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SPC Feb 12, 2025 Day 4-8 Severe Weather Outlook

5 months 3 weeks ago

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CST Wed Feb 12 2025 Valid 151200Z - 201200Z ...DISCUSSION... ...Day 4/Saturday... Model guidance continues to forecast a strong upper-level trough moving through the southern Plains and into the Southeast. Some modest slowing of the trough has been noted, however. The trough will promote the deepening of the surface low in the ArkLaTex vicinity during the afternoon with further deepening expected into the evening as it generally progresses north-northeastward within the Mid-South/Ohio Valley. Moisture return will have begun Friday evening and will continue Saturday. Guidance shows a consistent signal for mid 60s F dewpoints extending into much of Louisiana/Mississippi, and Alabama. Upper 60s F dewpoints are possible closer to the Gulf Coast. Very strong wind fields are anticipated throughout the troposphere. Shear will be strong and, despite more modest mid-level lapse rates, buoyancy will be more than adequate for severe storms. The current expectation is for warm advection precipitation to be ongoing early in the period and for it not to make much, if any, southward progress until the late afternoon. A Pacific front in East Texas/Sabine Valley into the ArkLaTex may be the initial zone for stronger convective development. By the late afternoon onward, the cold front will begin to surge south and east. The low-level jet should remain strong into the afternoon and then increase to 50-70 kts during the evening. As the cold front surges, shear vectors will acquire a greater cross-boundary component. This strongly forced line will be capable of scattered to widespread damaging winds along with the threat for embedded circulations/QLCS tornadoes. One of the main questions that remain will be the degree of the tornado threat, which would increase with any discrete activity ahead of the cold front. Given the weak capping and strong forcing, pre-frontal discrete storms are plausible. The ECMWF shows some hint of this from central Louisiana into adjacent Mississippi. The eastern and northern extent of the greatest severe threat are also in question, but the intense low-level jet could produce severe-caliber gusts even with relatively shallow convection. The overall pattern, along with signals in both deterministic and ML guidance, suggest 30% severe probabilities are warranted for Saturday. ...Day 5/Sunday... The strongly forced line will continue into portions of the Carolinas and Mid-Atlantic. Strong wind-fields will remain in place. The main question will be the degree of destabilization that can occur. The current forecast guidance suggests the line may move through these areas late morning/early afternoon. Uncertainty in the thermodynamic environment precludes severe probabilities at this time, but areas of eastern Virginia into parts of the eastern Carolinas will continue to be monitored. ...Day 6/Monday Onward... With cold air moving into much of the CONUS east of the Divide, severe potential appears low during the remainder of the period. Some moisture return could occur in coastal Texas next Tuesday, but a cold front is expected to quickly push back offshore. Read more