ALERT For The Potential Of Heavy To Locally Excessive Rainfall Amounts
Interactive Lightning And Storm Tracking Doppler
Folks living and driving (and hiking) near streams and in low-lying, flood-prone locations will need to remain alert and closely monitor changing weather conditions through coming days.
Some Thunderstorms Could Be Strong To Locally Severe Into Sunday-Monday
Observe flow field streamlines from the Atlantic Ocean across the Gulf of Mexico into the southern Appalachians in a clockwise flow around High pressure centered near Florida. In addition, there is some concern that Saharan Dust could contribute some CCI (cloud condensation nuclei) to further enhance rainfall making capability as air is lifted by a combination of dynamics and orographics through a deep vertical column.
Roles Of Mineral Dust As Cloud Condensation Nuclei
Efficiency of Dust Storm Particles As CCI
Measurement Of CCI And Droplet Activation Kinetics
The role of dust as CCI is complex, with varied results depending upon many factors, not the least of which is location and particle sizes. CCI as a linkage between different climate system components, however, is clear and more research is needed to better understand these connections and the role dust plays from weather to ecosystem biodiversity (e.g., Saharan dusting acting to fertilize the Amazonian Rainforest).
Influx of tropical moisture around High pressure toward the south will combine with a upper air setting favorable for upward vertical motion to support a heavy to excessive rainfall potential.
A very moist atmosphere will combine with disturbances passing through a developing W-NW flow field to trigger clusters of showers and thunderstorms into early next week.
Some thunderstorms could be strong to severe on Sunday into Monday, with two main modes being watched for the severe potential:
1). Mesoscale Convective Systems that may develop in W-NW flow will have the potential to support strong-severe convection
2). Localized convection could turn severe, especially if breaks develop in the rainfall pattern to enhance instability associated with daytime heating.
Mesoscale, higher resolution models, are showing wide variations in rainfall with potential for locally excessive amounts and flash flooding.
The placement of heaviest rainfall amounts continue to vary among forecast models, and from run-to-run on the same model, but a clear signal for significant rain amounts is being displayed on all models.
Synoptic-Scale Weather Setting
A somewhat unusual pattern featuring heat ridge formation over the Great Lakes and southeastern Canada will cause temperatures, relative to long-term average, to skew hot in the north country to contrast with near average conditions over the SE USA and southern Appalachians.
A boundary separating seasonally hot air to the north from seasonal air toward the south will generate clusters of showers-thunderstorms.
The position and movement of the boundary over time will help to dictate where heaviest rains fall. Models are currently in disagreement.
Soil moisture has decreased significantly from the end of March in many places (especially amid high June sun angles).
Due to excessive amounts of precipitation for this point in a year, soil moisture remains on the surplus side, especially in wettest places.
High Knob Massif Precipitation Update (23 June 2020)
