 Image: Credit The Washington Post Discussion: 2018 has been another active weather year featuring more extreme droughts, wildfires, hurricanes, extreme flooding events, and tornadoes. As 2018 comes to a close, the topic of discussion is how many cities broke their record for total precipitation this calendar year. Many are wondering if the wet weather will continue and for just how long.  Image: NOAA GOES GeoColor satellite image taken on December 15, 2018 Hurricane Florence dumped 24.06” of rain in Wilmington, North Carolina which contributed to its three-digit total precipitation record of 101.45” for 2018. More cities that have already set records include Wilmington, NC at 101.45”, Asheville, NC at 75.00”, Washington, D.C. at 64.78”, Baltimore, MD at 70.05”, Green Bay, WI at 38.68”, and Mason City, IA at 49.98”. Several cities still have a shot of setting a new record before the ringing in the New Year. Pittsburgh, PA currently sits at 56.98”and its record is 57.38”, Raleigh, NC sits at 58.54” and its record is 59.10”, and Jackson, TN sits at 73.49”and its record is 74.76”. All of these stats were collected from xmACIS2on December 28, 2018. So just what factors contributed to all of the rain in 2018? The Washington Postexplained that, “The extreme rainfall in the Mid-Atlantic has stemmed from a weather pattern unleashing a parade of storms through the region since May. Except for brief pauses in the first half of Julyand this month, it has seldom relented. The jet stream, which is the high-altitude air current along which storms track, has persistently directed moisture-packed storms through the region”. The Weather Channelfurther explained that an upper-level weather pattern has been another driving factor for wetter weather east of the Rockies. Furthermore, the federal government’s Fourth National Climate Assessment, released in November 2018, stated that “Extreme precipitation, one of the controlling factors in flood statistics, is observed to have generally increased and is projected to continue to do so across the United States in a warming atmosphere.” Images: WMO estimated ENSO probabilities for December 2018-February 2019, The Weather Channel Precipitation Forecast adapted from NOAA’s January-March 2019 Precipitation Outlook, NOAA’s January-March 2019 Temperature Outlook According to the World Meteorological Organization (WMO), we are going into 2019 with a 75-80% chance for a weak El Niñoby February 2019. The National Oceanic & Atmospheric Administration (NOAA) is also predicting a weak El Niño in its 2018-19 Winter Outlook. An El Niño is the warm phase of the El Niño Southern Oscillation (ENSO). If ENSO verifies, three-quarters of the U.S. will most likely experience warmer than average, as opposed to colder than average, winter temperatures. Additionally, wet weather will continue to dominate the southern states. So, keep your umbrella handy.
To learn about more historical weather events, click here. © 2018 Meteorologist Amber Liggett
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DISCUSSION: December through February is considered as the official meteorological winter season, so it is of no surprise that snow is the predominant precipitation type with winter weather systems. On this date back in 2010, most of the mid-Atlantic and New England states were dealing with the brunt of a rather powerful winter storm. Heavy blowing and drifting snow affected much of New Jersey, New York, and points north of that as the system rapidly made its way off shore and away from the U.S. mainland. The synoptic setup for this storm system was centered on the rapid deepening of a low pressure system that originally formed on the lee side of the Rocky Mountain range which quickly tracked eastward across the central Plains and southeast U.S. By late evening on the 26th, an upper-level jet streak maximum of near 150 kts (175 mph) was observed over northwestern Florida while significant pressure height falls were observed over the northeast. Moisture from the warm waters of the Gulf of Mexico was dragged northward along the poleward flank of the trough and observed radiosonde (weather balloon) data showed that the atmosphere through 600 hPa was at near-full saturation. This high amount of low-to-mid-level moisture, coupled with the already present favorable frontogenesis dynamics, set the stage for a significant snowfall event while the system tracked north and east through the mid-Atlantic and New England states.
The result was significant snowfall totals ranging from 20-30” with higher totals primarily along the New York City-New Jersey-Hudson Valley corridor. Heavy convective snow bands trained over the same areas for many consecutive hours, compounding on the snow already on the ground. In addition, a very tight pressure gradient was focused over much of the mid-Atlantic as the low pressure system advanced and upper-level winds sustained winds of 25 to 40 mph with higher gusts at the surface. which led to hazardous conditions for travel and infrastructure. Storms of this nature can occur during this time of year so it is always important to be vigilant to developing winter weather systems and alert to the latest forecasts from local weather forecast offices and the Weather Prediction Center. To learn more about other past historic weather events from around the world, click here! © 2018 Meteorologist Brian Matilla  DISCUSSION: Over the last two centuries, there is little to no doubt that atmospheric science observational and forecasting capabilities have come quite a long way. One of the premiere technologies which is associated with how far atmospheric science over the past 200 + years is the invention of the world-famous Doppler Radar technology which is based upon the fundamental principle known as the Doppler Effect. The so-called “Doppler Effect” which is what the modern Doppler Radar observational platform is based upon was invented by Christian Doppler. This was a historic discovery during the earlier part of the 19th century since this was a discovery which would go on to forever change the course of history.
Attached below is an excerpt which is from a corresponding Physics Today article: “Born on 29 November 1803 in Salzburg, Austria, physicist Christian Doppler proposed the phenomenon that enables astronomers to determine the velocity of distant objects. He studied mathematics at the Vienna Polytechnic Institute and math, mechanics, and astronomy at the University of Vienna. Doppler had shaky health throughout his life, and he had trouble securing a stable professorship. Nonetheless he produced several important papers, none more influential than “On the colored light of the double stars and certain other stars of the heavens” in 1842. He theorized that the colors of two stars orbiting each other would appear to change slightly, due to one star moving away from the observer and the other moving closer. More generally, Doppler proposed that the apparent frequency of light or sound waves emanating from an object changes depending on the object’s motion toward or away from the observer. Scientists in many fields, particularly astronomy, depend on the Doppler effect. Stars and galaxies moving away from Earth shift toward the red part of the color spectrum (red-shifted), while astronomical objects moving toward Earth are blue-shifted. Scientists analyzing the distance to and motion of stars and galaxies have determined that the universe is expanding at an ever-faster rate.” Upon discovering the Doppler Effect concept which is described in the excerpt attached above, this transformed the way in which mankind was able to interpret how sound and velocity works in the context of time and space in order to anticipate the movement of hydrometeors. Therefore, this is the concept which instigated the development of the modernized Doppler Radar which uses the Doppler Effect to produce velocity data to project and predict the speed and directional movement of different types of objects from a given distance. To learn more about other past historic weather history topics from around the world, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz |
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