Heavy Snows, Severe Weather and Cold Bursts Start The Week

La Nina Intensity Is Choppy And Weaker
03/08/2021, 1:26 pm EST
Stratospheric Warming on The East Coast in Late March
03/16/2021, 11:21 am EDT
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Fig. 1: NOAA/NWS weather watch, warning and advisory areas.

Short-term high impact events: A busy Sunday across the U.S. featuring adverse last-gasp winter weather events (Fig. 1). A major Central U.S. storm continues…heavy snows across the central Rocky Mountains including blizzard conditions in Wyoming to western Nebraska while flooding from weekend rains continues across Kansas and Missouri. Yesterday’s northwest/west Texas severe weather which included tornadoes shifts to the Mid-South States today although not as intense. Another 1-3 feet of snow is likely in the Central Rockies with chance of >1 foot of snow across Nebraska (Fig. 2). Damaging high wind plagues the Southwest U.S. to western Texas. A Red Flag Warning remains in-place in western Texas. A polar high-pressure center north of the Great Lakes provides the necessary cold air to cause the Central U.S. heavy snow. This air mass gains arctic characteristics today due to cross-polar flow from northern Russia. The arctic air mass gusts its way into the Northeast U.S. tonight/Monday bringing possible record cold (Fig. 3).

Fig. 2-3: ECMWF 48-hour snowfall forecast for the West-central U.S. and Monday afternoon maximum temperatures for the Northeast.

Storm focus shifts to California tomorrow where bursts of late winter weather continue. A (very) cold upper trough moves across central California Monday afternoon. Widespread snows are the result spreading from northern California tonight to the Sierra Nevada and southern California Mountains to start the week. Afternoon temperatures are 8-22F below normal Monday afternoon across California, coldest the southern half of the state. The California storm shifts (quickly) to the Great Plains TUE/Mid-South WED when major severe weather events are likely (Fig. 4-5). Major tornado outbreak(s) should be expected.

Fig. 4-5: NOAA/SPC severe weather outbreak forecasts for Tuesday and Wednesday.

The U.S. medium-range: In the 6-10 day period, another upper trough positions across The West maintain a chilly climate while an amplified high-pressure ridge warms the central continent into the Northeast States. A “sneaky cool” Mid-Atlantic coastal storm could push a cooler than indicated Northeast Corridor warm regime in the 6-10 day period (Fig. 6). In the 11-15 day forecast maintains an active upper trough pattern across the southern states while cresting high-pressure warms the northern areas (Fig. 7). We could see a significant rainfall/severe weather event days 11-15 in Texas/Mid-south States. Despite the storminess the next 1-2 weeks, analogs and probability forecasts want to warm and dry-out the U.S. pattern as demonstrated by NOAA/CPC (Fig. 8-9).

Fig. 6-7: The Climate Impact Co. medium-range temperature anomaly forecasts.

Fig. 8-9: NOAA/CPC issued a nationally warm and dry 16-30 day outlook on Friday.