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.

The SPC indicates severe weather risks for the remainder of the week, into Wednesday of next week.  
ALL IMAGES LINKED:
DAY 2

DAY 3

DAY 4 – 8

CURRENT DAY1 SEVERE WEATHER OUTLOOK
The Storm Prediction Center (SPC) has issued a SLIGHT risk for severe thunderstorms in the current DAY1 Outlook: ACROSS THE SOUTHERN HIGH PLAINS…

…SPC SUMMARY…
Scattered thunderstorms producing hail and strong wind gusts are possible across portions of the southern High Plains this afternoon and evening. More isolated strong to severe thunderstorms are expected across parts of the central Rockies, central Plains, upper Mississippi Valley, and portions of the California coast.

1300Z SPC DAY 1 SEVERE THUNDERSTORM OUTLOOK (LINKED FOR OUTLOOK TEXT)

TORNADO PROBABILITY

Probability of a tornado 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 DAY 1 AND 2 FORECAST PROBABILITIES (CLICK FOR LARGER IMAGE)

NSSL ML DAY 1 PROBABILITY

The current CSU – MLP probabilities forecast indicates a possible upgrade to an ENHANCED risk for Mon. and Tue.:
CSU – MLP 6 PANEL PROBABILITIES DAY 3 – DAY 8 (CLICK FOR LARGER IMAGE)


DAY 1 PROBABILITY CONVERSION TABLE

SPC DISCUSSION EXCERPT:
…Southern High Plains…
Thunderstorm development is likely by mid/late-afternoon across southwest Texas and eastern New Mexico as increase forcing for ascent overspreads modest but increasing low-level moisture. Initially discrete cells are likely and will pose a threat for large hail given adequate deep-layer wind shear /generally 30-40 kt/. However, weak capping and strong ascent should promote upscale growth by early evening into several linear clusters. As this transition occurs, strong to severe wind gust potential will increase and become the predominant hazard, though an embedded circulation or two may occur with a tornado possible.

…Central Plains to the Upper Mississippi Valley…
Low-level warm air advection will likely become increasingly focused through the day and into the overnight hours from the central Plains into the upper Mississippi Valley. 850 mb winds are forecast to steadily strengthen to 40-60 kt by this evening and will support moistening in the lowest 1-2 km under a plume of 7-7.5 C/km mid-level lapse rates. Forecast soundings suggest that this environment will be weakly capped and should support isolated to widely scattered thunderstorms during the afternoon hours across the central Plains before spreading/re-developing northeastward into the upper Mississippi Valley late tonight. While deep-layer wind shear will not be overly strong (around 30 kt), it should be sufficient for a few organized cells capable of severe hail.

A more conditional supercell potential may materialize by mid/late afternoon through early evening across portions of the middle/lower Missouri Valley near/just south of the northward-shifting surface warm front, which may augmented by residual cloud cover/weakening storms across northeast Kansas/far southeast Nebraska in the pre-dawn hours. Forecast soundings from this region suggest a weakly capped, but moderately buoyant airmass, with notably strong low-level/deep-layer wind profiles that would conditionally support supercells including some tornado risk.

The following maps are from NADOCAST for tornado and hail probabilities.  Click each image for a larger view.  If you tilt your head, you will be able to see the .1% tornado probability which is very light shading in the larger image. 
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 moderately unstable atmosphere at the moment within the SLIGHT risk outline.  The main severe risk as of analysis this morning appears to be a possibility for large hail, and damaging wind gusts.  A 2% TORNADO risk exists over a portion of Texas, and a small area over SE Nebraska and NE Kansas.

Based on analysis of mainly model animations, the current outlook, and analysis of indices, the strongest convection and indices should occur approximately between mid afternoon through late evening hours.    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, highest MLCAPE values for the best probability of tornado activity. I utilize the SRH and MLCAPE values over the area that has the highest tornado risk potential.  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 within the SLIGHT risk outline and 15% HAIL outline over Texas.  It was noted although the average of SBCAPE values and SRH were greater over the 2% TORNADO outline over the Nebraska area and a portion of Kansas, MLCAPE was the weakest at these locations, leaving the Texas outline with the greater probability for tornado activity. 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: 1500 – 2500 j/kg-1                  
MLCAPE: 1250 – 2000 j/kg-1                   
MUCAPE: 1500 – 2500 j/kg-1                
SRH 0 -1 km: <50 – 100 m2/s2               
SRH 0 -3 km: 100 – 175 m2/s2        
SRH EFFECTIVE: 50 – 150 m2/s2          
L. I.: -4 to -9                                                  
SCP: 1 – 8                                         
STP: 0.5 – 1.2
0 -6 km SHEAR: 30 kts – 40 kts                  
EFF. SHEAR: 30 kts – 35 kts                        
MID LEVEL LAPSE RATE: 6.0C – 7.5C   
DEWPOINT: 56F – 63F                                    
EHI: 0.8 – 2.2                               
TOTAL TOTALS INDEX: 55C                
K INDEX: 28C to 36C                                          
SWEAT INDEX: 490 – 535                     
THOMPSON INDEX: 32 to 45     
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. CDT APR. 11 – 1:00 A.M. CDT APR. 12

NAM 3KM STP FORECAST 1:00 P.M. CDT APR. 11 – 1:00 A.M. CDT APR. 12

NAM 3KM RADAR SIMULATION 1:00 P.M. CDT APR. 11 – 1:00 A.M. CDT APR. 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: twalsh22000@yahoo.com

Have a blessed day!

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