Download Weather Forecasting

Week 13 Notes
TONIGHT
• Weather Forecasting (Chp 14)
Nov 23
• No Class – Fall Recess
Nov 30
• Earth’s Changing Climate (Chp 15)
• Review
• Term Papers Due
Dec 7
• FINAL EXAM
• Extra Credit Term Papers Due
CHAPTER 14
WEATHER FORECASTING
Classwork (HW#11)
• Divide into 6 groups
• Find 2 different forecasts for Saturday, Nov. 20
• Groups 1 & 4: Seattle
• Groups 2 & 5: Reno
• Groups 3 & 6: San Francisco
• What sites did you use? Why?
• Discuss what was forecast.
• How were they different?
Weather Forecasting in US
• Ben
Franklin
• Used Post Service
• 1870s Congress Established Weather Services
• Branch of Army Signal Corps
• 1890 Transferred to Department of Agriculture
• US Weather Bureau
• 1942 Transferred to Department of Commerce
• 1970 National Oceanic and Atmospheric Administration
(NOAA)
• Renamed National Weather Service (NWS)
Forecast Methods
°
°
°
°
°
Persistence
Trend (Steady State)
Climatology
Interpolation
Analogue
° Weather Types
° Numerical Weather Prediction (NWP)
Climatology
Fig. 14.8, p. 409
Numerical Weather Prediction
• Model Inputs (Initial Conditions)
– Temperature
– Moisture
– Wind
– Pressure
Numerical Weather Prediction
° Initial Conditions
° Surface
° Airports
° Auto Remote Weather Stations
° Buoys
° Ships
° Upper Air
° Radiosondes
° Satellite Sounders
° Aircraft
Numerical Weather Prediction
° Interpolation of Initial Conditions
° Horizontal Grids
° Vertical Grids
° Other Inputs
° Topography
° Date/Season
° Ground Cover
° Numerical Models
° Time Step Forward
° 12, 24, 36, 48…384hrs
NAM Numerical Model
• Semi-staggered Arakawa E grid
• 32km horizontal resolution
• 45 vertical eta layers
NAM Numerical Model
• Now do it in 3-D
Numerical Weather Prediction
° Some of the Current Models
° NAM/WRF
° NGM (Nested Grid)
° GFS (Global Forecast System)
° Meso-ETA
° MM5
° RUC
° UK
° ECMWF
° NOGAPS
° Ensemble Forecasts
NAM Numerical Model
ETA Topography
GFS Topography
Numerical Weather Prediction
° Model Outputs
° Raw Data
° Temperature
° Pressure
° Moisture
° Derived Outputs
° Wind (x,y,z)
° Stability
° Vorticity
° Precipitation
° MOS
° Model Output Statistics
NWP Output - Raw
NWP Output - Raw
NWP Output - Raw
NWP Output - Raw
NWP Output - Derived
Day 2 Ensemble Forecasts
Day 5 Ensemble Forecasts
Day 8 Ensemble Forecasts
Day 11 Ensemble Forecasts
Rainfall Forecasts & Resolution
Human Output
MOS Output
KOAK AVN MOS GUIDANCE 3/24/2003 0600 UTC
DT /MAR 24 /MAR 25 /MAR 26 /
HR
X/N
12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 00 06
64
49
66
55
64
TMP 51 51 56 61 62 57 54 52 51 52 58 64 64 59 57 57 56 58 60 62 55
DPT 46 45 45 44 44 45 45 45 44 44 47 48 50 51 52 52 52 51 49 45 43
CLD BK BK SC SC CL CL CL CL SC SC BK BK OV OV OV OV OV OV BK SC CL
WDR 28 27 26 27 28 28 30 29 31 28 23 26 26 27 26 24 25 24 26 27 31
WSP 07 07 09 11 12 10 05 04 01 01 03 08 12 13 07 09 10 10 10 15 09
Types of Forecasts
• Quantitative Forecast
Amount of Forecast Variable Is Specified
An Inch of Rain
High Temperature Will Be 45°F
• Qualitative Forecast
Categorical Value for Forecast Variable
Above / Below Normal
Cloudy / Partly Cloudy / Mostly Cloudy
• Probability Forecast
Chance of Something Happening Rather Than a Certainty
Cloud Cover Will be 70%
Probability of Precipitation
PoP Forecast
75% Chance of Rain
Odds of Precipitation Are 3:1
Weather Products
° Public Forecasts
° Weather
° Temperatures
° Wind
° Advisories
• Types of Forecasts
– Now cast < 6 hrs
– Short range 12-72 hrs
– Medium range 3 - 8.5 days
– Long Range > 8.5 days
Weather Products
° Aviation Forecasts
° Terminal Conditions
° Enroute Conditions
° Marine Forecasts
°
°
°
°
Winds
Seas
Swells
Weather
Watches and Warnings
° Advisories
° Less Severe
° Dense Fog, Wind, Urban Flooding
° Watches (usually 6-24 hours in advance)
° Possible Severe Weather
° Tornadoes, Severe Thunderstorms, Flash Flooding
° Warnings (imminent or occurring)
° Probable Severe Weather
° Tornadoes, Severe Thunderstorms, Flash Flooding
Specialized Weather Products
° Fire Weather Forecasts
° Weather
° Temperatures
° Wind
° Humidity
° Agricultural Forecasts
° Frosts and Freezes
° Temperatures
° Precipitation
° Flood Forecasts
° Avalanche Forecasts
Weather Dissemination
° Where do you get weather information?
° How reliable is it?
Weather Forecast Sources
° National Weather Service
° NCEP
° Digital data
° Long range
° Local Offices
° Public, Aviation, Marine Forecasts
° Private Weather Companies
° Media
° Electronic
° Print
° Internet
Making a Forecast
° Initial Conditions
° Satellite
° Radar
° Surface observations
° Look at the models
° Forecasts discussions
° Other forecasts
Making a Forecast
BASIC
ADVANCED
Current •Latest hourly weather data •Weather Stations Map
Conditions •National Weather Map
•Satellite - Visible, Infrared, N Pacific Infrared,
National
•Radar - San Francisco, National
•Profilers
Forecast •Day 1-2 Maps
•San Jose State Model Page, NCEP Loops
Data
•Day 3-7 Maps
•CANSAC Model Page
Weather
•ModelGuide
Output Statistics
•6-10Do-It-Yourself
Day Temperature,
Rain Forecast
•Rainfall Maps
•Local Technical Discussion
Forecasts & •California Graphical
Warnings •National Graphical
Resources •Weather Glossary
•Weather 101
•California Text Forecasts
•IPS Meteostar
•Weather Underground
•Meteorologist's Weather Links
http://ggweather.com/4cast.htm
What is a Meteorologist?
° Do you have to have a degree in meteorology?
° Who certifies?
° Television meteorologists?
° Other careers:
° Academia
° Research
° Applied
° Forensic
Forecast Accuracy
° What to Verify? When to Verify? Who to
Verify?
° Temperature
° Rain
° Probability
° Amount
° Storminess
° Bay Area Storm Index (BASI)
° Farmer’s Almanac ?
Forecast Accountability
° Suing the Weatherperson
° Bad hair day? Ruined Picnic? Cancelled
Concert?
° Brazil
° “Sounding a False Alarm”
° Peru
° 10 inches of Rain, Floods and 17 Drowned
° “Sovereign Immunity”
° Federal Tort Claims Act
° Negligence or wrongful act or omission
° Private vs. Government Forecasts
NO CLASS NEXT
WEEK!!
HAPPY
THANKSGIVING