Friday September 22 2023 Forecast (7:28AM)

94 Comments

DAYS 1-5 (SEPTEMBER 22-26)

High pressure remains in control with another day of very nice weather for the final full day of astronomical summer. Autumn arrives at 2:50 a.m. Saturday with the vernal equinox (the moment the sun is directly over the equator on its journey to the southern hemisphere, where its their first day of spring). For the weekend, we turn our attention to a moisture plume associated with low pressure well to our south. While this low center, which may acquire enough tropical characteristics to be named, drifts to the coast of NC where it moves onshore there, its associated moisture plume elongates northward in a southerly flow aloft and makes a charge at southern New England. At the same time, an amplified higher latitude pattern with a high pressure ridge in east central Canada and a deepening low pressure trough further east in Canada will create a road block of sorts for the moisture / storm to the south. One surface high (the one governing today’s weather) will slide to the southeast and leave a little weakness in the pressure field to aid in the rain’s northward progress as we get to early Saturday, but as this is happening a second surface high to the northwest of it will begin pushing toward New England. So now you see the set-up for a tough day 2 forecast – just how fast and how far north does the rain push before it gets obliterated by dry air supplied by the systems to our north? Earlier onset / best chance of steadiest rain and most amounts will be the South Coast region, while the further north you go the onset time, ability to maintain steady rain, and ability to generate measurable rain drops off quickly, as well as the amount of time this can occur, because by Saturday evening the dry air to the north should already be in the process of slicing right into the rain area. On regional radar it will look somewhat like the rain splits in two with one area drifting into NY while another peels off to the east off Cape Cod. Either way you see it, we have a dry interlude where it rained, and continued dryness in any areas the rain never quite reaches. The greatest chance for the latter are places from around the MA/NH border into NH where it may only sprinkle lightly or not rain at all from the initial push of rain. All during this, with high pressure to the north and low pressure well south southwest of our region, we’ll set up a cool northeasterly air flow with below normal temperatures for the weekend. Patches of drizzle can evolve eventually, favoring the east-facing coastal communities where the wind will be directly off the ocean. This is most likely to happen later Saturday night into Sunday. During Sunday and Sunday night, and into early Monday, what remains from the low to the south will make its way northward through the Mid Atlantic, and then as a remnant low into the waters south of New England. It’s during this time when our region can see additional periods of rain along with continued areas of drizzle and some developing fog, though the gusty wind that had developed especially along the South Coast during Saturday will ease off some, because low pressure will be much weaker. Eventually, the stronger features to our north will push that remnant low away later Monday, but we still have to wait for upper level low pressure to cross the region through Tuesday. This means Monday would probably remain generally cloudy even if it starts to dry out in terms of rain chances, and Tuesday would be day that if any sun was to shine, it would help trigger lots of clouds, but I think the air would be dry enough to prevent much shower activity from developing. Those days will also feature a continuation of below normal temperatures for the early days of autumn. Also, the wind that had eased off a little Sunday would pick back up again as the pressure gradient tightened up behind now-regorganizing low pressure and the high to the north and west.

TODAY: Sunshine becomes filtered through an increasing shield of high clouds. Highs 66-73, coolest coast. Wind variable becoming E up to 10 MPH.

TONIGHT: High overcast. Low elevation ground fog patches. Lows 47-54. Wind E under 10 MPH, calm in some low elevations.

SATURDAY: Overcast may be thin enough for some sun in the morning-midday especially north of I-90 otherwise thickening overcast with time. Rain likely South Coast, tries to push north but very slowly and may struggle to get to areas north of I-90 doing so only as patchy and light. Highs 61-68 with a cool-down to under 60 especially near east-facing shores by late in the day. Wind E to NE 5-15 MPH but 15-25 MPH South Coast including late-day higher gusts around Cape Cod.

SATURDAY NIGHT: Cloudy. Any lingering rain ends / dissipates. Areas of drizzle/fog overnight favoring eastern coastal locations. Lows 52-59. Wind NE 5-15 MPH, higher gusts near the South Coast.

SUNDAY: Cloudy. Areas of drizzle and fog. Periods of rain, favoring the South Coast to I-90 region. Chance of rain at times further to the north. Highs 58-65, coolest eastern coastal areas. Wind NE 5-15 MPH.

SUNDAY NIGHT: Cloudy. Areas of drizzle and fog. Periods of rain, again favoring southern areas. Lows 50-57. Wind NE-N 5-15 MPH.

MONDAY: Mainly cloudy. Best chance of rain southeastern areas morning. Highs 60-67. Wind N 10-20 MPH, a few higher gusts possible.

MONDAY NIGHT: Breaking clouds. Lows 50-57. Wind N 5-15 MPH and gusty.

TUESDAY: Lots of clouds – intervals of sun. Highs 60-67. Wind NW 10-20 MPH and gusty.

DAYS 6-10 (SEPTEMBER 27 – OCTOBER 1)

High pressure builds in from Canada with a stretch of dry weather from mid week to at last the start of the weekend (September 30), but may have to watch to our south once again for low pressure threatening the region with rain by the end of the period (October 1).

DAYS 11-15 (OCTOBER 2-6)

General pattern should feature high pressure to our north and the tendency for additional low pressure to our south, leaving our region somewhat vulnerable to battle zone unsettled weather, but my continued leaning is that high pressure to the north will be close enough / strong enough to keep us drier more often than wet.

94 thoughts on “Friday September 22 2023 Forecast (7:28AM)”

  1. Taking my son to Fenway for our 12th and final game of this somewhat disappointing season. Thoughts on how wet it is for a 4:10 PM first pitch there? Of course this is the first game all season we didn’t get tickets under cover in the infield grandstand because we could get up close for cheap….

    2. I’m going to predict the game gets played. Whether it has a delay in it at some point remains to be seen.

      1. I like what I’ve seen from some of the kids–Casas looks like a force in the middle of the lineup, Duran had a great bounce back year until he got hurt, Abreau and Rafaela both look like solid big leaguers. In the offseason they need to address starting pitching, starting pitching, starting pitching, and starting pitching!

  13. In the for what it is worth department, the 12Z HRRR has MORE rainfall than the 6Z run at the same time period.

    Comparing 6Z total qpf at 48 hours with 12Z at 42 hours.

    6Z qpf

    https://www.pivotalweather.com/model.php?rh=2023092206&fh=48&dpdt=&mc=&r=us_ne&p=qpf_acc-imp&m=hrrr

    12Z qpf

    https://www.pivotalweather.com/model.php?rh=2023092212&fh=42&dpdt=&mc=&r=us_ne&p=qpf_acc-imp&m=hrrr

    And of course this is NOT the entire event as there will be at least “some” additional rainfall.

  15. We’re a little more than 24 hours from onset and STILL no agreement among the models. What a way to run an airline!!!!

    GEEZ!!!!

    1. A very sharp cutoff just to our north. Would love to see it further south but given this now “past” summer, that would be expecting too much.

  23. If this were a “potential” snow event, I would be going bonkers
    right about now. With this, I don’t give a S***!!!

  28. I am with ya JP if this was winter.

    I feel like we are using up all our blocking and great storms tracks will go dry and NAO probably goes + in December. Lol

  31. I just removed all my Hawaiian shirts from the closet and brought them downstairs to storage, and brought the sweatshirts from storage upstairs and into the closet. I hereby declare summer officially over now.

    1. I’m with you. Just uninstalled AC #1. At my age, I only do one a day. Can’t do more than 1 in a single day. 🙂

    3. I love how different people have their official starting / ending events for such thing. 🙂

      I have my own but sometimes they change. Like when do I put away the outside furniture and/or drain and store the garden hoses… 😉

  34. Even the NHC is uncertain of Ophelia’s track. The cone extends only as far north as extreme southern New Jersey.

    1. That’s not because they are uncertain. The uncertainty (or most likely margin of error) is indicated by the cone. The reason it stops is because they expect the storm to be non-tropical in 48 hours, and dissipated by 72 hours.

      This one is actually a pretty straightforward forecast, in terms of the low’s position and status.

      The uncertainty lies in how much punch the rain area way ahead of it has into SNE tomorrow, which is nothing they really need to worry about. 🙂

  35. 18Z NAM has a more robust phase 2 part of this upcoming event.

    Waiting for run to complete to post rainfall comparisons.

        1. I still think phase 1 is going to be less than most “advertisements” indicate.

          Phase 2 will be working on a slightly more saturated atmosphere. I don’t think it will be impressive, but I think it will be wetter, for longer.

      1. I’ve been impressed with its performance. The replacement of the HRRR by the RRFS is delayed until next year though – not sure why.

      2. Out through 19z, it has the northern edge of the rain about 30-40 miles further south than the NAM (12km).

  38. What a drastic change in 24 hours for the Canadian.

    Yesterday’s 12z run had 2+ inches of rain across all of SNE and the northern edge of the rain on the US / Canada border.

    Today’s 12z run has 2+ inches confined to the immediate South Coast, a rapid drop-off as you go north, and no rain at all north of the MA/NH border.

  39. I have family in Camden, NC. They are located 30 miles NW of Kitty Hawk. I’m watching a weather station about 0.1 mile from them. It’s recorded over 2.5″ of rain already and the rate is about 0.5″ per hour. There hasn’t been much wind yet.

  40. Seems we had back to back anniversaries of severe hurricanes. The link was posted before the discussion of 38 but I decided to wait as it stands in its own. Although this guy has his own special place.

    Hard for me to believe Hugo was 34 years ago last night into today. Mac’s parents lived in Mt Pleasant SC with the barrier island, Isle of Palms, the only thing separating them from the ocean. They fortunately were at their daughters in Spokane

    https://imgur.com/a/BxYwRaE

    Amazing that Hugo was still a cat 1 as far inland as Charlotte. He did considerable damage in and around Mac’s aunts home. And the comparison of cost and number to Evacuate……well, wow

    1. I remember Hugo’s satellite loop showing me one of the scariest looking hurricanes just making a beeline into the coast and it was moving so quickly it just held together much further inland.

      That was a nasty storm.

      1. Sure was. Lots of damage in the snee farm area where my in laws lived but not their condo. Everywhere else was a mess

  41. 18z GFS now gives about 1/4 inch rain to the South Coast and about 0.01 to Boston for “part 1” on Saturday. Even drier than previous op run.

  43. TK – Did we get much in the way of remnants (rain and/or wind) from Hugo? Any flooding or damage up this way?

  44. Question for all….As of tonight is Sunday late am or Saturday late am looking like a better outdoor bet. Thank you ❤️

  45. Maybe it’s wishful thinking, but it seems like consensus is building for lower rain totals among the models. Will this ultimately be reflected late tonight or early tomorrow morning? Thanks.

      1. Basically I still carry the same forecast. A slow onset of rain from south to north tomorrow, so anything is still best weighted toward the morning if possible. Sunday’s a wildcard. Some guidance has the rain coming back later, so there may be another shot at staying dry for a while. Kind of a play-by-ear situation. 🙂

  48. TV mets continue with decent rainfall later today, lighter tomorrow (Sunday) but a washout of a weekend nevertheless. Their models show 0.6” for Boston.

    The Ch. 7 met actually used the word “washout”.

    1. Boston will receive more rain from the Sunday / early Monday portion, or part 2, than they will from today’s portion, or part 1.

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