What is a weather analysis?
A weather analysis describes the current three-dimensional picture of the atmosphere and provides a narrative to accompany this description. This often will require looking retrospective to understand why the atmosphere looks the way it does at any given point in time. For example, it is one thing to say there are clouds over the Cascades, but another thing to explain why there are clouds. This requires a geographic analysis in 4 dimensions, two dimensions in the horizontal, one dimension in the vertical and one dimension in time. A weather analysis should rely heavily on observations (surface and upper-level) over the past 12-24 hours in addition to satellite and radar imagery. Please visit links provided on the course webpage, or others available for this. Components of an analysis include:
Looking at the BIG picture:
Looking at current local weather analysis:
Keep in mind that a weather analysis is typically needed to provide context for a weather forecast.
An example of a great weather analysis is shown in a youtube video below.
A weather analysis describes the current three-dimensional picture of the atmosphere and provides a narrative to accompany this description. This often will require looking retrospective to understand why the atmosphere looks the way it does at any given point in time. For example, it is one thing to say there are clouds over the Cascades, but another thing to explain why there are clouds. This requires a geographic analysis in 4 dimensions, two dimensions in the horizontal, one dimension in the vertical and one dimension in time. A weather analysis should rely heavily on observations (surface and upper-level) over the past 12-24 hours in addition to satellite and radar imagery. Please visit links provided on the course webpage, or others available for this. Components of an analysis include:
Looking at the BIG picture:
- Discuss large scale (continental-to-hemispheric) patterns and locate major troughs ridges and jet streams from upper air observations and numerical weather analyses.
- Discuss satellite imagery as it relates to large weather features in the forecast region.
Looking at current local weather analysis:
- Discuss local satellite imagery and RADAR if available and of interest.
- Discuss regional surface analyses to identify surface temperature, wind and pressure patterns. Note if there have been any major changes in pressure fields within the last 24 hours.
- Discuss the local sounding, compare with yesterdays.
Keep in mind that a weather analysis is typically needed to provide context for a weather forecast.
An example of a great weather analysis is shown in a youtube video below.
What is a weather forecast?
Weather forecasts refer to predictions of the state of the atmosphere for a specific location at a specific time. There are many varieties of weather forecasts. For the purpose of this class we will focus on short-range weather forecasts that considers the state of the atmosphere 12-72 hours out. Weather forecasts should consider the state of the atmosphere at a given time and apply a variety of methods to anticipate how the atmosphere will evolve through time. Different approaches to creating forecasts include extrapolating current conditions forward in time using numerical models of the atmosphere that solve equations iteratively through time. As there are several different models run (typically at 0Z and 12Z each day), forecasters often consider model runs from several models in developing their forecast. The steps to a weather forecast include the following:
On the use of numerical weather model output
A nice example of a weather forecast from NWS Reno is provided below.
Weather forecasts refer to predictions of the state of the atmosphere for a specific location at a specific time. There are many varieties of weather forecasts. For the purpose of this class we will focus on short-range weather forecasts that considers the state of the atmosphere 12-72 hours out. Weather forecasts should consider the state of the atmosphere at a given time and apply a variety of methods to anticipate how the atmosphere will evolve through time. Different approaches to creating forecasts include extrapolating current conditions forward in time using numerical models of the atmosphere that solve equations iteratively through time. As there are several different models run (typically at 0Z and 12Z each day), forecasters often consider model runs from several models in developing their forecast. The steps to a weather forecast include the following:
- Understand the current weather analysis
- Identify the main forecast problem
- Discuss model forecasts for your region. Refer to large-scale features first.
- Discuss geographic setting and climatology for your location/forecast date.
- Discuss the derived model products.
- Make a forecast!
On the use of numerical weather model output
- Forecast models are a tool, not an end-all to forecasts, or a panacea for forecasters.
- Experienced and alert forecasters can add significant value to numerical weather forecasts.
- Forecasters, however, must have a basic understanding of model interpretation, biases and limitation of the models in different forecasting situations.
- Interpretation of model output needed to be rooted using a solid understanding of meteorological concepts+theory.
A nice example of a weather forecast from NWS Reno is provided below.