The National Hurricane Center has named stationary Subtropical Storm Ana off the Florida coast. At the same time, tornadoes blast through the southern and central plains day after day. And if that isn’t enough rough weather, the Rockies will get two feet of snow as low pressure refuses to budge.
Decoded Science is naming this Weather Pattern Government — it’s long-lasting and doesn’t move much.
The Atmosphere Is Interconnected And The Butterflies Are Swarming
We live on a round earth. If it was flat, we could say goodbye to the weather once it passed. But on a round planet, what goes around comes around. Ripples in the atmosphere have effects both upstream and downstream.
The famous butterfly effect says that a butterfly flapping its wings over China can cause a tropical disturbance in the Atlantic a week later. We’re not blaming Ana on a butterfly, but we can connect Ana to the severe weather in the central plains the last few days, and to the snowstorm brewing in the Rockies and high plains.
The long-lived nature of Weather Event Government is a result of the breakdown of the normal west to east movement of weather systems. If the weather stops in the Rockies, it stops on the east coast — and vice versa. Currently we have a persistent tornado threat in the middle of the US and an almost stationary storm in the Atlantic.
Subtropical Storm Ana
Last night the National Weather Service named Subtropical Storm Ana off the coast of the southeastern US. At 2 o’clock this afternoon (Friday), tropical storm warnings were issued for part of the Carolina coast. The storm is over warm Gulf Stream waters, and so is deriving most of its strength from the process of evaporation of sea water followed by condensation in the atmosphere. This process releases heat and drives the production to kinetic energy (energy of motion) which we call wind.
At this time of year, the water along the coastal region is still cold, and it cools the air atop it. The cool air near the coast next to the warm air over the Gulf Stream allows a second energy-conversion process to take place: cool air and warm air side-by-side can reconfigure with warm air on top of cool — a lower potential energy state. The potential energy lost becomes kinetic energy.
Thus Ana has characteristics of both an extra-tropical storm fueled by contrasting temperatures, and a tropical storm supported by the release of latent heat of condensation. Hence this is considered a subtropical storm. It qualifies as tropical for the purpose of counting tropical storms and is given the first name on the list for this year.
Whom Will Ana Affect?
Currently Ana is less than 200 miles south-southeast of the North Carolina coast. It is stationary as of 2 p.m., but is expected to begin moving toward the coast tonight, albeit at a snail’s crawl of about 4 miles per hour. This motion would bring it ashore on Sunday.
The winds are currently 45 miles per hour, and though they may increase a little bit, Ana is not expected to become a hurricane.
The primary danger from Ana will be powerful waves and rip currents along the shore. Swimmers should wait until seas subside before venturing into the water.
The western side of Weather Pattern Government consists of a trough over the intermountain west. A trough is where the jet stream dips southward (in the northern hemisphere) and is normally accompanied by cold air at the surface.
Meanwhile warm and humid air has been streaming northward from the Gulf of Mexico into the plains and the rest of the southern and eastern US. As the warm air at the surface meets the colder flow aloft, violent weather can occur. The process is like the extratropical feature of Ana, but the cold over warm air has even greater potential energy than warm next to cold. The release of energy is often explosive, resulting in powerful thunderstorms and tornadoes.
Weather Pattern Government’s tornado phase began on Wednesday, with a large outbreak in the plains of tornadoes up to EF3 intensity (winds up to 165 miles per hour). There was a lot of damage and one death.
Thursday saw fewer tornadoes, but the threat continues daily through the weekend, with the highest probability of damaging storms moving into the Midwest on Sunday.
Government’s Snowy Side
The warm air from the Gulf of Mexico will penetrate far enough westward to provide sufficient moisture for a May snowstorm in the Rockies. The trough is providing the cold air. Up to two feet is expected in the mountains of Colorado and Wyoming Saturday and Sunday, with snow spreading into the high plains on Sunday.
How Long Will Government Keep Bothering the US?
Recent weather patterns have been remarkably reluctant to change. Just ask a New Englander about close encounters of a snowy kind. However, the pattern of ridge in the west and trough in the east that persisted for the entire winter has now switched to trough in the west and ridge in the east. Severe Weather Outbreak Jon a couple of weeks ago was symptomatic of the type of weather that this pattern breeds.
The same pattern of western trough and eastern ridge is now Weather Pattern Government. Some longer range forecasts indicate that it could stay with us right through the summer. This forecast is partly based on the currently strengthening El Niño Eggplant. El Niños tend to be correlated with a trough in the west and a ridge in the east, though normally a southern branch of the jet stream inhibits tropical formation.
Be Ready For Whatever Comes
The present pattern suggests that the eastern US could be in for a long, hot summer. But there really is no consensus on this summer’s forecast. Government can always change its mind.
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