


Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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
45
46
47
201 FXUS63 KIWX 141825 CCA AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 223 PM EDT Mon Jul 14 2025 .KEY MESSAGES... - Smoke aloft from Canadian wildfires is expected to overspread the Upper Great Lakes region today and into Tuesday. An Air Quality Alert remains in effect today for all of Michigan. Tomorrow, an Air Quality Action Day will be in effect for La Porte County, IN. - Patchy ground fog is possible early Tuesday. - Notable increase in humidity Tuesday and Wednesday. Heat indices in the 90s. - Isolated rain/storms Tuesday afternoon south of US 30. Several rounds of rain/storms will be possible between Wednesday and Friday. && .DISCUSSION... Issued at 222 PM EDT Mon Jul 14 2025 Surface high pressure continues to keep mild temperatures, comfortable humidity, and dry conditions across the area today. The cold front that brought showers and a few storms to the southern half of our area the past two days is now stalled across southern Indiana, keeping clouds and precipitation away. Enjoy the low dewpoints while you can today because humidity will notably increase in the coming days. Tonight, quiet weather continues! Light winds, clear skies, and leftover moisture near the ground will create favorable conditions for radiation fog overnight. Patchy dense fog will once again be possible by early Tuesday, especially in areas south of US 30 that have had some rain over the past few days. In addition, wildfire smoke from Canada continues to drift across the Upper Great Lakes region. A statewide Michigan Air Quality Alert remains in effect until midnight EDT tonight. It is possible that smoke aloft gets down into northern Indiana and far northwest Ohio, making for hazy skies. Surface air quality should not be impacted. In La Porte County, IN, an Air Quality Action Day will be effect for Tuesday, July 15th due to elevated levels of ozone caused by the wildfire smoke. Heat and humidity will increase over the next few days. Southerly low level flow and WAA will usher in low to mid 70s dewpoints on Tuesday and Wednesday, with a notable increase in humidity. Highs will be in the upper 80s to low 90s, with peak heat indices in the 90s. Mid range model guidance has been persistent with an active pattern reemerging by midweek. Isolated showers and storms will be possible south of US 30 on Tuesday as a mid level vorticity maximum lifts north and interacts with the still stalled frontal boundary across central/southern Indiana. Next, a warm front will lift north through the area Wednesday morning. With the area in the warm sector, the aforementioned vorticity maximum will aid in thunderstorm development as it pivots through the area Wednesday morning. It`s possible we get a lull in precipitation during the day with a lack for forcing, but renewed chances for rain/storms increase Wednesday evening into the day on Thursday. More shortwaves move through Thursday and a cold front sweeps through during the afternoon/evening, with additional rounds of showers and storms possible. Our typical summertime pattern of high moisture and instability yet minimal shear looks to set up once again, so any severe potential with these storms (especially on Thursday) will likely be determined by whatever leftover mesoscale outflow boundaries there are from prior day convection. By the weekend, dry conditions return with zonal flow over the Upper Great Lakes. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 129 PM EDT Mon Jul 14 2025 High pressure vacates the area Tuesday morning and a shortwave approaches from the south Tuesday afternoon. This allows for VFR conditions through the period and for wind to stay less than 10 kts sustained. Winds out of the west today become southeasterly Tuesday morning. One thing that may need to be watched is for at least MVFR BR tonight at SBN that could evolve into fog. Given low confidence, have kept it out for now, but future shifts may want to consider it. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Air Quality Alert from midnight tonight to midnight CDT Tuesday night for INZ103-203. OH...None. MI...Air Quality Alert until midnight EDT tonight for MIZ078>081- 177-277. MARINE...None. && $$ DISCUSSION...Johnson AVIATION...Roller