Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
455 PM EDT Mon May 20 2013

Valid 00Z Tue May 21 2013 - 00Z Thu May 23 2013

...Widespread severe weather and potential flooding are expected with a
cold front moving through the Nation's mid-section...

...Windy and wet conditions are in the forecast for the northwestern
corner of the country...

...Scattered showers and thunderstorms will continue over Florida and up
into the Mid-Atlantic region...

A cold front edging eastward through the Nation's mid-section will
continue to be a big weather maker during the short range period. 
Anomalous amounts of moisture surging northward out of the Gulf...combined
with strong dynamics aloft...should help fire up an organized line of
convection along/ahead of the boundary.  Flooding rains will be possible
with this system...and widespread severe weather is expected from the
Southern Plains to Upper Midwest/Upper Great Lakes.  The greatest threat
for severe storms will be from northeast Texas into the Lower/Middle
Mississippi Valley...but please refer to the SPC for the latest
information on severe weather.  Farther north...moisture getting wrapped
around the anchoring surface low slowly crossing the Upper Mississippi
Valley and moisture overrunning an east-west oriented frontal boundary
stretched through the Great Lakes and southern New England should fuel
some light to moderate rains with embedded thunderstorms for the next few
days. 

A vigorous upper vortex settling in over the Pacific Northwest will slowly
push a cold front inland over the Western U.S..  Moderate Pacific moisture
associated with this system will allow for scattered showers across the
northwestern corner of the country...and strong winds with the passing
cold front should really help enhance amounts along the favored slopes of
the terrain.  Conditions will be noticeably cooler behind the front...and
falling temperatures should lead to snow showers over the Washing/Oregon
Cascades by Wednesday morning.

In the East...weak energy aloft should keep conditions ripe for scattered
showers and thunderstorms over Florida and up into the Mid-Atlantic states.

Gerhardt

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