Our quiet pattern is slowly breaking down today. A seasonably strong Pacific storm made landfall on the West Coast yesterday, and will be moving east into the Rockies today. This system will bring rain and mountain snow to much of the northern Rockies. Meanwhile to the south, an upper level low that’s been stuck over Mexico is ejecting east towards Texas. As this system interacts with moisture from the Gulf of Mexico, expect storms to develop across parts of SE Texas today. Lightning and heavy rain will be the biggest threats from these storms and no organized severe weather is anticipated.
Today’s national overview map from the ECMWF highlights our two areas of active weather. Aside from the northern Rockies and SE Texas, quiet weather is expected today across the country.
ECMWF liquid equivalent snow forecasts (what’s that?) show a decent amount of moisture falling as a result of this system. Through tomorrow morning, a wide swath of Southern Montana, Western Wyoming, and Central Idaho will see more than .4″ of liquid equivalent precip, which will translate to 4-6″ of snow. The higher terrain will see over an inch of liquid equivalent, indicating potential for over a foot of snow. The valleys will see lesser amounts, between a coating and an inch or two. Snow will continue to fall as this system moves into the Northern Plains tomorrow, for more details on that aspect of the storm’s impacts click here.
The ECMWF’s thunderstorm composite (what’s that?) shows a setup favorable for some weak thunderstorms today across Texas. Instability is modest at best, as shown by CAPE (what’s that?) values generally at or below 500 J/kg. An upper level disturbance is shown by the blue arrows that point from the NW west of Austin Texas and from the SW east of Austin. This upper level disturbance will help to provide a trigger for some thunderstorms, but without much instability, severe weather potential will be limited.
Elsewhere across the country, quiet weather will continue today as our pattern is only beginning to transition from quiet to active. For more on that transition and what impacts it might bring, click here.
For more information about your local forecast: https://weather.us/
For more information about the local forecast for ME/NH: https://forecasterjack.com/2017/12/03/another-cool-and-quiet-day-today/