The High Resolution Rapid-Refresh (HRRR) model is produced hourly (up to 24 times a day). Many are produced as much as two, four or eight times a day. Computer models are produced not just once a day. The NAM and GFS do not match up as well.Ĭonsistency is another factor. The greater the match, the better that model may be at matching the future state of weather.Īs of now, the GEM and ECMWF models start with environmental conditions that are a better match to conditions on the ground at the time of their production. For many weather forecasters, a key indicator for whether a weather model may make a good prediction is how well the match is between that model’s simulation of current conditions and reality. At their initial point, they are also simulating current conditions. They simulate how the weather may be in the future. Numerical models for weather are a simulation. Initialization is the starting time for any model when it is produced. In synoptic meteorology and forecasting its initialization, initialization, initialization. In real estate it’s location, location, location. Here’s what goes into choosing which models may make more sense for any given time. The projected prolonging of wet and icy conditions reduces the snow totals in Southeast Michigan to 1 to 4 inches. So, greater amounts of snow that are 6 to 12 inches are possible in The Thumb and the Saginaw Valley according to these models. In fact, it snows sooner and longer not just north of 8 Mile Road but north of M-59 and into the Saginaw Valley. This means the full transition to snow occurs later rather than sooner in Southeast Michigan. This results in a longer period of transition from rain to snow Thursday with a greater chance of freezing rain and sleet. It has the same drop in temperatures at the surface where people, cars, trucks and houses are but temperatures aloft (inside clouds) either fluctuate near or are above freezing. These two models have the cold front forming and remaining farther west and north. Two other computer models, the North American Mesoscale (NAM) model and the Global Forecast System (GFS) model have the same cold front but take its origin (called frontogenesis) and trajectory in a very different way that results in drastically different snowy outcome (or not so snowy). By the end of Thursday evening, these models predict 3 to 8 inches of snow with much of it falling south of 8 Mile Road. The rapidly sinking mercury and persistently falling snowflakes combine to provide a significant amount of snow for most of Southeast Michigan from northern Oakland and Macomb Counties south through Detroit and Ann Arbor to the Michigan-Ohio Border. Snow lasts through much of the afternoon with this model as temperatures plummet. As it does, steady rain showers quickly change over to steady snow showers with not much sleet or ice. Two computer models, the Global Environmental Multiscale System (GEM) model and the European Centre for Medium Range Weather Forecast (ECMWF) model have a cold front developing and racing through the Motor City region Thursday morning. Here is a breakdown of this week’s computer models and decision to go with one versus another or combining elements of different models to help Southeast Michiganders get prepared not scared: A Tale of 2 Sets of Models Related: Wind, flood advisories, then winter storm watch in Metro Detroit: Significant snow coming Thursday Meteorologists take their education and experience to decipher which computer models are most relevant when figuring out the time snow will make its appearance the day after tomorrow. It is an eternity when it comes to numerical models and their digital prognostications. Computer models are a significant forecast for analyzing any prediction.Īs of Tuesday evening, snow is over a day and a half away. That’s when it’s up to the Local4Casters to provide on a top notch weather forecast. Also, the possibility of ice accumulations is one-tenth of an inch or less with snow and sleet accumulations less than half an inch.DETROIT – The ears of Detroiters perk up when snow is in the future. that will change to sleet and snow late evening into the overnight hours. Near I-94, expect freezing rain after 4 p.m. In addition, one-tenth of an inch of ice or less could coat surfaces, the agency said.įreezing rain and sleet are expected between I-69 and I-94. The biggest impact will be around the I-696 and I-96 corridors, which is expected to receive the greatest amount of snowfall. The agency issued a winter weather advisory for southeast Michigan until 4 a.m. Some 1-3 inches of snow is forecast for metro Detroit, according to the National Weather Service in White Lake. Besides coping with rush hour, motorists can expect slippery, icy roads for their afternoon commute.
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