The 14th Annual High Knob Naturalist Rally will continue virtually through this week and next.

First Major Autumn Cold Front

The first major cold front of the autumn season to transport polar air southward will begin impacting the mountain area Monday Night into Tuesday. A marginal risk of severe storms will be possible along and just ahead of the cold front.

While localized showers and areas of drizzle will be possible Monday, the main shield of rain-embedded thunderstorms will spread across the mountains Monday night. Downpours and a sharp drop in temperature are expected overnight as winds shift northerly into Tuesday morning.

Be alert for water level rises and ponding of water within poor drainage, low-lying locations overnight into Tuesday morning

Cloud bases are expected to lower on upsloping winds that will shift northerly behind the cold front, with lifting of moist air up across middle-upper elevations along and southeast of the Virginia-Kentucky stateline (especially in locations along and N-NW of the High Knob Massif-TN Valley Divide).

ALERT For Dense Fog Development Tuesday At Middle & Upper Elevations Along-North Of The High Knob Massif-Tennessee Valley Divide On Upsloping Northerly Winds

Recall my elevation breakdown for forecasting is:

Below 2000 Feet = Lower Elevations
2000-3000 Feet = Middle Elevations
Above 3000 Feet = Upper Elevations

Expect temperatures mainly in the 40s to around 50 degrees at mid-upper elevations Tuesday in locations along and north of the High Knob Massif-Tennessee Valley Divide (with colder wind chills at higher elevations)

The 14th Annual High Knob Naturalist Rally will continue virtually through this week and next.

In the wake of general 1.50″ to 2.00″ rains over the high country there was an array of orographic and lenticular cloud formations.

Watch the right, sunset lit side of the slides during the darker images around sunset to best see stacked, lenticular mountain waves that are nearly stationary and extend across a much larger portion of the massif (opening slides show lingering, orographic cap clouds in wake of rains).

Remnant rains of Beta pushed the 12-month precipitation total at Big Cherry Dam to nearly 100.00″ (98.89″), which may be broken by the end of September.

Interactive Doppler Radar-Lightning Detection System

Previous Discussion

Rainfall late Thursday Night into early Friday is expected to become enhanced as tropical moisture interacts with the right-rear entrance region of a strong jet streak aloft.

Interactive 250 MB Jet Stream Streamline Field_USA

The Big Chill Is Coming

*Looking ahead, to the end of September and early October, an early winter-like pattern will be taking shape with much below average temperatures looking increasingly likely across the eastern portion of the USA.

While the GFS Ensemble pattern is impressive, the European Ensemble Mean is even colder and more impressive for the first few days of October. Air becomes so cold, in fact, that the first flakes of snow may fly along the Appalachians (especially at upper elevations) if the ECMWF ensembles are on target.

Certainly this would not be that unusual for the mountains, with accumulating snow common at upper elevations in the High Knob Massif during October (strong cold air intrusions being detrimental to autumn color along highest crestlines).

At the least, a pattern favorable for widespread frost and freezing temperatures will be developing into early October.