Saturday November 14 2020 Forecast (9:12AM)

19 Comments

DAYS 1-5 (NOVEMBER 14-18)

Discussion…

Today will be a day of cold air advection. What does that mean for today in particular? It means that we’ll be delivered a modified cold air mass from Canada, although with temperatures already having dropped due to an overcast/wet/cool day yesterday and some clearing last night, what will really happen today when you factor the incoming cool air with the diurnal warming of sunlight, the temperature really just won’t go up that much. It will feel even cooler than it is because of a developing gusty breeze, as well as some passing patches of cloudiness, the result of a leftover layer of moisture a few thousand feet off the ground and incoming colder air above that. There may be enough initial instability for a few sprinkles of rain, with this most likely occurring north of I-90. These clouds will dissipate this evening and the wind will drop off as high pressure moves across the region. This is a recipe for radiational cooling, when any warmth of the sunlight radiates quickly out toward space and the temperature drops off. It may drop significantly enough to match the dew point in some interior lower elevations, which would result in patches of fog forming. Sunday, the high pressure area will move offshore and we’ll have a warm front pass by in the morning and midday hours, which will introduce a warmer southerly air flow for the balance of the day, setting the stage for a round of showers (maybe even a rumble of thunder) as a pretty potent cold front approaches from the west by evening, parented by low pressure tracking eastward and passing north of our area Sunday night. Besides the risk for brief heavy rain showers, we’ll have to watch for some strong wind gusts, as the air not that far above us will be blowing strongly, and any heavier showers can drag some of this wind down to the surface in gusts. Thankfully with a lot of the trees now having lost most of their leaves, this should lessen the chance of damage and therefore reduce the power outage chances. However, there still can be some isolated damage & resulting outages as this front and its band of showers crosses from west to east. Monday will be another cold advection day with plenty of wind and a sky of sun and passing clouds. A disturbance will move this way via the Great Lakes on Tuesday and bring plenty of clouds along with a chance of a few rain and/or snow showers as it will be chilly at the surface and cold aloft. This system is gone by Wednesday and high pressure in the Great Lakes will deliver a solid cold air mass from Canada. There may be a few isolated but insignificant snow flurries around on Wednesday.

Details…

TODAY: Sun/cloud mix. Brief very light rain showers possible mostly from Boston north and west during midday. Highs 47-54. Wind NW 5-15 MPH, gusts 20-25 MPH.

TONIGHT: Clearing. Patchy ground fog low elevations. Lows 30-37. Wind NW 5-15 MPH early, then diminishing to near calm.

SUNDAY: Increasing clouds. Highs 53-60. Wind S 5-15 MPH, higher gusts in the afternoon.

SUNDAY NIGHT: Cloudy with an episode of rain showers, possibly heavy, including a slight chance of thunder, during the evening. Clearing overnight. Lows 40-47. Wind S shifting to W 10-20 MPH with higher gusts, with a few gusts 30-50 MPH possible during the passage of the showers.

MONDAY: Sun and passing clouds. Highs 47-54 occurring in the morning then falling through the 40s. Wind W 10-20 MPH, gusts 25-35 MPH.

MONDAY NIGHT: Variably cloudy. Lows 30-37. Wind NW 5-15 MPH.

TUESDAY: Mostly cloudy. Chance of rain/snow showers. Highs 38-45. Wind W 10-20 MPH.

TUESDAY NIGHT: Mostly cloudy with a chance of snow showers early, then clearing. Lows 23-30. Wind N 10-20 MPH.

WEDNESDAY: Partly sunny. Slight chance of a passing snow flurry. Highs 35-42. Wind N 10-20 MPH.

DAYS 6-10 (NOVEMBER 19-23)

High pressure slips off to the south of New England and milder weather results for the early part of this period, before a frontal boundary slips to the south again with some briefly unsettled weather, followed by seasonably cool and drier weather.

DAYS 11-15 (NOVEMBER 24-28)

Thanksgiving Week Outlook: Trend continues to be for our area to be in a battle zone between a warm US Southeast and cold Canada. This creates the opportunity for some unsettled weather and temperature variation. There are some shifts in guidance resulting in model divergence but not going to read into that too much at this time, hence keeping the outlook unchanged.

19 thoughts on “Saturday November 14 2020 Forecast (9:12AM)”

  1. Free webinar for the virtual mini SNE Weather Conference going on right now. Mish Michaels, first speaker, going thru winter outlook now. Excellent so far. Great to see her. Wish this could be in person – targeting next year for a return to the traditional conference. 🙂

        1. I have been in for awhile. I can’t stay much longer.
          Pretty interesting. Excellent discussion of the
          Cape tornadoes last Summer.

          1. The entire conference was excellent.

            Mish with the winter outlook which was her going over forecasts for several sources – very well done!

            Charles Orloff from Blue Hill Observatory & Hayden Frank from NWS on the Cape Cod tornadoes.

            Andy Nash (the new MIC at NWS Boston) outlining ongoing and upcoming changes / streamlining of products/terminology. Very informative. Bob Thompson is not an easy set of shoes to fill but I think Andy will do a wonderful job.

            I give the webinar 5 out of 5 stars. 😉 They did a great job. If I heard correctly there were about 165 people watching, which is an excellent virtual turn-out, very close to the in-person attendance of a regular conference! That is encouraging for next year, when they hope to have an in person conference (target date Oct 23 2021).

            1. I saw Charlie, Hayden and Andy.
              I was fascinated by the Cape Cod tornados presentation.

              They introduced a new term to me:

              0-3KM CAPE and how very important that is for tornado development. Next season, you can be sure I will looking for that.

              Care to weigh in on that?

              Also, Andy’s presentation on the NMB was quite interesting as the NWS
              is introducing a new model blend called
              National Blend of Models (NBM).

              For those interested check it out:

              https://www.weather.gov/mdl/nbm_home

              1. That 0-3km CAPE is a big factor in the development of the types of tornadoes we see in this area. Pay close attention to that. I think we’ve had more of these events than we’ve even recognized, and as I have stated previously, we only “see” things better now, so we miss far less than we used to.

  2. An important take-away from today’s virtual mini SNE Weather Conference, and something I have been meaning to bring up but forgot to mention previously – starting next year we will be going by the climate averages for the past 30 years (1991-2020). Since 1991 we have been using the 30 year averages for the period 1960-1990. That’s about to change. This is done to make comparisons more directly related to trends in the last 3 decades, which makes more sense, given the long term nature of climate shifting (all aspects of climate, not just temperature, but precipitation, etc.).

    Boston’s average snowfall of 44 inches will likely increase to 48 or 49 inches for the next 30 years, to reflect the upward trend in snowfall during the last 3 decades. That’s just one example. Temperatures will also be adjusted not only at Boston, but nationally. This is nothing new. It’s just done every 30 years, so the subject is not brought up that often unless you are a climatologist / researcher. 🙂

    1. I suspect that Boston’s nearly 50-inch snow total will mostly reflect the two very anomolous snow seasons of 1995-96 (107.6”) and 2014-15 (110.6”). I understand that the 30 year average needs to be upgraded but I do wonder if it ends up a bit misleading for an “average” Boston winter.

      Well, it’s better than in the “other”direction. 🙂

      1. It’s not really misleading, because you are bound to have some extremes in both directions regardless of what you are measuring. This is why they do a 30 year average and not a 10 year average. The skewing is less of a factor.

    1. It very well may be. They did not say that it would or would not, but it can’t hurt to email and ask them. 🙂 There’s no info in there that can’t really be made public, so I’d think they should put it there.

  4. TK, I took a look around at several models (HRRR,HREF and SREF, GFS, NAM, NAMK 3KM, RAP, RDPS and GDPS) and did not
    see any available to me show the 0-3KM CAPE.

    Could possibly provide a link to a site where this parameter would be available to the general public.

    I am at a loss and would dearly love to access to this.

    Many thanks

  5. Thanks TK, and thanks for all the notes about the conference!

    I would’ve attended, but I’m working a stretch of overnights so it didn’t really fit in with that. Hoping they make a recording available and definitely hoping for a return to an in-person format next year. I got to meet Andy Nash at the AMS conference in January, he’s a little bit of a character but completely agree that he’ll do a great job. A lot of change in the works at the NWS, both nationally and at Boston, but I’m optimistic for the years ahead.

    JPDave – off the top of my head I don’t recall any sites that show 0-3km CAPE, but I’ll let you know if I stumble across it, I’m sure it’s out there.

  6. As TK covered well above, watch for a period of strong to locally damaging winds tomorrow evening/night. Always tough to tell how much wind will mix down in these southwesterly low-level jet cases. To me it looks like a case where most of the wind will not make it down, but there could be some exceptions especially towards the coast or southeast MA. I like TK’s range of 30-50mph gusts, locally a little higher where I mentioned. Wouldn’t be surprised to see Blue Hill gust in the 50-75 mph range either with that little bit of extra elevation.

  7. From NWS Boston for Sunday Night
    One thing we will need to keep a close eye on is several pieces of guidance develop a low along the triple point in western portions of the CWA as the front is sliding in. This has a tendency to increase the low level shear and could result in rotating storms.

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