Highlight: Mississippi River water level forecasts are too pessimistic! Warmer 11-15-day forecast in the East by 12Z GFS has some support.
Fig. 1-2: The two-week river level forecast for the Mississippi River at Memphis, TN and the just-received 12Z GFS 15-day precipitation amount forecast.
Discussion: The 2-week river level forecast at Memphis, TN indicates low water level descends another 5 feet (Fig. 1). However, Mid-south U.S. forecasts are trending wetter and the midday 12Z GFS is no exception offering 3-5 in. of rain in the central and southern Mississippi River Valley over the next 15 days (Fig. 2).
The 12Z GFS maintains a snowy pattern across the West U.S. and Southern Canada in the latest 15-day outlook and adds the Mid-south to Northeast U.S. early in the 11-15-day period (Fig. 3).
The 12Z GFS was somewhat warmer compared to 24 hours ago for Central Canada and the East U.S. (Fig. 4). The warmer changes are possibly linked to a cold stratosphere over North America at that time while an impressive warming stratospheric event emerges across Northeast Asia. Stratospheric warming events can cause fast-emerging arctic chill but most likely in East/Northeast Asia while eastern North America compensates with a milder look.
Fig. 3-4: The 12Z GFS 15-day snowfall forecast and 11-15-day 24-hour temperature change for North America.
|Dates||HDD Forecast||12-Hr Change||24 Hours Ago||10-Year NML||30-Year NML|
|Nov. 25-Dec. 1|
Table 1: The 12Z GFS U.S. gas population weight HDD forecast compared to 12 and 24 hours ago.