Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
428 AM EDT Mon Jun 25 2018
 
Day 2
Valid 12Z Tue Jun 26 2018 - 12Z Wed Jun 27 2018 

...SLIGHT RISK OVER MUCH OF THE MIDWEST INTO MISSOURI...

...Wisconsin/Illinois to Missouri and then Eastward into Ohio 
Valley...
The risk of heavy to excessive rainfall spreads eastward as a 
closed mid-level low and associated surface low pressure and front 
translates eastward. The biggest forecast problem continues to 
revolve around where any on-going convection, remnant MCV(s) or 
outflow boundaries will be at the beginning of the period...and 
how any of those factors impact eventual threat of heavy rainfall. 
While these concern are common in any Day 2 forecast, confidence 
is simply too low to make many refinements on mesoscale details 
given how much the models have been struggling to depict the 
systems evolution. Maintained the broad Slight Risk across much of 
the Midwest where low flash flood guidance is found. 

...Carolinas...
A lingering front provides a focus for tropical moisture to 
converge over the Carolinas and the possibility for coastal 
cyclogenesis near the Southeast U.S. coast.  The model signal has 
become more consistent over the possibility of cyclogenesis 
along/near the coast which results in a period of heavy rainfall 
through a combination of on-shore flow underneath increasingly 
favorable dynamics aloft before the system heads out to sea.  The 
ECMWF looked to be too strong with the system--something that was 
true with the 24/12Z runs.  The Canadian also looked to be 
over-developed.  But the signal is strong enough to warrant a 
marginal risk at this time.  

Bann

 
Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt