Tony Lyza
EF3
Thursday appears to be evolving into a nastier situation with each model run. I have grave concerns for the Mississippi Valley.
The 1800z GFS showed a powerful sfc low at the following positions:
36hr (0600z Thursday): 992 mb wrn OK
42hr (1200z Thursday): 900mb IA/MO/IL intersection
48hr (1800z Thursday): 984mb ern MO
54hr (0000z Friday): 980mb nw IL
60hr (0600z Friday): 977mb wrn Lake Michigan
The 1800z GFS also shows LI's of up to -3.60, especially in Mississippi.
As for the 1800z ETA, it has the sfc low progged at the following locations:
36hr (0600z Thursday): not formed
42hr (1200z Thursday): beginning to form over the Red River
48hr (1800z Thursday): 989mb over nw Arkansas
54hr (0000z Friday): 987mb over St. Louis
60hr (0600z Friday): 986mb over ctl IL
The ETA shows a tongue of 1500-2000 J/kg SBCAPE all the way up to the southern suburbs of St. Louis, with 500 J/kg SBCAPE numbers all the way up to Springfield. MLCAPE numbers of up to 200 J/kg stream north to the Missouri Bootheel, with 1500 J/kg MLCAPE up to St. Louis. A slight inversion is forecast to be in place over this area, with CIHN of up to -40 indicated. Dew points of 60-65°F are indicated to spread up to srn IL, with the ETA showing LIs of up to -6. All this, along with a LLJ of up to 75kt, a 700mb system of up to 77kt, a 500mb system of up to 95kt, and a 250mb jet stream disturbance of up to 110kt in Mississippi. The 0-3km helicity of up to 500 m**2/s**2 would probably yield a 0-3km EHI of up to ~4.5-5. Though a severe squall line will likely be in place that morning, these numbers should yield addtional development of storms ahead of the squall line. It is my belief that these will be intense supercells, with the possibility of strong/violent tornadoes. I also would not be surprised if a couple of cells broke off the squall line to become supercells a la the Evansville tornado.
I leave you with this quote from Tim Roche, professional meteorologist with the Weather Underground:
The 1800z GFS showed a powerful sfc low at the following positions:
36hr (0600z Thursday): 992 mb wrn OK
42hr (1200z Thursday): 900mb IA/MO/IL intersection
48hr (1800z Thursday): 984mb ern MO
54hr (0000z Friday): 980mb nw IL
60hr (0600z Friday): 977mb wrn Lake Michigan
The 1800z GFS also shows LI's of up to -3.60, especially in Mississippi.
As for the 1800z ETA, it has the sfc low progged at the following locations:
36hr (0600z Thursday): not formed
42hr (1200z Thursday): beginning to form over the Red River
48hr (1800z Thursday): 989mb over nw Arkansas
54hr (0000z Friday): 987mb over St. Louis
60hr (0600z Friday): 986mb over ctl IL
The ETA shows a tongue of 1500-2000 J/kg SBCAPE all the way up to the southern suburbs of St. Louis, with 500 J/kg SBCAPE numbers all the way up to Springfield. MLCAPE numbers of up to 200 J/kg stream north to the Missouri Bootheel, with 1500 J/kg MLCAPE up to St. Louis. A slight inversion is forecast to be in place over this area, with CIHN of up to -40 indicated. Dew points of 60-65°F are indicated to spread up to srn IL, with the ETA showing LIs of up to -6. All this, along with a LLJ of up to 75kt, a 700mb system of up to 77kt, a 500mb system of up to 95kt, and a 250mb jet stream disturbance of up to 110kt in Mississippi. The 0-3km helicity of up to 500 m**2/s**2 would probably yield a 0-3km EHI of up to ~4.5-5. Though a severe squall line will likely be in place that morning, these numbers should yield addtional development of storms ahead of the squall line. It is my belief that these will be intense supercells, with the possibility of strong/violent tornadoes. I also would not be surprised if a couple of cells broke off the squall line to become supercells a la the Evansville tornado.
I leave you with this quote from Tim Roche, professional meteorologist with the Weather Underground:
As the sun angle starts to rise in March and April, the ground begins to warm up a lot faster than the upper atmosphere. This creates instability, and is one of the major reasons that springtime is severe weather season in the Mid-West. Instability isn't the only factor in severe thunderstorms you need a bunch of factors coming together.
These factors look like they might begin to converge over the southern Mississippi Valley on Thursday afternoon. Moist southerly flow ahead of the system will substantially moisten the Atmosphere, while a strong shortwave trof moves into the target region. This combination of events, coupled with the extra instability caused by the sun warming the low layers of the atmosphere could spell disaster for those living in the area.