Written by Sig Silber
Updated at 9:50 pm EST February 19, 2021, to incorporate the Week 3 – 4 forecast which slightly modifies the fit of the monthly forecast with the sum of the available short-term forecasts.
Here is the February 18, 2021, NOAA four-season forecast for CONUS and Alaska including the Early Outlook for March 2021. It covers a period that begins one month later than the forecast last month and extends one month longer. Also included is the updated three-month drought forecast. There is not much change for the next three months from the forecast issued last month which is bad news for the Southwest with respect to drought. But right after that, there is some change which is mostly in the precipitation forecast and it is first an expansion of the dry area to include more of the Southern Tier and then an expansion of the wet anomaly to include the Southeast.
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A. Focus on the NOAA Update
A note about terminology; the deviations from climatology/normal are color-coded but also labeled “A” for more than (above) normal and “B” for less than (below) normal. The area designated EC means Equal Chances of being more or less than normal. In my comments for the shorter-term maps, NOAA uses “N” instead of “EC” as they believe they can be more definitive for shorter time frames. So the words “warm”, “cool”, “wet”, “dry” should be generally interpreted as being relative to climatology/normal for that location and time of year.
First, we will take a look at the NOAA Early Outlook for March 2021. It is called the Early Outlook because it will be updated at the end of February. Only the March Outlook will be updated at that time.
Temperature
Precipitation
We have nothing to compare these maps with as NOAA does not provide in their Update a forecast for each of the subsequent two months separate from their three-month forecast. Thus I do not have forecast maps for March from the previous NOAA Report to compare against. And the current month is not over so we can not really compare the forecast for next month against the actual for this month. It is probably best to just try to understand what NOAA is trying to convey about March*. For Temperature, it is cool in the Northwest and Southern part of Alaska including the Alaskan Panhandle, and warm for the Eastern and Southern Tier of CONUS with an EC transition zone between the cool and warm areas. With respect to precipitation, the Southern Tier of CONUS is dry and there are two wet anomalies one centered on central and western Montana and northern Idaho, and a large wet anomaly the covers the greater Great Lakes and Midwest. For Alaska where it is forecast to be warm, it is forecast to be wet and where it is forecast to be cold it is forecast to be dry.
* compared to normal/climatology for the indicated time of the year.
Visual Consistency Testing.
It is useful to see how the month forecast fits with the set of shorter forecasts that we have. The first two maps cover mostly February with the second map extending to March 4, 2021, and the third map as of today covers through March 12. Thus only the third of the three maps (to a much lesser extent the second map) is useful for this purpose. The Seasonal Outlook was issued neither early or late this month since the third Thursday fell on February 18. the earliest possible issue of the forecast is on the 15th of the month. We are publishing on a Thursday so we do not have the updated Week 3-4 forecast. 12 days is not a great basis for doing this visual consistency testing but it is worth looking at. There are 31 days in March. We have now updated this article and now have 19 days which is fairly adequate for our purposes. So many readers will find the updated Week 3 – 4 forecast in this section and other readers who have read the article before it was updated can click on the article a second time to see how that forecast changed remembering it covers a different two-week period since it the new week 3 – 4 forecast was issued a week later.
First Temperature
 |  |  |
| The new monthly forecast is to the right. Does it appear to be reflective of the parts of the month for which we have forecasts? |
| We have updated this section when the Week 3 – 4 forecast was issued this Friday, February 19, 2021. The fit looks pretty good but there are questions about the cool anomaly in the Northwest. Read the Week 3 – 4 discussion below. We will revisit the forecast at the end of February when the March forecast is updated. |
And then Precipitation
 |  |  |
| The new monthly forecast is to the right. Does it appear to be reflective of the parts of the month for which we have forecasts? |
| We have updated this section when the Week 3 – 4 forecast was issued this Friday, February 19, 2021. The fit looks pretty good but there are some questions about the wet anomalies. Read the Week 3 – 4 discussion below. It is important to remember that we are only looking at 19 days of short-term forecasts and March has 31 days. So the last 12 days will certainly impact the average for the month. We will revisit the forecast at the end of February when the March forecast is updated. |
Sometimes it is useful to look at the Week 3-4 Discussion. We have now added that discussion after it was issued on Friday afternoon February 19, 2022.
Week 3-4 Forecast Discussion Valid Sat Mar 06 2021-Fri Mar 19 2021
In the tropics, the La Nina pattern continues to maintain a strong presence over the equatorial Pacific while the Madden Julian Oscillation (MJO) signal across the west Pacific has weakened over the last several days. The RMM index, which appears to be influenced by other tropical waves and the current La Nina state, is forecast to continue weakening during the next week. There is some indication that a weak MJO may re-emerge prior to the start of the forecast period, but multimember ensembles from the GEFS and ECMWF are uncertain on the timing and location. In the extratropics, the Arctic Oscillation (AO) has undergone a transition from a strong negative phase to a slightly positive phase and is forecast to stay neutral/positive throughout the Week-2 period. With these factors in mind, this week’s forecast is primarily based on a blend of dynamical model guidance with additional influences from La Nina.
The anomalous 500-hPa height patterns are in good agreement among the dynamical models (CFS, ECMWF, JMA and the SubX multi-model ensemble). Models consistently feature positive height anomalies over the North Pacific and off the coast of Newfoundland with below normal heights across Alaska. This pattern bears some similarity to the positive phase of the AO. The most relevant inconsistency among the dynamical models is the extent to which the troughing over Alaska extends down to the western coast of CONUS, with the CFS favoring a more southward extension compared to the ECMWF and JMA.
As a result of the widespread positive height anomalies over much of CONUS, the temperature forecast tilts broadly toward above-normal probabilities from the Southwest to the eastern US. The highest probabilities are forecast throughout the Upper Midwest and the Northeast. The troughing over Alaska favors colder than normal conditions across the southern part of the state. The aforementioned uncertainty regarding the extent to which that troughing will extend south is further manifested in uncertainty in anomalous temperature conditions. As such, equal chances are carved out for the western and northwestern portions of CONUS.
Consistent with La Nina conditions and dynamical model guidance, the precipitation forecast for the outlook period favors below-normal precipitation across the southern tier and along the east coast with highest probabilities in the Southeast. Dynamical model guidance is less consistent with regard to an anomalous precipitation signal across the northern tier and thus equal chances are forecast. Elevated probabilities for anomalously wet conditions are forecast over western Alaska with equal chances favored over the rest of the state.
Sea surface temperature anomalies surrounding Hawaii are slightly above normal, elevating the chances of above normal temperatures throughout the forecast period. Dynamical model guidance also shows equal chances across the region tilting toward slightly below normal precipitation over the southeastern islands.
Now we consider the three-month Outlook.
Notice that the three-month periods are abbreviated e.g /March/April/May is shown as MAM. You will see such abbreviations often in this report.
Prior Temperature Outlook for MAM 2021
New Temperature Outlook for MAM 2021
Now Precipitation.
Prior forecast for MAM 2021
New Precipitation Outlook for MAM 2021
I can make the comparison easier by showing the prior forecast and the current forecast side by side.
| Prior Forecast | New Forecast | |
| Temperature | | |
| Precipitation | | |
Now let us focus on the long-term situation.
First Temperature
Prior 14 Month Temperature Outlook: MAM 2021 – FMA 2022
New 14 Month Temperature Outlook: AMJ 2021 – MAM 2022
To compare maps from one release to another, one needs to remember that the new release drops one three-month period and adds a later one. So to make the comparisons one has to shift the new maps to the right one position and that makes the map on the right drop-down to become the left-most map in the next level. I do not have a computer software tool for doing that for you so you have to do it mentally. When I do the comparison, I print the two sets of maps and put them side by side and number the same three-month maps 1, 2, 3,…..,11 in both sets of maps to make it easier for me to easily compare the same three-month period in the new with the previous forecast. One uses the same procedure to compare the precipitation maps. Based on this procedure, I conclude that:
Now Precipitation
Prior 14 Month Precipitation Outlook: MAM 2021 – FMA 2022
New 14 Month Precipitation Outlook: AMJ 2021 – MAM 2022
If you want larger versions of each map (temperature and precipitation) you can find them here. And then each of those maps can be clicked on to further enlarge them.
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 months.
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 months.
*The concept is that the probabilities of a deviation from climatology in the First Month and the combined Month Two-Three forecast that one derives must average out to the probabilities shown in the three-month maps.
Below is the NOAA Discussion (slightly reorganized) released by NOAA on February 18, 2021. Headings that are “Initial Cap” only rather than all caps were added by the Author of this Update Report for clarity. Also, we have organized the sequence of the sections of NOAA Discussion to first present the Atmospheric and Oceanic Conditions and then the Initial Month (February), the NOAA Summary for FMA, and finally the remainder of the 15-Month Forecast.
CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS
Oceanic and atmospheric observations reflect La Nina conditions. During the past four weeks (Jan 17 – Feb 13), sea surface temperature anomalies were below average across the west-central Pacific to 130W. The latest Nino-3.4 index is -1.2 degrees C. Negative subsurface temperature anomalies continue to persist at a depth of near 200 meters from 170W to 130W. The magnitude of negative upper-ocean heat anomalies has remained nearly steady since mid-November. Suppressed convection persists across the equatorial Pacific surrounding the Date Line, while enhanced convection continues across much of Indonesia and the Philippines. The coupled ocean-atmospheric system is consistent with La Nina conditions.
PROGNOSTIC DISCUSSION OF SST FORECASTS
The CPC SST consolidation for the Nino-3.4 region depicts negative SST anomalies decreasing in magnitude to less than -0.5 degrees C during the late spring. The North American Multi Model Ensemble (NMME) ensemble mean forecast for the Nino-3.4 SST anomaly has a similar evolution during the next several months. Based on these model forecasts as of early February, the official CPC/IRI ENSO outlook states that there is a 60 percent chance that La Nina transitions to ENSO-Neutral during the Northern Hemisphere spring (April-June). Later in the summer and fall 2021, dynamical and statistical tools diverge, with the dynamical models (NMME and CFSv2) favoring a return of La Nina conditions.
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS Since La Nina conditions are likely to persist through the early spring (MAM 2021), La Nina composites were used in creating the temperature and precipitation outlooks for that three month period. Dynamical model guidance such as the North American Multi-Model Ensemble (NMME) and the Calibration, Bridging, and Merging (CBaM) version of the NMME were also tools that were used during MAM and were increasingly relied upon starting with AMJ. The consolidation tool, which includes NMME input and various statistical tools, was also used, especially at later leads. Also, based on the likelihood of drought persisting across parts of the Great Plains and Southwest heading into the warm season, low soil moisture conditions were a factor in the temperature outlooks during the spring and summer 2021. Due to a number of back-to-back La Nina events in the historical record since the 1950s, a reemergence of La Nina by the fall was considered. At later leads, decadal trends in temperature and precipitation were the primary tool used in creating the seasonal outlooks.
30-DAY OUTLOOK DISCUSSION FOR MARCH 2021
As we approach the month of March, the pattern across the greater North America region appears to be in the process of changing from the last few weeks. Week 2 dynamical model forecast guidance supports a change to anomalous ridging over the north central Pacific with the central North America mean trough shifted westward and deepening over portions of western North America including into western CONUS. Downstream of this, more amplified ridging and positive 500-hPa height departures are forecast for much of the southeast U.S. favoring a more southwesterly-westerly mean flow for the eastern half of the CONUS then in recent weeks.
The most recent Week 3-4 guidance from the CFS, ECMWF and extended GEFS support a continuation of this change, in the mean, for approximately the first two weeks of March. March CFS forecasts as well as those from the majority of the NMME and Copernicus model suites also favor this pattern and associated anomalous temperature and precipitation patterns which are consistent with typical La Nina conditions in many ways during this point in the seasonal cycle.
Other factors to consider in addition to a review of the available dynamical model guidance across time scales, is the state and forecast evolution of the MJO, the AO and most recent anomalous snow cover.
The MJO has been active during January and February resulting in both constructive and destructive interference with La Nina impacting anomalous tropical rainfall, circulation and other variables in the Pacific basin. Forecast information suggests that the MJO is likely to weaken or become less coherent entering March and is not strongly utilized in the March outlook due to this as well as indications that much of recent mid-latitude temperature and precipitation anomalies have most likely been driven by high latitude subseasonal variability.
Predictions in the short-term (next 10 days) indicate the phase of the AO (which has returned to near zero) to remain near zero or weakly positive in the mean as compared to the strongly negative phase of the last couple months. The Sudden Stratospheric Warming (SSW) of early-mid January would continue to elevate odds for a negative AO phase into the month of March resulting in the continuation of potential cold air outbreaks into the mid-latitudes. There is high uncertainty, however, in whether the negative phase of the AO will return and persist and if so where troughing and so favored below-normal temperatures are most likely to develop at forecast lead times well into the month of March.
Finally, substantially below-normal snow cover and snow depth exist across parts of the northern Plains and upper Mississippi Valley. Although, early in the seasonal cycle, taken alone, this is likely to favor above-normal temperatures in these areas.
Temperature
After consideration of the factors described above, the March temperature outlook favors monthly mean below-normal temperatures for a region stretching from south-central Alaska southeastward to include northern California, the Pacific Northwest and the northern Rockies. This is strongly supported by dynamical model guidance across time scales and is consistent with La Nina conditions. Elevated probabilities for above-normal temperatures are depicted for parts of the north and west coast of Alaska based on negative sea ice and positive ocean surface temperature trends especially later in the month of March.
Dynamical model guidance and in some cases typical La Nina conditions and positive temperature trends favor above-normal temperatures for a region from the Southwest eastward to include the southern CONUS and northward to encompass the central Mississippi Valley, eastern Great Lakes, Ohio Valley and eastern seaboard. Only slightly tilted odds of above-normal temperatures or Equal-Chances (EC) are depicted for the northern and central Plains, central and upper Mississippi Valley and parts of the Ohio Valley, Great Lakes and Tennessee Valley due to the uncertainty and conflicting indicators described above with respect to the phase of the AO, anomalous snow cover and snow depth and dynamical model guidance.
Precipitation
For precipitation, below-normal monthly total precipitation amounts are most likely for the southern tier of the CONUS with some expansion of this highlighted area to the central Great Plains, primarily based on dynamical model guidance which is consistent with La Nina typical impacts. For similar reasons, elevated odds for above-normal precipitation is forecast for a small region in the northern Rockies and for the Ohio Valley and Great Lakes region. For Alaska, elevated odds for above-normal precipitation is depicted for parts of the north and west coasts associated with anticipated more open and warmer waters in nearby areas as well as typical La Nina impacts. Below-normal precipitation is most likely for the south-central coast and far northern Alaska Panhandle.
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS (focus on MAM)
La Nina conditions are present across the equatorial Pacific Ocean, as represented in current oceanic and atmospheric observations. The official CPC ENSO forecast indicates that La Nina conditions are favored to persist through March-April-May, followed by a transition to ENSO-Neutral later in the spring and into the early summer.
The March-April-May (MAM) 2021 temperature outlook favors above normal temperatures for a majority of the CONUS, with the largest probabilities (greater than 70 percent) forecast across parts of the Southwest. Elevated probabilities of below normal temperatures are forecast from the Pacific Northwest and Northern Rockies northward to the Alaska Panhandle and southeastern Mainland Alaska. Above normal temperatures are more likely for western and northern Mainland Alaska. The MAM 2021 precipitation outlook features enhanced probabilities of below normal precipitation amounts for much of California and the Southwest eastward to the central and southern Great Plains, along the Gulf Coast, and southern portions of the East Coast. Above normal precipitation is slightly favored for parts of the Northeast, Midwest, Pacific Northwest, Northern Rockies, and western Mainland Alaska. Equal chances (EC) are indicated among areas where seasonal mean temperatures and seasonal accumulated precipitation amounts are expected to be similar to climatological probabilities.
PROGNOSTIC DISCUSSION OF OUTLOOKS – MAM 2021 TO MAM 2022
TEMPERATURE
Above normal temperatures are favored for a majority of the CONUS during MAM with the largest probabilities (more than 70 percent) centered over west Texas and southeast New Mexico due to low soil moisture and strong support among the dynamical models. Below normal temperatures are slightly favored from the Pacific Northwest and Northern Rockies northward to the Alaska Panhandle and southeastern Mainland Alaska during MAM, based on La Nina composites and model guidance. Decadal trends were the primary factor for increased chances of above normal temperatures across western and northern Mainland Alaska during MAM. These increased chances of above normal temperatures extend south of the Brooks Range due in part to ongoing low snowpack across east-central Alaska which could lead to an early snowmelt. Forecast confidence for MAM is lowest across the Northern Great Plains where a highly variable pattern is expected, especially during March. Based on this and conflicting signals for the three month period, EC is indicated. As predicted low soil moisture begins to have more of an influence on surface temperatures later in the spring coupled with less effects from La Nina, above normal temperatures are the favored category across the northern Plains, beginning with AMJ. Low soil moisture also supports larger probabilities of above normal temperatures across the Great Plains and Southwest through the summer. During late spring and summer (MJJ through JAS), above normal temperatures are favored throughout the forecast domain. However, probabilities are lowest across the north-central CONUS where decadal trends are the weakest. Decadal trends were the largest factor during the winter 2021-2022 and spring 2022.
PRECIPITATION
Based on the latest model guidance and likely influence of La Nina through the early spring, elevated probabilities of below normal precipitation were expanded to include more of the Gulf Coast during MAM, compared to the previous outlook. The displaced storm track to the south, that occurred during early to mid-February, is expected to shift back to the north prior to the beginning of March as high latitude blocking eases. Other slight changes from last month’s MAM outlook include expanding the favored area of below (above) normal precipitation to cover more of the northern Great Plains (Northeast). The highest confidence in the MAM precipitation outlook remains across the Southwest due to excellent agreement among dynamical and statistical tools. The precipitation outlook for Alaska during MAM is consistent with the seasonal temperature outlook. The latest NMME and consolidation tool support a larger coverage, relative to last month’s outlook, with elevated probabilities of below normal precipitation across parts of the Great Plains and Gulf Coast States during AMJ. Another notable change from the previous month was to slightly favor below normal precipitation across the Great Plains during MJJ, which coincides with their wetter climatology. This dry signal is supported by multiple tools inducing the NMME, IMME, CBaM, and consolidation. Although decadal trends support a wet signal across the Ohio Valley during the summer, the latest dynamical models have trended drier. Therefore, EC is indicated for this region. During the fall and into the winter 2021-2022, decadal trends and consideration of a potential second La Nina were the primary factors in the forecast precipitation patterns.
Climate Normals
The Climatic normals are based on conditions between 1981 and 2010, following the World Meterological Organization convention of using the most recent 3 complete decades as the climatic reference period. The probability anomalies for temperature and precipitation based on these new normals better represent shorter term climatic anomalies than the forecasts based on older normals.
For a description of of the standard forecast tools – their skill- and the forecast format please see our web page at http://www.cpc.ncep.noaa.gov/products/predictions/long_range/tools.html (Use Lower Cas e Letters) Information on the formation of skill of the CAS forecasts may be found at: http://www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/US/Outlook/outlook.shtm l (use lowercase letters) Notes – These climate outlooks are intended for use prior to the start of their valid period. Within any given valid period observations and short and medium range forecasts should be consulted.
This set of outlooks will be superseded by the issuance of the new set next month on Mar 18 2021
1981-2010 base period means were implemented effective with the May 19, 2011 forecast release.
We will discuss this more when we compare the JAMSTEC to the NOAA forecast. But it is useful to look at the JAMSTEC discussion especially as it applies to Spring and Summer since their raising the issue that this is somewhat of a La Nina Modoki raises questions about the use of statistical analysis in these forecasts. We will address this in more detail when we publish our NOAA v JAMSTEC comparison. NOAA hardly recognizes an El Nino Modoki let alone a La Nina Modoki. Fortunately, the major impact of a La Nina Modoki is seen in the Western Pacific as it impacts the track of cyclones headed west. But what heads west frequently turns north and then returns east at higher latitudes and impacts North America in that way but perhaps in a more subtle way. Below is the JAMSTEC discussion.
Feb. 15, 2021 Prediction from 1st Feb., 2021
ENSO forecast:
Observation continues to show a La Nina Modoki-like state. The SINTEX-F continues to predict that this La Nina Modoki-like state will start to decay from early boreal spring. The tropical Pacific will return to a neutral-state from late spring.
Indian Ocean forecast:
Observation shows that the tropical Indian Ocean is a neutral state. The ensemble mean prediction suggests that the present condition will persist this year. Observation also shows the occurrence of Ningaloo Nino off the west coast of Australia, and the prediction suggests that it will persist in austral autumn (boreal spring).
Regional forecast:
On a seasonal scale, the SINTEX-F predicts that most part of the globe will experience a warmer-than-normal condition in boreal spring (austral autumn) except for Alaska, western Canada, northern part of the South American Continent, and Indochina Peninsula. In boreal summer (austral winter), the model predicts persistence of a similar condition except for Indochina Peninsula.
As regards to the seasonally averaged rainfall in boreal spring (austral autumn), a drier-than-normal condition is predicted for U.S.A., La Plata Basin, southeastern China, and Indonesia. In contrast, Canada, most part of Brazil, Philippines, Indochina Peninsula, India, Sri Lanka, and northern China will experience a wetter-than-normal condition. In boreal summer (austral winter), a wetter-than-normal condition is predicted for India, Philippines, and Indonesia. In contrast, eastern U.S.A, many parts of the South American Continent, central Africa, western Russia, and western China will experience a drier-than-normal condition.
The model predicts most part of Japan will experience a hotter-than-normal condition in spring and summer as a seasonal average. As regards to the seasonally averaged rainfall, Kyushu and Okinawa will experience a drier-than-normal condition in spring. In summer, Honshu (except for Hokkaido, Kyushu, Shikoku) will experience a drier-than-normal condition.
Drought Forecasts
These two forecasts (Monthly and Season) are issued by the same agency but to obtain them you need to access two different links here (for the single month forecast which comes out at the end of the month and here for the forecast issued with the Seasonal Outlook.
Here is the Three-Month Drought Forecast which was issued on February 18, 2021
Discussion for the Seasonal Drought Outlook
Tools used in the U.S. Seasonal Drought Outlook (SDO) included the Climate Prediction Center (CPC) temperature and precipitation outlooks for March 2021 and March through May (MAM) 2021, various short- and medium-range forecasts and models such as the 7-day quantitative precipitation forecast (QPF) from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC extended-range forecasts (ERFs), the Week 3-4 outlooks and tools from CPC, dynamic models at the monthly and seasonal time scales, the 384-hour total precipitation forecasts from several runs of the GFS, climatology for March and MAM, and initial conditions for parameters such as soil moisture. Existing drought areas on the forecast are based on the February 16 U.S. Drought Monitor. Forecasts currently reflect the presence of a moderate La Nina. It should slowly weaken as the year progresses. But for MAM, its influence will continue.
Across the West, only parts of the Pacific Northwest are expecting a notable degree of drought relief. Heavy precipitation is expected short-term along the immediate coast and in the Cascades, and odds favor surplus precipitation at longer-range time scales, particularly in Washington. Elsewhere, persistence is expected, with confidence increasing as you move south. In Montana, southern Idaho, and adjacent areas, the next week should bring little precipitation outside the higher elevations, but the odds favor above-normal precipitation in late February, and for March, but not for MAM as a whole. Given the mixed forecast signals, enhanced chances for above-normal MAM temperatures, observed short-term trends, the low snowpack at this time of year, and the relatively long-term (if not intense) nature of the drought there, persistence seems more likely than improvement. Farther south, the situation is more straightforward. Little or no precipitation is forecast through the end of February, and the outlook for MAM favors abnormally warm and dry conditions. Persistence is the only logical forecast, with the highest confidence in much of Arizona and New Mexico, where this is typically a dry time of year in any case.
Forecast confidence is moderate for the Pacific Northwest, low in the northern Rockies, and high across the southern half of the Western region.
Similar to most areas farther west, persistence or intensification is expected throughout the drought areas in the High Plains Region, with more confidence in southern sections than farther north. There are mixed signals across the most of the Dakotas and Wyoming, generally favoring dry weather for the coming week, surplus precipitation for late February, and no particular tilt of the odds for MAM as a whole. Precipitation climatologically increases toward the end of spring, so any short-term departures from normal would probably be minimally consequential comparted to late spring, when normals are higher. The bottom line is that none of the tools gives any reason to expect abundant precipitation on any time scale, so persistence is the better forecast. Across central and southern sections of the region, however, the tools robustly favor warmer and drier conditions than normal on most time scales ranging from one week to three months (the MAM outlook). Persistence is the only reasonable forecast. Also, the expected warm and dry spring, along with antecedent conditions slightly drier than normal, point toward drought expanding across south-central Kansas by the end of spring.
Forecast confidence is low in the northern reaches of the High Plains region, and high farther south.
Outside western Iowa, there is not much drought to speak of in the Midwest region. Forecasts for western Iowa favor subnormal precipitation for the next two weeks, with no consensus of indications in either direction after that. Meanwhile, above-normal temperatures should prevail. Considering this and the long-term nature of the drought there, there’s no particular reason to expect relief, so persistence is the best bet. In the rest of the region, drought is restricted to parts of northern Minnesota, central Illinois, and northwestern Indiana. There are enhanced chances for above-normal MAM precipitation in all these location, thus the forecast for drought removal.
Forecast confidence is moderate in western Iowa and high in the rest of the Midwest region.
Despite the almost-unprecedented cold and wintry conditions covering large parts of Texas in mid-February, drought of varying intensities still dominates southern and western Texas and, less intensely, western Oklahoma. Some areas in Texas are entrenched in extreme drought or worse. This is the southeastern end of the large drought area across the West, so forecast reasoning is similar. The enhanced chances of a warm and dry spring can only lead to conditions staying bad or getting worse, so persistence is forecast. In fact, drought is expected to expand eastward into central Oklahoma and part of eastern Texas by the end of May, at which point the current severe wintry weather will be a distant memory. Spotty areas of abnormal dryness and the enhanced chances for warm and dry MAM conditions are driving the forecast. Farther east, from central Oklahoma and eastern Texas through the lower Mississippi Valley and Tennessee, only small, isolated areas of drought exist. The recent cold, wet conditions are bringing short-term relief to these areas, but the MAM outlook favors subnormal precipitation in southern parts of the region, and unusually warm conditions everywhere. The sum of all this information favors persistence across Louisiana and Mississippi (despite some short-term relief), but drought removal from Tennessee
Forecast confidence is high in the southern Plains, and low farther east.
The preponderance of tools points toward drought development in central and southern Florida. The MAM outlook tilts significantly toward above-normal temperatures and subnormal precipitation there, where some moisture deficits are already in place. With all of this happening during a relatively dry season under the best of circumstances, drought development seems not only likely, but imminent. Elsewhere, drought is restricted to a small part of Alabama. Cold and wet conditions of late are providing short-term relief, but with enhanced chances of a dry and warm spring, the odds are better than not that these areas will be in drought at the end of May.
Forecast confidence is high in Florida, and low elsewhere in the Southeast region.
Drought has been gradually improving and contracting for the past several months in the Northeast region. Now, only a few patches of moderate drought remain in upstate New York and part of northern New England. Given the recent cold and stormy conditions, along with odds favoring surplus precipitation in the MAM outlook, the logical forecast is for these areas of drought to be gone by the end of spring.
Forecast confidence is moderate in the Northeast region.
Consistent with La Nina conditions, the outlook favors above-normal rainfall for MAM across Hawaii, which should bring some degree of relief to the areas of drought in central and southeastern parts of the state, although current areas of severe drought or worse could remain by the end of May with reduced intensity. There is no drought in Alaska at this time, but abnormal dryness covers a large part of the state. Right now, there isn’t enough evidence to forecast drought development in any specific area, but conditions will be closely monitored. In Puerto Rico, neither dryness nor wetness is favored over the next several months, but the Commonwealth is headed toward a wetter time of year, and the increase in rainfall, even if only near-normal, should be enough to bring an end to the drought by the end of May.
Forecast confidence is moderate for Alaska, Hawaii, and Puerto Rico.
ENSO Considerations
We have covered some of this when we reported on the IRI/CPC analysis on February 11, 2021. We may discuss it again when we do the NOAA/JAMSTEC Comparison.
Now let us look at the NOAA ENSO Update
More information can be found here.
NOAA depends a lot on the IRI-CPC analysis.
It is useful to see how the view has changed if at all which is shown below
This compares the new forecast to the one made last month. The first forecast in each month is based on a survey of meteorologists and the second is based on climate models so they are not totally comparable. But there is not much change through MAM but AMJ is more evenly balanced between La Nina and ENSO Neutral than the forecast in Mid-December and the chances of an El Nino getting started soon have been reduced.
NOAA has their own proprietary model which they rarely use. It is not exactly clear why they shun their own model.
In most cases, I freeze the models as of the date of publication but for this one, I am going to just let the above model run so if you refer to the article in the future, the values in the above may not relate well to the discussion. But I am doing that so if you refer to this article in say two weeks, you will see if there has been any change in the forecast from this model.
Comparison models would include JAMSTEC
And the JAMSTEC Modoki Index
And the Australian BOM
And here is one more graphic that I created from a different NOAA source. It is a cross-section of the Pacific Equator from the surface down to 450 meters. What is shown in this graphic is the temperature anomalies not the absolute temperature. ENSO is measured at the surface since only the surface interacts with the atmosphere. But the future of the surface often is impacted by the water below the surface. At some point, NOAA will update the normal values for this area as they do that every five years but they have not done so yet. See the note at the beginning of this article.
The current situation and three prior months are shown.
| Last Month | Currently |
 |  |
| Three Months Ago | Two Months Ago |
 |
|
The Southern Oscillation Index or SOI being above 7 confirms that the Atmosphere is in tune with the Sea Surface Temperatures in the Pacific along the Equator. This is another graphic that we have not frozen.
B. Conclusion
We are now in a La Nina. There may be an issue as to how westerly oriented this La Nina will be and what if any will be the impacts of it having some characteristics of a Modoki as JAMSTEC suggests.
NOAA has introduced the concept of a double-dip La Nina. That is not unusual. It would be devastating for the West.
