Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 249 PM EST Mon Dec 13 2021 Valid 00Z Tue Dec 14 2021 - 00Z Thu Dec 16 2021 ...There is a Moderate of excessive rainfall over parts of Central California through Tuesday morning; There is a Slight Risk of excessive rainfall over parts of Southern California on Tuesday into Wednesday morning... ...Heavy snow over the Cascades, Sierra Nevada Mountains, and Northern Rockies... ...Record warmth for the Central Plains by Wednesday, including possible all-time December records... ...Critical Fire Weather risk for parts of the Southern High Plains... ...Widespread significant wind gusts and blowing dust for the Four Corners, Southern High Plains into the Central Plains... An elongated mid-level low is currently digging southward along the California coast, propelled by a very strong 160-180 mph upper-level jet that extends from southern Alaska to the storm. This jet energy will transfer to the to the mid-level low and accelerate it into southern California late on Tuesday before shifting across the Colorado Rockies on Wednesday. Ahead of the base of the mid-level low, an atmospheric river is currently set up impacting the central California coast. While the moisture is average to slightly above average, the strength of the low is rapidly increasing low level wind response and focusing the plume increasing rain rates to up to 1"/hr and additional totals of 6" and so WPC has a moderate risk for excessive rainfall and given proximity to burn scars may result in flash flooding, debris flows and mudslides for the Big Sur coastline though this evening. The plume will start to shift south in earnest tonight and round the bend of Point Conception and direct similar high rates and overall totals of 3-5" for favored southward and southwestward facing Transverse Mountain ranges later tonight into tomorrow. 1-2" are possible in the lower valleys of southern California through Tuesday, before the plume weakens and drops south into Old Mexico, and as such a Slight Risk of Excessive Rain is posted for tomorrow (Tuesday) for southern California While a large amount of rain will fall along the coast, this mid-level low also brings cold air that and will lower freezing levels across the Sierra Nevada, where significant snows are likely with multiple feet (3-6) possible when all is over. Significant snows will given cross over into the Great Basin and parts of the Northern Rockies (Idaho, SW Montana) with 1-3 feet possible. Travel may become impossible through mountain passes with road closures expected. Heavy snow will occur across the tops of the Transverse and Peninsular ranges of southern California, though totals are to be as extreme as further north, Winter Storm Warnings are in effect with 3-7" with 8-24" above 8,000ft. High Wind Warnings generally accompany the heavy snow across the highest elevations of the Sierra Nevada and expected across Southern Californian Ranges. By Tuesday, the approach of the mid-level low will start to be felt along the length east of the Rockies from Montana to New Mexico. A surface low will rapidly deepen across the Northern Rockies and winds will rapidly accelerate from the south and southwest. This will bring in well above normal temperatures with high temperatures into the 60s across the Central Plains and 70s across the Southern Plains which is near records and 25-35 degrees above normal. The low will continue to deepen quickly and slide into the central Plains. Winds will respond continue to strengthen overnight and the heat will expand well into the Upper Midwest. Temperatures will be 35-45 degrees above normal (50s in Midwest, 80s in southern Plains) with a vast majority of record highs to be broken, with possibilities of record all-time December high temperatures possible in some cities. Along with the record temperatures, those winds will be strong throughout the day but with occasional gusty winds. Those winds could be significant with 60-75 mph gusts possible at times, as such a vast High Wind Watch is in effect from northwest Arizona to Colorado/New Mexico High Plains across the Central Missouri River Valley to southeast Minnesota. The stronger winds likely to be across the Plains, where blowing sand/dust is probable across New Mexico, West Texas into Colorado, western Kansas/Oklahoma. Dry grounds and low humidity also present Elevated to Critical fire danger, per the Storm Prediction Center across the OK/TX panhandles for Tuesday. This expands a bit into surrounding Colorado, Kansas and New Mexico for Wednesday with localized Extremely Critical fire conditions possible, which could lead to rapid fire spread which would be highly dangerous and life-threatening. Gallina Graphics are available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php