Saturday provides another example of a location where uncertainty in the exact location of a frontal feature leads to big differences in temperature forecasts. The Saturday high temperature predictions for Des Moines, Iowa vary from 64 to 79 F, as a strong low pressure system passes by. Let's predict Tmax for Des Moines and see what happens.
Question: The NWS discussion mentions the possibility of a "dry slot" as an important part of the forecast. Here's a cloud cover prediction for late Saturday afternoon. So what do you think a dry slot is?
Saturday was an interesting day in Des Moines, as there was a dramatic dry slot, as you can see in this beautiful satellite image. Looking at the "Latest obs" link, at 3 pm, it was overcast with light rain and the temperature was only 57 F. Then the rain stopped and the cloud cover decreased for two hours, and the temperature increased to 68 or 69 F pretty quickly. So I assume that they were in the dry slot for a short time, but it was late in the afternoon and the temperature started decreasing again after the quick warming. If they had been in the dry slot earlier in the afternoon and if it had lasted longer, they probably would have been able to get the temperature well up into the 70's. So another tough forecast challenge.
Forecaster | Tmax, deg F (error) | Comment | Day Score |
---|---|---|---|
OBSERVED | 69 | Tmax FINAL (minor problem). | |
1. Abbygale15 | 69 (0) | 3.3 | |
1. Gus15 | 69 (0) | 3.3 | |
3. Jasper15 | 70 (1) | 3.1 | |
NAM-MOS-12-DAY01 | 70 (1) | 3.1 | |
3. Grace15 | 68 (-1) | 3.1 | |
3. ashleigh15 | 68 (-1) | 3.1 | |
6. Hannah15 | 67 (-2) | 2.9 | |
6. Dorothy15 | 71 (2) | 2.9 | |
6. Autumn15 | 67 (-2) | 2.9 | |
9. Keith15 | 72 (3) | 2.7 | |
9. Mathison15 | 66 (-3) | 2.7 | |
9. EmilyV15 | 66 (-3) | 2.7 | |
12. Sara15 | 65 (-4) | 2.5 | |
12. Josh15 | 73 (4) | I think a dry slot is when in an area where a low pressure system is coming through their is an area or little slot on the side of the system where there is no rain or clouds. | 2.5 |
12. Joscelyn15 | 65 (-4) | 2.5 | |
NAM-MOS-00-DAY01 | 65 (-4) | 2.5 | |
GFS-MOS-00-DAY00 | 74 (5) | 2.3 | |
GFS-MOS-12-DAY01 | 74 (5) | 2.3 | |
NAM-MOS-12-DAY02 | 64 (-5) | 2.3 | |
15. Shyann15 | 75 (6) | 2.1 | |
NAM-MOS-00-DAY00 | 62 (-7) | 1.9 | |
16. Anna15 | 76 (7) | 1.9 | |
GFS-MOS-06-DAY01 | 76 (7) | 1.9 | |
GFS-MOS-18-DAY01 | 77 (8) | 1.7 | |
GFS-MOS-12-DAY02 | 77 (8) | 1.7 | |
GFS-MOS-00-DAY01 | 78 (9) | 1.5 | |
17. Alex15 | 78.5 (9.5) | 1.4 | |
18. Miles15 | 59 (-10) | ~(0-o)~ | 1.3 |
GFS-MOS-18-DAY02 | 79 (10) | 1.3 | |
19. Hailey15 | 58 (-11) | 1.1 | |
19. EmilyS15 | 58 (-11) | 1.1 | |
21. Elizabeth15 | 57 (-12) | 0.9 | |
21. Lizzie15 | 81 (12) | 0.9 | |
CLIMATE | 54.7 (-14.3) | NCDC Climate Normals, 1981-2010 | 0.4 |
23. Gianni15 | 85 (16) | 0.1 | |
23. T-Dawg15 | 53 (-16) | 0.1 | |
PERSISTENCE | 49 (-20) | 0 |