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tombo82685

Potential winter storm threats

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HPC 7-day snow prob - want to see this increase as event nears. Also has 10% prob for day 6.

prbww_sn25_DAY7.gif

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2 minutes ago, Chubbs said:

HPC 7-day snow prob - want to see this increase as event nears. Also has 10% prob for day 6.

prbww_sn25_DAY7.gif

WPC day 7 position was pretty close to the benchmark.   Looked a couple of days prior to the day 6-10 target date, might have stretched it, but saw a couple of advisory level snows which was an improvement over yesterday.

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First and foremost there is always the caveat that verifying a forecast with a forecast can be a slippery endeavor.

I just wanted to illustrate the point (hopefully correct) of how the Euro starts getting the 500mb idea reasonably close at about 120 hours out.  This is the loop of the 500mb pattern valid on New Year's morning.  There is enough bounciness in features between 168hrs and 120hrs (that closed low in the eastern Pacific, the elimination of the -nao ridge, the switch from a ridge to a trof northwest of Hudson Bay, the emergence of that short wave over Montana to name a few) to show uncertainty or inconsistencies between these forecast runs.  Its easier for me to see this on the e-wall site (the times are messed up today there) with the Euro because of less runs and statistically its the most accurate model anyway.  This has been the approximate point (120hrs) for this cold season from my admittedly subjective look at most systems.  So at 120hrs the PNA ridge looks fairly solid as should the double short wave structure in central noam.  From there the uncertainty of their phasing or lack thereof (ukonline site at 144hrs had the most uncertainty at the base of the trof which reads like a phasing uncertainty) and the wild card of convection east of Florida is (Thank-you Captain Obvious) going to cause differences over the next few days.  More/faster convection the more the first low turns up the coast.  I believe this is why the 18z GFS went east as its convection fires about 12 hours later than the 12z ggem and its previous run.   To me it looks like its really about the secondary cyclogenesis as the trof digs and the primary (while providing the latent heat to increase the ridging) muddies the modeling waters and resolution of it all per se.

I'll be in vegetableville the next two days, so enjoy the ride.

index.gif.fa08661c05556f723d829b46b3b3a56f.gif

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I think best shot of something more than these little storms is when the pv gets out of here after jan 5th. Though, by then ptype issues could become an issue with more of a se ridge look.

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2 minutes ago, Heisenberg said:

Nothing like a 384 hour GFS run without a flake of snow in it during January

Even when we had a run with flakes on it, it still didn't materialize. 

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Low level cold will be underdone early next week, first ice threat of the year. 

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Weather gods can be cruel with -11 & 2 lows followed by 40's and rain at PHL.  Something to keep an eye on as eps mean is cooler than OP.  If storm continues to trend not as wound up it will be hard to scour out that antecedent airmass.   As Mitch alluded to could be icy to start at the least, maybe more.  Big cold shot to follow.

Screenshot_20180101-051130.jpg

gfs_mslp_pcpn_frzn_eus_29.png

gfs_mslp_pcpn_frzn_eus_29.png

gem_mslp_pcpn_frzn_eus_30.png

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2 hours ago, susqushawn said:

Weather gods can be cruel with -11 & 2 lows followed by 40's and rain at PHL.  Something to keep an eye on as eps mean is cooler than OP.  If storm continues to trend not as wound up it will be hard to scour out that antecedent airmass.   As Mitch alluded to could be icy to start at the least, maybe more.  Big cold shot to follow.

Screenshot_20180101-051130.jpg

gfs_mslp_pcpn_frzn_eus_29.png

gfs_mslp_pcpn_frzn_eus_29.png

gem_mslp_pcpn_frzn_eus_30.png

Look for the surface to trend colder, need the low to be week with this. 

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11 minutes ago, al79philly said:

Is -11 even possible at PHL?  That would tie the all-time record that was set in the 30s.

it's snow cover induced min and then some. Highly unlikely. 

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12z GFS weaker with the low which means less WAA and a light snow event versus a change to rain Monday. 

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Looks like after the big storm missed us this week it's cutter City the next couple of weeks. January may end up a cruel month for snow 

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Models still not backing off the cutters. We're down till about two weeks before the mizer's thaw. 

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21 minutes ago, Mitchg said:

Models still not backing off the cutters. We're down till about two weeks before the mizer's thaw. 

The euro backed off the cutter early next week. Instead of taking it to Wisconsin it takes it just south of the area but 850's are warm 

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Just now, Feb said:

The euro backed off the cutter early next week. Instead of taking it to Wisconsin it takes it just south of the area but 850's are warm 

On the EPS as well. This has looked like a case of the surface trending cold but upper air not so much. 

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EPS :wub::wub: :heatmiser: with the cutters. Day 8-9 cold shot looks much weaker leading to another cutter day 10 ish. 

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21 minutes ago, Mitchg said:

EPS :wub::wub: :heatmiser: with the cutters. Day 8-9 cold shot looks much weaker leading to another cutter day 10 ish. 

Trending farther south each run. Yesterday it had the cutter on Monday in Wisconsin. Now where is it? 

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1 minute ago, Feb said:

Trending farther south each run. Yesterday it had the cutter on Monday in Wisconsin. Now where is it? 

Yes it is, as it should due to the depth of the cold at the surface. The first low in the lakes just may do us in. My idea usually works for the surface but 850 may fry. 

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2 minutes ago, Mitchg said:

Yes it is, as it should due to the depth of the cold at the surface. The first low in the lakes just may do us in. My idea usually works for the surface but 850 may fry. 

Oh yea the 850's are torchy. But the low itself is much farther south than yesterday's runs 

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7 hours ago, Feb said:

Looks like after the big storm missed us this week it's cutter City the next couple of weeks. January may end up a cruel month for snow 

If you live in or near the big cities, it will be better for where Mitch's new job is.

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Just now, Feb said:

Oh yea the 850's are torchy. But the low itself is much farther south than yesterday's runs 

Hopefully it's adjusts south. I would have liked to see more of a trend down the last couple of ensemble runs. 

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