Central PA Spring 2026 Discussion/Obs Thread

[Yardstickgozinya]

Just now, Jns2183 said:

Are you able to open the PDF I linked to from my Google drive,?

Sent from my SM-S731U using Tapatalk
 

Yes  I thoroughly  enjoyed looking that over.  That's what compelled me to post the mcs with eye and the full July 2003 radar. If you watch that July radar,  long enough without blinking, it's like playing tetris and pacman at the same time. I thought the mcs with eye was a good storm for a Jns case study.  That storm also absolutely rocked the area  bty. I don't recall it having the most storm damage in this general area , but it definitely didn't pass over our area quietly either . 

[mahantango#1]

17 this morning.

[mahantango#1]

[Yardstickgozinya]

23 minutes ago, Jns2183 said:

Are you able to open the PDF I linked to from my Google drive,?

Sent from my SM-S731U using Tapatalk
 

It's amazing that some years we struggle to get one single cell in the area the strength of any of those and that's just three days in April. I don't know if you or anyone here has ever  searched 2011 pennsylvania tornado on youtube. Several of the tornadoes and storms spoken of the last few days are there on video and no shortage of ones that haven't been brought up or completely forgotten. 

[mahantango#1]

Wow look at those single digits on the map. 

US National Weather Service State College PA 

 

 

With any luck  this morning will be the coldest temperatures we experience until late October or November.

[Mount Joy Snowman]

I know it was discussed a bit how things were stronger east of the river with the frontal passage Monday night but not sure if it was pointed out that LNS saw a peak gust of 66, while I believe the next two strongest were MUI and MDT with readings of 54 and 52.

[mahantango#1]

My take on the severe weather that was supposed to happen but really didn't get it's act together. Social Media, TV were saying it could happen and let the public know. But it seems the public now won't believe the media if there is a real threat in the near future, and there could be property damage and injuries, and loss of life from not heeding warnings. I understand forecasts aren't perfect. But if the models are hinting at something like severe weather, we should all pay attention and take the necessary precautions.

[Jsauss]

21 hours ago, WmsptWx said:

They blocked my ass. I can't see shit lol.

me too. But i am seeing other peoples social media. its great. 

[Itstrainingtime]

43 minutes ago, Mount Joy Snowman said:

I know it was discussed a bit how things were stronger east of the river with the frontal passage Monday night but not sure if it was pointed out that LNS saw a peak gust of 66, while I believe the next two strongest were MUI and MDT with readings of 54 and 52.

Top gust at the Maytown Parachute Club was just 42 mph. 

At the very top of Kinderhook Road there are a couple of yards that are still almost fully blanketed in white from Monday night's snowfall. 

[Summit Snow]

3 hours ago, Superstorm said:

19.8F this morning. Last teens until November/December?


.

Maybe for you down there! 

[WmsptWx]

2 hours ago, Jsauss said:

me too. But i am seeing other peoples social media. its great. 

I saw somebody noted they issued an apology. I wonder if companies started pulling business. 

 

I'll admit, I was petty. I found an old FB post from Shipley Energy from 12 years ago (of which I am a customer in Bigler) and posted the screenshot from this thread, and then another business who had a post from seven years ago. I want them bankrupt.

[NepaJames8602]

It was 12 degrees at 530 am when I left for work. Had a fresh cover of les last night here in the Poconos as well.

As of quarter after noon, it still hasn't melted off, with temps hanging in low 20's. 

[Jns2183]

My take on the severe weather that was supposed to happen but really didn't get it's act together. Social Media, TV were saying it could happen and let the public know. But it seems the public now won't believe the media if there is a real threat in the near future, and there could be property damage and injuries, and loss of life from not heeding warnings. I understand forecasts aren't perfect. But if the models are hinting at something like severe weather, we should all pay attention and take the necessary precautions.

At a certain point you can't hand hold the public. They either start to get it or they experience the consequences of not. My take is they are going to do whatever they want and if it goes wrong in any way they look to first person other than themselves to blame. Whatever it is that introduced this rot into our cultures era specific mindset needs to be ruthlessly scrubbed out.

Sent from my SM-S731U using Tapatalk

[Jns2183]

MDT vs. CXY: Quantifying the Bias Between Harrisburg's Two ASOS Stations (and Why It Matters for the Pre-1991 Record)

Something that doesn't get talked about much in discussions of Harrisburg climatology is that the "official" record changed stations in October 1991 — from Capital City Airport (CXY, Fairview Township, York County) to Harrisburg International (MDT, Lower Swatara Township, Dauphin County/Susquehanna floodplain) — and that switch was made with no homogeneity adjustment whatsoever. The ThreadEx composite that most people pull from ACIS just splices them together at that date and calls it a day.

I decided to actually quantify the bias using the 2001–2025 overlap period, when both stations were running reliably as ASOS units. 25 years of IEM daily data, both stations. Here's what I found.

---

PRECIPITATION

MDT runs wetter than CXY every single month except April, with an annual median ratio of 1.106 — meaning MDT receives roughly 11% more precipitation per year (43.3" vs. 38.4" mean over the overlap). The ratio is most consistent and statistically tight in winter (DJF ratio 1.126, tight bootstrap CI), which makes sense — synoptic-scale systems produce more uniform precipitation and the floodplain position at MDT reliably enhances totals. The widest uncertainty is in the summer convective months (Jun–Sep CI spans nearly 0.3), reflecting the high year-to-year variance when a single tropical remnant or MCS can hit one site much harder than the other. September has the largest single-month ratio at 1.164.

April is the odd one out at 0.988 — essentially no bias. Spring frontal/stratiform precipitation appears to be the most spatially uniform regime between these two sites.

The implication for ThreadEx is that the unadjusted splice at October 1991 introduces approximately an 11% step-down in precipitation when you cross back into the pre-1991 CXY period. Any trend analysis using that composite without adjustment is going to be systematically affected.

---

TEMPERATURE

The temperature story is more interesting than the precipitation one. Max temp is straightforward — MDT runs cooler than CXY all 12 months, ranging from −0.19°F in summer to −0.97°F in January. River valley moderating daytime heating, nothing surprising.

Min temp is where it gets physically interesting: the offset reverses sign seasonally. MDT runs cooler than CXY in winter (as low as −0.71°F in February) but warmer in summer (+1.09°F in July). The crossover is right around April, which is near zero (+0.03°F).

What you're seeing is the competing effects of cold air drainage into the Susquehanna floodplain in winter (making MDT colder at night) versus the river's thermal mass keeping the MDT boundary layer warmer on summer nights. CXY sits on a ridge position in Fairview Township at ~106m and apparently drains cold air off efficiently in winter while losing the river's moderating influence in summer. It's a textbook valley-versus-upland nocturnal temperature signature and it comes through cleanly in 25 years of data.

---

DEWPOINT AND RH

MDT runs higher dewpoint and RH than CXY all 12 months — no sign reversal here. The Susquehanna just keeps MDT moister year-round. The RH offset is largest in winter (DJF +3.68%) and smallest in summer (JJA +1.69%), which probably reflects the relative importance of the river moisture source versus atmospheric moisture demand across seasons.

---

PRACTICAL UPSHOT

If you're doing any work with the Harrisburg long-period record — trend studies, climatological normals, CAD research, whatever — and you're pulling ThreadEx without thinking about this, you should be aware of the discontinuity. The pre-1991 CXY record can be adjusted to MDT-equivalent using monthly multiplicative ratios for precipitation and additive offsets for temperature/dewpoint, derived from the overlap period. The adjustment is stable enough (particularly in the cool season) that I'm reasonably confident applying it back through the CXY record to 1939.

Happy to share the Excel adjustment factor table if anyone wants — monthly ratios with bootstrap CIs, plus seasonal summaries broken out by DJF/MAM/JJA/SON.


Sent from my SM-S731U using Tapatalk

[pasnownut]

7 hours ago, mahantango#1 said:

My take on the severe weather that was supposed to happen but really didn't get it's act together. Social Media, TV were saying it could happen and let the public know. But it seems the public now won't believe the media if there is a real threat in the near future, and there could be property damage and injuries, and loss of life from not heeding warnings. I understand forecasts aren't perfect. But if the models are hinting at something like severe weather, we should all pay attention and take the necessary precautions.

While you are correct that we should all pay attention, there was little reason IMO for public/private businesses to shut doors at 1-2pm.  While you cant put a real value on loss of life, the signs just really didn't look THAT ominous.  Secondly for those of us who had to buck it up and ride the storm out from our cars/work whatevs.... knowing that the real show wasn't to start after rush hour (here in east central/eastern locals), that wasn't a good look and one where distrust can fester from.  Tough calls, but I agree, the misinformation shown on soc. media, didnt help AT ALL.