Surprisingly, GFS ENS Matches/Exceeds ECM ENS Skill in Medium-range Past 30 Days

Texas and Mid-Atlantic Coast Tropical Threats Emerging
09/11/2021, 10:16 am EDT
Meridional Wind Anomaly Forecast For Q4/2021 Identifies Extreme Storm Risk
09/16/2021, 6:30 am EDT
Show all

In a surprise, the GFS Ensemble has equaled or exceeded ECM Ensemble in medium-range skill scores (of 2-meter temperature forecasts) during the past 30 days. Regions of the high demand energy East U.S. produced better GFS 9than ECM) ENS skill scores - a rare event!

Natural Gas Prices Are Up…Model Skill Score Importance Increases. Surprisingly, GFS ENS edges ECM ENS as most skillful medium-range model.

Discussion: Due to Ida impacts, natural gas prices have rallied to the $5 range (highest since February 2021 and February 2014 prior to this year) raising the importance of any additional adverse weather impacts on the U.S. (and global) market. Temperature forecasts have increased their relevance when any extreme emerges that increases (or decreases) natural gas demand. Late calendar summertime forecasts have been very warm-to-hot across high-energy demand regions keeping pressure on supply. This sort of pressure is projected to continue and be attributed to potential cold scenarios for upcoming winter beginning with any cold November risk (similar to November 2018).  

A quick review of 2-meter temperature forecast skill for North America and the high energy demand Midwest, Northeast and Mid-Atlantic regions is provided. The models considered are the primary operational tools: GFS, GFS Ensemble, ECM and ECM Ensemble. Skill scores are from the pat 30 days and calculated by Storm Vista WX Models.

The North America skill is typically very similar for days 1-5 for the past 30 days (Fig. 1). However, medium-range skill scores show separation. In the 6-10-day period the GFS and ECM Ensembles show good and similar skill. The GFS model is least skillful. For North America, the 11-15-day forecast skill scores are still reasonable (for this long-lead time) by both the GFS and ECM Ensemble. Typically, the ECM Ensemble dominates best skill at this timeframe. The GFS typically ranks last which is the case for the past 30 days for North America.

In the Midwest U.S., the GFS ENS (surprisingly) has the best skill while the GFS ranks last (Fig. 2). Similarly, the GFS ENS edges the ECM ENS in the medium-range for both the Northeast and Mid-Atlantic region (Fig. 3-4). GFS ENS edging ECM ENS in the medium-range is rare!

Fig. 1: North America skill scores for 2-meter temperature forecasts the past 30 days. The ECM and GFS Ensembles are very close as lead model(s).

Fig. 2: Midwest U.S. skill scores for 2-meter temperature forecasts the past 30 days. The GFS ENS edges the ECM ENS in the medium-range (which is very unusual).

Fig. 3: Northeast U.S. skill scores for 2-meter temperature forecasts the past 30 days. The GFS ENS edges the ECM ENS in the medium-range (which is very unusual).

Fig. 4: Mid-Atlantic U.S. skill scores for 2-meter temperature forecasts the past 30 days. The GFS ENS is (by far) most skillful in the medium-range.