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The Weather See-Saw: or Is it Winter yet? - 12.31.04
Recent radical shifts in the jet stream are elusive patterns difficult to see two years in advance. Learn why in this article.
It's enough to make a grown, long-range weather forecaster cry! On Christmas there was a record snow in Texas, and five days later, the temperatures there hover around the seventies and eighties. In the middle of this winter heat wave in Texas there was a heavy snow in Colorado, the neighbor to the north. A few days later people in the Carolinas who were skidding across the roadways on black ice a few days earlier bask in spring like conditions. Speaking as a climatologist the culprit for these events is a shifting see-saw pattern known as the PNA or Pacific North America pattern.
Fig.1
The first image shows the conditions at the beginning of the last week of December 2004 when a strong high on the West Coast pushed the jet stream up into Alaska causing temperatures to plummet in the eastern half of the country. This occurs when the east Pacific high-pressure area comes close to the coast. In that position the jet stream can't drop down along the West Coast but is pushed up over the Canadian Rockies. This positioning was supported by a series of planetary aspect that produced strong high-pressures against the coast starting with a nodal shift on the 15th of December.
Fig.2
Figure 2 shows the position of the jet stream after Mercury went off station on December 24th and then was followed by a Jupiter motion in arc to low pressure values over the eastern Pacific. The pattern illustrated here is the negative PNA pattern. The blocking high that was against the coast is now positioned far to the west in the Eastern Pacific. This shift allowed the polar jet stream to drop to the south along the coast bringing cold down into the Denver area and opening the storm door on the West Coast. As can be seen in the chart this pattern also allowed a strong high to build over the southeast. The circulation around this high brought warm moist Gulf of Mexico air into the continent. It is this feature that supported the shirtsleeve temperatures along the Gulf coast and Texas, where a few days earlier, it was snowing. The shift of the high to the west in the eastern Pacific was coincident with a Mercury motion in arc event that shifted the high-pressure value to the western most 45�° jet curve
. This shift allowed the polar jet to drop to the south more easily on the West Coast. The kicker was that a few days later Jupiter moved in arc to low-pressure values on the easternmost 45�° jet curve in the eastern Pacific and it has been storming there ever since.
These sequences show clearly the three levels of activity used by Doc Weather to see into future patterns. The three levels involve planetary configurations in different ways. The first level is the fundamental placement of the eclipse points in longitude. These positions project the eclipse grid onto the earth in specific longitudes. The most sensitive structure in the eclipse grid is the disturbance diamond Later in this article this feature will be placed in the context of the unusual weather for December 2004. The second level of activity in the charts is the angular aspects of the planets in relation to the eclipse points. The following descriptions will show how these aspects have combined to make an unusual situation this year. The third level of activity is the most dynamic. This is represented by what Doc Weather calls a "spasm" pattern. A spasm happens when a unique transiting situation adds extra energy to the atmosphere in a particular location. The "spasm arises when a transiting planet overtakes another planet that is in a particular relationship to an eclipse point. The spasm represents the dynamic between the transiting planet and the sitting planet. This most often happens when either an outer planet is crossed by a fast moving planet or more severely, when an inner planet is just coming off of station moving direct and is crossed by another inner planet so that the two are moving in tandem. The tandem motion arising just after the stationary planet begins to move in arc puts strong storm energies into the atmosphere in the longitude of the spasm. A recent spasm in the last week of December 2004 arose when Venus crossed Mercury that was just coming off of station direct in the middle of Scorpio, on the 27th.of December. The two moved in tandem for a few days after that as strong waves of storms beat against the coast.
Fig.3
In order to see these sequences from a planetary perspective figure 3 depicts the primary planetary influences for the mid December pattern. Jupiter over Indonesia is influencing the solar point (green arrow) to high-pressure. Mercury on station near Hawaii (green arrow) is influencing the lunar point to high-pressure. The two highs from the jet curves from these points are near the western United States. The 45�° jet curves are supporting the high over the eastern Pacific. The 72�° jet curves from these points are supporting a high latitude high over western Canada. Between them is a 72�° jet curve from the lunar node that is aspecting the solar point over the eastern Atlantic to low pressure (orange arrow). The 72�° jet curve from this point (heavy red curve over the West Coast), is the site of the path of the cold air from Canada into the western United States. This was the path of many cold outbreaks so far this season and it was the source of the cold air that produced the recent Christmas snow along the Gulf coast.
Fig.4
In figure 4 we see the aftermath of two motion in arc shifts between Christmas eve and the 28th. On the 23rd of December Mercury moved off station near Hawaii. Instead of producing a high-pressure value on the lunar point Mercury now produced a low-pressure value. This meant that the easternmost 45�° jet curve from the lunar point was no longer supporting high pressure. The high that had been blocking over the eastern Pacific for two weeks suddenly moved west to settle over the western 45�° jet curve from the solar point. This opened the storm door a bit on the west Coast. A low from the Gulf of Alaska promptly slid into the door on Christmas day and started towards the West Coast. The passage of this storm was problematical since dropped almost vertically along the coast in a free fall as the block that had been in place since mid month, made such a rapid exit to the west. This storm missed most of the west Coast but as it turned to go east drifted into Southern California where it produced floods. There was little guidance for this storm just a vacuum and the need to turn to the east as it got farther south. Local weather forecasts had rain for four days in northern California and none of it arrived. This kind of storm is a difficult call to make since it is not a direct event that is the trigger but a lot of what pool shooters call "table roll".
However, on the 28th of December Jupiter and the node moved in arc. This complex motion shifted the values for the whole chart. In the eastern Pacific Jupiter was now putting strong low-pressure values on the lunar point (red arrow). This put a low in the eastern Pacific against the coast on the 45�° jet curve from the solar point (heavy red curve). This opened the storm door in the eastern Pacific resulting in widespread rains. To the west Jupiter put high-pressure values on the solar point (green arrow) resulting in the formation of a dominant high in the longitude of the Aleutians. This is an example of the negative PNA pattern in figure 2. The nodal influences also shifted on the same day with low pressure on the lunar point (orange arrow) and high pressure on the solar point in the Atlantic (green arrow). Taken together these shifts have accompanied the highly complex and unusual weather patterns of the past few weeks.
Fig.5
In figure 5 the chart for December through March 2005 is depicted. No air mass information is given but the jet curves from both of the points are placed with the 72�° jet curves enhanced and the disturbance diamond rendered in yellow. It can be seen that the nexus of the 72�° jet curves is over the Great Basin. In 2005 and early 2006 elements of this nexus will be active in the region of the PNW gate in the eastern Pacific (pink circle). This area is extremely sensitive to shifts in low and high-pressure values on the jet curves. In general the wildly fluctuating patterns last for about a year and a half, and then return again nine years later. This makes approximately three years out of ten years when the nexus of the disturbance diamond is in the vicinity of the PNW the weather tends to be very flighty and fickle. This is due to the tendency for the Pacific jet to oscillate between being pushed up into Canada (positive PNA) , or split and run down the coast in an el Nino like pattern (negative PNA). These two patterns can oscillate with each other with alarming rapidity. This makes long-range forecasts during these three years out of ten a bit more speculative than at other times. When this is coupled with a current spasm pattern arising from the tandem transit of Venus and Mercury approaching the West Coast of the US, we can expect that the unsettled and wild and woolly nature of the weather should continue at least through the middle of February when Mars transits the West Coast and things will settle down. It is interesting to note that the tandem transit of Mercury and Venus will continue for most of the month of January 2005. This should stimulate the el nino like pattern of the southerly placed Pacific jet for most of the month.