ALERT For Torrential Rain In Hit-Miss Showers And Downpours In Thunderstorms During May 15-18
Increasing moisture from the Gulf of Mexico and Caribbean will combine with disturbances in the westerlies to trigger showers and downpours in thunderstorms beginning on Tuesday afternoon and continuing through the work week.
Overnight Into Tuesday Morning
High clouds & mild. Light valley winds. Winds S-SW at less than 10 mph on mountain ridges-plateaus below 2700 feet. SSW to SW winds 5-15 mph, with higher gusts, on mountain ridges above 2700 feet. Temperatures varying from 50s in cooler mountain valleys to the mid-upper 60s.
Tuesday Afternoon
Mostly cloudy with a chance of hit-miss showers and thunderstorms. Heavy rainfall possible, especially by late afternoon. Light & variable winds, except gusty in heavier storms. Temperatures varying from upper 60s to lower 70s at highest elevations to the lower 80s ( warmer south into the Great Valley ).
Tuesday Night Into Wednesday Morning
Mostly cloudy with a chance of showers & thunderstorms, especially during the evening. Areas of fog, dense in places receiving heavy rain. Light winds, except S-SW at 5-15 mph with higher gusts on mid-upper elevation mountain ridges. Temperatures in the 50s to lower-mid 60s.
Wednesday Afternoon Through Friday Afternoon
Partly-mostly cloudy with intervals of hit-miss showers and downpours in thunderstorms. Locally heavy rain amounts. Temperatures in 60s & 70s during the day and 50s to lower 60s at night ( generally coolest at upper elevations ).
Weather Discussion ( Summer Pattern )
A jump straight from spring into a summer-like pattern during the past week will kick into high gear during coming days as tropical moisture increases both horizontally and vertically through the atmosphere.
Wild Stonecrop ( Sedum ternatum )
Although the forest canopy has now closed at the lower elevations in the foothills of eastern Kentucky, and within the Tennessee Valley, it remains partially to fully open in higher elevations of the mountains.
NAM 12 KM Model Total Rainfall Forecast Through 8 AM Thursday – May 17
Humidification and relative mildness will enhance the progression of spring upward through higher elevations during the next week to 10 days, with a threat for tropical downpours to signal that this transition into summer is for real with staying power through the next couple of weeks.
European Model Ensemble Mean 500 MB Height Anomalies: Days 6-10
Bermuda High pressure off the east Coast and a general southwesterly flow aloft will continue the warm, humid pattern with intervals of showers & thunderstorms during the next week to 10 days ( while it will not rain, of course, all the time, a wetter and more humid pattern is coming to signal an early arrival of summer in the Mountain Empire ).
True summer will arrive as the forest canopy matures across all elevations and evapotranspiration increases to feed low-level moisture back into the overlying atmosphere ( * ).
*This process starts in lowlands, below 2000 feet, and progresses upward through higher terrain locations as spring progresses. It annually begins during the explosive April 15-May 15 period, at elevations below 3000 to 3500 feet, and advances to the highest summits through late May into early June.
