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WORSENING DROUGHT IN THE MID-ATLANTIC REGION

What's Going On

Drought has developed across a large part of the mid-Atlantic region, and the recent heat has rapidly intensified the dryness, with daily record highs on Monday of 98 F at DCA on and 96 F at IAD and BWI and more record highs expected on Tuesday. In the Mid-Atlantic region, the drought is centered over Maryland and Virginia, but also extends southward into Florida and other parts of the Deep South as well as northward into parts of New England. According to the long-term Palmer Drought Index, all of Maryland except the western panhandle is in severe to extreme drought, with northern Virginia in the severe drought category.

The origins of the current drought in the mid-Atlantic region can be traced to problems over both- medium and long-term periods.

From the medium-term perspective, abnormal dryness began during the last week of April and continued until the present, with May rainfall only 1 to 2 inches in the DC area. As a result, rainfall during the past 6 weeks has totaled only about 1 to 2 inches where around 4 to 6 inches would be expected. In addition, most of the region has measured no rainfall during the past 2 weeks. Temperatures rising into the 80s during the weekend and 90s on Monday and Tuesday of this week further aggravated the dryness.

Looking at the long-term perspective, abnormal dryness began last July and continued through the end of 1998. The precipitation deficits in the Baltimore-Washington area accumulated to around 13 inches during the last 6 months of last year, when only about 7 inches of precipitation fell versus a normal of around 20 inches. Heavy precipitation this past winter, especially in January and March, has resulted in year-to-date totals near normal despite the recent dryness, but total precipitation since last July remains under two-thirds of normal, with the deficit now around 14 inches.

For farmers in the Maryland and northern Virginia region, this makes the third consecutive year of drought, though the current drought comes abnormally early in the growing season.

Besides southern Maryland, other areas of the country experiencing extreme drought
according to the Palmer Index are central Georgia and north-central Florida. The
Georgia- Florida area has experienced persistently below-normal precipitation since late
January.

In other parts of the country, fingering drought after an abnormally dry winter continues
over parts of the Southwest, especially southwestern Texas and much of Arizona.
Another area of some concern, where near-drought conditions prevail, includes eastern
parts of Washington and Oregon, a rather surprising development given the record winter
rain and snowfalls in western parts of both states. Near the center of the country, across
the Great Plains, wet and stormy weather, with numerous severe outbreaks of thunderstorms, has persisted throughout the spring.

The drought is now having major impacts on farming up and down the Eastern Seaboard. In Maryland and Virginia, soil moisture is rated adequate in only about 10% of each state, with nearly 90% of both states short topsoil moisture. As a result, corn is beginning to wilt in many localities. In the Carolinas, the crop situation is critical, with crops entering their critical stages of development. Rainfall has been 3 to 9 inches below normal since March 1 in North Carolina. In South Carolina, corn faces a potential complete loss if rain does not come soon. In Georgia, 49% of the pastureland is rated in poor to very poor condition, with 41% of the corn and soybeans in poor or very poor shape.

What is the Outlook?

A cooling trend is expected later this week across the mid-Atlantic and Northeastern regions, culminating in a return to near-normal precipitation and temperatures by the middle of next week.

The summer seasonal forecast for the local region is for near normal rainfall. Although this will provide some relief for agriculture, the long-term deficits will not be erased unless the region experiences a tropical storm or hurricane.

The NWS seasonal hurricane outlook is for an enhanced likelihood of above normal number of tropical storms and hurricanes. However, the science does not permit a statement as to whether this region will be affected.

The extended outlook for the fall and winter is for a continuation of La Niña impacts
which results in below-normal rainfall in the Southeast and Southwest.

How did this happen?

U.S. climate during last year was strongly affected by La Niña. The U.S. wintertime impacts of this were well. predicted by the CPC.

The La Niña played a role in producing the rainfall deficits across the southern tier states and also the mid-Atlantic region.

The longer-term trends indicate that this area and the southeastern U.S. as a whole is getting less rainfall than average.

Understanding the origins of this trend is an active area of research for NOAA.

As for the near-term outlook, slightly cooler weather and some risk of showers are on slate by week's end for the Maryland-Virginia region, but rainfall amounts expected would barely dent the ongoing drought. However, heavier showers expected in the Carolinas,

Georgia, and Florida should improve the dry situation in those states, especially in the Florida peninsula, where 1 to 4 inches of rain is expected over the next 5 days.

Looking ahead to the rest of the summer, long-range rainfall forecasts in the U.S. are notoriously unreliable during the summer, but a new soil moisture model being tested at CPC that uses analogues to project future weather and moisture conditions suggests that most of the dryness should be history by late August along the Eastern Seaboard, with the greatest risk of drought displaced westward from the Ohio Valley southward to the lower Mississippi Valley. Moisture conditions in the Great Plains may remain wetter-than-normal for much of the summer.

The forecast of increased moisture along the southeastern coast is compatible with indications of an abnormally active tropical storm system in the Atlantic this summer and fall.

Relevant Web Sites:

NOAA's Climate Prediction Center for information about extended range seasonal forecasts, impacts of El Niño and La Niña, seasonal trends in U.S. temperature and rainfall: http://www.cpc.ncep.noaa.gov

The Drought Mitigation Center for general information about drought and drought impacts: http://enso.unl.edu/ndmc