The major emphasis of the short-term forecast remains the extensive snowfall that is predicted to begin this afternoon and continue through Wednesday evening.
The greatest projected uncertainty at this time is how progressive the front will be, as well as where it will stall to cause the largest snow accumulation.
Surface data reveals that the first cold front has draped over the northern plains, past South Dakota, and into northeast Wyoming. This is consistent with previous forecasts. This storm system will most likely travel across our northern counties in the following several hours.
The front is forecast to get bogged down by the mountains for a while, but it will gradually move across our area as the day develops. High clouds are beginning to spread southeastward throughout the region, according to GOES satellite imagery.
Cloud cover is shutting off radiative cooling, preventing temperatures from plunging this morning as they did last night, according to the National Weather Service.
The possibility of light snow showers along the frontal boundary throughout our northern counties and developing in the mountains during the morning is forecast, but it is not likely to be of significant size or duration. During the day, there may be an inch or two of snow near Chadron.
It was decided to increase the mountains to the status of a warning as well, farther west. With excellent, moist southwesterly 700-mb flow, which is a suitable upslope wind direction for this location, there is more confidence in the Sierra Madre range.
It was also decided to include the Arlington/Elk Mountain region as well as the Shirley basin since sufficient lift is predicted to meet the warning requirements in these areas.
When combined with northeasterly winds that may gust up to 35 mph, we might be looking at substantial traffic disruptions on I-80 due to falling and blowing snow. Zones farther west will need to be monitored for the possibility of the alert spreading into central Carbon county and the Ferris mountains, but for the time being, expect rainfall in the 3-6 inch range.
Because we anticipated that the Laramie valley would be heavily shaded by the deep easterly flow, we adjusted QPF lower in this location.