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
480 FXUS63 KDMX 051148 AAA AFDDMX Area Forecast Discussion...UPDATED National Weather Service Des Moines IA 648 AM CDT Fri Jul 5 2024 .KEY MESSAGES... - Relatively cool and cloudy today with scattered showers and isolated thunderstorms. - Quiet tonight into Saturday morning. Storm chances return late Saturday afternoon into Saturday night. - Additional chances for showers and isolated storms persist into early next week, although over severe threat is low. && .DISCUSSION... Issued at 420 AM CDT Fri Jul 5 2024 A broad upper trof is expected to remain across the central United States over the next several days. This general pattern helps to keep temperatures in check for early July along with chances for scattered convection into early next week. Currently, an upper low sits just north of Iowa with associated convection east of north of the forecast area. Much of the area has cleared although clouds in southwest Minnesota are beginning to move into northern Iowa as the upper low drifts gradually southeast into today. The clouds are expected to overspread much of the forecast area into today with the exception of the far south. Sufficient lift and some weak instability help produce scattered showers into today initially in the north but spreading south as daytime heating peaks. Some locally heavy downpours, gusty winds and some small hail may occur but the threat of severe weather remains low today. The activity will be mostly diurnal in nature with a decrease in coverage this evening along with some clearing. Relatively light winds tonight along with some clearing should lead to a cool night with readings in the 50s to lower 60s. The next shortwave in the broad trof drops southeast into South Dakota on Saturday with a resurgence of warm advection by afternoon into Saturday night. The increasing theta-e advection and modest instability leads to convection across Nebraska during the day which slides east with the wave into Iowa by late Saturday afternoon into Saturday night. Locally heavy rainfall is possible as PWATS increase to around 1.5" by Saturday night. The severe threat looks somewhat muted given relatively unimpressive lapse rates and weak low level shear. Additional weak waves move to the southeast into the upper Midwest through early next week providing additional threat for showers and storms, likely somewhat diurnally driven. The overall severe threat remains relatively low during this time as the shear profile is rather lax. Temperatures remain at or below normal as well with the bulk of heat holding west across the intermountain region of the southwest. However, as next week progresses, this warmer air is likely to build eastward with warming conditions through the end of the work week. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 645 AM CDT Fri Jul 5 2024 MVFR to VFR ceilings are expected over much of central Iowa today with large upper low passing just northeast of the area. Scattered showers and isolated storms are expected today with best coverage in northern Iowa. This activity dissipates by this evening with widespread VFR conditions overnight although a few patches of fog may develop. Winds become gusty by this afternoon from the northwest but diminish into the evening. && .HYDROLOGY... Issued at 420 AM CDT Fri Jul 5 2024 Area rivers continue the gradual fall from the intense rains in June. There were some rises in the upper Des Moines and Shell Rock basins late Thursday from scattered storms, but mostly nuisance rises. Saylorville Reservoir also continues to slowly rise, with a peak level still forecast near 878 feet on July 10-11. The chances for additional showers and storms persist through the weekend into early next week, but with only a low threat of widespread heavy rainfall. The main concern would be an isolated heavy rain leading to localized rise on a river. Overall, a gradual decrease in river levels is expected to persist into the weekend. && .DMX WATCHES/WARNINGS/ADVISORIES...None. && $$ DISCUSSION...Cogil AVIATION...Cogil HYDROLOGY...Cogil