Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 101952 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 252 PM EST WED FEB 10 2016 .SYNOPSIS... A FEW COMPACT DISTURBANCES WILL SLIDE SOUTHEAST OVER THE NEXT SEVERAL DAYS THROUGH A DEEP UPPER TROUGH OVER THE NORTHEASTERN U.S.. A PERSISTENT NORTHWEST FLOW WILL BRING IN THE COLDEST AIR OF THE SEASON...WHILE ALSO CREATING A PROLONGED PERIOD OF LAKE EFFECT AND UPSLOPE SNOW SHOWERS THROUGHOUT THE NORTHWEST PENN SNOW BELT...AND ACROSS THE LAUREL HIGHLANDS. && .NEAR TERM /THROUGH TONIGHT/... MOSTLY CLOUDY SKIES AND BLUSTERY CONDITIONS WITH FLURRIES AND A FEW BRIEF SNOW SHOWERS WILL BE FOUND ACROSS MUCH OF THE CENTRAL RIDGE AND VALLEY REGION LATE THIS AFTERNOON INTO THIS EVENING WITH WEAK LLVL RIDGING IN PLACE. PERSISTENT UPSLOPE SNOW SHOWERS AND FREQUENT LES FROM MEANDERING SNOW BANDS ACROSS THE FAR NW ZONES WILL BRING AN ADDITIONAL 1 TO 2 INCHES EVERY 4 TO 6 HOURS THROUGH TONIGHT...THOUGH PORTIONS OF NW WARREN COUNTY COULD SEE NEARLY DOUBLE THOSE SNOWFALL RATES. 18Z HRRR HAS BEEN FAIRLY CONSISTENT WITH ITS PAST SEVERAL RUNS IN DISPLAYING SIMILAR TIMING OF A NARROW NE-SW ORIENTED BAND OF BRIEFLY HEAVY SNOW SHOWERS AND POSSIBLE SQUALLS...THAT WILL ACCOMPANY A SECONDARY CFRONT ACROSS THE NW MTNS LATE TODAY BEFORE REACHING A KELM TO KFIG LINE AROUND 00Z THURSDAY. ONCE THIS SNOW BAND SLIDES OFF THE HIGHER TERRAIN OF THE ALLEGHENY PLATEAU LATER THIS EVENING...AND LLVL INSTABILITY WANES A BIT...THE HRRR IS PROBABLY ON TRACK WITH WEAKENING IT BY 02Z NEAR A KAVP...TO KSEG AND KUNV LINE. THE WELL-ALIGNED SFC-800 MB FLOW FROM ABOUT 270 DEGREES...WILL VEER TO ABOUT 295 DEG LATE TODAY/EARLY TONIGHT AS THE AFOREMENTIONED SECONDARY COLD FRONT SWINGS SE THROUGH THE AREA. THE FRONT COULD BRING A QUICK 1/2 INCH ALONG AND EAST OF THE INTERSTATE 99/RT 22 CORRIDOR...WITH UP TO ONE INCH ON THE HIGH TERRAIN TO THE NORTH AND WEST. BASED ON THE MODERATELY STRONG...WELL ALIGNED...AND PERSISTENT 280-290 DEG FLOW LATE TODAY THROUGH ABOUT 04Z FRIDAY...WE EXTENDED THE WINTER WX AND LES ADVISORIES AND WARNINGS OUT IN TIME THROUGH 03Z FRIDAY...AND EXPANDED THE WINT WX ADVIS NORTH TO COVER ELK AND CLEARFIELD COUNTIES. LATER TONIGHT...LOOK FOR VARIABLE AMOUNTS OF CLOUDS WITH SCATTERED FLURRIES ACROSS THE SUSQ VALLEY AND SOUTHERN TIER...WHILE A FEW BRIEF SNOW SHOWERS IN NARROW NW-SE STREAMERS OFF LAKE ERIE COULD ADD AN ADDITIONAL LIGHT COATING FROM KAOO TO KUNV. TEMPS ARE RIGHT AROUND THEIR FCST MAXES OF AROUND 20F ACROSS THE LAUREL HIGHLANDS...AND IN THE U20S TO LOWER 30S HEADING FROM THE CENTRAL MTNS TO THE MIDDLE AND LOWER SUSQ VALLEY. LOWS TONIGHT WILL VARY FROM 5-10F ACROSS THE NORTHERN AND WESTERN MTNS...TO THE UPPER TEENS IN THE SUSQ VALLEY. WIND CHILLS COULD DIP TO NEAR -10F AT TIMES LATE TONIGHT ACROSS THE NRN AND WRN MTNS...AND IN THE ZERO TO 10 ABOVE RANGE ACROSS THE CENTRAL AND SE ZONES...BUT WILL BE A GOOD 5 TO 10 DEG F ABOVE WIND CHILL ADVISORY CRITERIA IN ANY OF THESE LOCATIONS. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... PERSISTENT...MEAN BYLR FLOW FROM 280-290 DEGREES WILL LEAD TO WIDESPREAD STRATO CU WITH CLOUD TEMPS ACROSS MUCH OF CENTRAL PENN FALLING WITHIN THE FAVORABLE DGZ OF -12 TO -18C. THIS WILL LEAD TO WIDESPREAD FLURRIES AND BRIEF SNOW SHOWERS FROM NARROW...AND SLOWLY MEANDERING BANDS. MESOSCALE MODELS SUCH AS THE HRRR AND 3 KM NCAR EMSEMBLE WILL PLAY AN IMPORTANT ROLE IN FORECASTING THE LOCATION...MVMT...AND SNOW FROM THESE FAIRLY WELL- ORGANIZED BUT NARROW SNOW BANDS THAT WILL REACH INTO THE CENTRAL RIDGE AND VALLEY REGION AT TIMES. ADDITIONAL SNOW ACCUMS OF A FEW TO SEVERAL INCHES WILL OCCUR DURING THE DAYLIGHT HOURS THURSDAY ACROSS THE NW MTNS AND LAUREL HIGHLANDS WHERE THE WINT WX AND LES ADVISORIES...AND LES WARNINGS WILL CONTINUE. MAX TEMPS THURSDAY WILL BE ONLY 12-25F WHICH IS AROUND 15 DEG F BELOW NORMAL FOR THIS TIME OF YEAR. THE BULK OF THE MORE SIGNIFICANT SNOW SHOWERS/LES SHOULD TAPER OFF/LIFT TO THE NORTH...CLOSELY HUGGING THE I-90 CORRIDOR AS MEAN BLYR WINDS BACK MORE TO THE WSW AFTER MIDNIGHT. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... *IMPACT WEATHER HIGHLIGHTS: SNOW SQUALLS POSSIBLE WITH ARCTIC FRONT FRIDAY NIGHT-EARLY SATURDAY. FRIGID TEMPERATURES/DANGEROUS WIND CHILLS FOR VALENTINES WEEKEND. POLAR VORTEX DIVES FROM HUDSON BAY SOUTHEAST ACROSS QUEBEC AND NORTHERN NEW ENGLAND THURSDAY-SUNDAY. THE GLOBAL MODELS AND ENSEMBLE MEANS KEEP A `MILDER` TROUGH PATTERN IN PLACE OVER THE NORTHEAST CONUS INTO NEXT WEEK. THE FIRST SHOT OF COLD AIR ARRIVES ON THURSDAY WITH LAKE EFFECT AND UPSLOPE SNOW SHOWERS TAPERING OFF THURSDAY NIGHT. LIGHT TO MODERATE SNOW ACCUMULATIONS ARE LIKELY IN THE FAVORED NORTHWEST SNOWBELT AND HIGHER TERRAIN ALONG THE ALLEGHENIES/LAUREL HIGHLANDS. THE COLDEST AIRMASS OF THE 2015-16 WINTER SEASON REMAINS POISED TO ARRIVE THIS WEEKEND...AS A BLAST OF ARCTIC AIR DELIVERS A SHORT DURATION COLD OUTBREAK TO CENTRAL PENNSYLVANIA. SNOW SQUALLS ARE POSSIBLE WITH THE ARCTIC FRONTAL PASSAGE FRIDAY NIGHT INTO EARLY SATURDAY. MAX/MIN TEMPERATURE DEPARTURES OF -20 TO -25 DEGREES BELOW CLIMO ARE FCST SATURDAY AND SUNDAY. MINIMUM TEMPERATURES SATURDAY NIGHT INTO EARLY SUNDAY MORNING RANGE FROM AROUND 0F IN THE LOWER SUSQ. VALLEY TO -10F IN THE NORTHWEST ALLEGHENIES. THE FRIGID TEMPERATURES COMBINED WITH DANGEROUS WIND CHILLS /-10 TO -25 BELOW ZERO/ WILL RESULT IN AN INCREASED RISK FOR FROSTBITE AND HYPOTHERMIA. A SLOW MODERATION (WARMING TREND) IS EXPECTED INTO EARLY NEXT WEEK...BUT WITH A POTENTIAL OVERRUNNING/WAA TYPE SNOW EVENT. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... MAINLY VFR CIGS AND VSBYS WILL PREVAIL ACROSS THE SUSQ VALLEY TAF SITES /KIPT...KMDT AND KLNS/ WITH HIGH END MVFR CIGS AND VFR TO MVFR VSBYS AT KUNV AND KAOO. THE POOREST FLYING CONDITIONS WILL CONTINUE TO BE AT KJST AND KBFD FOR THE NEXT SEVERAL DAYS...WHERE CIGS AND VSBYS WILL BE MAINLY IN THE MVFR TO UPPER IFR RANGE...WITH OCNL DIPS TO LIFR/VLIFR IN LAKE EFFECT SNOW BANDS AND AREAS OF ENHANCED UPSLOPE SNOWS. FOR KUNV...KAOO...AND PERHAPS KIPT...EXPECT UP TO A FEW HOUR PERIOD OF MORE FREQUENT SNOW SHOWERS LATE TODAY AND AFTER SUNSET...AS A SECONDARY COLD FRONT PUSHES THROUGH THE AREA. GUSTY WEST TO WNW WINDS WILL PREVAIL THIS AFTERNOON...TONIGHT AND AND THURSDAY...AVERAGING 12-15 KTS WITH GUSTS IN THE LOW-MID 20 KT RANGE. OUTLOOK... THU/THU NIGHT...MVFR WITH PERIODS OF IFR IN -SHSN ACROSS THE WRN PENN MTNS. MAINLY VFR ELSEWHERE. FRI...MVFR IN -SHSN...MAINLY LATE WITH STRONG COLD FRONT. SAT...MVFR IN -SHSN W MTNS. VFR OTHERWISE. WINDY. SUN...MVFR IN -SHSN IN W MTNS EARLY...OTHERWISE VFR. MON...VFR POSSIBLE EARLY ACROSS THE EASTERN HALF OF PENN...THEN LOWERING AND THICKENING CLOUDS LIKELY WITH A FEW PERIODS OF SNOW POSSIBLE...YIELDING MVFR TO IFR VSBYS AND CIGS. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THURSDAY FOR PAZ005. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THURSDAY FOR PAZ004. WINTER WEATHER ADVISORY UNTIL 10 PM EST THURSDAY FOR PAZ010- 017-024-033. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT LONG TERM...STEINBUGL AVIATION...LAMBERT

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