Thursday Forecast Update

85 Comments

7:33AM

DAY 1-5…
A disturbance will pass just south of New England tonight. Ahead of it will be lots of high cloudiness, during its passage will come a package of rain and embedded thunderstorms for at least part of the region (will have to follow radar later today and tonight to see its exact configuration and area of impact), behind it will be some lingering showers and clouds to start Friday followed by improvement. This improvement will take full hold by later Friday and last through the weekend, which will turn warmer and more humid with time – a classic July feel. If you have any outdoor plans this weekend, you picked a good one. Though an isolated thunderstorm may visit a few areas by late Sunday, the vast majority of if not all of the area will be rain-free from midday Friday right through the weekend. The feel of Summer continues Monday before a cold front moves through with showers and thunderstorms more likely later Monday.
TODAY: Filtered to dimmed sun with lots of high clouds, with sun finally fading away by evening. Highs in the 70s, coolest coast. Wind light NE.
TONIGHT: Cloudy. A period or 2 of rain for many areas along with embedded thunderstorms possible. Some rain may be heavy. Lows in the 60s. Wind light variable.
FRIDAY: Mostly cloudy with lingering showers until mid morning. Breaking clouds late morning. Partly cloudy to mostly sunny afternoon. Highs 75-82. Wind variable becoming W 5-15 MPH.
SATURDAY: Mostly sunny. Lows 58-65. Highs 80-87, few cooler coastal areas.
SUNDAY: Partly cloudy. Isolated thunderstorms possible late. Lows 60-67. Highs 83-90, few cooler coastal areas.
MONDAY: Partly sunny. Chance of afternoon showers and thunderstorms. Lows 63-70. Highs 85-92, cooler South Coast.

DAYS 6-10 (JULY 14-18)…
Trough swings slowly through the Northeast with showers and thunderstorms to start the period and another potential period of unsettled weather from later July 16 to early July 18. Temperatures near to below normal.

DAYS 11-15 (JULY 19-23)…
Trough exits the Northeast, ridge builds into the eastern US by later in the period with the weather trending drier and hotter.

85 thoughts on “Thursday Forecast Update”

  2. Good morning and thank you TK.

    TK, I don’t think I have ever asked you for your thoughts on weather out in the future, but I have good reason now. My son is getting married in an outdoor ceremony
    and reception on 8/15. I am actually not concerned about rain, unless of course it
    was a hurricane, as we have a tent etc. What I am concerned about was your forecast
    to a change to hot around July 21st. IF that were to carry over into August 15th, my
    wife might not make the ceremony.

    We got a preview yesterday. She was deathly sick by the time I got home at 5:30
    and it came on quickly. I spoke to her at 3:30 and she was OK. The humidity/heat
    just got to her and the heat/humidity was going to be short lived so we
    did not install the ACs.

    So, any thought at all that far ahead? You are usually very good at discerning long
    range patterns etc.

    Many thanks

    1. Congratulations on the marriage of your son, OS. Very exciting. I will keep hoping for the weather to work for Mrs. OS. So sorry to hear that she had such a difficult time yesterday. Are the ACs in yet? We ran ours last night for the second (or possibly third) time only this season.

      1. I put one in, but then it started cooling off and she wanted
        the windows open, so I took it out again given it’s only going
        to be in the 70s today.

        Only put them in for heat waves.

        When there is any wind our house cools right off at night.

  3. TK, another question if I May.

    You indicated that there was no convection in the Boston Area due to the front
    moving too quickly. Can you please be more specific on that?

    According to the models there was ample CAPE by 15Z so that would have been in place.
    The Lifted index was fine as well.

    So, if the cape and LI was there and the front was barreling through providing lift,
    what prevented convection?

    1. Was there a CAP and there just wasn’t enough time for the CAP to be broken by
    the time the lift arrived, thus no convection. Then there was just enough time to
    break the Cap to the South and East?
    2. Was it just too warm aloft?
    3. Poor lapse rates? ( I suppose related to #1)
    4. CAPE and LI were NOT as modeled when the lift arrived?
    5. Charlie?

    I am puzzled and would feel MUCH better if you could explain EXACTLY why.
    Please feel free to be as technical as you like.

    Many thanks

    1. I’m going to guess, but look forward to TK’s answer as well ……

      I think #4 for Boston through its immediate SW suburbs points north and west is part of it.

      I think the best instability, combined with the most sunshine, combined with the best moisture and highest dewpoints were in that zone from Providence to Marshfield, points south and east.

      Boston, while hot and humid, was on the northwest most fringe of that zone and it had the earliest frontal passage. Just missed …….

      1. Sort of makes sense. BUT I have to tell you, we had a couple
        of hours of pretty good sunshine prior to that “convective” line coming through. I use the term loosely as there was dying convection to the N &NE here and of course stuff to the S & SW.
        Just connecting the 2 to come up with the “line”. Dew point was
        71 or 72.

        So, I’m just not sure. To me, a CAP would have made more
        sense because I feel the instability was there. BUT there was no discussion of CAP and the HRRR did NOT show any CAP. That is CIN levels were non-existent or very low.

        Convective inhibition (CIN or CINH)[1] is a numerical measure in meteorology that indicates the amount of energy that will prevent an air parcel from rising from the surface to the level of free convection.

        CIN is the amount of energy required to overcome the negatively buoyant energy the environment exerts on an air parcel. In most cases, when CIN exists, it covers a layer from the ground to the level of free convection (LFC). The negatively buoyant energy exerted on an air parcel is a result of the air parcel being cooler (denser) than the air which surrounds it, which causes the air parcel to accelerate downward. The layer of air dominated by CIN is warmer and more stable than the layers above or below it.

        The situation in which convective inhibition is measured is when layers of warmer air are above a particular region of air. The effect of having warm air above a cooler air parcel is to prevent the cooler air parcel from rising into the atmosphere. This creates a stable region of air. Convective inhibition indicates the amount of energy that will be required to force the cooler packet of air to rise. This energy comes from fronts, heating, moistening, or mesoscale convergence boundaries such as outflow and sea breeze boundaries, or orographic lift.

        Typically, an area with a high convection inhibition number is considered stable and has very little likelihood of developing a thunderstorm. Conceptually, it is the opposite of CAPE.

        To me, that is the only thing that makes sense concering yesterday. IF the front were delayed a bit, convection would
        have broken the Cap.

        I am anxiously awaiting TK’s explanation. 😀

        1. It is an interesting situation to try to understand …..

          Thanks for the info on convective inhibition, a term itself I had not heard of before, but certainly the explanation makes sense (after 3 readings 🙂 :). )

          TK chimed in below ……

          1. Yes, he did. I still don’t fully understand. See my further comments. We’re clearly getting there.

            Do you now have a clearer understanding?

            Curious to see if it is just I or not? 😀

  6. Thanks TK.
    Congrats to your son getting married Old Salty.
    Looks like were going to miss out on the severe weather and just get rain here in SNE. Just looking at the SPC outlook a good chunk of eastern PA in the 5% tornado risk for today.

  8. Latest update from SPC keeps severe weather threat to the south and west of SNE including an enhanced risk in eastern PA.
    Marginal risk does include lower Fairfield County in CT. Thankfully that warm front will stay south of SNE reading the discussion from NWS out of Upton, NY there mentioning isolated tornadoes and damaging winds as the main threats with thunderstorms.

  10. OS since I am on my phone I will give you short answers now and we can expand later…

    August pattern is likely to be one of near to above normal temperatures and fairly tropical the majority of the time.

    As for yesterday, the favorable conditions were over forecast by the models and another key was upper level convergence rather than divergence. There was no upper air “evacuation” to keep updrafts going. Notice the lack of sustained blow-off or anvils from the storms that did form?

    1. Many thanks TK.

      Although I appreciate it greatly, not liking August forecast.
      I guess now I just have to HOPE that 8/15 is a respite day in between
      tropical days.

      Re: Yesterday…. Still having trouble understanding. I hear what you are
      saying. Models over-forecasting I get for sure.

      The upper air concepts are somewhat confusing.

      I know when the upper winds are stronger it creates the divergence aloft
      and sort of a “sucking” situation allowing air to rise. When you say convergence aloft, I am having a more difficult time conceptualizing that
      feature.

      Does it mean the winds aloft were too light?
      Not aligned favorably?

      Sorry for acting like Micky the Dunce today, but I really want to understand
      exactly what happened and although I am getting there, still do not have a complete understanding. I mean we were being fed DOOM and GLOOM
      with Flooding etc. Frankly, I was shocked there was no convection here.
      Just really want to understand completely the reasons why.

      Many thanks again.

      1. I hope its ok that I’m participating in this topic and more importantly, that I’m in the ballpark of correctness with what I write ………..

        At the jet stream level, if the winds diverge, then the air is quickly being displaced aloft and has to be replaced with air from below, usually resulting in vigorous lift. Kind of what happens when a vigorous trof and associated surface low pass to our northwest with a bermuda high setup to our southeast. The east side of the trof is directing air from southwest to northeast and the west side of the bermuda high has the air moving west to east or sometimes northwest to southeast and btwn those 2, the air is definitely being evacuated quickly at the jet stream level. It gets replaced from below : tremendous lift.

        But, if the winds converge aloft, then the air is coming together aloft and sinks to the surface. I believe this is what forms arctic high pressures quite often in the winter to our north and northeast.

        2. Tom, are you kidding me!!!! Very much enjoy your contribution.

          Really getting there.

          I found this link:

          http://usatoday30.usatoday.com/weather/wcondiv1.htm

          Reader’s digest version:

          When air aloft, at the jet stream level, slows its forward motion, it piles up. Meteorologists call this convergence. When air aloft suddenly moves away from an area faster than it arrives, they call this divergence.

          So, if I understand this correctly, the Boston area was just not under the proper location of the upper winds, but areas to the South and East were just inside the
          favorable zone.

          Unbelievably fascinating to me.

          OK, I think I finally understand. Cool.

          1. Tom and RD covered it very adequately. 🙂

            I didn’t really interpret the flash flood watch as doom and gloom, but I believe some of the local media did just that…

  11. Thank you, TK.

    Next week looks damp and cool. May be the wettest week around here in a long time.

    Your August forecast of tropical conditions is not what I am hoping for. But, by then September will be around the corner.

      1. TK do you agree that next week is looking wet and cool around here? Was planning on trips to the beach and Cape, but if it’s not going to be good may take a trip somewhere out of dodge where it will be nicer.

        1. Not the entire week. Probably just Tuesday and Wednesday and no all day rain and big time chill.

  12. The daylight hours are getting shorter in August preseason football has started which are two signs to me fall is not that far away. So far this has not been a bad summer in terms of heat and humidty.

    1. Agree, JJ. Even if September turns out warm as TK suggests it might, warm and even hot days in September are not what they are like in June or July. There is more rapid cooling when the sun goes down, even on hot days in early September.

      I have no AC, only fans. Haven’t used them yet. Should have yesterday, but the switch from NStar to Eversource has increased my electrical bill by 35%! While not a lot in the grand scheme of things, I don’t have much money to spare, so every dollar counts. I’ll probably wind up using the fans in August.

  13. Joshua to me when you get to about the 10th of September you don’t have long spells of heat and humidity. That is not to say there won’t be a hot or humid day in there.

  14. The weekly drought monitor was released today. Moderate drought has been completely removed from MA, and much of the central and western part of the state are no longer even “abnormally dry”. This is largely to do with the rain on 7/1 I believe, the past week has been pretty dry for most places, with a few exceptions, especially yesterday, although that wouldn’t show up on this week’s report anyways. The pattern ahead, even with the trough that will develop, doesn’t look particularly wet to me for the next 7-10 days, but there should be enough disturbances to give most places some rain, along with some rain tonight. And that seems to be the way it’s going, we don’t appear to be poised for a long term, region-wide dry spell that could cause drought problems. Fairly dry overall, but not like what we saw in May. We’ll likely see periodic expansions and contractions of that abnormally dry area and maybe some moderate drought if we do get a real dry stretch, but on the whole it doesn’t look too bad to me. Perhaps TK will have other thoughts.

    1. I think it’s the correct assessment. The problem is, it won’t take much to get us right back there…

      1. Thank you WxW and TK. I agree. It stuns me how quickly the rivers react in both directions.

  15. If I may continue our discussion. I went to yesterday’s 500MB vorticity chart
    from 17Z yesterday or 1PM. Just about when we were beginning to see some
    convection.

    http://i.imgur.com/4ZzQlSo.jpg

    You will note on the map in SE map, a distinct shift in winds from WNW to WSW.
    Sort of a trough and Boston Westward per the discussion above on Wrong side of it
    for convection. SE map on correct side for convection. Sorry I am at home now
    and don’t have proper tools to draw a circle but I think you can see.

    TK is that it? thanks

      1. Thank you.
        Thanks to you and this blog I know oh so much more than
        I ever knew before. Lobe it!

        THANK YOU!

  16. Going to be interesting to watch the radar out of eastern PA Baltimore and D.C. areas this afternoon is SPC is thinking a tornado watch will likely be posted for those areas.

  18. TK/OS, on a flight from Jamaica to Philly, landing at 630. What’s it looking like. I saw the NECN futurecast this am and it looked like that was the same time as the biggest chance of storms, etc. Thanks! Wife hates flying and hates any kind of turbulence 🙂

    1. Not TK. 1. Philly NOT In the tornado watch area.
      2. Storms Id say arrive 5:30 to 7Pm. Somewhere in there.

      Hopefully you will be fine

      1. Thanks OS. Hopefully we get in just before them. Scheduled to arrive at 642. Then we have to get out to Boston:)

          1. Nice. Thanks OS. Pilot just said that we should beat it by 40 min. Now we just have to get out of Philly to Boston a little after 8.

  20. North … OS has nicely covered the request. I have nothing to add of any value. 🙂

  21. Not in agreement with CPC’s 8-15 today. Nor was I yesterday. And it’s quite likely I will not be in agreement with it tomorrow either…

  24. On board and going nowhere. Quite intense outside the plane right now. Torrential downpours, strong wind shaking the plane at the gate and lots of lightening aand now it is getting a little light out too(?).

    1. So sorry. Mac and I have been glued to the radar and hoped you might have gotten out ahead.

      1. It is starting to brighten and rain has lightened up. Sttill quite a bit of lightening.

    2. Hopefully it wont be too late into the night when the flight departs.

      But, I’m glad to hear that they are waiting this out.

      1. I was sorry to hear there was a delay but looking at the radar sure agree with you, Tom, that on the ground was a very wise choice.

        1. Indeed. Once we were flying into Miami from Cancu Mexico (may 2005 I believe). As we were approaching the airport I could see the cumulonimbus clouds and was hoping we would land before it hit. Well we landed OK and we taxied towards the gate and came to a grinding halt about 200 feet from the gate as they shut down the entire airport. We sat for 3 hours. The plane was rocked by the wind and I mean rocked. The pilot was awesome and let Mr OS and I into the cockpit and he showed us everything, including a fabulous in cockpit radar display. Brutal echoes. That was an experience.

          SO North, May you depart shortly and have a safe uneventful flight back to Boston.

          1. We are on the way to the runway. Not sure how many ahead of us. Only 40 min once airborne. Hopefully that is soon :). Thanks for the radar info, etc. I appreciate it. Mrs. North hates flying!

            1. Happy to help. Best of Luck. I think you’ll be fine. The worst in now behind you.

              Nice to know some airports take thunderstorms seriously.

          2. Wow OS I know that had to be nerve wracking but what an experience to get into the cockpit.

            2. Was not nerve racking. I was just pissed off about waiting. So I guess that in itself
              is nerve racking. They played a free movie for us, Chronicles of Narnia.

  26. We are finally in Boston. Lots of turbulence. Mrs. North did not like that! On Logan Express and happy to be home safe! Thanks for all the info!

  29. Really pouring in Sudbury now. The doppler radar not working on tv – weatherscan on The Weather Channel – had to turn on computer. Looks like heavy rain over us for awhile yet.

    2. We got hit for sure, it poured for another couple hours after I posted around 2:20am, so I believe your guage.

  31. North, I just read the earlier posts (was half-asleep when I posted around 2 in the morning. I am glad you and your wife are home and safe!

  32. Another beneficial rain. We have had luck on our side in the last 5 weeks when it comes to getting the deficit trimmed for sure!

    New post available. 🙂

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