Temperature

BCRMSE

    • In general, there is an increase in BCRMSE with forecast lead time. For both the 00 and 12 UTC initializations, a diurnal trend is displayed in the distribution of BCRMSE values, which generally range between 2.2 - 3.4 °C, depending on the temporal aggregation.
    • For most temporal aggregations, there is a maximum in forecast error magnitude near 15 UTC and again around 00 UTC. An exception is spring, where the errors tend to remain high throughout the daytime hours. The smallest forecast errors are generally seen for forecasts valid at 06 and 09 UTC and closer to 03 UTC during the fall aggreagtion.

Bias

    • A strong diurnal signal is seen regardless of initialization or temporal aggregation. There is generally a SS warm bias during the overnight hours (mainly between 06-12 UTC) and a SS cold bias is noted during the daytime hours of 15 - 00 UTC.

Dew Point Temperature

BCRMSE

    • All temporal aggregations reveal an increase in BCRMSE values with lead time. A strong diurnal trend is noted in all temporal aggregations except fall and winter, where the signal is weak.
    • For both the 00 and 12 UTC initializations, BCRMSE values generally range from 2.2 - 3.6 °C. The largest errors are generally seen around 21 - 00 UTC for all temporal aggregations. The smallest errors vary in exact time for each season, but generally occur during the overnight hours between 03 and 12 UTC.

Bias

    • A large number of CIs encompass zero for the fall and winter temporal aggregations and, thus, are not significantly different from an unbiased forecast.
    • Generally, there is a SS wet bias for forecasts valid between 18 and 00 UTC and a SS dry bias is noted for forecasts valid between 06 and 12 UTC for the spring, summer and annual temporal aggregations.

Wind

BCRMSE

    • For both initializations, the BCRMSE values range from approximately 1.5 - 2.6 m s^-1, with a diurnal trend noted for all temporal aggregations except fall and winter. Increasing error with lead time is also noted.
    • For the annual, summer and spring aggregations, the largest BCRMSE values are seen at forecast lead times valid at 00 UTC, while the smallest errors are around the 12 UTC valid time, regardless of initialization time.
    • Due to the weak diurnal signal seen for the fall and winter aggregations, the error is fairly consistent across valid times, especially when CIs are considered.

Bias

    • A SS high wind speed bias is noted for all forecast lead times, regardless of initialization hour or temporal aggregation.
    • For both the 00 and 12 UTC initializations, a very large diurnal cycle is noted with SS larger high bias during the overnight hours (03 - 12 UTC) compared to the daytime hours (15 - 21 UTC).

3-hour Precipitation Accumulation

GSS

    • Regardless of initialization time or forecast lead time examined, the highest GSS values are seen at the lowest precipitation threshold and steadily decrease to near-zero for higher thresholds. The number of observed events (base rate) by threshold has a similar trend. The largest CIs are typically noted for the winter aggregation, which also has the lowest base rate.

Frequency Bias

    • For the annual, fall and winter aggregations, a general high bias is seen for all but the highest thresholds, regardless of forecast lead time or initialization hour. This basic trend holds for spring and summer lead times valid at 00 UTC; however, for 12 UTC valid times, most results are not significantly different from an unbiased forecast.

24-hour Precipitation Accumulation

GSS

    • A general decrease in GSS with increasing threshold and lead time, similar to that seen for 3-hour precipitation accumulations, is noted for all temporal aggregations except winter. Again, a similar trend is noted in the base rate, with very few observed events of 3" accumulations in 24 hours.

Frequency Bias

    • Most temporal aggregations exhibit a fairly consistent high bias for all but the highest thresholds, which have CIs that encompass one.
    • In general, as the threshold increases, the width of the CIs increase, indicating more spread and less confidence in the median bias value, likely related to the decreasing base rate.

Temperature

BCRMSE

    • Regardless of forecast lead time or temporal aggregation, a minimum in the BCRMSE values occurs between 500 and 300 hPa and increases to a maximum at both the near-surface and upper levels.
    • A SS increase in BCRMSE values between the 12-hour and 48-hour forecast lead times is noted. Errors are less than 2.2 °C for all lead times.

Bias

    • For all temporal aggregations, a SS cold bias is seen for all lead times at the 850 hPa level transitioning to a SS warm bias with height. The level of transition occurs near 700 to 500 hPa, but is dependent on temporal aggreagtion and lead time. One exception is often noted at 150 hPa where there is large variability in the bias. A vertical local minimum is noted which translates into a larger cold bias or a smaller warm bias at that level.

Dew Point Temperature

BCRMSE

    • As the pressure level decreases from 850 to 500 hPa and the forecast lead time increases from 12 hours to 48 hours, the BCRMSE values generally increase for all temporal aggregations.

Bias

    • A SS high bias is noted for most forecast levels and lead times for each temporal aggregations except summer, which encompasses zero for all lead times at 850 hPa and has a SS low bias at 700 hPa for the 36- and 48-hour lead times.
    • Similar to the results for BCRMSE with pressure level, the highest bias is seen at the 500 hPa level.

Wind

BCRMSE

    • A general increase from the minimum BCRMSE values at the lowest levels (typically at the 850 or 700 hPa level) to a maximum at the generally found at 300 to 150 hPa level for all forecast lead times and temporal aggregations, is noted.
    • Overall, the errors generally range from 3.5 - 6.5 m s^-1 depending on lead time and temporal aggregation, with a SS increase in BCRMSE values between the 12- and 48-hour lead times seen for several levels.

Bias

    • In general, there is a SS low wind speed bias for the 12-hour lead time at all levels below 150 hPa, regardless of the temporal aggregation. As the lead time increases, the forecast bias values become smaller and encompass zero most frequently at the lowest and upper-most levels.
    • The largest (low wind speed) bias is observed at 200 hPa for all temporal aggregations.