Central PA Spring 2026 Discussion/Obs Thread

[Voyager]

Only 78 here, but no complaints. I don't need 80+. This is just fine. 

[mahantango#1]

82 was my high today.

[Yardstickgozinya]

I only included discussion specifically regarding localized threats. The full discussion is in the link below. No science to it, just a roll of the dice and some twisted intuition. I sense a convactive over achiever coming on today. Not that it will translate to today, but cpa had some decently, elevated  parameters that went the waste yesterday . The cap fully eroded over most of the area by mid-afternoon, but a lack of forcing and meager mid-level's hindered any convective development.

Although simple details, I think frontal timing and orientation are conducive to localize overachievement, especially if the sun can get that surface baked for us cpa southernish. 

SPC AC 010548 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Wed Apr 01 2026   Valid 011200Z - 021200Z ...Ohio Valley/Mid-Atlantic... West-southwesterly mid-level flow will be in place over much of the eastern U.S. today. At the surface, a quasi-stationary front will be located in the Ohio Valley from southern Indiana east-northeastward into far southern Pennsylvania. Surface dewpoints in the upper 50s and lower 60s F to the south of the front will contribute to weak instability by early afternoon. Increasing low-level convergence near the front and warming surface temperatures will result in scattered thunderstorms during the afternoon. Several short line segments are expected to form and move eastward across the Ohio Valley into the central Appalachians. 0-6 km shear in the 25 to 35 knot range and steep low-level lapse rates will support isolated severe storms with potential for damaging wind gusts. A low-end tornado threat will also be possible. https://www.spc.noaa.gov/products/outlook/day1otlk.html

[Yardstickgozinya]

I occasionally read lazy forecast discussions, from time to time, but this one really stands out, especially in it's extended. Full discussion is in the link below.

 

211
FXUS61 KCTP 010817
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
417 AM EDT Wed Apr 1 2026

.WHAT HAS CHANGED...
* Severe thunderstorm watch #83 has been cancelled

&&

.KEY MESSAGES...
1) Big temperature swings and periods of rain/thunderstorms
continue through Easter weekend into the first full week of
April

&&

.DISCUSSION...
KEY MESSAGE 1: Big temperature swings and periods of
rain/thunderstorms continue through Easter weekend into the
first full week of April

At the surface, a quasi-stationary front will be located from
southern Indiana east-northeastward into southern Pennsylvania
by the afternoon. Surface dewpoints in the upper 50s and lower
60s F to the south of the front will contribute to weak
instability. Increasing low-level convergence near the front
and warming surface temperatures into the 70s should trigger
scattered thunderstorms. 0-6 km shear in the 25 to 35 knot
range and steep low-level lapse rates will support isolated
strong to severe storms with potential for damaging wind gusts
focused within west-east corridor to the south of I-80 to MD
line. Periods of rain/showers continue tonight into Thursday
morning.

 

https://forecast.weather.gov/product.php?site=CTP&issuedby=CTP&product=AFD&format=CI&version=1&glossary=1&highlight=off

[mahantango#1]

[Mount Joy Snowman]

63 when I left the house with no rain. We’ll see what today brings. The train is a callin’. 

[Jns2183]

If you ever asked the question "I wonder what the local ASOS Stations at KCXY, KMDT, KTHV, KLNS record for wind when they have an kind of Snow" I have the fun answers below. Local terrain and microclimates making themselves known. Especially the wind tunnel that is the Susquehanna River

Sent from my SM-S731U using Tapatalk

[Jns2183]

84 here. I guess we skipped the second half of March, April and May. 

You say that now, but just wait till we get locked in the 50's half of May. On the years ahead of us from work they finish a plus 1.7 and exactly normal for April and May. Although they did have April's with mean in 40s and may mean In 50's

Sent from my SM-S731U using Tapatalk

[Jns2183]

I guess I should add York.

Sent from my SM-S731U using Tapatalk

[pawatch]

80 was the high yesterday. Rainfall yesterday and over night .25”

Grass is starting to grow. Maybe next week first cut.

[Itstrainingtime]

A ridiculous low of 65 this morning. No rain at home or at work but a pretty good shower fell in between.

Anyone see any snow piles left when you're out and about? Columbia Borough still has a pile about 2-3' deep in a vacant lot along the river. Last week at this time it was at least 5' so I'm not sure it has another week left in it or not. Still impressive considering how long it's been since it's snowed and how warm it's been over the past several weeks. 

[Jns2183]

I finally finished cateloging all winter storms greater than 3" since 2000 till end of 2025
77 storms

A bunch of other winter stuff is there too. I think it's a good start
https://jns182wx.github.io/winter-weather/

Sent from my SM-S731U using Tapatalk

[Itstrainingtime]

1 minute ago, Jns2183 said:

I finally finished cateloging all winter storms greater than 3" since 2000 till end of 2025
77 storms

A bunch of other winter stuff is there too. I think it's a good start
https://jns182wx.github.io/winter-weather/

Sent from my SM-S731U using Tapatalk
 

Holy cow, this is amazing! Thank you! This is a tremendous reference and just fun to read as well. 

[Jns2183]

Holy cow, this is amazing! Thank you! This is a tremendous reference and just fun to read as well. 

Thank you. I have to fix the stuff on the RSI page to actually show all records I have. I downloaded our top 10 storms from dive in CSV format but git hub co-pilot wanted to just keep the 4 station theme going and I was in no mood to fix after 5 hours at 1:30am. Eventually I'll try to get all the storms I can between RSI and Cocorahs. All accumulation I have are from kmdt for most part due to them actually keeping track of snow there. Small airports don't really have a point person for that. Other than that I downloaded every single hourly and daily record I could from those 4 sites over the years. 500mb of csv files, thank God for paraquet formats.

Sent from my SM-S731U using Tapatalk

[Itstrainingtime]

March stats are in from Lanco:

There were certainly more "ups" than "downs" on the wild March 2026 temp rollercoaster, and those "ups" were also much more significant than the "downs." As a result, it concluded as the 8th-warmest March on record.

[Jns2183]

MOS WHACK A MOLE
I've learned way way too much about this over the last couple months so now you get to also.

If you ever wonder why a new version of the GFS is in training forever it's MOS, it is always MOS

MOS is basically not “an equation.” It’s a bloated empire of site-by-site statistical band-aids.
At one station like MDT, a single MOS package can involve hundreds to over a thousand equations once you break out forecast hour, variable, and category thresholds. Then double it for warm vs. cool season.
Now spread that across 2,000 sites and multiple guidance systems, and you’re dealing with millions of regression equations.
So when model physics gets changed upstream, MDL doesn’t get a fun little tune-up. They get to play nationwide statistical whack-a-mole because half their bias-correction patchwork may now be off.
That’s the whole game.

MY next little project until I recover from winter storm data burnout is one I'm almost halfway through. A fun little deep dive into the various MOS for the the GFS, NAM, HRRR, NBM and a 10 year (8 year for NBM);statistical analysis of forcasting skill by them for KMDT using about 25 metrics from NWS and Research Papers for every variable that can be seen, computer, derived from data record of KMDT. And think. This skill is after a couple thousand linear regression equations to brow beat NAMs drunken benders

Sent from my SM-S731U using Tapatalk

[Jns2183]

That 68 wind guest should be 28:for Harrisburg, haha

Sent from my SM-S731U using Tapatalk