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, and for Tue. – Fri.  

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 MID MISSISSIPPI VALLEY ACROSS THE OHIO VALLEY AND SOUTHERN GREAT LAKES…AND ACROSS WESTERN OKLAHOMA AND FAR NORTHWEST TEXAS…

…SPC SUMMARY…
Scattered severe thunderstorms with damaging wind gusts and large hail are expected today from the Mid Mississippi Valley across the Ohio Valley and southern Great Lakes. Isolated severe storms capable of large hail and damaging gusts are possible across western Oklahoma and far northwest Texas as well.

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

CSU – MLP 6 PANEL PROBABILITIES DAY 1 AND DAY 2 (CLICK FOR LARGER IMAGE)

DAY 3 – DAY 8

DAY 1 PROBABILITY CONVERSION TABLE

SPC DISCUSSION EXCERPT:
…Mid/Upper MS Valley across the southern Great Lakes and OH Valley into the Northeast…

Showers and thunderstorms occurred overnight along and north of this boundary, with the primary remnants currently over southwestern ON towards western NY.

 Additional thunderstorm development is beginning to the northwest of the IA/WI border surface low as well as farther south within the warm sector across northern IL. This activity is likely supported by a combination of persistent warm-air advection and ascent linked to a subtle shortwave trough moving through IA. Most guidance suggests this activity, particularly the IL cluster, increases in coverage and intensity over the next several hours as it continues eastward across Lower MI and eventually into western PA/western NY. Some intensification of the convective remnants moving across southwest ON is possible as well. Robust deep-layer westerly flow amid at least modest buoyancy will support damaging gusts as the primary severe risk with these clusters. There is also enough low-level curvature to support a low-probability tornado risk, particularly along the southwest flanks of the IL and ON clusters where a more cell-in-line convective mode is possible. A line-embedded circulation could also occur if these clusters can become more organized.

How these clusters evolve, in particular the strength of any outflow, will dictate the extent of airmass recovery in their wake. This is particularly true across the OH Valley where much of the guidance suggests another round of thunderstorms is possible along a cold front forecast to move across the region this evening. Current expectation is that the airmass will support strong to severe thunderstorms, especially from central IN into central IL where the influence of antecedent convection should be minimal. Steep lapse rates and moderate shear will support a hail risk with the initially more cellular development along the front. A trend towards a more linear mode is anticipated thereafter, with undercutting by the cold front likely as well.

…Central/Southern Plains…
Increasing low-level moisture and strong heating will help destabilize the airmass ahead of the front and surface low. Low-level convergence along the front/dryline, and particularly near the surface low, will support convective initiation. Vertical shear will be sufficient for storm organization and a few supercells are possible. Steep lapse rates and strong shear in the cloud-bearing layer suggest large hail is possible early in the convective cycle, while high LCLs suggest a trend toward strong downbursts thereafter.

The following maps are from NADOCAST for tornado and hail probabilities.  
12Z NADOCAST TORNADO PROBABILITY

12Z NADOCAST SIGTOR PROBABILITY 

12Z NADOCAST HAIL PROBABILITY 

12Z NADOCAST SIGHAIL PROBABILITY 

Based on my analysis this morning of the current forecast severe weather indices, the forecast calls for a moderately unstable atmosphere at the moment.  The main severe risk as of analysis this morning appears to be large hail, based on lifted indices, steep mid level lapse rates, and maximum SBCAPE values within the 15% HAIL outlines, and damaging thunderstorm winds / gusts.  Tornadoes may be possible within the 2% TORNADO / HATCHED outline over the northern risk area, and should remain within the  (EF0 – EF1) intensity, however an isolated EF2 cannot be ruled out. 

Based on analysis of model animations, the current outlook, and analysis of indices, the strongest convection and indices should occur approximately between 3:00 P.M. EDT  – 11:00 P.M. EDT.  Strongest indices based on analysis appear to occur over the 15% SPC HAIL 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.

REGARDING EHI VALUES: While EHI values are calculated utilizing MLCAPE and 0 – 3 km SRH values (MLCAPE x 0 – 3 km SRH /160,000), the highest SRH values do not always fall within ample MLCAPE values in order to provide the best probability for tornado activity.  Maximum EHI values are calculated within the area(s) that have the greatest probability for tornado activity

The following were the forecast parameters and indices analyzed this morning, and will pertain the the northern risk outlines where the tornado risk is the greatest.  Although the outline area for OK/TX has the highest maximum SBCAPE and very steep lapse rates, weak shear and lack of any significant SRH and lower MLCAPE do not indicate a tornado threat at the moment.  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: 750 – 2000 j/kg-1                  
MLCAPE: 500 – 1500 j/kg-1                   
MUCAPE: 750 – 2000 j/kg-1                
SRH 0 -1 km: 100 – 200 m2/s2               
SRH 0 -3 km: 100 – 400 m2/s2        
SRH EFFECTIVE: 100 – 200 m2/s2          
L. I.: -3 to -8                                                  
SCP: 2- 10                                         
STP: 0.3 – 1.6
0 -6 km SHEAR: 30 kts – 50 kts                  
EFF. SHEAR: 30 kts – 40 kts                        
MID LEVEL LAPSE RATE: 7.0C – 8.0C   
DEWPOINT: 54F – 64F                                    
EHI: 1.8 – 2.4                                  
TOTAL TOTALS INDEX: 55C                
K INDEX: 24C to 36C                                          
SWEAT INDEX: 500 – 560                      
THOMPSON INDEX: 27 to 44     
CRAVEN – BROOKS INDEX: 10,000 – 25,000     

The following are some severe weather parameters and indices explanations:
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 1:00 P.M. EDT MAR. 31 – 3:00 A.M. EDT APR. 01

NAM 3KM STP FORECAST 1:00 P.M. EDT MAR. 31 – 3:00 A.M. EDT APR. 01

NAM 3KM RADAR SIMULATION 1:00 P.M. EDT MAR. 31 – 3:00 A.M. EDT APR. 01

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