U.S. Drought Monitor Report for the Week Ending May 7 (Text)

Following is the text of the weekly U.S. Drought Monitor as released by the National Drought Mitigation Center in Lincoln, Nebraska:

Weather Summary: Due to blocking high pressure over the
northwestern Atlantic Ocean, a weather system in the Nation’s
mid-section stalled and temporarily retrograded westward,
dropping widespread moderate to heavy rains on the Mississippi
and Tennessee Valleys, Southeast, and Florida. With the addition
of a deep southward push of sub-freezing air into the central
U.S., accumulating record-late May snows fell as far south as
northwestern Arkansas and northeastern Oklahoma. Unfortunately,
the moisture bypassed much of the West and southern Plains, and
was blocked by the strong high pressure from entering the
Northeast. As the period ended, however, enough moisture from an
upper-air low off the southern California coast raised humidity
levels, lowered winds, and generated widely-scattered showers in
the West which aided firefighters battling the huge wild fire in
the southern California coastal mountains. Farther east, the
slow-moving storm was creeping northeastward into the mid-
Atlantic. Most of the lower 48 States and Alaska recorded
subnormal weekly temperatures, especially the Plains, with
unseasonable warmth confined to the West, Southwest, eastern
Great Lakes region, Ohio Valley, and New England.

New England and mid-Atlantic: Strong high pressure off the
Northeast coast kept much of the region precipitation free until
after the cut off period (12Z Tuesday), further increasing
short-term shortages. With many areas receiving less than half
of normal precipitation at 30 and 60 days, and under 70 percent
at 90 days, deficits at 30, 60, and 90 days rose to between 2
and 4, 3 and 6, and 4 to 7 inches, respectively. Accordingly, D0
was expanded northward and southward, now stretching from
central Maine southward into southern West Virginia. In
addition, where the deficits were the greatest at 90 days
(northern West Virginia and south-central new England), and
where the average USGS stream flows at 1, 7, and 14 days were
below the tenth percentile (many at record lows on May 6), D1
was added. Fortunately, this is a time of year when stream flows
can respond quickly to a good soaking. With southern New England
still only one-third to one-half through green-up, the impacts
of dry weather were not as obvious as they would be later in the
spring. The dry weather, however, has elevated fire weather
conditions in the interior.

Southeast: Moderate to heavy rains fell on most of the remaining
D0 to D2 areas in the Southeast, prompting additional
improvements in the Carolinas, Georgia, southern Alabama, and
Florida. In the Carolinas, the slow-moving storm dropped 1 to 2
inches of rain on the western areas of the D0, enough to reduce
short and medium term deficits and remove abnormal dryness
there. Locations in the eastern D0 area, however, measured under
0.5 inch, and D0 remained. In Georgia, 1.5 to 2 inches of rain
near Augusta was enough to eliminate lingering long-term
shortages, while heavier rains (2.5 to 6 inches) along the
eastern coast eliminated the D1 and most of the D0. Glynn and
McIntosh counties were kept at D0 as those two counties missed
the intense rains that fell further to the south, in addition to
lingering departures at 180 days. In southern Alabama, copious
rains (7 to 11 inches) erased the small area of D0(L), producing
surpluses at 90 and 180 days. In Florida, a very wet week for
much of the state called for sweeping changes (1 and 2 category
improvements, and in a few areas, 3 categories). South Florida
had 2 to 6 inches, a 2 to 4 inch strip fell from Tampa to
Orlando and Daytona Beach, and over 10 inches inundated the
Jacksonville and St. Johns county areas. The Big Cypress
Preserve had its highest April rainfall since 1970, and the
entire South Florida Water Management District had its heaviest
7-day total for this time of the year. As a result, in north-
central Florida, D2 was improved to D1, D0, or nothing (3
categories) in its eastern half as the rain totals increased
toward the Atlantic Ocean. For example, most of Flagler County,
with over 7 inches of rain, went from D2 to nothing. The western
third of the D2 area, however, remained as amounts were much
lower (less than an inch) in Levy, Citrus, and western Marion
counties, with deficits still lingering at 90 days and USGS
stream flows remaining in the lower tenth percentile. Elsewhere,
most of the D1 was improved to D0 (except to no drought where
the heaviest rains fell), and the former D0 areas eliminated.

The Midwest: With a nearly stationary storm system located over
the Nation’s midsection for days, ample moisture was pulled
northward from the Gulf of Mexico, resulting in widespread heavy
rains (more than 2 inches) from the central Gulf Coast northward
into the western Great Lakes region. Where enough cold air mixed
into the system, late-spring heavy snows blanketed parts of the
Midwest (western Missouri, central Iowa, southeastern Minnesota,
western Wisconsin), and as far south as northwestern Arkansas.
As has been the precipitation pattern recently, the heaviest
totals have fallen mainly along and east of the eastern edge of
the main drought area, thus continuing a slow retreat of the
drought toward the west. In north-central Wisconsin, snow melt
and additional precipitation has caused many dam operators to
release excess water. Rochester, MN, has already had its fourth
wettest spring on record, with the rest of May yet to come.
Ground water sensors in north-central Iowa have risen
considerably during the past 2 months. In contrast, somewhat
lower totals (1 to 1.5 inches) in western Iowa, combined with
shallow well levels that are several feet lower than a year ago
(although they have been rising recently), and low subsoil
moisture estimates from USDA/NASS (4 percent very short and 24
percent short) tempered any major improvements here. However,
the combination of wet and cool weather this year has definitely
dented or eliminated the drought in much of the Midwest, and if
these conditions continue, additional improvement is likely.
With that said, a one category improvement was made in western
Wisconsin, southeastern Minnesota, most of central Iowa, and
western Missouri.

The Plains and western Delta: This week’s precipitation was a
miss, hit, and miss in the northern, central, and southern
Plains, respectively. Fortunately, temperatures averaged well
below normal (6 to 10 deg F) throughout the region, keeping the
heat factor out of this week’s equation except in western
portions of Texas, Oklahoma, and southwestern Kansas where highs
topped 90 deg F early in the period. Unfortunately, the winter
wheat crop, grown in much of the High Plains region, was rated
poor or very poor (percent) in Colorado (56), Kansas (40),
Nebraska (49), Oklahoma (45), South Dakota (62), and Texas (74),
according to USDA/NASS. The U.S. pasture and range conditions
are also starting off very poorly on the strength of drought
from California to the Great Plains. This is mainly due to the
poor previous year (2012) when all sorts of pasture and
rangeland condition records were set.

In the northern Plains, little or no precipitation fell on the
Dakotas, with the exception of 0.7 to 1.5 inches in extreme
southeastern South Dakota. In this area, some slight reductions
of D2 and D3 were made as there were small surpluses at 180
days. However, similar to western Iowa subsoil conditions (see
The Midwest), additional moisture will be required to bring
conditions back to levels a year ago. According to USDA/NASS,
South Dakota topsoil and subsoil moisture was 31 and 71 percent
short or very short, respectively. In contrast, North Dakota was
16 and 34 percent short or very short, respectively. With
changes made last week, the rest of the Dakotas remained
unchanged.

In the central Plains, the slow-moving storm system initially
tracked out of the central Rockies and brought snow and rain to
the central Plains. In western Nebraska (and southeastern
Wyoming and northern Colorado), 1 to 2 inches of precipitation
was enough to significantly reduce 180-day deficits, and in some
cases, create 6-month surpluses (southeastern Wyoming and
northern Colorado), justifying some reduction of D3 in parts of
far western Nebraska, and a slight shrinkage of D4 in
southwestern Nebraska. Farther east, widespread moderate
precipitation (1 to 1.5 inches) provided some slight reduction
of the D2 and D3 edges in eastern Nebraska, with most of this
area now above normal at 6 months. However, 12-month deficits
were still between 8 to 12 inches here, and with USDA/NASS
topsoil and subsoil moisture levels still rated 46 and 84
percent short and very short, respectively, it will take many
more rain events to fully recharge the entire soil profile. In
Kansas, the heaviest precipitation (1.5 to 2.2 inches) fell on
northeastern sections, with 1 to 1.5 inches occurring across the
southeast. Lighter amounts, between 0.2 to 0.5 inches, with some
of the precipitation falling as snow, were recorded across
northwestern and north-central parts of the state. Most of
eastern Kansas is now above normal during the past 90 days, but
some deficits still remain at 6-months. And similar to eastern
Nebraska, 12-months shortages were still large (12 to 16
inches). Accordingly, a one category improvement was made in the
northeast while only minor changes made in the southeast due to
the lingering long-term departures. In the southwest, little or
no precipitation, growing shortages in the short and long term,
and most indices indicating D4 conditions validated an eastward
expansion of D4 in southwestern Kansas. To the north, enough
precipitation (0.3 to 0.5 inches) fell to maintain D3 in
northwestern Kansas.

In the southern Plains and western Delta, light rain (less than
0.5 inch) was limited to northern and eastern Oklahoma, western
Arkansas, and parts of central Texas. Little or no precipitation
fell elsewhere. In northwestern Arkansas, some slight reduction
of D0 was made where 1 to 1.5 inches of precipitation occurred,
but was left where lingering 180-day deficits remained. In
southwestern Arkansas, half inch of rain maintained conditions
there. In Oklahoma, where at least 0.5 inches fell, no changes
were made. Farther west, however, another dry week in the
Panhandles of Oklahoma and Texas have effectively overcome the
short-term moisture from the winter and has reverted back to
impacts consistent with the long-term shortages. Some summer
planting is being skipped, and cattle are being sold off. As a
result, some degradations were made in the southern High Plains,
including a significant increase in D3 and D4. In parts of
coastal Texas that received substantial rains last week, the
streams were still sustaining their flows, thus additional
improvements were made from Corpus Christi to Galveston.

Southwest and West: Except for widely-scattered light showers
late in the period, much of the West saw no precipitation while
experiencing above normal temperatures. The late period change
of weather, however, was beneficial to wildfire fighters as
higher humidity, lower winds, and scattered showers aided the
fight to contain the large Spring blaze in the southern
California coastal mountains. After a good start to the 2012-13
wet season (November and December were very wet), the January
through April period was the complete opposite. In fact, the
January-April precipitation percentiles were the driest on
record in parts of western Oregon, most of northern and central
California, northwestern Nevada, and parts of southwestern
Montana, according to the WRCC. With the early good start to the
West wet season largely forgotten with four consecutive months
of very dry weather and declining basin average precipitation
and snow water content values, D0 was added into central Idaho,
most of Oregon, and southwestern Montana. Northern California
and southern Oregon were similarly degraded by one category,
from D0 to D1, while central California was increased from D1 to
D2. Losses in rangeland grasses and pastures have been reported
in California, with herds being moved to irrigated pastures.
Areas in southern California that received light showers late in
the period were left at D1 for now. In the Sierra Nevada basins,
water year average precipitation ranged from 72 to 81 percent of
normal, while the May 6 SWE at 0 to 45 percent. Slight increases
in D2 and D3 were made in parts of Arizona where the medium-term
deficits were the greatest. In New Mexico, a large expansion of
D4 was made as both short and long-term conditions are near
record low levels. Through March 2013, the past 30 months have
been the driest such period on record. Much of the state
reported under half of normal precipitation the past 6 months.
The months of July, August, and September (JAS) are the 3
wettest consecutive months for New Mexico, coincident with the
summer monsoon. The 2011 and 2012 JAS were the 14th and 9th
driest on record, respectively, and another dry monsoon could be
devastating. In southeastern New Mexico, the Brantley Reservoir,
the largest reservoir on the Pecos, is currently at 1 percent of
capacity. The combined storage on the 4 reservoir along the
Pecos is at 25 percent of average. In the Hatch Valley, New
Mexico’s chile belt, the Elephant Butte Reservoir, where Hatch
irrigation water is stored, held the lowest amount of water
available for irrigation in almost 100 years. Its storage
capacity of 2.2 million acre feet was at 10 percent capacity,
and will severely affect the farmers who must pump groundwater
to make up for the lost river water.

Hawaii, Alaska, and Puerto Rico: In Hawaii, showers over the
weekend dropped 1 to 3 inches of rain on Kauai and Oahu, with
lesser amounts on Molokai, Lanai, and Maui. Parts of western
Oahu had their wettest April since the early 1990s, with April
percentages running between 125 and 278. For example, Honolulu
measured 1.75 inches (normal is 0.63 inches), or 278 percent of
normal. As a result, D0 was removed from western Oahu. For
Molokai, April was relatively dry, but this weekend’s cold front
rains and VHI data suggest improvements. In response, west
Molokai was improved from D1 to D0, but D2(L) was left near the
Kualapuu Reservoir which was still at 20 percent mandatory water
restrictions. On Maui, Ulupalakua Ranch (southwest slope of
Haleakala) had its driest wet season (Oct-Apr) on record,
resulting in expansion of the D3 toward the southeast of Maui.
VHI data showed stress conditions over Kahoolawe, with
Honokanaia (southwest Kahoolawe) measuring 0.08 inches, or 12
percent of normal April rainfall, and 1.07 inches since January
1, or 18 percent of normal. Accordingly, the small island went
from D0 to D1. On the Big Island, coastal ranchers near South
Point stated that they are down to one month of dry feed, and D1
was expanded eastward to include the lower elevations near South
Point. East-facing slopes were also very dry in April (all
stations reporting under half of normal rainfall), but so far
there have not been any agricultural impacts. The remaining
weeks of May will be important as to whether drought develops in
this region.

In south-central and southeastern Alaska, another wet and cold
week (precipitation totals of 2 to 6 inches, average
temperatures 2 to 6 deg F below normal), along with a cold and
wet April, have built sufficient snow packs in south-central and
southeastern sections of the state. The Alaskan SNOTEL basin
average snow water equivalent (SWE) was above normal as of May 1
from the Chena and upper Tanana basins (182 to 254 percent of
normal) in east-central Alaska southward to the Kenai Peninsula
(115 to 181 percent of normal), as well as the southeastern
Alaskan basins (148 percent of normal). Most stream flow
forecasts will be at or above the long term average.
Accordingly, the D0 was removed in south-central Alaska. Farther
north, however, the Kuparuk average basin SWE (in north-central
Alaska) stood at 76 percent of normal, thus the D1 remained
there.

Toward the end of the period, widespread moderate to heavy rains
(1.5 to 5 inches) soaked much of  Puerto Rico, especially the
interior of the island, causing localized flash flooding and the
closure of several roads. As a result, the last remaining small
areas of D0 were removed.

Looking Ahead:  The next 5 days (May 9-13) favor wet weather
across most of the eastern half of the Nation, with the heaviest
totals expected in Colorado, from central Texas eastward to the
Florida Panhandle, and from eastern Kansas northeastward into
New England, with over 2 inches predicted in the latter area.
Little or no rain is expected in most of the West, Southwest,
north-central Plains, and upper Great Lakes region. Temperatures
should average above normal in the Far West, Great Basin, and
northern Rockies, and below normal in the eastern half of the
U.S. and southern Rockies.

For the ensuing 5 days (May 14-18), the odds favor above median
precipitation in the southern High Plains (New Mexico and
western Texas) and the northeastern quarter of the country. The
highest probabilities for submedian rainfall include the
Southeast, and from eastern Nevada to western Nebraska.
Elsewhere there is no tilt in the odds. Probabilities for above-
median temperatures are highest in the western half of the U.S.,
especially the Southwest, while submedian readings are most
likely in the southeastern quarter of the Nation.

To contact the reporter on this story: Stephen Rose in Washington at srose31@bloomberg.net

To contact the editor responsible for this story: Marco Babic at mbabic@bloomberg.net

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