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.
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.
| Our regular Daily Weather article can be found HERE. In addition to the short-term forecast it also provides the 6 – 10 day, 8 – 14 day, and Week 3 – 4 Outlooks. That is not a full month but close to it. So it is helpful if one wants to understand how the full-month forecast is expected to vary through the month. The maps in the Daily Article are updated throughout the month. But I have many of those maps right here in this article. |
What we knew about December before NOAA issued their Updated Outlook for December. It should update in this article but if not, you can find the updated version at econcurrents.com daily.
Below is the current five-day cumulative forecast of precipitation (Updates can be found HERE) Unfortunately I do not have a five-day temperature forecast.
Now we look at Intermediate-Term “Outlook” maps for three time periods. Days 6 – 10, Days 8 – 14, and Weeks 3 and 4. An outlook differs from a forecast based on how NOAA uses these terms in that an “outlook” presents information as deviation from normal and the likelihood of these deviations.
Below are the links to obtain updates and additional information. They are particularly useful if you happen to be reading this article significantly later than when it was published. I always try to provide readers with the source of the information in my articles. These links may also be useful for those viewing this article on a cell phone or other small screen.
| Days 6 – 10 (shown in Row 1) | Days 8 – 14 (Shown in Row 2) | Weeks 3 and 4 (Shown in Row 3 but updates only on Fridays) |
| https://www.cpc.ncep.noaa. gov/products/predictions/610day/ | https://www.cpc.ncep .noaa.gov/products/predictions/814day/ | https://www.cpc.ncep.noaa.gov/products/predictions/WK34/ |
Showing the actual maps. They should now update automatically. The Week 3 – 4 Outlook only updates on Fridays. So below is what I call the Intermediate-term outlook. On Fridays, it extends out 28 Days. That declines day by day so on Thursday it only looks out 22 days until the next day when the Week 3 – 4 Outlook is updated and this extends the outlook by one additional week.
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So we had a 28-day outl00k in advance of NOAA issuing their updated outlook for December.
Here are larger versions of the December Temperature and Precipitation Outlook maps.
NOAA (Really the National Weather Service Climate Prediction Division CPC) Discussion. I have shown certain important points in bold type. My comments if any are in brackets [ ].
30-DAY OUTLOOK DISCUSSION FOR DECEMBER 2024
The updated temperature and precipitation outlooks for December 2024 are based on the latest dynamical models , WPC temperature and precipitation forecasts during the first week of the month, the CPC 6-10/8-14 day temperature and precipitation outlooks, and the week 3-4 outlook (valid December 14-27). El Niño Southern Oscillation (ENSO)-neutral conditions continue with a limited area of below-average sea surface temperature anomalies observed across the east-central Pacific. During late November, the Madden-Julian Oscillation (MJO) contributed to anomalous low-level easterly winds across the equatorial Central Pacific. These enhanced trade winds may lead to a transition towards La Niña. The GEFS and ECMWF models indicate that the MJO propagates eastward from the Maritime Continent to the West Pacific during early December. However, beyond that time, ensemble spread increases on the MJO amplitude. Due to uncertainty on how much influence the MJO or the transition to La Niña has on the mid-latitude circulation pattern, the updated temperature and precipitation outlooks relied mostly upon the dynamical model guidance at varying time scales throughout December.
Temperature
During early December, the GEFS and ECMWF ensemble means are in good agreement and remain consistent that a highly amplified 500-hPa pattern persists over North America. These ensemble mean solutions depict a ridge over the western contiguous U.S. (CONUS) with anomalous troughing centered near the East Coast. This amplified longwave pattern is likely to result in above-normal temperatures from the West Coast east to the Rockies with below-normal temperatures across the eastern third of the CONUS. By mid-December, the GEFS indicates a retrogression of the longwave pattern with the amplified ridge along the West Coast shifting west to the North Pacific. This would eventually lead to a pattern change downstream with a 500-hPa trough (ridge) over the western (eastern) CONUS. The updated temperature outlook added a lean towards below-normal temperatures across the Mid-Atlantic and Northeast based on the anomalous cold through early December. However, probabilities are limited due to the predicted longwave pattern change which would result in a warming trend during the latter half of the month. For the western CONUS, the likelihood of above-normal temperatures through mid-December and the lack of a cold signal among the week 3-4 tools support an increased chance of above-normal temperatures. The largest probabilities (exceeding 60 percent) are forecast for southern California and the Desert Southwest where the magnitude of the anomalous warmth is predicted to be the strongest early in the month. Elevated above-normal temperature probabilities extend east to the Central and Southern Great Plains since model guidance, especially for the 8-14 day period, has trended warmer. Equal chances (EC) for below, near, or above-normal temperatures are forecast across portions of the Northern Great Plains, Mississippi Valley, and Southeast where temperatures are expected to be variable throughout the month. Following a cold start to the month across Alaska, a rapid flip to above-normal temperatures is forecast around December 4 due to enhanced onshore flow. A two-category change (favored below to above-normal temperatures) from the initial release on November 21 was necessary for southeastern Alaska as increased chances for above-normal temperatures are forecast to continue through the month.
Precipitation
The highly amplified ridge over western North America is likely to result in a dry pattern for much of the lower 48 states through early December. A couple exceptions include areas downwind of the Great Lakes with heavy lake-effect snow and portions of Texas and the Lower Mississippi Valley as a southern stream shortwave trough tracks eastward. Above-normal precipitation is slightly favored for those areas which are forecast to have a wet start to the month. In addition, the week 3-4 outlook favors above-normal precipitation across eastern and southern Texas. Since the first week of the month is forecast to be mostly dry and there is no strong wet signal later in the month, the elevated below-normal precipitation probabilities for parts of the eastern CONUS are maintained from the outlook released on November 21. Drier-than-normal conditions through at least mid-December elevate below-normal precipitation probabilities across the Southwest, parts of the Great Basin, and California. Also, the week 3-4 outlook favors below-normal precipitation for southern California and the Desert Southwest. Although the first week of December is forecast to be on the drier side across the Northern Rockies and Northern Great Plains, the 8-14 day and week 3-4 outlook depict a wetter signal which leads to favoring above-normal precipitation across those areas. Despite a dry start to the month for the Central Great Plains, Middle Mississippi Valley, and Ohio Valley, a pattern change later in December towards a trough upstream could lead to an increase in precipitation. Therefore, EC are forecast for these areas. Enhanced onshore flow is forecast to develop across Alaska during the first week of December and tools throughout the month generally lean towards above-normal precipitation for much of the state.
With an updated Outlook for December, we now have adjusted Outlooks for the three-month period of Dec/Jan/Feb. But the only thing updated is the December part of the three-month weather outlook.
| Given the major change in the December Outlook, I am skeptical about the three-month Outlook issued by NOAA. |
Drought Outlook
Here is the newly issued Drought Outlook for the month.
| You can see where drought development or persistence is likely. The summary and detailed discussions that accompany this graphic can be accessed HERE, but the short version is shown below. |
Here is the short version of the drought summary
Latest Monthly Assessment – Since the November 2024 Monthly Drought Outlook released on October 31, 2024, drought has markedly improved across much of the Pacific Northwest, Great Plains, Mississippi Valley, and Great Lakes, due in large part to a very active pattern in early November. Conversely, drought conditions have continued to worsen and expand across portions of the Southwest, Rio Grande Valley, Northern High Plains, and the East Coast states.
Looking forward to December 2024, drought persistence is favored across the contiguous U.S. (CONUS), associated with a predominantly dry pattern favored through the middle of the month. In areas where warmer and drier than average conditions are favored in the southwestern and southeastern CONUS, and where dry soil moisture signals are most prevalent, some drought development is also favored. Conversely, wetter than average conditions are favored throughout the month of December across portions of the south-central and northwestern CONUS, favoring some potential drought improvement and removal. Toward the latter half of the month, however, uncertainty in the temperature and precipitation outlooks and tools increases. In addition, La Niña conditions have yet to develop at the start of December and only have a 57% chance of developing by the end of 2024. As such, La Niña is not likely to be a major driver of weather patterns throughout December.
In Hawaii, drought persistence is favored through the end of December, associated with above average temperatures and near average precipitation forecast through at least the middle of the month. Alaska, Puerto Rico, and the U.S. Virgin Islands are drought-free with wet antecedent conditions at the start of December, and favorable precipitation outlooks are forecast to keep them drought-free by the end of December.
We also have an updated Seasonal Drought Outlook (link).
| This three-month outlook forecast is a combination of the mid-month three-month drought forecast and the revised drought forecast for December. Since I have a low level of confidence in the NOAA Outlooks for January and February, I have a low level of confidence for this seasonal drought outlook. |
| To update this forecast (which updates on Tuesdays), click HERE |
It is useful to review the prior month.
Month-to-date Temperature as the current month evolves can be found at https://hprcc.unl.edu/products/maps/acis/MonthTDeptUS.png
Month-to-date Precipitation as the current month evolves can be found at https://hprcc.unl.edu/products/maps/acis/MonthPNormUS.png
| You see an interesting West to East pattern of warm and cool with respect to a normal November. It is the reverse of October. |
| You see large areas of more-than-normal precipitation. It is not a La Nina pattern nor should it be as we had ENSO Neutral in November. |
Current Fire Situation. The link is HERE.
| But they for sure have good-looking maps. I will try to provide more information on the use of this website in the future. Canada has the major wildfire problem right now. |
| I hope you found this article interesting and useful |
