The shortwave on Sunday night will serve as a primer wave for the next system developing to our west on Monday. A wide area of rich moisture will be lurking near the Gulf Coast, poised to move inland Monday afternoon and evening as wind fields respond to a shortwave entering the Southern Plains. Models are coming into agreement on a potentially dangerous setup Monday night into Tuesday morning across a large area which includes Alabama. The GFS and ECMWF are in good agreement with the evolution of the synoptic pattern, showing a low-amplitude shortwave taking on a negative tilt Monday night to our northwest. This pattern has the look of a classic severe weather outbreak and would support a rapidly deepening surface low tracking toward the Great Lakes with significant pressure falls extending southward into Alabama. With dewpoints rising into the upper 60s to perhaps 70F, instability appears more than sufficient for deep convection within a very highly sheared environment. Taken at face value, the ECMWF shows semi-discrete supercells capable of producing long-track, significant tornadoes across the northern half of our forecast area on Tuesday morning. The HWO will be updated to include a moderate confidence threat for tornadoes and damaging winds across the entire forecast area. With this threat still around 96 hours out and models subject to change, we will refrain from going all in on the potential for a tornado outbreak.
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 020907
SPC AC 020907
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0407 AM CDT Fri Nov 02 2018
Valid 051200Z - 101200Z
Potential exists for a significant severe event to transpire day 4
(Monday) into day 5 (Tuesday) mainly from the lower MS Valley into
the Southeast States. Model solutions have converged and
demonstrated run to run consistency, depicting significant
cyclogenesis to commence by Monday evening over the lower MS Valley
in response to an approaching intense upper jet within base of an
amplifying shortwave trough. The low is forecast to deepen as it
lifts northeast into IL overnight with trailing cold front advancing
through the TN and lower MS valley regions. Richer low-level
moisture residing over the northern Gulf will advect rapidly
northward through the warm sector in response to the strengthening
low-level jet, contributing to destabilization with moderate
instability possible from east TX into a portion of the Gulf Coast
states. Severe storms are likely to develop along advancing cold
front Monday afternoon initially from southeast OK into east TX,
then spreading into the lower MS Valley and TN Valley regions Monday
night. Impressive wind profiles with large hodographs and an intense
upper jet will promote a threat for damaging wind, tornadoes and
large hail. Severe threat will continue east through portions of the
Southeast states and Middle Atlantic Tuesday.
POTENTIALLY DANGEROUS WEATHER EARLY NEXT WEEK: A deep, negative tilt upper trough will develop across the Central U.S. with very strong winds aloft, and a rapidly deepening surface low will move quickly from the Texas Panhandle to near Chicago. This will bring a rather potent severe weather setup to the southern U.S. Monday into Tuesday.
Based on the projected shear and instability values, it sure looks like thunderstorms across Alabama with this system will have the potential for large hail, damaging winds, and tornadoes. For now, the severe weather seems most likely late Monday night into Tuesday… generally in the range from midnight Monday night to noon Tuesday. SPC already has a risk of severe storms defined for most of Alabama during this time frame.
It is still early to be more specific, but with good model consistency, the pattern, and the time of the year, I would recommend everyone review your severe weather plan this weekend.
*Be sure you have multiple, reliable ways of receiving severe weather warnings. Have a NOAA Weather Radio in your home (if you already have one, change the batteries this weekend when you “fall back” and set the clocks tomorrow night). And, have a good app on your phone designed for warnings. NEVER rely on a siren.
*Know where you are going. In a site built home, that is a small room, on the lowest floor, away from windows, and near the center of the house. If you live in a mobile home, know the locations of nearby shelters and have a quick way of getting there.
*In your safe place, have a readiness kit that includes helmets for everyone (bicycle or batting helmets are great), portable airhorns, and hard soled shoes.
*Like April 27, 2011? That is not a good question; days like that are generational, and tend to happen every 40 years or so. All you need to know is that it takes just one tornado in the entire state, and if that tornado comes down your street, then it is YOUR April 27. We have to be ready for every severe weather threat.
Since the event is 96 hours out… we can’t be any more specific at this point, but we will keep you updated and coming days as we get closer.
Yes, if there's CAD, there's not going to be severe from NE/E Georgia and up. I've seen plenty of systems that look dangerous end up being a lamb in a good portion of Georgia because CAD snuffed it out.
That's not to say that this won't be a dangerous system in Alabama and points west or Tennessee though.
Pretty decent squall line threat with the possbility of discrete supercells. Cape overnight is between 800-1000, plenty for a fall setup. The more impressive bit though is the spring like broad based trough.