ALERT For The First Widespread Frost And Freezing Conditions Of The Season During Sunday Morning And Monday Morning (October 13-14), Especially Away From Major Lakes And River Valleys.
A combination of very dry air advecting in from the Midwest, with clear skies and light winds, will set the stage for the first widespread frost and freezing conditions. Mountain valleys, especially at middle-upper elevations, will be most at risk for frost-freezing conditions into Sunday morning (13 October). Mountain ridges will generally remain frost-free, except for cold air drainage areas on plateaus.
All locations except for major lakes and river valleys, as well as exposed mountain ridges, will be at risk for frost and freezing conditions into Monday morning (14 October).
A hard freeze will occur within colder mountain valleys into Monday morning versus fog formation in the vicinity of major lakes and rivers which will offer protection from sub-freezing temps (frost could occur prior to river-lake fog formation).
Until the cold season deepens, a complex pattern of frost and freezing conditions will naturally exist within the complex, three-dimensional terrain setting of the Mountain Empire.
It is important for you to recognize your setting. If you live within a location that typically gets frost more than nearby places, then your risk will be higher during the next couple of mornings. If you live in a location that typically is the last to experience frost, then your risk of having frost will be low during this period.
Observed Conditions_13 October 2019
The City of Norton lies within a middle elevation valley, with a downtown benchmark elevation of 2141 feet above mean sea level. Norton receives cold air drainage from the high country of the High Knob Massif toward the southwest-south-southeast, and from Black Mountain toward the northwest and north, to generate often notable temp contrasts with exposed sections of the nearby Wise Plateau where air temperatures can be 10-20+ degrees milder on cold air drainage nights.
Air temperatures late Sunday evening were dropping quickly in mountain valleys, with 39 degrees in the City of Norton and 39.5 degrees in Clintwood (at 11:34 PM on 13 October). This is setting the stage for widespread mountain valley frost within locations along and north of the High Knob Massif, with fog in locations along and upstream of major lakes and rivers.
The first scattered frost and freeze of the season was observed within colder mountain valleys and plateaus early Sunday, 13 October, with temperatures in the 30s (34 degrees Norton and locally below freezing in high valleys of the High Knob Massif). Areas of fog were also common, especially at lower elevations.
Looking Ahead_First Rime?
Following early week warming, in wake of weekend and early Monday frost in colder valleys, the focus shifts to the next cold frontal boundary expected to spread light-moderate rain, with possible downpours, into the mountains during Wednesday (16 October).
Dropping temperatures and wind chills through the afternoon into Wednesday night and Thursday morning (17 October), with air temps falling through the 40s and 30s, will set the stage for the first rime formation of the season on highest peaks into early Thursday. That is the current trend to be followed through coming days, with even a high elevation snowflake or two being possible.
Forecast Verification_14 October 2019
Widespread frost and freezing temperatures were observed Monday morning, 14 October, with temperatures at or below freezing from the City of Norton to Clintwood.
A low of 32 degrees was recorded on the roof-top at Norton ES, with slightly colder temps reported by more standard sites near ground level in the Norton-Ramsey to Tacoma-Coeburn corridor, and the Big Laurel to Esserville valley corridor. An official low temperature of 31 degrees was recorded in Clintwood.
Fog was limited amid dry air, such that mountain valley frost was heavy and widespread in many valley locations upstream and downstream of the High Knob Massif in Wise County and parts of Dickenson, Lee and northern Scott counties, with the coldest temperatures within high valleys at upper elevations, above 2700 feet, in the massif where hard freezes occurred.
Fog formation was most widespread along the Clinch River, lower portions of the Russell and Levisa Forks of the Big Sandy River, and the Cumberland River in southeastern Kentucky.