Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
154 PM EST Fri Mar 02 2018


Prelim Day 1 QPF Discussion
Valid Mar 03/0000 UTC thru Mar 04/0000 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1

...Western U.S...

A closed mid/upper level low will remain nearly stationary over
the pacific northwest through Saturday. Waves rotating around the
southern periphery of this low, combined with easterly onshore
upslope flow and persistent right entrance region jet
dynamics...will all support a continuation of rain and snow over
much of the west coast into the central Great Basin. Overall not
the strongest moisture transport or PWATs...so precipitation rates
will not be all that impressive. With that said, still looking at
a long duration of upslope flow and favored synoptics, especially
over the Sierras. Thus QPF through the day 1 period should end up
in the 1-2" range over much of the Sierras. Lighter amounts can be
expected elsewhere...with localized 1" amounts in the southern
California Transverse Ranges where orographic factors will also be
maximized.

Models were in pretty good agreement, with WPC thus utilizing a
blend of the latest HREF and global model means, with greater
weighting to the higher res guidance to capture orographic
effects.

...Northeast...

Precipitation will be winding down after 0z across the northeast
as the area of low pressure moves off to the east. Additional QPF
after 0z should generally be within the 0.5"-1" range over
southeast MA. Generally followed close to a blend of the 12z HREF
and recent HRRR runs to derive QPF for this area into the evening
hours.

Chenard