Tuesday Forecast Update

119 Comments

7:25AM

DAYS 1-5…
No major changes to this forecast except a little more optimistic heading into the holiday weekend.
TODAY: Mostly to partly sunny into afternoon then increasing clouds later. Highs 75-82 but turning cooler in coastal areas during the afternoon. Wind light variable through midday then SE up to 10 MPH.
TONIGHT: Mostly cloudy. Slight risk of showers. Lows 60-67. Wind light SE.
WEDNESDAY: Variably cloudy. Showers and thunderstorms likely in the morning and early afternoon. Scattered to isolated showers and thunderstorms later in the day with possible strong storms. Highs 75-82. Wind SW 10-20 MPH and gusty.
THURSDAY: Mostly sunny. Lows 60-67. Highs 78-85.
FRIDAY: Partly sunny. Lows 58-65. Highs 75-82.
SATURDAY – INDEPENDENCE DAY: Partly cloudy. Lows 60-67. Highs 78-85.

DAYS 6-10 (JULY 5-9)…
Sunday July 5 looks warm and dry. The early and middle portion of next week looks seasonably warm with a couple shower and thunderstorm opportunities from late on July 6 through early July 9.

DAYS 11-15 (JULY 10-14)…
Temperatures are expected to average close to normal with rainfall near to below normal, though opportunities for a few showers and storms with heavy rain will be present between a trough to the west and an offshore high pressure ridge.

119 thoughts on “Tuesday Forecast Update”

  2. Thank you TK for the update.

    Suggestion.

    When you make a new blog post in the AM, would it be possible to grab
    any recent posts and carry them over? (Use your best judgement as to a cut off time) For example this morning I posted a bunch of stuff from 6AM to 6:45 AM and the blog was updated at 7:25AM. JJ also made a few posts. Now there is a new blog post
    and the posts we made are now in oblivion.

    Just a thought.

    Have a great day all. Even Smells like a gorgeous day out there. Absolutely beautiful!!!!!!

  4. Thanks TK !

    Smoke now into the Ohio Valley, just behind this feature approaching New England.

    I have a feeling hazy skies may be possible once this feature passes by.

  6. JJ good thought.

    I am going to re-post the most robust of the instability parameters from the 6Z Canadian
    as follows:

    Old Salty says:
    June 30, 2015 at 6:08 AM
    6Z runs are a bit fickled. Looks like instability is back in the cards.

    Here is the 6Z CMC-RDPS a.k.a. GEM-REG / North America (mesh: 10 km)

    21Z CAPE

    http://img.meteocentre.com/models/gemreg_amer_qc_06/BE_BE_PN_039_0000.gif

    21Z LI

    http://img.meteocentre.com/models/gemreg_amer_qc_06/LI_PN_UU_VV_039_0000.gif

    21Z EHI

    http://img.meteocentre.com/models/gemreg_amer_qc_06/HI_PN_039_0000.gif
    Reply

  8. NWS out of Upton, NY the only discussion I have seen much possiblity of weak rotation for tomorrow.
    WITH DECENT SHEAR PROFILES AND LLJ…CANT RULE
    OUT AN ISOLATED STRONG TO SEVERE STORM WITH EVEN SOME WEAK ROTATION
    ALONG WARM FRONT/DEVELOPING TRIPLE PT WAVE. POTENTIAL IS LOW
    OVERALL…BUT SHOULD INCREASE THROUGH THE MORNING INTO EARLY
    AFTERNOON WITH BUILDING INSTABILITY

    1. Eric Fisher on Channel 4 Boston, outright said that there was a possibility
      that “some” storms could rotate on Wednesday. Now he did NOT say
      the possibility of a tornado, but CLEARLY said ROTATE. I guess one has
      to read in between the lines. IF a storm can rotate, I think it may be
      possible for a touch down? No?

      1. Rank amateur weather-watcher here: I have been caught sailing in what we used to simply call a “wicked squall”; and seen the “rotation” of that little storm act like a mini-hurricane. Start with dead calm, then wind and rain blowing from the NW and the wind direction rotated around and ended up from the SSE in a matter of 8-10 minutes. Winds like a mini-hurricane. Could that be what he is referring to?

  9. Interesting, 9Z SREF has an ever so slight risk of tornadic activity back in the game.
    Will continue to monitor that feature.

    Ingredients

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_prob_combined_sigtor__f033.gif

    Parameter

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_SIGTOR_MEDIAN_MXMN__f033.gif

    Until we start seeing 1s and 2s here, not too significant a risk. It’s not zero, it is
    still very small but not non-zero.

    Helicity

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_1KMHEL_SSB_MEDIAN_MXMN__f033.gif

    Shear

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_0-6KMSHR_SSB_MEDIAN_MXMN__f033.gif

    Shear still indicates the “possibility” of severe storms. No guarantee, just the possibility at this point.

    It’s still a watcher as JJ would say.

  10. Both NWS discussions out of Upton, NY and Taunton, MA indicating a good amount of shear in place tomorrow. When you have a good amount of shear in the atmosphere you COULD get a rotating storm. Two years ago we had a situation here with no sunshine and one of those low CAPE high shear environments and a thunderstorm that produced two weak tornadoes here in CT before lifting into the Worcester area and that prompted another tornado warning. I can’t remember if on touch down up there.

    1. I really think we’ll be fine, but we should proceed cautiously as we do not
      want to be surprised. Parameters are kind of marginal for tornadoes, BUT,
      that is just when we best be careful.

      I remember in the 90s the SPC completely missed the Great Barrington, MA
      EF3 tornado. No watches, nothing, YET it occurred. It can and does happen and that is why we watch carefully even if parameters are marginal.

  12. These severe parameters are nowhere near what we had last Tuesday. With that said can not completely rule out a strong to locally severe storm.
    Last year in Upstate, NY SPC did not highlight that area and there was a tornado touchdown. I believe WXwatcher commented on it as it happened and posted the radar image and you clearly see the rotation that storm had.

        1. Oh yes. Typically, there is more helicity with the
          warm front, so IF there is enough instability to tap
          into that, well then you have the Revere situation
          from last year.

  19. 12Z GFS coming out. Shows ZERO instability during the morning and then
    starting around 1 or 2PM it shows RAPID destabilization. So at 18Z CAPE and LI
    is high Just to West of Boston.

    Waiting for the 21Z frame to see what it looks like.

    1. 12Z GFS
      21Z CAPE

      http://www.instantweathermaps.com/GFS-php/showmap-conussfc.php?run=2015063012&time=INSTANT&var=CAPE&hour=033

      21Z LI

      http://www.instantweathermaps.com/GFS-php/showmap-conussfc.php?run=2015063012&time=INSTANT&var=LFTX&hour=033

      LI actually more impressive to the West at 18Z

      18Z Cape

      http://www.instantweathermaps.com/GFS-php/showmap-conussfc.php?run=2015063012&time=INSTANT&var=CAPE&hour=030

      18Z LI

      http://www.instantweathermaps.com/GFS-php/showmap-conussfc.php?run=2015063012&time=INSTANT&var=LFTX&hour=030

      1. But it does show ample Cape and LI for Boston
        at the 21Z hour, so it will have to be watched for sure.

  20. The 12z GFS EHI values from the metoecentre don’t come out to around 2pm. Curious to see how it compares to 12z NAM.
    For the SPC update for tomorrow around 1:30pm I would expect more of SNE to be in that marginal risk zone.

  21. 12Z ARW WRF Vorticity Generation Potential

    for 18Z tomorrow

    http://www2.mmm.ucar.edu/prod/rt/wrf/wrf20/2015063012/vgp.hr30.png

    for 21Z tomorrow

    http://wrf-model.org/plots/showforecast_15.php

    0Z

    http://www2.mmm.ucar.edu/prod/rt/wrf/wrf20/2015063012/vgp.hr36.png

    I see a bunch of .3 there.

    Here is the meaning. Sorry it’s a bit technical

    VGP – Vorticity Generation Potential. Another experimental field used to predict supercell tornadoes. Based on the work of Rasmussen and Wilhelmson (1982) it relates CAPE and shear. It is defined as the sqrt(CAPE) times the 0-3 km mean shear. The units are m/s2 (an acceleration) or m/s times 1/s which is the product of w times vorticity – a tilting term. It is possible to have high values of VGP when helicity (and the EHI) is low. The VGP climatology shows that supercell tornadoes rarely happen with VGP less than 0.3, and go from unlikely to likely as VGP goes from 0.5 to 0.6, and are likely above 0.6. It’s also possible that the larger the VGP the stronger the tornado. The VGP was developed by Erik Rasmussen for use over the central plains and may or may not be valid over other regions. Problems – Unknown. But, since it depends on the assumed CAPE and depth of the inflow wind layer, it might inherit their problems.

    I can’t find it now, but I read a simpler explanation last week somwhere that
    basically said that tornados were possible with the value above .2.

    So, it’s getting interesting for sure.

  22. Old Salty I remember you posting that about a value of .2 that a tornado was possible. For comparison last week there were values of .4 .5 That is a great link you posted there and is a good piece of data to look at.

    1. I love it. Not even sure how I stumbled across it.
      But it’s nice to have to go with our SREF data and the EHI data we get.
      For amateurs we have access to some pretty good stuff and keeps us informed.

  23. SPC now has all of SNE with the excepiton Cape Cod and The Islands. in marginal risk for tomorrow.
    THIS OUTLOOK ISSUANCE MAINTAINS A MARGINAL SEVERE WEATHER RISK
    ACROSS PARTS OF THE NORTHEAST STATES…THOUGH PORTIONS OF SOUTHERN
    NEW ENGLAND COULD HAVE HIGHER SEVERE PROBABILITIES INTRODUCED IN
    SUBSEQUENT OUTLOOKS IF CONFIDENCE IN DESTABILIZATION INCREASES FOR
    THAT REGION.

  24. From SPC for tomorrow.
    ROBUST CONVECTION COULD SPREAD INTO THE
    REST OF WRN NEW ENGLAND BY EARLY AFTERNOON…WITH LOCALLY DAMAGING
    WINDS BEING THE PRIMARY SEVERE WEATHER THREAT. HOWEVER…A TORNADO
    OR TWO CANNOT BE RULED OUT…AS CURVED LOW-LEVEL HODOGRAPHS COULD
    SUPPORT THIS SEVERE HAZARD TOO.

  26. I am thinking right now as it stands probablities would be 5% wind 2% tornado. Obviously if a slight risk is placed then the wind would probably go to 15%.

    1. Nope. Not at all.

      Again, it hasn’t all come together and it might not.
      We need to continue to monitor is all.

    2. You could be correct, however, it would not surprise me if an area
      is depicted as 5% for tornadoes. It will be interesting to see tomorrow Morning.

      1. If there is NO 5% area, then there will NOT be a tornado watch, unless conditions change drastically since outlook issuance. If there is a 5% area, then I suspect there would be a good chance of a tornado watch. If so, 2 in one week is pretty impressive for
        around these parts. We shall see.

  28. Curious to see with the latest SREF says when it comes out.
    I don’t think an enhanced risk will be issued tomorrow but I could see some parts of SNE in a slight risk. Will see how much we destablize tomorrow.

    2. Should be out sometime around 3PM or shortly thereafter. I can’t stand waiting for that thing to come out.

  29. I have noticed over the years that thunderstorms during the morning hours can sometimes be even stronger than those more typical in the late afternoon hours. The storms that occured with the Revere tornado last year is a good example.

    It is good to see no HHH anytime soon through mid-July. Thanks TK! 😀

    1. Indeed. We need to watch the activity with the warm front as well.

      There always seems to be more shear in the vicinity of the warm front.

      We’ll be all over the radar tomorrow. Sure hope we don’t get one of those
      crazy announcements: Radar Down for Maintenance

  30. If there are strong enough dynamics in play you could get strong to severe storms and you don’t have to them during the peak heating time of the day. In July 2013 here in CT I mentioned this earlier today we had no sunshine but a high shear low CAPE environment and a weak tornado touch down in Fairfield County just before 11:30 AM and then just after 1:30 another weak tornado touch down just after 1:30pm.

  31. I just thought of something…Today is officially the LAST DAY OF THE 2014-15 SNOW SEASON! = 110.6″ 😀

      1. Yes, even 0.1″ of HAIL would have to be included in the final total snowfall OS! LOL 😀

      1. I really doubt next winter OS. I suspect the opposite if anything. I can’t imagine back-to-back snowy winters.

        1. I understood that. I was just throwing it out there.
          Even so, can you say that with 100% assurance?
          Probably not. I agree not likely, but who knows.
          And I do agree, it could happen again a few years down the road. 😀

    2. With the climate evolving and changing so much these days, who knows Jimmy? We may see that much snow again a few years or a few decades from now. 😉

  34. We have had in this decade 4 out of 5 winters with above normal snowfall. To me were due for a dud winter next winter. I hope I am wrong as I love the snow. I would say right now snowfall next winter in the 20-30 inch range next winter and that isn’t based on anything other than my gut.

  35. An interesting thought: Can a snowman be built out of HAIL? I imagine that it would take a few inches at least, but theoretically, can it be done?? 🙂

    1. I presume so, but I think it would depend somewhat on the shape and size of the hail. It needs to congeal and stick together somehow. If it’s totally round and rather larger it would have a tough time doing so.

      1. I am surprised that there haven’t been at least some attempts at building one. I guess even hard core snow lovers don’t want to even remotely think about snow in the middle of summer to try. 😉

  36. OK, 15Z SREF is out. I could be reading this incorrectly, but it looks to me as if
    the main threat comes with the Warm Front at about 15Z.

    Here are the significant tornado ingredients.

    15Z

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_prob_combined_sigtor__f024.gif

    18Z

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_prob_combined_sigtor__f027.gif

    Helicity

    15Z

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_1KMHEL_SSB_MEDIAN_MXMN__f024.gif

    18Z

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_1KMHEL_SSB_MEDIAN_MXMN__f027.gif

    1. Btw, IF this holds, there would be at most a 2% chance of tornadoes from SPC
      and NO watch, but we shall monitor for any changes. This is a really slight
      risk.

  37. One of this situations its a low to very low threat but its certainly not zero.
    There will be more model runs later and see if anything changes.

    1. For certain. Still need to keep an eye on it.
      BUT, I keep remembering back to the Revere Tornado last year.
      That was a low risk as well and look what happened. EF2 of all things near
      the City. Well, actually, Revere is a City unto itself. And so NEAR the coast.

  38. Just out from the NWS office at Taunton:

    LATER INTO THE MORNING WEDNESDAY…THE THREAT TURNS MORE TO SEVEREWEATHER AND POTENTIAL HEAVY RAIN. AS THIS SHORTWAVE APPROACHES…THE UPPER LEVEL COLD POOL WILL INCITE STEEPER MID LEVEL LAPSE RATES.THIS INCREASES THE INSTABILITY TOWARDS THE SURFACE TO GO ALONG WITHTHE ELEVATED INSTABILITY. THIS IS
    EVIDENT IN SBCAPES FORECAST OVER1000 J/KG. A DECENT LOW LEVEL
    JET HAS PROVIDED PLENTY OF SHEAR…0-6 KM VALUES ARE 30-50KTS AND
    0-1 KM HELICITY VALUES ARE OVER 100 M2/S2.

    THE MAIN QUESTION SURROUNDING THIS FORECAST IS WHETHER THE
    INSTABILITY INCREASES BEFORE THE SHEAR DIMINISHES IN THE AFTERNOON. IF EVERYTHING LINES UP…STRONG TO SEVERE THUNDERSTORMS WITH DAMAGING WINDS AND LARGE HAIL ARE LIKELY. DEPENDING ON THE TIMINGOF THE WARM FRONT MOVING NORTHWARD THROUGH THE REGION /EXPECTED TO BE EARLY WEDNESDAY AFTERNOON AT THIS TIME/ AND THE HELICITY VALUES…THERE IS ALSO POTENTIAL FOR AN ISOLATED TORNADO OR TWO.

  40. When you get those helecity values over 100 then you start to look for any signs of possible rotation in storms that form.
    SPC in their discussion earlier this afternoon mentioned the possiblity of a tornado or two like NWS out of Taunton did.

  41. Not sure IF this link will work, but it links to some HRRR model forecasts.
    The HRRR site itself is often not updated.

    http://mag.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model%20Guidance&model=hrrr&area=east-us&cycle=20150630%2019%20UTC&param=500_temp_ht&fourpan=no&imageSize=M&ps=area

    This does not go out far enough yet, but interesting to note that
    tomorrow AM, the surface winds will be South East, 925MB winds will be South
    and 850MB winds will be SouthWest. So that’s surface, 2600 feet and 5000 feet or so.

    Have a look

    10M winds

    http://mag.ncep.noaa.gov/data/hrrr/19/hrrr_east-us_01300_10m_wnd.gif

    925Mb winds

    http://mag.ncep.noaa.gov/data/hrrr/19/hrrr_east-us_01300_925_temp_wnd.gif

    850MB winds

    http://mag.ncep.noaa.gov/data/hrrr/19/hrrr_east-us_01300_850_temp_ht.gif

    IF we get enough convection, that could give us a REVERE situation like last year.

      1. Vicki, “could” translate to here for tomorrow.
        We’ll know tomorrow AM if the SPC does so.
        Stay tuned. Could be a very interesting day tomorrow.

        1. Thanks OS. I was supposed to have some testing done tomorrow but in pm so was ok with going. They reschedued for thurs so I’m happy to be here. They were pleased I didn’t mind. I didn’t tell them why. People tend to think I’m nuts when I say I enjoy storms

  46. Tomorrow the SPC has us in marginal risk area.
    The risk area today is to our west. In fact around Allentown, PA area there may have been a tornado touchdown there today.

  47. Based on the futurecast radars from the TV mets, it definitely appears that the city of Boston is very much in the crosshairs of any severe storms while the usual areas N&W pretty much spared. This is totally opposite of the more typical late afternoon-type storms in which western sections get hit and eastern sections spared.

    Thinking back to the Revere tornado that struck last year mid-morning, I am now wondering if “time of day” switches things around, so to speak??

    1. I don’t put much stock in those silly “future” casts. They are NEVER correct.

      However, you may be correct that the City is under the gun, but that is based
      on instability parameters I am looking at, not a “future cast”.

      For example

      http://img.meteocentre.com/models/gemreg_amer_qc_18/BE_BE_PN_027_0000.gif

      http://img.meteocentre.com/models/gemreg_amer_qc_18/BE_BE_PN_027_0000.gif

      http://img.meteocentre.com/models/cmc_hrdps_amer_qc_12/HI_030_0000.gif

    1. 18z cmc products pretty robust
      As well. I posted a couple
      Of links above.

      21z sref output due around
      9pm or a bit after.

      Im mobile and will be
      On the road then and wont
      See it till later.

      I keep seeing visions
      Of a twisting turn clouof terror.
      Bad isnt it???

  50. There are ingredients there for POSSIBLE rotating storms. Let’s hope its a bust and its just embedded thunder with the showers coming through.

    1. Im concerned somewhat but not alarmed.
      I just keep thinking Revere.
      I saw that cell cross the city before
      Dropping that tornado.
      Fwiw I wouldnt exactly call
      That cell severe.

  51. There was no tornado warning on that storm till after it passed Revere producing that EF 2 tornado. Clearly here on this blog we saw signs of rotation but the NWS out of Taunton chose not to issue a warning.

  53. OS not seeing warning boxes in radar now. Is it because I have to upgrade. I only have free version.

  55. When is this melee expected to begin. TK said morning and I know mornjng begins in 1.75 hrs but suspect it means morning after average person wakes up?

    2. The futurecast radars I saw this evening seemed to make it appear that central and eastern Mass could have a line of showers/storms approaching anytime btwn 7 and 9 am.

  56. Good evening.

    Just got in and am reviewing 21Z SREF. OUCH.
    Main action (according to this run) is at 15Z or 11AM or so.

    Significant tornado ingredients

    http://www.spc.noaa.gov/exper/sref/gifs/2015063021/SREF_prob_combined_sigtor__f018.gif

    There’s a 15 in there somewhere.

    Significant tornado parameter

    http://www.spc.noaa.gov/exper/sref/gifs/2015063021/SREF_SIGTOR_MEDIAN_MXMN__f018.gif

    We got a 1 bullseye in Boston Area. That is BAD!!

    I stand up an TAKE notice when this parameter
    is 1 or more.

    Helicity

    http://www.spc.noaa.gov/exper/sref/gifs/2015063021/SREF_1KMHEL_SSB_MEDIAN_MXMN__f018.gif

    Shear

    http://www.spc.noaa.gov/exper/sref/gifs/2015063021/SREF_0-6KMSHR_SSB_MEDIAN_MXMN__f018.gif

    This spells trouble. I fear a Revere type situation. We shall see.

  57. 2 or 3 waves of storms tomorrow morning… Window is 7AM-1PM west to east. Boston area could see stuff as early as 8AM depending on location and timing of wave #1.

    PM stuff still looks more isolated to scattered to me with best support to the N.

    1. Any concern at all for tornadic activity?

      Eric said on air that he expects to see a tornado warning or 2 tomorrow.
      Pretty bold statement, so there must be something behind it. Thoughts?

  58. SERF Tornado parameters ever so slightly backed off

    Ingredients

    15Z

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_prob_combined_sigtor__f012.gif

    18Z

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_prob_combined_sigtor__f015.gif

    Parameter

    15Z

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_SIGTOR_MEDIAN_MXMN__f012.gif

    18Z

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_SIGTOR_MEDIAN_MXMN__f015.gif

    That 1 bulls eye is now gone, lessening the risk some.

  60. Good news from NWS this morning.

    WE DO NOT SEEM TO MAXIMIZE THE SHEAR AND
    INSTABILITY AT THE SAME TIME. THUS…NOT EXPECTING WIDESPREAD
    SEVERE WEATHER AT THIS TIME. THINKING IS FOR A FEW STRONG TO
    SEVERE THUNDERSTORMS…WITH THE MAIN THREAT BEING DAMAGING WINDS AND/OR HAIL.

  63. Look at this HRRR Helicity for 9AM

    http://mag.ncep.noaa.gov/data/hrrr/09/hrrr_east-us_00400_helicity_1km.gif

    best Cape doesn’t get here till 11AM

    http://mag.ncep.noaa.gov/data/hrrr/09/hrrr_east-us_00600_best_cape_cin.gif

    8Am helicity

    http://mag.ncep.noaa.gov/data/hrrr/09/hrrr_east-us_00300_helicity_1km.gif

    8Am simulated radar

    http://mag.ncep.noaa.gov/data/hrrr/09/hrrr_east-us_00300_sim_radar_1km.gif

    If anything bad is to happen, it will be in the 8-9 AM time frame where
    we have the most helicity. Don’t however, have the most CAPE.

  64. HRRR has this first batch coming through Boston between 8 and 11 AM.
    Then shows more convection around 5PM or so.

  65. Was just out with the dog and had lightening and thunder overhead. Getting interesting on the radar.

  66. New blog posted!

    I’ll grab the posts since dawn and repost them there…

  67. Another look at that line of storms

    http://radar.weather.gov/Conus/northeast_loop.php

    SPC earlier had a mesoscale discussion about it with a 40% chance of watch issuance.
    They did NOT issue the watch and mesoscal discussion has been removed.

    Looks like we “may” have dodged a bullet and are staying sub-severe.
    Still need to watch some cells for a brief spin up, but I “think” we may be OK.

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