While no tornado reports yesterday, there was 2.5 inch hail in Middleton, WI!
Helicity
Monday, April 4, 2011
Hail Event in Wisconsin 4/4/2011
NWS Milwaukee has a short summary of some of the hail events in SE WI yesterday:
Saturday, April 2, 2011
Severe Weather in the Middle Midwest - Sunday Evening Edition
Well hi there!
A nice synoptic - sized cyclone will be developing late this weekend and moving towards the east (as usual) right through the Missouri region tomorrow afternoon. The combination of frontal lift, along with a nice influx of moisture from our good friend the Gulf Coast (the non-oil, all moisture component) and a little dry air (elevated mixed layer) advecting into the southern Missouri/northern Oklahoma area AND the fact that the middle Midwest is right between an upstream trough and downstream ridge (implying upward vertical motion due to upper tropospheric dynamics) is promising for a decent triple point warm sector set up.
Analysis via the NAM model (12 UTC 2 Apr 2011 run):
Synoptic Scale Forcing: 300 mb wind/height between (12 Z Sunday and 00 Z Monday) map shows the western Illinois, Missouri south to northern Oklahoma regions between an upstream trough and downstream ridge, implying upward vertical motion within this region. This is where the cyclone will develop. 500 mb maps (same time-frame) show similar setup, with southwest winds ~60 knots at this level. Vorticity map shows some nice positive/negative anomaly couplets in the Missouri region, and sometimes can be a nice first order indicator of developing convection (though in case the features are small and could just be noisy vorticity data, but I think there is some legitimacy to this). The cyclone and it's respective triple point (including developing warm and cold front) can easily be seen at the 850 mb level (temperature maps) during this same time frame, with the triple point of the system residing near the La Crosse, WI region at 00 UTC Monday. Both the 850 mb and 925 mb maps during this time show strong warm air advection and moisture advection from the south central US meeting with cold air that has resided over the northern US for quite some time, with wind speeds ~50 knots in extreme southeastern Missouri, and still near 40 knots throughout most of Missouri at 00 UTC Monday at 925 mb (between 30-40 knots at the same pressure level since 12 UTC).
Bottom line: Synoptic forcing due to upper level dynamics inducing, as well as strong warm air and moisture advection from the gulf fueling development of a synoptic cyclone, AND dry air (elevated mixed layer) advection from southwest seem to favor a nice triple point style setup over the central US.
Mesoscale Forcing:
Moisture: As mentioned, moist air advection from the Gulf will be present due to the low level jet in the south central US, which will intensify overnight between 6-9 UTC Monday (and transform into the fan-favorite NOCTURNAL LOW LEVEL JET). Dewpoints are forecasted to be in the 60 degree Fahrenheit range easily throughout a nice portion of Illinois south through Missouri and into Oklahoma and Arkansas, with a strip of near 70 deg. dew points along a line from western Illinois through west Missouri south through eastern Texas at 00 UTC Monday. This along with warm air temperatures at the surface will allow for a nice moist boundary layer to develop.
Dry Air Cap: A nice elevated mixed layer will advect over this same region throughout the day due to strong southwesterly winds at 700 mb throughout the day. This will provide for a nice initial cap, and may actually be somewhat difficult to break before dark in some areas, such as eastern Missouri and the southern tip of Illinois. Nevertheless, this will allow for daytime heating to build up a nice "loaded gun" sounding-esque situation that, if broken at the right time, could fire up some nice thunderstorms, including supercells.
Instability: nice values of CAPE (Convective Available Potential Energy) are present throughout this region, with some areas approaching 2000 J/kg (see map below). Therefore, this region will be very unstable, and lifting mechanisms such as daytime heating and frontal forcing will allow for strong to severe thunderstorms to develop.
Shear: 0-1 km relative helicity values are favorable throughout Missouri and Illinois (~ 175-200 m^2 s^-2 range). Soundings (like the one below; note all soundings shown for 18 UTC-00 UTC Monday for north-central Missouri) show some nice veering of the winds with height, and definite speed shear (also, see discussion above about strong lower tropospheric winds). Since the shear is present in regions of favorable instability, supercells and tornadoes are definitely possible in the triple point region.
LCL heights: NAM is showing relatively low LCL heights (~1000m above ground level) throughout Missouri and western Illinois, which is nice for getting some funnel clouds to reach the ground :)
Bottom Line: Okay, there's plenty more to talk about, but I'm getting lazy and have plans this afternoon, so to summarize briefly:
elevated mixed layer + low level jet + shear + instability + high lapse rates (which I didn't cover extensively, but I pseudo-cheated and noticed discussion about this in SPC's breakdown) = supercells + some tornadoes
Key Drawbacks to Tomorrow: Too much CIN throughout the morning might prevent "loaded gun" scenarios from "firing," or in simpler terms, may prevent development of strong updrafts and firing of supercells during daytime hours. Also, I noticed a small gap where CIN diminishes too early, and composite reflectivity is generating a mini-MCS in this spot (see 2-panel plot of CIN and composite reflectivity at 00 UTC Monday below; feature circled). This worries me, because if thunderstorms in the triple point become too organized, then forget about chasing supercells. Also, the sun still sets fairly early, so chasing hours may be limited.
Go Zone: Basically north-central Missouri, then maybe Western Illinois overnight (but mainly north-central Missouri). A few cells may fire in southern Missouri, but with warmer temperatures, dew point depression values are a little higher (also, region is farther from triple point, warm front).
I'll throw out a storm report forecast tomorrow once HRRR is in range of forecasting this thing :)
Peace out,
Helicity
P.S. Again, all plots from Twister Data (www.twisterdata.com)
Tuesday, March 22, 2011
Friday, March 11, 2011
Laser Tag - Briefing
Greetings long distance internet travelers,
As you are all aware, laser tag challenge 2.0 is happening this evening at the Discovery Zone in downtown klanbioandiobna, XZ (look, we cannot give away the city we're from, because otherwise you'll find out we're from What Cheer, IA). I know I know, you are all very excited about this, but don't worry, I am too. That's why I've dedicated this blog post to discussing the necessary strategies to succeeding at laser tag.
First, watch this video to get a quick intro briefing on laser tag:
Great! Now that you know what's going on, it's time to discuss our battle plan to defeat the most talented, strategical, vicious, and laziest people on the planet...children.
Strategy #1: Cheating is okay!
You know how everyone tells you not to cheat in laser tag? Don't listen to those people. Cheating is most definitely allowed.
"But wait Helicity, why would you say something so immoral?"
Don't worry, it's not immoral. Remember, you'll be playing against a plethora of children and young adults that will do ANYTHING IT TAKES to win this game. They'll run between your legs, follow you in the arena, and even continue to shoot you after you have been deactivated. How classless is that? WE CANNOT LET THEM WIN! If you need to cover your shield for a minute, do so. If the kid players follow you, you follow them back. If they are annoying you, pick them up and hold them hostage...they'll have nowhere to hide (see video reference below for this)
Strategy #2: Make the children come to you by "Camping Out"
When playing against kids, one should remember that effort is inversely proportional to winning. How does one accomplish success on the battlefield with minimal effort? Have your whole team hang out in one room, enjoy a nice conversation and throwback with your teammates, and LET THE CHILDREN COME TO YOU! This by definition is called "camping out," and is also known as "cherry picking." If you do this, not only will you and your teammates easily take out your laser tag nemeses, but you also don't have to walk around and exhaust yourself in pursuit of one individual at a time.
As a guide, I marked regions where "camping out" will lead to high success rates:
The green stars indicate excellent regions to chillax and wait for those pesky kids to come find you, so you can deactivate them all day long. Notice that the white star marks a suggested spot as well. I mean, if you think about it, if they can't get inside the level, how will they win?
Strategy #3: Taunting
There's an old saying that goes, "Sticks and stones will break my bones, but words will never hurt me."
Well, since you don't have sticks and stones to break your opponent's bones, then words are your only option. Most kids at this point in their life enjoy laser tag, because it's a free opportunity for them to apply taunting and name calling without their parents yelling at them (especially since no one will hear you when there's loud laser gun shots and music drowning out the noise). Don't give them the satisfaction of taunting. TAUNT BACK! For example, say that you are on the yellow team, and a kid tells you that your team stinks because yellow is the color of pee (actual quote used here, no joke!). In this case, some suggestions for comebacks are
1) "Well, if we are like pee, then at least we're sterile!"
2) Can't wait to play you all evening...oh wait that's right! You have a curfew!
3) "Oh yeah? Your color is the color of (whatever offends them or angers them)"
4) "You're adopted, your parents don't love you!"
Well, there are many other ways to taunt as well, so be creative! Hit 'em where it hurts!
Well, that's all I can think of for now. Whatever happens out there on the laser tag battlefield, make sure you are having lots of fun....and making sure your team defeats the kids.
Peace,
Helicity
Tuesday, March 8, 2011
HRRR Strikes Again?
The latest HRRR spits out 4/5 inches of snow for Madison, as seen below.
As has been the case with the last three storms to hit the Midwest and Great Lakes, there has been a southerly trend even as close to 24 hours out. Which poses the questions, is the heavy snow pack over the Northern Plains and Canada altering the storm track? The argument could be made that the models are showing bias to move the storm track north, due to climatology programmed into the model. But with a deep snow pack firmly in place the largest temperature gradient and consequently the storm track has remained further south compared to what is normal for this time of year…
We’ll see tomorrow if the “Answer Key” is correct once again. The HRRR is notorious for pinpointing the heaviest bands of precip, snow fall and even Supercells with uncanny precision. More on this later, with a brief recap of today’s severe weather.
“Convergence”
Severe Weather Outlook - March 8, 2011 C.E.
Bore da (which means Hello in Welsh, or something),
Well, it looks like that old trickster dryline in the southern United States is going to be at it again, along with a little help from his/her/its friends (aka a synoptic scale cyclone developing in the Southwest; okay so only one friend this time). Currently the SPC (Storm Prediction Center) down in Oklahoma is predicting a 5-10% chance of tornadoes forming in Lousiana later this afternoon. Their claim is that the combination of upper level jet streak dynamics (with the right jet entrance region, or upper (lower) level divergence (convergence) region over Arkansas and Louisiana, implying upward vertical motion), along with the dryline feature and frontogenetic forcing (in this order) will lead to severe weather in this region.
A look at the 15 UTC (9 am LST, so about an hour ago) NAM (initialized 00 UTC) 300 mb (plot of wind speed (fill pattern, with more purplely colors indicating stronger wind speeds) and wind barbs (knots) and geopotential height in units of dam (black contours)) shows that the right jet entrance region of a local jet streak is indeed over the Lousiana region. This will provide some initial upward motion in this region.
Interestingly though, a small jet streak feature off to the west will move into the region around 18-21 UTC (12-3 pm LST), with the right jet exit region over Lousiana. Since a thermally indirect circulation exists in the exit region of the jet, subsidence (downward vertical motion) will act to warm the the middle to upper troposphere. While at times this type of setup can lead to dynamic destabilization, allowing for the atmosphere to become unstable over time and fire
up some nice convection later in the afternoon, this can also inhibit severe thunderstorms by warming the air too much such that lapse rates decrease and are not as favorable for development of strong upward motion. My guess (along with Croix "Convergence", the man himself) is that it might be limiting thunderstorm development initially.
Forunately, the dryline comes to the rescue! During sunset hours (00 UTC Wednesday, March 9, aka 6 pm LST in Louisiana), the dryline moves into the region, along with the start-up of the nocturnal low level jet. The dryline acts as a lifting mechanism for warm, moist surface parcels to rise as the drier, more dense air forces the less dense moist air to rise. Along with this, the low level jet (see 925 dewpoint map, where color fill pattern is dewpoint, wind barbs are in knots and contours are height contours in dam) shows wind speeds reaching nearly 50 knots overnight over this region, and then near the Alabama-Mississippi border!!! Along with this, favorable CAPE (measure of instability) values > 1000 J/kg, Lifted Index less than -4 (a measure of lift; less than -4 is good for severe weather) and helicity (measure of the "corkscrewiness" or rotation more or less from 0-1 km (in this case)) values near 200 m^2 s^-2 reside in this region.
While strong helicity values are also present in Arkansas and Missouri, the instability and lifted index values are not quite there for a tornado outbreak, but organized severe weather (or at least strong convection) in the form of an MCS is still likely with high dewpoint values (55+ deg F), precipitable water (~1.5 in) and lift from the synoptic cyclone present.
Above: Lifted Index (fill), mean sea level pressure (mb) contours 00 UTC Wed 8 Mar 2011
Above: 0-1 km Storm Relative Helicity (fill and contour, m^2 s^-2).
Which leads me to the discussion regarding the forcing from the synoptic scale cyclone. A look at the 00 UTC Wed. (still from NAM 00 UTC Tuesday model run) 925 mb map (Wind speed in fill pattern similar to 300 mb map shown earlier, with heights in black contour and wind barbs in knots) shows the location of the cyclone over over the Kansas-Missouri border. This cyclone will provide frontal lift as it moves to the north-east, aiding in the generation of thunderstorms (and supercells farther south of the cyclone, near Louisiana) during the evening to overnight hours.
This blog post was sort of rushed due to my necessity to solve the mysteries of tropical meteorology today at home base, but the general idea is that the combination of upper level jet dynamics, the low level jet and dryline combo, along with the synoptic level forcing from a strong low level cyclone is going to create some interesting weather in Louisiana. Louisiana is in the perfect spot, since it is most affected by the three weather forcings described above, and also is in the zone for most instability and high values of lifted index. I'd say that a few tornadoes will form, mainly during the later evening hours and overnight. Those in Alabama and Mississippi should be on the lookout for tomorrow morning, since any generated convection will move east and possibly induce tornadogenesis in a region that is predicted to have high values of helicity and reasonable instability tomorrow morning.
Over/under on tornado reports: 5
Over/under on wind reports: 34
Over/under on hail reports: 9
Are these over/under's reasonable? I honestly don't know, but I've never done this before so it's a nice starting point.
Peace,
Helicity
NOTE: ALL MAPS FROM TWISTERDATA.COM.
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