Disclaimer:  This site 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.

Good day everyone!
The forecast center is closed on Sunday’s.

IF 1300Z SPC outlook graphics are utilized, please check the SPC site for any updates to the outline risks when they are issued.  1630Z updates post at approximately 12:30 p.m.

As of this morning, the Storm Prediction Center has issued a SLIGHT risk for severe thunderstorms for today’s outlook.  SIGNIFICANT HATCHED tornado outlines are present  
CSU – MLP 6 PANEL PROBABILITIES (CLICK FOR LARGER IMAGE)

CURRENT DAY1 SEVERE WEATHER OUTLOOK
The Storm Prediction Center (SPC) has issued a SLIGHT risk for severe thunderstorms in the current DAY1 Outlook: FROM THE LOWER MISSISSIPPI VALLEY ACROSS THE TENNESSEE AND OHIO VALLEYS INTO THE MID-ATLANTIC…

…SPC SUMMARY…
Isolated to scattered severe thunderstorms are expected today from the ArkLaTex and Lower Mississippi Valley northeastward through the Ohio Valley and Mid-Atlantic.
1300Z SPC DAY 1 SEVERE THUNDERSTORM OUTLOOK (LINKED FOR OUTLOOK TEXT)

TORNADO PROBABILITY

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 PROBABILITY

Probability of one inch diameter hail or larger within 25 miles of a point.
DAMAGING THUNDERSTORM WIND PROBABILITY

Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
CSU – MLP DAY1 PROBABILITY (CLICK FOR LARGER IMAGE)

NSSL ML DAY 1 PROBABILITY

DAY 1 PROBABILITY CONVERSION TABLE

SPC DISCUSSION EXCERPT:
…Ohio Valley through the Mid-Atlantic…
Regional radar imagery shows a convective line extending from west-central IN southwestward into southern IL. This line is progressing quickly east-northeastward and has produced several strong gusts (i.e. 40-45 kt) thus far. Regional radar imagery also depicts a MCV moving into southern IL. Mesoscale ascent attendant to this MCV could be aiding in the development of the convective line as well as the more cellular storms to its south. General expectation is for this convective line to continue quickly northeastward across the Ohio Valley, with the robust low-level flow support in the potential strong to severe gusts as well as a few line-embedded tornadoes. This activity will spread east toward the Middle Atlantic by late afternoon.

As a result, a second round of thunderstorms is anticipated as the shortwave and its associated cold front moves through the Ohio Valley during the afternoon and evening. Despite airmass recovery, the overall buoyancy will likely be tempered by widespread clouds and muted diurnal heating. Even so, the combination of modest buoyancy with robust shear will still support another round of strong to severe thunderstorms. Strong gusts are the primary risk, but line-embedded tornadoes are possible as well. Any mature discrete development ahead of the front would likely be supercellular and capable of all severe hazards, including tornadoes.

…East Texas through the Southeast…
A more substantial increase in the coverage of the severe threat is expected later this afternoon, in response to increased ascent attendant to the approaching shortwave trough. This additional development will likely begin in a more cellular mode over east TX before progressing eastward and becoming more linear with time. All hazards are possible with this more cellular activity, including tornadoes. Southwesterly flow aloft should strengthen ahead of the shortwave throughout the evening and overnight, leading to increased organization and strength of the convective line. As such, the threat for damaging gusts and line-embedded tornadoes will persist throughout the night across the Gulf Coast states.

The following maps are from NADOCAST for tornado and hail probabilities.  
00Z NADOCAST TORNADO PROBABILITY

00Z NADOCAST SIGTOR PROBABILITY 

00Z NADOCAST HAIL PROBABILITY 

00Z NADOCAST SIGHAIL PROBABILITY 

Severe thunderstorms were already in progress, and a TORNADO WATCH issued for portions of East-Central and Southeast Illinois Central and Southern Indiana Far Northern Kentucky, Far Northeast Kentucky, Western Ohio, Central and Eastern Ohio, Western and Central West Virginia, and Lake Erie.

Based on my analysis this morning of the current forecast severe weather indices, the forecast seems t0 call for a high end moderately unstable atmosphere at the moment.  Indices and current SPC outlook indicate severe thunderstorms may re-intensify from afternoon through late evening.  The main severe risk as of analysis this morning appears to be large hail, with the based on lifted indices, bulk shear and, moderate mid level lapse rates, and SBCAPE values within the 15% HAIL outline, and damaging thunderstorm winds / gusts.  Tornadoes appear likely and could attain strong (EF2 – EF5) intensity within the 5% HATCHED TORNADO outlines.

Based on analysis of model animations, the current outlook, and analysis of indices, the strongest convection and indices should occur approximately between 11:00 A.M. CDT – 9:00 P.M. CDT (12:00 NOON – 10:00 P.M. EDT)  Strongest indices based on analysis appear to occur over the 5% SPC tornado areas.  Please visit the SPC homepage via the link provided for any changes to the forecast today.
CAPE VALUES FORECAST

DEW POINT FORECAST

Indices were analyzed from the NAM 3KM, HRRR 3KM, CIPS DETERMINISTIC, and SPC SREF model guidance.

The following were the forecast parameters and indices analyzed this morning.  Bear in mind, MAXIMUM indices recorded below are for the time of peak intensity.  Some indices meanings are posted below the indices themselves, and the NWS page containing a more extensive explanation can be accessed further on in the synopsis:
SBCAPE: 500 – 2500 j/kg-1                  
MLCAPE: 500 – 1500 j/kg-1                   
MUCAPE: 500 – 2500 j/kg-1                
SRH 0 -1 km: 150 – 350 m2/s2               
SRH 0 -3 km: 150 – 400 m2/s2        
SRH EFFECTIVE: 100 – 300 m2/s2          
L. I.: -3 to -6                                                  
SCP: 1 – 15                                          
STP: 0.3 – 2.6
0 -6 km SHEAR: 40 kts – 60 kts                  
EFF. SHEAR: 30 kts – 50 kts                        
MID LEVEL LAPSE RATE: 6.0C – 7.0C   
DEWPOINT: 57F – 72F                                    
EHI: 0.5 – 3.7                                  
TOTAL TOTALS INDEX: 49C                
K INDEX: 27C to 36C                                          
SWEAT INDEX: 365 – 475                       
THOMPSON INDEX: 30 to 42      
CRAVEN – BROOKS INDEX: 10,000 – 30,000     

CAPE

ENERGY HELICITY INDEX

K INDEX

TOTAL TOTALS INDEX

STORM RELATIVE HELICITY

LIFTED INDEX

SWEAT VALUES

THOMPSON INDEX

Craven SigSvr Parameter:
The simple product of 100mb MLCAPE and 0-6km magnitude of the vector difference (m/s; often referred to as “deep layer shear”) accounts for the compensation between instability and shear magnitude. Using a database of about 60,000 soundings, the majority of significant severe events (2+ inch hail, 65+ knot winds, F2+ tornadoes) occur when the product exceeds 20,000 m3/s3.

A little fact on SRH values and tornadoes from NOAA / NWS
Storm Relative Helicity (m² s^-2)
SRH (Storm Relative Helicity) is a measure of the potential for cyclonic updraft rotation in right-moving supercells, and is calculated for the lowest 1-km and 3-km layers above ground level. There is no clear threshold value for SRH when forecasting supercells, since the formation of supercells appears to be related more strongly to the deeper layer vertical shear. Larger values of 0-3-km SRH (greater than 250 m² s^-2) and 0-1-km SRH (greater than 100 m² s^-2), however, do suggest an increased threat of tornadoes with supercells. For SRH, larger values are generally better, but there are no clear thresholds between non-tornadic and significant tornadic supercells.

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 are the SCP (Supercell Composite Parameter) and STP (Significant Tornado Parameter) forecast maps from the NAM 3KM model.  Generally, the higher the values and brighter the color, indicates a greater probability of strong thunderstorm and / or tornadic activity over an area:
NAM 3KM SCP FORECAST 10:00 A.M. CDT MAR. 11 – 4:00 A.M. CDT MAR. 12

NAM 3KM STP FORECAST 10:00 A.M. CDT MAR. 11 – 4:00 A.M. CDT MAR. 12

NAM 3KM RADAR SIMULATION 10:00 A.M. CDT MAR. 11 – 4:00 A.M. CDT MAR. 12

Please use the following maps, which 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 below, so you may get the updated information regarding any changes to the outlook:
https://www.spc.noaa.gov/classic.html
SPC MESOSCALE DISCUSSIONS (CLICK IMAGE FOR UPDATES)

SPC CONVECTIVE WATCHES (CLICK IMAGE FOR UPDATES)

The following sites will explain most of the severe weather and tornado values listed above, 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/

The following links will connect you to the Excessive Rainfall probabilities and River Flood Outlook:
EXCESSIVE RAINFALL
https://www.wpc.ncep.noaa.gov/qpf/excessive_rainfall_outlook_ero.php

SIGNIFICANT RIVER FLOOD OUTLOOK
https://www.wpc.ncep.noaa.gov/nationalfloodoutlook/index.html

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 forecasts, any special weather statements, hazards or advisories for your area.
IF A TORNADO WARNING IS ISSUED FOR YOUR AREA…SEEK STURDY AND SAFE SHELTER IMMEDIATELY!

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)
WUNDERGROUND RADAR SUMMARY MAP (CLICK FOR UPDATES)

PRECIPITATION TYPE (CLICK TO ACCESS ANIMATION FEATURE)

CARIBBEAN RADAR (CLICK IMAGE TO ACCESS ANIMATION)

You may direct any questions by contacting me personally, ANYTIME, at: [email protected]

Have a blessed day!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST