Atlanta is located in northwestern Georgia. It is located in the foothills to the south of the Appalachian Mountains at an elevation of 320 m. The city is pretty unimpeded from Gulf air from the south or Atlantic moisture from the east, should a favorable wind direction set up to transport heat and moisture but it doesn't look like there will be much of that in our first week of forecasting. Time to stalk the airport!
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KATL is Hartsfield-Jackson Atlanta International Airport and is located to the southwest of the city center. KATL's WMO ID is 72219. The only topography around is about 100 km to the north. Be sure to check in with the local NWS WFO which is the Peachtree City office. A convenient quality of KATL is that it is located in our timezone (EST) to minimize conversions for us!
Large-scale Pattern:
The forecast upper-level pattern according to the GFS for the start of our first week of forecasting for Atlanta shows a large-amplitude trough across most of the Eastern CONUS persisting throughout the entire week with a few shortwave impulses forcing some sensible weather. This first week would be a bad one to take climatological values for late January temperatures (50s/30s) given this trough inducing Arctic air to reach the city. The first day of forecasting should provide some challenge regarding precipitation amounts but at least we don't have to worry about precipitation type, just QPF. See the section on precipitation below for some useful resources.
Tips/Comments for Forecasting in General:
- Check out the current weather first via satellite, radar, surface observations, METAR, etc. You have to understand the present before you can look to the future.
- Get a feel for general pattern from NAM, GFS, etc. (available from here and here, for example). Identify the general pattern of low and high surface pressure systems and their progression, temperature advection at 850 mb, moisture at 700 mb, vorticity at 500 mb and the general jet structure at 300 mb. Make sure you are focusing your attention on Atlanta.
- Look at forecast model soundings for the period for KATL.
- How are the models evolving in time? Check out d(model)/dt plots like this one that focuses on the GFS.
- Ensembles are your friend. Here's a cool page for some spaghetti from the GEFS.
- Compare your idea for values with MOS (model output statistics). Keep in mind these are instantaneous output values and you can always have values above/below that between output times.
- Read the Peachtree City, GA WFO forecast discussion for info on KATL. These are the experts for that location, after all!
- Other universities have great WxChallenge-specific pages:
Tips/Comments for Forecasting for High/Low temperature (Fahrenheit):
- Recall such basics as nighttime radiative cooling and daytime solar radiative heating, both of which are affected by cloud cover and fog. Should there be snow-cover (even in Atlanta!) then temperatures can potentially be a bit colder due to snow's reflective properties and low heat capacity.
- Frontal passages can affect your temperature forecast. Pay attention to the forecast timing of such frontal passages especially right at the start of our first week of forecasting for KATL!
- Given quiet synoptic players, the evening dew point can act as a rough guess for the nighttime low (some forecasters use this as a first guess when they think the model output statistics (MOS) is bonkers). Therefore the wind direction may be a good indicator of humidity which may affect the nighttime temperatures.
Tips/Comments for Forecasting Wind Speed (knots):
- NWS outputs wind speed in mph so if you are comparing your forecast value to theirs keep that in mind. Otherwise the models output wind speed (WSP) in knots.
- Look through METAR or surface obs for wind direction and temperature changes.
Tips/Comments for Forecasting Precipitation (inches):
- Take a look at some higher-resolution models (e.g. WRF, hi-res NAM) or compare a whole bunch at once using a meteogram (ISU)
- What does the WPC show?
- Take a look at some GFS model-derived standardized anomalies of precipitable water (PWAT) to get a handle on any significant movement of the forecast of dry air or very moist air.
- Take a look at some ensemble data (e.g. SREF (South Central option) or for a zoomed-in national look try here.)
- Most products you will be looking at will output the QPF in inches already so no conversion is necessary. Recall that we are forecasting for the liquid precipitation so if the forecast calls for snow, make sure you aren't forecasting 4 inches-- use the liquid equivalent.
Be sure to check out a previous post found here for a long list of great resources that you should check out! Most of them are also found on Dr. Colle's Coastal Meteorology and Atmospheric Prediction (COMAP) group's website. Please feel free to comment below with any cool sites or tools that you've discovered from your experience!
I hope that you are excited to begin forecasting for Atlanta, GA. The first forecast city of the Spring semester is always the city in which the American Meteorological Society's (AMS) Annual Meeting is held. The AMS Annual Meeting will be held from 2-6 February 2014 at the Georgia World Congress Center. A few graduate students and at least one undergraduate that I know of from SBU will be attending along with Professor Colle. If you aren't a Student Member of the AMS, I would highly recommend it as it provides great insight into the field at large as well as scholarship and networking opportunities. So if you want forecasting insight during the second week of forecasting, just pester those attending the conference! Best of luck forecasting for this cold period for Atlanta, GA. Go Team SBU!!!
