This usually signifies a bit of an active pattern, which explains why we can expect rain chances in the future. The jet stream, as depicted by the arrows, is pushing the storm from the west to the east.
As the pattern progresses, the jet stream pushes that feature from the west to the east. Now and then, we can get storms here to move in from the east, but it takes a big perturbation in the jet stream to do so.
From years of watching TV weathermen I know that our weather (in particular the jet stream) moves from west to east. The main thing to remember is that the weather moves from west to east only in the part of the world where you happen to be, namely the temperate latitudes.
In both tropical and polar regions the prevailing winds move in the opposite direction, from east to west. Hot air at the equator expands, rises, and (in the Northern Hemisphere) moves north.
By the time it gets to about 25-30 degrees north latitude it cools off, sinks, and heads south again. The Coriolis effect deflects it to the right (west) and we wind up with the polar easterlies.
In our region of relatively moderate temperatures, general circulation of the atmosphere is driven by the extremes to the north and south. At the southern boundary of our zone the air is driven down by tropical convection and thereafter heads north.
The upshot: the prevailing winds are out of the west, just like on the TV weather maps. The grammarian microchip in your incontrovertibly mighty brain was clearly malfunctioning when you wrote, “You try explaining convection currents and the Coriolis effect in 600 words or fewer.” What you meant to say was “600 words or fewer.” I suggest you pull a Newt here and blame this embarrassing solecism on snarky liberal/Commie McGovern in the Straight Dope proofreading division.
Cecil messed up!” but rather, “How is it that I have been mistaken all these years?” I quote from the American Heritage Dictionary, third edition: Less is sometimes used with plural nouns in the expressions no less than (as in No less than 30 of his colleagues signed the letter) and or less (as in Give your reasons in 25 words or fewer).” In June 1989, Pacific Hurricane Come traveled across North America and became Atlantic Tropical Storm Allison.
In July 1985, Hurricane Bob crossed Florida from west to east, tracked north along the Florida coast, made landfall on the southern coast of South Carolina as a tropical storm, and finally traveled north through Western Virginia. However, if you live closer to the equator, toward the tropics, the weather patterns tend to move west and come out of the east.
If you live in the United States, you can usually expect winds and weather patterns out of the west. However, if you live closer to the equator, you can expect winds and weather patterns to come of the East.
Weather generally in Southern Hemisphere moves from the west to the east. Approaching weather fronts are often visible from the ground, but are not always as well-defined as this. Cold fronts generally move from west to east, while warm fronts move pole ward.
When the density contrast between the air masses is diminished, for instance after flowing out over a uniformly warm ocean, the front can degenerate into a line which separates regions of differing wind velocity known as a shoreline. The second letter describes the thermal characteristic of its source region: T for tropical, P for polar, A for arctic or Antarctic, M for monsoon, E for equatorial, and S for superior air (dry air formed by significant upward motion in the atmosphere).
Different air masses which affect North America, as well as other continents, tend to be separated by frontal boundaries. Surface weather analyses have special symbols which show frontal systems, cloud cover, precipitation, or other important information.
A waterfront is weaker, bringing smaller changes in temperature and moisture, as well as limited rainfall. A cold front is located along the warm side of a tightly packed temperature gradient.
On weather maps, the surface position of the cold front is marked by a blue line with triangles pointing in the direction of cold air travel and it is placed at the leading edge of the cooler air mass. The lifting motion often creates a narrow line of showers and thunderstorms if enough humidity is present.
The concept of colder, dense air “wedging” under the less dense warmer air is too simplistic , as the upward motion is really part of a maintenance process for geographic balance on the rotating Earth in response to frontogenesis. Warm fronts are at the leading edge of a homogeneous warm air mass, which is located on the equator ward edge of the gradient in isotherms, and lie within broader troughs of low pressure than cold fronts.
If the warm air mass is unstable, thunderstorms may be embedded among the strati form clouds ahead of the front, and after frontal passage thundershowers may continue. On weather maps, the surface location of a warm front is marked with a red line of semicircles pointing in the direction of travel.
A wide variety of weather can be found along an occluded front, with thunderstorms possible, but usually their passage is associated with a drying of the air mass. Precipitations and clouds are associated with the trowel, the projection on the Earth's surface of the tongue of warm air aloft formed during the occlusion process of the depression.
Occluded fronts are indicated on a weather map by a purple line with alternating half-circles and triangles pointing in direction of travel. They tend to remain essentially in the same area for extended periods of time, usually moving in waves.
Stationary fronts are marked on weather maps with alternating red half-circles and blue spikes pointing in opposite directions, indicating no significant movement. When stationary fronts become smaller in scale, degenerating to a narrow zone where wind direction changes significantly over a relatively short distance, they become known as shorelines.
A similar phenomenon to a weather front is the dry line, which is the boundary between air masses with significant moisture differences. When the westerlies increase on the north side of surface highs, areas of lowered pressure will form downwind of north-south oriented mountain chains, leading to the formation of a lee trough.
In the vicinity of the reversal aloft, severe weather is possible, especially when a triple point is formed with a cold front. When moisture pools along the boundary during the warm season, it can be the focus of diurnal thunderstorms.
The dry line may occur anywhere on earth in regions intermediate between desert areas and warm seas. The southern plains west of the Mississippi River in the United States are a particularly favored location.
Dry lines are one of the few surface fronts where the pips indicated do not necessarily reflect the direction of motion. A shelf cloud such as this one can be a sign that a squall is imminentOrganized areas of thunderstorm activity not only reinforce pre-existing frontal zones, but can outrun cold fronts in a pattern where the upper level jet splits apart into two streams, with the resultant Message Convective System (MCS) forming at the point of the upper level split in the wind pattern running southeast into the warm sector parallel to low-level thickness lines.
When the convection is strong and linear or curved, the MCS is called a squall line, with the feature placed at the leading edge of the significant wind shift and pressure rise. Even weaker and less organized areas of thunderstorms lead to locally cooler air and higher pressures, and outflow boundaries exist ahead of this type of activity, which can act as loci for additional thunderstorm activity later in the day.
If outflow boundaries or squall lines form over arid regions, a haboob may result. Squall lines are depicted on News surface analyses as an alternating pattern of two red dots and a dash labelled SQL Nor SQUALL LINE, while outflow boundaries are depicted as troughs with a label of OUTFLOW BOUNDARY.
Convective precipitation (showers, thundershowers, and related unstable weather) is caused by air being lifted and condensing into clouds by the movement of the cold front or cold occlusion under a mass of warmer, moist air. If the temperature differences of the two air masses involved are large and the turbulence is extreme because of wind shear and the presence of a strong jet stream, roll clouds and tornadoes may occur.
In the warm season, lee troughs, breezes, outflow boundaries and occlusions can lead to convection if enough moisture is available. It may sometimes occur in advance of warm fronts moving northward to the east of mountainous terrain.
Although, not all fronts produce precipitation or even clouds because moisture must be present in the air mass which is being lifted. Frontal zones can be slowed by geographic features like mountains and large bodies of warm water.
During a day the West takes a lot of sunshine (hot air) but the east cools down (since it is under darkness) On the eastern side, though, air becomes cooler since around midnight sunshine has ended nearly 4, 5, or 6 hours ago.
Low pressure spins counterclockwise, causing weather systems to move from west to east in the Northern Hemisphere. It is important to note that precipitation generally moves from west to east in the Northern Hemisphere.
Another MAJOR factor that drives weather systems in the U.S. is that the Jet Steam moves from West to East across North America. This is largely due to a variety of factors including the sun's heat primarily targeting the equator, the speed of the Earth's spin and more.
This is because tropical cyclones develop over warm sea waters and follow trade winds that blow westward. Prevailing weather patterns refer to the movement of entire air masses, not just the winds they produce in their rotations.
Prevailing weather is the result of expansive convection currents formed by the temperature differences on the surface of the earth as latitude increases. As air heats up due to the direct rays of the sun and higher temperature at the equator, it rises and moves up into the atmosphere where it cools again and begins to flow high aloft, at the same time turning north or south depending on its origin.
During all this activity spin of the earth results in the Coriolis effect which deflects the winds towards the right in the Northern Hemisphere and to the left in the south.