U.S. Drought Monitor: Updated Sept. 2

9/5/2008 7:46:00 AM

The Northeast and Mid-Atlantic:
The week was generally drier than average from coastal mid-Atlantic
to New England and interior New York, while the remnants of Tropical
Storm Fay brought more than 3 inches of rain to central and southern
Virginia and widespread amounts of 1 to 2 inches northward through
western Maryland and central and western Pennsylvania. Abnormally dry
(D0) conditions expanded northward from southeastern to northeastern
Pennsylvania and all but the northernmost counties of New Jersey. An
area of moderate (D1A) drought developed in southern New Jersey,
Delaware, and the Eastern Shore of Maryland where the deteriorating
conditions are reflected by USGS 7- to 28-day streamflow values below
the 10th percentile. Abnormally dry conditions also expanded westward
to cover much of the eastern half of Pennsylvania, and the areal
coverage of moderate (D1A) drought in central Pennsylvania expanded
eastward where 30- and 60-day precipitation amounts were generally
less than 50% and 70% of average, respectively.

Precipitation fell in parts of eastern Kentucky and eastern Ohio as
remnants of Tropical Storm Fay moved northeastward. Totals were
generally not sufficient for improvements in widespread abnormally
dry and moderate drought conditions. But in southeastern Ohio, totals
from 1 to 2 inches brought an end to abnormally dry conditions. In
central and western Kentucky, a continued lack of rainfall and
growing 30- to 90-day deficits led to the northward expansion of
abnormal dryness (D0) and moderate (D1AH) drought.

A continued lack of rainfall in northern Indiana and southwestern
Michigan led to the introduction of moderate (D1A) drought from the
southeastern shores of Lake Michigan to northeastern Indiana. With
rainfall totals less than 25% of average during the past 30 to 45
days, there have been widespread reports of rapidly deteriorating
crop conditions. Moderate (D1A) drought also expanded across the
western third of the Upper Peninsula of Michigan and areas of
northeastern Wisconsin where 30- to 45-day precipitation totals are
less than 50% of average, modeled soil moisture indicates
deteriorating conditions, and USGS 7- to 28-day streamflows are well
below the 10th percentile.

Localized rainfall amounts of 2 to 4 inches brought an end to
abnormally dry conditions in west central parts of Iowa, while
worsening 30- to 45-day precipitation deficits led to a southeastward
expansion of moderate (D1A) drought from eastern Nebraska to
southwestern parts of Iowa. Abnormal dryness (D0A) also expanded
southwestward from southwest Wisconsin into northeast Iowa.

More than 5 inches of rain associated with the remnants of Tropical
Storm Fay brought widespread 1-category improvements from the central
Piedmont of South Carolina to northwestern North Carolina, and
southern and central areas of Virginia. These improvements left a
transition from moderate (D1H) drought in the central Piedmont of
North Carolina to extreme (D3H) drought in southwestern areas of the
state. A 1-category improvement to moderate (D1H) drought in
southwestern and south-central Virginia and an improvement to
abnormally dry conditions from central to northern Virginia reflect
the effects of widespread rainfall amounts exceeding 2 to 3 inches
and scattered totals exceeding 5 to 6 inches. Totals generally less
than 1 inch fell in southeastern Virginia where severe (D2H) drought
conditions remain. There were small reductions in the coverage of
abnormally dry (D0) and moderate (D1H) drought in northeastern South
Carolina, while exceptional (D4H) drought remained in much of the
Upstate, where lower rainfall totals from Tropical Storm Fay (2 to 3
inches) left larger long-term deficits and persistent severe impacts.

Rainfall was again below average in northeastern North Carolina and
severe (D2H) drought expanded southward across Halifax, Edgecombe,
and Wilson counties where USGS 7- to 28-day streamflows below the 5th
percentile were widespread. Moderate (D1AH) drought also expanded
southward along coastal areas of southeastern North Carolina where
30- to 90-day precipitation totals were generally below 70%.

A reduction from severe (D2H) to moderate (D1H) drought was made in
Tennessee where more than 5 inches of rainfall from Tropical Storm
Fay brought 30- to 180-day precipitation totals to near and above
average. Moderate (D1AH) drought expanded in northwestern Tennessee
where 60- and 90-day precipitation totals were generally less than
50% of average and multi-model soil moisture estimates below the 10th
percentile reflected deteriorating conditions.

The Delta:
A northwestward-moving Hurricane Gustav made landfall along the coast
of southeastern Louisiana as a Category 2 storm on September 1, and
brought more than 6 inches of rain to the most severely
drought-affected areas of the state. At the U.S. Climate Reference
Network station in Lafayette, 5.82 inches of rain fell prior to the
12Z cutoff on Sept 2, with almost 2.5 inches falling in the
succeeding 24 hours. To the north in Monroe, Louisiana, 3.01 inches
fell before the 12Z cutoff and more than 8 additional inches before
noon the next day. Two-category improvements occurred in areas that
had been in moderate (D1H) and severe (D2H) drought in central
Louisiana, while a sharp westward gradient of decreasing rainfall
totals resulted in 1-category reductions in southwestern areas of the
state. Abnormally dry hydrologic conditions (D0) were present from
southwestern to central Louisiana at the end of the DM period.

The Plains:
In Del Rio more than 6 inches of rain on August 29th helped push its
monthly total to more than 11 inches and produced the second-wettest
August since records began in 1905. More than 2 inches fell north of
Del Rio and more than 1 inch of rain was widespread along and east of
the Rio Grande in areas where 30-day totals have been generally more
than 150% of average. The heavy rain brought an end to drought and
abnormally dry conditions in the Del Rio area, and broad 1-category
reductions occurred eastward to the San Antonio area. Abnormally dry
and moderate (D1A) drought conditions are now present in areas that
were impacted by severe (D2H) to extreme (D3H) drought in early

Areas of western Oklahoma, the eastern Panhandle of Texas, and
southwestern Kansas received more than an inch of rain and isolated
amounts greater than 2 to 3 inches fell within the past week,
bringing about a reduction in the areal coverage of abnormal dryness.
A small reduction in moderate (D1H) drought was also made in
southwestern Kansas.

Short-term conditions continued to deteriorate in eastern South
Dakota and southwestern Minnesota, leading to an expansion of
moderate (D1A) drought conditions where summer rainfall was less than
70% of climatological norms. An expansion of moderate (D1A) drought
also occurred in southeastern Nebraska, while 1 to 3 inches of rain
from northwestern Nebraska to northeastern South Dakota resulted in a
reduction of abnormal dryness in areas of south-central and
northeastern South Dakota, and northwestern Nebraska.

A persistent pattern of showers in eastern North Dakota brought 1 to
2 inches of rain during the past two to three weeks and helped end
abnormally dry conditions in much of the eastern half of the state.
Areas of moderate (D1H) drought in north-central North Dakota also
decreased. Moderate (D1H) to extreme (D3H) conditions persist in
western areas of the state where the Vegetation Drought Response
Index and long-term precipitation deficits reflect continuing poor

The West:
The far West was generally drier than average during the past week
while widespread areas of near- and above-average precipitation
occurred from the Southwest to parts of the northern Rockies. Drought
designations across most areas of the West remained unchanged, but
drought severity worsened in southwestern Utah and northern
California. Moderate (D1A) drought expanded to the Oregon border in
northern California’s Del Norte County, where rainfall since February
has been less than 50% of average. The lack of rainfall has resulted
in sharp losses in non-irrigated crops and pasture land for
livestock. The area of severe (D2H) drought near the northern
California/Nevada border also grew to cover all of Lassen County. In
southwestern Utah, an area of abnormally dry (D0) and moderate (D1AH)
drought was extended eastward where 6-month precipitation deficits
reflect below average precipitation during the critical spring and
early summer seasons and impacts to agriculture have been widespread.

Hawaii, Alaska and Puerto Rico:
In Hawaii, moderate (D1A) drought expanded on the northeast slopes of
the island of Oahu where deteriorating conditions led to requests for
voluntary reductions in public water consumption. The remainder of
the state remained status quo. No changes were made in Puerto Rico
where rainfall in central and western areas was generally average to
above average while precipitation in drought-affected and abnormally
dry areas on the eastern side of the island was generally average to
below average.

Looking Ahead:
During the next 5 days (through September 8) tropical activity will
remain a dominant feature affecting the eastern half of the U.S.
Remnants of Hurricane Gustav are expected to remain over the central
U.S. through the weekend with moisture from these remnants expected
to flow northeastward along a frontal boundary extending from the
southern Plains northeastward. The greatest potential for heavy
rainfall from this system is the mid-Mississippi Valley to the Great
Lakes. In the Atlantic, Hurricane Hanna is expected to reach the
southeastern U.S. before moving northeastward along the eastern
seaboard. There is potential for heavy rainfall in the Carolinas and
along the path of Hanna through the easternmost areas of the
mid-Atlantic and Northeast. Scattered showers are expected in the
north-central U.S., while much of the western U.S. with the exception
of the northern Rockies is expected to experience generally dry and
warmer-than-average conditions.

The CPC 6-10 day forecast (September 9-13) calls for moisture from
Hurricane Hanna to move off the East Coast by the start of the
forecast period, but above-average precipitation is expected to
continue in the eastern half of the nation as a result of an active
upper-level pattern. NOAA’s National Hurricane Center expects
Tropical Storm Ike to develop into a hurricane with the possibility
that this storm could bring additional rainfall to parts of Florida
and Gulf Coast states. Temperatures are expected to be below normal
over the central U.S. while large parts of the West experience
above-normal temperatures and drier-than-average conditions.

US Drought Monitor, September 2, 2008


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