Severe Weather Threat - January 8th-9th, 2024

[Clancy]

Watch the mesoscale models come in and say, "that's not issue" lol

Certainly possible. Still waiting to see what they say about moisture return overall.

 

[KevinH]

Watch the mesoscale models come in and say, "that's not issue" lol

Right… SMH

 

[CheeselandSkies]

12Z GFS seems to imply a little greater severe threat for parts of southeastern Georgia/northeastern to peninsular Florida, with a more expansive area of high EHI values at FH126 (18Z Tuesday 1/9) compared to earlier runs. Peninsular Florida's most significant tornado events often seem to come during El Nino winters.

 

[JPWX]

@Clancy does the GFS and Canadian also show coastal convection?

 

[KevinH]

12Z GFS seems to imply a little greater severe threat for parts of southeastern Georgia/northeastern to peninsular Florida, with a more expansive area of high EHI values at FH126 (18Z Tuesday 1/9) compared to earlier runs. Peninsular Florida's most significant tornado events often seem to come during El Nino winters.

Yeah this is starting to feel like more of a coastal event… FOR NOW lol

 

[Clancy]

@Clancy does the GFS and Canadian also show coastal convection?

Somewhat, though not as intense as the Euro it seems.

 

[Taylor Campbell]

The GFS has been slowing this system.

 

[Clancy]

The GFS (and EURO, for that matter) have been relatively static with regard to overall details, aside from some small temporal changes, for the last several runs. Will be intrigued in what changes (or perhaps more importantly - what doesn't change) between now and when this system comes into the range of the CAMs.

 

[JPWX]

Playing devils advocate here. 18z GFS. Okay we have the low pressure system over southern Arkansas lifting northward/intensifying. Warm front lifts northward too. If I'm reading right where the frontal positions would be, then why wouldn't you have a greater risk farther north. I do see the ongoing precipitation, but then again, what if it's overdoing the precip. Plus the 18z does bring in higher dewpoints farther north. Again, I do see the all the limiting factors (including cloud cover), but I also have to note the potential bias with the models here.

 

[Clancy]

Playing devils advocate here. 18z GFS. Okay we have the low pressure system over southern Arkansas lifting northward/intensifying. Warm front lifts northward too. If I'm reading right where the frontal positions would be, then why wouldn't you have a greater risk farther north. I do see the ongoing precipitation, but then again, what if it's overdoing the precip. Plus the 18z does bring in higher dewpoints farther north. Again, I do see the all the limiting factors (including cloud cover), but I also have to note the potential bias with the models here.

Can't remember if any of the globals have a cold-season bias on overdoing convection, but they seem to handle the more subtle destabilization that occurs with winter events pretty poorly in the Deep South, and sometimes exhibit a dry bias. Will likely have to wait for CAMs to come in range, and even then that may not clear things up all that much initially.

 

[Austin Dawg]

Playing devils advocate here. 18z GFS. Okay we have the low pressure system over southern Arkansas lifting northward/intensifying. Warm front lifts northward too. If I'm reading right where the frontal positions would be, then why wouldn't you have a greater risk farther north. I do see the ongoing precipitation, but then again, what if it's overdoing the precip. Plus the 18z does bring in higher dewpoints farther north. Again, I do see the all the limiting factors (including cloud cover), but I also have to note the potential bias with the models here

I know Ventusky is not usually in the discussion, but the European and GFS models are showing a more northern position for the warm front ticket to reach before the storm makes it into Alabama.

 

[CheeselandSkies]

SPC has introduced "strong tornado" verbiage in today's 4-8.

 

[Clancy]

SPC has introduced "strong tornado" verbiage in today's 4-8.

While there's plenty of uncertainty, they do sound significantly more bullish in today's outlook than previously.

...DISCUSSION...
Within the mid-latitude westerlies, significant mid-level troughing
digging into the Southwest by early Monday is forecast to continue
generally digging across and east of the southern Rockies Monday
through Monday night. As it does, models indicate that it will come
increasingly in phase with a perturbation within a branch of
westerlies emanating from the subtropical eastern Pacific, before
pivoting across the lower Mississippi Valley through the upper Ohio
Valley and Mid Atlantic Tuesday into early Wednesday. Associated
forcing for ascent is forecast to support the evolution of a broad
and deep cyclone, with an initial surface low consolidating within
deepening surface troughing across the Texas Panhandle by Monday
morning, before gradually migrating eastward near/north of the Red
River through the day Monday. The most rapid deepening, however,
may not commence until Monday night, centered across the Ozark
Plateau/Mid South, before proceeding northeastward through the lower
Ohio Valley and lower Great Lakes region into southwestern Quebec by
12Z Wednesday.

In the wake of a prior intrusion of cold/dry air, boundary-layer
recovery across the northwestern Gulf of Mexico may be slow to
contribute to destabilization inland of coastal areas.
Additionally, there has been a signal in model output that
considerable warm advection driven convection near or offshore of
north central Gulf coastal areas may further impede, or at least
slow, inland moisture return. However, in response to the more
rapid deepening of the surface cyclone, it appears that an
increasingly moist warm sector boundary-layer will spread inland
across the Gulf Coast, near/east of the Mississippi River by late
Monday night, before surging east-northeastward through portions of
the eastern Gulf and southern Atlantic coast states on Tuesday.
Coincident with intensifying deep-layer wind fields and shear,
including potentially large clockwise curved low-level hodographs,
the environment may become conducive to considerable organized
severe thunderstorm development, including supercells, with
potential to produce damaging wind gusts and a few strong tornadoes.

 

[UncleJuJu98]

Cant wait for the mesoscale models to come into view. Should be in about 24 hours it looks like.

 

[UncleJuJu98]

While there's plenty of uncertainty, they do sound significantly more bullish in today's outlook than previously.

That is a very aggressive wording by the NWS I wouldn't expect that at this point lol. That perks my ears some.

 

[Clancy]

That is a very aggressive wording by the NWS I wouldn't expect that at this point lol. That perks my ears some.

They're the pros, if they're being that aggressive I'll definitely take their word for it. Still think the globals are missing something.

 

[UncleJuJu98]

They're the pros, if they're being that aggressive I'll definitely take their word for it. Still think the globals are missing something.

Yeah the globals have left me dumbfounded, I haven't been posting because I don't know what to think. Obviously the pros know something. Maybe @MattPetrulli can give some insight he's very knowledgeable

 

[KevinH]

While there's plenty of uncertainty, they do sound significantly more bullish in today's outlook than previously.

Well okay THEN

 

[UncleJuJu98]

Dewpoints / LI index maps at 18z Monday on both the GFS and NAM for the same timeframe.

I do want to note the Nam has been notoriously cold bias here lately it seems.

 

[Wind Driven Coconut]

I’ve been less involved with severe weather monitoring the last few months but as a Floridian who is well aware of El Niño enhanced scenarios here, I’m keeping a wary eye on this one. I do wish the outlook had been a little more clear about the area and day (4 or 5) that they had the most concern about strong tornadoes…