A Preliminary Investigation of Supercell Longevity
Matthew J. Bunkers, NOAA/NWSFO, Rapid City, SD; and J. S. Johnson, J. M. Grzywacz, L. J. Czepyha, and B. A. Klimowski
One of the components of the supercell definition includes persistence, namely, that the storm's circulation persists for at least 30-45 minutes. In some cases, a supercell may persist in a quasi-steady manner for several hours, and in extreme cases, the lifetime of a supercell may extend well beyond 4-5 hours. These long-lived supercells can produce significant severe weather along the majority of their paths, and on occasion, they generate a devastating combination of large hail and damaging winds.
Since these long-lived supercells are rare, they present a forecasting challenge. However, a few studies have addressed forecast issues related to supercell longevity. Some of the environmental parameters used to investigate supercell longevity have included storm-relative helicity (SRH), lifted condensation level (LCL) height, midtropospheric dryness, and the synoptic weather regime. No solid relationships have emerged from these studies, which leaves unsolved the problem of why a few supercells persist for many hours.
In the current study, we present findings from a preliminary investigation of supercells that persisted in a quasi-steady manner for greater than four hours. Specific attention is paid to local sounding parameters and the large-scale environment. For comparison purposes, we also examine shorter-lived supercells to determine if the environmental signals are the same or different from their longer-lived counterparts. The main finding of this preliminary work is that the large-scale environment plays a more significant role in determining supercell longevity than what can be inferred from individual soundings.
Extended Abstract (168K)
Session 16, Tornado and Severe Storms Environments
Friday, 16 August 2002, 8:00 AM-9:59 AM
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"Mfano wa utafiti wa kwanza wa ""Supercell Longevity"" ni utafiti uliofanywa na Matthew J. Bunkers, NOAA, na J. S. Johnson, J. M. Grzyb, na L. J. Chepychuk, na B. J. S. Johnson, na J. S. Johnson, na J. S. Chepychuk, na B. J. Chepychuk, na J. S. Chepychuk, na J. S. Chepychuk, na J. S. Chepichuk." "Kilimo cha ""supercell"" ni kipengele cha mfumo wa mzunguko wa mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi ya mawimbi." Katika baadhi ya kesi, supercell inaweza kudumu kwa njia ya karibu-imara kwa masaa kadhaa, na katika kesi kali, maisha ya supercell inaweza kupanua zaidi ya masaa 4-5. "Seli hizo zenye maisha marefu zinaweza kutokeza hali mbaya ya hewa katika sehemu nyingi za njia zao, na nyakati nyingine, hutokeza mchanganyiko wenye kuangamiza wa mvua kubwa ya mawe na upepo wenye kuharibu.""" Kwa kuwa chembe hizo zenye uhai mrefu ni nadra sana, ni vigumu kutabiri hali hiyo. Hata hivyo, masomo machache yamechunguza masuala ya utabiri yanayohusiana na urefu wa maisha ya supercell. Baadhi ya vigezo vya mazingira kutumika kuchunguza supercell longevity ni pamoja na dhoruba-relative helicity (SRH), kuinuliwa condensation ngazi (LCL), urefu, midtropospheric ukame, na hali ya hewa synoptic. Hakuna uhusiano thabiti uliojitokeza kutokana na masomo haya, ambayo inaacha bila kutatua tatizo la kwa nini supercells chache kudumu kwa masaa mengi. Katika utafiti huu, tunawasilisha matokeo kutoka kwa uchunguzi wa awali wa supercells ambayo ilidumu kwa njia ya karibu ya kudumu kwa zaidi ya masaa manne. Uangalifu maalum hutolewa kwa vigezo vya sauti za mitaa na mazingira ya kiwango kikubwa. Kwa madhumuni ya kulinganisha, pia tunachunguza supercells za muda mfupi ili kuamua kama ishara za mazingira ni sawa au tofauti na wenzao wa muda mrefu. Ugunduzi wa msingi wa kazi hii ya awali ni kwamba mazingira ya kiwango kikubwa hucheza jukumu muhimu zaidi katika kuamua urefu wa maisha ya supercell kuliko kile kinachoweza kuelezwa kutoka kwa sauti za mtu binafsi. "Kutoka kwa ""Session 16: Tornadoes and Severe Storms: Environment Friday, 16 August 2002: 8:00 AM-9:59 AM"" na ""Session 16: Tornadoes and Severe Storms: Environment Friday, 16 August 2002: 8:00 AM-9:59 AM"" na ""Session 16: Tornadoes and Severe Storms: Environment Friday, 16 August 2002: 8:00 AM-9:59 AM"" ni makala ya kwanza ya mkutano wa AMS."