lakeville weather journal

Wow...I wanted to title this entry "Deja Vu", but I think I used that title last July. But, weather history...like all history...does has a tendancy to repeat itself. I think that we are all hard pressed to think the repetition here is due so soon. And, in case you didn't hear it all over the news today, yes, the pattern is scary reminiscent of January 1982 when there were two back-to-back storms each dumping 17" of snow on the Twin Cities.

So, I waited until I could study the 00Z model runs tonight to make my "preview" predictions and analysis. Others were very intrigued by the 18Z runs this afternoon, which coupled up the jet structure very nicely on this system, and progged vigorous cyclogenesis as the bulk of the storm energy rolled across KS. GFS has been relatively consistent at pointing out a similar track to the main sfc low as this past weekend storm, putting the metro and surrounds back under the gun. 00Z GFS still tracking like this, but it seems that NAM might have taken a slight departure tonight. 18Z NAM was running the storm track pretty consistent with the other models, and decided to go a bit farther north with the 00Z run, and lacked some other consistency with the previous version. GFS on the other hand is almost carbon-copy. GFS still has the best track record for these Pac-gen'ed winter cyclones, in my opinion. MOS from it at station KLVN has been extremely reliable as well.

Near term concern (or, "Round One") is warm air advection begining tomorrow AM, with H70 flow especially running up from the Gulf of Mex by just afternoon, and with already high relhum in place...low lev atmos is 'primed', which could aid dendridic growth in the low-mid level stratus that will end up rolling over the area through the day. Looks like GFS places precip beginning in earnest over SW MN at first around noon Wednesday, and then progresses NE quickly...with Twin Cities being in height of snowfall around the PM rush hour. Most commercial progs tonight called for 2-4" around the metro by 1800 CST, and I would concur with that given this synopsis. I would expect snow to taper a bit after 06Z Thurs, and redevelop for round two.

Round two comes after the main low moves from KS to northeast IA by 00Z Friday (18C Thurs) and has a central pressure of 980mb or less...very powerful height falls will preceed as a result, and per the GFS, I think we will see heavy snow bands develop between 18Z and 22Z Thurs, and like the last storm will develop and propogate from southeast MN towards the northwest. GFS precip bullseye is focused over SE MN, and pushes the 1" accum Pwat mark...translating on the 10:1 rule for snow as 10".

Here is where I may not totally toss the NAM...as stated before, the 00Z NAM run put that 980 low further north...but NAM develops the upper low and closes it off over the Badger State from 00Z Fri-12Z Sat...quite the stall-out. As a result, precip progs for NAM favor heavy initial snowbands acrs EC MN and WC WI, then changing over to a more "steady" and sustained -SN event into early Sat MN.

Turning to MOS for the period, GFS categorical snowfall outputs show 6-8" through 06C Thurs, and 8"+ from then through Fri AM. I will also point out that the GFS temps run warm tomorrow night...just hovering at if not slightly above freezing. This is a good indication we will see some mixing possible in the precip during the rush hour.

WINTER STORM WARNING Noon Wed-Noon Friday
Wednesday...Cloudy, High 34, snow and/or sleet or snow pellets move in after 4pm. Wind ESE 5-10. All snow after dark. Total accumulation 5-7". Low 25.
Thursday...Cloudy, light snow in the AM possible with 1-2" accum possible. Then heavy snow developing after 4pm. 8-12" possible. Gusty ESE winds 15-20 mph. High 32, low 25.
Friday...Cloudy, snow tapering off after noon. Total storm accumulation 12-17" possible. Blustery and cooler, High 23. Low 19.