Friday, May 7, 2021

Late Spring 2021_High Knob Massif

 
6 May 2021
High Knob Massif
Looking Across High Knob Lake Basin
Early Spring Conditions (Above 3500 feet)
Wayne Browning Photograph © All Rights Reserved

The forest canopy remains wide open within cold air collecting basins (observe basin floor above) and along higher mountain ridges, with generally small, immature leaves on scattered trees down to between 3000 and 3500 feet.

At this time of year the transition to spring is always vertically wondrous, with early spring conditions above 3000 feet elevation being in dramatic contrast to late spring conditions across lower-middle elevations.

6 May 2021
High Knob Massif
Looking Down From Flag Rock RA
Late Spring Conditions (Below 3000 feet)
Wayne Browning Photograph © All Rights Reserved

Plenty of water was tumbling out of the high country on this day, with nearly as much or locally more rain during the first week of May than observed during all of April, which ended as the driest on record at Big Cherry Dam (2008 to present).

High Knob Massif
Precipitation Update

(Totals Listed By AM Measurement Format)
Monthly Total Precipitation
Big Cherry Lake Dam
(Elevation 3139 feet)

2019

January
6.14"

February
12.50"

Winter 2018-19
(1 Dec-29 Feb)
26.56"

March
5.93"

April
6.64"

May
6.75"

Spring 2019
(1 Mar-31 May)
19.32"

June
10.68"

July
10.77"

August
4.15"

Summer 2019
(1 Jun-31 Aug)
25.60"

September
0.63"

October
5.01"
( 5.89" to Midnight 31st )

November
5.20"
( 7.04" to Midnight 30th )

Autumn 2019
(1 Sep-31 Oct)
10.84"

December
8.52"

2019 Total: 82.92" (M)
 (January 1 to December 31 Period)

2020

*January
7.15"

**February
13.01"

Winter 2019-20
(1 Dec-29 Feb)
28.68"

March
9.55"
( 10.77" to Midnight 31st )

April
11.59"

May
8.73"
(6.90" on Eagle Knob of High Knob Massif)

Spring 2020
(1 Mar-31 May)
29.87"

June
7.48"

July
9.72"
(10.48" to Midnight 31st)

August
8.12"

Summer 2020
(1 Jun-31 Aug)
25.32"

September
6.21"

October 
7.06"

November 
1.96"
(Eagle Knob Snowfall: 0.5")

Autumn 2020
(1 Sep-31 Oct)
15.23"

December 
6.22"
(Eagle Knob Snowfall: 34.0")

2020 Total: 96.80" (M)
 (January 1 to December 31 Period)

2021

January
6.35"
***(Eagle Knob Snowfall: 34.0")

February
7.42"
(Eagle Knob Snowfall: 19.5")

Winter 2020-21
(1 Dec to 28 Feb)
19.99"
(21.70" on Eagle Knob)

March
10.82"
(11.14" to Midnight 31st)

April
2.53"

1-10 May
3.14"

2021 Total: 30.26"
 (January 1 to May 10 Period)

Total Past 12-Months: 85.76"

November 2019-October 2020: 102.34"

Autumn 2018 to Summer 2019: 91.21"

Autumn 2019 to Summer 2020: 94.44"

(M): Some missing moisture in undercatch and frozen precipitation, with partial corrections applied for the 24.4 meter (80 feet) tall dam structure where rain gauges are located.  Corrections are based upon 86-months of direct comparisons between NWS and IFLOWS at Big Cherry Dam (including occasional snow core-water content data).

*General 7.00" to 8.00" at upper elevations (above 3000 feet) with 5.96" at the City of Norton Water Plant (official NWS rain gauge located at approximately 2342 feet elevation).

**Third consecutive February to reach double-digit precipitation totals within upper elevations of the 
High Knob Massif.

***Not a mistake, with a second consecutive month having 34.0" of snowfall (rare to have back-to-back months with the same total).  

6 May 2021
High Knob Lake Basin
Early Spring Conditions
Wayne Browning Photograph © All Rights Reserved

Temperatures dipped to freezing and below at upper elevations in the High Knob Massif during morning hours of 6 May, as unseasonably cool air continued to grip the region.

6 May 2021
Lower-Middle Elevations
Late Spring Conditions
Wayne Browning Photograph © All Rights Reserved

Featured birds at upper elevations included an assemblage of gorgeous Rose-breasted Grosbeaks, Chestnut-sided Warblers, and Least Flycatchers.

Common Raven and Blue-headed Vireo were also observed, along with Northern Parula and the abundant Dark-eyed Junco, with many more species yet to arrive on territory at these high elevations.

6 May 2021
Water Elevation 3318 feet
Upper Norton Reservoir
Wayne Browning Photograph © All Rights Reserved

Some featured birds within cold air drainages that I observed included:
 

and below 3000 feet the elusive Swainson's Warbler.

6 May 2021
Looking Toward Powell Valley Overlook
Early Evening Light on Little Stone Gap
Wayne Browning Photograph © All Rights Reserved

Many more bird species were observed, with the 
above being mainly migrants that have recently 
returned to the mountains.

6 May 2021
Upper Norton Reservoir
Early Spring Conditions At 3318 Feet
Wayne Browning Photograph © All Rights Reserved

Climbing 2500 to 3000 vertical feet from the karst terrain of the Clinch and Powell river valleys into the High Knob Massif is analogous to traveling northward 300+ air miles (from the valleys).


This is based on Hopkins Bioclimatic Law, that states spring green-up is delayed approximately 4 days for every 400 vertical feet of elevation increase or 1 degree of latitude increase (a degree of latitude = 69 air miles).
 
The test of Hopkins Law cited at the above link, which found a shorter interval, may be explained (in part) by global warming if research in the Alps (below link) is correct. 
 

Local microclimates and current global warming complicates this basic law, and according to recent research is changing the spread between lower and upper elevations with respect to spring green-up (shortening the difference observed in the Alps). 

6 May 2021
Water Reflections on Upper Reservoir
Early Spring Conditions At 3318 Feet
Wayne Browning Photograph © All Rights Reserved

The timing of warm periods during winter and spring complicates the emergence of spring vegetation.  This also applies to orchards.

I recently wrote the following:
Orchards with apple, blueberry, peach, pear, strawberry, 
and other sensitive crops naturally go through acclaimation, dormancy, and deacclimation stages.  Following a growing season, an accumulation of cold conditions is necessary before blooming will occur again.  The length of cold time required depends upon the variety.  Accumulating enough cold is not the problem, it is premature deacclimation driven by warm periods in winter and spring that is problematic as this causes early budding and blooming.  This is one example of many consequences associated with a changing climate.   

6 May 2021
Little Stone Gap-Powell Valley Overlook
Late Spring Conditions At Mid-Elevations
Wayne Browning Photograph © All Rights Reserved

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