SEVERE THREAT WITH HEAVY RAIN

A 24-hour change in temperatures from Saturday night to Sunday night.

A much colder start to the week this week compared to the end of last week for the area. A powerful cold front brought severe weather to our east in addition to a significant temperature drop. Early Monday morning temperatures dropped 20-30° compared to Sunday morning. Wind gusts were topping 30mph at times as well, however warmer temperatures are on the way and this will be accompanied by a risk of severe weather.

The severe weather outlook for Tuesday and Tuesday night from the Storm Prediction Center.

Tuesday night into Wednesday morning a fairly strong warm front will lift northward through the region bringing warmer, wetter conditions with a risk of severe weather as well. A Level 2 of 5 risk, a Slight Risk, is in place from the Central Plains into Iowa, Missouri and Illinois. The main threat locally will be strong wind gusts and heavy rain, mainly overnight Tuesday.

A warm front (red line) will lift northward late Tuesday and will be the focus for thunderstorms, some strong to severe, in addition to heavy rain.

Storms are expected to form well to the west in eastern Nebraska and Kansas in the evening Tuesday. These storms will form into a line and move eastward into our area late Tuesday night and early Wednesday morning. In addition to the strong storm threat, heavy rainfall and frequent lightning are likely.

Three-day precipitation forecast from the Weather Prediction Center.

Models have come into agreement a rather widespread area of 1"+ of rain is fairy likely from southern Iowa and northern Missouri into northern Illinois and southern Wisconsin. This will be due to high-end moisture levels setting up over the central US as this storm system rapidly gains strength.

Water vapor transport into the region will be near-record levels. This strong southerly flow from the Gulf will likely be uninterrupted with precipitable water values approaching 1.0" to 1.25". That is more reminiscent of June! This is something that could really run up the rainfall totals, especially if we see training thunderstorms along the warm front. Despite the heavy rain threat, flash flooding is not of major concern at this time as the soil is quite dry and can absorb a lot of moisture.

We could use the rain and are certainly hoping it pans out.

Wednesday's severe weather threat from the Storm Prediction Center.

In addition to Tuesday, we continue to watch Wednesday. A Level 3 of 5, an Enhanced Risk, of severe weather is already in place for the region with eastern Iowa, all of Illinois and most of Missouri in the Level 2 of 5 Risk as well. This could still change with several days before the storms. In addition, there is some lesser confidence here on Wednesday due to the Tuesday night storm activity expected and its potential impact on Wednesday.

Storm could form in the early/mid afternoon from eastern Iowa into Missouri Wednesday and move eastward across the Great Lakes. If the prior activity has a negligible impact, we could be looking at quite a volatile overlap of wind shear and instability, especially over central Illinois and down for much of Missouri.

I think eastern Iowa will remain right on the fringe Wednesday.

Any storms that do form will be capable of producing large hail, damaging wind and a few tornadoes. The highest tornado threat will likely be farther south, especially along and south of I-70.

Also, notice the snow well to the north! Winter Storm Watches have been issued for northern Minnesota and Wisconsin.

A look at the several previous runs of the GFS model showing instability.

In regard to instability, the GFS model has been trending slightly farther west with almost every run for the last two days. This could bring that severe weather threat more into our area. We will really get a much clearer picture once the higher-resolution models get in range to determine the severe potential.

A look at 24-hour precipitation for Friday afternoon into Saturday afternoon.

Looking forward towards the weekend, a northern shift is apparent with the weekend system floating around the Friday-Saturday time frame. The models are still keeping the majority of the rain and storm chances to the south of our area, but we will watch for any more northern shifts. The main reason why we started seeing this shift north is the system is looking stronger, and these stronger systems will have a tendency to shift farther north.

Ending on a quick note, it was great to be back in Iowa over the weekend! I presented my ongoing research into the historic Hurricane Milton tornado outbreak that affected Florida this past October to the Central Iowa NWA Severe Storms and Doppler Radar Conference. So much to learn from this deadly event as we head into the next hurricane season.

Have a great week everyone!

-Meteorologist Nick Stewart