Before I share the climo graph, (as I promised to
@Ollie Williams & others) I've made a much deserved facelift the massive teleconnection spreadsheet on my website, made it a bit user friendly and added a few parameters to it, like the TNH Index I talked about yesterday as well as the RMM MJO and then made distinctions between the type of winter storm (ice or snow) and its severity.
I've taken a screen capture (shown below) from a piece of it around January 2000 to explain what each column means:
From left to right:
Column 1: Day # (Number of total Nov-Apr days since 1948 in sequential order).
Column 2: Winter Season Day # (Starting at 1 on Nov, and increasing up to 181 on April 30th, then going back to one on the next Nov 1, etc.)
Column 3: Year (In sequential order from 1948 to 2021)
Column 4: Month # (1 = January, 2 = February, 3 = March, etc.)
Column 5: Day (of month) (self explanatory).
Column 6: Daily
Arctic Oscillation (AO) Index: (1950-Present) (I normalized + detrended each month to remove long-term trends)
Column 7: Daily
North Atlantic Oscillation (NAO) Index: (1948-Present).
(I normalized + detrended each month to remove long-term trends)
Column 8: Daily
Pacific-North American Pattern (PNA) Index: (1948-Present) (I normalized + detrended each month to remove long-term trends)
Column 9: Daily
Eastern Pacific Oscillation (EPO) Index: (1948-Present) (I normalized + detrended each month to remove long-term trends)
Column 10: Daily
Western Pacific Oscillation (WPO) Index: (1948-Present) (I normalized + detrended each month to remove long-term trends)
Column 11: Daily
Tropical-Northern Hemisphere (TNH) Index: (1948-Present) Defined using the following daily-averaged NCEP-NCAR Reanalysis 500mb geopotential height grid boxes:
[[(30N-60N, 160W-120W) - 42.5N-67.5N, 105W-35W) +[(15N-32.5N, 100W-30W) - 42.5N-67.5N, 105W-35W)]/2] (I normalized + detrended each month to remove long-term trends)
Column 12: Daily
Realtime Multivariate MJO (RMM) Index: (1974-Present) Phase. Amplitude < 0.95 = "Null" phase.
Column 13: Daily
Realtime Multivariate MJO (RMM) Index: (1974-Present) Amplitude
Column 14: NC Winter Storms Categorized by severity I've chosen arbitrarily but I think the descriptions and corresponding amounts are pretty accurate:
"Minor" (Level 1) Winter Storm: At least 1" Snow/Sleet accumulation &/or at least a trace of glaze anywhere east of the mountains & far western piedmont
"Major" (Level 2) Winter Storm: More than 4" Snow/Sleet accumulation &/or at least 0.25" of glaze anywhere east of the mountains & far western piedmont
"Extreme" (Level 3) Winter Storm: More than 8" Snow/Sleet accumulation &/or at least 0.50" of glaze anywhere east of the mountains & far western piedmont
"Historic" (Level 4) Winter Storm: More than 12" Snow/Sleet accumulation &/or at least 1" of glaze anywhere east of the mountains & far western piedmont
Column 15: Hyperlinks to Winter Storm Maps associated with each storm.
(a few are missing & haven't been analyzed yet, but that'll change soon)
Column 16: Determines which precipitation type (snow or ice) has greater severity. Ice takes precedent over snow if they're both of the same category (because generally speaking, ice tends to be more destructive than snow)
Column 17: sources for maps &/or data:
Webberweather.com
NC State Climate Office Winter Storm Database
NWS RAH Past events
xmACIS2
View attachment 95999
You can also download this spreadsheet by clicking the link below:
Nov-Mar Daily Teleconnections and NC Winter Storms List (1948-2021)