OVERALL OBJECTIVE: To familiarize the forecaster with GENERAL trends in frequencies of winter weather events in the contiguous US (ConUS), as a function of time of year, geographic locations, type(s) of hazards, and spatial/temporal scales. By the end of training, forecasters should be able to:
1. Recognize general seasonal and monthly trends in overall winter weather event frequencies in the ConUS;
2. Recognize relative frequencies of occurrence of primary winter weather hazards (heavy snow, ice, blizzard conditions);
3. Identify important geographic variations in winter weather frequencies, including recognizing general locations of enhanced or suppressed frequencies of heavy snow, ice, and blizzard conditions.
OVERALL OBJECTIVE: To familiarize the forecaster with general weather patterns associated with winter storms, for various regions of the country. By the end of the session the forecaster should be able to:
1. Identify the three most common synoptic patterns associated with heavy snow in the Midwest.
2. Identify the three most common synoptic patterns associated with heavy snow in the eastern U.S.
3. Identify the three most common synoptic patterns associated with heavy snow in the western U.S.
4. Identify the two most common synoptic patterns associated with heavy snow over the Colorado Front Range.
5. Recognize general synoptic- and subsynoptic-scale characteristics commonly observed with heavy snow events in the south central US.
6. Identify the two most common synoptic patterns associated with heavy lake effect snows.
LOCAL AND REGIONAL INFLUENCES
OVERALL OBJECTIVE: To understand regional tendencies and local effects that are important for forecasting of the location, timing, and amount of significant winter precipitation in the U.S.
1. Learn common deficiencies in understanding and forecasting the formation, amount, and timing of winter precipitation across the U.S.
2.Understand unique factors that influence the forecasting of frozen precipitation in mountainous western states compared to the southeastern states.
3. Identify regions of the U.S. where the following processes or forecast methods for significant winter precipitation are best suited, or are especially difficult to forecast:
*Temperature of moist layer
Review synoptic, subsynoptic and mesoscale processes, analysis techniques,
and conceptual models of winter weather events.
1. Objective: Use threshold values to specify and identify the spatial extent and location of meteorological processes.
2. Objective: Recognize features that are common in a variety of meteorological fields, such as troughs, ridges, minima, maxima, inflection points and saddles; use conventional depictions to represent each feature on a composite chart.
3. Objective: Given several horizontal or vertical charts, use compositing techniques to determine the vertical orientation, slope and extent of features such as ridges, troughs, highs, lows and fronts.
4. Objective: Given several cross-sections, determing the extent and thickness of stable layers and moisture plumes.
5. Objective: Recognize common structures that occur in atmospheric flows, such as currents, circulations, confluent and diffluent zones.
6. Objective: Use available data to assess any deepening or amplification of troughs, lows, fronts, etc; obtain the speed and direction in which the pattern is moving.
7. Objective: Locate and recognize advective processes that are feeding ongoing processes in an initial configuration of the atmosphere.
Conceptual models as visualizations of combinations of
physical processes, and diagnostic techniques required to identify them.
1. Objective: Given the conceptual models which incorporate the relationships of surface and/or upper air features (parameters)used in winter weather forecasting; identify areas relative to these features which favor the production of heavy snow, freezing rain and/or sleet.
2. Objective: Given the conceptual model(s) of specific snowstorm type(s) based on very general surface and upper air features (parameters), identify the general area(s) where heavy snowfall is most likely to occur.
3. Objective: Given the interacting physical processes (and their defining parameters) needed to produce winter weather, identify the analysis techniques and/or parameters required to help resolve the areal threat of severe winter weather.
4. Objective: Using the interacting physical processes needed to produce severe winter weather and composite techniques, be able to construct a composite chart(s) and identify the area(s) most likely to have heavy snow, freezing precipitation, and/or sleet.
-Without references, describe the two forcing terms in the QG-Omega Equation.
-Discuss which of the two forcing terms is usually more dominant in the low levels.
-Explain why QG-Omega cannot be measured directly in the atmosphere.
-Describe why vorticity advection must be evaluated on more than one level.
-Describe a method that approximates QG-Omega using easily available model fields.
-Explain what a Q-vector is and what it physically represents.
-Explain how Q-vectors can be used to diagnose upward motion.
- identify thermodynamic structure typically associated with snow, rain, freezing rain, ice pellets, and freezing drizzle;
-identify and discuss two processes that can change the thermal stratification;
-explain two factors that can affect the growth rate of ice crystals;
-determine whether latent heat is removed from or added to an air parcel when either evaporation, sublimation, melting, freezing, or condensation occurs;
-identify atmospheric conditions that are conducive to maximum dendritic crystal growth and why these conditions are improtant;
-understand how precipitation-type is determined using the meso-eta model output.
-Compare and contrast summer and winter convection.
-Given a cross-sectional analysis, identify areas of potential CSI.
OTHER WINTER WEATHER FORECAST TECHNIQUES
-Identify synoptic scale features at 500 and 850 mb that can assist in forecasting winter weather.
-Identify thickness values important for precipitation type forecasting.
-Using an isentropic surface, as well as wind and mixing ratio on that surface, calcualte the average 12 hour mixing ratio for a specified point.
JET STREAK STRUCTURE AND INTERACTION
Identify two mechanisms for the formation of low-level jets.
Identify and explain the vertical motion field and the direct/indirect transverse circulations associated with jet streak(s).
Identify jet structure associated with cyclogenesis.
CONCEPTUAL MODELS OF AIRMASS MODIFICATION OVER WATER AND MOISTURE RETURN
Describe the process of modification of air masses over bodies of water.
Understand the fundamental concepts of moisture advection and moisture transport, and their role in the overall hydrologic cycle.
Recognize biases in numerical guidance associated with moisture return.
REVIEW OF SATELLITE INTERPRETATION TECHNIQUES
Identify features such as jets (and associated vertical motion fields), cyclones, vorticity maxima, etc. using satellite imagery.
Identify areas favorable for the ongoing occurrence of heavy snow.
Identify preferred enhancement curves for identifying areas of convective snows.
By analysis and observation of output from NWP models, forecasters will be able to support/discount the individual models as useful forecasting tools.
OVERVIEW / PHILOSOPHY OF MODELS:
1. Without references describe the intended use of NWP model solutions in the forecast process.
2. Explain the basic historical perspective and future trends of NWP models.
1. Briefly summarize the role and limitations of:
- Using discontinuous grid points to represent spatially continuous motions in the atmosphere.
- Surface and boundary layer parameterizations
- Moist convective parameterizations
- Parameterization of condensation and precipitation processes on the scale of the model grid.
- Radiation parameterizations
- Data Assimilation
NCEP OPERATIONAL MODELS
1. Identify the 3 primary NCEP operational models.
2. List 3 reasons why these models are preferred over other models.
3. List the timing of of model packages.
4. Discuss the effects of initial conditions, boundary conditions, data assimilation and data cutoff upon model output.
5. Describe the differences between gridded files v. sounding files.
6. List and Discuss 3 known biases in the Eta...NGM...and RUC/RUCII.
7. Identify 5 known strengths/weakness of the ouput from the Eta...RUC/RUCII and NGM as pertains to winter weather forecasting.
8. Explain the concept and hazards of using model guidance in the 0 - 12 hour range for operational forecasting.
1. Identify 3 experimental models that are useful in Winter Weather Forecasting.
2. Identify the primary weakness and strength of each experimental model.
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