Monday September 20 2021 Forecast (7:28AM)

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DAYS 1-5 (SEPTEMBER 20-24)

High pressure will be the dominant force in our weather through Wednesday, and at least into if not all the way through Thursday too. As the high center, which is just to the north of our area now, slides offshore toward midweek, the transition will be from low dew point weather with cool nights and mild days early week to a more humid southerly air flow by midweek. The biggest weather question remains the timing of the next trough and frontal system from the west. At one point, guidance was aiming at Wednesday / Thursday for this, and as we’ve gotten a little closer the guidance remains spread on timing with the quickest model bringing the most rainfall through the region Thursday, and the slowest guidance indicating most of the rainfall will occur later Friday through Friday night. For this update, I am making no changes in the timing from yesterday’s post, but don’t be surprised if additional tweaks are going to be needed. For now, just “reserve” late Thursday through Friday as the potential unsettled time period. Rewinding back a bit, a reminder that summer ends and fall arrives with the autumnal equinox at 3:20 p.m. EDT Wednesday September 20, and back a bit more, look for the rise of the full Harvest Moon tonight just after 7 p.m., reaching it’s “peak fullness” at 7:55 p.m. as it sits low in the eastern sky on its rise and will light the landscape brightly all night.

TODAY: Sunny. Highs 68-75. Wind variable to E up to 10 MPH.

TONIGHT: Clear except patches of ground fog forming in lowest elevations. Lows 47-54. Wind calm.

TUESDAY: Sunny. Highs 68-75. Wind variable to E up to 10 MPH.

TUESDAY NIGHT: Clear. Patchy ground fog interior lower elevations again. Lows 55-62. Wind SE under 10 MPH.

WEDNESDAY: Mostly sunny to partly cloudy. Highs 72-79. Wind S 5-15 MPH.

WEDNESDAY NIGHT: Partly cloudy. Lows 56-63. Wind S 5-15 MPH.

THURSDAY: Partly sunny. Highs 73-80. Wind S 5-15 MPH.

THURSDAY NIGHT: Mostly cloudy. Chance of showers overnight. Lows 60-67. Wind S 5-15 MPH, higher gusts.

FRIDAY: Mostly cloudy. Showers likely. Highs 68-75. Wind S 10-20 MPH.

DAYS 6-10 (SEPTEMBER 25-29)

The weekend forecast depends highly on the speed of the frontal system moving in late this week and how quickly it departs the region. Leaning toward the potential for early showers September 25 with the departure of that system on the slower side, and late-day showers September 26 with the approach of the next one from the west, with rain-free weather for the bulk of the weekend in between. Still adjustments are likely to be needed. Potentially unsettled weather into September 27 and one more shower threat near the end of the period as we start a cooling trend.

DAYS 11-15 (SEPTEMBER 30 – OCTOBER 4)

More west-to-east flow is expected, with a bit more northwesterly flow possible, which means minor shower threats with passing fronts and an overall cooling trend. With uncertainties in the pattern leading up to this, this is still a low confidence forecast at this time.

18 thoughts on “Monday September 20 2021 Forecast (7:28AM)”

  5. Thank you, TK.

    Good weather for the annual changing of the colors of leaves. Vicki’s note that the temperature fell to 47F in Sutton, MA, and then quickly rebounded is absolutely perfect for the process that turns leaves into oranges, reds, and yellows.

  7. Thanks TK.

    I find it ironic that as soon as “fall” arrives we go back to the YUCKFEST that we have been accustomed to much of this summer. Oh well.

    1. We’re only going to have a relatively short period of unsettled weather, then back to drier with a cooling trend.

  9. Wooly Bear Caterpillar aka Woolyworm: Very wide brown band this autumn.

    What does that mean for winter? Absolutely nothing. Caterpillars cannot predict the future. Neither can wasps, nor trees, or any of that stuff. It’s all completely false, but fun folklore nontheless.

    1. But I have heard that, just maybe, a weather vane can actually control the weather:

      Good morning Weathercock
      How’d you fare last night?
      Did the cold wind bite you
      Did you face up to the fright
      When the leaves spin from October
      And whip around your tail?
      Did you shake from the blast
      And did you shiver through the gale?

      Give us direction, the best of goodwill
      Put us in touch with fair winds
      Sing to us softly, hum evening’s song
      Tell us what the blacksmith has done for you

      Do you simply reflect changes
      In the patterns of the sky
      Or is it true to say the weather heeds
      The twinkle in your eye?
      Do you fight the rush of winter
      And hold snowflakes at bay?
      Do you lift the dawn sun from the fields
      And help him on his way?

      Good morning Weathercock, make this day bright
      Put us in touch with your fair winds
      Sing to us softly, hum evening’s song
      Point the way to better days we can share with you

      – Ian Anderson

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