Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
248 PM EDT Wed May 30 2018


Prelim Day 1 QPF Discussion
Valid May 31/0000 UTC thru Jun 01/0000 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1

...Upper Great Lakes and Midwest...

Alberto is expected to continue tracking progressively to the
north, producing locally heavy amounts near the center as it
tracks from Indiana across Lower Michigan this evening overnight,
with additional moderate to locally heavy amounts continuing to
develop further west across Wisconsin and Minnesota as moisture
streaming out ahead of the center interacts with an approaching
negatively-tilted upper trough.  WPC QPF reflects consensus of the
12z hi-res models, which continued to maintain a good signal for
1-2 inch amounts, with locally heavier amounts from northern
Indiana into western Lower Michigan this afternoon and evening.

...Central Plains to the lower Ohio and Tennessee valleys...

While showing some differences in the details, the 12z hi-res
models runs continue to show a good signal for developing moderate
to heavy rains this evening-overnight as a shortwave trough moving
out of the central Rockies interacts with moisture pooling along a
stationary boundary extending along the Kansas-Oklahoma border. 
Convection is expected to wane Thu morning as the lead shortwave
moves across the mid Mississippi valley before redeveloping
further downstream across the lower Ohio and Tennessee valleys,
with upstream energy possibly spurring some additional
redevelopment across the mid Mississippi valley later in the day
as well.  WPC QPF gave significant weighting to the HREF Mean
through most of the period.

...Lower Great Lakes / Upper Ohio valley / Central Appalachians /
Mid Atlantic...

As the aforementioned trough over the upper Midwest translates
eastward this period, a northwest-southeast oriented boundary and
the leading edge of a very moist airmass extending from the
Mid-Atlantic from the Great Lakes is expected to move north this
period.  Guidance shows deep moisture surging north along the
central Appalachians and Mid-Atlantic as the low level flow backs
ahead of the approaching trough.  This moisture along with
afternoon heating and the larger scale forcing afforded by the
approaching trough is expected to support and increasing threat
for moderate to locally heavy amounts both along the higher
terrain and ahead of a cold front pushing across the lower Great
Lakes late Fri.  WPC QPF gave significant weighting to the HREF
Mean through most of the period.

...Northern Intermountain West / Northern Rockies and High
Plains...

As an upper level trough continues to amplify across the
Northwest, a developing upper jet couplet along with ample
moisture along the low to mid level boundary there remains a good
signal for widespread light to locally heavier amounts across the
region.  WPC QPF reflects a consensus of the hi-res models here as
well.

Pereira