Note:
The expiration time in the watch graphic is amended if the watch is
replaced, cancelled or extended.
Note: Click for
Watch Status Reports.
SEL9
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 639
NWS Storm Prediction Center Norman OK
805 PM EDT Sat Aug 12 2023
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
The Maryland Panhandle
Southeast Ohio
Southwest and south central Pennsylvania
Northern West Virginia
* Effective this Saturday night and Sunday morning from 805 PM
until 200 AM EDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Scattered large hail events to 1.5 inches in diameter possible
A tornado or two possible
SUMMARY...Scattered supercells and storm clusters will persist
through the early overnight hours as storms spread to the east and
east-southeast. Damaging winds and large hail will be the main
threats, though an isolated tornado or two could occur through about
9-10 pm EDT.
The severe thunderstorm watch area is approximately along and 35
statute miles north and south of a line from 25 miles north of
Parkersburg WV to 20 miles north of Hagerstown MD. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU9).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
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.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 634...WW 636...WW
637...WW 638...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
29030.
...Thompson
SEL9
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 639
NWS Storm Prediction Center Norman OK
805 PM EDT Sat Aug 12 2023
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
The Maryland Panhandle
Southeast Ohio
Southwest and south central Pennsylvania
Northern West Virginia
* Effective this Saturday night and Sunday morning from 805 PM
until 200 AM EDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Scattered large hail events to 1.5 inches in diameter possible
A tornado or two possible
SUMMARY...Scattered supercells and storm clusters will persist
through the early overnight hours as storms spread to the east and
east-southeast. Damaging winds and large hail will be the main
threats, though an isolated tornado or two could occur through about
9-10 pm EDT.
The severe thunderstorm watch area is approximately along and 35
statute miles north and south of a line from 25 miles north of
Parkersburg WV to 20 miles north of Hagerstown MD. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU9).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
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.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 634...WW 636...WW
637...WW 638...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
29030.
...Thompson
Note:
The Aviation Watch (SAW) product is an approximation to the watch area.
The actual watch is depicted by the shaded areas.
SAW9
WW 639 SEVERE TSTM MD OH PA WV 130005Z - 130600Z
AXIS..35 STATUTE MILES NORTH AND SOUTH OF LINE..
25N PKB/PARKERSBURG WV/ - 20N HGR/HAGERSTOWN MD/
..AVIATION COORDS.. 30NM N/S /34WSW AIR - 35WSW HAR/
HAIL SURFACE AND ALOFT..1.5 INCHES. WIND GUSTS..60 KNOTS.
MAX TOPS TO 500. MEAN STORM MOTION VECTOR 29030.
LAT...LON 40228143 40507772 39487772 39218143
THIS IS AN APPROXIMATION TO THE WATCH AREA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE WOUS64 KWNS
FOR WOU9.
Watch 639 Status Report Messages:
STATUS REPORT #2 ON WW 639
VALID 130240Z - 130340Z
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 SSE PKB
TO 30 ENE MGW TO 20 SSW AOO TO 30 ESE AOO TO 35 WNW CXY.
..LYONS..08/13/23
ATTN...WFO...LWX...RLX...PBZ...CTP...
&&
STATUS REPORT FOR WS 639
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MDC001-023-043-130340-
MD
. MARYLAND COUNTIES INCLUDED ARE
ALLEGANY GARRETT WASHINGTON
$$
PAC009-055-057-130340-
PA
. PENNSYLVANIA COUNTIES INCLUDED ARE
BEDFORD FRANKLIN FULTON
$$
WVC001-003-017-023-027-031-033-057-065-077-085-091-093-105-
130340-
WV
. WEST VIRGINIA COUNTIES INCLUDED ARE
BARBOUR BERKELEY DODDRIDGE
GRANT HAMPSHIRE HARDY
HARRISON MINERAL MORGAN
PRESTON RITCHIE TAYLOR
TUCKER WIRT
$$
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
$$
STATUS REPORT #1 ON WW 639
VALID 130105Z - 130240Z
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 ENE ZZV
TO 35 NNW AOO.
..LYONS..08/13/23
ATTN...WFO...LWX...RLX...PBZ...CTP...
&&
STATUS REPORT FOR WS 639
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MDC001-023-043-130240-
MD
. MARYLAND COUNTIES INCLUDED ARE
ALLEGANY GARRETT WASHINGTON
$$
OHC009-013-105-111-115-121-167-130240-
OH
. OHIO COUNTIES INCLUDED ARE
ATHENS BELMONT MEIGS
MONROE MORGAN NOBLE
WASHINGTON
$$
PAC009-013-021-051-055-057-059-061-063-111-125-129-130240-
PA
. PENNSYLVANIA COUNTIES INCLUDED ARE
BEDFORD BLAIR CAMBRIA
FAYETTE FRANKLIN FULTON
GREENE HUNTINGDON INDIANA
SOMERSET WASHINGTON WESTMORELAND
$$
WVC001-003-017-023-027-031-033-049-051-057-061-065-069-073-077-
085-091-093-095-103-105-107-130240-
WV
. WEST VIRGINIA COUNTIES INCLUDED ARE
BARBOUR BERKELEY DODDRIDGE
GRANT HAMPSHIRE HARDY
HARRISON MARION MARSHALL
MINERAL MONONGALIA MORGAN
OHIO PLEASANTS PRESTON
RITCHIE TAYLOR TUCKER
TYLER WETZEL WIRT
WOOD
$$
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 (20%)
|
Probability of 1 or more strong (EF2-EF5) tornadoes
|
Low (5%)
|
Wind
Probability of 10 or more severe wind events
|
Mod (50%)
|
Probability of 1 or more wind events > 65 knots
|
Low (20%)
|
Hail
Probability of 10 or more severe hail events
|
Mod (40%)
|
Probability of 1 or more hailstones > 2 inches
|
Low (20%)
|
Combined Severe Hail/Wind
Probability of 6 or more combined severe hail/wind events
|
High (80%)
|
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% (EF2-EF5 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 
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