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Plenty to sneeze at

It’s bad out there, a veritable jungle of windblown pollen, ragweed, unspeakable allergens floating overhead. One big HOT ZONE. A colleague of mine at WeatherNation told me his allergies are worse this year than any time since his childhood. Sneezing, wheezing, sniffling, it’s a wasteland of Zyrtec and Clariten – anything to ease the symptoms. Our dry spell has made the situation much worse than normal: 14 days of dry weather in a row, no rain to pull these natural pollutants down to the ground. They accumulate over time, and frankly, no significant improvement is likely until the first widespread frost, which is at least 3-4 weeks away. So these are my choices: sneeze myself silly, or pray for frost? Great. Thanks Paul.

The Unofficial State Flower: Goldenrod
. Yes, pull your car over to any ditch beside any highway in Minnesota, get out and grab a handful of goldenrod for that special someone in your life. If you want to score some points put a little bouquet of goldenrod on the kitchen table. See if your significant other has a sense of humor. And then count the seconds before the shouting and screaming begins.

Yesterday’s cool frontal passage was a bust, the front fizzling as it tracked east. Showers and T-storms sprouted just south of the Twin Cities metro during the evening hours, there were even a few reports of pea-size hail and downpours, mainly over the southern suburbs, where some .25 to 1″ rainfall amounts were reported. It was the first rain in these neighborhoods in 2 weeks, welcome raindrops indeed.

Dopper Radar from the MPX National Weather Service site at 6:45 Wednesday evening, showing heavy showers and thunderstorms over the southwestern suburbs. Doppler estimates of 3″ were reported near Glencoe, closer to .25″ at Delano.

Estimated Rainfall from Wednesday’s late PM downpours. Such is the fickle nature of summer “convection” (ie: shower activity) that sprouts, dumps heavy rain over a few thousand square miles, and then dissipates as quickly as it formed. These instability showers and T-storms formed along a weak cool frontal boundary – it provided just enough lift to break through a stable layer, the result: a few hours of mushrooming showers and towering thunderheads south/west of the cities. Note the 3-4″ (red) rainfall bullseye between Glencoe and Gaylord. In spite of all the computational horsepower at our finger tips, it’s still virtually impossible predicting, more than 2-4 hours in advance, where the heaviest rains will set up. This is the real frontier: the “nowcast”, the next 6-12 hours, trying to pin down which suburbs will see the heaviest rains well in advance.

Skies clear Thursday, the sun should be out, temperatures topping 80 degrees, another pleasant taste of mid August. The next cool front arrives late Friday with another spirited round of showers, a few of which will linger into Saturday as the weather machine begins to slow down and stall out early next week. The last few computer runs have been hinting at a “cut-off low” situation, a cold, stormy swirl cutting off from the main belt of westerly jet stream winds – spinning like a top just to our south/west, keeping us gray, cool, showery and unsettled into the first few days of next week. Once the pattern becomes cut off, it can remain stuck in this rut for day after day, sometimes a week or more. It’s unclear just how long we’re going to be impacted by this stalled, cut-off low, but the trend should be toward cooler, more showery weather as we move into next week. No cold fronts, nothing harsh, or severe is in sight, no ragweed-killing frost or early flakes (watch your mouth Paul!) and it still looks like 70s for highs the latter half of next week into the weekend of September 19-20; I wouldn’t be shocked to see 80 return, not this upcoming weekend, but the following weekend.

500 mb winds predicted for Sunday morning, 1 am. This shows winds at about 18,000 feet above the ground, showing the “cut off low” stalling just to our west across the Dakotas. The chance of showers, especially PM instability showers, will probably be greater the farther west you live in Minnesota early next week.

WRF/NMM Model Output for Saturday evening at 7 pm. This map shows predicted rainfall from 1 pm to 7 pm Saturday, hinting at a few hours of showers on Saturday. Have a Plan B (indoors) for at least part of the day – but at this point I still do NOT see an all day wash-out.

September is prime-time for fog and hurricanes….mercifully we only have to deal with the former. Fog peaks this month, when the atmosphere is still moist from persistent southerly breezes, pumping in humidity from the Gulf of Mexico. But the nights are getting much longer, giving the temperature more of a chance to fall to the dew point. When that happens, temperature = dew point, the relative humidity reaches a whopping 100% The air is said to be saturated, clouds form, and when that cloud forms on the ground we call it “fog”. Of course fog is much more likely to form in a river valley (moisture source) and residents of the Minnesota and Mississippi River Valleys are probably waking up to a touch of fog this morning.

Paul’s Outlook

Today: Foggy start in some areas. Plenty of warm sunshine. Winds: South 5-15. High: 83

Tonight: Mostly clear, relatively mild. Low: 61

Friday: Sunny start, clouds increase. High: 77

Friday night: Showers likely, possible thunder. Low: 59

Saturday: More clouds than sun, a few hours of showers. High: 74

Sunday: Mix of clouds and sun, late PM shower possible. High: 75

Monday: More clouds, better chance of showers. High: 73

Tuesday: Mostly cloudy, cool and unsettled, a few more showers. High: 71

Wednesday: Partly sunny and milder. High: 75

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Comments (1)

  1. Submitted by Jarrett Smith on 09/10/2009 - 01:55 pm.

    Paul, your going to have to choose another plant.
    This is from

    (Goldenrod is NOT responsible for your allergies. The pollen is heavy and sticky, designed for insect pollination, not wind. The only way to get goldenrod pollen in your nasal passages is to stick the flower up your nose! Wind-blown ragweed pollen is the most common culprit for allergies.)

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