Mostly clear. Large vertical temperature spread between colder valleys and milder ridges & exposed plateaus. Areas of dense valley fog. Light winds. Temperatures varying from lower-middle 40s in colder mountain valleys to the upper 50s to around 60 degrees exposed ridges-plateaus.
Monday Afternoon
Partly to mostly cloudy at times. Small chance of sprinkles. Light northerly winds. Temps varying from mid-upper 60s in upper elevations to the middle 70s to around 80 degrees.
Monday Night Into Tuesday Morning
Mostly clear. Areas of dense valley fog. Light northerly winds below 2700 feet. SE winds 5 to 10 mph, with some higher gusts, along mid-upper elevation mountain ridges. Large vertical temperature difference developing between colder mountain valleys & milder ridges-exposed plateaus. Temperatures varying from 40s in colder valleys at upper elevations to the upper 50s to lower-mid 60s.
Tuesday Afternoon
Partly to mostly cloudy. Chance of rain showers. Thunder possible. Winds becoming NW-NE generally less than 10 mph. Temps varying from 60s in upper elevations to the middle 70s to around 80 degrees.
Tuesday Night Into Wednesday Morning
Partly-mostly cloudy. Chance of showers-thunderstorms. WNW to NW winds 5-10 mph, with some higher gusts, on middle-upper elevation mountain ridges. Areas of locally dense fog. Temps varying from 50s to lower-middle 60s.
Wednesday Afternoon
Partly to mostly cloudy. Chance of showers-thunderstorms. WNW-NW winds generally less than 10 mph. Temperatures varying from 60s in upper elevations to the mid-upper 70s.
High Knob Massif Webcam – University Of Virginia’s College At Wise
A beautiful sunset to mark the close of the first work day of these final days of astronomical summer. Afternoon maxs varied from 60s in upper elevations of the High Knob Massif to the 70s across low-middle elevations in Norton-Wise and the Clintwood area ( around 80 degrees in Haysi-Grundy ).
Clintwood 1 W National Weather Service Station
Monday began with a large vertical temperature spread that is typical of the mountains. Readings at sunrise varied from 40s in colder valleys of the High Knob Massif to upper 50s to lower 60s on exposed mid-elevation mountain ridges.
*The AM MIN actually only fell to 63.9 degrees at the Flatwoods Mountain Mesonet adjacent to Pine Mountain along the Kentucky side of the stateline ( generating a nearly 20 degree difference between coldest valleys and mildest ridges ).
Nora 4 SSE National Weather Service Station
This temperature data is, of course, from highly accurate and well shielded instruments and not roof-top sensors or other small solar radiation equipped stations.
*My study on solar radiation shields indicates that day-time temperatures tend to run 1 to 3 degrees, occasionally more, above what official National Weather Service sensors with larger shields record. It is very important to realize that the design and size of the solar radiation shield used is vital to accurate data collection.
*I should have noted that the above study was over a natural surface of grass. If sensors are not over a natural surface, or located near roof-tops or parking lots, then the skew ( error ) will be much greater by day due to heat liberation and advection from anthropogenic surfaces. So placement and instrumentation are critical to accurate temperature recording of the true air temperature for long-term climate documentation and analysis.
Clintwood 1 W National Weather Service Station – September 1-18, 2017
The only changes to my update is to increase the chances for showers, with thunder possible, from late Tuesday into Wednesday, with the European Model continuing to show best chances being during Wednesday ( the NAM Model begins best chances Tuesday evening into Wednesday ).
Category 5 – Hurricane Marie
Meanwhile, Hurricane Marie has just been upgraded to a CAT 5. Although truly a majestic storm from new GOES-16 visible imagery ( below ), this is yet another tragedy for places to be impacted in coming hours.
Hurricanes Marie and Jose – Beginning Of A Fujiwhara
Monday afternoon offered the first GOES-16 visible images that show the developing connection between Marie ( lower right ) and Jose ( off the Virginia coast ), with upper-level outflow from Jose reaching down to the anticyclonic spin of intensifying Hurricane Marie.
Previous Discussion
Early Autumn In Big Cherry Lake Wetland Valley – September 16, 2017
Seasonally cool nights in mountains valleys, and mild to warm days, will be featured this week along with cloud development by day. Only a small chance of sprinkles or rain showers is currently in my forecast, with Wednesday afternoon looking to have the best chances. A typical array of dense valley fog formation is expected by night.
Early Autumn At High Knob Lake – September 16, 2017
An array of early color changes are on display across the high country of the High Knob Massif. Most places have some early color changes, to a more limited extent, following a rather cool first half of September.
Early Autumn At Upper Norton Reservoir – September 16, 2017
The tropics will again be the main focus this week, with the European Model group suggesting that Jose and Marie may do a Fujiwhara Dance with each other; although, details of this dance routine are still being choreographed!
The Fujiwhare effect in meteorology is named for Japanese meteorologist Sakuhei Fujiwhara who first described the interaction of two vortex centers about each other. A connection between their circulations becomes increasingly evident over time as the effect develops ( initially they are far removed with no clear interactions between each other, as seen early on September 18 ).
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 1-5
Upper-level ridging over eastern North America into the western Atlantic is the main factor expected to play into this dance, with no clear steering flow yet seen to carry these hurricanes out to sea. This is the same system that will limit rain amounts this week and contribute to a mild to warm pattern ( with mountain valley coolness being a terrain driven feature more than a synoptic-scale one ).
There are increasing signs of a significant upper-level shift back to unseasonably cool conditions by the final days of September into the beginning of October.
