Beautiful Thanksgiving Weather - Snow Black Friday Night Into Saturday?
Beautiful Thanksgiving Weather!
Sunny skies, light winds, and afternoon high temperatures in the upper 60's to mid 70's are forecast across the Southeastern Plains of New Mexico today. Average high/low temperatures for Nov 26th range from the upper 60's across the lower elevations, to the mid 50's and mid 40's in the mountains. Lows in the mountains average in the 20's and plains.
Thanksgiving weather just does not get much better than this unless of course, you like the cold and snow like me. Enjoy New Mexico's holiday weather today because this too shall change starting tonight.
Cold Front Arrives This Evening.
Valid At 5 PM MST Thanksgiving Evening.
Valid At 5 AM MST Saturday.
A backdoor cold front will move south and west down the eastern side of New Mexico today arriving in the Pecos Valley around sunset. Temperatures will be some 15º colder behind the front on Friday. Low level easterly to southeasterly upslope flow will develop over the area Friday night into Saturday.
GFS 500 MB/18,000' Forecast.
Valid At 5 PM MST Friday.
Normally when I talk about the mid-upper level storms that affect our area I post snapshots of the 500 millibar (18,000' level) pressure chart anomalies. These charts depict the pressure gradient at the 18,000' level of the atmosphere. Both high-pressure systems and low-pressure systems. This morning I chose to show the heights and vorticity map instead.
A strong short wave trough of low pressure at 18,000' was centered over northern Nevada last night at midnight. This short wave trough of low pressure is forecast to move slowly southeast today into Friday. By Friday at sunset, the GFS forecast model places a closed low over western New Mexico at the 18,000' level. The 500 millibar or 18,000' level charts are roughly halfway up in the atmosphere between the surface and about 40,000. Remember the jet stream normally is located between about 17,000' and 40,000' so these mid-upper levels storms usually form (but not always) just below the jet stream.
This next inbound storm to affect New Mexico's weather Friday into Saturday will be somewhat moisture starved at the mid and upper levels. It will be a strong and cold storm but will have limited moisture to work with. Weak easterly to southeasterly low-level upslope flow will develop behind the cold front Friday and Saturday and this will provide limited moisture for the storm to ingest or work with.
I chose the vorticity chart because it gives a clearer picture of the dynamics of the storm. Strong PVA or positive vorticity advection will be located over southern and western New Mexico Friday into Saturday at the mid-upper levels of the atmosphere. This lifting or upward forcing motion will help produce snow over parts of the Land of Enchantment Friday into Saturday.
NWS Albuquerque Snowfall Forecast.
Storm For Black Friday Into Saturday?
Given the current computer models forecast track of our next incoming winter storm, current forecasts indicate that snowfall totals across New Mexico will be on the light side with the heaviest snows falling in the mountains. As is the case so many times with these storms the exact track, speed, and location of this one will determine where the snow falls or doesn't. If it slips further south and slows down some more then the totals depicted on the charts above will be higher than currently forecast.
And this storm will produce bands of snow which will mean that some locations could get several inches of snow, while just a few miles away, others get next to nothing. We saw a great example of this with our October 25th, 26th storm. Carlsbad got 11/2" to 2", Artesia flurries to patchy ground cover, Hobbs flurries, Roswell 6" to 10", Cloudcroft 1"-3", Mayhill 6", Ruidoso area 6" to 9". A CoCoRAHS Station located 25 miles north of Roswell got clobbered with 17". Snow bands are extremely difficult to predict even in the short term forecast window and even more so when these narrow bands of moderate to heavy snow are convective in nature.
Snow will start falling across northern and western New Mexico on Friday and will spread eastward and southward Friday night into Saturday.
The Truth Is Stranger Than Fiction!