Thursday August 17 2023 Forecast (7:38AM)

95 Comments

DAYS 1-5 (AUGUST 17-21)

A frontal boundary continues to hang just to our south, with our region on the cool side. But being on the cool side of this boundary also comes with relatively high humidity, not dry air, so clouds are quite dominant and will continue to be today, but with a lack of any rain / drizzle chances, so just dry weather, mild, humid, but not that much sun. That’s the Thursday story. Low pressure passing to our northwest and north tonight into Friday will finally drag the frontal boundary north as a warm front with an increased chance of showers tonight into Friday before a cold front sweeps eastward across the region. When this happens, add the chance of thunderstorms too. Some downpours are likely, but I’m not expecting widespread heavy rain coverage, and where it does occur it will tend to be brief, limiting flooding. The cold front sweeps offshore by late Friday as we see the shower/storm threat drop off and end from west to east during Friday afternoon to early evening. Behind this front comes a refreshing dry air mass from Canada. Saturday’s weather will feature low humidity, a gusty breeze, and a sun/cloud mix, with dry weather as any showers triggered by cool air aloft will occur in the mountains to our north. A more gentle westerly breeze is expected Sunday with less diurnal clouds, more sun, slightly warmer air, and a small and slow up-tick in humidity levels, but still fairly comfortable. Monday, a cold front is expected to drop southeastward out of Canada in response to a trough in eastern Canada, introducing a new Canadian air mass at some point during the day. This is part of a larger scale pattern that will be keeping a hot ridge of high pressure to our west, preventing heat here.

TODAY: Lots of clouds / limited sun. Highs 73-80. Dew point 60s. Wind E-SE up to 10 MPH, shifting to S 5-15 MPH in southern areas by later in the day.

TONIGHT: Mostly cloudy. Isolated showers evening. Scattered showers overnight, a few possibly heavy with a slight chance of thunderstorms. Areas of fog. Lows 65-72. Dew point 60s. Wind S 5-15 MPH.

FRIDAY: Variably cloudy. Scattered to numerous showers and thunderstorms , diminishing from west to east during the afternoon hours. Highs 76-83. Dew point 60s. Wind S 5-15 MPH shifting to W from west to east.

FRIDAY NIGHT: Partly cloudy. Lows 60-67. Dew point falling below 60. Wind W 5-15 MPH.

SATURDAY: Sun/cloud mix. Highs 78-85. Dew point falling below 50. Wind W 5-15 MPH.

SATURDAY NIGHT: Clearing. Lows 55-62. Dew point 40s. Wind W 5-15 MPH, diminishing.

SUNDAY: Mostly sunny. Highs 78-85. Dew point near 50. Wind W up to 10 MPH.

SUNDAY NIGHT: Clear. Patchy ground fog. Lows 57-64. Dew point rising through 50s. Wind WSW up to 10 MPH.

MONDAY: Partly cloudy. Highs 77-84. Dew point briefly 60+ then dropping into 50s. Wind WSW 5-15 MPH shifting to NW.

DAYS 6-10 (AUGUST 22-26)

General pattern should feature a northwesterly upper level air flow with a ridge of high pressure in the central US and a trough of low pressure from eastern Canada to northern New England. This pattern keeps major heat out, with near to below normal temperatures, but leaves the door open for passing disturbances and fronts with shower and thunderstorm chances a couple times.

DAYS 11-15 (AUGUST 27-31)

The final days of August look like they’ll feature a similar pattern with temperatures near to below normal as cool air is reinforced behind brief shower chances.

95 thoughts on “Thursday August 17 2023 Forecast (7:38AM)”

  4. TK, that pattern you are describing that will keep us near to below average in temperature, will it not also protect us from
    any possible tropical activity? Thanks

    1. For the most part, but I don’t expect much, despite what you may hear elsewhere.

      A bit more than recently, but not wild.

  5. Not for nothing, but it has been SUNNY here since sun rise. 🙂
    Hope it stays that way, but I am prepared for clouds. 🙂

  7. https://www.star.nesdis.noaa.gov/GOES/sector_band.php?sat=G18&sector=wus&band=09&length=24

    https://www.pivotalweather.com/model.php?m=ecmwf_full&p=500wh&rh=2023081700&fh=12&r=conus&dpdt=&mc=

    So, the upper level low that will be one factor in Hilary’s track is already present, both on the water vapor and where the euro expects it to be at 12z

    https://www.pivotalweather.com/model.php?m=ecmwf_full&p=500wh&rh=2023081700&fh=90&r=conus&dpdt=&mc=

    A little more than 72 hrs later, the upper low is simulated to be just off the California coast. The 2nd big player is the strength and location of the central US ridge. The strong south flow aloft between the 2 is what will direct Hilary and more importantly, its moisture.

    The upper low is already there. I don’t think the question is, how far will Hilary go offshore ?

    I think the question is, because the 500 mb ridge hasn’t really formed yet, how far east will Hilary track. If the ridge isn’t as strong or ends up slightly further east, then Hilary’s moisture might head more for Arizona/western New Mexico than California.

    1. Nice Tom,

      Euro and GFS are fairly similar, but the GFS appears
      more juiced than the Euro. If the GFS verifies, there
      are going to be some problems. The rain will fall in areas that simply do NOT get much rainfall all year. In one day more than a year’s rain could occur. Think about that?

      The desert will be blooming!

      1. Agreed. 4” on that ground out there, I can’t imagine what equivalent amt that would be out here given our vastly different ground.

        1. In terms of behavior for runoff.

          I do know 4” of rain in any location is the same amt of rain 🙂 🙂 🙂

    1. It’s in reverse 🙂

      I saw their latest track which then sent me trying to understand why their track shifted eastward.

  12. Cold front/possible small triple point low passing through middle of the afternoon tomorrow in eastern New England.

    I sure hope we don’t get more of the sun’s energy than expected.

    1. NWS discussion

      As mentioned above, fall-like jet dynamics with very fast flow
      aloft, 50-60 kt at 500 mb and 90-100 kt at 250 mb is very anomalous
      for mid August. Friday will be a very warm and humid day, with dew
      pts surging to 70-75 and temps of 80-85, supporting ML capes of 750-
      1500 j/kg. This combined with anomalous wind fields aloft will
      result in the risk for a few strong to severe storms Friday morning
      and afternoon. The instability combined with high PWAT airmass will
      also yield a low risk for flash flooding. WPC continues with a
      marginal risk of flash flooding for all of SNE Friday. In addition,
      the strong jet dynamics may induce a triple point low on the frontal
      boundary, increasing low level helocity and as a result, a low risk
      for an isolated tornado. SPC has included a 2% chance of tornadoes
      across eastern MA and RI. HREF supports this with numerous swaths of
      updraft helocity Fri morning and afternoon from eastern CT into RI
      and eastern MA. As for timing, given dry slot and FROPA may advect
      into western MA/CT by 18z per some model guidance, greatest risk for
      strong to severe storms will be farther east across RI, eastern CT
      and eastern MA.

  14. re; Hilary
    I have never been to California, But I have been to Las Vegas more times than I care to report here.
    Las Vegas Floods very easily when there is copious rainfall.
    Hilary “could” present some serious problems for that city.

    1. Excellent. Thank you, JimmyJames, for your day in history posts. The 50s sure were an active hurricane period for the NE

  20. Thanks TK.

    This morning earlier I saw the most sunshine in the past two days. I was out all day running errands between Boston and Brookline and saw nothing but dark clouds, not even any brief brightening. There was even a bit of drizzle as I noticed it on the bus driver’s windshield. Only today’s brief early sun prevents a trifecta.

  21. Interesting series on Netflix

    PAINKILLER

    Starring Matthew Broderick who turned in a Stellar performance to say the least.

    It is the story of the Sackler family, Purdue Pharma and how
    they developed and distributed Oxycontin.

    It was very well done and really documents the problems with the drug and the methods used by Perdue Pharma to distribute it.

    I highly recommend it.

    2. I worked at Tufts University during the peak of sales of Oxycontin and other prescription opioids. I personally knew several of the folks who either worked at Purdue at the time or were pain specialists at the medical school.

      The story is quite complex. Initially, in the late 90s, there was an acute need for more pain medications. Chronic pain was largely ignored for a fairly long period of time. Purdue thought it had the answer to the problem in Oxycontin. It turned out it did not. Within a few years of marketing the product it became clear that misuse, abuse, overuse, and diversion were major problems. What Purdue and others perhaps didn’t know during the first few years of selling their products, they definitely knew by, say, 2000 or 2001. It is at that point that Purdue and others should have halted marketing and cooperated with the federal government in studying misuse, abuse, overuse, and diversion. Instead, Purdue decided to minimize the problem. Worse, it decided to expand sales opportunities by telling doctors to prescribe the product off-label, meaning for conditions not approved by the FDA.

      Sadly, this is what sparked our opioid crisis today. It’s not that prescription opioids don’t have any place in medicine. They certainly do. Even Oxycontin. But, it should be limited, monitored and not promoted to doctors and patients as if there isn’t a real risk of addiction (however low that risk may be).

      Eventually more powerful illicit forms of opioids (non-prescription) like fentanyl hit the illegal markets. Getting hooked onto one form of opioid – a legal prescription – can in some instances lead to the use of worse and more potent forms, such as heroin and fentanyl. Moreover, prescription opioids themselves, if abused and used in conjunction with other drugs or alcohol can lead to fatalities. The sad sagas of Tom Petty, Prince, Seymour Hoffman, and many others, point to this.

      Excessive greed and the pursuit of profits at the expense of people are bad, in my view. There is nothing wrong with making profits per se, but it should never been done when it causes massive harms to people.

      1. Excellent comments. Thank you.
        If you have not viewed the series, then it looks like it may interest you.

      2. Thank you for this. I see red when I think about exactly how these companies have knowingly destroyed so many lives ans created more pain with the claim that they are easing pain

        Mac and we had a horrific time getting doctors to not force the Oxys and the morphine, etc. Same for hospice. Not only was mac nervous about their addictive danger but they messed up his system to the point he needed multiple other medications to counter what they did. (As an aside….doesn’t that work well for the pharmaceutical business )

        We finally were able to get MM edibles ….it was just barely legal here at that point. The forms the doctors had to complete to prescribe were pages and pages long so not many were certified. We had an amazing doctor at Brigham who understood the benefits ans strongly advised us to get MM. Mac’s life changed at that point. Not only did the edibles control pain and the cough no med to date had touched but it increased a formerly nonexistent appetite.

        I did add this movie to my list. But not sure what it will do to my BP so will have to think on it

            1. Thank you. I’ll watch. I’ll just wait for Mac’s birthday weekend to pass. As of now my BP is elevated over who the inept coach starts Saturday night. So you see….it doesn’t take a lot 😉

    1. Will this be Connecticut’s Norwood Airport?
      Or Beverly? Or Marshfield? Or Hanscom Field? 🙂

      Would be nice to have another reporting station. 🙂

  24. Thanks TK.

    Hilary looks now like it is going to reach Cat 4 strength (140 mph winds) at its closest pass to Cabo San Lucas Saturday when we are scheduled to arrive. Perhaps a stronger offshore storm would be a better scenario? The stronger the storm, the tighter the circulation, and the strongest winds dont fan out as far from the center? I do see that the NHC now has a tropical storm warning up for the southern Baja California peninsula but the tropical storm wind probabilities there are only 10% per their map and hurricane wind probabilities are zero.

    https://www.nhc.noaa.gov/refresh/graphics_ep4+shtml/174208.shtml?tswind120#contents

  25. TWC forecast for Cabo Saturday:

    Watching the tropics. Windy with showers and thunderstorms likely. High 84F. Winds SE at 25 to 40 mph. Chance of rain 100%. Rainfall may reach one inch.

    I checked out the Cabo airport on an aerial map and looks like the runway is aligned north/south so the plane at least would not be landing in crosswinds.

    1. actually it is aligned more ESE to WNW. A more easterly component to the winds would be helpful. Oh well, guess we are going to have to wait and see what happens…

    2. It’s the Carnival Panorama, and it’s scheduled to leave port at 2:30pm local, en route to it’s final destination, Los Angeles, scheduled to arrive at 9am Saturday.

      1. Yikes. They should stay ahead of the storm in good weather but that could be a rough day at sea tomorrow for those people.

  27. I can’t even imagine what a place like Death Valley is going to look like if those 2-4″ rain prognostications verify. If I recall, there was flash flooding in Death Valley last year after only a half inch fell. Ground is bone dry….it just all runs off.

  30. 15Z SREF Craven Brooks Severe Parameter for tomorrow:

    https://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_CB_MEDIAN_MXMN__f027.gif

    Meaning…

    Craven SigSvr Parameter

    The simple product of 100mb MLCAPE and 0-6km magnitude of the vector difference (m/s; often referred to as “deep layer shear”) accounts for the compensation between instability and shear magnitude. Using a database of about 60,000 soundings, the majority of significant severe events (2+ inch hail, 65+ knot winds, F2+ tornadoes) occur when the product exceeds 20,000 m3/s3.

    The index is formulated as follows:

    C = (MLCAPE J kg-1) * (SHR6 m s-1)

    For example, a 0-6-km shear of 20 m s-1 (40 knots) and CAPE of 3000 J kg-1 results in a Craven SigSvr index of 60,000. Units are scaled to the nearest 1000 on the web plot.

    Reference:
    Craven, J. P., and H. E. Brooks, 2004: Baseline climatology of sounding derived parameters associated with deeep moist convection. Natl. Wea. Digest, 28, 13-24.

    1. the 20,000 in our area is significant. We shall see what actually happens. Hopefully nothing but some down pours.

      I am most interested in seeing future runs of all of these severe parameters.

  32. The ECMWF forecast for Hilary is interesting. I’m not talking about the track or the amount of rain. I’m talking about the fact that is has a few inches of SNOW across the higher terrain of the Central and Southern Sierra Nevada.

  33. Not overly excited about Friday’s severe weather potential. Yes, it’s there, but we’re looking at a very modest opportunity for a couple rotating storms in the morning-midday round, with otherwise isolated damaging wind gusts the main threat. Flooding not a big issue with quick-movers.

    The frontal round will be shorter lived and greatest threat is hail and straight line wind gusts, but even more isolated. Also that has a very short window to occur in.

    By evening, almost a hint of the early days of autumn with how dry it will become along with a breeze.

    Saturday will whisper “September isn’t that far away” in its breeze. 🙂

    1. I’ve been waiting all day for this as I got a sense of how you felt reading your discussion. 🙂

      1. Even so, one of these days where the SPC has 2% tornado and the SREF has their 5% we’re going to get one. Tomorrow may not be the day, but we can’t duck these forever.

  35. I’m going to make it official:

    3 dark days in a row!
    (Not including 2-3 hours of sunshine following sunrise)

    The month of August is giving November a run for its money for sure. 🙁

  36. At least no 90 degree heat this August so far. One of our meteorologists here in CT thinks we could get through the rest of August with no 90 degree heat.

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