2014 Penn State Weather Camp
National Weather Service Presentation
NATIONAL WEATHER SERVICE
STATE COLLEGE, PA
PETER JUNG
WARNING COORDINATION METEOROLOGIST
PETER.JUNG@NOAA.GOV
A little bit about the National Weather Service
 National Weather Service
 Our parent agency is NOAA


National Oceanic and Atmospheric Administration
NWS (and NOAA) fall under the Department of Commerce
Federal agency
 Tax-payer supported

Does Weather have an Impact?
 Weather related damages exceed $20 billion per year
 70% of all travel delays weather related
 Economic impact (direct impacts, delays, loss of work,
etc.) on the U.S. over $3 trillion per year
 97+% of all Presidentially declared disasters are weather
related

“Super” snowstorms, Hurricanes (Lee, Irene, Sandy, etc.), Severe
thunderstorms and Tornadoes, Flash flooding.
The Mission of the National Weather Service
 Primary Mission:
 Provide Weather, Hydrologic and Climate Forecasts and
Warnings for the Protection of Life and Property
 Secondary Mission Objectives:
 Enhance the National Economy
 Provide a National Information Database which can be used by
other government agencies, the private sector, and the Global
Community
Who is the National Weather Service
Organization
 Local Offices



123 Local Weather Forecast Offices
 Five offices serve Pennsylvania
13 River Forecast Centers
 Two serve Pennsylvania

AWC – Aviation Weather Center

CPC – Climate Prediction Center

EMC – Environmental Modeling Center

NCO – NCEP Central Operations

NHC – National Hurricane Center

OPC – Ocean Prediction Center

SPC – Storm Prediction Center

SWPC – Space Weather Prediction Center

WPC – Weather Prediction Center
6 Regional Offices


 9 National Centers (NCEP)
Eastern, Central Southern, Western,
Alaska and Pacific
NWS Headquarters

Silver Spring, MD
Where are all those Local Offices?
Pennsylvania Counties and Corresponding
National Weather Service Offices
YOU ARE HERE
A look at the local office
 Staffing: ~25 persons
 10 full-time forecasters
 3 interns
 5 technicians
 5 specialists in science, outreach, observing program and
hydrology
 Open 24x7x365
Key Pieces of Equipment
Satellite
Remote Sensing
Equipment
Doppler Radar
Powerful Computers
SkyWarn Spotter Program
 In addition to all our remote sensing equipment, we use a
VOLUNTEER group of TRAINED public citizens that
observe and report weather to the NWS to:



Supplement remote sensing equipment
Provide real-time ground truth reports
Add credibility to NWS products and services
 The SkyWarn program is NOT a storm-chasing network!
 SkyWarn Spotters act as thousands of “eyes and ears” out
in the field, supporting our forecast and warning
program!
NWS Products: A Three–Tiered Approach
Outlooks
Time
To
Watches
Event
Warnings/
Advisories
Confidence in the forecast
Weather Definitions and Terms
 OUTLOOK
 A long term product (generally 3 to 7 days)
 Heads-up of something potential on the horizon

Our confidence level is about
%
 WATCH
 Conditions are FAVORABLE for a given weather event to
occur, but not imminent
 Generally 6 hours to as much as 2 days
Severe Thunderstorm, Tornado, Flood, High Wind, Snow, etc.
 Our confidence level is at about
%

Weather Definitions and Terms
 OUTLOOK
 A long term product (generally 3 to 7 days)
 Heads-up of something potential on the horizon

Our confidence level is about 30%
 WATCH
 Conditions are FAVORABLE for a given weather event to
occur, but not imminent
 Generally 6 hours to as much as 2 days
Severe Thunderstorm, Tornado, Flood, High Wind, Snow, etc.
 Our confidence level is at about
%

Weather Definitions and Terms
 OUTLOOK
 A long term product (generally 3 to 7 days)
 Heads-up of something potential on the horizon

Our confidence level is about 30%
 WATCH
 Conditions are FAVORABLE for a given weather event to
occur, but not imminent
 Generally 6 hours to as much as 2 days
Severe Thunderstorm, Tornado, Flood, High Wind, Snow, etc.
 Our confidence level is at about 50%

Weather Definitions and Terms
 ADVISORY


A shorter term product, mainly 0 – 24 hours
High confidence that a weather event will occur, but with limited
impacts
Lighter snow and ice events, strong (but not severe) wind events, etc.
 Our confidence level is about
%

 WARNING


A shorter term product, mainly 0 to 24 hours
High confidence that a significant, high impact, and potentially life
threatening condition will take place
Severe Thunderstorms, Tornadoes, Flash Floods, Heavy Snow/Ice,
etc.
 Our confidence level is at about
%

Weather Definitions and Terms
 ADVISORY


A shorter term product, mainly 0 – 24 hours
High confidence that a weather event will occur, but with limited
impacts
Lighter snow and ice events, strong (but not severe) wind events, etc.
 Our confidence level is about 80%

 WARNING


A shorter term product, mainly 0 to 24 hours
High confidence that a significant, high impact, and potentially life
threatening condition will take place
Severe Thunderstorms, Tornadoes, Flash Floods, Heavy Snow/Ice,
etc.
 Our confidence level is at about 80%

Thunderstorms
REVIEW OF A LIFECYCLE OF A
THUNDERSTORM
Lifecycle of a Thunderstorm
 Developing Stage
 Dominated by UPWARD
MOVING air
 Extends vertically to
10,000 to 20,000 ft
No Severe Weather at this stage
Depending on atmospheric
conditions, this may (or may not)
develop into a thunderstorm
Lifecycle of a Thunderstorm
 Mature Stage
 Storm contains UPWARD
and DOWNWARD moving
air
 Extends vertically to
40,000 to 60,000 ft
 Best potential for severe
weather including hail at this
stage
 With rotation, this can lead to
a tornado
Lifecycle of a Thunderstorm
 Dissipating Stage
 Storm contains mostly
DOWNWARD moving
air
 Supply of warm moist air
“fuel” has been exhausted
or cut off
 Transition from “mature” to
“dissipating stages best time
for Downbursts to occur
Types of Thunderstorms
QUIZ
 Pulse Type

Characteristics:




Average Lifespan:?
 30-60 minutes
 1 to 3 hours
 3 to 6 hours
 > 6 hours
Severe Potential?
 Low
 Moderate
 High
Most significant threat?
 High winds
 Tornadoes
 Hail
 Flooding
Wind Shear Environment?
 Weak
 Strong
QUIZ
 Pulse Type

Characteristics:




Average Lifespan:?
 30 -60 minutes
 1 to 3 hours
 3 to 6 hours
 > 6 hours
Severe Potential?
 Low
 Moderate
 High
Most significant threat?
 High winds
 Tornadoes
 Hail
 Flooding
Wind Shear Environment?
 Weak
 Strong
QUIZ
 Pulse Type

Characteristics:




Average Lifespan:?
 30 -60 minutes
 1 to 3 hours
 3 to 6 hours
 > 6 hours
Severe Potential?
 Low
 Moderate
 High
Most significant threat?
 High winds
 Tornadoes
 Hail
 Flooding
Wind Shear Environment?
 Weak
 Strong
QUIZ
 Pulse Type

Characteristics:




Average Lifespan:?
 30 -60 minutes
 1 to 3 hours
 3 to 6 hours
 > 6 hours
Severe Potential?
 Low
 Moderate
 High
Most significant threat?
 High winds
 Tornadoes
 Hail
 Flooding
Wind Shear Environment?
 Weak
 Strong
QUIZ
 Pulse Type

Characteristics:




Average Lifespan:?
 30 -60 minutes
 1 to 3 hours
 3 to 6 hours
 > 6 hours
Severe Potential?
 Low
 Moderate
 High
Most significant threat?
 High winds
 Tornadoes
 Hail
 Flooding
Wind Shear Environment?
 Weak
 Strong
Types of Thunderstorms
 Back-Building Storms

Characteristics:



Multiple Cells...where each cell
generates a cold outflow that triggers
a gust front
Severe potential is higher than pulse
storms
Good potential Flash Flood
producers
 Cells may propagate (new cells
form) different direction from the
movement of overall storm
system
 “Training Echoes”
 Johnstown Flood
Johnstown Area – Prone to Devastating
Flash Floods
May 1889 – March 1936 – July 1977
May 31, 1889 – 2209 fatalities
March 17, 1936 “St.
Patrick’s Day Flood”
- 25 deaths
- 9000 homeless
- $50 million in damages
- Heavy rain and snowmelt
- Water 14 feet deep in
downtown Johnstown
July 19-20, 1977
-Over 12 inches of rain from training MCS, eventual failure of the Laurel Run
Dam and seven others!
- 78 lives lost
- 50,000 homeless
- $200 million in damages
QUIZ
 Multicell Line or
Squall Line Type

Characteristics:
Multicell Thunderstorm
complex in a line
 Severe potential is higher
than pulse storms
 Best Severe Potential is:

•
•
•
•
Strong Wind
Hail
Tornadoes
Flooding
QUIZ
 Multicell Line or
Squall Line Type

Characteristics:
Multicell Thunderstorm
complex in a line
 Severe potential is higher
than pulse storms
 Best Severe Potential is:

•
•
•
•
Strong Wind
Hail
Tornadoes
Flooding
QUIZ
 Supercell Type

Characteristics:




Average Lifespan:?
 30-60 minutes
 1 to 3 hours
 3 to 6 hours
 > 6 hours
Severe Potential?
 Low
 Moderate
 High
Most significant threat?
 High winds
 Tornadoes
 Hail
 Flooding
Wind Shear Environment?
 Weak
 Strong
QUIZ
 Supercell Type

Characteristics:




Average Lifespan:?
 30-60 minutes
 1 to 3 hours
 3 to 6 hours
 > 6 hours
Severe Potential?
 Low
 Moderate
 High
Most significant threat?
 High winds
 Tornadoes
 Hail
 Flooding
Wind Shear Environment?
 Weak
 Strong
QUIZ
 Supercell Type

Characteristics:




Average Lifespan:?
 30-60 minutes
 1 to 3 hours
 3 to 6 hours
 > 6 hours
Severe Potential?
 Low
 Moderate
 High
Most significant threat?
 High winds
 Tornadoes
 Hail
 Flooding
Wind Shear Environment?
 Weak
 Strong
QUIZ
 Supercell Type

Characteristics:




Average Lifespan:?
 30-60 minutes
 1 to 3 hours
 3 to 6 hours
 > 6 hours
Severe Potential?
 Low
 Moderate
 High
Most significant threat?
 High winds (Downburst)
 Tornadoes
 Hail
 Flooding
Wind Shear Environment?
 Weak
 Strong
QUIZ
 Supercell Type

Characteristics:




Average Lifespan:?
 30-60 minutes
 1 to 3 hours
 3 to 6 hours
 > 6 hours
Severe Potential?
 Low
 Moderate
 High
Most significant threat?
 High winds (Downburst)
 Tornadoes
 Hail
 Flooding
Wind Shear Environment?
 Weak
 Strong
Severe Thunderstorms
and
Damage
STRAIGHT LINE WINDS
DOWNBURSTS
MICROBURSTS
MACROBURSTS
TORNADO
DERECHO
Severe Thunderstorms
 Definition:
?? mph,
 A thunderstorm producing Winds in excess of 58
structural damage, or large hail greater than ??
1 inch in
diameter

Lightning, no matter how frequent or deadly is NOT a measure of a
Severe Thunderstorm
Straight Line Winds

Probably the most common wind damage type in Pennsylvania



Often the result of a Squall Line
Result from a combination of the forward movement of the
storm, and transport of high winds aloft down to the surface.
Straight line winds may occur ahead of the actual “storm” at
the leading edge (or gust front)
Straight Line Winds
35 mph
winds at
5000 feet
+
Cold
Front
moving at
30 mph
=
Surface
wind
gusts of
65 mph
Straight Line Winds
 Straight Line Winds
 As the name implies...damaging winds produce damage in a
unidirectional pattern
 Not as glamorous as a tornado in name...but can be far more
destructive

Often covers a large geographic area with many damage
reports
Straight Line Winds
 Straight Line Winds
 Do not be fooled by the extent or intensity of damage, or by the
structures the wind affects. Roofs blown off barns/houses,
uprooted trees, and even twisted trees are not necessarily an
indicator of a tornado

Straight Line Winds can easily exceed 100 mph!
Straight Line Winds
 Radar Loop
Straight Line Winds
STRAIGHT LINE WINDS
Damage shows a clear
UNI-DIRECTIONAL
pattern
STRAIGHT LINE WIND
“fingerprint”
Downburst Winds

The second most common damaging winds in Pennsylvania

Unlike straight-line-winds, Downbursts are formed by the
outrush of air from aloft brought down by the thunderstorm

Damage can be more concentrated than Straight Line Winds

Winds can exceed 150 mph...That’s the equivalent of an EF3
Tornado!
Downburst
 Downbursts can be as destructive IF NOT MORE
destructive than tornadoes


Often cover much larger areas than a tornado
Are much more common than tornadoes
 Downbursts, by their nature, are winds diverging
on the ground


While trees and damage may be oriented in different
directions, they show a pattern of emerging outward from a
central point
These can cause significant tree and structural damage.
More often than not, a very large damage path is indicative
of a Downburst rather than a Tornado
Downburst Damage to NWS Radar
We are not Immune!
Built to withstand 134 mph winds
Downburst / Microburst / Macroburst
 Downburst: Generic term for downward moving
air that spreads out when it reaches the ground

Microburst


Term for a Downburst less than 2.5 miles in extent
Macroburst

Term for a Downburst grater than 2.5 miles in extent
 These terms all describe the same mechanism, and
only are differentiated by the size and scope of the
damage
DOWNBURST
Central PA
Downburst
Wind Event
(04/19/13)
Dauphin
County
Doppler Reflectivity (around 6:20 pm EDT)
showing a fairly straight line of storms.
Central PA
Downburst
Wind Event
(04/19/13)
Dauphin
County
Doppler Reflectivity (around 6:37 pm EDT)
showing a “bowing out” segment of the line of
storms, a good indicator of accelerating winds
and a fingerprint of a Downburst wind event.
Downburst
 Radar Loop
DOWNBURST
Damage
shows a clear
DIVERGING
pattern
DOWNBURST
“fingerprint”
Tornado
 Very specialized wind event
 It takes unique conditions aloft in the storm, and very close
to the ground, to produce a Tornado
 1 in 100 thunderstorms are severe, and on average
1 in 100 “severe” thunderstorms produce
Tornadoes


Pennsylvania sees about 15 tornadoes per year.
Tornadoes usually produce a very small and defined area of
damage (path)

THE DEGREE OF DAMAGE DOES NOT INDICATE
WHETHER OR NOT THERE WAS A TORNADO!
Tornadoes
A look at a Tornado on Doppler Radar
 Tornado Winds
 Much different than Straight Line and Downburst Winds

Pattern of Damage shows CONVERGENCE...winds being pulled
into the center of the tornado
Tornado
 Is it always that easy?
 NO!
 A key is to see where the rotation is, and what is it doing
with time!
 Lots of storms show mid
and upper level rotation
Tornado
 Another KEY question: Is the atmosphere near the
ground primed for tornadoes?

Right conditions of moisture and shear need to be present!
Tornadoes – Some Terms
 Wall Cloud – Rotating lowering (and often rain-
free) section of a thunderstorm.
ROTATION IS THE KEY!!!!
 Sign that conditions within the storm are right for producing a
tornado
 But what are the low level
conditions below the storm???
 A Wall Cloud, while looking
impressive, is not causing damage!

Funnel Cloud
 Funnel Cloud – Fast spinning funnel descending
from the thunderstorm cloud...BUT NOT YET
REACHING THE GROUND!
ROTATION IS THE KEY!!!!
 Sign that conditions within the storm are right for producing a
tornado
 Again, what about conditions
below the storm?
 A Funnel Cloud, while looking very
impressive, is NOT causing damage.
 It may become a tornado soon!

Tornadoes – Tornado
 Tornado – Rapidly rotating funnel of air IN
CONTACT WITH THE GROUND!
ROTATION, STILL, IS THE KEY!!!!
 Look for Damage: No Damage = No Tornado!

Campbelltown Tornado – July 14, 2004
Campbelltown Tornado (SRM)
TORNADO
Damage shows
a clear
CRISS-CROSS
pattern
TORNADO
“fingerprint”
TORNADO
Damage shows
a clear
CONVERGENT
pattern
TORNADO “fingerprint”
Damage
shows a clear
CYCLONIC
turning
TORNADO “fingerprint”
TORNADO
 Enhanced Fujita Scale
 Used to Estimate Winds in a
tornado
 Based on after-the-fact
damage surveys
 Expected wind speeds based
on engineering studies

NOTE: The EF-Scale is a
reworking of the F-Scale
introduced decades ago

Wind Speeds adjusted to
reflect more accurate
measurements
EFScale
EF0
EF1
EF2
EF3
EF4
EF5
Wind
Speed
65-85
86-109
110-137
138-167
168-199
200-234
Be wary of Tornado “look-a-likes”
 Wall Clouds

Make sure they are rotating and connected to the cloud base!
 Funnel Clouds

Again, look for rotation...not just a cloud that looks like a funnel
 Tornado

What damage is it producing


Debris!
Which way is it moving
Pennsylvania Tornadoes through the Years
COMMON TORNADO MYTHS
Myth: Trees laying in different directions must mean tornado damage.
• The direction trees are laying can be influenced by things like tree type, tree bark, size of tree,
amount of foliage, wind load, root structure, and soil conditions.
• Local terrain can influence the wind direction and change the way trees are blown down.
• Branches or trunks can lay in different directions if there is tree rot causing weak or failure
points.
Myth: "Projectiles" automatically suggest a tornado.
• While projectiles are common from a tornado, straight line wind (especially a downburst) can
throw debris down wind and produce projectiles.
Myth: A "roaring" sound suggests a tornado.
• Witnesses often describe a "roaring" or freight train sound with a tornado but that sound can
also occur from straight line winds as they pass through trees, forests, or terrain. Those who
have been struck by a tornado also describe a high-pitch whine or squeal sound as it hits.
Myth: Damage = Tornado!
• Not all damage is tornado related. More times than not it is simply straight-line wind.
• The severe thunderstorm that produces a tornado (usually a Supercell) often produces
straight line wind damage as well. It is very common to have both types of damage related to
the same parent thunderstorm in different areas.
COMMON TORNADO MYTHS
Myth: Uprooted trees are only caused by Severe Thunderstorms (gusts of 58 mph or
higher).
• Root structure can make a big difference. Shallow roots may allow the tree to topple much
easier.
• Soil type and moisture content can also allow a tree to uproot with winds well below 58 mph.
• Tree rot can cause branches or entire trees to be toppled with relatively weak wind speeds.
Myth: Structures explode in a tornado due to lower pressure.
• Structures are torn apart in a tornado from the wind or from the impact of debris.
Myth: Twisting automatically means a tornado hit.
• Not true. Houses, for example, are usually impacted by wind in one primary direction due to the
size of the tornado. You need to examine the entire area impacted. Another example is stop
signs…you can see these “twist” in strong winds even without a tornado.
Derecho
 Derecho
 Extreme Straight Line
Wind (Bow Echo) that
covers a huge area
 250+ miles long
 Lasting at least 6
hours
May 21, 2004
June 30, 2012
Derecho
 Another Look with Velocity
Portable deck used for concerts was lifted and blown away at Hershey Park
06/29/2012
Straight Line (Derecho) Wind Damage near Hershey, PA – 06/29/2012
Straight Line (Derecho) Wind Damage near Hershey, PA – 06/29/2012
Hail
The “idealized” Supercell
Hail forms in the region
BETWEEN the upward
moving air and downward
moving air
Hail Storm – May 22, 2014
Hail Storm – May 22, 2014
Flooding
RIVER FLOODS
FLASH FLOODS
River Flooding
 Forecasts handled by the River Forecast Center
 These are for specific, gauged locations along Main Stem
Rivers and large tributaries
 Locations where it takes more than 6 hours for the waterway to
respond to heavy rainfall


Many streams and creeks are ungauged, and are covered by Flood
and Flash Flood products
River Forecasts are driven by....




Forecast Rainfall
Soil conditions
Snow Melt
Temperatures



Time of Year (foliage)
Routing of upstream water
Reservoir and Dam
releases
Flash Flooding
 Rapid Rises on small (ungauged) streams and creeks
 Mainly driven by...
Slow moving, heavy rain producing thunderstorms
 Repeated rainfall over the same area
 Dam Breaks
 Ice Jams



These streams and creeks respond in
minutes to a few hours after a heavy rain
event
Major threat to LIFE and PROPERTY
Flooding Fatalities
Flooding Fatalities
Flooding Fatalities
Flooding Fatalities
Is your bus
driver crazy
enough to do
this?
A last word about Safety
SAFETY
 TORNADOES
 Never try and outrun a tornado
 Immediately get to a sturdy structure...if not...get out of your
car!
 Do not take shelter under bridges or overpasses
 FLASH FLOODS
 Turn Around, Don’t Drown...Don’t drive through flooded roads

As little as 18 inches of moving water can carry away most vehicles
 LIGHTNING
 Get in a hard-topped vehicle
 Don’t use a corded phone
 Don’t stand under a tall object
SAFETY
 DOWNBURST and HIGH WINDS
 Keep a firm grip on the steering wheel to maintain control
 If it can be done safely...point your vehicle into the direction of
the wind
 Be prepared for sudden visibility restrictions
 In a building, move away from windows
 HAIL
 Get in a strong building
 Hard topped vehicles provide good protection for hail about
golf ball sized.

Larger hail will damage windshields.