sign in sign up
<<
Home , Derecho, Severe weather, Tornado emergency, Tornado warning

TOPICS

Thunderstorm/ structure

Boxology: Issuing Warnings

Severe & the threat – taking it seriously

Our tornado history & climatology

(E)F5s – how can tornadoes get that strong?

Tornado Topography

Tornado damage tracks

What worst tornado situation…here

Wrap-up

The biggest tornado – ever. How many severe warnings in a typical year?

500No. Severe Warnings – last 10 years 10-year Avg.

450 Year SVR TOR SVR TOR

4002005 152 11 267.5 29.9 2006 177 13 350 2007 297 15 -based “polygon” 3002008 290 36 warnings instituted

2502009 219 13 SVR 2010 265 31 TOR 200 2011 441 96 4/27-28 1502012 368 44 6/29 “”

1002013 211 22 2014 255 18 50(so far…)

0 2005 2006 SVR2007 = 2008Severe2009 Thunderstorm2010 2011 Warning2012 2013 2014 TOR = What is a tornado (size-wise)?

Tropopause

Answer: a very small extension of, or “output” of the much larger parent The “Core” (/wind) In a thunderstorm, the mesocyclone can be nearly the entire height of the cloud, but strongest from the middle of the cloud, down to the surface. It Profile *is* the rotating updraft. Not all meso- produce tornadoes and not all tornadoes are derived from , except the for strongest ones.

Inflow (warm)

Wall Cloud

Tornado Height comparison Supercell Tropopause

Elevated core of large hail and strong winds

45 – 50kft

Strong/deep Mesocyclone Heavy / some hail Mostly rain-free near meso

1 – 3kft Height comparison Typical Mid-Atlantic Jet Stream

Everything happens in the lowest 15-20kft, not ideal for a potent or long-lived structure – either the thunderstorm itself or a tornado.

Updrafts can still “spin”, even with all the core elements at half/two-thirds that of a normal supercell. Tropopause This creates “mini-”, having the same basic structure but more compact and less intense.

Mini-supercells can last for long distances, producing multiple tornadoes over that distance Elevated core of but usually of the EF0-1 variety (EF2 at worst). 30 – 40kft small/medium hail and strong winds Since the basic elements of the structure are weaker, the heavy rain/hail shaft usually falls closer to the Weak/shallow Heavy Rain/ updraft. This ensures the tornado has a Mesocyclone some hail better chance to be rain-wrapped than a strong supercell with lots of feature- shaping . 1 – 2kft

True, the Mid-Atlantic has plenty of low-level moisture (/) and an occasional low-level jet max (especially along/E of I-95) but all the ingredients just typically aren’t as strong as the other areas. BOXOLOGY WarnGen Warning Generation

T D W R S

We’re Surrounded…by

TIAD

TBWI

KLWX

TDCA TADW WUUS51SEVERE KLWX 082130 STATEMENT SVRLWXNATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC MDC043559 -PMVAC043 EDT -TUE069 -JUL171 -8187 2014-840 -WVC003-037-065-082215- /O.NEW.KLWX.SV.W.0150.140708T2130Z -140708T2215Z/ WVC065-082209- BULLETIN/O.CAN.KLWX.SV.W.0150.000000T0000Z - EAS ACTIVATION REQUESTED -140708T2215Z/ SEVEREMORGAN THUNDERSTORM WV- WARNING NATIONAL559 PM WEATHEREDT TUE SERVICEJUL 8 2014 BALTIMORE MD/WASHINGTON DC 530 PM EDT TUE JUL 8 2014 ...THE SEVERE THUNDERSTORM WARNING IS CANCELLED FOR MORGAN AND THEFREDERICK NATIONAL COUNTIES...ANDWEATHER SERVICE THE IN CITYSTERLING OF WINCHESTER... VIRGINIA HAS ISSUED A

* SEVERETHE THUNDERSTORM THUNDERSTORM THAT WARNING PROMPTED FOR... THE WARNING HAS EXITED THE WARNED WASHINGTONAREA. THUS COUNTYTHE SEVERE IN NORTH THUNDERSTORM CENTRAL MARYLANDWARNING ...HAS BEEN CANCELLED. FREDERICK IN NORTHWEST VIRGINIA... CLARKELAT...LON COUNTY 3884 IN 7867 NORTHWEST 3895 7855 VIRGINIA... 3904 7833 3913 7823 MORGAN 3931COUNTY 7817 IN 3944THE PANHANDLE7808 3971 OF7795 WEST 3972 VIRGINIA... 7752 JEFFERSON 3914 COUNTY 7784 3882IN THE 7820 PANHANDLE OF WEST VIRGINIA... BERKELEYTIME...MOT...LOC COUNTY IN 2159Z THE PANHANDLE270DEG 46KT OF 3972WEST 7777VIRGINIA... 3952 7778 CITY OF WINCHESTER 3926 7786 IN 3894 NORTHWEST 7805 VIRGINIA...

* UNTIL$$ 615 PM EDT

* ATMDC043 527 -PMVAC043 EDT...SEVERE-069-171- 187THUNDERSTORMS-840-WVC003 -WERE037- 082215DETECTED- ALONG A LINE EXTENDING/O.CON.KLWX.SV.W.0150.000000T0000Z FROM 12 MILES NORTH OF FISHERS-140708T2215Z/ BRIDGE TO LARGENT TO 14 MILESWASHINGTON WEST OFMD -WINCHESTERSHENANDOAH TOVA -17WARREN MILES VA WEST-FREDERICK OF STRASBURG...AND VA-CLARKE VA -WERE MOVINGJEFFERSON EAST WV AT-BERKELEY 45 MPH. WVTHIS-CITY LINE OF OFWINCHESTER IS VA CAPABLE- OF PRODUCING DAMAGING559 PM EDT WINDS TUE INJUL EXCESS 8 2014 OF 60 MPH.

* LOCATIONS...A SEVERE IMPACTED THUNDERSTORM INCLUDE... WARNING REMAINS IN EFFECT UNTIL 615 PM EDT VALLEYFOR BERKELEY VIEW...... JEFFERSON... CLARKE...WARREN AND WASHINGTON COUNTIES... ROCK GAP... VALLEYAT 558 HIGH...PM EDT...SEVERE THUNDERSTORMS WERE DETECTED ALONG A LINE NEWEXTENDING HOPE... FROM LONG MEADOW TO 6 MILES SOUTH OF WILLIAMSPORT TO STRASBURGCHARLES TOWN... TO 6 MILES EAST OF FRONT ROYAL...AND WERE MOVING EAST AT INWOOD...55 MPH.

PRECAUTIONARY/PREPAREDNESSTHESE STORMS ARE CAPABLE ACTIONS...OF PRODUCING HAIL UP TO THE SIZE OF QUARTERS AND DAMAGING WINDS IN EXCESS OF 60 MPH. THIS IS A DANGEROUS LINE OF STORMS. IF YOU ARE IN ITS PATH...MOVE INDOORSLOCATIONS TO A IMPACTEDSTURDY BUILDING INCLUDE... AND STAY AWAY FROM WINDOWS. WHEN IT IS SAFE LONGTO DO MEADOW... SO...REPORT TO LOCAL LAW ENFORCEMENT OR TO THE NATIONALCHEWSVILLE... WEATHER SERVICE. CAVETOWN... THIS SMITHSBURG...LINE OF STORMS HAS A HISTORY OF PRODUCING WIDESPREAD WIND DAMAGE. RINGGOLD... SEEK SHELTER INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS. LEITERSBURG...

&& THIS IS A DANGEROUS LINE OF STORMS. IF YOU ARE IN ITS PATH...MOVE INDOORS TO A STURDY BUILDING AND STAY AWAY FROM WINDOWS. WHEN IT IS LAT...LONSAFE TO 3972DO SO...REPORT 7752 3914 7784SEVERE 3882 WEATHER 7820 3883TO LOCAL 7881 LAW ENFORCEMENT OR TO THE 3892NATIONAL 7875 WEATHER3897 7860 SERVICE. 3905 7856 3917 7841 3921 7843 3935 7834 3947 7835 3952 7847 THIS 3955 LINE 7846 OF STORMS3955 7842 HAS 3959A HISTORY 7846 3958OF PRODUCING 7840 WIDESPREAD WIND DAMAGE. 3962 SEEK7844 SHELTER3961 7838 INSIDE 3964 A7834 STURDY 3973 STRUCTURE 7834 AND STAY AWAY FROM TIME...MOT...LOCWINDOWS. 2130Z 264DEG 38KT 3970 7837 3949 7831 3923 7839 3890 7862 LAT...LON 3884 7867 3895 7855 3904 7833 3913 7823 $$ 3931 7817 3944 7808 3971 7795 3972 7752 3914 7784 3882 7820 TIME...MOT...LOC 2159Z 270DEG 46KT 3972 7777 3952 7778 3926 7786 3894 7805 Severe Winds – the danger of leading edge gust fronts Severe Winds – the danger of leading edge gust fronts

With the speed of the gust front (40-50 mph itself – or more), you will be receiving severe winds several minutes before the first drop of rain or being under most “ominous” part of the incoming Winds along and just behind roll/shelf cloud the fast-moving can be severe without any precip. Wind damage report

The precip begins to “separate” from the outflow/gust front – which is basically outrunning the storm(s). At some point, friction works against the outflow and it dissipates or becomes less intense, but that process takes a while. Typical thunderstorm lifecycle …in terms of

A thunderstorm cell develops a core within a few minutes and becomes t = 25 min severe a few minutes later. t = 20 min Dying cell t = 15 min

SEVERE New cell t = 10 min

5 min to t = 5 min surface / “Core” Outflow

Depending on the distance of This example represents typical “pulse” storms w/ storms, VCP 12 can run full little wind shear. “Linear” storms – lines have typically much longer lead time since they are self- volumes between 3.5 and 4.5 min. sustaining and can last hundreds of miles What’s our tornado history?

Blue Ridge Some of the more high-impact severe events…

Frostburg, MD F4 tornado (June 6, ‘98)

The “Derecho” June 29, 2012Deadly Petersburg, VA F4 tornado (Aug 6, ‘93) Notice how there’s a much smaller corridor of warm/moist air that is able to affect the Eastern Seaboard, relative to the other “alleys”. That is because of the relative size of this land area compared to the others.

The “original” Tornado Alley – The High Plains Area tornado

Northern MD/WV Panhandle (Linear)

Tornadoes can happen anywhere (over land) at any time of day – and have. However, there are areas that more commonly receive tornadic activity, based on terrain, relative proximity to bodies of water, typical boundary placement

How wide and powerful was the La Plata tornado?

U.S. 301

EF4 EF3 EF1 EF2 ~1/2 mile

~1/4 mile

Downtown

Let’s transpose this (slightly stronger/wider) onto a more urbanized area… May 20, 2013 EF5 - Moore, OK

“Only” 2 “small” locations of EF5 damage

But a decent swath of EF4 BULLETIN – EAS ACTIVATION REQUESTED 5:24 pm EDT TORNADO WARNING 5:28 pm EDT BALTIMOREBULLETIN MD/WASHINGTON – EAS ACTIVATION DC REQUESTED BULLETIN – EAS ACTIVATION600 REQUESTED PM EDT FRI JUN 8 20XX TORNADO WARNING TORNADO WARNING NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC NATIONAL WEATHER SERVICE ...TORNADOBALTIMORE MD/WASHINGTONEMERGENCY FOR DCARLINGTON...ALEXANDRIA...THE 630 PM EDT FRI JUN 8 20XX DISTRICT OF 530 PM EDT FRI JUN 8 20XXCOLUMBIA AND CENTRAL MONTGOMERY COUNTY...... FOR PORTIONS OF CENTRAL MONTGOMERY COUNTY AND ANNE THE NATIONAL WEATHER SERVICETHE NATIONALIN STERLING WEATHER VIRGINIA SERVICE HAS ARUNDELINISSUED STERLING ACOUNTY... VIRGINIA HAS ISSUED A

* TORNADO WARNING FOR... * TORNADO WARNING FOR... THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A THE DISTRICT OF COLUMBIA... THE DISTRICT OF COLUMBIA... NORTHERN FAIRFAX COUNTY INEXTREME NORTHERN EASTERN VIRGINIA... FAIRFAX COUNTY* TORNADO IN NORTHERN WARNING VIRGINIA... FOR... CITY OF FALLS CHURCH IN NORTHERNCITY OF FALLSVIRGINIA... CHURCH IN NORTHERN MONTGOMERY VIRGINIA... COUNTY IN CENTRAL MARYLAND... ARLINGTON COUNTY IN NORTHERN ARLINGTON VIRGINIA... COUNTY IN NORTHERN CENTRALVIRGINIA... ANNE ARUNDEL COUNTY IN CENTRAL MARYLAND... MONTGOMERY COUNTY IN CENTRAL MONTGOMERY MARYLAND... COUNTY IN CENTRAL MARYLAND... * UNTIL 715 PM EDT... * UNTIL 615 PM EDT... * UNTIL 645 PM EDT... * THE NATIONAL WEATHER SERVICE WAS TRACKING A LARGE AND EXTREMELY * AT 528 PM EDT...A SEVERE* THETHUNDERSTORM NATIONAL WEATHERCAPABLE SERVICEOF PRODUCING DANGEROUSWAS TRACKING A TORNADO TORNADO A LARGE 3 MILES AND EXTREMELYSOUTHEAST OF CAPITOL HEIGHTS...OR 2 MILES WAS 2 MILES SOUTHWEST OF DANGEROUSSTERLING...OR TORNADO NEAR NEAR HERNDON...AND DOWNTOWN SOUTHWEST ARLINGTON...OR WAS MOVING OF LARGO. 2 DOPPLERMILES NORTHWEST RADAR SHOWED OF THIS TORNADO MOVING EAST SOUTHEAST AT 30 MPH. FT MEYER. DOPPLER RADAR SHOWED AT THIS30 MPH. TORNADO MOVING EAST AT 30 MPH.

* LOCATIONS IMPACTED INCLUDE THIS IS A TORNADO EMERGENCY FORTHIS THE IS CITYA TORNADO OF LARGO EMERGENCY AND SURROUNDING FOR THE CITY OF LARGO AND SURROUNDING HERNDON... AREAS. TAKE COVER NOW. AREAS. TAKE COVER NOW. RESTON... GREAT FALLS... * LOCATIONS IMPACTED INCLUDE * LOCATIONS IMPACTED INCLUDE WOLF TRAP... ARLINGTON... KETTERING... TYSONS CORNER... ARLINGTON NATIONAL CEMETERY... LARGO... THE AMERICAN LEGION BRIDGE... FT MEYER... DISTRICT HEIGHTS... MCLEAN... ADAMS MORGAN... FORESTVILLE... FALLS CHURCH... DOWNTOWN WASHINGTON... BOWIE... US CAPITOL... DAVIDSONVILLE... TAKE COVER NOW. MOVE TO AN NATIONALSINTERIOR ROOMPARK... ON THE LOWEST FLOOR OF A STURDY BUILDING AND AVOID WINDOWS.RFK STADIUM... IF OUTDOORS OR IN APRECAUTIONARY/PREPAREDNESS MOBILE HOME OR ACTIONS... VEHICLE...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT YOURSELF FROM FLYING . PRECAUTIONARY/PREPAREDNESS ACTIONSTO REPEAT...A... LARGE...EXTREMELY DANGEROUS...AND POTENTIALLY DEADLY TORNADO IS ON THE GROUND. TO PROTECT YOUR LIFE...TAKE COVER NOW. MOTOROISTS SHOULD NOT TAKETO SHELTERREPEAT...A UNDER LARGE...EXTREMELY HIGHWAY OVERPASSES.MOVE DANGEROUS...AND TO ASAN AINTERIOR LAST POTENTIALLYROOM ON THE DEADLYLOWEST FLOOR OF A STURDY BUILDING. RESORT...EITHER PARK AND TORNADOSTAY IN ISYOUR ON VEHICLE...ORTHE GROUND. TOABANDON AVOIDPROTECT YOURWINDOWS. YOUR VEHCILE LIFE...TAKE IF IN A MOBILE COVER HOME...A NOW. VEHICLE OR OUTDOORS...MOVE AND LAY FLAT IN A LOW SPOT.MOVE TO AN INTERIOR ROOM ON THETO THELOWEST CLOSEST FLOOR SUBSTANTIAL OF A STURDY SHELTER BUILDING. AND PROTECT YOURSELF FROM FLYING AVOID WINDOWS. IF IN A MOBILEDEBRIS. HOME...A VEHICLE OR OUTDOORS...MOVE LAT...LON 3884 7867 3895 TO7855 THE 3904 CLOSEST 7833 SUBSTANTIAL3913 7823 SHELTER AND PROTECT YOURSELF FROM FLYING 3931 7817 3944 7808DEBRIS. 3971 7795 3972 7752 LAT...LON 3884 7867 3895 7855 3904 7833 3913 7823 3914 7784 3882 7820 3931 7817 3944 7808 3971 7795 3972 7752 TIME...MOT...LOC 2159Z 240DEGLAT...LON 26KT 38843972 78677777 38953952 78557778 3904 39147833 77843913 38827823 7820 3926 7786 3894 7805 3931 7817 3944 7808 3971TIME...MOT...LOC 7795 3972 7752 2159Z 280DEG 26KT 3972 7777 3952 7778 3914 7784 3882 7820 3926 7786 3894 7805 $$ TIME...MOT...LOC 2159Z 270DEG 26KT 3972 7777 3952 7778 3926 7786 3894 7805$$ GMS $$ GMS

GMS EF0 EF1

EF2 EF3 0.7 mi

EF4

The worst part of the nearly 35 mi. damage path crossing over the Court House section of downtown Arlington – passing just north of Arlington Cemetery, then over the Potomac River, straight down the National Mall. Max path width is roughly ¾ of a mile. Zooming-in even further to the heart of downtown D.C. Unfortunately, the “post-river” flat land expanse gives the tornado enough room A solid swath of EF2-type damage, though the damage after crossing the Potomac to intensify points would be subjective with part of the river, rows directly over The U.S. Capitol & of trees and only a few structures, surrounded by surrounding buildings. concrete buildings.

EF0 EF1 EF2 EF3

EF4 A steady 0.3-0.4 mi. wide EF2 stripe with a couple of pockets of EF3 & smaller areas of EF4 damage… EF0 EF1

EF2 EF3

EF4

Not to leave anyone out and actually, Baltimore has just as good a chance – if not better – of having a similar scenario.

Imagine this same storm scraping a 35 mi. path, with the worst going through downtown Baltimore. No Warning System in-place Effective Warning and Dissemination What does this mean to you? Deaths: ????? Deaths: ????? Injuries: ????? Injuries: ????? How will you prepare? June 29-30, 2012 Derecho May 20, 2013 - Moore, OK EF-5: (entire path) ~$3 billion 24 deaths; nearly 400 injuries * Tree and power line damage, trees on homes, tree removal, etc. 14 minutes from initial warning to touchdown 39 minutes on ground 17 mile path

DCBaltimore Area Damage Area Damage Estimates: Estimates: $5-10 billion $1-2 billion * Downtown DCBaltimore – millions – millions on various on Inner monuments/buildings, Harbor commerce, infrastructure buildings, *shipping Downtown infrastructure Arlington – (just high missedrises, businesses stadiums, but what if it didn’t) * Fairfax/MontgomerySuburban Areas – similar CO’s to– thousandsMoore, OK ofbut homes, more businesses,structures and schools, road etc. *networks Transportation: affected thousands of cars directly impacted, on area roads at the time, in path at homes May 20, 2013 - Moore, OK EF-5: $2-3 billion May* Mostly 20, homes, 2013 small - Moore, commercial OK buildings,EF-5: $2 a- 3few billion schools, and other *suburban Mostly homes, dwellings small commercial buildings, a few schools, and other suburban dwellings

Severe Thunderstorm Warnings cannot be taken for granted • Not all T-storms are created equally but a severe one is enough to damage/injure/kill – so can “near-severe” (, strong winds) • Most deaths (in this area) from falling trees/limbs – severe winds * M.A. is covered in trees – old ones too (as 2012 Derecho showed) • Winds (even severe strength) can be well out ahead of precip – stay alert!

Tornadoes • We get them, plenty of them – strong ones are rare but not unprecedented • EF5 strength? High unlikely but possible. * We don’t need an EF5 or a large wedge for it to be devastating. • Tornadoes (even the worst ones) can happen any time of the year

Damage Paths • VERY variable. House to house, tree to tree, different effects along a path * Classification for a tornado is for the worst damage but it may be only a tiny portion of the path.