Weather Discussion: Friday, December 22nd, 2017

HIGHLIGHTS: RAIN OVER THE WEEKEND, CHRISTMAS DAY CLEARING, MORE WINTRY WEATHER?

A disturbance will develop in the lower Mississippi Valley on Friday and will move northwestward, bringing rain to Alabama and Tennessee and up toward the Ohio Valley. Most of the precipitation from the system will not make it over the Appalachians until Saturday; however, increased cloud cover and warm conditions from southwesterly flow will dominate the weather on Friday into Saturday morning. Precipitation will finally make it over the mountains Saturday afternoon, although a lot of the strongest precipitation will have already fallen, as the system will be dying as it moves over the mountains. Currently, best estimates of precipitation would be between a tenth and one-quarter of one inch Saturday night into early Sunday morning. The system will move out of the area Sunday morning, providing clearing for Christmas Eve, although an upper-level disturbance will move in early on Christmas morning, providing snow showers to the mountains and extra cloud cover for our area.

 American Model (GFS) Forecasted Precipitation amounts for Saturday Night into Sunday Morning, 23-24 December 2017.

American Model (GFS) Forecasted Precipitation amounts for Saturday Night into Sunday Morning, 23-24 December 2017.

This disturbance will be short-lived and should move out of the area by the time you wake up on Christmas Day. Christmas Day should be clear but chilly, as a cold Canadian air mass moves into the area. High temperatures will be in the low 40s and low temperatures will be in the 20s. This cold pattern looks to hang over the area for at least the next week. There will be some moderation of temperatures on Tuesday and Wednesday, with temperatures looking like they will be in the mid-to-upper 40s for highs and in the 20s for lows.

 European Model (ECMWF) Forecasted 500-mb height anomalies for Saturday. 

European Model (ECMWF) Forecasted 500-mb height anomalies for Saturday. 

 European Model (ECMWF) 500-mb height anomalies for Monday

European Model (ECMWF) 500-mb height anomalies for Monday

An interesting setup appears likely for late next week into early next weekend. At present, models are suggesting that a disturbance out of the Gulf of Mexico will combine with an upper-level disturbance dropping out of the Great Plains, providing a source of moisture. At the same time, a strong cold area of high pressure will be located in Central Ontario, pumping cold air down across the eastern seaboard of the United States and into the Carolinas. While nothing is certain seven days out, there is a significant possibility for winter weather late next week. However, there is no need to take action at this moment, as the threat is still relatively low. The best thing to do is to stay tuned to updates from us here at Foothills Weather Network and other reliable sources of weather information (National Weather Service, Local Television stations).

 Synopsis of the POSSIBLE setup for late next week, likely Friday (29 December) into Saturday (30 December), overlayed on top of the GFS Forecast. THIS IS NOT A FORECAST!

Synopsis of the POSSIBLE setup for late next week, likely Friday (29 December) into Saturday (30 December), overlayed on top of the GFS Forecast. THIS IS NOT A FORECAST!

Have a great Friday!

Chase Scott Graham