Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
429 AM EDT Mon Apr 21 2014
Valid 12Z Mon Apr 21 2014 - 12Z Wed Apr 23 2014
...Severe weather will be possible today from Central to Northeast Texas...
...Heavy snow is expected across the Oregon Cascades and over the Tetons...
A definitive pattern change will be underway as a strong upper trof sets
up across the Western U.S. by Tuesday. This will lead to quite a
sinusoidal pattern with unsettled weather across the Western/Eastern U.S.
while ridging across the middle of the nation keeps conditions more
To begin the forecast period, a slow moving cold front was seen moving
toward the Middle Mississippi Valley and Central Plains. Mid-level energy
associated with a weakening trof should help ignite showers and
thunderstorms ahead of the advancing cold front. Much of the convection
should spawn along a north-south oriented trof across Texas/Oklahoma where
low-level convergence will be maximized. Sufficient daytime heating is
expected leading to large amounts of instability in the atmosphere. The
Storm Prediction Center outlook suggests a threat for severe thunderstorm
development anywhere from Central Texas toward the Arkansas/Louisiana
border through tonight.
As an upper trof in the northern stream begins to dig through the Upper
Great Lakes early Tuesday, the cold front is forecast to accelerate
reaching the Eastern Seaboard by late Tuesday night. Showers and
thunderstorms will break out along and ahead of the boundary with any
wintry precipitation remaining north of the U.S./Canadian border. Ahead of
this advancing cold front the temperatures should be quite mild with highs
well into the 70s along the I-95 corridor on Tuesday.
The change in the pattern bringing the large upper trof to the West will
allow cooler and wetter conditions to affect the region. The combination
of onshore flow with frontal and orographic lift will help spread an
expansive region of precipitation to the Western U.S. Snow levels should
fall sufficiently to bring decent accumulations to the Oregon Cascades and
across the Tetons. Both of these mountain ranges can expect snow totals
through early Wednesday of 6 to 10 inches while localized heavier amounts
will be possible. The other aspect of this system will be dry and gusty
winds expected as the pressure gradient tightens across the Intermountain
West. An enhanced risk for wildfire development is in place for the Desert
Southwest on Tuesday with locations further east being affected by
Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php