A highly amplified upper-level trough continues to swing eastward across the Intermountain West, triggering multitudinous weather hazards for areas west of the Mississippi River.
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Colder air associated with the upper trough continues to overspread the western U.S.
today in the wake of a potent, eastward-progressing cold front.
As snow across the Sierra Nevada and northern Rockies gradually tapers off today, a low-pressure system is forecast to develop over the central High Plains.
Snow associated with this system will overspread much of the central Rockies in addition to increasingly gusty winds.
Snow will spread into the nearby northern to central High Plains today and Friday, with strong and gusty winds from the north adding to the wintry feel in these areas.
A drastic change from the warm and dry weather in recent days.
Conditions will improve late tonight as the system moves eastward, leading to a pleasant, albeit cold, start to the weekend for central and western portions of the Intermountain West.
As the strong storm system ejects eastward into the central and southern Plains today, hazardous weather will occur along and ahead of the progressing cold front and dry line as warm, moist air surging northward from the Gulf clashes with the cooler, drier air.
As a result, showers and potentially severe thunderstorms may develop across the central Plains before the threat shifts further east on Friday into eastern Texas and Oklahoma.
As a result, the Storm Prediction Center has placed portions of the region under a Slight Risk of Severe Thunderstorms today and an Enhanced Risk tomorrow, due to the potential for damaging winds, hail, and isolated tornadoes.
In addition to the severe threat, anomalously moist air in conjunction with developing showers and thunderstorms along the slow-moving cold front may lead to prolonged moderate to, at times, heavy rainfall rates and isolated instances of flash flooding across the Mississippi Valley and central Plains on Friday.
Therefore, a Slight Risk of Excessive Rainfall has been issued for the Ark-La-Tex region.
By early on Saturday, the intensifying low-pressure system is forecast to move toward the upper Midwest with a band of showers and thunderstorms extending down the Mississippi Valley along the cold front as well as another band of enhanced rainfall with possibly strong thunderstorms extending up across the upper Midwest ahead of a warm front.
Colder air wrapping behind the intensifying low could change the rain to snow across the western portion of the upper Midwest.
The cold front is forecast to become more diffuse Saturday afternoon as it progresses into the Ohio Valley and Southeast, with the potential for strong thunderstorms and moderate to heavy rainfall rates decreasing as the frontal convergence weakens.
Further east, ahead of the cold front, warmer-than-average temperatures will persist across the eastern two-thirds of the country under the influence of an expansive high-pressure system centered over the Northeast.
Widespread above-average temperatures are forecast today across the northern Plains and Midwest, with temperatures in the mid-to-upper 70s (15-25 degrees above average) due to a dry, southerly flow.
As the high pressure continues pushing east the warm air will shift eastward into the Southeast and Northeast this weekend, leading to delightful weather for outdoor activities.
The next storm system will make its way onshore in the Pacific Northwest this evening, with mountain snow and lower-elevation rain rapidly overspreading the area.
Rainfall amounts of 2-6" are possible across the region, which, in unison with the recent rainfall, may lead to isolated instances of flash flooding, especially in areas with elevation.
Precipitation will spread inland on Friday and Saturday as the system emerges from the northern Rockies and intensifies, leading to increasingly gusty winds and infiltrating cooler air in its wake. ■