Lab 8: Case Study 2 and 3 (Winter)

All portions of Lab 8 are due December 2.

Case 2 is the ice storm on Dec. 8 2013. Case 3 is the 1st round of the "Snowmageddon" storm on Feb. 5th and 6th, 2010.

Use the link below to access the model data for Case 2. The model data is set up the same as for Case 1 -- 5 days of data, with a time interval of three hours:

http://wx.gmu.edu/pix/case2.html

Use the link below to access the model data for Case 3:

http://wx.gmu.edu/pix/case3.html

Surface maps and observed RAOB soundings (as Skew-T plots) can be found HERE for Case 2.

Surface maps and observed RAOB soundings (as Skew-T plots) can be found HERE for Case 3.

You can view hourly surface plots of SLP, temperature, and radar by looking at the archive on wx.gmu.edu:

HERE

Use the drop-down menu tabs to select the desired date and time, then press the submit button.

There will be more maps and data posted for these cases in the next week -- this web page will be updated then.

Update 2:

The link below will help with locating fronts. Go to the link and scroll down a bit to "Archive of United States (CONUS) Analyses". Select the date and time using the selection tools, then click the "Retrieve Archived Map" button.

You should still look at the surface data to fine tune the location of fronts. It is also very important to look at the front locations and evolution over a period of time during the event. The archive has maps every three hours.

http://www.wpc.ncep.noaa.gov/archives/web_pages/sfc/sfc_archive.php

Update 1:

A model run has been posted for case 2, for comparing with the observed data. The model is initialized at 12Z on Dec. 8, 2013. The first 36 hours of the model forecast is availabe, at a time step of every three hours. For the web tool, this means there are 13 times.

http://wx.gmu.edu/pix/model2.html

It is useful to view time-height cross sections at various points. Note that it does take a while for these to be done, so be patient. For an example, we use case2.html (link above). The grid point nearest to DC is longitude 77W and latitude 39N. Using the web tool, set the first longitude field to -77 and blank out the 2nd field. Set the first latitude field to 39 and blank out the 2nd field. For the level, set the first value to 1000 and the 2nd value to 400. For the time, set the 1st value to 21 and the 2nd value to 33 (this covers the time range of the ice storm event). For expression 1, use t-273.15. For expression 2, use vv. For GXout1, select contours. For GXout2, also select contours. For CINT1, enter a value of 1. Leave CINT2 blank. Now press the submit button, and wait a while. You will get a time-height cross section showing the warm air aloft and cold air near the surface. You will also see pressure vertical velocity, which helps to give an idea of the time periods of the heavier precipitation. The plot should be repeated with Expression 2 as rh rather than vv, to examine whether there is sufficient moisture for precipitation.

Lab 8 Part 1:

The 1000-500mb thickness can be plotted using the web tool using this expression:
z(lev=500) - z(lev=1000)

For case 2, plot features at the time of 00Z Mon. 9 Dec 2013. This is a Time Value of 25 on the web tool.

For case 3, plot features at the time of 00Z Sat 6 Feb 2010. This is a Time Value of 25 on the web tool.

Lab 8 Part 2:

Also, write a map and forecast discussion for these two cases. We will discuss these two cases in the lecture and lab over the next two weeks. Build on those dicussions for this exercise.