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Wintry February 19-21, 2020 Winter Storm

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Well, I would think with the heavy rates the snow depth chart would be a little better than this. Looks like the temperatures bottom out at 34 during the event.
Lol so it thinks it'll snow 5-9 inches in places(rates of 1-2 inch per hour at some points), but only accumulate an inch at most? Even I got an inch of accumulation this past event with borderline temperatures and I couldn't have gotten more than 1.5-2 inches of snowfall(with only 25 minutes of heavy snow).
 

GaSnowhound

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I’m no met and understand this my not be the usual setup but I’ll take suppression rt now too. May eat my words but im
yeah...I don’t like seeing that 5.5” rt over my house at this time. GFS needs to go easy on me......I’d settle for a fringe inch and being on N side for a cpl more runs. I firmly expect a N shift w precip field. Climb and history....
 

GaWx

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More climo to consider:

Here are the dates for which I've found a 3.5" plus official ATL snow and/or 1.5”+ sleet event since 3/1876 (39 of them or one every 3.5 years)(I counted only Jan 12 of the 1/12-14/1982 event and Feb 15 of the 2/12-15/1885 event for this second table) :


DEC: 2, 3-6, 11-13, 29

JAN: 1, 2-3, 7, 7-8, 9, 9-10, 12, 18, 18-19, 22, 23, 23, 26, 28, 29-30

FEB: 10, 11-12, 11-12, 12, 12-13, 14-15, 15, 15, 15-16, 17-18, 21, 23, 24-25, 26

MAR: 1, 2, 11, 13, 14, 24

Note the 9 bolded storms, which are within 6 days of Feb 20th. That is almost 1/4 of the storms just within days of 2/20! So, the point is that Feb 20th is in the midst of one of the most climo favored periods at ATL for a major snow or sleet, the last half of Feb.
 

Jon

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GFS Vort maps aren’t even anything that would make you drool over. You don’t need that wave in the SW to kick at all. It just needs to spark the fire with that piece from the southern branch and not get squashed out front. Really not that many moving parts here if we’re being totally honest. Really good look here. Really good View attachment 34358
You don’t need the SW ULL at all that’s true. But we never needed it, unless it was gonna kick and link with cold it’s worthless.

But what creates the SW ULL eventually means that the NS will be too flat and less elongated and “tip heavy” meaning it would have less of a chance to dig and go neutral, creating a bigger system.

Our best bet now, because of the SW ULL, is a light system... unless for some reason the modeling is missing out on some energy we have yet to see and I doubt it.

Edit: I will say the GFS is trending nicely with the main northern stream confluence just west of the lakes. This is a new and helpful development

Sent from my iPhone using Tapatalk
 
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I want this storm to continue trending south then when the NW trend happens correct back to the 18z GFS scenario of today. I will call it a winter for the next two winters if that was to happen almost 7 inches of snow at my house. 😂
Sorry for the wish casting above in the storm thread. I’m not good at the h5 maps and all that but just looking at the trend in where the snow is at its trended south over the past three runs and I think will continue to do that over the next few runs. Like many have said this is a go big or go home scenario in my opinion.
 

SnowNiner

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GSP discussion this afternoon. Comparison to last weekend's event seems to have weight. Light event probably at best.

The models continue to have some difficulty in handling the
situation Wednesday and beyond. There is better agreement with
pushing the front through and to our south on Wednesday, but
moisture and srn stream energy moving in the fast WSW flow aloft
really complicate the issue for the late part of the week. Problem
is, the guidance also shows a cold continental high pressure air
mass that drops down into the Plains/Midwest/OH valley Wednesday
and Thursday, such that thickness drops down into the wintry precip
range. The new ECMWF has a deeper eastern upper trof and suppresses
any precip far enough south that we would remain cold but dry. Not
so with the operational GFS, which has the nrn fringe of the precip
along the old stalled front up into the cold air across the fcst
area Wednesday night and Thursday morning. The 12Z GEFS has some
form of wintry precip somewhere in the fcst area in about 2/3 of
the ensemble members...hardly a sure thing, but nothing to write
off either. If it were to happen, it might be an unusual event in
that the srn parts of the fcst area might stand a better chance at
some light accumulation than the nrn parts because of where the
precip would fall, sort of like what happened with the system we
had this past Saturday. Fortunately, precip amounts look modest
right now, so at this time it does NOT appear have the makings of
a significant winter storm. The forecast remains conservative with
the temps...about five degrees below normal but on the top end of
the guidance envelope...and tries to remain conservative with the
precip chances as well...limited to the chance range. Hopefully
the next several runs will give more clarity. For now, we will not
mention it in the HWO. We should end the period with cool and dry
high pressure for next Friday.
 

GaSnowhound

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More climo to consider:

Here are the dates for which I've found a 3.5" plus official ATL snow and/or 1.5”+ sleet event since 3/1876 (39 of them or one every 3.5 years)(I counted only Jan 12 of the 1/12-14/1982 event and Feb 15 of the 2/12-15/1885 event for this second table) :


DEC: 2, 3-6, 11-13, 29

JAN: 1, 2-3, 7, 7-8, 9, 9-10, 12, 18, 18-19, 22, 23, 23, 26, 28, 29-30

FEB: 10, 11-12, 11-12, 12, 12-13, 14-15, 15, 15, 15-16, 17-18, 21, 23, 24-25, 26

MAR: 1, 2, 11, 13, 14, 24

Note the 9 bolded storms, which are within 6 days of Feb 20th. That is almost 1/4 of the storms just within days of 2/20! So, the point is that Feb 20th is in the midst of one of the most climo favored periods at ATL for a major snow or sleet, the last half of Feb.
Larry,

ive spoken to you intermittently over years. You and Perry (May he Rest In Peace) are two of the greatest statisticians re weather I’ve ever encountered. We’re blessed to have you. Do you recall the event in Jan ‘01 that lasted nearly 24 hrs?? If I recall we had a nice 12 hr evening/night w ULL plowing thru late next if morning....out here in Social Circle we did extremely well if I recall and it was a seemingly disjointed affair throughout. Almost an I 20 special in some respects.
 

ryan1234

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GSP discussion this afternoon. Comparison to last weekend's event seems to have weight. Light event probably at best.

The models continue to have some difficulty in handling the
situation Wednesday and beyond. There is better agreement with
pushing the front through and to our south on Wednesday, but
moisture and srn stream energy moving in the fast WSW flow aloft
really complicate the issue for the late part of the week. Problem
is, the guidance also shows a cold continental high pressure air
mass that drops down into the Plains/Midwest/OH valley Wednesday
and Thursday, such that thickness drops down into the wintry precip
range. The new ECMWF has a deeper eastern upper trof and suppresses
any precip far enough south that we would remain cold but dry. Not
so with the operational GFS, which has the nrn fringe of the precip
along the old stalled front up into the cold air across the fcst
area Wednesday night and Thursday morning. The 12Z GEFS has some
form of wintry precip somewhere in the fcst area in about 2/3 of
the ensemble members...hardly a sure thing, but nothing to write
off either. If it were to happen, it might be an unusual event in
that the srn parts of the fcst area might stand a better chance at
some light accumulation than the nrn parts because of where the
precip would fall, sort of like what happened with the system we
had this past Saturday. Fortunately, precip amounts look modest
right now, so at this time it does NOT appear have the makings of
a significant winter storm. The forecast remains conservative with
the temps...about five degrees below normal but on the top end of
the guidance envelope...and tries to remain conservative with the
precip chances as well...limited to the chance range. Hopefully
the next several runs will give more clarity. For now, we will not
mention it in the HWO. We should end the period with cool and dry
high pressure for next Friday.
GSP has always been conservative, as they should. I also wouldn't call it a "light event" either. Anything above 4 inches is considered substantial for our areas.
 

GaWx

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Larry,

ive spoken to you intermittently over years. You and Perry (May he Rest In Peace) are two of the greatest statisticians re weather I’ve ever encountered. We’re blessed to have you. Do you recall the event in Jan ‘01 that lasted nearly 24 hrs?? If I recall we had a nice 12 hr evening/night w ULL plowing thru late next if morning....out here in Social Circle we did extremely well if I recall and it was a seemingly disjointed affair throughout. Almost an I 20 special in some respects.
You mean 1/2-3/2002, right?
 

GaSnowhound

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You are likely correct. Been a minute😁
My point was could this type set up favor a similar event? Rarely do we have a scenario that favors extended events and I was wondering if that se hangs back out west we might fare well as impulse train thru in a cold hp boundary scenario?? Am I thinking rationally or missing the whole concept given modeling at present?
 
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