Headline: Mississippi River low water level recovering. Heavy rains forecast this week Mid-south U.S. Deep layer soil moisture deficits identified in South America. Midday models are colder for Europe.
Fig. 1: ECM 10-day precipitation amount forecast indicates several to as much as 5-6 in. of rain centered on the Tennessee Valley this week.
Discussion: A frontal system with waves of low-pressure travel across the Tennessee Valley beginning tomorrow night into early Friday. The result is risk of excessive rainfall centered primarily on the Tennessee Valley. Rainfall amount of 3-6 in. is projected by the ECM (Fig. 1) and other forecast models. Thunderstorm activity is included. Most of the precipitation is rain as the forecast has featured a warmer trend. The Mississippi River low water level in the central basin will continue to improve.
Deep layer soil moisture deficits can foreshadow drought or flash drought during the summer season if a period of long duration dryness and anomalous heat settle across an area. Due to a long-term dry climate pattern, deep layer soil moisture deficit is indicated across Central/South-central Brazil to the north of Paraguay (Fig. 2). Dryness is also indicated in deep soil moisture of Northeast Argentina. At the surface, the most recent daily soil moisture anomaly analysis reveals drought across Northeast Argentina and Central/East-central Brazil (Fig. 3). The shallow and deep layer soil moisture deficit profiles identify soil moisture deficit/drought concern areas for meteorological summer.
Fig. 2-3: South America deep layer (10-200 CM) and surface level soil moisture anomalies for early December.
Fig. 4-5: Last week’s percent of normal rainfall across South America and the 15-day percent of normal rainfall forecast.
Last week, most of the dry soil moisture regions identified were drier than normal (Fig. 4). The exception was northeast coastal Argentina. Northeast Brazil maintained their wet weather pattern. The latest 15-day rainfall outlook for South America indicates the drought concern area is mostly drier than normal although some beneficial rain will occur in Central/East-central Argentina and all East Brazil (Fig. 5). The forecast trend is a little wetter in Argentina.
The GFS 15-day temperature forecast is quite cold, especially during the medium-range, across most of Europe (Fig. 6). The cold forecast is due to a sudden 24-hour much colder change (Fig. 7). The upper trough just off the West Coast of Europe budges eastward due to the established negative North Atlantic oscillation (-NAO) pattern (Fig. 8). The upper trough spawns a Spain to Black Sea region (and Southwest Russia) storm track with moderating temperatures.
Fig. 6-8: Europe 15-day temperature anomaly forecast and 24-hour trend plus the latest 15-day upper air outlook.