https://www.youtube.com/watch?v=mgXDJbnk_Qo
After the first round of cold weather exits the area, we look ahead to the next system set to impact the area early this week. The GFS has been very consistent with just about everything with this storm over the past several days, which is the reason we are publishing this forecast earlier than normal. It is also of priority that we update frequently as state girls basketball is played in Des Moines this week. Look for forecasts to begin on those later tonight.
The two areas of low pressure that we are monitoring are a. low in Canada and b. surface low around the Rockies. The current thinking with this suggests that the precipitation will start as snow across the northern counties Monday night with an icy mix across the south. Warmer temperatures will move into the southern counties of the state that may change the precipitation there to all rain during the morning and early afternoon hours. Areas around the I-80 and US 30 corridors may see a rain, freezing rain or sleet mix for most of the morning hours and even into the early afternoon. Areas along and north of US 20 will be seeing light to moderate snow with possibly some sleet mixed in closer to US 20. The precipitation will change all to snow over the entire state Tuesday afternoon and into Tuesday night as the system moves quickly off to the east.
Currently the heaviest snowfall appears to be in the far north counties where a mixed bag of precipitation and rain may not occur. These areas will likely see a frequent light to moderate snow, possibly heavy at times. The GFS has been pointing to an enhanced band of precipitation in central Iowa, right in the middle of all of the types. We will be keeping a close eye on this as it could have an effect on the ice and snow totals across the area. While the title of the post does sound like pure madness, the overall accumulation of ice and snow is not expected to be all that great, with 3-5″ of snow the hotspot in the northern half of the state with 0.05″ to 0.10″ of ice in the southern end. However, as always, this will lead to travel difficulties across the area, and with girls basketball going on as mentioned above, could turn into a real mess.
Another thing of concern will be wind speeds and gusts on Tuesday afternoon. Sustained winds across the area will be in the 20-30 MPH range for most with gusts to 50 MPH. This, if combined with falling snow, will create very dangerous blizzard and white-out conditions across the area, adding to the list of hazards. Winds will still be breezy to windy before 3:00 PM, but things should peak at this time. Any snow that is falling will be blown around and cause difficulties. This will also need to be monitored as we get closer to Tuesday.
No alerts are out on this specific system this morning but some NWS offices in the state have discussed issuing products later today. Would not be surprised to see Winter Storm Watches in the beginning, later to be upgraded to Freezing Rain Advisories and Winter Weather Advisories. There is also potential for a Blizzard Watch if the winds above do occur, primarily in the north central part of the state. Make sure to follow all of the Iowa Weather Network automated social media accounts on Facebook and Twitter to get the latest National Weather Service watches, warnings, and advisories. We should have an update out later this afternoon and another one following in the evening. Stick with IWN for the latest updates!
(Forecast prepared 3/1/2015 at 5:30 AM CST by Lead Forecaster Henry Luker, Senior Forecasters Jeff Wilcox & Dan Herrstrom)