Area Forecast Discussion
Issued by NWS State College, PA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KCTP 310916 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 516 AM EDT TUE MAR 31 2015 .SYNOPSIS... A POTENT BUT RELATIVELY FAST MOVING AREA OF LOW PRESSURE WILL MOVE SOUTHEAST FROM THE WESTERN GREAT LAKES AND RIDE ALONG THE MASON- DIXON LINE TODAY. THIS STORM SYSTEM WILL BRING A HIGHLY ELEVATION DEPENDENT WET SNOWFALL OF A FEW TO SEVERAL INCHES ACROSS THE NORTHERN HALF OF PENNSYLVANIA. MIXED PRECIPITATION OR PLAIN RAIN WILL FALL ACROSS THE SOUTHERN TIER OF PENNSYLVANIA...WHERE A FEW MIDDAY AND AFTERNOON THUNDERSTORMS ARE ALSO POSSIBLE. HIGH PRESSURE WILL BUILD OVER THE REGION WEDNESDAY WITH FAIR AND COOL CONDITIONS. A SHARP MODERATION IN TEMPERATURES WILL OCCUR THURSDAY BEFORE A NEW COLD FRONT APPROACHES FOR FRIDAY WITH RAIN SHOWERS...POSSIBLY CHANGING TO A PERIOD OF SNOW AT NIGHT ACROSS THE NORTHWEST HALF OF PENN. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NARROW RIDGE OF HIGH PRESSURE EXTENDED FROM THE FINGER LAKES OF NEW YORK TO CENTRAL PENN AT 08Z. POTENT ALBERTA CLIPPER JUST EAST OF CHICAGO WILL TRACK ESE AND MOVE ALONG THE MASON-DIXON LINE THIS AFTERNOON. SOME SLIGHT VARIATIONS WERE NOTED IN THE LOW PRES TRACK VIA THE LATEST OPER MODEL AND ENSEMBLE GUIDANCE...BUT NO SIGNIFICANT CHANGES IN THE FORECAST OF UP TO SEVERAL INCHES OF SNOWFALL ACROSS THE HIGHER TERRAIN OF CENTRAL AND NRN PENN /WITH MAINLY RAIN FALLING OVER THE SOUTHERN THIRD OF THE STATE NEAR THE CENTER LINE OF THE STORM TRACK /AND JUST SOUTH OF THE MEAN 0C 850 MB ISOTHERM/. COORDINATED WITH SURROUNDING WFOS TO ISSUE A RATHER BORDERLINE WINTER WEATHER ADVISORY FOR WET SNOW DURING THE DAYLIGHT HOURS TODAY /WHICH IS STAGGERED BY ABOUT 2 HOURS FROM WEST TO EAST ACROSS OUR CWA...WITH RESPECT TO ONSET AND ENDING TIMES OF THE MAIN IMPACT PERIOD/. CONFIDENCE REMAINS QUITE HIGH FOR A SWATH OF MODERATELY HEAVY QPF OF 0.40 TO 0.60 OF AN INCH ACROSS THE NORTHERN HALF OF PENN...WITH LESSER AMOUNTS IN THE SOUTH. NEAR TERM HI RES /07Z HRRR/ AND SHORT RANGE ENSEMBLE SYSTEM DEPICT NEAR TO SLIGHTLY ABOVE ADVISORY CRITERIA SNOWFALL FOR PORTIONS OF THE WEST CENTRAL AND NORTH CENTRAL MOUNTAINS TODAY WITH ACCUMS OF UP TO 4 OR 5 INCHES AT ELEVATIONS ABOVE 1800 FT MSL. GIVEN THE MARGINALLY COLD LLVL AIR /AND THE BULK OF THE PRECIP/SNOW FALLING DURING THE WARMEST PART OF THE DAY/...WE STILL THINK THAT MOST DEEPER VALLEY LOCATIONS...AOB 1200 FT MSL WILL REMAIN NEAR OR SLIGHTLY BELOW ADVISORY AMTS WITH AROUND 2 INCHES. THE INITIAL ABOVE FREEZING BLYR SHOULD MEAN THAT SOME RAIN WILL BE MIXED IT AT THE ONSET...THEN A QUICK CHANGEOVER TO WET SNOW IS EXPECTED NEAR AND TO THE NORTH OF I-80 BY LATE THIS MORNING. A SEVERAL HOUR PERIOD OF MODERATE TO STG UVVEL ASSOCIATED WITH THE LEFT EXIT REGION OF A 100 KT UPPER JET WILL BRING A PERIOD OF MODERATE TO BRIEFLY HEAVY SNOW LATER THIS MORNING INTO EARLY THIS AFTERNOON...GRADUALLY TAPERING TO AREAS OF LIGHTER SNOW/SNOW SHOWERS FOR THE MID TO LATE AFTERNOON. THERE MAY BE LITTLE OR NO SNOW SOUTH OF THE TURNPIKE AND WEST OF INTERSTATE 81...ALONG AND JUST SOUTH OF THE LOW TRACK. CONSIDERING NUMEROUS MAIN TRAVEL ROUTES ACROSS CENTRAL AND NRN PENN...CRESTING TERRAIN ABOVE 1600 FT MSL...WE PLAYED IT ON THE SAFE SIDE AND WENT WITH A LOW-END ADVISORY FOR THIS LATE SEASON WET SNOWFALL. LATE DAY HIGH TEMPS WILL BE LOWER TO MIDDLE 30S ACROSS THE NORTH...NEAR 40F JUST TO THE SOUTH OF I-80...AND LIKELY CRESTING THE 5O DEGREE MARK OVER THE SCENT REGION AND LOWER SUSQ VALLEY. LASTLY...SPC HAS 1-2 LAYERS OF COUNTIES IN SCENT PENN WITHIN THEIR GENERAL TSRA CATEGORY FOR THIS AFTERNOON AS SFC BASED CAPES /ALONG AND JUST TO THE SOUTH OF THE PROJECTED SFC LOW TRACK/ CLIMB TO SEVERAL HUNDRED J/KG. INCLUDED THE CHC FOR TSRA IN OUR WEATHER GRIDS ACRS THE SOUTHERN TWO LAYERS OF COUNTIES IN SCENT PENN THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... SFC LOW WILL EXIT THE NJ/DELMARVA COAST TONIGHT WITH HIGH PRESSURE ARRIVING FROM THE GREAT LAKES. DRY WEATHER WILL PERSIST THROUGH MIDWEEK BEFORE THE PATTERN TURNS INCREASINGLY UNSETTLED FROM THURSDAY INTO EASTER WEEKEND. LOW TEMPS TNGT WILL RANGE FROM AROUND 20 IN THE NORTH TO 30F IN THE SOUTH. HIGHS WEDNESDAY WILL BE IN THE UPPER 30S ACROSS THE NORTH...AND AROUND 50F IN THE FAR SOUTH...ACCOMPANIED BY PARTIAL CLEARING AND A 7-12 KT NWRLY WIND && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... YESTERDAYS 12Z.../AND THE LATEST 00Z/ MODEL RUN AND ENSEMBLE DATA...CONTINUE TO INDICATE THAT ONE OR TWO FRONTAL WAVES WILL BRING PCPN TO THE AREA FROM THURSDAY INTO SATURDAY. THERE IS STILL SOME SPREAD IN BOTH THE TRACK AND STRENGTH OF THE TRAILING FRONTAL WAVES WITH THE LAST TWO RUNS OF THE EC COMING IN MUCH STRONGER THAN THE GFS. THE CANADIAN IS IN THE MIDDLE IN TERMS OF POSITION BUT LEANS TOWARD THE STRONGER EC. AT ANY RATE THE DETAILS ARE STILL UNCLEAR BUT A MEAN BLEND/CONSENSUS SOLUTION INCORPORATING WPC GUIDANCE SUPPORTS INCREASING POPS INTO THE LKLY RANGE FOR AT LEAST TWO 12-HOUR PERIODS. A SHORTWAVE TROUGH ROTATING THROUGH THE MID ATLC AND NORTHEAST STATES WILL BRING A REINFORCING SHOT OF COOL AIR ON SATURDAY...PRECEDED BY ABOVE NORMAL TEMPS AHEAD OF THE COLD FRONT. THE COOL DOWN SHOULD BE BRIEF WITH MODERATING TEMPS INTO EARLY NEXT WEEK. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... 06Z TAFS SENT. WIDELY SCATTERED RAIN SHOWERS ARE MAINLY EAST OF THE AREA NOW. STILL SOME MID LEVEL CLOUDS ACROSS THE AREA...MAINLY CENTRAL AND SOUTHERN AREAS. EARLIER DISCUSSION BELOW. UPPER TROF SLIDING EASTWARD THIS EVENING OVER SOUTHERN NEW YORK STATE ALONG WITH STEEP LOW-LEVEL LAPSE RATES IS MAINTAINING SCATTERED SNOW AND RAIN SHOWER ACTIVITY ACROSS THE NORTHERN MOUNTAINS THIS MID EVENING...WITH INTERMITTENT CIG/VSBY REDUCTIONS IN THE MOST INTENSE CELLS. EXPECT THUS ACTIVITY TO DECREASE BY LATE EVENING (03Z-04Z) AS UPPER TROF AXIS SLIDES EAST AND LLVLS STABILIZE. CONDITIONS SHOULD RETURN TO VFR AREAWIDE FROM LATE EVENING HEADING TOWARD SUNRISE...WITH WINDS DIMINISHING BELOW 10 MPH. A FAST MOVING ALBERTA CLIPPER WILL BRING ANOTHER EARLY SPRING WINTRY WEATHER EVENT TO MUCH OF CENTRAL AND NORTHERN PENN. REDUCTIONS WILL BEGIN AROUND OR SHORTLY BEFORE DAYBREAK TUESDAY ACROSS THE WESTERN MTNS...THEN SPREAD ACROSS THE REMAINDER OF THE REGION DURING THE MID TO LATE MORNING HOURS. A SHIELD OF STEADY LIGHT TO MDT SNOW ACROSS THE NORTHERN THIRD OF PENN WILL DROP CONDITIONS TO IFR/LIFR FROM BFD TO POINTS EAST TWD KIPT BY MID MORNING TUE. IFR IN MIXED PRECIP OR SNOW APPEARS LIKELY FOR THE CENTRAL THIRD OF THE STATE TUESDAY MORNING/EARLY AFTERNOON...WHILE A FEW PERIODS OF LIGHTER RAIN/SNOW SHOWERS WILL OCCUR ACROSS THE SOUTHERN TIER COUNTIES OF PENNSYLVANIA WITH GENERALLY MVFR CIGS/VSBYS. SOME LIGHTER AND MORE BRIEF RAIN AND SNOW SHOWERS REMAIN FROM LATE TUESDAY AFTERNOON INTO EARLY WEDNESDAY...IN THE WAKE OF THE EXITING LOW PRESSURE AREA. OUTLOOK... WED-THU MORNING...MAINLY VFR...AS HIGH PRESSURE BUILDS ACROSS THE AREA. THU PM-FRI...LOWERING CONDITIONS TO MVFR WITH SCATTERED RAIN SHOWERS...AS A COLD FRONT MOVES EASTWARD. GUSTY SW WIND DEVELOPING. SAT...LOW PROB FOR RAIN SHOWERS /MIXED WITH SNOW SHOWERS NORTH/. REDUCTIONS POSS MAINLY NORTHERN MTNS. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 8 AM THIS MORNING TO 6 PM EDT THIS EVENING FOR PAZ004>006-010>012-017>019-045. WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR PAZ037-041-042-046-049-051>053-058. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT/DEVOIR SHORT TERM...LAMBERT/DEVOIR LONG TERM...LAMBERT/STEINBUGL AVIATION...MARTIN/RXR

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.