“By all these lovely tokens September days are here, With summer’s best of weather And autumn’s best of cheer.” -Helen Hunt Jackson
September swan song
It’s easy to wax poetic about late September in Minnesota. The nights are finally crisp. The trees a tapestry of color. The sky turns a classic shade of autumn blue.
Yes, it felt good to see the sun return to Minnesota skies today.
Our weather maps seems finally in tune with the calendar. It’s hard to believe October arrives Sunday. Forecast models are often in flux a week out this time of year. Summer’s lazy, slow-moving atmosphere is fading. A faster, more unstable jet stream can produce bigger changes as we move into October. The forecast models often play catch up during this seasonal transition.
In the short term we enjoy sunny days and longer, cooler nights.
Tale of two seasons
Fall usually finds the Rocky Mountains and Upper Midwest first. Today’s national temperature map shows the distinct difference between a lingering summer air mass to the south and the inbound hues of autumn.
High and dry
When I talk with younger children over the years about weather I basically ask them to remember two basic concepts. High pressure brings fair weather. Low pressure brings storms.
Seasonably cool high pressure dominates Minnesota’s weather through Saturday. That means more sunshine. The next real rain chance rolls in on Sunday. Here’s Canada’s GEM model.
Temperatures in the 60s blanket most of Minnesota the next few days. The best shot at 70 in the Twin Cities and southern Minnesota is Thursday and again next Tuesday.
NOAA’s GFS still hints at 80 degrees next Thursday. The Euro (ECMWF) and Canadian GEM are not so sure.
Birds on Doppler
Military radar operators in World War ll tracking enemy planes noticed big smudges on the radar scope. What tuned out to be rain launched an entire subset of weather forecasting called radar meteorology. NOAA’s new Dual Polar radars are so sensitive now, they can see birds or even insects in what’s known as “clear-air mode.” The Doppler at NWS Milwaukee picked up these cool images.
Can you spot the birds departing at sunrise? (Hint: Look for the rings) The radar is very sensitive in this mode. pic.twitter.com/OOrCQnRGYn
— NWS Milwaukee (@NWSMKX) September 27, 2017