[NEW] Download App Weather Forecast

With nearly 4,900 employees in 122 weather forecast offices, 13 river forecast centers, 9 national centers, and other support offices around the country, NWS provides a national infrastructure to gather and process data worldwide.

*Easterly or offshore flow is highlighted with an asterisk when we expect relatively cool east winds in the major Cascade Passes. Easterly flow will often lead to temperature inversions and is a key variable for forecasting precipitation type in the Cascade Passes. Strong easterly flow events can affect terrain on a more regional scale.

Download App Weather Forecast

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The wind forecast represents an elevation range instead of a single elevation slice. The elevation range overlaps with the near and above treeline elevation bands in the avalanche forecast and differs per zone.

Water Equivalent (WE) is the liquid water equivalent of all precipitation types; rain, snow, ice pellets, etc., forecast to the hundredth of an inch at specific locations. To use WE as a proxy for snowfall amounts, start with a snow to water ratio of 10:1 (10 inches of snow = 1 inch WE). Temperatures at or near freezing will generally have a lower ratio (heavy wet snow) and very cold temperatures can have a much higher ratio (dry fluffy snow).

Displays flood and flash flood reports as well as intense rainfall observations for user-selectable time ranges and customizable geographic regions. Includes ability to download reports and associated metadata in csv format. GEFS Probabilities Plots of GEFS probabilistic forecast of precipitation, temperature, and sea-level pressure exceeding various thresholds.

Displays the climatological significance of precipitation forecast by WPC. The climatological significance is represented by Average Recurrence Intervals (ARIs) of precipitation estimates from NOAA Atlas-14 and Atlas2.

Displays Days 1-7 NDFD maximum and minimum temperatures, along with their respective departures from climatology. Prototype Snowband Probability Forecasts An interactive tool that depicts areas of heavy snowfall from individual members of high-resolution short range ensemble forecasts. Weather in Context Prototype Displays forecast information and its climatological context to quickly alert a forecaster when a record or neear-record breaking event is possible. This tool is available for both CONUS and Alaska. Prototype Specialized Excessive Rainfall Maps Interface for specialized WPC Excessive Rainfall Outlook Maps for NWS County Warning Areas and States. 1/3/6/24-hr Changes Change in weather parameters (temperature, dewpoint, surface pressure, etc) over the last 1/3/6/24 hours. Data is provided from the Real-Time Mesoscale Analysis (RTMA) or the Rapid Refresh (RAP).

We are now leveraging our big data smarts to deliver on the promise of IoT. By integrating our hyper-local weather data with Smart Home connected devices we are delievering predictive energy efficiency insight to homeowners and Utility companies.

Snowfall amounts for 12hr (overnight), 24hr, and 48hr timeframes are based on measurements taken at 5am daily. 24hr and 48hr snow totals are cumulative, so whatever fell in the last 24 is built into the 48. Between 5pm and 5am our weather data is automatically updated based on telemetry data from Northwest Avalanche Center and represents our overnight totals.

Weather forecasting is the application of science and technology to predict the conditions of the atmosphere for a given location and time. People have attempted to predict the weather informally for millennia and formally since the 19th century.

Once calculated manually based mainly upon changes in barometric pressure, current weather conditions, and sky conditions or cloud cover, weather forecasting now relies on computer-based models that take many atmospheric factors into account.[1] Human input is still required to pick the best possible model to base the forecast upon, which involves pattern recognition skills, teleconnections, knowledge of model performance, and knowledge of model biases.

The inaccuracy of forecasting is due to the chaotic nature of the atmosphere, the massive computational power required to solve the equations that describe the atmosphere, the land, and the ocean, the error involved in measuring the initial conditions, and an incomplete understanding of atmospheric and related processes. Hence, forecasts become less accurate as the difference between the current time and the time for which the forecast is being made (the range of the forecast) increases. The use of ensembles and model consensus helps narrow the error and provide confidence in the forecast.

There is a vast variety of end uses for weather forecasts. Weather warnings are important because they are used to protect lives and property. Forecasts based on temperature and precipitation are important to agriculture, and therefore to traders within commodity markets. Temperature forecasts are used by utility companies to estimate demand over coming days.

On an everyday basis, many people use weather forecasts to determine what to wear on a given day. Since outdoor activities are severely curtailed by heavy rain, snow and wind chill, forecasts can be used to plan activities around these events, and to plan ahead and survive them.

In 650 BC, the Babylonians predicted the weather from cloud patterns as well as astrology. In about 350 BC, Aristotle described weather patterns in Meteorologica.[3] Later, Theophrastus compiled a book on weather forecasting, called the Book of Signs.[4] Chinese weather prediction lore extends at least as far back as 300 BC,[5] which was also around the same time ancient Indian astronomers developed weather-prediction methods.[6] In New Testament times, Jesus himself referred to deciphering and understanding local weather patterns, by saying, "When evening comes, you say, 'It will be fair weather, for the sky is red', and in the morning, 'Today it will be stormy, for the sky is red and overcast.' You know how to interpret the appearance of the sky, but you cannot interpret the signs of the times."[7]

In 904 AD, Ibn Wahshiyya's Nabatean Agriculture, translated into Arabic from an earlier Aramaic work,[8] discussed the weather forecasting of atmospheric changes and signs from the planetary astral alterations; signs of rain based on observation of the lunar phases; and weather forecasts based on the movement of winds.[9]

Ancient weather forecasting methods usually relied on observed patterns of events, also termed pattern recognition. For example, it was observed that if the sunset was particularly red, the following day often brought fair weather. This experience accumulated over the generations to produce weather lore. However, not all[which?] of these predictions prove reliable, and many of them have since been found not to stand up to rigorous statistical testing.[10]

The two men credited with the birth of forecasting as a science were an officer of the Royal Navy Francis Beaufort and his protg Robert FitzRoy. Both were influential men in British naval and governmental circles, and though ridiculed in the press at the time, their work gained scientific credence, was accepted by the Royal Navy, and formed the basis for all of today's weather forecasting knowledge.[15][16]

Beaufort developed the Wind Force Scale and Weather Notation coding, which he was to use in his journals for the remainder of his life. He also promoted the development of reliable tide tables around British shores, and with his friend William Whewell, expanded weather record-keeping at 200 British coast guard stations.

Robert FitzRoy was appointed in 1854 as chief of a new department within the Board of Trade to deal with the collection of weather data at sea as a service to mariners. This was the forerunner of the modern Meteorological Office.[16] All ship captains were tasked with collating data on the weather and computing it, with the use of tested instruments that were loaned for this purpose.[17]

A storm in October 1859 that caused the loss of the Royal Charter inspired FitzRoy to develop charts to allow predictions to be made, which he called "forecasting the weather", thus coining the term "weather forecast".[17] Fifteen land stations were established to use the telegraph to transmit to him daily reports of weather at set times leading to the first gale warning service. His warning service for shipping was initiated in February 1861, with the use of telegraph communications. The first daily weather forecasts were published in The Times in 1861.[16] In the following year a system was introduced of hoisting storm warning cones at the principal ports when a gale was expected.[18] The "Weather Book" which FitzRoy published in 1863 was far in advance of the scientific opinion of the time.

It was not until the 20th century that advances in the understanding of atmospheric physics led to the foundation of modern numerical weather prediction. In 1922, English scientist Lewis Fry Richardson published "Weather Prediction By Numerical Process",[21] after finding notes and derivations he worked on as an ambulance driver in World War I. He described therein how small terms in the prognostic fluid dynamics equations governing atmospheric flow could be neglected, and a finite differencing scheme in time and space could be devised, to allow numerical prediction solutions to be found.

Richardson envisioned a large auditorium of thousands of people performing the calculations and passing them to others. However, the sheer number of calculations required was too large to be completed without the use of computers, and the size of the grid and time steps led to unrealistic results in deepening systems. It was later found, through numerical analysis, that this was due to numerical instability.[22] The first computerised weather forecast was performed by a team composed of American meteorologists Jule Charney, Philip Duncan Thompson, Larry Gates, and Norwegian meteorologist Ragnar Fjrtoft, applied mathematician John von Neumann, and ENIAC programmer Klara Dan von Neumann.[23][24][25] Practical use of numerical weather prediction began in 1955,[26] spurred by the development of programmable electronic computers. ff782bc1db