An upper-level trough entering the West today will be responsible for much of the significant weather experienced throughout the western half of the country over the next few days.
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Periods of rain showers and scattered to isolated thunderstorms will continue across the Oregon and California coasts through tonight.
Heavy mountain snow will wane across the Sierra over the next 24 hours with additional accumulations of 6-12 inches of snow expected.
Rain showers and thunderstorms along an ascending warm front are forecast to impact portions of the Central Plains and Middle Mississippi Valley tonight, where some severe weather in the form of large hail may cause isolated yet serious damage.
Upstream from this warm front, a surface low will begin to organize on Friday as it spreads rain and snow showers into the Great Basin, Rockies and Great Plains.
Diurnal heating will allow for thunderstorms to develop across the Rockies on Friday afternoon.
This low pressure system will rapidly develop into a powerful and dynamic mid-latitude cyclone by Friday night.
This system will produce moderate to heavy rain across parts of the Dakotas.
Heavy snow and gusty winds will develop on the backside of this system across portions of the Northern Rockies/Plains and Front Range on Friday and continuing through Saturday.
The combination of heavy snow rates and gusty winds should produce periods of lower visibility leading to difficult travel conditions.
Significant accumulations of heavy wet snow has the potential to produce impacts to infrastructure including tree damage and power outages.
Prepare now for impactful winter weather and hazardous travel beginning Friday and persisting into Sunday.
Cold air filters into the West on the backside of this system over the next couple of days.
Thunderstorms, some severe, may develop along the strong cold front associated with the dynamic system beginning on Friday.
A Slight Risk (level 2/5) extends from South Dakota down to the Texas panhandle with an embedded Enhanced Risk (level 3/5) over portions of central Nebraska down to the Texas panhandle tomorrow.
Supercells capable of producing tornadoes and very large hail are possible, particularly where there's an enhanced risk of storms.
As the cold front progresses eastward on Saturday, thunderstorms will spread into the Upper Midwest, eastern Central Plains and central Texas where Slight Risks of severe thunderstorms capable of producing tornadoes, hail and strong wind gusts are in place.
Upper-level ridging from the Southern Plains through the Southeast will allow for above normal temperatures to spread from the Great Plains eastward over the next few days.
Critical fire weather risk continue across portions of the western Central/Southern Plains through this weekend, due to above average temperatures, dry air and windy conditions.
Very dangerous wildfire spread conditions are forecast for tomorrow along the Colorado Front Range into New Mexico tomorrow afternoon.
30-40mph sustained winds, 5-15 percent RH and abnormally warm conditions will drive this extremely critical fire weather threat.
Thunderstorm development along the dryline may also contribute to the risk of fires near the Colorado/Kansas/New Mexico/Texas border area. ■
Modified arctic air combined with a moisture-laden area of low pressure along the Gulf Coast will continue to allow for a broad area of winter weather impacts from the Lower Mississippi Valley to the Southeast today into early Saturday morning.