We had a few raindrops fall here in Otsego yesterday morning, not enough to assume even a trace while from Grand Rapids to the north taunted us with their rain and storms. The thunderstorm watch for Allegan and Barry counties were not productive and lay our hopes for rain dashed by the wayside. We will see similar circumstances today.
Additional rounds of thunderstorms will affect portions of Lower Michigan through Tuesday. Most of these storms will NOT be severe. However, there is a small risk of severe thunderstorms today/tomorrow for communities within the dark-green shading. A somewhat greater risk of severe storms exists on Tuesday for communities within the yellow shading. Here are some key messages: (1) For today and tonight, the timing of storms is uncertain. We expect that several rounds of storms will affect parts of Lower Michigan at different times, but details are unclear at present. (2) For Tuesday, the main risk of severe thunderstorms (yellow shading) appears to be focused in the afternoon/evening. (3) On both days, the main risks will be for local wind damage to trees and power lines, along with large hail and locally heavy rain. Note, however, that most locations will NOT experience severe weather.
Below are the SPC graphics for today and tomorrow.
- Periods of convection into this evening A stalled front to the south of Michigan (near I-80) is parallel to the upper jet, which will be over northern WI into the northern half of Lower Michigan through the day today. One shortwave is causing thunderstorms, some strong over southern WI at 3 am this morning. That convection will reach the I-96 area before sunrise and will likely weaken some as it does so. The next upstream shortwave will kick of another area of storms that will track across the area this afternoon into early this evening. The deep layer bulk shear is in the 30 to 40 knot range where the storms will track. There is an elevated mixed layer between 950 and 850 mb so the instability is above 850 mb. Even so there is around 1500 j/kg of cape for the storms so I would expect the potential for some large hail from these storms. Gusty winds are possible for the stronger storms but it may be hard to mix the wind through that frontal inversion. - Warm front/cold front brings strong storms to area Tuesday Tuesday will be the most active weather day of the week. We have the both and northern and southern stream shortwave trying to come in phase with each other over the central CONUS. This leads to a deepening surface over WI early on Tuesday that tracks north of Lake Superior during the day. This pushes a warm front north through the CWA during the morning then the trailing cold front comes through in the mid to late afternoon hours. The conditons look favorable for strong to severe storms, more so east of Grand Rapids then from GRR to the lake shore. The southern and northern stream jets merge over Michigan by late in the day on Tuesday. That creates a strong right entrance region lift area that comes over Southern Michigan in the afternoon. As with the previous event, we have 40 to 50 knots of deep layer shear, 7 to 8c lapse rates in the 700 to 500 mb layer (good for large hail), and unidirectional shear. All of the HI-RES models (as viewed in HREF) show decent helicity tracks just east of GRR in the afternoon. The storms should be out of the area by early evening. It will be a breezy and warm day too with winds gusting of 20 to 30 mph inland during the afternoon. Highs should be mid to upper 80s south and east of GRR. - Quiet weather mid week then turning warmer by the weekend Once the front is through by late afternoon Tuesday surface high pressure and upper ridging build into the area. This front will bring cooler air into the area for Wed and Thursday. Later in the week a much stronger Pacific system moves on shore and that builds a large upper ridge in front of it. That means warming late in the week into the weekend. Highs could be approaching 90 by Sunday into Monday. There could be some thunderstorms with the warm front Friday or Friday night but it seems most of that will really be farther north than our area.