Extreme Weather Leads To A Mix Of Drought Development & Relief
Extreme weather events across the U.S. painted a starkly contrasting picture of drought development and relief last week.
High pressure over the western half of the U.S. brought record-breaking heat to the West and Plains. This intense heat, combined with high winds and pre-existing dryness threatened to rapidly deplete topsoil moisture and fueled explosive wildfires, most notably the historic Morrill Fire in Nebraska that consumed over 800,000 acres.
At the same time, other regions of the nation experienced abrupt and volatile moisture influxes that mitigated dry conditions but also introduced localized to severe flooding. In the Pacific Northwest, an atmospheric river stalled over Washington, bringing heavy rain and significant snowmelt. Further east, a powerful winter storm delivered a massive precipitation boost in the form of a late-season blizzard, dropping over 50 inches of snow across parts of the Upper Midwest and Michigan's Upper Peninsula.
Northeast
A parade of storm systems moved across the Northeast last week, bringing daily or almost daily chances of precipitation. Interior portions of the Northeast were cold enough for precipitation to remain in the form of snow. Some sleet, freezing rain and rain occasionally mixed in with the snow. Rain was the predominant precipitation type across southern portions of the Northeast and much of the Mid-Atlantic.
While there were daily or almost daily chances of precipitation, precipitation was highly variable throughout the region. Liquid precipitation amounts ranged from 0.25 to 3 inches. Beneficial rain helped alleviate ongoing dry conditions across New York, New England and parts of the Mid-Atlantic.
Most notably, this beneficial moisture allowed for the reduction of severe drought (D2) in northern New Jersey and along the Pennsylvania-Maryland border. Moderate drought (D1) was trimmed across parts of Pennsylvania, New Jersey, Maryland and Massachusetts. Abnormal dryness (D0) improved across New York, Connecticut, Pennsylvania, Maryland and Delaware.
There were no spots that saw drought or abnormally dry conditions expand this week.
Southeast
Much of the Southeast experienced unseasonably warm and largely dry weather throughout last week. The exception was Florida and parts of Georgia, which remained cooler than normal. Precipitation was scarce, with most of the region reporting little to no rainfall. Month-to-date precipitation totals from central North Carolina down to northern Florida currently sit at 25% of normal. The combination of dry weather and warm temperatures exacerbated short-term precipitation deficits, streamflows and soil moisture deficits.
Consequently, exceptional drought (D4) expanded from southern Georgia into northern Florida. Extreme drought (D3) grew in south-central North Carolina, northern and southern Georgia, western Florida and southern South Carolina. Severe drought (D2) expanded in northwestern and southeastern North Carolina, and moderate drought (D1) saw a slight increase in central South Carolina.
There were some pockets of beneficial rain that led to minor localized improvements. This rain helped trim severe drought (D2) to moderate drought (D1) and abnormal dryness (D0) in small parts of western Virigina and eastern North Carolina.
South
Hot and dry weather dominated the South this week, leading to widespread drought degradation. The heat coupled with persistent dryness caused month-to-date rainfall deficits to grow to 1 to 3 inches below average. This represents only 5 to 50% of normal.
Deteriorating short- and long-term indicators justified the introduction and expansion of exceptional drought (D4) in southern Texas and northern Arkansas. Extreme drought (D3) was introduced in the Oklahoma Panhandle and expanded across central Oklahoma, Texas, Arkansas, Louisiana and Tennessee. Moderate drought (D1) and abnormal dryness (D0) expanded as well in Texas, Mississippi and southern Louisiana. Over 80% of the South region is now reporting some form of drought.
There were no spots that saw drought or abnormally dry conditions improve this week.
Midwest
A wide range of weather impacts were observed throughout the Midwest region last week. Unseasonably warm temperatures occurred throughout most of the Midwest, especially in western Illinois and southern Missouri. In contrast, parts of Michigan, Wisconsin and Minnesota ended up with below-normal temperatures in the past week.
Precipitation was also highly variable. Northern and eastern areas received one-half inch or more of liquid precipitation, with some locations seeing 150 to 300% of normal weekly rainfall. However, the southern half of the region largely missed out on precipitation, picking up as little 5% of normal rainfall.
The above average rainfall and corresponding improvements in streamflow and soil moisture led to the reduction of extreme drought (D3) and severe drought (D2) in Indiana and Ohio, along with severe drought (D2) improvements in Illinois. Moderate drought (D1) and abnormal dryness (D0) were also trimmed across Illinois, Indiana, Ohio and northern Michigan.
Conversely, growing precipitation deficits and degrading conditions in these southern areas led to the expansion of moderate drought (D1) in parts of Iowa and Missouri, as well as an increase in abnormal dryness (D0) in northeastern Ohio.
High Plains
Intense, unusual warmth gripped the High Plains last week, with temperatures soaring up to 25 degrees above normal, peaking in parts of Wyoming and Colorado. Precipitation was nearly non-existent, particularly across the southern half of the region. This severe, persistent dryness coupled with rapidly deteriorating drought indicators force widespread expansion and intensification of drought categories.
Exceptional drought (D4) expanded in northwestern Colorado, while extreme drought (D3) grew across Colorado, southern Wyoming and southern Nebraska. Severe drought (D2) pushed further into central and northern Wyoming, western and southern Colorado and from Nebraska into South Dakota. Moderate drought (D1) and abnormal dryness (D0) also expanded broadly across Wyoming, Colorado, Nebraska and Kansas. Even worse, a record-breaking “snow-drought” is occurring in the mountains of western Colorado, with snowpack water equivalent much less than has ever occurred in the past 40 years.
There were no spots that saw drought or abnormally dry conditions improve this week.
West
Anomalous warmth dominated the West, with nearly much of the region seeing temperatures range from 15 to 25 degrees above normal. Precipitation was largely absent, save for beneficial moisture in parts of Washington and Montana. This localized precipitation allowed for the reduction of severe drought (D2) in central Montana and abnormal dryness (D0) in western Washington.
Elsewhere, the combination of soaring temperatures, lacking precipitation and declining soil moisture and streamflow data resulted in broad drought degradation. Extreme drought (D3) expanded in southern Idaho, central and northeastern Utah and northwestern New Mexico. Severe drought (D2) increased in coverage across Oregon, southern Idaho, southern Montana, southern and eastern Utah, southern and eastern Arizona and New Mexico. Abnormal dryness (D0) expanded in eastern Oregon and central and eastern California.
There were no spots that saw drought or abnormally dry conditions improve this week.
Looking Ahead
Much of the contiguous U.S. is expected to see widespread, record-breaking warmth driven by a strong ridge of high pressure over the western and central regions. Temperatures may run 20 to 40 degrees above average, with dry conditions and gusty winds increasing fire weather risks across the High Plains, especially midweek. Stronger winds are also anticipated in the northern Rockies due to a deepening low-pressure system.
At the same time, a powerful storm system will move from the Pacific Northwest across the nation. Early in the period, it will bring moderate to heavy rain to the Northwest, raising some flooding concerns. There were also be some snow in higher elevations like the Olympics and Cascades. After weakening over the central U.S., the system is forecast to strengthen again in the East, producing rain in southern areas and a mix of rain and snow across the Great Lakes, Ohio Valley, and Northeast by late week.
------
Source: U.S. Drought Monitor