1. January History Great Flood of 1937 70% of Louisville was submerged
3.3 billion in damages
Crest ft. (Flood Stage – 55 ft.)
15 inches of rain in 12 days

2. Chapter 1: Monitoring the Weather (Basics)
One of the Deepest Extratropical Cyclones Ever Recorded

3. Difference between Weather and Climate
Weather is the state of the atmosphere at some place and time
Described with quantitative variables
Temperature, humidity, cloudiness, precipitation, wind speed, wind direction
Meteorology is the study of the atmosphere and the processes that cause weather
Climate is weather conditions at some locality averaged over a specified time period
Climate is an average of the weather, figured over the last 30-years and updated every decade
A locale’s climate also includes weather extremes

4. Look at Climatological Information

5. Sources of Weather Information
Television
The Weather Channel and local newscasts
Radio
NOAA Weather Radio
Continuous broadcasts
repeated every minutes
Interrupted with warnings
and watches
The Internet (Ag Weather)
What about now?
Survey of Farmers at the 2013 National Farm Machinery Show

6. Early Days in Ag Weather
Green Thumb – Brought on demand market, futures, and weather information.
100 farmers in 2 counties as a pilot project. Viewed on televisions by accessing county computers using a telephone line
Keypad allowed farmers the option to choose what they wanted to view.
AGTEXT - Worked with KET to distribute closed captioning information to anyone across Kentucky. Forecasts were updated real time.
Netscape in the 1990s, before the World Wide Web became established

7. Retrieving Weather Information & Maps
Weather info received via TV,
radio, or the Internet includes
Weather maps
National
Regional
Satellite/radar images
Data on current/past
conditions
Weather forecasts
Short-term
24 – 48 hours
Long-term
Up to 7 days or longer

8. GOES-R Much higher resolution Can scan areas for severe
weather every 30
seconds
Also detects lightning strikes
Not fully operational until
November.
22,300 miles high

9. Two Types of Pressure Systems
High Pressure
Systems, or
“Anticyclones”
Low Pressure
“Cyclones”

10. Pressure Systems Cont. High and low refer to air pressure Highs Lows
High pressure area is relatively high compared to surrounding air
Low pressure area is relatively low compared to surrounding air
Highs
Fair weather
Clockwise rotation of sinking air (in Northern Hemisphere)
Generally track toward the east and southeast
Lows
Stormy weather
Counterclockwise rotation of rising air (in Northern Hemisphere)
Generally track toward the east and northeast
Lows tracking across the northern U.S. or southern Canada produce less moisture than lows tracking across the southern U.S.
Weather to the west and north – usually cold
Weather to the south and east – usually warm

11. (High and Low Pressure Centers)
Pressure Systems Cont.
(High and Low Pressure Centers)
Arrows indicate surface horizontal winds

12. (What’s the weather like?)
Pressure Systems Cont.
(What’s the weather like?)
1. Tallahassee, FL
2. Greenville, NC
3. Duluth, MN
4. Scranton, PA
Wind Direction?
Cloudy/Wet, Clear/Dry?

13. Air Masses Huge volume of air covering thousands of square kilometers
Horizontally relatively uniform in characteristics
Temperature
Humidity
Gathers characteristics from its source region
Cold, dry air masses form at higher latitudes over continents
Cold, humid air masses form at higher latitudes over maritime surfaces
Warm, dry air masses form over continents in subtropical regions
Warm, humid air masses form near the equator or in the subtropics over maritime surfaces

14. Air Masses Across North America
Old Saying in the Ohio Valley:
“Don’t like the weather today?
It will change tomorrow!”

15. Fronts “Transition Zones between Air Masses”
Warm Front
Warm Air Rising
Cold Front

16. Fronts – Boundary Between Air Masses
Cold Front
Generally, a narrow band of precipitation along or just ahead of the surface front, where precipitation is brief (couple of minutes to a few hours)
Precipitation can be severe
Boundary between advancing cold air and retreating warm air
Plotted on a map as a blue line with triangles pointed in the direction of motion
Sharp Temperature Change

17. Fronts – Boundary Between Air Masses
2. Warm Front
Generally, a wide band of precipitation along or just ahead of the surface warm front, where precipitation can be persistent (12-24 hours)
Precipitation is generally light to moderate
Boundary between advancing warm air and retreating cold air
Plotted on a map as a red line with semi-circles pointed in the direction of motion

18. Fronts – Boundary Between Air Masses
Right - A cyclone with the warm and cold fronts extending outward from the low pressure center. Showers generally form along the warm front, while more severe weather can occur along the cold front.
Left - Shows how the warm and cold fronts act as boundaries between different air masses. Notice how the wind directions are different on either side of the fronts, and that the flow is counterclockwise and convergent.

19. Ways to Locate a Front on a Surface Weather Map
Precipitation
Cloud Cover
Wind Shift
Temperature Difference
Dew Point Difference

20. Other Types of Frontal Boundaries
Stationary – a non-moving front where winds on either side blow in opposite directions. Can become a cold or warm front based on advection.
2. Occluded – when the air behind the cold front overtakes the air ahead of the warm front

21. Characteristics of Air Masses & Fronts
Wind directions are different on the two sides of a front
Some fronts have no clouds or precipitation.
Passage indicated by wind shift, and temperature/humidity changes
In summer, temperature can be nearly the same on both sides of a cold front
Difference will be humidity
Fronts are anchored to lows on a weather map.
Counterclockwise flow brings contrasting air masses together to form fronts
Thunderstorms/severe weather often occur in the warm, humid air mass located between the cold and warm front

22. Describing the State of the Atmosphere What do Forecasters Tell Us?
Maximum Temperature
Usually occurs in early to mid-afternoon
Minimum temperature
Usually occurs around sunrise
Dewpoint (frost point)
The temperature at which air must be cooled at constant pressure to become saturated with water vapor and for dew (or frost) to form
Higher Dewpoint = More Moisture
Relative humidity
A percentage; the ratio of the actual concentration of the water vapor component of air compared to the concentration the air would have if saturated with water vapor
Relative humidity will change throughout the day as the temperature varies
Generally highest around sunrise and lowest when warmest
Precipitation amounts
General rule – 10” of snow = 1” of precipitation

23. Example: More about RH and Dew Point
Dew Point Temp F
Human Perception
R. Humidity
75 +
Extremely uncomfortable, oppressive
62%
70-74
Very Humid, quite uncomfortable
52-60%
65-69
Somewhat uncomfortable for most people
44-52%
60-64
OK for most
37-46%
55-59
Comfortable
31-41%
50-54
Very comfortable
31-37%
49 or lower
Feels like the western US
30%
None
Danger
Emergency
Livestock Cold Stress?

24. Describing the State of the Atmosphere Cont.
What do Forecasters Tell Us?
Air Pressure
And its tendency (rising or falling)
Falling may indicate approaching
cold front
Wind direction and speed
Wind direction is the direction wind
is blowing from
Example; a west wind is blowing from the west, toward the east
Sky cover
Fraction of the sky covered in clouds
NWS Weather watch – issued when hazardous weather is considered possible
NWS Weather warning – issued when hazardous weather is imminent or actually taking place

25. Weather Satellite Imagery
Two major types of satellite orbits
Geostationary
High orbits
36,000 km (22,300 miles) high
Orbits planet at same rate as Earth’s rotation and in same eastward direction
Currently 2 of these provide a complete view of much of N. America and adjacent oceans to latitudes of about 60 degrees
Positioned over equator at 750 W longitude, 1350 W longitude
Low angle in polar regions
Polar orbiting
Low orbits
km (~ miles) high (Much more detailed info)
Provides overlapping north-south strips of images
Passes over the same point twice every 24 hours

26. Orbits of Each Type of Satellite
Geostationary Satellite
Polar Orbiting Satellite

27. Weather Satellite Imagery
Visible
Black and white photograph of the planet
Only available during daylight hours
Highly reflective surfaces appear bright white and less reflective surfaces are darker

28. Weather Satellite Imagery
Infrared
Available anytime, not just during daylight
Provides temperature comparison of features within image
Colder = Bright
Warmer = Dark
Lower Altitude= Gray
Higher altitude =Bright colors

29. Weather Satellite Imagery
Water vapor imagery
Enables tracking of plumes of moisture
Shades of white = increasing moisture
Upper-level clouds appear milky to bright white

30. Weather Radar Complements satellite surveillance
Doppler radar detects movement
Excellent tool to forecast tornadoes

31. Understanding UTC Time
Weather observations are taken across the world based on a standard time.
In doing so, a 24 hour clock is used, similar to military time.
UTC (Coordinated Universal Time or Universal Time Coordinated)
Also called “Z Time”
To get local time in the United States, you have to subtract a certain number of hours based on time zone.
Daylight Savings Time does make a difference

32. Understanding UTC Time
UTC Time = 1200 UTC
Daylight Savings Time?
(Not until March 8th) No
-5 Hours for EST
= 7 AM
18 UTC = 18Z = ?
00 UTC = 0Z = ?
06 UTC = 6Z = ?