NOAA predictions: Grib vs. Website??
Posted: 15 Feb 2014 22:33
Delighted with the program, thank you.
Would enjoy hearing of others' experience in predicting snowfall:
Are the precipitation levels actually in centimeters per hour, not the millimeters per hour shown in the sidebar display?
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Right now zyGrib is showing between 0.7-2.5 MM/h of precipitation (presumably snow) for 41° 25' 13"N 70° 56' 20" for the next fifteen hours, based on 20140215_210922_.grb.bz2, which I assume is a NOAA-GFS product.
+ Weather map has precipitation selected
+ The "Snow Depth" box in the "Weather data" panel shows 19 CM after the storm passes at 10AM local on Sunday 2/16. This is curiously close to my calculations below in MILLIMETERS (NOT centimeters)
+ For each three hour interval of the storm I read the "Precipitation" box (MM/H) in the "Weather data" panel, multiply the average over the interval by three for the three hour time interval and add it to the previous total, then do the unit conversion. This gives a maximum accumulation of 0.97 INCHES:
Time MM/h Interval Total MM Inches
13:00 0.02
16:00 1.65 2.505 2.51 0.10
19:00 2.17 5.73 8.24 0.32
22:00 2.34 6.765 15.00 0.59
01:00 1.86 6.3 21.30 0.84
04:00 0.13 2.985 24.29 0.96
07:00 0.06 0.285 24.57 0.97
10:00 0 0.09 24.66 0.97
13:00 0 0 24.66 0.97
However, the NOAA website:
http://forecast.weather.gov/MapClick.ph ... mnyrapSeRt
says between four to eleven inches. That is at least an order of magnitude difference...
Now, if the sidebar is actually CM/H, rather than MM/H then the answer is 9.7 (not 0.97) inches, which matches the website prediction...
What am I missing?
Kind regards (stay wahm in New England), Andy
Would enjoy hearing of others' experience in predicting snowfall:
Are the precipitation levels actually in centimeters per hour, not the millimeters per hour shown in the sidebar display?
=====
Right now zyGrib is showing between 0.7-2.5 MM/h of precipitation (presumably snow) for 41° 25' 13"N 70° 56' 20" for the next fifteen hours, based on 20140215_210922_.grb.bz2, which I assume is a NOAA-GFS product.
+ Weather map has precipitation selected
+ The "Snow Depth" box in the "Weather data" panel shows 19 CM after the storm passes at 10AM local on Sunday 2/16. This is curiously close to my calculations below in MILLIMETERS (NOT centimeters)
+ For each three hour interval of the storm I read the "Precipitation" box (MM/H) in the "Weather data" panel, multiply the average over the interval by three for the three hour time interval and add it to the previous total, then do the unit conversion. This gives a maximum accumulation of 0.97 INCHES:
Time MM/h Interval Total MM Inches
13:00 0.02
16:00 1.65 2.505 2.51 0.10
19:00 2.17 5.73 8.24 0.32
22:00 2.34 6.765 15.00 0.59
01:00 1.86 6.3 21.30 0.84
04:00 0.13 2.985 24.29 0.96
07:00 0.06 0.285 24.57 0.97
10:00 0 0.09 24.66 0.97
13:00 0 0 24.66 0.97
However, the NOAA website:
http://forecast.weather.gov/MapClick.ph ... mnyrapSeRt
says between four to eleven inches. That is at least an order of magnitude difference...
Now, if the sidebar is actually CM/H, rather than MM/H then the answer is 9.7 (not 0.97) inches, which matches the website prediction...
What am I missing?
Kind regards (stay wahm in New England), Andy