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  • EJSSM 9.2: Southern Great Plains Wildfire Outbreaks - Articles - EJSSM Scientific Discussions Board
    Lindley et al 2014 Abstract Destructive wildfire outbreaks are a preeminent natural hazard on the grass dominated landscape of the southern Great Plains These southern Great Plains wildfire outbreaks SGPWOs are characterized by tens of wildfires that evolve on spatial and temporal scales closely tied to the passage of midlatitude cyclones when dormant herbaceous vegetation is particularly dry and abundant Ten SGPWOs inflicted tragic losses of life and property across eastern New Mexico west Texas and Oklahoma between December 2005 and April 2009 This study reviews the conditions that promoted these dangerous phenomena Texas A M Forest Service records reveal that enhanced seasonal wildfire activity and increased potential for SGPWOs typically occurs during El Niño Southern Oscillation cold phases La Niña especially when preceded by positive growing season rainfall anomalies The antecedent state of predominately fine grassland vegetative fuels associated with SGPWOs is quantified per Energy Release Component ERC fuel model G Average ERC values 50 70th percentile supported the 2005 2009 SGPWOs on the Great Plains of Texas Meteorological composites that quantify mean synoptic patterns during SGPWOs are generated via Rapid Update Cycle analyses and averaged vertical temperature moisture and wind profiles are presented Further analyses of subsynoptic low and midlevel tropospheric temperatures and winds illustrate a tendency for wildfires to occur near 2 m and 850 hPa thermal ridges when overspread by 500 hPa wind maxima The juxtaposition of these atmospheric features appears to be a useful meso α scale predictor of heightened wildfire risks Recognition of the presented seasonal indicators toward a fire prone regime influenced strategic preparations for the historic 2011 Texas wildfires Operational use of composite pattern recognition based forecasts in tactical decision support is demonstrated for the 27 February 2011 firestorm a particularly damaging SGPWO during an unprecedented fire season Average ERC values 75

    Original URL path: http://ejssm.org/forums/index.php?showtopic=95 (2016-05-01)
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  • EJSSM 9.1: Topographic Sensitivity of the Snake River Plain Convergence Zone of Eastern Idaho. Part II: Numerical Simulations - Articles - EJSSM Scientific Discussions Board
    to this topic 1 Roger Edwards Roger Edwards Advanced Member Administrators 161 posts Gender Male Location Norman OK Interests For the purposes of this forum EJSSM Posted 30 January 2014 11 43 PM EJSSM Forum comments are welcome on this article by Andretta 2014 Abstract The Snake River Plain Convergence Zone SPCZ is a mesoscale topographic weather system in the planetary boundary layer that occasionally forms in a post cold frontal environment during the cold season in eastern Idaho Part I of this study investigated persistent and locally heavy topographic snowfall associated with such a zone on 26 November 2005 Multiple snowbands formed in the presence of conditional convective and inertial instabilities In Part II nested grid high resolution numerical simulations of the WRF ARW model are used to investigate the structure and evolution of the SPCZ with two different terrain grid scales In a smoothed topography with a coarsely resolved tributary valley system upstream of the broad parabolic shaped Snake Plain the model does not simulate a lee convergence band and vorticity dipole These features are evident in the observations and control simulation The smoothed run also misses snowfall associated with windward convergence and stable upslope flow in the

    Original URL path: http://ejssm.org/forums/index.php?showtopic=93 (2016-05-01)
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  • EJSSM 8.7: Adjusted Tornado Probabilities - Articles - EJSSM Scientific Discussions Board
    to reply No replies to this topic 1 Roger Edwards Roger Edwards Advanced Member Administrators 161 posts Gender Male Location Norman OK Interests For the purposes of this forum EJSSM Posted 07 December 2013 02 55 AM EJSSM Forum comments are welcome on this article by Widen et al 2013 Abstract Tornado occurrence rates computed from the available reports are biased low relative to the unknown true rates To correct for this low bias the authors demonstrate a method to estimate the annual probability of being struck by a tornado that uses the average report density estimated as a function of distance from nearest city town center The method is demonstrated on Kansas and then applied to 15 other tornado prone states from Nebraska to Tennessee States are ranked according to their adjusted tornado rate and comparisons are made with raw rates published elsewhere The adjusted rates expressed as return periods are 1250 y for four states including Alabama Mississippi Arkansas and Oklahoma The expected annual number of people exposed to tornadoes is highest for Illinois followed by Alabama and Indiana For the four states with the highest tornado rates exposure increases since 1980 are largest for Oklahoma 24 and

    Original URL path: http://ejssm.org/forums/index.php?showtopic=91 (2016-05-01)
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  • EJSSM 8.6: Early History of Using Total Lightning Data at NWS Melbourne, Florida - Articles - EJSSM Scientific Discussions Board
    28 AM EJSSM Forum comments are welcome on this article by Hodanish et al 2013 Abstract This forecaster s note documents the early history 1989 1998 of the use of total lightning data within an operational forecast and warning environment As early as 1989 the Melbourne field office of the National Weather Service had access to real time cloud to ground lightning data In 1993 the Lightning Detection and Ranging system capable of detecting all types of lightning flashes became available In 1996 these two lightning data sets along with radar data were incorporated into the Lightning Imaging Sensor Data Applications Display LISDAD system During a 3 y period 1996 1998 inclusive the LISDAD permitted forecasters to observe relationships of total lightning with a variety of convective events including pulse severe thunderstorms in the warm season cool season tornadic supercells tornadic mini supercells in tropical cyclones and non severe storms Major findings included 1 lightning jumps with warm season pulse severe storms several minutes prior to reported severe weather 2 cool season tornadic supercell storms with very large total flash rates and 3 tornadic mini supercells in tropical cyclones produced only small amounts of lightning however this sporadic activity benefited

    Original URL path: http://ejssm.org/forums/index.php?showtopic=89 (2016-05-01)
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  • EJSSM 8.5: Spatial Distributions of Tornadic Near-Storm Environments by Convective Mode - Articles - EJSSM Scientific Discussions Board
    All tornado reports across the contiguous United States from 2003 2011 were filtered for the maximum damage rating on an hourly grid with 40 km horizontal spacing Convective mode was assigned to each grid hour tornado event via manual examination of full volumetric WSR 88D data and supercell related environmental parameters accompanied each grid hour tornado event from the hourly objective analyses calculated and archived at the Storm Prediction Center Only tornado events associated with right moving supercells RM or quasi linear convective systems QLCS were considered in this work which resulted in a sample of 8837 tornado grid hour events Spatial distributions of supercell related parameters were constructed for the RM and QLCS tornado events Sample sizes were increased by accumulating tornado events within a 120 km neighborhood to each 40 km grid box All neighborhoods with 10 events were retained for percentile rank distributions of the supercell related parameters and then smoothed using a Gaussian kernel with a 120 km influence radius Regional variations in buoyancy and lifting condensation level LCL are apparent RM tornadoes are more common with greater buoyancy and higher LCL heights across the Great Plains compared to the Mississippi Valley region QLCS tornadoes tend

    Original URL path: http://ejssm.org/forums/index.php?showtopic=88 (2016-05-01)
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  • EJSSM 8.4: Synoptic-Scale Precursors, Characteristics and Typing of Nocturnal Mesoscale Convective Complexes in the Great Plains - Articles - EJSSM Scientific Discussions Board
    55 AM EJSSM Forum comments are welcome on this article by Milrad and Kelly 2013 Abstract Mesoscale convective complexes MCCs occur frequently during the warm season in the central U S and can produce flooding rains hail and tornadoes Previous work has found that the synoptic scale environment can greatly affect and be affected by the development and maintenance of MCCs Ninety two MCC cases from 2006 2011 are manually identified using infrared satellite imagery and partitioned into three types upstream trough zonal and ridge using a unique manual synoptic typing based on 500 hPa height patterns Upstream trough cases feature an amplified longwave 500 hPa trough upstream of the MCC genesis region GR while the 500 hPa flow is relatively flat in zonal cases and a strong 500 hPa ridge is present over the Rockies in ridge cases Individual case and storm relative composite analyses of a subset of 28 cases show that of the three types upstream trough cases feature both the strongest quasigeostrophic forcing for ascent and lower tropospheric frontogenesis the latter of which enhances ascent and is associated with a strong southerly low level jet LLJ Zonal and ridge cases feature smaller magnitudes in descending order of all ascent forcing parameters Ridge cases in particular are characterized by weak Q vector convergence but easterly upslope flow likely acts as a compensating ascent mechanism A thermodynamic analysis shows that high θ e air is advected into the GR in all three MCC types and serves as fuel for development and maintenance However while the southerly LLJ advects high θ e air from the Gulf of Mexico in the upstream trough and zonal cases such air is already pooled in the High Plains in the ridge cases and advected into the GR by easterly flow In accordance with

    Original URL path: http://ejssm.org/forums/index.php?showtopic=87 (2016-05-01)
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  • EJSSM 7.4: Russian Tornado Outbreak of 9 June 1984 - Articles - EJSSM Scientific Discussions Board
    loss of life 400 deaths and contained one of two F4 tornadoes on record for that country Also a 1 kg hailstone was observed comparable to the heaviest on world record The synoptic and mesoscale environments are examined and previous studies of this case are revisited to confirm or dispute findings One of the major findings in dispute is the source of the low level moist air mass which is shown to be the Black Sea Due to the paucity of previous studies the authors also surveyed the typical sources of low level moisture for tornado events in the western part of the former Soviet Union Despite the limited information available about the tornadoes for this case at least relative to significant tornado events in the United States the authors present details from eyewitness accounts previous studies and modernized updates from the European Severe Weather Database ESWD Satellite data were studied in order to augment this limited information and to refine event locations and times A map of storm tracks is presented along with reasons why it differs in some instances from previous studies Back to top 2 Valerian Jewtoukoff Valerian Jewtoukoff Newbie Members 1 posts Gender Male Location Boulder CO Posted 02 September 2013 06 00 PM A few years ago I did a numerical simulation of this case study using WRF You can see the synoptic situation at 1200 UTC on the outer domain below surface analysis Here in the simulation the surface dewpoint tongue originating from the Black Sea is consistent with the description of the article So is the fact that the Mediterranean Sea does not seem to be a significant source of moisture for that particular case On the other hand the simulation sees the Caspian Sea as an equal if not bigger source of

    Original URL path: http://ejssm.org/forums/index.php?showtopic=78 (2016-05-01)
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  • Valerian Jewtoukoff - Viewing Profile - EJSSM Scientific Discussions Board
    to access full functionality Overview Profile Feed Likes Friends Topics Posts Valerian Jewtoukoff Member Since 02 Sep 2013 Offline Last Active Sep 03 2013 12 24 AM Find content Community Stats Group Members Active Posts 1 Profile Views 25 687 Member Title Newbie Age Age Unknown Birthday Birthday Unknown Gender Male Location Boulder CO 0 Neutral User Tools Friends Valerian Jewtoukoff hasn t added any friends yet Latest Visitors No

    Original URL path: http://ejssm.org/forums/index.php?showuser=1650 (2016-05-01)
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