Winterstorm 2/13-2/14: NE, IA, IL

[jshields]

the next in a series of strong storm systems will move rapidly from the southwest U.S. tomorrow, to across Kansas, central Missouri and Illinois on the 13th and 14th. the gulf will again be wide open so available moisture will not be a problem. temp profile shows very favorable conditions in the dendritic region, a strong 700 mb low that tracks across the KS/NE border and MO, IA border to northern Illinois. also with strong mid level frontogenesis, and some instability so thundersnow will also be possible. forecast qpf is .50" to .90" and with somewhat lower snowfall ratios a broad area of 4-10" of snow should be likely along the southern half of Nebraska, Iowa, and northern Illinois. Areas that receive thundersnow could top 12+ inches!! also strong northeast and then north to northwest winds of 20-30 mph will cause probs with blowing and drifting and visiblilty. Winter storm watches have been issued thus far across Nebraska and western Iowa thru Friday evening but will be extended eastward as time goes on. the length of snowfall in any one place will be around 12 hours or less so high snowfall rates will be needed and are likely with the strong dynamics of the system to reach the forecasted amounts.

 

[Dustin Wilcox]

Extremely narrow band of intense snowfall rates will setup across much of NE/IA and points E. For quite some time (several runs now) the models of been in remarkable agreement with the heaviest band riding the US Hwy 30 corridor and points JUST South across C and E NE. Doesn't appear to be anything crippling and should be in and out rather quickly, though areas with in that really narrow band could see a quick 8-10" and given the relatively "quiet" winter season across the E NE area so far this year, it will likely shut a lot of things down...

 

[jshields]

the 0Z runs of the gfs and nam are in and the gfs is further south placing the heaviest band of precip mainly south of I-80 through nebraska and iowa on friday. the nam is further north placing the higest qpf along and either side of I-80 and it also about 6 hours slower keeping at least moderate snow through 06Z on saturday. prior to this run the nam was also lighter in its amounts but now seems to be a little heavier than the gfs. still looking at 6-10" with higher amts possible across the area

 

[Darren Addy]

Looks like a predicted bulls-eye of precipitable water between Kearney & Grand Island, NE of .70-.79 (inches). That would be a minimum of 8" of snow (I believe). We're also going to be on the NW quadrant of the low as it moves through NE Kansas. I think I need to take a toothbrush to work with me tomorrow, because it is gonna be piled up by 5 PM.

 

[Anthony Petito]

NWS is holding conference calls with local METs about thundersnow possibilities in some areas. Could push up snow totals in a few localized areas.

 

[jshields]

hey anthony- just curious, but was that the valley nws that was holding the discussion or several of the local/regional offices? i'm kindof surprised bc according to valley earlier this morning they were talking about the models coming in less supportive of very heavy snows and and also showing no instability. that was in the 4 am discussion. i checked the 12Z models earlier this morning and they were also showing that. maybe the new models are in and have trended back towards more instablility tomorrow?! the homepage for eastern ne/western iowa does show a snowfall forecast graphic with a bullseye of 8+ inches just west of the omaha metro tomorrow. it would be pretty cool to get some thundersnow tomorrow and hike up those snowfall totals

 

[Anthony Petito]

I'mnot sure if was directly the Valley office or a combination... There has been up updated discussions posted to the NWS site, currently only the 0500 report is up there. The same page you're seeing the expected snowfall totals (along with the 8+ inches just west of OAX) also has a link to a PDF they gave to media orgs about the storm. Unfortuantely, there is no mention of thundersnow/instability with this storm in that discussion.

 

[Darren Addy]

OAX forecast discussion posted at 3:55 pm on Thursday the 12th is pretty descriptive.

Currently still showing a good area of .70 precip. water farther west. Be interesting to see what GID says later as I think their CWA is going to be hit at least as hard as Omaha's. Earlier they were saying 12:1 ratio, but at 15:1 the .70 figure gives you 10.5".

 

[jshields]

thanks for the reply! i did see the updated afternoon forecast discussion on the homepage, and its definitely different than this mornings coversation. it appears the models are under forecasting the strength of the low based on the upper air and surface obs of the low currently out in the southwest us. it mentions that the latest runs of the gfs and nam show both negative lapse rates and epv tomorrow pointing to slantwise or even upright convection. with that being said, a broad 6" snowfall is likely, and if convection develops using the cobb method outputs 8-12+" of snow along and either side of the I-80 corridor. winter storm warnings are now up for most of nebraska and into western iowa.

 

[Joel Wright]

This was once looking like quite a formidable little storm system, but the models are eating it away with every cycle. The weakening trend in the models began a few days ago, and has been declining since. It's been kind of like watching a balloon slowly deflate LOL.

Still looks like 3-6" could fall out in Nebraska before the storm craps out. By the time you reach the Mississippi River amounts look to tail off into the 1-3" range.

00z GFS has yet to come in, but the updated NAM/GEM indicate the weakening trend continues.

 

[Darren Addy]

Wow. Where did all the predicted moisture go?
QUANTITATIVE PRECIPITATION FORECAST DISCUSSION now says

RATHER CHANNELED
VORTICITY AND WEAKENING 85H CIRC WOULD SEEM TO SUPPORT A RATHER
NARROW AREA OF .25 INCH LIQUID AMOUNTS ACRS SRN NEB/SW IA INTO
EXTREME NRN KS/NW MO.

That's about 1/3 of the QFP than they were forecasting 24 hrs ago.

 

[Chris Fitzgerald]

They lowered snowfall totals here to 1-2 inches here with the heaviest snowfall totals south of highway 34.

 

[Brad Nelson]

The problem, to me, seems to be that this is a fast moving system of Pacific origin. Looks like it did not have any time to tap into any sort of Gulf moisture.

The 12Z NAM is coming in even drier for eastern IA and IL for this evening. Nice storm for Nebraska and western Iowa though! I see as of 8:30am Lincoln had 6" on the ground and Custer had 7". Some good 1"+ per hour snow going on in some of the heavier bands.

 

[Dustin Wilcox]

Heavist band has setup directly over head now, in fact I am smack dab in the middle of the highest return any where. Would guess we are seeing rates of close to 2" an hour right now. Started snowing not that long ago and we're already around 3". No thunder that I have noted as of yet.

 

[jshields]

here in omaha, it started snowing just before 9 this morning, and we are already up to 3". the snow lessened up for a little while but has started to come down harder again. looking at the radar there is still a larger area of moderate to heavy snow all the way back to at least Grand Island, NE, but the returns have started to shift pretty quickly east. i'm guessing snow will be done here by 6pm. one other note, the north platte regional airport was still reporting moderate snow as of 10:53 this morning, but radar returns looked fairly weak in that area, so decent snowfall might be all the way back to north platte despite what the radar is showing also, there was a 10" report of snow near broken bow out in western nebraska.

edit: report of thundersnow in western omaha a few minutes ago about noon!