Might need to watch the 3/10-3/12 timeframe for another round of severe weather for the south/Dixie alley. May have a couple smaller-setup days before then
Moderate Risk already along the Mississippi River in Mississippi and Louisiana
Re: 2023 Severe Weather
Posted: Thu Mar 23, 2023 3:35 pm
by captainbarbossa19
Iceresistance wrote:Moderate Risk already along the Mississippi River in Mississippi and Louisiana
Yep. Looks like tomorrow will be busy for me.
Re: 2023 Severe Weather
Posted: Fri Mar 24, 2023 1:11 am
by ElectricStorm
Day 1 outlook expands the moderate risk area a bit and includes some very strong wording in the discussion.
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Mar 24 2023
Valid 241200Z - 251200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MID-MISSISSIPPI VALLEY...
...SUMMARY... An outbreak of severe weather is expected from the Lower Mississippi Valley toward the lower Ohio Valley Friday afternoon and evening. Tornadoes, strong to potentially intense, as well as damaging winds and hail are expected.
***Tornado Outbreak Possible Across Portions of the Mid Mississippi Valley Friday Evening***
...Synopsis... A mid-level trough can be seen on water vapor east of the northern Baja Peninsula this morning. This trough will move quickly across the southern Plains through the day and into the Mid Mississippi/Lower Ohio Valley by Saturday morning. A very strong mid-level jet (90-100 knots) will develop as this wave impinges on a strong upper-level High across the Southeast.
Broad warm air advection is expected across the Mid-Mississippi Valley during the day Friday with a strengthening low-level jet through the day. Significant mass response is expected across this area by early evening as the mid-level trough approaches the area. As a result, the surface low will deepen rapidly between 00Z to 06Z to around 992-994mb in the southern Illinois/Indiana vicinity. During this period of rapid deepening, a warm front which is forecast to be mostly stationary from northeast Arkansas to central Tennessee during most of the day, will start to move quickly north during the late afternoon with the northern extent of the warm sector depicted by the approximate path of the surface low.
...Mid Mississippi Valley... Thunderstorms will be ongoing at the beginning of the period across eastern Oklahoma and western Arkansas. Some embedded supercells are possible with the threat for a few weak tornadoes. Most guidance is consistent with the convectively enhanced cold front drifting south into north-central/northeast Arkansas in the morning. Therefore, this early activity will likely wane as it interacts with this southward moving front by late morning.
A pocket of drier air can be seen on water vapor moving north in the west-central Gulf early this morning. This is associated with a relative minimum in PWAT which will overspread eastern Louisiana and much of Mississippi during the late morning and through the afternoon. This seems to be responsible for the significant mixing and surface dewpoint reductions seen my much of the guidance across Mississippi in the afternoon where temperatures warm into low 80s. However, despite this drier air further east, deep moisture will remain across the western Gulf and will advect northward into Louisiana during the afternoon as low-level mass response increases. By mid to late afternoon, upper 60s to potentially low 70s dewpoints are expected across northern Louisiana and eastern Arkansas, spreading into northern Mississippi by the evening. This will lead to an uncapped warm sector featuring MLCAPE of 500-1000 J/kg up the Mississippi River to near Memphis and 1500-2000 J/kg farther south across northern Louisiana and west-central Mississippi.
Expect storms to strengthen during the afternoon as the better moisture advects northward and destabilizes the airmass ahead of ongoing activity. CAM guidance is in agreement for a strong QLCS to develop from central to northern Arkansas during the afternoon. This line of storms will pose a threat for damaging wind and QLCS tornadoes given the long, curved low-level hodographs with the best overlap of favorable shear and instability in the vicinity of the Mississippi River. This line of storms will eventually outrun the better instability as it moves toward Middle Tennessee/southern Kentucky, but the strong low-level jet (~70 kts), and strong forcing with the deepening surface cyclone will help to maintain some severe threat well into the overnight despite progressively more meager instability.
Across southeast Arkansas, northern Louisiana, and northwest Mississippi, a more volatile environment will develop Friday evening/early overnight. More discrete convection is anticipated on the southern periphery of the aforementioned QLCS. The more discrete mode, combined with greater instability and strong shear should allow for multiple supercells to develop across northern Louisiana and southern Arkansas and move northeastward. Low-level hodographs are very favorable in this region with 0-500m SRH around 200 m2/s2 and 0-1km SRH 300+ m2/s2. Therefore, any sustained supercells will be capable of producing strong to intense (EF3+) tornadoes, with long-track tornadoes possible with any longer-lived, undisturbed supercells.
00Z HREF members showed a variety of solutions which cast some uncertainty on the forecast. WRF members are notably less bullish with warm sector supercell development from northeast Louisiana into northern Mississippi while the HRRR was most aggressive with convective coverage and environment. After further investigation it appears the more aggressive HRRR solution can be attributed to a more robust mass response during the afternoon/early evening hours. This results in a pronounced shortwave trough which can be seen at 700 and 850mb and reflected as a significant confluence zone at the surface. Not only does this act as a forcing for storm development, but it also acts as moisture convergence with a more broad region of 70+F dewpoints. In this scenario, numerous strong tornadoes would be likely, with the potential for several intense tornadoes. Despite being the most aggressive, this solution does not seem unreasonable as similar low-level confluence features can been on both the 00Z GFS and the 18Z ECMWF.
As is often the case, the severity of the tornado threat across the moderate risk will be modulated by mesoscale influences in the region. As the event approaches, these mesoscale effects may become more clear and allow the greatest risk corridor to become better defined.
..Bentley/Weinman.. 03/24/2023
If the HRRR continues to look like the 0z run and morning/surface obs support it, I think we could see an upgrade here. Probably a small chance like usual but either way the ceiling for this event is very high. If it does get upgraded it would be the first high risk in almost exactly 2 years, 3/25/21. Overall there's going to be a fine line between a major outbreak and a mostly linear event, hopefully it's the latter.
Re: 2023 Severe Weather
Posted: Fri Mar 24, 2023 8:49 am
by Iceresistance
Moderate Risk now includes Memphis, TN
Re: 2023 Severe Weather
Posted: Fri Mar 24, 2023 3:39 pm
by Tireman4
000 FXUS64 KSHV 242037 AFDSHV
Area Forecast Discussion National Weather Service Shreveport LA 337 PM CDT Fri Mar 24 2023
...New SHORT TERM, LONG TERM...
.SHORT TERM... (This evening through Saturday Night) Issued at 249 PM CDT Fri Mar 24 2023
We are currently monitoring increasing and strengthening thunderstorms across the Arklatex, along and ahead of a cold front pushing into far western zones. What is occurring is meeting our previous expectations for this afternoon as the combination of the incoming front, strengthening low pressure in our northwest along the front, and deep lift prompted by an incoming upper level trough will be increasingly initiating deep and likely severe thunderstorms the rest of this afternoon across western and central portions of the region, with this activity organizing further and advancing out of the Arklatex and into the Arklamiss in several hours. A mixed mode of supercells and QLCS activity is expected to march through the Moderate Risk from the Storm Prediction Center over the Arklamiss and points to the east over this time frame with hail, damaging winds, and tornadoes (some strong) all possible this afternoon into at least early this evening. The latest high resolution guidance consensus suggests any potent supercells will also carry the potential for large hail. While the highest severe weather risk will be in the Moderate risk area, all areas of the Four State region will have at least some risk of severe storms until this system clears the region later on tonight. In addition, most of our covered areas of south-central AR and northern LA are in an Enhanced Risk of severe storms, if not already in the Moderate Risk itself, and all locations in or near the Enhanced or Moderate risk have a risk of experiencing a strong tornado. We expect severe weather to clear east of the region between 9 to 11 pm tonight, but until then at least portions of our region will be experiencing severe weather and everyone needs to be ready to quickly take shelter if under a tornado warning. Finally, most of our region is under a tornado watch until 7 pm, with locations in the Arklamiss not currently in a watch likely to have one issued for them in the not-too-distant future.
Later tonight as the convection exits entirely and the front clears east of the region, expect skies to gradually clear from the west with low temperatures ranging from the mid 40s in the far northwest to near 60 in the far southeast. The air mass in the wake of this front is definitely not overly chilly, so tomorrow should be a nice day with a good amount of sunshine and high temperatures ranging from near 70 in far northwest zones to around 80 in the far southeast. Clouds should probably wait to increase much until Sunday morning with seasonably cool low Saturday night in the 40s and 50s. /50/
&&
.LONG TERM... (Sunday through next Thursday) Issued at 249 PM CDT Fri Mar 24 2023
The weak cold front driving through the region tonight will be trying to slowly come back north toward the region as a warm front by Sunday. Model guidance continues to trend toward more consensus for showers and mainly elevated thunderstorms across central and southern zones as another weak wave aloft in southwest flow triggers convection mainly north of the boundary. There is an SPC marginal risk for mainly just the southeast portion of our forecast area on Sunday and this will have to be watched for potential expansion on later SPC updates. Significant severe weather does not appear likely, although sufficient deep layer wind shear and decent temperature lapse rates aloft could be conducive for at least semi-organized storms producing hail.
Chances for showers and embedded thunderstorms could continue into Monday for central and southern zones as the aforementioned boundary gets further activated by another weak disturbance. This should drive the front back south and latest model trends are more aggressive with a cool and dry push which could keep us rain free most of Tuesday and Wednesday, before another, more significant, upper trough amplifies the perturbed southwest flow pattern over our region. This will return the boundary back north for Thursday and Thursday and Friday holds at least some risk for significant weather from a combination of heavy rain and thunderstorm concerns. That said, there is still some NWP discrepancies regarding evolution that far out, so definitely stayed tuned for further updates in the coming days. /50/
&&
.AVIATION... (18Z TAFS) Issued at 1236 PM CDT Fri Mar 24 2023
A mix of VFR and MVFR conditions are in place currently across the forecast area with ceilings ranging from roughly 2 kft to 4 kft with surface SE to S winds quite gusty, with sustained winds of 15 to 25 mph and gusts up to 30 mph. Scattered showers are blossoming now across most of the region with thunderstorms rapidly developing just west of TYR along a cold front moving toward the region. Expect scattered to numerous strong to severe thunderstorms moving from west to east across the region from roughly now through roughly 10 pm. Expect activity to clear TYR by roughly 4 to 5 pm, clear TXK/SHV/LFK by roughly 5 to 7 pm, and then clear ELD/MLU by 9 to 10 pm. Severe thunderstorms should be accompanied by a risk of large hail, winds in excess of 60 mph, a risk of tornadoes, and IFR to MVFR flight cats. Expect winds to turn to the SW to W in the wake of the front with conditions trending rather quickly back to VFR after the storms pass. Some patchy late night fog cannot be entirely ruled out, with mostly clear skies and west winds of 10 to 15 mph anticipated tomorrow. /50/
Watching closely discrete cells moving into Mississippi from Louisiana. The HRRR shows them, but not near the coverage as currently depicted on radar. These could get ugly in a hurry since some are already producing lightning.
Re: 2023 Severe Weather
Posted: Fri Mar 24, 2023 5:36 pm
by Cpv17
Storm approaching Georgetown, MS looks like it could produce.
Re: 2023 Severe Weather
Posted: Fri Mar 24, 2023 7:20 pm
by ElectricStorm
Very poor lapse rates seem to really be hurting this event so far. We'll see if things can pick up a bit over the next few hours but so far it's been very slow. SPC definitely made the right call not upgrading to high.
Re: 2023 Severe Weather
Posted: Fri Mar 24, 2023 8:04 pm
by ElectricStorm
Welp, starting to pick up now, PDS warning for the cell near Rolling Fork, MS
Mesoscale Discussion 0329 NWS Storm Prediction Center Norman OK 0824 PM CDT Fri Mar 24 2023
Areas affected...North-central MS
Concerning...Tornado Watch 76...
Valid 250124Z - 250215Z
CORRECTED FOR ERROR IN SPATIAL DELINEATION
The severe weather threat for Tornado Watch 76 continues.
SUMMARY...An intense tornado (EF3+) is likely ongoing with a supercell tracking northeastward across western Sharkley County MS, and this storm should persist for the next 30-60 min.
DISCUSSION...Latest radar data shows an organized cyclonic supercell tracking northeastward across western Sharkley County MS, with a VROT above 70 kt and well-defined TDS up to 13k ft -- indicative of an intense tornado (EF3+) given the parameter space (STP of 4). The downstream environment features a large, clockwise-curved hodograph per DGX VWP (around 430 m2/s2 0-1 km SRH) amid rich boundary-layer moisture. This will support the maintenance of this intense supercell toward the northeast for the next 30-60 min.