Friday, July 27, 2018

The Blackstone Valley Dodged A Bullet

- The Blackstone Valley dodged a bullet with the twin 7/26 tornadoes.  They were bad enough and its almost a miracle that there are no injuries.

Pine Grove Cematary Whitinsville, MA (image Steve Falconer)

  • Nocturnal Tornado
    • The 230 AM arrival time meant most people were sleeping.  Nocturnal tornadoes account for only 27% of all tornadoes, but they are responsible for 39% of all tornado deaths. 
  • No Tornado Warning
    • The National Weather Service issued a Severe Thunderstorm Warning at 232 AM.  It arrived at 232 according to the NWS Public Information Statement about the tornadoes.  A Tornado Warning would likely have triggered the emergency alert feature on many cell phones.  There was no real warning.  
    • I don't blame the NWS.  They issued the Severe Thunderstorm Warning when the velocity scan reached the threshold for severe wind.  It was a unique small supercell as the SPC Mesoscale Discussion called it, but not until 3 AM.  This was on no one's radar.
    • MEMA claiming that there was warning is technically true, but they are fortunate there were no causalities.  A severe thunderstorm warning issued as the storm hit containing the language "a tornado is possible" isn't adequate warning for a nocturnal tornado.
  • Lack of Lightning 
    • The largely uncomfortable tropical air mass ensured air conditioning units would be running on high.  With no thunder to roar over the a/c's, residents woke up to trees slamming against their homes or crashing in the woods.  I saw a lot of people on social media saying that they did not even know there was a storm.
    • Tornado Track Avoided Densely Populated Areas
      • There is significant damage to dozens of residences.  If the storm had tracked in a route where the 4.4 miles took it from the Village to Rockdale in Northbridge, several hundred to even over a thousand families could have suffered structural damage to their homes or apartments.  An even worse track would be the second tornado then tracking down in Grafton or Millbury.  

    • Tornadoes sine 1950
      • Douglas- 1 (7/26/18 EF-1)
      • Uxbridge 1(7/26/18 EF-0)
      • Northbridge 2 (6/9/53 EF-3, 7/26/18 EF-0)
      • Upton 1 (7/26/18 EF-1)
    • Tropical Air Mass Continues
      • Tropical air thanks to south/southwest winds will continue Friday and Saturday.  Severe weather looks to stay in Western MA and Northern CT on Friday with damaging winds and flash flooding as primary hazards.  Storms will weaken as they approach the Blackstone Valley.  That said, high resolution guidance is holding these storms together in Rhode Island and Southeast MA through midnight, especially towards the coast.
    11z HRRR Simulated Radar Through Saturday 1 AM (image WeatherModels.com)
    Additional storms may fire Friday as the triggering cold front will be slow to push offshore, largely thanks to stubborn Bermuda High.  Saturday afternoon humidity should decrease we the region gets a small break from the oppressive air.  

    Until next time.

    -Zack Green

    Thursday, July 26, 2018

    National Weather Service Confirms 2 Separate Tornadoes in the Blackstone Valley

    The National Weather Service in Norton has confirmed that two separate tornadoes touched down in the Blackstone Valley early this morning.  The twin twisters were each rated at EF-1 with winds of 100 MPH.  The first touched down in Douglas and tracked through Uxbridge and into Northbridge before lifting up around Lasell Field and Pine Grove Cemetery.  A second tornado touched down in West Upton around Main Street.

    Severe weather in Southern New England is just different than the rest of the country.  Rare is the big discrete supercell thunderstorm that is common in the Midwest and Southern US.  They do happen;  the 1953 outbreak that produced the infamous EF-4 Worcester tornado and the EF-3 Sutton-Northbridge-Mendon tornado (by my records the last tornado to track through Northbridge) were classic supercell thunderstorms.  This storm was anything but.  I didn't see a single flash of lightning.  But it is consistent with a few tornadoes that have hit Massachusetts in the past few years.  The Concord, MA twister of 2017 and the Revere tornado of 2014 immediately come to mind.
      But it really does sound like a train when a tornado moves through.  As I outlined in my last post, I was lucky enough to be thirsty for a drink of water around 2 AM last night.  I always envisioned my first tornado to be in the Midwest somewhere on a chase-vacation.  I missed one in 2013 in which friends and classmates of mine were able to see a tornado in Kansas (I think).  It was pitch black so I didn't see a classic tornado but I think I'm all set seeing one now that I can see what an EF-1 tornado can do.

    Here is the NWS write-up for tornado number 1.
    Here is tornado number 2.

    To all my new readers who joined today welcome.  I blog full time in the winter but only sporadically in spring, summer, and fall.  But when life-threatening weather hits I will also post.   Here are some pictures from Douglas, Uxbridge, and Northbridge (I covered Upton this morning before I realized what actually happened in my own backyard).



    Widespread Wind Damage in Upton After Wild Storm

    A small section of Upton, MA is recovering this morning after a severe thunderstorm brought severe damage to Main Street, Warren Street, and Ephraims Way around 240 AM.  National Weather Service survey teams will investigate to determine whether or not this damage has been caused by a tornado or a microburst.  Early indications are that this is a tornado, but the final assessment is to be done by the NWS.
    I woke up around 2 AM to get a drink of water and since I knew some intense weather was possible, I checked the radar.  What I found was a developing supercell thunderstorm with weak rotation heading directly towards Uxbridge, Northbridge, and Upton.

    Radarscope KBOX radar 220 AM
    The hook just south of Uxbridge in the top image and the hint of bright green next to the brighter red in the same spot in the bottom image instantly caught my attention.  This indicated rotation as the red and green colors measure the direction and velocity of upper level winds.  At this point the rotation is still weak.  However, any strengthening of the rotation could produce a weak tornado or a microburst.  Just 5 minutes later as the cell crossed into Uxbridge that is exactly what happened.
    I went out to my porch and around 235 AM there was a 30-45 second burst of intense rain and gusty winds, but no immediately obvious damage occurred in my section of Whitinsville .  Just after passing through my area the rotation tightened even more.  I was concerned about the Riverdale and Rockdale sections of Northbridge.  Meteorologists from Alabama and Oklahoma started to tweet me expressing concern over what they were seeing on the radar.

    This is all meteorological jargon so if you can't follow along that is OK, that is what we went to school for.   The point is, this was no ordinary severe thunderstorm for Massachusetts.  The National Weather Service did issue a Severe Thunderstorm Warning at 232 AM.  In the warning it says a tornado is possible, although no official tornado warning was issued.
    Shortly after the Storm Prediction Center in Norman, OK issued a "mesoscale discussion" noting the potential for isolated tornadoes. 

    SPC MCD
    Not long after I saw Upton PD tweet about numerous emergency calls around Glen Ave and Main Street.  I'm glad the damage is isolated, but it is significant for the folks who were hit.  There have been no reports of injuries thankfully.  I haven't been to bed (save for a 25 minute nap on the train) so I will be going to get a coffee.  I'll have more on this later after the NWS survey is complete.   

    -Zack Green





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