082817 Forecast

Mountain Area Forecast ( Aug 28-30 )

An increasing chance for widespread showers and thunderstorms is being watched for mid-late week into this weekend as moisture from Harvey begins to finally lift north and east.

Overnight Into Monday Morning

High cloudiness.  Areas of valley fog.  Winds SSE-S at 5-15 mph, with higher gusts, on mid-upper elevation mountain ridges.  Temperatures varying from low-mid 50s in cooler mountain valleys and highest ridges to the lower 60s.

Remainder of Monday Afternoon

Cloudy ( mid-high clouds ).  Small chance of showers, mainly west of the mountains in SE Kentucky.  Light ESE-SSE winds generally less than 10 mph.  Temps varying from the lower 60s within upper elevations to the lower 70s.

Monday Night Into Tuesday Morning

Mostly cloudy.  Small chance of showers, especially to the southeast toward Mount Rogers-Whitetop.  Areas of river valley fog.  Winds E-SE at 5 to 15 mph, with higher gusts, along mid-upper elevation mountain ridges.  Temperatures varying from the upper 40s to low 50s at upper elevations in the High Knob Massif to the mid-upper 50s.

Tuesday Afternoon

Partly to mostly cloudy.  Chance of hit-miss showers and thunderstorms.  Light winds.  Temps varying from low-mid 60s in upper elevations to the low-mid 70s ( warmer south into the Great Valley ).

Tuesday Night Into Wednesday Morning

Partly to mostly cloudy.  Areas of valley fog.  Light winds.  Temperatures in the 50s to around 60 degrees, except the upper 40s to low 50s within colder high valleys at upper elevations in the High Knob Massif.

Wednesday Afternoon

Partly to mostly cloudy.  More humid.  A chance for showers and thunderstorms by mid-late afternoon into the evening.  Winds generally light and variable.  Temperatures varying from mid-upper 60s at upper elevations to the mid-upper 70s to around 80 degrees.


Weather Discussion ( In The Middle )

Monday Evening Update

A solid mid-high altitude overcast has dominated Monday with abundant clouds streaming northeast from tropical storm Harvey.  This held temperatures in the 60s and 70s, varying from lower 60s in the High Knob Massif to the low 70s in Clintwood ( 71.7 degree official maximum ).

High Knob Massif Webcam – University Of Virginia’s College At Wise

This update continues to highlight low rain chances over the mountains tonight, with a lesser chance for showers even toward the Blue Ridge as potential Irma along the Atlantic Coast struggles to develop within wind shear generated by Harvey and a polar jet stream.

Based upon late Monday evening readings, overnight temperatures in the high country of the High Knob Massif have been dropped a little from my previous forecast to account for lowering dewpoints and some possible over-night cloud breaks ( and decreasing predawn winds ).

Humidity + some instability will then offer a chance for localized shower-thunderstorm development Tuesday afternoon across the Cumberland Mountains.

NAM 12 KM Model Total Rainfall Forecast Next 84 Hours

Moisture related to the remnants of Harvey may begin to impact the mountain region by later Wednesday into the Thursday-Friday-Saturday period, with rainfall amounts and details yet to be determined.

Moisture from Harvey is looking increasingly like it will have some impact upon the area by late week-this weekend, per the latest ensemble means.
GFS Model Total Rainfall Forecast Next 132 Hours

While it has been a wet August in the mountains, with 7.00″ to 9.00″ widespread within the High Knob Massif – City of Norton and Big Stone Gap Water Plant area – just imagine that 3 to 4 times this much has fallen in the past few days over the area centered on Houston, Texas.

Month-To-Date Rainfall Estimated-Observed  – Ending 8 AM August 28, 2017
Estimated Rainfall Past 7 Days – Houston Tx Area – Ending 8 AM August 28, 2017


Previous Discussion

A few local downpours of rain, with lightning & thunder, developed Sunday to close out a seasonally cool weekend in the Cumberland Mountains.  This as the mountain region is safely in the middle between the terrible impact of Harvey along the Gulf Coast of Texas and a developing tropical system near the Atlantic Coast.

Low temperatures of 40 to 45 degrees were reported within colder mountain valleys of upper elevations, with 50s being widespread elsewhere in the mountain area, during recent days.
High Knob Massif Webcam – University Of Virginia’s College At Wise
The heaviest rain developed along the U.S. 23 corridor between the City of Norton and Big Stone Gap.
NASA Visible Satellite Image At 6:00 PM on Sunday – August 27, 2017
Doppler radar estimated locally more than 1.00″ of rain near and just northeast of Big Stone Gap ( most of which fell within 1 hour ).
Doppler 1-Hour Estimated Rainfall Ending At 6:14 PM on August 27, 2017

With so much air rising over the remnants of Harvey and along the Tidewater of the southeastern USA it is likely any local rainfall will remain limited into mid-week ( due to synoptic-scale subsidence ).  Meanwhile, there will be an abundance of high clouds over the area which are being sheared off the top of Harvey’s upper-level outflow.

USA Infrared Satellite Image At 3:15 AM on August 28, 2017

Some adjustments in cloud cover, temperatures, and the chance for showers may be needed depending upon the track of Harvey’s remnants during mid-late week.

European Model Mean Sea Level Pressure Forecast – 8:00 PM Friday ( Sept 1 )

The best chance for rain looks to be late this week into the weekend, when remnants of Harvey may finally get picked up by the jet stream.  Stay tuned for updates.