011617 Forecast

Mountain Area Forecast ( Jan 16-19 )

Several Significant To Major Storm Systems Will Be Impacting The Mountain Region During The Next Five To Ten Days, And Beyond In Time, With A Colder Trend Developing During The January 23-31 Period.

Strong rises on streams will begin to become more of a concern during this stormy pattern.  Folks living and driving through low-lying, poor drainage and flood prone locations will need to keep alert of changing weather conditions.  Stay tuned for updates.

ALERT For Dense Fog Continues Into Monday Morning

A very moist, saturated atmosphere will support widespread dense fog into Monday morning.  Visibility will drop to a quarter mile or less in the more dense areas of fog.  Caution is advised.

Overnight Into Mid-Morning Monday

Low clouds with widespread dense fog.  A chance for drizzle.  Winds SW to W at 5-10 mph, with some higher gusts, along middle-upper elevation mountain ridges.  Temperatures widespread in the 40s to around 50 degrees.

Monday Afternoon

Partly cloudy & unseasonably mild.  Winds SSW-SW at 5-10 mph, with higher gusts.  Temperatures varying from low to mid 50s in upper elevations to the lower-middle 60s.

Monday Night Into Tuesday Morning

Cloudy.  Becoming windy with a chance of showers and downpours overnight into morning.  Thunder possible.  Winds S-SW at 5-15 mph, with higher gusts, on mountain ridges & plateaus below 2700 feet.  Winds SW 15-25 mph, with higher gusts, on mountain ridges above 2700 feet.  Mild with temperatures in the upper 40s to low-mid 50s.  Dense fog redeveloping along upper elevation mountain ridges ( locally in other locations ).

Tuesday Afternoon

Low clouds.  Windy.  Showers redeveloping, with a chance of thunder ( especially by late ).  SW winds 10-20 mph with higher gusts.  Dense fog along upper elevation mountain ridges.  Temperatures from around 50 degrees at highest elevations in the High Knob Massif to the upper 50s to middle 60s ( warmest in lower elevations ).

Tuesday Night Into Mid-Morning Wednesday

Showers with a chance of thunder.  Downpours likely.  Gusty SW winds at 10-25 mph, with higher gusts, shifting WNW by morning and decreasing to 5-15 mph.  Mild through the overnight then turning colder during morning.  Temps widespread in the 50s, then dropping into the 40s and 30s during the predawn to mid-morning period ( coldest at the highest elevations ).  Areas of fog with widespread dense fog across the upper elevations.  Wind chills developing by morning with values dropping into the 20s and 30s.

Updated: Wednesday Afternoon

Partly to mostly cloudy ( cloudier toward the north and northwest of Wise ).  Chilly.  Winds WNW-NW at 5-10 mph, with higher gusts.  Temperatures varying from upper 30s to around 40 degrees at highest elevations to the mid-upper 40s to around 50 degrees ( warmer southward into valleys of the Clinch, Powell, Holston rivers ).

Wednesday Night Into Thursday Morning

Mostly clear during the evening, then increasing high altitude clouds overnight into morning.  Areas of fog possible, especially at lower-middle elevations.  A large vertical temperature spread developing between valleys & ridges.  Light & variable winds below 2700 feet.  Winds SW to WNW at 5-15 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures varying from low-mid 20s in high valleys to the 30s, except readings rising into 40s on higher elevation ridges by predawn-morning.

The return of a colder, wintry pattern is being monitored for the January 23-31 period.  This could begin with a major storm system, featuring high winds and a heavy rainfall to high elevation snow potential.  Stay tuned for later updates.


Weather Discussion ( Active Pattern )

Wednesday Morning Update

Low clouds are breaking up along the southeast edge of a large cloud shield, so I have updated my Wednesday PM forecast to account for this current trend.

High Knob Massif Webcam – University Of Virginia’s College At Wise
If this trend continues, afternoon temperatures will be a little milder and sunshine more abundant.  A low cloud deck will likely remain very close by, near the Virginia-Kentucky stateline, such that conditions will vary significantly over short distances along the U.S. 23 corridor.
NASA Visible At 9:30 AM on Wednesday – January 18, 2017
Turbulent mixing, enhanced by mountain waves, appears to have been able to mix out a relatively narrow inversion just above the summit level of the High Knob Massif to open up clouds.  To the northwest, by notable contrast, where mountain waves are lacking, a solid deck of clouds is continuing to hold.


Monday Evening Update

A stormy weather pattern is upcoming for the mountain region during the next 1-2+ weeks.  It is important to begin highlighting this now, as the first wave will start impacting the mountains overnight into Tuesday ( the weakest wave ).

European 51-Member Ensemble MEAN 500 MB Height Anomalies: Days 6-10

The European Ensembles remain very consistent day after day in the upcoming forecast setting, with blocking taking shape near Hudson Bay and a storm train of waves moving across the USA from west to east beneath it.

As I have already noted, many days ago, the combination of Pacific Ocean moisture ( mid-upper levels ) & Gulf of Mexico moisture ( low-levels ) with orographic forcing will make upcoming systems productive precipitation producers.  Given all the wetness of the past 7 weeks, an increasing threat for too much water will have to be respected.

As the EPO trends negative by around January 23, it will join a +PNA to help a colder pattern to develop.  Until then rain will continue to be the major precipitation form.


Previous Discussion

A very moist atmosphere continues to grip the mountain area with widespread dense fog at middle-upper elevations across Wise and Dickenson counties at the present time.

High Knob Massif Webcam – University Of Virginia’s College At Wise
The lower atmosphere has become saturated through a deep layer.
Lonesome Pine Airport In Wise
Fog has now been dense at high elevations in the High Knob Massif for the past 6 days  Only a minor break occurred when the highest elevations got briefly above the low cloud deck.  Another break, if lucky, could occur Monday afternoon with partly cloudy skies.
European Model 850 MB Temp Anomalies Analysis At 7 AM Sunday – January 15
An unseasonably warm air mass for this time of year is widespread across the USA and western-central Canada.
NWS 4 KM HRAP Precipitation Estimate – November 28 to January 12
The NWS HRAP Precipitation Estimate is too low for the City of Norton and High Knob Massif area ( above ), where totals during the November 28 to January 12 period have varied from 12.80″ in the City of Norton ( official NWS rain gauge ) to as much as 18.00″ in upper elevations of the High Knob Massif.

This is part of a wet winter season pattern that has produced a general 10.00″ to 15.00″+ of total precipitation in the High Knob Massif area ( including the City of Norton ) since the beginning of December 2016 ( several inches more if including the final couple of days in November ).

European 51-Member MEAN 500 MB Height Anomalies Forecast: Days 6 to 10

Several important weather systems will be impacting the mountain region through the next week to 10 days, with number one upcoming for late Tuesday into Wednesday when gusty showers & possible thunder will give way temporarily to a drop in temperatures.

NAM 4 KM Model Total Rainfall Forecast To 7 AM Wednesday – January 18, 2017

As the wet pattern rolls onward this week, signals for a major-league storm system continue to show up in models for the final week of January ( beginning around the Jan 22-23 period based upon current timing ).  This occurs as high latitude blocking develops over Canada with falling 500 MB heights to the south.  Confidence in this is increased since major changes are also expected in the stratosphere and polar vortex positioning through the end of January.

A setting like this typically produces a series of storms, so a very active pattern is upcoming into the extended that will feature a notable trend back toward wintry conditions in the final week of January.

Stay tuned for updates.