New Long-lead Forecasts From NOAA Include Wet Louisiana/Mid-Atlantic Projections in September. Possible TC Strikes!

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The updated NOAA/CPC long-lead climate forecast for September indicates an increased risk of above normal rain across Louisiana and the Mid-Atlantic region possibly related to tropical cyclone activity.

Highlight: NOAA/CPC updates probability climate forecasts.

Fig. 1-2: NOAA/CPC long-lead probabilistic temperature and precipitation forecast update for September 2021.

Discussion: NOAA/CPC updates their long-lead probabilistic temperature/precipitation climate outlooks. The September 2021 forecast maintains Northwest U.S. heat risk and also implies a significant land-falling tropical cyclone into the northwest Gulf of Mexico and Mid-Atlantic States (Fig. 1-2). Meteorological autumn (SEP/OCT/NOV) is projected very warm in the southwest and Northeast U.S. (Fig. 3) while dryness over the Southwest extends to the Great Plains (Fig. 4). The meteorological winter forecast is mostly unchanged and features warm/dry risk for the South and East while the Northwest is cold/wet (Fig. 5-6).

Fig. 3-4: NOAA/CPC long-lead probabilistic temperature and precipitation forecast update for September/October/November 2021.

Fig. 5-6: NOAA/CPC long-lead probabilistic temperature and precipitation forecast update for December/January/February 2021-22.

During meteorological autumn the U.S. seasonal drought outlook indicates minimal change except for drought development in western Nebraska (Fig. 7).

Fig. 7: NOAA/CPC seasonal drought outlook.