2023 Harvest Weather Outlook
September 12, 2023 | By ForGround by Bayer
The weather impacts many farming operations, and the folks at BAM Weather and ForGround by Bayer are trying to help you make more informed farming decisions. The conditions will vary across regions and from field to field, so here are some considerations to make if certain weather scenarios come to fruition.
Quick Takeaways for Your Farm:
- Soil moisture through the region is lacking and near-term dry weather may influence cover crop seeding.
- A transition from warmer than normal to cooler than normal in the next few weeks may require quick planning to capture the waning growing or plan for delayed harvest and cool weather.
- An early frost may limit growth of warm season cover crops.
- The lack of soil moisture for some areas is already a concern for cover crop water use next spring, which makes maintaining surface residue even more valuable.
Current ENSO Forecast:
The largest pattern driver to the upcoming forecast across September to November will be the ocean temperatures in the Pacific. With high confidence, El Niño will be present heading into the autumn months. Specifically, above average warmth will be notable in the eastern portion of the Pacific and this is classified as an “eastern-based Niño” as opposed to a conventional El Niño. The eastern-most two sections of where water temperatures are measured across the equator are Niño 1 +2. The three images below with a green highlighted box serve as the best interest to above normal sea surface temperatures.
The current El Niño reading sits at 0.8 degrees above average. This means that the waters along the Pacific are nearly 1.0 degrees above normal. This value is favored to increase to near 1.3-1.6 degrees through fall. El Niño conditions are favored to persist throughout autumn and into winter, with potentially a strong Niño (greater or equal to 1.0 degree) by October.
The years similar to how we see this September/October play out continue to be those with more of an eastern-based Niño (boxes in image below). Closest years are 1997 and 2006 as eastern-based Niños were observed during this time of the year. Other years that follow similar progressions are 1994, 2002, 2009 and 2018.
Soil Moisture Outlook
Above is the latest Root Zone Moisture status as of September 4. The areas outlined in green have favorability to see improvements in excessive dryness through November. The areas in red are at risk of seeing deterioration through the same time period. The areas with no color overlay have a neutral look or only slight leans towards improvement or deterioration. Western KS and NE are at risk of seeing slight improvements in soil moisture, but not a substantial improvement due to the large deficit endured throughout late August into early September. The lower Ohio Valley can anticipate an active look with slight improvements as well. The Deep South will also feel active flow from the southern jet. As such, already saturated soil moisture is anticipated to stay moist. The best opportunity for precipitation in areas at risk for deterioration will come earlier in the September-October-November timeframe, more towards late September into early October. However, as we progress into late October-November, look for this location to see increasing dryness that will average out to overall drier soil.
>>>>> What Does This Mean for Your Farm?
The current deficit of soil moisture is concerning for cover crop seeding and even planning for next spring. Some areas should consider waiting until there is moisture for seeding cover crops, if you are able; however, seed availability and equipment may limit your flexibility. Leaving crop residue after harvest can help reduce soil evaporative losses and keep as much soil moisture as possible. Pro tip: make sure that residue is distributed evenly behind the combine and leave those stalks standing to catch snow and prevent the wind from blowing the husks away.
Late September/Early October Outlook
Expect the eastern third of the US to continue to hold onto below normal temperatures heading into the third week of September from the late week 2 storm system (September 13-15). A second storm system will work in towards the last week of the month near the Great Lakes that will continue to keep temperatures below normal. Support from tropical forcing in the Pacific along the equator also lingers. Eastern US coolness to close the month and heading into week 4 of the month. There can be some moderation across the Central US with small ups and downs from average as storm systems work through, but generally favored to be slightly above normal.
Active flow will likely be present across the Central US for locations between the trough in the east and the ridge in the west. There is some lower confidence regarding exact placement of where the wettest risks setup, but KS and MO will be at play for waves of precipitation from the north with descending storm systems. The Great Lakes will be at risk of being drier if some of the flow from storm systems becomes too northerly with cooler air sinking in. The further we progress into week 4, the South Central looks to become more active with the southern jet stream and tropical influences.
Due to support from the anticipated increasing global winds as well as tropical forcing, the Midwest is at risk of verifying even cooler than forecasted. A tropical system around September 15 would also support some continued cooler risks. If that same area of coolness is more concentrated, more warmth can bleed in underneath and cause the Southeast to verify warmer than normal as opposed to near normal.
For precipitation, there is risk for the Southern Plains and Deep South to be wetter as the southern jet and tropical influences will become increasingly active the further we progress into September. If storm systems across the Ohio Valley and Midwest can draw in a stronger arctic (unseasonably cool) air mass, there will be a drier risk as the air flow can be too northerly. This will in turn cut off precipitation chances from the west.
>>>>> What Does This Mean for Your Farm?
The next few weeks may prove to be very challenging when deciding when, if and what type of cover crops should be seeded. It’s currently warm enough for good cover crop growth, but many areas are limited on moisture. The best advice is to pay close attention to the forecast and remain flexible on cover crop seeding methods and type. If time gets away from you, there may be some custom operations that can seed cover crops for you.
October/November will hold cold risks as a whole, as our top analog years for eastern-based Niños support a colder look to the interior US with warmth along the coastal regions. Top years include 1997, 2006 and 2018. Other years with loose correlations are 2002 and 2009.
It will be worth monitoring the strength of the southeast high pressure. The lower Ohio Valley and Deep South are in favorable locations for active gulf stream moisture sitting to the west of the high pressure. As such, these locations hold the best threat to end with above average precipitation.
Fall Forecast Risk
Due to September being well above normal across the central US, it will be dependent on how soon the pattern can flip heading into October for more below normal temperature to enter the Central Plains. As a result, despite having October/November trending toward below normal temperatures, the result is still warmer than average risks for the central US.
This would couple with the drier risk in the Central Plains as the remainder of September will be slightly below normal for precipitation. October and November will hold more active shots of precipitation in the Central Plains, but the question will be if it can overcome the deficit of rain in September.
Preliminary Frost/Freeze Forecast
Above is our first official frost/freeze forecast for this fall. Years factored into the forecast (given a similar pattern progression) include 2018, 2015, 2009, 2006, 1997 and 1991. Overall, there is a consistent and strong signal for an earlier-than-normal frost/freeze risk for the Ag Belt. This is especially true for the Eastern Ag Belt (Ohio Valley) with colder signals likely in early-mid October. The first frost threat for the Northern Plains appears to only be slightly earlier than normal given a warmer pattern for much of September.
Overall, this is one of the stronger early frost/freeze signals we have seen and confidence is above normal for that potential at this time.
>>>>> What Does This Mean for Your Farm?
An early frost can be highly variable across and within regions. A hard freeze can kill sensitive species, but a light frost may not make an impact. The small difference of a few degrees can make a significant difference. They key consideration here is how this may limit growth of your late summer planted cover crops.
Crop Residue: Your Soils Protective Shield. November 2022. ForGround by Bayer. https://bayerforground.com/resources/crop-residue-management
Cover Crops and Planting Strategies. July 2023. ForGround by Bayer. https://bayerforground.com/resources/cover-crops-and-planting-strategies
Midwest Cover Crop Council Cover Crop Species Selector Tool: https://www.midwestcovercrops.org/selector-tool/
Plant Cover Crops ASAP. August 2019. Penn State University Extension. https://extension.psu.edu/plant-cover-crops-asap
Seeding Cover Crops in Dry Conditions. August 2017. Iowa State University Extension. https://crops.extension.iastate.edu/blog/angie-rieck-hinz-meaghan-anderson/seeding-cover-crops-dry-conditions
Legal Statements ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower's fields.