Wednesday September 6 2023 Forecast (7:07AM)

96 Comments

DAYS 1-5 (SEPTEMBER 6-10)

A September hot spell lasts a few more days before it eases up on us. We haven’t had much in the way of heat to deal with all summer so getting a spike if it now will make those not used to it feel it that much more. The good news about getting hotter weather at this time of year, if you don’t care for it, is that with shorter daylight and lower sun angle it takes away from some of the intensity, especially since there is going to be fairly high humidity to go along with that heat. Its origin is that long-standing hot spell in the middle of the country as an adjustment in the pattern allows the ridge to slide eastward across our region over the next few days. Once the ridge axis gets offshore late in the week, we’ll watch for the approach of a trough from the west and an increase in shower and thunderstorm chances, but this may be quite slow to occur, keeping our weather mainly rain-free into the weekend. We’ll have to watch for remnant showers and storms approaching the WHW forecast area from the west Thursday evening and again some favoring the western portion of the area Friday and Saturday, with Sunday seeing an increase in chance and coverage.

TODAY: Mostly sunny to partly cloudy. Highs 84-91. Dew point 60s. Wind SW 5-15 MPH.

TONIGHT: Partly cloudy. Patchy fog in lower elevations. Lows 63-70. Dew point 60s. Wind SW up to 10 MPH.

THURSDAY: Partly sunny. Highs 86-93. Dew point 60s. Wind SW 5-15 MPH.

THURSDAY NIGHT: Variably cloudy. Chance of a shower or thunderstorm. Areas of fog. Lows 63-70. Dew point 60s. Wind SW up to 10 MPH.

FRIDAY: Partly sunny. Chance of a late-day shower and thunderstorm favoring western areas. Highs 84-91. Dew point 60s. Wind SW 5-15 MPH.

FRIDAY NIGHT: Variably cloudy. Chance of a shower or thunderstorm. Areas of fog. Lows 64-71. Dew point 60s. Wind SW up to 10 MPH.

SATURDAY: Partly sunny. A few showers/thunderstorms possible mainly in the afternoon and mainly in western portions of the region. Highs 82-89. Dew point 60s. Wind SW 5-15 MPH.

SATURDAY NIGHT: Partly cloudy. Patchy fog. Lows 63-70. Dew point 60s. Wind SW-S up to 10 MPH.

SUNDAY: Variably cloudy. Chance of showers and thunderstorms. Highs 78-85. Dew point 60s. Wind S 5-15 MPH.

DAYS 6-10 (SEPTEMBER 11-15)

Frontal boundary still in the vicinity with high humidity and wet weather chances to start the period, and another mid period frontal boundary may bring a shower or thunderstorm chance. Not as warm as previously, but temperatures still somewhat above normal into mid month. By late period we may be seeing a strong tropical system (Hurricane Lee) somewhere off the US East Coast. While it being far too soon to know the specific track, the early indications from the most reliable guidance indicate a track far enough offshore to spare the East Coast (and our region) any direct impact. Obviously, it’s in need of watching as time goes on.

DAYS 11-15 (SEPTEMBER 16-20)

Any offshore tropical system exits the vicinity (if it’s in the vicinity) early in the period, and the general pattern switches up to allow a shot or 2 of cooler/drier air from Canada, with the potential for showers during air mass changes. More details to come.

96 thoughts on “Wednesday September 6 2023 Forecast (7:07AM)”

    1. bottomed out at 72 this morning.
      Currently 74 with dp 71

      Lee about to become a hurricane very soon and forecast to become a top end cat 4 at 150 mph.

    1. This is destined to be a very powerful hurricane. Current indications are that it “should” spare the islands. After that, hopefully off shore, but needs to be watched closely.

      1. Oh dear heavens. You are right. Sorry. I was excited thinking I had something to measure with my new toy ):

    2. I was surprised by “very low humidity.” We currently have temperature 72.7 and DP 72.3.

      Then I noticed that Eric posted this on May 15 🙂

  8. https://my.sfwmd.gov/sfwmd/common/images/weather/plots/storm_13_ens.gif

    Probably not good to post an image your not solidly knowledgeable on.

    I know its tracks.

    But, there is one thing. There’s that model in purple taking Lee into the Maritimes.

    I know at 00z last night, there wasn’t really any “pasta” tracks west of that purple track line and now there are.

    Euro has a trof/cutoff in the southern US late in its 00z run.

    Next 3-5 days of model watching may get interesting.

    1. I think it is too early to say it will stay off shore. Certainly
      a likely outcome, but it is not cast in stone just yet.

      I see that trough just to our West on all the models.
      The right timing and combination of tilt could be dangerous.

      Of course the timing could just as easily kick this thing well off shore.

      As you say, interesting time ahead as we watch this.

      NO matter what, even if it were to come up here, it appears
      that it would be moving slowly enough (over “cooler sub 80 water) to weaken considerably before getting up here.
      Still could be a problem, though.

    1. Yup, something Tom and I have been discussing.

      Hopefully, that gets kicked well off shore.

      We’ll be watching

  13. All sorts of questions remain.

    But everything has to line up perfectly to get that system
    up here. NOT likely, but who knows.

    1. Thanks, JPD. And I am returning the kestrel. Sadly. It is amazing when hand held. But way too labor intensive when outside collecting readings and that was the main reason I wanted

      Now to look for something new. Glad you didn’t get it

  16. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/pna.gefs.fcst.png

    https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.gefs.fcst.png

    https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.gefs.fcst.png

    Focusing around Sept 15 on these charts.

    PNA now projected +1 Standard Deviation positive. Going to be a decent ridge somewhere out west. Ridge-trof-ridge possible set up. Possible disturbances riding western ridge and how it might carve out a central US trof.

    AO slightly negative. Increases chances of a more amplified pattern vs zonal pattern

    NAO : right now, uncertain. Plenty of ensembles both sides of neutral. Potentially important how this teleconnection turns out to determine any north atlantic blocking and how that might affect the central atlantic ridge.

  17. Thanks TK.

    I find it interesting that the sea breezes have been kicking in by mid- morning. For me, pretty much right after breakfast time. They really do temper the heat right along the shoreline.

  22. I’m so happy Lee is going to cross the 60w line at 20n. Though would have liked some rain from the outer rain bands and cooler weather the further away this storm is the better. Just wish we were not going to have a south wind that’s gonna bring heat index back up

  27. This is the first September that I can remember when I’ve had to run indoors for at least 3 consecutive days. I tried running outside. I can’t. It’s unbearable outside. Not so much the heat, but the humidity.

    What has surprised me is the lack of a true break in humidity all summer. We’ve had a few days of lower dewpoints but relatively very few, even recently. It’s relentless.

    1. The closest simile to what it feels like now is Washington DC in September. I do lots of conferences there, or at least I did for many years. And I remember going there and feeling the humidity, but always returning to much less humidity in Boston.

  29. Euro is coming in Farther South than the same time period of
    the 0Z run. We shall see how that translates.

  33. When I first saw this graphic, I wondered how the high temperatures in Boston and Worcester could have been 102 and 90 or less, respectively, on the same day in 1881.
    https://ibb.co/VM77TQs

    Then I found that the records for Worcester only go back to 1895. Records like this should have an asterisk!

    1. I believe Boston records go back to the 1870s or so. Not certain about the exact year.

      Thanks for pointing that out SC!

    2. I was actually about to post about tomorrow’s record high for Boston, 102 on Sep 7 1881. I think if Boston is going to add a 5th day of 90+ to their list for the year, tomorrow’s the day, but I’m pretty confident that the record high is very, very safe. 😉

  37. Philip – regarding the early-day sea breezes. Petey B talked about this on-air yesterday (probably the only weathercast I’ve watched in about a week haha, been far too busy to do much of anything weather-related other than updating the blog in the AM).

    Very weak gradient and light wind allows the sea breeze cell to evolve more quickly, and this has been the case in what now is the “least windy” meteorological summer on record at Boston. Not a stat you’ll hear too often. 🙂

  38. One last tidbit of info before I launch into some errands that take me to another state for a while ………. The operational models are still not really the best way to look at this thing this far out. Ensembles. Ensembles. Ensembles. Similar to winter weather events.

    The likely reason for that little left jog on the operational ECMWF model from 12z is very likely the same over-amp issue we see on that model all the time. It’ll correct that, eventually.

    Also (bonus tidbit). There is a large wake cool-pool of water (a result of Franklin) in the western Atlantic that will likely result in a slightly faster weakening of Lee when it enters the region south of Bermuda. That cooler water isn’t going anywhere anytime soon.

    Da cool pool: https://photos.app.goo.gl/fnzWuffxcb7m7smb9

  39. My thermometer says 87F and it’s almost 5pm on Sept 6th. That’s warm. I know it ain’t close to a record. But the fact that it’s like this day in and day out this week is unusual, in my humble opinion. Just went out to mail a letter (yes, I still use mail boxes). 10 minutes of walking and I’m cooked.

  40. Lee is now a hurricane.

    Some important climatology info from a colleague of TK and myself:

    “Pay attention to the 20/60 intersection. In the Atlantic, this is like a magic line. Fewer than half the storms passing southwest of there strike the US. So, it’s far, far, FAR from any guarantee. Less than 50/50 even. But comparatively, to passing outside (NE) of 20/60? The difference is MASSIVE.
    I examined all storms which became hurricanes over the past 30 years and passed within the box between 15N-25N and 55W-65W. Then I calculated the US landfall rate of those NE of 20/60 versus those passing SW of 20/60. Despite being less than 50% even for the southwest ones, the difference is massive. 20/60 is like a magic point. 42% of the storms passing SW of 20/60 eventually hit the US. Only 14% of those passing NE of 20/60 reached the US coast. That’s exactly TRIPLE the rate for those passing SW of 20/60.”

    The latest forecast from NHC brings Lee northeast of 20/60.

    1. Awesome! I wondered if there was something like this but never bothered to try to figure it out.

      I bet I know who came up with that…

      1. Most of those are NOT the 00z models. Any model that has an “I” for the last letter means it is the 6-hour forecast from the previous run, as the current version has not run yet.

  44. Overnight lows won’t get under 70 anytime soon. In fact, Eric hinted at record consecutive nights 70+ for September.

    1. Look at how intense it has it at this latitude. That is impressive.
      Usual over amplification?????

      Or will Lee remain a BEAST all the way to this latitude?

  49. I think I saw a twitter post from Dr Rick Knabb last night that the NHC has scheduled one of those high altitude recon missions today, where the data they get from the atmosphere somewhere ahead of the storm’s path will get added into the models.

    Probably for the next set of 00z model runs.

  50. Lee struggling with a little bit of dry air and a couple other negative factors overnight. Delay in intensification by about 12 hours. Not a big change in the grand scheme, but a speed bump.

    New weather post…

Comments are closed.