Tornado Threat Forecast: May 17-23, 2018

Plains tornadoes are back! But how many and where can we expect them over the next seven days? Let’s find out as we head into the peak of the average tornado season.

1-3 Day

Thursday – Northern Plains

NUMBER OF TORNADOES EXPECTED: 1-3 – CONFIDENCE: Normal
Tornado Hot-spot: None

Pros: Moderate to high instability, good low-level directional shear and speed shear, decent upper-level support.
Cons: Weak/decent mid-level speed shear, hints of backing winds in the mid-to-upper levels, questionable storm mode, initially high LCLs.

Friday – Central Plains

NUMBER OF TORNADOES EXPECTED: 2-5 – CONFIDENCE: Normal
Tornado Hot-spot: None

Pros: Moderate to high instability, good low-level directional shear and speed shear, decent upper-level support.
Cons: Weak/decent mid-level speed shear, hints of backing winds in the mid-to-upper levels, questionable storm mode in most areas.

Saturday – Central Plains, southwestern Midwest

NUMBER OF TORNADOES EXPECTED: 3-8 – CONFIDENCE: Normal
Tornado Hot-spot: None

Pros: Moderate to high instability, decent/good low-level directional shear, decent/good speed shear, decent upper-level support.
Cons: mostly unidirectional mid-to-upper level winds, hints of backing winds in the mid-to-upper levels across the northernmost parts of the risk area.

Saturday- Eastern Ohio Valley

NUMBER OF TORNADOES EXPECTED: 0-2 – CONFIDENCE: Normal
Tornado Hot-spot: None

Pros: Low to moderate instability, decent low-level directional shear.
Cons: Unidirectional mid-to-upper level winds, weak/decent speed shear, poor/decent upper-level dynamics.

4-7 Day

Sunday – Midwest

NUMBER OF TORNADOES EXPECTED: 2-5 – CONFIDENCE: Low
Tornado Hot-spot: None

Pros: Moderate instability, decent/good low-level directional shear along the warm front, decent/good speed shear, decent upper-level support.
Cons: Poor/decent low-level directional shear south of the warm front, unidirectional mid-to-upper level winds, storm motion will generally cause storms to move from the warm sector over the warm front into the cool sector.

Monday – Central Plains

NUMBER OF TORNADOES EXPECTED: 0-3 – CONFIDENCE: Low
Tornado Hot-spot: None

Pros: Good/excellent directional shear, decent/good speed shear.
Cons: Questionable moisture, potential storm coverage issues, little to no upper-level support.

Monday – Southern High Plains

NUMBER OF TORNADOES EXPECTED: 0-2 – CONFIDENCE: Normal
Tornado Hot-spot: None

Pros: Moderate instability, good directional shear, decent/good low-level speed shear.
Cons: Poor mid-to-upper level speed shear, high LCLs, little to no upper-level support.

Tuesday – Central Plains, southern High Plains

NUMBER OF TORNADOES EXPECTED: 1-4 – CONFIDENCE: Low
Tornado Hot-spot: Central Plains

Pros: Moderate instability, good/excellent directional shear, decent/good low-level speed shear.
Cons: Weak mid-to-upper level winds, initially high LCLs, little to no upper-level support.

Wednesday – Central and southern Plains

NUMBER OF TORNADOES EXPECTED: 4-10 – CONFIDENCE: Low
Tornado Hot-spot: Central Plains

Pros: Moderate to high instability, good/excellent directional shear, decent speed shear in most of the central Plains, decent upper-level support in the central High Plains.
Cons: High LCLs in the southern Plains and the lower parts of the central High Plains, weak speed shear in the southern Plains.