An active pattern is more-or-less coming to an end this week. Several strong systems have moved through the contiguous U.S. during the last few weeks, bringing widespread moderate to heavy precipitation and severe weather. This has allowed much of the country to see reduced dryness and drought, but not everywhere.
The Northern Plains, specifically North Dakota, have seen intensifying drought. Some areas right around the Great Lakes along with western Texas have also seen some dryness increases. The drought in North Dakota is the biggest concern for rangelands and livestock as temperatures increase and allow pastures to exit dormancy with little soil moisture to draw from.
An upper-level trough currently in the Northern Plains and central Canada March 30 is producing a strong cold front across the U.S. midsection. Ahead of this front, temperatures have been well-above normal by some 20 to 25 degrees Fahrenheit (roughly 11 to 14 degrees Celsius). However, behind the front temperatures are plummeting 10-20 degrees F (roughly 5-10 degrees C) below normal.
The significant drop in temperatures may be concerning for vulnerable winter wheat, but the low temperatures will not last more than two days for most areas. This quick-moving upper-level system will be replaced by a broad ridge for Easter weekend and temperatures will swing higher by a similar 20-25 degrees F (roughly 11-14 degrees C) range across a wide area from the West through the Plains and Midwest. Some mild weather may hang on over the Southeast, but that will only be briefly as temperatures continue to rise next week.
A wild swing in temperatures during the course of a couple of days should not surprise anyone. This is typical for a transition season like spring. What should be a little surprising is the general lack of precipitation that this system is producing. Such large temperature swings create stronger upward motion, which produces clouds and precipitation. However, despite all the precipitation we have seen during the last two weeks, moisture in the lower levels of the atmosphere ahead of this system is surprisingly low. It will take moisture from the Gulf of Mexico to light this front up, which should be confined to the Southeast and East Coast later this week.
The dryness is a touch concerning for those drier areas that still need to see more precipitation to feel confident about spring planting season. But there may be some good news in the medium range.
The broad ridge of high pressure that will encompass the majority of the country this weekend will slide to the East next week and a trough will move into the West.
The trough will send a few pieces of energy through the country next week, which may be a trigger for precipitation east of the Rockies. Models still have time to change, but there will be at least some chances for precipitation still this spring. This includes the dry Northern Plains. There could be several chances for meaningful precipitation here, which would be very helpful indeed.
I should remind people that we are still in a La Nina pattern, though it has weakened considerably during the last couple of months. Models are more convinced that the La Nina pattern will dissolve this summer, though remain around a neutral or negative-neutral state.
However, even with neutral temperatures in the equatorial Pacific Ocean, there is not a large correlation with wet weather for the summer or fall. An overall picture of heat and dryness this spring is likely to remain the case.
John Baranick can be reached at firstname.lastname@example.org
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