sbnwx85

Pretty good bounded weak echo region now.

WPC expanded the excessive rainfall moderate risk into southeast Iowa and basically the northern half of IL. Good write-up below. Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1223 PM EDT Thu May 14 2020 Day 1 Valid 12Z Thu May 14 2020 - 12Z Fri May 15 2020 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FROM CHICAGOLAND TO NORTHERN MISSOURI... ...Moderate Risk Area... A northern stream system skirting across the Midwest, with a developing upper level jet streak during convective maximum, 21-06Z, will interact moderate instability along a slow moving frontal zone, to produce a multi-hour heavy rain event this afternoon/evening. Synoptic deep layer forcing becomes maximized along a zone from northern Missouri and southern Iowa toward northern Illinois and southwest lower Michigan. Many model QPFs align here, such as the NAM, NAM Nest, WRF-NMMB, and recent HRRR runs. The WRF-ARW is a bit of an outlier in how much southward propagation it produces, ending up considerably south of the rest... but the WRF-ARW2 perhaps represents a more resonable southward adjustment that may occur as a result of outflow from early-morning convection. Thus, there are still some placement challenges, especially toward Chicago where the lake breeze may also act to inhibit the northward rebound of instability later on today. Northern Illinois is, however, more hydrologically vulnerable - having received 0.50 to 1.50 inches of rain this morning. Parts of the Davenport area also received some local amounts up to two inches. Aside from the early-day event, much of the region has been running below normal on precipitation recently, with fairly dry soils. Thus a second challenge is whether the evening event is likely to produce impacts consistent with the Moderate Risk category. But there do appear to be enough overlapping factors to support Moderate Risk. Inflow of unstable low level air near and atop the effective surface front and other outflow boundaries will increase to 30-40 knots late this afternoon, with deep layer flow becoming quite parallel to the boundaries. We could see a several hour period of training, causing what is otherwise an average combination of PW and CAPE to produce a few spots of higher-end rainfall totals. The NMMB even signals a small 3-inch / 1-hour amount in Illinois, and the NAM Nest signals local 3 to 4 inch in 3 hour totals, indicative of what could occur. This may lead to numerous flash floods and isolated higher-end impacts. Thanks to the WFOs and RFCs for helping shape the updated Moderate Risk contour.