Won't be surprised the current WPC Excessive Rainfall Outlook for Friday sees an extension of the slight risk. NWS Jackson has bumped up totals up to inches for much of North Mississippi.
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Severe Weather Threat January 8-10, 2026
- Thread starter CheeselandSkies
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WeathermanLeprechaun
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There's some instability left over. I'd be concerned over a inversion there, and that inversion could also be prominent on Friday in Mississippi too so even that's not all a slam dunk. A early morning tornado threat likely will exist Saturday maybe in SE MS, i have some confidence in that. But the Delta round is conditional in itself. spinup tornadoes would be possible with this band if not elevated. Line orientation would need to be favorable though and the HRRR is depicting NE-moving streaks. We will see. Could see something interesting to start tye year in Oklahoma...
Thanks for the info! I think I understand now. Is the initial line of storms is cooling the upper layers more than the surface, and that increased change with height is creating more instability? Is this a result of how fast the low pressure system is moving, and humid air being harder to cool than dry air? Any deeper analysis is much appreciated! Same to you @ColdFront
jiharris0220
Member
It’s colder (above the surface) towards the dryline because it’s simply closer to the cold core low, this combined with the higher surface temps along the dryline is the reason for the higher cape.
This is the typical synoptic set up for the majority of extratropical cyclones. The highest cape will be near the cold front/dry line naturally due to proximity from the CCL and the highest surface temps due to WAA being the most substantial along the front.
Although sometimes the highest cape will be along the warm front section since the greatest vertical temp gradient is located there.
During spring and summer months, the highest cape usually will be away from the front and further south in the OWS, simply because the shear amount of moisture and heat present compared to near the CCL.
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Here's a sounding from the HRRR in the area of interest.
And this is the closest analog I could find in my collection. It's from a very photogenic 2015 "cold core" tornado outbreak in Colorado
And this is the closest analog I could find in my collection. It's from a very photogenic 2015 "cold core" tornado outbreak in Colorado
NWS Memphis in their updated discussion mentions 60kt bulk shear, but CAPE probability of exceeding 500 is 10%.
Here's the thing: that shear can compensate for lack of CAPE. I've mentioned this many times on here as well as others. Basically your classic low CAPE/high shear setup.
Here's the thing: that shear can compensate for lack of CAPE. I've mentioned this many times on here as well as others. Basically your classic low CAPE/high shear setup.
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Certainly an impressive synoptic setup that is being modeled, but mesoscale features seem to be lacking to make this a widespread outbreak. I'd shift/shrink the SPC probability to have a bullseye on the ArkLaMiss area, but I don't see the northern part of the current highlighted area getting anything significant.
Cyclonic Paracosm
Member
lets hope this synoptic set up type thing doesn't stick as we don't need a repeat of of last year where most events have the setup but no actual thermos then one hits and boom outbreak
Kolle
Member
The history of severe events in the southern US during winter is so rife with low CAPE/high shear events, so I am still surprised some people still discount them.
That makes very good sense! Thank you. I haven't followed many winter set ups this closely, so it's interesting seeing CAPE manifested this way.
21Z RAP continues the uptrend across mesoscale models with an even crazier Thursday evening. My goodness. CAPE wasn't supposed to get this high until around sundown on Friday. I guess the main question is if convection is going to outrun the stronger synoptics?
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WeathermanLeprechaun
Member
Seems like Thursday might go thru and RAP even got 1k MLCAPE up in NE TX. Problems are storm mode, a small surface inversion. Overall, i can see a risk for spinup tornadoes in NE OK all the way down to conditionally SW AR if convection can mature thru a sharp 700 mb warm nose. If that lessens up then Thursday may be the more notable event given strong low level shear is in place and not misplaced like Friday.
Tends to happen this way, wait until the HRRR gets into range.
RFD66
Member
National Weather Service Memphis TN
545 PM CST Tue Jan 6 2026
edited for emphasis :
**If lower end instability values do manage to
develop, storms will be capable of producing damaging winds and a
brief, spin-up tornado. One thing to note: CSU and CIPS machine
learning models, along with the EFI/SOT depict a southerly shift
in severe potential on Friday. Future outlooks issued by the
Storm Prediction Center may trim the Slight Risk to focus more on
our northeast Mississippi counties.
545 PM CST Tue Jan 6 2026
edited for emphasis :
**If lower end instability values do manage to
develop, storms will be capable of producing damaging winds and a
brief, spin-up tornado. One thing to note: CSU and CIPS machine
learning models, along with the EFI/SOT depict a southerly shift
in severe potential on Friday. Future outlooks issued by the
Storm Prediction Center may trim the Slight Risk to focus more on
our northeast Mississippi counties.
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CheeselandSkies
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It's a bit difficult to compare thermodynamic profiles from areas like Colorado, eastern Wyoming and the Nebraska Panhandle, where the higher terrain tends to make marginal moisture a little more effective (hence why you can see prolific tornado events with dewpoints in the low 50s or even upper 40s) to areas further east. Trey has touched on this a few times in his videos and in some of the "Forecast Challenges" he did for the original Storm Chaser Coaching Community site.
18Z GFS predicts some half-decent CAPE (for January) across AL/GA Saturday afternoon. Wind fields aren't half-bad for the earlier parts of Saturday, but the LLJ really pulls away come the afternoon, so by then you're looking at a pretty marginal risk for tornadoes - not zero, but low (sounding from btw Birmingham and Montgomery). There will be ample moisture in place even in the morning, so if we do get any instability across AL/GA in the morning hours, overlapping with the stronger kinematics, I could see a more robust overnight tornado risk. Overall, highest risk will be on Friday over the Arklamiss with anything that gets going in clusters or as discrete activity in the late afternoon and evening hours. Saturday feels like Marginal or low-end Slight Risk material; conditional but worth keeping an eye on.
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CheeselandSkies
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0Z HRRR actually has a decent environment in southwest to central Arkansas at 0Z Friday, only problem as depicted verbatim it seems is the most robust storms fire on the eastern edge and are already tracking out of it. However...
WeathermanLeprechaun
Member
Think the more minimal instability and surface inversion would limit the ceiling here. Thursday and Saturday looking somewhat alright for severe Wx, Friday a bit questionable to me
CCAir90
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Long time lurker here, and I hate to come out of the shadows to be a stickler.
But, this is completely incorrect regarding dew point. What you mentioned is RELATIVE HUMIDITY. Two temperature+moisture combos may have the same RH, but the higher dew point indicates greater moisture content - a higher ABSOLUTE humidity.
Further, the moisture CAPACITY of air is almost exponentially related to actual temperature, with its capacity rapidly increasing above 50F. Meaning, a dewp of 13 is pretty bone-dry, while a dewp of 70 is extremely moist, regardless of the actual air temp and resulting calculated RH.
That said, your analysis of instability is largely spot-on, although the marginal dewps AND temps in this event are leading to the marginal instability. Skew-T CAPE calculation depends upon the intersection of diabatic & adiabatic lapse rates raised from the surface or mixed-layer dewps AND temps, meaning BOTH contribute to the ultimate CAPE calculation. A relatively high temp - say, 80, 85, etc - can compensate for a marginal dewp, but having soupy dewpoints (like low 70s in Dixie in Spring) can make up for a relatively lower temp (say, 75).
This turned into a book - main point is to clear up the definition of dewpoint as well as to clarify that both dewp & temp from surface upwards contribute to the ultimate CAPE calculation. Now, back into the shadows...
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