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Strong Winter Storm Thursday

By now I'm sure you've heard a powerful winter storm is setting up for Thursday into Friday morning.  This next round looks to bring the most snow we've seen in any one sitting this winter.  While snows have been frequent for us they haven't exactly been heavy hitting.  This round looks to change that.  So why is it.

The biggest factor can be attributed to where this storm system is originating.  As we pointed out in our blog post from a couple weeks ago, 'Cold Releasing its Grip', the jet stream has been consistently set up from northwest running southeast across the upper midwest this winter.  This means the storms we've had this season have primarily come from Canada, originating over land and in colder temperatures.  Both, don't really allow for a high moisture event.



This one is different.  A storm system called a 'Panhandle Hooker'.  Yes, I see you giggling through your camera, that's the actual name.  Panhandle, is for the region it originates, down towards the Texas/Oklahoma panhandles. Hooker, for the hooking motion it has it it sweeps into the upper midwest.



This setup is far more favorable for higher moisture content due to the warmer airmass in which it develops, and also from the moisture from the Gulf of Mexico this system will pull up as it develops.  Below shows moisture (green) being transported north via the wind (blue arrows) about a mile above the surface.



Below shows an ensemble, or group of computer model outputs, showing the heart of the storm, or low placement, at various times.  This ensemble shows on Wednesday evening the storm starts developing over eastern Colorado and eventually the track bringing it up by Superior by Friday morning.  All the while rapidly intensifying noted by the three digit number next to the L.  The lower the number, the stronger the storm. The stronger the storm, the stronger the wind, and sometimes, the more the snow.


The individual colored markers (above) show one computer model output of where the heart of the storm will be.  The more scattered these markers are, the more variability there is in the forecast, which is not a good thing when you are forecasting. 

That means some changes will likely be seen as this situation plays out.  However, these changes will be relatively subtle and won't be enough to thwart the storm all together.  Here's how we have it playing out as of now.

So here's the Storm Tracker 6 Forecast.  Below shows Storm Tracker at sunrise, Thursday.  The warmer air is still sticking around to start this storm.  That should have an influence on what type of precipitation we see at the start.  A light freezing rain/sleet is possible to start.  However it won't last long and accumulations of both will be minor.



As the day goes on, that falling precipitation will help cool the atmosphere to change things over to snow.  The heaviest falling from late morning into early afternoon.  At times snow intensity could be as high as 1 to 1 1/2" per hour!



Snow will wrap up by evening.  However it's not the end of the storm even though it looks like it below.



Remember above we talked about the wind becoming stronger as the storm strengthens?  The storm is at it's strongest point as it exits, and that's when the wind will kick up from the northwest.

First let's talk about the amount of snow we'll see.  We've opened up the forecast with initial call for 4-8" of snow, likely most places in the higher end of that range.  Due to the warmer temperatures, this will be a wetter/heavier type of snow than what we've been used to.



Remember that variability discussed above, may make those numbers wobble just a bit as we get closer to the time of the event.  However, don't get hung up on how much snow we're calling for.  Because with the wind picking up, the net effect will be the same.  Blizzard conditions will be possible.

The graph below shows accumulated snow in two hour increments (dark blue) with wind speed (light blue) from Thursday morning to Friday morning.  Notice the disconnect from when the heaviest snow falls and when the strongest winds hit.  The strongest winds arrive Thursday evening and last into Friday morning, somewhere in the range of 30 to 45 mph.  This will be the point when blizzard conditions will be possible, despite this being a wetter type of snow that is harder to be blown around. 



Here's a look at expected impacts:
     -Heavy Snow Mid-day Thursday. (1"+ per hour)
     -Reduced Visibility, both from heavy snow initially, followed by blowing snow later.
     -Blowing/Drifting Snow Thursday evening - Friday morning.
     -Treacherous, if not impossible travel in spots.

Wind will finally ease after sunrise Friday.  It will take some time for conditions to improve too.  Following the storm, we are expecting a shift to a cooler regime.  A few subzero mornings will be possible into the weekend and beyond.

And remember, don't get fixed on the snow totals.  It doesn't matter if we get 6" or 12", the impacts from the wind will be about the same.  So while the forecast snow amounts may vary a little bit, the blizzard force winds will make that a moot point.  The only way we won't see blizzard impacts is if the snow never materializes, which doesn't look likely to happen.



Storm Tracker 6 Chief Meteorologist
Chris Kuball

 


Heat Advisory

IA AREAS AFFECTED: Adair; Adams; Appanoose; Audubon; Black Hawk; Boone; Bremer; Butler; Calhoun; Carroll; Cass; Cerro Gordo; Clarke; Crawford; Dallas; Davis; Decatur; Emmet; Franklin; Greene; Grundy; Guthrie; Hamilton; Hancock; Hardin; Humboldt; Jasper; Kossuth; Lucas; Madison; Mahaska; Marion; Marshall; Monroe; Palo Alto; Pocahontas; Polk; Poweshiek; Ringgold; Sac; Story; Tama; Taylor; Union; Wapello; Warren; Wayne; Webster; Winnebago; Worth; Wright
Expires: 7/22/2014 7:00 PM