Cool Northeast Pacific/Warm Gulf of Mexico SSTA = Powerful Severe Weather Events

Blizzards, Tornadoes, and High Wind Central Into East States
03/31/2023, 8:38 am EDT
Tornado Risk East-central U.S. Today to Ohio Valley Tomorrow
04/04/2023, 10:14 am EDT
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Headline: Growing season issues in the Great Plains…late season snow cover, wet soils from recent heavy rains, and drought.

Fig. 1: Current U.S. soil moisture anomalies.

Discussion: The U.S. soil moisture anomalies identify many regimes. For instance, parts of the West remain in drought despite heavy precipitation during Q1/2023. Examples are northern California and Utah. The Kansas drought is impressive…both short-term and long-term precipitation deficits producing D4 intensity. D4 drought is also located in south-central Texas and northeast Nebraska. Almost the entire Great Plains is in a drought. Drought persists in Florida and is strengthening in the coastal Mid-Atlantic region. Due to a wet/snowy Q1/2023, much of the West has very moist to extremely moist soil moisture. Other locations with +4.0 Palmer Drought Severity Index (PDSI) include south-central Wisconsin and western New York. Right now, marginally wet soils are dominant in the Central U.S. corn belt and moderately wet in southern soybean crop areas. The spring wheat areas are covered with snow. Wheat-growing areas in the west/southwest Great Plains and into Texas are in fierce drought. Regarding the snow cover across the North-central U.S., concern is increasing given a recent snowstorm, continued widespread (deep) snow cover and another snowstorm this week (Fig. 2). The snow cover biases the climate pattern colder which in-turn maintains snow cover and prevents planting. The snow cover precedent in May since 2000 is roughly 10-20% risk but current snow cover with more snow on the way is historic for early April in the North-central/Upper Midwest States. Finally, a wet weather pattern is forecast to emerge in the northwest Gulf States over the next 2 weeks. Extreme rain is forecast for eastern Texas through northern Louisiana to central Mississippi (Fig. 3).

Fig. 2-3: The GFS 48-hour snowfall forecast for TUE/WED in the North-central U.S. and 15-day rainfall forecast for Texas using the latest GFS forecast.

The FRI/SAT severe weather event across the Midwest U.S. and into the East States produced historic number of severe weather reports including 881 on Friday (Fig. 4) and 1,264 reports for the 2-day event (Fig. 5). On Friday, 96 tornado damage reports were issued. The entire central and eastern U.S. Corn Belt was hard-hit by the outbreak on Friday followed by high wind on Saturday.

The SSTA pattern in the Northeast Pacific and Gulf of Mexico identifies in-part why the weekend severe weather outbreak was so intense. The West U.S. trough well-correlated to persistent cool SSTA off the U.S. West Coast (Fig. 6) entrained more abundant moisture than normal from the much warmer than usual Gulf of Mexico (Fig. 7).

Fig. 4-5: The severe storm reports for the Mar. 31-Apr. 1, 2023 outbreak.

Fig. 6-7: Influencing a climate pattern favorable for intense severe weather is the cool SSTA off the U.S. West Coast and much warmer than normal SSTA in the Gulf of Mexico.

In Europe, soil moisture is increasing. Soil conditions across West to West-central Russia are soaking wet (Fig. 8) while Central Europe soil moisture is increasing. Dryness in France is easing while soil moisture anomalies are turning drier rapidly in Spain. Last week, much of Europe was much wetter than normal including Western Russia to the Black Sea region (Fig. 9). The 10-day percent of normal precipitation forecast indicates Central and East Europe turn dry while Southeast Europe and the Black Sea region trend somewhat wetter (Fig. 10).

Fig. 8-9: Daily soil moisture analysis across Europe and the 7-day percent of normal precipitation observations.

Fig. 10: Europe 10-day percent of normal precipitation forecast across Europe and Western Russia.