![\"Patrick](\"http:\/\/www.image-upload.net\/files\/2921\/PatCreek.jpg\")
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Experimental Warning Program Blog Entry: 4\/23\/08<\/p>\n
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Between 3 and 5 pm today, Angelyn Kolodziej and I ran through an archived event, using PAR data as the basis for mock severe weather warnings. <\/span>We both noted the utility of rapid-update radar data in catching the onset of low-level mesocyclogenesis. <\/span>It was also enlightening to interrogate storms as a team viewing the same data. <\/span>This forced us to state our reasoning aloud, and resulted in a verbal exchange of conceptual models and warning philosophies. <\/span>I felt that we arrived at more accurate and timely warning decisions than either one of us could have accomplished alone. <\/span>When the 1.5 hour simulation concluded, it was fairly obvious from my five plus years of NWS warning experience that we had issued more warnings over a small area than we would have issued using WSR-88D data. <\/span>Angelyn and I suspect the PAR scan strategy captured certain features that tipped the scales toward issuing a warning, and which may have fallen between traditional WSR-88D volume scans.<\/span><\/p>\n Shortly after 5 pm, we had intended to begin probabilistic warning operations, but paused to observe the supercell that came up to the south and east of Norman. <\/span>All eyes were fixed on the live updating PAR data and the SADS. <\/span>Oklahoma City television crews delivered video of a low hanging wall cloud with rising scud, but weak rotation. <\/span>The circulation never quite tightened up, and the storm had trouble maintaining supercell structure for any length of time.<\/span><\/p>\n The Norman storm was at the southeast extend of an extensive cluster of multicell thunderstorms that spread northward across Oklahoma through mid evening. Between 6 and 8pm, <\/span>Mike Magsig worked this activity from one of the probabilistic warning desks. <\/span>Meanwhile, at the second desk, I shifted my attention to an ongoing high-end severe weather event in north Texas. <\/span>A long-lived, high-precipitation supercell moved eastward into the Fort Worth WSR-88D domain. <\/span>This storm expanded in size, forming a classic bow echo anchored by a broad mesocyclone at the northern end. <\/span>An exceptionally intense rear inflow jet presented 90 to 100 knot ground-relative velocities at times. <\/span>Out ahead of this complex, another large supercell formed and approached the southern sides of Fort Worth. <\/span>This storm quickly took on the appearance of a classic, tornadic supercell. <\/span>Eventually, the bow echo overtook the tornadic storm in the vicinity of the KFWS radar. <\/span>With the advantage of near range sampling at low levels, the radar detected several small-scale vortices along the leading edge of the storm outflow.<\/span><\/p>\n The variety of storm modes and storm motions in the two operational domains fostered a productive discussion between myself, Mike, and Greg Stumpf. <\/span>Mike had difficulty drawing probabilistic grids for the transient multicell hail storms taking place in Oklahoma. <\/span>One potential approach may be to outline a broad area of low probability severe hail, and then embed shorter duration, higher probability warnings for particular cores that show some persistence or organization. <\/span>Whatever the warning philosophy, the actual grid preparation could benefit from some type of automated routine or suite of routines for defining a threat area. <\/span>For instance, a tool that outlines the 55 dbZ contour with attention to echo overhang might be a good starting point for drawing a hail threat area.<\/span><\/p>\n The Texas storms brought up a host of even more complex issues, including personal tornado warning thresholds expressed as a percent chance of tornado, detailed spatial resolution of tornado threats (e.g. high probability surrounding a TVS and lower probabilities along the RFD gust front), and how to emulate longer lead-time information in a probabilistic way (e.g. drawing a 2-hour probability swath to mimic a special weather statement that WFO Fort Worth issued to raise awareness in the metropolitan area). <\/span><\/span><\/p>\n Much of our conversation stemmed from large scale design issues, using examples from the evening’s data to explore probabilistic warning strategies. In general, we concluded that in designing a probabilistic warning system, researchers may begin with an idealized philosophy, and then incorporate forecaster preferences that have been gained through experience. <\/span>Many of these preferences will hopefully become evident throughout the course of the EWP spring activities.<\/span><\/p>\n Patrick Burke (WFO OUN Forecaster, EWP Weekly Coordinator-in-Training)<\/em><\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" Experimental Warning Program Blog Entry: 4\/23\/08 Between 3 and 5 pm today, Angelyn Kolodziej and I ran through an archived event, using PAR data as the basis for mock severe… <\/p>\n