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Radar valid at 145 pm EDT, Aug 4th 2020

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Tropical Storm Isaias Local Statement Advisory Number 29
National Weather Service Baltimore MD/Washington DC AL092020
539 AM EDT Tue Aug 4 2020

This product covers Eastern West Virginia, Central and Western Maryland,
Northern and Northwestern Virginia, and District of Columbia



- None

- A Tropical Storm Warning is in effect for Anne Arundel,
Arlington/Falls Church/Alexandria, Calvert, Carroll, Central
and Southeast Howard, Central and Southeast Montgomery,
Charles, District of Columbia, Fairfax, King George, Northern
Baltimore, Northwest Harford, Northwest Howard, Northwest
Montgomery, Prince Georges, Prince William/Manassas/Manassas
Park, Southeast Harford, Southern Baltimore, Spotsylvania, St.
Marys, and Stafford

- About 180 miles south of Washington DC or about 210 miles
south-southwest of Baltimore MD
- 36.3N 77.5W
- Storm Intensity 70 mph
- Movement North-northeast or 20 degrees at 28 mph


Tropical Storm Isaias will move rapidly to the north northeast
passing near or over St. Mary's County this morning and exit the
Chesapeake Bay by midday.

Life-threatening flash flooding of small streams and creeks is
likely today as rainfall associated with Isaias continues to spread
northward. Widespread rainfall totals of 3 to 6 inches are expected
with locally higher amounts possible. The highest amounts are
expected over the I-95 corridor through early afternoon.

Tropical storm force winds are likely along and east of the I-95
corridor this morning. Tree damage and power outages are possible in
this area. There is also a risk of isolated tornadoes across
southern Maryland through this morning. Moderate coastal flooding is
also likely along the western shores of the Chesapeake Bay and at
Washington DC Southwest Waterfront today. Minor coastal flooding is
likely along other tidal waters.


Potential impacts from the flooding rain are still unfolding across
along and east of Interstate 95. Remain well guarded against
life-threatening flood waters having extensive impacts.

If realized, these impacts include:
- Major rainfall flooding may prompt many evacuations and rescues.
- Rivers and tributaries may rapidly overflow their banks in
multiple places. Small streams, creeks, canals, arroyos, and
ditches may become dangerous rivers. In mountain areas,
destructive runoff may run quickly down valleys while
increasing susceptibility to rockslides and mudslides. Flood
control systems and barriers may become stressed.
- Flood waters can enter many structures within multiple
communities, some structures becoming uninhabitable or washed
away. Many places where flood waters may cover escape routes.
Streets and parking lots become rivers of moving water with
underpasses submerged. Driving conditions become dangerous.
Many road and bridge closures with some weakened or washed out.

Potential impacts from the main wind event are now unfolding across
southern Maryland. Remain well sheltered from dangerous
wind having possible significant impacts. If
realized, these impacts include:
- Some damage to roofing and siding materials, along with damage
to porches, awnings, carports, and sheds. A few buildings
experiencing window, door, and garage door failures. Mobile
homes damaged, especially if unanchored. Unsecured lightweight
objects become dangerous projectiles.
- Several large trees snapped or uprooted, but with greater
numbers in places where trees are shallow rooted. Several
fences and roadway signs blown over.
- Some roads impassable from large debris, and more within urban
or heavily wooded places. A few bridges, causeways, and access
routes impassable.
- Scattered power and communications outages, but more prevalent
in areas with above ground lines.

Elsewhere across Eastern West Virginia, Central and Western Maryland,
Northern and Northwestern Virginia, and District of Columbia, little
to no impact is anticipated.

Potential impacts from tornadoes are still unfolding across southern
Maryland. Remain well braced against a tornado event
having possible limited impacts. If realized,
these impacts include:
- The occurrence of isolated tornadoes can hinder the execution
of emergency plans during tropical events.
- A few places may experience tornado damage, along with power
and communications disruptions.
- Locations could realize roofs peeled off buildings, chimneys
toppled, mobile homes pushed off foundations or overturned,
large tree tops and branches snapped off, shallow-rooted trees
knocked over, moving vehicles blown off roads, and small boats
pulled from moorings.

Elsewhere across Eastern West Virginia, Central and Western Maryland,
Northern and Northwestern Virginia, and District of Columbia, little
to no impact is anticipated.

Potential impacts from the main surge event are now unfolding along
the Tidal Potomac River and western shore of the Chesapeake Bay.
Remain well away from locally hazardous surge having moderate impacts. If
realized, these impacts include:
- Localized inundation with storm surge flooding mainly along
immediate shorelines and in low-lying spots, or in areas
farther inland near where higher surge waters move ashore.
- Sections of near-shore roads and parking lots become overspread
with surge water. Driving conditions dangerous in places where
surge water covers the road.
- Moderate beach erosion. Heavy surf also breaching dunes, mainly
in usually vulnerable locations. Strong rip currents.
- Minor to locally moderate damage to marinas, docks, boardwalks,
and piers. A few small craft broken away from moorings.


If you are prone to flooding or in an area under a coastal flood warning
be prepared for the possibility of a quick and dramatic
rise in water levels.

If a tornado warning is issued for your area, quickly move to the
safest place within your shelter. Protect your head and body.

- For information on appropriate preparations see
- For information on creating an emergency plan see
- For additional disaster preparedness information see


The next local statement will be issued by the National Weather
Service in Baltimore MD/Washington DC around 830 AM EDT, or sooner if
conditions warrant.

iNWS is an experimental service intended for NWS core partners, including emergency managers, community leaders and other government agencies only. You are encouraged to complete a short survey on iNWS. See the iNWS Service Description Document for more information.