Drought Monitor Weekly: Mostly Hit or Miss Rains

Summary

Precipitation was hit-or-miss this week for many locations east of the Great Plains. Much of the Midwest, South, and Southeast saw combinations of D0 additions and removals based on 7-day rainfall accumulations. Most areas with D0 removal observed at least 2-3 inches of rainfall.

Some short-term dryness crept into southern Georgia (isolated 2-4 inch 30-day deficits) and the Florida Gulf Coast (widespread 2-4 inch deficits over the last 14 days). The Mid-Atlantic coast saw some D0 expansion near the Delmarva Peninsula.

Portions of New England saw more than 3 inches of rainfall, drastically reducing 30- and 60-day deficits and warranting some D1 removal. However, USGS 7-day average stream flows remain below normal for much of the Northeast.

The High Plains and northern Rockies also received some beneficial rainfall. Many locations in Idaho saw 1-category improvements (D1 to D0 and D0 removal), but much of the northern High Plains Region did not receive enough rainfall for much improvement.

Some degradation from D3 to D4 occurred in southeastern Colorado and southwestern Kansas in areas where little or no precipitation fell and temperatures averaged above normal for the week.

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The wildfire risk remains high for many locations that remain in drought, particularly in the West.

Southeast

Despite precipitation surpluses beyond 90 days, short-term dryness (30-60 days) remains the concern for many locations across the Southeast. This region again experienced a combination of D0 addition and removal, depending on where the heaviest precipitation fell.

Parts of southeastern Alabama and southern Georgia have also experienced below normal precipitation over the last 30-60 day periods, as some stations are reporting D0, D1, and D2 SPIs for those periods. USGS 7-day average stream flows remain near and above normal for all of Georgia, so this week is status quo for much of the state.

The exception being southwestern Georgia, where an area of D0 was introduced in southeastern Alabama and along the AL/GA border, where the area has received 25-50 percent of normal precipitation in the last 30 days, stream flows have fallen below normal (10th to 24th percentile), and soil moisture continues to decline.

Many locations along Florida’s Gulf Coast saw a very dry last two weeks in June, with much of the coast experiencing 2-4 inch 14-day deficits. Scattered showers this week did little to help and USGS stream flows are mostly near normal, with the exception of the Tampa Bay area.

30-day SPIs are generally positive also, so no D0 introduction this week. However, the Florida Gulf Coast will need to be monitored closely in the coming weeks if the short-term dryness continues.

South

In the Southern Region, the story remains the short-term (30-60 day) dryness. Western Tennessee has missed out in recent weeks on the heaviest precipitation, warranting some D0 expansion (2-3 inch deficits going back 90 days).

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Northwestern Arkansas and northeastern Oklahoma saw D0 and D1 expansion, as little to no rain fell and most of these areas have received only 10-25 percent of normal precipitation in the last 30 days. 7 inch rainfall deficits in the last 60 days have been observed near Tulsa and Creek Counties in Oklahoma, warranting the addition of a small area of D2. USGS 7-day stream flows are also below normal (10th-24th percentile) for areas around Tulsa County, OK.

In western areas of Texas and Oklahoma, heat, low humidity, and lack of rainfall continue to exacerbate existing drought conditions, leading to some D1, D2 and D3 expansion. Widespread D2-D4 SPIs over several time periods for many of these locations.

Midwest

The Midwest saw widespread precipitation where some locations received 3-6 inches of rain. D0 removal from much of the lower Ohio River Valley. The Corn Belt saw both expansion and reduction of D0, depending on where 7-day totals were below and above normal, respectively, adding to 1.5-3 inch 30-day deficits.

The Arrowhead of Minnesota and northern Wisconsin saw D0 and D1 expansion, in favor of 3-5 inch 60-day departures, D3-D4 SPIs over several time periods, and much below normal (below the 10th percentile) USGS average 7-day stream flows.

High Plains

Above normal temperatures, low humidity, high winds, and below normal precipitation in recent weeks has led to continued degradation in southeastern Colorado and southwestern Kansas. Although some isolated convection occurred in southeastern Colorado, in areas that did not see precipitation and that continued to see above normal temperatures this week, D4 was introduced, which expanded into southwestern Kansas.

However, some D0 and D2 reduction was warranted in western Kansas, as 7-day rainfall accumulations of more than 1.5 inches eliminated 30-day departures for several locations.

Some areas of Nebraska saw expansion of existing D0 coverage, where 30-day dryness continues. There are concerns of potential flash drought in eastern Nebraska, where 30-day SPIs of D2 or greater are being reported.

The northern High Plains saw enough rainfall this week (1.5-3 inches) to warrant D1 reduction in northwestern South Dakota and southwestern North Dakota. The remainder of the region was generally status quo.

West

The Western Region is mainly status quo, except for the northern Rockies and Pacific Northwest, where an active storm track. Idaho benefited the most, with several locations seeing 1-category improvements, particularly western Idaho, which received 0.5-1.5 inches of rainfall.

Light showers in eastern Washington and northeastern Oregon led to slight reduction of D0 and D1 coverages.

Soil moisture is below the 10th percentile in many areas across the Great Basin and northern California. USGS 7-day average stream flows also continue to be below to much below normal this week for much of the Four Corners Region, the Great Basin, and northern California.

Northeast

Parts of New England received more than 3 inches of rainfall this week. Some locations in western Maine, eastern New Hampshire, and eastern Massachusetts had 30-day deficits reduced to around an inch, warranting an upgrade from D1 to D0 over western Maine.

Precipitation deficits were totally removed near Norfolk, MA (7-day precipitation totals greater than 3 inches), leading to D0 removal. However, greater than 1.5 inch 60-day precipitation deficits remained for much of eastern Maine and USGS 7-day average stream flows remain below to much below normal (below the 24th percentile).

In eastern Maine, despite light rainfall, D1 was expanded over Penobscot, Hancock, and Piscataquis Counties, in favor of D3-D4 SPIs at 30 and 60 days. D1 was also added near Jefferson County, NY, in support of a D3 60-day SPI nearby and 3-4 inch 60-day rainfall deficits.

D0 was expanded across northern and southern New Jersey and the Delmarva Peninsula as 30-60 day precipitation deficits continue to mount. Many of the new D0 areas have seen 25-50 percent of normal precipitation over the last 60 days, diminishing to 10-25 percent of normal for several locations in the last 30 days.

In addition, USGS 7-day average stream flows are below normal (10th-24th percentile) for D0 areas on the Delmarva and much below normal (less than the 10th percentile) for southern and northern New Jersey.

Alaska, Hawaii, and Puerto Rico

In Alaska, rainfall has been near and above normal for many locations across the state going back 7-14 days, warranting status quo this week.

Hawaii remained dry again this week, with most locations seeing below normal precipitation for the 7-day period. Several stations in Oahu reported negative precipitation departures of more than 0.5 inches while northern portions of Maui also saw slight negative precipitation anomalies.

As such, D1 was expanded eastward in Oahu to encompass locations seeing the greatest negative departures, and D0 was expanded to cover the remainder of the island. D0 was also expanded in Maui, in favor of slightly negative 30-day SPIs, below normal precipitation, and above normal temperatures this week.

D0-D2 reductions were made in western Puerto Rico, with several locations receiving 2-5 inches of rainfall this week. Many D2 locations along the southern coast of the have seen YTD deficits of 2-5 inches, with pockets of 5-10 inch deficits.

Much of the eastern third of the island is seeing 25-50 percent of normal precipitation going back 90 days and USGS 7-day average stream flows are below the 10th percentile for much of the region. It was reported that the San Juan metro area will be implementing water rationing measures to cope with moderate and severe drought conditions in surrounding areas.

Looking Ahead

During the next 5 days (July 2-6), WPC’s QPF showed increased probabilities for precipitation across many of the northern tier states, much of the Mississippi Valley, and Southeast, where many areas are favored to receive up to and exceeding 1 inch of precipitation.

The Northern High Plains and the Middle Mississippi Valley are expected to see some of the heaviest rainfall (2-4 inches in some cases). Probabilities drop off quite a bit for many locations just east of the Rockies, where below normal precipitation, high winds, low relative humidity, and above normal temperatures continue to be the driving factors for maintenance and exacerbation of drought conditions.

Luckily, temperature anomalies are favored to be near to slightly above normal for much of the next week over the western Plains. Much of the Great Lakes is also favored to miss out on some beneficial rainfall in the upcoming week, in addition to positive temperature anomalies of 8-10 °F.

The Climate Prediction Center’s 6-10 day outlook (July 7-11) shows an amplified pattern with a mean ridge over the central CONUS, and troughing over the West Coast and over the eastern CONUS. Enhanced probabilities of below normal temperatures are favored along the West Coast and interior Pacific Northwest, in association with a mean mid-level trough over the West.

Above normal temperatures and below normal precipitation are favored in much of the central CONUS, with probabilities for above normal temperatures extending to the Great Lakes and Northeast, underneath a mean ridge. The active storm track is favored to continue for the northern tier states, with elevated odds for above normal precipitation centered over the Upper Midwest and Great Plains.




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