000 FXUS61 KRLX 161103 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 556 AM EST WED JAN 16 2008 .SYNOPSIS... HIGH PRESSURE LINGERS TODAY. A SYSTEM WILL BRING MIXED PRECIPITATION THURSDAY...BUT HEAVIEST REMAINS TO OUR EAST. AN ARCTIC COLD FRONT PASSES SATURDAY AFTERNOON. AS A RESULT...MUCH COLDER ON SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... I WOKE UP TUESDAY AFTERNOON TO A CLOUDLESS SKY AT CRW...BUT THE SOUTHERN EDGE OF THE OVERCAST LINGERED UNTIL THIS PREDAWN FOR PKB AND SUTTON. FIGURING LINGERING STRATOCUMULUS CLEARING PKB AROUND 4 TO 5 AM...THEN REACHING I-79 CORRIDOR AROUND WESTON AND CLARKSBURG AROUND DAWN/12-13Z WITH EKN AROUND THAT TIME TOO. LOWERED MAXIMUM TEMPERATURES A BIT. WAS WORRIED ABOUT LIGHT WINDS AND INCREASING HIGH CLOUDS DIMMING/FADING THE SUNSHINE THIS AFTERNOON...ESPECIALLY FOR OUR SOUTHERN COUNTIES . HAVE TEMPERATURES TONIGHT DROPPING THIS EVENING...THEN STEADY OR RISING DURING THE PREDAWN HOURS. STRONG OVERRUNNING IN THE 850 TO 700 MB LAYER PUSHING QUICKLY NORTH TONIGHT...OUT AHEAD OF THE 500 MB VORT MAXIMUM. A LOT OF THE LIFT/WORK WILL GO INTO SATURATING A VERY DRY COLUMN BELOW 12 THSD FT THIS EVENING. TIMING ON PCPN REACHING THE GROUND IS...AS USUAL...TOUGH. BROUGHT LIKELY POPS INTO SW VA AFTER 06Z THURSDAY THEN REACHING BKW BEFORE DAWN THURSDAY. THE ISSUE WITH THIS EVENT IS THE QPF...SINCE THE DURATION OF THE MAIN EVENT IS ONLY 6 TO 8 HOURS...BEFORE MID LEVEL MOISTURE EXITS...BUT THATS OUT OF THIS TIME FRAME. CONCERNED THAT THE PCPN MAY NOT BE HEAVY ENOUGH THIS FAR W/NW...SO NO WATCH ISSUED ON THE MIDNIGHT SHIFT FOR OUR SRN MTNS...THINKING MORE TOWARD ADVISORIES...BUT WOULD NOT RULE OUT A WATCH/WARNING EVENT JUST YET. HPC THOUGHT AND WE AGREED THAT THE 00Z MODEL QPF(S) MAY BE A BIT HEAVY INTO SRN WV. HAVE SOME 1 TO 3 INCHES OF SNOW POSSIBLE IN OUR SRN COUNTIES LATE TONIGHT BEFORE TRANSITION TO MIXTURE. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... THE SQUEEZE PLAY IS ON FOR THURSDAY...WITH CWA BETWEEN LOW MOVING UP THE CAROLINA COAST...AND SLOW-MOVING COLD FRONT TO THE WEST ASSOCIATED WITH A GREAT LAKES SHORTWAVE. UPSLOPE FLOW ALONG THE EAST-FACING SLOPES ALLOWS SOME MODEST COLD AIR DAMMING IN THE LOW LEVELS...WHILE TEMPERATURES IN THE 850/925 LAYER RISE ABOVE 0C. THE RESULT IS A MIX CHANGING OVER TO RAIN BY 18Z WEST OF THE MOUNTAINS...AND A CHANGEOVER TO MAINLY FREEZING RAIN BY MIDDAY ALONG SAID EASTERN SLOPES. USED NAM H850 TEMPERATURES IN WEATHER TOOL TO DERIVE GRIDS...SINCE NAM USUALLY HANDLES THESE DAMMING EVENTS BETTER THAN THE GFS DUE TO ITS SUPERIOR HANDLE ON TERRAIN. USED A MAV/MET MIX FOR SURFACE TEMPERATURES. AS NOTED IN PREVIOUS SECTION...MAIN LIMITING FACTOR WITH THIS EVENT IS QPF. WITH BEST LIFT GENERALLY SOUTH AND EAST OF CWA CLOSER TO THE COASTAL LOW...DO NOT FEEL THAT WE WILL GET ENOUGH LIQUID EQUIVALENT TO REACH WATCH/WARNING ICE ACCRETION CRITERIA ALONG THE EASTERN SLOPES. LOOKS MORE LIKE AN ADVISORY-TYPE EVENT...WHICH WOULD LIKELY BE ISSUED BY THE DAY SHIFT. COULD EVEN SEE AN INCH OR TWO OF SNOW BEFORE THE CHANGEOVER. AS WE HEAD INTO THURSDAY NIGHT...PRECIPITATION BECOMES SPOTTIER AS COASTAL LOW PULLS AWAY. COLD FRONT WILL PASS THROUGH OVERNIGHT...BUT DEEP MOISTURE WILL BE GONE...AND COLD ADVECTION BEHIND FRONT IS RATHER WEAK. THUS...EXPECTING LEFTOVER RAIN/FREEZING RAIN TO TRANSITION TO SNOW SLOWLY OVERNIGHT...WITH ALL SNOW EXPECTED BY 12Z. AFTER LINGERING SNOW SHOWERS FRIDAY MORNING...CWA IS IN LULL BETWEEN FRONTAL BOUNDARIES...AND WE SHOULD SEE AT LEAST PARTLY CLOUDY SKIES. ARCTIC BOUNDARY APPROACHES FRIDAY NIGHT...WITH AN INCREASE IN SNOW SHOWER ACTIVITY AHEAD OF IT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... USED MOSGUIDE GRIDS FOR THIS PERIOD...WHICH KEPT THE PREVIOUS THINKING MOSTLY INTACT. TEMPERATURES LOOKED FINE...ALTHOUGH DID RAISE MONDAY/TUESDAY VALUES TO KEEP IN LINE WITH A MILDER SCENARIO FOR SYSTEM EARLY NEXT WEEK. VERY COLD AIRMASS MOVES IN SATURDAY WITH SCATTERED SNOW SHOWERS...GFS STILL BRINGING IN SUB -20C AIRMASS AT H850. WIND CHILLS MAY YET BE AN ISSUE SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE BUILDS IN FOR A QUIET BUT COLD SUNDAY...AND PRECIPITATION CHANCES RETURN MONDAY INTO TUESDAY WITH A MIDWESTERN LOW. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... STILL TIMING THE LEFTOVER STRATOCUMULUS WITH CEILINGS 25 TO 45 HND TO CLEAR CKB TO EKN BETWEEN 12 AND 14Z. OTHERWISE VFR...THROUGH 06Z. RAPID DETERIORATION IN CEILING AND VSBY WITH SNOW DEVELOPING FM S BKW-CRW VCNTY 08-11Z. CEILING LOWERING TO NEAR 1 THSD FT BKN/OVC AND VSBY AOB 3 MILES. HEAVIEST PCPN FIGURED TO STAY MOSTLY E OF CRW-BKW. BEYOND 12Z THURSDAY...IFR POSSIBLE THURSDAY...MAINLY AND MOST PERSISTENT ALONG EASTERN SLOPES INCLUDING BKW...IN SNOW AND FREEZING RAIN. PCPN SHOULD DECREASE THURSDAY AFTERNOON. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB NEAR TERM...CL SHORT TERM...TRM LONG TERM...JMV AVIATION...KTB