Potential Severe Weather - February 27th - 29th

[NWMSGuy]

Since the SPC has outlined a Day 6 & Day 7 outlook area, I think it's best we go ahead and start a thread for this potential multi day event. As of this morning, here is the latest from the SPC:

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CST Thu Feb 22 2024

Valid 251200Z - 011200Z

...DISCUSSION...
Medium-range models continue to show a powerful mid- to upper-level
trough ejecting into the central U.S. by late Tuesday into
Wednesday. A deep cyclone is currently progged by most ensemble
members to move from the central Great Plains into the Great Lakes
vicinity. Preceding this upper trough, an antecedent re-charging of
steep lapse rates associated with an elevated mixed layer over the
southern High Plains is forecast. A few days of airmass
modification, both in terms of ambient temperature and moistening
over the Gulf Basin, will occur in wake of frontal passage on
Saturday. Northward moisture return beneath the aforementioned EML
will probably result in a substantial warm sector by late afternoon
Tuesday and into Wednesday farther east. Model run-to-run
continuity is such that there is increased confidence in the
introduction of 15-percent severe-risk highlights with the expected
eastward progression of the trough. Will defer the possibility of
an additional area farther east on Thursday until confidence in
details related to earlier days becomes more focused.

 

[NWMSGuy]

Latest SPC Outlook for next weeks severe potential. SPC is mentioning there is uncertainty regarding Wednesday's Outlook area:




Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0224 AM CST Fri Feb 23 2024

Valid 261200Z - 021200Z

...DISCUSSION...
Strong southern stream westerly upper-level flow will extend from
northwest Mexico through the southern half of the U.S. on Day 4/Mon.
In northern stream flow, a strong upper trough will develop
east/southeast from the Pacific Northwest toward the
northern/central High Plains. Deepening surface low pressure over
the northern Plains, with a surface trough extending southward
through the southern Plains, will result in increasing southerly
low-level flow across the Gulf of Mexico northward to the Mid-MS
Valley. This will allow for substantial airmass modification ahead
of the western upper trough and southeastward-advancing surface cold
front through Day 6/Wed.

By Day 5/Tue afternoon, improved boundary-layer moisture (50s to low
60s F dewpoints) is forecast to arrive across the Ozark Plateau and
the Mid-MS and Lower OH Valley vicinity. At the same time, an EML
with a plume of steep midlevel lapse rates shifting east from the
Plains will overspread the central U.S. vicinity. This should allow
for at least modest destabilization, though quality of surface-based
instability remains in question given marginal low-level moisture.
Nevertheless, favorable vertical shear and strong forcing associated
with a surging cold front will support organized thunderstorms with
an attendant severe risk across a broad region of the central U.S.

Uncertainty has increased heading into Day 6/Wed as this system
shifts east across OH/TN Valley toward the Appalachians. The last
couple of cycles from the ECMWF have the surface cold front surging
east much faster than the GFS. While the operational GFS remains
much slower, the GEFS ensemble guidance overall has trended faster.
Given the combination of uncertainty and overall trends, severe
probabilities will be maintained for Day 6/Wed, but trimmed. It is
likely this delineated area will continue to change in the coming
days given higher uncertainty.

Beyond Day 6/Wed, spread in forecast guidance continues to increase
and predictability is low.

 

[NWMSGuy]

@tennessee storm Sounds like the incoming system may be slowing some? What’s your take for us here locally?

 

[tennessee storm]

@tennessee storm Sounds like the incoming system may be slowing some? What’s your take for us here locally?

Yeah good point , timing will be adjusted for sure , could be after midnight now in Memphis north Ms area …. Really think we have watch more of a damaging wind threat for us. Best dynamics go more
North

 

[NWMSGuy]

SPC has now dropped the Wednesday outlook altogether.

 

[gawxnative]

SPC has now dropped the Wednesday outlook altogether.

Think it may show back in Day 3 as Marginal with a limited in area Slight in tomorrows outlook package... Just models are spreading so much in last runs

 

[thanksgivingbrown]

Is anyone awake? Tornado on the ground near the western burbs of Chicago

 

[SD]

Is anyone awake? Tornado on the ground near the western burbs of Chicago

Really wonky cell motions up there with these hope no one was trying to chase

 

[Brick Tamland]

Local mets saying it's going to be windy here tomorrow.

 

[Chazwin]

Local mets saying it's going to be windy here tomorrow.

I’m already getting gusts 30-35mph this evening. Actually feels nice with the windows open

 

[Brent]

I’m already getting gusts 30-35mph this evening. Actually feels nice with the windows open

Yeah it really made our record heat not seem so bad here

 

[SD]

Most models have a decent amount of wind associated with the one of convection this afternoon

 

[Brick Tamland]

Heavy rain and wind here at the moment.