DAY 2 ENHANCED RISK FOR SEVERE THUNDERSTORMS SYNOPSIS…ISSUED APR. 30, 2022…8:00 P. M. EDT6 min read
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(T. F. “Storm” Walsh)
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Please be aware, even though I do not post every night, rest assured I am continuously monitoring various areas for any significant weather. I will be taking Sundays off (family time), unless we have active systems that may be posing a threat (i.e. Tropical, Winter Weather, Coastal Storms, etc.).
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 Storm Prediction Center (SPC), has issued an ENHANCED RISK OF SEVERE THUNDERSTORMS in the current DAY 2 outlook: SUNDAY AFTERNOON/EVENING ACROSS THE SOUTHERN HIGH PLAINS…
Very large hail, damaging winds, and a few tornadoes will be possible Sunday afternoon into early Sunday night across the southern High Plains.
Also from the SPC outlook:
It appears that the cap will be relatively weak, so scattered thunderstorm development is likely by mid-late afternoon from southwest TX northward near the TX/NM border, with multiple clusters/supercells possible. Convection will likely persist into the overnight hours, while spreading eastward near the warm front into OK.
SPC DAY 2 CONVECTIVE OUTLOOK LINK:
SPC DAY 2 CONVECTIVE OUTLOOK
Probability of one inch diameter hail or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of two inch diameter hail or larger within 25 miles of a point.
DAMAGING THUNDERSTORM WIND PROBABILITY
Based on my analysis of the SPC DAY 2 Outlook, the thermodynamic setup will allow for all hazards. Analysis of the forecast setup tends to indicate at the moment, the main threat to be large to significant hail over the risk areas, especially within the enhanced risk outline. DCAPE (Downdraft Convective Available Potential Energy) is forecast to favor severe outflow gusts. These outflow boundaries can aid in thunderstorm development further away from the outline area. Within the enhanced area, steep midlevel lapse rates (7.5-8.5 C/km) should produce moderate to strong buoyancy, basically indicating decent lift in the atmosphere. SPC indicates that large hail of 2 to 3 inches in diameter is possible given this thermodynamic setup.
Based on my analysis of both the NAM-WRF model from F5 DATA, and the NAM 3 km model, the following forecast severe and tornado indices were analyzed and values represent a blend of both models:
SBCAPE: 1500 – 2500 j/kg
MLCAPE: 5000 – 2000 j/kg
SRH: 200 – 250 m2/s2
L. I.: -2 to -8
SWEAT: 350 – 475
EHI: 1 – 2
VGP: 0.3 – 0.6
STP: 1 – 3
A majority of significant tornadoes (F2 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.
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.
VGP: The VGP (Vorticity Generation Parameter) is meant to estimate the rate of tilting and stretching of horizontal vorticity by a thunderstorm updraft. Values greater than 0.2 m s-2 suggest an increasing possibility of tornadic storms.
The following sites will explain most of these values, and will give you an idea of what to expect:
ENVIRONMENTAL INDICES AND PARAMETERS NWS
THE WEATHER PREDICTION
The following outlined areas indicate where the modeling suggests the best / highest probabilities for the strongest severe weather and tornadoes could occur. The strongest of the indices will be located where the SPC has the 5% area probability for tornadoes. Based on analysis of the indices, the values begin to increase at around 4:00 p. m. CDT, and become more isolated and weakening around 4:00 a. m. CDT. This is shown on both the NAM 3km STP and SCP animations. The animations will also show you where the strongest index values lie, within the outlined maps. Be advised, these may change, as some of the indices were displaced in the recent run
F5 DATA NAM – WRF 4:00 P. M. CDT
7:00 P. M. CDT
10:00 P. M. CDT
1:00 A. M. CDT
4:00 A. M. CDT
The following NAM 3km animations indicate the locations and strength of the forecast STP (Significant Tornado Parameter) index, and SCP (Supercell Composite Parameter) index.
NAM 3km STP ANIMATION (4:00 P. M. CDT MAY 01 – 4:00 A. M. CDT MAY 02)
NAM 3km SCP ANIMATION
Please use the following maps for all days, which should update automatically, for Mesoscale Discussions and Convective Watches. You may have to refresh your browser, or click on the graphics. I am also providing the SPC homepage link, 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)
SPC HOMEPAGE LINK
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)
WSI DOPPLER RADAR LOOP (LINKED)
RAP RADAR (CLICK IMAGE THEN RADAR SITE)
You may direct any questions by contacting me personally, ANYTIME, at: email@example.com
Have a blessed evening!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
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