Sunday, January 12, 2014

Wet Winter Pattern of 2013-14

January 4, 2014
Photograph View Number 2
Upper Falls of Little Stony Creek Gorge
Majestic Beauty Of Winter In High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

The winter pattern of 2013-14 has been wet since 
a White Thanksgiving was produced by a major storm system at the end of November 2013.

City of Norton Water Plant
Days With Measurable Precipitation
Official 8" Diameter NWS Rain Gauge
Hand-Measured Daily at 9:00 AM
Elevation 2342 feet

11-26-2013  0.41"
11-27-2013  1.59"
11-28-2013  0.08"

12-06-2013  0.73"
12-07-2013  1.16"
12-08-2013  0.43"
12-09-2013  1.79"
12-10-2013  0.38"

12-15-2013  0.68"

12-18-2013  0.10"

12-22-2013  1.36"
12-23-2013  0.53"

12-25-2013  0.02"

12-29-2013  1.45"
12-30-2013  0.22"

01-02-2014  0.07"
01-03-2014  0.31"

01-06-2014  0.70"
01-07-2014  0.01"

01-10-2014  0.12"
01-11-2014  0.87"
01-12-2014  0.36"

01-14-2014  0.42"
01-15-2014  0.05"

Total: 13.84"
( November 26, 2013-January 15, 2014 )

Mean Per Week: 1.90"
( During a 7.3 Week Period )

December 2013: 8.85"

January 1-15, 2014: 2.91"

A total of 13.84" of precip have been measured in the official NWS rain gauge at the City of Norton WP since the Thanksgiving Holiday 
( 51 day period or 7.3 weeks ).

January 3, 2014
High Knob Massif
Fluffy Snow Upon Buds & Branches
Photograph by Roddy Addington - © All Rights Reserved.

A missing ingredient amid all this precipitation, even in the High Knob Massif where more than 15.00" fell since Thanksgiving, has been SNOW.

January 3, 2014
Near Sunset In High Knob Massif
Majestic Rime Coated Mountain Forest
Photograph by Roddy Addington - © All Rights Reserved.

Snowfall totals of 25-30" were observed at 
highest elevations in the High Knob Massif during 
the October 23, 2013 to January 7, 2014 period.

January 3, 2014 at 9:20 AM
High Chaparral of High Knob Massif
Time For Another Bird Feeder Fill Up
Photograph by Darlene Fields - © All Rights Reserved.

At least, given such significant precipitation amounts and intervals of intense cold the snow to rain ratio ( and I'm not talking snow density ) has been MUCH below average for this snowy massif.

For example, of the 13.84" of total precipitation measured in the City of Norton since November 26, less than 10% of it has been in the form of snow ( i.e., less than 10% of this 13.84" of water came from snow with only around 12" measured at Norton WP ).

January 3, 2014
High Knob Massif
Where's The Snow Says The Sprout
Photograph by Roddy Addington - © All Rights Reserved.

A sprout like that should be buried in snow by this time, given so much precipitation, but not during Winter 2013-14 when SW Upper Air Flow has ruled the bulk of precipitation events. 

November 26, 2013 to January 10, 2014
500 MB Vector Wind Composite Anomaly

Colder, Snowier Pattern Returns
Taking One At A Time ( January 15-25 Period )

Teleconnection Trends
Updated January 15, 2014

A significant shift from a prolonged -PNA into a potentially prolonged +PNA oscillation signals a major change from recent weeks and sets the stage for longer lasting coldness and multiple snow chances more typical of winter in the Appalachians.
( Until the February pattern can be better resolved )

Note that a -PNA has dominated the Autumn-Early Winter of 2013-14 ( analysis graph above ), with the last significant upward spike of short duration coinciding with the Thanksgiving 2013 winter storm that dropped 5-8" upon the City of Norton-High Knob Massif area.

The previous significant +PNA period, centered around October 25 in 2013, being associated with the first round of accumulating snow of this season in the 
High Knob Massif ( 1-3" snow depths ).

While model snow emphasis shifted from the January 15 system to that of January 17-18, as regards being most significant, snow showers and locally intense, hit-miss squalls remain likely across the mountains during January 15. 

Case in point, The Little Snowman of High Chaparral.

( 1.0" of depth at 3300 feet )
January 15, 2014 at 10:53 AM
High Chaparral Community of High Knob Massif
The Little Snowman Of The High Chaparral
Photograph by Darlene Fields - © All Rights Reserved.

A general 0.5" to 1.0" of snow accumulated
across the area during the AM of January 15.

New Trends Toward Possible Major to Moderate
Stratospheric Warming Event
Of The Displacement Vortex Type
  ( Current Timing - Late January or Early February )

Up to now a 2 wave attack has been the dominant one upon the Polar Vortex ( Wave 2 it is called ) which initially worked to trigger the first two arctic blasts of early January 2014 ( the second one, of course, being the barbaric blast ) by squeezing, or compressing, the vortex such that blobs of bitter air were pushed southward into the USA against an otherwise unfavorable pattern for severe cold ( the blasts were progressive & relatively short-lived ). 

This continued Wave 2 action has now split the vortex 
( partially split ) into two pieces through the depth of the stratosphere between 100 MB & 1 MB, but without having a major disruption to its core ( no major stratospheric warming event or wind reversal has even come close to occurring amid the 60 degrees North and 10 MB sector, but the vortex has been weakening as illustrated by temp rises observed above the North Pole at 30 MB ).

12z January 11, 2014
Polar Vortex Near Bottom of Stratosphere

12z January 11, 2014
Polar Vortex Near Top of Stratosphere

Although temperatures have warmed dramatically at the top of the stratosphere, with a positive temp gradient recently observed between 60 degrees and 90 degrees North latitude, another downward trend in the Mean Temperature above the North Pole at 30 MB reflects the potent strength of this Vortex.

A decrease in zonal mean zonal wind speed also indicates vortex weakening; however, in both cases of core temperature & current westerly wind speed this Polar Vortex remains stronger than climatology despite Wave 2 action beating on it like a drum!

This is where a forecast Wave 1 ramp up during the next 5-10+ days enters the picture via what appears to be a tropospheric coupling between Aleutian Low pressure and Siberian High pressure.

Wave 1 At 12z January 19, 2014
European Model Wave 1 Forecast Day 7

If this occurs as currently forecast it will represent a major hemispheric change from mean conditions observed during Autumn 2013-early Winter 2014.

Note that the Autumn of 2013, from September-October through November, was dominated by a weaker than average Siberian High ( more blue color, or low pressure, where red color or high pressure should have been ) and a weaker than average Aleutian Low ( the Aleutian Low being essentially non-existent in the anomaly mean from late October through much of December ).

Northern Hemisphere
October 25 to December 25, 2013
500 MB Geopotential Height Composite Anomalies

Strong positive height anomalies dominated the Northern Pacific, in place of an Aleutian Low, during the October 25-December 25 period 
( generating Wave 2 forcing but little Wave 1 ).

While there are wave and ozone induced warming events amid the stratosphere at various times during any given winter season, here the focus is upon the type of high amplitude wave induced warming that can breach the surf zone of the Polar Vortex and do major structural damage to its core via changes in both internal temp and vector winds ( changes in speed + direction ).

This section is under construction.  Check back for updates.