Thursday Forecast

137 Comments

7:01AM

DAYS 1-5 (JULY 21-25)…
During the overnight hours, a clear sky, light wind, and low dew point allowed temperatures to drop into the 50s in many areas away from the cities, while the asphalt and cement of the urban areas held temperatures in the 60s – the urban heat island effect. But this morning the sun will go to work and temperatures will heat up fairly rapidly and end up fairly uniformly in the 80s in all areas by about noon. The difference during the afternoon will be less pronounced, but still there, as many interior areas make a run at 90 while the coast is a little cooler due to a light sea breeze. So today will be a good clear air natural weather lab kind of day in southern New England. As high pressure sinks to the south and a southwest wind flow gets going by tonight, the humidity will increase, and this will lead to a hot and humid day on Friday, but an approaching upper level disturbance and series of surface troughs will lead to more cloudiness at times as well as the risk of a few waves of scattered showers and thunderstorms right into Friday night. Any storms have the potential to be strong, but at this time it does not look as if the entire area will be swept with strong or severe storms and that such weather will be isolated to scattered at best. The heat will hang around for the weekend though may ease back slightly for part of the weekend. Saturday will still carry a slight risk of isolated thunderstorms as a final disturbances traverses the area. The next disturbance due later Monday will again increase the risk of showers and storms.
TODAY: Sunny. Highs 75-82 Cape Cod and Islands, 82-87 other coastal areas but may cool down slightly during the afternoon, 87-92 elsewhere. Wind light W but with light coastal sea breezes developing.
TONIGHT: Mostly clear. Increasingly humid. Lows 60-65 except 65-70 urban areas. Wind light SW.
FRIDAY: Intervals of clouds and sun. Isolated to scattered showers and thunderstorms possible. Humid. Highs 78-85 South Coast, 86-93 elsewhere. Wind SW 10-20 MPH with higher gusts.
FRIDAY NIGHT: Variably cloudy. Isolated to scattered showers and thunderstorms. Any storms may be strong to locally severe. Humid. Lows 67-74, warmest urban areas. Wind SW to variable 5-15 MPH.
SATURDAY: Partly to mostly sunny. Slight risk of isolated thunderstorms. Humid. Highs 80-87 Cape Cod and Islands, 88-95 elsewhere. Wind NW 5-15 MPH.
SATURDAY NIGHT: Partly cloudy. Humid. Lows 67-74, warmest urban areas. Wind light NW.
SUNDAY: Mostly sunny. Humid. Highs 78-85 Cape Cod and Islands, 86-92 elsewhere.
MONDAY: Partly sunny. Chance of afternoon and evening showers/thunderstorms. Humid. Lows 65-75, warmest urban areas. Highs 84-91 South Coast, 92-98 elsewhere.

DAYS 6-10 (JULY 26-30)…
Warm and humid with a risk of additional showers and thunderstorms July 26 as a disturbance passes through the region and a frontal boundary sits nearby. High pressure brings fair, warm, and less humid weather July 27. More humidity and a risk of showers/storms returning sometime July 28-29 before a return to warm to hot and dry weather by the end of the period.

DAYS 11-15 (JULY 31-AUGUST 4)…
A warm to hot and dry start then humidity returns with a few episodes of showers/thunderstorms at times in the early days of August.

137 thoughts on “Thursday Forecast”

  2. Was writing this and posted on previous blog. 😀
    Thank you TK.

    Morning.

    Taking a quick look around at the model sites, I am less and less impressed with
    the severe parameters for tomorrow afternoon/night. In fact not only less chance of severe, but looking more and more like little to NO rain for the Boston area.

    I suppose things could still change. We shall see.

    SPC still has us in the slight chance of severe area.

    http://www.spc.noaa.gov/products/outlook/day2otlk_0600.gif?1469098917851

    NWS discussion same as it was yesterday.

  5. Thanks TK !

    So here was Minneapolis, MN at midnight last night …..

    84F with a dewpoint of 77F !!!!!! for a heat index of 94F. South wind only at 9 mph.

    Thankfully a thundershower with a gusty northerly wind has dropped it to 73F with a dewpoint of 67F.

    I’m going to guess that residential A/C in that area is not as widespread as in our area.

  7. I am thinking that the SPC removes our area from the Slight Severe risk at the next
    update (1-1:30 or so? I think) and either replace us with Marginal or perhaps even
    general thunderstorm. Perhaps Northern VT, NH and ME remain in slight. Just a
    my current thinking. I could be totally out to lunch. We shall see.

  8. Thanks TK.
    The SPC did shift the slight risk north and only has northern CT in that area. Yesterday the entire state was in the slight risk.

    1. Yes and that was updated at: Issued: 07/21/2016 at 0559Z
      OR 1:59 AM this morning. I suspect more of a shift with the next update.
      We shall see.

      Perhaps the 12Z runs will see things differently? Who knows.
      latest runs were NOT impressive, imho. Thunderstorms? Yes, I suppose.
      Severe? hardly, perhaps an isolated one here or there. Nothing widespread.

      Again, could change. Will continue to monitor, but I feel like the air
      has been slowing leaking out of the severe balloon. 😀

  9. Tweet from meteorologist Ryan Hanrahan for tomorrow.
    Any severe weather tomorrow would likely be after dark. In fact I wouldn’t be surprised if it’s after 10 p.m.!

    Here was a question for Ryan on that tweet
    Wonder if loss of day time heating hurts areal coverage of strong/Severe storms

    His Response
    Not really – this kind of setup supports nocturnal storms

    1. Thank you again for this. Keep em coming.

      I think he is a hold out and doesn’t want to give it up yet.
      Hey, perhaps he is correct. We shall see.

  11. The only thing I am thinking is will and EML be in place tomorrow night which could keep the storms strong to severe even when were past peak heating.
    I believe back in February when we had those strong to severe storms overnight and EML was present.

  13. Tom, what you wrote about Minneapolis makes it seem like a city in southeast Asia. Midnight temp of 84F with a dewpoint of 77F. I get a headache just looking at those numbers. Needless to say, Minneapolis is far from tropical on most days. I was there this year on May 13th and there was a snowsquall, with temps hovering in the 30s.

    1. Too far North and their location places them TOO CLOSE to the cold air source.

      I wouldn’t live there if you paid me a King’s Ransom.

  15. This is from the 0Z NAM last night.
    Look at this sounding. Looking at the coordinates it is somewhere in West Central, VT?
    I don’t get that, but what I am pointing out is the Potential Hazards. Note that it
    indicates: PDS TOR

    PDS
    tornado (TOR) watches are issued when the forecaster
    has high confidence that multiple strong (F2-F3 on the
    Fujita Scale) or violent tornadoes (F4-F5 on the Fujita
    Scale) will occur in the watch area.

    Link to sounding:

    PDS
    tornado (TOR) watches are issued when the forecaster
    has high confidence that multiple strong (F2-F3 on the
    Fujita Scale) or violent tornadoes (F4-F5 on the Fujita
    Scale) will occur in the watch area,

  17. Little twitter dialogue for tomorrow with Ryan Hanrahan and capecodweather.net. capecodweather.net is Meteorologist forecasting the Weather on Cape Cod and Working in Emergency Management / Disaster Preparedness. MS Applied Meteorology
    capecodweather.net similar thought.
    Similar thought he is referring to is Ryan’s tweet which I posted earlier
    Ryan that 7+C/km plume of h5-h7 lapse rates on GFS argues for severe nocturnal convection I think
    capecodweather.net yeah definitely has that look. there on the NAM as well (actually more so)

        1. That’s a good question !!

          I think it has 3 things currently working for it.

          1) the disturbance in south-central Canada

          2) the 70s + dewpoint environment it’s in

          3) its location on the 500 mb ridge ring of fire

          For us tomorrow, I think #1 also happens here (the disturbance). It won’t have the magnitude of humidity currently in the Midwest and (I’m also not sure about New England being located within the ring of fire or under the outer edge of the ridge ??)

          Tomorrow will be interesting to watch it unfold.

        3. We won’t get that particular set of storms. It’s the area of instability that will bring the risk but it will be developing much closer.

  19. There is a severe thunderstorm watch where that area of thunderstorms is going and looking at the SPC site there have been some 5 wind reports 3 hail reports. I would expect those severe weather reports to increase.

  20. Quick peak at 12z NAM on cod website and strong to severe storms still on the table with some fairly potent severe parameters which come after peak heating.

  21. Keep in mind that this is likely to be an event that produces scattered strong storms and isolated severe storms. NOT widespread.

    Greater parameters DOES NOT mean greater coverage.

  23. With the Pivotal site, placing the mouse on any map, will give you the Actual value
    for any chart. Pretty damn cool feature.

  24. HRRR shows up to 93 today for areas “just’ West of the Coast.
    Shows Logan topping off at about 85. We shall see on that.

    1. COD has the same feature. It also has the sounding feature, so IF you left click
      the mouse over a location, you get the sounding info for that location, including
      any possible hazard type. Pretty cool.

      1. At least on the regular NAM and the GFS. I don’t see it avaialable
        on the 4KM Nam. Too bad.

  27. I read that the other day. Excellent write up by Eric.
    Good twitter chat between Ryan and Capecodweather.net with regards to tomorrow’s potential which was posted here earlier.

  28. Some discussion from the Albany NWS office.

    Our thinking continues similar to yesterday at this time…as an
    active day of shower and thunderstorm coverage is likely. The one
    new wrinkle is an elevated mixed layer /EML/ may linger well into
    Friday night. Steep lapse rates in the northwest flow aloft
    persist until 03Z-09Z according to the GFS and NAM.

    BUFKIT soundings from the NAM/GFS indicate
    moderate to large instability with thick CAPE profiles. Large hail
    and damaging winds would be a threat with possibly multiple rounds
    of convection well into the night. The thick CAPE does not
    diminish until well after midnight across most of the fcst area.
    The convective environment will likely be the most unstable of the
    warm season.

  29. Latest SREF still not bullish on severe for tomorrow night.
    Has all of the severe parameters diminish to practically nothing as the system
    moves Eastward. We shall see. Wondering IF it is not performing well.

    The significant tornado and supercell composite that is showing on the
    NAM and GFS, just isn’t showing on the SREF

      1. Too bad, because often times it does perform well.

        Do you agree that the instability may stick around until about
        12Z on Saturday?

  31. Quick peak at 12z GFS not as aggressive as 12z NAM but enough instability being shown for strong to severe storms past peak heating.

  32. Checking the 12Z GFS in Pivotal Weather and it shows most of the action (including the EML) moving quite a bit South of our area. Has Boston only BRIEFLY in a Marginally severe hazard at 3Z Sat. Most severe over Southern NY and in PA. Unless, of course, I am not reading it correctly.

  33. Dave I am noticing when running the loop on cod site with some of the severe parameters. The biggest look to be NYC area just clipping Fairfield County CT. Still all of SNE in play for strong to severe storms though.
    One thing the 12z American Models agree upon the peak instability after peak heating time of the day.

  34. Boston is now 85. “probably” NOT destined for 90.
    Wind WSW gusting to 22. Predicted sea breeze does not look likely now.

  35. Little change with the latest SPC update for tomorrow:

    http://www.spc.noaa.gov/products/outlook/day2otlk_0600.gif?1469122365995

    discussion:

    …NORTHEAST STATES…
    NY INTO WESTERN AND NORTHERN NEW ENGLAND WILL CONTINUE TO
    MOISTEN FROM WEST TO EAST AHEAD OF A COLD FRONT ON
    FRIDAY…WHILE SOUTHERLY LOW-LEVEL FLOW INTO SOUTHERN NEW
    ENGLAND SUPPORTS BOUNDARY-LAYER MOISTENING IN THAT PART OF
    THE NORTHEAST. THERE REMAINS SOME UNCERTAINTY WITH THE
    DEGREE OF DESTABILIZATION THAT CAN OCCUR THIS
    FORECAST PERIOD ACROSS THE NORTHEAST STATES. THIS WILL BE DUE
    TO LATE DAY 1 STORMS AND ATTENDANT CLOUDINESS SPREADING IN LEE
    OF THE LOWER GREAT LAKES AND UPPER SAINT LAWRENCE RIVER VALLEY
    INTO THE EARLY PART OF DAY 2. DESPITE THIS FACTOR…THE ONGOING
    BOUNDARY-LAYER MOISTENING…MIDLEVEL LAPSE RATES AROUND 6.5
    C/KM AND EVEN POCKETS OF SURFACE HEATING SUGGEST MODERATE
    INSTABILITY SHOULD OCCUR ACROSS THE WARM SECTOR. FORCING FOR
    ASCENT ATTENDANT TO THE PASSAGE OF A LEAD SHORTWAVE TROUGH
    AROUND PEAK HEATING AND IN VICINITY OF A PRE-FRONTAL TROUGH
    AND COLD FRONT SUGGEST THE AVAILABLE INSTABILITY AND
    STRENGTHENING NORTHWESTERLY WINDS ALOFT
    WILL SUPPORT STORMS. SOUTHWESTERLY LOW-LEVEL WINDS VEERING
    AND STRENGTHENING WITH HEIGHT SHOULD ALLOW FOR ORGANIZED
    STORMS WITH DAMAGING WINDS AND HAIL BEING THE PRIMARY
    THREATS.

  36. Logan, currently at 88. I guess we could say that is an official run at 90 Degrees.
    Dew Point is at 50. NICE!!

  37. From Taunton NWS discussion a few minutes ago:

    While winds/hail remain the primary risks, especially since
    shear/CAPE profiles support MCS organization which would peak
    overnight (at the point of EML peaking), there is a low end
    tornado risk given the lowest lvl shear values and EHI between
    1.0-2.0. However, not a pure S New England tornado break case per
    internal study and the very dry mixed layer (high LCLs).

  38. Here is the 12Z NCAR ARW WRF 15km Forecast for the Vorticity Generation Parameter:

    Most robust in Eastern MA is 0Z Sat (8PM Friday)

    http://www2.mmm.ucar.edu/prod/rt/wrf/wrf20/2016072112/vgp.hr36.png

    You will note that the value is Orange or .4 to .4 with Yellow, .2 to .3 to the West
    of the Boston area.

    VGP = Vorticity Generation Parameter. The VGP is meant to estimate the rate of tilting and stretching of horizontal vorticity by a thunderstorm updraft. Values greater than 0.2 suggest an increasing possibility of tornadic storms.

  39. 12Z Euro has some severe parameters. Looking them over, I think they suggest
    Marginally severe to possible severe. Not as robust as the NAM.

  40. Logan touched 90 at 1:55 PM, unless they change it later. Here is the obs:

    21 Jul 1:55 pm 90 48 24 WNW 10 10.00 FEW065 30.04 30.027

  41. Is there a time frame for the riskiest period tomorrow

    Sorry if someone posted and I missed.

    So far any action down here has been during nap. Perhaps I could answer my own question. 🙂

    2. Depends on your model of choice. Late evening, say 7 or 8PM up to around 11 PM and possibly beyond to 2AM. But where still 2 days out so clearly subject
      to change.

  43. There’s a million different indices out there now, and you guys seem to look at everyone single one of them. Too much data. WAY too much data. Makes everyone over-analyze everything, and ultimately end up disappointed almost every time.

    I still look at the same basic ones I’ve been using for the past 20-25 years: Lifted Index, CAPE, K Index, SWEAT, and Total Totals. That and a look at the what is actually going on now tells me all I need to know 95% of the time.

    1. Good one SAK. Guilty as charged, but guess what? I am not going to stop
      looking at everything I can get my hands on.

      Btw, where does one locate the K Index. I always see NWS discussing that, but
      have not come across that index in a model. Perhaps I have overlooked it all these years? 😀

      1. You can calculate it using this formula: K= (T850 -T500) +TD850 – (T700-TD700)

        T850 = 850mb temp
        TD850 =850mb dewpoint
        T700 = 700mb temp
        TD700 = 700mb dewpoint
        T500 = 500mb temp

        21-25 = isolated t-storms possible
        26-30 = widely scattered t-storms
        31-35 = scattered t-storms
        36-40 = numerous t-storms
        41+ = widespread t-storms

        http://twister.sbs.ohio-state.edu/upper/charts/k-index

    2. I was a blackjack card counter. You want to know how many indices I knew in addition to the 256 different basic strategy plays? It’s mind blowing. 😀 😀 😀

    3. Well NOW my secret’s out! Same indices I most heavily rely on. Did I tell you that years ago? Just kidding. 😉

      I’ve never been a fan of Too Much Information, except for the song by the Police of course. 😀

      1. You’ve seen me say this on Facebook a million times, but I am so happy that you and I learned meteorology when we did, before most of the models were freely available. We actually had to learn the meteorology and how to actually forecast, not just look at the models and decide which one looks best or fits with what we want to happen.

        1. It was of great benefit! I still use many of the “old ways”, in fact I rely more heavily on those than the “click-and-read” style that many met’s learn today. There is great value in building a forecast from scratch. You won’t be right every time, but when you do mess up, it’ll be easier to learn from it too!

          1. Awesome. You 2 could never be accused of being model huggers, that’s for sure. 😀

  44. Tweet from Eric Fisher
    Doesn’t look like things are going to link up right for widespread severe tomorrow. Instability & forcing not overlapping right

    1. Now there’s a surprise. We were seeing that this morning.
      Still could change. I wouldn’t write off just yet.

  45. I agree. Though from that tweet sounds like it could be a repeat of Monday where some towns get hit hard and other towns nothing at all.

    1. Agree. He said no widespread severe. That does not mean that there couldn’t be a severe storm here and there. Ie isolated.

  47. Here is a response Eric Fisher gave on twitter to someone with regards to tomorrow.
    I’m thinking a couple afternoon pulse severe storms, but then a line moving down overnight.

  48. 18Z NAM is cooking. Out to hour 12 on instant weather maps.

    We shall see what it has to say very soon. 😀

  49. With those pulse type storms you look at the radar and an area doesn’t look impressive then all of sudden the thunderstorm gets stronger and sometimes reaches warning criteria but as quickly as it does that it weakens. I believe several years back there was one of those type storms around the Hopkinton, MA area where it quickly became severe and produced a microburst then weakened big time.

    1. Thank you. I guess they are pretty much on board.

      18Z NAM CAPE numbers are high throughout the area. Simulated radar
      shows convection in Eastern sections from 8PM through 10 PM and possibly beyond.

  51. That cloud cover is one piece to the puzzle I get from reading the discussion. If it stays cloudy we MAY catch a break but if that sun comes out with the humidity in place watch out. Taunton keeps the threat low for an isolated tornado but its there and something to watch.

  52. Look at this Boston area sounding chart of the Pivotal Weather 18Z NAM for 21Z tomorrow. Best parameters are right around 21Z.

    http://soundings.pivotalweather.com/sounding_images/nam_2016072118_027_42.25–71.2.png

    CAPE: 3085
    DCAPE: 1711
    1KM EHI: 1.3
    3KM EHI: 3.3

    Hazard: SVR

    Same time period, sounding north of Worcester:

    http://soundings.pivotalweather.com/sounding_images/nam_2016072118_027_42.59–72.26.png

    Hazard: TOR

    CAPE: 4568

    Now, these are most likely over cooked, but clearly, severe is possible.

  53. I agree totally over cooked as per usual with NAM. Even if you could those values down still enough juice for strong to severe storms.
    Interesting from the Taunton Discussion RPM and NAM are somewhat more favored over other guidance though WRF solutions are handling well the anticipated forecasted MCS overnight.

  54. Tweet from meteorologist Ryan Hanrahan
    First time I’ve ever seen the NWS siding with @weathercompany ‘s RPM model for their forecast

    1. An Overview of WSI’s 4km RPM Model

      Peter P. Neilley, WSI, Corp, Andover, MA; and T. A. Hutchinson

      Since 2004, WSI has operated a version of the WRF-ARW model intended for use in various operational weather forecasting applications, including broadcast meteorology. Select products from our WRF model are packaged into a dataset distributed to broadcast meteorologists under the RPM (“Rapid Precision Model”) brand name. In 2008, WSI increased the resolution of its WRF model (and RPM datasets) to 4km. This was the nation’s first CONUS-domain numerical model operating at such resolution, and the first fully convective resolving model in operational use.

      In this presentation, an overview of WSI’s RPM model will be provided. Case studies illustrating the advantages of a convective-resolving model compared to lower-resolution convective-parameterizing models will be shown. Validation of temperature and precipitation forecasts compared to NCEP model’s will also be shown. Future directions of WSI’s numerical weather prediction program will also be discussed, including the development of rapid-update forecast capabilities based on radar data assimilation techniques. Recent tornado-generating case studies using the data assimilation will be shown.

  55. I still see mixed signals from the models.

    I guess we’ll be now-casting late tomorrow or should I say Radar Gazing.
    Or on a more sinister note, we’ll all be Radar Voyeurs. 😀

  56. Little twitter chat on RPM
    Question for Ryan Hanrahan is it publicly available? Is it particularly good at anything, historically?
    Response It’s good. It’s WRF-based model

  57. Thank you Dave for your answer to my earlier question re timing. Althiugh I like T storms after dark, I’m never a fan of any tornadic potential.

    Also …for one I say keep posting the different links. For one, gives me some lessons in how the models work and what they are saying.

  58. TK, thanks for the response on the Bermuda outlook last night. The GFS is behaving the last few runs and must have listened to you!

  59. I am working tomorrow night so hopefully the thunderstorms will happen when I am at work and not driving home. Back in February I was coming back from work around midnight and even before the thunderstorms came through the winds were gusting. I was just parking my car in my parking spot and that thunder was loud and the winds gusted as have not gusted that strong here since Sandy.

  60. I just had the pleasure of spending a couple of hours with Tom and Sue. It is a perfect way to the end of my vacation. I do wish it could have been more but the drive here at this time of night is nasty. Next time more central.

    2. It was wonderful spending time with you and Tom. I am so glad we were able to make it happen. Couldn’t have asked for a better way to spend a couple hours this afternoon. Thank you both!

  62. Is the moon at perigee? I’m wondering why at full moon the tides are as low as I see them here

    1. A few days away from perigee but close enough to perigee to be exerting a good amount of pull. And then we’re just past the full moon, so that’s also adding to the pull.

      Tomorrows high tide will be a bit higher and its low tides will be a bit lower still.

      1. Thanks Tom. Perigee is further from moon…right?? Son in law checked miles from sun and thought we were closer than normal

            1. Full and new moons have increased gravitational pull and thus bigger tidal ranges.

              Separately, a perigean moon increases the gravitational pull, apogean moon decreases them.

              The biggest tides occurs when the full or new moon is at perigee because the 2 compound each other.

  66. St Louis today …..

    5 pm ob : 98F, dewpoint : 75F, heat index : 111F

    11 pm ob : 90F, dewpoint : 75F, heat index : 101F

    In combination with other atmospheric factors, it’s no wonder there’s another huge complex of storms diving SSE through the Midwest.

    1. I’ve been to plenty of places across this great Nation, and St. Louis was, ummm…..well…..ummm……yeah, I got nothing. It’s just an awful place, especially in the summer.

      1. nws

        Tornado…
        Low risk, but non-zero. Very high LCLs is not overly supportive.
        However should an isolated supercell structured storm develop
        especially in the vicinity of the southern sea breeze or other
        localized low-lvl vorticity source, this will need to be watched.
        EHI values already progged to be between 1.0-2.0 and near sfc
        lapse rates are nearly dry-adiabatic thanks to mixing.

  70. from what I can see, the sounding info form the cos site s different than pivotal weather.
    not as robust.

Comments are closed.