What I first like to do is stalk the airport where the verification of the forecast is taking place. I do this via Google Earth or Google Maps to see if there's a field, water body, or giant asphalt parking lot in a particular wind direction that may affect the high temperature, for example.
View Larger Map
So there is water to the East and South and developments immediately surrounding the airport and no significant topography around. Mental notes made.
After stalking the airport and before looking at model outlooks for the forecast period, I like to check out the climatological averages of temperature and precip. for this time of year. Provided below are the mean daily maximum and minimum temperatures for KPNS but check out the link for information about precipitation and extreme values. (Remember, these are just averages-- there's always exceptions!)
Month Daily Max Daily Min
Sep 87.0 70.4
Oct 79.3 59.6
Now that I've decided that I want to move there (actually, the humidity would get to me so never mind) it's time to look at what to expect when forecasting for this city.
Large-scale Pattern
A look at forecast 500-hPa heights according to the GFS shows that the ridge looks to build but pop-up showers and thunderstorms may form on the sea breeze. But all-in-all the pattern is looking pretty quiet.
What to watch out for (IMO):
- Isolated convection
- High and low temperatures may be tricky
- 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 Pensacola.
- Look at forecast model soundings for the period for KPNS.
- 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 Mobile, AL WFO forecast discussion for KPNS- they use words like "bugaboo" which is hysterical and they provide a lot of insight into the forecast.
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.
- Frontal passages, mainly cold frontal for KPNS, can affect your temperature forecast. Pay attention to the forecast timing of such frontal passages.
- NWS outputs wind speed in mph so if you are comparing your forecast value to theirs keep that in mind. Otherwise the models ouput wind speed (WSP) in knots.
- Due to the coastal location, there may be sea breeze development that has a cooling effect during the daytime. Look through METAR or surface obs for wind direction and temperature changes or try to spot it on the Mobile, AL radar and know whether to take it into consideration for certain days with weak synoptic flow.
- Take a look at some higher-resolution models (e.g. WRF)
- What does the HPC show?
- Take a look at some ensemble data (e.g. SREF)
- Most products you will be looking at will output the QPF in inches already so no conversion is necessary.
- When making a forecast for the first day only, always select the "Guidance" option for the "Optional Forecast for Future Days" days just in case you forget.
- It is advisable that you enter your forecast for the next couple of days when you enter your Day 1 forecast. They are not counted towards any score and it is just a good way to possibly save your score if you happen to forget to forecast the next day. However, you realistically likely only have enough time to forecast for the first 24-hour period so I always just select "Guidance" anyway.
