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September 9, 2010

Third of Maryland now in drought

Drought Monitor 

The new Drought Monitor map, released Thursday morning, shows that nearly a third of Maryland is now in "moderate" to "extreme" drought, with the most serious drought in Western Maryland.

Southern Maryland and the Lower Eastern Shore are also struggling with scarce rainfall. But hardest-hit is an arc of territory along the Potomac River in Allegany and Washington counties, where conditions were rated as "extreme" for the first time this summer, as rainfall dwindled to 40 percent of normal. Portions of nearby West Virginia and Virginia are also in the "extreme drought" zone. 

Drought conditions in Garrett, Allegany, Washington counties and the western sections of Frederick County are all rated as "severe" to "extreme."USGS Washington County well  The graph below shows the water level in a monitoring well in Washington County over the past 90 days.

Farther east, the yellow shading where the state is considered to be "abnormally dry" has crept back into northern Carroll, Baltimore and Harford counties, and "moderate" drought persists in the Lower Eastern Shore.

The "drought" ratings are derived from data on soil moisture, rainfall, streamflow and vegetation health measured by satellite. Here are some definitions:

D1: "Moderate" drought: Some damage to crops, pastures; fire risk high; streams, reservoirs, or wells low, some water shortages developing or imminent, voluntary water use restrictions requested

D2: "Severe" drought: Crop or pasture losses likely; fire risk very high; water shortages common; water restrictions imposed

D3: "Extreme" drought: Major crop/pasture losses; extreme fire danger; widespread water shortages or restrictions

D4: "Exceptional" drought: Exceptional and widespread crop/pasture losses; exceptional fire risk; shortages of water in reservoirs, streams, and wells, creating water emergencies

Overall, the percentage of the state where moisture is rated as normal (white on the map) shrank from 58 percent to 41 percent in the past week. Sixty percent is considered to be abnormally dry or in drought, up from 42 percent last week.

Many Maryland streams are running far below normal (cranberry and red dots on the map below).

Here's how the Drought Monitor described the week's developments:

"Across the panhandle of West Virginia, northwest Maryland and extreme southwest Pennsylvania, extreme drought (D3) conditions were added.  Precipitation for the most recent 30 and 90 days measure in at about 40% of normal, while the SPI, NLDAS soil moisture and stream flows are all below the 5% threshold for indicating extreme drought.  USGS Streamflow

"Across northern Virginia, abnormal dryness was expanded from the west toward the District of Columbia to reflect the field reports of deciduous trees dropping leaves and fruit earlier than normal due to lack of recent rainfall.

"Abnormal dryness and moderate drought were also expanded into eastern Pennsylvania and across Delaware, where the entire state is now experiencing abnormal dryness or moderate drought.   Dropping lake levels and scorched lawns are becoming more common across this region."

A Water Supply Outlook report issued last week by the Interstate Commission on the Potomac River Basin said water resources in the system are decreasing, with stream flow throughout the basin below normal. And the forecasts indicate the pattern will continue.

Upstream reservoirs - Jennings Randolph and Little Seneca - are "moderately full to full," the report stated. So, "from a water supply perspective, there is sufficient water in the Potomac River to meet Washington metropolitan area demands..."  Water releases from the reservoirs would supplement the Potomac's flow and ensure supplies for downstream communities that get their drinking water from the river.

Okay. Now I've written about the drought. Let the rains begin.

Posted by Frank Roylance at 11:38 AM | | Comments (2)
Categories: Drought
        

Comments

None of this looks very optimistic.
Some boaters are pulling for a little turn-around in October, plus maybe extra boost from expected earlier leaf-drop improving run-off & reduced tree-leaf transpiration.

Also ran across these "long range" forecasts from

http://www.longrangeweather.com/Long-Range-Monthly-Weather-Forecasts.htm

Never heard of Harris-Mann;
any comments on credibility?? (As far as long-term forecasting in general goes, that is.. ;-D) I assume this type of long range forecasting might be based on expected oceanic dynamics, which haven't been bringing anything our way lately.

Thanks Frank for this info. I live in Western Frederick County and I have to say, its surreal. it just doesn't rain anymore. It has actually reached the point where you literally don't watch the weather reports because everyday is the same thing. I just check this blog daily because I like your commentary but that is about it. Since July 1 it has only rained on 3 days, the last being August 12th. I have lost several trees on my property, we just cannot water them anymore, everything is dying, and it looks like Arizona. Is there any long term foreast models showing this pattern changing?

FR: The NOAA Climate prediction Center's long-term forecast for Sept. through Nov. shows equal chances for above- or below-normal precipitation. http://bit.ly/ik1NJ Not much help there. These things are usually, or often, broken by a tropical storm, or remnants of one. That's a fair bet through October, anyway.

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About Frank Roylance
This site is the Maryland Weather archive. The current Maryland Weather blog can be found here.
Frank Roylance is a reporter for The Baltimore Sun. He came to Baltimore from New Bedford, Mass. in 1980 to join the old Evening Sun. He moved to the morning Sun when the papers merged in 1992, and has spent most of his time since covering science, including astronomy and the weather. One of The Baltimore Sun's first online Web logs, the Weather Blog debuted in October 2004. In June 2006 Frank also began writing comments on local weather and stargazing for The Baltimore Sun's print Weather Page. Frank also answers readers’ weather queries for the newspaper and the blog. Frank Roylance retired in October 2011. Maryland Weather is now being updated by members of The Baltimore Sun staff
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