![](\"http:\/\/weather.umd.edu\/wordpress\/wp-content\/uploads\/2017\/01\/Halverson-Illustrates-Depth-of-Rainfall-from-Flash-Flood.jpg\")
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Scanning the various weather maps, he quickly analyzes and makes sense of the ensemble forecasts and satellite\u00a0imagery\u00a0that lies before him. The confluence of shaded Doppler shapes and contoured isobars is skillfully synthesized into a forecast. However, Capital Weather Gang forecaster Jeff Halverson knew he was missing something on July 30. That was the day rampant flooding wreaked havoc on Ellicott City.<\/p>\n
The topographic bowl-like shape of the city has made it historically vulnerable to accumulating a massive volume of rainfall. Since 1950, seven destructive flood events have occurred in Ellicott City. \u201cWater gets in there like a sluice,\u201d said Halverson. \u201cFlashfloods are as much about landscape, topography\u2014as they are about rain. It\u2019s truly multidisciplinary.\u201d This flooding event like its ancestors caught forecasters off-guard in its sudden severity. As Halverson points out in one of his Washington Post articles, \u201cFlash flood warning essentially becomes a now-casting exercise.\u201d<\/p>\n
\u201cAll that time I wish I had caught it,\u201d said Halverson, who had consulted a variety of synoptic maps that morning to try to give better lead-time on the storm. \u201cI thought perhaps I hadn\u2019t looked at the water vapor imagery\u2014but no it was still dry.\u201d Eventually around 3 p.m., the Capital Weather Gang was able to observe echo training in the radar that indicated the potential for rapid development of a quasi-stationary, mesoscale thunderstorm. But the massive destruction that ensued from the concentrated 8.2 inches of rainfall still was unable to be foreseen by even the\u00a0highest resolution of models.<\/p>\n
Jeff Halverson came to speak to faculty and students at University of Maryland to discuss other severe summer weather events that happened in the D.C. area during the preceding summer. A common theme amongst these convective super-cell days was the shear uncertainty surrounding their progression.<\/p>\n
\u201cWhat we need to do is get better at conveying uncertainty,\u201d said Halverson, \u201cThe models are great but we have to their limitations.\u201d The trend of \u2018fake news\u2019 proliferating on social media has been a hot-button issue for political news outlets, but weather forecasters have had to deal with the spreading of such rumors since the dawn of social media. \u201cSomeone will put on Facebook, \u2018Snowmaggedon\u2019 at 10 days out,\u201d said Halverson, \u201cSo then we have to look at the ensembles too early on and do damage control way too early on.\u201d<\/p>\n
Halverson thinks packaging the ensembles in a way the public can understand will be crucial towards enhancing the publics\u2019 understanding of severe weather events and their level of imminence. He discussed the importance of the National Weather Service\u2019s social science research into people\u2019s perceptions of warnings versus watches that are issued. \u201cPeople aren\u2019t taking for example, tornado watches, at face value,\u201d said Halverson, \u201cThey are fatigued.\u201d<\/p>\n
As we move into the more snow-laden months of January and February, it will be interesting to see if weather forecasters will be able to come to a consensus with the public with what is certain and what is uncertain. Even if snow does not factor in, the predictions for any precipitation event may be put increasingly to the test.<\/p>\n
\u201cHeavy rain events may be increasing because of global warming,\u201d said Halverson, \u201cThe line between climate and weather may be fuzzier than we once thought.\u201d![](\"http:\/\/weather.umd.edu\/wordpress\/wp-content\/uploads\/2017\/01\/Jeff-3.jpg\")
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Scanning the various weather maps, he quickly analyzes and makes sense of the ensemble forecasts and satellite\u00a0imagery\u00a0that lies before him. The confluence of shaded Doppler shapes and contoured isobars is skillfully synthesized into a forecast. However, Capital Weather Gang forecaster…
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