forecasting tricks for irwin (february 28, 2014)
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Forecasting tricks for Irwin
Photo: Connor Walberg ActionPhotoSchool.com
Meteorologist Joel Gratz
1960
2005
I want to remove the mystery of Colorado weather.
Hi, I’m Joel Gratz.I grew up in Pennsylvania, ski raced and instructed, then moved to Colorado after college.
And I started to miss powder days due to inaccurate forecasts.
Dec 2007 28 people email list
2008-2009 500 people email list
2009-2010 245,000 pageviews
2010-2011 1,315,000 pageviews
2011-2012 3,330,000 pageviews
2012-2013 12,000,000 pageviews
2013-2014 ~18,000,000 pageviews
So I learned how to forecast in Colorado, and started to share.
This is where we look for El Nino or La Nina.
Courtesy: Mike Baker, NWS Boulder
Storm tracks for La Nina.
Courtesy: Mike Baker, NWS Boulder
Storm tracks for El Nino.
This year is a La Nada.
Courtesy: Mike Baker, NWS Boulder
Storm tracks for La Nada.
It snowed in Aspen during September.
Of the past 22 Septembers with snow, 19 of the
ensuing winters have been average or above.
- Cory Gates, AspenWeather.net
Perhaps there’s another clue. !
We set a snowfall record in April and a rainfall record in September for Boulder. Does this tell us anything about winter snow in the mountains?
Each line shows amount of snow on the ground for various weather stations, during winters after heavy precipitation in Boulder.
100%
110%
120%
130%
140%
150%
160%
Dec 1 Jan 1 Feb 1 Mar 1 April 1
Pueblo
Durango
Alamosa
Gunnison
Leadville
Fort Collins
Grand Junction
Colorado Springs
Steamboat Springs
UPPER ARKANSAS
SOUTH PLATTE
GUNNISON
WHITE-YAMPA
REPUBLICAN
COLORADO HEADWATERS
RIO GRANDE HEADWATERS
UPPER SAN JUAN UPPER CIMARRON
UPPER COLORADO-DOLORES
NORTH PLATTE
SMOKY HILL
LOWER SAN JUAN
UPPER GREEN
Denver
47
79
72
68
94
70
88
89
95
67
82
99
9895
95
87
72
98
58
76
39
98
97
47
67
73
69
86
81
76
85
70
90
87
10
148
136
117
141
126
138
117
118
152
114
121 148
129
126
131
137
136
126
123
109
164
119
122
122
106
117
149
111
130
128
110
101
130
162
124
145
144
141
119
150
147
132
112
110
111
159
144
158
191
147
140
116
188
152
153
105 123
123
182133
76
25
ColoradoSNOTEL Snow Water Equivalent (SWE)
% of Normal
70
0 20 40 60 80 10010Miles
Prepared by theUSDA/NRCS National Water and Climate CenterPortland, Oregonhttp://www.wcc.nrcs.usda.gov/gis/
Provisional Data Subject to Revision
Current SWE % of 1981-2010Median
> 160%
140-160%
120-139%
100-119%
80-99%
60-79%
40-59%
1-39%
0%
Unavailable*
Feb 27, 2014
* Data unavailable at time of posting or unavailable long-term normal.
This year
Average
2010-2011
Average
Schofield Pass
2010 - 2011 Season:
2 of 60 storms created
25% of the total season snow
2010-2011
2013-2014
Schofield Pass
Crested Butte
2.5x
Long range forecasts stink! !
We cannot reliably predict snow accumulations beyond about two weeks. Seasonal outlooks are even worse.
Actual Storm Track
16 Day Forecast
15 Day Forecast
14 Day Forecast
13 Day Forecast
12 Day Forecast
11 Day Forecast
10 Day Forecast
9 Day Forecast
8 Day Forecast
7 Day Forecast
6 Day Forecast
5 Day Forecast
4 Day Forecast
3 Day Forecast
2 Day Forecast
1 Day Forecast
Actual Storm Track
Weather happens when moist air
gets high
1 2 3
Where’s the moisture?
Lots of moisture(ocean source)
Less moisture (land source)
OK moisture (ocean + plants)
C onvection L ow Pressure O rographics U ndercut D ynamics
How to get air high?
WEATHER 101: Five ways to get high
C is for convection.
warm air
cold air
WEATHER 101: Five ways to get high
L is for low pressure.
Low Pressure
Orographics!
O is for orographic.
WEATHER 101: Five ways to get high
U is for undercut.
http://www.clker.com/cliparts/e/4/9/a/12401693261710228990Kliponius_Mountain_in_a_Cartoon_Style.svg.med.png
Cold Air Warm Air
Cold front moving left-to-right
WEATHER 101: Five ways to get high
D is for dynamic.
http://www.clker.com/cliparts/e/4/9/a/12401693261710228990Kliponius_Mountain_in_a_Cartoon_Style.svg.med.png
This is complicated - it’s all physics.
30,000ft300mb
Jet Stream(river of fast air)
Induces upward motion by “pulling” surface air upward into the void left by the fast-moving air above. Similar to opening a car window while moving and having a piece of paper “sucked” out.
WEATHER 101: Five ways to get high
D is for dynamic.
http://www.clker.com/cliparts/e/4/9/a/12401693261710228990Kliponius_Mountain_in_a_Cartoon_Style.svg.med.png
This is complicated - it’s all physics.
Vorticity counter-clockwise
spin
As vorticity centers (“vort max”) move, they induce upward motion in front and downward motion behind.
18,000ft500mb
SNOW in CO: What winds to watch?
5,000ft850mb
10,000ft700mb
18,000ft500mb
30,000ft300mb
As a standard, winds are forecast (and measured) at 850mb, 700mb, 500mb, 300mb, and 250mb.
JET STREAM
VORTICITY
OROGRAPHIC
Orographics get air high
Mountains = Precipitation
Indian Peaks / RMNP
Sangre deChristo
Park Range
Flattops
Grand Mesa
Elk Mtns
East San Juans
N&S San Juans
Sawatch
Gore
Ten Mile & Mosquito
Favorable wind directions
Wolf Creek
Silverton
Telluride
Powderhorn Crested Butte
AspenVail
Summit Co.
SteamboatRMNP
Crested Butte: West-southwest
Irwin Crested Butte
Irwin: Almost any wind direction?
Crested Butte
Vail: Northwest winds
BeaverCreek
Vail
Gore Range
VailPass
Beaver Creek: West winds
Vail
Gore Range
VailPass
BeaverCreek
Telluride: West & WNW winds
http://www.its.caltech.edu/~atomic/snowcrystals/primer/primer.htm
Moi
stur
e in
the
air
Temperature >> colder
10F 0F
The best snow requires... • Lots of moisture
• Temperatures between about 0-10F where the lift is taking place (usually mountain top, but sometimes higher)
• Best wind for Crested Butte = West-southwest Irwin = SW through NW
Wind directions? Complicated. What about radar? !
Nope. There’s a problem...
Radar
Jamming the Radar
Overshooting the Snow
0.5 deg
http://www.ncdc.noaa.gov/nexradinv/
Denver Airport
PuebloGrand Mesa
http://www.ncdc.noaa.gov/nexradinv/
RMNP
Steamboat
Telluride
Wolf Creek
Aspen
BC / Vail
Summit Co.
Crested Butte
http://www.ncdc.noaa.gov/nexradinv/
4.8 mile resolution
2.4 mile resolution
4.8 mile resolution
2.4 mile resolution
4.8 mile resolution
2.4 mile resolution
Model Accuracy at 6-day forecast
European = British = Canadian = American =
0.845 0.825 0.820 0.807
1 = a perfect score
How to plan
7-10 days 4-5 days 2-3 days
What’s the forecast?
To the internet!
Forecast process!Forecast sites!Model biases!Downslope wind (Foehn)