Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
434 PM EDT Mon Aug 20 2018
 
Day 3
Valid 12Z Wed Aug 22 2018 - 12Z Thu Aug 23 2018 

...MARGINAL RISK FOR EXCESSIVE OVER NEW ENGLAND...CENTRAL 
PLAINS...AND THE SOUTHWESTERN U.S....

...Northern New England...
Maintained a Marginal Risk over northern New England as moist flow 
from the Atlantic Ocean gets drawn inland by a developing low 
pressure moving into Canada from the eastern Great Lakes 
Wednesday. Plenty of confluent flow at the low levels being drawn 
into the hilly terrain of northern New England is expected. 
Instability looks quite limited per the 12Z GFS/ECMWF, so the 
Marginal Risk was maintained for now.

...Southwest U.S....
Moisture being drawn northward across AZ shifts east a bit 
centering on the four corners. Ample moisture (generally 1.5 
standard deviations above normal) and instability will allow heavy 
thunderstorms. However, weak forcing suggests widely scattered 
heavy rain with the Marginal Risk maintained for now.

...Central Plains...
Convection forming over the Central/Southern Plains early 
Wednesday morning will taper off at the time of convective minimum 
over parts of Kansas or Oklahoma, followed by an additional round 
of convection forming during the latter portion of Wednesday and 
the early-hours of Thursday morning as 850 mb winds ramp up in a 
low-level jet of 25 to 35 knots. 12Z guidance converged a bit on a 
QPF max just north of the KS/OK border which has been fairly wet 
over the past week. Maintained a Marginal Risk. 

Jackson

 
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt