City #3: Norman, OK (NRMN)

Forecasting for Cheyenne, WY is officially over and we are moving on to an exciting addition to the WxChallenge. We will now be forecasting for a Mesonet station in Norman, OK (NRMN). This is not a METAR site at an airport as we are used to with available ~hourly data. The Oklahoma Mesonet is a network of high temporal and spatial observations. Data is collected approximately every 5 minutes and observations from these stations can be incredibly interesting when they observe a frontal passage or any mesoscale or convective boundaries. We will be forecasting for Norman, OK (NRMN) for the 24-h period (06 UTC - 06 UTC) from 28 October - 7 November which is 1 AM - 1 AM CDT for the first week of forecasting but is 12 AM - 12 AM CST for the second week of forecasting thanks to Daylight Savings Time ending on 3 November. So that means that forecasts are still due at 00 UTC which is 8 PM EDT for the first week of forecasting for Norman but at 7 PM EST for the second week of forecasting for Norman! Please, please, please remember that! I'll walk by Professor Colle's class on Monday, 4 November playing this from my phone just in case...






Time to stalk NRMN! Norman, OK is located in central Oklahoma due south of Oklahoma City which means it is incredibly flat. The observation site is located right near the ASOS station for Norman, OK (KOUN) at the Max Westheimer Airport. It is collocated with the University of Oklahoma Research Park (where the NWS forecast office used to be) where they have a dual-pol radar and a phased-array radar that they test and you can see by zooming in on the satellite imagery below. The airport is located to the northeast of the National Weather Center which houses many things including NSSL, SPC, The University of Oklahoma Meteorology Department and the Norman, OK NWS Weather Forecast Office. If you ever have an opportunity to go to the National Weather Center- definitely go. I spent a weekend there in January and then an entire summer there in 2010 and it was an incredible experience with very interesting weather. Anyway, the Mesonet site has a great page devoted to it with panoramic photos and a ton of information so I would definitely check it out. A live webcam image can be found on the WxChallenge site information page for NRMN. For a meteogram of the data, click here. Even though the observational data is available at a higher temporal frequency than the ASOS data we are used to, the rules for the WxChallenge are not changing in any way except that the verification will come from the 5-minute data instead of the hourly and the wind data is going to come from the 5-minute 10-meter wind sensor instead of the 2-m wind. A cool thing about this is that our scores will actually be updated every 5 minutes instead of every hour... although that might drive some people insane if they are prone to compulsively checking the scores. ;-) For a full list of rule changes and site information for NRMN, please consult the WxChallenge page.



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Large-scale Pattern: 

The forecast upper-level pattern for the start of our first week of forecasting for Norman, OK is tricky. There is an upper-level low that is strengthening over the Rocky Mountains (deepening trough) which will allow for some ridging downstream which may usher in some warm, moist air into Oklahoma. There may be some weak upper-level disturbances out ahead of the main system that, combined with the moisture gradient across the region, may force some showers and thunderstorm activity. The low should move eastward and cause some precipitation for NRMN sometime mid-week. The timing of the frontal passage and the strength of the pre-system disturbances are still a bit up in the air... literally. For the rest of the time forecasting for Norman, the AO is expected to trend negative which may mean amplified flow and consistent disturbances tracking across the US. The GFS in its "dreamland" hours (> fh 180) hint at this type of pattern. We'll see!

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. Use Norman, OK (KOUN) in place of the Mesonet Site (NRMN) but to check out the current observations with the Mesonet site you can look at an updated meteogram. And also see the 3-day observation history for NRMN.
• 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 Norman.
• Look at forecast model soundings for the period for KOUN (close enough to NRMN).
• How are the models evolving in time? Check out d(model)/dt plots like this one that focuses on the GFS.
• 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 Norman WFO forecast discussion for KOUN/NRMN. These are the experts for that location, after all! 
• Other universities have great WxChallenge-specific pages:
• http://www.atmos.washington.edu/~wxchallenge/
• http://www.meteor.iastate.edu/ams/wxchallenge/

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.
• Frontal passages can affect your temperature forecast. Pay attention to the forecast timing of such frontal passages.
• 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.
• i.e. southeasterly winds should be more moist which means a higher dew point which means a higher nighttime temperature and northwesterly winds will advect drier air which means a lower dew point which means the possibility for lower 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. For example, because of the flat terrain, advection plays a major role especially with deep troughs allowing for cold, Canadian air to spill into the Central US.

Tips/Comments for Forecasting Precipitation (inches):

• Take a look at some higher-resolution models (e.g. WRF)
• What does the WPC show? 
• Tropical activity?
• 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.

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!

Alright guys- I hope you are excited to forecast for a Mesonet station for the first ever time in WxChallenge history!!! Norman, OK is an awesome city (Boomer Sooner!!!) and is very vulnerable to air masses coming from any direction because it is just so flat and in the middle of everything. If you ever have any questions please feel free to stop by my office in Challenger 121. I still have candy. That is all. Good luck with NRMN and let's go Team SBU!!!