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
414 FXUS63 KIWX 231801 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 201 PM EDT Sun Jun 23 2024 .KEY MESSAGES... * Showers and storms diminish this morning with widely scattered showers and isolated storms possible through early afternoon along a cool front. * Seasonable temperatures and less humid conditions from today into Monday, but heat and humidity may return for Tuesday. Chances of storms/cloud cover lead to low confidence in maximum heat indices for Tuesday. * Renewed chances of thunderstorms for Tuesday and Wednesday. Some of these storms could be strong to severe, but a good deal of uncertainty remains with timing and extent of the severe threat. && .DISCUSSION... Issued at 425 AM EDT Sun Jun 23 2024 Widespread showers and thunderstorms in pre-frontal environment have been exhibiting signs of a weakening trend over the past hour, which should continue through the rest of the early morning hours. Effective shear on the order of 35 knots will support maintenance of this convection into northwest Ohio, but in a continued weakening state as this convective line has outrun better MUCAPE axis. A few gusts in excess of 30-35 mph will be possible through 10-11Z with some brief heavy downpours. Progression of this line should not lead to any notable hydro concerns however. A lagging mid/upper trough working across the western Great Lakes this morning, will allow a region of weak positive vorticity advection to spread across the southern Great Lakes and Ohio Valley through early afternoon. Main question for this afternoon will be on magnitude of instability along the cold front as it progresses through southeast half of the area. Extensive debris cloudiness gradually diminishing this morning may slow destabilization given early afternoon frontal timing, but some low level moisture pooling could briefly allow a modest axis of surface based CAPE to push back across southeast third of the area by midday. Will maintain scattered PoPs across the southeast through early afternoon for some regeneration of showers and thunderstorms, with thunder potential much less across northwest half of the area based on frontal timing. Influx of drier low level air today into this evening will allow for noticeably cooler conditions tonight with lows in the lower 60s and perhaps upper 50s across the northeast. Sfc anticyclone will provide quiet conditions tonight into Monday evening. Monday will feature seasonable temperatures and low humidity values. Tuesday and Wednesday still appear to be potentially more active days in terms of renewed convective chances. Departure of low level anticyclone Monday night into early Tuesday will allow a very sharp low/mid level theta-e gradient to shift back east across the Great Lakes and Ohio Valley. Potential does exist for warm/moist advection to allow area to push near heat advisory criteria again by Tuesday afternoon, but increasing potential of convection still casts a large shadow of uncertainty on how this will evolve. In terms of late Monday/Tuesday`s convective potential, stronger synoptic upper level wave will remain well displaced to the north across Manitoba with zone of strong moisture transport lifting north across the Upper Midwest. Strong low level moisture convergence ahead of associated cold frontal boundary should allow for overnight convection to develop across the Upper MS Valley/northern Great Lakes into Tuesday morning. Farther south across the local area, some risk of isolated convection may accompany the warm/moist advection with the warm frontal zone, but confidence in convection through early morning Tuesday is low due to potential of capped conditions. While moderate to strong instability may develop across the southern Great Lakes and Ohio Valley on Tuesday, ingredients for convection remain muddled at this forecast distance with a wide range of possibilities persisting regarding the evolution of potential upstream convectively enhanced mid level disturbance approaching the area. Overall synoptic shear profiles look to be not overly impressive, but if convective disturbance affects the area it could have its own enhanced shear associated with it. Larger scale signals do appear to be somewhat favorable for MCS type development across the region with stronger upstream northwest flow aloft and potential strong instability gradient sprawled across the area. Some medium range guidance does suggest potential upwind development with southwesterly low level jet feeding in from the southern/central Plains which could possibly keep greatest severe risk across the Mid MS Valley. Needless to say plenty of uncertainty in this scenario, but Tuesday/Tuesday night will be a period to watch for a round or two of convection. SPC has placed much of northwest half of the forecast area in a Day 3 Slight Risk of severe storms. Another southeast diving short wave is expected on Wednesday with main cold front pushing through the area that could bring additional chances of storms. A transition to drier and slightly cooler conditions is expected for Thursday, but in this highly progressive pattern, mid/upper level heights build back in quickly for Friday/Saturday before next potential fropa for the weekend. Did maintain low PoPs next weekend to account for this. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 120 PM EDT Sun Jun 23 2024 The weak cold front has moved southeast of FWA with ample post- frontal low clouds and lingering light precipitation well behind the cold front over northern Indiana. Made some adjustments for more persistent clouds and light precipitation based on satellite, surface & radar obs & trends. It looks like the HRRR and RAP have initialized this activity reasonably well. Clouds should decrease and winds should become light by late evening. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Beach Hazards Statement until 5 PM CDT this afternoon for INZ103. OH...None. MI...Beach Hazards Statement until 6 PM EDT this evening for MIZ177- 277. MARINE...Small Craft Advisory until 6 PM EDT this evening for LMZ043- 046. && $$ DISCUSSION...Marsili AVIATION...Skipper