Saturday November 21 2020 Forecast (8:05AM)

37 Comments

DAYS 1-5 (NOVEMBER 21-25)

Discussion…

A cold front will pass by the region today, although the day itself will be pleasant by November standards, just some clouds for a while before sun returns and most areas achieve a high temperature of over 50. As the center of high pressure in southeastern Canada moves eastward it will turn the wind, which is northwest as the front passes, around to the east by Sunday, bringing a maritime air mass into the region with cooler/raw feel being the result. Expect some low clouds to arrive from the ocean as high and mid level clouds stream in from an approaching warm front. For now, I’m expecting the daylight hours of Sunday to remain dry. Things change Sunday night when that warm front gets closer, bringing a threat of rain at the same time areas of drizzle result from the onshore air flow. As previously mentioned, the warm front may have trouble getting northward through the entire area Monday before a cold / occluded front arrives from the west to bring drying but colder air into the region during Monday night. Before that, we’ll have a wet day on Monday with widespread rain showers. Tuesday will be a dry but breezy and colder day with high pressure approaching via the Great Lakes, delivering Canadian cold to our region. While the center of high pressure moves just to our north Tuesday night, a nose of it will extend across the region, so a clear/cold night will result. Wednesday, the high moves quickly off to the east and a southeast to south wind develops here. Expect it to moderate somewhat, temperature-wise, but we’ll also see an increasing cloudiness ahead of the next disturbance. Guidance continues to be very divergent on how quickly this system arrives here, but my best guess for now is that our next rain threat holds off until after the daylight hours of Wednesday.

Details…

TODAY: Variably cloudy morning. Mostly sunny afternoon. Highs 50-57. Wind W 5-15 MPH shifting to N.

TONIGHT: Mostly clear. Lows 28-35. Wind N to NE up to 10 MPH.

SUNDAY: Partly sunny to mostly cloudy. Highs 46-53. Wind NE to E 5-15 MPH.

SUNDAY NIGHT: Cloudy. Periods of rain and drizzle. Areas of fog. Lows 42-49. Wind E to SE 5-15 MPH.

MONDAY: Cloudy with rain showers likely through early afternoon. Areas of fog and drizzle in the morning. Breaking clouds later in the day. Highs 48-55, coolest southern NH and northeastern MA. Wind SE 5-15 MPH in southern NH and northeastern MA, SW 5-15 MPH elsewhere, shifting to W and increasing to 10-20 MPH with higher gusts all areas by late day.

MONDAY NIGHT: Partly cloudy. Lows 27-34. Wind NW 10-20 MPH and gusty.

TUESDAY: Mostly sunny. Highs 37-44. Wind NW 10-20 MPH and gusty.

TUESDAY NIGHT: Clear. Lows 20-27. Wind N under 10 MPH.

WEDNESDAY: Increasing clouds. Rain possible at night. Highs 45-52. Wind SE 5-15 MPH.

DAYS 6-10 (NOVEMBER 26-30)

To give an example of the guidance divergence I have been mentioning, the most recent run (as of the writing of this blog) of the US operational model (GFS) has a dry, breezy, cool Thanksgiving Day while the most recent run of the European operational model (ECMWF) has an overcast and rain day here. My adjusted educated guess for now is a wet morning and drier afternoon for November 26, but I have a feeling further tweaking will be needed. The behavior and timing of that system has an impact on the forecast for the last several days of the month as well. Cautiously optimistic that we have fair and mild weather for November 27-28 and somewhat unsettled weather for the last couple days of the month, but this is very low confidence at this time.

DAYS 11-15 (DECEMBER 1-5)

The first several days of December should see a west-to-east large scale flow aloft, with out area still in that middle ground between a warm US Southeast and a cold Canada. At least one episode of unsettled weather and a couple air mass changes are likely.

37 thoughts on “Saturday November 21 2020 Forecast (8:05AM)”

  2. Thanks TK!

    FWIW, a consensus of ensemble guidance right now certainly suggests winter storm potential over the East for the first week of December. But a lot of time between now and then.

    1. Of course we had a snowy December last year and not much more after that for the remainder of the winter…15.8”

    3. Hi WxW……you the timeframe leading up to December 9?

      Just a reminder that has been my target snow date since 1978 and so far it has produced a handful of major storms…along with some minor

      1. Hi Vicki:) right now it looks like maybe one or two opportunities around 3 to 7 days into the month, kinda centered around 12/6 as TK said. But just for fun that far out, I doubt we’ll know more for a week or so.

    1. Thanks Vicki thanksgiving was to be here but we know how that went . We will be zooming around noontime .

  8. December 5-6, 1981 comes to mind…a “sneaky” snow event to say the least.

    Also December 9, 2005…a Friday iirc.

    2. It was Macs and my wedding day. It rained all day. The change to snow happened just as we left the church for the reception. The place we had our reception has a huge stone fireplace with a wall of windows overlooking a nature preserve in Belmont. It was glorious. We went to the Hyatt on memorial drive that night and looked out over the Charles when we had the thunder snow

        1. It was well over shovelable. Messed up our guests ..especially Macs family who had flown in from their current home in Rome and North Carolina.

  10. Philip the December 9, 2005 event was a Friday. Hurricane force wind gusts on the Cape as that storm under went bombogensis.

    2. To this date, that is the most impressive low pressure system I have seen here, in terms of it’s overall behavior and impact.

    3. Mac took six hours as I recall from Watertown to framingham. At one point when we had the thunder snow we were getting six inches an hour and could not see the houses across the street

      There was thunder snow on dec 9 1978 also

  11. From now on, I’m going to have to focus on the first half of December for potential snow events.

    Expecting a snow event just in time for Christmas itself is a complete waste of time around here. Maybe we should move Christmas Day to December 5th? 😉

      1. Oh yes. I remember now. And the last one before that was 12-25-1974. I got my first Radio Shack (blue) Wx Radio as a Christmas present from my grandmother (Nana). 🙂

        On a side note, that same Christmas I got my first calculator (not a pocket) from my grandfather (Ga-Ga). How ancient the technology was compared to now. 🙂

        Sometimes I wonder if I have been spending more of my Christmases in Atlanta than Boston all my life. So few have had that cold & snow/ “Currier & Ives” theme that a northern city should have. Oh well. 😉

          1. I relate things to events like our wedding and if they don’t line up with an event all bets are off. So no great memory here either

          2. There have been many. But events and/or anniversaries that match up with them always make them easier to remember.

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