Administrators NorthGeorgiaWX Posted July 23 Administrators Posted July 23 Day 4-8 Outlook Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0346 AM CDT Tue Jul 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... Upper ridging will spread across parts of the Plains and eastern states, while the subtropical high develops westward over the southern tier of the U.S. during the Day 4-8/Fri-Tue period. This will suppress severe thunderstorm potential for much of the CONUS. The exception will be a potentially more active period for parts of the northern Plains into the Upper Midwest due to a series of upper shortwave troughs migrating across the Canadian Prairies and parts of the northern Plains/Upper Midwest through the forecast period. Surface high pressure over the Great Lakes and periodic surface low development over the northern High Plains will maintain a baroclinic zone over the Upper Midwest. As a result, southerly low-level flow will keep a seasonally moist airmass in place across the eastern Dakotas and Mid-MO Valley east to the Mid/Upper MS Valley. Some severe thunderstorm potential could develop around Day 4 Fri as the first upper shortwave trough moves across the Canadian Prairies. However, stronger vertical shear and large scale ascent will be focused north of the international border. Another weaker, but further south shortwave trough will traverse the northern Plains vicinity on Day 6/Sun before a somewhat stronger wave migrates through westerly flow toward Day 8/Tue. While various forecast guidance generally depicts this more progressive northern stream pattern, details in timing of each wave, as well as differences in the strength of the central U.S. upper ridge/subtropical high vary greatly. As a result, confidence is too low to include 15 percent probabilities at this time. Read more View the full article Quote
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