COLDEST MORNING OF THE WINTER FOR SOME...
A FRIGID START TO THE DAY...
For parts of my area, Wednesday morning is likely to be the coldest of the winter so far with temperatures that may fall into the range of 14 to 18 below zero in my northwestern counties. The region most likely to experience these extreme lows is near and north of I-80 where snow depths of 2-7" exist. The cold properties of the snow and very light winds by daybreak will allow the mercury to crash, especially in the low lying areas where cold air drainage becomes a factor.
This is what the EURO depicts for temperatures near daybreak. I suspect these are a few degrees too cold. However, notice how the worst of the sub-zero cold is contained within the deeper snow field. South of I-80 where snow cover is generally an inch or less, temperatures are a good 10-15 degrees warmer. Snow begets cold.
Despite very little wind, just a slight breeze creates dangerous wind chills. Where the coldest readings are expected, wind chill warnings are in effect until noon Wednesday in my Iowa counties near and north of HWY 30 where some chills to 30 below are likely. The rest of the region is under wind chill advisories for chills mainly in the 15 to 25 below category.
The EURO shows wind chills that look like this around 6:00am Wednesday. Again, I think these are a few degrees too low. Whatever happens, the numbers improve significantly by noon although the far north (near HWY 20) may retain chills a bit below zero all day. The south moderates to the 10-15 range.
Thanks largely to the snow cover, there will be a significant spread in temperatures Wednesday with highs ranging from about 8 in the north to 24 in the south. Skies will remain mostly sunny until late afternoon with the ridge just to the east. Winds start calm and then turn to the SW increasing to 10-15 mph in the afternoon.
AN UPWARDS BOUNCE:
Wednesday night with southwest winds blowing briskly ahead of another clipper and cold front, temperatures will rise or hold steady all night long allowing the days highs to occur at night. Thursday morning the cold front slips southeast exiting all of the area by afternoon. Before the cold air gets really established highs push freezing in the north and may touch 40 in the far south.
Thursday night as the cold deepens we go the other direction with lows of 5 below north to 8 above in the south. Wind chills get back into the nasty range of 20 below in the NW to zero far SE. The EURO shows this for wind chills to start the day Friday.
That's followed by highs in the 10 to 20 degree category north to south Friday afternoon. A fitting end to cold week.
THE WEEKEND AND BEYOND...
Overall the weekend looks to be uneventful with temperatures about what you would expect for the last weekend of January. That means teens and 20 Saturday and 20s to low 30s Sunday. In both instances the coldest readings each day will be in the north where snow cover hinders warming. With high pressure in control skies remain mostly sunny.
Monday and the first half of Tuesday next week, conditions continue dry as a warming trend gets underway that could spell 40s in the southern half of my area both days. The north won't get out of the low to mid 30s but there will be a a thaw with some melting snow.
The most intriguing part of the forecast comes the middle and end of next week when a significant trough develops over the southwest bringing moisture and our first chance at precipitation in over a week. This is a significant change in the overall pattern as you can see in the animation below. The big trough that's been situated over the east the past month is retrograding and moving into the west. That shuts down the northwest flow for a few days and allows a more moderate pattern next week.
As the energy ejects out of the southwest it develops a a series of impulses that could bring rain, snow, or a combination of both to my area Tuesday night into Thursday. It's all contingent on the eventual track of the energy but the ensembles are pointing towards a path that sends the rain snow line very close to the Quad Cities.
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One thing that's very different about this potential set-up is that instead of moisture starved clippers like recent events, the storm track in the coming scenario opens up the Gulf of Mexico and moisture will be plentiful. Water vapor levels (PWATs) are shown approaching an inch as far north as SE Iowa.
That's more than 3 times what's typical in early February.
With the details of how the energy phases far from certain, it's premature to gauge how much precipitation ultimately falls but for a couple days now amounts have vacillated between the moderate to heavy category. Here's what the GFS and EURO are depicting for total precipitation.
Snow forecasts have been rather erratic and are too far out to even dignify so for now I will let that sleeping dog lie. There has been a trend for more snow potential in my area than in previous model data but that could easily change in coming days. Models should be more reliable in the next 24-48 hours and then we'll get into that issue.
On that note, I'm wrapping this up like a burrito. Stay warm and have an enjoyable hump day. Roll weather...TS
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