THE JANUARY THAW...
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THE JANUARY THAW IS ON THE MOVE...
Make no bones about it, after one of the most remarkable 10 days of wintry weather in this regions' history, the January thaw is advancing. The "thaw", rooted in American folklore, describes a period of days in mid to late-January in which unseasonably warm temperatures have a tendency to occur. Although the thaw is not associated with a fixed time of occurrence, climatologists note the most frequent thaws occur between Jan. 19 and Jan. 28.
What's coming fits right into that time range and has the potential to be prolonged. We are going to melt some snow and things will get sloppy. Notice the temperature departures we'll experience early Saturday when we are well below zero, January 20th.
By February 2nd, temperatures have gone from 30 below normal to 30 degrees above on the GFS. Are you kidding me! Yea, I think that is pie in the sky.
THE PROS AND CONS OF A THAW...
The big factor regarding how warm we eventually get will be how fast we can eat away the snow cover. If the GFS is correct, we go from a snow depth of 12-20 inches now....
To nothing but piles by February 3rd. Take a look. That would be an incredible accomplishment coming at the coldest time of year with very short days, and a low sun angle. I doubt it.
One factor that should help melt some snow is temperatures a couple nights may remain at or above freezing. Additionally, there are hints that a system or two may produce a mild rain that could gobble up snow in a hurry.
Something that is likely to happen is that once we start melting snow in earnest, low level moisture is going to ramp up. That's likely to set up an inversion that produces lots of low clouds and the potential for dense fog. Mild as it may be, we should get into a dreary pattern that could last the better part of 10 days. Here's the 500mb jet shown February 2nd that delivers the warmth. What a change that is aloft.
The problem is we don't live at 500mb. It's probable that it's much warmer at 30,000 feet than it is where we live at the surface. Guidance will have big problems resolving that issue. The GFS is already conflicted. Below you can see in the afternoon runs how during the snow melting process temperatures, while significantly warmer, remain stuck in the 30s as the energy that would otherwise go into heating is channeled into melting. Then, once the snow is gone the GFS goes bonkers showing a spike in early February where highs soar into the 50s and even the mid-60s February 4th.
My experience tells me to be very leery with temperatures going forward. We will warm considerably compared to where we are now but just how much? One or two little back door highs in Canada and a NE wind could bring our "thaw party" to a standstill once or twice. I think what the GFS is showing is very unlikely and the absolute best case scenario for warmth, and I'm far from ready to buy into its dream of 50s and 60s.
After I exhausted myself, showing the spring warmth the GFS was promoting, the new run 6 hours later just came in. What a difference. Take a look at the change in temperatures into early February. The previous 65 February 4th is now 22. Not a single day has a high warmer than 36 in the Quad Cities.
Instead of eliminating the snow pack, it still shows this for snow cover February 4th. It's lower but far from gone as indicated in the previous GFS run.
I personally think the recent GFS run is more reasonable but with no sampling to measure trends, who knows where things go in coming days. Needless to say, confidence is low in regard to the degree of warming that occurs in the next week or so. For sure, we are warming up, but just how much remains a bit of a mystery.
WINTRY WEATHER TO KICK OFF THE WEEK?
The last thing I will shed some light on is the potential for a light mix of freezing rain, sleet and snow by early Monday, generally from the Quad Cities SE. That wave quickly departs, and a stronger surge of lift associated with warm advection increases precipitation Monday night and Tuesday morning. Mainly snow is shown in the NW third of my area. Elsewhere, mixed precipitation including freezing rain could fall over the remainder of the region. With the cold ground temperatures, slick driving is possible and some form of advisory is a possibility. Due to the complex set of circumstances and issues with thermal profiles, confidence is low on the overall impacts and precipitation types. I see plenty of challenges ahead.
With that, I will wrap this up. Have a fine weekend and roll weather. Also, please consider a donation to the site as my annual fund-raiser continues. Anything you can contribute would be immensely appreciated. Roll weather.
