Sydney Claridge

Looks like we got our first severe thunderstorm warning over Odessa, with a risk for 70 mph wind gusts.  Dew points are only in the 30s and 40s there, but there is still a little instability present.

Storm on MS/AL border might have “that look” to it.

While well outside of this subforum (this seems to be the main thread for the event), storms are going up over the eastern DFW metroplex, much further west than expected.  SPC says they are "high based" in a mesoscale discussion regarding the possibility of issuing a watch for the ArkLaTex.

I do wonder what this means in terms of implications for later in the event.

It looks like we have what appears to be an outflow-dominant squall line here.

I wonder if this gold-circle area should be watched for potential supercell development? It looks like there is a break in the line here, or that one segment (northern) has moved ahead of the southern segment.

Damaging 70-80 mph winds coming into the Mustang/Yukon area per News 9 live stream.  There is a kink in the line there too, although the News 9 live stream does say it is slightly behind the cool front.

Severe-warned storm coming out of the Breckenridge area needs to be watched for the DFW Metroplex within the next few hours.

8 minutes ago, BrandonC_TX said:

Looks like there might be some weak rotation on that cell over Altus.

Definitely looks like this is the dominant cell right now, with a severe thunderstorm warning.

Looks like there might be some weak rotation on that cell over Altus.

Might as well start a thread for this event.  We have a moderate risk, with a 15% hatched tornado probability across central Oklahoma.

Quote

SPC AC 100559

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Sun Oct 10 2021

   Valid 101200Z - 111200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM SOUTHWEST
   THROUGH CENTRAL AND EASTERN OKLAHOMA...

   ...SUMMARY...
   A potentially significant severe weather event is forecast across a
   portion of Oklahoma into north Texas late this afternoon into the
   overnight. Severe storms capable of large to very large hail, a few
   strong tornadoes and damaging wind are expected.

   ...Southern Plains area...

   A vigorous shortwave trough situated near the Four Corners region
   will advance east through the southern Plains this afternoon and
   evening before reaching the lower to mid-MS Valley late tonight. In
   advance of this feature, a cold front now over the central Plains
   will move slowly south. By late afternoon this front will extend
   from a weak surface low in the southeast TX Panhandle or northwest
   TX, northeast through north central OK, southeast KS and northwest
   MO. This boundary will move slowly south into the evening. A dryline
   will extend southward from the surface low through west TX, but will
   eventually be overtaken by a Pacific cold front accompanying the
   progressive shortwave trough.

   Richer low-level moisture return is already underway with mid 60s F
   dewpoints approaching central TX. As temperatures warm through the
   80s F along with modest mid-level lapse rates, up to 1500-2000 J/kg
   MLCAPE is likely by late afternoon. Initial storms should initiate
   over southwest OK or northwest TX along intersection of the dryline
   and the southwest-northeast oriented cold front. Given strength of
   effective bulk shear with 50+ kt associated with the approaching
   mid-upper jet, this activity should quickly become supercellular.
   Hodograph size should undergo a substantial increase as the
   low-level jet strengthens during the early evening with 0-1 km
   storm-relative helicity likely exceeding 250 m2/s2 by 00Z. Given the
   favorable kinematic and thermodynamic parameter space, potential
   exists for a couple of long track supercells to evolve and track
   east northeast through OK along and just south of the front. These
   storms will be capable of producing very large hail and strong
   tornadoes. Additional storms will likely develop farther northeast
   along this front as well farther south into TX as the Pacific front
   intercepts greater low-level moisture. These storms will also likely
   become supercells capable of all hazards. Eventually, storms may
   evolve into lines and clusters during the evening and into the
   overnight, but with a continued severe threat toward the lower and
   middle MS Valley regions.

   ...Upper Mississippi Valley and Great Lakes regions...

   A northern-stream shortwave trough will advance slowly northeast
   through northern MN during the day. Storms may increase over
   northeast MN just northeast of the vorticity maximum during the
   afternoon where wind profiles and modest instability will be
   sufficient for supercells. Primary threat with this activity will be
   hail and possibly a couple of brief tornadoes. Farther southeast
   across WI within the dry slot region, the extent of thunderstorm
   initiation during the day remains uncertain, but a conditionally
   favorable environment for supercells will exist. If confidence
   increases that robust updrafts can develop in this environment, then
   a categorical risk upgrade may be needed in later day 1 updates.

   ..Dial/Marsh.. 10/10/2021

1 minute ago, Indystorm said:

That is where the greatest helicity has been located.

And there is now a TOR warning on the MN/WI border SW of Grantsburg.

Part of me feels that SPC went with a Severe Thunderstorm Watch specifically so that they could label it as a Particularly Dangerous Situation for straight-line winds. Tornado probabilities are at the maximum (20%) for a SVR watch, while the SPC outlook has a 10% tornado probability (within 25 miles of a point); normally we would expect a Tornado Watch with a 10% on the outlook, barring some post-outlook "nowcasting" suggesting lower probabilities.

Typically I've noticed that 10% contours almost always lead to Tornado Watches, while 5% contours can go in either direction (that is, either a SVR or a TOR watch).

1 hour ago, StormfanaticInd said:

If a tornado forms in this environment watch out.

The parameters for significant tornadoes and the Violent Tornado Parameter are both very high over the Twin Cities metro area.  These parameters are not everything by themselves, but still, it is not an environment you would want a supercell to form and then go on to produce a significant tornado, especially over a highly populated metropolitan area like MSP.
 

7 minutes ago, Chinook said:

southwest of Lansing MI - confirmed tornado

 

I’m getting concerned about the path this storm is taking. It’s moving in the direction of the Lansing metro area (especially the SE part). If this storm can hold together, there would be concern for a tornado in a highly-populated area.

And just look at how wrapped up that hook echo is.

Looks great on radar, but I sure wouldn’t want to be in the path.

EDIT: it now has a PDS tornado warning on it. Large and extremely dangerous tornado in progress, fortunately this is happening in an area with very low population.

Looked like a pretty well-developed rotational signature in NW Sterling County, TX, SE of Forsan:

Looks like a hail core has formed with a left-mover SE of Springtown, TX and is moving in the direction of Azle. Tarrant County may need a severe thunderstorm warning soon if so.

The main supercell continues to move SSE towards Weatherford.

25 minutes ago, Powerball said:

Although the cell was tornado warned, it seems they're calling it high winds for now. 

It looks like some pretty serious damage occurred to a home in the Northhaven area. Some debris was even lodged into the ground, apparently: https://mobile.twitter.com/HowertonNews/status/1394032811875651595?ref_src=twsrc^google|twcamp^serp|twgr^tweet

We’ll have to wait for the official survey, but the evidence seems pretty convincing for a brief tornado touchdown. This very spot got hit with the tornado on 10/20/19, so if this were a tornado it would be the second time in less than two years that a tornado hit this spot.

Apparently there was "significant tree damage" at Goar Park in University Park according to NWS storm reports. Also a home got damaged on Northhaven Road across from North Haven Gardens, which was an area hit hard back on October 20, 2019.

That now-severe storm northeast of Denton seemed to blow up out of nowhere.  Though very minor right now, radar seems to suggest additional attempts at initiation SW of Decatur.

Storm northeast of Denton (around Pilot Point) might need a warning soon; it seems hail sizes are coming up.

Also there seems to be a notch on that storm over Mesquite. Fortunately it seems there is very little rotation however.

1 minute ago, TheSuckZone said:

Looks like a new tornado trying to form N of Forreston, TX

Yep, couplet on radar:

New TOR warning includes NE San Antonio metro area and New Braunfels.  Seems to be some strong winds in that storm with perhaps some rain-wrapped rotation (though it seems broad).

That said, the below screenshot doesn’t really seem to show rotation and seems to be a straight-line wind threat.

7 minutes ago, TexMexWx said:

Wonder if the updraft will be able to sustain itself, especially with some dry air still in the lower levels of the atmosphere per the recent FWD sounding

What I saw driving home from work had quite a high base; I wonder if this updraft is rooted above the cap?

17 hours ago, beavis1729 said:

An already impressive winter in interior Alaska is going out with a bang, with snow and cold.  2-day snowfall of 13.2" on April 3-4 in Fairbanks, which brought the snow depth to 40".  This is the highest snow depth since 1993.  Snow depth on 4/7/2021 was still 38", 2nd highest so late in the season (only 1991 was greater).  Could be a bad year for flooding and river ice break-up.

Fairbanks just set a new record for consecutive days under 40F:

(1) 179 days:  10/11/2020 to 4/7/2021 - still active

(2) 176 days:  10/3/1965 to 3/27/1966

(3) 171 days:  10/8/1994 to 3/27/1995 

With clear skies and fresh snow cover, Fairbanks dropped to -24 on 4/6/2021, which is the 3rd coldest temp on record so late in the season (-24 on 4/7/1986 and -32 on 4/10/1911).  It was even colder at some other sites:  -36 at Jim River DOT (Mile 138 Dalton Highway); -34 Norutak Lake RAWS; -33 Bettles.

There is an even colder airmass lurking for this upcoming weekend, where Fairbanks could hit -25 or -30.  Normal temps for this weekend are 40/16.  Per Rick Thoman:  "By several measures, the Utqiaġvik 00Z Thu RAOB records the coldest April low-level airmass on record (since 1948). Lowest 850mb temp -35.5C; lowest 1000-850mb thickness 1138 gpm; lowest 1000-500mb thickness 4803 gpm."

http://ak-wx.blogspot.com/2021/04/even-colder-on-way.html

http://ak-wx.blogspot.com/2021/04/extreme-cold-approaches.html

It’s crazy to see such cold temperatures there so late, although definitely not unprecedented as their April record low is -32F. Climatically speaking, Fairbanks has very little seasonal lag. This means that in Fairbanks, June is warmer than August, and December is colder than February.

It looks like temperatures return to normal next week, and that streak of below 40F temperatures will come to an end.