First Weather Pattern Yeti brought record snow to Boston; then Weather Pattern Government flooded Texas; for the past couple of weeks, Weather Pattern Hotzilla has spread steamy conditions across the south.
And with a change in the jet stream configuration taking place at this moment, Weather Pattern Westzilla is born.
What is the Current Weather Pattern?
Westzilla is a cousin of Hotzilla, the high latitude zonal flow which set temperature records from California to Carolina.
The jet stream is bending, and the new pattern will have a ridge in the west and a trough in the east. Heat will build to record levels in the west, including parts of the northwest that are normally cool at this time of year.
With hot air already in place over the desert, compliments of Hotzilla, it only takes a wind shift to southerly to bring the record temperatures northward. Here are some of the places that were hot spots in the southwest during the last two weeks:
- Phoenix, Arizona has been over 110 degrees for eleven straight days, topping out at 115 last Thursday, a new daily record.
- Las Vegas, Nevada has been over 100 for two weeks, with a record 113 last Saturday.
- Death Valley, California has been over 115 for two weeks. The highest temperature ever recorded on Earth was in Death Valley on July 10, 1913. This year’s highest so far was 123 last Saturday.
- Gallup, New Mexico reached 95 on four consecutive days, the first time that ever happened in June.
The Heat Moves North
As the jet stream develops the bulge in the west, the hot air will flow in underneath, reaching beyond the Canadian border: Hotzilla transforms into Westzilla. In addition, the high pressure at all levels in the atmosphere will produce a gentle subsidence. The sinking air warms as it descends. Here are some of the forecasts for Westzilla:
- Spokane, Washington will exceed its normal temperatures by over fifteen degrees for the next week. New daily and monthly temperature records will almost certainly be set over the weekend, perhaps by several degrees.
- Boise, Idaho is forecast to top the 100 degree mark for the next nine days, including a June-record 108 on Sunday.
- Portland, Oregon, normally in the 70s at this time of year, will be in the 90s for the next week, with temperatures possibly nudging 100 this weekend and next.
- Helena, Montana is forecast to reach 100 degrees on Sunday. It would be the first time the temperature ever hit triple digits in June.
- Vancouver, British Columbia, Canada is normally cool, with average high temperatures in the 70s. For the next week, temperatures will be in the 80s, a little warm for soccer. Hopefully it will cool down for the Women’s World Cup Final on July 5. Right now the forecast calls for temperatures in the upper 70s.
Weather Patterns In Flux
After a winter during which a stubborn trough over the northeast brought Boston its snowiest winter ever, May featured a rainy pattern over the southern plains, That lasted about six weeks.
More recently the jet stream receded to the northern states and southern Canada. That zonal pattern, which Decoded Science named Hotzilla, produced record heat in the southeast and southwest.
Now the jet stream is folding again, this time going back to something like the winter pattern. As the fold becomes more pronounced, the warm air will push farther north, reaching north-central Canada. Some of the Women’s World Cup soccer tournament games will be played with temperatures in the 80s on the pitch.
Fire Danger Accompanies Heat
The subsiding air under a high pressure dome such as the one building over the northwest is dry. There will be an increasing probability of forest fires during the heat wave, particularly if afternoon convective activity creates thunderstorms with high bases.
If the atmosphere becomes unstable enough for thunderstorms to form, but the air in the lower layers is dry, the rain may not reach the ground. Lightning unaccompanied by rain is a dangerous fire-starting mechanism.
What’s Ahead? The Battle Of The Pacific Water Temperatures
The general circulation of the atmosphere is everywhere interrelated. Allegedly a butterfly flapping its wings over China can affect the weather in the US a week later. So it isn’t surprising that major departures from average water temperatures can create important changes in the flow.
Decoded Science has repeatedly pointed out that the water in the Gulf of Alaska has been anomalously warm. This is most likely the cause of the recent severe winters in the eastern US., as the warm water tends to produce a ridge of high pressure on the west coast and a corresponding low pressure in the east.
Recently, El Niño Eggplant has strengthened. Its influence on the weather should be to produce a trough in the western US.
The recent changes in pattern reflect the tug-of-war between the two forcing mechanisms. Weather Pattern Yeti which brought the cold, snowy winter to the northeast, represented the supremacy of the Alaskan waters. Weather Pattern Government represented ascendance of Eggplant.
Zonal Flow To Return As The Battle Goes On
Hotzilla was apparently a default pattern during a stalemate between the competing waters, but now, with Westzilla, the Alaskan waters have again taken charge.
With Eggplant strengthening, there is every prospect that this is not the final battle, just a skirmish.