Severe WX January 10-12, 2020 Severe Weather Forecast Thread

[Kory]

Honestly I think that will be the issue for this system. The wind profile s may be there but instability will be lacking further north. I don't see anything major north of the middle of AR, MS, and AL

Ummm euro disagrees.

 

[Xenesthis]

Ummm euro disagrees.

I thought the Euro has the surface low moving across AL\TN border? Both models agree on low placement. That wouldn't allow much instability north of the Birmingham area basically

 

[Richardjacks]

Ummm euro disagrees.

One thing that stands out to me, if the models are correct is how easily accessible the high quality low level dewpoints are from the southern gulf....take a look a this from the GFS, not typical for a mid January system to be able to pull 70+ dewpoints that widespread, that far north.

 

[tennessee storm chaser]

I thought the Euro has the surface low moving across AL\TN border? Both models agree on low placement. That wouldn't allow much instability north of the Birmingham area basically

Euro has storm track with slp moving through west Kentucky Ohio valley regions...

 

[Xenesthis]

One thing that stands out to me, if the models are correct is how easily accessible the high quality low level dewpoints are from the southern gulf....take a look a this from the GFS, not typical for a mid January system to be able to pull 70+ dewpoints that widespread, that far north.

Now if that verified I could see some issues

 

[Xenesthis]

Euro has storm track with slp moving through west Kentucky Ohio valley regions...

Ok then what am I looking at? I just pulled the Euro from pivotalweather. It has the low on the KY\TN border which would spare TN for the most part

 

[Richardjacks]

Ok then what am I looking at? I just pulled the Euro from pivotalweather. It has the low on the KY\TN border which would spare TN for the most part

I would say the threat higher is higher for east Tenn vs. west, unless it tracks further north

 

[Xenesthis]

I would say the threat higher is higher for east Tenn vs. west, unless it tracks further north

Ok we agree with the current information. Thanks!

 

[TornadoFan]

 

[Richardjacks]

12z gfs looks nasty for north and central Alabama Saturday

 

[bwalk]

Another map visualizing this system: (per Reed Timmer)

 

[andyhb]

Overnight Friday into Saturday morning looks rather problematic for the Arklamiss into W AL with how it sits right now. Might be the best overlap of rich low level moisture and strong low level shear.

 

[Kory]

Overnight Friday into Saturday morning looks rather problematic for the Arklamiss into W AL with how it sits right now. Might be the best overlap of rich low level moisture and strong low level shear.

What do you make of the slowing trend across guidance as the trough goes negative tilt? That might bring it through here during better heating hours...surface-3KM lapse rates were not very great when it looked like a 06-12z timeframe.

 

[Richardjacks]

What do you make of the slowing trend across guidance as the trough goes negative tilt? That might bring it through here during better heating hours...surface-3KM lapse rates were not very great when it looked like a 06-12z timeframe.

This time of year daytime heating is less important, while it can add to the instability, the low sun angle and limited hours doesn't make as much difference compared to later in the season.

 

[andyhb]

What do you make of the slowing trend across guidance as the trough goes negative tilt? That might bring it through here during better heating hours...surface-3KM lapse rates were not very great when it looked like a 06-12z timeframe.

I mean naturally the low level lapse rates will drop with the lack of surface heating/insolation, but forcing for ascent will be increasing and strong low level WAA/moist advection should partially offset.

Saturday could also turn into a real problem should there be slightly less meridional flow aloft. Right now, it looks a bit more linear given the shear vectors off the boundary.

 

[Kory]

Something else that I am seeing on the models is some coastal convection due to the height falls down there. Could play a role in tempering the threat. More of those details will come with time.

 

[TornadoFan]

 

[Equus]

Two of the analogs earlier were Super Tuesday (the top analog in fact) and Nov 24 2004... neither of which were especially good weather days here. Big boy threat comin' down the tracks... time to take down the dead tree about to fall on the driveway, clearly.

 

[Timhsv]

Well, looks like game ON. A Day 5 30% seems to be an ominous signal.

 

[Kory]

Form the NWS SPC:

"Mixed convective modes
are anticipated given the strength of shear, with a QLCS likely
developing ahead of the surface cold front. This will support
damaging gusts and mesovortex tornado potential. Additionally, any
semi-discrete convection that develops ahead of the QLCS will be in
an environment capable of supporting supercells and tornadoes,
especially from east TX through central MS/AL."