


Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
651 FXUS63 KDMX 150858 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 358 AM CDT Tue Jul 15 2025 .KEY MESSAGES... - Warm and humid conditions continue today, cooler temperatures in the 70s on Thursday. - Storm chances return to western Iowa late tonight (overnight) into Wednesday morning. A few strong storms possible with gusty winds the primary threat. Conditional threat for additional strong storms later Wednesday into Wednesday night, but will depend on morning activity. - Drier to end the week before additional storm chances return at times into the weekend. && .UPDATE... Issued at 358 AM CDT Tue Jul 15 2025 Expectations for a quiet day remain today, though will see moisture advection increase as Iowa sits in the warm sector in relation to a developing low pressure system into Nebraska and Kansas this evening. The cold front per guidance still looks to generally sag into southern Minnesota into north/northwest Iowa and eastern Nebraska late tonight into early Wednesday, with a 30-35 knot low level jet nosing into Kansas. As the front gradually sinks southward into Iowa Wednesday morning, an MCV will track along the boundary across Iowa, which per CAM guidance is still somewhat varied on the path and speed that this system will take. Generally speaking, scattered showers and storms look to move into western Iowa around midnight and track eastward, with instability values around 1000- 1500 and shear values around 25-30 knots that are favorable to produce isolated strong to severe storms should any mature enough, considering these storms will gradually lose steam with eastern extent as the environment looks less conducive. Some CAM guidance points to further development over northern into northeast Iowa into the mid-late morning hours as heating increases, which could keep the potential for isolated severe weather, with damaging winds looking to be the main threat. Into the afternoon to evening, the frontal boundary is slated to generally be somewhere over southern Iowa, with recent guidance suggesting that the boundary would be close to the IA/MO border, with redevelopment of scattered showers and storms in the early evening, gradually pushing out of the state Thursday morning as high pressure over the Dakotas/Minnesota takes over the region. The question still remains on the extensiveness of potential severe weather with the evening activity, as it will still depend on how well the atmosphere recovers following the morning activity. A close eye will be kept on trends to better determine the potential outcome of the later activity. For now, a conditional severe threat remains reasonable, with a more broad-brushed Marginal Risk across Iowa to include at least some chance for isolated severe weather. The heavy rain potential remains highest with the scattered activity Wednesday evening into early Thursday given PWATS of 1.75-2 inches and warm cloud depths overhead, with 1-2 inches of rainfall possible in far southern to eastern Iowa, where a Slight Risk for Excessive Rainfall is in place per WPC guidance. && .DISCUSSION... Issued at 303 PM CDT Mon Jul 14 2025 Fog was quick to burn off this morning leaving mostly clear skies across the state. Few weather concerns through the rest of today into much of Tuesday with the exception of the heat and humidity with temperatures in the mid to upper 80s this afternoon but when paired with dew points in the 60s to 70s, has resulted in heat indicies back in the upper 80s to 90s. Similar warm and humid conditions are expected on Tuesday though moisture off the Gulf increases into Wednesday as flow turns more southwesterly. Although timing and strength discrepancies remain, there is decent agreement in the CAMs and deterministic models of MCS development in NE Tuesday evening that pushes eastward towards the Missouri River late in the evening to early overnight hours. A 30-40 knot LLJ will favorably sustain the activity through NE with the uncertainty lying in what happens as the storms cross into Iowa. The parameter space remains most favorable in western Iowa (pending storm arrival time) where some risk for strong to damaging wind gusts could be maintained before storms continue to diminish with eastward extent. The Day 2 SPC Marginal (Level 1 of 5) Risk area covers this threat well into early Wednesday morning. Additional storms are forecast at times on Wednesday but are fairly dependent on the mesoscale details following the MCS progression into/though Iowa into Wednesday morning. Activity lingering longer on Wednesday morning may push the surface boundary further south towards the IA/MO border into Wednesday afternoon/evening with storm development occurring far south to even south of the IA/MO border. A MCS that decays faster with additional clearing and heating/instability may allow storms to then develop further north into Iowa in the warm sector ahead of the front. Although instability in the warm sector of central to southern Iowa blossoms on Wednesday afternoon into early evening, the better shear lags behind the front. As such, uncertainty remains fairly high Wednesday but some strong to severe storms may be possible and conditions will continue to be monitored closely. The SPC Day 3 Marginal (Level 1 of 5) Risk area again covers this threat well, albeit the threat remains a bit conditional at this point. The LLJ is not as robust on Wednesday night into Thursday, but may help maintain some rain/storms over far southern Iowa into the night. With continuing maturing crops and a couple dry days now, the hydro threat overall remains low, but exists nonetheless with some locally heavy rain possible Wednesday as pwats reach between 1.5 and 2" with favorable warm cloud depth. Precipitation amounts of 1-2" may occur over portions of central into southern Iowa into early Thursday morning, but location and amounts are highly dependent on where shower/storms occur, as noted above. Quiet conditions return for portions of Thursday into Friday as high pressure returns before additional chances for showers/storms return for the weekend. Cooler temperatures in the 70s to 80s will also be in place behind the front on Thursday and Friday before temperatures start to warm again especially into early next week. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1221 AM CDT Tue Jul 15 2025 VFR conditions are expected to continue across the terminals through the period. High clouds are expected to pass through at times, with increasing winds later this morning through the afternoon out of the south, gusting to 15-20 knots especially over northern Iowa. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Bury DISCUSSION...05 AVIATION...Bury