***Official 2025 Weather Thread***

[BCClone]

Waiting for the farm channel to tell us we are still in a drought.

Lol, well, have you looked at a drought map lately???

I’ve always said that those maps love to put us in drought territories. Last year we were in moderate drought and ground water levels were extremely high while we had drown outs all over.

 

[TornadoTouhou]

Storm Prediction Center Apr 27, 2025 1730 UTC Day 2 Convective Outlook

Severe weather, tornado, thunderstorm, fire weather, storm report, tornado watch, severe thunderstorm watch, mesoscale discussion, convective outlook products from the Storm Prediction Center.

www.spc.noaa.gov

Not surprised given most CAMs stubbornly refuse to drop big tornado producing supercells in Iowa or don't even initiate storms until well after the tornado threat is over. Minnesota/Wisconsin is the sure shot, Iowa is the conditional risk despite the synoptic factors being there.

 

[Cyhig]

Not surprised given most CAMs stubbornly refuse to drop big tornado producing supercells in Iowa or don't even initiate storms until well after the tornado threat is over. Minnesota/Wisconsin is the sure shot, Iowa is the conditional risk despite the synoptic factors being there.

Very reassuring to those of us in MN

Making sure my portable generator is fully charged tonight. Figured I won’t need it if it’s fully charged, but you know you’ll need it if it isn’t charged

 

[wxman1]

 

[cowgirl836]

Not surprised given most CAMs stubbornly refuse to drop big tornado producing supercells in Iowa or don't even initiate storms until well after the tornado threat is over. Minnesota/Wisconsin is the sure shot, Iowa is the conditional risk despite the synoptic factors being there.

Very comfortable that I'm spitting distance from the highest risk region. Need that lake disruptor but I think these are more likely dropping from the nw and probably lower tornado risk but those are always the worst wind.

 

[Gunnerclone]

SPC moving Moderate Risk (4/5) farther north.

Much of Central Iowa now Enhanced (3/5)

I’ve been thinking about the risk levels and their usages. I worry that when there is moderate (and high) risk days, it degrades the importance of the enhanced risk area. Not sure if there is a solution (%’s maybe?).

 

[TornadoTouhou]

I’ve been thinking about the risk levels and their usages. I worry that when there is moderate (and high) risk days, it degrades the importance of the enhanced risk area. Not sure if there is a solution (%’s maybe?).

FYI the risk level is more of a probability of severe weather rather than its intensity. You can have a high risk that mainly drops weaker tornadoes (the worst tornado in the Mississippi/Alabama high risk on March 17, 2021 was EF2). You could have a very low risk that drops dangerous tornadoes- I think of the Marshalltown, Iowa EF3 in 2018 which happened in just a 2% risk.

Tomorrow looking at the synoptics, the setup is potent enough that the reason central Iowa dropped to an enhanced isn't because the chance for huge dangerous EF3+ tornadoes dropped that much, but because there is extreme uncertainty on whether storms will even fire in central/center east Iowa. There is a strong cap in place (dry air in the middle levels of the atmosphere) that is preventing surface warm air from mixing with high-up cold air and causing big storms which is the only reason we are not at a higher risk. If something comes through and causes a storm to break through the cap, we could still have supercells that can drop big tornadoes tomorrow in Iowa just cause everything else is favorable for a very dangerous outbreak.

 

[FDWxMan]

I’ve been thinking about the risk levels and their usages. I worry that when there is moderate (and high) risk days, it degrades the importance of the enhanced risk area. Not sure if there is a solution (%’s maybe?).

Yeah, it's a very hard problem. Back in the day when I started it was just Slight/Mod/High, and it was decided that was too course of a scale.

Now with five levels it feels like more detail, but you still have the dilemma of coverage/number of storms vs. intensity.

How do you quantify the risk of a widespread expectation of severe storms, vs something with high end potential, but will probably have very isolated coverage.

Trying to boil essentially 2 big variables into 1 number and I'm not sure there's a great answer.

 

[Gunnerclone]

FYI the risk level is more of a probability of severe weather rather than its intensity. You can have a high risk that mainly drops weaker tornadoes (the worst tornado in the Mississippi/Alabama high risk on March 17, 2021 was EF2). You could have a very low risk that drops dangerous tornadoes- I think of the Marshalltown, Iowa EF3 in 2018 which happened in just a 2% risk.

Tomorrow looking at the synoptics, the setup is potent enough that the reason central Iowa dropped to an enhanced isn't because the chance for huge dangerous EF3+ tornadoes dropped that much, but because there is extreme uncertainty on whether storms will even fire in central/center east Iowa. There is a strong cap in place (dry air in the middle levels of the atmosphere) that is preventing surface warm air from mixing with high-up cold air and causing big storms which is the only reason we are not at a higher risk. If something comes through and causes a storm to break through the cap, we could still have supercells that can drop big tornadoes tomorrow in Iowa just cause everything else is favorable for a very dangerous outbreak.

My thought process using this setup as an example is Des Moines. I know most people don’t even pay attention at all, but even for people that have been watching newscasts for the past few days that have at least seen SOMETHING, I feel like they see DSM come out of moderate and go to enhanced and their mindset is, “Ope, we’re in the clear”. Which kind of jives perfectly with what you posted above.

 

[awd4cy]

I will be happy if there is nothing tomorrow.

 

[Hoggins]

I will be happy if there is nothing tomorrow.

Same. Need a good long week of dry weather to get this crop in

 

[nfrine]

Not surprised given most CAMs stubbornly refuse to drop big tornado producing supercells in Iowa or don't even initiate storms until well after the tornado threat is over. Minnesota/Wisconsin is the sure shot, Iowa is the conditional risk despite the synoptic factors being there.

Name checks out!
Appreciate the inputs you folks provide.

 

[CrossCyed]

National Weather Service

forecast.weather.gov

Looking into tomorrow is when the real questions arrive, along
with a noted MLCAPE axis of 3000+ J/kg as temps and dewpoints
reach the 80s and 60s respectively: possibly the most warm/humid
day of the season thus far. With 0-6km shear values jumping to
50+ kts, the atmosphere will certainly be primed for severe
convection and discrete, all-mode supercells. The question will
be when, or if, initiation occurs however either due to CINH or
a lack of a sufficient forcing mechanism. While there will be
some weak synoptic scale lift across eastern IA from MO into the
MS Valley, and models do suggest some weaker elevated
convection there, the main question will be whether deep convective
initiation can occur along a noted dry line over western IA,
which doesn`t occur too often in the state. Low level mass
convergence will be weak with flow fairly parallel to the
dryline, and the surface low and associated strong QG forcing
moving from MN toward the Great Lakes. Extended range hi res
models at this time yesterday, such as cSHiELD and the NCAR
MPAS ensemble, where noting nearly all healthy convection and
updraft helicity streaks farther north closer to the triple
point and associated warm front, close to the typical conceptual
model for tornado outbreaks. Recent HRRR runs now entering the
applicable window reflect this evolution as well, as do various
MPAS and RRFS runs. However, some 12z HREF members across three
different cores (NamNest, NSSL WRF, HRW FV3) are now depicting
isolated weak to moderate updraft helicity swaths across
northern IA. While the Day 2 SPC outlook has scaled back
probabilities south to north, a Moderate Risk (4/5) is still in
place encompassing locations where some 12Z HREF members are
initiating convection. Any healthy convection that develops
could realize a somewhat alarming near storm environment.
Examination of 00z RAP soundings east of the dryline note
parameter space quite conductive for strong tornadoes in sub
1000m LCLs: 0-500m shear and SRH 30 kts and 326 m2/s2, and
streamwise vorticity at 0.033 (96% of total vorticity). So,
unfortunately, the primary message here needs to be that
possible outcomes range from little to no development this far
south, to isolated, but strong supercells with large hail and
longer track tornadoes. To compound those hazards, any storm
that develops would be moving rapidly, likely in excess of 50
mph with conditions potentially changing quite rapidly,
straining warning and reaction times. Needless to say, it would
be best to continue to monitor for updates into tomorrow. The
severe potential will mainly be in the early evening but
additional storms linger late evening with more development
possible east as convergence increases with the merger of the
approaching cold front and lingering dryline.

 

[TornadoTouhou]

National Weather Service

forecast.weather.gov

So basically, storms probably won't fire south of I-20, might fire a couple north of I-20, hence they kept the 4/5 15% hatched risk up there. The gun is loaded and the safety is off, but there's no one to pull the trigger for central IA, hence the 3/5 10% hatched risk for strong tornadoes in central IA. Anything that fires will be isolated and they can be powerful and spawn big tornadoes that stay on the ground for a while.

The saving grace here if you are caught under a tornado is storms are moving extremely fast, so as long as you stay weather aware the tornadoes will not deal as much damage as they could. A 50 mph forward speed could be the difference between the Nevada EF2 on May 21, 2024 and the Parkersburg-New Hartford EF5 on May 25, 2008.

 

[Gunnerclone]

Pretty insane tornado on the ground in Nebraska right now. Max Velocity has it with his chasers on the ground.

 

[Tpups21]

Pretty insane tornado on the ground in Nebraska right now. Max Velocity has it with his chasers on the ground.

Crazy stuff. Looks about two miles wide.

 

[awd4cy]

Tornado near Whitman. Little town was hit last year.

 

[WartburgClone]

Crazy stuff. Looks about two miles wide.

Little fella' still got the red polygon several hours later. Wonder if this effects tomorrow's weather at all.

 

[FLYINGCYCLONE]

Things are popping up up fast. Just before 6:00 am Iowa had nothing going on, now there is a nice line of showers growing. Hang on.

 

[wxman1]