Robert Dewey - Imminent snow?

[Todd Rittinger]

Robert, Nick, and any other Michiganites: it would appear that a snow event is inbound for you and us (S.O.), but on another mailing list, a student whose forecasting ability has proven quite accurate in the past, is thinking a dud. Since my skills are still non-existent, what do you think?

Be well, TR

 

[Robert Dewey]

Well, it certainly is interesting... The one thing I notice the most is the very dry air in the low levels, with dewpoints down to nearly -20F in southern Ontario, to around -6F or so in lower MI. Usually, this tends to stop significant snows in it's tracks. On the other hand, the latest 18Z ETA and GFS have bumped up QPF across this region to nearly 0.50 inches, and with a nice ratio of 1 to 20 or 1 to 25 would mean nearly a foot of snow for quite a few places. Supporting that would be the weak stability in the lower mid levels, as well as a very strong TROWAL that lingers around between 700-500mb in the >80% humidity layer and good vertical velocity through tomorrow afternoon which to me would point to mesoscale banding of snows. Again though, it's highly dependant on whether or not the dry low level air can be over come, so certainly not an easy forecast. I would tend to go middle of the road and call for around 6 inches, but if it appears that the low level dry air won't be too much of a problem, I would say 8-12 inches.

 

[Todd Rittinger]

Thank-you muchly my friend; I'm now going to try to identify what you have mentioned in an effort to improve my skills.

Be well, TR

 

[Todd Rittinger]

It's the dry air that I keep missing for some reason...ok, so am I correct in this reasoning:

Dry air is dry for a reason, that is, it is colder air, therefore more dense (like my brain lol) and lower ability to retain water. The only way for this air to be able to retain moisture (significant amounts) is to increase in temperature. This warmer air then has to pass over moisture (large water body for example) or be mingled with air already containing moisture. A large and dense enough cold dry air mass has enough clout to divert an "inbound" moist air mass or stop it.

Am I on track with this concept?

Thanx everyone, I'll have this down yet...

Be well, TR