Quick snowstorm update

Moderate to heavy snow continues across the area with the heaviest of it confined to along and south of I-88 down to the I-80 corridor around Morris/Joliet. Snow will continue for several more hours before beginning to taper off late this evening.



Have just over 4" down now and probably a few more to go so my 5-8" forecast from last night looks good.

We have another storm system for sunday night/monday but this one looks warmer and we should melt atleast some snow as we get into the mid 30's with some rain before changing over to snow monday morning.

Old Man Winter..."I'm back" in the words of MJ

Well it took long enough but winter is finally going to show its face tomorrow, better late than never. This isn't going to be as long as it could be cause I'm just too tired. Anyways, our first significant snowfall of the season is due tomorrow and tomorrow night....FINALLY! I've only had 2.1" thus far which is WAY WAY below average by this date in winter.

As usual, taking at the WV loop of whats going on.

http://weather.rap.ucar.edu/satellite/displaySat.php?region=EVV&itype=wv&size=large&endDate=20111020&endTime=-1&duration=12

The southern stream wave is located over the eastern US with sfc low currently located over the IN/OH border down to 996mb which will slowly drift north later tonight and move into MI. As this is happening our main player is the deepening/amplifying trof over the central plains that will continue to dive southeast into MO and continuing to intensify as it then heads east during the day through southern IL tomorrow and into IN/OH tomorrow night.

0z NAM with our strong upper level system by tomorrow evening




Associated with the feature is a strong cold front with very cold air behind it. The front right now is closing in on the ole miss river southward through MO with much stronger winds behind it as well as light snow and temps in the teens and 20's. Whats amazing is we have only had a few events where we are in the 50's one day and a big snow and 20's the next day.



Snow will continue to increase in coverage to our west just behind the front and shouldn't get here till around 9am or after.



Once it gets going though it wont stop till the early morning hours on friday, the long duration nature of this event is one of the things is going to help pile up the snow. The heaviest period of snow should be from around 12-7pm tomorrow.



Another thing that is going to help snowfall production as well as size of the dendrites is what we call the DGZ (dendritic growth zone) This is a zone roughly between -10 and -20 degrees C in the atmosphere and typically where your best snow growth is located. The deeper the layer is, the better snowfall production we have. Thanks to Victor Gensini for putting this image together off the WRF. As you can see the temperature is in the layer from around 600mb down to 900mb which is extremely impressive.



For totals I am still riding my 4-7" call area wide with possibly higher amounts near the lake due to lake enhancement. Rush hour tomorrow afternoon is going to be hell so drive carefully.


Matt

Big 0z Euro phased event next week

Between being bored and thinking it was a cool loop, I thought I would put up a quick animation of the 0z Euro run tonight showing the northern stream wave diving southeast and phasing with the cut off low in the southwest as it slowly tracks eastward across the southern plains.

Where have we seen this before? Geez. Anyways, the models have been throwing around this solution for a few days now with the Euro being most consistent with this happening or atleast trying to phasing somewhere over the central/eastern US.

GR level 2 radar loops of strong tornadoes-Joplin and Greensburg to start

With the current boring weather pattern I thought I would put together a few radar loops from different strong tornado events. I will start off with two monsters that happened in the last four years.

5/4/07-Greensburg EF-5

One of my favorite tornado events of all-time to go back and look at. Analyzing the entire synoptic and even more, mesoscale setup is amazing to me and how the hodograph dramatically near dark, left split after left split after left split then BOOM. The loop of the Greensburg supercell and its associated strong tornadoes is probably my favorite 4 hour loop of all-time. Whats amazing this the amount of occlusions and new mesocyclones that went on to produce more strong tornadoes, some at the same time. As you can see in this loop, the mesocyclone and Greensburg tornadoe starts to occlude just before hitting the town of Greensburg and begins to turn north and eventually northwest while the new meso really intensifies just east of town.


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5/22/11 Joplin MO EF-5 (Joplin marked by the red dot)

The environment suggested the possibility of strong tornadoes in southwest MO but what amazes me is how quickly it spun up and you can get a sense in some of the videos of it showing it going from a funnel to a full blown wedge in seconds. You can also see the insane debris ball as debris was lifted up into the tornado aloft and picked up by the radar.



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I'm bored so thought I'd throw together a quick loop of this run showing a major snowstorm during the first weekend of December. Yes it most likely will not verify and the system in model land is still two weeks away but I couldn't resist. But...this run which goes out to 360hr is very active with enough cold air to work with.

"Control run of the 51 member ECMWF Ensemble Predition System. This is not an ensemble mean"

Saturday, October 29, 2011

0z GFS run...a run for the ages for next weekend

Well the models have been progging a trof in the Western US by late this coming week and have been advertising some serious cold air up in Canada to come on down into the northern plains with a strong wave developing and pushing northeast into the central plains bring up lots of moisture with it. And due to the extreme cold air entering the U.S from the north and alot of warm and moist air from the south, this is creating a serious baroclinic zone for this possible storm system to feed off of and track along. I won't get into serious details because its still 7 days out and lots can and probably will change in model land but some of these images are just insane..

H5 vort and winds showing the 120kt mid-level jet and very strong wave, the 80kt LLJ, 60 dews getting up into IA and northern IL and the 983mb sfc low in northwest IA.

It doesn't get more impressive than this for a system to produce both good severe weather and an impressive snowstorm on the cold side.

5/18/97 Northern IL tornado event-Linderhurst F2

Once I really got into weather I knew I had to go back and figure out what storm it was that scared me to death and hit the area and my town while my friend was over that evening. It was as also tornado warned and the sirens were very loud and I can still remember them to this day. I was seven years old at the time and lived where I still do today, in Batavia. This was one of those events that really got me interested in the weather at a very young age. Every weather nerd like me has "that event" when they were younger that they still remember. This is mine.

This day started off like alot of severe weather days around here...we had convection fire in northern IA in the early morning hours around 12z and develop into a nice storm complex as it headed into southern WI and northern IL but began to weaken as the LLJ faded and mid-level temps warmed. Although the convection died off, we still had clouds leftover to deal with before we began to destablize later in the afternoon. And just an FYI, there aren't any sfc maps from this day...only go back to 1998 on Plymouth's site which is kind of a buzzkill.

14z satellite image



Around 15z or so we began to slowly clear the clouds and have the almost June sun doe its job in heating up the atmosphere and it didn't take long before we had some real progress going on.

18z satellite image



We continued to destablize and by 20z, we got our first hint of DMC in central/eastern IA with a very strong mid-level jet pushing eastward and into the area creating more than enough, and actually quite alot of shear for supercells later in the day.



Quite the jet for late May...a 65kt weserly H5 jet at 0z that evening



Here is the 700mb chart, decided to contour some of the H7 temps to show you the thermal ridge/EML and also put the main jet over the area. H7 temps of 8 degrees C in the area were good until to hold off convection till just the right time in the afternoon.



Storms very going up like crazy in central/eastern IA that eventally pushed into WI/IL by late afternoon and looked very healthy on radar with a tornado watch already issued for that area with a new one likely further east.



As these storms pushed further eastward into IL, more storms fired further to the east along the WI/IL border and with the strong mid-level jet overhead and strengthening 30-40kt LLJ near 0z, the environment became very favorable for supercells and tornadoes as low-level shear increased and created curved and looping hodographs. Also, DVN and ILX both had 35kts at 925mb on the 0z raob soundings, very impressive.





By around 23:30z we had our first legit supercell near Woodstock, IL with a strong meso but there wasn't a tornado reported with this storm, even though it was very impressive for awhile. At the same time, we had the second supercell and associated meso beginning to get going further east.






Here is the VAD wind profile from KLOT at around the time of that image to an hour or so before it. This is exhibiting a veering signature near the boundary layer with increasing slightly veering winds through 3km. We had 0-3km helicity values of 420 m2/s2.



About 30 mins later or so the 2nd supercell to the east become dominant and really took off as the LLJ continued to strengthen and the low-level rotation beginning to really increase as it approached to town of Lindenhurst. This is about at the time right after the tornado dropped just west of town





This tornado went on to produce F2 damage in Lindenhurst.

zoomed out radar image at about the time of the tornado and you can see the red box across the area.




I will continue to do other discussions/write-ups on other northern IL tornado events from the mid-late 90's up to around 2005.


Matt