Saturday July 18 2020 Forecast

60 Comments

8:21AM

DAYS 1-5 ( JULY 18-22)

3 days of summer heat (will be an official heatwave for any areas that reach or exceed 90 all 3 days). High pressure brings plenty of sun both today and Sunday and the air coming from the southwest will carry increasing humidity by Sunday. Today, we’ll actually see the dew point drop off a little bit as a batch of drier air arrives despite the increasing heat. The most uncomfortable of the 3 days will be Monday when that will be the maximum combination of heat and humidity, dew points closer to or just over 70, and we will also have to add in the risk of afternoon showers and thunderstorms with an approaching trough of low pressure. This will push through Monday night and break the heat and humidity to some degree (no pun intended) Tuesday. A warm front approaches Wednesday with more cloudiness and a limited risk of showers.

TODAY: Any fog dissipates by 9AM, otherwise sunny. Moderately humid then drying slightly. Highs 86-93, but turning cooler in many coastal areas this afternoon. Wind SW up to 10 MPH with coastal sea breezes developing.

TONIGHT: Mostly clear. Moderately humid. Lows 67-74. Wind SW up to 10 MPH.

SUNDAY: Mostly sunny. More humid. Highs 90-97 except cooler Cape Cod / South Coast. Wind WSW 5-15 MPH.

SUNDAY NIGHT: Partly cloudy. Humid. Lows 73-80. Wind SW up to 10 MPH.

MONDAY: Partly sunny. Chance of showers and thunderstorms in the afternoon. Very humid. Highs 87-94. Wind SW 5-15 MPH.

MONDAY NIGHT: Party cloudy. Chance of a shower or thunderstorm early. Patchy fog. Humid. Lows 65-72. Wind W under 10 MPH.

TUESDAY: Partly cloudy. Less humid. Highs 85-92, except cooler some coastal areas especially Cape Cod. Wind W up to 10 MPH.

TUESDAY NIGHT: Mostly clear. Lows 60-67. Wind variable under 10 MPH.

WEDNESDAY: Variably cloudy. Risk of showers. Highs 78-85, coolest coast. Wind SE 5-15 MPH.

DAYS 6-10 (JULY 23-27)

A cold front approaches and passes through the region July 23 with higher humidity and a risk of showers and thunderstorms. High pressure brings drier air and fair weather July 24. Warm front / cold front combo brings a risk of showers / thunderstorms and higher humidity for the July 25-26 weekend. High pressure brings drier air and fair weather back by July 27.

DAYS 11-15 (JULY 28 – AUGUST 1)

West to northwest flow aloft, a seasonably warm to occasionally hot pattern but no lasting or extreme heat expected. Occasional opportunities for showers and thunderstorms but drier than average overall for most of the region.

60 thoughts on “Saturday July 18 2020 Forecast”

  1. I’ve noticed a lot of times when people talk about heat, many automatically assume humidity will be high. Today won’t really be that humid. Dew point drops to near 60 during the day. Slightly humid, yes, but quite a distance from oppressive as well.

    1. I know TK is right about the dew-points lowering today.

      Within a couple miles of the coast, if a sea breeze continues, probably going to have higher humidity.

      Light winds, bright sun, warming airmass, I’m curious to see the Boston harbor water temp this afternoon, IF the sea-breeze holds. If so, 73, 74, take a run at 75 ?

  8. Thank you, TK.

    Humidity hit like a brick wall first thing. ….keeping in mind my first thing today was close to 9:00. Windows were all covered in dew at 5:30

    Then poof. Quite nice this morning.

      1. If it stays away from the sea breeze. I’ll bet that the wind
        flips on shore again shortly. 🙂

          1. At this pace, some place in southern NH/Merrimack Valley are going to end up with around 20 (90F) days and Logan is going to have 3 or 4.

  12. For the 2nd time in the last 3 runs, I think the GFS takes the upcoming mid week disturbance and really closes it off to our east in the Maritimes and has it sit in place or even retrograde a bit in the days 6 thru 8 (at least) time period.

    This turns the 500 mb flow NNW across the northeast, lowers the heights into the mid 570s dm and here´s what many may like …

    delivers what looks like a refreshing airmass to New England.
    80F or so by day, 50s inland at night, 60s along the coast and much lower humidity.

    Of course, is this projection correct or in the ball park ?

    2. I rather keep the nights above 60 to keep the pool warm. Last week the pool lost about 8 degrees

      2. there were some cool evenings and nights last week, to be sure.

        Hopefully, the pool will add those 8F back and then some, the next 3 or 4 days.

    3. Hmmm, with a closed low that close, I would think that
      the possibility of diurnally driven showers and T-storms
      would be a possibility? No?

      1. sounds reasonable. The precipitation projection, on the few I clicked on during that period, looked very empty.

        1. Then, it probably will be mainly dry, but then again, maybe
          we need to get closer for the models to pick up on that?
          I dunno. I do not posses TK’s crystal ball.

  13. I managed to install AC #2 yesterday. I tried moving it
    down from the attic a little differently so that it did not
    bother my back at all.

    Damn, those things are heavy.

    We may still install AC#3. We’ll see how bad it gets.
    I don’t want to install it, If we only need it for one evening
    (tomorrow evening). So far, at night the living room has
    been reasonably comfortable with the windows open.
    I fear tomorrow night it will not be.

  14. 88 at the airport with wind hanging in SW at 5 mph. How that
    is not flipping to on shore, I’ll never know. 🙂 🙂 🙂

  15. There it is. Down to 82 at the airport with ESE wind
    at 12 mph. (DP back up to 68) Nice refreshing sea breeze at the coast. Not making it here, that’s for sure. My equipment
    is reading 94, which means it is certainly 90 here.

    1. Best I can tell, Logan topped out at 88, unless there is a wind
      shift and another 5 or 6PM heat up.-

  16. Thank you, TK!

    Thank you, Tom, for that possible period of a comfortable air mass.

    Today isn’t that bad, actually. As TK said, the humidity is not especially high. That makes a big difference.

    We’re in that time of year – 16 – 24 July – that our average highs are at their maximum. On the flip side, if you will, from 16 to 24 January our average highs are at their minimum.

    1. According to Meso West, Logan reached 90, however, sometimes
      they have rounding issues, so it may have only reached 89 at
      the Airport. Could go either way.
      If it touched 90, then we will have an “official” heat wave.

        1. Without the radiation shield, the Davis Instruments
          thermometer reads up to 4 degrees high in full sunshine
          with high sun angle. Barely affects it in Winter.

    1. The wind just switched here at the beach in Marshfield and it’s like someone turned on a hair dryer. Hot and dry.

  21. Not enough sea breeze to keep Logan away from 90, as you saw. SAK will attest to how “fun” it can be trying to forecast things things.

    Another thing that both SAK & I often refer to is how much the models can suck after day 3 or 4. Well, take a look at the divergent forecasts for next Saturday & Sunday between the ECMWF & GFS. One of them is going to be way off, or both of them are going to be kind-of bad. 😛 Time will tell.

  23. Wow! DP down to 54 at the airport. I guess the dew points
    came down. Earlier this morning dp was 70 at Logan. That is a drop of 16 degrees!! Impressive!

    1. That is a great example of mixing !

      No such luck down here. Marshfield´s dp runs high, but as of 7pm, surrounding area dewpoints are in the upper 60s.

  24. TK,SAK, JMA and/or WxWatcher

    How come on air mets did NOT have a clue to this drop
    in the DP today? All I heard from Wankum was how HUMID
    it was going to be today.

    Why don’t we see the class of you 4 in on air mets? We just
    don’t see it very often. Sometimes Eric and Harvey show flashes, but still don’t measure up imho. Just saying.

    1. I did notice Petey B. talking about it last night. NWS was on it as well if you look at their hour by hour projections.

      1. Fair enough. I can only say for certain that Wankum did not.
        Not for nothing, but I do not think he is that good. We like
        the news on Channel 5 better, so we switched from 4.
        I miss watching Eric.

  26. Pleasant evenings on-going in both Minneapolis, MN and Chicago, IL

    Minneapolis: 86F, dp: 79F, heat index: 100F

    Chicago, IL: 88F, dp: 77F, heat index: 100F.

  27. Per 00z NAM, hr 42 to 45, highest heat index Monday might be located around Boston to Providence corridor and down into SE Mass.

    Pooling of humidity ahead of front, NAM projects 70F to 75F dewpoints at 2pm Monday, then slowly dropping during the late afternoon.

    N and W of Providence to Boston, the NAM projects lower dps in the mid 60s, then slowly falling late afternoon.

  29. High clouds did a number on the ability to view Neowise this evening. Should be better tomorrow.

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