FXUS61 KCTP 211220 AFDCTP Area Forecast Discussion National Weather Service State College PA 820 AM EDT Sat Mar 21 2026 .WHAT HAS CHANGED... Dense Fog Advisory for a portion of east-central PA has expired. Severe thunderstorm risk level increased from 1 to 2 for Sunday over south central PA. && .KEY MESSAGES... 1) First weekend of Spring warmup precedes rain and severe thunderstorm risk Sunday afternoon into Sunday night. && .DISCUSSION... KEY MESSAGE 1: First weekend of Spring warmup precedes rain and severe thunderstorm risk Sunday afternoon into Sunday night A nice start to Spring this weekend with fcst highs ramping 15 to 30F above the historical average by Sunday. This surge of warmth will be brief and followed by a noticeable cooldown on Monday with max temps 20-30 degrees lower than Sunday. SPC expanded the level 2/slight risk outlook from the Upper Ohio Valley into south central PA (south of I-80) for Sunday afternoon and evening. CAPE and 0-6km shear profiles appear rather favorable for organized severe storms ahead of a southeastward advancing cold front. Large hail probs are relatively high with 700-500mb lapse rates 7-7.5 C/km and essentially match the damaging wind probs. Secondary frontal wave development near the Delmarva/srn NJ should hold up the cold front and allow colder temps to bleed/creep southward late Sunday night into Monday morning. This should result in a rain/snow mix or changeover to wet snow along the northern edge of the frontal precip band as it exits the area. A coating of snow up to 0.5" is most likely on non- paved sfcs across the northern tier by 12Z Monday. High temps on Monday are projected to be 20 to 30 degrees colder than Sunday, punctuated by a chilly and brisk/gusty NW wind. The rest of next week should feature more temperature swings up and down with occasional light precip. The best precip signal in the 21/00Z model cycle is in the late Thursday/Thursday night timeframe. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... Mixed bag of observations across central Pennsylvania this morning with fog across SE PA and lower ceilings bringing borderline MVFR-IFR ceilings elsewhere as of 10Z. All model guidance points to widespread improvement towards VFR after 12Z Saturday. Recent model guidance trends more optimistic with respect to conditions at most airfields (outside of BFD) reaching VFR thresholds by 15-16Z Saturday, which seems plausible. The main deviation from model guidance and previous forecast was to keep BFD down an extra hour or two due to model guidance typically being too optimistic here for improvement in ceilings. Between 18Z Sat and 06Z Sun, VFR conditions are virtually certain across all of central Pennsylvania. Model guidance continues to paint all airfields outside of MDT/LNS for continued VFR conditions, with the main concern being LLWS across W PA. LLWS concerns have seen an uptick in this region, so have decided to go ahead and include mentions even though these concerns are over twelve hours out, given the arrival of a 40-50kt LLJ across the region. Further southeast at MDT/LNS, southerly flow with an extremely slight easterly component could allow for some moisture for reach into the furthest reaches of the Lower Susquehanna Valley, mainly after 08Z Sunday. This would bring in lower ceilings with slightly lower potential for lower visibilities manifesting; however, have knocked these down some to keep trended with GLAMP model guidance which appears to be onto the same idea. Alternative scenarios of VFR continuing are most likely at MDT, with higher probabilities and confidence in the lower ceiling scenario playing out at LNS between 08Z-12Z Sun. Outlook... Sun...Rain overspreads north to south, restrictions possible. Mon...Rain gradually tapers off north to south, transition to snow possible mainly north of I-80 (BFD/IPT). Restrictions possible within rain/snow showers. Tue...Mainly dry with VFR conditions. Slight chance of snow shower across northern PA late which could bring some restrictions. Wed...Rain and snow showers across northern PA with restrictions possible. && .CLIMATE... Daily record high temperatures for March 22: Harrisburg 80 in 1938 Williamsport 82 in 1938 Altoona 81 in 1966 State College 80 in 1938 && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ WHAT HAS CHANGED...Steinbugl/Martin KEY MESSAGES...Steinbugl/Martin DISCUSSION...Steinbugl/Martin AVIATION...Beaty CLIMATE...Steinbugl