SAN FRANCISCO STATE UNIVERSITY                                                             Meteorology 403 DEPARTMENT OF GEOSCIENCES                                                      Fall 2004

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Midterm #1

250 Points

Part A.  Map Set 1 (70 pts)

 

Attached find the WXP analyses of 350 mb convergence and 850 mb convergence for 12Z 22 October 2004.  Note the station indicated by the point at the South Dakota/North Dakota/Montana border.

 

Compute the one hour surface pressure tendency for this point.

 

                                                      (1)

 

is the pressure tendency equation if w at top is zero and density advection is negligible.  In this case, "top" is the tropopause and "bottom" is the surface.

 

You may make the following assumptions which will simplify the procedure:

 

(a)        vertical motion is zero at the surface;

(b)       the 850 mb divergence is representative of the net divergence BELOW the level of

            nondivergence;

(c)        the 350 mb divergence is representative of the net divergence ABOVE the level of

            nondivergence;

(d)       the tropopause is at the 200 mb level and the surface pressure at station A is 850 mb (this station is not at sealevel);

(e)        the atmosphere is hydrostatic (will greatly simplify the equation).

Part B.  Map Set 2 (60 pts)

 

Attached find the 850 mb, 700 mb, 500 mb and 200 mb charts for12Z 22 October 2004. Also included is the Eta initialization for surface isobars and 1000-500 mb thickness.

 

1. Discuss why the trough over the central portions of the country "tilts" towards the west (in this case).

 

 

2. Draw advection arrows and fronts for the cyclone in the midsection of the country.
(This is the model you should have used, as discussed numerous times in class)

 

 

Part C.  Map Set 3 (80 pts)

 

Attached find sfcplot and a plot of unanalyzed surface observations for 12Z 22 October 2004

 

Analyze the surface plot inside the solid lines, using proper isobar intervals, color conventions, frontal/trough symbols etc. (no isotherms or isodrosotherms).  Use the 1000-500 mb thickness analysis from Part B to help you to complete the frontal analysis. (70 POINTS)

 

 

Part D.  Map Set 4 (40 pts)

 

Attached find the 12UTC soundings for Davenport, Iowa and Albuquerque, New Mexico; and the surface isobars and 1000/500 mb Thickness for 12Z 22 October 2004.

 

Do the following sets of questions:

 

1.   Note the locations of Albuquerque and Davenport labeled A and B, respectively. 

 

(a)       Plot the 1000 mb geostrophic wind vector at each location with a solid arrow.                                                 (You will have to qualitatively estimate the length of the vector).

(b)       Plot the thermal wind vector at the same locations with dashed arrows.  (Again,         you will have to qualitatively estimate the length of the vector..make it 4 times the length of the 1000 mb geostrophic wind vector you did in (a)).

(c)        Now, on the back of this sheet, replot these vectors in a manner that will allowyou to estimate the 500 mb geostrophic wind vector.  Replot the 500 mb geostrophic wind vector on the map.

 

2.         Describe how the thermal structure and wind profiles evident on the sounding/wind plot for Davenport and Albuquerque is consistent with your frontal analyses.