2025 Severe Weather General Discussion

[high risk]

1 hour ago, Kmlwx said:

NAM and NAM nest seem better with parameters for Thursday now - but sim reflectivity doesn't really have any initiation at least on the panels I've seen (through 0z Fri). 

Right.   Parameters, especially the shear, are very favorable Thursday.  But will there be a trigger?   As you noted, the NAM says no, but the HiResW FV3 opens the door to at least a few cells in the Mid-Atlantic. 

[Eskimo Joe]

18 hours ago, Kmlwx said:

TBWI shows outflow moving out ahead of the storms. 

Classic issue when we have bad mid level lapse rates and dry air at the surface. Storms just can't get above 10,000 feet and the updrafts kick the storms apart.

[Kmlwx]

7 minutes ago, Eskimo Joe said:

Classic issue when we have bad mid level lapse rates and dry air at the surface. Storms just can't get above 10,000 feet and the updrafts kick the storms apart.

And my excuse of "it's still early in the season" gets less relevant each passing day. By April, we often have much better thermodynamic profiles - though May/June would be even better. Though that admittedly won't solve mid-level lapse rates!

I will say - yesterday ahead of the storms did feel juicier than the prior few events this year so far. So we are "getting there" in terms of better dew points and temps. 

One thing I do like is that we haven't had a shortage of "chances" this year so far. While there has sometimes been a week+ between risks, there's been a pretty steady stream of at least potential systems showing up. 

Thursday has my interest at least for now. 

[Kmlwx]

12z CSU MLP maps

[Kmlwx]

18z NAM and NAM nest continue with the theme of no initiation/storms for Thur. Parameters look a bit worse than prior runs as well. Still worth watching. 

[high risk]

Early take on Thursday:   some CAMs have storms in the area by late afternoon or early evening, and some don't.   If, however, storms do form, the environment actually features some decent low-level shear and a resultant conditional tornado threat.

[yoda]

SLGT risk up for Thursday 2/5/15

.OH Valley into the Mid Atlantic...
   Complications abound from overnight convection likely persisting
   into the daylight hours across the OH Valley. The front is forecast
   to continue to sag south and stall eventually across the OH Valley
   and Mid Atlantic by midday Thursday. South of the boundary low 60s F
   surface dewpoints and some filtered diurnal heating should support
   around 1000 J/kg of MLCAPE. Several embedded mid-level perturbations
   may provide enough ascent for additional convective development
   through the day.  Vertical shear will remain strong as increasingly
   zonal winds aloft overspread the frontal zone. Several clusters of
   strong to severe storms are possible along the front with a risk
   primarily for damaging winds and tornado or two, given the
   relatively poor mid-level lapse rates and veered low-level flow.

 

[WxUSAF]

Wide range of options on 12z mesos. I vote FV3.

[yoda]

2 hours ago, WxUSAF said:

Wide range of options on 12z mesos. I vote FV3.

12z HRRR wasn't too bad either... 12z WRF-ARW looked decent in MD 

[high risk]

2 hours ago, WxUSAF said:

Wide range of options on 12z mesos. I vote FV3.

Yeah, lots of uncertainty, but most of the CAMs (NAM Nest is notably bearish) have at least a couple of cells - a widespread severe event does not appear likely, but localized severe appears to be on the table.  I maintain that there is a slightly higher tornado risk; SPC notes the veered surface winds but that may be offset by a greater westerly component in the flow just above.  
 

More widespread storm coverage may be possible later Thursday night, but these would have very limited severe potential. 

[yoda]

Still 2/5/15 on 1730z SPC OTLK... but 15% hail was moved NE into W VA and WV

[yoda]

Day 2 1730z SPC OTLK disco for our region

 

   ...Kentucky to the Mid-Atlantic...
   Day 1 convection and cloud cover will significantly inhibit severe
   weather potential on Day 2 along the frontal zone from Kentucky to
   the Mid-Atlantic. Trimmed probabilities farther south near the Ohio
   River based on latest forecast front location. Otherwise, a moist
   airmass will remain in place along and south of the front/remnant
   outflow. Therefore, only minimal heating will be needed for some
   storms to develop which could be supercellular given 45 to 55 knots
   of effective shear along the frontal zone. Overall height rises
   should keep stronger storm coverage isolated to potentially
   scattered. Some damaging wind/large hail, and perhaps a tornado
   threat may exist within this corridor on Thursday, but the exact
   locations of this threat remains uncertain at this time.