Main changes in this update include a slight shift west in the National Hurricane Center track for Nate, with a little faster arrival of the worst conditions. This is not good news for final hours of the Cloudsplitter.
ALERT For Strong Winds & Heavy Rainfall Developing Sunday Into Monday Morning With Remnants of Nate
Strong Rises On Mountain Streams Will Become Possible By Later Sunday Into Monday Morning
*Later Portions of the Cloudspitter 100 race will have to endure increasingly bad conditions. Due to the speed of Nate there is increasing concern that some of the worst weather conditions may now arrive before the finish or ending time of the Cloudsplitter 100. Runners will need be prepared for increasingly bad conditions Sunday afternoon into Sunday evening, with ROARING winds developing over the high country of the massif. This could generate dangerous conditions for final hours of this race.
Strong rises on creeks will become possible by later Sunday into Sunday evening and Monday morning.
Saturday will feature relatively warm & gusty conditions for the High Knob Hellbender 10K Race and the first day of the Cloudsplitter. Conditions will then begin to deteriorate into Sunday and the second day of the Cloudsplitter, with precise conditions dependent upon the track and intensity of Nate into the central-southern Appalachians.
Conditions in the high country of the High Knob Massif will become much worse than at low elevations if this current National Hurricane Center track forecast verifies.
Nate became a hurricane by 2:00 AM Saturday.
A slight westward shift in the track of Nate is important since worst conditions will be along and east of the track.
Note – I will show graphics from the high-resolution NAM 3 KM Model for this forecast period. Although this model struggles to resolve local terrain, its high resolution allows for better modeling than courser model solutions. I will fill in the gaps with my own information based upon local climatology.
Friday Night Into Saturday Morning
Partly-mostly clear ( high clouds possible ). Becoming gusty higher elevations. SSE-SSW winds increasing to 10-20 mph, with higher gusts, into the overnight-morning on middle to upper elevation mountain ridges. Temps varying from 40s in cooler mountain valleys ( sheltered from winds ) to mid-upper 50s to around 60 degrees on exposed middle-upper elevation mountain ridges and plateaus.
A morning temperature inversion is likely on the floor of the valley in the City of Norton, with upper 40s to lower 50s ( 9 to 11 degrees Celsius ) during the sunrise period.
Racers beginning early will encounter the inversion layer upon climbing upward toward Benges Rock and the turn to Flag Rock Recreation Area ( warmer temperatures in this zone than down in the City of Norton ), with temperatures warming into the lower-middle 60s ( 18 Celsius ).
Climbing higher, above Flag Rock-Upper Norton Reservoir, the temperature will begin to decline back into the lower 60s ( 16 Celsius ) as wind speeds increase out of the SSW to SW at 10 to 20 mph, with higher gusts ( especially along the high crest lines ), to make it feel somewhat cooler than air temperatures suggest. While humidity levels will be higher than in recent days, conditions should in general be fine for the High Knob Hellbender 10K and the first day of racing in the Cloudsplitter.
Becoming partly to mostly cloudy & more humid. Winds SSE-SSW at 10-20 mph, with higher gusts. Temperatures varying from upper 60s to lower 70s ( 18 to 22 Celsius ) in upper elevations, above 3000 feet, to middle-upper 70s ( 24-26 Celsius ) at elevations below 3000 feet. Warmest at low elevations in the Hanging Rock Recreation Area where temperatures could rise above 80 degrees ( 27 Celsius ).
Note that microclimates in the High Knob Massif will impact conditions, with forest trails going along creeks and valleys ( which are cold air drainages ) tending to be cooler than more open sections during the day.
During this race period, of October 7-8, higher elevations will tend to be cooler by both day and night given enhanced mixing by winds and increasing moisture levels. The main exception being at the race beginning when temperatures in the City of Norton will be cooler than higher up until the nocturnal inversion mixes out into mid-morning Saturday.
If winds are light enough, some hollows, valleys and stream drainages could see temperatures fall back through the 60s late Saturday afternoon into the early evening, but unlike recent days a increase in clouds and moisture will prevent rapid temperature drops and keep most locations at or above 60 degrees ( a few high valley drainages could drop into the 50s early Saturday afternoon prior to rising later into the night as clouds thicken and rain develops ).
Saturday Night Into Sunday Morning
Becoming cloudy with light rain developing overnight into morning. Cloud bases lowering to below the summit level of the High Knob Massif. SSE-S winds 5-15 mph below 2700 feet. Winds S-SW 10-25 mph, with higher gusts, above 2700 feet ( especially on mountain ridges ). Temperatures falling into the 60s ( 16-18 Celsius ). Around 60 degrees ( 15-16 C ) at the summit level of the high country.
Temperatures will not be varying much in the high country as moisture levels increase and cloud bases begin dropping to eventually engulf upper elevations ( above 3000-3500 feet ) in dense fog ( orographic, upslope clouds ).
Runners can expect temperatures in the low-mid 60s with 90-100% RH throughout most of Sunday at elevations above 3000 feet, with mid-upper 60s expected at lower elevations.
Because lower elevations on the Scott County side of the massif, such as at Hanging Rock Recreation Area and the Devil Fork Trail, will be on the windward side of the massif during this event, conditions through Sunday will tend to be somewhat cooler and wetter than at lower elevations on the Wise County side of the massif ( below 2500 feet ).
Weather conditions are expected to become worse as Sunday continues, with increasing rain, wind, and the chance for thunderstorm development into afternoon-evening hours. Cloud bases are likely to drop into upper elevations of the high country to produce dense fog.
Sunday Morning Through The Afternoon
Increasing rain, with a chance for thunderstorms. Locally heavy rainfall likely, especially along windward slopes and crest lines of the High Knob Massif ( at elevations above 3000 feet & downward to bases in northern Scott County ). Cloud bases lowering to obscure upper elevations.
Winds SE to SSE increasing to 15-25 mph by later afternoon, with gusts over 40 mph in upper elevations ( lighter winds at lower elevations in hollows-valleys ). Temps near steady in low-mid 60s ( 16-18 Celsius ) at high elevations and in the upper 60s to middle 70s ( 20-22 Celsius ) at lower elevations ( below 2000 feet ).
This is the period, Sunday afternoon into Sunday evening, when weather conditions are likely to begin to deteriorate as remnants of Nate begin approaching and the pressure gradient begins increasing. This will begin increasing lift and orographic forcing across the High Knob Massif, with increasing wetness and increasingly strong SSE-S winds.
Although it is hoped that everyone will be finished with this race by the time wind speeds become dangerous, all runners should remain vigilant for possible falling limbs or trees as wind speeds increase into the 20-40+ mph range by Sunday afternoon into evening ( gusts of 50+ mph will be possible ).
Sunday Night Into Monday Morning
Rain becoming heavy. A chance of thunderstorms. Windy. Dense fog ( orographic clouds ) across upper elevations. SE-S winds 15-25 mph, with higher gusts below 2700 feet. SSE-SW winds 25-35 mph, with gusts over 50 mph, at elevations above 2700-3000 feet. Temps widespread in the 60s ( low-mid 60s in upper elevations ).
A general 2.00″ to 4.00″+ of rain is currently expected over the High Knob Massif area during Sunday into Monday AM, with locally higher amounts possible depending upon the track of Nate, his strength, and the positioning of a cold frontal boundary that is depicted above with a zone of enhanced rainfall amounts across central Kentucky.
Unseasonably warm and dry conditions will dominate the first day of racing on October 7, which will include all of the High Knob Hellbender 10K and the first day of Cloudsplitter races ( which extends through Sunday ).
Friday Night Into Saturday Morning
Partly-mostly clear ( high clouds possible ). Becoming gusty higher elevations. SSE-SSW winds increasing to 10-20 mph, with higher gusts, into the overnight-morning. Temps from 40s in cooler mountain valleys ( sheltered from winds ) to mid-upper 50s to around 60 degrees on exposed middle-upper elevation mountain ridges and plateaus.
The race period is only now ( Oct 4 ) coming into range of high resolution forecast models; therefore, I will begin to update this through coming days with more details that will extend through the entire race periods.
Currently it is clear that a surge of unseasonably warm air will be felt through Saturday in advance of another change back into unseasonably cool conditions by middle portions of next week.
What is uncertain, and will have to be updated, is how will a developing tropical system in the Caribbean-Gulf of Mexico impact the mountains by Day 2 of the Cloudsplitter. Stay tuned for updates as new data gets incorporated into forecast models during the next couple of days.
While a significant pattern change into chilly conditions will occur by the end of September and beginning of the new month of October, the most recent trend now finds a majority of the European Ensemble members warming temperatures back to above average by race weekend.
Although I highlight the operational European Model, the mean of the 51-Member Ensemble Group continues to show a shift to unseasonably cool conditions that will impact the 11th Annual High Knob Naturalist Rally.
This will create chilly conditions for the rally, as well as for any racers who may be in the region to practice.
Eagle Knob of High Knob Massif Elevation 4188 feet
Average Daily MAX: 62.1 degrees Average Daily MIN: 51.4 degrees September 1-23 MEAN: 56.8 degrees Highest Temperature: 73 degrees Lowest Temperature: 41 degrees Total Precipitation: 3.50″ to 4.00″
Conditions observed during September 1-23
High Knob Lake Elevation 3527 feet
Average Daily MAX: 64.8 degrees Average Daily MIN: 50.4 degrees September 1-23 MEAN: 57.6 degrees Highest Temperature: 76 degrees *Lowest Temperature: 41 degrees
*Middle 30s occurred in the colder valleys, with average nightly lows for the September 1-23 period being in middle-upper 40s.
The new development is beyond this time, with a shift back toward eastern-central USA ridging and troughing over the Pacific Northwest leading up to the weekend of the races.
The operational European Model ( above ) has support of all but approximately 14 members of the 51-member ensemble group ( mean of the group below ).
If this new trend is accurate, it would lead to above average temperatures returning in time for race weekend ( Oct 7-8 ). Positioning of height centers, above, would also suggest a continuation of mainly dry conditions.
Stay tuned for updates as race weekend gets closer in time and details become more clear. The first detailed forecast for these races will be made by the middle of next week.
The High Knob Hellbender 10K and Cloudsplitter 100 races remain more than a month away at the time of this initial outlook. So this certainly must be considered preliminary.
Forecast’s such as this current 5 to 9 day outlook from the 51-Member European Ensembles are extended outward through time to generate the European Weeklies.
I am not allowed to actually show the graphics of the weeklies, but they are currently forecasting a cooler than average temperature trend through September into early October, with near to above average precipitation.
The Climate Prediction Center outlooks for September and Autumn 2017 are similar, predicting a cooler than average September followed by warming to above average to push mean fall temperatures above average.
Many changes begin occurring in the atmosphere during autumn, as the seasonal transition from summer toward winter begins in the Northern Hemisphere, making any given forecast uncertain for extended periods of time. Check back for later updates.
As race time gets closer a forecast designed specifically for the three-dimensional nature of the race courses, which are run across 2000-3000 vertical feet of elevation change, will be produced that accounts for the complex terrain and microclimatology of the High Knob Massif.