Central PA Spring 2026 Discussion/Obs Thread

[Jns2183]

A Few Things That Should Make You Uncomfortable
At 100 ft — 62,351 ft³. Roughly the size of a large house. This is the only range where the radar is sampling anything resembling a point.
At 1 mile — 92 ft beam diameter, still smaller than a football field. Still reasonable. Still vaguely honest.
At 10 miles — beam is now 922 ft wide. Bigger than the range gate itself. The pancake starts to make sense.
At 65 miles (Camp Hill) — ~22 billion ft³. The beam diameter (~5,990 ft) is now wider than it is deep by a factor of 7. Your "data point" is a disc, not a cube. And it's floating at ~5,200 ft AGL.
At 100 miles — 54.9 billion ft³, beam nearly 1.75 miles wide, center beam at 9,708 ft AGL. At this point the radar is essentially sampling the lower stratosphere and calling it precipitation data.
Depth is always 822 feet.

It took me a number of ever increasing pancake sizes and a traffic cone of unsavory origins to visualize this. This pulse and about 50;more with 97% overlap get run through a bunch of algorithms and out pops a pixel over us. So if radar makes you want to pull your hair out, this is why.

America’s Boeing Everett Factory, 25 miles north of Seattle, remains the world’s largest building by volume and world’s largest factory. Workers assemble Boeing aircraft—including the new 787 Dreamliner—within this 472,000,000-cubic-foot factory.

My single radar pixel contains roughly 47 Boeing Everett Factories worth of air


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[Jns2183]

My Magnus Opus of why I can never be mad at preceiptitation reports after a big storms..
We've all been there. NEXRAD shows 0.50" for your pixel. Your CoCoRaHS gauge reads 0.22". Your neighbor two blocks over posts 0.81". Both of you are right. The radar might also be right. Here's why, and why it gets genuinely alarming during intense convection.
The Geometry First
I'm 73.8 miles from KCCX at State College. At that range, the 1° beam has expanded to 6,803 feet in diameter — that's 1.29 miles across. The center of that beam is floating 7,882 feet above my roof. The super-resolution pixel covering my house is 0.830 square miles / 2.15 km². The legacy pixel was 1.660 square miles / 4.30 km². That single dBZ value stamped on that pixel represents the average backscatter of a volume of air roughly the size of 12 Disneylands hovering a mile and a half above the ground.
Now imagine 100 top-of-the-line rain gauges evenly distributed across that pixel. Super-res spacing works out to one gauge every 481 feet. I stand dead-center in my grid cell. By Pythagoras, my four nearest gauges are at the corners — each 340 feet away from me.
Here's Where It Gets Uncomfortable
For well-behaved stratiform rain — your warm-frontal overrunning, your classic nimbostratus — everything is fine. CV of 0.10 to 0.16. My four nearest gauges within a few hundredths of each other. Radar is defensible. Life is good.
But bump up into Category 7 — intense convective core directly over the pixel — and the math falls apart spectacularly.
Radar reports 0.50". CV = 1.00. Standard deviation = 0.50". Lognormal distribution gives a pixel-wide range of 0.090" to 1.391" at the P5/P95 level. That's a 15:1 spread across my 0.830 square mile pixel, between gauges that are less than half a mile from each other.
But here's the part that genuinely made me sit back: my four nearest gauges — 340 feet away from me, about the length of a city block — have a realistic P10/P90 spread of 0.250" to 0.810". Three-to-one variation between gauges I can practically see from my porch. Both are physically correct measurements of the same event.
Scale that up to Category 8 — extreme/flash flood/training cells — and it becomes almost philosophical. Radar reports 0.50". Pixel range P5/P95: 0.052" to 1.613". That's a 31:1 ratio. My four nearest gauges: 0.157" to 0.965". Six-to-one. The gauge 340 feet north of me reads under two tenths. The gauge 340 feet east reads close to an inch. The radar says half an inch. Every single instrument is functioning perfectly.
At 1.00" reported by the radar the numbers get worse: Cat 7 gives my nearest four a spread of 0.500" to 1.620" and Cat 8 gives 0.314" to 1.930". The gauge closest to me physically could read less than a third of an inch while the one a city block away reads nearly two inches. During the same event. At the same time.
Why This Matters for Verification Work
This isn't a measurement error problem. This isn't instrument quality. This is the fundamental physics of convective precipitation at sub-kilometer scales, documented by Peleg et al. (2013) with a dense gauge network and confirmed repeatedly in the literature. Rainfall within a single radar pixel during convection can vary by over 100% — and that finding came from a network covering a smaller area than my NEXRAD pixel at 73.8 miles.
When someone posts their CoCoRaHS total and it's half what radar showed during a summer storm, the correct response isn't "your gauge is off." The correct response is "yes, that is entirely expected and physically consistent with everything we know about convective precipitation structure."
The radar isn't wrong. Your gauge isn't wrong. The atmosphere just doesn't care about our need for tidy single-number summaries.
The only honest statement you can make about precipitation during a Cat 7/8 event with a single gauge is: this is what fell at this exact point. Full stop. Extrapolating to even the next block over is an act of faith, not measurement.
Methodology: Lognormal distribution fit to literature CV values by precip type (Ciach & Krajewski 1999, 2006; Peleg et al. 2013; Jensen & Pedersen 2005). Local near-gauge CV compressed by exponential spatial correlation model. KCCX beam geometry calculated using 4/3 Earth radius refraction. All pixel areas computed from actual Camp Hill–KCCX range of 73.8 miles.

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[mahantango#1]

Hazardous Weather Outlook
National Weather Service State College PA
303 AM EDT Tue Apr 7 2026

PAZ026>028-035-036-049>052-056-057-059-063>066-080715-
Huntingdon-Mifflin-Juniata-Fulton-Franklin-Union-Snyder-Montour-
Northumberland-Perry-Dauphin-Lebanon-Cumberland-Adams-York-Lancaster-
303 AM EDT Tue Apr 7 2026

...FREEZE WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 9 AM EDT
WEDNESDAY...
...FREEZE WATCH IN EFFECT FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
MORNING...

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Today and tonight.

Please listen to NOAA Weather Radio or go to
weather.gov/StateCollege on the internet for more
information about the following hazards.

   Freeze Warning.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Please listen to NOAA Weather Radio or go to
weather.gov/StateCollege on the internet for more
information about the following hazards.

   Freeze Warning.
   Freeze Watch.

[Mount Joy Snowman]

Temp was 41 and dropping when I left the house. Had beautiful clear tequila sunrise skies just to my east and a thick cloud deck just to my west. A couple chilly ones ahead and then what could be a spectacular weekend. Carry on.