• Hello, please take a minute to check out our awesome content, contributed by the wonderful members of our community. We hope you'll add your own thoughts and opinions by making a free account!

Severe December 28th -new years possible severe weather event.

May want to extend the date.
scp.conus.png
 
Snowfan said:
May want to extend the date.
scp.conus.png
Click to expand...
Definitely a moist air mass setting up shop around the southeast for a good chunk of time. Models aren't in good agreement that far out though, heck the day 5 risk still isn't in good consensus with models lol. But I imagine with the moist air mass there will be some threat eventually down the road from the first potential batch. January seems to be a bad month for tornadoes in Alabama. Two ef3s just miles from me the last 10 years in January.
 
FROM SPC FOR DAY FIVE

Wed - Northern Mississippi, northern Alabama, and vicinity...
Prior to D5, the warm sector moisture has been contaminated by
continental air which has led to weak instability across much of the
warm sector. However, by Tuesday night, a true maritime tropical
moisture feed is forecast to overtake the western Gulf of Mexico.
Persistent southerly flow will advect this airmass inland from
eastern Texas to northern Mississippi/Alabama by Wednesday
afternoon. Moderate instability should develop south of a front,
which is expected to be in place from eastern Texas into the
Tennessee/Ohio Valley region. There is decent model agreement with
the increasing low-level moisture and the relative position of the
surface front. However, the upper-level pattern does cast more
uncertainty on the forecast.

The details of any severe weather threat will come from the
evolution of the low-amplitude wave to eject from the larger scale
western CONUS upper-level trough. Predictability of the
timing/amplitude of upper-level troughs such as these is inherently
challenging, especially at Day 5. Therefore, it is unsurprising that
there is still considerable spread between available mid-range model
guidance. The last 2 runs of the ECMWF have shown a more amplified
mid-upper level trough which would initiate a greater low-level mass
response and likely lead to a greater severe-weather threat.

Therefore, uncertainty remains regarding the evolution, timing, and
amplitude of the upper-level pattern on Wednesday. However, there
has been a consistent signal for surface-based storms in an
environment with moderate buoyancy and strong shear for several
days. The aforementioned arrival of a maritime tropical airmass in
the vicinity of a surface front and at least weak height falls aloft
is consistent with at least scattered storm development. Therefore,
confidence is high enough to introduce 15 percent severe
probabilities for Wednesday.

..Bentley.. 12/25/2021
 
Again. Very isolated convection being shown for late wensday into early Thursday morning. Instability increases as the LLJ ramps up in the overnight hours.Screenshot_20211226-150325.pngScreenshot_20211226-150311.pngScreenshot_20211226-150346.pngScreenshot_20211226-150358.png
 
tennessee storm said:
Still think the second system around new years has a even higher ceiling
Click to expand...
I think so too. The wensday system though might be a banger. I'm pretty intrigued, looking at forecast soundings. Shows a loaded gun setup. There's a decent bit of supportive factors for wensday, the cape has ticked up with each new NAM run, wouldn't be surprised for a enhanced corridor at least. Might not be a tornado outbreak with the wensday system but it sure could produce 1 or 2 significant storms.
 
Myfrotho704_ said:
That’s not really a EML but just lots of dry air aloft, a EML typically has 6.5C+ lapse rates, lapse rates under 6C are very poor
Click to expand...
Hmmph. I thought dry air aloft and eml where the same ?. I always looked at the 500mb area and see those jagged lines pushing to the west of the sounding and thought that correlated with a good EML. Does both no aid in more discreet convection, and loaded gun soundings?
 
Zander98al said:
Hmmph. I thought dry air aloft and eml where the same ?. I always looked at the 500mb area and see those jagged lines pushing to the west of the sounding and thought that correlated with a good EML. Does both no aid in more discreet convection, and loaded gun soundings?
Click to expand...
Typically a EML has steep mid level lapse rates (near dry adiabatic lapse rate) and a cap within a area of dry desert airEABCCD78-6003-410F-95CC-14A3E3A3B963.gif
That sounding you posted just has dry air aloft, typically dry air aloft makes convection more discreet but increases the chance of damaging wind gusts/stronger downdrafts, given dry air entrainment creates evaporative cooling and downward momentum in thunderstorms, which is the process that results in microbursts. Basically dry air aloft means a high chance of downdraft/RFD dominated convection/supercells
 
Spc mentions they're holding off on added enchanced and a hatched 10% tornado risk because of uncertainty with the surface low. If this isnt eerie looking I don't know what is. 20211228_035604.jpg
 
Per the 12z hrrr. There's a decent little swath of updraft tracks in central Alabama I've been seeing this a few runs. My thinking is, that a enchanced area will be added in this corridor with the sig tornado chance. The Birmingham vicinity seems to be the sweet spot of both instability and shear as of right now.Screenshot_20211228-074559-599.png
 
12z NAM is really impressive with thermodynamics across MS/west AL. One of the big sticking points right now is the almost complete unidirectional flow. The surface will suffice and probably back more, but there really needs to be more directional turning aloft.
 
How stupid 18z hrrr run was skipped over. Now I gotta wait til the 00z to see what tommorow a threat looks like on the hrrr ???
 
I feel like tommorows event will overproduce a bit. It already feels muggy outside so it's not going to take much for it to destabilize more. I think it's aiding in the intensity by this system being nocturnal cause it's really juicing out as much shear as it can coming during the night when shear increases.
 
Temp is 72 and dew point 66. That's muggy for a winter day. Me thinking out loud, but I wonder how well models are grasping the moisture. Seems to always be underdone and never do that well during the winter months. When it comes to instability.
 
If anything hopefully we can get a good amount of rain out of this system and the next. We could use some after how dry it has been the last few months.
 
You must log in or register to reply here.
Back
Top