We have enjoyed a long summer with warm temps and lots of dry and sunny days. The autumnal equinox begins this week on the 22nd and our weather pattern will cooperate with temps dropping into the 60s, which after sweltering in the 80s for so long this will feel cold to some.
This is the seven-day QPF (rain) forecast for this week which is guessing one to three inches. We have had only .16 of rain here in Otsego thus far for September so this will be welcome. I am building a shed in my back yard so I hope to get a roof on it before the rain starts tomorrow.
Yesterday’s high temp was 80° and the low was 61°. Today many areas in SW Michigan will see temps in the mid-80s.
Sunrise today is 7:27 and sunset is 7:45 pm.
- Swaths of heavier rain possible Monday into Tuesday Moisture associated with the former tropical system Nicholas moves into Southern Lower Michigan late tonight, but especially on Monday. PWAT values will increase to right around 2.00 inches which is rather high for mid to late September, but typical of tropical moisture reaching this far north. The chances for rain Monday and Monday night will be associated with this tropical moisture and an associated upper shortwave. There is little to focus the rainfall however with deep southerly flow in place and no boundary to interact with. Not expecting widespread heavy rain, but given the PWAT values there will certainly be efficient rainfall processes ongoing. Better chances for heavier swaths of rain are expected on Tuesday as a cold front pushes into the very moist airmass. WPC QPF progs show widespread 1-2 inch amounts over our entire forecast area through Wednesday morning. Feel these amounts will likely occur in swaths across our area and not be widespread across the entire area. Given heavier rainfall rates some localized ponding of water is certainly possible Monday into Tuesday. Rivers are quite low, so not expecting much issue there. Case in point, the Grand at Grand Rapids is at 1.61 feet at 200am which is very low. Threat for severe weather looks low as instability never really increases substantially. Most unstable CAPE values via the NAM3km which has a high bias on this variable only generates around 1,000 J/KG on Monday and even less on Tuesday. Some embedded storms for sure, but agree with the general thunder assessment via SPC. - Chances for rain continue mid week It appears the GFS is trending towards the ECMWF in that an upper low retrogrades back into the Great Lakes from Ontario mid week. This will bring additional showers to the area and think leaning on the ECMWF is the way to go given it seems to be leading the way. Another stronger shortwave dives into the Great Lakes late in the week which deepens an upper trough overhead. So, showers will likely continue into the Friday and Saturday time frame as well. The bottom line is that we look to be set for a pattern change and to one that is quite a bit more active than we have been seeing of late. - Turning much more fall like mid to late week Temperatures will turn more towards sweat shirt weather as we head through the work week. 850mb temps will be in the middle teens C through Monday night as summer tries to hang on. The bottom drops out though behind the Tuesday front with the coldest air settling in from Wednesday and Thursday. The ECMWF actually has a Zero C temperature over Grand Rapids at 850mb Thursday afternoon. Euro MOS guidance has 59 for a high at GRR Thursday. We currently have low 60s in the forecast, but could see needing to nudge this down. Coolish weather continues into Saturday.