Written by Sig Silber
Updated at 5 PM EDT August 31 to reflect the updated Week 3 – 4 forecast and the one-month drought forecast for September.
We expected more improvement but it did not happen. Looking ahead there are a lot of questions about the precipitation forecast so we may get a lot of relief over the next two weeks or not so much. The updated September and Week 3 – 4 forecasts will be issued tomorrow. Tonight we also provide updates on Lakes Mead and Powell on the Colorado River which are developing into a major long-term problem.
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New Forecast which covers September (It will has just now (Friday) updated)
Information sources: Although not limited to the following, most of the material in this report comes from:
- The U.S. Drought Monitor (full report can be accessed here)
- Selected parts of our Weekly Weather and Climate Report (Monday’s full report can be accessed here) which has forecasts for the next 25 days and which auto-updates
- Selections from the Tuesday USDA Weather and Crop Bulletin (full report can be accessed here). Other useful sources of information that I regularly utilize are the National Integrated Drought Information System (NIDIS) which can be accessed here and the USDA NRCS Weekly and Weather Climate Update which can be accessed here.
Remember if you leave this page to go to links or if you have clicked to enlarge a graphic, in order to get back you need to hit the return arrow usually located on the left of your URL box on the upper left of the screen. Also most of the small graphics are designed to become full size when you click on them. If that does not work, an alternative way to view the larger graphics is to right click and then hit “view image”. That should always work.
This report is now organized as follows:
- Present Drought Conditions
- Last Week’s Weather
- Information from our Weekly Weather Column (the forecast maps auto-update) and combined with brief commentary from me provides a forecast which I attempt to interpret re the likely change in drought conditions
- U.S. Crop Information
- International Crop Information and related weather
- Prior month’s weather and month-to-date weather excluding the prior week when I have that information. Drought is based on cumulative deficits.
- A science theme if we have one.
- Reference Information.
1. Present Drought Conditions
The U.S. Drought Monitor is a comprehensive way of understanding the drought situation for the U.S. It is issued every Thursday and reflects the conditions as of the prior Tuesday. Drought is defined as a moisture deficit bad enough to have social, environmental or economic effects. Thus, more factors than recent precipitation are considered and more information on how it is done is found at the end of this report.
Below is the same map but just CONUS and with statistics and below that map I have provided a cut-out of the statistics which I think you can click on to enlarge.
The graphic below shows the one-week change in drought intensity. Yellow is bad. Green is good.
This pair of maps might make it easier to get a general idea of what is happening in the worst part of the drought area.
Last Week | This Week |
This map may be useful also.
Now we show the same information by region. The yellow is where the drought has been upgraded.
Improvement in Kansas |
Mostly moderate improvement. |
Essentially no change |
Improvement Arkansas, deterioration Texas especially near the Gulf Coast |
Slight deterioration |
Mixed. Some improvement for Utah and Colorado but southern Oregon and Northern Nevada had deterioration. |
Some may find this way of looking at things useful and I hope these graphics are not too small to read. I did not make them so you could click on them individually but you can click on the whole graphic and it may enlarge. But I think you get the picture. It has been a rapid onset and hopefully it’s demise will also be fairly rapid.
Some might find this animation of twelve weeks of change useful;
Here is the discussion which was issued with the Drought Monitor today.
This Week’s Drought Summary
Frontal systems brought thunderstorms and some heavy rainfall to parts of the Plains, the Midwest, and the South. While rainfall was enough to reduce or alleviate drought conditions in some places, such as Arkansas, northern Missouri, Kansas, Wisconsin, and Michigan, it wasn’t enough in other areas, such as southwestern Missouri and Idaho, as deficits and impacts remain. This past week saw temperatures slightly below average across much of the nation, with areas of eastern Montana and western North Dakota 4-8 degrees F cooler than normal, which helped to slow, but not halt, drought development. Conversely, parts of the Southwest, Texas, and areas along the eastern northern tier of the U.S. were well above their average temperatures. In Texas, notably, the widespread heat exacerbated evolving and ongoing drought.
Northeast
Very few changes were made to the depictions in the Northeast this week. Recent wet conditions have relieved shorter-term dryness in most places except for the areas that were already experiencing abnormal dryness (D0) and moderate drought (D1), which generally remained unchanged. The area of D0 in southeastern Massachusetts was reduced, reflecting normal local stream flows and groundwater levels. No changes were made this week to the depictions in the rest f the Northeast.
Southeast
Abnormally dry (D0) conditions along the central North Carolina/South Carolina border expanded southward into the central part of South Carolina, where the region has received limited amounts of rainfall over the short and long term, including less than 1 inch over the past couple of weeks. As noted by a local hydrologist, “while the dry weather has been good for harvesting crops, such as corn, it is starting to impact other crops such as grasses. Stream flows are also down in this portion of the state, especially along the Lynches River Basin.” In northern Alabama, some broad areas received no rainfall and continued to dry, albeit with cooler-than-average temperatures which helped to moderate the summer impacts. Stream flows were below average from Sumter and Pickens through northern Tuscaloosa to Jefferson Counties. As such, a few areas of D0 were expanded in central and northern parts of the state, while a lone pocket in Elmore County improved to normal in the southeast, as did western Baldwin County in the southwestern corner. No changes were made this week to the depictions in Virginia, Georgia, and Florida.
South
Lack of precipitation led to more short-term deficits and thus more widespread abnormal dryness (D0) across northern Mississippi into southwestern Tennessee. To the west, Arkansas saw widespread improvements continue this week due to recent record rainfall and continuing precipitation. The only part of the state that continued to see drought conditions is in the southwest corner, which has missed out on most of the precipitation. Neighboring northwest Louisiana actually saw moderate (D1), severe (D2), and extreme (D3) drought conditions expand a bit. Eastern Louisiana has seen comparatively more rainfall, and D1 conditions improved some near the southwestern Mississippi border. Oklahoma also saw improvements, including the southwest where exceptional drought (D4) improved to D3 and in the northeast, although the area of severe drought did expand a bit into Washington County. As noted in an impact report from a local producer, “over the last 180 days, which is not only the entire growing season but also is the base for cool and warm season forage, we have been considerably below normal in precipitation. That lack of precipitation has impacted us in several ways including the failing of crops, the decline in hay production by nearly half and the reduction in our normal daily weight gain in our cattle due to the lack and decline of forage”. In Texas, with the exception of the northern Panhandle, it was hot and dry, with temperatures climbing into the upper 90s and 100s (F) in many places. In southern Texas, McAllen broke temperature records throughout the week, reaching highs of 104 to 106 degrees F each day. This area has received only about 3% of its typical rainfall over the past couple of months. The Gulf Coast has had almost no rain since a major rainfall event in mid-June. Overall, abnormal dryness and drought conditions remained steady or degraded across most of the state. Perhaps most notably, D3 pockets expanded in several areas.
Midwest
Drought conditions in Missouri improved quite a lot this week, particularly in the north and northeast where there were widespread heavy rains. One small region around Knox and Lewis Counties saw a 2-category improvement where rainfall was particularly heavy (4-6 inches or more). Most of central and southern Arkansas remained status quo as effects linger here, although extreme drought (D3) regions did improve to severe (D2). Abnormally dry (D0) and moderate drought (D1) conditions were reduced in regions across northern Minnesota, central Wisconsin and central Michigan where a series of heavy rainfall events reduced or eradicated dryness in parts of these states. In the area encompassing La Crosse to Adams Counties in Wisconsin, 6 to 11 inches of rain fell in a 12-hour period. Wetsby, in Vernon County, recorded a (preliminary) 9.98 inches from 8 PM Monday night through 7 AM Tuesday morning, marking its record highest 1-day rainfall total, breaking the previous record of 7.17 inches on August 18-19, 2007. Additionally, a record flood wave moved down the Kickapoo River. The flood wave was so high that it knocked out at least three river gauges. In this region, dryness and drought conditions have been completely eradicated. To the southeast, the D0 footprint shrank in northern Indiana where the area received more than twice its normal rainfall over the past week. Unfortunately, northern Ohio mostly missed out on the precipitation and a new region of D0 was introduced in the northeastern corner of the state. There are reports that trees in that area are dropping leaves early due to water stress. No changes were made this week to the depictions in Iowa, Illinois, and Kentucky.
High Plains
Conditions along parts of the northern tier of the U.S. bordering Canada continue to deteriorate. This week the remaining area of normal conditions from northwestern North Dakota into northeastern Montana (see West for more information about Montana) was degraded to abnormally dry (D0). The area has missed out on all the rains from the last few storms and the soil has been very dry, dating back to the previous year’s drought. In Kansas, conditions improved enough to contract D0 in the central and south central part of the state eastward. In east central Kansas, some areas of moderate (D1), severe (D2), and extreme (D3) drought also improved. However, there are still longer-term deficits and impacts remaining in the state. In eastern Colorado, D3 was improved to D2 in Crowley County and northern Otero County, where there were a few isolated thunderstorms in the area over the past week. D2 improved to D1 in southeast Las Animas County and western Baca County, where up to 2 inches of rain fell. Eastern Baca and Prowers Counties also received up to 2 inches of rain, allowing for improvement from D1 to D0. No changes were made this week to the depictions in South Dakota, Nebraska, and Wyoming.
West
Similar to North Dakota, some areas across the northern tier of Montana continued to deteriorate. The area of abnormally dry conditions (D0) was expanded eastward to connect with the dry area in North Dakota. Also along the northern tier, the two severe drought (D2) areas expanded slightly westward. However, improvements were made in southern Beaverhead, Madison, Gallatin, and Park counties in the southwest where precipitation has been more abundant. Conditions there are now considered normal. Drought continues to plague Oregon and grow worse in areas. This week the area of D2 expanded through most of the southern part of the state. In Utah, D2 improved to moderate drought (D1) across eastern Washington County and western Kane and Garfield Counties. This area has received its typical moisture since the beginning of July. No changes were made this week to the depictions in Washington, California, Nevada [Editor’s note: The change map shows some deterioration in Nevada] , Arizona, and New Mexico. Additionally, no changes were made to the depiction in Idaho, but, as an aside, some precipitation did provide enough relief to Boise to make the region smoke free for the first time in a couple of weeks. Conditions still remain dry.
Alaska, Hawaii, and Puerto Rico
Hurricane Lane dumped a tremendous amount of record-breaking rainfall over parts, but not all, of Hawaii this past week, and not necessarily in agriculturally-related drought areas. As such, several areas of abnormally dry (D0) conditions improved to normal. Over Kaua’i, the small area of abnormally dry (D0) conditions improved to normal as it did on Lanai and Kaho’olawe. Over Maui, where windward rainfall was excessive in some areas, the D0 area was reduced toward the southwest. Notably, the area of severe drought (D2) in west Maui is consistent with the large brush fire that went out of control when Lane approached. No changes were made here. Over the Big Island, the 40-50 inch and higher rainfall totals fell mainly in the existing drought-free areas. The area of D0 was scaled back in the west and most was removed on the east side. Local experts continue to monitor the islands to assess how the rainfall impacts pasture conditions. No changes were made to the depictions in Alaska or Puerto Rico this week.
Looking Ahead
Over the week beginning Tuesday August 28, the Midwestern states are expected receive the highest precipitation, including northern Missouri, which as been plagued by extreme (D3) and exceptional (D4) drought conditions. Temperatures are forecast to reach the 90s (F), and even the 100s in places, across most of the central and southern tier of the U.S.. The Northeast will begin with temperatures in the 90s, but is forecast to cool into the 70s and 80s by the end of the Labor Day weekend. Daytime highs in the 70s and 80s are also forecast across much of the northern tier. Southern Florida and the central Appalachians are forecast to receive up to 3 inches of rainfall, while most of the West and the High Plains are expecting a quarter of an inch or less, with no rain forecast for much of the region. Looking further ahead at NOAA’s Climate Prediction Center (CPC) 6-10 day Outlook (September 2-6), the probability of dry conditions is highest in the Northwest from southern Alaska into Oregon, northern Idaho, and western Montana., while wet conditions are most likely across the Midwest, Mid-Atlantic, and Northeast. During this period, below-average temperatures may be seen over the much of the forecasted wet areas — upper Northwest into Alaska — while above-average temperatures are forecast for most of the contiguous U.S., especially the eastern half. Looking two weeks out (September 4-10), the likelihood of above-average temperatures is highest in central to southern California and in the eastern third of the contiguous U.S. The probability of below-average temperatures is highest across most of Alaska and Montana. The probability of above-average precipitation is highest over a swath of the central U.S. stretching northeast from New Mexico to eastern North Dakota, Minnesota, and western Wisconsin, with the highest probability of dryness now expected across Washington, Oregon, and Idaho.
Wildfires are happening.
And we do not want to ignore floods.
Reservoirs
This article provides a little background on the problem.
2. Last Week’s Weather
Here is what happened with precipitation during the most recent week. The maps are in sync with the crop reports.
It is useful to look at temperature in a few different ways.
First let’s look at the Minimum Temperature.
And now the weekly maximum temperature
And for many purposes the average deviation from Normal or Climatology is very useful.
And here is a graphic that pulls a lot of information together. Image provided by the NOAA/ESRL Physical Sciences Division, Boulder, Colorado see website. It shows the demands of the atmosphere for moisture from the ground and is based on temperature, wind, relative humidity and solar radiation. It tells you nothing about how much precipitation you will get but how much you need to retain the same level of soil moisture.
Here is a regional view but a three-month version.
And here is an experimental way of quantifying the above. This was done for Colorado.
And here is one impact – vegetation
Soil Moisture is a very important part of understanding drought.
3. Current Forecast for Precipitation.
First we show the Seasonal Forecast through November which was issued on August 16 with the full Seasonal Outlook and then the Month of September Forecast Issued on August 31. These two forecasts are issued by the same agency but to obtain them you need to access two different links here and here. We either show the latest or both in this report. Sometimes we show them in more than one place in this report for the convenience of the reader. The one month forecast was still showing the August forecast when we went to press Thursday night but the September forecast updated on Friday August 31, 2018.
And now one month forecast for September.
And now the current precipitation forecasts so that we can make our own assessment of the drought forecast. Here I provide the weather forecasts for different periods of time in August which should allow the reader to assess the likelihood of this forecast working out as shown over the next three to four weeks. (Since we publish this week on Thursday, we will update the discussion for the Week 3 – 4 forecast when it is updated on Friday August 31). This is important as the current Day 6 – 14 forecasts and the week-old week 3 – 4 forecast overlap to some extent.
For reference purposes here is the precipitation information for the prior seven days.
Now let’s look at the forecasts. Because temperature is so important right now re this drought I have switched over to the same format we use on Mondays. When we publish Thursday night, the Week 3 – 4 forecast is a week old but in then updates on Friday and we update the discussion accordingly.
First Temperature
And then Precipitation
The Week 3 – 4 forecast is always updated the day after we publish our drought and agriculture report so it is our practice to update that report on Fridays to reflect the updated Week 3 – 4 report. We have not done that update.
Here is another useful graphic from my weekly report which also updates automatically.
I was not going to show this graphic this week but it shows the inverted trough.
The below is of interest.
4. U.S. Crop Information
Below are more details and there is more information this week as the planting season advances.
This summarizes the situation which is not very much different than the report last week. In some cases there is slight improvement and this is best seen in the detailed tables below. It is getting to be difficult preparing this table separate from the information above and below. The reason for that is that in general there are at this point in time three parameters reported:
1. percent planted
2. percent that has developed to a key point
3. crop condition
Plus there are two reference points: last year and the five year average. So it is harder to assess the six measurements and arrive at a single conclusion for a crop but I have taken my best shot at it. For those with a more serious interest I suggest you review the tables below and the text summary above which is what I have done to populated this table which has not changed since last week.
Worse than last year and or 5-Yr average | Better than last year or 5-Yr average | In line with recent conditions for this time of year or 5 – Yr Average |
Winter Wheat (low yields)*, Cotton, Sorghum, Pasture and Range Conditions* | Corn, Barley, Oats, Soybeans, Spring Wheat, | Rice, Peanuts, Sunflowers (no recent reports for sunflowers), |
* These two situations are not as bad now as they were as more states enter the picture.
The information in the table below is summarized in the above discussion but in the table below, it is broken down by State.
5. International Crop and Weather Related Information
Sometimes a map is useful.
I am now routinely including the precipitation report for Mexico since storms do not respect borders.
Here is the four-month result of these dry weeks.
6. Prior Month and when available the Current Month-to date Weather (excluding prior week)
Here is the recent history shown in this report as the month of August month to date average anomalies.
First precipitation
And then temperature:
You can generate a wide variety of different graphics here.
7. Science Theme When we Have One.
No Science Theme this week.
8. Additional Reference Information
A more complete description of
Sequence of drought occurrence and impacts for commonly accepted drought types. All droughts originate from a deficiency of precipitation or meteorological drought but other types of drought and impacts cascade from this deficiency. (Source: NDMC)
Source: National Drought Mitigation Center, University of Nebraska-Lincoln, U