248 FXUS61 KRLX 192226 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 626 PM EDT THU APR 19 2012 .SYNOPSIS... HIGH PRESSURE LINGERS THROUGH MUCH OF FRIDAY. A COLD FRONT MOVES THROUGH FRIDAY NIGHT AND SATURDAY...WITH SHOWERS AND THUNDERSTORMS. COOLER WEATHER FOLLOWS FOR THE REST OF THE WEEKEND INTO NEXT WEEK. && .NEAR TERM /THROUGH FRIDAY/... 630 PM UPDATE...ONLY CHANGE MADE TO THE PREVIOUS FORECAST WAS TO DECREASE CLOUD COVER ACROSS THE CWA IN THE FIRST FEW HOURS BASED ON CURRENT SATELLITE OBSERVATIONS. ALTHOUGH WE WILL SEE BRIEF CLEARING EARLY TONIGHT...CLOUDS WILL BE ON THE INCREASE LATE FROM THE NORTH AND WEST IN ADVANCE OF AN APPROACHING COLD FRONT. PREVIOUS DISCUSSION FOLLOWS... HIGH PRESSURE SLIDES EAST LATER TONIGHT. BY MORNING ENOUGH OF A PRESSURE GRADIENT DEVELOPS ON THE BACK SIDE OF THE HIGH TO AT LEAST PROVIDE SOME ATMOSPHERIC AGITATION TO PREVENT FOG FORMATION. THE EXCEPTION FOR FOG FORMATION MAY BE IN THE PROTECTED NORTHERN MOUNTAIN VALLEYS FOR A BRIEF PERIOD LATE TONIGHT. SO ALL IN ALL...LOOKS LIKE A CLEAR AND TRANQUIL NIGHT.IN TURN..GOING ON LOWER SIDE OF TEMP GUIDANCE...CLOSE TO MAV NUMBERS. FOR FRIDAY...MODELS KEEP THE EFFECTS OF AN APPROACHING COLD FRONT MOSTLY WEST OF OUR AREA. HOWEVER...SINCE THE MODEL TREND HAS BEEN FASTER WITH THE SYSTEM...WILL INTRODUCE LOW CHANCE POPS INTO SOUTHEAST OHIO...BUT KEEP ANY PRECIP WEST OF THE OHIO RIVER. ENOUGH INSTABILITY WITH SUNSHINE AHEAD OF THE FRONT TO INCLUDE THUNDER. MODELS DO TRY TO PUT SCATTERED LOW QPF IN THE SOUTHERLY FLOW WELL AHEAD OF THE FRONT OVER OUR AREA DURING FRIDAY. THINK THIS IS DUE TO SOME WEAK LOW LEVEL CONVERGENCE WELL AHEAD OF THE FRONT. HOWEVER...GIVEN LACK OF DEEPER MOISTURE THIS FAR AHEAD OF THE FRONT...QUITE WEAK CONVERGING FLOW...AND LITTLE TO NO UPPER SUPPORT...WILL NOT BUY INTO THIS QPF SO FAR AHEAD OF THE FRONT. SO NO MEASURABLE POPS EAST OF THE OHIO RIVER FRIDAY. WILL INCREASE DIURNAL CLOUD COVER A BIT IN THIS WEAK CONVERGING SOUTHERLY FLOW...BUT STILL HAVE PLENTY OF SUNSHINE TO LIFT MAX TEMPS TO THE HIGHER MAV GUIDANCE. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... THE MAIN WEATHER MAKER FOR THE SHORT TERM WILL BE A COLD FRONT PUSHING THROUGH LATE FRIDAY NIGHT AND SATURDAY...BRING SHOWERS AND THUNDERSTORMS ALONG WITH COOLER TEMPERATURES. MODELS HAVE CONTINUED TO SPEED UP THE PROGRESS OF THE COLD FRONT MOVING THROUGH...AND THEN DRY THINGS OUT FAIRLY QUICKLY BEHIND THE FRONT. NAM/GFS/ECMWF ALL AGREE ON CLOSING OF A 500MB LOW IN THE NORTHERN GULF OF MEXICO...BUT KEEP IT QUITE PROGRESSIVE...WHICH SUPPORTS THE COLD FRONT NOT HANGING AROUND TOO LONG. THINKING THE HIGHEST POPS WILL BE BEHIND THE SURFACE FRONT...MORE IN LINE WITH THE FRONT AT 850MB....MOVING THROUGH THE LOWLANDS SATURDAY MORNING...AND THROUGH THE MOUNTAINS DURING THE AFTERNOON. PRECIP WILL GRADUALLY END FROM WEST TO EAST SATURDAY AFTERNOON/EVENING ACROSS THE LOWLANDS...THEN LINGERING SLIGHT CHANCE POPS IN THE MOUNTAINS SATURDAY NIGHT. AS FOR TEMPS...DECENT SPREAD IN MODELS FOR FRIDAY NIGHT LOWS. DID NOT MAKE ANY SIGNIFICANT CHANGES...ALTHOUGH DID COOL THE LOWS IN SE OHIO A BIT. WITH COLD FRONT BISECTING THE CWA ON SATURDAY...WENT WITH COOLER MET ALONG THE OHIO RIVER...BUT STAYED CLOSER TO THE WARMER MAV ACROSS THE MOUNTAINS...WITH A TRANSITION ZONE IN BETWEEN. ALSO COOLED LOWS A BIT FOR SATURDAY NIGHT...WITH MAV AND MET IN GOOD AGREEMENT. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MODELS IN BETTER...THOUGH NOT TOTAL...AGREEMENT ON E COAST LONG WAVE TROF NEXT WEEK. THE SIGNIFICANT STRATIFORM PRECIPITATION ASSOCIATED WITH THE SURFACE LOW TRACKING UP THE E COAST WILL OCCUR E OF THE AREA. HOWEVER...DEPENDING UPON HOW LONG THE UPPER LEVEL LOW HANGS AROUND...AND SMALLER UNTIMABLE DISTURBANCES ROTATING AROUND IT...A LITTLE BIT OF PRECIPITATION IS POSSIBLE IN AND NEAR THE MOUNTAINS MON INTO MIDWEEK...AFTER A RELATIVELY DRY INTERLUDE SUN NT. DILEMMA LATER IN THE WEEK IS HOW FAST THE UPPER LEVEL SYSTEM SHIFTS E...AND...CONSEQUENTLY...WHEN A WARM FRONT ARRIVES FROM THE W. WENT CLOSER TO THE FASTER GFS VS SLOWER ECMWF...WITH A WARM FRONT FROM THE W WED NT FOLLOWED BY A COLD FROM THE N LATE THU. BLENDED IN SOME MEX / HPC ON HIGHS MOST PF THE PERIOD AND LOWS SUN NT. PREVIOUS LOWS LOOKED GOOD FOR THE MOST PART FOR MON NT ON...USED BCCONSRAW FOR DAY 7 NT. HIGHS ARE HIGHER EARLY ON ON ACCOUNT OF FARTHER E SOLN W/R LONG WAVE TROF...AND TEMPERATURES ARE NOT FAR FROM HPC GUIDANCE. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... 18Z THURSDAY THRU 18Z FRIDAY... HIGH PRESSURE AND VFR MOSTLY CLEAR WILL DOMINATE THRU THE PERIOD. MINOR EXCEPTIONS MAY BE BRIEF LIFR IN THE MOST PROTECTED MOUNTAIN VALLEYS BETWEEN 08Z AND 12Z FRIDAY...INCLUDING EKN...AND VFR CEILINGS AROUND 4000 FEET ON EAST FACING SLOPES OF SOUTHERN AND CENTRAL WEST VIRGINIA MOUNTAINS 06Z TO 14Z FRIDAY DUE TO WEAK UPSLOPE FLOW. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY... FORECAST CONFIDENCE...HIGH. ALTERNATE SCENARIOS: NONE...OTHER THAN MENTIONED ABOVE. 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 20 21 22 23 00 01 02 03 04 05 06 07 EDT 1HRLY 16 17 18 19 20 21 22 23 00 01 02 03 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY L M H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H M M PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 00Z SATURDAY... IFR CONDITIONS POSSIBLE FRIDAY NIGHT AND SATURDAY AS CLOUDS AND PRECIPITATION ARE EXPECTED. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/JMV/MZ NEAR TERM...JMV/SL SHORT TERM...MZ LONG TERM...TRM AVIATION...JMV