Rain will change to snow at highest elevations late Friday night into Saturday morning. Caution for a few slick patches, mainly above 3300 feet, into the early morning hours of Saturday ( Jan 5 ).
Wednesday Night Into Thursday Morning
Evening showers and areas of drizzle giving way to soaking rain. Breezing to gusty S-SW winds shifting W-NW and decreasing to 5-10 mph with some higher gusts. Temperatures dropping into the 30s to lower 40s ( coolest at highest elevations ). Low clouds with areas of fog, becoming widespread upper elevations.
Wind chill factors in the 20s to lower 30s at upper elevations and the 30s to low 40s at middle to lower elevations ( mainly along mountain ridges and exposed plateaus ).
Thursday Morning Through The Afternoon
Morning rain and low clouds giving way to mid-high clouds. Light NW-N winds becoming westerly at high elevations. Temperatures in the 30s to middle 40s.
Thursday Night Into Friday Morning
Mostly cloudy ( mainly mid-high altitude clouds ) evening skies giving way to lowering cloud bases with rain developing into the predawn-morning. Winds becoming SE-S and increasing to 5-15 mph, with higher gusts, mid-upper elevation mountain ridges.
Temperatures in the 30s to lower 40s, steady or rising overnight into morning. Areas of low clouds and fog developing ( especially at high elevations ).
Friday Morning Through The Afternoon
Morning rain giving way to showers. Breaks in clouds during the afternoon, especially west to north of the High Knob Massif. Unseasonably mild. Winds SE-S at 10 to 20 mph, with higher gusts, at elevations below 2700 feet. Winds SSE-SSW at 15-25 mph with higher gusts above 2700-3000 feet. Temps in the 40s to mid-upper 50s. Low clouds-fog at highest elevations.
Friday Night Into Saturday Morning
Windy & turning colder. Evening rain showers changing to snow at upper elevations, becoming mixed with or changing to snow showers or mix at middle elevations and becoming mixed with snow or sleet at lower elevations. Winds shifting SW to WNW at 10-25 mph, with higher gusts, on mountain ridges and exposed plateaus. Temperatures dropping to around 30 degrees at highest elevations to the mid 30s to around 40 degrees. Wind chills dropping into the 20s to lower 30s, except 10s in gusts highest peaks.
Snow accumulations of a dusting up to 1-2″ will be possible, mainly at elevations above 3300 feet.
Saturday Morning Through The Afternoon
Morning clouds giving way to mostly sunny skies. Gusty and seasonally cool. Winds W-NW at 10-20 mph with higher gusts. Temperatures mainly in the 40s, with 30s at highest elevations during much of day. Wind chill factors in the 20s and 30s.
An increasingly cold weather pattern is being monitored for the extended 6-10+ day period. Stay tuned for later updates on a return of wintry conditions.
Weather Discussion ( Winter Not Dead )
Lovers of snow and cold weather should not despair despite a mild, wet beginning to 2019. In fact, severe winter conditions remain likely to develop in coming weeks across the eastern USA.
Major Sudden Stratospheric Warming Officially Designated
New Year Day 2019 marked not only the beginning of another year but the official designation of a major sudden stratospheric warming above high latitudes within the Northern Hemisphere.
Winds at 10 mb and 60 degrees North must change from westerly to easterly ( blue color above ) and the temperature gradient must become positive in order to meet the technical criteria adopted by the World Meteorological Organization for a Major Mid-Winter Warming or SSW ( Sudden Stratospheric Warming ) event to be designated.
Zonal Mean Temperature At 10 MB And 60-90 Degrees North
This is an exciting development for meteorologists in the research fields, and a look back at last winter can illustrate why this is so important.
SSW = Sudden Stratospheric Warming
Zonal Mean Wind At 60 North and 10 MB During 2017-18 Winter Season
During the 2017-18 winter ( red line above ) a minor stratospheric warming aided an arctic blast which started 2018 as the Polar Vortex temporarily became weaker and the polar jet developed high amplitude.
The Polar Vortex then became stronger in January 2018 with a significant increase in zonal mean wind speeds ( upward spike in red line above ). A mild and record wet February followed locally as changes at high latitudes generated a major SSW event and the Polar Vortex weakened in February with reversal of winds to easterly ( red line dips below zero above ).
Locally, March into April turned wintry and conditions during March 2018 were colder than February.
45-Day Heat Flux This Winter_Last Winter_Versus Climatology
Major warming of the stratosphere came late in the winter season last year, with impacts locally being felt during March-April after they propagated down from the stratosphere to impact weather conditions within the troposphere.
This winter a record-level heat flux associated with current major SSW has occurred early in the winter season, with upcoming changes having the potential to be much more significant in terms of tapping air that is much colder ( forming amid darkness at high latitudes and being yet unmodified by rising solar angles ) in nature and transporting it southward.
Zonal Mean Wind At 60 N and 10 MB During 1984-85 Winter Season
Every SSW event tends to be different with varied results for middle latitudes, yet it must be recognized that these events tend to increase odds of conditions turning bad in mid-latitudes. This can result in late season wintry conditions which are bad for the time of year or severe conditions that can occasionally result in extreme events like happened later in January 1985 following a major SSW.
