Weather conditions have been typically observed to successfully repeat itself on several days in a row within specific areas. Weather may be seen occurring for several days as consistently being cold, hot and dry, or even rainy. Weather conditions which have the tendency to display repetitive characteristics have been referred to as weather patterns.
Meteorologists have over time found it quite common to find specific weather conditions within a given location to be locked within a repeating pattern on a daily basis.
A weather pattern which may occasionally display any instance of sudden change, such as seen in consistent rainfall for a week followed by sunny dry weather for the following two weeks is seen as a distinctive change in weather pattern.
Upper level flow patterns have been categorically seen as the main and determining factors for specific weather patterns within the mid-latitudes. Jet stream winds on close examination have revealed that certain regions with lower than normal temperatures and slightly above normal are more likely to experience specific weather patterns. Surface areas forecasted which have the tendency to be located within a trough will tend to exhibit cooler climates than normal.
Similarly if a surface area’s location allows it to be continuously be located within a ridge, then the weather climate associated will generally tend to be much warmer than usual. This observation has allowed the conclusion to be formed that areas located within ridges and troughs can experience weather conditions in locked patterns occurring from a few days to several weeks at a time.
Such regions have been known to have the tendencies to be affected by severe instances of drought patterns or consistent flooding relative to their location as the regions will be warmer in some instances and cooler in the other.
Winds affecting a location from a southerly direction will tend to impact those regions with a warmer climate than normal. Similarly regions mostly affected by winds approaching from a northerly direction will tend to have a much cooler than normal weather condition. Specific regions within designated areas between the trough to the ridge and impacted by winds approaching from a southerly direction are most likely to be affected by instances of rainfall.
The possibility of rain within such areas is also increased in the event that a high concentration of moisture is brought by those southerly winds. If the winds approaching from the southerly direction were originated within a climatically dry region such as those associated with a desert, then what will be experienced is more of a dry weather.
However regions located between the ridges to the trough which are affected by winds from a northerly direction will tend to have a much drier climate due to the fact that air which is cooler does not contain high levels of moisture as northerly winds have often been observed to have lower dew points.