Models: Backing off on magnitude of heat the next few days?

97 degrees NAM model forecast for Friday’s high temp yesterday

88 degrees NAM forecast for Friday on last night’s (7pm) run

-9 degrees drop in magnitude of Friday’s heat according to NAM model

22 days at or above 90 degrees so far this summer

1-2 days & possibly 3 days of low 90 degree heat in the next week?

(trend from latest model runs)

More days in the 80s than 90s the next 7 days?

90 wxs.PNG

Source: Twin Cities NWS

Not so hot?

There’s a noticeable trend in the latest model runs that started Wednesday evening.

Virtually all models have been trending a few degrees cooler in the past 24 hours. The NAM, Euro, GFS, RAP all seem to be converging on a very warm….but not brutally hot stretch of days from today right through most of next week.

In fact, other than a couple of potential days just above 90 this weekend, it may feel almost downright typically “July-like” over the next week.

It’s still going to be very warm (and above average) this weekend and into early next week, but the latest trends suggest we may avoid several days in a row above 90 degrees again.

90 90.PNG

Source: Iowa State University

The NAM model has been handling the recent heat spikes better than any other model. Last night’s NAM run dropped the forecast high temp for Friday a full 9 degrees, from 97 to 88 degrees.

It also dropped dew points several degrees, and now favors low 60s, or even upper 50s dew points Friday into Saturday.

Even the ECMWF (European) Model is cranking out temps mostly below 90 in the next week.

European Model Forecast #’s/GFS

Thu 77/85

Fri 83/87

Sat 84/90

Sun 86/88

Mon 91/92

Tue 86/89

Wed 88/89

Thu 90/84

It will be interesting to see if todday’s model runs confirm this trend.

What’s happening?

It appears a slight southward shift in the position of the big upper level heat pump high that’s been baking the nation may be enough to allow the edge of Canadian high pressure to linger over Wisconsin the next few days. That means a light, but important east wind may ease into Minnesota. Local forecasters know an east breeze is not our warmest wind, and slightly cooler air may hold temps at bay a few degrees, especially in eastern Minnesota.

Temps may just reach 90 this weekend in the metro, with mid 90s held off into southwest Minnesota. If the latest model trends verify, the Twin Cities may escape with just 1 or 2 days at or above 90 in the next week…which would put us at 24 or 25 before the heat wave appears ready to break for a while late next week.

The latest model runs still bring high in the 70s to near 80 at best (and comfy dew points in the 50s) late next week in the metro.

NOAA’s CPC is finally picking up on the trends, and has shifted the core of the heat wave south into the central USA in the 8-14 day range.

90 14 day outlook.PNG

Source: NOAA’s Climate Prediction Center

Stay tuned!

Hot streak is over:

Showers and cooler temps brought our string of 21 consecutive days at or above 85 degrees came to a screeching halt Wednesday. Details from the Twin Cities NWS.

90 streak.PNG

Source: Twin Cities NWS


  • RalfW

    Hey Paul,

    I’d be very interested in data about overnight lows. It seems like we’ve had a lot of nights where the lows have been in the upper 70s or very close to 80.

    Could you compare that to other years? I’m particularly interested in overnight lows in greater MN.

    I’ve camped in the Superior Nat’l forest 8 to 12 days a year (over two trips) every summer since 1995. My sense is that the overnight lows have moved warmer much more than the highs.

    Back here in the city, it seems the A/C just doesn’t get a break or a chance to ‘catch up’ at night like it used to.


  • Disco

    What is the “NAM model?” The North American Model model?

  • Doug T

    Interesting. We always talk about August being the big heat month in Minnesota, but looking at the top 10 streaks for each category, 80% of them were (mostly) in July. If you expand that to the last week of June to the 1st week of August it goes up to 90%. I guess come the end of June next year, Paul, you’ll have to warn us that our “hot streak” period is upon us! No wonder my plants hate it when I go away in July.

  • John Lamb

    @disco Correct. It is the North American Mesoscale Model.