Category Archives: Today’s Forecast Archive

An Archive For My Forecast And Discussion

My Forecast For Today

Mountain Area Forecast ( July 18-20 )

Overnight Into Tuesday Morning

Partly-mostly clear.  Areas of valley fog.  Light winds.  Temperatures varying from mid-upper 50s to lower 60s within cooler valleys to the middle-upper 60s.

Tuesday Afternoon

Partly to mostly cloudy skies.  A chance of hit-miss showers and thunderstorms.  Light winds.  Temps varying from the 70s in upper elevations to the mid-upper 80s.

Tuesday Night Into Wednesday Morning

Chance of a hit-miss evening shower or thunderstorm.  Hazy and humid with areas of valley fog.  Light SSW to W winds generally less than 10 mph on mid-upper elevation mountain ridges.  Temps in the 60s to near 70 degrees.

Wednesday Afternoon

Partly-mostly cloudy skies.  Hazy-humid.  A chance of hit-miss showers and thunderstorms.  WNW-NW winds 5-10 mph, with higher gusts ( especially on mountain ridges ).  Temperatures varying from 70s in upper elevations to the mid-upper 80s.

Wednesday Night Into Thursday Morning

Warm & humid.  A chance of hit-miss showers & thunder-storms.  NW-NNW winds 5-15 mph, with higher gusts, on middle-upper elevation mountain ridges-plateaus.  Temps in the 60s to lower 70s.

Thursday Afternoon

Partly-mostly cloudy skies.  Hazy & humid.  A chance of hit-miss showers & thunderstorms.  Winds NW-NNW 5-10 mph.  Temperatures varying from 70s in upper elevations to the mid-upper 80s ( warmer, as per each day, at low elevations south of the High Knob Massif and in the eastern Kentucky foothills and lower sections of the Russell Fork-Levisa Fork river valleys around Haysi and Grundy ).

 

Weather Discussion ( Dog Days )

The somewhat lower humidity of recent days is being replaced by a more humid air mass, with a dominant and deep NW-N flow regime aloft developing around a large heat dome centered over the central USA.

High-Elevation Meadow In High Knob Massif – Elevation 3900 feet – July 15, 2017
The afternoon MAX reached 70 to 74 degrees at highest elevations in the High Knob Massif on Saturday, July 15, as relatively pleasant weekend conditions were observed in the high country ( nocturnal low temps dropped to 50-55 degrees within high valleys ).
To the south, by contrast, weekend conditions remained hot in the Great Valley with upper 80s to lower 90s reported from Knoxville into the Tri-Cities.
Turk’s-cap Lilies ( Lilium superbum ) Bloom In High Knob High-Country – July 15, 2017

Rainfall has been hit or miss during the past week, with a notable dry trend since the start of Meteorological Summer  ( on June 1 ) across much of the Cumberland Mountains, at least relative to what is average for this time of year.

National Weather Service Rainfall Analysis – Past 7 Days
Note heavy, locally excessive, rains to the north across Indiana and Ohio as thunderstorm clusters moved around the periphery of heat last week.  Rain was locally heavy across Dickenson-Buchanan counties & adjoining locales in eastern Kentucky and southern West Virginia as a front passed during the July 13-14 period.
Although 1.25″ of rain fell in Clintwood during July 14, only 5.26″ have been measured since June 1 ( 2.14″ below the 1981-2010 avg. ), which is also about the same as observed at Big Cherry Lake Dam.  A total of 7.68″ have been measured at Nora 4 SSE on Long Ridge of Sandy Ridge, in between these two sites, to illustrate the hit-miss nature of Summer 2017 convection.
USA Water Vapor Image At 1:15 AM on July 18, 2017
A upper low over central Virginia-North Carolina will be pushed eastward as the heat dome initially expands, with deep NW-N flow aloft that may carry debris cloudiness from thunderstorm clusters forming on the periphery of blazing heat over the Upper Midwest.

A hit-miss pattern of convective activity is expected to continue as heat builds through the remainder of this work week.  Changes will be possible by this weekend into next week, especially, as troughing develops aloft and monsoon moisture continues to flow around the big heat dome.

European 51-Member Ensemble MEAN 500 MB Height Anomalies: Day 1-5

An increasing potential for showers-thunderstorms will occur over time with a retrogression of the heat dome core, especially by later this weekend into next week ( this is the current ensemble trend ).  Stay tuned for updates.

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

070717 Forecast

Mountain Area Headlines ( July 7-9 )

1 ).  A Mesoscale Convective System will drop south to southeast toward the mountains Friday Night into the early hours of Saturday.  While a weakening trend is expected, strong to locally severe thunderstorms will remain possible as this cluster of storms approaches the Cumberland Mountains.

HRRR Model Future Doppler Radar Forecast At 1:00 AM Saturday – July 8, 2017

The main storm threats are damaging winds, lightning and heavy rainfall.  This system is expected to weaken across the higher mountain terrain overnight.

2 ).  Rain cooled outflow from this system & approach of a surface cold front will trigger new development from the morning into afternoon hours of Saturday.

JKL Doppler At 9:27 PM Friday – July 7, 2017
An outflow boundary just north of Jackson, Ky., at 9:27 PM is starting to move out ahead of the MCS, indicating a trend toward  weakening during coming hours.  Any left-over boundaries + the surface front will bear watching for new development following onset of day-time heating Saturday.

3 ).  Drier, less humid and more stable air is expected to overspread the mountains from northwest toward southeast by late Saturday afternoon into Sunday.

Lower dewpoints will make conditions feel much better from Saturday Night through Sunday Night, with notable cooling within mountain valleys ( MINS in the 50s will be widespread across the area, with coolest valleys dropping into the 40s to contrast with upper 50s to low-mid 60s on exposed mountain ridges Sunday & Monday mornings ).

4 ).  A ring-of-fire pattern will become possible next week around the periphery of a building heat dome with rising day-time temperatures early next week.

European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 4-8

A modeling trend ( ensemble mean ) is for a heat dome to set up near the Red River Valley & Texas-Oklahoma panhandles next week.  This will generate a WNW-NW flow pattern and ring-of-fire convective regime ( i.e., clusters of showers and thunderstorms will develop along the edge of the hottest air and move around the periphery of the heat dome ).

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

The eventual location of the heat dome core will need to be followed, along with the recent dry feedback tendency that has generated below average rainfall across portions of the mountain region during June-early July ( local wet feedback has also been observed as typical of patterns featuring hit-miss convective development & movement ).

063017 Forecast

Mountain Area Forecast ( Jun 30-July 2 )

The Storm Prediction Center Has Issued A Marginal Risk Of Severe Thunderstorm Development Saturday

Friday Morning Through Friday Afternoon

Predawn rain showers and rain developing ( especially along and southeast of the High Knob Massif & Tennessee Valley Divide.  Dense fog at highest elevations.  Then partly cloudy with a chance of showers and thunderstorms this afternoon.  Local downpours.  SSW-SW winds 5 to 15 mph, with higher gusts.  Temperatures varying from 60s to low 70s in upper elevations to the upper 70s to lower 80s.

Friday Night Into Saturday Morning

Chance of hit-miss showers or thunderstorms.  Partly to mostly cloudy.  Areas of fog.  SSW-WSW winds 5-15 mph, with higher gusts, on mid-upper elevation mountain ridges and plateaus.  Mild with temperature widespread in the 60s ( upper 50s to lower 60s in cooler locations ).

Saturday Afternoon

A chance of showers & downpours in thunderstorms.  Some storms could be locally strong-severe.  SW winds 5-15 mph, with higher gusts.  Temperatures varying from upper 60s to lower 70s at highest elevations to the upper 70s to low 80s.  Areas of dense fog ( orographic clouds ) at upper elevations.

Saturday Night Into Sunday Morning

A chance of showers & thunderstorms.  Winds shifting to WNW-NW at 5-10 mph, with higher gusts.  Areas of fog, especially at high elevations.  Temperatures dropping into the upper 50s to middle 60s ( coolest highest elevations ).

Intervals of showers & downpours in thunderstorms are expected through most of next week in advance of a stronger cold front that could again introduce much cooler air by the second week of July.  Many dry hours are expected between active weather.  Stay tuned for later updates on this future weather pattern.

 

Weather Discussion ( Back To Summer )

A return of humid air means that a return of more typical summer conditions, with intervals of showers & thunder-storms, will be a common feature of the forecast through the Independence Holiday period and next week.

Big Cherry Wetland Valley of High Knob Massif – June 28, 2017

Coldest mountain valleys along the Appalachians fell into the 30s, prior to this return of summer, with widespread 40s in other valleys across the Mountain Empire.

Coldest Mountain Valley Reports
( Morning Of June 28, 2017 )
Canaan Valley West Virginia
37 degrees
Burkes Garden Virginia
37 degrees
*Big Cherry Wetland Valley
38 degrees
A June 1-29 mean low temperature of 47.6 degrees was recorded in colder portions of the Big Cherry Wetland Valley ( 49.9 degrees in Burkes Garden during this same period ).
Following a very WET April-May, the month of June will end with near to below average rainfall.  Many local locations are currently in the 3.00″ to 5.00″ rainfall bracket ( as of AM on June 30 ).

 June featured a host of nice, chilly nights amid high valleys with 16 out of the 29 days of June featuring a 24-hour MIN which dropped below 50 degrees in the Big Cherry Lake Wetland Valley of the High Knob Massif.

Storm Prediction Center Risk Regions From 8 AM Saturday To 8 AM Sunday

Strong to possibly severe thunderstorm development will be possible Saturday, with formation west of the mountains  tending to move eastward.  Be sure to stay tuned to NOAA Weather Radio and your favorite media sources for any possible watches or warnings that may be issued.

062717 Forecast

Mountain Area Forecast ( June 27-29 )

Overnight Into Tuesday Morning

Increasing overnight clouds.  Small chance of a shower or sprinkle.  Light NW-N winds increasing to 5-10 mph, with higher gusts, along mid-upper elevation mountain ridges.  Temperatures in the upper 40s to upper 50s.

Tuesday Morning Through The Afternoon

Partly to mostly sunny.  Small chance of a hit-miss shower or thunderstorm.  Increasingly blue skies.  NW winds 5-10 mph.  Temperatures varying from low 60s to the lower 70s.

Tuesday Night Into Wednesday Morning

Clear.  Large vertical temperature spread between colder mountain valleys and exposed ridges.  Light winds.  Temps varying from low-mid 40s valleys to low-mid 50s on ridges, except 30s in coldest valleys of upper elevations.  Areas of locally dense river valley fog.

Wednesday Afternoon

Mostly sunny.  Mild.  SSW-SW winds 5-10 mph, with higher gusts.  Temperatures varying from 60s in upper elevations to the mid-upper 70s to around 80 degrees.

Wednesday Night Into Thursday Morning

Becoming partly to mostly cloudy.  Becoming windy across higher mountain ridges.  SSW-SW winds 5 to 15 mph, with higher gusts, on mountain ridges-plateaus below 2700 feet.  SW winds 10 to 20 mph, with higher gusts, along mountain ridges above 2700-3000 feet.  Temperatures from the upper 40s to middle 50s in cooler valleys during the evening to the upper 50s to mid 60s along gusty mountain ridges ( temps tending to rise overnight in many mountain valleys ).

Thursday Afternoon

A chance of hit-miss showers & thunderstorms.  SSW-SW winds 5-15 mph, with higher gusts.  Temperatures varying from low-mid 70s in upper elevations to the low-middle 80s.

A hit-miss pattern of showers and downpours in thunderstorms is expected to return for the close of June and opening of July, with increased humidity levels more typical of summer-time.  A front stalling near the Mountain Empire will have to be monitored by this weekend into early next week.

 

Weather Discussion ( Chilly Valleys )

A welcomed and refreshing break from summer-time humidity levels is being enjoyed this week.  Morning temperatures dipped to 48 degrees ( 47.6 ) in Clintwood Monday, with 40-45 degrees in colder mountain valleys.

June Minimum Temperature Records ( 1896-Present ) – Burkes Garden

Colder places in upper elevations will make a run at the 30s into Wednesday morning, when conditions for radiational cooling and cold air drainage ( with nocturnal inversions ) will rule mountain valleys in three-dimensional space and time.  In other words, multiple inversions amid the vertical will develop from lower, into middle and upper elevations.

If any doubt this be true, merely check the recorded history in Burkes Garden where the past 121 years have illustrated that every single June night has experienced low temps in the 30s ( or lower ) at some point in time ( a MIN as cold as 26 degrees was recorded on June 1 in 1930, with 28 degrees as late as June 26 during 1935 ).

*The undergraduate field research project at the University Of Virginia’s College At Wise is illustrating that nocturnal minimums tend to run even colder than Burkes Garden within high valleys of the High Knob Massif ( at upper elevations above 3000 feet ).
June 22-24 Storm Reports

Jackson KY NWS Forecast Office – Cindy Review

The Cumberland Mountains were lucky, pure and simple, to have escaped flooding rains and wind damage ( minor tree damage occurred locally ) that occurred last week.

*An impressive 8.42″ rainfall total was recorded at the Morehead Airport in Rowan County, Ky., during last week ( June 18-24) with torrential rains prior to and during the remnants of Cindy.
European 51-Member Ensemble MEAN 500 MB Height Anomalies: Days 1-5

The pattern continues cooler than average for this time of year during the next few days, with below average 500 MB heights centered on the Upper Midwest and Great Lakes.

European 51-Member Ensemble MEAN 850 MB Temp Anomalies: Days 1-5

The pattern gives way to one more typical of summer by this weekend into next week, and the Independence Holiday period, with rising 500 MB heights and temperatures.

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

Weak troughing in the upper air across the eastern USA indicates that the pattern will not get out of hand with heating during this period.  Temperatures near to a little above average are currently being forecast by the MEAN ensemble guidance during the first week of July 2017.

European 51-Member Ensemble MEAN 850 MB Temp Anomalies: Days 6-10

A pattern typical of summer in the mountains is expected, with hit-miss showers & downpours in thunderstorms.  The potential for more organized activity along any boundaries which stall will have to be respected amid an array of what is likely to be many dry hours in between active weather.

062317 Forecast

Mountain Area ALERTS ( June 23-24 )

A Heavy Rainfall Potential ALERT Is Now In Effect For Friday Into Saturday For The Cumberland Mountains.

The Potential For Rock-Mud Slides & Flash Flooding Will Exist With This System In Locations Along And West Of The Appalachians.

A high water content air mass associated with remnants of tropical storm Cindy will be moving across the mountains during Friday into Friday Night-early hours of Saturday.

Orographic Clouds Over The High Knob Massif
Observe wavy nature of clouds ( above ) over the High Knob Massif and the distinct band of clouds capping upper portions of the mass that helps to increase the volume of rain reaching the ground as drops fall from seeder clouds aloft ( radar beams overshoot these low-level orographic clouds and under-estimate the amount of rainfall reaching the surface over this complex terrain ).
Black Mountain Mesonet ( 0.72″ of rain during past 18-hours )

Increasingly strong & gusty SW winds + the seeder-feeder precipitation process ( orographic cap clouds ) will enhance lift and rainfall production, with torrential rains likely at times as this system moves across complex terrain of the Cumberland Mountain Overthrust Block.

NAM 12 KM Model MSLP and Precipitable Water At 8:00 AM Friday – June 23, 2017

A very moist air mass + strong low-level S-SW flow will develop rain over the mountains during Friday, with a concentrated band of system rain expected by Friday Night into early hours of Saturday.

NAM 12 KM Model MSLP and Precipitable Water At 8:00 PM Friday – June 23, 2017

Forecast models, and Doppler radars, tend to under-estimate the amount of rain that falls in this type of setting ( with rainfall during Thursday being under-estimate over the Cumberland Mountains well in advance of this system and its deep moisture ).

*Doppler beams overshoot orographic clouds and also tend to under-estimate the fine droplet-rapid fall rate nature of tropical rains moving across complex terrain.

NAM 12 KM Model Rainfall Forecast

Residents living and driving through low-lying areas and along mountain streams need to remain alert for the potential of rapid water-level rises and changing conditions Friday into Friday Night-early Saturday.

Storm Prediction Center Risk Regions

The Storm Prediction Center Has Issued A Marginal To Slight Risk For Severe Thunderstorm Development On Friday Into Early Hours Of Saturday ( June 23-24 ).

Stay tuned to NOAA Weather Radio and your favorite media sources for possible warnings that may be needed during this event.

National Weather Service Advisories As Of 3:12 AM Friday ( June 23 )

062017 Forecast

Mountain Area Forecast ( June 20-22 )

ALERT For Heavy Rainfall Potential Friday Into Saturday For The Cumberland Mountains

Overnight Into Tuesday Morning

Mostly clear.  Areas of dense valley fog.  Winds WNW-NW at 5-10 mph, with some higher gusts, on mid-upper elevation mountain ridges.  Temperatures varying from the 50s to near 60 degrees, except upper 40s to lower 50s within colder valleys at upper elevations ( above 3000 ft ).

Tuesday Afternoon

Partly sunny ( some increase in clouds during late PM ).  Light SSW-WSW winds.  Temperatures varying from upper 60s to lower 70s within upper elevations to the upper 70s to lower 80s ( warmer south into the major river valleys ).

Tuesday Night Into Wednesday Morning

Partly cloudy.  Light winds.  Temperatures varying from low-middle 50s in cooler mountain valleys to the lower to middle 60s along exposed ridges and plateaus.  Areas of dense valley fog.

Wednesday Afternoon

Partly-mostly cloudy.  SW winds 5-10 mph, with some higher gusts.  Temperatures varying from upper 60s to lower 70s at upper elevations to the upper 70s to low 80s.

Wednesday Night Into Thursday Morning

Mostly cloudy ( high cloudiness ).  SSW-WSW winds 5-10 mph, with higher gusts, on mid-upper elevation mountain ridges and plateaus.  Temperatures varying from the 50s to mid-upper 60s ( warmest mid-elevation thermal belts ).

 

Weather Discussion ( Evolution )

Predawn Of Wednesday ( June 21 ) Update

The rainfall forecast range from a host of different models and ensembles are predicting potential totals of from 2.00″ to 6.00″+ across the mountain region.  This has come down significantly from initial model projections, but remains worrisome given that orographic forcing continues to be shown as a factor ( gradient and low-level jet winds ).

Model Cluster Track For Cindy And Remnant Core

Stay tuned for continued updates on this system.

 

Previous Discussion

A nice afternoon finally graced the mountain landscape in wake of the latest rounds of showers & thunderstorms, with much less humid air being felt ( and improved visibility ).

High Knob Massif Webcam – University Of Virginia’s College At Wise
A spectacular sunset illuminated the early evening.
High Knob Massif Webcam – University Of Virginia’s College At Wise

An evolving weather pattern is the best way to describe late week into this upcoming weekend and early next week, as a radical shift in the flow regime across the eastern USA will occur.  Complicating this major change will be a developing tropical system in the Gulf of Mexico and its remnants.

European 51-Member Ensemble MEAN 500 MB Height Anomalies: Days 1-5

The forecast MEAN of the European Ensembles has a notable break in the heat ridge across the southern USA, offering a possible route for movement of tropical remnants lifting out of the Gulf of Mexico late this week into this weekend.

The cluster of many different models ( below ) agree and use this break amid the heat ridge as a pathway for movement, with this system being heavily loaded on its eastern side ( i.e., the flooding rainfall potential will be greatest along and east of its centroid ).
Forecast Model Cluster On Forecast Track Of Tropical Moisture

The model cluster initialized at 00z ( 2000 hours ) on Monday ( June 19 ) was in generally good agreement in lifting the tropical system ( possible Cindy ) toward the mouth of the Mississippi River, before recurvature to the north and northeast occurs in advance of the developing and digging Canadian trough.

Official National Hurricane Center Track

Although it is far too soon to know how much rain will fall, some scary rain numbers are already coming out of forecast models with the Monday Night European placing flooding 5.00″ to 10.00″ rains over southeastern Kentucky and far southwestern Virginia.  The 00z Canadian ( GEM ) is very similar and a little more expansive with 5.00″ to 10.00″ rain amounts extending from middle Tennessee across Kentucky into far southwestern Virginia.

The greatest concern is that the remnant moisture plume will interact with an approaching cold front and upper air trough.  That would be a worst case scenario over complex terrain.  The good news, this remains days away and there is plenty of time for changes in this current forecast.  The bad news is; however, that such a moisture plume is likely to cause flooding rains some where across the region.

European 51-Member Ensemble MEAN 850 MB Temp Anomalies: Days 6-10

The magnitude of this upper trough and amount of cold air for early summer is impressive.  Add in an approaching tropical system and it has the potential of becoming a headline, or history, making event.  

Exactly how & where this evolves is to be determined.  Please stay tuned to NOAA weather radio and your favorite media sources for updates.

061317 Forecast

Mountain Area Weather Headlines

An ALERT For The Potential Of Gully Washing Rains In Showers And Thunderstorms Is Now In Effect For The Mountain Region & Cumberland Mountains

A muggy, high water content air mass will generate showers and downpours in drenching thunderstorms during the June 13-17 period ( in hit or miss fashion ).

Folks living and driving through flood prone, low-lying locations should be aware of an enhanced risk for heavy rainfall and significant run-off through coming days.  Understand that a watch or warning may not be issued until an event develops over a localized area.

The potential exists for more widespread, organized activity later this week.  Stay tuned to NOAA Weather Radio and your favorite media sources for updates.

Updated at 10:25 PM on June 12, 2017.

060317 Forecast

Mountain Area Forecast ( June 3-5 )

A significant increase in moisture is expected by late Sunday into Monday, with showers and downpours in thunderstorms.  Locally heavy rainfall amounts will be possible before much drier air returns by June 6.

Overnight Into Saturday Morning

Clear.  Seasonally chilly.  Large vertical temperature spread between colder mountain valleys and milder ridges.  Light winds.  Temperatures varying from 39 to 43 degrees in the coldest mountain valleys to the mid-upper 50s along milder mountain ridges.  Areas of dense river valley fog.

Saturday Afternoon

Sunny.  Beautiful blue skies.  Light northerly winds.  Temps varying from low-mid 70s in upper elevations to the lower to mid 80s.

Saturday Night Into Sunday Morning

Clear.  Large vertical temperature spread developing between colder mountain valleys & milder ridges and plateaus.  Light southerly winds along mid-upper elevation mountain ridges.  Temperatures varying from 40s in the colder mountain valleys to the low-mid 60s on exposed mountain ridges.  Areas of dense river valley fog.

Sunday Afternoon

Increasing clouds.  More humid.  A chance of showers and thunderstorms.  Local downpours.  SW winds 5 to 10 mph.  Temps varying from low-mid 70s in upper elevations to the low-mid 80s.

Sunday Night Into Monday

Warm & humid. Showers & downpours in thunderstorms.  Locally heavy rain amounts.  SW-W winds 5-15 mph, with higher gusts, on mid-upper elevation mountain ridges.  Areas of fog, especially at upper elevations.

A period with showers and downpours in thunderstorms will be followed by another spell of below average temperatures ( chilly nights in mountain valleys ) next week ( as Florida turns wet ).

 

Weather Discussion ( Cool Nights )

A chilly night is underway in the mountains, with light winds and clear skies generating large vertical temperature spreads between colder valleys and exposed ridges.

Chinese Dogwood & Chestnut Trees In Bloom – June 2, 2017
Gorgeous blue skies observed Saturday afternoon indicated that low dewpoint air had advected into the mountain area.  This sets the stage for coldest valleys to drop into the upper 30s to low 40s in contrast with 50s along exposed ridges and plateaus.
NAM 12 KM Model Precipitable Water Forecast At 8:00 AM Saturday ( June 3 )
A very low precipitable water atmosphere ( above ) will be in place through Saturday into Sunday morning to allow for large diurnal temperature changes between night and day.  Note the tropical moisture across the Gulf of Mexico and Florida.

A large diurnal ( day-to-night ) temperature spread will also be observed into Sunday, with rapid warming by day giving way to another significant temperature drop in mountain valleys during Saturday night into Sunday morning.

NAM 12 KM Model Precipitable Water Forecast At 11:00 PM Sunday ( June 4 )

A significant increase in moisture is expected by late Sunday into Monday, with development of showers and downpours in thunderstorms ahead of a upper air trough and surface cold front.  Much drier air is expected to then return by Tuesday ( below ).

NAM 12 KM Model Precipitable Water Forecast At 8:00 AM Tuesday ( June 6 )

This will mark the beginning of an unseasonably cool period, with more chilly nights in the mountains.

European 51-Member Ensemble MEAN 850 MB Temperatures: June 6-10

As I alluded to before, rising air in association with a plume of tropical moisture and deep convection across Florida and the Gulf Coast will contribute to this next cool period ( some may call it Elderberry Winter ) via synoptic-scale sinking of air ( subsidence ) over the southern-central Appalachians.

053117 Forecast

My Area Forecast ( May 31-June 2 )

Overnight Into Wednesday Morning

Partly to mostly cloudy.  Small chance of a shower or sprinkle.  Areas of valley fog at lower elevations.  Light and variable winds.  Temperatures varying from the upper 40s to lower 50s in high mountain valleys to the mid-upper 50s.

Wednesday Afternoon

A chance of showers & thunderstorms.  Local downpours.  Winds SW-W at 5-10 mph, with some higher gusts.  Temps varying from 60s upper elevations to the lower-middle 70s.

Wednesday Night Into Thursday Morning

A chance of showers & thunderstorms.  Local downpours possible.  Winds SW-WNW at 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges.  Temperatures mostly in the 50s.

Thursday Afternoon

Partly to mostly cloudy.  Chance of a hit-miss shower or thunderstorm, especially along and south of the High Knob Massif and Tennessee Valley Divide.  Winds W-WNW at 5-10 mph with higher gusts.  Temperatures varying from 60s at upper elevations to the mid-upper 70s.

Thursday Night Into Friday Morning

Partly to mostly cloudy.  Winds becoming light.  Seasonally cool with temperatures varying from 40s to lower 50s in the colder mountain valleys to the middle-upper 50s.  Areas of fog at lower elevations.

*More humid air will feature numerous showers and downpours in thunderstorms during Saturday and Sunday ( June 3-4 ).  Some of the thunderstorms could become strong to locally severe.

 

Weather Discussion ( SOS Into June )

Although any dry hours this week will be enjoyed, along with brief reductions in humidity, a return of more humid conditions into this weekend means that showers and downpours in thunderstorms will also be roaming the mountain landscape.

Vegetation Flourishes Amid Spring 2017 Wetness – Big Cherry Lake ( May 28 )

Spring 2017 has been wet across the region, with the second month in a row producing a general 8.00″ to 10.00″ of rain within the High Knob Massif ( after 5.00-7.00″ in March ).

May 1-30 Rainfall Totals

City of Norton
7.88″

Clintwood 1 W
8.49″

*Big Cherry Dam
10.05″

*The past 6 months have generated a general 47.00″ to 56.00″ of total precipitation in the High Knob Massif area ( around 52.00″ estimated on average at upper elevations ).  This translates to a general 8.00″ to 9.00″+ per month for the past six months.

There are some model signs that a more prolonged break in this very wet pattern could occur but, and this is a big but, such a break remains uncertain.  It might actually become more likely if a tropical or a tropical-like system develops far to the south and tracks across Florida and off into the western Atlantic Ocean.

Such a track could ideally place the Mountain Empire under a subsidence, or sinking air, regime around the periphery of the system ( especially if it were to strengthen a little ).

European Model Forecast 500 MB Height Anomalies: Days 1-5

A break is uncertain since the European Ensemble MEAN  continues to show a tendency toward showers & storms along and just west of the Appalachians through the next couple of weeks.

European Model Forecast 500 MB Height Anomalies: Days 6-10
The latest European Model is going with a synoptic-scale sinking air regime centered over Canada, but not along the Appalachians.

Perhaps the biggest factor, as often is the case at this time of year, is soil moisture with significant evapotranspiration to supply latent energy for formation of more showers and thunderstorms.  A wet feedback can be hard to overcome at this time of year, and would likely require a synoptic-scale forcing mechanism ( to generate significant subsidence ).

052817 Forecast

Mountain Area Forecast ( May 28-30 )

ALERT For High Water Levels And Flooding In Low-lying Locations Along The South Fork of the Powell River and Big Stony Creek of the Clinch River

More than 3.00″ of rain fell over the Big Cherry Lake basin and adjacent locations into Saturday evening ( May 27 ).  ROARING water and dangerously high levels will continue into Sunday.

The Storm Prediction Center Has Issued A Marginal Risk For Severe Thunderstorm Development Sunday

Thunderstorm development Sunday will largely be dependent upon cloud coverage and if the stabilizing overnight atmosphere can recover ( become unstable ) during the day.

*Downpours Of Flooding Rain Will Remain Possible Throughout The Memorial Day Holiday Period

Due to a super-saturated surface layer, and high rates of evapo-transpiration ( a positive moisture feedback ), showers and any thunderstorms which develop will remain capable of producing heavy rainfall and possible localized flooding.  

Overnight Into Sunday Morning

Low clouds.  Areas of fog.  A chance of showers.  Thunder possible.  Winds SW at 5-10 mph, with higher gusts, along mid-upper elevation mountain ridges.  Temperatures from mid-upper 50s to the lower 60s.

Sunday Afternoon

Mostly cloudy.  A chance of showers and thunderstorms.  Any storm could become strong-severe.  Local downpours.  SW winds 5-10 mph, with higher gusts.  Temperatures in the 60s to lower 70s.  Dense fog possible at upper elevations ( i.e., orographic clouds ).

Sunday Night Into Memorial Day Morning

Mostly cloudy.  A chance of showers and thunderstorms.  Local downpours possible.  SW-W winds 5-10 mph, with higher gusts, along mid-upper elevation mountain ridges.  Temperatures in the 50s to lower-mid 60s ( coolest at the highest elevations ).  Dense fog in upper elevations, with areas of fog at middle-lower elevations.

Memorial Day Afternoon

Mostly cloudy.  A chance of showers and thunderstorms.  Local downpours possible.  SW-WSW winds generally less than 10 mph.  Temperatures varying from 60s in upper elevations to the lower-middle 70s.

Monday Night Into Tuesday Morning

Mostly cloudy.  A chance of showers.  Thunder possible.  SW-W winds 5-10 mph, with higher gusts, along middle to upper elevation mountain ridges-plateaus.  Temperatures varying from 50s to middle 60s ( coolest at highest elevations ).

 

Weather Discussion ( Saturated )

The mountain landscape is not only saturated, it is super-saturated, in wake of a wet Spring 2017 and torrential rain producing thunderstorms on Saturday ( May 27 ).

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

Cumulonimbus clouds & orographic mountain waves, as well as low-level orographic clouds ( across Little Stone Mountain Gap and the Powell Valley Overlook area as seen at lower right of below image ), formed as severe thunderstorms with flooding rains, damaging winds, and vivid lightning developed Saturday afternoon-evening.

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

Rapid convective development occurred during the mid-late afternoon hours of Saturday, with overshooting cloud tops and gravity waves, indicative of vigorous upward motion, clearly seen on new GOES-EAST Imagery ( below ).

NASA Visible Image With Overshooting Tops And Gravity Waves

Although the amount of convective formation is uncertain during Sunday, the situation is now so saturated that a wet feedback for rain shower development means that it will take little upward motion to trigger new activity ( i.e., even showers without thunder will be capable of downpours ).

Any breaks within the overcast will make showers-storms nearly certain to develop amid this “jungle-like” setting.

Storm Prediction Center Risk Regions From 8 AM Sunday To 8 AM Monday

It is hoped that Memorial Day afternoon will be dry, but for now I have left a chance of showers-storms in the forecast until it is seen if somewhat drier low-level air can actually reach the Cumberland Mountains ( stay tuned for updates ).

European 51-Member Ensemble MEAN 500 MB Height Anomalies: Days 1-5

The continuation of mean upper air troughing + wet ground means that this unsettled pattern will continue into early June, with dry periods to be savored in between showers and thunderstorms.

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

While generally humid, the cooler than average temp regime observed since May 21 will also continue.

European 51-Member Ensemble MEAN 850 MB Temp Anomalies: Days 1-5

Although this pattern can certainly change, wet ground and abundant evaporation + transpiration heading into summer often develops a feedback that helps to maintain a setting which is unsettled via input of abundant moisture into the atmosphere ( latent heat energy for storm formation ).

European 51-Member Ensemble MEAN 850 MB Temp Anomalies: Days 6-10
*Positive and negative feedbacks are an important part of every summer season and are driven largely by soil-vegetative moisture inputs ( or the lack thereof ) into the overlying air.  Seasons with abundant moisture input into the lower atmosphere often trend wetter and cooler than average versus those which feature dry ground and reduced evapotranspiration ( ** ).
**Cooler by day, especially, since drier summer seasons in the mountains can feature anomalous nocturnal coldness at times ( with frost-freezing temperatures having been observed during every month of the year amid high mountain valleys, sometimes this may be due to low dewpoint air behind strong summer fronts…but in seasons like Summer 1988 it was largely due to developing drought conditions ).