Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
231 PM EDT Tue Apr 10 2018


Prelim Day 1 QPF Discussion
Valid Apr 11/0000 UTC thru Apr 12/0000 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1

...Northern California---coastal Pacific Northwest...

The upper trof over the northeast Pacific will be amplifying day
1---helping to propel a strong frontal boundary toward the west
coast Tuesday night/early Wednesday.  Strengthening south
southwesterly low level flow and increasing pw values ahead of
this front will support organized frontal/pre-frontal
precipitation pushing inland Wednesday across the Pacific
Northwest from the coast ranges into the Cascades---southward into
northern California.  The best upslope component to the south
southwest low level flow will be over northwest California...far
southwest Oregon and into the Olympic Range of Washington State. 
Across these areas heavy precip totals in the 1-2" range
likely...with lighter totals elsewhere from the Cascades west to
the coast ranges where the low level flow will not have as
significant upslope component.  Overall---very good model
agreement with precip amounts and distributions--leading to a high
confidence forecast this period.

...Northern Rockies into the Northern Plains...

Ahead of the strong front approaching the west coast day 1---a
lead area of height falls will be pushing through the Northern
Rockies and into the Northern Plains.  Above average pw values
will support moderate to locally heavy precip totals over the
Northern Rockies from northwest WY into far eastern ID---central
to northern ID...northeast Oregon into southwest MT.  To the east
of the Rockies---isentropic lift will strengthen along and north
of the northwest to southeast oriented frontal boundary across the
Northern Plains.  This will support increasing overrunning precip
Wednesday from central Montana---eastward across ND and northern
portions of SD---with areal average .10-.25"+ amounts possible.

...Upper Great Lakes into the eastern Great Lakes...

Northern stream shortwave pushing quickly southeast from
Saskatchewan into the Upper Great Lakes tonight and toward the
eastern Great Lakes by Wednesday evening will push an associated
front southeast across these areas.  The fast movement and lack of
moisture will keep any precip on the light side.

...Florida...

The stationary front across north Florida this afternoon will be
pushing southward tonight into early Wednesday across central to
south Florida.  The model consensus is for lessening organization
of convection ahead of this front as the current favorable right
entrance region jet dynamics in the vicinity of this front weaken.
 This weakening dynamics and expected progression should keep any
precip on the light to moderate side.

Oravec