DEPARTMENT OF GEOSCIENCES San Francisco State University NAME _______________________________

Metr 201 Synoptic Metr Quiz # 5

100 pts.

A.    Radar.  (5 points each for a total of 15 points in this section).

Figure 1:  Radar Analysis for 1749 UTC 11 February 2005

1.  Convert the time and date to PDT __10:49 AM PDT or 1049 PDT 11 February 2005

If you noticed the typo and converted to PST, the correct answer is: 9:49 AM PST or 0949 PST 11 February 2005

2.  The overlapping white circles on the map of the United States indicate what?

The white regions are areas with radar coverage by the National Weather Service's Doppler Radar network.

3.  Why is there a grey area shown in eastern California extending into central Nevada?

This is a region without radar coverage, mostly because of high mountains blocking radar beams.

B.        Satellite.  Examine Figures 2 and 3, and note the locations shown at A,  B and C on both images. (50 pts)

Figure 2:  Visible Satellite Image, 1730 UTC 11 February 2005

Figure 3:  Enhanced Infrared Satellite Image, 1730 UTC 11 February 2005

1.  Which of the three locations has the clouds that are most likely be towering the highest in the troposphere and why?  (20 pts)

The clouds at location B have the coldest tops (as indicated by the blue colors on the infrared imagery).  We make the assumption that these clouds are towering from the ground to the level in the atmosphere at which the temperatures are very cold, which is almost always at high elevation. Also, the visible image shows the brightest white in this area, suggesting thick clouds reflecting much of the incident solar radiation. Finally, the visible image suggests shadowing, which occurs when clouds are towering. The combination of all of these suggests the possiblity of thick clouds, possibly cumulonimbus, which often are associated with heavy precipitation.

2.  Here are the three cloud types that are occurring at either location A, B and C:  stratus, altostratus, and cumulonimbus.  Insert these cloud names at their most likely location.  You may only use the cloud type once: (15 pts)

Location A __stratus

Location B _cumulonimbus

Location C __altostratus

3.  The temperature of the cloud tops at location B is (15 pts)

(a)  10C

(b)  20C

(c)  -10C

(d)  -55C

(e)  0C

C. Synthesis. (40 points)

The graphic below shows a combined radar image, infrared satellite image and surface data plot for around 1700 UTC, 29 April 2009 (N.B.: the times for each are not quite the same, but are roughly coincident with 1700 UTC).

Comment on the extent to which the information given on the radar image is consistent with the information shown on the satellite image and surface data plot. This can be done in four to five sentences. As soon as you find yourself writing paragraphs, you are on the wrong track and providing much too much detail. (Answer on the back or on a separate sheet).

This is a case we examined in class. The radar analysis shows an area of strong thunderstorms and heavy rain extending from the Texas-Oklahoma border northeastward. We would expect to find very cold temperatures on a satellite image associated with the anvil of these thunderstorms, with the coldest temperatures where the thunderstorms are most active. This is exactly what we find. Finally, the surface plot should corroborate the radar and satellite imagery by showing surface observations of present weather of thunderstorms, and rain. This is also the case.