Mesoscale Analysis in Des Moines

GOES-16 upper-level water vapor imagery reveals a closed upper low advancing east across southern Nebraska early this afternoon.

Visible imagery shows low clouds across much of the CWA, with cu beginning to develop across the far southern portions in the warm sector of the storm system

Morning GOES-16 Derived Motion Winds revealed a 110+ knot 300 mb southwest to northeast oriented jet core across Iowa. This agrees with the GFS depiction of the jet in that area, which has that jet exiting and a jet entrance region poking into southern Iowa later today. Winds in the 750 mb to 850 mb layer are generally 15-25 knots from the south/southeast, with slightly stronger winds advancing towards our south implying increasing LL WAA.

The default LAP products have very little data given low cloud cover over the region.  However, the all-sky LAP products have a lot of cloudy sky retrieval pixels, filling in those gaps, in addition to some clear sky pixels moving north into the CWA. From 1730 to 1900, all sky LAP CAPE has increased from 500 to 700 j/kg, and TPW has increased from around 1.32" to 1.36". CAPE over 1000 j/kg reside just south of our warning area. These trends imply the atmosphere is becoming more favorable for the development of severe storms.

 The LAP Layer PW product, comprised mostly of clear sky and cloudy sky retrievals across the domain, shows some significant features. Clockwise from top left PW sigma layers: sfc - 0.9, 0.9 - 0.7, TPW, 0.7 - 0.3. The two lower layers show fairly high levels of moisture, while the upper level reveals a nose of dryer air advancing toward the CWA. This trend would imply increasing convective instability as we advance through the afternoon.

- Bucky