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/basicwx/basicwx_wbg.php