Tornadoes · United States · Maryland · 2011

EF1 tornado, New London to Melrose, Maryland, April 16, 2011

Name: EF1 tornado, New London to Melrose, Maryland, April 16, 2011
Start: 2011-04-16T23:47:00.000Z
End: 2011-04-16T23:51:00.000Z
Location: New London to Melrose, Maryland

From New London to Melrose, this EF1 tornado ran 3.5 miles across Carroll and Frederick counties on April 16, 2011, touching down at 7:47 PM EDT and reaching 50 yards wide. It killed nobody, and did $30,000 of property damage.

The rating scale

Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

EF065 to 85 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mphthis tornado
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
EF2111 to 135 mph
Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
EF3136 to 165 mph
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
EF5over 200 mph
Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.
Unrated
The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

The record

Rating: EF1
Date: April 16, 2011
Touchdown: 7:47 PM EDT (23:47 UTC)
Lifted: 7:51 PM EDT (23:51 UTC)
On the ground: 4 minutes
Path length: 3.5 miles (5.6 km)
Path width: 50 yards (46 m)
Deaths: 0
Injuries: 0
Property damage: $30,000
Counties: Carroll and Frederick counties
Touchdown point: 39.436, -77.148
Lift-off point: 39.459, -77.090
Record number: 1104161747-01

What the Weather Service recorded

Strong low pressure over the Midwest remained cutoff from the jet stream on the 16th. The warm front associated with this system passed through during the morning. Warm and moist southerly winds behind the front provided moderate amounts of instability. The instability combined with forcing from the low for showers and thunderstorms to develop. ||There was enough instability along with strong winds aloft for some thunderstorms to become severe.

A detached garage collapsed along New London Road. Shingles and siding were removed from a single-family home and softwood trees were snapped along New London Road. |Numerous hardwood trees were uprooted or snapped and barns were damaged or destroyed.

Roofing panels were removed from a detached garage near Detrick Road and Old Annapolis Road. Six or more softwood trees were snapped and pieces of large limbs and plywood were impaled in adjacent roofs.

Substantial tree damage was noted near Talbot Run road. Pine trees were snapped near Buffalo Road and there was also a report of siding and trim torn from a home near Buffalo Road.

Tree damage was found near the intersection of MD-26 and MD-27. A power pole was also snapped near the intersection.

Dozens of trees were snapped along Deep Run Road. A roof was partially removed from a barn along Geeting Road and numerous trees were down. Several trees and large branches were also down at the Grand Valley Farms subdivision. A large tree fell on a home rendering the home uninhabitable. The tornado also snapped trees and partially removed another roof from a barn along Band Hall Hill Road.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

The warnings

1 minute of warning. NWS LWX issued a tornado warning for this county at 23:46 UTC, 1 minute before the tornado touched down, in force until 00:00 UTC.

The county was under a tornado watch, issued at 17:29 UTC and running to 01:00 UTC.

Issued (UTC)	Expired	Product	Office
10:38 UTC	21:00 UTC	Wind Advisory	LWX
17:29 UTC	01:00 UTC	Tornado Watch	LWX
18:00 UTC	02:01 UTC	Flash Flood Watch	LWX
20:21 UTC	21:00 UTC	Severe Thunderstorm Warning	LWX
20:53 UTC	01:45 UTC	Flood Warning	LWX
20:59 UTC	21:45 UTC	Severe Thunderstorm Warning	LWX
23:01 UTC	23:45 UTC	Severe Thunderstorm Warning	LWX
23:14 UTC	23:45 UTC	Tornado Warning	LWX
23:38 UTC	00:30 UTC	Severe Thunderstorm Warning	LWX
23:46 UTC	00:00 UTC	Tornado Warning	LWX
01:48 UTC	14:45 UTC	Flood Warning	LWX

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The forecast that day

The Storm Prediction Center had this point in a Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 20:03 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

What forecasters said that day

The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Baltimore/Washington wrote its last area forecast discussion before the tornado touched down at Apr 16, 7:15 PM EDT, 32 minutes earlier.

Area forecast discussion, Apr 16, 7:15 PM EDT, 32 minutes before

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
715 PM EDT SAT APR 16 2011

.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE MID ATLANTIC THIS EVENING. HIGH
PRESSURE RETURNS SUNDAY AND MONDAY AND MOVES OFFSHORE ON TUESDAY.
A COLD FRONT WILL MOVE THROUGH THE REGION ON WEDNESDAY...WITH HIGH
PRESSURE BUILDING IN FOR THE REMAINDER OF THE WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
UPDATE...HEADLINE CHANGES. TOR WATCH TRUNCATED WEST OF THE BLUE
RIDGE. SAME FOR THE FLOOD WATCH MINUS THE NRN SHENANDOAH VLY. THE
LAST LINE OF CONVECTION NOW CLEARING THE BLUE RIDGE AND WILL
CONTINUE ON TOWARD THE I-95 CORRIDOR - REACHING THE METRO AREAS
BETWEEN 8-10 PM. PORTIONS OF THIS LINE MAY STILL PRODUCE SEVERE WX
/MAINLY WIND DAMAGE AND SOME SMALL HAIL AT THIS POINT/. THE SHARP
HELICITY VALUES FROM THE VERY TURBULENT ATMS MAY DEVELOP A FEW
QUICK CIRCULATIONS THAT COULD BECOME TORNADIC.

FROM PREV DISC...
LINES OF STORMS WILL CONTINUE EASTWARD INTO THE METRO AREAS
DURING THE REMAINDER OF THE AFTERNOON INTO THE EVENING HOURS.
THUNDERSTORMS ALONG THIS LINE WILL BE CAPABLE OF PRODUCING
DAMAGING WIND GUSTS...AND A FEW TORNADOES. THE POTENTIAL FOR
SEVERE WEATHER SHOULD DIMINISH AFTER 8 PM. SHOWERS WILL LINGER
UNTIL THE FROPA LATER THIS EVENING FOR MOST AREAS THIS EVENING. A
FEW UPSLOPE RA/SN SHOWERS POSSIBLE ALONG THE WESTERN SLOPES OF THE
POTOMAC HIGHLANDS OVERNIGHT.

STRONG SE WINDS WILL CONTINUE THIS AFTERNOON. OCCASIONAL GUSTS TO
AROUND 50 MPH HAVE BEEN REPORTED IN THE WIND ADVISORY AREA.
OUTSIDE THE WIND ADVISORY...FREQUENT GUSTS AROUND 30 KT HAVE BEEN
REPORTED. WILL GO AHEAD AND KEEP THE WIND ADVISORY IN EFFECT.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH 6 PM SUNDAY/...
HIGH PRESSURE WILL BUILD IN ACROSS THE CWFA ON SUNDAY. PRECIP
ALONG THE WESTERN SLOPES SHOULD END DURING THE EARLY MORNING
HOURS. WINDS MAY BE AN ISSUE TOMORROW...AND DO HAVE NEAR WIND
ADVISORY CRITERIA ACROSS THE HIGHER ELEVATIONS AND MASON DIXON
LINE. A WIND ADVISORY MAY BE NEEDED. EVEN IF WINDS DO NOT REACH
CRITERIA...WITH THE SATURATED SOILS...DOWNED TREES WILL BE AN
ISSUE.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
A STATIONARY BOUNDARY WILL REMAIN NEAR THE MASON DIXON LINE EARLY
NEXT WEEK...BRINGING A CHANCE FOR SHOWERS ACROSS THE NORTHERN
PORTION OF THE CWA. DRY AND MILD CONDITIONS ARE EXPECTED FURTHER
SOUTH. THE STATIONARY BOUNDARY WILL MOVE NORTH AS A WARM FRONT
WEDNESDAY AND IT WILL TURN WARM AND BREEZY WEDNESDAY AFTERNOON
ACROSS THE ENTIRE AREA. A COLD FRONT WILL APPROACH THE AREA LATER
WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT...BRINGING POSSIBLE SHOWERS
AND THUNDERSTORMS.

HIGH PRESSURE WILL BRIEFLY BUILD OVERHEAD THURSDAY BEFORE MOVING OFF
THE COAST FRIDAY INTO THE WEEKEND. AN ONSHORE FLOW WILL BRING MORE
CLOUDS ALONG WITH THE CHANCE FOR RAIN DURING THIS TIME.

&&

.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
WIDESPREAD SUB VFR CONDITIONS THIS EVENING AS A COLD FRONT MOVES
ACROSS THE MID ATLANTIC. THUNDERSTORMS WILL BE CAPABLE OF LOW
CIGS/VSBYS IN THE HEAVY RAIN. VERY GUSTY WINDS IN THUNDERSTORMS LIKELY.

IN ADDITION TO THE GUSTY THUNDERSTORMS...GRADIENT WINDS WILL ALSO
BE AN ISSUE. STRONG SE WINDS WILL CONTINUE WITH FREQUENT GUSTS TO
AROUND 30 KT LIKELY. AFTER THE FRONT...WINDS WILL SHIFT AROUND TO
THE WEST. GUSTY WINDS OUT OF THE WEST ARE ANTICIPATED
TOMORROW...WITH FREQUENT GUSTS BETWEEN 30 AND 35 KT.

VFR CONDITIONS EXPECTED FOR EARLY NEXT WEEK. A COLD FRONT WILL BRING
A CHANCE FOR SHOWERS AND THUNDERSTORMS LATER WEDNESDAY INTO
WEDNESDAY NIGHT.

&&

.MARINE...
STRONG SE WINDS CONTINUE ACROSS THE WATERS THIS AFTERNOON. THE SE
FLOW WILL CONTNUE UNTIL AFTER A FRONTAL PASSAGE THIS EVENING.
FREQUEST GUSTS TO BETWEEN 35 AND 40 KT HAVE BEEN REPORTED. BEHIND
THE FROPA LATE THIS EVENING...WINDS MAY DIP BELOW GALE FORCE FOR A
FEW HOURS BUT WILL SHIFT TO THE WEST. WINDS MAY APPROACH GALE
FORCE AGAIN ON SUNDAY.

A SMALL CRAFT ADVISORY MAY BE WARRANTED FOR THE WATERS SUNDAY
NIGHT. HIGH PRESSURE WILL BUILD OVER THE WATERS EARLY NEXT WEEK. A
COLD FRONT WILL PASS THROUGH LATER WEDNESDAY. A SMALL CRAFT ADVISORY
MAY BE WARRANTED FOR THE WATERS WEDNESDAY INTO WEDNESDAY NIGHT.

&&

.HYDROLOGY...
FLASH FLOOD WATCH REMAINS IN EFFECT FOR AREAS MAINLY ALONG AND
WEST OF THE INTERSTATE 95 CORRIDOR. REPORTS OF FLOODING CONTINUE
TO COME INTO THE OFFICE THIS AFTERNOON. WIDESPREAD VALUES BETWEEN
ONE AND THREE INCHES LIKELY...WITH LOCALLY HIGHER AMOUNTS
EXPECTED.

&&

.TIDES/COASTAL FLOODING...
WATER LEVELS ARE RUNNING AROUND 2 FT ABOVE NORMAL THIS AFTERNOON.
HIGH TIDE HASN'T EVEN OCCURED IN MANY PLACES...AND EXPECT WATER
LEVELS TO CONTINUE CREEPING UPWARDS. HAVE ISSUED A COASTAL FLOOD
WARNING FOR THE ENTIRE TIDAL POTOMAC AND WESTERN SHORE OF THE
MARYLAND CHESAPEAKE BAY. DO THINK WATER LEVELS WILL REMAIN
ELEVEATED THROUGH THE EVENING AND SUNDAY MORNING HIGH TIDE CYCLES.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...COASTAL FLOOD WARNING UNTIL 11 AM EDT SUNDAY FOR DCZ001.
     FLASH FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR DCZ001.
MD...COASTAL FLOOD WARNING UNTIL 11 AM EDT SUNDAY FOR MDZ007-011-
     013-014-016>018.
     FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR MDZ003.
     FLASH FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR MDZ004>007-
     009>011.
VA...COASTAL FLOOD WARNING UNTIL 11 AM EDT SUNDAY FOR VAZ052>055-
     057.
     FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR VAZ028>031-
     036>040-050-051.
     FLASH FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR VAZ042-
     052>056-501-502.
WV...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR WVZ051>053.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
     ANZ530>543.
     GALE WARNING UNTIL 6 AM EDT SUNDAY FOR ANZ530>543.

&&

UPDATE...GMS
PREV DISC...LISTEMAA/LASORSA

Hazardous weather outlook, Apr 16, 7:10 PM EDT, 37 minutes before

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
710 PM EDT SAT APR 16 2011

ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057-
171115-
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-
PATAPSCO RIVER INCLUDING BALTIMORE HARBOR-
CHESTER RIVER TO QUEENSTOWN MD-EASTERN BAY-
CHOPTANK RIVER TO CAMBRIDGE MD AND THE LITTLE CHOPTANK RIVER-
PATUXENT RIVER TO BROOMES ISLAND MD-
TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH
ISLAND-DISTRICT OF COLUMBIA-NORTHERN BALTIMORE-HARFORD-
SOUTHERN BALTIMORE-PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS-
CALVERT-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-
ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA-
KING GEORGE-
710 PM EDT SAT APR 16 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MARYLAND PORTION OF THE
CHESAPEAKE BAY...TIDAL POTOMAC RIVER...AND ADJACENT COUNTIES IN
CENTRAL MARYLAND AND NORTHERN VIRGINIA AS WELL AS THE DISTRICT OF
COLUMBIA.

.DAY ONE...TONIGHT

A COASTAL FLOOD WARNING HAS BEEN ISSUED ALONG THE TIDAL POTOMAC
AND WESTERN SHORE OF THE CHESAPEAKE BAY THROUGH TONIGHT. WATER
LEVELS OF 2 TO 3 FEET ABOVE NORMAL ARE ANTICIPATED. PLEASE REFER
TO THE LATEST HAZARD MESSAGE /CFWLWX/ FOR DETAILS.

A GALE WARNING IS IN EFFECT THROUGH TONIGHT FOR THE MARYLAND
CHESAPEAKE BAY AND TIDAL POTOMAC RIVER.

A TORNADO WATCH IS IN EFFECT UNTIL 9 PM FOR THE OUTLOOK AREA.
THUNDERSTORMS WILL BE CAPABLE OF TORNADOES AND DAMAGING WIND
GUSTS. HEAVY RAIN IN THESE STORMS ALSO COULD LEAD TO FLASH
FLOODING MAINLY ALONG AND WEST OF THE INTERSTATE 95 CORRIDOR.

SPECIAL MARINE WARNINGS ARE LIKELY LATE THIS AFTERNOON AND EVENING
AS THUNDERSTORMS CROSS THE WATERS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE COASTAL FLOOD WARNING REMAINS IN EFFECT THROUGH 11 AM SUNDAY
MORNING.

A SMALL CRAFT ADVISORY IS IN EFFECT SUNDAY FOR THE MARYLAND
CHESAPEAKE BAY AND TIDAL POTOMAC RIVER...BUT A PERIOD OF GALE
CONDITIONS IS POSSIBLE. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR
PORTIONS OF THE WATERS SUNDAY EVENING AND TUESDAY THROUGH
WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS HAVE BEEN ACTIVATED.

MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504-
WVZ050>053-055-501>506-171115-
WASHINGTON-FREDERICK MD-CARROLL-MONTGOMERY-HOWARD-
EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-AUGUSTA-
ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE-NELSON-
ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-LOUDOUN-ORANGE-CULPEPER-
NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND-
EASTERN HIGHLAND-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-HARDY-
WESTERN GRANT-EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL-
WESTERN PENDLETON-EASTERN PENDLETON-
710 PM EDT SAT APR 16 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN WEST VIRGINIA...
NORTHERN AND CENTRAL VIRGINIA...AND CENTRAL AND WESTERN MARYLAND
WITH THE EXCEPTION OF GARRETT COUNTY.

.DAY ONE...TONIGHT

A TORNADO WATCH IS IN EFFECT UNTIL 9 PM FOR AREAS EAST OF THE BLUE
RIDGE IN NORTHERN VIRGINIA AND EASTERN MARYLAND. THUNDERSTORMS
WILL BE CAPABLE OF TORNADOES AND DAMAGING WIND GUSTS.

HEAVY RAIN WITH THESE STORMS COULD LEAD TO FLASH FLOODING AND
RIVER FLOODING. A FLASH FLOOD WATCH IS IN EFFECT FOR AREAS EAST OF
THE BLUE RIDGE AND THE NORTHERN SHENANDOAH VALLEY. PLEASE REFER
TO THE LATEST HAZARD MESSAGE /FFALWX/ FOR DETAILS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A WIND ADVISORY MAY BE NEEDED FOR THE POTOMAC HIGHLANDS AND ALONG
THE MASON DIXON LINE TOMORROW.

HEAVY RAIN FROM SATURDAY STORMS COULD LEAD TO MINOR RIVER
FLOODING ON SUNDAY.

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED WEDNESDAY
AFTERNOON AND EVENING PRIMARILY ALONG AND WEST OF THE BLUE RIDGE.
SOME STORMS COULD BECOME SEVERE...WITH DAMAGING WIND GUSTS AND
LARGE HAIL THE PRIMARY THREATS.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS HAVE BEEN ACTIVATED.

In the hours before

Local storm report, Apr 16, 6:41 PM EDT, 1 hour 6 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
641 PM EDT SAT APR 16 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0345 PM     FLASH FLOOD      1 S FRONT ROYAL         38.91N  78.19W
04/16/2011                   WARREN             VA   PUBLIC

            BRIDGE WASHED OUT ON CRISER ROAD AT HAPPY CREEK.

&&

EVENT NUMBER LWX1100340

JE

Local storm report, Apr 16, 6:43 PM EDT, 1 hour 4 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
643 PM EDT SAT APR 16 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0640 PM     FLOOD            2 WNW LEHEW             39.21N  78.48W
04/16/2011                   HAMPSHIRE          WV   TRAINED SPOTTER

            MEASURED 3.1 INCHS OF RAIN STORM TOTAL. SMALL STREAMS
            WERE OUT OF THEIR BANKS.

&&

EVENT NUMBER LWX1100341

BJL

Local storm report, Apr 16, 7:19 PM EDT, 28 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
719 PM EDT SAT APR 16 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0715 PM     FLOOD            1 N PURCELLVILLE        39.15N  77.71W
04/16/2011                   LOUDOUN            VA   AMATEUR RADIO

            CATOCTIN CREEK OUT OF ITS BANKS NEAR ROUTE 690

&&

EVENT NUMBER LWX1100342

JE

Special weather statement, Apr 16, 7:28 PM EDT, 19 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
728 PM EDT SAT APR 16 2011

MDZ009-VAZ036-037-039-042-050>053-501-502-170030-
MONTGOMERY MD-NELSON VA-ORANGE VA-MADISON VA-CULPEPER VA-
NORTHERN FAUQUIER VA-LOUDOUN VA-
PRINCE WILLIAM/MANASSAS/MANASSAS PARK VA-SOUTHERN FAUQUIER VA-
ALBEMARLE VA-FAIRFAX VA-
728 PM EDT SAT APR 16 2011

...STRONG THUNDERSTORMS TO AFFECT MONTGOMERY...NELSON...ORANGE...
MADISON...CULPEPER...NORTHERN FAUQUIER...LOUDOUN...PRINCE
WILLIAM/MANASSAS/MANASSAS PARK...SOUTHERN FAUQUIER...ALBEMARLE AND
FAIRFAX COUNTIES...

AT 727 PM EDT...DOPPLER RADAR INDICATED STRONG THUNDERSTORMS ALONG A
LINE EXTENDING FROM 2 MILES SOUTH OF HALFWAY TO OLD SOMERSET TO 5
MILES NORTHEAST OF GREENFIELD...MOVING NORTHEAST AT 35 MPH.

LOCATIONS IMPACTED THROUGH 8:30 PM INCLUDE NORTH GARDEN...BROAD
RUN...FIVE FORKS...WARRENTON...HOLLYMEAD...NEW BALTIMORE...
MITCHELLS...WINSTON...BRAMBLETON AND WOODRIDGE.

WIND GUSTS OF 40 TO 50 MPH AND SMALL HAIL CAN BE EXPECTED WITH THESE
STORMS.

&&

LAT...LON 3788 7894 3818 7833 3893 7775 3909 7719
      3840 7770 3814 7808 3812 7821 3789 7842
TIME...MOT...LOC 2327Z 240DEG 29KT 3890 7771 3823 7823
          3798 7874

HTS

Local storm report, Apr 16, 7:39 PM EDT, 8 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
739 PM EDT SAT APR 16 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0712 PM     TSTM WND DMG     1 W LEESBURG            39.10N  77.57W
04/16/2011                   LOUDOUN            VA   TRAINED SPOTTER

            LARGE SIGN TORN DOWN AND A LOT OF TREES BLOWN DOWN NEAR
            SOUTH KING STREET AND DAVIS AVENUE IN LEESBURG

&&

EVENT NUMBER LWX1100343

KLW

Special weather statement, Apr 16, 7:39 PM EDT, 8 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
739 PM EDT SAT APR 16 2011

MDZ004>006-009>011-170045-
CARROLL MD-NORTHERN BALTIMORE MD-FREDERICK MD-HOWARD MD-MONTGOMERY MD-
SOUTHERN BALTIMORE MD-
739 PM EDT SAT APR 16 2011

...BRIEF VERY HEAVY DOWNPOURS TO AFFECT CARROLL...WESTERN
BALTIMORE...EASTERN FREDERICK...NORTHWESTERN HOWARD...AND
NORTHWESTERN MONTGOMERY COUNTIES...

AT 739 PM EDT...DOPPLER RADAR INDICATED A LINE OF VERY HEAVY RAIN
EXTENDING FROM 3 MILES NORTH OF ROCKY RIDGE TO 2 MILES WEST OF
BOYDS...MOVING NORTHEAST AT 45 MPH.

LOCATIONS IMPACTED INCLUDE HARNEY...MONTGOMERY VILLAGE...
UNIONVILLE...UNION BRIDGE...LAYTONSVILLE...NEW WINDSOR...UNIONTOWN...
MOUNT AIRY...ROXBURY MILLS AND WOODBINE.

HEAVY RAIN WITH THIS LINE MAY REDUCE VISIBILITIES TO BELOW ONE MILE
AND MAY CAUSE PONDING OF WATER ON ROADWAYS.

&&

LAT...LON 3936 7677 3907 7740 3907 7742 3970 7737
      3973 7732 3973 7674
TIME...MOT...LOC 2339Z 239DEG 46KT 3966 7727 3919 7731

JE

The air that afternoon

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Washington/Dulle, VA (KIAD), 12:00Z

11.8 hours before the tornado, 60 km from the path. April 16, 2011.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: -81332 J/kg
Surface CAPE: 0 J/kg
Mixed-layer LCL: 533 m above ground
0-6 km bulk shear: 56 kt
0-1 km bulk shear: 40 kt
0-1 km storm-relative helicity: 473 m²/s²
0-3 km storm-relative helicity: 699 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0
0-3 km lapse rate: 4.5 K/km

Open this sounding in Storm Lab

Washington/Dulle, VA (KIAD), 00:00Z

0.2 hours after it, 60 km from the path. April 17, 2011.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.

Hodograph

Mixed-layer CAPE: 132 J/kg
Mixed-layer CIN: -18 J/kg
Surface CAPE: 48 J/kg
Mixed-layer LCL: 547 m above ground
0-6 km bulk shear: 77 kt
0-1 km bulk shear: 42 kt
0-1 km storm-relative helicity: 574 m²/s²
0-3 km storm-relative helicity: 593 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.5
0-3 km lapse rate: 5.4 K/km

Open this sounding in Storm Lab

The surface observations

Westminster (DMW), 20 km from the path, in the two hours either side.

Time (UTC)	Temp (°F)	Dew point (°F)	Wind	Gust (kt)	Pressure (mb)	Weather
21:55 UTC	59	55.4	160° 11 kt	26	1000	+TSRA
22:16 UTC	59	55.4	150° 13 kt	20	998.6	-RA
22:37 UTC	60.8	55.4	160° 14 kt	25	998.6	TSRA
22:58 UTC	60.8	55.4	150° 18 kt	27	998.3	-RA
23:19 UTC	60.8	57.2	140° 19 kt	35	997	VCTS
23:40 UTC	60.8	57.2	150° 19 kt	29	996.6
00:04 UTC	57.2	53.6	290° 22 kt	35	999.3	+VCTSRA
00:25 UTC	53.6	50	300° 5 kt		999.3	-RA
00:46 UTC	55.4	51.8	340° 3 kt		999.3	RA
01:07 UTC	53.6	51.8	280° 3 kt		1000	RA
01:28 UTC	55.4	51.8			1000.7	RA

From the Iowa Environmental Mesonet's archive of airport observations.

The radar

The Sterling radar (KLWX), 61 km away, was scanning. The volume nearest the touchdown began at 23:45 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)	Report	Where	County	Remark
21:00 UTC	NON-TSTM WND DMG	Elkridge	Howard, MD	TREES DOWN AT ELK RIDGE AND COLUMBIA.
21:17 UTC	FLOOD	2 Ne Granite	Baltimore, MD	WATER ON ROAD AT 8800 MILLER ISLAND ROAD.
21:40 UTC	TSTM WND DMG	Finksburg	Carroll, MD	TREES DOWN NEAR ROUTE 140.
21:45 UTC	NON-TSTM WND DMG	Carney	Baltimore, MD	TREE DOWN.
21:48 UTC	TSTM WND DMG	2 Ene Carrollton	Carroll, MD	LARGE 3 TO 4 INCH DIAMETER BRANCHES BROUGHT DOWN FROM THUNDERSTORM WINDS.
22:00 UTC	FLOOD	Leitersburg	Washington, MD	HARPERS FERRY ROAD CLOSED DUE TO FLOODING IN NUMEROUS AREAS.
22:10 UTC	NON-TSTM WND DMG	Bethesda	Montgomery, MD	TREES DOWN IN BETHESDA DUE TO GUSTY WINDS.
22:30 UTC	FLOOD	Baltimore	Baltimore City, MD	ALICEANNA STREET CLOSED DUE TO FLOODING
23:30 UTC	TSTM WND DMG	Frederick	Frederick, MD	TREES SNAPPED UPROOTED
23:30 UTC	FLOOD	1 Nne Thurmont	Frederick, MD	RODDY CREEK ROAD WAS CLOSED NEAR ROUTE 15.
23:30 UTC	FLOOD	Myersville	Frederick, MD	HIGH WATER RESCUE OF A PERSON IN A SUBMERGED VEHICLE ON ROUTE 40 IN VICINITY OF CATOCTIN CREEK.
23:30 UTC	FLOOD	Thurmont	Frederick, MD	HIGH WATER RESCUE IN NORTHWEST FREDERICK COUNTY.
23:36 UTC	TORNADO	2 Nne New Market	Frederick, MD	TORNADO CONFIRMED EF1. MAX WINDS 90-100 MPH. MAX WIDTH 50 YARDS. PATH LENGTH 1 MILE. NUMEROUS TREES UPROOTED. BARNS PARTIALLY DESTROYED. ROOF DAMAGE TO RESIDENCE.
23:38 UTC	TORNADO	3 Ne New Market	Frederick, MD	TORNADO CONFIRMED EF-1. MAX WINDS 90-100 MPH. MAX WIDTH 75 YARDS. PATH LENGTH 5 MILES. SEVERAL SMALL BARNS DESTROYED. ROOFS PARTIALLY OFF OF WAREHOUSES. NUMEROUS TREES SNAPPED.
23:43 UTC	TSTM WND DMG	3 S Unionville	Frederick, MD	SEVERAL DOWNED AND SNAPPED TREES NEAR INTERSECTION OF WOODVILLE ROAD AND GLISSANS MILL ROAD.
23:44 UTC	TORNADO	3 Se Unionville	Frederick, MD	TORNADO CONFIRMED EF-0. MAX WINDS 70-80 MPH. MAX WIDTH 50 YARDS. PATH LENGTH 3 MILES. TREES SNAPPED AND SHINGLES REMOVED FROM RESIDENCE. TORNADO ENDED IN CARROLL COUNTY.
23:45 UTC	TSTM WND DMG	3 Sse Unionville	Frederick, MD	LARGE BRANCHES DOWN.
23:46 UTC	TSTM WND DMG	3 W Winfield	Carroll, MD	TREE DOWN
23:48 UTC	TSTM WND DMG	2 Wnw Winfield	Carroll, MD	2 SMALL TREES DOWN.
23:49 UTC	TSTM WND DMG	2 Wnw Winfield	Carroll, MD	TELEPHONE POLE SNAPPED
23:50 UTC	TSTM WND DMG	2 W Winfield	Carroll, MD	BARN MOVED OFF FOUNDATION AND ONTO MD HWY 27 NEAR BRADDOCK RD ALONG WITH TREE DAMAGE.
23:53 UTC	TSTM WND DMG	5 Ne Uniontown	Carroll, MD	FIFTEEN TREES DOWN ON FARM.
23:54 UTC	TSTM WND DMG	6 Ne Uniontown	Carroll, MD	TREES DOWN ON FARM.
23:55 UTC	TSTM WND DMG	6 N Westminster	Carroll, MD	2 TREES DOWN.
23:55 UTC	TSTM WND DMG	7 N Westminster	Carroll, MD	12 LARGE TREES UPROOTED
23:56 UTC	TSTM WND DMG	5 Wnw Manchester	Carroll, MD	TREE DOWN
23:56 UTC	TSTM WND DMG	6 Wnw Manchester	Carroll, MD	DOZENS OF TREES DOWNED
23:56 UTC	TORNADO	1 Sw Deep Run	Carroll, MD	TORNADO CONFIRMED EF-0. MAX WINDS 80 MPH. MAX WIDTH 200 YARDS. PATH LENGTH 2 MILES. NUMEROUS TREES UPROOTED AND SNAPPED. ONE TREE INTO HOUSE. TWO BARNS PARTIALLY UNROOFED.
23:57 UTC	TSTM WND DMG	6 Wnw Manchester	Carroll, MD	NUMEROUS TREES DOWN. BARN PARTIALLY UNROOFED. SMALL SHED FLATTENED.
23:58 UTC	TSTM WND DMG	5 Nw Manchester	Carroll, MD	SEVERAL TREES SNAPPED. BARN PARTIALLY UNROOFED.
23:58 UTC	TSTM WND DMG	5 Wnw Manchester	Carroll, MD	SEVERAL LARGE TREES DOWN. ONE INTO A HOME. SHED AND DECK DAMAGE AT ANOTHER HOME FROM LARGE BRANCHES.
23:59 UTC	TSTM WND DMG	5 Nw Manchester	Carroll, MD	4 TREES SNAPPED.
00:00 UTC	TSTM WND DMG	Westminster	Carroll, MD	NUMEROUS TREES DOWN ACROSS THE COUNTY.
00:03 UTC	TSTM WND DMG	2 Ene Carrollton	Carroll, MD	SEVERAL SMALL BRANCHES BROUGHT DOWN FROM THUNDERSTORM WINDS.
00:03 UTC	TSTM WND DMG	3 Nnw Manchester	Carroll, MD	SHINGLES AND TAR PAPER BLOWN OFF HOUSE ROOF
00:03 UTC	TORNADO	5 Wnw Manchester	Carroll, MD	TREE AND STRUCTURAL DAMAGE ON ARBOR DRIVE IN WESTMINSTER
00:04 UTC	TSTM WND DMG	4 W Lineboro	Carroll, MD	UPROOTED TREE ONTO A TRUCK. TREES TWISTED. ONE TREE 6 TO 8 INCHES IN DIAMETER BROKEN OFF. SIDING WRAPPED AROUND A TREE NEAR THE TOP. BOARD JAMMED INTO GROUND. PILLARS ON PORCH OFF SET. NEIGHBOR ACROSS STREET SUSTAINED SO
00:05 UTC	TSTM WND DMG	West Manheim	York, PA	TREE ON TRUCK...MINOR HOUSE DAMAGE
00:30 UTC	FLOOD	1 Nne Thurmont	Frederick, MD	RODDY CREEK ROAD WAS CLOSED NEAR ROUTE 15.
00:35 UTC	FLOOD	Harpers Ferry	Jefferson, WV	WATER CASCADING DOWN CHESTNUT HILL ROAD TOWARD US HIGHWAY 340. ROAD CLOSED.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the track Every 2011 tornado in Maryland Every tornado in Maryland since 1950 Warnings in force in Maryland now The forecast where you are

The other tornadoes of April 16, 2011

56 more were confirmed in the United States that day.

Date	Time	Rating	Where	Path (mi)	Width (yd)	Deaths	Injuries	Damage
April 16	4:50 AM EDT	EF1	Chattahoochee, GA	0.3	50			$250,000
April 16	6:02 AM EDT	EF1	Bibb, GA	3.5	500			$2.0 million
April 16	12:41 PM EDT	EF1	Rowan, NC	4.0	100
April 16	12:59 PM EDT	EF0	Union, NC	3.0	50
April 16	2:03 PM EDT	EF0	Rockbridge, VA	1.3	100			$6,000
April 16	2:06 PM EDT	EF1	Alamance, NC	10.7	300			$980,000
April 16	2:20 PM EDT	EF0	Augusta, VA	3.8	200			$2.2 million
April 16	1:40 PM CDT	EF2	Person, NC to VA	26.2	300		6	$1.1 million
April 16	2:53 PM EDT	EF3	Moore, NC	65.2	500	6	103	$172 million
April 16	3:25 PM EDT	EF1	Dillon, SC	1.5	440		3	$180,000
April 16	3:27 PM EDT	EF0	Clarendon, SC	9.6	40			$12,000
April 16	3:30 PM EDT	EF1	Lunenburg, VA	16.9	300			$100,000
April 16	3:33 PM EDT	EF1	Robeson, NC	0.7	50			$1.5 million
April 16	3:33 PM EDT	EF3	Hoke, NC	52.9	800	2	176	$141 million
April 16	3:47 PM EDT	EF1	Robeson, NC	1.5	352			$3.0 million
April 16	4:13 PM EDT	EF1	Clarendon, SC	8.9	50			$14,000
April 16	4:25 PM EDT	EF2	Bladen, NC	29.9	800	3	13	$11 million
April 16	4:37 PM EDT	EF1	Dinwiddie, VA	7.0	400		5	$1.5 million
April 16	4:50 PM EDT	EF1	Johnston, NC	8.6	100
April 16	4:58 PM EDT	EF2	Bladen, NC	13.1	440	1		$3.1 million
April 16	5:03 PM EDT	EF1	Berkeley, SC	7.9	120
April 16	5:12 PM EDT	EF0	Duplin, NC	0.2	30
April 16	5:12 PM EDT	EF2	Wilson, NC	9.0	200		10	$3.0 million
April 16	5:20 PM EDT	EF2	Halifax, NC	8.2	300			$1.2 million
April 16	5:32 PM EDT	EF3	Wayne, NC	20.4	400		30	$30 million
April 16	5:33 PM EDT	EF0	Columbus, NC	0.2	25
April 16	5:41 PM EDT	EF0	Georgetown, SC	0.2	30			$28,000
April 16	5:45 PM EDT	EF0	Georgetown, SC	0.6	30			$40,000
April 16	5:50 PM EDT	EF1	Southampton, VA	1.9	300			$30,000
April 16	5:53 PM EDT	EF1	Georgetown, SC	0.5	60			$100,000
April 16	5:59 PM EDT	EF1	Georgetown, SC	0.5	60			$60,000
April 16	5:59 PM EDT	EF1	Pitt, NC	3.3	75		5	$1.0 million
April 16	6:05 PM EDT	EF1	Columbus, NC	1.1	50			$35,000
April 16	6:20 PM EDT	EF0	Southampton, VA	1.8	50			$2,000
April 16	6:30 PM EDT	EF1	Middlesex, VA	1.1	400			$100,000
April 16	6:35 PM EDT	EF0	Duplin, NC	0.6	150
April 16	6:45 PM EDT	EF3	Surry, VA	26.5	800	2	24	$8.0 million
April 16	6:55 PM EDT	EF3	Bertie, NC	17.9	1,300	12	58	$3.3 million
April 16	7:05 PM EDT	EF2	Bertie, NC	17.5	500		8	$1.1 million
April 16	7:07 PM EDT	EF2	Jones, NC	2.4	200			$100,000
April 16	7:09 PM EDT	EF0	Martin, NC	0.1	75			$10,000
April 16	7:10 PM EDT	EF2	Isle of Wight, VA	22.6	400			$300,000
April 16	7:12 PM EDT	EF0	Loudoun, VA	4.1	50			$4,000
April 16	7:25 PM EDT	EF2	Middlesex, VA	2.8	400			$6.0 million
April 16	7:37 PM EDT	EF1	Frederick, MD	1.2	50			$50,000
April 16	7:38 PM EDT	EF1	Frederick, MD	4.4	50			$50,000
April 16	7:40 PM EDT	EF0	Craven, NC	0.1	30
April 16	7:51 PM EDT	EF0	Carroll, MD	1.9	75			$20,000
April 16	8:08 PM EDT	EF0	Beaufort, NC	0.6	30			$4,000
April 16	8:11 PM EDT	EF3	Onslow, NC	3.8	450		30	$9.4 million
April 16	8:20 PM EDT	EF0	York, PA	0.5	200		2	$20,000
April 16	8:43 PM EDT	EF2	Craven, NC	4.1	200		7	$4.0 million
April 16	8:52 PM EDT	EF0	Pamlico, NC	0.1	30
April 16	9:01 PM EDT	EF1	Tyrrell, NC	7.4	550			$400,000
April 16	9:30 PM EDT	EF1	Currituck, NC	2.0	200			$40,000
April 16	9:35 PM EDT	EF1	Dare, NC	0.7	250			$767,000

What this means

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

Sources

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.