Nationwide
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Hurricane Zeta made landfall near Cocodrie in southeastern Louisiana during the late afternoon on Wednesday, October 28, as a Category 2 hurricane with sustained winds estimated at 110 mph.
With a fast northeastern track that took it off the mid-Atlantic coast in about 24 hours, the rapid pace limited rainfall totals along its path to between 2 and 4 inches, with locally heavier amounts in southern Mississippi and Alabama of up to 8 inches. Unfortunately, the fast pace delayed the weakening of Zeta’s winds, and widespread wind damage and power outages occurred along Zeta’s path, even into the mid-Atlantic.
In addition, as the period started, an upper-air low over the southern Rockies slowly tracked eastward, becoming infused with tropical moisture from Zeta and the Gulf of Mexico. It dumped 1.5 to 3.5 inches of precipitation, locally to 5 inches, from the western Oklahoma and northern Texas Panhandles eastward across northern Oklahoma and southern Kansas, southern Missouri and northern Arkansas, and into the Ohio and Tennessee Valleys.
Although the precipitation was very beneficial to the winter wheat crop and pastures, some of the precipitation fell in the form of snow and freezing rain in western Texas, Oklahoma, and Kansas, causing damage. Once the upper-air low and Zeta cleared the East Coast, much drier and colder air rushed into the Northeast and Southeast, with light snow accumulating across parts of western New England and upstate New York.
Elsewhere, little or no precipitation occurred in the Far West, Southwest, Rockies, southern and northern Plains, and upper Midwest. Subnormal weekly temperatures enveloped the Midwest, southern and central Plains, and Northeast, while the West, Rockies, and Southeast experienced near to above-normal readings.
The West
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Dry weather prevailed across the entire West, with only light precipitation (less than 2 inches) reported in western Washington and the extreme northern Cascades.
Temperatures gradually increased during the week, with most locations averaging at or above-normal weekly anomalies. With beneficial precipitation falling the previous week (Oct. 21-27) across the Northwest and Rockies, no deteriorations were made this week where precipitation fell in late October.
However, with two consecutive weeks of no precipitation, the wet season that should be in full swing by now, and lingering long-term impacts, some slight deterioration was made in Oregon (D2 and D3 expansions) and southwestern Idaho (Elmore County to D1). In northern Colorado, D4 was expanded into northern Routt and northern Grand Counties, which missed significant precipitation two weeks ago, with SPIs, evaporative demands, and precipitation out to 6-months at D4 levels. No changes were made in the Southwest as October and November are climatologically dry.
In contrast, additional investigations to last week’s precipitation called for improvements to central Idaho (D0 removed in Clearwater Basin) and south-central Colorado (D3 and D2 reductions) from recent precipitation and overall favorable impacts.
The High Plains
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With much of the region cold and dry this week, status-quo was the norm for most states that either received precipitation two weeks ago (Wyoming, Montana, the Dakotas) or deteriorations were made (North Dakota).
Unfortunately, southern Nebraska and northern Kansas missed out on precipitation during late October, thus some degradations were made there. With short-term (out to 90-days) SPIs much drier than D1 and 90-day rainfall less than half of normal – producing 4-6 inch deficits – D1 was extended across northern Kansas and into southeastern Nebraska. D2 was slightly expanded into northwestern Kansas and southwestern and northeastern Nebraska.
Wetter conditions at 4-months limited the deteriorations made this week, along with a dry climatology during October and November.
In contrast, the upper-air low trekked from the southern Rockies to the mid-Atlantic. It became infused with Gulf moisture courtesy of Hurricane Zeta dumped welcome and heavy precipitation (1-4 inches) across southern Kansas, effectively allowing a 1-category improvement across the southern third of the state. The middle third of Kansas remained unchanged.
The South
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As the week started, the upper-air low over the southern Rockies tapped Gulf moisture, bringing welcome and beneficial precipitation (1.5-5 inches) to the south-central Plains.
Unfortunately, the demarcation of the haves versus have-nots was sharp, with southern Kansas, the northern half and far eastern Oklahoma, and the Panhandles of Oklahoma and Texas coming out favorably.
Accordingly, the copious precipitation resulted in 1- and 2-cat improvements, particularly in northwestern Oklahoma, where 3-5 inches fell, including some light amounts the previous week. Western Texas, much of it in D3-D4, did receive some light precipitation (0.25-1 inch) but could have used a lot more, and improvements were minimal.
In contrast, little or no precipitation fell in Texas’s southern half for the second consecutive week, resulting in additional degradation. October usually is one of the wetter months in south-central Texas, so with many locations measuring less than 25% of normal the past 30 days, short-term deficits have rapidly accumulated. USGS 7-day average stream flows have also picked up on the dryness, with many gauges in the much below category (less than the tenth percentile). — UNL Drought Monitor
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