Mountain Area Forecast ( Jan 21-24 )
An Alert For Development Of A Major Storm System, With Deep Low Pressure, Is Now In Effect From Late Sunday Into Tuesday Morning.
A powerful low pressure will develop along the Appalachians by late Sunday into Monday. Showers & thunderstorms Sunday will give way to the development of heavy rainfall Sunday Night into Monday, with significant rainfall amounts expected.
Strong rises on streams will be likely into Monday. Folks living & driving through low-lying and flood prone locations will need to remain alert for changing conditions.
An increase in wind speeds and colder air will develop by late Monday into Tuesday, with a change from rain to accumulating snow at elevations above 3500 feet.
Overnight Into Saturday Morning
Mostly cloudy ( high clouds ). Areas of valley fog possible. Winds SSW-SW at 5-15 mph, with higher gusts, on ridges & plateaus below 2700 feet. SSW-SW winds 10-20 mph, with higher gusts, on upper elevation mountain ridges. Temps varying from 30s to around 40 degrees in valleys to the upper 40s to low-mid 50s on gusty mountain ridges.
Increasing clouds with a chance for showers or steady rain by middle to late afternoon. Unseasonably mild. Light SE-S winds at mostly less than 10 mph. Temperatures varying from upper 40s to lower 50s at highest elevations to the upper 50s to lower 60s.
Saturday Night Into Sunday Morning
Mostly cloudy. Chance of showers. SE-S winds increasing to 5-15 mph, with some higher gusts along mountain ridges by morning. Temperatures in the 40s to lower 50s. Areas of dense valley fog.
Mostly cloudy. A chance of showers & thundershowers. Mild. ESE-SSE winds at 10-20 mph, with some higher gusts, especially across middle-upper elevation mountain ridges & plateaus. Temperatures from the 40s to lower-middle 50s, coolest at the highest elevations.
Strong water level rises on streams will be possible into Monday. Folks living and driving through low-lying, flood prone locations will need to remain alert to changing conditions.
Sunday Night Into Monday Morning
Rain developing. Becoming windy. Heavy rainfall totals. Winds shifting from easterly to northerly into morning. Wind speeds 10-20 mph, with higher gusts, on mid-upper elevation plateaus-ridges. Dense fog ( orographic clouds ) at mid-upper elevations. Temperatures dropping into the 40s. Wind chills falling into the 30s in upper elevations.
Rain & showers. Low clouds with dense fog at elevations above 2500-3000 feet. Patchy fog at lower elevations. NW-N winds 10-25 mph with higher gusts. Temperatures falling into the 30s to low-mid 40s ( coldest at highest elevations ). Wind chills dropping into the 20s & 30s.
A change from rain to snow is expected in upper elevations by late Monday into Tuesday AM. Accumulations of 1-3″ are expected at elevations above 3500 feet, with 3-6″+ at elevations above 4000 to 5000+ feet in the southern Appalachians. Slushy to hazardous driving conditions are expected at these high elevations.
Monday Night Into Tuesday Morning
Rain & showers. Rain changing to snow at the highest elevations. Winds NW-N at 10-25 mph, with higher gusts. Dense fog at elevations above 2500-3000 feet, becoming freezing fog at elevations above 3400 feet. Temperatures dropping into the upper 20s to mid-upper 30s ( coldest at highest elevations ). Wind chills in the 10s and 20s ( again coldest at highest elevations ).
A storm system tracking across mid-continent will push milder air briefly back into the mountain region by the middle of next week, before temperatures crash during late week to mark the start of a prolonged wave of cold conditions.
Weather Discussion ( Major Storm )
Saturday Night Update
The strongest low pressure of the winter season to date will be impacting the mountain region Sunday into Tuesday AM, with home barometers expected to plunge toward 29.00″ .
Any time pressure has reached that low in the past, strong winds develop as the center begins moving away with rapidly rising air pressures as air flow rushes across the mountains to fill the “void” of low pressure ( i.e., the atmosphere works to achieve balance ).
Although varying at the surface with details, models remain fairly consistent at upper levels. Past climatology says that significant weather impacts will occur with this type of storm development, which will present an array of conditions varying from showers and possible downpours in thunderstorms Sunday to heavy rain Sunday Night into Monday. Winds increase and air turns colder later Monday as barometric pressure begins rising rapidly as the storm center shifts east. Rain turns to accumulating snow at upper elevations ( cold air is limited, so this will be a strongly elevation biased event with respect to snow accumulations ).