000
FXUS61 KRLX 180008
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
809 PM EDT SAT MAY 17 2008
.SYNOPSIS...
A COLD FRONT DROPS INTO AREA OVERNIGHT. LOW PRESSURE MOVES ALONG
THE FRONT SUNDAY MORNING...AND KICKS IT EAST SUNDAY AFTERNOON WITH A
COOLER AIRMASS BEHIND IT. ANOTHER FRONTAL SYSTEM IS EXPECTED MONDAY
NIGHT AND TUESDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
FRONTAL BOUNDARY NOW SITUATED ACROSS NORTHERN OH/IN...MOVING SLOWLY
SOUTHEAST. ACTIVITY ALONG BOUNDARY IS CURRENTLY NOT TOO
WIDESPREAD...LOW DEWPOINT AIR AHEAD OF BOUNDARY IS LIKELY PLAYING A
ROLE. MIDLEVEL SUPPORT IS LACKING AS WELL. HAVE BACKED OFF ON POPS
THIS EVENING...OPTING FOR HIGH CHANCE INSTEAD OF LOW LIKELY VALUES.
THUNDER POTENTIAL APPEARS MINIMAL AS WELL...BUT KEPT IN ISOLATED
CHANCES. FRONT BECOMES PARALLEL TO UPPER FLOW AND HANGS UP FOR A
SHORT WHILE IN OR NEAR OUR NORTHERN COUNTIES. PRECIP COVERAGE ALONG
FRONT WILL DECREASE FURTHER AS DAYTIME HEATING IS LOST.
MODELS ALL DEVELOP A WEAK WAVE ALONG BOUNDARY LATE TONIGHT AND SLIDE
IT INTO OUR NORTHWESTERN COUNTIES BY 12Z. H500 TROUGH AROUND
SOUTHERN CANADA UPPER LOW WILL BE DIGGING IN AS WELL. THESE WILL
WORK WITH BOUNDARY IN PLACE TO CREATE A BLOOM OF PRECIPITATION LATE
TONIGHT AND TOMORROW MORNING. HIGH LIKELY/LOW CATEGORICAL POPS
STILL LOOK APPROPRIATE FOR THIS SCENARIO. FRONT WILL BE SHUNTED
EAST BY 18Z. UPPER COLD POOL MOVES IN BEHIND THE FRONT...WITH H500
TEMPS OF AROUND -25C BUILDING IN. OPEN CELLULAR SHOWERS SHOULD FORM
DURING THE AFTERNOON HOURS...MAINTAIN CHANCE POPS FOR THESE.
SUFFICIENT INSTABILITY FOR ISOLATED THUNDER AS WELL.
GENERALLY TOOK A MAV/MET BLEND FOR TEMPERATURES THROUGH THE PERIOD.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
LOW LEVEL MOISTURE WILL BE SLOW TO DEPART BEHIND FRONT SUNDAY NIGHT.
TOOK POPS OUT OF MOUNTAINS BY 06Z MONDAY AS WEAK HIGH PRESSURE
BEGINS TO BUILD IN FROM SW. KEPT SOME CLOUDS IN FOR MONDAY AS LOW
LEVEL MOISTURE LINGERS UNDER NW FLOW. UPPER LEVEL LOW WILL SHIFT
EASTWARD ON MONDAY TO A POSITION OVER QUEBEC. ANOTHER PIECE OF
VORTICITY AND WEAK SFC LOW WILL ROTATE AROUND THE UPPER LOW EARLY
TUESDAY MORNING. NAM12...GFS...AND SREF SEEM TO HAVE SHIFTED TRACK
SOUTHWARD THROUGH SOUTHERN KY TO VA/NC LINE. NOT READY TO TOTALLY
BUY THIS SOLUTION AS THESE FEATURES TEND TO HAVE A NORTHWARD
CORRECTION WITH TIME. HOWEVER...DID FOCUS HIGH CHC POPS IN SOUTHERN
COAL FIELDS/SW VA TUESDAY...TAILING OFF TO SCHC POPS IN NORTH.
MODELS ALSO DEPICT A LOW PRESSURE/ASSOCIATED VORT MAX DEVELOPING
JUST NORTH OF CWA BEHIND INITIAL LOW...BRINGING QPF BACK IN MIDDAY
TUESDAY AFTER SHORT LULL. KEPT CLOSE TO HPC GUIDANCE/MOSGUIDE FOR
TEMPS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
BASICALLY FOLLOWED HPC FOR END OF WEEK WITH ONE LAST PIECE OF
VORTICITY ROTATING THROUGH THURSDAY INTO FRIDAY...AS UPPER LEVEL
TROUGH FINALLY SHIFTS EASTWARD.
MODELS INDICATING A PATTERN CHANGE FOR THE WEEKEND...WITH ECMWF
/AND TO A LESSER EXTENT GFS/ CARVING OUT A DEEP TROUGH IN THE WEST
AND JUST OFF THE ATLANTIC COAST...WITH STRONG RIDGE FOR MISSISSIPPI
VALLEY. THIS WOULD MEAN ABOVE NORMAL TEMPS OVER CWA FOR END OF
WEEKEND/FOLLOWING WEEK.
GENERALLY WENT WITH MOSGUIDE FOR MAXT. DID ADJUST MINS UP A FEW
DEGREES FOR MIDWEEK...WITH LOW LEVEL MOISTURE AND CLOUDS PREVALENT.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
TWO BROKEN LINES OF SHOWERS...ALONG WITH A FEW THUNDERSTORMS WITHIN
THESE LINES...WILL MOVE QUICKLY THROUGH THE AREA DURING THE FIRST
6-8 HOURS OF THE FORECAST. THE FIRST LINE EXTENDED FROM CKB TO HTS
WHILE THE SECOND WAS RIGHT BEHIND THE FIRST...JUST W OF THE OHIO
RIVER. THE FIRST LINE WILL MAKE IT TO EKN BY 03Z AND THEN PROBABLY
ALL BUT DISSIPATE BY THE TIME IT GETS TO BKW 4-5Z. THE SECOND LINE
WILL AFFECT MAINLY NORTHERN SITES ABOUT 2-3 HOURS AFTER THE FIRST.
SHOWERS WITHIN THE LINE WILL BRING MVFR CONDITIONS...BUT IF A SITE
GETS RIGHT UNDER A THUNDERSTORM...IFR CONDITIONS ARE MORE LIKELY.
AFTER A BRIEF PERIOD OF MVFR MIST FOLLOWING RAIN AT A PARTICULAR
SITE...THE BALANCE OF THE NIGHT WILL BRING PREDOMINANTLY VFR
CONDITIONS.
A NEW LOW PRESSURE SYSTEM WILL BRING RAIN WITH MVFR TO IFR
CONDITIONS FIRST THING SUN MORNING. CONDITIONS WILL START TO
IMPROVE PKB BY AFTERNOON AND W TO E ACROSS THE REMAINDER OF THE AREA
DURING THE EARLY AND MID AFTERNOON HOURS.
GUSTY W TO SW WINDS WILL CONTINUE THROUGH MOST OF THE PERIOD EXCEPT
BECOMING LIGHT DURING THE OVERNIGHT TONIGHT.
AVIATION OUTLOOK /AFTER 00Z MONDAY/...NO WIDESPREAD IFR EXPECTED.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...CL/30
NEAR TERM...CL
SHORT TERM...30
LONG TERM...30
AVIATION...TRM
