I'm using a new forecasting and imaging tool that I think you're going to like. It's called MeteoEarth, and it allows me to show you time-stamped snapshots of what our weather might look like at any given point in time. But before we get to the pretty new pictures, here's a quick glance at the next 4 days:
Saturday: Wintry mix early, then a break in precipitation, then evening and overnight snow.
Sunday: Gusty winds, cold, snow showers ending, blowing snow throughout the day, some clearing at night.
Monday: Very cold with snow developing late evening and overnight.
Tuesday: Snow ending by Noon, continued cold.
So that's two separate storm systems -- one coming from the southwest Saturday into Sunday, and another coming from Canada on Monday night.
I have to say this first about the weekend storm: it strikes me as nearly irresponsible that the National Weather service office out of Sullivan, WI has not issued any weather advisories for the southeastern half of the state. They still might, but with the mix of precipitation in the forecast and the real potential for travel hazards, they should have done it by now. Just sayin.'
OK, let's get to the detail...
The weekend storm is setting up just as I described it yesterday, with two exceptions: 1) precipitation Saturday into Sunday will fall in two rounds, not one, and; 2) the first round of precipitation may include sleet and/or freezing rain.
That first round starts tomorrow morning as the low brings warm and moist air up from the south. That warm air aloft will override the cooler air at the surface, causing rain to form in the upper atmosphere. But with temperatures still below freezing at the surface, that precipitation will fall as either sleet or freezing rain. Expect this first round of precipitation to essentially last from 6:00am to Noon Saturday. This snapshot from MeteoEarth shows the leading edge of precipitation coming from the south before sunrise tomorrow morning. (Remember you can click on any image to enlarge. Also note future time stamps in the upper right of the MeteoEarth images).
After that first batch of precipitation goes through, we'll get into a brief dry zone. Skies will remain cloudy and temperatures will fluctuate within only 2 degrees of freezing -- about 30-34 degrees. As the low passes to our east late tomorrow evening, snow will wrap in behind it, giving us a 6-9 hour period of light to moderate snowfall Saturday night into Sunday morning.
Here's the overnight image for early Sunday morning:
My snowfall prediction, 6pm Saturday to Noon Sunday: 3.1 inches. Totals will be higher to the northeast (Fox Valley area) and lower to the west/northwest (La Crosse area).
So far, I'm only seeing one projection that thinks there could be a heavier band of snow in southern Wisconsin.
That orange band over southern Wisconsin is showing an 80% probability of 4 inches or more by Noon Sunday. The same model suggests a 40% probability of 6 inches or more in that same period. As I mentioned yesterday, these types of storms often contain narrow bands of heavier snow, but they're nearly impossible to pinpoint geographically. So, I'm generally discounting the model above.
Behind that system comes the first of 3 shots of cold air that we'll experience in the next 5-7 days. This image from MeteoEarth shows strong north winds on Sunday, as indicated by the closeness of the isobars (or equal lines of barometric pressure):
That cold air gets reinforced again Monday, then again Tuesday night. Look for highs only in the single digits Monday and Tuesday, and perhaps barely reaching zero on Wednesday.
In between those arctic blasts will come a second snowstorm on Monday night. This "Alberta Clipper" will produce a prolonged period of light snow from about midnight Monday to Noon Tuesday. Other forecasters have snow starting earlier in the late afternoon or evening Monday, but I can't find a single computer model to support that.
Here's what overnight Monday looks like, according to MeteoEarth.
My snowfall prediction, midnight Monday to Noon Tuesday: 3.4 inches. This time, look for slightly higher totals toward La Crosse, and slightly lower totals toward Green Bay.
Long-range models look dry (but bitterly cold) for the rest of next week, with the next potential snowstorm late next weekend. I'll watch that for those of you planning on going to Lambeau next Sunday for the Packers playoff game.
As always, if and when things change, I'll let you know!
No comments:
Post a Comment