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Despite record warmth, winter is coming
It is a fair bet that we would get near universal agreement that the weekend of November 15-16 was incredibly nice, even the slightly cooler Sunday that followed a truly remarkable Saturday. Both Milwaukee and Madison set all-time record high temperatures for November 15 at 69 and 68 degrees Fahrenheit, respectively.
Apart from the fact that each city recorded highs that were at least 20 degrees lower the very next day (46 for Milwaukee and 48 for Madison), the weekend was also noteworthy for another meteorological reason: At least for Madison, November 15 is the date on which the probability of precipitation falling as snow first reaches 50%. This means that, from here on out, if precipitation is in the forecast, there is at least an even chance that it will fall as snow. Only 10 days later comes the average date of our first 1-inch snowfall. Continue reading
What is lake effect snow?
Lake effect snow forms when cold air passes over the warmer water of a lake. As cold air moves over water, the lower layers are warmed and moistened by the lake below. This makes the air mass unstable. Evaporation increases the moisture content of the air mass, which is then precipitated in the form of snow on the land downwind.
Maximum heat and moisture exchanges occur when the air is cold and the temperature difference between the air and the water is large. This condition tends to occur during early winter; this is when the most lake effect snow is produced. A long path across warm water by the air mass results in heavy precipitation over the land. Continue reading
Does lightning travel from the sky downward or ground upward?
Lightning is a huge electrical discharge that results from vigorous motions that occur in thunderstorms.
Lightning can travel from cloud to cloud, within the same cloud, or between the cloud and ground. In-cloud lightning discharges are more common than cloud-to-ground discharges and are not as hazardous. Cloud-to-ground is the best known type of lightning and it poses the greatest risk. Continue reading
Category: Meteorology, Phenomena, Severe Weather
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Does the federal shutdown impact weather forecasting?
Weather forecasts provided by the government will continue during the shutdown. The National Weather Service (NWS) and other National Oceanic and Atmospheric Administration (NOAA) agencies provide essential services; therefore, most NWS federal forecasters are considered emergency employees and are required to work without pay during the shutdown.
While NWS will continue their life-saving essential work, some weather and climate data feeds and public-facing services will have limited or no access to researchers and the public. According to a NWS webpage announcement, “Due to the government shutdown, all public National Weather Service activities, including tours and other outreach activities, have been canceled or postponed until further notice. We apologize for any inconvenience. The NWS will continue to provide critical forecast, watch, and warning information to protect life and property throughout the shutdown.” The National Hurricane Center (NHC) will also continue to provide hurricane updates and forecasts. There are a few “non-essential” fields in NOAA that are not operating during the shutdown, including some active research. Continue reading
Category: Meteorology, Weather Dangers
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Why is fog more common in the early morning?
Fog can occur any time of day throughout the year. In southern Wisconsin, fog is most frequent in the morning, between about 6 and 8 a.m.
Fog formation is the result of two primary processes. First, the air is cooled to the dew point, and the relative humidity reaches 100%. When the air temperature is the same as the dew point temperature, condensation of the atmospheric water vapor occurs forming fog droplets. Another method of fog formation requires water to evaporate from the surface into the air, increasing the relative humidity until condensation occurs. Continue reading
