Seasonal Drought Outlook Archives

NOAA Updates its Seasonal Outlook on December 19, 2024 – Emerging Weak, Short La Nina Conditions – Posted on December 20, 2024

By Sig Silber December 20, 2024weatherNo Comments

On the third Thursday of the month right on schedule NOAA issued their updated Seasonal Outlook which I describe as their Four-Season Outlook because it extends a bit more than one year into the future. The information released also included the Mid-Month Outlook for the following month plus the weather and drought outlook for the next three months. I present the information issued by NOAA and try to add context to it. It is quite a challenge for NOAA to address the subsequent month, the subsequent three-month period as well as the twelve successive three-month periods for a year or a bit more.

With respect to the long-term part of the Outlook which I call the Four-Season Outlook, the timing of the transition from Neutral to LaNina has been challenging to predict. But there is more confidence in the situation for the moment. We are still in ENSO Neutral. La Nina is the likely scenario very soon, but the strength of the La Nina may be fairly weak. The transition from ENSO Neutral to La Nina is complicated as is the transition from La Nino back to ENSO Neutral. We may have both of these transitions in the three-month period January through March. So even if we have La Nina conditions for two or three months this period of time will probably not be recorded as a La Nina event because of the short duration. Every ten years the definition of climate normals are changed (it may be every five years for oceans) and some ENSO events are canceled and others are promoted to El Nino or La Nina status. This applies to the ONI status only as they do not reexamine the connection with the atmosphere. The warming of the oceans may very well make our definition of the states of ENSO incorrect. NOAA is looking at that.

From the NOAA discussion:

“El Niño Southern Oscillation (ENSO)-neutral conditions are present, as equatorial sea surface temperatures (SSTs) are near-to-below average in the central and eastern Pacific Ocean. During the last four weeks, mostly negative SST anomaly changes were evident across the equatorial Pacific Ocean. As such, a La Niña Watch is in effect, with La Niña conditions most likely to emerge in November 2024 – January 2025 (NDJ) (59% chance) and is expected to persist through February-April (FMA) 2025. In fact, the latest weekly Nino 3.4 SST departure was -0.6 degrees Celsius, which technically crosses the La Niña threshold. However, chances of a strong La Niña are exceedingly small, with a near zero percent chance of occurrence through the Winter. ENSO-neutral conditions are favored to re-emerge by the March-May (MAM) 2025 season.”

I personally would not have total confidence in this outlook given the uncertainty about there actually being a La Nina and its strength and duration if it does happen. The number of El Nino and La Nina events since 1950 is a fairly small number. When you further segment them by strength (LINK) you end up with a very small number of events in each category (El Nino v La Nina and three or four categories of strength within each of perhaps 7 subcategories. This makes both statistical methods and dynamical models have a large error range. We are pretty confident now that we will have either a weak La Nina or Neutral with a La Nina bias meaning it will be in the Neutral Range but closer to a La Nina than an El Nino. This suggests that there is value in this forecast. The maps show the level of confidence that NOAA (really the NOAA Climate Prediction Center) has for the outlook shown when they show a part of the U.S. or Alaska differing from normal.

Let’s Take a Look at the (mid-month) Outlook for January.

It will be updated on the last day of November.

Then we look at a graphic that shows both the next month and the next three months.

The top row is what is now called the Mid-Month Outlook for next month which will be updated at the end of this month. There is a temperature map and a precipitation map. The second row is a three-month outlook that includes next month. I think the outlook maps are self-explanatory. What is important to remember is that they show deviations from the current definition of normal which is the period 1991 through 2020. So this is not a forecast of the absolute value of temperature or precipitation but the change from what is defined as normal or to use the technical term “climatology”.

Notice that the Outlook for next month and the three-month Outlook are fairly similar except for temperatures in the Northwest and Alaska. This tells us that February and March will be substantially the same as January for most of CONUS. Part of the explanation for this is that NOAA expects La Nina to impact all three months.

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The full NOAA Seasonal Outlook extends through January/February/March of 2026 (yes that is more than a year out). All of these maps are in the body of the article. Large maps are provided for January and the three-month period January/February/March. Small maps are provided beyond that through January/February/March of 2026 with a link to get larger versions of these maps. NOAA provides a discussion to support the maps. It is included in the body of this article.

In some cases, one will need to click on “read more” to read the full article. For those on my email list where I have sent the url of the article, that will not be necessary.

NOAA Updates their Mid-Month Forecast for December 2024 on November 30, 2024 – Major Changes. – Posted on December 2, 2024

By Sig Silber December 2, 2024weatherNo Comments

At the end of every month, NOAA updates its Outlook for the following month which in this case is December of 2024. We are reporting on that tonight. In this article, I refer to December 2024 as “The New Month”.

There have been significant changes in the Outlook for the new month and these are addressed in the NOAA Discussion so it is well worth reading. We provided the prior Mid-Month Outlook for the new month for comparison. It is easy to see the substantial changes in the weather outlook by comparing the Mid-Month and Updated Maps. My comments are in a box.

The article includes the Drought Outlook for the new month. NOAA also adjusted the previously issued three-month Drought Outlook to reflect the changes in the new month’s Drought Outlook. We also provide the Week 2/3 Tropical Outlook for the World. The Tropical Outlet includes both direct and indirect potential impacts to the Southern Tier of CONUS. We also include a whole set of forecasts for parts of the new month. These are both useful and provide a crosscheck on the validity of the new month’s Outlook. The whole should be equal to the sum of its parts.

The best way to understand the updated outlook for the new month is to view the maps and read the NOAA discussion. I have highlighted the key statements in the NOAA Discussion.

I am going to start with graphics that show the updated Outlook for the new month and the earlier Mid-Month Outlook for the new month. This is followed by a graphic that shows both the Updated Outlook for the new month and the previously issued three-month outlook for the three-month period that includes the new month. So you get the full picture in three graphics.

Here is the updated Outlook for December 2024.

For Comparison Purposes, Here is the earlier Mid-Month Outlook for November

It is important to remember that the maps show deviations from the current definition of normal which is the period 1991 through 2020. So this is not a forecast of the absolute value of temperature or precipitation but the change from what is defined as normal or to use the technical term climatology.

It is a substantial change from what was issued on November 21, 2024. Remember, it is the first set of maps that are the current outlook for December which is the new month. One expects some changes 10 days later. However, the changes to the updated new month Outlook are very significant. This then gives us some reason to question the (November 21, 2024) three-month NDJ temperature and precipitation Outlooks which are shown in the following graphic.

NOAA provided a combination of the Updated Outlook for the New Month and the Three-Month Outlook.

The top pair of maps are again the Updated Outlook for the new month. There is a temperature map and a precipitation map. The bottom row shows the three-month outlooks which includes the new month. I think the outlook maps are self-explanatory.

To the extent that one can rely on a forecast, we would conclude that January and February will be very different than December. You can subtract December from the three-month Outlook and divide by two to get a combined January/February Outlook.

However given the major change in the new Outlook outlook from what was issued on November 21, 2024, we might not trust the three-month Outlook issued on November 21, 2024. Something to think about. But the major factor is the projected slower onset of La Nina. Thus this change may be consistent with the pattern the NOAA has been predicting although they have been playing catch-up.

I am still not convinced that there will be a La Nina Winter. Thus I am somewhat skeptical about the NOAA Outlooks.

Some readers may need to click “Read More” to read the rest of the article. Some will feel that they have enough information. But there is a lot more information in the rest of this article.

NOAA Updates its Seasonal Outlook on September 19, 2024 – Similar to the Outlook Issued last Month but the potential La Nina is Downgraded – Posted on September 20, 2024

By Sig Silber September 20, 2024weatherNo Comments

With respect to the long-term part of the Outlook which I call the Four-Season Outlook, the timing of the transition from Neutral to LaNina is challenging to predict. We are now in ENSO Neutral. La Nina is the likely scenario soon, but the strength of the La Nina may be fairly weak..

From the NOAA discussion:

“The most recent International Research Institute (IRI) for Climate and Society plume forecast of the Niño-3.4 SST index predicts a weak and a short duration La Niña, as indicated by the Niño-3.4 index values less than -0.5°C. This month, the latest North American Multi-Model Ensemble (NMME) guidance was relied upon, which predicts La Niña to emerge in the next couple of months and continue through the Northern Hemisphere winter. The continuation of negative subsurface temperatures and enhanced low-level easterly wind anomalies supports the formation of a weak La Nina. In summary, La Niña is favored to emerge in SON (71% chance) and is expected to persist through JFM 2025.”

“However, chances of a moderate to strong La Niña are currently less than 50% through the Fall and Winter. ENSO-neutral conditions are favored to re-emerge by the February-April (FMA) 2025 season.”

I personally would not have total confidence in this outlook given the uncertainty about there actually being a La Nina and its strength if it does happen. I do not have the JAMSTEC outlook yet but for sure they will lean towards a weak La Nina with Modoki characteristics. I do not have a lot of confidence that NOAA knows how to deal with a La Nina Modoki. But they may have it exactly correct.

Let’s Take a Look at the (mid-month) Outlook for October

It will be updated on the last day of August.

Then we look at a graphic that shows both the next month and the next three months.

The top row is what is now called the Mid-Month Outlook for next month which will be updated at the end of this month. There is a temperature map and a precipitation map. The second row is a three-month outlook that includes next month. I think the outlook maps are self-explanatory. What is important to remember is that they show deviations from the current definition of normal which is the period 1991 through 2020. So this is not a forecast of the absolute value of temperature or precipitation but the change from what is defined as normal or to use the technical term “climatology”.

Notice that the Outlook for next month and the three-month Outlook are dissimilar. This tells us that November and December will be substantially different than October.

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The full NOAA Seasonal Outlook extends through October/November/December of 2025 (yes that is more than a year out). All of these maps are in the body of the article. Large maps are provided for October and the three-month period October/November/December Small maps are provided beyond that through October/November/December of 2025 with a link to get larger versions of these maps.

NOAA provides a discussion to support the maps. It is included in the body of this article. In some cases, one will need to click on “read more” to read the full article. For those on my email list where I have sent the url of the article, that will not be necessary.

NOAA Updates its Seasonal Outlook on August 15, 2024 – Similar to the Outlook Issued last Month but Shifted Out a Month or Two – Posted on August 16, 2024

By Sig Silber August 16, 2024weatherNo Comments

From the NOAA discussion:

“The major climate driver during the winter and early spring 2024-2025 is expected to be La Niña and the outlooks from DJF 2024-2025 through FMA 2025 reflect this with above-normal temperatures favored for the Southern Great Plains, Lower Mississippi Valley, and Southeast.”

“Later in the fall and into the 2024-2025 winter, the three-month precipitation outlooks are based largely on La Niña composites. The spatial coverage for below-normal precipitation probabilities exceeding 50 percent is largest during DJF and JFM across southeastern New Mexico, Texas, and parts of the Southeast where the dry signal is the strongest and occurs most frequently according to La Niña composites. Based on the same reasoning, above-normal precipitation probabilities are at their largest during DJF for the Pacific Northwest. Typically during La Niña, a tight gradient of dry to wet from the Gulf Coast to the Tennessee and Ohio Valleys becomes established during the winter and early spring.”

Let’s Take a Look at the (mid-month) Outlook for September

It will be updated on the last day of August.

Then we look at a graphic that shows both the next month and the next three months.

The top row is what is now called the Mid-Month Outlook for next month which will be updated at the end of this month. There is a temperature map and a precipitation map. The second row is a three-month outlook that includes next month. I think the outlook maps are self-explanatory. What is important to remember is that they show deviations from the current definition of normal which is the period 1991 through 2020. So this is not a forecast of the absolute value of temperature or precipitation but the change from what is defined as normal or to use the technical term “climatology”.

Notice that the Outlook for next month and the three-month Outlook are fairly similar. This tells us that October and November will be fairly similar to September.

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The full NOAA Seasonal Outlook extends through September/October/November of 2025 (yes that is more than a year out). All of these maps are in the body of the article. Large maps are provided for September and the three-month period September/October/November. Small maps are provided beyond that through September/October/November of 2025 with a link to get larger versions of these maps.

NOAA provides a discussion to support the maps. It is included in the body of this article. In some cases, one will need to click on “read more” to read the full article. For those on my email list where I have sent the url of the article, that will not be necessary.

NOAA Updates its Seasonal Outlook on March 21, 2024 – Hints of a Possibly Very Strong La Nina Coming: Published March 22, 2024

By Sig Silber March 22, 2024weatherNo Comments

Updated at 11 p.m. EDT March 22, 2024. Three additional graphics were added plus some additional commentary.

With respect to the long-term part of the Outlook which I call the Four-Season Outlook, there is a fairly rapid transition from El Nino to ENSO Neutral to LaNina. So getting the timing right is very challenging. The potential for a very strong La Nina is discussed but it is not the likely scenario at this point in time. But it seems that the longer-term outlook now factors in both drier conditions in certain parts of the U.S. and wetter conditions on the East Coast and Southeast this summer.

First, Let’s Take a Look at the (mid-month) Outlook for April.

It will be updated on the last day of March

The top row is what is now called the Mid-Month Outlook for next month which will be updated at the end of this month. There is a temperature map and a precipitation map. The second row is a three-month outlook that includes next month. I think the outlook maps are self-explanatory. What is important to remember is that they show deviations from the current definition of normal which is the period 1991 through 2020. So this is not a forecast of the absolute value of temperature or precipitation but the change from what is defined as normal or to use the technical term “climatology”.

Notice that the Outlook for next month and the three-month Outlook are somewhat different, especially with regard to temperature. This tells us that May and June will be different than April to some extent.

The full NOAA Seasonal Outlook extends through April/May/June of 2025 (yes that is more than a year out). All of these maps are in the body of the article. Large maps are provided for April and the three-month period Apr/May/June. Small maps are provided beyond that through Apr/May/June of 2025 with a link to get larger versions of these maps.

NOAA provides an excellent discussion to support the maps. It is included in the body of this article. In some cases, one will need to click on “read more” to read the full article. For those on my email list where I have sent the url of the article, that will not be necessary.

NOAA Updates its Seasonal Outlook on February 15, 2024 – MJO, Neg AO, Possible SSW Make the March Outlook Quite Interesting

By Sig Silber February 16, 2024weatherNo Comments

First, Let’s Take a Look at the (mid-month) Outlook for March.

It will be updated on the last day of February

The top row is what is now called the Mid-Month Outlook for next month which will be updated at the end of this month. There is a temperature map and a precipitation map. The second row is a three-month outlook that includes next month. I think the outlook maps are self-explanatory. What is important to remember is that they show deviations from the current definition of normal which is the period 1991 through 2020. So this is not a forecast of the absolute value of temperature or precipitation but the change from what is defined as normal or to use the technical term “climatology”.

Notice that the Outlook for next month and the three-month Outlook are somewhat different. This tells us that April and May will be different than March to some extent.

The full NOAA Seasonal Outlook extends through March/April/May of 2025. All of these maps are in the body of the article. Large maps are provided for March and the three-month period Mar/Apr/May. Small maps are provided beyond that through May of 2025 with a link to get larger versions of these maps.

NOAA provides an excellent discussion to support the maps. It is included in the body of this article. In some cases, one will need to click on “read more” to read the full article. For those on my email list where I have sent the url of the article, that will not be necessary.

NOAA Updates its Seasonal Outlook October 19, 2023 – Reduction in Drought

By Sig Silber October 20, 2023weatherNo Comments

On the third Thursday of the month right on schedule NOAA issued their updated Seasonal Outlook which I describe as their Four-Season Outlook because it extends a bit more than one year into the future. The information released also included the Mid-Month Outlook for the following month plus the weather and drought outlook for the next three months. I present the information issued by NOAA and try to add context to it. It is quite a challenge for NOAA to address the subsequent month, the subsequent three-month period as well as the twelve successive three-month periods for a year or a bit more.

First, Let’s Take a Look at the (mid-month) Outlook for November. It will be updated on the last day of October.

Then I present a graphic that shows both the preliminary Outlook for November and the three-month outlook for NDJ 2023-2024. So you get the full picture in one graphic. For some, that may be all they are interested in. Others will be interested in the longer-term predictions and also the rationale supporting the predictions which is mostly provided by the NOAA discussion.

The top row is what is now called the Mid-Month Outlook for next month which will be updated at the end of this month. There is a temperature map and a precipitation map. The second row is a three-month outlook that includes next month. I think the outlook maps are self-explanatory. What is important to remember is that they show deviations from the current definition of normal which is the period 1991 through 2020. So this is not a forecast of the absolute value of temperature or precipitation but the change from what is defined as normal or to use the technical term “climatology”.

Notice that the outlook for next month and the three-month outlooks are somewhat different with respect to temperature and also to some extent precipitation. This tells us that December and January will be different than November to some extent.

The full NOAA Seasonal Outlook extends through November/December/January of 2025. All of these maps are in the body of the article. Large maps are there for November and the three-month period Nov/Dec/Jan. Small maps are provided beyond that through January of 2025 with a link to get larger versions of these maps.

NOAA provides an excellent discussion to support the maps.[Author’s Note: many other meteorological agencies see this El Nino being stronger than NOAA does so there is more than usual uncertainty relating to the more distant months.]

NOAA Updates its Seasonal Outlook September 22, 2023 – Some Changes from what was Issued Last Month.

By Sig Silber September 22, 2023weatherNo Comments

First, Let’s Take a Look at the (mid-month) Outlook for October. It will be updated on the last day of September.

Then I present a graphic that shows both the preliminary Outlook for October and the three-month outlook for OND 2023. So you get the full picture in one graphic. For some, that may be all they are interested in. Others will be interested in the longer-term predictions and also the rationale supporting the predictions which is mostly provided by the NOAA discussion.

Notice that the outlook for next month and the three-month outlooks are somewhat different with respect to temperature. This tells us that November and December will be different than October to some extent.

The full NOAA Seasonal Outlook extends through October/November/December of 2024. All of these maps are in the body of the article. Large maps are there for October and the three-month period Oct/Nov/Dec. Small maps are provided beyond that through December of next year with a link to get larger versions of these maps.

NOAA provides an excellent discussion to support the maps and the changes which starting in the Spring of 2024 are significantly different from what was issued a month ago. [Author’s Note: many other meteorological agencies see this El Nino lasting longer than NOAA does so there is more than usual uncertainty relating to the more distant months. It seems to me that NOAA was showing some of these as El Nino months last month but has changed them to ENSO Neutral months in what they issued on September 21, 2023.]

NOAA Updates their Seasonal Outlook – June 17, 2023

By Sig Silber June 17, 2023weatherNo Comments

On the third Thursday of the month right on schedule NOAA issued what I describe as their Four-Season Outlook. The information released also included the Mid-Month Outlook for the single month of July plus the weather and drought outlook for the next three months. I present the information issued by NOAA and try to add context to it. It is quite a challenge for NOAA to address the subsequent month, the subsequent three-month period as well as successive three-month periods for a year or a bit more. A seasonal drought outlook is also issued.

It is very useful to read the excellent discussion that NOAA issues with this Seasonal Outlook. The overall level of confidence in the Seasonal Outlook is addressed in the NOAA discussion. It is best to read the full discussion but here are some of the highlights:

Re ENSO:

“NOAA’s CPC forecast calls for more than a 90 percent chance of El Niño persisting through JFM 2024 with a 56 percent chance of a strong El Niño (> 1.5 degrees C) during NDJ 2023.”

For July:

“Above normal temperatures are favored from the Four Corners region, across the central and southern Great Plains, the Southeast, and the Northeast.”
“A weakened monsoon during July across eastern Arizona and New Mexico is predicted”
“a strong subtropical ridge, which would favor above-normal precipitation from the southern Great Plains northward and into the Mid-Atlantic”
“a storm track across the northern Great Plains and into the Ohio River valley”

For JAS 2023:

“The highest probabilities (more than 50 percent) of above-normal temperatures are forecast across parts of California, the Pacific Northwest, Great Basin, Southwest, Gulf Coast, and East.”
“elevated probabilities of below-normal precipitation for parts of the Southwest, Pacific Northwest, and Great Lakes, while above-normal precipitation is favored across much of the Great Plains, parts of the Middle to Lower Mississippi Valley, Northern Rockies, and Florida Peninsula.”

Beyond JAS 2023:

“Above-normal temperatures remain the most likely outcome throughout much of the U.S. from ASO to OND 2023.”
“Beginning in NDJ 2023-24 through JFM 2024, predicted El Niño conditions result in enhanced chances for above-normal temperatures across the northern tier of the CONUS”
“During the winter 2023-24, above-normal temperatures are favored across the East”
“Precipitation outlooks during the fall 2023 through the winter 2023-24 relied upon El Niño composites and the consolidation tool with an increased chance of above (below)-normal precipitation across the southern (northern) tier of the CONUS.”
“The largest probabilities (50 percent for above) are forecast across parts of the Southeast from NDJ 2023-24 through JFM 2024 based on a strong, reliable wet signal associated with El Niño.
“During the spring and summer 2023, the precipitation outlooks are based mostly on decadal trends.”

NOAA Updates their Seasonal Outlook – El Nino coming but not here yet – May 27, 2023

By Sig Silber May 27, 2023weatherNo Comments

Lightly edited at 5:54 p.m. EDT Saturday, May 27, 2023 mostly to compare the new to the prior Seasonal Outlook. They are very similar.

On the third Thursday of the month right on schedule NOAA issued what I describe as their Four-Season Outlook. The information released also included the Mid-Month Outlook for the single month of June plus the weather and drought outlook for the next three months. I present (apologies for the delay) the information issued and try to add context to it. It is quite a challenge for NOAA to address the subsequent month, the subsequent three-month period as well as successive three-month periods for a year or a bit more.

It is very useful to read the excellent discussion that NOAA issues with this Seasonal Outlook. In general, the overall level of confidence in the Seasonal Outlook is lower than usual for many reasons that are addressed in the NOAA discussion. It is best to read the full discussion but here are some of the highlights:

Equatorial SSTs are near-to-above average across most of the Pacific Ocean and atmospheric conditions reflect ENSO-neutral conditions [Editor’s Note: The Atmosphere has not yet responded to the warming in the Eastern Pacific which is marginally at El Nino levels].
At least a weak El Niño is likely given high levels of above-average oceanic heat content, but the range of possibilities include an 80 percent chance of at least a moderate El Niño and a 55 percent chance of a strong El Niño by the end of the year.
This likely warm start to June along with monthly dynamical and statistical tools support increased probabilities for above-normal temperatures from the Pacific Northwest east to the Northern Great Plains.
The NMME along with an increased potential for an early season TC [tropical cyclone] to emerge from the western Caribbean Sea favors above-normal precipitation [in June] for parts of the Southeast.
The JJA 2023 temperature outlook favors above-normal temperatures over the western CONUS, the Southwest, the Gulf States, along the eastern seaboard, and for much of the state of Alaska.
The JJA 2023 precipitation outlook depicts below-normal precipitation probabilities over the Pacific Northwest and parts of the Northern Rockies, the Southwest, and south coast of Alaska. NMME and C3S are in good agreement on below normal precipitation over the southwest and wet soil moisture over the Four Corners region may provide a sluggish start to the Monsoon this summer. Above normal precipitation probabilities are indicated over parts of the Middle and Lower Mississippi Valleys, the Ohio and Tennessee Valleys, the Southeast, and mid-Atlantic. Parts of the Central Plains tend to be anti-correlated with the monsoon region, and as such a weak tilt toward above normal precipitation is indicated.
Confidence decreases in September-November (SON) 2023 and following seasons as lead time increases and dynamical models become more uncertain, however, El Niño is expected to become more dominant in the forecast(s), and the pattern begins to reflect El Niño conditions during fall and winter seasons.
Decadal [Temperature] trends become the dominant player in spring and summer 2024, with below normal trends over the Pacific Northwest and above-normal trends over the Mid-Atlantic.