Grade Summary
This storm was well forecasted on an overall basis, however local conditions and perceptions may vary from the objective grade calculated below. Step through the other tabs to see a breakdown of the scoring.
| 95% | Graded Element | Possible Points | Actual Points |
| 6 inch contour error | 8 | 8 | |
| Magnitude of snow error | 8 | 8 | |
| Onset timing error | 4 | 4 | |
| Peak wind gust error | 4 | 3 | |
| Probability of Detection/False Alarm Ratio | 8 | 7 | |
| Warning lead time | 8 | 8 | |
| Impact messaging | 4 | 4 | |
| Total | 44 | 42 | |
| Grade | 95% |
6 inch contour error
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.PNG) |
| Official snowfall forecast at warning issuance | Observed Snowfall | Overlap of predicted and observed 6 inch snowfall areas |
| Error | Points |
| <=15 miles | 8 |
| 16-20 miles | 7 |
| 21-25 miles | 6 |
| 26-30 miles | 5 |
| 31-35 miles | 4 |
| 36-40 miles | 3 |
| 41-45 miles | 2 |
| 46-50 miles | 1 |
| 51+ miles | 0 |
| Actual: 14 miles | 8 |
Magnitude of snow error
The highest amount of snow forecast was around 12 inches. The actual highest total was 12.2 inches 6 miles NW of Swanville, MN.
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| 10th percentile snow at warning issuance (90% chance for more snow than this) | Official snowfall forecast at warning issuance | 90th percentile snow at warning issuance (10% chance for more snow than this) |
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| List of Snowfall Totals |
| Error | Points |
| <=2" | 8 |
| 2.1-3.5" | 6 |
| 3.6-5.0" | 4 |
| 5.1-6.5" | 2 |
| 6.6+" | 0 |
| Actual: 0" | 8 |
Onset timing error
The time visibility falls to less than 3 miles due to falling snow is noted for each warned weather station at an airport. This is considered the time accumulating snow begins. It is checked against the "When" bullet in the Winter Storm or Blizzard Warning and the difference is calculated. The expected time range will never be greater than 3 hours. The existence of the range is often determined by the number of counties included in each warning grouping. The more counties included, the larger the differences in timing.
| Warned Airport Weather Station | Expected Time ("When" bullet in warning) | Actual time visibility fell to less than 3 miles due to snow | Error (hh:mm) |
| Alexandria (AXN) | 3-6 am | 5:29 am | 0:00 |
| Appleton (AQP) | 3-6 am | 2:54 am | 0:06 |
| Benson (BBB) | 3-6 am | 3:14 am | 0:00 |
| Canby (CNB) | 3-6 am | 4:14 am | 0:00 |
| Glenwood (GHW) | 3-6 am | 6:14 am | 0:14 |
| Granite Falls (GDB) | 3-6 am | 7:12 am | 1:12 |
| Litchfield (LJF) | 6 am | 9:52 am | 3:52 |
| Little Falls (LXL) | 6 am | 3:52 am | 2:08 |
| Long Prairie (Y14) | 6 am | 6:53 am | 0:53 |
| Madison (DXX) | 3-6 am | 4:53 am | 0:00 |
| Montevideo (MVE) | 3-6 am | 6:11 am | 0:11 |
| Mora (JMR) | 7-10 am | 10:59 am | 0:59 |
| Morris (MOX) | 3-6 am | 3:53 am | 0:00 |
| Olivia (OVL) | 6-9 am | 7:33 am | 0:00 |
| Paynesville (PEX) | 6 am | 8:59 am | 2:59 |
| Princeton (PNM) | 7-10 am | 10:34 am | 0:34 |
| Redwood Falls (RWF) | 6-9 am | 5:25 am | 0:35 |
| Sauk Centre (D39) | 6 am | 7:52 am | 1:52 |
| St. Cloud (STC) | 6 am | 9:27 am | 3:27 |
| Willmar (BDH) | 6-9 am | 6:15 am | 0:00 |
| Average: 0:57 |
| Error | Points |
| <1 hr | 4 |
| 1-2 hr | 3 |
| 2-3 hr | 2 |
| 3-4 hr | 1 |
| 4+ hr | 0 |
| Actual: 00:57 | 4 |
Peak wind gust error
| Warned Airport Weather Station |
Expected wind gusts from warning (mph) |
Actual wind gust (mph) |
Error (mph) |
| Alexandria (AXN) | 55 | 53 | 2 |
| Appleton (AQP) | 55 | 52 | 3 |
| Benson (BBB) | 55 | 39 | 16 |
| Canby (CNB) | 55 | 40 | 15 |
| Glenwood (GHW) | 55 | 46 | 9 |
| Granite Falls (GDB) | 55 | 40 | 15 |
| Litchfield (LJF) | 40-45 | 39 | 1 |
| Little Falls (LXL) | 40-45 | 32 | 8 |
| Long Prairie (Y14) | 40-45 | 41 | 0 |
| Madison (DXX) | 55 | 52 | 3 |
| Montevideo (MVE) | 55 | 52 | 3 |
| Mora (JMR) | 40 | 43 | 3 |
| Morris (MOX) | 55 | 47 | 8 |
| Olivia (OVL) | 55 | 39 | 16 |
| Paynesville (PEX) | 40-45 | 36 | 4 |
| Princeton (PNM) | 40 | 38 | 2 |
| Redwood Falls (RWF) | 55 | 51 | 4 |
| Sauk Centre (D39) | 40-45 | 44 | 0 |
| St. Cloud (STC) | 40-45 | 45 | 0 |
| Willmar (BDH) | 40-45 | 43 | 12 |
| Average: 6 mph |
| Error | Points |
| <5 mph | 4 |
| 5-8 mph | 3 |
| 9-12 mph | 2 |
| 13-16 mph | 1 |
| 17+ mph | 0 |
| Actual: 6 mph | 3 |
Probability of Detection (POD)/False Alarm Ratio (FAR)
Probability of Detection (POD) is event-based, meaning that each confirmed event is checked to see if a warning was issued and in effect at the time of the event. The national goal for winter storms is 0.90 or greater (90%).
False Alarm Rates (FAR) are computed based on warnings. For each warning issued, did an event meeting warning criteria take place? There is not a set national goal for FAR.
| POD | Points | FAR | Points | |
| 0.90+ | 4 | <0.11 | 4 | |
| 0.80-0.89 | 3 | 0.11-0.20 | 3 | |
| 0.70-0.79 | 2 | 0.21-0.30 | 2 | |
| 0.60-0.69 | 1 | 0.31-0.40 | 1 | |
| <0.60 | 0 | 0.40+ | 0 | |
| Actual: 1.000 | 4 | Actual: 0.15 | 3 |
Warning lead time
Lead time is considered the amount of time between the warning issuance and when criteria is met (typically when 6 inches of snow was measured). This category is the average lead time of all the verified counties.
| Lead Time | Points |
| 20+ hours | 8 |
| 15-19 hours | 6 |
| 10-14 hours | 4 |
| 5-9 hours | 2 |
| <5 hours | 0 |
| Actual: 32 hours | 8 |
Impact messaging
This is the only subjective category since it is very difficult to set hard criteria for impacts. Snow falling at night on a weekend will have minimal impact compared to rush hour during the week, even if the amount was the same. Were the impacts experienced conveyed properly in the warning and social media postings?
| Impact messaging | Up to 4 points |
| 4 |
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