Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
302 AM EST Thu Feb 22 2018
Valid 12Z Thu Feb 22 2018 - 12Z Sat Feb 24 2018
...Cold and unsettled weather is expected over the West including some
heavy snow over the Rockies...
...Additional heavy rainfall and widespread concerns for flooding will
persist across parts of the southern Plains, lower Mississippi Valley and
the Ohio Valley...
...Warm temperatures are generally expected to continue across a large
portion of the East...
Much of the West will remain in a cold, active wet pattern through the end
of the week thanks to a series of impulses that will drop south and
reinforce the broad upper level trough of low pressure. Snow will spread
across the Pacific Northwest, Great Basin and to the Rockies. Snow will be
heavy at times across the higher terrain in northern California, southern
Idaho, Nevada, Utah and for portions of the Central Rockies. The cold
airmass in place over the region will keep afternoon highs generally 10 to
20 degrees cooler than usual for late February.
The waves of energy will exit the Front Range and track across the Plains
where a quasi-stationary frontal boundary extends from the Lower
Mississippi Valley to the Ohio/Tennessee Valley and Mid-Atlantic. Multiple
rounds of heavy rain is forecast as warm Gulf moisture advects northward
along the boundary. This rainfall is expected to occur over a broad area
already saturated from prior days of excessive rain. A slight to moderate
risk for flash flooding main stem river flooding will persist through the
end of the week. In the cold sector, scattered to widespread snow will be
possible for portions of the Plains, Midwest and Upper Mississippi Valley
- numerous Winter Weather Advisories are in effect for these areas.
Much of the East Coast lies within the warm sector of this system and will
continue to have temperatures topping off in the 70s and 80s, whereas, the
central CONUS will be below freezing as much as 10 to 20 degrees below
Regarding the threat of winter weather, there will be the approach of a
wave of low pressure from the Tennessee Valley on Thursday that will
actually interact with sufficient cold air over parts of the upper Ohio
Valley, far northern Mid-Atlantic and interior of the Northeast for a
stripe of some accumulating snow and ice. Meanwhile, there will also be a
swath of accumulating snow and ice across portions of especially the
central Plains, Midwest and Great Lakes for Thursday and Friday as low
pressure rides northeast up across the region.
Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php