October 4, 2018 Drought and Agriculture Report – Looking Better for New Year

Written by Sig Silber

Updated at 3:15 PM EDT October 5, 2018 to reflect the updated Week 3 – 4 Forecast.

Water Year 2018 was not good. Water Year 2019 which started on October 1 is already looking a bit better and many believe it will be a lot better except for areas normally dry due to El Nino which typically are the Northwest and perhaps the Midwest. Tonight we report on the past week. It is too soon to predict the full implications for Water Year 2019 but we had a week with slight improvement and things are looking up. Read on for the details.

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Information sources: Although not limited to the following, most of the material in this report comes from:

This explains what a Water Year is. It is different than a calendar year. I am not positive why it is done the way  it is done but my guess is that the definition of a Water Year includes four seasons rather than dividing the winter between two years and ends after the last release of water from reservoirs for agriculture but again I am not sure that is the reason but it is both my hunch and also a reason why I think it makes sense. At any rate it is the system that is used.

This report is now organized as follows:

1. Present Drought Conditions
2. Last Week’s Weather
3. 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
4. U.S. Crop Information
5. International Crop Information and related weather
6. Prior month’s weather and month-to-date weather excluding the prior week when I have that information. Drought is based on cumulative deficits.
7. A science theme if we have one.
8. Reference Information. (This includes a lot of information on reservoirs that we are not focusing on this week)

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 which covers the West may be useful also.

Now we show the week to week change information by region. The yellow is where the drought has been upgraded. The green is where the level of drought has been downgraded.

General Improvement especially the Dakotas.

Mixed

Fairly Mixed

Improvement

Some Deterioration

Improvement

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. When you read these graphics remember that the older graphics are not the drought conditions that existed then but the change from then until now. 

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

Multiple cold fronts, associated with an amplified upper-level trough, resulted in heavy rainfall across the eastern third of the continental U.S. during the final week of September. A widespread area of 2 to 4 inches, locally to 10 inches, was observed from the Tennessee Valley northeast to southern New England. A strong subtropical ridge maintained below normal precipitation and above normal temperatures (6 to 8 degrees F) across the Coastal Plain of Georgia south to the Atlantic coastal areas of Florida during the past week. A pair of strong surface highs shifted south from Canada into the north-central U.S. where below-normal temperatures were observed at the end of September through the beginning of October. Hurricane Rosa, in the East Pacific, turned northeast and made landfall as a tropical depression in the northern Baja Peninsula at the beginning of October. Heavy rainfall associated with Rosa spread northward from northwestern Mexico and triggered flash flooding across southern Arizona during October 1-2.

Northeast

Although widespread rainfall occurred across the mid-Atlantic and New England, the heaviest amounts (2-6 inches) mostly fell across the drought-free areas. The northern extent of rainfall amounts exceeding 2 inches resulted in some reduction of D0-D2 drought across north-central New York, southwestern Vermont, and coastal Maine. The eastern extent of the heavy rain also erased D0 across eastern Long Island, southern Rhode Island, and southern Massachusetts, but some D0 was left in southern Cape Cod, Nantucket Island, and Martha’s Vineyard as totals were lower (less than 1.5 inches) and short-term shortages remained. In addition, since weekly precipitation was lighter (less than an inch), 60-day precipitation deficits increased to more than 2 inches, and USGS 7-day stream flows were still below normal (10-24th percentile), D0 was expanded across north-central Maine.

Southeast

Much of northern Alabama received heavy rainfall (2 to 6 inches), resulting in a 1 to 2 category improvement. Rainfall amounts, in excess of 4 inches, justified a 2-category improvement (D1 to nothing) in northeastern sections of the state. Short-term abnormal dryness and moderate drought continued to increase in coverage across parts of Georgia and adjacent areas of South Carolina based on 30-day precipitation deficits of 2 to 4 inches and a near-record warm September (temperatures averaged 4 to 8 degrees F above normal across Georgia and South Carolina). The lack of rainfall and much above-normal temperatures maintained high evapotranspiration rates, and CPC soil moisture ranked in the lowest 30th percentile across southeast Georgia. Despite 6-month precipitation surpluses, D0 was introduced to extreme northeast Florida and along the Space Coast of Florida where short-term (60-90 days) precipitation deficits continue to increase and CPC soil moisture ranked in the lowest 20th percentile. A sharp cutoff existed between record-breaking rainfall in North Carolina and northeastern South Carolina from Hurricane Florence and the expanding D0 and D1 areas in southern South Carolina and Georgia.

South

Showers and thunderstorms were numerous along the western and central Gulf Coasts and across most of Louisiana, Mississippi, and central Tennessee where 2-4 inches of rain, locally to 8 inches, fell. Lighter amounts (1-2 inches) were recorded from east-central New Mexico eastward into southwestern Oklahoma, across northeastern Texas, central Arkansas, and western Tennessee. Little or no rain was reported in southwestern and central Texas, the Texas and Oklahoma Panhandles, northern and eastern Oklahoma, northwestern and southeastern Arkansas, and northwestern Mississippi. In Texas, after a very wet September (preliminary stats indicated Sep’18 was the second or third wettest month on record statewide), a reassessment using station-based precipitation amounts (CoCoRAHs) and radar-based precipitation estimates (AHPS), along with reported impacts, indicated better (wetter) conditions in central and eastern Texas, and worse (drier) conditions in the far southwest and Panhandle areas. Accordingly, improvements were made in central and eastern Texas, with deteriorations in far southwestern and Panhandle areas. Southwestern Oklahoma saw some improvement with the 1-2 inches of rain, but northeastern sections were degraded where 30-day deficits were found (similar to the Midwest summary for Missouri). Additional improvements were made in Louisiana, northeastern Mississippi, and south-central Tennessee, although the D1 near the TN-MS-AL borders remained and expanded slightly northward as reflected in the 60-day deficiencies. Most 7-day averaged USGS stream flows have recovered with the recent rains and are at normal to above-normal flows. Likewise, Sep. 30 USDA/NASS pasture and range lands have recovered in Texas and Oklahoma, with only 19% and 15% rated poor or very poor while 47% and 50% were rated good or very good, respectively. Similarly, soil moistures have improved in both states, with a continued decline in the categories of short to very short topsoil (17 and 21%) and subsoil (30 and 26%) moistures using raw statewide proportions.

Midwest

A swath of moderate to heavy rain (1 to 3.5 inches) resulted in a decrease in D0 and D1 across lower Michigan during a favorable time of year for soil moisture recharge as temperatures and evaporation decrease. D0 reduction was also warranted across northeastern Minnesota as recent rains produced 30-day surpluses and increased USGS stream flows (to normal or above-normal). Excessively wet conditions continue to plague northern Iowa and southern Wisconsin where rainfall amounts have exceeded 16 inches during the past 60 days. To the south of this wet region, an area of varying drought intensity continued across parts of Missouri, adjacent eastern Kansas, northeast Oklahoma, and southeastern Iowa. Although major improvements were made in this area due to heavy Midwest rains during late August and early September, D0 and D1 was increased in parts of southwest and east-central Missouri, and D0 returned to western Illinois and southeastern Kansas where 30-day precipitation deficits of 1.5-3 inches occurred. CPC soil moisture ranked in the lowest 10th percentile, and 6-month precipitation deficits exceeded 12 inches near the Kansas City, MO area. According to the Sep. 30 USDA/NASS statewide soil moisture and pasture conditions, Missouri remained a drought outlier as compared to surrounding wetter states as 39% and 53% of topsoil and subsoil moisture, respectively, remained short or very short, while 38% of pastures were rated poor or very poor.

High Plains

Light precipitation (0.5-1 inch) and 7-day temperatures averaging 5 to 10 degF below normal was enough to provide some improvements to the drought across the Dakotas as autumn is an ideal time of year for soil moisture recharge due to the lack of evaporation and minimal plant growth. Based upon a combination of various tools, the cool, wet weather warranted improvement in northwestern and southwestern ND and northeastern SD (D2 to D1), central SD (D1 to D0), and east-central and south-central ND, north-central and southwestern SD, and northeastern WY (D0 to nothing). Elsewhere, the light precipitation and subnormal temperatures were enough to keep conditions from deteriorating, but not wet enough for any improvement. Although it has been dry for the past 60-days in western Nebraska and northwestern Kansas, the cool weather delayed the introduction of D0 for now, but rain will be needed soon to prevent deterioration. In addition, as explained in the Midwest and South summaries, D0 was expanded into southeastern Kansas with respect to the large Midwestern drought area as 30-day deficits had accumulated there.

West

Remnant moisture and showers from former Hurricane Rosa in the East Pacific began to spread north into the desert Southwest by the end the valid period (12Z Oct. 2). South-central Arizona received 1-3 inches of rainfall, locally to 6 inches, which resulted in a 1 to 2 category improvement and included reports of flash flooding and a dam failure in western Pima County. Since more heavy rainfall with the remnants of Rosa occurred after 12Z Tuesday, additional improvements are anticipated across the Southwest next week. Onshore flow with a Pacific storm brought 0.5 to 2 inches of rainfall to coastal Washington and northwest Oregon where slight improvements were made as USGS 7-day stream flows rose to near-normal levels. Additionally, slight improvements were made in extreme east-central New Mexico due to changes in neighboring west Texas and recent rains (see South summary). However, further expansion of D3 was made in west-central Oregon (Deschutes, Crook, and Jefferson Counties) due to numerous months through September (out to 18-months) where the Standardized Precipitation Evapotranspiration Index (SPEI) was less than -1.5, along with corresponding drought impact reports that included surface water tributaries used for stock watering that dried up by early August, hay crops were reduced 50%, and remaining forage was of poor quality. Elsewhere, drought coverage and intensity remained unchanged throughout the remainder of the West.

Alaska, Hawaii, and Puerto Rico

In Hawaii, dryness and drought was limited to two small leeward areas on Maui and the Big Island. During Sep. 26-29, showers brought beneficial moisture to western Maui, dropping 3.23 inches on Lahainaluna (near the D0-D1 area) while 0.5-4 inches fell on other leeward locations of Maui. No changes were made this week in west Maui as assessments of ground conditions will not be ready until next week. Elsewhere, lighter showers (less than 1 inch) fell on the western Big Island, but it was not enough to make any improvements there. Moderate to heavy showers also fell on the remaining islands, assuring that no dryness will develop anytime soon.

In Puerto Rico, widespread, moderate to heavy showers (1-4 inches) fell across much of the island, allowing for some trimming of the northern and eastern D0 border in central sections of Puerto Rico. USGS 7-day averaged stream flows were all in the normal percentiles, with a few in the above-normal flows.

In the southeastern Alaskan Panhandle, the areas of D0 was expanded westward to near Yakutat in response to a below normal 2017-18 Water Year (WY; Oct. 1 – Sep. 30). Yakutat received 116.39 inches of precipitation, but that was only 75% of normal. Farther to the southeast, Haines recorded its driest WY with 30.14 inches, or 63% of normal, as did Petersburg (65.89”; 67%) and Klawock (54.53”; 60%). Skagway, Ketchikan, Sitka, and Snettisham Power Plant all had a near-record dry WY. 7-day averaged USGS stream flows are also in the lower tenth percentiles (much below to record low) which will greatly impact hydroelectric power plants if the wet season (autumn and winter) fails to ramp up soon.

Looking Ahead

During the next 5 days (October 4-8), a highly amplified upper-level pattern is likely to become established across the middle latitudes of the North Pacific and North America. A highly amplified upper-level trough are forecast to result in widespread above-normal precipitation throughout the Great Basin and north-central Rockies. The first major snowfall of the season is likely to blanket the Rocky Mountains with the higher elevations forecast to receive more than a foot. Accumulating snow, with locally high amounts, is probable for parts of the northern and central high Plains. As the upper-level trough amplifies over the West, maximum temperatures are forecast to average as much as 20 to 30 degrees F below normal across the north-central Rockies and adjacent high Plains on Oct 7 and 8. Multiple waves of low pressure are likely to emerge from the upper-level trough over the western U.S. and bring widespread heavy to excessive rainfall (3 to 7 inches, locally more) from the southern Great Plains northeast to the upper Mississippi Valley. The strong ridge aloft is likely to result in little to no rainfall along with much above-normal temperatures across the increasingly dry areas of Georgia.

For the CPC 6-10 day extended range outlook (October 9-13), indicates that the high amplitude pattern is likely to persist, resulting in a high confidence forecast with very high odds (above 80 percent)of below normal temperatures forecast for the northern Great Plains, northern/central Rockies, and Great Basin. Very high odds (above 80 percent) of above normal temperatures are forecast across the eastern third of the continental U.S. (CONUS). Above-normal precipitation is favored for much of the CONUS with the highest odds across the north-central Rockies, Great Plains, and middle to upper Mississippi Valley. Above-normal temperatures are likely throughout Alaska except for the Alaska Panhandle. Enhanced odds for above-normal precipitation are forecast for the Aleutians and mainland Alaska, while below-normal precipitation is favored to continue across the Alaska Panhandle.

Wildfires are happening.

The below are the forecasts by month for wildfires. Notice the area of risk is shrinking.  

Additional information can be found here.

And we do not want to ignore floods.

Reservoirs and Stream Flow (We expect this graphic to be updated very soon)

Let us look at California

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.

The darker areas would appear to have a big problem with pronounced drought and high levels of atmospheric demand for moisture from the ground and wind also appears to be an issue. Right now, the Southwest still has the largest problem.

Pan evaporation is another way to look at the evaporation. (It was not updated for the past two weeks so we are not showing the graphic this week.

Soil Moisture is a very important part of understanding drought. I uploaded the graphics in pairs this week (which is easier for me and we will see if they are still able to be read. You can click on them and the pair will enlarge.

Surface	Subsurface
The numbers in parentheses show the changes by state. Re the situation with surplus water,  the number of states with Topsoil (near surface) surpluses has increased by 2 from last week and the number of states with Subsoil (subsurface) surpluses has increased  by 1. It is not always easy to know how to relate to a moisture surplus. Is it a positive moisture reserve or is it too wet to work the ground?
Re those states with deficiencies, The number of states with Topsoil (near-surface) deficiencies has decreased by 3 from last week and the number of states with Subsoil (deeper) deficiencies has decreased by 2.

3. Current Forecast for Precipitation.

First we show the Month of October Forecast Issued on September 30 and then the Seasonal Forecast through December which was issued on September 20 with the full Seasonal Outlook. 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.

And here is the longer seasonal drought forecast.

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 September 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 September 21). This is important as the current Day 6 – 14 forecasts and the week-old week 3 – 4 forecast overlap to some extent.

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 it then updates on Friday and we then update the discussion accordingly which we have just done.

First Temperature

This shows magnitude rather than probability of  being higher or lower than Normal and shows the middle day of the five day period.	Cool anomaly is shifting slowly east. This helps with the Western Drought.		↑ ←  The Week 3 – 4 forecast was updated on Friday October 5. As expected, for that two-week period it is not the best news for the West.

The five day QPF is shown above. The units are different than the other maps i.e. in units of precipitation (inches) not probabilities of exceeding or being less than climatology.	The pattern is moving west to east. It is favorable for the Southwest Drought, and the easing Southern Plains Drought but not for the Northwest Drought.		↑ ←  The current Week 3 – 4 forecast was updated on Friday October 5 As expected, for that two week period it is not the best news for the Northwest. .

Here is another useful graphic from my weekly report which also updates automatically.

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.

** Close to completion for this years crop  and 2018 planting has begun or soon will

5. International Crop and Weather Related Information

Sometimes a map is useful. (It was not updated this week)

I am now routinely including the precipitation report for Mexico since storms do not respect borders.

Here is the six-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 September month to date average anomalies. Source

First Precipitation

Current Week

For reference purposes here is the precipitation information for the prior seven days.

Then we show month to date data. 

And then temperature:

You can generate a wide variety of different graphics here.

International Report for August.  We published that last week and one can refer to that information in that article which can be accessed here.

7. Science Theme When we Have One.

No Science Theme this week.

8. Additional Reference Information

Reservoir Status

We update these graphics when we receive new ones. They do not auto-update. They tend to change slowly.

This article provides a little background on the problem.

We have added more rivers to the discussion. Above we have reservoirs and they are of course connected by rivers. Both are important and provide insight.

Here are the similar graphics for some other reservoirs.

Below is 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