ANOTHER DAY, ANOTHER BEAUTY...
The weather powers have been smiling on the Midwest this week with some fabulous late summer weather. Temperatures Thursday were at mid-August levels but fortunately humidity was not. Thanks to high pressure and the dry air associated with it, the only rain the past 24 hours was far to the northwest.
Temperatures early Thursday afternoon were well above normal over the entire Midwest with some very large departures noted in Minnesota.
The relatively straight forward aspect of the forecast continues for another day Friday with another dry, breezy, warm day on the table. Highs in the low to mid 80s are expected areawide. The only change will be somewhat higher dew points which could hit the mid 60s in spots. Still manageable though.
Things get more complicated over the weekend as the ingredients come together for at least scattered showers and thunderstorms to roam parts of the area this weekend. The first opportunity comes in my counties west of the Mississippi early Saturday in the form of some remnant convection from overnight storms in central Iowa. This is tied to a slug of warm advection and an upper level disturbance. What's left should be in a weakening state and I don't look for much out of this wave in my area.
That should leave us with a dry Saturday afternoon which allows highs to get back into the 80s. There will be some humidity too deal with as well.
Saturday night low level moisture will be impressive by September standards and with the low level jet ramping up thunderstorms look to be a good bet Saturday night. How widespread and precisely where is the question I'm dealing with right now. Currently my counties in eastern Iowa are most favored for what does develop. A few of these could produce some marginal severe weather with the primary concern being heavy downpours and lightning.
The remnants of this activity should depart early Sunday leaving a window for heating and instability Sunday afternoon. Again with highs in the 80s and plenty of moisture new storms could develop late Sunday afternoon or night along a slow moving cold front. Any of these would have the ability to produce localized heavy rain. Again, mesoscale details unknown at this distance will play a big roll in what ultimately happens. It could be much of the daylight hours Saturday and Sunday end up dry with nocturnal processes keeping much of the rain that falls confined to the overnight hours. The precise location of forcing will tell the tale in the end. For now, here's what models are suggesting for rainfall Saturday through Sunday night. Quite a bit of variance as you can see.
THE NBM (national model blend)
The Weather Prediction Center
The 12K NAM
After Sunday, the forecast looks generally dry with the primary focus being unseasonal warmth. Tuesday and Wednesday should be the warmest days with highs likely reaching the upper 80s, perhaps 90 in spots. Here's what the EURO meteogram indicates for temperatures the next 10 days.
Here's the average 5 day temperature departures during the peak of the heat Saturday through next Wednesday.
The big take away Friday is that breezy, warm conditions will take us into the weekend with a healthy helping of summery conditions. Enjoy the feast. Roll weather...TS