With Freeze Warnings and snow flurries nearby in the GA/NC mountains tonight and lows in the 30's Upstate SC finally, might as well start the thread!
Some general area winter weather info / resource links:
(no wintry weather for us yet, but first frost likely soon)
Newcomers summary: We usually only get a couple chances of snow a year, even threat of a small amount shuts things down, snow typically melts within 1 to 3 days. Typically a mixed bag of rain, sleet, ice back and forth. i85 can sometimes be a magical dividing line. Occasionally an ice storm comes through but it's been awhile since a big one hit. There's a giant mound of salt/sand mix SCDOT has stored alongside i85 mm57 in the tall shed with no door facing i85. SCDOT also now employs a large liquid pre-treat sprayer vehicle that can coat 3 lanes of i85 at once.
Stats 1892-2019 (courtesy NWS GSP
https://www.weather.gov/media/gsp/Cl...ySNobs_htm.pdf
Notes: Totals are snow & sleet combined since we usually get a mix (ice(freezing rain) totals kept separate). Everyone see a little different. I talked to NWS GSP for where totals come from and got: Totals are from GSP airport Oct. 1962-present, prior are from GMU (Greenville Airport by downtown / 385 (GMU website says airport opened in 1928)) or are from 'observing site in Greenville before then, or Spartanburg to cover data gaps'. I also believe I've seen some older records from 1800's and early 1900's taken from various Upstate locations. On totals below I counted "Trace" amount of snow as 0.01" so totals may be slightly off from GSP, but this way I didn't end up with 0" for those times as we did get 'something'. Official data is missing for Nov-Jan 1894/95, Dec 1948, Nov 1955.
-In 127 years only 2011-2012 season was officially 0"
-Highest season total ever 21.4" 1935-1936
-Earliest snow: October of 1913 & 1926 only
-Latest snow: May 1993 only
-White Christmas: 1909, 1945, 1947, 1963, 1966, 1969, 1975, 2009, 2010
-Snowiest months since 1892 highest to lowest: Jan, Feb, Dec, Mar, Nov, Apr, Oct, May
Averages:
-Since 1892: Oct 0", Nov 0.09", Dec 0.94", Jan 1.78", Feb 1.58", Mar 0.77", Apr 0", Annual 5.13"
-Last 50 years: Oct 0", Nov 0.07", Dec 0.65", Jan 2.06", Feb 1.42", Mar 0.84", Apr 0.01", Annual 5.04"
-Last 30 years: Oct 0", Nov 0.08", Dec 0.60", Jan 1.63", Feb 1.00", Mar 0.59", Apr 0", Annual 3.90"
-Last 10 years: Oct 0", Nov 0.01", Dec 0.82", Jan 1.65", Feb 1.68", Mar 0.14", Apr 0", Annual 4.30"
Helpful links/info:
-Local NWS Snow maps: Experimental NWS maps (date last updated on bottom of image, totals valid for date(s) at image top): 3 main maps showing: expected totals, a 10% chance of happening max totals, & a 90% chance of something higher then shown low end min totals. Below that is percent chance of x" snow from 0.1" to >18" snow maps:
https://www.weather.gov/gsp/winter
-Local NWS Snow/Ice maps: Expected totals maps of both here:
https://www.weather.gov/gsp/brief_winter
-National Snow Probability (% chance) maps:
--Next 3 days (change date just above map, change snow totals on right of map):
https://origin.wpc.ncep.noaa.gov/pwp...=24&ptype=snow
--Days 4-7 (Assume for 2.5" or higher, change date just above map):
https://origin.wpc.ncep.noaa.gov/wwd...medr.php?day=4
-National Ice(Freezing rain) Probability (% chance) maps:
Next 3 days (change date just above map, change ice totals on right of map):
https://origin.wpc.ncep.noaa.gov/pwp...=24&ptype=icez
-Weather Models: Note: Models "see" different things (so when they agree we watch closely what they're saying), handle parts of storms differently, and some include mixed precipitation in their snow totals making appear higher, so best to look at many and not just the one you want to happen. Many models don't include ground warmth melting your snow totals away or back and forth mixing that erodes totals either. Many models run at 10:1 snow ratio (1" rain = 10" snow) but reality may be less or more and vary during event.
--Weather.US (change "Weather Model" (EURO(ECMWF) and GFS(Global US Standard) are main ones) & date box as desired to see precipitation type, & change "Change Parameter" from "Significant Weather" to "Snow Depth" for snow totals:
https://weather.us/model-charts/euro...t-weather.html
--TropicalTidbits:
https://tropicaltidbits.com/analysis/models/
-Many more out there, but there's 2 for the curious.
-Weather apps: Apps/sites typically use just one model run out of dozens available, only update every so often, aren't human interpreted. Useful, but have multiple sources of info to get the true picture. Large majority use GFS models since its free data from US gov (NOAA) which updates 4 times per day. Weather Channel, Intellicast and Weather Underground apps/sites are IBM now and may be using their own in-house modeling.
-Report Precipitation Type to National Weather Service / Your Neighbors:
-mPing iOs/Android app, free and ad-free! Meteorologists/NWS actually use these reports, great way to see how close actual snow falling to the ground is to you as well!
https://mping.nssl.noaa.gov/
-mPing is also integrated and usable in RadarScope radar app.
https://www.radarscope.app/
-on Twitter use "#nwsgsp" or tag @NWSGSP to report to our local NWS office (also on FaceBook).
-The NWS loves to hear your reports! Radar only tells them what's happening a few thousand feet up.
-Weather Terms:
-Snow: 32 degrees or less from cloud to near ground level for snow.
-Sleet: like tiny hail, just frozen rain drops, a problem if too many accumulate on roadway but they don't get larger like summer time hail.
-Freezing Rain (Ice) (the 'bad' ice): rain that freezes once it touches something (power line, tree, roads, etc), often fools people because "It's just raining", but that's why its called freezing 'rain'. Happens when rains at 32 degrees or less. Very dangerous. Easily can get 100's of car wrecks in our area from this.
In general:
0.01" = lite harmless glisten on trees
0.10" = bridge/overpass issues, maybe spotty road issues elsewhere.
0.25" = trees start to bend, start of tree/power issues, widespread road issues.
0.50" = scattered to widespread tree/power issues, roads icy.
-Black Ice: Thin layer of ice, road often looks just wet or damp but is actually frozen, very hard to know if frozen until it's too late. Usually occurs in freezing rain or snow melt runoff that refreezes overnight.
-CAD: Cold Air Daming, main ingredient for us to get freezing rain / ice storms, cold air is pushed down and damed in / trapped against the base of the mountains and spreads across Upstate SC region.