Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
1237 PM EDT Mon Apr 16 2018


Prelim Day 1 QPF Discussion
Valid Apr 17/0000 UTC through Apr 18/0000 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1

...Mid Atlantic into the Northeast and Great Lakes...
A negatively tilted mid/upper level trough supports strong upper
level divergence, strong low-level inflow, and ample moisture
within an atmospheric river/warm conveyor belt which moves through
New England today and tonight.  CAPE should be harder and to come
by rain translates northeast, instability slowly fades, and the
moisture feed slowly winnows, though it should be enough to allow
for continued embedded heavier convective cores within the rain
shield.  Localized rates peaking in the 0.5"-0.75" in an hour
range early on will slowly fade with time.  Further northwest
under the closed mid/upper level low, will continue to see
precipitation into the Great Lakes region.  Overall, a compromise
of continuity, the 12z ARW, the 14z National Blend of Models, the
12z GFS, and the 00z ECMWF were used for the precipitation
pattern, with a strong lean towards the National Blend of Models
near the Great Lakes themselves where global guidance can
underestimate lake effect.


...West...
A trough will continue moving east into the Great Basin and
northern Rockies with associated low- to mid-level frontogenesis
supporting modest precipitation over much of the area.  WPC QPF
used a compromise of continuity, the 12z ARW, the 14z National
Blend of Models, the 12z GFS, and the 00z ECMWF were used for
precipitation amounts.

Roth