A new cold front every few days

Published 12:16 pm Saturday, November 20, 2021

By Skip Rigney

Cold fronts are passing through more and more frequently as we head into late November, driven by waves of low pressure moving quickly along the jet stream miles above the earth’s surface.

On Thursday afternoon a line of showers along such a cold front began to dissipate as it entered Pearl River County. About a third of the county, mainly in the north, received a few hundredths to one-quarter of an inch of rain. Those in the south got none, continuing a drought, which for some is now entering its fourth week.

Behind the front, north winds transported in cold and dry air that just a few days ago had been above the Dakotas and Nebraska. That air kept our high temperatures capped at about 65 on Friday, and gave us lower 40s this morning (Saturday).

However, the current pattern of winds in the upper atmosphere is quickly pushing the surface high pressure system associated with this cold air eastward. The high was centered over Illinois on Friday. Today it is centered 600 miles farther east over Virginia.

That means we have gone from being in the cool southeastern quadrant of the high’s clockwise circulation to the warmer southwestern quadrant. Our winds have veered to the east and southeast. Those factors will combine with sunshine to allow temperatures to climb into the lower to middle 70s on Saturday afternoon. Sunday afternoon will be even a little warmer.

Don’t get used to the warmth, because with this fast-moving pattern, two new cold fronts are already dropping southward through the Great Plains. By Sunday evening the two fronts will combine into a single, strong cold front as they enter Mississippi. There’s a chance of light showers ahead of the front, but as with the last few fronts, rain is not guaranteed.

After the front passes late Sunday night, winds will shift to the north and high pressure will once again build in from the northwest. Monday will be windy and sharply cooler.

Tuesday will be even colder with temperatures starting out in the lower to middle 30s, and may barely make it to 60 for a high. But, in the spirit of the old saying, “If you don’t like the weather, just wait a little while,” a warming trend will get underway Wednesday with afternoon highs climbing back into the upper 60s or lower 70s both Wednesday and on Thanksgiving Day.

Fortunately, for those with holiday travel plans, Tuesday and Wednesday look dry, not only here but across much of the country.

But, in keeping with the rapidly moving weather pattern, another disturbance will already be upstream from us.

A low pressure system, much further south than any we’ve seen lately, is predicted to be in southern California on Wednesday and northern Mexico by Thursday.

Although our rain chances aren’t zero on Thanksgiving Day, it appears that most of the messy weather associated with the low will stay to our west that day in Texas, Oklahoma, and Arkansas. The exact timing is uncertain, but the low will continue heading our way, and sometime between Thursday night and Sunday morning will give us our best chances of significant rain in Pearl River County since late October.