showmethesnow Posted November 11, 2018 Share Posted November 11, 2018 Seeing as we have an event (see possible snow/frozen) that will be impacting our region in under 5 days (under 4 for southern portions) I thought it might be time to pull out the discussion from the mid/long range to keep the clutter to a minimum. We have seen the latest GFS now come in with a quicker onset and it is even more gung-ho for our possible system which now is projected to impact our region from late Wed through Thur. At this point it looks as if the western burbs have the best shot at seeing snow though the latest run looks as if it is attempting to put the cities in play for some snow/frozen in the air. 00Z GFS snowfall Kuchera 06Z GFS snowfall Kuchera 3 Link to comment Share on other sites More sharing options...
showmethesnow Posted November 11, 2018 Author Share Posted November 11, 2018 Looking at the above snow maps and why we are seeing a ramp up of frozen on the latest run (06z vs 00z) I think the major reason is that we are seeing a 6 hour earlier onset of precip compared to the previous run. This means we are seeing the precip moving in during the overnight hours of Wed night vs the 00z which had it moving in during the morning hours of Thur. So we are not seeing the influence of solar until later in the storm. Link to comment Share on other sites More sharing options...
showmethesnow Posted November 11, 2018 Author Share Posted November 11, 2018 38 minutes ago, showmethesnow said: Looking at the above snow maps and why we are seeing a ramp up of frozen on the latest run (06z vs 00z) I think the major reason is that we are seeing a 6 hour earlier onset of precip compared to the previous run. This means we are seeing the precip moving in during the overnight hours of Wed night vs the 00z which had it moving in during the morning hours of Thur. So we are not seeing the influence of solar until later in the storm. Now looking at the 850's (may be a sneaky warm layer somewhere but far too soon to worry about that) on down everything looks fine until we reach the surface. Now below we have the surface temps for the beginning of the storm on the 00Z GFS. These are the temps for the beginning of the storm on the 06Z GFS. Notice we are seeing a 3-4 degree difference through the cities and a 1-2 degree difference in the western/northern burbs. Now these are the surface temps mid way through the storm on the 00Z GFS. Vs the 06Z run which has everything 2-3 degrees colder through the cities and burbs. The burbs are actually still flirting with freezing through this period of time. Now part of the temp difference could possible be attributed to the GFS picking up a little better on the CAD (cold air damming) as the models tend to pick up better on that as we get closer in time. But I think the main difference here is we are not getting the influence of solar until later in the storm with the GFS. Now one thing of note is that we lose the 850s midway through the storm on both runs. So on the 00Z run we are probably looking at region wide rain though the 925s are still good so depending on the depth of the warm air we could possibly see some sleet mixed in. The 06Z run on the other hand suggests the possibility of this turning into a sleet and/or ice storm for the north/western burbs as we see a healthy slug of moisture through this time. 1 Link to comment Share on other sites More sharing options...
showmethesnow Posted November 11, 2018 Author Share Posted November 11, 2018 The latest GEFS snowmaps have seen improvement as well. 00Z run 06z run 06z individual members 1 Link to comment Share on other sites More sharing options...
showmethesnow Posted November 11, 2018 Author Share Posted November 11, 2018 Now some of you may be wondering why the GEFS wasn't really picking up on the late wed/thur storm just a day or two ago. The reason why is the differences we are seeing at 500 mbs. Below we have yesterdays 6z run. Notice the placement of the pv rotating through eastern Canada. It is far enough south and west that we are seeing tightly packed isobars through the mid-Atlantic effectively creating a wall for any energy attempting to move up through the region. So in this setup any energy to our south has no room to amplify and is suppressed and shunted off to sea. Now this is the current 6z. What we are seeing is the pv is shifted farther east taking the wall of compressed height lines farther north and east allowing a much more relaxed flow through our region. This is allowing the enrgey to out south to amplify and move north. Though the EPS isn't as aggressive with the possible storm as the GEFS is we have also seen the same thing occur. 6 Link to comment Share on other sites More sharing options...
Stormpc Posted November 11, 2018 Share Posted November 11, 2018 Thank you SMTS for the informative posts. Something to watch. Your effort is appreciated. Let's bring it home. 1 Link to comment Share on other sites More sharing options...
Scraff Posted November 11, 2018 Share Posted November 11, 2018 Great write up @showmethesnow per the norm. Thank you! And with the possible NAO tanking, it seems it’s not really a question of its going to snow, just a matter of when. 1 Link to comment Share on other sites More sharing options...
showmethesnow Posted November 11, 2018 Author Share Posted November 11, 2018 1 hour ago, Scraff said: Great write up @showmethesnow per the norm. Thank you! And with the possible NAO tanking, it seems it’s not really a question of its going to snow, just a matter of when. If the current GEFS is more right then the EPS I would not be surprised if we have a couple/several short term tracking opportunities in the coming 16 days. But of course we would be fighting climo, not to mention the models do not remain static, so I guess we will see. Link to comment Share on other sites More sharing options...
NorthArlington101 Posted November 11, 2018 Share Posted November 11, 2018 12z ICON is a mixy mess as well. Shows heavy precip and below freezing temperatures throughout much of the area at the start of the storm. Too bad we can't see the other layers on TTT. Link to comment Share on other sites More sharing options...
showmethesnow Posted November 11, 2018 Author Share Posted November 11, 2018 14 minutes ago, NorthArlington101 said: 12z ICON is a mixy mess as well. Shows heavy precip and below freezing temperatures throughout much of the area at the start of the storm. Too bad we can't see the other layers on TTT. With the 1000-500mb line all the way up in upstate NY at onset not sure we really want to know what the upper layers look like. 1 Link to comment Share on other sites More sharing options...
LP08 Posted November 11, 2018 Share Posted November 11, 2018 1 hour ago, showmethesnow said: With the 1000-500mb line all the way up in upstate NY at onset not sure we really want to know what the upper layers look like. Fv3 is acceptable! Link to comment Share on other sites More sharing options...
Scraff Posted November 11, 2018 Share Posted November 11, 2018 19 minutes ago, LP08 said: Fv3 is acceptable! Hells yes! Lock it in!! 2 Link to comment Share on other sites More sharing options...
NorthArlington101 Posted November 11, 2018 Share Posted November 11, 2018 ICON took a huge step in the right direction. Faster and colder. Big snowstorm for November. This doesn’t include FRZA, which would certainly happen out my way as temps are below 0. 2 Link to comment Share on other sites More sharing options...
Bob Chill Posted November 11, 2018 Share Posted November 11, 2018 11 minutes ago, NorthArlington101 said: ICON took a huge step in the right direction. Faster and colder. Big snowstorm for November. It's a perfect ULL pass. That's what caused the unexpected vet day storm in the 80's. I'm very skeptical of this working out anywhere near the cities but if something is going to happen then this panel is how to do it. 4 Link to comment Share on other sites More sharing options...
AfewUniversesBelowNormal Posted November 11, 2018 Share Posted November 11, 2018 This one might actually start as snow/mix What a healthy cloud pattern Link to comment Share on other sites More sharing options...
NorthArlington101 Posted November 11, 2018 Share Posted November 11, 2018 18z GFS much more tame than the ICON -- still suggests first shot at flakes but it would be in the form of an initial wintry mix to rain. Link to comment Share on other sites More sharing options...
MJO812 Posted November 11, 2018 Share Posted November 11, 2018 Congrats on the para gfs Link to comment Share on other sites More sharing options...
Bob Chill Posted November 11, 2018 Share Posted November 11, 2018 16 minutes ago, Snow88 said: Congrats on the para gfs Too bad the snow map algo is whacked and magically turns cold rain into snow. I'll enjoy the sleet at onset tho 1 Link to comment Share on other sites More sharing options...
Chris78 Posted November 11, 2018 Share Posted November 11, 2018 5 minutes ago, Bob Chill said: Too bad the snow map algo is whacked and magically turns cold rain into snow. I'll enjoy the sleet at onset tho Yes I noticed that. It's way way off. Even for clown maps it's really misleading. 1 Link to comment Share on other sites More sharing options...
yoda Posted November 12, 2018 Share Posted November 12, 2018 1 hour ago, Bob Chill said: Too bad the snow map algo is whacked and magically turns cold rain into snow. I'll enjoy the sleet at onset tho I'll take the 18z ICON and a side of 18z FV3 to go Though we already know the snow charts suck lol Link to comment Share on other sites More sharing options...
Chris78 Posted November 12, 2018 Share Posted November 12, 2018 8 minutes ago, yoda said: I'll take the 18z ICON and a side of 18z FV3 to go Though we already know the snow charts suck lol The icon snow maps atleast match up to the surface precip type and temp maps. Actually I noticed last winter that the icon snow maps were the most conservative and reasonable lol. The Fv3 isn't even close to reality. Link to comment Share on other sites More sharing options...
WxUSAF Posted November 12, 2018 Share Posted November 12, 2018 ICON calculates snow ratios directly in the model, so what’s shown on TT is not using a post-processing algorithm. It’s still not going to snow 8”. 1 Link to comment Share on other sites More sharing options...
yoda Posted November 12, 2018 Share Posted November 12, 2018 Just now, WxUSAF said: ICON calculates snow ratios directly in the model, so what’s shown on TT is not using a post-processing algorithm. It’s still not going to snow 8”. True... but I'd take even 1/8th of it and call it a win lol Link to comment Share on other sites More sharing options...
smokeybandit Posted November 12, 2018 Share Posted November 12, 2018 Yeah a sloppy inch in November is always a win Link to comment Share on other sites More sharing options...
NorthArlington101 Posted November 12, 2018 Share Posted November 12, 2018 If you like sleet and FRZA we got NAM’d. Link to comment Share on other sites More sharing options...
Chris78 Posted November 12, 2018 Share Posted November 12, 2018 1 hour ago, WxUSAF said: ICON calculates snow ratios directly in the model, so what’s shown on TT is not using a post-processing algorithm. It’s still not going to snow 8”. That makes sense. I didn't know that. Thanks for the info. Id be shocked if it even snowed 1" but id gladly take it...lol Link to comment Share on other sites More sharing options...
NorthArlington101 Posted November 12, 2018 Share Posted November 12, 2018 ICON is still FRZA for most areas outside DC proper and SE (most likely) as surface temps are below 32. All snow for N MD and flips everyone to snow at the end. I’d lock it up. for posterity: Link to comment Share on other sites More sharing options...
poolz1 Posted November 12, 2018 Share Posted November 12, 2018 Gfs has at least slightly reversed the trend of slowing the ull down. A good sign imo... Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted November 12, 2018 Share Posted November 12, 2018 This seems to be a bit of a CAD setup. One truism is that low level cold is always under modeled and usually modeled too quickly to leave. 1 1 Link to comment Share on other sites More sharing options...
Chris78 Posted November 12, 2018 Share Posted November 12, 2018 The temps on the icon and fv3 are just crazy for Thursday. Keeps NW areas below freezing the entire day. Kind of HARD to believe for November 15th. Link to comment Share on other sites More sharing options...
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