Thursday August 19 2021 Forecast (7:36AM)

231 Comments

DAYS 1-5 (AUGUST 19-23)

Two systems of tropical origin have some impact on our weather the next 5 days. First, the remains of what was once Tropical Storm Fred pass through our region today from southwest to northeast, in the form of a weak low pressure area, but with plenty of moisture. It will produce a couple rounds of showers, the first being a pretty solid batch of rainfall, steadiest I-90 northward, a little more showery to the south. Keep in mind that the low level wind shear associated with systems like this can sometimes lead to brief, usually weak tornadoes occurring with some of the convective cells. These can lead to locally damaging winds and this is a slight possibility during the morning and midday hours as the first batch of showers comes across the region. Also, some localized flooding may occur with heavier rain in poor drainage areas. The second shower batch will be more in the form of a scattered shower area moving through as the low center gets ready to pull away later on, and this system will have made its exit by tonight. A small area of high pressure sneaks in behind it for Friday, which will likely be a rain-free day with the exception of a possible pop up shower, and it will be warm and quite humid. A back-door cold front will slip down from the northeast this weekend with a bit of a cooling trend and a slight drop in the humidity. Our attention will be on Henri, forecast to be a category 1 hurricane south of New England by later in the weekend. There is still a significant deal of uncertainty with the eventual track of this system and its impact on SNE. My advice is to be prepared for an impact while keeping in mind that we may still be impacted minimally. This is all going to depend on the track and strength details, which will reveal themselves the next couple of days. Subtle details of strength of high pressure ridging to the north of the system and a trough of low pressure approaching from the west will have the final say in this, so for now my forecast will reflect the potential for rainfall from the system later Sunday into Monday, with some wind.

TODAY: Mainly cloudy. Numerous to widespread showers and possible thunderstorms morning-midday southwest to northeast across the region. Scattered showers and thunderstorms west to east again later in the day. Highs 75-82. Dew point upper 60s to middle 70s. Wind S up to 10 MPH. Briefly stronger wind gusts are possible in some showers and storms.

TONIGHT: Mostly cloudy. Slight chance of a passing shower this evening. Patchy fog. Lows 67-74. Dew point upper 60s to lower 70s. Wind SW up to 10 MPH.

FRIDAY: Partly sunny. Isolated showers and thunderstorms possible. Highs 80-87. Dew point upper 60s to lower 70s. Wind W up to 10 MPH.

FRIDAY NIGHT: Variably cloudy. Areas of fog. Lows 65-72. Dew point upper 60s. Wind SW under 10 MPH.

SATURDAY: Partly sunny. Highs 78-85, coolest coast. Dew point upper to middle 60s. Wind SW up to 10 MPH shifting to E during the day.

SATURDAY NIGHT: Variably cloudy. Patchy fog. Lows 62-69. Dew point middle to lower 60s. Wind E under 10 MPH.

SUNDAY: Mostly cloudy. Rain is possible mainly later in the day favoring southern areas. Areas of fog.Highs 72-79. Dew point middle to upper 60s. Wind E to NE 5-15 MPH, may be stronger South Coast region later in the day.

SUNDAY NIGHT: Cloudy with periods of rain and a chance of thunderstorms. Fog likely. Lows 63-70. Dew point middle to upper 60s. Wind E to NE 10-20 MPH and gusty, may be stronger especially in coastal areas.

MONDAY: Mostly cloudy with a chance of rain or showers in the morning. Partly sunny afternoon. Highs 75-82. Dew point upper to middle 60s. Wind variable to W 5-15 MPH.

DAYS 6-10 (AUGUST 24-28)

A trough moving through from the west brings the chance of additional shower and thunderstorm activity August 24 possibly into August 25 before high pressure builds in with dry and seasonably warm weather thereafter.

DAYS 11-15 (AUGUST 29 – SEPTEMBER 2)

High pressure is expected to dominate, with limited rain chances and fairly warm weather.

231 thoughts on “Thursday August 19 2021 Forecast (7:36AM)”

    2. Yeah, I noticed that too last night at 11pm and they (the NHC) just kind of continued it at 5am, I think.

  8. Flash flood warnings currently ongoing for a small area of north-central CT into a small area of Mass, including Springfield.

  10. Thirty years ago today Hurricane Bob arrived to celebrate Mac’s birthday. Now we are looking at Hurricane Henri to join us for our sons wedding day …a good deal of which takes place on a mountain summit. Well, then…….

    1. Hurricane Bob was on my father-in-law’s (80th) birthday as well! We were on the Cape and wound up in a shelter, but first we had trouble getting my mother-in-law off the beach (“I want to feel the wind”) and then we had trouble getting her out of the cottage and into the car (“I’ll just stay here and watch “). She loved weather.

  12. SE sfc winds and some convection around.

    TK discusses nicely above, hopefully no rotating storms next couple of hours.

    1. From NWS at Norton

      .NEAR TERM /THROUGH TONIGHT/…
      635 AM Update:

      Main area of showers with some embedded thunder moving through
      SNE this morning. Severe threat remains low this morning, but
      environment remains somewhat favorable for a shot-lived tornado
      (tropical remnant with plenty of low level shear and low LCLs)
      but lack of surface boundary and deeper instability should
      prevent much from happening. RAP and HRRR indicate most
      favorable areas will be CT into RI and SE MA where better 0-3km
      instability exists but that instability should be outrunning low
      level vorticity which should limit overall threat. Certainly
      need to be concerned about minor urban flooding but activity is
      moving along enough to prevent a greater flood threat.

  13. Just heard that the G-4 aircraft mission to get atmospheric conditions in relation to Henri will have its information it gathered used in tonight’s 00z GFS and HWRF runs. They will also run another mission tomorrow,

  17. I enjoy reading these tweets and posting them to hear different perspectives. One thing everyone seems to agree on Henri stays weak its the eastern solution if Henri is strong the western solution.

  18. Loads of lightening out there. Mostly in NW RI NE Ct and adjacent areas over the border into MA.

    I cannot hear any thunder here at the moment.

      1. Is it severe? Are winds 58 MPH or More? Is there 1 inch hail?
        Is there a tornado?

        I am not saying it’s not severe, but often these warned storms
        are NOT technically severe. I think they are warned because they might possibly become severe. Just my own thoughts.

        What say you?

  22. Severe Thunderstorm Warning
    for Worcester County

    Issued by National Weather Service
    Boston, MA
    10:14 AM EDT Thu, Aug 19, 2021

    The National Weather Service in Boston/Norton has issued a

    * Severe Thunderstorm Warning for… Northeastern Windham County in northern Connecticut… Southeastern Worcester County in central Massachusetts… South central Middlesex County in northeastern Massachusetts… Northwestern Providence County in Rhode Island…

    * Until 1115 AM EDT.

    * At 1014 AM EDT, a severe thunderstorm was located over Webster, or 16 miles south of Worcester, moving northeast at 25 mph.

    HAZARD…60 mph wind gusts and quarter size hail.

    SOURCE…Radar indicated.

    IMPACT…Expect wind damage to trees and power lines. Minor hail damage to vehicles is possible.

    * Locations impacted include… Worcester, Framingham, Marlborough, Shrewsbury, Natick, Milford, Hudson, Westborough, Grafton, Webster, Southbridge, Ashland, Auburn, Burrillville, Northbridge, Hopkinton, Northborough, Oxford, Clinton and Uxbridge.

    PRECAUTIONARY/PREPAREDNESS ACTIONS…

    For your protection move to an interior room on the lowest floor of a building.

    &&

    TORNADO…POSSIBLE; HAIL THREAT…RADAR INDICATED; MAX HAIL SIZE…1.00 IN; WIND THREAT…RADAR INDICATED; MAX WIND GUST…60 MPH

  27. * Tornado Warning for…
    Southeastern Worcester County in central Massachusetts…
    Southwestern Middlesex County in northeastern Massachusetts…

    * Until 1115 AM EDT.

    * At 1021 AM EDT, a severe thunderstorm capable of producing a
    tornado was located over Webster, or 13 miles south of Worcester,
    moving northeast at 25 mph.

    HAZARD…Tornado and quarter size hail.

    SOURCE…Radar indicated rotation.

    IMPACT…Flying debris will be dangerous to those caught without
    shelter. Mobile homes will be damaged or destroyed.
    Damage to roofs, windows, and vehicles will occur. Tree
    damage is likely.

    * This dangerous storm will be near…
    Douglas around 1030 AM EDT.
    Oxford around 1035 AM EDT.
    Auburn and Sutton around 1045 AM EDT.
    Northbridge and Millbury around 1050 AM EDT.
    Worcester and Grafton around 1100 AM EDT.
    Upton around 1105 AM EDT.
    Shrewsbury around 1110 AM EDT.
    Westborough, Hopkinton, Northborough and Boylston around 1115 AM
    EDT.

      1. Thank you all. Tom thanks for the wbz link. And many thanks for prayers, Jean

        We are in whitinsville area on Douglas, northbridge, Uxbridge line. There was something just popping up in this area but most concerned is moving away

  31. Here is a shot of the rotation a bit ago.

    https://ibb.co/bmHw22y

    It appears to be gone or reduced now.

    Btw I have been watching this cell all morning. It has shown signs of rotation for over an hour, but I never thought it was enough to even mention. Even the screenshot I posted still
    does not show a whole lot.

  36. A little more rotation showing in the Northern part of Hopkinton/Southboro area. Hailing in town Hopkinton.

  37. 4+ inches rain and we now have a river pouring through a crack in our foundation which apparently has been patched previously.

      1. Thanks. SIL just came home from work to help. We have filled two huge coolers and many buckets. But all said, it is minor compared to what could have been.

        Thank you ALL for your guidance. Appreciated far more than I can say

  38. Well, that was exciting!

    Good morning, TK!
    Hope you’re safe and there’s no damage in Sutton, Vicki!

    We had heavy rain here and a few rumbles of thunder.

    0.67 of rain. Getting a bit brighter.

    Had a great lunch on Cove Road in the southern end of New Bedford yesterday in the shadow of the hurricane barrier. After lunch, we took a walk up on the CoveWalk on top of the hurricane barrier and had a beautiful view of Clarks Cove.

    SAK…great write-up yesterday. Greatly appreciated your thoughts and research.

    “With the forecast as it is, and knowing how the media can be, we are issuing an Extreme Hype Watch for the region. An Extreme Hype Watch is issued when conditions are favorable for media hype of an event to reach extreme levels within the next 48-72 hours. If conditions warrant, a Hype Advisory or Extreme Hype Warning will be issued as the event draws nearer.”

    This is magnificent!!!!! Well done!!!!

    1. Now it looks like the Holliston rotation has weakened and almost
      disappeared, but pretty intense storm in that area.

  45. Holliston rotation now back, only closer to Sherborn now.

    btw, these cells so much remind me of the Revere tornado set up.
    On that revere cell rotation came and went for 30 miles or more
    as the cell moved NE or ENE from the SW suburbs.

    1. Just looking at a non-dopplar, regular radar, the cell itself has some curves in it, where it looks like there´s warm inflow on the east side and opportunity for rotation. Right by or just northeast of Holliston.

  46. Boston now under a Severe Thunderstorm Warning.

    That cell showing rotation is headed towards my location.
    I am watching it. Seriously rotation looks more than the tornado warned one earlier this morning,. Watching very closely!!!

      1. Rotation seems to be pulsing. It strengthens and then weakens and then strengthens again.

        Most interesting.

      2. They must be hemming and hawing. Should we, shouldn’t we?
        I’ll bet they were reading and saw the rotation weaken.

        We’ll have to see if the rotation ever gets strong enouogh.

  48. I have a dopplar radar open, on the 11:55am scan, would the area of possible rotation be just SSE of Natick ?

    2. Dave? Is in natick. I’m thinking anyone who is a member of whw is watching here now.

      Praying for all to be safe

      1. Yes. Following that idea of the ensembles showing weaker storm, further east, stronger storm, further west.

  50. We are on our sailboat and have just left Edgartown. We are in Vineyard Sound heading to Onset today, Winthrop tomorrow. Edgartown told everyone with a boat on a mooring that they must leave by tomorrow morning. Fingers crossed that Henri is not bad.

  54. Discount 12z UkMet, unless the recon plane, nearly to Henri, reports a pressure of 984 mb in the next hour or so.

    If the plane finds that, then we´ll give more weight to the UkMet.

  56. Alert just came over radio saying tornado warning for Revere and north shore. Anything indicated on radar?

    1. I got one on my phone too, and I’m on the Lexington-Arlington line. What’s up with that? Isn’t the storm moving to the northeast?

      1. The couplet to me looks a couple miles north of Lynn.

        A couplet is two different colors on the radar, indicating wind is headed towards the radar in one color and headed away from the radar on the other color.

  60. We r in car Sutton center heading to millbury. We just got warning on car radio for tstorm and tornado 10 miles from here. Is that wrong ?

  61. The reasoning for the further east track by the NHC is due to how the structure of Henri looks. The LLC is not alligned with the MLC along with northerly shear at those times of NHC issue.

    1. Our house windows fogged up, my glasses really fog up going from the car to outside. Can´t see a damn thing. 🙂 🙂

    1. And now into central Mass with heavy rain.

      The Euro has the upper flow to capture it.

      I´m still concerned.

        1. True and lets hope the Euro has the intensity correct. If it does, we can enjoy a heavy slug of rain and a breeze.

          I think the 500 mb pattern screams intensification of Henri through tremendous outflow potential on Henri´s north and east side during its approach up the coast. That kind of fanning out of cirrus seen on tropical systems a fair distance to the north and east of the center.

  67. And that approach angle is worrisome to me too.

    Talk about bringing east coastal areas into play for storm surge, IF we have a stronger system.

  68. This entity, Henri, also seems tenacious to me, given the intensity of sheer its been under and for probably 36 hrs now.

    Its center is somehow, not completely exposed. It continues to produce convection and its southern semi-circle doesn´t look awful, all shear considered. 🙂

  71. Has anyone hear about a confirmed touch down of tornado in Thompson, CT? My wife saw it on Face Book?

    I cannot confirm.

      1. That’s probably what my wife saw. This says channel 3 which is Hartford. It is not official NWS confirmation.

        I’d like to know if it was one of their experienced Mets. If so, likely true that it was a touch down.

        Many thanks

  74. We all know the NAM sux at tropicals, but what the 18z run does tell me is that the scenario of a loop or a westward followed by reversal eastward movement without a landfall is completely possible. The run itself is likely incorrect. I don’t think this (or the other) models have the correct scenario yet.

    Long way to go though – don’t draw any solid conclusions yet.

    2. We are due for a hit . I’m already thinking I’ll be called in on Sunday so I’m going in Saturday morning so it will be my 7th day which = double time $$$$

      1. Boston may very well have gotten a more “dramatic” event out of today’s activity than they will with Henri.

        1. Even tropical storm or talk of hurricane will probably land is there . When it rains we have leaks everywhere.

  77. Quick peak at 18z GFS you could see the turn back to the west and not good for the Cape and Islands.

  79. Tom it looks similar to the 12z EURO with the left hand turn only difference 18z GFS is stronger.

  80. 12z GFS: rough ocean, not much rain, low to maybe moderate coastal flooding at astronomical high tide, a breeze at the coast and perhaps some tropical storm wind gusts on the outer Cape ??

    18z GFS: moderate coastal flooding, tropical storm wind gusts in a much greater area of SE Mass and further inland perhaps, with a hurricane force gust possible on Cape and Islands ??? and a deluge of rain in east-central Mass.

    Nice to have consistency 72 hrs or so out.

    There goes my patience !

    Eh …. the models will let us know for sure Sunday morning.

  81. So was at work while a possible tornado/microburst came through Clinton about a 1/3rd of a mile from my house. Scoping things out, damage is mostly to trees either uprooted or snapped about 15′ up or so, with a variety of large branches down. Damage is in a straight line about a mile long from end to end, maybe 100 yards wide. Damage is not consistent but spaced out over that path, and matched the area with highest velocities I saw on Radarscope when I got the warning.

    Tornado or not, I couldn’t tell you. If it was, my guess would be a low end EF-0.

    And now on to Henri!

      1. Looks like a couple of houses and cars have trees on them, but haven’t seen any reports of major damage.

  83. Tk,

    It seems as though Henri looks to be a bad nor’easter we see in the winter with hurricane gusts and flooding along the coast. Should we be more concerned?

    1. While it’s too early to determine exactly how strong any wind gusts will be (since we don’t know track of center yet, which will determine alot), I would be prepared for the possibility of wind gusts like we see in our bigger winter storms. The difference though, you have leaved out trees on saturated ground. Those go a lot more easily than leafless trees on frozen winter ground, with regard to just wind.

  84. TJ I was thinking the same thing earlier today that this looks like at the moment a bad Nor’easter we get in the winter.

    2. A reasonable intensity average looks clustered around 35 kts if this played out according to these tracks/intensity.

      Taken literally, perhaps a 65-70 mph tropical storm at south coast and a 40 mph storm (24 hrs) later somewhere in eastern Mass.

      Just my interpretation of the 2 links, not a forecast.

  87. What is not good is your seeing the major of those spaghetti plots showing a landfall. South shore Cape and Islands folks hopefully are starting to prepare.

      1. I mentioned filling gas cans for generators…..ewww that word still gives me chills. Anyway, I digress. The kids asked why since the gas station is right down the street and they’d have a generator. I remember gas pumps being shut down because of no power. Maybe times changed???

        1. I don´t remember gas stations opened via generators when power has gone out recently in Marshfield, anyway.

  88. The real uh-oh on those tracks could be fresh water flooding possibilities.

    I´d think those tracks throw some heavier rains into areas that have seen a ton of water this summer.

  89. Fill up the car is a good idea. Last year before Isiais struck I did that along with pulling in my deck furniture, making sure my battery powered radio was working, cell phone fully charged, and having my flashlights ready.

    1. All good ideas.

      I like no power in summer. Its bright late and bright early.

      Winter´s long in the dark. You´ve been in the dark 2 hrs, it feels like midnight and its 6 or 7pm. 🙂 🙂

  90. With the battery powered radio last summer after Isiais knocked out the power I felt like I was living before tv was invented listening to the Yankees Phillies game on the radio sitting on the deck.

  91. These are wild times as Northeast US meteorologists. Exciting, but draining. We had a few (more) tornadoes down in my neck of the woods last night, along with serious flash flooding. I’m actually on overnights at the moment so that was among the busiest night shifts I’ve worked. Glad everyone is ok up there in SNE after today’s severe weather!

    I can’t add much insight on Henri, other than it looks pretty good to me on satellite this evening. Sheared (the center is near the northern edge of the convective mass), but with really great outflow everywhere except the northern quadrant, where the shear is hitting it. If it maintains this structure, it will be poised to strengthen, possibly quickly, when the shear relaxes by later tomorrow. Still a chance the shear could disrupt it more overnight though. Regardless, worth keeping a (continued) very close eye on.

    https://weather.cod.edu/satrad/?parms=regional-southeast-13-24-0-100-1&checked=map&colorbar=data

    Don’t expect wholesale changes in the 0z guidance, but G-IV data should be in there which past performance has shown can yield at least subtle improvements, on average.

  93. I know its the NAM …. but its a worrisome solution.

    The increased size of the windfield over the ocean btwn hr 00 and hr 60 is easily noticeable. A large, large amount of water would be being pushed north, ready to encounter the south coast, especially near and to the east of the center.

    This run of the NAM is not unreasonable with respect to pressures, but it brings Henri down to around 979 to 980 mb which seems totally plausible to me.

    I´m not focused on the general location of landfall, but just that this would be an impacting scenario should it ever verify. But, in my opinion, there´s nothing on this run that seems very outlandish.

  94. 0z NAM for what it’s worth has a landfall in southeastern CT.
    I am wondering if we will see the hurricane center shift the cone a bit to the west with the 11pm update.

  95. 3km NAM has Katrina, I mean Henri, bottom out at 915 mb.

    Don´t worry, its up to 933 mb when its nearing Long Island.

    No sweat.

    1. Rainfall potential

      https://www.nhc.noaa.gov/storm_graphics/AT08/refresh/AL082021_5day_cone_no_line_and_wind+png/092851_5day_cone_no_line_and_wind.png

      Flood potential

      https://www.nhc.noaa.gov/refresh/graphics_at3+shtml/092851.shtml?ero#contents

      Surge

      https://www.nhc.noaa.gov/refresh/graphics_at3+shtml/092851.shtml?peakSurge#contents

      Wind speed probabilities

      https://www.nhc.noaa.gov/refresh/graphics_at3+shtml/092851.shtml?tswind120#contents

      arrival times

      https://www.nhc.noaa.gov/refresh/graphics_at3+shtml/092851.shtml?mltoa34#contents

      1. Thanks for the info JpDave and the way you present it, so easy to go link by link and find each impact.

    2. I think we´ll need to nowcast, within 3-6 hrs, the intensity.

      We´ll need to see max intensity just past the northern Gulf Stream wall and see forward velocity.

      Outflow looking better and better with time on satellite.

    3. Looks like Cat 1 as it approaches the South Coast. Once it comes on land it will very quickly become a tropical storm and not too much longer after that it will become extra tropical.

      Personally I do not believe that a hurricane watch or warning
      will be issued for inland areas. Tropical Storm watch/warnings, yes.

      The South coast and Islands will take the brunt of this, imho. Could be quite severe down there.

      Flooding and some wind damage for much of SNE.

      Given all of that, I am wondering if Henri is ultimately destined to go even farther West???????

  102. No doubt that Hurricane watch will be expanded northward into Boston and the North Shore. Maybe NH Seacoast as well?

  106. Thank you for all the great analysis.

    It looks like to me on satellite this is poised to strengthen quite a bit. Models usually have difficulty with intensity. Let’s pray it’s not that bad.

    1. From NHC

      The strong shear affecting Henri is forecast to begin weakening
      later today, and SHIPS diagnostics indicate that it could drop to
      less than 10 kt in about 36 hours. In addition, Henri will be
      traversing very warm waters for the next 48 hours before it crosses
      the north wall of the Gulf Stream. Therefore, strengthening is
      anticipated for the next 2 days, with Henri likely to become a
      hurricane by Saturday. After 48 hours, Henri’s expected slower
      motion over the colder water south of New England should induce
      quick weakening, but it may not be quick enough to keep Henri from
      reaching the coast as a hurricane. Faster weakening is anticipated
      after Henri’s center moves over land, and simulated satellite
      imagery from the GFS and ECMWF models suggest that deep convection
      could dissipate by day 4, making Henri a post-tropical low at that
      time. Global models suggest that Henri may dissipate by day 5, but
      for the time being a day 5 point is being kept for continuity.

  107. I’m going to start preparing in pembroke as we have had sone major issues just with tropical storms . Although I don’t know when I’ll be home I’m working all weekend

    1. Henri : 45-60 knots SE side after all that shear. 35-40 knots northwest side. What will they encounter in the northeast quadrant ?? (Flight level winds)

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