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
FROM PARTS OF EAST TEXAS ACROSS CENTRAL/NORTHERN LOUISIANA TO CENTRAL/SOUTHERN MISSISSIPPI…
Tornadoes (some strong), damaging thunderstorm winds and isolated large hail are expected from this afternoon across east Texas and parts of Louisiana, into tonight across the Delta region into portions of Mississippi and Alabama.
SPC DAY 1 SEVERE THUNDERSTORM OUTLOOK MAPS (THIS MAP LINKED)
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.
Based on my analysis this morning of the SPC DAY 1 Convective Outlook, severe weather and tornado indices from the NAM and HRRR models and CIPS guidance, all severe threats will be possible this afternoon through tonight and into early morning. 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 60 – 65 kts and effective shear of 40 – 50 kts, which lends itself to helicity or rotation in the atmosphere and supercells. While not strong, upon the initiation of storms that may occur prior to 3:00 p.m. CST the stronger severe storms develop between 3:00 p.m. (21Z) and 6:00 p.m. (00Z) CST. CAPE values are forecast to become moderately unstable and forecast lifted indices indicate the atmosphere will be buoyant enough for severe thunderstorms and supercells to develop. Given the increase in the L.I. values this morning, isolated large hail cannot be ruled out in the stronger supercells. Based on forecast wind shear and effective shear values 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 a possibility of an upgrade, which would be to moderate, may be required for a portion of the risk area. 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, these values could change between now and this evening:
SBCAPE: 750 – 1500 j/kg-1
MLCAPE: 1000 – 1500 j/kg-1
MUCAPE: 750 – 1500 j/kg-1
SRH: 300 – 400+ m2/s2
L. I.: -4 to -6
STP: 3 to 6
SCP: 7 to 12
EFF. SHEAR: 40 – 50 kts
0 -6 km SHEAR: 60 – 65 kts
MID LEVEL LAPSE RATE: 6.0 – 6.5C
DEWPOINT: 65F – 72F
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
THE WEATHER PREDICTION
SPC HOMEPAGE LINK
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, and greater risk for stronger of the both.
NAM MODEL SCP FORECAST
NAM MODEL STP FORECAST
The following graphics from the SREF model indicate the time and probability of STP values greater than one. A majority of significant tornadoes (EF2 or greater damage) have been associated with STP values greater than 1
STORM PREDICTION CENTER PROBABILITY FOR STP VALUES >1
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)
You may direct any questions by contacting me personally, ANYTIME, at: firstname.lastname@example.org
Have a blessed evening!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
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