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US Wild Weather

Extreme active pattern across the entire US continues, what does it mean for your region? Join the conversion

ClicheVortex2014

February 6-8, 2019 | Storms

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We are not that far apart and I'm sitting on about 38" for the year. Snowfall disparity is big compared with the downtown Chicago loop also

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18z HRRR showing a typical evolution of a OV winter severe event, even including a potential SW OH screw zone. 

Initially looks like a broken line of supercells or a squall with embedded supercells. The southern half of the 'line' forms a squall, the northern half kind of breaks off and does its own thing. In this scenario, the tornado threat would be greatest in the northern half of the 'line'... especially if any supercell can be at least semi-discrete like this scenario. 

It is worth noting that SPC is really not that impressed with the setup tomorrow, so I don't think they thought much about this scenario. But I have definitely seen crazier things happen. 

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Look at that cold front.

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NAM does agree with HRRR though about directional shear being pretty strong tomorrow. I'd actually say the two are in pretty decent agreement. I actually wouldn't be surprised if the OV steals the event from the south.

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NAM sounding near Indianapolis. Definitely some very strong wind shear.

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Even though Twisterdata has fallen behind as a model site, their graphics are some of the best.

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5 hours ago, Cary67 said:

We are not that far apart and I'm sitting on about 38" for the year. Snowfall disparity is big compared with the downtown Chicago loop also

Yep. The majority of the low pressure centers have tracked almost directly overhead this winter, with most of our precip being rain. Hopefully next winter we see a track further southeast so I can get in on some of the snow too.

Edited by weather_boy2010

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1 hour ago, weather_boy2010 said:

Yep. The majority of the low pressure centers have tracked almost directly overhead this winter, with most of our precip being rain. Hopefully next winter we see a track further southeast so I can get in on some of the snow too.

I hear that. I swear there is a scientific reason that I'm not aware of that stops snow from hitting my area. We got one storm with 1 inch of snow and nothing more than a tiny amount of flurries or tiny accumulations on cars. Every time snow comes near Hendersonville it breaks apart or turns into rain.

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The tiny cells seen in Kentucky and Ohio in this HRRR run are capable of producing strong to severe winds. The soundings in these areas show enough instability to help bring the very strong winds aloft to the surface. The surface winds on this run are fairly parallel to the upper-level winds, so tornadoes aren't as much of a threat on this run. The best overlap of CAPE and wind shear is in Ohio and Pennsylvania. There may be more of a tornado threat in western Pennsylvania on this run due to more backed surface winds.

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8 hours ago, Cary67 said:

We are not that far apart and I'm sitting on about 38" for the year. Snowfall disparity is big compared with the downtown Chicago loop also

It seems you guys in the NW 'burbs always get more snow. I've had roughly 20" of snow this year. The November storm is most responsible for our starkly different amounts, though. 

 

 

Back to the topic, there was a severe thunderstorm warning in the ice storm warning counties. 

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9 minutes ago, chicagosnow said:

It seems you guys in the NW 'burbs always get more snow. I've had roughly 20" of snow this year. The November storm is most responsible for our starkly different amounts, though. 

 

 

Back to the topic, there was a severe thunderstorm warning in the ice storm warning counties. 

Yeah I saw a special weather statement earlier that warned of sleet and hail... at the same time. That’s sure to confuse people. 

Now, not only do we have a MCS in NE OK, it’s an MCS with temps in the mid-30’s at its warmest. The stratiform region of the MCS is likely freezing rain. The storms popping ahead of the Texas dryline is tonights main event (I think), and is ultimately going to be tomorrows low-topped squall in at least the Tennessee valley. 

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Been a few severe storm warnings tonight in MO. Might be a few elsewhere, but haven't checked radar much.

 

Screenshot_20190206-212442_RadarScope.thumb.jpg.062bcad2e502dd5b769c8093b379e39f.jpg

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2 tornado warnings south of Springfield, MO. Mesoanalysis shows these are barely surface based, if at all. 

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The western half of the slight risk has 5% tornado.

EvGk5Dw.gif

Quote

  Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1153 PM CST Wed Feb 06 2019

   Valid 071200Z - 081200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS MORNING
   INTO THE AFTERNOON HOURS FROM PORTIONS OF THE MIDDLE MISSISSIPPI
   VALLEY INTO THE LOWER OHIO VALLEY...

   ...SUMMARY...
   Severe thunderstorms are possible today across parts of the middle
   Mississippi and lower Ohio Valleys.  Some of these could be
   accompanied by a risk for tornadoes, in addition to potentially
   damaging wind gusts.

   ...Synopsis...
   As mid-level subtropical ridging remains strong across the Gulf
   Basin into much of the Southeast and adjacent Atlantic, it appears
   that a significant short wave trough (now turning northeast of the
   southern Rockies into the central Plains) will maintain a
   northeastward acceleration during this period.  As it does, models
   continue to indicate that it will be accompanied by strong lower/mid
   tropospheric cyclogenesis, particularly across the Great Lakes
   region into western Quebec this afternoon through 12Z Friday.

   An influx of low-level moisture off the western Gulf of Mexico has
   already contributed to sufficient destabilization to support a
   considerable increase in thunderstorm development across the central
   and southern Plains into the lower Missouri Valley and Ozark
   Plateau.  This activity appears likely to spread northeastward and
   eastward into/through the Ozark Plateau, middle Mississippi and Ohio
   Valleys and the lower Great Lakes region, before the inflow of
   moisture becomes cut off, and destabilization becomes insufficient
   to maintain thunderstorm activity.  Before this occurs, though, a
   risk for severe thunderstorms is expected to persist today, and
   could even increase from late morning through mid to late afternoon
   across parts of the middle Mississippi and lower Ohio Valleys.

   ...Middle Mississippi into Lower Ohio Valleys...
   Low clouds and rain within the warm sector, and an initially
   cold/stable low-level environment to the northeast/east of the
   northeastward migrating cyclone, will probably impede
   destabilization and limit the overall severe weather risk through
   this period.

   However, guidance remains suggestive of a continuing window of
   opportunity for strong/severe thunderstorm development into today,
   mainly within the deepening surface trough, east/southeast of the
   cyclone center, southward ahead of the eastward advancing surface
   front.  Despite generally weak lapse rates, it appears that near
   surface warming and moistening, coupled with weak mid-level cooling,
   may yield at least weak destabilization of the boundary layer.

   Aided by difluent and divergent flow ahead of the upper trough,
   low-level forcing along/ahead of the cold front may support an
   evolving line of low-topped thunderstorms, perhaps including a few
   supercells, by midday.  In the presence of 50-70+ kt
   south/southwesterly flow in the 850-500 mb layer, strong deep layer
   shear and large clockwise curved low-level hodographs may contribute
   to potential for convection capable of producing a couple of
   tornadoes.  

   Otherwise, strongest activity will probably be accompanied by a risk
   for potentially da

 

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Tornado threat seems to be decreasing 

 

Screenshot_20190207-094043_Chrome.jpg

 

Severe storms still a threat though

 

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Edited by Grace

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Solid squall formed in the lower OV. Threat for embedded tornadoes due to the LEWPy nature of it

(not sure if I have the power to do it now, but can we add LEWP to our glossary @PlanetMaster? It’s line echo wave pattern, a type of squall that produces a series of bow echos (high-end wind damage) and embedded tornadoes https://en.m.wikipedia.org/wiki/Line_echo_wave_pattern)

 

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1 hour ago, Grace said:

Tornado threat seems to be decreasing 

 

Screenshot_20190207-094043_Chrome.jpg

 

Severe storms still a threat though

 

Screenshot_20190207-094104_Chrome.jpg

STP is really dependent upon storm mode. In a case like this, we're not looking for EF2+ or long-lived tornadoes... any tornadoes that form today will be weak and short-lived because the dominant storm mode will be linear with exception to the low potential for transient supercells. STP is built to gauge the opposite of that. There's not really a good all-encompassing parameter for days like today, but the main thing you look for is surface-based instability (at least some SBCAPE), very strong low-level shear (40+ knots 0-1km, 300+ 0-1km SRH) and near-surface cloud base (LCL <200m). Today we have all 3 of those conditions met in wesetern KY, so I still wouldn't rule out a tornado for the next few hours or longer.

The warm front should move north and insolation through clouds should help gain some instability today. I think SPC did well with the placement of tornado probabilities. The western half of the OV could see some spotty damaging winds/tornadoes.

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There was a LEO confirmed tornado in SW IN. Extreme shear up there near the warm front... any surface-based convection has a brief tornado threat

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Got another tornado warning this time with a debris signature. Looks like it struck Oakland City, IN and may be about to hit Winslow, IN.

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I've decided since I can't even get into the warm sector fun on this one, I am just going to live vicariously through the plow cams from the blizzard in MN. Here is one from near my parents house not long ago:

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