Weather Headlines
A reduction in heat and increase in wetness is being outlooked heading into early June, especially along the Cumberland-Allegheny and Blue Ridge mountain ranges near and north of the central valley of eastern Tennessee (the Great Appalachian Valley Province).
A cluster of strong-severe thunderstorms generated local wind damage and power outages as it blasted across southeastern Kentucky into northern Dickenson County on May 26.
A ring-of-fire pattern will begin influencing the mountain area to a much greater extent heading into early June, with a contraction of the eastern USA heat dome that has ruled the second half of May 2019. This will place the Mountain Empire in between unseasonably cool air to the north and unseasonably hot air retreating to the south.
Note how the temperature regime changes during the first week of June (from above to below).
These changes occur as the pattern deamplifies with a contraction of the eastern USA heat dome and development of a more zonal to WNW flow into the eastern USA, replacing the broad SW flow regime which has locked severe weather in place within locations across the central USA and north of the Ohio River in the second half of May 2019.
Observe how the 500 MB height pattern changes (from above to below) in the first week of June. This occurs following an initial transition period during the upcoming weekend into early next week, when cooler and drier (lower dewpoint) air is felt. The potential for unseasonably cool air to reach the local area for a period of time is on the table and will be interesting to watch as a more northerly flow field develops. Eventually, at this time of year, this type of flow will become favorable for a ring-of-fire pattern as coolest air retreats northward unless the upper troughing becomes highly anomalous (deep-persistent).
This is not breaking news, of course, as the Mountain Empire has been just south of a ring-of-fire flow during recent days.
This type of flow regime will be favorable for clusters of thunderstorms, some strong to severe, as dictated by past climatology. This occurs as the ring-of-fire is displaced south and reoriented with contraction of the northern & northeastern heat dome periphery, assuming the 51-member ensemble mean is mainly correct in progged W-NW flow field trajectories.
May 2019 Pattern
Anomalies observed during May intensified during the May 12-26 period to help anchor persistent storminess in the zone between height anomaly centers (below).
The majority of the 4.00″ to 6.00″ of rain that fell in the May 1-28 period from the High Knob Massif north to Clintwood was observed during the May 1-12 period, with more hit-miss action during the second half of this month.
The majority of warmest days, even at high elevations, have occurred during the past two weeks with low-mid 70s on hottest days at highest elevations within the High Knob Massif and Black Mountain (following the unseasonably chilly air mass of May 13-15).
It is not surprising that highest temperatures are occurring over the driest ground in the southeast USA, with even the typically hot Tri-Cities area of eastern Tennessee being held in check by some energy being used to evaporate soil moisture accumulated from long-term wetness.
If precipitation continues to run below average in the Tri-Cities this effect will wane as the ground continues to dry during Summer 2019, however, it will continue if the upcoming June pattern reverses short-term dryness.
