Saturday, October 8, 2022

The good and bad of prolonged dryness, and when rain will fall again

The big weather story for the Mid-South is the arrival of beautiful fall weather that has stuck around for a few weeks now. While fortunate in that we can enjoy some terrific weather and not worry about rain-out's, the flip side is that drought is once again taking hold on the region, affecting everything from allergies due to dust and other foreign debris in the air to Mississippi River traffic that is severely limited by low water.

The Drought Monitor for this past week shows expanding dry conditions across the region, including Moderate Drought in the southern and western metro. (UNL Drought Monitor)

Precipitation the past 30 days

The last 30 days or so has featured one "round" of precipitation - scattered storms on Saturday evening, September 24 that brought very heavy rain to some and little to none for others. A look at the 30 day rainfall anomalies (below) shows that much of the region, especially west of the river, has received less than 25% of normal precipitation in the past month - in fact much of Arkansas has not had a drop of rain.

Rainfall anomalies (as a percentage of normal) for the past 30 days are significantly below normal, in fact near 0% for much of AR into OK and TX and well below 50% for our area. (WeatherBell)

Effects on the Mississippi River

The bigger picture is that the lack of precipitation throughout the Mississippi and Missouri River Valleys has resulted in water levels on the river that are in the top 10 lowest on record. Barge traffic has been reduced to a trickle through our area, which is starting to affect supply chain, particularly for agricultural goods that flow south on the river from harvested land in the Midwest. The lowest reading of late was -.8.2 feet on October 3, which ranks 7th lowest on record. While up just a bit, the river is forecast to get that low again within some much-needed rainfall, especially up-river.

The hydrograph for the Mississippi River at Memphis points to water levels well below the "low stage" of 5 feet, running between 5-8 feet below zero so far this month. Projections are for water levels to remain historically low well into October. (NWS/AHPS)

Looking ahead

In the wake of another dry cold front on Thursday evening, we are once again enjoying an amazing weather weekend with sunshine, highs in the 70s, and crisp mornings. Today (Saturday) will likely be the coolest day in Memphis since April, and tonight, all Mid-South residents will see temperatures drop into the 40s, while some frost will be possible in northern reaches of the Mid-South. 

The week ahead features a warming trend ahead of another cold front that arrives early Thursday. We'll be back in the low 80s Monday, then the mid 80s for the mid-week period, though low dewpoints will allow for mornings to still be pleasantly cool for a few days. By Wednesday, clouds will increase, as will humidity, setting the stage for a decent chance of precipitation for many of us. The most likely timeframe for rainfall will be Wednesday night (satisfying many of you who would like rain, but not during the day so you can enjoy the fall weather!). A few thunderstorms cannot be ruled out as dewpoints climb into the mid 60s. While projected rainfall totals aren't overly impressive, anything will help at this point! 

Forecast precipitation from the National Weather Service through mid-day Thursday.  About one-half inch is forecast in the metro. Here's hoping we all get that much, or more! (WeatherBell)

Behind the front, sunshine returns Thursday and continues into next weekend, with another shot of cool weather as well. Highs will be back in the 70s through next weekend with morning lows in the 50s. 

There are signs of an even bigger cool down about 10 days out as we get deep into mid-October, but we'll see how that plays out. In the meantime, we've got one decent chance of rain late Wednesday into early Thursday to plan around, otherwise Fall Break looks pretty good!

Erik Proseus
MWN Meteorologist

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