Steps to a good surface analysis


1. Assemble all your analysis tools: (a) clean copy of plotted data; (b) for rough draft - grease pencils, clean acetate, alcohol and rags; (c) for final draft - colored pencils and pens.

2. Examine previous chart for positions of highs, lows, fronts and boundaries. -Previous" means 3 hours to 6 hours in advance. Even a chart for 12 hours previous will help.

3. Examine the 500 mb chart to obtain a mental picture of the synoptic-scale dynamic controls. Use a synoptic-scale plot of surface isobars and 1000-500 mb to judge the rough position of surface synoptic boundaries (cold, warm, starionary and occluded fronts, dry lines). Examine the plotted data to "characterize" or "diagnose" the patterns on it. Mentally note any circulations apparent, large wind shifts etc.

4. In colored pencil, lightly shade a circle (about 1/4" outward" from each station that reports present weather using the color coding posted on the wall).

5. On acetate, find the lowest or highest pressure and start drawing IN BLACK isobars as follows: (a) 4 mb interval; (b) isobars on surface charts are drawn STARTING with 1000 mb (e.g., 1000, 1004, 1008, 1012 etc). Make sure to label Highs (blue H) and Lows (red L) at the center of the patterns, and to label isobars clearly so you dont get confused when you transfer. For mesoanalysis, depending on the size of the region covered, use a 2 mb or a 1 mb interval, as needed. (Generally, 1 mb interval for the isobars works for only regions that are subsynoptic in size, for example a couple of hundred km in diameter or smaller).

6. Examine the previous analyzed chart (if you have one) (such charts are called the synoptic HISTORY) for locations of fronts, boundaries, highs and lows. It is highly unlikely that such features either disappear or move erratically. In other words, a cold front on the HISTORY should appear on your chart. It should not disappear or back up. If you analyze a series of charts, there should be a logical progression (based upon sound meteorology) of features. Highs and Lows should NOT appear and disappear, or jump around the map.

7. Draw a first guess for frontal positions based upon the techniques discussed in class.
8. Adjust the position of fronts to match wind shifts, etc. and then kink the isobars at the front AWAY from low pressure.

9. Show rough draft to instructor for OK.

10. Transfer to hard copy using the light tables. Final analysis MUST be neat. No erasures. No grease pencil. Isobars - black (or pencil); cold fronts blue; warm fronts red; occluded fronts purple; stationary fronts alternating blue and red; dry line, brown broken open warm front (scallops) symbols. If isotherms are drawn, they should be dashed red; isodrosotherms, dashed green.