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Central PA - Late Dec 2019/Jan 2020


MAG5035
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Did anyone else notice a huge difference between the 10:1 snowfall map at 84 hours between Pivotal Weather and Tropical Tidbits with the 12z NAM? Pivotal is showing next to nothing up the Susquehanna and about 4 inches in my backyard while TT is showing 6-8 regionwide...

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5 minutes ago, Voyager said:

Did anyone else notice a huge difference between the 10:1 snowfall map at 84 hours between Pivotal Weather and Tropical Tidbits with the 12z NAM? Pivotal is showing next to nothing up the Susquehanna and about 4 inches in my backyard while TT is showing 6-8 regionwide...

It's the NAM ... ;) The different maybe zr-related? 

A look at the GFS shows more misery, really. psuhoffman has a terrific writeup over in the MA about why this storm seems to be evolving how it looks to be. 

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25 minutes ago, Voyager said:

Did anyone else notice a huge difference between the 10:1 snowfall map at 84 hours between Pivotal Weather and Tropical Tidbits with the 12z NAM? Pivotal is showing next to nothing up the Susquehanna and about 4 inches in my backyard while TT is showing 6-8 regionwide...

Was the map you were looking at the one that includes sleet? I saw output from the NAM depicting 1.5 - 2" of pure sleet. That would make a huge difference in the actual snow accumulation...

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5 minutes ago, Itstrainingtime said:

Was the map you were looking at the one that includes sleet? I saw output from the NAM depicting 1.5 - 2" of pure sleet. That would make a huge difference in the actual snow accumulation...

Yes it was. My bad I guess, but I wonder if we get much sleet or if it goes over to zr. Some in the Mid-Atlantic thread are growing more concerned about an ice storm.

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45 minutes ago, Voyager said:

Did anyone else notice a huge difference between the 10:1 snowfall map at 84 hours between Pivotal Weather and Tropical Tidbits with the 12z NAM? Pivotal is showing next to nothing up the Susquehanna and about 4 inches in my backyard while TT is showing 6-8 regionwide...

Probably a lot of sleet in central PA that some maps combine with snow and show bigger amounts than reality. A lot of sleet is a risk here with the mid level lows going so far north. That will rush mid level warm air in and change it from snow. A rule of thumb is to assume the snow maps are significantly overdone when the 850mb low goes NW of you. I learned that lesson the VERY hard way with the Valentines Day 2007 storm that had maps with 20” south of I-80 and in State College we were getting heavy sleet after maybe 4-5” fell (we had another 6” the next day from the coastal system). Always assume the mid level warmth is underdone in systems like these that cut to the west. 

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31 minutes ago, Voyager said:

Yes it was. My bad I guess, but I wonder if we get much sleet or if it goes over to zr. Some in the Mid-Atlantic thread are growing more concerned about an ice storm.

They should be concerned. Let me remind everyone that while it’s fun to browse other forums (I do it as well and have many good convos down there), but the MA is often vastly different to what’s happening here. 

“I read it somewhere so it’s happening” doesn’t necessarily apply.  I’d much rather be up here than down there for this event.  
 

 

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33 minutes ago, jm1220 said:

Probably a lot of sleet in central PA that some maps combine with snow and show bigger amounts than reality. A lot of sleet is a risk here with the mid level lows going so far north. That will rush mid level warm air in and change it from snow. A rule of thumb is to assume the snow maps are significantly overdone when the 850mb low goes NW of you. I learned that lesson the VERY hard way with the Valentines Day 2007 storm that had maps with 20” south of I-80 and in State College we were getting heavy sleet after maybe 4-5” fell (we had another 6” the next day from the coastal system). Always assume the mid level warmth is underdone in systems like these that cut to the west. 

Thanks! I guess I still have a lot to learn about this hobby. As for the VD07 storm, we were pretty much the same here as you were there, except for, perhaps, the mid 40's temp spike for an hour before the crash which is what caused the freeway mess down here.

 

 

7 minutes ago, pasnownut said:

They should be concerned. Let me remind everyone that while it’s fun to browse other forums (I do it as well and have many good convos down there), but the MA is often vastly different to what’s happening here. 

“I read it somewhere so it’s happening” doesn’t necessarily apply.  I’d much rather be up here than down there for this event.  
 

Absolutely.

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First happy hour run made me happy...and want a beer. 

As stated by many of us many times....with storms like this....small differences can make notably better (or worse) outcomes.  Plenty of time for more "adjustments". We are a couple more tics away from a primarily frozen event.  Surface LP came in a tad weaker which shows up in critical layers, as warm nose gets cut off a bit. 

;)

and this is just me looking for fun and to see what trends are showing.  No forecast whatsoever.  Thats MAG's job.

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4 hours ago, Voyager said:

Did anyone else notice a huge difference between the 10:1 snowfall map at 84 hours between Pivotal Weather and Tropical Tidbits with the 12z NAM? Pivotal is showing next to nothing up the Susquehanna and about 4 inches in my backyard while TT is showing 6-8 regionwide...

Tropical Tidbit's lumps sleet/ice into their 10:1 snowmap, which the NAM has a fair amount of. That's why you see really blown up snowmaps on that site in areas where p-type is potentially an issue... which btw I feel like every single significant winter event dating back to the beginning of last winter has had p-type issues. 

To add to that, the ICON p-type maps on TT is flawed a bit as well. There's only a conditional for snow and rain, not ice... so you won't see where there's mixing present on that one via the p-type map. 

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20 minutes ago, pasnownut said:

First happy hour run made me happy...and want a beer. 

As stated by many of us many times....with storms like this....small differences can make notably better (or worse) outcomes.  Plenty of time for more "adjustments". We are a couple more tics away from a primarily frozen event.  Surface LP came in a tad weaker which shows up in critical layers, as warm nose gets cut off a bit. 

;)

and this is just me looking for fun and to see what trends are showing.  No forecast whatsoever.  Thats MAG's job.

My expectations are 1-3". 

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24 minutes ago, MAG5035 said:

Tropical Tidbit's lumps sleet/ice into their 10:1 snowmap, which the NAM has a fair amount of. That's why you see really blown up snowmaps on that site in areas where p-type is potentially an issue... which btw I feel like every single significant winter event dating back to the beginning of last winter has had p-type issues. 

To add to that, the ICON p-type maps on TT is flawed a bit as well. There's only a conditional for snow and rain, not ice... so you won't see where there's mixing present on that one via the p-type map. 

Thanks MIke!

Just think how much accumulation we'd have every winter if sleet really was a 10:1 ratio...lol

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41 minutes ago, pasnownut said:

But man....if only they were.  

GFS is much the same....ridin the line gang.

Yes, we are on the line in the Susquehanna Valley on the 18z GFS. 

It will come down to temps in all layers of the atmosphere.

Reading gets 5 inches of snow while Harrisburg gets .5 of sleet on the 18z GFS. It is that close.

The short range models will give us a better idea over the next 2 days.

8978E8E4-E933-4D33-A71E-46E9A2737387.png

FE284CCE-6E10-45CE-8132-DE6D1BE5725C.png

22CB1FD3-8D2B-4AB0-B1AD-DE79FF098CB8.png

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@pasnownut & all snow hounds on here, Please take a look at the 18z GFS !

It delivers snow next weekend around the 25th with a Miller B storm & then delivers a Miller A a few days after that. If this dream scenario unfolded as shown, we would suddenly all be ahead of our pace for our season average snow by the end of January. 

The upcoming pattern supports cold with an active storm track, so hopefully this fantasy run has the chance to become a reality. We will know for sure in 2 weeks...

F17D24AB-F346-47A5-8A8F-AE4C31F0888D.png

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Looking over the 18Z Nam I see it showing a snow to sleet storm and then ending before 7pm Saturday evening.  No rain as surface remains below freezing before, during, and then after the storm passes.  This seems to concur with the snow to sleet storm the GFS painted over us as well.  It would be great to reach 2" of snow before the mix/changeover.  My guess is there will likely be a nice burst of heavy snow for the first several hours before the mix.  One thing the GFS shows is temps will be no warmer than the 30's through the end of the run with 20's for highs for quite a few of the days.  

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22 minutes ago, Itstrainingtime said:

If I could do it all over again (and I said earlier today that I'm not) I'd go 1-3"...and I really think 3" is a stretch. 

A couple of inches of snow packed down by sleet & a little freezing rain followed by a cold week is fine for me.

Then, hopefully it will be time to go big game hunting for a significant snowstorm the last week of the month!

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6 minutes ago, pasnownut said:

Keep wishing it away and you may end up right.....but no it didnt

 

C86BC45B-63CD-4650-B732-9F2E43D8075A.png

I'm not wishing it away. I actually want this one, which is why it's upsetting to see the numbers go down. Earlier, I was told that those 10:1 maps that include sleet were wrong, and I should be looking at positive snowfall change, which is what I did. Pivotal's maps are much lower than what that TT map is showing.

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