ROLLING DOWN THE RIVER, BARELY...
Living on the Mississippi, it's easy sometimes to take the girth of the worlds second longest river for granted. However, in the midst of a drought it's easy to see the big river has shrunk to levels rarely seen. Wing dams and sand bars are exposed and with the dry pattern expected to continue in the upper reaches of its massive drainage system, the potential is there for it to reach historically low levels in spots.
Last week, the low water levels prompted the closing of the main channel to barge traffic at a crucial time of the year for the transport of crops from our nation’s heartland. The Army Corps of Engineers has been dredging portions of the river in an attempt to deepen channels and get barge traffic up to speed again. But the recent closures and reduced channel size have contributed to the massive tie-up in the nation’s already challenged supply chains.
The low water levels were responsible for eight barges running aground last week. According to the US Coast Guard, there were 144 vessels and 2,253 barges queued up and waiting to get through two stretches of the river where traffic was halted.
Dredging on big Muddy
For the time being traffic is moving again thanks to dredging efforts but barges may be forced to carry as much as 20% less cargo than normal in order to not ride too deep in the water. And rather than a single vessel moving between 30 to 40 barges at one time as they typically do, they’ve been forced to move no more than 25 barges on each trip due to the more narrow channels.
The combination of fewer barges per trip, and less cargo per barge, has cut the capacity of barges moving on the river by about 50% even before the recent river closures, said Mike Seyfert, CEO of the National Grain and Feed Association. And that has sent the rates that shippers are paying soaring.
In Dubuque, where .14" of rain has fallen the past 30 days, the Tuesday stage of the Mississippi at the railroad bridge was 7.46 feet. The lowest ever for that date is 6.50".
Over the next 7 days, the stage in Dubuque is projected to remain at or slightly below the current level.
Further downstream at lock and dam 15 in Rock Island the stage report was missing Tuesday. However, the projected stage Wednesday is for 3.90 feet which is less than a foot above Tuesday's historic low level of 3.00 feet.
The good news is that some rain did fall Tuesday. However, the majority of the heavier amounts were in the southeast. What little run-off there was will head downstream and have no meaningful impact on rivers and streams from here north. These are the doppler estimates from Tuesday's rain. Some amounts greater than 1/2 inch were noted just southeast of the Quad Cities. Another narrow band of heavier rain fell in a small swath from Tipton and Maquoketa to Savanna and Freeport. My northwest counties which needed the rain the most were left high and in some cases dry.
Overnight a cold front has been steadily advancing from the northwest. It's generated some additional showers and even a few storms. What remains of that will be scattered around the the region Wednesday morning. These should be light to perhaps moderate in nature and out of the east by noon. Some guidance shows 1/4 to 1/2 in amounts in narrow bands. More general totals of 1/10 to 2/10ths of an inch are expected in most areas. After that, strong cyclonic flow kicks in that could pop a few more instability showers late in the afternoon or evening. They appear to be spotty and brief in nature. Winds which gusted to 40 mph overnight will ease a bit as they turn to the NW behind the cold front. Even so a blustery is in store with gust up to 30 mph. Temperatures Wednesday will reach the low 60s far north to the mid to upper 60s elsewhere.
Strong cold air advection spreads through the region Wednesday night sending temperatures spiraling downward. Lows by Thursday morning should reach the upper 30s north to the low 40s south. That sets the area up for a very fresh day Thursday with highs remaining in the upper 40s north to the mid 50s far south. Again the strong cyclonic flow could bring periods of clouds and some isolated brief showers, mainly in the north. The hi-res HRRR shows temperatures at 2:00pm Thursday that look like this.
Wind chills in all but the far south are in the 30s and 40s.
The weekend will be very much on the cool side but uneventful as the region remains in a blocked pattern dominated by a cold core upper level low at 500mb. That should keep temperatures generally in the mid to upper 50s Friday, Saturday, and Sunday. A reinforcing lobe of strong vorticity pivots through the trough and around the upper air low Sunday. It serves to strengthen and re-establish the closed low aloft. As a result, even colder air is shown entering the pattern Monday and Tuesday when highs are likely to remain in the 40s in all but my far southern counties near the Missouri border. These are the 5 day temperature departures for the period Saturday through next Wednesday.