NOAA Seasonal Dought Outlook – September, October, November – AgFax | Panda Anku

Last month, continued increased monsoon convection brought widespread drought relief in the Four Corners region and the Great Basin, with frequent localized flash flooding observed in many areas. Periods of heavy rainfall also reversed the trend of rapidly onset drought in the central corn belt and Ohio River Valley, but also led to historic flooding in mountainous parts of eastern Kentucky.

In contrast, episodes of extreme heat and drought between these two wetter regions caused significant drought extension in the plains and western corn belt. Generous rainfall moderated drought conditions in the Southeast, while weaker rainfall and multiple heat waves led to continued deterioration in parts of New Jersey, southeast New York and southern New England.

The autumn months are a very transitional time of the year as Gulf moisture recedes southward and climatological rainfall decreases on the plains and the rainy season begins to increase in the northwest. Declining sunlight and temperatures reduce evaporation rates, while maturing crops reduce the effects of short-term drought conditions.

Through late August, dynamic models strongly favor a continuation of increased rainfall in the southwest monsoon regions, with heavy rainfall extending eastward across the Southern Plains and lower Mississippi Valley. Some model solutions show copious rain spreading over parts of Texas.

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This short- and intermediate-term rainfall would result in widespread drought relief stretching from the Four Corners through Texas and Oklahoma and the lower Mississippi River Valley. Drought conditions are also favored to continue to improve in the Southeast.

In contrast, unless there is a clear wet signal over the next few months, where runoff remains extremely low and drought conditions persist for an unusually long period, drought conditions are unlikely to improve significantly in the Northeast. While storm systems are likely to bring some soil moisture to the Northeast early in the season, given forecasts for above-normal temperatures, drought conditions may continue to worsen in the near term.

Drought duration is favored for the west ahead of the core rainy season, and a fairly dry September and SON outlook favors drought duration for the north-central CONUS and Great Lakes region, with drought development in parts of the northeast Montana and western North Dakota is possible.

Forecast confidence is moderate to high for the western and southern regions.

  • Drought conditions remain widespread in the western and southern climate regions of the CONUS, with just over 70 percent of the western region and over 77 percent of the southern region experiencing moderate drought or worse as of August 11, 2022 USDM.
  • The southwest monsoon was very active this summer, resulting in a reduction in drought in parts of the California desert, Great Basin, and Four Corners states. As is usual during the monsoon, the heaviest convection thunderstorms led to flash floods, while other regions have so far been largely spared from precipitation.
  • Farther east a tropical disturbance (98L) brought drought relief to South Texas.
  • In contrast, abnormal dryness along with periods of extreme heat in the southern plains, resulted in a widespread extension and intensification of drought, with parts of central Oklahoma experiencing a 3-class deterioration in USDM plots over the past 4 weeks.
  • There was a seasonal drought over the rest of California, resulting in a small change in drought representation, while some rain spells brought relief in central Washington and the Oregon Cascades.
  • In the next two weeks Forecasts from the WPC and CPC indicate a continued active monsoon pattern, with widespread rainfall extending eastward across the south-central CONUS. Recent runs of the ECMWF indicate a potential for widespread heavy to excessive precipitation in north or central Texas, with the WPC’s latest 7-day QPF forecast showing a swath of 5 to 7 inches of precipitation in north Texas and south Oklahoma.
  • Beyond the last weeks of August The September CPC outlook favors equal odds (EC) for below, near, and above mean rainfall in the southern Four Corners region, Texas, and Oklahoma, with slightly favoring above mean rainfall for southern Arizona and Louisiana.
  • The SON season outlook shows a slightly drier solution, but precipitation climatology in these regions is heavier early in the period and decreases markedly by late November. Hence, from widespread wetness favored in the short and mid-range, widespread drought reduction is favored in Arizona, New Mexico, southern Utah, and Colorado, and eastward throughout the southern region.
  • Despite widespread drought conditions Currently, local flooding is possible in areas with the heaviest rainfall.

Forecast confidence for the High Plains and Midwest regions is moderate.

  • While convective systems brought localized relief In parts of central South Dakota and Nebraska, drought conditions generally worsened throughout the High Plains region, with frequent heat waves and droughts, with the greatest drought impacts being seen in Kansas, Nebraska, and northeastern Colorado.
  • Farther east, after a rapid onset of drought In much of the corn belt, increased rainfall last month led to widespread improvements, although nearly 40 percent of Missouri and Iowa are still experiencing moderate drought or worse, according to the Aug. 11 USDM.
  • Farther east periods of extreme rainfall has brought historic flooding to mountain communities in eastern Kentucky while pockets of moderate drought persist in parts of the Great Lakes region.
  • Climatological precipitation decreases rapidly in the fall months across the Plains and Midwest, limiting the potential for significant drought relief, although falling evapotranspiration rates also reduce the potential for the drought to spread further.
  • Over the next 7 days widespread precipitation preference is given to encroaching on the northern Mississippi Valley, which may provide spot drought relief and halt further deterioration.
  • Drier conditions are preferred for the week 2 period, and both the September and SON CPC outlooks favor below-average precipitation and EC to above-normal temperatures in the northern plains and upper Midwest. Thus, drought duration is favored in nearly all regions of the High Plains and Midwest, with possible niches of development in already unusually dry parts of the Northern Plains.
  • Drought improvements are possible along the southern extent of these regions due to a near-term potential for heavy rainfall, as discussed above in relation to the southern region.

Forecast confidence is high for most of the southeastern region and moderate for Florida.

  • Flash drought conditions were also common throughout the Southeast in early summer, but a return to a more widespread convection regime eliminated most drought conditions across the region. As of August 11 USDM, less than 2 percent of the southern region was experiencing moderate drought, with small areas remaining in the state of South Carolina and eastern North Carolina.
  • in the next 7 days, The WPC QPF forecast shows an ongoing pattern of generous rainfall, with the heaviest amounts (1.5 to 4 inches) concentrated in the Piedmont and coastal Carolinas.
  • The CPC 8-14 days ERF is slightly favoured above average rainfall and the September outlook favors above average rainfall along the Gulf Coast and along the Georgia-Florida border. Increased chances of above-average precipitation shift to Florida Peninsula in SON outlook.
  • Based on these forecasts The elimination of the small remaining areas of drought is likely and no further development of drought will be favored.
  • Uncertainty is growing across the Florida Peninsula where a somewhat lackluster convection regime of sea breezes combined with periods of abnormal heat has resulted in reduced currents.
  • With the peak of the Atlantic hurricane season With a few months of wet season still to come, there are ample opportunities to increase humidity throughout Florida. However, should no tropical systems affect the state by the end of November, the region will be vulnerable to drought developments in the coming dry season beyond this forecast period.

Forecast confidence for the north-eastern region is low.

  • Gradual drought in spring accelerated into the development of an unusually intractable drought over much of the Northeast, with the greatest impact (D3, severe drought) in eastern Massachusetts and parts of Rhode Island.
  • More rain brought some relief to northern and western Maine in recent weeks, but precipitation events continue to miss coastal areas of the northern mid-Atlantic region and southern New England.
  • Streamflow values ​​are extremely low (less than 10 percent) in much of southern New England, and water tables have begun to drop.
  • The fall months are usually a great opportunity for recharging soil moisture in the NE as a south-shifting mean storm track maintains a generous precipitation climatology and ET rates decrease when trees are dormant.
  • Short term, The increasing impact on parts of central Pennsylvania, New York state and New Jersey may result in the drought spreading further, but the WPC-QPF forecast has become wetter, with the most recent outlook a widely held 0.5 to 1.5 inches could bring rain across the region, which could be enough to stave off widespread deterioration.
  • The CPC-ERF forecast favors slightly above-average precipitation, while monthly and seasonal CPC prospects favor EC for precipitation and above-average temperatures.
  • Despite the potential for seasonal moisture loading, The severity of the current impact and the potential for further near-term deterioration make significant improvements less likely in the absence of a clear wet signal. Therefore, consistency is maintained across the region.

Forecast confidence is high for Alaska and moderate for Hawaii and Puerto Rico.

  • Drought conditions eased across Alaska after periods of increased precipitation and below-average temperatures. A rapidly decreasing sun angle and temperature climatology during SUN make droughts less likely to form. Therefore, a drought development is not expected in the forecast period.
  • Drought conditions continue to plague much of Hawaii, and increased trade winds associated with ongoing La Niña present little opportunity for significant relief. Therefore, drought persistence is favored until the end of November.
  • In contrast, drought improvement is the most likely outcome for Puerto Rico as the late summer rainy season and hurricane season approach.

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