MY GOSH, IS THAT SNOW I SEE...
Thursday in a post I mentioned that a clipper disturbance might catch the northeast parts of my area with some snow as it digs southeast. Recent runs have been digging and tracking the system further and further west and now it looks like the southwest half of the region has the best chances for snow and the northeast may miss out altogether.
This is where the NWS in Des Moines showed the highest threat of snow late Thursday. Well, things change and now we have a different scenario.
To give you an idea of how fast things change, this is what the afternoon run of the 3k NAM looked like for snow.
The night run just 6 hours later shows a significant push west of the heavier snow taking much of my area except the far south out of the snow band. I don't like to see swings like that at the last hour.
Having said that, the GFS is not as far west and shows this for accumulations.More of my area gets in on the act.but now its the southwest half of my area that gets most of the gold. The northeast is left holding the empty bag.
This is the culprit, a compact but potent piece of energy that is closed off at 500mb. It's likely to produce some nice lift in a narrow band just east of the upper lows track. Question is, where is it going?
The negative with this system is the lack of moisture. Most models depict liquid equivalents on the order of 0.05 to 0.20" where the heaviest snow falls. It falls into an air mass that should yield snow ratios of about 13:1. While that generally translates to totals of 1/2 to 2 inches in the primary swath, banding could squeeze out a couple 3" totals where forcing is maximized. If trends hold chances are that a winter weather advisory will be issued for some of my western counties, especially SW of a line from Waterloo to Cedar Rapids and close to the Quad Cities. The majority of the snow falls between 5:00pm and 4:00am Friday night as it spreads from northwest to southeast.
This is what the EURO shows for total precipitation.
This is what the latest EURO has for total snowfall.
To summarize, considering how late it is in the game there is still some doubt as to the exact track of the disturbance. A last minute shift in track 25-30 miles SW to NE is still possible so confidence is not as high as it normally would be. However, I think the best chances for an inch or two of snow is SW of a line from roughly Waterloo to Cedar Rapids and on close to the Quad Cities. I will have an update for you by mid to late morning. No issues before evening.
The snow moves out where it does fall by daybreak Saturday and the rest of the weekend looks quiet. Saturday will be chilly with seasonal temperatures around 30, especially where there is a snow pack. Sunday should be warmer as the next clipper tracks across Minnesota bringing a surge of southerly winds and about 10 degrees of moderation. More to come. Roll weather...TS
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