Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
433 AM EDT Wed Jun 06 2018


...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN PORTIONS OF
THE NORTHERN HIGH PLAINS AND CENTRAL PLAINS TO UPPER MIDWEST...

...Northern High Plains...
Shortwave energy riding over the central CONUS upper ridge from a
west coast trough will lift Gulf moisture-laden air from western
SD to eastern MT Thursday. PW of 1.25 inches is two standard
deviations above normal and a ribbon of ample instability streams
across the area on 20-30kt southeasterly flow. The Marginal Risk
was expanded over MT as FFG is rather low there (about 1.5 inches
in 6hr). The 00Z GFS/NAM was preferred for QPF.

...Central Plains/Upper Midwest...
Additional weak shortwave energy riding over the broad mid to
upper level ridge axis over the High Plains will cross portions of
the Central Plains and Upper Midwest Thursday. A broad swath of
1.5 to 1.75 inch PW rides a low level jet below the mid-level
forcing over KS/NE/IA. The PW anomaly over this area is two
standard deviations above normal. Two camps for QPF exist for day
2 -- the 00Z ECMWF/UKMET which is along the SD/NE border and the
00Z GFS/NAM which is centered over IA. The 00Z GFS/NAM was
preferred for QPF based on the main trajectory of moisture and
instability.  A Marginal Risk was expanded for KS through IA and
into WI/IL where 2-3 inch areal average is possible. This outlook
area should contract as forecast confidence increases through time.

Jackson