MÉXICO – Masa de aire frío ocasionará un descenso en las temperaturas de los estados al norte de México / Why the origin of cold air is key to how extreme temperatures get in winter

El SMN prevé que el frente frío núm. 8 se extienda sobre el noreste del país con un descenso en las temperaturas y generará condiciones ideales para lluvias fuertes

Este día el frente frío Núm. 8 se extenderá sobre el norte y noreste del país, de acuerdo con la previsión del Servicio Meteorológico Nacional. Esto, en interacción con entrada de aire cálido y húmedo del Golfo de México, con un canal de baja presión y con la corriente en chorro subtropical, ocasionará lluvias fuertes en Nuevo León y Tamaulipas.

Además, la masa de aire frío que impulsa al frente ocasionará descenso de temperatura en región norte del territorio nacional, así como bancos de niebla en sus zonas serranas. También se pronostica un evento de “Norte” con rachas fuertes a muy fuertes de viento y oleaje de 1 a 3 metros en la costa norte de Tamaulipas, principalmente en la noche de este viernes y madrugada del sábado.

México registrará temperaturas máximas de hasta 40º C en Nuevo León, San Luis Potosí, Tamaulipas, Michoacán, Guerrero, Campeche, Yucatán y Quintana Roo, y de hasta 35° C en Sinaloa, Nayarit, Jalisco, Colima, Veracruz, Tabasco, Oaxaca y Chiapas. En contraste, las mínimas podrían ser de hasta -10º C en zonas montañosas de Baja California, Chihuahua y Durango, y de hasta -5° C en Sonora.

Pronóstico por regiones:

Valle de México: Cielo despejado y ambiente fresco por la mañana. Por la tarde, ambiente templado a cálido y nubes dispersas. Probabilidad de lluvias aisladas en el suroeste del Estado de México y sin lluvia en la Ciudad de México. Viento de componente norte de 5 a 15 km/h con rachas de 35 km/h.

En la Ciudad de México se pronostica temperatura mínima de 8 a 10 °C y una máxima de 25 a 27 °C. Para la capital del Estado de México, temperatura mínima de 3 a 5 °C y máxima de 21 a 23 °C.

Península de Baja California: Cielo parcialmente nublado, ambiente matutino fresco, siendo frío a muy frío en zonas serranas de Baja California y gélido con heladas sobre sierras del norte de dicha entidad. Por la tarde, cielo despejado, ambiente templado a cálido y sin lluvia.

Pacífico Norte: Cielo parcialmente nublado durante el día y sin lluvia. Ambiente matutino fresco, siendo frío en zonas serranas y muy frío con heladas en sierras de Sonora. Durante la tarde, ambiente cálido.

Pacífico Centro: Cielo parcialmente nublado por la mañana y medio nublado por la tarde con lluvias aisladas en Jalisco, Colima y Michoacán. Sin lluvia en Nayarit. Ambiente fresco por la mañana, y frío con posibles heladas en zonas serranas de Michoacán. Por la tarde ambiente cálido, y caluroso en zonas de Michoacán.

Pacífico Sur: Cielo medio nublado durante la mañana con ambiente fresco y bancos de niebla en zonas serranas, siendo frío y con posibles heladas en sierras de Oaxaca. Cielo nublado por la tarde con chubascos en el sur de Guerrero, Oaxaca y Chiapas, acompañados de descargas eléctricas. Ambiente vespertino cálido, y caluroso en zonas del noroeste de Guerrero.

Golfo de México: Cielo medio nublado a nublado con probabilidad de lluvias puntuales muy fuertes en Tamaulipas, chubascos en zonas del norte de Veracruz y sin lluvias en Tabasco. Ambiente fresco por la mañana, siendo templado en costas y frío con probables heladas en zonas altas de Veracruz. Por la tarde, ambiente cálido.

Península de Yucatán: Cielo con nubosidad dispersa por la mañana y nublado por la tarde, con lluvias aisladas en el noreste de Yucatán y norte de Quintana Roo y sin lluvia en Campeche. Ambiente templado por la mañana y caluroso por la tarde.

Mesa del Norte: Cielo medio nublado por la mañana con ambiente fresco y posibles heladas, siendo frío en zonas serranas de Zacatecas y Aguascalientes, además de gélido con heladas en sierras de Chihuahua y Durango. Lluvias puntuales muy fuertes en Nuevo León y chubascos en el norte de Coahuila y San Luis Potosí. Sin lluvia en el resto de la región. Por la tarde, ambiente cálido, además de caluroso en zonas de Nuevo León y San Luis Potosí.

Mesa Central: Cielo parcialmente nublado por la mañana. Ambiente fresco al amanecer, y frío con posibles heladas en sierras de Guanajuato, Querétaro, Hidalgo, Tlaxcala y Puebla. Por la tarde, cielo medio nublado con probabilidad de lluvias aisladas en Querétaro, Hidalgo y Puebla. INFOBAE

11 de Noviembre de 2022

Why the origin of cold air is key to how extreme temperatures get in winter

How cold you feel, or not, during the winter depends a great deal on where the air surrounding you originated from.

Year round, there are several primary source regions of air that determine the playing field for temperatures in the United States.

These are the Pacific Ocean, Gulf of Mexico, Maritime, Polar region and Siberian. Below we discuss these source regions from warmest to coldest and how they relate to the weather we feel during the winter months.

Air coming from the Gulf of Mexico

Most often, record warmth during the winter is produced by a flow of air from the Gulf of Mexico.

A Gulf of Mexico air mass is often quite moist. While there either is, or soon will be, rain and fog occurring, there may also be brief episodes of sunshine. The presence of a Gulf air mass to the south can help to fuel moisture to a snowstorm to the north.

Because a gulf air mass is usually only present just ahead of a major storm producing strong southerly winds during the winter, the peak of the warmth and record highs may ignore the time of day.

High temperatures may occur at night in the winter. For example, temperatures may reach the 60s F in New York City in January near midnight as a storm moves up the Atlantic coast.

Air originating from the Pacific Ocean

When a west to east jet stream pattern is present, storms tend to move across the country in an average of three days. Under these conditions, air from the Pacific Ocean dominates the nation.

This fast flow not only limits the amount of warm, Gulf of Mexico air but also tends to limit the amount of cold air from the north.

This air is mild to begin with as it reaches the West coast and may gain some warmth after flowing downhill from the Rockies and then later the Appalachians.

This type of air mass can bring some record high temperatures, but often it only brings above-average temperatures. For example, highs may be in the 40s to near 50 in Chicago during the middle of January, instead of the 31 F average high.

Pacific air is neither very moist nor very dry east of the Rockies but can be quite moist farther west. If this air mass moves over snowcover or following prolonged cold weather, fog may form, especially over the interior valleys of the West.

When Pacific air is around, the humidity level in your home may be comfortable with fewer problems related to dry skin.

Occasionally, during the winter and spring, the routine west to northwest flow of air gets disrupted in the eastern quarter of the nation. When this happens, the flow of air may originate from the Atlantic Ocean and sometimes from the Atlantic waters surrounding the southeastern provinces of Canada.

When a wedge of this air extends southward along the eastern slopes of the Appalachians, a setup for a prolonged period of freezing rain and drizzle may occur as far south as the Carolinas and Georgia.

This air is cooler than that of the Pacific in the winter.

In a few cases, the air can be dry but most often it is moist and strewn with clouds and drizzle.

For example, temperatures may hover in the 30s in Boston day and night during late February and March when this air mass is in play. The normal high in Boston in late February is 41.

Air plunging from Polar (Arctic) origins

When a north to northwest flow of cold air results in below-average temperatures over large tracts of land, a polar air mass is most often the culprit. Occasionally, this air mass can produce record low temperatures and may be tied to a displacement of the Polar Vortex.

This air usually originates from northern Canada and often contains air from north of the Arctic Circle. Sometimes air from the North Pacific may settle over northern Canada and transform by means of extended darkness into a polar air mass. However, most often during the early stages, air from this source region hovers over the middle of the continent away from unfrozen waters of the Pacific or the Atlantic.

Often a polar air mass is accompanied by gusty winds, which may drive AccuWeather RealFeel® temperatures down to frigid and dangerous levels. This air mass often produces heavy lake-effect snow early in the winter and may help fuel blizzards and nor’easters.

A polar air mass can cause frozen pipes and bring freezes to agricultural areas of the Deep South from California to Texas and Florida. High temperatures below zero can occur across the northern tier states. Temperatures may not get above freezing in Seattle and Atlanta when this air is around.

Within a couple of days of its presence, a polar air mass can bring very low humidity levels to homes and businesses. It may be difficult to keep hands from drying out and lips from becoming chapped. This persistent cold, very dry air may also increase the risk of the spread of influenza.

When and where Polar air persists, skiing is often at its best.

The most intense cold waves stem from Siberian (Arctic) roots

By far, the coldest of the cold air masses of the winter originates from Siberia. Technically speaking, this air mass is also Arctic in origin, but from a secondary sense.

Not only is this air frigid to start with, since it began over frozen ground and darkness over north-central and northeastern Russia, but it may also continue to get even colder as it spends more time while moving across the Arctic, before plunging southward over North America.

Siberian air can drop deep into North America when the jet stream extends from northern Asia, over the top of the globe and southward over Canada and the United States. In this case, the Polar Vortex has become displaced well to the south.

While visits from a Siberian air mass may only occur a couple of times a winter and may not occur at all during certain winters, record low temperatures often accompany its presence.

Heat pump systems may struggle to keep up, while tremendous amounts of energy are expended in general. Layered clothing is an absolute must, and exposed skin can freeze in a matter of minutes across the northern tier states.

Temperatures may struggle to get above zero across portions of the interior Northwest, the central Rockies, the Ohio Valley and mid-Atlantic when a Siberian air mass is in the neighborhood. By Alex Sosnowski, Accu Weather senior meteorologist