Friday, December 31, 2010

Severe possible along and south of I-72 today

Here's a snippet from my forecast for NIU this morning dealing with the severe weather chances:

A thin line of showers and thunderstorms is possible along the cold
front as it approaches the area early tonight, which should bring an
end to the precipitation. Minimal instability levels will limit the intensity
of any storms that enter the area, though some heavy downpours are
possible, and this coupled with rapid melting of a decent snow pack
will lead to flooding in some areas. Further south in central and
southern Illinois, somewhat higher instability will lead to a higher
chance at a couple severe weather reports. The best threat
appears to be damaging winds, but if enough instability is
present a tornado or two is possible over the southern half
of the state. Instability is much lower than that of winter severe weather
outbreaks of recent years (January 7th 2008 and December 27 2008
to name a couple) so while the potential exists, I'm not expecting
anything too substantial. Wind shear is very strong in the
southern half of the state however, so any pockets of increasing
instability will need to be watched. Tornadoes have already been
reported with the supercell thunderstorms located in southern
Missouri, that at their current track and speed would be entering
Illinois around the St. Louis area around noon. Instability
will be decreasing through the day with eastward extend, so
an atypical weakening trend though the afternoon hours is
certainly possible. Again, this does not pertain to the immediate
DeKalb area, but being a major holiday during a time when many
are not expecting severe weather it's worth mentioning. I would say
areas south of Interstate 72 in central and southern Illinois should
remain alert for changing weather conditions and the possibility
that the storms in Missouri do maintain their current strength, while
areas north of Interstate 72 can expect to experience only garden
variety, but still perhaps heavy rain producing thunderstorms.

Thursday, December 30, 2010

New Years Eve thoughts cont'd

For now, it looks like things will be too far west for me to really
care about chasing prospects, but it does look like there is the chance for some winter fun around these parts, that doesn't involve snow.

I'll have family over for an extended family X-mas gathering,
and while I alerted them to the fact that I could not pass up stepping
out briefly for a December intercept, I won't be heading very far. If
we can get some clearing early in the day in west central IL I may be
interested. My eye is on the St. Louis area right now, if any.
Whether or not it's worth the trip for me will be figured out tomorrow afternoon.
Best case scenario for me is to head down 72 and intercept something
near Springfield, but I don't know how likely that is now. I think somewhere
along and near Interstate 70 in southwest / south central IL stands a
chance of a few after dark tornadoes tomorrow night. I expect storms
to initiate near St. Louis, eventually becoming widespread along the cold front
across much of Illinois producing potentially severe weather along and
south of I-80, and potentially tornadic over the area outlined above, in
southwest/south central Illinois.

Not likely a chase day, but certainly something exciting to watch in
late December.

Monday, December 27, 2010

Noisy New Years?

With a potent storm system entering the picture at the end of the week, my weather senses are beginning to tingle with the potential for some thunder in the mid-west! Here's an excerpt from my forecast discussion for northern Illinois:

"There should be a brief pause in the heavier precipitation later on
Thursday as we enter the warm sector of the system. That said,
abundant dense fog and some drizzle are still looking like a good bet.
Once the center of low pressure begins pushing into the Great Lakes,
dragging with it a sharp cold front we'll begin to see a return to heavier
precipitation during the day on Friday. The rate at which we can melt
off the snow pack on the ground (DeKalb currently has 13" of snow
on the ground) will determine just how warm we get ahead of this very
dynamic system. At this point, it appears that we should at least
reach the middle 40s by Friday evening. Remaining snow on the
ground, coupled with thick soupy cloud cover and heavy rains
could cap us off right there, but with such a potent system
it's not yet certain just how high we'll get. For that reason,
it remains unclear whether or not we'll see any thunderstorms
with the passage of the cold front. A vigorous system such
as this one certainly lends the possibility, but the amount
of instability that we actually achieve will be the deciding point.
Whether the sky is illuminated and the ground shakes is
up in the air, but a period or two of heavy rain is a safe bet."

Downstate in central Illinois, some thunder looks a little more likely as temperatures approach the middle 50s by Friday evening.

Below is the European solution for New Years Eve at 500 mb. In April, that'd have us talking tornadoes.

Also, in some of the holiday downtime, I took the liberty to go and visit a neglected chase day and share a few unseen photos. June 19 2009, Tia and I chased a supercell from right over Urbana into western Indiana. This was the day after my car was totaled driving to Iowa for a storm chase. I woke up knowing the chance for storms existed but frankly did not care. Tia drove me to the hospital to get some neck and back pain from the accident examined. Right as we got to the waiting room, I was texted by Mark Sefried informing me of a supercell heading right for us. The appointment went quickly, and Tia was up for a chase and was willing to use her car as the chase vehicle for the day so we were off. No data at all, not even a paper atlas. Just our eyes and a car. It ended up being a great chase, however! But, once we returned home, I was still not a happy camper after the situation in the 24 hours prior so I didn't do anything with the photos I took.

Oh yeah! I remember why. I missed documenting an apparent tornado that afternoon south of Danville, IL. Rapidly rotating wall cloud narrowed into a beautiful white funnel which apparently touched down just north of us. I didn't see anything on the ground though, and the ground contact could not have been more than a hundred feet from us as the funnel passed directly overhead. I realized when I returned home that the camera was on stand by. That's what I really wanted to see on top of the situation. Anyway, here are a few photos of the storm...

Early in the storms life cycle, just east of Urbana, IL.

Crossing the border near Cayuga, Indiana.

Weakening now:

Wednesday, December 15, 2010

Geminid Meteor

Was it really only 4 degrees above zero the other night? I didn't notice.

I went out and braved the cold to capture some of the Geminid meteor shower that peaked on the morning of the 14th. I counted approximately 60 meteors in the one hour that I was out there. I had on enough layers to clothe a small village, and managed to stay fairly warm for the brunt of the hour that I was out. It was the feet that got me... once your toes and feet get cold there is no turning back. The conditions were perfect, and the meteors were beautiful. I didn't get the fireball that I was after, but I did manage to capture one decent meteor in with the star trails. There are several others in the photo below, but they were too dim to pick up with the Sigma 10-20. Need something that can do lower than f4.0 for that.

Looking like another 2-4 inches of snow here in central Illinois. I'm back in the Champaign area for the majority of the next month for the holiday semester break. I'm always anxious to get the spring semester underway as the days only get longer and warmer, and after a few weeks that first hopeless "slight risk" always pops up somewhere in the midwest. That day that you know you'll regret going for, but after a long and cold winter you can't help but lose sleep over. Only a couple months and change until what I consider the beginning of storm season. Nothing is fun to chase until early April, but as I always say, *someday*, that early season violent outbreak will show it's ugly face again, and I can only hope it's not the day I finally give up on the early season chase.

Geminid meteor and about 30 minutes worth of star trails:

Beautiful water vapor illustration of the powerhouse storm system that brought the blizzard conditions to the midwest on Saturday and Sunday.

Monday, December 6, 2010

Tentacle like snow bands

Saved a quick loop of the radar out of Chicago, IL this afternoon that showed some very bizarre tentacle like snow bands passing over the area. Each one was producing snow that was not making it to the ground.

Friday, December 3, 2010

Snow update

Things becoming a little more clear with the snowfall totals across northern Illinois Friday night into Saturday. Looks like we're finally converging on what will likely be a swath of 3-4 inch accumulations with isolated 5-6 inch totals possible in the heaviest banding likely in northwest Illinois around the Quad Cities / Sterling area. The main swath of 3-4 inch totals should extend out of Iowa into NW Illinois from the Quad Cities to Rockford southeast toward Kankakee to Peoria. As the strength of the system wanes during Saturday morning areas downstate in central and eastern Illinois will receive lesser amounts, but will still be at the very least sweeping off their front porches by Saturday morning. I''ll go with more common 1-2 inches down there, with a few 3 inch reports possible along and north of Interstate 74 from Bloomington to Danville.

Snow should begin in northwest Illinois between 9 PM and midnight, and translate into north central Illinois and the DeKalb area shortly after. Central Illinois should begin to see their first flakes around midnight or so. It will take a while to saturate the very dry column, so while initially the radar may indicate snowfall, it will take a couple hours before snow begins making it's way to the ground in earnest.

I'll throw in the disclaimer that with such a dry powdery snow, any area that sees any period of banding/increased precipitation rates could easily stack up the totals quickly. I've done my best to outline where I think the best banding will line up at 24 hours out, but adjustments may need made once the action begins! I'll try to throw in another update once the evening model suite comes out.

Thursday, December 2, 2010

First accumulating snow

Looks like the first accumulating snowfall will glance the area over the weekend. Here in northern Illinois is looks like things will kick off late at night on Friday and carry into the day on Saturday.

Yesterday morning the models decided to go bonkers with snowfall amounts suggesting upwards of 10 inches, but have since calmed down to a more realistic scenario. Main killing factor seems to be the weakening trend with the H5 wave. Rather than the more amplified solution projected yesterday morning, a more subtle feature should sweep into the area and rapidly lose it's definition as it pushes over the area. This lack of upper level support seems to be the main instigator in the lesser snow totals. Initially as the dendritic zone becomes saturated it will remain above the more favorable omega layer, but over time into Saturday morning it should lower into a more favorable layer. Even with upper level support lacking this should instigate a period of fairly heavy snowfall over northern Illinois around sunrise.

It won't be the most organized system, but with a fairly dry snow things could accumulate quickly. Winds won't be overly strong, but again a dry powdery snow will let things blow around in rural areas through Sunday. Given QPF totals from around 0.3-0.5" and a dry snow ratio beginning around 12:1 and increasing upwards of 18:1 by Saturday morning, maximum totals of around 4-5 inches seem plausible in a narrow band. With large model spreads even only 36-48 hours out and the system not even onshore yet, nailing down the area of heaviest snow totals is pointless.

As is typical with me, I'm fairly excited about the first snow of the year. I'm generally okay with snow until about the end of January. By February as things start thawing out, I start getting that "February itch" to get out chasing and am about ready for frozen things to stop falling out of the sky, unless they're golf ball sized chunks of ice hitting my windshield as I search for tornadoes. So mother nature, you've got two months to get in all the winter storms you want so use your time wisely.