A powerful pacific storm system will impact the area starting later today and going through Friday with ice, showers/thunderstorms, strong winds and even snow toward the end of the event. The full image suite for rain, snow and ice is below, so read on for the full details...
A strong upper level low will move from northeast Colorado and into Nebraska by Tuesday. With the current situation, we will likely continue to see patchy dense fog mainly west of I-35 in western Iowa through this evening. As moisture profiles increase aloft, this will turn into a freezing drizzle risk across western Iowa starting this afternoon through late tonight. Then a complex of thunder-mix (sleet/snow/freezing rain) will lift north into much of west and central Iowa after midnight tonight through late Tuesday with PWAT values on the upper scale to produce moderate to at times heavy precipitation. This will be generally showers and thunderstorms further south and east. The areas suspect to ice will be across northwest Iowa and toward the north central part of the state where surface temperatures will hang around 30-32F for at least the first half of Tuesday. Despite temperatures eventually warming above freezing Tuesday afternoon, this will be an ice storm for some of you extending from southwest Minnesota and down into northwest Iowa where significant ice accumulations will be likely. In addition, strong southeast winds will increase across western Iowa this evening and quickly spread east into much of Iowa by Tuesday, sustained 15-30 MPH with wind gusts of 35-50 MPH expected. Later, this system will bring some light snow later Wednesday through Friday before slowly working east of the state by Saturday. The maps for rain, snow and ice are below.
The areas at greatest risk for significant ice accumulation does include Cherokee, Orange City, Sheldon, Spencer, Spirit Lake and Storm Lake. Total ice accumulations of 0.25"+ are expected in the orange shaded zones. Other areas will be prone to a glaze-0.25" across northern Iowa. Ice amounts of this magnitude with strong winds may lead to power outages in northwest Iowa.
Some mix is expected further south but temperatures will warm quickly so the primary precipitation type will be rain across southeast half of Iowa. Rainfall amounts of 0.5-1.5" are expected with the system for much of the state. Keep in mind that some of this will be in the form of mix and freezing rain further north as mentioned above.
We will get a small break in precipitation Wednesday as a dry slot sets in across much of Iowa but eventually snow will increase by Thursday through Friday as cold air works in on the backside of the storm system. I will continue to crunch numbers for this side of the forecast with a follow-up article expected later. Here is the probably for at least 1" of snow accumulation Wednesday night through Friday.
So, a very complex system will unfold later today through late week. Stay tuned to Iowa Storm Center.com for updates.
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