**Weekly Report - Snowpack / Drought Monitor Update Date: 11 September,
2008**

**SNOTEL SNOWPACK AND PRECIPITATION SUMMARY**

**Temperature**: SNOTEL and ACIS-day station average temperature
anomalies were highest (positive departures) were located over the
Northern Sierra and lowest (negative departures) over the Northern
Rockies (Fig. 1). Specifically, the greatest positive temperature
departures occurred over Central Interior California (\>+6F) and the
greatest negative departures occurred over Northern High Plains (\<-10F)
(Fig. 1a).

**Precipitation:** Preliminary precipitation totals for the 7-day period
ending 10September shows areas of heavy precipitation over portions of
the Wyoming and Montana while the Southwest Monsoon is continuing over
southern New Mexico. Otherwise, typical dry conditions prevail over the
much of California and the Pacific Northwest (Fig. 2). For the latest
information on the status of the Southwest Monsoon, see:
<http://www.wrh.noaa.gov/twc/monsoon/monsoon_tracker.php>:

![](media/image1.png){width="5.308333333333334in"
height="4.354166666666667in"}

**Rainfall totals for the 2008 Monsoon Season**

Seasonal precipitation (rain & snow water equivalent) as a percent of
normal for the 2008 Water Year that began on October 1, 2007 (Fig. 2a)
shows above normal totals over northeastern Wyoming, parts of the Snake
and Columbia River Basins in Washington, Oregon, and Idaho, and over
parts of Arizona, New Mexico and Colorado. Parts of Nevada are
experiencing significant shortfalls and to a lesser extent in southern
Idaho. No change since last week. For precipitation totals, departures,
and percent of normal for several time periods see:
<http://water.weather.gov/>.

**WESTERN DROUGHT STATUS**

**The West: ** Mostly dry weather prevailed in the West, with cooler
conditions (weekly temperatures averaged 4 to 12 degrees F below normal)
in the Rockies and eastern Great Basin. Above-normal departures (+2 to
+6 degrees F), however, remained in California and Arizona, with
triple-digit highs in California's Central Valley.  According to the
NIFC, 5 large wildfires remained active in northern California, while
California's pastures and ranges were still rated 100% poor or very
poor, according to USDA/NASS.  With continued declines in pasture and
range productivity, the D2 was expanded northward into counties of
northwestern (Del Monte) and northeastern (Lassen) California.  In
central Nevada, low flows on the Humboldt River below Winnemucca have
reduced irrigation allocations to 58% of normal below Rye Patch
reservoir, dropping Pershing County into D1 status.

In contrast, a reassessment from the local western experts suggested
improvement in some western Nevada and eastern California counties where
water year-to-date precipitation (since Oct. 1, 2007) was at or above
normal and no water restrictions were in place.  Accordingly, counties
in western Nevada (northern Churchill, southern Mineral, Esmeralda),
southern Nevada (southern Clark), and eastern California (southern Mono
and northern Inyo) were changed from D1 to D0. Author: [David Miskus,
Joint Agricultural Weather Facility,
CPC/NCEP/NWS/NOAA](mailto:droughtmonitor@unl.edu)

***A comprehensive narrative describing drought conditions for the
nation can be found at the end of this document.***

# DROUGHT IMPACTS DEFINITIONS ([**http://drought.unl.edu/dm/classify.htm**](http://drought.unl.edu/dm/classify.htm))

The possible impacts associated with **D4 (H, A)** drought include
widespread crop/pasture losses and shortages of water in reservoirs,
streams, and wells creating water emergencies. The possible impacts
associated with **D3 (H, A)** drought include major crop/pasture losses
and widespread water shortages or restrictions. Possible impacts from
**D2 (H, A)** drought are focused on water shortages common and water
restrictions imposed and crop or pasture losses likely. The possible
impacts associated with **D1 (H, A)** drought are focused on water
shortages developing in streams, reservoirs, or wells, and some damage
to crops and pastures (Figs. 3, 3a, 3b, and 3c).

**SOIL MOISTURE**

Soil moisture (Figs. 4a and 4b), is simulated by the [VIC macroscale
hydrologic
model](http://www.hydro.washington.edu/Lettenmaier/Models/VIC/VIChome.html).
The detailed, physically-based VIC model is driven by observed daily
precipitation and temperature maxima and minima from approximately 2130
stations, selected for reporting reliably in real-time and for having
records of longer than 45 years (and various other criteria).

## OBSERVED FIRE DANGER CLASS

The National Interagency Coordination Center provides a variety of
products that describe the current wildfire status for the U.S. -
<http://activefiremaps.fs.fed.us/lg_fire2.php>. The latest Observed Fire
Danger Class is shown in Figs. 5 shows the current active wildfires
across the West - <http://geomac.usgs.gov/>.

**U.S. HISTORICAL STREAMFLOW**

This map, (Fig. 6) shows the 7-day average streamflow conditions in
hydrologic units of the United States and Puerto Rico for the day of
year. The colors represent 7-day average streamflow percentiles based on
historical streamflow for the day of the year. Thus, the map shows
conditions adjusted for this time of the year. Only stations having at
least 30 years of record are used. Sub-regions shaded gray indicate that
insufficient data were available to compute a reliable 7-day average
streamflow value. During winter months, this situation frequently arises
due to ice effects. The data used to produce this map are provisional
and have not been reviewed or edited. They may be subject to significant
change.

<http://water.usgs.gov/cgi-bin/waterwatch?state=us&map_type=dryw&web_type=map>.

# 

# STATE ACTIVITIES

State government drought activities can be tracked at the following URL:
<http://drought.unl.edu/mitigate/mitigate.htm>. NRCS SS/WSF State Office
personnel are participating in state drought committee meetings and
providing the committees and media with appropriate SS/WSF information -
<http://www.wcc.nrcs.usda.gov/cgibin/bor.pl>. Additional information
describing the products available from the Drought Monitor can be found
at the following URL: <http://drought.unl.edu/dm/>

## 

## FOR MORE INFORMATION

The National Water and Climate Center Homepage provide the latest
available snowpack and water supply information. Please visit us at
[http://www.wcc.nrcs.usda.gov](http://www.wcc.nrcs.usda.gov/). This
document is available from the following location on the NWCC homepage -
<http://www.wcc.nrcs.usda.gov/water/drought/wdr.pl>

[This report](http://www.wcc.nrcs.usda.gov/water/drought/wdr.pl) uses
data and products provided by the Interagency Drought Monitor Consortium
members and the National Interagency Fire Center.

/s/ NOLLER HERBERT

Director, Conservation Engineering Division

> ![](media/image2.png){width="6.752777777777778in"
> height="8.946527777777778in"}

![](media/image3.png){width="7.145138888888889in"
height="5.686805555555556in"}

![](media/image4.png){width="7.134722222222222in"
height="5.677777777777778in"}

![](media/image5.png){width="7.396527777777778in"
height="5.513194444444444in"}![](media/image6.png){width="7.217361111111111in"
height="5.521527777777778in"}![](media/image7.png){width="6.409722222222222in"
height="8.255555555555556in"}

![](media/image8.png){width="7.673611111111111in" height="5.75625in"}

![](media/image9.png){width="7.334027777777778in"
height="5.729166666666667in"}

![](media/image10.png){width="6.801388888888889in"
height="5.198611111111111in"}

![](media/image11.png){width="7.360416666666667in"
height="7.929861111111111in"}

**Fig. 3c: Drought Monitor classification changes. Note improvement over
the Mid-Atlantic States this past week.** Ref:
<http://www.cpc.ncep.noaa.gov/products/predictions/experimental/edb/dm-change-4maps.png>

![](media/image12.png){width="5.668055555555555in"
height="4.096527777777778in"}

**\
**![](media/image13.png){width="5.313888888888889in" height="3.78125in"}

**Figs. 4a & 4b: Soil Moisture Ranking and change in percentile based on
1915-2003 climatology for this past week. The driest conditions persist
over California and part of Nevada, Wisconsin, and Kentucky (Fig. 5).
Last week saw a significant increase in soil moisture over the Eastern
Seaboard (TD Hanna) and central region of the nation. Significant
decreases in soil moisture occurred over the Appalachian Mountains.**
Ref:
<http://www.hydro.washington.edu/forecast/monitor/curr/CONUS.multimodel.sm_qnt.gif>

> <http://www.hydro.washington.edu/forecast/monitor/curr/CONUS.vic.sm_qnt.1wk.gif>

![](media/image14.png){width="7.8381944444444445in"
height="5.815277777777778in"}

![](media/image15.png){width="5.978472222222222in"
height="5.009722222222222in"}

### Fig. 6. Map of below normal 7-day average streamflow compared to historical streamflow for the day of year. Ref: [**http://water.usgs.gov/waterwatch/?m=dryw&w=map&r=us**](http://water.usgs.gov/waterwatch/?m=dryw&w=map&r=us) 

**National Drought Summary \-- September 9, 2008**

*The discussion in the Looking Ahead section is simply a description of
what the official national guidance from the National Weather Service
(NWS) National Centers for Environmental Prediction is depicting for
current areas of dryness and drought. The NWS forecast products utilized
include the HPC 5-day QPF and 5-day Mean Temperature progs, the 6-10 Day
Outlooks of Temperature and Precipitation Probability, and the 8-14 Day
Outlooks of Temperature and Precipitation Probability, valid as of late
Wednesday afternoon of the USDM release week. The NWS forecast web page
used for this section is:*
<http://www.cpc.ncep.noaa.gov/products/forecasts>*/.*

**Weather Summary:**  After meandering Tropical Storm Fay dumped heavy
rains on the Southeast in late August, two more tropical systems
impacted the lower 48 States.  After raking Louisiana, slow-moving
Hurricane Gustav drenched the lower and middle Mississippi valleys and
middle Great Lakes region, while fast-tracking Tropical Storm Hanna
inundated the eastern portions of the Atlantic Coast States. Meanwhile,
feeder bands from Tropical Storm Hanna soaked Puerto Rico and flooded
northern Haiti. 

Spotty, locally heavy thunderstorms dropped 1 to 4 inches of rain on
parts of the central and southern Plains; however, only light rains fell
on the upper Midwest and in-between the heavy rain tracks of Gustav and
Hanna, particularly on the core D2-D4 drought areas of the southern
Appalachians. Unseasonably cool weather enveloped the Rockies, Plains,
and Mississippi River Valley, while above-normal temperatures prevailed
in California, Arizona, and the eastern third of the nation.

**The Northeast and mid-Atlantic: ** Tropical Storm Hanna *(see Delta
and Southeast below*) rapidly tracked northeastward, dumping moderate to
heavy rains on eastern sections of the mid-Atlantic and New England.  A
wide swath of more than 2 inches was measured in the eastern half of
Virginia, most of Maryland, Delaware, and New Jersey, eastern
Pennsylvania, and points northeastward.  Isolated amounts of over 9
inches were measured south of Washington, D.C., causing flash flooding
in Prince William County, VA.  As a result, a 1-category reduction was
made in the aforementioned areas as short-term dryness D0(A) was
eliminated.  Moderate drought was alleviated in the Delmarva Peninsula
and southern New Jersey, but D0 remained as rains from Hanna were lower
(less than 2 inches).

Although the bulk of significant rains from Hanna stayed east of the
Appalachians, a cold front on Monday produced 1 to 2 inches of rain that
shrank the D0-D1 area of central Pennsylvania.  In addition, the Monday
thunderstorms insured that short-term dryness D0(A) did not spread into
western Pennsylvania and northern West Virginia, another area missed by
Hanna.

**Midwest:**  In the eastern Corn Belt, rains from Gustav dumped over 2
inches on northwestern Indiana and much of Lower Michigan, including
almost 5 inches near Grand Rapids, MI, eliminating the western and
northern D0 area, and trimming away the western edge of D1.  In
southwestern Ohio, thunderstorms dropped 1 to 2 inches of rain, further
easing D0(A) there.  Just to the north, however, rainfall sharply
diminished, and weekly totals in northeastern Indiana and northwestern
Ohio were less than 0.5 inches, maintaining D0 and even adding a new D1
area in the latter region.  Since July 9, only 44% of normal
precipitation (2.64 inches observed vs. 6.03 inches normal) has been
measured at Toledo, OH.

In the western Corn Belt, Gustav dumped 1.5 to 2 inches of rain on
northwestern Missouri and northeastern Kansas, eliminating any lingering
abnormal dryness, but dropped less than 0.5 inches on southwestern Iowa,
maintaining D0-D1 there.  In the upper Midwest, Gustav completely
bypassed Minnesota and northern Wisconsin, and deficits since early
summer continued to grow.  Since June 17, under 60% of normal
precipitation was measured across most of northeastern, north-central,
and southeastern Minnesota, including less than 40% between Grand Rapids
and Brainerd where a small D2 was added.  With similar departures
existing across northern Wisconsin, and 28-day USGS stream flow values
in the lower 10th percentile, D1 was expanded across the upper Midwest.

**The Delta and Southeast: ** Although heavy rains from Hurricane Gustav
mainly fell on non-drought areas of the lower and middle Mississippi
valleys, a small remaining area of D0 in west-central Louisiana and
extreme southeastern Texas was alleviated as 1 to 6 inches of rain
fell.  Additional Gustav relief also occurred in northeastern
Mississippi and western Tennessee as 1.5 to 3 inches removed abnormal
dryness there. 

Farther east, Tropical Storm Hanna made landfall near the South and
North Carolina border early in the morning Saturday, and rapidly tracked
northeastward.  Totals were greatest to the northwest of Hanna's track
and less to the east where winds were stronger. In the Carolinas, storm
totals of 2 to 6 inches, locally to 9 inches, occurred in eastern South
Carolina and east-central North Carolina, improving conditions by at
least one category.  In eastern North Carolina, amounts under 2 inches
improved short-term dryness, but with long-term deficits still
persisting and real-time wells and stream flows still at near-record low
levels, only the impact type designation changed (AH to H). Farther west
in the core D2-D4 areas of the southern Appalachians, little to no rain
fell courtesy of Hanna and Gustav, and drought conditions remained. In
fact, 7-day USGS average stream flows ending September 9 were still near
or at record-low values from northern Georgia northward into
southwestern Virginia.

**The Plains: ** Scattered showers and thunderstorms dropped 1 to 4
inches on parts of the Great Plains, specifically in northwestern North
Dakota, most of Nebraska and Kansas, northern Oklahoma, southeastern New
Mexico, and southwestern and west-central Texas.  The rains were enough
to make some 1-category improvements in the aforementioned areas.  In
North Dakota, however, the driest conditions shifted southward into
southwestern sections, namely Bowman and Adams counties, while
improvements were made to northern drought areas.  In Nebraska, 1-2
inches of rain eliminated D1 in the Panhandle and southeastern sections,
while locally heavy thunderstorms trimmed the D0 in southwestern Kansas
and extreme northern Oklahoma.  Farther south, scattered thundershowers
late in the period provided relief from abnormal dryness in southeastern
New Mexico and southwestern and west-central Texas, especially around
San Angelo, where a September 8 record of 3.05 inches of rain fell.

**The West: ** Mostly dry weather prevailed in the West, with cooler
conditions (weekly temperatures averaged 4 to 12 degrees F below normal)
in the Rockies and eastern Great Basin. Above-normal departures (+2 to
+6 degrees F), however, remained in California and Arizona, with
triple-digit highs in California's Central Valley.  According to the
NIFC, 5 large wildfires remained active in northern California, while
California's pastures and ranges were still rated 100% poor or very
poor, according to USDA/NASS.  With continued declines in pasture and
range productivity, the D2 was expanded northward into counties of
northwestern (Del Monte) and northeastern (Lassen) California.  In
central Nevada, low flows on the Humboldt River below Winnemucca have
reduced irrigation allocations to 58% of normal below Rye Patch
reservoir, dropping Pershing County into D1 status.

In contrast, a reassessment from the local western experts suggested
improvement in some western Nevada and eastern California counties where
water year-to-date precipitation (since Oct. 1, 2007) was at or above
normal and no water restrictions were in place.  Accordingly, counties
in western Nevada (northern Churchill, southern Mineral, Esmeralda),
southern Nevada (southern Clark), and eastern California (southern Mono
and northern Inyo) were changed from D1 to D0.

**Puerto Rico and Hawaii:**  Heavy, widespread rains from Tropical Storm
Hanna feeder bands (the center passed well to the west of Puerto Rico)
dropped 5 to 12 inches across much of the island, producing localized
flooding but improving drought conditions by one category.  D0(H),
however, was left where the former D1 area was as long-term deficiencies
(50-75% of normal rainfall at 90- and 180-days) remained.  In Hawaii,
light occasional showers, more frequent on the windward than leeward
sides, were not enough for any improvement, keeping conditions
status-quo.

***Looking Ahead: *** During the next 5 days (September 11-15), all eyes
will be watching Hurricane Ike, currently intensifying in the central
Gulf of Mexico and tracking west-northwestward.  Ike is expected to make
landfall in Texas early this weekend as a dangerous Category 3
hurricane, then curve north into the south-central Plains, and northeast
into the middle Mississippi Valley.  Expect heavy rains to occur along
the track of Ike.  Meanwhile, cooler, drier air will prevail in the
Northeast, while wet weather will continue along a front extending from
western Texas through the Carolinas.  A second system is expected to
bring rain across the northern and central Plains and Midwest.  The Far
West should remain warm and dry throughout the period.

The CPC 6-10 day forecast (September 16-20) calls for above-normal
chances of rain in the Southwest and Sierra Nevada and southern Texas,
and from the Appalachians eastward.  Drier than usual weather is
expected from the Pacific Northwest southeastward into the central
Plains and northeastward into the upper Midwest.  Unseasonable warmth is
predicted for the Northwest and Great Basin, with subnormal readings in
the South and East (except Florida).

**Author:** [David Miskus, Joint Agricultural Weather Facility,
CPC/NCEP/NWS/NOAA](mailto:droughtmonitor@unl.edu)

  **Dryness Categories**

D0 \... Abnormally Dry \... used for areas showing dryness but not yet
in drought, or for areas recovering from drought.\
\
**Drought Intensity Categories**\
D1 \... Moderate Drought\
D2 \... Severe Drought\
D3 \... Extreme Drought\
D4 \... Exceptional Drought\
\
**Drought or Dryness Types**\
A \... Agricultural\
H \... Hydrological

Updated September 10, 2008