NOAA Updates The Outlook For March, 2021 – Surprisingly Little Change!

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 February. Today, just ten days later, NOAA has issued their Updated Outlook for March. There are unusually few changes this month from the Early Outlook to the Updated Outlook. I am somewhat surprised.

Some housekeeping: On February 19, 2021, 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 March 2021 Early Outlook was issued. This article presents the NOAA update of their Early temperature and precipitation Outlooks for March and the most recent Drought Forecast update for the month of March.

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First, we will compare the NOAA Early Outlook for March, 2021 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 MARCH 2021

The updated March 2021 temperature and precipitation outlooks are not too significantly changed from the previous mid-month outlook. The updated outlooks utilized the latest short-range, medium-range, extended-range and subseasonal dynamical model forecast guidance for some adjustments. In addition, the most recent assessment of boundary conditions (anomalous soil moisture and snow cover), the MJO state and the AO state are also considered in making the update.

The uncertainty whether short-range forecasts of a change to a positive AO phase would persist and be supported by changes in stratosphere troposphere interaction have been removed as the extended range forecasts of the AO support continuation of the current positive AO phase through at least mid-month.

The MJO influence described at mid-month, however, remains in play as predictions of the MJO signal (i.e., RMM) are forecast to shift from Phase 5/6 (Indonesia/far western Pacific) to potentially Phase 8/1 over the next two weeks. This increases uncertainty in the temperature outlook some for the Great Lakes, Ohio Valley and Northeast as the odds for below-normal temperatures would increase for the 3rd and 4th weeks of March. This is strongly at adds with the latest Week 3-4 dynamical model guidance which continues persistence of favored above-normal temperatures for the eastern two-thirds of the CONUS from Week-2.

Anomalous snow cover and depth remains strongly negative across the northern plains as noted in the mid-month outlook. Soil moisture anomalies are likely to become increasingly positive for areas in the lower Mississippi Valley, the Tennessee Valley and lower Ohio Valley as a combination of antecedent conditions from recent snowmelt and heavy rains in some areas prior to the start of the month.

Based on the above factors, the updated March 2021 temperature outlook keeps elevated odds for monthly mean below-normal temperatures for southern Alaska, and the Far West – which is a more narrow area than the mid-month outlook depiction. Above-normal monthly mean temperatures remain favored for the eastern two-thirds of the CONUS, however, there are some changes. First, above-normal temperatures in the Southwest were shifted eastward in the updated outlook and probabilities across the northern Plains and Great Lakes are increased. Lower probabilities are located in a zonal swath for the Tennessee and lower Ohio Valley’s due to possible impact from above-normal surface wetness and also along the eastern seaboard due to cooler temperatures forecast early in the month and also due to the potential impact from the MJO, albeit highly uncertain.

For precipitation, the latest dynamical model guidance, especially in the short term help better focus favored above-normal precipitation in the Tennessee Valley at the start of the month of March. This region and areas northward to the Great Lakes are slightly modified from the half month lead outlook. Below-normal precipitation is highlighted from the interior West and Southwest eastward to the central and southern Plains and along the Gulf Coast and Florida. Changes in these regions from the earlier outlook include removal of the slightly elevated odds for above-normal precipitation in the northern Rockies, removal or reducing of chances for below normal precipitation for parts of California and the central and southern Great Basin and Rockies. A strong jet forecast to impinge western Alaska through at least the first half of the month, favors elevated odds for above-normal precipitation for much of Alaska with removal of the small region of elevated odds for below-normal precipitation along the Alaska south coast in the mid-month outlook.

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 Sunday, we have short-term forecasts that cover 26 of the 31 days in March so we are in pretty good shape to see if the whole is equal to the sum of the parts.

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 forecast for the month fits well with the four short-term 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 forecast for the month fits well with the four short-term forecasts.

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 February 28, 2021

Latest Monthly Assessment – The moderate La Niña event is expected to slowly relax over the next few months, and thus its influence on the Nation’s weather should gradually decline. But for March 2021, it does not look like any decline in strength will be sufficient to reduce its influence, so it remains a significant factor in the Climate Prediction Center’s (CPC’s) outlooks. Subnormal March Precipitation is favored in the eastern Great Basin, the Four Corners States, much of the central and southern Plains, the immediate Gulf Coast, and Florida. This includes much of the region currently experiencing entrenched severe to exceptional drought (D2 to D4 on the Drought Monitor). Meanwhile, the odds tilt toward surplus precipitation in the Great Lakes Region, the Ohio and Tennessee Valleys, the middle Mississippi Valley, central and eastern Alaska, and Hawaii. Much smaller patches of less-severe drought are scattered across these regions. Below-normal temperatures are anticipated in the Far West and the southern one-third of Alaska, but warmer than normal conditions are favored over a much larger part of the country, specifically from the eastern Rockies to the Atlantic Coast, in northern Alaska, and throughout Hawaii.

February 2021 brought a variety of changes to the areas in drought, but the bottom line is that much of the western half of the Nation remains in some degree of dryness, and extreme to exceptional drought (D3 and D4) continues to cover most of the Four Corners States and the southern Great Basin, plus some adjacent areas. Drought conditions improved along the West Coast and in most of Hawaii, and scattered patches of improvement were observed in part of the Four Corners States, the adjacent northern Rockies, the central Plains, central and western Texas, and widely scattered locales farther east. At the same time, dry conditions worsened in some parts of the Intermountain West, northern Montana, the northern Plains, the remainder of Texas, and again in scattered patches farther east.

Taking all this into account, the Drought Outlook through March 2021 expects conditions to generally persist in areas currently affected by drought, with development expected in parts of the central and southern Plains and much of the Florida Peninsula. Improvement or removal is only forecast for southwestern Oregon and immediately adjacent areas, and across Hawaii.

Looking back on February 2021 to relate the forecast for March to the actuals in February

First February 2021 Temperature (27 out of 28 days).

And then February Precipitation (27 out of 28 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 March, 2021 and compare it with the Early Outlook. It is not to critique the updated Outlook for March based on our opinions but we point out possible inconsistencies if we find them. 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 March 11, 2021, IRI/CBC will issue their ENSO forecast and we will present that and critique it. What they present on March 11 is likely to begin to impact the forecasts for the next three months and should shed some light on Spring and beyond. 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.