Note:
The expiration time in the watch graphic is amended if the watch is
replaced, cancelled or extended.
Note: Click for
Watch Status Reports.
SEL7
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 137
NWS STORM PREDICTION CENTER NORMAN OK
1200 AM EDT THU MAR 20 2008
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
DISTRICT OF COLUMBIA
CENTRAL MARYLAND
NORTHEAST VIRGINIA
COASTAL WATERS
EFFECTIVE THIS THURSDAY MORNING FROM MIDNIGHT UNTIL 400 AM EDT.
HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 40
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH
NORTHEAST OF BALTIMORE MARYLAND TO 55 MILES SOUTH SOUTHWEST OF
WASHINGTON DISTRICT OF COLUM. FOR A COMPLETE DEPICTION OF THE
WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.
DISCUSSION...LOW-TOPPED CONVECTIVE BAND ACROSS CENTRAL/N CENTRAL VA
HAS INTENSIFIED SOME IN THE PAST HOUR. THOUGH INSTABILITY REMAINS
QUITE MARGINAL...55-70 KT FLOW COULD BE TRANSPORTED TO THE SURFACE
IN THE HEAVIER PRECIPITATION CORES.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 350. MEAN STORM
MOTION VECTOR 25045.
...THOMPSON
SEL7
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 137
NWS STORM PREDICTION CENTER NORMAN OK
1200 AM EDT THU MAR 20 2008
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
DISTRICT OF COLUMBIA
CENTRAL MARYLAND
NORTHEAST VIRGINIA
COASTAL WATERS
EFFECTIVE THIS THURSDAY MORNING FROM MIDNIGHT UNTIL 400 AM EDT.
HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 40
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH
NORTHEAST OF BALTIMORE MARYLAND TO 55 MILES SOUTH SOUTHWEST OF
WASHINGTON DISTRICT OF COLUM. FOR A COMPLETE DEPICTION OF THE
WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.
DISCUSSION...LOW-TOPPED CONVECTIVE BAND ACROSS CENTRAL/N CENTRAL VA
HAS INTENSIFIED SOME IN THE PAST HOUR. THOUGH INSTABILITY REMAINS
QUITE MARGINAL...55-70 KT FLOW COULD BE TRANSPORTED TO THE SURFACE
IN THE HEAVIER PRECIPITATION CORES.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 350. MEAN STORM
MOTION VECTOR 25045.
...THOMPSON
Note:
The Aviation Watch (SAW) product is an approximation to the watch area.
The actual watch is depicted by the shaded areas.
SAW7
WW 137 SEVERE TSTM DC MD VA CW 200400Z - 200800Z
AXIS..40 STATUTE MILES EAST AND WEST OF LINE..
35NNE BWI/BALTIMORE MD/ - 55SSW DCA/WASHINGTON DC/
..AVIATION COORDS.. 35NM E/W /27ENE EMI - 37N RIC/
HAIL SURFACE AND ALOFT..0.5 INCH. WIND GUSTS..60 KNOTS.
MAX TOPS TO 350. MEAN STORM MOTION VECTOR 25045.
LAT...LON 39657566 38117668 38117815 39657716
THIS IS AN APPROXIMATION TO THE WATCH AREA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE WOUS64 KWNS
FOR WOU7.
Watch 137 Status Report Messages:
STATUS REPORT #3 ON WW 137
VALID 200630Z - 200740Z
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 SW NHK TO
35 NNE BWI.
..KERR..03/20/08
ATTN...WFO...LWX...
&&
STATUS REPORT FOR WS 137
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MDC009-025-037-200740-
MD
. MARYLAND COUNTIES INCLUDED ARE
CALVERT HARFORD ST. MARYS
$$
ANZ530-533-534-537-200740-
CW
. ADJACENT COASTAL WATERS INCLUDED ARE
CHESAPEAKE BAY NORTH OF POOLES ISLAND MD
CHESAPEAKE BAY FROM NORTH BEACH TO DRUM POINT MD
CHESAPEAKE BAY FROM DRUM POINT MD TO SMITH POINT VA
TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA
$$
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
$$
STATUS REPORT #2 ON WW 137
VALID 200540Z - 200640Z
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
..KERR..03/20/08
ATTN...WFO...LWX...
&&
STATUS REPORT FOR WS 137
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
DCC001-200640-
DC
. DISTRICT OF COLUMBIA COUNTIES INCLUDED ARE
DISTRICT OF COLUMBIA
$$
MDC003-005-009-013-017-025-027-031-033-037-510-200640-
MD
. MARYLAND COUNTIES INCLUDED ARE
ANNE ARUNDEL BALTIMORE CALVERT
CARROLL CHARLES HARFORD
HOWARD MONTGOMERY PRINCE GEORGES
ST. MARYS
MARYLAND INDEPENDENT CITIES INCLUDED ARE
BALTIMORE CITY
$$
VAC013-059-099-153-177-179-510-600-610-630-683-685-200640-
VA
. VIRGINIA COUNTIES INCLUDED ARE
ARLINGTON FAIRFAX KING GEORGE
PRINCE WILLIAM SPOTSYLVANIA STAFFORD
VIRGINIA INDEPENDENT CITIES INCLUDED ARE
ALEXANDRIA FAIRFAX FALLS CHURCH
FREDERICKSBURG MANASSAS MANASSAS PARK
$$
ANZ530-531-532-533-534-535-536-537-200640-
CW
. ADJACENT COASTAL WATERS INCLUDED ARE
CHESAPEAKE BAY NORTH OF POOLES ISLAND MD
CHESAPEAKE BAY FROM POOLES ISLAND TO SANDY POINT MD
CHESAPEAKE BAY FROM SANDY POINT TO NORTH BEACH MD
CHESAPEAKE BAY FROM NORTH BEACH TO DRUM POINT MD
CHESAPEAKE BAY FROM DRUM POINT MD TO SMITH POINT VA
TIDAL POTOMAC FROM KEY BRIDGE TO INDIAN HEAD MD
TIDAL POTOMAC FROM INDIAN HEAD TO COBB ISLAND MD
TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA
$$
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
$$
STATUS REPORT #1 ON WW 137
VALID 200435Z - 200540Z
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
..BROYLES..03/20/08
ATTN...WFO...LWX...
&&
STATUS REPORT FOR WS 137
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
DCC001-200540-
DC
. DISTRICT OF COLUMBIA COUNTIES INCLUDED ARE
DISTRICT OF COLUMBIA
$$
MDC003-005-009-013-017-025-027-031-033-037-510-200540-
MD
. MARYLAND COUNTIES INCLUDED ARE
ANNE ARUNDEL BALTIMORE CALVERT
CARROLL CHARLES HARFORD
HOWARD MONTGOMERY PRINCE GEORGES
ST. MARYS
MARYLAND INDEPENDENT CITIES INCLUDED ARE
BALTIMORE CITY
$$
VAC013-059-099-153-177-179-510-600-610-630-683-685-200540-
VA
. VIRGINIA COUNTIES INCLUDED ARE
ARLINGTON FAIRFAX KING GEORGE
PRINCE WILLIAM SPOTSYLVANIA STAFFORD
VIRGINIA INDEPENDENT CITIES INCLUDED ARE
ALEXANDRIA FAIRFAX FALLS CHURCH
FREDERICKSBURG MANASSAS MANASSAS PARK
$$
ANZ530-531-532-533-534-535-536-537-200540-
CW
. ADJACENT COASTAL WATERS INCLUDED ARE
CHESAPEAKE BAY NORTH OF POOLES ISLAND MD
CHESAPEAKE BAY FROM POOLES ISLAND TO SANDY POINT MD
CHESAPEAKE BAY FROM SANDY POINT TO NORTH BEACH MD
CHESAPEAKE BAY FROM NORTH BEACH TO DRUM POINT MD
CHESAPEAKE BAY FROM DRUM POINT MD TO SMITH POINT VA
TIDAL POTOMAC FROM KEY BRIDGE TO INDIAN HEAD MD
TIDAL POTOMAC FROM INDIAN HEAD TO COBB ISLAND MD
TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA
$$
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
$$
Note:
Click for Complete Product Text.
Tornadoes
Probability of 2 or more tornadoes
|
Low (<5%)
|
Probability of 1 or more strong (F2-F5) tornadoes
|
Low (<2%)
|
Wind
Probability of 10 or more severe wind events
|
Mod (30%)
|
Probability of 1 or more wind events > 65 knots
|
Mod (30%)
|
Hail
Probability of 10 or more severe hail events
|
Low (<5%)
|
Probability
of 1 or
more hailstones > 2 inches
|
Low (<5%)
|
Combined Severe Hail/Wind
Probability of 6 or more combined severe hail/wind events
|
Mod (50%)
|
For each watch, probabilities for particular events inside the watch
(listed above in each table) are determined by the issuing forecaster.
The "Low" category contains probability values ranging from less than 2%
to 20% (F2-F5 tornadoes), less than 5% to 20% (all other probabilities),
"Moderate" from 30% to 60%, and "High" from 70% to greater than 95%.
High values are bolded and lighter in color to provide awareness of
an increased threat for a particular event.
weather.gov 
