November 2014

Outlook Graphic: PNG   PDF 

Latest Monthly Assessment - During the past 14 days (since the SDO release on Oct. 16), above-normal precipitation in the lower 48 States was limited to the Northwest, New England, upper Great Lakes, and upper Rio Grande Valley. The remainder of the Nation observed subnormal precipitation and above normal temperatures, with only parts of the Southeast experiencing slightly below normal readings. Moderate to heavy rains fell on most of Hawaii from Tropical Storm Ana which passed to the west of the islands. Western Puerto Rico measured surplus rains, but eastern sections recorded subnormal amounts. ENSO neutral conditions remained in the equatorial Pacific Ocean, but an El Niño watch continued as El Niño is favored to begin in the next 1 to 2 months and last into the Northern Hemisphere spring 2015.

Precipitation normally peaks in the Pacific Northwest during the late fall and winter months, while California's main wet season usually occurs from the late fall into the early spring, with December-February most critical for receiving the bulk of their annual precipitation. In contrast, the Southwest, Plains, and Southeast are typically dry during November, but with lower temperatures and little to no evapotranspiration, this time of the year is ideal for soil moisture recharge before the ground freezes in the north. During early November, a storm system laden with tropical Pacific moisture should drop ample rains on most of the south-central Plains before tracking into the Ohio Valley and Northeast, while yet another system brings precipitation to the Pacific Northwest and northern Rockies. Meanwhile, a possible Nor'easter will remain just off the Atlantic Coast, although it may brush coastal New England with rain. This precipitation in the Northwest, south-central Plains, and New England should be enough for some improvement, with the western edge of improvement in Texas and Oklahoma highly dependent on storm totals and November normals (that rapidly decrease from east to west). By mid-month, the odds favor above-median precipitation across the northern third of the U.S. and in Florida, with subnormal precipitation in California and the Southwest. Temperatures are likely to be above-normal in the western and northern U.S. Although the updated November precipitation outlook favors above-median amounts in Arizona, New Mexico, and western Texas, November normal are quite low and much of the remaining drought is long-term (hydrological)- requiring large amounts of precipitation - which is not likely during November, hence persistence was shown. In California and the Great Basin, persistence is expected with the normal wet season still about a month away, and dry and warm conditions forecast during the first half of November. In the Southeast, the forecasts over various time frames showed uncertainty as to possible wetness (improvement) or dryness (development), hence persistence was depicted.

In Hawaii, widespread moderate to heavy rains from Tropical Storm Ana provided some drought relief, but expected drier conditions and the onset of the normal dry season should keep existing D1 areas as is. In Puerto Rico, the late summer and fall months are typically wet, and although October was dry in eastern sections, November outlooks tilt toward near-normal rainfall, not enough to erase D1 but enough to prevent deterioration, hence status-quo conditions.

Tools used in the U.S. Monthly Drought Outlook (MDO) included the official Climate Prediction Center (CPC) updated temperature and precipitation outlooks for November 2014, various short- and medium-range forecasts and models such as the 5-day and 7-day precipitation totals from the Weather Prediction Center, the 6-10 day and 8-14 day CPC forecasts, the NAEFS precipitation outlooks, the soil moisture tools based on the Constructed Analog on Soil (CAS) moisture, dynamical models (CFSv2, NMME, IMME, and IRI), the 384-hour total precipitation forecasts from several runs of the GFS, climatology, the latest official Drought Monitor analysis, observed precipitation during the last few weeks, and initial conditions.

A late October Nor'easter brought widespread soaking rainfall (0.5 to over 4 inches) to New England, boosting moisture across Massachusetts, Vermont, New Hampshire, and Maine. Smaller accumulations were observed across southern New England, where moderate drought (D1) conditions persist across parts of southern New York, southeastern Connecticut, and Rhode Island. Significantly reduced evapotranspiration due to the end of the growing season and cooler temperatures makes November an ideal month for soil moisture recharge across the Northeastern States before the ground freezes during the winter. Therefore, any precipitation that falls during the month has the potential to efficiently reduce lingering drought conditions. During the upcoming week, an area of low pressure is forecast to deepen rapidly off of the mid-Atlantic coast and lift northward. Although the majority of the rainfall is anticipated to remain offshore, the WPC 7-day outlook indicates accumulations of 0.5 inches or more across coastal New England, with lighter amounts further inland. Both the CPC 6-10 and 8-14 day outlooks tilt the odds towards above median precipitation across the northeastern U.S., while the revised November monthly outlook maintains equal chances for near, above, and below median precipitation. Based on recent rainfall and an anticipated wet signal during the first half of November, drought removal is forecast for the D1 areas of southern New England and New York.
Forecast confidence for the Northeast is moderate.

Below normal rainfall across the southeastern Atlantic coastal Plain and adjacent Piedmont resulted in an expansion of abnormal dryness (D0) across parts of the Florida Panhandle, Georgia, and the Carolinas during the past week. D0 conditions also expanded westward across parts of Mississippi, while moderate to severe drought conditions persisted across central Alabama, southwestern Georgia, and northern Florida. November is a relatively dry time of year across the Southeast, particularly along the Atlantic coastal Plain, dry weather during this period typically aids fieldwork activities, while cooler temperatures reduce the evapotranspiration rates. Therefore, drought expansion tends to slow during November, while periods of rainfall can be effective in ameliorating existing drought conditions. Scattered showers fell across Alabama, Georgia, and the coastal Carolinas late in the week. The WPC 7-day precipitation outlook forecasts light precipitation across the Southeast, while the CPC 6-10 day outlook tilts the odds towards above median rainfall. The revised November monthly outlook tilts the odds towards above median precipitation for the central Gulf Coast primarily west of the drought areas, while maintaining no signal for the remainder of the Southeast. Based on the seasonably dry climatology and lack of a strong signal favoring enhanced rainfall, drought persistence is maintained across central Alabama, southern Georgia and northern Florida.
Forecast confidence for the Southeast is moderate.

Although near average precipitation early in the month brought localized relief across parts of the central and southern Plains, below normal rainfall and unseasonable warmth during late October promoted drought persistence and expansion across eastern Texas and southeastern Oklahoma, where rainfall deficits exceeded 1 inch during the last week of the month. Much of Texas and Oklahoma remain entrenched in long-term and significant drought conditions. During November, there is a tight gradient in climatological precipitation, with dryness increasing towards the west across Kansas, Oklahoma, and Texas. The WPC forecasts widespread, soaking rains exceeding two inches across much of the core drought regions of Texas and Oklahoma for the upcoming week. These rains may be augmented by the remnants of Tropical Storm Vance, which is forecast to attain hurricane intensity over the eastern Pacific before making landfall along the western coast of Mexico. The CPC 6-10 day outlook favors enhanced rainfall across eastern Texas and Oklahoma, and the updated November monthly outlook also tilts the odds towards above median precipitation for the southern Plains. These forecasts indicate a potential for widespread short term drought amelioration during November; however, the potential for improvements to the more entrenched long term drought conditions across central Texas and the extreme to exceptional drought across northern Texas and central Oklahoma, is more uncertain. Therefore, an area of drought improvement and removal of moderate (D1) drought is indicated for the southeastern Plains, including parts of eastern and central Texas and eastern and central Oklahoma. Drought persistence is maintained for west-central and western Texas, as well as western Oklahoma, where climatological precipitation is low and long-drought is more entrenched.
Forecast confidence for the central and southern Plains is moderate to high.

Below normal precipitation during the previous two months promoted the expansion of abnormal dryness (D0) across Minnesota and the Dakotas, while a small area of moderate drought (D1) developed over northeastern South Dakota. November is a climatologically dry time of year for the northern Plains and upper Midwest, and seasonably cold temperatures keep evapotranspiration rates very low. Therefore, drought conditions tend to develop slowly during the Fall, while bouts of precipitation can boost soil moisture efficiently before the winter freeze. Mostly dry weather is anticipated during the first week of November. While the CPC 6-10 and 8-14 day outlooks tilt the odds towards above median precipitation along the northern tier of the CONUS, the updated November outlook maintains equal chances for below, near, or above median precipitation. Based on the cool and dry climatology and a potential for above average precipitation near the middle of the month, no further drought expansion is anticipated for the northern Plains or upper Midwest. Drought persistence is maintained for the D1 area in northeastern South Dakota, however, due to the low climatology.
Forecast confidence for the northern Plains and upper Midwest is moderate to high.

Climatological precipitation begins to increase across California from north to south during November, but the primary wet season for the State begins during December. November is a climatologically dry time of year for the Great Basin and interior Southwest as the monsoon season is over. During the past month, seasonably dry weather was observed over central and southern California and Nevada, while late monsoon rains fell across parts of southern Arizona and New Mexico. Outside of small improvements across western New Mexico, drought conditions remained largely unchanged across the Southwest during the past four weeks. In contrast, widespread heavy precipitation fell across northwestern California and the southern Cascades, which may result in some short-term improvements. During the upcoming week, a series of storms impacting the Northwest is anticipated to bring precipitation to coastal areas of northern California and across the Cascades and northern Sierras. Although these rains would be welcome, it is unlikely that they will be robust enough to provide significant early relief to the entrenched, multi-year drought. Additionally, the CPC 8-14 day outlook indicates a pattern shift towards drier weather across California. The revised monthly outlook indicates no signal for wet or dry during November. Therefore, based on climatology, where the bulk of California's winter precipitation falls after November and the interior Southwest is dry, as well as the significantly dry initial conditions, drought persistence is forecast for all of California and the rest of the Southwest.
Forecast confidence for the Southwest and California is high.

Widespread heavy precipitation from multiple systems since mid-September yielded above average rainfall to coastal regions of Oregon and Washington and boosted moisture across the Cascades ranges. The favorable pattern brought relief to abnormal dryness and drought conditions across northwestern Oregon and northwestern Washington. In contrast, drier conditions east of the Cascades resulted in degradation for northeastern Oregon. Climatological precipitation increases markedly during November across the Northwest, and the early storms have resulted in a wet start to the rainy winter season. Additional heavy precipitation is forecast during the upcoming week across coastal areas and the Cascades, with moisture anticipated to increase across the northern Rockies of Idaho and Montana as well. Much less precipitation is forecast over eastern Washington and Oregon, however, due to the rain shadow effects of the mountain ranges, and most of the remaining core drought areas are in this rain shadow region. Therefore, improvement is anticipated across the drought areas of the Cascades, while persistence is maintained further east.
Forecast confidence for the Northwest is moderate to high.

Hurricane Ana passed just south and west of the Hawaiian Islands during mid to late October, bringing abundant moisture. Reservoir deficits remain in some locations, however, so moderate hydrological drought areas across Molokai and Maui persisted through the end of the month. The CFS model indicates that some moisture along an active ITCZ south of Hawaii may propagate northward and affect the islands early in the month; however, it is unlikely that sufficient rainfall will fall during November to reduce long term drought conditions before the winter rainy season.
Forecast confidence for Hawaii is moderate.

Scattered thunderstorms fell across western Puerto Rico during the past week, but eastern sections saw subnormal October rainfall, increasing the abnormal dryness there. November is climatologically wet across Puerto Rico, and a return to suppressed convective conditions across the Caribbean could result in drought degradation. Both the CFS and ECMWF indicate enhanced rainfall for Puerto Rico during early October. While the CFS trends slightly drier during mid-October, the ECMWF maintains a wet signal during Week-2. Both models have little signal during the end of the month. Based on a lack of a dry signal in the tools, no further drought development is anticipated, but sufficient rainfall to significantly improve drought is likewise not anticipated.
Forecast confidence for Puerto Rico is moderate.

There is no drought indicated or anticipated to develop across Alaska during November.