National Drought Monitor for July 1, 2014
Summary
During the past 7-days, a series of weak upper-level disturbances and frontal systems at the surface brought widespread precipitation to much of the contiguous United States, outside of the Southwest and California. Heavy rain (2”-4”, locally greater) fell across portions of the Upper Mississippi Valley, the northern Plains, the Pacific Northwest, the west-central Gulf Coast region, the general vicinity of the southern Appalachians, and the Northeast. A low pressure area off the East Coast of Florida was in the process of developing into a tropical depression, and would become Tropical Storm Arthur by the end of the period.
Alaska, Hawaii, and Puerto Rico
Moderate to heavy rain (0.5-3.0 inches, locally greater) fell across most of the D0 area in southeast Alaska, including the Panhandle. Most stream flows in this region are near to above-average. As a result, abnormal dryness was removed from the state. Preliminary reports suggest Anchorage may have its second wettest June on record. Ketchikan measured a record 5.45 inches of rain on June 22nd, breaking the previous record for that date of 1.74 inches set back in 1956. Juneau International Airport reported 7.46 inches of rain for the month of June, while normal rainfall for June is 3.24 inches. The previous June record was 6.69 inches, set in 2012. In Hawaii, the only alteration made to the depiction was to slightly resize and reposition the D0 area on the Big Island, based on observed rainfall data, the Vegetation Health Index (VHI), and ground reports from the Farm Service Agency (of the U.S. Department of Agriculture). No modifications were made to the drought depiction this week in Puerto Rico.
Mississippi Valley
A one-category upgrade was rendered to the drought depiction in Iowa, Illinois, and Louisiana, due to plentiful (and in some cases excessive) rainfall. At least 10 inches of rain was reported in Lake Charles in southwest Louisiana, while recent dryness is beginning to show up in northwest Louisiana. In northwest Illinois, four key stations in Mercer County reported between 4.64 and 5.70 inches of rain for the month of June. AHPS DNPs through 180-days indicate that (in a statistical sense) Mercer County is near the southern edge of a very persistent band of above-average rainfall. All that remains of the drought in Iowa are two small areas of D0, one in the southeast corner of the state, and one in the southwest corner.
Northeast and mid-Atlantic
Though moderate to heavy rain (greater than 0.5”) fell across much of the region, it largely missed southeastern New England and the south-central Delmarva Peninsula, where the Percent of Normal Precipitation (PNP) is generally between 25-50 percent over the last 30-days (AHPS), and stream flows are in the lowest quartile of the historical distribution. Accordingly, abnormal dryness (D0) was expanded across southern and eastern portions of New England, and D0 was introduced to the south-central Delmarva Peninsula. These areas will need to be reassessed next week, once Tropical Storm (projected to be hurricane) Arthur moves through the region.
Ohio/Tennessee Valley
Moderate rain (0.5-2.0 inches) fell over Kentucky and Tennessee during the past 7-days. Stream flows are generally near-average in Kentucky, and above-average in Tennessee. One-category improvements were warranted in central and eastern sections of Kentucky, except where 30-day and 60-day precipitation deficits favored the retention of D0 conditions.
Southeast
Moderate precipitation (0.5-2.0 inches, locally heavier) was observed over northern Alabama and northern Georgia during the past week. Stream flows are running near to above-average in these areas, including that of the Paint Rock River in northeast Alabama. Accordingly, abnormal dryness was removed from northwest Georgia and northeast Alabama. In contrast, in east-northeast Georgia in the vicinity of the Savannah River, D0 was expanded approximately one county northwestward. The 30-day and 60-day Departure from Normal Precipitation (DNP) in this last region lend some support to this expansion. The North Carolina drought depiction has not been altered this week, but will be reassessed next week after the expected passages of both an active cold front and Tropical Storm Arthur (as of the 2pm update from the National Hurricane Center on July 2nd).
Southern and Central Plains
Two to four inch rains fell over southern and central portions of Nebraska, prompting 1-category upgrades for these areas. In central and southern Kansas, 2-5 inch rains (locally heavier) warranted one-category improvements, especially in places which received two to three times their normal rainfall for the week. In Oklahoma, widespread one-category improvements were made in the northern portion of the state, due to very heavy rains during the past 30-days. For example, in the town of Buffalo, OK, 10.44 inches of rain fell during the past month, compared to the normal June rainfall of 4.08 inches. Flash flooding was also reported in Buffalo. On June 30th, the Oklahoma Panhandle experienced a very impressive dust storm. In the southeast portion of the state, minor degradations were rendered to the drought depiction. Texas had an unexpectedly wet week, with very heavy precipitation along the Gulf Coast (generally 3-5 inches, locally greater), and moderate to heavy precipitation (0.5-3.0 inches) in the interior East, supporting 1-category improvements. Relatively small alterations were made to the depiction in southern and far western Texas, both improvements and degradations.
Southwest and California
Little if any precipitation was observed in the Southwest during the past week. In western New Mexico, severe drought (D2) was downgraded to extreme drought (D3), and a general one-category degradation was rendered to the depiction in the southernmost counties of Luna, Dona Ana, and Otero. El Paso has received only 25 percent of its normal precipitation since January 1, 2014, making this the 7th driest year on record (so far) since 1879. High temperatures have been exacerbating drought-related impacts. Every day in June, El Paso was at or above normal, with a June departure of about +6.1 degrees F, making this the second warmest June on record, only behind June of 1994. In northeast Utah, most of the D2 area was downgraded to D3 conditions, while moderate rain (0.5-2.0 inches) supported a one-category improvement to parts of northeast Colorado. In southern Nevada, the continued lack of rain prompted the expansion of extreme drought (D3) conditions across parts of Nye, Lincoln, and Clark Counties, while in southern California, exceptional drought (D4) was expanded across Ventura, Los Angeles, and much of Orange Counties.
The Pacific Northwest
In the rain-shadow of the Oregon Cascades, conditions have continued to decline in the Klamath Valley area. One-category degradations (D2 to D3) were rendered to the drought depiction over south-central Oregon. This area is experiencing its worst drought in 20 years, and the first round of involuntary water shutoffs since 2001 has been implemented. In addition, the area of extreme drought (D3) in the southeast counties of Harney and Matheur has been connected with the adjacent D3 area in northwest Humboldt County in Nevada.
Looking Ahead
During July 3-7, 2014, most of the contiguous United States is expected to receive a half-inch or less of rain, though there are a few exceptions. Northern and central Florida, the Outer Banks of North Carolina, near the mid-Atlantic Coast, and the southern and eastern New England coasts may get 2-4 inches of rain, in part from what is currently Tropical Storm (projected to be hurricane) Arthur and from an active cold front approaching from the west. In the Middle Mississippi Valley, 0.5-1.0 inch of rain is forecast during this period, while 0.5-1.5 inches of rain is expected in association with the onset of the Southwest Monsoon across portions of Arizona, New Mexico and northern Texas. Temperatures during the period are anticipated to be mostly within 4 degrees of normal, though very brief departures of 8-10 degrees above normal are projected for the northern Plains region. For the ensuing 5-day period, July 8-12, 2014, there are enhanced odds of above-median rainfall in the east-central CONUS, the Great Lakes region, southern Florida, and the Southwest. Below-median precipitation is favored over the Pacific Northwest, the northern Rockies, and southwest Alaska. Mean temperatures for this period are favored to be above-normal over approximately the eastern and western thirds of the lower 48 states, and the southern half of Alaska, and near to below-normal temperatures are favored over the central third of the CONUS.
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