Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
317 AM EDT Sat May 18 2013

Valid 12Z Sat May 18 2013 - 12Z Mon May 20 2013

***Stormy weather for the Northern Plains and Upper Midwest***

***Warm and humid for the southern tier states***

***Showers and scattered storms for the Northern Rockies***

An active weather pattern is forecast to continue over the Dakotas
and into Minnesota and the western Great Lakes region as a strong
spring storm system moves slowly eastward across the Great Plains.
 Multiple rounds of organized thunderstorm activity are likely
through Sunday, and numerous strong and severe thunderstorms are
expected from northern Texas northward to the Upper Midwest.  Much
of this activity should fire up along and east of a dryline and
slowly approaching cold front, in an environment of high
instability and wind shear.

Over the eastern U.S., a stalled frontal boundary situated from
North Carolina westward to Illinois will serve as the delineation
between very warm temperatures over the south central states and
Southeast, and 60s and 70s to the north.  Moisture convergence
along this boundary will result in periods of rain for the
southeastern quadrant of the country, coupled with support from a
mid-level shortwave passing slowly overhead.  A warming trend is
expected to commence by Monday for much of the Ohio Valley and
Mid-Atlantic region as the front lifts northward and washes out.

Elsewhere, scattered showers and storms remain in the forecast for
much of
the Inter-Mountain West and extending into the Pacific Northwest
for
the weekend.  A large scale trough in the atmosphere will allow for
enough instability for convection over this region, and some
onshore flow
from the Pacific will generate some showers for the coastal areas
of
Oregon and Washington state.  Hot and dry weather is expected for
the Desert Southwest, along with gusty winds.


Hamrick


Graphics available at www.wpc.ncep.noaa.gov