Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
353 AM EDT Thu Jul 20 2017

Valid 12Z Thu Jul 20 2017 - 12Z Sat Jul 22 2017

...There is a slight risk of severe thunderstorms over parts of the Lower
Great Lakes/Ohio Valley and the Northern/Central High Plains ...

...Heavy rain possible over parts of the Upper/Middle Mississippi Valley
into the Western Ohio Valley...

...Temperatures will average 10 degrees above average over parts of the
Central Plains/Middle Mississippi Valley...

A front extending from the Northeast/Northern Mid-Atlantic westward to the
Northern/Central Plains will become quasi-stationary as the eastern end of
the boundary dissipates overnight Thursday.  The remaining parts of the
boundary will linkup with the energy from another front moving
southeastward from Central Canada by Friday morning.  Showers and
thunderstorms will develop along and ahead of the front over the Great
Lakes westward into parts of the Northern/Central Plains that will move
eastward to the Northeast westward to the Middle Mississippi Valley by
Thursday night.  The showers and thunderstorms will move off the Northeast
Coast by Friday morning and continue over parts of the Ohio Valley/Middle
Mississippi Valley on Friday into Friday evening. 

Another front will develop over the Northern Intermountain Region/Northern
Rockies by Thursday evening and advance eastward to the Northern
Plains/Great Basin by Friday evening.  Showers and thunderstorms will
develop along and ahead of the boundary over parts of the Northern High
Plains/Northern Rockies by Thursday evening that will expand into the
Northern Plains overnight Thursday.  On Friday, the showers and
thunderstorms will move into parts of the Upper Mississippi Valley/Central
Plains into Friday evening. 

Meanwhile, monsoonal moisture and daytime heating along with upper-level
energy will aid in producing showers and thunderstorms over parts of the
Southwest/Great Basin eastward to the Central/Southern Rockies through
Friday evening.  The showers and thunderstorms will have the greatest
areal coverage during the late afternoon into late evening on Thursday and
Friday.  In addition, moisture rich air over the Southern
Mid-Atlantic/Southeast Coast and across the Gulf Coast State will interact
with daytime heating and upper-level impulses to produce showers and
thunderstorms along and near the coastal region through Friday evening. 
Similarly, the showers and thunderstorms will have the greatest areal
coverage during the late afternoon into late evening on Thursday and
Friday.    

Elsewhere, onshore flow off the Pacific will aid in producing rain over
parts of the Pacific Northwest through late Thursday night.


Ziegenfelder


Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php