STORMS SOUTH, SNOW NORTH, AN UPDATE...

March 19, 2020

As of mid-afternoon a conditional threat of severe weather remains in effect for my southern counties. The window looks small and confined to the area south of I-80, especially HWY 34 south. The Storm Prediction Center still has an enhanced risk of severe weather for much of my area in Iowa.

 I believe the enhanced risk is probably too far north and not likely to verify beyond I-80 but that remains to be seen (it's possible it could be cut back in SPC's next outlook due in before 3pm). The big problem I see is cloud cover and the northward extent of the warm front. This is what temperatures are projected to look like at 5:00pm.

The really good instability remains in the warm sector over southern Iowa, Missouri, and WC Illinois as you can see in the projected CAPE values towards evening.

The significant tornado parameters are highest near and south of HWY 34 and maximized in SC Iowa and NC MIssouri. I do expect a tornado watch will be issued for that area later this afternoon.

Here's the supercell composite index showing where the best chances of rotating storms will be found

In summation, severe weather is still a threat late this afternoon and early evening over far southern Iowa and northern Missouri. A tornado risk remains with any discrete cells but that is likely to diminish quickly towards evening with the primary concerns becoming strong winds and hail through early evening. If you are near or south of HWY 34, especially in Iowa keep and eye to the sky later this afternoon.

 

The other issue is the potential for rain in my northern counties to transition to snow shortly after midnight. There is a chance of 1 (to perhaps 2") of snow near and north of HWY 20 with a dusting possible as far south as Cedar Rapids. Temperatures will fall rapidly later tonight and reach the low to mid 20s by morning. That means a flash freeze will take place and some travel issues are likely around HWY 20 late tonight and early Friday before the snow comes to an end. Here's what models are currently showing for snow totals.

 

The 3k NAM

The GFS 

 The 12k NAM

 The EURO

 That's where things currently stand. Roll weather...TS

 

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© 2019 Terry Swails