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The Mystical Month of February--Long Range Discussion


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4 minutes ago, LP08 said:

Bob's is right.  Mine is including more frozen as snow.  Its 2-4 then ice.

Regardless, it would be great for you guys to have snow on snow.  While I'm fringed for now, still like the trends and in truth just want snow in the MA, as i know eventually, I'll get mine.  We got a couple inches Mon night, so i cant complain.  

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25 minutes ago, Bob Chill said:

I'm not seeing the same thing as you? Do you have 3hr panels? 850s are retreating as the heavies move in. Looks like SN to ZR to me?

Hard to say without in between panels...but this is what I was seeing, and this is silly at this range but let's pretend its 6 hours away.  

EC1.thumb.png.ee0bec5513dfd764c20f9e0da36727ba.png

That was all snow...its close but the algorithm using temps at the end of the 6 hour period estimated snow, probably an isothermal profile.  

But look at the way the cooling at 850 stretches back to the SW, and when you look at the precip pattern on the next plot it looks like that is mirroring where the heavy precip is.  This is the kind of signature to me that indicates a thump where the heavy precip keeps the column cool and then as it ends we transition to ice. 

ec2.thumb.png.a723d5fabeeb1e4f4fe6857a5e65d2cc.png

The precip on this next panel indicates that towards the end of that 6 hour period the precip was pretty much over, just some spotty light precip around.  And the 850 line only moved to just north of the PA line...it could easily jump up there in a couple hours once heavy precip moves out.  Also...the heavy precip will be where the best cooling is and usually sets up along the WAA...once the WAA wins the precip shuts off..you almost never see that heavy area of precip SOUTH of the rain/snow line in this setup.  It's almost always just north and then you get the changeover and lighter precip.  

ec3.thumb.png.03151307d59e0f6fb99c63f16cd0784c.png

So somewhere in that second panel during the really heavy thump of precip it changes over...but my guess from the limited evidence is that wont happen during the heaviest precip...that as the precip moves out the temps will warm, but such an extreme thump as that woulid keep the column cool enough for a snow/sleet mix at least...and not freezing rain IMO until later.  Of course this is crazy for such range, and if you remove the extreme thump then all bets are off...but if the area does get that much precip in such a short time...near the boundary, its probably mostly snow/sleet, and less freezing rain.  

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28 minutes ago, stormtracker said:

It's a lot of ice. 

Those precip type plots use the average temperature over the period to estimate precip type, but if during the heavy thump temps are isothermal and just cold enough, which is what those maps hint at to me, it would be a mostly heavy snow thump to lighter freezing rain.  There was a storm in Feb 2007 with a similar temp/precip profile and I think the same happened.  It was warmer at the surface so I don't think heavy freezing rain was the concern but people didnt expect a big thump of snow but the heavy precip along the temperature boundary created enough cooling to keep the area mostly snow until the heavy precip moved out.    I could be wrong but that was the look imo.  

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@psuhoffman

I totally agree with your logic but even at onset 850s are hovering just below freezing. With southerly midlevel flow there can easily be warm layers at different levels or a fast retreat of 850s. In my brain the euro maps verbatim do make sense given the marginal column at onset and southerly midlevel flow. Of course discussing this level of detail is borderline insane because we'll get new things to worry, despise, or celebrate every 6-12 hours for many days to come. lol

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1 minute ago, Bob Chill said:

@psuhoffman

I totally agree with your logic but even at onset 850s are hovering just below freezing. With southerly midlevel flow there can easily be warm layers at different levels or a fast retreat of 850s. In my brain the euro maps verbatim do make sense given the marginal column at onset and southerly midlevel flow. Of course discussing this level of detail is borderline insane because we'll get new things to worry, despise, or celebrate every 6-12 hours for many days to come. lol

lol you're right verbatim its probably mix...but I bet more sleet than frz rain at those rates.  Actually if we actually got that much precip...like .75 in a very short period... I am just adding my "interpretation" that it would be mostly snow.  We see that all the time...the thump snow, my area got that in November, that kind of heavy precip will almost always flip the coin onto the cold side in marginal situations like that.  

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4 minutes ago, psuhoffman said:

Those precip type plots use the average temperature over the period to estimate precip type, but if during the heavy thump temps are isothermal and just cold enough, which is what those maps hint at to me, it would be a mostly heavy snow thump to lighter freezing rain.  There was a storm in Feb 2007 with a similar temp/precip profile and I think the same happened.  It was warmer at the surface so I don't think heavy freezing rain was the concern but people didnt expect a big thump of snow but the heavy precip along the temperature boundary created enough cooling to keep the area mostly snow until the heavy precip moved out.    I could be wrong but that was the look imo.  

I remember that storm, in fact it was Feb. 25, 2007.  And you're correct, it was an unexpected heavy thump of snow over several hours, on the order of 5-6" in fact.  Forecasts I think were calling for mostly ice and sleet, but we got a paste job.  The surface temperature was right around freezing with an isothermal profile I seem to recall hearing.  When the precip came to an end, we were just above freezing and got some light drizzle for awhile after the heavy snow.  Quite a neat event!

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5 minutes ago, Bob Chill said:

EPS is pretty decent for next week. Spread is big so no real details worth mentioning other than the majority of the members give us some frozen precip ranging from just a little or a very nice hit. 

Well it sounds like we have a week of tracking legit threats.  I'm just gonna leave it at that for now...

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22 minutes ago, Bob Chill said:

EPS is pretty decent for next week. Spread is big so no real details worth mentioning other than the majority of the members give us some frozen precip ranging from just a little or a very nice hit. 

There was a subtle uptick in hits day 9 after 0z had unanimous support for a cutter there. Not much signal yet but a noticeable trend away from the abyss. 

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5 minutes ago, psuhoffman said:

There was a subtle uptick in hits day 9 after 0z had unanimous support for a cutter there. Not much signal yet but a noticeable trend away from the abyss. 

Nice shift on the EPS rolling the PNA/EPO forward. Much better than last night and looks more like the GEFS now late in the run. I still think it's coming sooner rather than later but the stubbornness on the ens give me pause. Regardless, we'll have plenty to track over the coming days. If it gets really good after then great. If not, we'll keep figuring out how to get snow in jacked up patterns. 

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7 minutes ago, Bob Chill said:

Nice shift on the EPS rolling the PNA/EPO forward. Much better than last night and looks more like the GEFS now late in the run. I still think it's coming sooner rather than later but the stubbornness on the ens give me pause. Regardless, we'll have plenty to track over the coming days. If it gets really good after then great. If not, we'll keep figuring out how to get snow in jacked up patterns. 

in my mind, thats 50% of how we snow anymore.  Stable longwave favorable patterns have been modeled much, but are seemingly few and far between in the last few years.  Feels that way anyhow.

 

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14 minutes ago, Bob Chill said:

Nice shift on the EPS rolling the PNA/EPO forward. Much better than last night and looks more like the GEFS now late in the run. I still think it's coming sooner rather than later but the stubbornness on the ens give me pause. Regardless, we'll have plenty to track over the coming days. If it gets really good after then great. If not, we'll keep figuring out how to get snow in jacked up patterns. 

It feels like they are meeting in the middle. Gefs backing off blocking and shifting the trough north once it shifts east. Eps backing off getting stuck west. The look can work. Slight adjustment and it’s good. My only fear would be if the war pops back up then we would just be right back where we were weeks ago where any major amplified storm would cut.  

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