As April comes to an end and the United States surges deeper and deeper into spring, average temperatures in even the coldest spots will rise above the freezing mark. However, yet another surge of cold air into early this week will make winter coats a necessity across the northern Rockies and Plains states.
A strong dip in the jet stream will work in tandem with a cold front near the surface to send a pool of dry, arctic air across much of the western half of the country early in the week.
The air mass, originating from the Yukon and Northwest Territories in Canada, is arriving across Montana and North Dakota currently before pushing south into Colorado and Minnesota on Monday and as far south as northern Texas on Tuesday.
Within the heart of the cold air, mean temperatures will reach values of 20 degrees or more below seasonal averages. To put that into perspective, many locations from Great Falls, Mont., to Dodge City, Kan., will experience temperatures much more common of late January or early February than the end of April.
Precipitation will accompany the leading edge of the cold air, and several inches of snow are also likely to fall from Montana and Wyoming into tonight before expanding eastward into western portions of the Dakotas, Nebraska and northern Colorado on Monday and Tuesday.
Fortunately, storm total snow accumulations with this cold front are not expected to be as high as those of the most recent storm system which was responsible for close to a foot of snow from Cheyenne and Casper, Wyo., to areas just west of Denver, Colo.
The cold air will modify a bit on Wednesday and Thursday as the air mass expands south and east, but temperature departures greater than 10 degrees below normal will still be possible as far south as Lubbock, Texas, on Wednesday and as far east as Des Moines, Iowa, on Thursday as the cold front speeds towards the Great Lakes.
Winds aloft in the atmosphere will shift from the northwest to the west as the week progresses, allowing temperatures to moderate back to near average late-April warmth by the weekend.
Ahead of an approaching storm system, unseasonable warmth will overspread much of the United Kingdom on Sunday and Monday.
With no exact details on where Malaysia Airlines Flight 370 went missing, Indian Ocean currents may have swept one piece of the complicated puzzle to shores on Reunion Island.
The stream of moisture into the Southwest is drying out some, so this weekend may not be as wet as the previous few days.
Life-threatening heavy rainfall will continue to focus on northeastern India, Bangladesh and western Myanmar into Monday before a drier weather pattern sets in.
Heat and humidity remained in control over the much of the country during the last week of July.
The air felt like an exceptional 163 F in Bandar Mahshahr, Iran, on Friday and similar or worse conditions will follow.
Mansfield, OH (1992)
13.23" of rain in July -- wettest month on record.
Moline, IL (1992)
11.40" of rain -- wettest July on record.
La Crosse, WI (1992)
August temperature only 68.0 degrees for month; coolest since July 1891.