Tuesday Forecast

75 Comments

7:08AM

DAYS 1-5 (AUGUST 20-24)
A bubble of high pressure will eliminate the thunderstorm risk today, so a very nice day, but a warm front will cross the region Wednesday, causing a spike in humidity and destabilizing the atmosphere significantly. We’ll have to watch for a few storms in the morning and another round or 2 in the afternoon / evening with some potential for severe weather as well. A cold front will cross the region Thursday, and while it doesn’t look like a widespread storm day, we will still run the risk of some activity especially in eastern and southern areas. High pressure from Canada builds in with a dry and refreshing airmass for the end of the week.
Forecast details…
TODAY: Mostly sunny. Moderately humid. Highs 80-85 coast, 85-90 interior. Wind light variable with coastal sea breezes.
TONIGHT: Partly cloudy. Moderately humid. Lows 66-73. Wind light S.
WEDNESDAY: Variably cloudy. Isolated to scattered showers/thunderstorms, favoring early to mid morning and again later in the afternoon. Humid. Highs 81-88. Wind S 5-15 MPH.
WEDNESDAY NIGHT: Mostly cloudy. Showers and thunderstorms likely. Patchy fog. Humid. Lows 62-69. Wind SW 5-15 MPH.
THURSDAY: Variably cloudy. Isolated to scattered showers and thunderstorms, favoring southeastern NH, eastern MA, and RI. Humid. Highs 80-87. Wind SW 5-15 MPH.
THURSDAY NIGHT: Clearing. Less humid. Patchy fog evening favoring interior lower elevations. Lows 60-67. Wind NW up to 10 MPH.
FRIDAY: Mostly sunny. Highs 76-83. Wind NW 5-15 MPH.
FRIDAY NIGHT: Mostly clear. Lows 55-62. Wind light N.
SATURDAY: Mostly sunny. Highs 75-82. Wind N 5-15 MPH.

DAYS 6-10 (AUGUST 25-29)
High pressure will dominate but will likely be centered northeast of the region, which means onshore flow and coolest weather coastal areas while inland locations are warmer August 25-26. High pressure sinks southward with an increase in warmth and humidity and eventually an increasing risk of showers/thunderstorms August 27-29.

DAYS 11-15 (AUGUST 30-SEPTEMBER 3)
A boundary between offshore high pressure and Canadian high pressure will bring a shower and thunderstorm risk the last couple days of August before high pressure from Canada temporarily wins the battle to bring drier air in to start September. Temperatures will likely run above normal through this period.

75 thoughts on “Tuesday Forecast”

  5. Good morning and thank you TK.

    The hang back echoes provided a few more drops of rain that finally
    tripped my rain gauge.

    We received a whopping 0.01 inch of rain yesterday. Big deal.

    1. I was out and about in the `rain’ yesterday. Stopped at CVS in Copley Square on my way home. Several people (probably tourists) came in to the store and asked for umbrellas. As you know, CVS sells way over-priced cheaply made umbrellas for $12. These are the same umbrellas you can buy in Chinatown for $3. By the time the people had purchased their umbrellas and made their way out the store the rain had basically stopped. I guess if they’re still in the Boston area tomorrow they can use their umbrellas. But, any major wind gust tomorrow will break these pieces of junk.

      1. funny story. I know that CVS. 😀
        do you live near there?

        We shall see what tomorrow brings.
        IF not enough rain, I may have to water for the 1st time
        this season.

  10. 12Z NAM has a VERY strong tornado threat for SNE tomorrow.
    12Z 4KM NAM has tornado threat as well, but not nearly as strong as the 12ZNAM.
    Both of the above from the College of DuPage Soundings.

    https://imgur.com/a/aIU5GTq

    FWIW, the SREF has virtually no tornado threat at all.

    2. 12Z GFS, NOT so much
      Marginal severe to weak tornado across the area and again this is from
      the COD site.

  11. 61 dp at Logan with sea breeze and 55 dp at Norwood with land breeze.
    Can’t get away from that facata humidity()@!&#*()!@&#*!&(*@#&!*&#@*(

    1. Be grateful that it’s not 70+ like yesterday. Too bad we’re going to have to endure the next two days of that yuck. Look forward to the weekend.

  12. Philip, you’re right about needing an umbrella tomorrow and possibly Thursday.

    Jp Dave, yes I live about a half-mile from Copley Square. I consider myself blessed, because I think Copley Square is one of the nicest `real’ city squares (not the `wedding cake’ ones that feel too clean and fake) in the world. The variety of 19th century architecture is astounding: Old South church, Trinity, the Copley hotel (now Fairmount, I believe), Boston Public Library. Couple that with the world’s largest mirror – the John Hancock building – and you have yourself a gem. To me, the drug addicts, homeless people, skateboarders, thousands of commuters, and even some of the odd buildings on Boylston Street etc … make this a real, living square.

  13. I’m not a TV watcher, so I have basic cable, which is quite basic. But now and then I discover something new, like channel 98 (Comcast), Portuguese TV from the Azores. My understanding of Portuguese is limited. I understand about 20% of spoken Brazilian Portuguese, and maybe 10% of spoken Portuguese from Portugal. But, I was fascinated by the news (Noticias do Atlantico – News from the Atlantic) and especially the local news items. After an hour of watching I began to pick up a few things. My knowledge of Latin and Spanish helps. Gosh, that place – well, archipelago – is remote. It’s `out there,’ as in far from anything. Yet, it’s distinctly European and Portuguese. The weather looks idyllic. Constant seabreeze. Never really hot. Also never cold, unless one is in the mountains. For some reason, hurricanes don’t hit often. TK can maybe explain that. One part of the archipelago is technically on the North American side geologically, while the other is on the Eurasian side.

    1. My family on my mom’s mother’s side came here from the Azores. No idea why they would ever want to leave that place. Its beautiful.

  15. I am not surprised to see the upgrade to a slight risk as the SPC yesterday in their discussions that parts of the marginal risk might need to be upgraded. In their discussion it mentions Hudson River Valley of NY western New England and Champaign Valley as areas where a tornado is possible.

  16. Add the 12Z HREF as touting Severe weather for tomorrow, including a threat
    of tornadoes, even to Boston. We shall see.
    At the very least, tomorrow is a day that needs to be monitored carefully.

    Even the 12Z HRRR (waiting on 18Z) had tornado as a risk in the soundings.

    Every model I have looked at, except the Euro has tornado as a threat tomorrow.
    Even the Euro has a very slight threat, a non-zero chance anyway.

    1. Thanks for posting that info JpDave on what the other models say. Will see what future model runs say but right now I would expect a 2% tornado chance covering parts of SNE tomorrow.

      1. Agree with the general 2%, but it would not surprise
        me to have parts of the area in a 5%. Will be MOST interesting
        to see what they say tomorrow AM.

  19. I will be interested if the latest SREF which should start to roll out soon highlights an area in New England in that low tornado risk. Yesterday there was a run that showed a low tornado risk for parts of Vermont

    1. As of this morning, only a 5% area in far NNE.

      SREF is a different animal than the others. I’ll bet it does NOT show it.

      We shall see.

  20. Just read the Albany discussion. There are some factors that could limit/eliminate
    severe threat.

    There is still uncertainty tied to the progression of midlevel
    impulses. A well timed wave tracking through in the morning
    could short-circuit the development of instability via numerous
    morning showers and thunderstorms, and could also modulate the
    midlevel wind field. A good surface triggering mechanism is also
    absent as the cold front will be well to the west, although we
    often see prefrontal troughs developing.

  21. I have a feeling that cloud cover will limit the potential tommorow. the morning activity will give us a lot of cloud debris. I hope i am wrong

    1. You could easily be correct. And also, the worst of the weather could
      actually end up being morning convection, leaving little or nothing for the PM.

      Still, should be an interesting day,

  23. From NWS Boston. I thought the EURO is conservative when it comes to severe parameters.
    Rel Humidity fields also show lots of moisture and suggest cloudy skies. But cross sections show many breaks…enough to suggest temps warming into the 80s again Wednesday. Stability parameters are impressive with SBCAPE 1500-2500 J/Kg, LI of -5 to -8, totals around 50. Winds at 850 mb are forecast at 25-30 kt while 500 mb winds are forecast around 35 kt. The 0-3Km Helicity is forecast at 150 on the ECMWF and 220 on the GFS.

  25. Question… say that we do manage to get to like 83 or 85 degrees. but its cloudy. can storms still fire even thought its cloudy? I mean as long as we warm up to the 80’s doesnt matter if its cloud right?

      2. The last couple of times TK and others have said the storm type was not the kind that needed sun. I cannot recall whether there was an explanation but if so I apologize for forgetting what it is.

        I’d love to know the reason

  26. I want to say if a warm front is in the area that might be able to overcome the cloudy skies. I don’t know for sure.

    1. Warmth, humidity, warm front and cold front is a recipe for severe weather
      around these parts. Does it mean it will happen? Nope.
      Could it? Yup.
      We’ll have to wait and see.

  27. Ace, interesting to hear about your Portuguese (Azores) heritage. I’m usually not impulsive, but I’ve decided to visit the Azores next June. I’ll see Ponta Delgada and Angra do Heroismo (a 6 hour ferry ride from the island where Ponta Delgada is situated). Talk about the crossroads of history and geography. Only 2000 miles due southeast of Nantucket.

  28. This event is still like 24 hours out, but the more I look at all of the maps, the more
    I think that the main threat will be the lower Hudson River Valley and the Connecticut
    River Valley and areas in between. Would not surprise me if SPC paints that area
    in 5% chance of tornado, while most of the rest of SNE will be in a 2% area.
    In fact, it would not surprise me if the aforementioned area has a tornado watch
    posted.

    Once again like a broken record, we shall see.

  30. JpDave Meteorologist John Homenuk mentioned those areas you mentioned as areas where a possible tornado threat could happen.

    1. You can’t focus on specific amounts with convection. It’s going to put whatever it calculates based on where it “guesses” cells are. You know that one area could get 2+ inches and 1 mile away doesn’t get a drop. Totally different animal from stratiform precipitation.

      I have noticed a lot of the TV forecasters lately have been relying TOO MUCH on “futurecast” for cell positions over 24 hours in advance! You can’t even do that with HRRR, which has done some fabulous forecasting. They have to scale back trying to specify where cells are going to be.

  32. I am NOT as impressed with the 18Z NAMs severe parameters for tomorrow.
    CAPE seems to be down quite a bit, presumably due to excessive cloudiness???

  35. So as of late afternoon Tuesday I feel like this is how it may unfold…

    Round 1: Warm front t-storms from SW to NE, favoring CT, western and central to northeastern MA and southern NH. These storms have the greatest potential for rotation and therefore the greatest potential for any tornadic activity, should it get to that point.

    Round 2: Post warm frontal trough broken to solid line(s) / clusters of thunderstorms from west to east mid to late afternoon Wednesday, which carry high lightning potential and the possibility of straight-line wind damage, as well as the usual downpours. This round may fail to fully materialize. Greatest potential northwest of a Boston-Providence line, but especially northwest of I-95.

    Round 3: Warm sector trough broken line or clusters of thunderstorms Wednesday late evening to overnight, which may be stronger especially if Round 2 does not materialize fully. This would be your nocturnal lightning show. Again greatest potential would be northwest of a Boston-Providence line, but could penetrate further southeast with enough momentum.

    Round 4: Pre cold frontal trough thunderstorm threat Thursday late morning to early afternoon, may not fully develop due to lack of sufficient heating, but still have to watch for this which could produce hail and gusty winds if any cells are strong enough. Threat zone for this is anywhere in the region as the trough swings through.

    Round 5: Cold front thunderstorm risk later in the day Thursday, which to me looks like the least amount of coverage but possibly some strong isolated cells, hail & wind being threats and possible anywhere in the region, just limited coverage.

    Round 6: Post cold frontal wave of low pressure which may bring a quick round of shower and embedded storms to the South Coast and parts of southeastern MA Friday morning between pre-dawn and mid morning, depending on timing. This wave may fail to really get going and stay to the south.

      1. I am leaning chasing as an option beginning at 2:30PM Wednesday. The only times I can’t do it are before 2:30PM Wednesday and for about 6 1/2 hours from Thursday morning to early afternoon. We’ll see how it all breaks down.

        1. Well, for 2 or 3 days anyway. 😛

          We don’t usually get long pushes of air like that until after the equinox.

    1. It would really only have an impact on Round 2, and Round 2 could impact Round 3. But everything else is kind of independent I believe.

      1. My last Dana meeting is tomorrow night. I’m hoping the front end is loaded and not as much back end

  38. The #1 thing on my bucket list is to go on one of those chasing excursions set up by one of those professional outfits that does one week chases in the spring. Has anyone here ever taken part in one of those excursions, and if so was it worth it?

  40. 4 alarms. Hopefully not toxic if plastics, etc. involved. We are in North Attleboro. Think this is NNW of Boston.

    1. Forget the NAM until further notice. Multiple crap runs in a row. It doesn’t mean MA will get hammered, but the NAM is not performing.

  42. New post!

    I’ll try to give quick updates on my thoughts in comments as the day goes on. I will be limited on my access here until after 2PM, and I am probably heading for southern NH later this afternoon.

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