# Lab 6: Synthesis and Quasigeostrophic Assessment

In this lab, you will be working with the WRF-NAM 36 h forecast gridded data from the initialization at 12 UTC 12/10/09. Please remember to place the date and time marker in any wxp command you use (otherwise, you will be using the data from 12/11/09).

Each student should print all charts, and complete the analyses that supports their own discussion assignments. At the end of class, staple the charts, and that, together with my evaluation of your presentation, will be the basis for the grade in this assignment.

**1. All Students**

(a) You will need to print the following NAM charts:, 36 hour forecast 500 mb heights and absolute vorticity; 36 hour forecast surface isobars and 1000-500 mb thickness; and 36 hour forecast 700 mb contours with 700 mb relative humidity.

nam_maps nam_thick 09121012 –ft=h36 -p

nam_maps nam_vort 09121012 –ft=h36 -p

(b) You will need to print the following NAM forecast using mod_grib :, 36 hour forecast 500 mb absolute vorticity advection; 36 hour forecast 500 mb vertical velocity (positive values show upward motion); 36 hour forecast 300 mb convergence (negative values show divergence); and 36 hour forecast 850 mb temperature advection.

mod_grib -ft=h36 -lev=500 -var=vadv -in=2 -re=36,-122 -p

mod_grib -ft=h36 -lev=500 -var=vvel -in=2 -re=36,-122 -p

mod_grib -ft=h36 -lev=300 -var=conv -in=1 -re=36,-122 -p

mod_grib -ft=h36 -lev=850 -var=tadv -in=0.5 -re=36,-122 -p

1. Draw advection arrows and fronts for the boxed area on the thickness forecast.

2. Estimate the nature of the vorticity advection at locations A and B by drawing either a green circle (for cva) or a brown circle (for ava).

**2. Breakout Groups**

*Grad Student Group - Chris and Sang*

Comment on the quasi-geostrophic forcing for upward motion at 700 mb at locations A and B, as discussed in class, using the two nam_maps charts.

*Sang Group - Sang (facilitator), Xiu, Vanessa, Lexie*

- Comment on the degree to which the mod_grib 500 mb vorticity advection plot is consistent with your results in
**Part 1 (b) 2**above. - Comment on the degree to which the mod_grib 300 mb convergence and the mod_grib 500 mb vertical velocity plot illustrates Dines Compensation at location B.

*Chris Group - Chris (facilitator), Nick, Jaq*

- Comment on the degree to which the mod_grib 850 mb temperature advection plot is consistent wiht your results in
**Part 1 (b) 1**above. - Comment on the degree to which the mod_grib 300 mb convergence and the mod_grib 500 mb vertical velocity plot illustrates Dines Compensation at location A.