Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
223 AM EDT Thu Jun 20 2013

Valid 12Z Thu Jun 20 2013 - 12Z Sat Jun 22 2013

...Deep cyclone will bring unseasonably wet conditions from the Great
Basin to the Northern Plains and Great Lakes along with the possibility of
severe weather...

...Showers and thunderstorms will continue across the Southeast and
southern Atlantic states near a dying frontal zone...

A deep cyclone across the Pacific Northwest will continue to bring
unsettled conditions across the northern Great Basin for the next couple
days as it slowly progresses eastward towards the Northern Plains. The
combination of cold air combined with available moisture and daytime
heating will trigger showers and thunderstorms along the mountains which
then spread eastward into lower elevations of Montana and the Dakotas into
the Great Lakes.  In the higher terrain, it should be cold enough for the
precipitation to fall as snow in Montana and Idaho.  The heaviest
rainfall, along with the threat of severe weather, will spread through the
northern Plains towards the Great Lakes over the next couple days per the
latest thinking from the Storm Prediction Center where vertical wind shear
is sufficient to organize thunderstorms.    

The Gulf Coast region along with southeastern Atlantic states will see a
dying polar front linger over the next couple days.  Southerly winds will
bestow this region with copious amounts of Gulf moisture, aiding and
abetting scattered thunderstorms and showers.  A surface low will remain
adjacent to the Carolina coast and allow some of the heavier rainfall
concentrate near and to their east. 

Roth/Fanning


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