National Weather Service United States Department of Commerce

Significant Snowfall for Washington Cascades and Northern Rocky Mountains

A cold front will linger for several days from the Pacific Northwest to portions of the northern Plains early this week. Cold temperatures and copious moisture will combine to produce several feet of snow into the mountain passes, with up to 4 feet of snow down to 4000 feet in the northern Rockies. Travel through mountain passes will be very difficult. Read More >

A dense fog advisory is in effect until 11 AM. Slow down and use your low-beam headlights if you encounter reduced visibilities.
There will be a significant increase in rain chances as an upper low moves northeast across West-Central Texas on Tuesday. The best rain chances will occur across the southeastern half of the region where rain is almost a guarantee, with slightly lower chances farther northwest. Severe weather is unlikely, though a few storms may become strong and produce small hail and frequent lightning. Precipitation will move east of the region late Tuesday night.
Forecast models are showing cold air arriving next week around December 22nd and 23rd (on average). What we do not know for sure yet is exactly when the cold air arrives, how cold temperatures will be, and if there will be any precipitation and what kind. We will be providing updates when/as we acquire better confidence in the late week forecast.

 
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Automatically generated image showing areas of the significant tornado parameter.

 

Thumbnail of an automatically generated image showing areas of the significant tornado parameter. Thumbnail of an automatically generated image showing areas of the significant tornado parameter. Thumbnail of an automatically generated image showing areas of the significant tornado parameter.
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Significant Tornado (SigTor) 

A composite index that includes 0-6 km bulk wind shear, 0-1 km storm-relative helicity, surface based CAPE, surface parcel CIN, and surface parcel LCL height. Values greater than 1 are indicative of increased potential of significant tornadoes.

The contours are the Lifted Condensation Level or LCL.  A lower LCL typically increases tornadic risk because it is indicative of air parcel acceleration occurring closer to the surface. 

 

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