Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
221 PM EDT Mon Apr 30 2018


Prelim Day 1 QPF Discussion
Valid May 01/0000 UTC thru May 02/0000 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1


...Northeast...

The strong New England mid to upper level closed low  will be
pulling offshore tonight and passing south of Nova Scotia during
Tuesday.  The precipitation effects from this system will continue
to diminish across the northeast tonight with only additional
light precip totals expected after 0000 UTC Tuesday

...Northern Rockies into the Northern Plains--Upper MS Valley...

A lead area of height falls will be ejecting northeastward out of
the mean Rockies/Great Basin upper trof---pushing across portions
of the Northern Plains into the Upper MS Valley. This will
accentuate large scale lift from the upslope region of the
Northern Rockies across southwest MT into northwest
WY---northeastward along and north of the surface front lying
northeastward into the Upper MS Valley---southwest to central
Ontario.  Model consensus is for moderate to isolated heavy totals
across these areas--with heavy spring snows possible across
northwest to north central WY.  See the latest QPFHSD for
additional winter weather information.

...Central Plains...

Convection may enhance this evening across portions of the Central
Plains in the vicinity of central to eastern Nebraska in a region
of strong frontal convergence/well defined upper difluence ahead
of the above mentioned northeastward moving height falls.  There
may be a brief period of training of cells between 0000-0600 UTC
over northeast Nebraska--supporting locally heavy rainfall
potential across this area. 

...Central to Southern High Plains...

Farther to the south along the dry line stretching across the
Central to Southern High Plains---scattered convection possible
early in the period in the broadly difluent upper flow downstream
of the amplifying Southwest upper trof.  Low confidence on qpf
details here---with light areal average amounts depicted---with
isolated moderate to heavy totals likely.

...Sierra---southern California into the Southern Great Basin...

In the wake of the lead area of height falls ejecting out of the
mean western trof----additional  upstream height falls will be
dropping south and southeastward---re-amplifying the upper low
over southern California Tuesday.  A broad region of scattered
precipitation likely downstream of this amplifying upper low from
the Sierra--into southern California and the southern Great Basin.
 The day 1 qpf did not deviate from the model consensus of light
to moderate areal average totals across these regions.

Oravec