Wednesday July 21 2021 Forecast (7:52AM)

84 Comments

DAYS 1-5 (JULY 21-25)

Today, we still have the smoke in the atmosphere, both upper and lower, fairly high humidity, and a thunderstorm threat (for parts of the region). Tomorrow, we lose all of it and gain one of the nicest days of the summer. To get there, we have to go through a transition today as a disturbance moves across the region. Previous chatter was a little more inclusive of the entire region in a significant thunderstorm threat, but one must keep in mind that weather in the hours just before can impact weather in the hours just after, and if using short range models for guidance, it’s essential to watch trends on those as well as keeping track of what’s going on via surface obs. Last night, some of the convection from yesterday’s activity to the west survived its trip east, even a bit more so than I expected it to, and one thing this has done is to stabilize the atmosphere in a good part of the region north of I-90, and it is these areas that have the smaller risk of showers and storms today, just some isolated activity popping up early or mid afternoon. To the south, closer to where today’s disturbance will pass, and with less stable air, look for a little more in the way of shower and thunderstorm activity developing and moving in during the afternoon and into the evening. It is still quite possible that a few of these storms may become severe with damaging wind being the most significant threat, but also some chance of larger hail as well. All of this activity moves away later tonight and is replaced by a dry air mass from Canada. Even though a lot of our wild fire smoke has originated in Canada, the shift in the winds both surface and aloft will be enough to remove most of the smoke from our region, and Thursday should feature a deeper blue sky than we have seen in quite a while, not that we’ve seen much of any blue sky this month anyway. You may be wondering if this is temporary and we’re going right back to the pattern we’ve been in. Actually, not this time. The pattern is changing for now, and even though a disturbance has to swing through the region on Friday with some clouds and the threat of passing showers, we’ll be introduce to fresh Canadian air, part 2, on Saturday. But things are moving along and the next disturbance will be on the way by Sunday, once again with more cloudiness and the threat of some shower activity. The difference now is that we’re not seeing these frontal systems move in then sit around for a few days, creating stretches of unsettled weather…

TODAY: Mixed sun, clouds, and wildfire smoke. Isolated showers and thunderstorms north of I-90 midday through mid afternoon. Scattered showers and thunderstorms I-90 belt southward mid afternoon to early evening, with any thunderstorms potentially severe (hail, wind damage). Highs 77-84. Dew point middle to upper 60s. Wind W 5-15 MPH, variable and potentially stronger around storms.

TONIGHT: Partly cloudy. Lows 57-64. Dew point falling to middle 50s. Wind NW 5-15 MPH.

THURSDAY: Mostly sunny. Highs 76-83. Dew point upper 50s. Wind NW 5-15 MPH.

THURSDAY NIGHT: Partly cloudy. Lows 58-65. Dew point middle to upper 50s. Wind W under 10 MPH.

FRIDAY: Partly sunny. Chance of showers, mostly morning through midday. Highs 73-80. Dew point near 60. Wind W 5-15 MPH.

FRIDAY NIGHT: Mostly clear. Patchy ground fog lower elevation areas. Lows 55-62. Dew point falling to middle 50s. Wind NW up to 10 MPH.

SATURDAY: Mostly sunny. Highs 76-83. Dew point upper 50s. Wind W 5-15 MPH.

SATURDAY NIGHT: Partly cloudy. Lower elevation fog patches. Lows 57-64. Dew point upper 50s. Wind W under 10 MPH.

SUNDAY: Variably cloudy. Chance of showers. Highs 76-83. Dew point lower 60s. Wind W 5-15 MPH.

DAYS 6-10 (JULY 26-30)

A westerly air flow pattern will feature drier than average conditions and near to below normal temperatures, often seeing air coming from Canada. Best chance for an interrupting disturbance with showers mid period.

DAYS 11-15 (JULY 31 – AUGUST 4)

Overall pattern keeps us in a west to northwesterly air flow, with no major heat, temperatures near to slightly below normal, and a drier overall regime with fewer shower chances.

84 thoughts on “Wednesday July 21 2021 Forecast (7:52AM)”

  4. Good morning and thank you TK.

    I just don’t feel super charged about storms in Boston today.
    We shall see.

  5. Thanks TK. Hope the worst storms stay farther south, even though I am a few miles south of the pike. Charles river in south Natick below flood stage but falling very slowly.

  8. Thank you, TK. If we had a storm in the night, I slept through it

    I copied the first part of your commentary and sent to my oldest. She will be 41 tomorrow……really, I can’t have a 41 year old. They have been hoping to head to Humarock. Looks as if that will happen

    We had a severe thunderstorm 41 years ago….right around midnight.

  11. On the other hand, our Norton NWS office appears to be
    a bit bullish on thunder storms today.

    Sharpening upper trough will move across New England today. The
    area leading the trough will feature a 90-kt upper jet and
    sufficient jet forcing to encourage lifting the the airmass. The
    southwest flow will also maintain a warm humid and unstable
    airmass over Srn New England. A cold front over the St Lawrence
    Valley and Western NY will move southeast today. This will
    provide low-level convergence to focus the developing updrafts.

    Model CAPE shows afternoon values of 2000 to 2500 J/Kg; model total-
    totals shows values of 53 to 55 this afternoon; model Lifted Index
    values range from minus 5 to minus 9. Cold advection aloft will
    bring 500-mb temperatures down to minus 14 and increase temperature
    lapse rates, adding to the instability. The bulk shear values reach
    30-35 kt this afternoon, suggesting further organizing of any
    updrafts. Most favorable values are over CT, RI, and SE Mass.

    Putting it together, there is potential for development of
    buoyant thunderstorm updrafts with straight-line winds and hail,
    possibly enough to cause damage. SPC shows similar thinking with a
    slight risk, their second level of concern, for areas south of the
    Mass Pike and a marginal risk for northern parts of
    Massachusetts.

  12. Logan DP is only 63 while Norwood is 68. That is a HUGE difference when it comes to firing off T-storms.

    I have dp 67 here with temp ONLY 74.

    1. Very nice. thank you.
      At the current rate of temperature rise, won’t be necessary today.

      It is remarkably unhot today (so far) 🙂

  14. It is now after 11AM and radar is awfully quiet. Only convection is down in Eastern PA.

    Will convection fire or will this be a bustorama?

    1. Less.

      The nocturnal stuff stabilized things a lot.

      This is a great example backing up my statement the other day about convective forecasting.

  16. Thanks TK.

    About that 3km NAM run yesterday, eh 😉 This is a classic case of poorly handled convection the prior day totally changing the game for the next day.

    Definitely looks like a reduced severe potential for SNE today, though I think portions of eastern CT, RI, and east/southeast MA are still in play. But the better chances should be down my way in NJ. Off work today so there may be some storm chasing involved….

  17. Not a cumulus cloud to be seen down here at the moment. Dp’s definitely feel a bit lower. Very hazy sun, getting above 80F.

    1. Too hazy to see much cloud formation. I don’t see any cumulus building to the south. DP dropped from 65 to 63

    2. I wonder if WxWatcher is cruising around the Atlantic City area getting a first hand look at those storms????

      1. You don’t like nice weather? OR you think it might be a bit
        too cool to really enjoy the beach and swimming?

        1. Second part . Speaking for me only I need sunny warm days to be at the beach ( not hot but 80s weather . The water is cold usually so a cool day will be a not so good feeling at the beach . I’ll hold off until I get the detailed weekly outlook .

          1. I am with you 100%.
            I can only go in the water if it is reasonably warm to hot out. Cool weather is great for other activities, but NOT swimming.

        1. True, but will it be warm enough for his liking? that is the question. 🙂 Hope so.

          PM temps mid 80s dp mid 50s. PERFECT!!!!

          1. Near to below normal temps & below normal precip in late July / early August is ideal. The sun is hot out there! We’re still very high angle sunshine.

  21. I am with you 100%.
    I can only go in the water if it is reasonably warm to hot out. Cool weather is great for other activities, but NOT swimming.

    Now watch me get burned.

  22. What I was trying to say was….

    I think that the severe watch was unwarranted for our area.
    Farther South and SW is/was a different story.

    I am ready to declare it a Bust. Wait one last check of radar….
    I still think so, but cautiously eyeing a cluster of convection
    out by Albany. We shall see.

    1. 250 PM – Mesoscale Update:

      Severe Thunderstorm Watch continues for northern CT, RI, and
      much of eastern MA until 8 PM EDT.

      Still seeing some ML CIN across SE CT, RI, and SE MA which has
      limited development thus far and caused earlier New Haven County
      CT storm to weaken as it headed east into a less favorable
      environment. We`re currently watching the activity across PA/NJ
      which in in an area of greater instability and is closer to
      upper trough. This should all rotate toward SNE over next few
      hours. RAP mesoanalysis indicates we will maintain enough
      instability, mid level lapse rates, and 0-6km shear to support a
      continued severe threat, especially from Providence and Plymouth
      to Cape Cod and Islands where we feel the greatest severe threat
      exists thru 6-7 PM. One negative factor has been some mid level
      drying that worked into region behind surface trough which can
      be seen in K-index fields. This may end up limiting activity
      overall or forcing it more over coastal waters so this is
      something we will monitor during next few hours. We may also end
      up needed to trim northern edge of watch (Hartford to northern
      RI into Boston) but will re-assess that in a bit pending radar
      trends.

      Farther north, airmass is more stable which will prevent
      thunderstorm development but could still see a pop-up shower due to
      daytime heating. Otherwise, dense fog near Nantucket may very well
      linger most of the day due to light winds and high moisture.

      Later tonight, upper trough and cold front move offshore,
      bringing in drier air and gradual clearing. Will definitely be
      cooler by daybreak with lows in 50s and lower 60s.

      ……………

      I actually think the watch was fine, seeing as it’s a watch. We’re barely under what we need for something to fire. Until that energy passes by, it can still happen. I agree with trimming the northern edge of the watch though.

      I think NWS performed admirably on this, especially with the uncertainty initiated by the overnight convection.

      1. Yes, I think the watch extended too far North. Perhaps should have been cut off at the Providence to Plymouth line as stated above. Perhaps over to Hartford or a bit South.

        We shall see if anything develops.

        I knew when Boston was on the Northern fringe of the Slight area and then on the watch itself, I KNEW NADA was going to happen in the City.

        I’d be SHOCKED if anything happened in the city.

  23. 88° water temp down here at Lido Beach Sarasota. Air temp 88° air temp dew point 76° I’m loving it. I’m 65 heat doesn’t affect me. I’m fortunate. I know it effects lots of folks on this site. I’m under an umbrella and just finished drinking a liter of water.

    1. I remember back in my private sector days many many occurrences like this that never made the news in the US. Coverage is so different now.

      1. I’m used to hearing about these events from Macs family. From all I have read, this is exceptionally rare. Sure are A lot of rare events lately.

    1. Nice to see you. Either I was too focused on the covid page and missed you (very likely) or you have been away for a bit.

  26. Watch eastern CT, RI, southeastern MA for 2 1/2 to 3 hours for potential shower / t-storm generation. If anything goes, it should exit via Cape Cod & possibly the South Shore by about 9PM or so.

    1. It is truly sad that I had no clue it was pouring outside my window until I looked at the radar

      2. Hilarious!

        That reminds me of the time I was in the house and learned that Amazon had delivered a package when I saw an online photo of it sitting on my porch. What is happening to us?!?!

        2. SClarke. If you read below, You will notice is saw a storm in RI out of my window but not one in my backyard

  30. TK, agree that in the Internet age, with the world at our fingertips and a 24/7 news cycle, we know more about all these weather events around the globe than we used to.

    You know me. I’m not an alarmist. Try to be even-keeled about things. I believe very much in climate change, but don’t think it’s sensible to tie in every natural disaster – from wildfires to flooding – to climate change. For example, we’re probably all going to experience a hike in coffee prices this year. Why? Much colder than normal temperatures throughout Brazil, one of the world biggest coffee producers. It’s been relatively cold in Colombia, too. https://www.reuters.com/business/environment/frosts-reported-brazils-sugarcane-coffee-corn-areas-2021-06-30/ I don’t tie this in to climate change, at least not right away. I just like reporting on unusual weather phenomena around this earth of ours. Hope you and the others don’t mind.

    1. The coffee-growing areas of Brazil get a freeze every few years, similar to the orange-growing areas in Florida. TK and I used to forecast for these areas all the time back in the day.

      What I always find amusing is that there will be a freeze in Brazil for a crop that won’t even be harvested for a few more months, and thus we don’t know the extent of the damage to it, but the coffee shops will all raise their prices next week citing the freeze and resulting shortage as the reason.

      1. Have you looked at the price of lumber recently. We do have a lot of nuts…coffee and otherwise..in this world.

  32. Now I’m seeing lighting out in north and maybe Captain land. This is an awesome light show

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