Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
417 AM EDT Mon Mar 23 2015
Valid 12Z Mon Mar 23 2015 - 12Z Wed Mar 25 2015
...Heavy precipitation expected across the Pacific Northwest coast...
...A winter storm is forecast to affect the Upper Midwest and Great Lakes
...Severe weather will be possible over the Ozarks on Tuesday...
The upper pattern setting up across the nation will feature a series of
low-amplitude systems with Pacific air generally being the dominant air
mass moving into the U.S. Throughout the next couple of days, the coldest
air on the map should remain north of the international border with
Canada. An active period of weather is in store for the northwestern
states as a series of impulses track through the region. Enhanced onshore
flow will drag a well-defined plume of moisture inland spreading moderate
to heavy precipitation across the Pacific Northwest. As usual, the most
concentrated activity should be confined to the favored upslope terrain
with the heaviest forecast amounts over the Coastal Ranges and Cascades.
The latest WPC winter weather desk outlook shows the heaviest snowfall
over the Oregon Cascades, Sawtooth, and Tetons where a foot of snow is
expected through Wednesday morning. All of this activity will translate
eastward spreading unsettled conditions to the northern tier.
Before the Pacific system moves toward the Northern Plains and Upper
Midwest, an area of wintry precipitation is currently advancing through
the Middle Mississippi Valley. Some of the early morning activity has
produced some lightning within the heavier snow bands showing how dynamic
this initial system is. This system should continue migrating eastward
spreading a few inches of snow to Chicago, Illinois before the impulse
aloft weakens by Monday evening across the Ohio Valley. In its wake, there
will be a brief lull before the Pacific energy reaches the Upper Midwest
by Tuesday and into Wednesday. While a majority of the system will produce
rain, enough cold air is expected to loom along the northern tier to
spread snow and ice to Minnesota eastward through the Great Lakes. 4 to 6
inches of snow may be possible along the Minnesota/Wisconsin border
accompanied by accumulating ice.
The other aspect of this system is the potential for severe weather across
the Ozarks. A strong cold front is forecast to march eastward which will
be intercepting copious amounts of Gulf moisture. The latest Storm
Prediction Center forecast suggests severe thunderstorms may be break out
on Tuesday with the activity continuing into the following day.
Elsewhere, a slow-moving frontal boundary will gradually exit the
southeastern U.S. This will bring the threat for showers and thunderstorms
with the areal coverage of convection diminishing in time as the system
weakens and moves offshore.
Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php