Dave Sills 🍁
@dave_sills
Followers
4,493
Following
761
Media
1,976
Statuses
9,276
🌪️ guru at @westernuNTP , Great Lakes sailor, my folk-rock album 'Fifty' charted in Kamloops(!?), YorkU & ECCC alumnus, on @secretsofradar board, #LeafsForever
London, Ontario, Canada
Joined April 2012
Don't wanna be here?
Send us removal request.
Explore trending content on Musk Viewer
SEVENTEEN
• 1535141 Tweets
Hanni
• 169941 Tweets
無料クーポン
• 161105 Tweets
Jets
• 121704 Tweets
連休明け
• 93538 Tweets
Carat
• 87635 Tweets
DG X ORM KORNNAPHAT
• 77901 Tweets
अब्दुल कलाम
• 60452 Tweets
पूर्व राष्ट्रपति
• 42349 Tweets
भारत रत्न
• 32619 Tweets
FELIP TAKES ON BBPHSTAGE
• 24619 Tweets
JC BBPH MAINSTAGE
• 23908 Tweets
The Next Prince Q9
• 23618 Tweets
ミンギュ
• 17872 Tweets
金木犀の香り
• 15582 Tweets
バーニス
• 14943 Tweets
मुस्लिम एरिया
• 13980 Tweets
うさぎだらけくじ
• 12881 Tweets
ITZY WORLD IS STILL DIFFERENT
• 11960 Tweets
ジョシュア
• 11896 Tweets
スングァン
• 11446 Tweets
エスクプス
• 11017 Tweets
ドギョム
• 10178 Tweets
Meteorology without borders: yesterday, folks at the Ontario Storm Prediction Centre sent pizza & wings to their counterparts at the Buffalo weather office - who are still working without being paid. Hats off to all our US colleagues affected by the shutdown - hope it ends soon!
9
101
449
Had to drive a good distance north of London to escape the hordes of aurora chasers (never though I'd say that ;-) ). But got to share these special Northern Lights with my better half, a pack of coyotes and a shooting star.
#LdnOnt
#AuroraBorealis
#Canada
9
31
339
Some pics from today's rather strange chase. Storms were weird, thunder was weird (and earth shaking), chasing with dead leaves flying all over was weird. But I'll take October thunderstorms over snowstorms any day ;-)
#ONStorm
7
20
245
Almost 20 years ago, Chuck Doswell (a veteran NSSL storm scientist and chaser) wrote the definitive guide to chasing storms safely and responsibly. He has continued to update it. All chasers young & old should (re)read it at the beginning of each season:
9
48
209
5
26
194
Some sizable hail with this supercell N of Lake Simcoe. Did not see a funnel cloud but lots of impressive storm motion
#onstorm
Going to look for bigger hail (that I escaped from!)
7
48
162
OK, I don’t think I’ve ever seen that much lightning with a hurricane before. I’m no hurricane expert, but this seems like a wild one.
#Helene
8
33
170
After her decades of service to Canadians,
@BellMediaPR
terminated national anchor Lisa LaFlamme's contract and made her say her own goodbye from her cottage.
This from the company that's supposed to champion mental health.
#BellLetsTalk
- Lisa deserved so much better.
#Legend
13
26
154
Back of camera - waterspout over Lake Huron, behind a freighter heading into port at Goderich. Lasted for about 10 min. Might have caught spray vortex once ship passed - will have to check when I get home. Developed around 10:42 AM EDT.
#onstorm
10
27
152
Have been waiting to try shooting lightning across the bay in
#Barrie
for over a year - got one! Not bad =)
#onstorm
http://t.co/ZggzHfcwwZ
24
79
139
Well that was a fun and unexpected local storm chase! From the area between London and St. Thomas.
#ONwx
4
16
147
Not a fan of chasers that get WAY to close too tornadic storms, putting themselves & others in danger - often just for the adrenaline rush & bragging rights. Having said that, Reed & his team getting 3D measurements from inside of a monster Kansas
#tornado
with a rocket - wow...
Check it out! Here is a 3D visualization of the 1 second GPS data points from the
#tornado
sensor launched into EF4 wedge south of Lawrence, KS last week, created by
@ChasinSpin
! The tornado/meso carried the sensor over 30 miles, losing signal at 34,000'! RED is prior to apogee
101
491
2K
5
14
141
I don’t think I’d ever tire of this view - the entrance to the harbour at St. John’s, NL with Signal Hill on the left. The food here has been amazing as well. Oh, and some science happening too ;-)
#CMOS2023
10
8
143
I didn’t try to get any special close-ups of the total eclipse, but this photo on the beach at Port Burwell, ON tells the story pretty well. Wonderful cheers as totality arrived. Had a bat fly over our heads just after I took this shot - that was pretty cool too! 😎
#Eclipse2024
8
8
135
This! Here's why the May 21st derecho is such a big deal - it affected around 40% of the population of Canada. Great comparison.
#ONStorm
#meteoQC
According to a Columbia University plotting tool, yesterday's derecho impacted approximately 15.6 million people- 41% of Canada's population.
For a progressive derecho to hit 41% of the US population, it would have to impact 135 million, which I've attempted here.
@JackSillin
13
102
213
4
51
124
Hard to believe but there is some supercell tornado potential tomorrow afternoon for those parts of NS / PEI / NB just pounded by Fiona. Wind / shear parameters are supportive but may be CAPE limited. Here are some current model outputs showing the potential. Will be monitoring.
29
44
116
Up in Orillia (no hotel rooms in Barrie after the tornado) & still processing all that happened today. Apparently we still have a long way to go when it comes to supercell tornado prediction. And building tornado-resistant homes (or even homes to code). Back at it tomorrow...
11
8
110
At the end of our dock in
#Wiarton
, there is a big bluff that is part of the
#NiagaraEscarpment
. And on clear mornings, the sun’s reflection off
#ColpoysBay
creates what I call ‘Shimmering Rock’. Always nice to wake up to :-)
#SailingLife
#GreatLakes
3
5
108
5
4
108
The same low-pressure system that brought devastating tornadoes to the US Ohio Valley overnight will bring damaging winds to southern Ontario as the low deepens today. Nearly 50 kt sustained over the Lakes with gusts to 90+ km/h over land (HRRR model shown). Be prepared
#ONStorm
3
43
105
The EC upgrade of the Alonsa, MB
#tornado
damage rating to low-end EF4 (estimated max winds 270-280 km/h) makes it the only EF4-rated tornado damage in North America so far in 2018 and the only tornado damage rated EF4 or higher in
#Canada
since the Elie, MB F5 tornado in 2007.
6
62
102
Just had a 'career highlight moment'. I gave a talk on NTP and how we analyze tornado/downburst damage. Brian Smith, who worked closely with Ted Fujita, was on the call and told me that Fujita would have been proud of the work we're doing. Can't get much higher praise than that!
10
4
104
Derechos are widespread, long-lived and fast-moving wind storms that can also generate tornadoes. While rare in Canada, there have been some notable examples such as the May 30-31 1998 derecho across the southern Great Lakes (see image). More details here:
6
38
103
At St. John’s, Newfoundland, for the 2023
@CMOS_SCMO
Congress. View out the hotel window is a banger - ocean view :-) Might be a view of fog the rest of the week so enjoying this now. And of course looking forward to the conference.
#Science
!
8
7
100
Amazing to see tornadoes across North America (for the first time for me)! Right now the only Canadian data are 1980-2009 and 2017-2021 but
@westernuNTP
will be making the new 1991-2020 national database public soon!
@torarchive
#MeteorologyWithoutBorders
Tornado Archive VERSION 2.0 IS NOW LIVE!! Stop in and see!
🌪️'s in 🇨🇦🇲🇽🇬🇧🇫🇷🇩🇪🇮🇹🇪🇸🇺🇦🇦🇺🇦🇹🇳🇿🇯🇵🇨🇱🇦🇷🇧🇷🇿🇦🇧🇩🇮🇳
+ERA5 Data and MORE
@NWSSPC
@essl_ecss
@BOM_au
#wxtwitter
@ReedTimmerAccu
@ryanhallyall
@Ginger_Zee
@spann
@MikeMorganKFOR
@sigtor2019
7
69
215
4
33
95
Question: Has anyone captured sprites over a thunderstorm in Canada? They're photographed regularly in the US now, and I've seen a number of good European examples. Where are the Canuck sprites??
10
26
97
THIS I have not seen before. Intriguing apparently helical structure to this lake-effect snow band over southern Lake Huron. Wow.
Also, embedded areas of low-level rotation that *may* indicate winter waterspouts. Difficult to verify but you never know...may get a report!
#onwx
6
17
95
This is going to happen more and more along the Great Lakes shorelines - buyer beware!
And I wouldn't be building a new dream home right on the shore, either - especially next to a cliff.
21
16
95
And thanks to my dash cam, I have proof (it was so tough keeping up with this thing that I never did get any camera shots of the tornado). This is taken heading S on Line 7 in Oro E of Barrie. There may have in fact been two tornadoes here - will be investigating this...
#onstorm
4
24
90
The new dual-pol Doppler S-band radar covering SW Ontario is now operational! Data from the radar, known as CASET (Exeter), should be flowing to radar clients like RadarScope (and NTP) soon. WesternU now has the old C-band radar - and plans for redeployment are in the works...
11
19
88
Let's have a moment for WKR, EC's King City weather research radar, the version that's been serving
#Toronto
, the
#GTA
& beyond since 2004. It got one last storm event in last night before being quietly turned off this morning. On to better technology!
#science
#onwx
#RadarLove
2
14
89
These NASA P3 research flights over the southern Ontario blizzard are for the Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) study - see
Great to see this historic storm being investigated!
#ONStorm
3
25
89
Arn Ashton, veteran severe wx forecaster at the Ontario SPC & one of THE best in Canada, worked his last shift today. After 33 years & ~1500 night shifts, he's taking on the even busier job of retirement (he's got a lot of plans!). Sincere congrats & much respect, my friend
#onwx
8
3
88
Shelf cloud from Wiarton last night. Today's severe weather threat is surprisingly uncertain at this point. Looks like best chance for a supercell tor in central / NE ON and W QC. Downbursts & possible QLCS tor in SW / E ON & Golden Horseshoe area. Eyes to the skies today!
#onwx
2
5
86
Back of camera funnel cloud just before 4 pm near Poplar Hill W of London, ON. Lasted a good 5 min.
#ONstorm
5
13
84
Tough conditions for catching waterspouts on Lake Erie this morning - foggy, too much storm outflow, low contrast/tough to focus. But did I manage to catch one S of Long Point that appeared under a rapidly growing cell at 8:48 am ET. Full condensation and spray vortex.
#ONstorm
7
13
83
1/
@westernuNTP
has completed a 'Fujita-style' analysis of the Brooks Lake, ON tornado of 8 Jun 2020 based on aircraft imagery. The damage path was 31.5 km long, 2440 m wide, with a max wind of 210 km/h (EF2). 33 microbursts were identified along either side of the path.
#ONstorm
7
27
84
More convinced now that the tornado (perhaps more than one) formed via supercell processes. But wow, nowhere near a classic supercell tor environment and Doppler velocity signatures rather subtle. Another data point on the spectrum...
Spectacular
#OttawaTornado
photo taken looking back from Hwy 174 W/B between Cumberland and Orleans as tornado moves across the Ottawa River forming a water spout between Ontario & Quebec.
#onstorm
#ottnews
Credit: Bryan Shepherd
@bshep17
20
331
640
3
17
77
EC Funnel Cloud Advisory for parts of SW Ont & here's an actual funnel cloud from Newbury just before 5 pm
#onstorm
6
53
76
That dashcam video from the 401 pile-up is so gutting I'm not going to share it - just hope everyone made it out alive. Please stay off any roads in open areas until the warnings have been lifted! This is an extremely dangerous storm.
#ONStorm
12
10
83
It's possible that Canada has never seen a fire season like this one, certainly not in the modern record. Much of that has to do with large-scale weather patterns & in particular blocking (long periods of heat/little rain).
#ClimateChange
amplification - you're choking on it.
5
31
79
New feature article in the Toronto Star today on the work of the Northern Tornadoes Project, with key input from
@gensiniwx
.
Still lots of work to do to build Canada’s tornado climatology and look for important trends, but NTP’s in it for the long haul.
3
20
80
Some partially melted beauties - biggest one is about 4.5 cm across - golfball!
#onstorm
Near Shanty Bay, ON
2
20
79
There have been 3 'billion dollar' severe thunderstorm events in Canada - all in the past 10 years:
* 8 Jul 2013 - Toronto flash flood
* 13 Jun 2020 - Calgary hail storm+flash flooding
* 21 May 2022 - ON/QC derecho+tornadoes
And they all have something in common... 1/4
4
30
81
Tornado travelling NE through Ottawa roughly along direction of arrow. Tornado warning issued. Take shelter if in the area immediately.
#ONstorm
3
27
77
Someone at our government weather service just made a huge mistake (likely during training or something similar). There is NO tornadic storm potential over SW Ontario, despite this warning that just went out. This is the second false alert in 2 days. NEEDS TO STOP IMMEDIATELY.
7
26
79
Power outages across nearly all of southern Ontario with this powerful fall storm. Hydro One's outage phone line is 'experiencing issues'. I bet! Big thanks to all of those working tonight to get power back for so many.
#onstorm
6
21
77
When I'm asked during interviews to describe the difference between a tornado & a downburst, I usually say the air with the first is 'in and up' while the second is 'down and out'. The amazing WindEEE dome at
@WesternUEng
, run by
@btisuamlak
, makes this distinction pretty clear.
4
31
76
Just had a compact, rapidly rotating wall cloud move over and to the east of King Radar. Not a supercell env at all so was a real surprise - likely boundary interaction / spin-up. Seemed to dissipate somewhat, but impressive!
#ONStorm
6
14
74
There may have been no fatalities from yesterday's major tornado outbreak in the US. This is a testament to the hard work of scientists, forecasters, emergency managers - truly a 'weather-ready nation'. Hopefully this holds today as well - thoughts to friends in OK. Stay safe!
5
11
77
Took Jack to the Leafs game tonight. Was supposed to wait until they’re in the Cup final (that’s what’s on the bucket list) but seeing them FINALLY in a Round 2 game is pretty rockin’ too - and about $9K cheaper ;-)
#GoLeafsGo
!!!
#LeafsForever
1
2
74
I was south of all of the action today (left after work). Got overrun by the shelf cloud way out ahead of the precip and never got out from under it again. So lots of dashcam photos like this one - stuck in the whale's mouth ;-) Still, not bad for September.
#onwx
3
4
74
Found a track of minor damage south of Hwy 11 - worst so far is this 20m comm tower bent in half toward the SE. Lots of excited locals milling around, thankful it wasn't worse.
#onstorm
4
30
74
Getting treated to some Northern Lights in Wiarton tonight. Considering this is a shot using an iPhone from a boat bouncing on the water, not bad!
#ONwx
2
6
72
FINALLY saw my first mature waterspout after years of trying. The action started just before I got to the shore at Port Burwell / Lake Erie - two funnels aloft. Then a longer funnel cloud developed. As it narrowed, a tall spray vortex appeared on the horizon. Waterspout!
#onstorm
7
2
72
Wow - the Northern Tornadoes Project is one of the 2019
@WesternU
Newsmakers of the Year! Have to share this with - couldn't have 'gone national' without their support.
#BigScience
#BigData
#CanadianTornadoes
3
19
72
Your cellphone will soon be alerting you if you are in the vicinity of severe weather or in other hazardous situations. No opting out - similar to the relatively new TV & radio alerts across Canada. A big step forward for getting timely info to the public.
9
25
72
One of the key factors affecting the dynamics of tornadogenesis over Lake Huron yesterday was the faster QLCS overtaking the short line(s) of storms moving more slowly ahead of it. Without that merger, the rotation does not develop. So perhaps a supercell-QLCS hybrid.
#ONStorm
4
16
71
Have to say - the 14 hr HRRR model forecast for last night's 'bow echo' storm was rather impressive. The timing was about 1 hr early, the location was about 30 km too far north, the convective mode was bang on. Success likely due to strong synoptic-scale forcing - but wow.
#onwx
5
11
73
MSC / Western crews starting to take old Exeter radar down today. Radome off first - looks much larger on the ground than it does way up on the tower!
@westernuEng
4
9
69
Just an amazing amount of lightning north of the snow/rain boundary (yellow line) as it moves NE. Quite the snowy light show in southern Ontario right now.
#Thundersnow
#ONStorm
6
11
71
Just found a detailed report of a tornado in what is now Nunavut, published in the journal Weather: afternoon of 10 Aug 1973, Upper Garry Lake (65.8N), 'violent funnel' extending from cloud base, spray ring to 100m. Canada's most northerly documented tornado, and only NU tornado.
4
17
69
I’ve been waiting to say this for almost 20 years - THE LEAFS ARE GOING TO THE SECOND ROUND!!! This team actually freaking did it
#CupOrBust
#LeafsForever
#GoLeafsGo
!!!
2
2
69
This is not a bullseye I wanted to see - looks like the SREF ensemble members are starting to converge on the probability of a significant tornado in the lower Great Lakes on Wednesday aft/eve. Still time for this to change - hopefully the next run backs off on the threat.
#onwx
5
22
71
What's a derecho and why is it so destructive? The science behind this powerful storm | CBC News
5
31
69
For decades I've been observing lake breeze convergence zone-initiated thunderstorms in SW Ontario and wondering how exactly they work. That is, most storms will dissipate when their updraft is cut off by outflow (see radar below). But not these - they keep going for hours. 1/4
1
5
70
We've seen a variety of powerful storms in southern Ontario this year and tonight's was no exception. Cells moved in from Michigan than wound up into a classic bow echo as it moved from Sarnia to Hamilton. Torrential rain, non-stop lightning, pockets of damaging wind.
#ONStorm
1
19
69
A little late but I put together a list of Canada's top 10 tornado *events* of the past decade. Quite lucky that there are only two fatalities on this list, though a lot of injuries and ~half a billion in insured losses. Just 1 EF4 and 4 F/EF3. Let the debate over ranking begin.
7
31
67
We lost a legendary figure in meteorology on February 11th - Isztar Zawadzki. Born in 1939, he became - through his work at UQAM and McGill U in Montreal - a leading researcher on weather radar, cloud physics and precipitation nowcasting, known around the world.
#EndOfAnEra
.
6
3
65
I believe we have the first Canadian hail (TBS) spike of 2024 with this storm near Blyth, ON at 7 pm EDT (white arrow / outline). Check out the max dBZ -> 76.5. Just may have been some large hail in there...
#ONStorm
4
15
69
Ontario's first-ever S-band radar has arrived! The fourth installed in Canada with many more time come as part of a big network upgrade. The radar features dual-polarization technology, doubled Doppler range and much faster scanning times. See the details in the link below.
#onwx
A new, state-of-the-art Canadian
#weather
radar has arrived! Smooth Rock Falls, near
#Timmins
, is home to Ontario’s upgraded
#CANWeatherRadar
!
Find out how it works, and how it can help you:
#BehindTheScenes
4
19
44
6
21
66
Looks like that Belmont tube developed at the intersection of a bow echo with an outflow boundary from the previous line of storms (blue line). Weak echo notch at back, northern bookend vortex, and little embedded couplet / notch near the leading edge. Pretty classic.
#onstorm
6
12
66
Most people would not be at all happy to see
@StormhunterTWN
out front of their house ;-) Thankfully just a quick visit to London, with a short tour of the NTP facilities
@westernu
.
0
7
65
Still some uncertainty but appears ingredients coming together for threat of severe storms in Goderich-Hamilton corridor late today. Damaging winds/hail are greatest threats though also slight risk of a low-end tornado or two. Here's one plausible model forecast (12Z HRRR)
#onwx
7
28
66
I'm doing a cross-country media tour today discussing tornadoes. I'll be talking with CBC Radio stations in Edmonton, Saskatchewan, St. John's, Calgary, Victoria, Ottawa, Sudbury / Thunder Bay, Vancouver, London / Windsor, Winnipeg, Kelowna, Quebec City, Whitehorse & Yellowknife!
10
12
68
Pretty impressive tornado-warned supercell in NW Ontario nearest to Eagle River but unlikely to be affecting many humans, if any (thankfully). But it’s likely generating a tornado, maybe a sig tor. Satellite imagery will likely reveal all in the coming days.
#ONstorm
3
11
67
Updated - At a preliminary EF3 rating, the Sept 21 Dunrobin-area tornado is only the 2nd E/F3 or higher recorded in Canada in Sept or later. The other was an F3 in Sept 1898 in the Niagara region - well south and west. The 2011 Goderich F3 was the last recorded Ontario E/F3
#onwx
1
45
62