ENHANCED RISK SEVERE THUNDERSTORM OUTLOOK…ISSUED NOV. 19, 2023…6:10 P.M. EST

Disclaimer: This is not affiliated with the National Hurricane Center, Hurricane Hunters, Storm Prediction Center, or National Weather Service. ALL forecasts herein are the result of my analysis, (to which you will see me at times, insert excerpts from various agencies due to the nature of the importance of the information) and I am solely responsible for the content. As ALWAYS, follow the National Hurricane Center, National Weather Service, and your local Emergency Management officials for emergency decisions. In addition, this is strictly a FORECAST OFFICE. I CANNOT make decisions regarding travel plans, etc. My purpose, is to provide you the information, based solely on information I analyze, and the accuracy of the information at hand of the time of analysis, so you may make informed decisions.
(T. F. “Storm” Walsh)

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I will reiterate, my forecasts are based on the available information at the time of analysis, and are only as accurate as the information analyzed and the solutions provided.

The outlined maps you were used to seeing from my F5 DATA software, are no longer around and operational. This means I have lost quite a bit of data to analyze but I will try to make the severe weather forecasts as accurate and understandable as possible.

The Storm Prediction Center (SPC), has issued an ENHANCED risk of severe thunderstorms FOR PORTIONS OF NORTHERN LOUISIANA AND CENTRAL MISSISSIPPI…

…SPC SUMMARY…
Severe thunderstorms are likely Monday afternoon into Monday night from east Texas into parts of the Lower-Mississippi Valley and Southeast. Damaging winds and several tornadoes, a few of which may be strong, will be the primary hazards. However, some large hail is also possible

SPC DAY 2 SEVERE THUNDERSTORM OUTLOOK MAPS (THIS MAP LINKED)

TORNADO

Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 – EF5 tornadoes within 25 miles of a point.
HAIL
day2probotlk_1730_hail
DAMAGING WINDS

Based on my analysis this evening of the SPC DAY 2 Convective Outlook, severe weather and tornado indices, from the NAM model and CIPS guidance, all severe threats will be possible for tomorrow. A brief summary of the analysis indicates veering winds from the surface (southerly) to SWLY at the 850 mb level, to westerly from 500 mb to the upper level. This will aid in some favorable wind shear of 50 – 60 kts and effective shear of 40 – 50 kts which lends itself to helicity or rotation / turning in the atmosphere. While not strong upon initiation of the stronger severe storms, CAPE values are forecast to become moderately unstable and the current forecast lifted indices indicate the atmosphere will be buoyant enough for severe thunderstorms and supercells to develop. The STP is estimating the stronger storms at approximately 21Z (3:00 p.m. CST) – 00Z (6:00 p.m. CST). Large hail cannot be ruled out in the stronger supercells, and some isolated strong tornadoes are possible (EF2 – EF3), and should be most probable within the enhanced risk area, especially in the hatched area on the SPC tornado map. SPC mentions in the outlook, that supercell development is forecast to occur during the evening, into the overnight hours. As I ran the model out a little further, severe parameters are forecast to strengthen over Mississippi, which could mean a more of a threat for strong tornadoes and large hail along with damaging wind gusts.

The following forecast indices and parameters were observed in analysis this evening for the risk area, and are representative of the time period 21Z – 00Z mentioned in the forecast . Depending on how exactly the situation develops, and degree of daytime heating tomorrow, these values CAN change between now and the 12Z model run:
SBCAPE: 750 – 1500 j/kg-1
MLCAPE: 1000 – 1000 j/kg-1
MUCAPE: 750 – 100 j/kg-1
SRH: 250 – 400+ m2/s2
L. I.: -3 to -5
STP: 3 to 6
SCP: 5 to 8
EFF. SHEAR: 40 – 50 kts
0 -6 km SHEAR: 50 – 60 kts
MID LEVEL LAPSE RATE: 6.5 – 7.0C
DEWPOINT: 65F – 71F

STP ( Significant Tornado Parameter) EXPLAINED:
A majority of significant tornadoes (EF2 or greater damage) have been associated with STP values greater than 1, while most non-tornadic supercells have been associated with values less than 1 in a large sample of RAP analysis proximity soundings.

SCP (Supercell Composite Parameter) EXPLAINED:
A multiple ingredient, composite index that includes effective storm-relative helicity (ESRH, based on Bunkers right supercell motion), most unstable parcel CAPE (muCAPE) and convective inhibition (muCIN), and effective bulk wind difference (EBWD). Each ingredient is normalized to supercell “threshold” values, and larger values of SCP denote greater “overlap” in the three supercell ingredients. Only positive values of SCP are displayed, which correspond to environments favoring right-moving (cyclonic) supercells.

The following sites will explain most of these values, and will give you an idea of what to expect:
ENVIRONMENTAL INDICES AND PARAMETERS NWS
https://www.weather.gov/lmk/indices

THE WEATHER PREDICTION
http://www.theweatherprediction.com/severe/indices/

SPC HOMEPAGE LINK
https://www.spc.noaa.gov/classic.html

The following are animations of both the SCP and STP The animation runs from 3:00 p.m. to 6:00 p.m. CST. The greater the index value, the greater the risk to an area for supercell and tornado development.
NAM MODEL SCP FORECAST
nam-nest-louisiana-supercell_comp-1700416800-1700514000-1700524800-80 NAM MODEL STP FORECAST

The following maps, should update automatically for Mesoscale Discussions and Convective Watches. You may have to refresh your browser, or click on the graphics. I have provided the SPC homepage link above, so you may get the updated information regarding any changes to the outlook:
SPC MESOSCALE DISCUSSIONS (CLICK IMAGE FOR UPDATES)

SPC CONVECTIVE WATCHES (CLICK IMAGE FOR UPDATES)

IF A TORNADO WARNING IS ISSUED FOR YOUR AREA, IMMEDIATELY TAKE STURDY AND SAFE SHELTER
The following NWS Watch / Warning map will provide local NWS information for your area. Click the image, then once it refreshes, click on your area of interest to view any special weather statements, hazards or advisories for your area.
NWS WATCH / WARNING DISPLAY (LINKED…CLICK MAP, THEN YOUR AREA)

NWS DOPPLER RADAR LOOP (LINKED, CLICK RADAR MAP)

RAP RADAR (CLICK IMAGE THEN GO TO LOOP DURATION AND PICK LENGTH OF LOOP, THEN CLICK RADAR SITE)
CARIBBEAN RADAR (CLICK IMAGE)

I will try to have an update late tomorrow morning in this situation.