After wet April, May to start dry

Published 7:00 am Tuesday, April 28, 2015

Average rainfall totals for the month of April in Pearl River County are about five inches.  With still a few days to go, April 2015 has been significantly wetter than normal in the southernmost part of the county. As of Sunday, rain gauges in southern Pearl River County have collected between nine and twelve inches of rain during the first 26 days of April. Rainfall accumulations have been less farther north in the county with totals dropping off to much closer to the monthly average of five inches.

Over half of the rain near Picayune fell on just three days: April 5th, 14th, and, this past Saturday, the 25th. Not only have there been some big rains, our number of days with rain has been higher than normal. On average, it rains on about one-third of the days in April. So far this April rain has fallen on about two-thirds of the days.

Showers and thunderstorms yesterday and today will add to the April totals, but these should be our last days with rain for the month.

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The primary cause of the rain Monday and Tuesday is a strong, well-defined low in the middle and upper levels of the atmosphere moving slowly from the southern Great Plains eastward into the lower Mississippi River Valley. An associated surface low will move out of Texas eastward along a weak, stalled frontal boundary across the northern Gulf and will pass by us tonight. This is a classic setup for possible heavy rain, and as of Monday morning, the National Weather Service in Slidell had issued a flash flood watch for our area through at least this morning. Additionally, a few of the thunderstorms kicked off by the low before it passes to our east could be severe in the southernmost parts of Louisiana, Mississippi, Alabama and into the Florida panhandle.

Our rain chances will drop to near zero for the rest of the week as the low moves off to our east and then up the Atlantic coast of the southeast U.S., and a ridge of surface high pressure extends all the way from the Canadian prairies southward through the U.S. Great Plains and Texas into northern Mexico.

 The north winds on the eastern side of the ridge will bring us dry air and below normal temperatures Wednesday through Friday. Morning lows will be in the 50s with temperatures climbing through the 60s into the 70s each day with low humidity. Temperatures on Wednesday may not even make it out of the 60s.

 As with almost all of the large weather systems that affect us during every season except occasionally in summer, the surface high will slide from west to east. By Saturday we will be on the western side of the ridge. This means our winds will veer around first from the east and then to a more southerly direction, and higher humidity will begin their return. But, it doesn’t look like there will be any strong triggers for lifting that moister air, and so, the upcoming weekend looks to be dry with seasonable temperatures.

By Skip Rigney.