SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 PM CST Thu Feb 11 2021 Valid 121200Z - 131200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few weak thunderstorms are possible across parts of the eastern Gulf and south Atlantic coast region today through tonight, and near northern California and southern Oregon coastal areas by late tonight. ...Discussion... Models indicate little movement to a deep, elongated mid-level low, centered to the north of the North Dakota/Minnesota border area, through this period. And arctic surface high pressure will remain entrenched across much of North America, to the east of the Rockies. It does appear that the shallow leading edge of this air mass will stall across parts of the western through north central Gulf of Mexico, and the northern Florida/southern Georgia vicinity into the western Atlantic, as mid-level subtropical ridging begins to build once again across much of the Southeast. This is forecast to occur downstream of a short wave trough turning eastward into the western Gulf of Mexico, after digging through Mexico. A significant trailing impulse is forecast to dig near/southwest of the southern Sierra Nevada, and across the lower Colorado Valley into northwestern Mexico by 12Z Saturday, as a more vigorous mid-level perturbation digs toward the Oregon/northern California coast, downstream of building large-scale mid-level ridging across the eastern mid-latitude Pacific. Beneath their respective mid-level cold pools, thermodynamic profiles may become weakly unstable and conducive to convection capable of producing lightning along their tracks, into the Pacific coast and across parts of the Southwest. The trailing impulse, with its colder air aloft, has been accompanied by considerable thunderstorm activity across the mid-latitude Pacific, and appears to provide the most certain risk for thunderstorm activity during this period, which could impact northern California and southern Oregon coastal areas toward 12Z Saturday. Meanwhile, east of the Rockies, destabilization supportive of thunderstorm development appears in the process of becoming increasingly focused along and south of the surface frontal zone, and confined to offshore areas of the Gulf of Mexico and western Atlantic. This may generally remain the case through much of the period. However, a zone of strengthening low-level warm advection developing across the central through northeastern Gulf of Mexico may provide a focus for increasing thunderstorm development impacting northeastern Gulf coastal areas toward 12Z Saturday. ..Kerr.. 02/12/2021
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