A FLASH FLOOD WATCH IS IN EFFECT THROUGH SUNDAY AFTERNOON FOR ALL COUNTIES ALONG THE VIRGINIA-KENTUCKY BORDER. GIVEN RAIN ALREADY OBSERVED AND THE UPPER AIR-SURFACE SETTING THIS IS A PARTICULARLY DANGEROUS SITUATION.
ALERT FOR HIGH WATER LEVELS ALONG CREEKS & RIVERS AND THE THREAT FOR FLASH FLOODING AND RIVER FLOODING WITH ADDITIONAL HEAVY RAINS.
*A general 3.50″ to 4.00″ of rain has fallen across upper elevations in the High Knob Massif since 2:00 AM on April 20. Roaring water levels and dangerously slick banks are being observed now ( as of 3:00 PM April 22 ). Additional rainfall will threaten low-lying sites downstream along the Wise-Scott-Lee border through Sunday with flooding and flash flooding. Remain alert to changing conditions. Extreme caution is advised.
Communities at risk for flash flooding and flooding include but are not limited to the following: City of Norton, Ramsey, Tacoma, Coeburn, Dungannon, Fort Blackmore, Ka, Appalachia, Big Stone Gap, East Stone Gap and Cracker Neck, Jasper, Peterson, Duffield, Pennington Gap as well as communities along and upstream of tributaries of the Clinch and Powell rivers.
**In addition, flash flooding and river flooding will need to be closely watched for communities across northern Wise and Dickenson counties where creeks are also running high on tributaries of the Russell Fork and Levisa Fork rivers.
*Do NOT Cross Flooded Roadways. TURN AROUND AND DO NOT DROWN – A LIFE CAN NOT BE REPLACED!!!
Remainder of Saturday Afternoon Into Sunday AM
Periods of showers and thunderstorms. Rain will be heavy at times, especially by the predawn-morning hours. Remain alert for flash flooding-flooding. NE-E winds increasing to 5-15 mph, with higher gusts. Temperatures near steady or falling into the 40s. Widespread fog above 2500-3000 feet, with areas of dense fog at lower elevations.
Sunday Morning Through Sunday Afternoon
Rain, with a chance of thunderstorms. Rain will be heavy at times. Remain alert for continued rises on creeks-rivers. E winds 5-15 mph, with higher gusts, below 2700 feet. Winds E-ESE at 10-20 mph, with higher gusts, on mountain ridges above 2700 feet. Unseasonably chilly with temperatures varying from upper 30s to lower 40s at highest elevations to the mid-upper 40s to near 50 degrees. Widespread dense fog at upper elevations. Wind chills in the 20s and 30s at upper elevations.
Sunday Night Into Monday Morning
Rain tapering to showers and drizzle. Low clouds with areas of dense fog ( especially at higher elevations ). Winds NE-E at 5-15 mph, with higher gusts. Temperatures varying from 30s at highest elevations to the 40s. Wind chills in the 20s and 30s in upper elevations ( above 3000 feet elevation ).
Weather Discussion ( Flood Threat )
Saturated ground from recent days of rainfall and another storm system is threatening the mountain area with flash flooding and flooding.
High Knob Massif Webcam – University Of Virginia’s College At Wise
The current break in rainfall will be short-lived with a threat of training rains moving back into the area by late afternoon into tonight.
Regional Doppler Composite
In addition, a notable dip in the jet stream will provide upper air divergence aloft to support rising air through a deep layer of the atmosphere by the predawn-morning hours of Sunday to enhance the heavy rainfall potential.
*Isentropic lifting, not “over-running,” of very moist air over cooler air near the surface will aid rainfall along with orographic lifting in low-levels by major terrain features. This all occurs below significant 500-250 MB upper air divergence ( diffluence ) with the cutting-off of a upper-level low and cold pocket aloft.
NASA Water Vapor Image At 3:45 PM on Saturday ( April 22, 2017 )
The period that looks especially worrisome is during the daylight hours of Sunday, according to the latest model runs Saturday night. Several more inches of rain will be possible across the southern Appalachians ( the eastern slopes received much less rain into Saturday so they can handle more rainfall than western slopes…but all these areas from the Cumberlands to the Blue Ridge will have enhanced risk of flooding into Sunday night ).
NAM 12 KM Model – Rainfall Still To Come Through Sunday Afternoon
Up to this point ( Saturday PM ) rainfall amounts have been under-estimated by models in many places; therefore, with several more inches being forecast the flood threat in this setting is “higher than average.”
NAM 3 KM Model – Rainfall Still To Come Through Sunday Afternoon
Although any one living or driving through flood prone, low-lying areas will need to remain alert, a threat for flash flooding-river flooding means that everyone should pay close attention to changing conditions through tonight and Sunday.
Stay tuned to NOAA Weather Radio and your favorite media sources for possible WARNINGS that may be needed during this event.
