Central PA Winter 25/26 Discussion and Obs

[Ruin]

11 minutes ago, Yardstickgozinya said:

Another forecast discussion should be available in about an 1.5 hours, but I still feel this was a pretty interesting read, with a lot more explanation then generally seen. It's a very lengthy discussion, so I only posted part of it here, the rest will be in the link if anybody wants to read it before the next update. 

 

436

FXUS61 KCTP 230420

AFDCTP

Area Forecast Discussion

National Weather Service State College PA

1120 PM EST Thu Jan 22 2026

.WHAT HAS CHANGED...

* Increasing chances for heavy snow this weekend. More details

  provided in discussion section.

&&

.KEY MESSAGES...

1) Frigid temperatures and dangerous wind chills expand from

northwest to southeast Friday afternoon into Saturday morning

2) Increasing odds for double digit heavy snow accumulation and

widespread moderate to major winter storm impacts Saturday

night through Monday morning, heaviest on Sunday.

3) Arctic blast persists with frigid temperatures and subzero wind

chills expected next Monday all the way through next weekend.          &&

.DISCUSSION...

KEY MESSAGE 1: Frigid temperatures and dangerous wind chills expand from northwest to southeast Friday afternoon into Saturday morning.Arctic air is poised to return to the forecast area - filtering in from northwest to southeast through Friday night. High confidence in -10 to -20F wind chills across all of central PA Friday afternoon into early Saturday morning approaching extreme cold criteria in the Laurel Highlands. Frigid Arctic air will remain in place prior to the onset of the significant winter storm this weekend.

KEY MESSAGE 2: Increasing odds for double digit heavy snow accumulation and widespread moderate to major winter storm impacts Saturday night through Monday morning, heaviest on Sunday. Snow accumulations will likely begin with a vengeance from south to north in the predawn hours Sunday. Periods with snowfall rates greater than 1 inch per hour are becoming increasingly likely in the isentropic ascent early Sunday and as low and midlevel frontogenesis becomes stronger later in the day and evening. Given the dry, fluffy snow and wind gusts of 15-30 mph, there will likely be some blowing and drifting. There could be a period of sleet especially across the southern tier Sunday evening cutting into snow totals just a bit, but not before double digit accumulations are expected to fall.While warm advective, front-end snow is becoming increasingly likely, there is considerable model uncertainty with the placement of a comma head area of snowfall as a secondary low pressure system develops offshore (in a Miller B type evolution). If the comma head sits over central PA Sunday night, several additional inches of accumulation are possible. However, if it misses us to the north and we see more of a dry slot, that would result in snow ending sooner Sunday evening with less accumulation overnight.

All in all, the probability of snowfall amounts exceeding 12inches has increased to 60-80 percent across much of central PA. The probability of more than 18 inches ranges from 15 to 40 percent. Amounts near 24 inches can`t be ruled out (10 percent chance) especially if the comma head sits over central PA Sunday night. Always prepare for the worst case scenario and continue to check the forecast as it evolves. Now is the time to prepare. Think snow blowers, re-arranging travel plans to avoid travel during the storm, what to do in case of a power outage, etc. Remember it will be very cold before, during and after the storm. Never run a generator indoors due to carbon monoxide.

Now if you really enjoy meteorology and want to know *why* we are predicting the most significant accumulations.

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

2 questions with winds this high and temps in the teens and heavy snowfall why isnt the blizzard word being used? also 2 is the storm lasting longer then earlier model runs from today last night? saw 2 diff models in videos today showing snowing monday afternoon till 4 instead of wrapping up like 2am 

[Yardstickgozinya]

32 minutes ago, Ruin said:

2 questions with winds this high and temps in the teens and heavy snowfall why isnt the blizzard word being used? also 2 is the storm lasting longer then earlier model runs from today last night? saw 2 diff models in videos today showing snowing monday afternoon till 4 instead of wrapping up like 2am 

Well, I'm not trying to be a dick, buddy. but a lot of these guys here aren't going to take kindly to the back and forth between me and you with a event of this nature coming into the short range. I don't know exactly what defines a blizzard but at this point the national weather service is either not seeing or are anticipating we meet the criteria. Furthermore if they are going to put out a blizzard warning, they have to be confident that they know where the criteria will be met. Once that's pinned down., maybe we'll see something like that somewhere. As far as duration  no one can give you an accurate answer on that yet with this particular storm. 

[Ruin]

29 minutes ago, Yardstickgozinya said:

Well, I'm not trying to be a dick, buddy. but a lot of these guys here aren't going to take kindly to the back and forth between me and you with a event of this nature coming into the short range. I don't know exactly what defines a blizzard but at this point the national weather service is either not seeing or are anticipating we meet the criteria. Furthermore if they are going to put out a blizzard warning, they have to be confident that they know where the criteria will be met. Once that's pinned down., maybe we'll see something like that somewhere. As far as duration  no one can give you an accurate answer on that yet with this particular storm. 

I know for a blizzard criteria temps in the teens and winds higher then 20 mph mostly it doesnt depend on heavy snow but high winds and temps in the teens. atm my high is now only 15 this would bring me to 20-1 ratio which during yesterday was said to be a stretch we would be in the mid teens during the snow they were looking at temps 18-20 yesterday but ty for the reply 

[Caveman]

1 hour ago, Yardstickgozinya said:

Well, I'm not trying to be a dick, buddy. but a lot of these guys here aren't going to take kindly to the back and forth between me and you with a event of this nature coming into the short range. I don't know exactly what defines a blizzard but at this point the national weather service is either not seeing or are anticipating we meet the criteria. Furthermore if they are going to put out a blizzard warning, they have to be confident that they know where the criteria will be met. Once that's pinned down., maybe we'll see something like that somewhere. As far as duration  no one can give you an accurate answer on that yet with this particular storm. 

 

39 minutes ago, Ruin said:

I know for a blizzard criteria temps in the teens and winds higher then 20 mph mostly it doesnt depend on heavy snow but high winds and temps in the teens. atm my high is now only 15 this would bring me to 20-1 ratio which during yesterday was said to be a stretch we would be in the mid teens during the snow they were looking at temps 18-20 yesterday but ty for the reply 

From the National Weather Service...

Blizzard Warning

A Blizzard Warning means that the following conditions are occurring or expected within the next 12 to 18 hours.
1) Snow and/or blowing snow reducing visibility to 1/4 mile or less for 3 hours or longer
AND
2)  Sustained winds of 35 mph or greater or frequent gusts to 35 mph or greater.
There is no temperature requirement that must be met to achieve blizzard conditions.

[Voyager]

7 hours ago, Voyager said:

So this is what I have for a forecast. Question is, how much more Sunday night and Monday morning? They only show 8-14 through Sunday late afternoon/evening.

 

 

To answer my question, I just had to wait until this morning's update. Thy added in Sunday overnight accumulations, which gives me a range of 12-22 inches. Still mum on Monday's possible accumulations if it snows late into the morning.

Saturday Night

Snow likely after 1am. Cloudy, with a low around 8. Calm wind. Chance of precipitation is 70%. New snow accumulation of 1 to 3 inches possible.

Sunday

Snow. The snow could be heavy at times. High near 18. East wind 5 to 7 mph, with gusts as high as 22 mph. Chance of precipitation is 100%. New snow accumulation of 8 to 12 inches possible.

Sunday Night

Snow. The snow could be heavy at times. Low around 15. Chance of precipitation is 100%. New snow accumulation of 3 to 7 inches possible.

Monday

A chance of snow before 1pm. Mostly cloudy, with a high near 22. Chance of precipitation is 50%.

 

 

 

 

[pasnownut]

6z's starting off the day w/ good steps.

Icon pops secondary quicker and bring perty blues 40-50 mile SE with it.  Saves my ass from much taint.

Giddy up buttercups....

Yardsticks snippet from ctp also a thing of beauty.

Celebration of life service this morning

Celebration of snow rest of weekend.

 

[mahantango#1]

6 minutes ago, Voyager said:

To answer my question, I just had to wait until this morning's update. Thy added in Sunday overnight accumulations, which gives me a range of 12-22 inches. Still mum on Monday's possible accumulations if it snows late into the morning.

Saturday Night

Snow likely after 1am. Cloudy, with a low around 8. Calm wind. Chance of precipitation is 70%. New snow accumulation of 1 to 3 inches possible.

Sunday

Snow. The snow could be heavy at times. High near 18. East wind 5 to 7 mph, with gusts as high as 22 mph. Chance of precipitation is 100%. New snow accumulation of 8 to 12 inches possible.

Sunday Night

Snow. The snow could be heavy at times. Low around 15. Chance of precipitation is 100%. New snow accumulation of 3 to 7 inches possible.

Monday

A chance of snow before 1pm. Mostly cloudy, with a high near 22. Chance of precipitation is 50%.

 

 

 

 

Your forecast is almost identical to mine.

[pasnownut]

6z GFS also ticks S and has no taint except for extreme SE corner of Philly

really nice to see cold holding its ground, and not getttin bullied by primary.  

Just a thing of beauty.

 

[pasnownut]

0z euro also looks better.

Still has us SE'rs pingin for a bit, but pops secondary a tad quicker.

Theres not a model I wouldnt sign for.

NMB's snow maps gotta look great right now.

 

[Yardstickgozinya]

She's starting to come together.

[MickeyTim6533]

so the storm is over by Sunday night? seems quick

[Yardstickgozinya]

This is where I start getting giddy, quantifiable images. The gods are bowling

[mahantango#1]

ABC27 going on the lower side while my NWS is 15-22 snow

[Jns2183]

ABC27 going on the lower side while my NWS is 15-22 snow

After the epic storm drought we've had I think it would take us getting less than 7" for me to feel slightly jibbed. I do think now we end up in the 12"-14" range much more than 16"-18" range it won't affect my enjoyment

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[Yardstickgozinya]

I find it interesting that nws did not update their forecast discussion yet this morning, This is unusually late. Waiting on additional data is my guess. 

[mahantango#1]

https://www.pennlive.com/news/2026/01/the-10-biggest-snowstorms-that-buried-central-pennsylvania-and-brought-life-to-a-standstill.html?utm_campaign=pennlive_sf&utm_medium=social&utm_source=facebook&fbclid=IwY2xjawPgNXFleHRuA2FlbQIxMQBzcnRjBmFwcF9pZBAyMjIwMzkxNzg4MjAwODkyAAEe8uNczIz0GM_C_nvs-_0eqQM5_t3bv-eBjl21ANo1i-ZxM25ap0BQuQK_QEY_aem_H6lPhQV8U1N4Kv3Z-Vo3tA

[mahantango#1]

3 minutes ago, Jns2183 said:

After the epic storm drought we've had I think it would take us getting less than 7" for me to feel slightly jibbed. I do think now we end up in the 12"-14" range much more than 16"-18" range it won't affect my enjoyment

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And theres still more time for this to change till Saturday night and Sunday. 

 

[Jns2183]

Someone made these from 00z model models

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[pawatch]

1 hour ago, Voyager said:

To answer my question, I just had to wait until this morning's update. Thy added in Sunday overnight accumulations, which gives me a range of 12-22 inches. Still mum on Monday's possible accumulations if it snows late into the morning.

Saturday Night

Snow likely after 1am. Cloudy, with a low around 8. Calm wind. Chance of precipitation is 70%. New snow accumulation of 1 to 3 inches possible.

Sunday

Snow. The snow could be heavy at times. High near 18. East wind 5 to 7 mph, with gusts as high as 22 mph. Chance of precipitation is 100%. New snow accumulation of 8 to 12 inches possible.

Sunday Night

Snow. The snow could be heavy at times. Low around 15. Chance of precipitation is 100%. New snow accumulation of 3 to 7 inches possible.

Monday

A chance of snow before 1pm. Mostly cloudy, with a high near 22. Chance of precipitation is 50%.

 

 

 

 

See what they done here. The map is only good till Sunday 7:00 pm they are cutting 12 hours of snow totals off their snow forecast.

Why??

[Burghblizz]

9 minutes ago, Jns2183 said:

Someone made these from 00z model models

Sent from my SM-X210 using Tapatalk
 

Really like that presentation. 

[Voyager]

25 minutes ago, pawatch said:

See what they done here. The map is only good till Sunday 7:00 pm they are cutting 12 hours of snow totals off their snow forecast.

Why??

Good question. Maybe they're a bit unsure of when accumulating snow ends. If they took that map to 1am, it would probably be 4-6 inches higher.

[Yardstickgozinya]

12 hours ago, Mount Joy Snowman said:

What’s your elevation over there? 

  Proximity fuse settings  ? 

[mahantango#1]

 

 

[southpark]

41 minutes ago, pawatch said:

See what they done here. The map is only good till Sunday 7:00 pm they are cutting 12 hours of snow totals off their snow forecast.

Why??

To toy with our emotions 

[pasnownut]

2 hours ago, MickeyTim6533 said:

so the storm is over by Sunday night? seems quick

most majors have a 24-27 hr window of snow. 

If that's what you call quick, your wife must really love you.

 

[MickeyTim6533]

geez, gfs at hour 228....wow

[AccuChris]

Excellent write up by NWS State College in their AFD:

“All in all, the probability of snowfall amounts exceeding 12
inches has increased to 60-80 percent across much of central
PA. The probability of more than 18 inches ranges from 15 to 40
percent. Amounts near 24 inches can`t be ruled out (10 percent
chance) especially if the comma head sits over central PA Sunday
night. Always prepare for the worst case scenario and continue
to check the forecast as it evolves. Now is the time to prepare.
Think snow blowers, re-arranging travel plans to avoid travel
during the storm, what to do in case of a power outage, etc.
Remember it will be very cold before, during and after the
storm. Never run a generator indoors due to carbon monoxide.

Now if you really enjoy meteorology and want to know *why* we
are predicting the most significant accumulations in the past
5+ years, feel free to read on through the remainder of this KEY
MESSAGE 2 discussion. We`ve had our fair share of cold snaps
this winter season, and tomorrow (Friday) will be no exception
after the next Arctic front pushes through. A large factor
driving all this cold weather has been the Polar Vortex
displaced from the North Pole, with a tendency for the vortex to
find itself over Hudson Bay and northern Quebec. With
displacement that far south, we`ve gotten plenty of cold air,
but it`s also nudged the storm track south of our area for many
of the recent events. If you`ve ever heard people say "it`s too
cold to snow", it`s not that it`s physically too cold to snow,
it usually just means that the storm track has shifted far
enough to the south that we end up under dry high pressure while
our temps are cold.

One key difference this time is the influence of a Pacific
storm, located off the coast of southern California this
evening, and a strengthening subtropical jet to its south. Over
the next 24 hours these features will cross the Baja Peninsula
of Mexico and then into Texas. Southwesterly flow out ahead of
this southern stream feature will pump warmer air into the Gulf
Coast and Southeastern US Saturday night into Sunday. At the
same time, a northern stream shortwave trough coming down from
western Canada into the Great Plains will bring a reinforcing
shot of cold air to the back side of the northern longwave
trough. The increasing temperature gradients will result in an
overall increase in wind speed aloft at jet stream altitude, and
an amplification of the northern stream trough and ridge. By
Sunday, the right entrance region of the northern jet and the
left exit region of the southern jet will align to produce
enhanced upward motion through the troposphere. Remaining
uncertainty in the forecast largely depends on the degree of
phasing of these two jets, the angle at which they align, and
how much amplification there is of the ridge out ahead of the
deepening trough.

The very cold air in place ahead of this system also plays other
crucial roles to increase impacts. At 00Z Sunday, model
consensus depicts a 1040+ mb high over New York State, which
only slowly moves northeastward across New England over the next
24 hours. The deep, cold blocking high to the northeast of a
winter storm is a textbook feature that supplies a stream of
cold air down the Alleghenies and provides a cold dome for
warmer, less dense air parcels streaming in from the southwest
to ascend over. That upward motion is key to production of
hydrometeors - in this case snow. And then there is the key role
that cold temperatures have on ice crystal habits. The so
called "dendritic growth zone" exists where temperatures are
between roughly 0F and 10F. Given low temperatures Saturday
night in the single digits, some spots might start off with a
DGZ that extends from the ground up 10,000 to 15,000 feet which
is pretty remarkable for a large synoptic storm in this region.
As long as the column saturates quickly enough, any snow that
falls late Saturday night and into early Sunday morning could be
very high ratio, fluffy, rapidly accumulating snow that
consists of many pristine dendrites (SLRs 15-20:1, could be
even higher if the column saturates faster but there is dry air
at low levels to overcome at onset). So after a few hours of
virga, accumulations have the potential to begin with a
vengeance in the predawn hours Sunday, especially from I-80
south.”


.

[Blizzard of 93]

Great write up by CTP. 

[Blizzard of 93]

If you want some extra Friday weather tracking fun, check out the 6z GFS for Next weekend…wow! 
The GFS & some other Op/ensembles have been interested off & on for another chance next weekend.

Oh  & there could be a Clipper around this Thursday that takes a decent track for us a little snow pack refresher.

Exciting times on here!

[Jns2183]

If you want some extra Friday weather tracking fun, check out the 6z GFS for Next weekend…wow! 
The GFS & some other Op/ensembles have been interested off & on for another chance next weekend.
Oh  & there could be a Clipper around this Thursday that takes a decent track for us a little snow pack refresher.
Exciting times on here!

Big Jan 96 vibes with the multiple storms and artic cold

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