of cyclones and anti-cyclones on the synoptic chart. The following 

 thumb rules in relation to winds were found to be of aid in 

 antarctic forecasting: 



1. Favorable weather at Little America sets in very shortly 

 after the surface winds shift to the south. This shift is generally 

 accompanied by a marked drop in temperature. The shift of the 

 wind aloft to the south likewise denoted the approach of good 

 weather in the western portion of the Bellingshausen Sea. 



2. Good weather, both at Little America and in the Bellings- 

 hausen Sea, is maintained by southerly winds aloft. 



3. A wind shift from south to southwest in the Bellingshausen 

 Sea indicated the development of a weak cold front orientated 

 east-west near the edge of the ice pack and large areas of snow 

 showers, accompanied by low ceilings and very poor visibility in 

 the showers. 



4. A wind shift from the prevailing direction of southeast to 

 either east or northeast indicated the approach of a migratory low 

 pressure center from the northwest. Within the following 18 

 hours, heavy fog could be expected after the warm, moist air mov- 

 ing southward around the leading edge of the low had had a short 

 but sufficient trajectory over the ice pack resulting in cooling and 

 condensation. 



5. An increasing pressure gradient and resultant increasing 

 winds will not result in dissipation of fog formed on the southeast 

 quadrant of lows moving into the Bellingshausen Sea. In winds 

 as high as 30 knots the fog was thinned but visibility remained 

 less than 14 niile. 



6. On and near the continent, blowing snow extending to 100 

 feet above the surface is common when high winds (generally 

 above 17 knots) are blowing. It is difficult to distinguish this 

 phenomenon from an actual snowfall when observed from the 

 ground. Aviators flying at low altitudes should be emphatically 

 warned that blowing snow is extremely difficult to visually dif- 

 ferentiate from terrain and that in areas where sloping hillsides 

 might be encountered, the only safe flight is one at sufficient alti- 

 tude to be well clear of any such obstacles. 



7. Wind speeds were less near the center of wedges and in- 

 creased toward the edges. 



8. Extreme care should be exercised in keeping a check on 

 winds aloft, particularly in the 5,000 to 10,000-foot layer. Most 

 high pressure wedges are relatively thin and narrow and ap- 



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