Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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
981 FXUS63 KDVN 221950 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 250 PM CDT Mon Apr 22 2024 .KEY MESSAGES... - Precipitation chances tonight and Tuesday, initially battling dry air. - Non-zero, but very low potential for a strong/severe storm Tuesday PM for parts of IL to near Miss. River. - Colder air returns midweek with frost possible Wednesday night. - Turning warmer and active by the end of the week through next weekend, with potential for rounds of showers and storms. Severe weather and heavy rain are possible. && .SHORT TERM /THROUGH THURSDAY/... Issued at 240 PM CDT Mon Apr 22 2024 A shortwave diving down across the Upper Midwest and Great Lakes will usher in a couple of boundaries over the next 24 hrs. The initial boundary/wind shift extends through the eastern Dakotas then into the Front Range. A tightening pressure gradient between than and high pressure over the lower Mississippi Valley is aiding gusty SW winds across the area up to 40 mph. Despite the increasing high cloudiness, the favorable warm SW trajectory has pushed temperatures into the 60s areawide at 2 PM. The air remains rather dry with dew points mixing down into the mid 20s to lower 30s owing to RH as low as around 20-25 percent. This is leading to elevated fire danger, especially in the Ag fields. Tonight, the initial boundary/wind shift will roughly bisect the cwa by morning. A weak wave and warm advection will foster some mid cloudiness and isolated to scattered shower potential this evening mainly north, but the dry sub-cloud air may limit this to more sprinkles if anything. Later tonight and into Tuesday morning, a stronger bout of forcing aided by jet dynamics along with better mid level moisture advection will lead to scattered showers and possibly a thunderstorm, mainly for areas along and especially south of I-80. Winds tonight will likely remain gusty ahead of the boundary, which aLong with cloud cover will result in warmer lows mainly in the 50s with 40s north/west behind the boundary. Tuesday, the shower activity should wane by late morning as the shortwave and boundary exit. Tuesday afternoon becomes a period that may need monitoring for a very low, but non-zero threat for strong to isolated severe storms for portions of the area ahead of a stronger shortwave and surface cold front. General consensus of the guidance places dew points in the upper 40s and lower 50s ahead of the front. A very chilly airmass aloft combined with surface heating will yield the potential for low topped convection ahead of the front. Favorably low wet bulb zero heights will foster hail with any cells that manage updraft organization within a strongly sheared environment. Strong gusty winds will also be possible. The proxy soundings show a favorable juxtaposition of low level buoyancy (0-3km) and low level steep lapse rates (7-8c/km), which could also favor some low level vortex stretching and a very low potential for a tornado provided a storm that manages to develop can remain anchored near the boundary. This conditional very low isolated severe potential would be a fleeting 2-3 hour window (2-5pm), mainly focused along and east of the Mississippi River near and southeast of the QC metro where the best low level convergence is currently being suggested. In the wake, we may see additional scattered showers develop by mid to late afternoon with the cold pocket aloft, which may foster some pea hail and potential for stronger gusts over 40 mph with proxy soundings showing nice inverted V sub- cloud profiles. Winds in general will be rather gusty Tuesday PM 30-40 mph. Colder air settles in Tuesday night and Wednesday morning with lows dropping into the mid/upper 30s north and lower 40s south. Winds likely to remain up to eliminate a frost threat, and temperatures may be largely above freezing and even if a site were to hit the freezing mark it probably wouldn`t be for a sufficiently long enough time to warrant any freeze headlines. Ridging builds in Wednesday through the day on Thursday with cool/chilly mornings and seasonable afternoons. A better potential for at least frost is expected Wednesday night for areas mainly north of I-80, with a low chance (20-30%) for a light freeze. && .LONG TERM /FRIDAY THROUGH SUNDAY/... Issued at 240 PM CDT Mon Apr 22 2024 Friday into Saturday, models agree on bringing a strong low pressure system across Nebraska, NW IA, and southern MN. This will leave the local area in the warm sector with strong southerly winds drawing Gulf moisture northward. PWATs of 1.3 to 1.5 surge into the area by Friday morning. After a lull of PWATs near 1", another trailing surface low in the southern plains will track across eastern Iowa bringing PWATs of 1.5 to 1.8" into the area. WPC has rainfall totals of 1 to 2 inches Friday into Saturday, with the higher amounts in the NW CWA. Then, for Saturday into Monday, another widespread 1.5 to 3 inches are possible. Deep layer moisture and shear will increase with each wave that lifts through the area, which will bring the potential for organized storms, some possibly strong to severe. SPC has roughly the western half of the CWA in a 15 percent outlook area for Friday AM into Sat AM. Meanwhile, WPC has the entire area in a Marginal risk for Excessive Rainfall in it`s day 5 (Fri AM to Sat AM) outlook. It also has widespread 2 to 5 inches across much of NE MO, eastern IA, and western IL in it`s 7-day QPF. Those individuals or businesses that are near creeks, rivers, and poorly drained areas will want to monitor the forecast closely late this week and this weekend. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1235 PM CDT Mon Apr 22 2024 Predominantly VFR conditions are expected along with gusty SW/W winds. Wind gusts will be 25-35 kt at times. Guidance is generating a fleeting period of LLWS after 03z-10z from N to S across the terminals with a nocturnal LLJ, but confidence is low as surface winds are likely to remain gusty and thus have held off on any mention at this time. Several CAMs suggest a few showers are possible this evening with elevated warm air advection, but probabilities are generally around 20% and also sub-cloud dry air could lead to mainly sprinkles with no impacts, and so because of this I`ve not included this in the TAFs. Tuesday, winds will return to gustiness by mid to late morning with gusts to 30 kt ahead of an approaching front. There will be an accompanying chance for showers at KMLI and KBRL and have introduced PROB30 mention 14z-18z. Just beyond the end of the TAF period, the front will sweep through the terminals with winds shifting to the NW and ramping up with gusts 30-40 kt and locally higher possible near any convection. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...McClure LONG TERM...14 AVIATION...McClure