The National Weather Service (NWS) said flood warnings in some parts of Dallas were in effect until at least Wednesday morning, with risks of thunderstorms and brief periods of heavy rainfall possible for Tuesday and Wednesday. Rescue personnel wade through floodwaters after heavy flooding in the Dallas metro area submerged roads and entire neighborhoods, in Dallas County, Texas, U.S., August 22, 2022, in this still image taken from video. Rainfall over a 24-hour period ending Monday night exceeded forecasts, with one area in east Dallas experiencing more than 15 inches (38cm) of rain, according to Dallas water utility's floodway operations. The body of a 60-year-old woman, who has not been identified, was recovered from her car after floodwaters receded Monday afternoon in an area of east Dallas, according to Clay Jenkins, the top elected official in Dallas County. Alternatively, a site lower than model orography (Site B) may have forecast wind speeds slightly over-estimated and hence these are reduced slightly in the post-processing.(Reuters) - Flooding and heavy rains hit the Dallas, Texas area on Monday, leaving at least one person dead after their vehicle was swept away by rising water, authorities said. In these situations winds may be intensified slightly. If a site is higher in reality than the model orography (Site A), then the wind speed may be under-estimated by the model. This has implications for a range of forecast parameters (including rainfall, temperature, wind speed and visibility), meaning that orographic adjustments need making depending on a specific site elevation. Model orography is usually defined as the average elevation for each grid square.
Orographic adjustment of local weather forecastsįigure 2 illustrates taking account of differences between model orography and reality. This method is often referred to as "intelligent grid point selection", whereby grid points with most similar characteristics to a specific location are given greater weighting in the final forecast. This means that forecast temperature and wind speed at Site B would be quite different depending on whether the wind is on- or off-shore. For coastal sites, the weighting between the 'land' and 'sea' values varies with the direction of the wind. Local forecasts for coastal sites can be more difficult to define than inland sites. Site A is likely to be computed from the nearest two land points as it is exactly half way between the two. Coastal adjustment of local weather forecastsįigure 1 illustrates how a local (site-specific) forecast can be computed from a range of surrounding model grid points.
Two of the methods are briefly outlined below.
#Local weather series#
The extracted model data for each location goes through a series of post-processing procedures to make the forecast more specific to a particular location, hence the name "site-specific" forecasts. The site-specific forecasts themselves have to be extracted from horizontal gridded fields for a range of forecast parameters, including rainfall, temperature and wind speed. This means that at any time, the most recent model data is available.
They use a "best data" approach, whereby the most recent highest resolution model is used at any given forecast lead time.įorecasts are updated hourly to include the most recent nowcast and any recently updated forecast models. Local forecasts (or site-specific forecasts) are regularly updated and make use of a range of weather models run on the Met Office supercomputer.
UK forecast How local weather forecasts are created You will then be given the option to choose from a range of locations near you. Simply enter your town, city, region, first half of a UK postcode or mountain area into the search box. Use the Met Office weather forecast page to find your local seven-day weather forecast. This page provides links to Met Office local weather forecasts along with details on how they are created.
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