NOAA Updates The Outlook For November 2020 – Not Much Change If You Believe It.

Written by Sig Silber

At the end of every month, NOAA issues an update to their Early Outlook for the following month which was issued as usual on the Third Thursday of October. Today, sixteen days later, NOAA has issued their Updated Outlook for November. Our visual consistency testing raises questions about the accuracy of the full-month forecast given the 6 – 10 Day and the 8 – 14 Day forecasts with respect to the Greater Northwest. This concern is mostly regarding temperature but it may apply to precipitation also for the Northwest and perhaps a larger area. We also have the new Drought Forecast for November.

Some housekeeping: On October 16, 2020, we published Part I of our analysis of the NOAA and JAMSTEC Three- to Four- Season Outlook and that can be accessed here. In that report, the November 2020 Early Outlook was issued. This article presents the NOAA update of their Early temperature and precipitation Outlook for November and the most recent Drought Forecast update for the month of November.

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Now, we will compare the NOAA Early Outlook for November 2020 with the newly issued update.

Early Outlook Temperature

Updated Temperature Forecast

Early Outlook Precipitation

Updated Precipitation Forecast

Here is the discussion released with the forecast.

30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2020

The updated November 2020 outlook is based on the November outlook released in mid-October adjusted using the current WPC outlooks for week 1 and CPC outlooks for the extended range and week 3-4, while considering current climate conditions, including an ongoing La Nina, and following the most recent subseasonal and monthly integrated dynamical model guidance. The influence of ongoing La Nina conditions is apparent in both the prior half-month lead November outlook and the updated November outlook, increasing the chances of above normal temperatures and below normal precipitation across much of the southern CONUS, while increasing the chances of below normal temperatures and above normal precipitation for parts of the northern CONUS.

The updated November temperature outlook has only small changes relative to the prior outlook, most notably increasing the area of likely above normal temperatures in the Pacific Northwest to include Oregon and southwestern Washington, while increasing the probabilities of above normal temperatures over parts of the Central Plains to be over 50 percent. Dynamical models predict an amplified 500-hPa ridge over the western CONUS and a 500-hPa trough over the eastern CONUS at the start of November, with the ridge expected to progress eastward while the trough lifts to the northeast during the first week of the month. This pattern increases the probabilities of above normal temperatures for much of the western CONUS in the monthly outlook, while decreasing probabilities over the southeastern CONUS. Above normal temperatures remain likely for almost the entire CONUS in the updated November outlook, with the exception of parts of the Northern Rockies extending to the Northern Plains, where equal chances of above, near and below normal temperatures are forecast. During the second week of November, a trough is predicted to amplify over the western CONUS, and the week 2 outlook calls for high probabilities of below normal temperatures over parts of the west that are consistent with areas showing equal chances in the November outlook. Probabilities of above normal temperatures were increased over parts of the Northeast, where the outlooks for week 2 and week 3-4 indicate greater chances of above normal temperatures. Small adjustments were made in the area of likely above normal temperatures in western and northern Alaska, consistent with current dynamical model forecasts.

The updated November precipitation outlook has a similar pattern to the prior outlook, predicting enhanced probabilities of below normal precipitation across a large area of the southern CONUS from the Southwest region across the Central and Southern Plains into the Southeast region from the southern Ohio Valley and Mid-Atlantic region to the Gulf Coast. The area of enhanced probabilities of above normal precipitation has expanded over the Pacific Northwest into Northern Plains, supported by dynamical model forecasts and precipitation outlooks for weeks 1 through 4. Chances of below normal precipitation have decreased and equal chances of below, near and above normal precipitation are predicted in the November update for parts of California, Arizona and Nevada, where the climatology is relatively dry and there is uncertainty in the precipitation outlook for early November and only weak probabilities of below normal precipitation are predicted in the week 3-4 outlook. Probabilities of below normal precipitation have increased for parts of the Southeast, where likely below normal precipitation is predicted for the week 2 and week 3-4 periods. An area of enhanced probabilities of above normal precipitation over Alaska shifted somewhat to be over northwestern Mainland Alaska and the North .Slope, consistent with current dynamical model forecasts for November.

Visual Consistency Testing.

It is useful to see how the full-month forecast fits with the set of partial-month forecasts that we have. These will continue to update in this article. It is important to remember that with the partial-month forecasts, we generally have about 25 days of the subsequent month to look at when we do this at the end of the month as we are doing now. It depends on what day of the week the month ends. So this month, which ended on a Saturday, we are missing a forecast that includes only three of the last three days of the month. So we are in excellent shape for the visual consistency testing this month.

First Temperature

The new monthly forecast is to the right. Does it appear to be reflective of the four parts of the month for which we have forecasts? →			↑ ← The Week 3 – 4 forecast was updated Friday, October 30 so we do not need to update the commentary when the Week 3 – 4 update is reissued on November 6. At this point, we have forecasts for 27 days of the 30 days in November and the fit looks not very good. We will take another look on Monday since the weekend forecasts for Days 6 – 10 and 8 -14 are computer-generated only but I went back and looked at Friday’s forecasts.

And Precipitation

The new monthly forecast is to the right. Does it appear to be reflective of the four parts of the month for which we have forecasts? →			↑ ←The Week 3 – 4 forecast was updated Friday, October 30 so we have no need to update the commentary when the Week 3 – 4 update is reissued on November 6. At this point, we have forecasts for 27 days of the 30 days in November and the fit looks not so great. We will take another look on Monday as the weekend 6 -10 day and 8 – 14 day forecasts are computer generated and often changed on the following Monday.

Sometimes it is useful to compare the three-month outlook to the forecast for the first of the three months. It shows how much the pattern changes over the three-month period.

One can mentally subtract the First-Month Outlook from the Three-month Outlook and create the Outlook for the last two months in the three-month period.

And with respect to drought, this was also issued on October 31, 2020

Latest Monthly Assessment – The Monthly Drought Outlook (MDO) for November 2020 is based on dynamical model guidance, official temperature and precipitation outlooks, climatology, recent precipitation observations, and considers the effects of La Niña. Drought is predicted to persist across much of the West, with some drought development possible in southern interior California. This potential development of drought in southern California is not only uncertain, but a corresponding delay in the rainy season can have significant impacts on (for example) the fisheries industry and the management of rangelands. In contrast, odds favor drought improvement/removal over the Pacific Northwest and Northern Rockies. Drought is likely to persist across most of the Great Plains, consistent with precipitation forecasts at time-scales out to a month in advance, and with November climatology. Some drought development is possible in central Texas. Very limited, small-scale improvements in current drought conditions are expected across the Midwest and Ohio Valley due to passing frontal systems. In the Northeast, recent precipitation is helping to ease abnormal dryness and drought, especially in eastern and southern portions of New England. There is currently no drought in the Southeast thanks to a very active Atlantic hurricane season and occasional stalled fronts, though some development is possible by the end of November in Georgia and South Carolina.

Drought removal is anticipated in northwestern Alaska, based on the updated 30-day precipitation outlook. In Hawaii, drought improvement and/or removal is expected, coincident with the onset of the traditional rainy season and the current La Niña. However, this is far from certain, as the most significant precipitation typically falls during the winter months, not in November. Puerto Rico is drought-free and is expected to remain free of drought through November.

Looking back on October to relate the forecast for November to the actuals in October

First October Temperature (30 out of 31 days).

And then October Precipitation (30 out of 31 days).

We then show the new forecast and the prior month actuals (less one day) side by side.

Conclusion

The purpose of this article was to present the updated Outlook for November 2020 and compare it with the Early Outlook. It is not to critique the updated Outlook for November based on our opinions but we point out possible inconsistencies if we find them and we have. We have assessed the extent to which the monthly outlook seems to fit with the other forecasts provided by NOAA. In reality, all forecasts are obsolete when issued as the situation changes day by day or six hours by six hours i.e. each new model run. In our other articles, we continually examine the current forecasts from NOAA including Day 1- 5, 6-10, 8-14, and Week 3 and 4. So we are continually looking at approximately 25 days into the future.

On November 12, 2020, IRI/CBC will issue their ENSO forecast and we will present that and critique it. What they present on November 12 is not likely to impact the forecasts for the next three months but may shed some light on the second half of Winter and Spring. It is an ongoing process and we attempt to provide our readers with the best current assessment of the next approximately 25 days (except when we cover the Four-Season Analysis or medium-frequency cycles such as ENSO in which cases we are looking further out than 25 days), so our analysis is pretty much ongoing. We also publish a “LIVE” Weather Article which updates in real-time to reflect NOAA Weather Headlines and for those interested provides detailed information down to current warnings in place. All of our reports including past versions of these reports can be located via the Directory/Archive which can be accessed here.