Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
302 PM EDT Sat Jun 02 2018


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


...Eastern U.S....

A Moderate Risk for flash flooding remains in place across
portions of Maryland, Delaware and the Virginas as a shortwave
trough drifting east from the Virginias interacts with a deep
moisture pool -- supporting heavy rains across the northern Mid
Altantic, including areas that were impacted by heavy rains
earlier in the week.  Guidance shows the aforementioned trough
drifting slowly east from the Virginias to the coast over the next
24-36 hours, with deep moisture (PWs around 2 inches) pooling near
the associated low level circulation.  Expanding coverage of
moderate to heavy rainfall rates is expected to continue as
instability increases this afternoon.  Weak flow aloft is expected
to support slow moving cells with high RH through the mid levels
and tall 'skinny' CAPE supporting efficient rainfall processes. 
Threat for heavy rainfall rates is expected to peak during the
afternoon into the evening hours, with a downward trend as
instability decreases overnight.  The return of daytime heating is
expected to support an upward trend in rainfall rates closer the
Mid Atlantic coast tomorrow afternoon.  WPC QPF utilized the HREF
Mean as a starting point through much of the period, with moderate
to heavy amounts from eastern West Virginia to the mid Atlantic
coast over the 24-30 hours. 

...Upper Midwest/Great Lakes/Ohio Valley...

A negatively-tilted upper trough will continue to push showers and
storms eastward across the upper Midwest and Great Lakes region
this afternoon/evening.  The progressive nature of the system
along with modest instability should limit the potential for heavy
amounts, with generally light to moderate accumulations expected
as the system moves across the upper Great Lakes region tonight. 
As the system pushes further east on Sunday, increasing
instability supported by daytime heating is expected to raise the
threat for locally heavy rains across the Ohio valley Sunday
afternoon-evening.  The HREF Mean was utilized as a starting point
with a slight shift toward the more progressive members, including
the HRW-NMMB. 


...Mid and Lower Mississippi Valley...

Divergent flow along of the base of the aforementioned trough
along with deepening moisture ahead of the associated cold front
will continue to support developing convection across from the mid
Mississippi valley and Ozark region southward into the lower
Mississippi valley and ArkLaTex region.    Deep moisture and
instability are expected to support locally heavy amounts with the
hi-res models continuing to show a good signal for heavier amounts
centered across Arkansas this evening.   However these storms
should be fairly progressive in nature, limiting the threat for
more widespread heavy amounts.  The HREF Mean was utilized as a
starting point, with a slight shift toward the more progressive
members.


...Southern Rockies/High Plains...

Guidance shows a good signal for developing precipitation, with
locally heavy amounts possible across portions of the region
tomorrow.  Increasing southeasterly low level inflow ahead of a
shortwave trough moving across the Four Corners region is expected
to support developing showers and storms during the afternoon and
evening hours tomorrow, with some signal for moderate to locally
heavy amounts across the southern Colorado and the New Mexico
ranges.

Pereira