frostfern

West Michigan seems to miss out on most general afternoon thunder. Hopefully Friday will feature a more organized MCS. Will really need the rain by then. Who knows if it will be evenly distributed though. So often it's a 40 mile wide E-W ribbon of 2-3" with almost nothing north or south.

At least Chicago doesn't get lake shadowed. This weak diurnal stuff always skips over my area. Storms make it 2/3 the way over the lake then die.

I wonder how much time spent in re-circulating AC air contributes to spread. I the north people open their windows and get fresh air. Arizona and Texas mid-summer is the other cabin fever season. Similar for Florida with the humidity if you're not right on the beach where you might be able to catch a breeze.

Next week looks good for thunder according to ECMWF. Showing a progressive zonal flow with heat over the plains.

Up here in Michigan May 2018 kinda crap. Stuck on the north side of the warm front with constant rain for the first half of the month. Only south of I-80 saw the sun. Overnight lows were mild enough for things to start growing, but it didn't really get nice until the end, and at that point it was summer. Summer started early, but there was no pleasant spring with sunshine and temps in the 70s. Went straight from rain and 50s early to 80s and 90s late. Not that I wouldn't take 80s and humidity over cloudy and 40s and 50s.

What is "mild" anyways? I had one of the worst fevers in my life back in early March, but since I was only bedridden for 3 days and never felt so bad I might die if I don't go to the hospital I couldn't get tested. For COVID-19 it wasn't that bad, but I'm having a lot of trouble believing it was something else because I'm 40 and haven't had influenza since childhood. The symptoms were either influenza or a short COVID-19 case. A positive antibody test would make me feel better. It's still worth it even if false positives are possible. Whatever it was my wife got it exactly a week after me. Both my parents were exposed to us before I realized it might not have been influenza, so I was nervous for a while. My father has heart disease.

I noticed the snowpack in the zone southeast of James Bay has continued to increase over the past month. That might have something to do with this stubborn Eastern US trough pattern. The spring melt has failed to reach the 50th parallel anywhere east of Winnipeg. Zone between 45 and 50 has lost some snowpack, but it's stopped as of now and won't resume for several days. We really need a good torch to knock back the glaciers of Ontario and Quebec. Lengthening days and higher sun angle does no good when it all gets reflected off snow. The Canadian prairies now being snow free and warm only seems to amplify the annoying NW flow and eastern Great Lakes digging.

Every month has been some variation of March or November for the past 5 months.

Even if there isn't a snowstorm, these cold outbreaks in April can be interesting due to the increasing afternoon instability. Heaviest snow showers's I've ever seen in my life in Michigan have always been on April afternoons. They tend to be wet and mix with a lot of graupel though, so not much accumulation.

ECMWF had it one run then lost it. Now GFS is showing it.

GFS is now showing a Great Lakes snowstorm on the 14th. Maybe Grand Rapids MI finally gets the bulls-eye 8" swath after we missed it every time this winter. Now that the buds are just starting to open it's finally time for some snow. lol

The destabilization will be driven by cold air advection aloft more than surface heating. The upper low moving in was producing thundersnow showers over the southwestern US. These will be very low-topped cells. Less instability is needed. The bigger problem will be whether there's enough upward forcing to overcome dry air entertainment with such a big shear-to-instability ratio. I don't think CAMS really know how to handle these kind of small-scale details. Chasing small fast-moving cells that can poop out at any moment will be frustrating. It also gets dark early this time of year. If it's a late-evening event it will be mostly in the dark.

Yea. There might be an outbreak of low-topped supercell storms coming out of Iowa as the dry slot and upper low sweeps in from the west. Not a lot of CAPE needed because the tropopause/EL will be low. It's hard to predict if there will be any really persistent cells though. Updrafts might have a lot of spin but are usually kind of small and can be snuffed out pretty easily in the dry slot.

I had a bad cough and 102 F fever a couple nights in a row about 2 weeks ago. I get colds and bad intestinal stuff a couple times a year but I don't recall the last time I had full-blown flu symptoms like that. I'd probably have to go back to childhood. Thankfully I was only really sick for about 3 days. I want to the doctor but there was no test. They said 90% likelihood it was influenze B or H1N1 (even though I had a normal flu shot last October). It would have been nice to know for sure what it was and why the flu shot didn't prevent it. I didn't travel anywhere but now it's a little concerning that random celebrity cases are turning up. It's a worry if non-severe cases are slipping through untested.

Yea. I think sometimes intense sunshine is unhelpful because it produces a deep dry adiabatic layer. Supercell tornadoes tend to like areas where there the low-level lapse rate isn't too steep. Downdrafts don't become too dominant then. You also get more backing near the ground when the first 1000 feet is a little more stable because there aren't as many dry thermals mixing westerly momentum down from above. The most likely place for big tornadoes usually isn't in the middle of a bubble of high SBCAPE. It's usually around the edge of the SBCAPE bubble (i.e. where there's a sharp SBCAPE gradient). I think tornadic supercells are often pulling in the most unstable air from a slightly elevated layer, but the meso is able to "dig" down and pull in surfaced based air as well. For example, you might have a MUCAPE of 1400 j/kg for a layer rooted around 900 hPa on the "cool" side of an old outflow boundary, but the storm is also pulling in surface parcels with CAPE around 700 j/kg. The surface parcels probably have a fairly high LFC, but the vacuum effect of the meso can get them up there. These parcels have a lot more "backed" momentum profile than those entering the storm from the 900 hPa level, so they can contribute a lot of extra spin to the meso, helping to reinforce the upward vacuum effect. On the warm side of the outflow boundary you might have SBCAPE of 2500 j/kg, but meso's are all weak and elevated due to strong cold pools and lack of near-surface backed flow.

Yea. Tornado outbreaks in March and April are usually going to coincide with abnormal warmth and humidity for the time of year. That doesn't mean you need summer-like temperatures though. Shear is far more important, and low cloud bases / high relative humidity is very beneficial because evaporative cooling from nearby precip won't completely stabilize surface-based storm-inflow. I think Dr. Leigh Orf's work provided some pretty strong evidence that violent tornadoes ingest a lot of surface-based parcels that are more stable than average, yet still realize some positive buoyancy once lifted into the middle levels of the storm by the upward vacuum-suction force of the rotating meso. Hot weather brings you the highest surface based CAPE, but that CAPE can be completely neutralized by just a little bit of precip if the boundary layer is characterized by low relative humidity. The result is many hot-day summer supercells have elevated inflow, and thus never produce tornadoes. Early spring supercells are very good at producing tornadoes because they often form in an environment where instability is more than adequate for strong convection despite high boundary layer relative humidity.