Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
325 AM EDT Wed May 16 2018


Prelim Day 1 QPF Discussion
Valid May 16/1200 UTC thru May 17/1200 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1...

...Mid-Atlantic/Central and Southern Appalachians...

Southerly flow along the western periphery of the Bermuda high and
ahead of a weakening trough lifting out of the eastern Gulf of
Mexico will continue to channel deep moisture northward through
the region.  This moisture along with weak mid-level energy
lifting out ahead of the trough is expected to support some
orographically enhanced rainfall totals along the eastern slopes
of the southern to central Appalachians.  Guidance shows a fairly
good signal for south to north oriented training convection
producing some locally heavy amounts along the favored terrain
from far northeast Georgia and western North Carolina, to at least
as far north as southwest Virginia later today.  As energy
continues to lift north, weak surface to low level wave
development will enhance moisture convergence, which along with
some support from the right-entrance region of the upper jet, may
generate another round of heavy rains this afternoon and evening
from central and eastern Virginia to along a stationary boundary
draped across the northern Mid-Atlantic. 

...Southeast...

Onshore flow and low level convergence east of the surface wave
associated with the previously noted upper trough is expected to
support some moderate to heavy amounts across the eastern Florida
panhandle into southern Georgia today.  Heavy rainfall threat is
expected to wane by early Thu as the low weakens and lifts further
north.

...Pacific Northwest/Northern California/Great Basin/Northern
Rockies...

A weak mid-upper level low is forecast to drift northeast from the
northern Great Basin into the northern Rockies this today. 
Guidance shows PWS increasing to around an inch (over 2 standard
deviations above normal) near the center.  This moisture along
with daytime heating is expected to support scattered storms with
the potential for locally heavy amounts from central Oregon
northeastward into western Montana.  Meanwhile, an upstream low is
forecast to move into northern California, fostering additional
precipitation further south and west across northern California
into northern Nevada late Wed into early Thu.

Pereira