A Heavy Rainfall Potential ALERT Is Now In Effect For Friday Into Saturday For The Cumberland Mountains.
The Potential For Rock-Mud Slides & Flash Flooding Will Exist With This System In Locations Along And West Of The Appalachians.
A high water content air mass associated with remnants of tropical storm Cindy will be moving across the mountains during Friday into Friday Night-early hours of Saturday.
Orographic Clouds Over The High Knob Massif
Observe wavy nature of clouds ( above ) over the High Knob Massif and the distinct band of clouds capping upper portions of the mass that helps to increase the volume of rain reaching the ground as drops fall from seeder clouds aloft ( radar beams overshoot these low-level orographic clouds and under-estimate the amount of rainfall reaching the surface over this complex terrain ).
Black Mountain Mesonet ( 0.72″ of rain during past 18-hours )
Increasingly strong & gusty SW winds + the seeder-feeder precipitation process ( orographic cap clouds ) will enhance lift and rainfall production, with torrential rains likely at times as this system moves across complex terrain of the Cumberland Mountain Overthrust Block.
NAM 12 KM Model MSLP and Precipitable Water At 8:00 AM Friday – June 23, 2017
A very moist air mass + strong low-level S-SW flow will develop rain over the mountains during Friday, with a concentrated band of system rain expected by Friday Night into early hours of Saturday.
NAM 12 KM Model MSLP and Precipitable Water At 8:00 PM Friday – June 23, 2017
Forecast models, and Doppler radars, tend to under-estimate the amount of rain that falls in this type of setting ( with rainfall during Thursday being under-estimate over the Cumberland Mountains well in advance of this system and its deep moisture ).
*Doppler beams overshoot orographic clouds and also tend to under-estimate the fine droplet-rapid fall rate nature of tropical rains moving across complex terrain.
NAM 12 KM Model Rainfall Forecast
Residents living and driving through low-lying areas and along mountain streams need to remain alert for the potential of rapid water-level rises and changing conditions Friday into Friday Night-early Saturday.
Storm Prediction Center Risk Regions
The Storm Prediction Center Has Issued A Marginal To Slight Risk For Severe Thunderstorm Development On Friday Into Early Hours Of Saturday ( June 23-24 ).
Stay tuned to NOAA Weather Radio and your favorite media sources for possible warnings that may be needed during this event.
National Weather Service Advisories As Of 3:12 AM Friday ( June 23 )
