November 19-21st severe threat

[JPWX]

I think we see another expansion north and east with the Slight and Enhanced Risk tomorrow.

 

[KevinH]

I think we see another expansion north and east with the Slight and Enhanced Risk tomorrow.

Don’t say that… I need the EHN to stay OUT of AL.

But why do you say that though?

 

[JPWX]

Don’t say that… I need the EHN to stay OUT of AL.

But why do you say that though?

Well just my gut feeling. The way this year has been, everything has seemed to overperform in what appears to be lackluster conditions. By lackluster, I mean CAPE/Instability.

 

[KevinH]

Well just my gut feeling. The way this year has been, everything has seemed to overperform in what appears to be lackluster conditions. By lackluster, I mean CAPE/Instability.

Ah ok

Be safe. Stay safe.

 

[UncleJuJu98]

00z hrrr came in even more stout than the previous long range hrrr runs.

 

[JPWX]

From my post on Patreon:

North MS:

Severe Risk Level: Level 1 out of 5 (Marginal)

Locations In Severe Risk (but not limited to): Fulton, Tupelo, Amory, Smithville, and Aberdeen

Primary Threats: damaging winds to 60mph, quarter size hail (1 inch), and a few isolated tornadoes.

Tornado Probability (within 25 miles of a point): 2% to 4%

Storm Timing: roughly 4pm tomorrow evening thru 1am Tuesday.

Severe Storm Timing: 6pm tomorrow evening thru midnight Tuesday.

Total Rainfall: 1-2 inches with locally 2+

Flash Flood Risk: Level 1 out of 4 (Marginal)

Central/Southern MS:

Severe Risk Level: Level 2 out of 5 (Slight)

Locations In Level 2 (Slight Risk) Area (but not limited to): Starkville, Meridian, Biloxi, Greenville.

Level 2 Slight Risk Threats: damaging winds to 60mph, quarter size hail (1 inch), and few tornadoes.

Tornado Probability (within 25 miles of a point) In Level 2 Slight Risk Area: 5% to 9%

Damaging Wind Probability (within 25 miles of a point) In Level 2 Slight Risk Area: 15% to 29%

Severe Risk Level: Level 3 out of 5 (Enhanced)

Locations In Level 3 (Enhanced Risk) Area (but not limited to): Hattiesburg, Jackson, McComb, Natchez, and Vicksburg.

Level 3 Enhanced Risk Threats: damaging winds to 70mph, golf ball size hail (1.75 inch), and tornadoes (some strong).

Tornado Probability (within 25 miles of a point) In Level 3 Enhanced Risk Area: 10% to 14% SIG Hatch Area for a Significant tornado (EF2-EF5)

Damaging Wind Probability (within 25 miles of a point) In Level 3 Enhanced Risk Area: 30% to 44%

 

[Clancy]

00Z HRRR doing HRRR things.

 

[JPWX]

00Z HRRR doing HRRR things.
View attachment 22103

Fascinating that the bulk of the tracks are further north than the Gulf Coast and honestly to some extent outside of the highest risk from SPC

 

[KevinH]

Fascinating that the bulk of the tracks are further north than the Gulf Coast and honestly to some extent outside of the highest risk from SPC

This is Tuesday evening. Some of those tracks are to the SW of me.

 

[Clancy]

Fascinating that the bulk of the tracks are further north than the Gulf Coast and honestly to some extent outside of the highest risk from SPC

May be a situation where there's an optimal overlap of wind dynamics and instability around the LA/AR border. NAM 3km far less aggressive but shows some relatively weak UH tracks at the MS/AR/LA triple-point.

 

[KevinH]

May be a situation where there's an optimal overlap of wind dynamics and instability around the LA/AR border. NAM 3km far less aggressive but shows some relatively weak UH tracks at the MS/AR/LA triple-point.
View attachment 22104

Key word: WEAK

 

[KevinH]

On going thread that just started that breaks down tonight 00z models

https://x.com/weathertrackus/status/1726437724201111593?s=46&t=NBCFVgjjJLxach1Cmkmpsw

 

[Timhsv]

The "trend" here is a little further north and east. Will be interesting when new Day1 comes out.

 

[Timhsv]

 

[JBishopwx]

.THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
FAR EAST TEXAS...CENTRAL LOUISIANA AND SOUTHWEST MISSISSIPPI...

...SUMMARY...
Severe thunderstorms are likely this afternoon into tonight from
east Texas, into parts of the Lower-Mississippi Valley, and
Southeast States. Damaging winds and several tornadoes, a few of
which may be strong, will be the primary hazards. Though damaging
winds and some large hail are also possible.

...Synopsis...
A broad positively tilted mid-level trough and jet streak over the
southern Rockies is forecast to consolidate and strengthen rapidly
into an upper low moving over the Southern Plains and the lower
Mississippi Valley by late tonight. Several more neutral to
negatively tilted shortwave perturbations embedded within the 80-90
kt jet streak will round the base of the trough and eject over the
ArkLaTex and Southeast ahead of the main trough this afternoon.
Broad diffluence and strong forcing for ascent will aid a surface
low over OK as it moves northeastward toward the Mississippi River
tonight. Strong low-level mass response ahead of the trough and the
surface low should draw a warm front with rich low-level moisture
(dewpoints in the 60s F) as far north as the MS/TN border. While
mid-level lapse rates are modest, strong differential thermal
advection and ascent should allow for the development of weak to
moderate buoyancy sufficient for scattered severe storms over parts
of the ArklaTex and Southeast states this afternoon into tonight.

...East TX into the lower Mississippi Valley...
A complex convective evolution is expected today with widespread
showers and thunderstorms likely to be ongoing north and east of the
surface warm front across eastern OK, AR and parts of northeast TX
at the start of the period. Isentropic ascent should remain strong
through the morning hours with weak showers and broken to overcast
skies likely throughout the warm sector. While this will likely
inhibit surface heating to some degree, a few cloud breaks and
low-level warm advection along a pre-frontal confluence axis in east
TX should allow for weak to moderate destabilization and scattered
storm development by mid morning to early afternoon.

Veered surface flow with relatively weak shear and high RH in the
low-levels suggests a messy storm evolution with early updrafts.
However, strong line-normal mid and upper-level shear components
should allow for the gradual intensification of individual supercell
structures within a broader cluster or broken line ahead of the
surface cold front across east-central TX. Albeit gradual, owing to
modest low and mid-level lapse rates, the maturation of these storms
through the mid to later afternoon will eventually overlap with a
strongly sheared-low-level air mass as the main upper jet ejects
over parts of far east TX, southern AR, and LA. 0-500m SRH of
100-150 m2/s2 and STP values of 2-3 will likely support strong
low-level mesocyclones with the potential for tornadoes, some of
which could be strong. These storms should continue eastward through
the evening hours with a risk for tornadoes before gradual upscale
growth into a loose QLCS increases the potential for damaging winds
over central and eastern MS into western AL.

Across parts of eastern AR into western/central TN and northern
MS/AL, low-level destabilization appears much less favorable with
multiple rounds of warm advection precipitation ahead of the surface
low and main trough. A few model solutions bring the warm front far
enough north to generate some positive near-surface buoyancy
immediately ahead of the cold front. A fine-line QLCS may evolve
with a low-end risk for damaging wind gusts given mixing of the
strong background wind field to the surface.

...Southern AL and Gulf Coast tonight...
As the warm front lifts north over parts of southeastern LA and
southern MS this afternoon and evening, rich Gulf moisture will move
quickly inland beneath a 30-40 kt low-level jet. While it is
uncertain if storms can develop given modest forcing, a few
supercells may evolve within the warm sector and track northeastward
toward the strongly sheared frontal zone. A few tornadoes could
develop in the evening hours ahead of the main band of convection
farther west.

Later tonight, the storms ahead of the cold front should gradually
coalesce into a QLCS as the front shifts eastward. With strong
low-level wind fields and at least some buoyancy remaining in place,
damaging gusts and isolated tornadoes are possible well into the
overnight hours across southeastern MS, southwest AL and possibly
the western FL Panhandle. However, confidence in the eastward extent
of the severe risk will depend greatly on the onshore
destabilization which, given the diurnal timing, is not a guarantee.

 

[UncleJuJu98]

Looks like we're still on track for a significant weather / tornado day.

06z toned down on updraft intensity a bit compared to last nights 00z run.

Watching for a small corridor of moderate risk area later, I doubt it happens but I think your close, to a small one.

 

[UncleJuJu98]

Northern half of Louisiana needs a moderate today. Last few hrrr runs have been kindve ridiculous for that area.

 

[Gail]

I hope people pay attention today. It’s been so quiet for months that it’s easy to take that pattern for granted and forget the weather.

 

[MattPetrulli]

Northern half of Louisiana needs a moderate today. Last few hrrr runs have been kindve ridiculous for that area.

Disagree, the HRRR runs have been a little sloppy and show a pretty messy convective evolution. I think a 10% # is perfectly fine.

 

[UncleJuJu98]

Disagree, the HRRR runs have been a little sloppy and show a pretty messy convective evolution. I think a 10% # is perfectly fine.
View attachment 22111

Looked pretty good to me lol, I said earlier though that I doubt spc goes with a moderate but In my opinion I could see that Northern half verifying and would probably go with one right before the event unfolds if things maintain some, even with a bit of a messier evolution. But I'm not a meteorologist just a amateur weather observer lol.