Sunday, March 3, 2013

WX UNIT DISCUSSION Sunday March 3, 2013


(Hi guys I know I haven't done this in a while.  I'll do this one in plain language instead of the usual abbreviations.  Some readers that aren't into weather don't understand the other format but I won't do this very often so those who don't like it might have to learn the other and get with the program.  I guess I'm getting the itch for severe weather season so this is my way of warming up the brain cells again so I can get away from The News UNIT a bit.)

A relatively strong winter storm system is expected to develop for the upper Mississippi valley, upper Midwest region, the mid Missouri Valley region and portions of the northern Great Plains Monday through late Tuesday. 

Currently a shortwave is evident via water vapor imagery over southwestern Canada with a surface area of low pressure developing over southern Alberta, Canada.  The latest satellite and upper level synopsis shows a large upper level trough across the eastern Continental United States and pronounced ridging across the western half of the United States.  

A narrow stretch of meridional high pressure is noted from central Ontario, Canada to the Gulf Coast which runs the entire length of the Mississippi River Valley with weak ridging noted from Wisconsin northward where overnight temperatures have dropped below zero Fahrenheit across much of central and northern Wisconsin.

Snowfall across much of the region is rather thick with amounts in many areas which will be difficult to erode as warm air advection approaches from the west over the next 18 to 24 hours and ends up keeping the surface freezing level generally west of the Mississippi River save for a few hours this afternoon under sunny skies and peak insolation.  

The next storm system is peculiar in that my initial thoughts were here comes an Alberta Clipper system however upon further observation there is a copious amount of maritime moisture fetch noted at H700 and a rather robust vorticity max noted moving in on the upper ridge along the northwestern U.S. and southwestern Canadian border region.  Also some strong orographic lift was noted on water vapor imagery along the higher mountain range in western Montana northwestward into southeastern British Columbia.   This lift along with ample moisture flow at mid and upper levels is causing considerable cloudiness to spill over from the northern Rockies into the northern and central Plains states with some spotty precipitation indicated on NEXRAD composites but mainly virga for now as moisture has not saturated the column yet with this next event.
I haven't looked at any models but I did glance at a forecast discussion out of the MKX office and saw the Winter Storm Watches and advisories starting to light up from North Dakota southeastward into the Corn Belt region.  I think it's a bit hasty for a Winter Storm Warning across North Dakota and will only mention that with the understanding that forecasters in that region have their own reasons for that as my focus is primarily on Wisconsin and adjoining states.

While this is not the usual WX UNIT discussion I'll consider this a preliminary discussion of observations as I see them happening right now at 1200Z Sunday.  

One more observation I have not mentioned is a rather strong surface trough of low pressure that runs along the lee of the Rockies from eastern New Mexico northward through eastern Colorado and into easten Wyoming.  

Although my initial impressions were perhaps forecasters are expecting a strong clipper system this could reorganize into a potent western type low with a storm track from around KAIA in western Nebraska eastward as it seems there is some initial weak cyclogenesis already in process there.

Further trends will be monitored from here and I will give my detailed forecast later today after reviewing satellite and upper air trends along with the usual peek at the GFS and NAM as I'm a bit old fashioned in forecasting the weather.  Unfortunately things are so model based today we basically forecast from these models and are forced into RUC analysis and all the computer soundings during the height of the storms.  

Either way this system needs to be watched for these primary reasons:
1) The upper level flow is strong 
2) There is a strong vorticity max that is impinging on the western U.S. ridge
3) Unusually strong cyclogenesis already occurring (but will reorganize later on)
4) Copious amount of maritime moisture unlike the usual expectations
5) Large amount of snow cover across Midwest and northern Plains along with deep snow cover from the eastern Dakotas across Minnesota and into much of Wisconsin and inland Lakes well frozen with ice as much as 1 to 2 feet thick in some locations.  

I will also note that there is a chance at a reasonable mild day if the cloudiness can hold off through peak heating and a good day for outdoor activities with no real windy conditions expected across much of the region.

It's still somewhat of a toss up whether this is going to be an Alberta Clipper type system or a Western Type Low.  It may be a blend of both.  


Storm Chaser, David Casper, The WX UNIT

ADDITIONAL COMMENTS:  I see I haven't mentioned snow amounts but I will say I am impressed with the forecasters calling for 4 to 8 and 6 to 10 which immediately got my attention.  I'll be covering this in greater detail later on.  Have a good one!  Don't over cook the books on this too soon. :-) 

Also want to add here that the only reason I looked at the charts today was because I got up here with NO DEGREES on the thermometer and thought "When is it going to warm up?" so I first checked the H500 and then thought O good a ridge.  Then I glanced at the other levels and things immediately looked dicey.  I then spun a 48 hour water vapor of NOAM and I was hooked like fish on this one when I saw that flow to the west.  Yikes!  Winter isn't over yet. 

And one more thing for those of you running the HAARP and NEXRAD transmitters to enhance this storm...yea right?  :-)  Of course I'm kidding.  You don't think I'm a conspiracy nut job do you?


I just can't quit today:  If that GFS is right this looks like a clipper to be albeit a strong one.  I see NCEP and HPC really have some handsome looking charts now in greater detail than before.  Nice.  Makes the storm look pretty doesn't it?  LSE is going to get pounded and Chicago could get hit quite hard.  Too soon to call but there's a lot of red on the charts:

This is not good folks!  If we get the snowfall like this from this one we have a major warming trend in the middle of the month and what looks like one of the stronger spring cyclones I've seen coming around the 13th.  This could spell some major epic springtime flooding problems that need to be discussed for various rivers and tributaries.  Hopefully this one ends up stacking as a big dry windy cyclone but the H850 PW is rather intense.  Could be some long track supercells to the south.

People need to be aware that we could really have a serious springtime flooding problem on our hands.  Definitely keep up with the forecast if you live in a FLOOD PRONE AREA.

Any questions on your region feel free to ask below in the COMMENT section.  I don't charge for forecasting--yet. :-)
If this is a CLIPPER SYSTEM this is one of the strongest CLIPPER SYSTEMS for snowfall amounts I have ever seen in my life.  My doubt meter just went up a bit.