A slow-moving front will interact with a very humid airmass in
place to result in multiple rounds of showers and thunderstorms this
afternoon and evening.

* WHAT...Flash flooding caused by excessive rainfall continues to be
possible.

* WHERE...Washington DC, and portions of Maryland, including the
following areas, Anne Arundel, Carroll, Cecil, Central and
Southeast Howard, Central and Southeast Montgomery, Frederick,
Northern Baltimore, Northwest Harford, Northwest Howard, Northwest
Montgomery, Prince Georges, Southeast Harford and Southern
Baltimore, and northern Virginia, including the following areas,
Arlington/Falls Church/Alexandria, Eastern Loudoun, Fairfax and
Western Loudoun.

* WHEN...From 2 PM this afternoon through 8 PM EDT this evening.

* IMPACTS...Excessive runoff may result in flooding of rivers,
creeks, streams, and other low-lying and flood-prone locations.
Flooding may occur in poor drainage and urban areas.

* ADDITIONAL DETAILS...
- High humidity coupled with a slow-moving front is expected to
result in multiple rounds of showers and thunderstorms this
afternoon and evening. Localized rainfall rates of up to 2
inches per hour, with isolated totals of 2 to 4 inches are
possible.
- Please visit www.weather.gov/safety/flood for flood safety
and preparedness information.
                                            

* WHAT...Heat index values around 105 expected.

* WHERE...Washington DC, and portions of central, northern, and
southern Maryland, and central and northern Virginia.

* WHEN...From 11 AM this morning to 7 PM EDT this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat
illnesses.
                                            

The Maryland Department of the Environment has issued a Code
ORANGE Air Quality Alert Saturday for
the Baltimore City Metro and Annapolis region.

Concentrations of fine particulate matter due to wildfire smoke will
persist at levels consistent with an Air Quality Index of Unhealthy
(Red Alert) to Very Unhealthy (Purple Alert) Friday night into
Saturday morning. Air quality begins to improve Saturday afternoon.

Code Purple and Code Red Air Quality Alerts mean that air pollution
concentrations within the region are unhealthy to very unhealthy for
the general population.

A Code Orange Air Quality Alert means that air pollution
concentrations within the region may become unhealthy for
sensitive groups. Sensitive groups include children, people
suffering from asthma, heart disease or other lung diseases and
the elderly. The effects of air pollution can be minimized by
avoiding strenuous activity or exercise outdoors.

For more information on ground-level ozone
and fine particles visit the web site
mde.maryland.gov/programs/air/AirQualityMonitoring/Pages/index.aspx