8. East of the Rocky Mountains, a storm which moves to the left of its normal track increases in intensity.
9. Storms with isobars closely crowded on the west and northwest generally move slowly and to the east or southeast, and the precipitation and high winds are maintained unusually long in the northern and western quadrants.
10. Storms with the isobars closely crowded in the south and southeast quadrants move rapidly northeastward and the weather quickly clears after the passage of the storm center.
Rules for Making Local Forecasts. As an illustration of what may be done by the local observer or the layman in formulating rules of weather forecasting for his immediate vicinities, the following rules, which were evolved by the writer in 1892, while serving as the Weather Bureau local forecaster for Milwaukee, Wisconsin, are subjoined:
1. In summer warmer weather occurs after the center of the Low has passed a little to the east, and southwest winds are blowing, because the easterly winds, which otherwise would be the warmest winds, are cooled by passing over the lake.
2. A Low from the northwest that reaches western Minnesota and western Iowa without precipitation or clouds will pass over Wisconsin as a dry Low, unless the isobars are closer than five eighths of an inch.
3. Light frosts will occur on clear, quiet nights in the cranberry marshes when minimum temperatures at Duluth and La Crosse fall to 40° and 45° respectively. When these stations record five degrees lower the frost will be killing in the cranberry marshes and light in the tobacco fields of the southern counties of the State.
4. No frost will occur in the counties bordering on Lake Michigan until the temperatures at the Weather Bureau stations fall close to the freezing point, such is the influence of the lake in storing up heat and slowly radiating it during the night; and on the eastern side of the lake its protecting influence is much greater.
5. When the wind sets in from points between south and southeast and the barometer falls steadily, a storm is approaching from the west or northwest, and its center will pass near or north of the observer within twelve to twenty-four hours, with wind shifting to northwest by way of south and southwest. When the wind sets in from points between east and northeast and the barometer falls steadily, a storm is approaching from the south or southwest, and its center will pass near or to the south of the observer within twelve to twenty-four hours, with wind shifting to northwest by way of north. The rapidity of the storm’s approach and its intensity will be indicated by the rate and the amount of the fall in the barometer.