Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
253 PM EDT Thu Apr 19 2018


Prelim Day 1 QPF Discussion
Valid Apr 20/0000 UTC thru Apr 21/0000 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1

...Great Basin into the central to southern Rockies

The strong closed low moving into the western Great Basin early
this afternoon will be moving steadily eastward through the Great
Basin this evening/overnight and into the central to southern
Rockies during the day on Friday.  PW values ahead of this closed
low across the Great Basin will not be anomalous with values near
or slightly above the mean.  This should be a limiting factor for
widespread heavy precip totals with model consensus of .10-.25"
areal average totals across the Great Basin and into the southern
to central Rockies.  Locally heavier totals likely in the favored
upslope regions of the Wasatch of UT and into the central to
southern Rockies from south central WY---through CO and into north
central AZ.  Heavy early spring snows likely  through the southern
Wasatch and through the southern to central Rockies.  See the
latest QPFHSD for additional winter weather information across
this region.

...Southern to Central High Plains...

PW values expected to become more anomalous day 1 to the east of
the Rockies into the central to southern high plains where the low
level south southeasterly flow is expected to strengthen
significantly during Friday ahead of the upstream closed low. 
Increasing upper difluence ahead of the Great Basin/Rockies closed
low in the increasingly anomalous PW axis will support increasing
precip coverage Friday through large portions of the central to
southern high plains.  .25 to .50"+ areal average amounts possible
with locally heavier totals where the north to south oriented
precip bands possible train for a short period of time.

...Western to northern NY state into northern New England...

Surface low pressure moving to the south of New England this
afternoon will be pushing into the Canadian Maritimes tonight into
Friday with the western peripheries of the associated comma head
precip area possibly affecting far eastern Maine early in the day
1 period.  In the wake of this low---deep layered cold cyclonic
flow will persist day 1 from the eastern Great Lakes into New
England.  This will support scattered snow showers for portions of
western to northern NY state and into northern New England.  Light
to locally moderate precip/snowfall totals possible across these
areas.  See the latest QPFHSD for additional winter weather
information across this region.


Oravec