The Rockies To The West Coast
Little precipitation fell from the Rockies westward to the Pacific Coast last week. Overall, there was little change in conditions except along the northern tier of states from Montana westward through Washington and Oregon. Continued dryness and exceptionally hot weather kept dryness and drought increasing most significantly across eastern Washington, central and northern Idaho, and western Montana.
The entire state of Washington is now covered by D0 conditions or worse, and D2 was pulled northward along the Oregon coastline, and expanded across a large part of central Idaho and adjacent Montana. These areas recorded generally 6 to 12 inches less precipitation than normal in the last 6 months, and less than half of normal amounts in the last 60 days.
In contrast, recent heavy precipitation in west New Mexico and adjacent northeast Arizona led to additional improvements in these areas despite the dry week.
Light to moderate rainfall, on the order of 0.5 to 1.5 inches, fell on most of the dry areas in the Plains, though little or no rain fell on dry areas from northern Kansas into southeastern New Mexico.
A second week of significant rainfall led to reductions in the extent of D0 and D1 conditions in southeastern South Dakota and adjacent Nebraska, and there was further reduction in the D0 area still lingering in central Texas. Otherwise, conditions remained essentially as they were last week.
Midwest and Great Lakes Region
Light to moderate precipitation fell on the dry areas along and northwest of the Great Lakes Region, and across parts of the southeastern Great Lakes region. No tangible change in dryness severity was noted in Wisconsin and Minnesota, but in combination with moderate to heavy rains over the past few weeks, D0 was removed from part of south-central Michigan, where 3- to 6-month precipitation totals are now near to above normal.
Ohio Valley and East-Central States
The remnants of Tropical Storm Bill, in concert with a frontal boundary, brought copious amounts of rain to the Ohio Valley. Many locations from the Mississippi and Ohio Rivers’ confluence to the central Appalachians received 2 to 6 inches of rain, resulting in widespread dryness and drought relief.
Some locations across southern Ohio improved by 2 classifications from D1. Moderate rain brought improvement as far south as central Kentucky, western West Virginia, and south-central Virginia.
South of the stripe of heavy rain from Tropical Storm Bill’s remnants, rain resulted primarily from hit-and-miss thunderstorms. There were areas of moderate rain and isolated locations with heavy amounts, but most areas reported less than a normal week’s worth of precipitation, and hotter-than-normal conditions exacerbated dryness. Overall, despite some small areas of improvement, dryness and drought either persisted or worsened.
Some notable changes – all based on 30- to 90-day rainfall, streamflow reports, and soil moisture – included the introduction of D2 conditions in some areas near the Georgia/Florida border, D2 expansion northward along the southeast Florida coast, D1 development in western North Carolina and central South Carolina, D0 expansion through a large part of the southern Appalachians and northern Alabama.
Several areas in central South Carolina, southern Georgia, and northern and southeastern sections of Florida received 3 to 6 inches less rain than normal in the last 90 days.
Between 1 and 3 inches of precipitation fell on parts of the Northeast, leading to improved conditions in south and east Pennsylvania, New Jersey northwestern New York, parts of northern and eastern Maine, and northeast Massachusetts. In other areas, precipitation was not enough to substantially effect D0 to D1 conditions.
Hawaii, Alaska, and Puerto Rico
A few tenths of an inch of precipitation fell on east-central Alaska and part of the Kenai Peninsula, but little if any fell elsewhere. Recent dryness, exacerbated by above-normal temperatures, has led to increasing impacts of streamflows and high to extreme fire danger in large parts of the state. As a result, D0 was expanded to cover most of the state outside the northern and western tiers, and D1 conditions were assessed in parts of both east-central and south-central Alaska, where precipitation shortfalls date back as far as late 2014.
Leeward sections of Hawaii again recorded below-normal precipitation, and surface moisture continued to decrease, reportedly impacting some agricultural operations. As a result, extreme drought has been introduced in parts of both Maui and Kauai.
Light to isolated moderate rainfall totals reported across Puerto Rico were insufficient to bring any significant improvement to the areas of dryness and drought in Puerto Rico, and assessments were unchanged from last week. D2 continues to afflict interior sections of eastern Puerto Rico, where most streamflow measurements were among the lowest 5 percent ever recorded during this time of year.
For the upcoming 5-day period (June 25-29), hot and dry weather should prevail west of the Rockies’ front range, except in parts of the desert Southwest. Little if any precipitation is expected, and daily high temperatures from Utah and Nevada northward through the northern Rockies and Intermountain West will average 9 to 18 degrees F above normal, with even higher departures possible along the east side of the Cascades.
Near normal temperatures and light to moderate precipitation are forecast for the Plains and southeastern Rockies, with over an inch of possible in the higher elevations of south-central Colorado and adjacent New Mexico. Light to moderate rain is also expected across the Great Lakes and northern New England, along with cooler than normal temperatures (daily highs should average 3 to 6 degrees F below normal).
Moderate to heavy rainfall, generally exceeding an inch, is expected from the Midwest, Ohio Valley, and lower Northeast southward through the Gulf Coast and Florida. Over an inch of rain is anticipated everywhere except parts of Florida, with 2 to 5 inches potentially falling on the Ohio Valley, central to northern Appalachians, and mid-Atlantic region.
For the ensuing 5-day period (June 30 – July 4), continued above normal temperatures are favored in most of the West and across the Gulf Coast and southern Atlantic regions, including Florida. Meanwhile, the odds favor anomalously cool weather from the Plains eastward through the upper Southeast, Ohio Valley, Great Lakes, and interior portions of the mid-Atlantic and Northeast.
Drier than normal conditions are favored across Florida and in a swath from the northern Plains to the Pacific Northwest. Enhanced chances for above-normal precipitation cover a large part of the rest of the contiguous 48 states, excepting California, the central Gulf Coast, and in a stripe from the northern Intermountain West eastward through the Dakotas and Minnesota, south of the area where subnormal precipitation is favored.
Warm weather is anticipated over most of Alaska, with enhanced chances for above normal precipitation identified outside the Panhandle and east-central parts of the state.