Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
457 PM EDT Wed Jun 19 2013
Valid 00Z Thu Jun 20 2013 - 00Z Sat Jun 22 2013
...Deep upper level low will bring unseasonably wet conditions from the
Great Basin to the Northern Plains...
...Showers and thunderstorms will continue across the Southeast and
southern Atlantic states...
A deep upper level low has moved inland from the Pacific Northwest and
continues to bring unsettled conditions across the northern Great Basin.
This upper level low is slowly progressing eastward towards the Northern
Plains; in fact, it does not exit the Northern Rockies until after the
short range period. The placement of already unstable air combined with
enough lift and anomalous supply of moisture, showers and thunderstorms
will be triggered along the mountains and eventually spread eastward into
Montana and the Dakotas by early Thursday morning. The heaviest rainfall,
along with the threat of severe weather, will concentrate along the
U.S.-Canada border in Idaho and Montana. As the surface frontal boundary
advances into the Northern Plains by Thursday morning, most of the
convection will taper off across the Northern Rockies and surrounding
regions. However, due to the slow moving nature of the upper level low,
showers with periods of moderate rainfall will linger across the Pacific
Northwest and portions of the Great Basin through Friday.
The Gulf Coast region along with southeastern Atlantic states will
continue with its rounds of showers and thunderstorms. A cold front is
slowly dipping southward across the Southeast. This boundary will stall
out and remain along the Gulf Coast and off the coast of the Carolinas
through Friday evening. Southerly winds will bestow this region with
copious amounts of warm Gulf moisture and the aforementioned boundary will
provide focus for scattered thunderstorms and showers. A surface low will
remain adjacent to the Carolina coast and allow some of the heavier
activity to concentrate around that region. By Thursday night and into
Friday morning, the majority of the convection will subside. With that
said, don't expect all of the convection to subside as the boundary will
stick around for the beginning of the weekend.
Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php