***Official 2025 Weather Thread***

[JM4CY]

View attachment 148465
It's still a little early for the higher resolution models (HRRR, NAM) for Monday but the latest GFS is showing actual convection and potentially discrete/embedded supercells in Iowa from 4-10pm on Monday.
View attachment 148466
Here is a sounding for Ames, IA on 4pm on Monday- decent low level curvature that gets better as the night wears on, upper 60s dew points, over 3,000 Surface-Based CAPE, and 54 knots of wind shear is a very potent setup for all modes of severe weather if a supercell moves over, even strong tornadoes. Again the main thing that is stopping this from being an upper upper echelon event is the helicity- around 200 helicity is good for tornadoes but a little low for the really violent ones like the ones that hit Greenfield last year. Of course an unlucky boundary interaction and that could be overcome.
View attachment 148469 Another potential limiting factor for a tornado outbreak is Iowa will likely have near total cloud cover for most of Monday (this is Monday morning at 10am) and that could dampen the instability somewhat, though not nearly enough to prevent severe weather outright especially given there is the occasional break in the clouds.
View attachment 148470 Map of helicity at 7pm on Monday (still a tad early for helicity tracks)- blue is 100 m2/s2, orange is 200 m2/s2, red is 300 m2/s2, purple is 400 m2/s2. The SPC defines the ideal environment for strong tornadoes to be around 247-402 m2/s2 helicity: https://www.spc.noaa.gov/exper/envbrowser/, and the higher helicity values are generally gonna be east of I35, so I think that's looking to be where the largest potential for tornadic action will likely be from this model- of course that can change as high resolution models come into play (and GFS is historically very bullish and somewhat chaotic on tornadic setups).

Can someone explain this to me like I am 9 years old?

 

[jsb]

There’s something kind of weird with my parents’ farm. They’ve been real dry. Have gotten around 5 inches of rain since Sunday but nothing super crazy. No real big rain to the north. But their creek is flooded fairly bad. They can’t figure it out.

 

[ClonerJams]

Can someone explain this to me like I am 9 years old?

Pucker your anus

 

[ISUAgronomist]

There’s something kind of weird with my parents’ farm. They’ve been real dry. Have gotten around 5 inches of rain since Sunday but nothing super crazy. No real big rain to the north. But their creek is flooded fairly bad. They can’t figure it out.

5" is a lot for infiltration in a week.

 

[DSMCy]

Can someone explain this to me like I am 9 years old?

This is my yearly Spring tradition where I don't understand a word in this thread, but I open it right away when I see a new post lol

 

[jsb]

5" is a lot for infiltration in a week.

Yeah, but it was pretty slow—-they didn’t get all 5 at once. They are surprised at how high it is. They’ve been here 43 years and are good at predicting what the creek will do and this surprised them. The neighbors are also wondering what’s up.

Hopefully they don’t get one of those 6 inches in a night because they’d probably be floating.

 

[CryoLegion]

Can someone explain this to me like I am 9 years old?

Basically there is a lot of uncertainty with the setup but expect a chance for big tornadoes even if it's not like Greenfield bad or Parkersburg bad, and right now I'm guessing that chance is best mainly east of Ames/Des Moines (although the whole state could see tornadoes at this rate).

 

[3TrueFans]

Can someone explain this to me like I am 9 years old?

Gonna be bad on Monday, or maybe not, but possibly, but also maybe not.

 

[simply1]

Can someone explain this to me like I am 9 years old?

Cloudy and sunny and stormy and maybe tornadoey

 

[CryoLegion]

Cloudy and sunny and stormy and maybe tornadoey

Hopefully more cloudy than sunny (which seems to be the trend for models on Monday), sunny and 65F (or hotter) is perfect weather in the day to cause big instability which leads to big tornadoes in the evening.

 

[Gunnerclone]

5" is a lot for infiltration in a week.

Username checks out ^^^

 

[cowgirl836]

The odds of you getting hit are the same regardless of whether you have been hit before.

Independent events!

 

[Cyhig]

Can someone explain this to me like I am 9 years old?

 

[cowgirl836]

This is my yearly Spring tradition where I don't understand a word in this thread, but I open it right away when I see a new post lol

The weird vertical graph lines are what I can't understand

 

[awd4cy]

I know someone whose house was destroyed in a tornado in 2000. They rebuilt the exact same house and it was destroyed in 2008 in another tornado.

Damn. Here in Iowa?

 

[FerShizzle]

50/50

ish

 

[CryoLegion]

Independent events!

If you want a history of all the places that have been hit twice by a tornado, TornadoArchive is a good place to check, they have documented just about every tornado from the late 19th century to 2023 https://tornadoarchive.com/explorer...ale|(E)FU,(E)F0,(E)F1,(E)F2,(E)F3,(E)F4,(E)F5


You can see that most F5/EF5s tend to hit north of Des Moines, despite the generally higher amount of tornadoes in the south part of Iowa. And there are a number of spots where multiple tornadoes have hit the same spot (albeit this is over 140 years).

 

[CryoLegion]

I know someone whose house was destroyed in a tornado in 2000. They rebuilt the exact same house and it was destroyed in 2008 in another tornado.

I wonder if that person lives just northwest of Dunkerton, IA
Orange+Yellow is the Cedar Falls F3 in 2000, Purple is the Parkersburg EF5 in 2008

 

[3TrueFans]

I wonder if that person lives just northwest of Dunkerton, IA View attachment 148479
Orange+Yellow is the Cedar Falls F3 in 2000, Purple is the Parkersburg EF5 in 2008

That purple tornado was doing tricks, just casually hitting a loop-the-loop and a u-turn

 

[JM4CY]

Pucker your anus