Tag: fall weather

Lake Minnetonka at SunsetPaul Douglas Cool-ish. The maps still don’t look like late October for much of the USA. Prevailing winds are whisking the coldest air well north of the USA; we are just experiencing glancing blows of chilly air east of the Rockies, a pattern which may remain largely intact through the end of October. October Rainfall To DatePraedictix October Rainfall Departures. Rainfall this month is running above average for parts of central and northwestern Minnesota into the Red River Valley and Dakotas – while a deficit lingers for much of southern and eastern Minnesota and much of Wisconsin....

The leaves are leaving, but not before a brilliant, Technicolor explosion of color! Why do leaves even change color? As the days get shorter in the fall, there is less sunlight for photosynthesis. Plants convert carbon dioxide in the air into sugars (glucose and starch) and oxygen by using energy from the sun through the process of photosynthesis. Chlorophyll is the green pigment necessary for photosynthesis. A decrease in photosynthesis that comes with less daylight means trees stop producing chlorophyll. As the green pigment fades over time other pigments present in the leaf are revealed, producing a veritable explosion of...

Weather BlissPaul Douglas Weather Models Are Only A First Guess My father still thinks I forecast weather by looking out a west-facing window. I have nothing against using an “Amish Doppler” to gauge the current state of the clouds and sky. To be able to predict the future one needs to first grasp the present. Meteorologists have dozens of weather models to choose from. Which one works best in a pattern like this? What are the trends in models (wetter, drier, warmer, etc?). George Box said “all models are wrong, but some are useful”. They are merely a guide, not...

Paul Douglas Weather Entering An Unusual Holding Pattern ”Paul, what’s the jet stream up to these days?” Great question. Glad you asked. Upper level steering winds are unusually light for late September. In fact, weather models predict an odd holding pattern into early October as weather systems stall. That’s more typical in mid-July than October, by the way. Warmer air holds more water vapor, increasing the potential for heavier downpours (exhibit A was the soggy remains of Hurricane Ida, a 1-in-1,000 year flood from Philadelphia to New York City). But it’s a 1- 2 punch of wetter systems AND lighter...

Paul Douglas A Taste of Autumn Into Thursday ”80s in late September. Paul, is this a symptom of a warming planet?” Yes and no. Most of this is natural weather variability, amplified by the warming signal we see all around us. Warmer background temperatures (atmosphere and oceans) are flavoring all weather now – today’s rerun of August may be a few degrees warmer than it would be otherwise, in a world where CO2 levels hadn’t doubled since the mid-1800s. Fickle winters, wetter springs (this year notwithstanding) and longer, milder autumns seem to be a trend. Minnesota DNR Low Lake Levels...

File image near Pequot LakesPete Schenck So Why Do We Call This Season “Fall”? Today at 2:21 pm the sun’s direct rays will fall on the equator, marking the official start of autumn. Which is all fine and well, but if you look at the 90 warmest days of the year, on average, “Meteorological Fall” really started back on September 1. The term “fall” may be a contraction of Middle English expressions like “fall of the leaf” or “fall of the year”. And if anyone asks, sex drives apparently peak in the fall. More people go from “single” to “in...