SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0930 AM CST Thu Nov 19 2020 Valid 191630Z - 201200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of general thunder is negligible through tonight. ...Northwest... While the probability of thunder appears to be less than 10 percent, three areas of nonzero probability appear to exist. The first is near the ND/SD border area with a corridor of elevated convection in association with a shortwave impulse moving across the northern Great Plains. While a couple flashes occurred in southeast MT earlier this morning, effective inflow layers should become increasingly elevated with eastern extent, thereby decreasing potential for charge separation. A lightning flash or two is also possible across parts of western to southern MT during the late afternoon but predominately 20s surface dew points will limit appreciable surface-based buoyancy. Finally, low-topped showers will likely persist across coastal portions of WA and northwest OR. Mid-level warm advection is underway in the wake of shortwave trough passage earlier this morning, although this process should be temporarily curtailed as a weak mid-level impulse over the northeast Pacific approaches this evening. The weak forcing for ascent coupled with generally increasingly marginal thermodynamic profiles should limit thunder potential. ..Grams.. 11/19/2020
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