Administrators NorthGeorgiaWX Posted July 27 Administrators Posted July 27 SPC 1630Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1126 AM CDT Sat Jul 27 2024 Valid 271630Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA AND NORTHERN MINNESOTA... ...SUMMARY... Scattered severe thunderstorms capable of producing both large hail and damaging winds appear possible across portions of the northern Plains vicinity, including parts of the Dakotas and northern Minnesota, mainly this afternoon and evening. ...Northern Plains/Upper Midwest... A closed upper low centered over northern Saskatchewan/Manitoba this morning will move slowly eastward towards Hudson Bay through the period. Across the northern Plains, a low-amplitude shortwave trough over the Dakotas is forecast to advance northeastward into eastern ND and northern MN through this evening. This feature should aid in renewed convective development across this area later today. A cold front/surface trough arcs southward from the primary surface low in northern Saskatchewan/Manitoba into parts of eastern MT. Low-level moisture remains more limited with westward extent across the northern High Plains, with greater surface dewpoints (mid/upper 60s to low 70s) present farther east in the Dakotas and northern MN. Scattered thunderstorms should develop this afternoon along an instability/moisture gradient across parts of northern MN as the previously mentioned shortwave trough overspreads this region. Ongoing weak/elevated thunderstorms in northeast SD may also persist and gradually strengthen as they move northeastward into greater instability this afternoon. Around 1500-2500 J/kg of MLCAPE is forecast to be in place in a narrow corridor across northern MN and vicinity by late afternoon, as daytime heating of the moist low-level airmass continues to occur, and as modestly steepened mid-level lapse rates overspread the warm sector. Around 35-50 kt of southwesterly mid-level flow associated with the shortwave trough should aid in similar values of deep-layer shear, which will promote organized severe thunderstorm potential, including supercells. Large hail and severe/damaging winds will be a threat with any robust convection that can remain at least semi-discrete. Enough low-level shear should also be present to support some threat for a tornado or two. This activity will spread northeastward towards the international border through the evening, before eventually moving into Canada. Additional convection may also develop along the weak cold front/surface trough in the western/central Dakotas vicinity late this afternoon and early evening. This potential still appears somewhat more uncertain in the wake of the lead shortwave trough. Even so, any thunderstorm clusters that can be sustained will be capable of producing both large hail and damaging winds, given a favorable thermodynamic environment and sufficient deep-layer shear. This convection should eventually weaken by late evening into the eastern Dakotas with the loss of daytime heating. ...Northern Great Basin into the Central Rockies/High Plains... Multiple mid-level vorticity maxima will move east-northeastward across the northern Great Basin and central Rockies/High Plains today. Scattered to numerous thunderstorms should develop across these regions this afternoon and evening while spreading generally eastward. Even though low-level moisture will tend to remain fairly limited, steepened low/mid-level lapse rates and modestly enhanced mid-level flow should support an isolated threat for strong to severe wind gusts with the more robust cores. Convection may have a tendency to form into one or more loosely organized clusters through this evening, especially across the central High Plains of eastern WY/northeast CO into the NE Panhandle vicinity. Still, with generally modest deep-layer shear, confidence in a more concentrated corridor of severe winds remains too low to include a Slight Risk across the central High Plains with this update. ..Gleason/Mosier.. 07/27/2024 Read more View the full article Quote
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