ALERT For Heavy, Wet Snow Developing Along And N-NW Of The Cumberland Front During The Predawn-Morning Hours Of Monday (14 Dec 2020)

NOTE: The main departure from this will also include the area along and northwest of Clinch Mountain, northeast from Brumley Mountain, for the heavy snow potential

I am concerned about a crippling fall of snow. The potential is there based upon the setting and well documented, past events. Crippling in terms of the snowfall rates and also for the possibility of power outages. To be honest in every way, the potential exists for either a non-event or a crippling event. Reality may be in between these extremes, however, I must make everyone aware of this crippling threat.

Snowfall Forecast

2″ to 6″ below 3000 feet

6″ to 10″ above 3000 feet
with locally higher depths

Target Snowfall: 4.0″ in Norton-Wise (+/- 2.0″ error potential) implying the potential for 2″ to 6″ of snowfall through early afternoon Monday (14 December).

The deepest snow depths of more than 6″ are expected at upper elevations in the High Knob Massif and highest portions of Black Mountain. The majority of precipitation is expected to be snow at the summit level of the High Knob Massif, where 10″ or more could accumulate in a furious fall of heavy snow.

The above forecast is for locations along and northwest-north of the Cumberland Front.

This first wave presents a relatively easy forecast for locations toward the south into the Clinch, Powell, and Holston river valleys where it will be mainly a rain-mix event with limited to no snow accumulation, and to the northeast along the Allegheny Front of the highlands of eastern West Virginia where upper air temperatures will be colder to support mainly a snow event.

In the middle along the Cumberland Front, northeast from Cumberland Gap, it will be a war and the forecast bust potential will be much higher than average.

Forecast models are literally divided between a non-event and a heavy, pounding event that could include potential for power outages and downed trees.

Rain will overspread the mountain region initially, then processes that work to cool the air will become the main focus for locations along and just north and northwest of the Cumberland-Allegheny Front.

This forecast is leaning toward more wet snow based upon already observed, documented past climatology of events possessing an analogous surface low track and surface to 850 MB air flow trajectories.

Although no two forecast settings are identical, the reasoning for my lean toward wet snow is sound based upon past observed events and meteorology.

Column cooling, supported by dynamics, will develop downward via entrainment of cold air at higher levels as low-level northerly upslope flow develops to begin the process of low-level cooling via orographic lifting.

If these processes phase earlier in the event, a crippling snow could occur versus if they occur later during the event (that is the big unknown that gives this forecast setting a higher than average bust potential).

Anyone who is a student of past climatology should recognize this crippling potential immediately, given many have occurred and a few are even documented on the High Knob Landform website (even though it only came online during Summer 2009).

Storm Report At 1:50 AM on 14 December 2020

Snow began falling at the summit level of the High Knob Massif by around 1:00 AM, with sticking to roads by 1:30 AM (a gravel lot above at 1:50 AM).

It is likely that roads will become near impassible at these upper elevations by morning as winds shift and become stronger out of the north.

Snowfall Potential Increasing

High-latitude blocking over Greenland is expected to impact upper air waves moving across the continental USA next week.

This is part of a pattern that currently features favorable Atlantic Ocean Basin teleconnections for wintry conditions across the eastern USA, with negative phases of both the Arctic and North Atlantic oscillations.

The European ensemble mean is more negative than the GFS ensemble mean, but there are signs of warming during Christmas week. That remains to be seen as time gets closer to the Holiday period.

An initial (weaker) wave will support the first potential for accumulating snowfall into Monday (14 December), with a stronger secondary wave being monitored for the middle of next week (16-17 December 2020).

While the Pacific Ocean basin is supporting teleconnections in opposition to wintry conditions across the eastern USA, in general, there has been a trend toward +PNA by the middle to end of this coming week (centered on 17-18 December 2020).

Warm forcing from the Pacific Basin will attempt to win out in the longer term (Christmas Week into January 2021).

Potential Impact of First Upper-Wave

Advisory to local warning level amounts of snow are being highlighted by different model groups for an upper wave predicted to cross the Appalachians into Monday, with accumulating snow developing locally between midnight-sunrise on Monday (14 Dec 2020).

The European Model group (not shown) and NAM Model group are in general agreement with placement of an axis of moderate to locally heavy snow along and northwest of the Allegheny-Cumberland Front. The new ICON (German) Model and GFS run are also in basic agreement.

The Canadian Model (GEM Operational) remains the single model of the big groups to predict very little to no snowfall through Monday.

Extended Outlook – Toward Christmas

Although the extended outlook to Christmas, released today, from NOAA looks like a blow-torch, all hope is NOT yet lost for a White Christmas.

Above average precipitation is a notable indication of storminess, and there are some other signs of a variable up-down pattern as forcing factors in the Atlantic (cold) and Pacific (warmer) continue to battle for control.

Stay tuned for later adjustments.

Autumn Color 2020_High Knob Massif Area

Autumn color has advanced significantly across the area since the beginning of this week, with conditions on 9 October featuring an array of nice colorations across many locations along and north of the High Knob Massif (Clintwood-Pound to Norton-Wise), with this weekend (10-11 October) through next weekend (17-18 October) expected to offer some of the best color above 3000 feet.

If color continues to advance rapidly below this elevation, a general peak will occur by 17-18 October in locations along and northwest-north-northeast of the High Knob Massif.

As autumn color begins peaking at upper elevations, remnant rains from Hurricane Delta will overspread the mountain region this weekend, with additional showers and thunderstorms into early next week.

Moderate to heavy rainfall, wind driven within upper elevations, will be detrimental to some leaves.

Time will tell what impact it has on the general peak, with brightening color on some trees as other trees experience leaf drop into next week. Trees with bright color currently, standing within exposed locations, will be at greatest risk of leaf fall.

Models are forecasting a general 1.00″ to 4.00″, with locally more in favored upslope locations and less in downslope locations on general SSE-SSW air flow trajectories across the southern Appalachians.

Heaviest rains are expected Sunday as the remnant core of Delta pushes across the region.

Colder Trend – Second Half of October

A colder trend in modeling is showing up during the second half of October, with high latitude blocking predicted to develop within positions that favor enhanced eastern USA upper air trough formation.

The 14th Annual High Knob Naturalist Rally will continue virtually through this week and next.

High Knob Hellbender 10K Race

Weather conditions for the 7th Annual Hellbender 10K will be nearly ideal this year, with light southwest winds and seasonally chilly conditions under partly to mostly sunny skies (featuring fair weather cumulus).

Frosty cold sunrise conditions in the Norton Valley will warm quickly through mid-morning. Air temperatures in the 40s (4° to 9° Celsius) can be expected along the course that follows a 10:00 AM start time Saturday.

Expect air to dry with increasing elevation. A drop in relative humidity values will occur above the valley floor, toward the summit level of the massif, through mid-morning into mid-day Saturday.

Mountain Valley Frost

Areas of frost were featured in colder valleys Friday morning, such as in the Norton Valley which had temps analogous to the summit level of the High Knob Massif (the main difference being low-mid 30s accompanied wind chills in the 20s at the summit).

NOTE: Significant differences are typical on these mornings between the Norton Valley and adjacent Wise Plateau, with colder temperatures and enhanced frost on the floor of the Norton Valley (including the Big Laurel to Esserville and Ramsey to Tacoma corridors), and low spots within the plateau, often contrasting with milder, frost-free conditions in exposed locations of the Wise Plateau and higher places within the City of Norton.

Forecasters should not confuse Norton with Lonesome Pine Airport in Wise (especially for those following obs), as they are within two distinctly different topographic settings with significant weather contrasts on nights featuring radiational cooling and cold air drainage.

The Norton Valley is influenced by cold air drainage from both the High Knob Massif and northeastern end of the Black Mountains versus the Wise Plateau which features only localized drainage into lower sections, especially those once known as The Big Glades.

Latent heat of condensation associated with fog formation will help to prevent or minimize any frost formation along major river valleys and near the larger, lower-elevation lakes.

River valley fog will continue to be a nocturnal feature, as typical at this time of year, to contrast with below freezing conditions developing overnight into Saturday morning within the colder, high elevation valleys from the High Knob Massif to Burkes Garden.

Cooler-Drier Than Normal Short-Term

Generally cooler and drier than average conditions will continue to dominate the short-term forecast period into next week, when a warming trend develops.

A drier pattern is very welcome in wake of wetness, with the past year featuring 100.29″ of total precipitation at Big Cherry Lake Dam in the High Knob Massif.

Big Cherry Dam Breaks 100.00″ During Past Year

Reference the above link for other totals observed during the water year from October 2019 to September 2020.

The 14th Annual High Knob Naturalist Rally will continue virtually through this week and next.

First Major Autumn Cold Front

The first major cold front of the autumn season to transport polar air southward will begin impacting the mountain area Monday Night into Tuesday. A marginal risk of severe storms will be possible along and just ahead of the cold front.

While localized showers and areas of drizzle will be possible Monday, the main shield of rain-embedded thunderstorms will spread across the mountains Monday night. Downpours and a sharp drop in temperature are expected overnight as winds shift northerly into Tuesday morning.

Be alert for water level rises and ponding of water within poor drainage, low-lying locations overnight into Tuesday morning

Cloud bases are expected to lower on upsloping winds that will shift northerly behind the cold front, with lifting of moist air up across middle-upper elevations along and southeast of the Virginia-Kentucky stateline (especially in locations along and N-NW of the High Knob Massif-TN Valley Divide).

ALERT For Dense Fog Development Tuesday At Middle & Upper Elevations Along-North Of The High Knob Massif-Tennessee Valley Divide On Upsloping Northerly Winds

Recall my elevation breakdown for forecasting is:

Below 2000 Feet = Lower Elevations
2000-3000 Feet = Middle Elevations
Above 3000 Feet = Upper Elevations

Expect temperatures mainly in the 40s to around 50 degrees at mid-upper elevations Tuesday in locations along and north of the High Knob Massif-Tennessee Valley Divide (with colder wind chills at higher elevations)

The 14th Annual High Knob Naturalist Rally will continue virtually through this week and next.

In the wake of general 1.50″ to 2.00″ rains over the high country there was an array of orographic and lenticular cloud formations.

Watch the right, sunset lit side of the slides during the darker images around sunset to best see stacked, lenticular mountain waves that are nearly stationary and extend across a much larger portion of the massif (opening slides show lingering, orographic cap clouds in wake of rains).

Remnant rains of Beta pushed the 12-month precipitation total at Big Cherry Dam to nearly 100.00″ (98.89″), which may be broken by the end of September.

Interactive Doppler Radar-Lightning Detection System

Previous Discussion

Rainfall late Thursday Night into early Friday is expected to become enhanced as tropical moisture interacts with the right-rear entrance region of a strong jet streak aloft.

Interactive 250 MB Jet Stream Streamline Field_USA

The Big Chill Is Coming

*Looking ahead, to the end of September and early October, an early winter-like pattern will be taking shape with much below average temperatures looking increasingly likely across the eastern portion of the USA.

While the GFS Ensemble pattern is impressive, the European Ensemble Mean is even colder and more impressive for the first few days of October. Air becomes so cold, in fact, that the first flakes of snow may fly along the Appalachians (especially at upper elevations) if the ECMWF ensembles are on target.

Certainly this would not be that unusual for the mountains, with accumulating snow common at upper elevations in the High Knob Massif during October (strong cold air intrusions being detrimental to autumn color along highest crestlines).

At the least, a pattern favorable for widespread frost and freezing temperatures will be developing into early October.

ALERT For The Potential Of Excessive Rainfall Into This Weekend

Previous Discussions

More than 2.00″ of rain fell in the Pound area of northern Wise County (2.28″ measured in Pound Gap near U.S. 23) late Wednesday, beneath slow moving thunderstorms.

Heavy rain potential will continue through this upcoming weekend, with excessive local rain amounts being likely.

This is part of a stormy, late summer pattern that is expected to continue through the next one to two weeks (reference increasing upper air trough formation over the eastern USA on these mean, 51-member European Model forecasts).

Derecho Recap_10 August 2020

An event that sparked my interest in weather as just a kid was associated with a gustnado that formed along an outflow boundary. I have been interested in these types of events ever since. The following links highlight what will be recorded as a historic Derecho event.

At least 10 Million acres of corn in Iowa alone, were destroyed by a classic Derecho that blasted across the Midwest on 10 August 2020.

This is estimated to represent more than 1 Billion bushels of corn and a loss of at least 3.4 Billion dollars (just in Iowa). This Derecho impacted more than 800 miles of varied landscapes, much of it in the nation’s heartland.

The peak recorded wind gust reached 112 mph in Cedar Rapids, Iowa.

Inside The Iowa Derecho_Nick Stewart (KGAN-TV)

Corn can be seen in a portion of Nick’s video, as part of a live broadcast associated with KGAN-TV during the event. A link to the full broadcast is below:

KGAN-TV_Rebecca Kopeland and Nick Stewart

The Derecho remained a potent force through Illinois, as it turned southward toward the Ohio River before weakening below severe limits.

Andrew Pritchard_Storm Chaser_In Illinois

NOAA highlights a GOES-16 visible loop of the Derecho, with lightning overlain.

GOES Watches Derecho Slam Midwest_NOAA

Derecho Definition And Facts_Storm Prediction Center

A long-lived wind damage producing system of organized, severe thunderstorms will approach the Appalachians overnight.

Interactive Storm Reports_NOAA-NWS

At this time, weakening is expected, however, this must be closely monitored and a severe potential will exist until it is seen that the system dissipates upstream of the local mountains. A right turn into most unstable, energy-rich air toward western and central Kentucky is likely.

Wind damage often continues as the system weakens with a downward transfer of high momentum air to the surface, such, that I include this in the term “dissipates” that extends somewhat beyond disappearance of stronger radar echoes.

It appears that locations toward Cumberland Gap will be at higher risk, versus locations to the north and east, but please stay tuned to NOAA weather radio and your favorite media sources for updates on this evolving situation.

Interactive Full-Screen Doppler Radar

Rounds of showers and downpours in thunderstorms will impact the mountain region through this week into the upcoming weekend.

Interactive Lightning And Storm Tracking Doppler

Showers and thunderstorms Monday will initially impact southwestern portions of the region, with a general east to northeast expansion of the impact zone from Tuesday into mid-late week.

While the placement of heaviest rain varies on nearly every model run, the idea of locally heavy to excessive amounts in localized places is what needs to be monitored.

Development of upper-air troughing over the eastern USA, in combination with a break in the heat ridge across the Deep South, will support increasing chances for showers & downpours in thunderstorms through mid-late week.

Weather Headlines

A late summer weather pattern, with daily chances for showers and local downpours in thunderstorms (mainly hit or miss during afternoon and early evening hours), will continue through coming days.

A notable difference being cooler temperatures, versus average, for this time of year, with more typical August heating not returning until later this weekend into next week when the atmosphere expands vertically.

Previous Discussion

Interactive Lightning And Storm Tracking Doppler

Tropical Storm Isaias, which is likely to become a hurricane once again, will dominate regional weather conditions through early this week.

Although wind shear will increase again beyond 24-hours, Isaias is in position for intensification late Sunday and will later develop more extensive impacts due to enhanced upper-level divergence within the right-rear quadrant of a upper-level jet streak.

Isaias will become absorbed, or partially absorbed, into a upper-level trough, the axis of which (below) was over the Mississippi River Valley at 8:00 PM Sunday, and will become a more potent weather maker for the entire expanse of the eastern seaboard Monday into Wednesday. Isaias will be a potent rain producer given upper-level divergence aloft lifting tropical moisture vertically above a major population corridor.

I like the European Model and its ensemble mean best for handling of the upper-level dynamics, although both the GFS and high-resolution NAM are in general agreement, with indirect rain and thunderstorm development likely in the southern-central Appalachians.

With deep low pressure (Hurricane Isaias) moving across the eastern Carolina’s and Virginia, inflow and terrain convergence, in association initially (at least Monday) with upper-level divergence, will favor shower and thunderstorm development along both flanks of the Appalachian chain.

Locally strong-severe thunderstorm development will be possible.

Stay tuned to NOAA Weather Radio and your favorite media sources for possible alerts and warnings which may be needed through early this week.

Monitoring A Flood Potential

*An Enhanced Flash Flood Risk Is Expected Thursday Into Friday (30-31 July 2020)

3:00 PM Update_Friday_31 July 2020

Thunderstorms developing over central portions of Kentucky and Tennessee represent the next wave to impact the mountains into late afternoon-evening.

A southwest to northeast corridor with a heavy to excessive rainfall potential will be present into this evening and night.

A boundary from the Kentucky Foothills into the mountains along the Virginia-Kentucky border will need to be closely monitored for the potential of enhancement and training.

Antecedent Conditions = Run-off & Saturated Soils

Heavy rains have Big Cherry Lake overflowing, and water gushing through South Fork Gorge, following a dry first-half of July that dropped the lake level 2 feet below its spillway (this rise represented more than 75 Million gallons of water gained in the lake, and much more within the basin_not including overflow).

Reference the High Knob Landform for more information.

A total of 5.62″ of rain fell at Big Cherry Dam during the 27-31 July period, including 1.66″ of overnight rain since midnight this morning (31 July).

A potential for locally strong-severe thunderstorms, in addition to the flood potential, will continue through this weekend.

Previous Discussions (Below)

Following Thursday afternoon convection, that dropped 0.98″ of rainfall in Clintwood and up to 1.75″ at Big Cherry Dam in the High Knob Massif (where orographic feeder clouds were present…see images), I am now monitoring the potential for new convection and heavy rains to develop into the overnight as orographic forcing increases on southwesterly inflow.

Doppler radar tends to under-estimate rainfall amounts when orographic pilatus clouds are present and capping the High Knob high country. Why? Because radar detectable rain drops falling aloft out of seeder clouds (be them thunderstorm towers or other nimbus types) become enriched by falling through thick terrain capping clouds = increased rain volume with more rain reaching the surface than detected by Doppler radar.

The problem at hand, then becomes one of a SW low-level jet of unseasonably strong winds (given this is the convective season when organized winds are lacking in the mean) that will push upon the terrain.

The high-resolution NAM is nearly identical to the latest 18z European Model in forecasting this first wave of enhanced winds, with additional jets of enhanced low-level wind predicted at times through the upcoming weekend.

Since air can not go downward into the solid ground, the only option will be an increase in surface-based upward vertical motion. Not be a problem in a stable air mass, but with any instability in a high (rich and tropical) precipitable water air mass there is the potential for trouble.

The mountains are not merely static entities, as they counter atmospheric pushing with a torque (in this case, it is a Positive Mountain Torque force).

The Bottom Line…Remain ALERT for the potential development of heavy rains into the overnight and Friday (day-time).

A surge in precipitable water values to well above 2.00″ in combination with SW-W low-level inflow and convergence along the mountains is expected to enhance the potential for heavy rain and thunderstorms Thursday into Friday.

The location of any flooding can not be known for certain until actual rain-thunderstorms develop.

A moisture rich air mass is expected to combine with a stalling frontal boundary, and waves of low pressure, to support repetitive rounds of showers & downpours in thunderstorms during coming days.

Interactive Lightning And Storm Tracking Doppler

A main focus is expected to develop by late Thursday into Friday (30-31 July), with any accumulated rain prior to this period acting to increase soil moisture and the flooding risk.

While the NAM Model is faster than the European Ensemble Mean, there is general agreement in a heavy to excessive rainfall potential developing this week.

Part of a stormy pattern likely to continue during the first week of August 2020.

The core of a strong heat dome retrogrades into the southwestern USA as a positively tilted upper trough deepens over the eastern USA.

This locks in a stormy, wet weather pattern.

Weakening of the western extent of the Bermuda High ridge could be an ominous development (should it occur as now predicted) for tropical activity, and at the least an aid to the feed of deep, tropical moisture into the eastern USA.

All Conditions Are Connected

It is no surprise to residents that far southwestern Virginia and southeastern Kentucky are among the foggiest area’s in the United States, with nocturnal fog formation along river valleys nearly every night from summer into autumn within the ecologically diverse river basins forming headwaters of the Upper Tennessee, Upper Cumberland, and Upper Ohio river systems.

The moisture visible as fog may disappear from human sight, with a phase transition from liquid to vapor, but energy represented remains and more often than not helps to fuel development of day-time showers and thunderstorms.

This is all part of a positive feedback loop that plays a simply vital role in the summer precipitation and air temperature regime.

Afternoon air temperatures across Virginia during this time (below) varied from 60s in the High Knob Massif, and City of Norton, to around 100 degrees in the Tidewater of far eastern Virginia.

Weather Headlines

A heat dome will be expanding eastward across the USA this week into the upcoming weekend, with warm (upper elevations) to hot (lower elevations) mid-summer conditions.

Interactive Lightning And Storm Tracking Doppler

Instability driven, hit or miss, showers and downpours in thunderstorms will begin developing by later this week into next week.

While instability driven convection is mainly diurnal, favoring day-time hours, clusters of storms that develop in a ring of fire pattern can occur at any time of day or night and often favor night-time hours when they can undergo up-scale growth with increased low-level inflow.

Clusters of organized thunderstorms developing along the edge of heat will also become possible. These are often called “Ring of Fire” storms.

July rainfall totals have varied from 0.50″ or less to more than 3.00″ during this first half of the month, with much of the region running below average.

Climate System Feedback Loops

Have you ever wondered or became frustrated by, especially as a farmer or gardener, the hit or miss nature of summer showers and thunderstorms?

While part of this reason is related to the natural, chaotic nature of thermal convection, it is also due to positive feedback loops that develop between the surfaces of Earth and the overlying atmosphere.

I first started looking at feedback loops in the 1990s, as part of the seasonal variability of summer-time convection across three-dimensional terrain of the Mountain Empire.

Whether it be the long-term climate system, or a short-term weather pattern, feedback loops are critical components that function to either amplify or dampen the response to forcing mechanisms.

Feedback loops, by definition, change the sensitivity of the response to forcing.

*In this way, it becomes easier to understand how a synoptic-scale pattern, conducive to either wetness or dryness, can become amplified by a positive feedback loop which is naturally unstable in that it acts to push a set of conditions farther away from the initial state over time (that is, wet ground may become wetter and dry ground drier as time passes).

*Nothing in the climate system is ever as simple as it might appear. That is certainly true within complex, three-dimensional terrain where any given system that may be able to generate orographic forcing could potentially overwhelm a positive feedback for continuation of dryness or wetness. Orographic forcing tends to be limited in both duration and strength during the convective (warm) season, but can occasionally become a significant factor in rainfall enhancement [especially over smaller temporal-spacial scales versus the orographic forcing (cold) season (Nov-April) when widespread regional impacts are common].

A simplified (+) feedback loop runs like this, an initial increase in rainfall leads to an increase in soil moisture, which acts to increase evaporation and transpiration (evapotranspiration) from surfaces into the overlying atmosphere where water vapor increases within the troposphere.

A water vapor increase then aids production of additional rainfall (via thermal instability and associated differential heating and latent heat release) to continue this positive loop for amplification of wetness.

On the other hand, an initial decrease in rainfall leads to a decrease in soil moisture, which acts to decrease (reduce) the rate of evaporation and transpiration from surfaces into the overlying atmosphere where water vapor decreases.

A decrease in atmospheric water vapor then acts to hinder production of rainfall to continue and amplify this positive feedback for dryness.

The solid black line connecting the Latent and Sensible heat flux boxes indicate that they are connected in the surface energy balance, and while a moist surface will be dominated by the latent flux and a dry surface by the sensible flux, in reality, they may both operate at the same time with varying magnitudes dependent upon the moisture present within a given location (as suggested).

If you are a student of climatology, you already know where this is heading. This simplified feedback loop (at the top) becomes complicated by fluxes of energy driven by solar radiation and phase changes of water (surface energy budget graphic).

While the overall feedback remains positive, I have included a couple of negative couplings between soil moisture and sensible heat flux as well as between latent heat flux and temperature.

When soil moisture is present, and especially elevated, some of the incoming solar radiation from the sun (called insolation) will be diverted and used for evaporating water and for driving transpiration through vegetation. In other words, a soil moisture increase will tend to amplify the latent heat flux and diminish (dampen) the sensible heat flux such that air temperature tends to be lower when moisture is present for evapotranspiration.

When soil moisture is lacking, and especially decreasing, nearly all of the insolation from the sun will be applied to sensible heating of surfaces which then act to heat up the overlying air. So a lack of soil moisture increases the sensible heat flux, forming a negative coupling (blue arrow above graphic), and the sensible heat flux dominates the surface energy budget to cause air temperature to increase.

The bottom line, there is strong correlation between soil moisture and air temperature during summer, with dry ground tending to support hot temperatures and wet ground supporting cooler, but often more humid, conditions (hotter by daytime, as dry ground often supports cool nights, especially within the mountains)…such that positive feedbacks tend to exert significance influence upon summer-time weather conditions.

Upcoming Weather Pattern

A major weather shift has occurred during July, with a transition from cooler than average conditions (in the mean, below) during May and June giving way to above average July temperatures and a significant drying (above) of surface soils (in the mean).

NCEP/NCAR Reanalysis from the Climate Data Assimilation System (CDAS).

Although rainfall with an incoming front July 10-11 will be important, as well as rainfall next week, this generally sets the stage for the development of heat wave conditions heading into mid-July.

A heat dome core (5940 meters), recently centered southeast of the Four Corners, will be expanding eastward across the USA next week to generate unseasonably hot, mid-summer conditions.

Feedback loops, as described above, will enhance heating over locations that maintain dry surface conditions.

Soil moisture remains above average through a deep layer, but surface soil is drying significantly due to high sun angles (strong insolation) and much below average July rainfall (in the mean, some locations have observed average to above average rainfall).

A ring-of-fire convective pattern may eventually develop, otherwise, hit-miss instability driven convection will form along the mountains.

The extent of such activity, including of course, day-time cloud formations above the mountains, will determine how high temperatures get through next week and how much amplification will occur with positive feedback loops.