Wednesday, December 19, 2012

December 19-22 Blizzard NowCast (12/19)

**This post is dedicated to Olivia Engel, age 6, a victim of the Connecticut shootings.**

Surface analysis across the nation shows that our storm system has now ejected from the Plains and is on its way to moving across the Midwest. We already see a wide precipitation shield spread out across the Plains in the presence of this storm system and another disturbance latched onto the north side of this storm system. Blizzard conditions have already been reported in many areas across Kansas and Nebraska in response to this storm's presence in the Plains at this time.

The wide array of winter weather bulletins shows us just how intense this storm system is. We have winter weather advisories in purple, and those stetch from the Front Range in Colorado to central Ohio. Dark blue colors represent Winter Storm Watches, which now only appears valid for the Chicagoland area. Pink implies a Winter Storm Warning, and this is where we will see good accumulations above 6 inches. The reddish shading is the fearsome Blizzard Warning, combining heavy snow and very high winds to make this event a big one, and one worthy of blizzard warnings.

This snowfall forecast fresh off the presses from the 18z GFS shows that accumulations well above 12 inches are likely to fall in southwest Wisconsin and east Illinois as the storm meanders on through. If such a development came true, travel would be paralyzed in cities in this region. Howling winds would not help the snowplow's efforts to keep the roads cleared.

Another, more high resolution graphic from the NAM model shows amounts significantly lower than the GFS is showing. I can't say I have a preference for either based on these single model runs, but if I were to pick one model, I would side with the GFS for its consistency and the definite likelihood of such high snowfall amounts to verify.

Travel will be severely disrupted in many regions across the Midwest, particularly Wisconsin, Iowa, Nebraska and northwest Illinois. Again, very high winds will make travel difficult, and snow days are likely to happen upon these areas, especially Wisconsin and Iowa if the GFS verifies.

More updates as this situation develops.


1 comment:

Anonymous said...

We got clobbered here in Palmer Lake, Colorado, with about 10" of snow, that combined with 40+ mph winds at times that created drifts that in some places exceed 3 feet.