Editing Hail (section)

== Accumulations ==

[[File:Sydneyhailstorm.jpg|thumb|240px|Accumulated hail in [[Sydney]], Australia (April 2015)]]

Narrow zones where hail accumulates on the ground in association with thunderstorm activity are known as hail streaks or hail swaths,<ref>{{cite web|url=http://www.nssl.noaa.gov/primer/hail/hail_climatology.html|title=Hail Climatology| publisher= National Severe Storms Laboratory, National Oceanic and Atmospheric Administration |date=2006-10-09|access-date=2009-08-29|archive-url= https://web.archive.org/web/20090613020028/http://www.nssl.noaa.gov/primer/hail/hail_climatology.html|archive-date=2009-06-13}}</ref> which can be detectable by satellite after the storms pass by.<ref>{{cite web|url=http://www-roc.inria.fr/clime/lynx/peters-factsheet.pdf|title=Crop Hail Damage Assessment| first= Albert J. |last= Peters| website= inria.fr| publisher= Institut National De Recherche En Informatique Et En Automatique|date=2003-03-03 |access-date=2009-08-28|archive-url=https://web.archive.org/web/20110721003010/http://www-roc.inria.fr/clime/lynx/peters-factsheet.pdf |archive-date=2011-07-21}}</ref> Hailstorms normally last from a few minutes up to 15 minutes in duration.<ref name="Nolanhail"/> Accumulating hail storms can blanket the ground with over {{cvt|2|in|cm}} of hail, cause thousands to lose power, and bring down many trees. Flash flooding and mudslides within areas of steep terrain can be a concern with accumulating hail.<ref>{{cite news| url= http://www.thesudburystar.com/ArticleDisplay.aspx?e=1612615|archive-url= https://web.archive.org/web/20090616051630/http://www.thesudburystar.com/ArticleDisplay.aspx?e=1612615|archive-date=2009-06-16| title= Sudbury lashed by freak storm; hail pummels downtown core| first= Harold |last= Carmichael|date=2009-06-15|access-date=2009-08-28|newspaper=Sudbury Star |publisher= Sun Media}}</ref>

Depths of up to {{cvt|18|in|m|abbr=on}} have been reported. A landscape covered in accumulated hail generally resembles one covered in accumulated snow and any significant accumulation of hail has the same restrictive effects as snow accumulation, albeit over a smaller area, on transport and infrastructure.<ref>{{cite journal| first1= Thomas W.| last1= Schlatter| first2= Nolan |last2= Doesken|date=September 2010|title=Deep Hail: Tracking an Elusive Phenomenon|url=http://www.weatherwise.org/Archives/Back%20Issues/2010/September%202010/weather-deep-hail-full.html |journal= Weatherwise| publisher= Taylor & Francis|volume=63|issn=0043-1672|access-date=2015-08-09|number=5| pages= 35–41| doi= 10.1080/00431672.2010.503841| bibcode= 2010Weawi..63e..35S| s2cid= 191481064}} {{Dead link|date=May 2017|fix-attempted=yes}}</ref> Accumulated hail can also cause flooding by blocking drains, and hail can be carried in the floodwater, turning into a snow-like slush which is deposited at lower elevations.

On somewhat rare occasions, a thunderstorm can become stationary or nearly so while prolifically producing hail and significant depths of accumulation do occur; this tends to happen in mountainous areas, such as the July 29, 2010 case<ref>{{Cite news|url = http://www.coloradodaily.com/rant-rave/ci_15630529#axzz1NnYBPl6D|title = Boulder County cleans up Nederland-area roadways after foot-deep hailstorm|last = Rubino|first = Joe|date = 2010-07-29|work = Colorado Daily|access-date = 2014-12-20|archive-url = https://web.archive.org/web/20150610200951/http://www.coloradodaily.com/rant-rave/ci_15630529#axzz1NnYBPl6D|archive-date = 2015-06-10}}</ref> of a foot of hail accumulation in [[Boulder County]], Colorado. On June 5, 2015, hail up to four feet deep fell on one city block in [[Denver, Colorado]]. The hailstones, described as between the size of bumble bees and ping pong balls, were accompanied by rain and high winds. The hail fell in only the one area, leaving the surrounding area untouched. It fell for one and a half hours between 10:00 pm and 11:30&nbsp;pm. A meteorologist for the National Weather Service in Boulder said, "It's a very interesting phenomenon. We saw the storm stall. It produced copious amounts of hail in one small area. It's a meteorological thing."  Tractors used to clear the area filled more than 30 dump truck loads of hail.<ref name="The Denver Post">{{cite news | url=http://www.denverpost.com/news/ci_28258514/one-denver-block-buried-under-up-four-feet | title=One Denver block buried under up to 4 feet of hail | newspaper=The Denver Post | date=5 June 2015 | access-date=7 June 2015 | last= Mitchell| first= Kirk | url-status=live | archive-url= https://web.archive.org/web/20150606235643/http://www.denverpost.com/news/ci_28258514/one-denver-block-buried-under-up-four-feet | archive-date=6 June 2015 }}</ref>

[[File:Hand holding hail in a strawberry patch.jpg|thumb|Hand holding hail in a strawberry patch]]

Research focused on four individual days that accumulated more than {{convert|5.9|in|cm}} of hail in 30 minutes on the Colorado front range has shown that these events share similar patterns in observed synoptic weather, radar, and lightning characteristics,<ref>{{Cite journal|first1=E.|last1=Kalina|display-authors=etal|date=26 October 2015|title=Colorado Plowable Hailstorms: Synoptic Weather, Radar and Lightning Characteristics|url=https://zenodo.org/record/1234621|journal=Weather and Forecasting|volume=31|issue=2|page=663|doi=10.1175/WAF-D-15-0037.1|bibcode=2016WtFor..31..663K|doi-access=free|access-date=28 June 2019|archive-date=18 February 2021|archive-url=https://web.archive.org/web/20210218212236/https://zenodo.org/record/1234621|url-status=live}}</ref> suggesting the possibility of predicting these events prior to their occurrence. A fundamental problem in continuing research in this area is that, unlike hail diameter, hail depth is not commonly reported. The lack of data leaves researchers and forecasters in the dark when trying to verify operational methods. A cooperative effort between the University of Colorado and the National Weather Service is in progress. The joint project's goal is to enlist the help of the general public to develop a database of hail accumulation depths.<ref>{{cite web| url= http://clouds.colorado.edu/deephail|title=Deep Hail Project – Report your hail depth!!|publisher=[[University of Colorado Boulder]]| archive-url=https://web.archive.org/web/20160708085322/http://clouds.colorado.edu/deephail|archive-date=2016-07-08|access-date=2016-06-14}}</ref>