Moderate La Niña conditions continue over the equatorial Pacific. A slow decline in intensity is likely to result in ENSO-neutral conditions later this year, but for the forecast period through May 2021, it will continue to influence conditions across the Nation.
As a result, the Climate Prediction Center’s (CPC) seasonal forecast for March-May 2021 largely reflects the climate anomalies favored during La Niña, based on a composite of historical events.
During the past month, drought conditions as depicted in the Drought Monitor have changed in many parts of the Nation, but only a few scattered areas saw dramatic improvement or deterioration. In particular, there were no widespread changes to the intense, protracted drought across the Four Corners states and some adjacent parts of the High Plains and Great Basin.
The one relatively small part of this region that experienced heavy precipitation and marked drought relief was noted in parts of Arizona. A series of storms brought a dramatic increase in higher-elevation snowpack. Across the state, only 10 to locally 50 percent of normal snowpack was reported in mid-January, which increased to between 50 and 100 percent of normal in mid-February.
Some of the higher elevations improved from D4 to D2, and less dramatic improvement to D3 occurred in a swath across the central part of the state. Southwest Arizona, where drought has been less intense, also saw improvement.
Farther west, a stormy pattern along the West Coast resulted in large areas of improvement from California to northward through Washington, with the most substantial changes in central Washington and the coastal areas of southwest Oregon and adjacent California.
Other regions with notable improvements included the central Great Plains, the middle Mississippi Valley, and central Texas. In contrast, drought conditions deteriorated in the northern Rockies and adjacent High Plains, The Texas Panhandle, and a few patches across the Southeast.
Moving forward, the large area of drought covering much of the western half of the country is expected to generally persist, with areas of intensification possible. In addition, drought is expected to expand eastward into the south-central Plains, where odds favor below-normal March-May precipitation and a return to warmer than normal conditions.
The only area in the West where drought should ease extends from southwest Oregon to central Washington. Outside this extensive area of drought area, only small, isolated locales are impacted by drought. The scattered patches across the Southeast should be approximately the same at the end of May, though precipitation in the short-term may provide limited relief for the time being.
Meanwhile, drought is expected to develop across much of the Florida Peninsula, where moisture deficits have been increasing and odds favor a warm and dry March-May, which is typically one of their drier seasons in any case.
Across the remainder of the country, the small regions of drought in northern New England, the Midwest, Hawaii, and Puerto Rico should improve or be removed by the end of May.
Forecast confidence is moderate for the Pacific Northwest, low in the northern Rockies, and high across the southern half of the Western region.
- 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 low in the northern reaches of the High Plains region, and high farther south.
- 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 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 moderate in western Iowa and high in the rest of the Midwest region.
- 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 high in the southern Plains, and low farther east.
- 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 Florida, and low elsewhere in the Southeast region.
- 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 moderate in the Northeast 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 for Alaska, Hawaii, and Puerto Rico.
- Consistent with La Niña 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.