MET 1010 Ch. 13
University of Florida
MET 1010
Intro. to Meteorology
Meteorology Today by Ahrens
Chapter 13
MET 1010
Intro. to Meteorology
Meteorology Today by Ahrens
Chapter 13
Terms
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- Weather Type
- forecast that uses general criteria to predict weather
- The Station Model
- a collection of symbols that tell the current weather conditions (center; cloud cover. left; temp, present weather, dew point, wind direction and speed. Right; pressure, pressure tendency, prev. weather 1 hr ago.)
- National Center for Environmental Prediction (NCEP)
- national center in Camp Springs, MD where data analysis, prep of weather maps, and prediction of nation-wide weather takes place
- Gale Warnings
- winds range from 39-54 mph in the area
- Medium-Range Forecast
- 3-8 days, numerical models
- Steady State Forecast
- trend method, forecast that a weather system will continue with the same speed and direction so forecaster can extrapolate future location
- Meteogram
- collection of observations at a given station over time
- Heat Warning
- daytime heat index reaches 115F or more for 3 or more hours
- Extended Forecast
- forecast goes beyond 3 days
- Hurricane Warning
- A hurricane or tropical storm appears to be striking the area within 24 hrs
- Very Short-Range Forecast
- nowcast, up to 6 hrs, based satellite images and Doppler radar
- Small Craft Advisories
- winds from 21-39 mph can be expected
- Slight Chance of Having Precipitation
- widely scattered showers, 20% chance
- Sounding
- vertical profile of temp, dew point and wind
- Short-Range Forecast
- 2-3 days, numerical models, satellite images and Doppler radar
- Chance of Having Precipitation
- scattered showers, 30-50% chance
- Snow Advisory
- There is a substantial snowfall expected in the area (2 in or more in 12 hours, or 3 in or more in 24 hours)
- Hurricane Watch
- A hurricane or a tropical storm is a threat to coastal line
- World meteorological organization (WMO)
- a UN organization which standardizes meteorological measurements and allows for exchange of data between nations, 175 nations involved, centers in Melbourne, Moscow, and D.C.
- Long-Range Forecast
- up to 16 days, numerical models, not very accurate
- Blizzard Warning
- snow with winds exceeding 35 mph, visibility less than ¼ mile for several hours
- High Wind Warnings
- winds above 40 mph
- Flash Flood Warning
- flash flooding is occurring in the area
- National Weather Service
- issues advisories and warnings for severe weather
- Weather Forecast Offices (WFO)
- regional offices where regional weather maps are prepared
- Climatological Forecast
- forecast based on typical weather conditions at a given location for a given season
- Wind Advisory
- winds between 25-39 mph
- Heat Advisory
- daytime heat index reaches 105F for 3 or more hours
- Will Have Precipitation
- showers, more than 80% chance
- Tornado Watch/Warning
- Tornado may/has developed in the area
- Persistent Forecast
- forecast that weather conditions will not change (accurate for short term)
- Advisory
- less hazardous conditions due to wind, dust, fog, snow, sleet, and freezing rain
- Severe Thunderstorm Warning
- Thunderstorms with winds above 57 mph have been visually sighted
- Statistical Forecast
- forecast made based on computer simulations that use actual conditions
- Warning
- hazardous weather is imminent or actually occurring
- Outlook
- how average weather conditions for a month or season compare to normal ones
- Wind Chill Advisory
- wind chill temps -30 to -35F and below
- Probability Forecast
- forecast based on historical data
- Likely to Have Precipitation
- numerous showers, 60-70% chance
- Numerical Weather Prediction
- a set of equations to describe how atmospheric conditions change with time, computer system uses 3-D grid to make time-step predictions
- Severe Thunderstorm Watch
- Thunderstorms with winds above 57 mph are possible
- Watch
- atmospheric conditions favor hazardous weather
- Problems with forecasting
- models are simplified, original measurements are inaccurate, don't have complete info because of uneven distribution of observation stations on the Earth, round-off errors
- Analogue Forecast
- pattern recognition, using previously observed weather patterns to predict what will happen in the future for similarly developing systems (used for predicting temp)
- Flash Flood Watch
- heavy rain may result in flash flood in the area