andyhb

Incredible 00z HRRR run for tomorrow night. Really leaning towards this becoming a high impact event.

That FV3 (which is a bad model to begin with) is a tornado outbreak with a big cluster of supercells. The NAM 3 km is notorious for being too cold in WAA regimes, which will make it much less likely to generate open warm sector convection. With that said, the convective signature it is indicating there looks like the start of a significant event.

Have strong suspicion there will be a 15%/hatched tornado risk outlined at some point for tomorrow for parts of E MO, NE AR, central and S IL, and W KY (perhaps into W TN). Should the moisture be sufficient (and virtually every model is now showing this to be the case), very cold temperatures aloft, a very powerful shortwave trough blasting essentially right into the warm sector, and very strong wind fields favoring long-lived storms should yield at least a few significant/potentially long-tracked tornadoes in the region.

12z CAMs are either showing or close to showing a tornado outbreak from E MO into central and S IL Friday evening/overnight. Multiple discrete elements embedded within the greater line in some truly ungodly shear.

D3 moderate risk out from SPC. Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Thu Mar 13 2025 Valid 151200Z - 161200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF SOUTHEAST LOUISIANA INTO SOUTHERN AND CENTRAL MS/AL... ...SUMMARY... A severe weather outbreak is expected on Saturday from the central Gulf coast states/Deep South into the Ohio Valley. Significant tornadoes (focused across the South), swaths of damaging gusts, and hail are expected. ...Synopsis... An upper cyclone over the Upper Midwest will lift northeast into Ontario through Saturday evening. Meanwhile, a large-scale upper trough over the Plains will eject east toward the MS Valley. Strong southwesterly mid/upper flow (with a 500 mb jet streak near 100 kt) will overspread the Lower MS Valley/Mid-South vicinity by 00z, and continue east/northeast overnight into the Ohio Valley and central Appalachians. An intense south/southwesterly low level jet greater than 60 kt is forecast to overspread the central Gulf coast/Deep South into the TN/OH Valley during the late afternoon and nighttime hours. Rich Gulf moisture with dewpoints in the mid/upper 60s is expected to be focused over LA/MS/AL and the FL Panhandle, and possibly as far north as Middle TN and far western GA. 50s to low 60s F dewpoints will extend north into the Ohio Valley. This should support a widespread risk for severe storms across much of the central into the southeastern U.S. Saturday into early Sunday. ...Deep South/TN Valley vicinity... Forecast guidance has generally trended toward less widespread precipitation coverage Saturday morning as stronger height falls are not expected until late morning/early afternoon as the Plains trough ejects and a surface low begins to develop over the Mid-South. Persistent strong southerly low-level flow will allow for a moisture-rich boundary layer that should remain relatively pristine across southeast LA into southern/central MS/AL before convection develops by midday. Forecast soundings show cooling aloft will support steep midlevel lapse rates atop this moist boundary layer, leading to MLCAPE values perhaps approaching 2000 J/kg (decreasing with northward extent in Middle TN). Vertically veering wind profiles with strong anvil-level divergence amid moderate instability should support robust updrafts and intense supercells. Significant tornadoes, damaging gusts and large hail will be possible through the afternoon and spreading into AL during the evening/nighttime hours. Additional convection is expected to develop along an eastward-advancing cold front during the afternoon and into the overnight. An organized line of storms will pose a risk for damaging wind swaths and tornadoes across northern MS/AL into TN, eastward into GA and the western Carolinas overnight. ...Ohio Valley... Very strong deep-layer flow will be in place across the Ohio Valley on Saturday with some convection possibly ongoing from southeast Lower MI into western/central KY. The extent of severe potential is uncertain and dependent on how much precipitation occurs early in the forecast period. Too much convection early in the day could largely limit destabilization and temper the overall risk. However, if less convective contamination occurs, greater destabilization could occur ahead of a deepening surface low lifting northeast from the Mid-South to OH during the evening. Given the strength of deep-layer flow at least some risk of strong/damaging gusts within bands of thunderstorms should occur through Saturday night. ..Leitman.. 03/13/2025

Really nasty 00z GFS/Euro run for MO into W IL on Friday. Enough moisture and very favorable hodographs with the trough punching right into the warm sector. The proximity of the ULL to the warm sector also means it is very cold aloft, you probably would only need something like 70/58 to get almost 2000 CAPE out of this.

That's impossible to really say this far out, but yes I'd lean towards Middle TN being too far east on Friday and too far north on Saturday.

Saturday could be a bad day. The overlap of cold mid level temperatures, upper 60s dewpoints, and a 55-70+ kt LLJ cannot be underestimated.

Outbreaks on both Friday and Saturday on that 18z NAM run. The hodographs on Friday evening are just off the charts if enough moisture can get north. This is looking big.

00z GFS... holy friggin crap for next Friday.

I f*cking lol'd audibly.

Truly monumental, historic storm for the Gulf Coast here. You won't see this again in your lifetime in all likelihood.

Incredible, likely once-in-a-lifetime storm for the Gulf Coast here. New Orleans with 10", Lafayette with 10", places near Mobile AL and Pensacola with 8-10". Truly insane stuff.

I-10 corridor in Louisiana is poised for an event they haven't seen in at least 60 years (1963) if not since 1895.

Pretty remarkable event taking shape early this week as currently modeled for TX/LA. Very potent overrunning setup with a 1050 mb high dropping into the center of the country could yield borderline historic snowfall totals (at least in the modern record, nothing is coming close to that absurd 1895 storm) for the Gulf Coast/I-10 corridor. Remains to be seen which area gets hit hardest, but the 00z HRRR was giving southern LA upwards of 8 inches.

The death knell.

Can't think a 500 mb setup like this is anything less than "pretty darn good".

Ok, but seriously, what in the actual hell?

That thing deepens 15 mb in 6 hours, absolute nuclear grade blizzard lol.

Just chiming in to say, what in the f*ck...

Ice from freezing drizzle is causing a ton of problems in KS and W MO right now near I-70.

Blizzard warnings hoisted for the ICT/TOP CWAs in KS.

That storm in the latter part of next week has major potential if it can phase with the northern stream a bit as it ejects.

Huge potential with that system for the S Plains in the latter part of next week if it doesn't get trapped in the SW and at least partially phases with the northern stream.

Euro is a major ice storm from KS into the Ohio Valley. Moderate-strong winds, moderate precip rates, a deep warm layer aloft, and temperatures significantly colder than freezing at the surface are trouble. It looks to me like moisture for the cold conveyor belt gets robbed by convection in the Southeast, which would lead me to believe that the GFS is probably overdone on QPF further east.