Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 151956 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 356 PM EDT TUE APR 15 2014 .SYNOPSIS... A STRONG COLD FRONT WILL PUSH EAST OF PENNSYLVANIA EARLY THIS EVENING. MUCH COLDER AIR WILL COVER THE COMMONWEALTH TONIGHT AND WEDNESDAY...WITH POSSIBLE RECORD LOW TEMPERATURES EARLY WEDNESDAY MORNING. A GRADUAL REBOUND IN TEMPERATURES ACCOMPANIED BY FAIR...DRY WEATHER WILL OCCUR FOR THURSDAY AND FRIDAY. A POTENT UPPER AIR DISTURBANCE WILL MOVES EAST FROM THE GREAT LAKES ON SATURDAY...BRINGING COOLER TEMPERATURES WITH SOME MOUNTAIN RAIN AND SNOW SHOWERS POSSIBLE. && .NEAR TERM /UNTIL 11 PM THIS EVENING/... AFTER A MILD START TO THE DAY WITH TEMPS IN THE LOWER TO MID 60S ACROSS CENTRAL AND ERN PENN...TEMPS HAVE PLUMMETED WELL DOWN INTO THE 30S ACROSS THE NRN AND WRN MTNS...AND INTO THE U30S AND 40S ACROSS THE CENTRAL MTNS AND MUCH OF THE SUSQ VALLEY. A WEAK WAVE OF LOW PRESSURE AND ASSOCIATED UPPER SHORT WAVE RIDING NE FROM THE MID ATLANTIC PIEDMONT WILL MAINTAIN PLENTY OF THICK CLOUDS AND PERIODS OF RAIN ACROSS THE SUSQ VALLEY AND POINTS EAST LATE THIS AFTERNOON INTO EARLY THIS EVENING. A FEW HOUR PERIOD OF SNOW WILL IMPACT THE NRN AND WESTERN MTNS BETWEEN 19-23Z...BRINGING A SLUSHY INCH OR TWO TO ELEVATIONS AOA 1400 FT MSL...WITH ONLY A COATING IN THE DEEPER RIVER VALLEYS. SIMILAR LIGHT ACCUMULATION IS LIKELY ACROSS THE LAURELS. THE RAIN WILL MIX WITH AND CHANGE TO A LITTLE WET SNOW LATE TODAY AND THIS EVENING OVER...AND TO THE EAST OF...THE SUSQ VALLEY. A SLUSHY INCH IS POSSIBLE ON COLDER GRASSY AREAS ACROSS THE HIGHER TERRAIN OF SCHUYLKILL COUNTY...NORTH TO SULLIVAN COUNTY BEFORE ANY LINGERING SNOW FIZZLES OUT BY 03Z. HI RES WRF ARW AND 09Z SREF /ALONG WITH VARIOUS OTHER OP MODEL GUIDANCE/ INDICATES UP TO A FEW TENTHS OF QPF FALLING AS MAINLY SNOW ACROSS OUR FAR ERN ZONES BETWEEN 22Z-02Z WED...BUT RECENT WARMTH HAS KEPT GROUND TEMPS QUITE WARM...SO LITTLE PROBLEM IS EXPECTED TRAVEL-WISE IN THE EAST. && .SHORT TERM /11 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... PRECIP SHOULD DRY IN THE WAKE OF THE CFRONT BY SHORTLY AFTER DARK IN THE EAST...WITH JUST SOME SCATTERED LIGHT SNOW SHOWERS LINGERING ACROSS THE HIGHER TERRAIN OF THE NORTH AND WEST AS THE SUBSIDENCE INVERSION BASE CRASHES TO BELOW 4 KFT AGL. THE NW WIND /AND GUSTS/ WILL PEAK EARLY TONIGHT AS THE COLDER AIR DEEPENS IN COMBINATION WITH A MODERATELY TIGHT LLVL P-GRADIENT. GUSTS AROUND 30 KTS WILL BE COMMON THROUGH ABOUT 04-06Z. CLOUDS WILL OF COURSE LINGER OFF LAKE ERIE AND OVER THE NRN MTS EARLY TONIGHT. MIN TEMPS EARLY WED ARE EXPECTED TO SETTLE NEAR...OR EVEN SEVERAL DEG F BELOW RECORD LOWS FOR THE DATE. SEE CLIMO SECTION BELOW FOR SPECIFIC RECORDS AT VARIOUS LOCATIONS ACROSS THE REGION. THE CLEARING AND SIGNIFICANT CAA WILL DROP TEMPS INTO THE 20S. EVEN THE SE WILL GET INT THE M20S - EVEN WITH A 10-15KT NWRLY WIND THROUGH THE LATE NIGHT/EARLY MORNING HOURS WED. A FREEZE WARNING IS IN EFFECT FOR THOSE ZONES WHICH HAVE JUST PASSED THE CLIMATOLOGICAL MEAN DATE OF LAST SPRING FREEZE...AND A FREEZE WATCH WAS RECENTLY POSTED FOR WEDNESDAY NIGHT ACROSS THE SAME SE ZONES. A MAINLY SUNNY...BUT UNSEASONABLY COLD DAY IS SHAPING UP FOR THE ENTIRE REGION WEDNESDAY. WINDS WILL BE MUCH LIGHTER AS HIGH PRESSURE BUILDS IN FROM THE OHIO VALLEY...BUT WITH 850 MB TEMPS AVERAGE MINUS 8-12...MAXS WILL ONLY REACH THE UPPER 30S ACROSS PARTS OF THE NRN AND WESTERN MTNS...AND UPPER 40S IN THE SE. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... STG RIDGING WILL EXTEND SWWD ALONG/EAST OF THE APPALACHIANS FROM STG HP CELL CENTERED OVER MAINE AND THE CANADIAN MARITIMES. THE SYNOPTIC CONDITIONS LOOK FAVORABLE FOR FROST/FREEZE CONDITIONS AGAIN WED NGT INTO AM THURS...AND THEREFORE ISSUED A FREEZE WATCH FOR THE SERN ZONES WHERE THE GROWING SEASON IS UNDERWAY. HIGH PRESSURE WILL STRENGTHEN TO +3-4SD OVER NORTHERN NEW ENGLAND THROUGH THURSDAY...BEFORE SLOWLY WEAKENING INTO THE UPCOMING WEEKEND. THIS SUGGESTS A POSSIBLE EASTERLY MARITIME LLVL FLOW WITH LOW CLOUDS AND PERHAPS SOME LGT RAIN/DZ POSSIBLY REACHING INTO THE SERN ZONES. THERE IS GENERAL AGREEMENT IN A SHORTWAVE TROUGH CROSSING THE GREAT LAKES REGION FRI-SAT WITH THE BEST CHC FOR RAIN OVER THE NW 1/3 OF THE CWA. THE MODELS GENERALLY AGREE ON THIS IDEA BUT TIMING DIFFS MAY BE AN ISSUE. THE UPPER LEVEL PATTERN BRIEFLY RELAXES LATE IN THE WEEKEND BEFORE REAMPLIFYING UPSTREAM...WITH STRONG HEIGHT FALLS /CUT-OFF LOW PROGGED ALONG THE WEST COAST...SLIGHTLY ABOVE- AVG 500MB RIDGING EXPANDING INTO THE N-CENTRAL PLAINS AND TROUGHING LINGERING OVER THE NERN CONUS. THERE IS LOW CONFIDENCE IN THE PCPN PATTERN DUE THE COMPLEXITY OF THE LW FLOW...WITH SEVERAL LOW-MEDIUM CHC OPPORTUNITIES FOR RAIN IN THE OUTER PERIODS. TEMPERATURES WILL BOTTOM OUT ON WEDNESDAY WITH HIGHS -10 TO -15 DEGREES BELOW NORMAL. A MILDER SW FLOW ALOFT WILL ALLOW READINGS TO MODERATE THROUGH THE END OF THE PERIOD...BUT LKLY STILL AVG BELOW LATE APRIL CLIMO. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... COLD FRONT IS PRESSING EAST TWD THE DELAWARE VALLEY AT 19Z. ALONG PERIODS OF RAIN WILL PERSIST ACROSS THE SUSQ VALLEY AND POINTS EAST UNTIL 22-00Z WED. ELSEWHERE ACROSS THE CENTRAL AND WEST...MVFR TO LOW-END VFR CONDITIONS WILL BE COMMON. SCATTERED LIGHT RAIN AND SNOW SHOWERS WILL FALL ACROSS THE CENTRAL VALLEYS...WITH PERIODS OF SNOW ACROSS THE WESTERN AND NRN MTNS...WHERE OCNL IFR WILL DEVELOP LATE THIS AFTERNOON INTO EARLY THIS EVENING. GRADUAL IMPROVEMENT TO MAINLY VFR WILL FOLLOW FOR TONIGHT ACROSS THE CENTRAL AND EASTERN ZONES...WITH LINGERING MVFR TO IFR CIGS AND VSBYS IN SNOW SHOWERS ACROSS THE WRN MTNS THROUGH AT LEAST EARLY TONIGHT. WED THRU FRI SHOULD BE FAIRLY BENIGN...WITH ANOTHER ROUND OF WET WEATHER POSSIBLE BY SAT. OUTLOOK... .WED-FRI...GENERALLY VFR. .SAT...REDUCED CIGS/VSBYS IN RAIN /AND POSSIBLY SOME WET SNOW ACROSS THE HIGHER TERRAIN/. .SUN...MAINLY VFR UNDER A WEAK RIDGE OF HIGH PRESSURE. && .CLIMATE... MORNING TEMPERATURES TOMORROW AND THURSDAY WILL CHALLENGE RECORD LOWS. BELOW ARE SELECTED RECORDS FROM AROUND THE AREA. AOO... WEDNESDAY 24/1950/... THURSDAY 23/1980/ BFD... WEDNESDAY 18/1980/... THURSDAY 16/1983/ IPT... WEDNESDAY 20/1943/... THURSDAY 25/1904/ MDT... WEDNESDAY 25/1943/... THURSDAY 29/1980/ && .CTP WATCHES/WARNINGS/ADVISORIES... FREEZE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY MORNING FOR PAZ057-059-063>066. FREEZE WARNING FROM 2 AM TO 8 AM EDT WEDNESDAY FOR PAZ057-059- 063>066. && $$ SYNOPSIS...DANGELO/LAMBERT NEAR TERM...LAMBERT SHORT TERM...DANGELO/LAMBERT LONG TERM...STEINBUGL AVIATION...LAMBERT CLIMATE...COLBERT/STEINBUGL

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