Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
801 PM EST Thu Jan 21 2021
 
Day 1
Valid 01Z Fri Jan 22 2021 - 12Z Fri Jan 22 2021 

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF 
THE LOWER MISSISSIPPI VALLEY...

...Central Louisiana through southern Mississippi and into 
southwestern Alabama...

Areas of moderate rain have developed this evening along a 
stationary front over central LA and south-central MS. Ample 
moisture is converging on this front with precipitable water 
values  of 1.6 to 1.8 inches which is about 2.5 standard 
deviations above normal and near climatological max values for 
late January. However, limiting factors include a lack of 
instability (MUCAPE around 250 J/Kg) and rather dry antecedent 
conditions (7-day rainfall totals are near zero and soil 
saturation only about 50% per the HRRR). So this will mainly be a 
beneficial rain, but should repeating activity late tonight go 
over areas that receive around 2 inches per the 23Z HRRR, there 
may be localized runoff issues. Narrowed the Marginal Risk area a 
little on the north side given regional radar trends and 12hr QPF 
overnight from recent CAMs.


Jackson

 
Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt