NOAA drought outlook

News
Oct 5, 2012
by WLJ

At the beginning of October, a widespread area of moderate to heavy rainfall (locally more than 5 inches) resulted in a 1-category improvement to drought categories across northern Georgia and northeast Alabama.

Although October and November are a relatively dry time of year for the Southeast, the Climate Prediction Center (CPC) outlook calls for enhanced odds for above median precipitation for eastern Alabama and Georgia. Therefore, some improvement is forecast for this region but long-term precipitation deficits are not expected to be eliminated.

The forecast confidence for the Southeast is moderate.

Frequent rainfall during the past month led to improvement across the mid- Atlantic and western New York. The 6-10/8-14 day outlooks on Oct. 3 along with updated October precipitation outlook call for above median precipitation for these areas. Soil moisture currently ranks mostly above the 30th percentile. Since above rainfall is favored during the remainder of October, improvement can be expected for the small areas of ongoing drought across the mid-Atlantic and western New York.

The forecast confidence for the mid-Atlantic and western New York is high.

Due to an increase in rainfall since late August which began with the remnants of Isaac, significant amelioration of drought occurred across Arkansas, southeast Missouri, and the eastern Corn Belt. Soil moisture levels and stream flows have mostly recovered in these areas since mid-summer. The updated October precipitation outlook calls for a tilt towards above median precipitation across much of the Ohio Valley. Due to expected wetness during October and recent alleviation of drought since late August, improvement is forecast across the middle Mississippi and Ohio valleys.

The forecast confidence for the middle Mississippi Valley and Ohio Valley is moderate.

According to U.S. Data Management (USDM), extreme to exceptional drought covers nearly all of Oklahoma with varying drought intensity across Texas. A relatively dry climatology favors persistence across the Oklahoma Panhandle and the northwest Texas Panhandle. Prospects for improvement increase across the remainder of Oklahoma and north Texas where, climatologically, conditions do not become significantly drier during OND (October, November, December). Other factors that support some improvement or improvement across much of Oklahoma and Texas include: several inches of precipitation indicated by the 384-hour forecasts from the 0/6z gfs models, the 6-10/8-14 day outlooks from Oct. 3 favoring near to above median precipitation, and the CPC seasonal outlook for OND calling for enhanced odds of above median precipitation across central and south Texas.

Forecast confidence for Oklahoma and Texas is moderate.

During the past month, drought increased to cover nearly all of the northern Great Plains and upper Mississippi Valley with drought intensifying across the central Great Plains. According to USDM, most of Kansas, Nebraska, and southern South Dakota are designated in the extreme or exceptional drought category. A relatively dry climatology favors persistence across the northern/ central Great Plains and upper Mississippi Valley. However, some improvement is forecast in northeast North Dakota and extreme northern areas of Minnesota where 1 to 2.5 inches of precipitation are expected at the beginning of the outlook period.

The forecast confidence for the northern/central Great Plains and upper Mississippi Valley is high.

During September, drought expanded in Montana where dry weather was accompanied by unseasonably warm temperatures. A relatively dry climatology favors persistence across Montana. Although development remains forecast across Montana due to the dry initial conditions, some precipitation at the beginning of the outlook period reduces forecast confidence.

The forecast confidence for the northern Rockies is low.

During September, dry weather accompanied by unseasonably warm temperatures also affected the Pacific Northwest. As of Oct. 3, multiple large wildfires continue to burn across the Pacific Northwest. Since tools on all time scales indicate enhanced odds for below median precipitation, persistence or development is forecast for the Pacific Northwest and northern California. El Niño precipitation composites indicating below median precipitation across these areas are also considered.

The forecast confidence for the Pacific Northwest and northern California is moderate.

Persistence is forecast for the Southwest and central Rockies with precipitation associated with the monsoon ending. Since the 6-10/8-14 day outlooks from Oct. 3 favor near to above median precipitation across the Southwest and weak signals exist among the seasonal precipitation tools, forecast confidence is low for persistence. Climatology tends to be dry across southern Arizona during OND.

Forecast confidence for the Southwest and central Rockies is low.

In Hawaii, October through December will become progressively wetter.

However, the long-lead forecast indicates enhanced chances for below-normal rainfall. As a result, drought is expected to persist in existing areas and slowly expand into other parts of the state, much like the previous Drought Outlook. Still, the fact that the islands are getting climatologically wetter during the period does imply that the chances for drought-relieving rains improve later in the period, even if only based on climatology.

The forecast confidence for Hawaii is low. — NOAA

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