SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0729 AM CDT Wed Oct 14 2020 Valid 141300Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A SMALL PORTION OF THE UPPER MISSISSIPPI VALLEY AREA... ...SUMMARY... A strong/severe wind gust or two may occur this afternoon over portions of the upper Mississippi Valley region. ...Synopsis... Gradual amplification of the upper flow field over the U.S. is expected today, as short-wave troughing initially crossing the northern Intermountain Region digs southeastward into the central states. By the end of the period, an expanding/broad belt of cyclonic flow -- centered over the central third of the U.S. -- is expected to cover nearly the entire country. At the surface, a southeastward-surging cold front is expected to evolve, in conjunction with the digging upper system. During the afternoon, the front should extend from a low over the upper Mississippi Valley area southwestward into the central Plains. By the end of the period, as the low shifts northeastward into eastern Canada, the cold front will likely have advanced to a position extending from the lower Great Lakes to Texas. ...Upper Mississippi Valley area... As the surface cold front and parent upper system advance eastward across the upper Mississippi Valley area this afternoon, modest pre-frontal moistening/destabilization is expected -- with CAPE generally on the order of 150 to 350 J/kg anticipated. This -- in conjunction with strong ascent near the surface front -- should be sufficient to support a couple of stronger low-topped updrafts. Aided by moderately strong/quasi-unidirectional westerly flow increasing with height through the lower troposphere, a stronger/damaging gust or two cannot be ruled out as convection shifts quickly eastward. The greatest risk is expected during the late afternoon, near peak heating, with convection then weakening with the onset of diurnal stabilization. ..Goss.. 10/14/2020
There’s more click here.