Monday, December 2, 2013

City #5: Grand Rapids, MI (KGRR)

Congrats on making it this far in the WxChallenge and on your performance so far this semester. While we are certainly not the best team as that is currently UAlbany (at least it's a fellow SUNY, right?), we are doing okay at 40th place. The final forecast city for the Fall semester is Grand Rapids, MI (KGRR). We will be forecasting for the 24-h period of 06-06 UTC (1 AM - 1 AM EST) from 2-12 December before taking a break until we start up again in the Spring.

Grand Rapids, Michigan is located about 50 km (25 mi) east of Lake Michigan on the Lower Peninsula of Michigan and is situated on the Grand River. Even though it is displaced from the shore of the lake, it is still a susceptible city to lake effect or lake-enhanced precipitation. There is no real topography to deal with and KGRR is at an elevation of 245 m. Time to stalk the airport!



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KGRR is Gerald R. Ford International Airport and is located to the southeast of the city center. KGRR's WMO ID is 72635. There is no real topography around and there is a mixture of more developed land to the west versus more tree-filled neighborhoods to the east. Remember that "great" lake to the west, though. Be sure to check in with the local NWS WFO which is the Grand Rapids office. A convenient quality of KGRR 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 Grand Rapids shows an amplifying pattern throughout the week that is associated with the development of a low pressure system sometime mid-week (there's some model disagreement about the timing). Throughout the week there's a pretty steady chance of light precipitation, especially within the next couple of days with the passage of a warm front ahead of the strengthening low pressure system. A good tactic for dealing with precipitation forecasts like this is to look at some plume diagrams that show the differences between the models and then return to each model and check out some key levels (e.g. is the 850 mb temperature advection too overdone or is there a stronger jet at 300 mb or more positive vorticity advection at 500 mb?).


Tips/Comments for Forecasting in General:


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 especially right at the start of our first week of forecasting for KGRR!
  • 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)
  • 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.
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 you are Team Jacob because Grand Rapids is Taylor Lautner's hometown as well as Reed Timmer's which is more appropriate given our field of study. Best of luck forecasting for KGRR! Go Team SBU!!! Have a very Happy Holidays and enjoy your Winter Break! We'll resume forecasting on 27 January 2014. 

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