Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0211 AM CDT Thu Apr 06 2017 Valid 081200Z - 091200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe storms appears currently appears negligible across the U.S. for Saturday through Saturday night. ...Synopsis... Models indicate that large-scale upper ridging into troughing, from the Mississippi Valley through the western Atlantic, will begin to lose amplitude during this period, with upper flow becoming more progressive and zonal across much of the nation. This is expected to occur as the remnants of a once strong mid-latitude Pacific jet continue to migrate inland across the Pacific coast through the Rockies. Within this regime, a pair of speed maxima, somewhat in phase, are forecast to progress through the southern Great Basin and Rockies by late Saturday night. Large-scale forcing for ascent and cooling aloft associated with these features probably will be accompanied by sufficient destabilization for scattered thunderstorm activity across the Great Basin and Rockies. Downstream, surface cyclogenesis may commence to the lee of the Colorado Rockies, accompanied by strengthening southerly low-level flow across the central and southern Plains. However, it appears that low-level moisture return beneath warm and capping elevated mixed layer air will remain fairly modest through this period. The leading edge of this moisture return may contribute to scattered thunderstorm development by late Saturday night, based within a developing zone of enhanced lower/mid tropospheric warm advection across the mid Missouri Valley. This may be displaced well to the north of the warmer and more strongly capping elevated mixed layer air and steeper mid-level lapse rates, where CAPE will be too weak to support an appreciable risk for large hail. At this time, the risk for severe storms seems too limited and/or uncertain for even 5 percent severe probabilities. ..Kerr.. 04/06/2017Read more
from SPC Forecast Products http://ift.tt/GAMjPN
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