGHTLY BELOW GUIDANCE FOR MAX
TEMPS SATURDAY DUE TO CLOUD COVER AND PRECIP.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
ALL MODELS INDICATING UPPER LOW COMING OUT OF LOWER MISSISSIPPI 
VALLEY...GETTING CAUGHT UP IN THE WESTERLIES AND TRACKING ACROSS THE 
FCST AREA SAT AFTN AND EVNG.  ALL OF THE MODELS ALSO INDICATING 
INTENSE RAINFALL ALTHOUGH ITS HISTORY OF PRODUCING FLOODING SHOULD 
NOT BE DUPLICATED HERE ON ACCOUNT OF ITS FASTER MOVEMENT.

VERY WARM AND MOIST AIR AHEAD OF THIS SYSTEM...ALONG WITH IDEAL 
DIURNAL TIMING SHOULD LEAD TO RATHER STRONG THUNDERSTORMS...A FEW 
GOING SEVERE NOT OUT OF THE QUESTION.  CLOUD SHIELD OUT AHEAD OF 
COMPLEX IN THE MORNING MAY LIMIT HEATING INDUCED INSTABILITY AND 
INDEED MODELS DO NOT O OVERBOARD WITH THIS.  FLOW AND SHEAR DO LOOK 
FAVORABLE INCLUDING SOME TURNING WITH HEIGHT.

WHAT IS RIDICULOUS IS THE FCST PWATS WHICH PEAK AOA 2.25 IN.  WHILE 
THE SYSTEM WILL BE MOVING...DOWNPOURS MAY BE HEAVY ENOUGH FOR FLASH 
FLOODING ON THE SCALE OF AN HOUR OR TWO.  THE SEVERE THREAT WILL 
LIKELY PRECEDE THE WATER THREAT...WITH THE HARD RAIN OCCURRING IN 
THE STABLE COOL POOL.  WILL CONTINUE HIGHLIGHTING SEVERE AND WATER 
THREATS IN HWO.

SYSTEM IS GONE SUNDAY...BUT CONTINUED VERY WARM AND HUMID S TO SW 
LOW LEVEL FLOW AND WNW FLOW WITH EMBEDDED RIPPLES ALOFT SHOULD LEAD 
TO CONVECTION AGAIN SUN AFTN.  GIVEN DECENT FLOW AND 
BUOYANCY...THERE WILL LIKELY BE SOME SEVERE THREAT ONCE AGAIN SUN 
AFTN.

QUESTION FOR SUN NT AND MON IS WHETHER A COLD FRONT MOVES S 
THROUGH THE AREA SUN NT...WITH DRIER CONDITIONS FOR MON...AS 
ALLEGED BY THE NAM12.  OTHER MODELS KEEP FRONT HUNG UP TO THE N.  
BELIEVE FRONT SHOULD MAKE SOME PROGRESS INTO THE AREA AND THEN 
EVENTUALLY BECOME HUNG UP.

EDGED HIGHS BACK A BUT FOR SAT WITH SYSTEM MOVING THROUGH AND LEANED 
HIGHS UP A BIT SUN WITH A BIT MORE SUNSHINE...AND ON MON WITH 
SLIGHTLY LESS AGGRESSIVE COLD FRONT.  ALSO EDGED LOWS UP A BIT IN 
MOST CASES ALONG WITH SOME OF THE DEW POINTS.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
AGREED WITH HPC THAT THERE IS A LARGE AMOUNT OF SPREAD BETWEEN THE 
MODELS...THEREFORE FOLLOWED HPCS REASONING AND FOLLOWED THE ECMWF 
DUE TO THE CONSISTENCY IN ITS MODEL SOLUTIONS. HOWEVER...KEPT POPS 
AT OR BELOW THE CHANCE RANGE TO REFLECT THE UNCERTAINTY BETWEEN THE 
MODELS.

RAIN WILL CONTINUE THROUGH MONDAY EVENING AS THE COLD FRONT SLOWLY 
DRIFTS SOUTHWARD AND STALLS OUT SOUTH OF TENNESSEE...SOME OF THESE 
SHOWERS COULD PRODUCE HEAVY DOWNPOURS ESPECIALLY SINCE PW VALUES 
WILL REMAIN NEAR 2 INCHES.  THE AREA WILL BE DRY THROUGH LATE 
TUESDAY AFTERNOON AS AN UPPER LEVEL RIDGE TAKES HOLD OVER THE 
SOUTHEAST US.  THE NEXT CHANCE OF RAIN ARRIVES LATE TUESDAY 
AFTERNOON AS MOISTURE ASSOCIATED WITH A WEAKENING LOW PRESSURE 
SYSTEM MIGRATES AROUND THE UPPER LEVEL RIDGE AND INTO THE TRI-STATE 
AREA. EXPECTING A SOMEWHAT DIURNAL PATTERN AS FAR AS THUNDERSTORMS 
ARE CONCERNED...BUT AT THIS TIME THE PROBABILITIES OF RAIN AND 
STORMS ARE CHANCE TO SLIGHT CHANCE THROUGHOUT THE REMAINDER OF THE 
EXTENDED FORECAST. 

TEMPERATURES THROUGHOUT THE EXTENDED WILL BE RELATIVE STEADY WITH 
HIGHS IN THE LOW TO MID 80S AND LOWS AROUND 60...WITH LOWER 
TEMPERATURES EXPECTED IN THE HIGHER TERRAIN.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...

GENERAL VFR CONDITIONS FOR MOST AREAS THIS AFTERNOON...EXCEPTION
BEING ALONG THE OH RVR VALLEY WHERE SOME CONVECTIVE ACTIVITY
DEVELOPING. ACTIVITY SHOULD SUBSIDE AFTER SUNSET WITH VALLEY FOG
EXPECTED BY MORNING. REMNANTS OF AR CONVECTIVE COMPLEX PROGGED TO
MOVE ACROSS SE OH AND NRN WV TO START THE DAY SAT. THIS FEATURE
WILL PRODUCE AREAS OF MVFR AND LOCL IFR CONDITIONS SPREADING WEST
TO EAST.

AFTER 18Z SATURDAY... 
IFR POSSIBLE IN THUNDERSTORMS INTO SATURDAY NIGHT...FOLLOWED BY
LOW CLOUDS AND FOG INTO EARLY SUNDAY MORNING ESPECIALLY FOR AREAS
THAT RECEIVE RAIN.

&&

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

&&

$$