LATE WINTER STORM ARRIVES TONIGHT...
A quick hitting spring storm will bring a period of heavy wet snow to the northern half of the area late tonight into Monday. The potent storm currently centered over the Plains will send a surge of energy and moisture into the region by daybreak. Temperatures will initially be warm enough for rain but with the dynamic cooling the rain will change to snow (perhaps mixed with sleet for a time) near and north of I-80. The area at risk for the greatest accumulations is approximately HWY 30 north, especially in Iowa where some 4 to 6" totals are suggested.
Here are the warnings and advisories currently in effect. These could still change if conditions warrant overnight.
One model that brings an interesting twist to the table is the HRRR. Since Saturday, its been consistently colder with the storm which increases snow totals and brings accumulations further south in my area. The HRRR is a high 3-km resolution, hourly updated, cloud-resolving, convection-allowing atmospheric model. It is the most accurate high resolution model available with 2 million grid points. It deserves some respect and this is what it shows for snow totals.
Most of the other models keep that rain/snow line about 50 miles further north closer to I-80. I haven't had a lot of opportunity to use the HRRR but when I have its performed well. This will be a good test to see how it holds up against the other solutions. Here they are.
The 12K NAM
The Canadian GEM
This is the official NWS forecast which you can compare with the model output above.
I'm still a bit hesitant about how this all works out due to the transition from rain to snow. If its quick, the qpf is there for a sloppy 4-6" inches (maybe a few spots a bit more), mostly likely north of I-80. If things are slower, that will knock amounts down. Dry air and slight weakening could also have an impact. This is one of those situations where mesoscale parameters will play an important role in the outcome and models are not as adept in this type of role. About all we can do from here on out is wait, watch and adapt. If anything interesting shows up I'll let you in. Roll weather...TS
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