377
FXUS61 KRLX 090149
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
949 PM EDT TUE JUL 8 2008
SYNOPSIS
A COLD FRONT MOVES THROUGH WEDNESDAY AND WEDNESDAY NIGHT. DRIER
AIR MOVES IN FOR THURSDAY. ANOTHER COLD FRONT MOVES IN FOR THE
WEEKEND.
NEAR TERM /THROUGH WEDNESDAY/
LINE OF WEAKENING CONVECTION WILL CONTINUE TO SLIDE THROUGH OH
PORTION OF CWA. LINE IS MOVING INTO A MORE STABLE AIRMASS SO THE
THE LINE HAS BEEN SLOWING...AND THE HI WIND THREAT IS NOW
DIMINISHING. PAINTED POPS ACROSS THE NORTHERN PORTION OF THE CWA
AND LESSENED VALUES ACROSS THE SOUTHERN PORTION FOR THE OVERNIGHT
HOURS.
MAIN FRONTAL BOUNDARY WELL TO THE WEST AND PROGGED TO SLIDE
THROUGH DURING THE DAY ON WEDNESDAY. WAVE RIDING ALONG BAROCLINIC
ZONE WAS WELL EVIDENT OVER IL AND IND. NAM CARRIES THIS FEATURE TO
THE NORTH OF THE CWA...BUT RADAR TRENDS AND IR SAT IMAGERY
SUGGEST A MORE SOUTHERLY TRACK. THIS FEATURE SHOULD MAKE IT TO
OH-WV LINE BEFORE SUNRISE BASED ON CURRENT TRENDS. BY THEN...
FEATURE WILL HAVE LOST MUCH OF ITS CONVECTIVE NATURE...AND MAINLY
STRATIFORM PRECIP IS EXPECTED.
FRONTAL PASSAGE EXPECTED DURING THE DAY WEDNESDAY TRIGGERING
ANOTHER ROUND OF CONVECTION. THIS COVERED WELL IN CURRENT PACKAGE
SO NO CHANGES MADE.
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/
500HPA WILL CONTINUE TO FLATTEN OUT AND BECOME MORE ZONAL...LENDING
THE POSSIBILITY THAT DIURNAL THUNDERSTORMS WILL BE THE NORM IN THE
SHORT TERM FORECAST PERIOD. HOWEVER...NAM IS SUGGESTING THE DEPTH OF
THE MOISTURE WILL NOT BE THERE IN SUPPORT OF CONVECTION COURTESY OF
HIGH PRESSURE AT THE SURFACE. THE EXTREME SOUTHERN ZONES MAY END UP
BEING THE EXCEPTION IN THIS CASE...WHERE MOISTURE APPEARS DEEP
ENOUGH TO AT LEAST WARRANT SLIGHT CHANCE POPS GIVEN THE SERIES OF
VORTICITY MAXIMA TRAVERSING THE KENTUCKY/TENNESSEE BORDER AND INTO
THE SOUTH CENTRAL APPALACHIANS. GENERALLY BLENDED GUIDANCE VALUES
FOR THE MAX AND MIN T VALUES.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
HIGH PRESSURE WILL DEPART TO THE EAST HEADING INTO THE
WEEKEND...GIVING WAY TO A COLD FRONT APPROACHING FROM THE WEST.
INSTABILITY AND MOISTURE DEPTH WILL INCREASE OUT AHEAD OF THIS
SYSTEM...WITH DIURNAL STORMS POSSIBLE SATURDAY. WILL SEE THE COLD
FRONT PASS THROUGH MOST LIKELY SATURDAY NIGHT OR SUNDAY...WITH HIGH
PRESSURE IN ITS WAKE. WILL ASSESS ANY SEVERE THREATS AS THE FORECAST
TIME APPROACHES.
500HPA HEIGHTS ARE SUGGESTING A RELIEF FROM THE HEAT AND HUMIDITY
UPON FRONTAL PASSAGE WITH THE INFILTRATION OF A CONTINENTAL AIR MASS
ORIGINATING IN THE PRAIRIE PROVINCES OF CANADA.
AVIATION /02Z WEDNESDAY THROUGH SUNDAY/
ONE LINE OF CONVECTION HAS COMPLETED ITS JOURNEY ACROSS THE
FORECAST AREA...WITH ANOTHER ONE NOW ENTERING WESTERN PORTIONS.
PAINTED MVFR FOR SITES IN THE OVERNIGHT HOURS AS LOTS OF LOW LEVEL
MOISTURE IN PLACE AHEAD OF APPROACHING COLD FRONT. ALSO ADDED
TEMPO FOR NEXT BATCH OF CONVECTION TRYING TO TIME IT ACROSS. WE
SUSPECT IT WILL LOSS ITS PUNCH ONCE IT REACHES OUR EASTERN MOUNTAINS.
IFR FOG TONIGHT SHOULD BE MINIMAL...HOWEVER LOW LEVEL RH IS QUITE
HIGH...THUS BROUGHT VSBYS DOWN TO MVFR RANGE IN HZ AND BR.
FROPA EXPECTED DURING THE AFT ON WEDNESDAY...AND THIS WILL LEAD TO
A GOOD CHANCE FROM WIDESPREAD CONVECTIVE DEVELOPMENT AFTER 17Z.
AVIATION OUTLOOK /AFTER 00Z THU/...IFR POSSIBLE IN WIDESPREAD
THUNDERSTORMS INTO WED EVENING AND FOG EARLY THU MORNING.
RLX WATCHES/WARNINGS/ADVISORIES
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
SYNOPSIS...26/TRM/KMC
NEAR TERM...KMC
SHORT TERM...26
LONG TERM...26
AVIATION...KMC
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