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Forecast area will remain at the southern edge of the westerlies through the upcoming weak, which will allow for several frontal systems to impact the area. Additionally, temperatures this week will be mainly at or just above normal with the exception of Monday and Friday, where temperatures will be a bit warmer ahead of approaching cold fronts. There is uncertainty Monday with both temperatures and the magnitude/coverage of convection in the afternoon/evening hours as a pre-frontal trough triggers the majority of the convection. Model time-height cross sections indicate an abundance of mid and high level moisture (clouds) which would be a limiting factor for highs as well as how much the airmass destabilizes. For the time, have held off on extending the heat advisory into Monday, but the potential remains. SPC has maintained a Slight Risk for severe thunderstorms across the entire area Monday. The main threat being damaging winds associated with multicell clusters or line segments. Deep-layer shear does deepen through the day. The question is the amount of daytime heating/destabilization (extent of cloud cover) and whether the forcing with the pre-frontal trough will be deep enough to trigger convection. Mid-level lapse rates, as has been the case for most events this warm season, are around or just shy of 6C. So while not a slam dunk event (rarely are here), the ingredients are there for severe weather. In addition, the southward progression of the boundary will be slow, raising possible concerns for training of thunderstorms. WPC has the area under a Marginal Risk for Excessive Rainfall. High pressure builds in behind the cold front for Tue and Wed. A warm front is forecast to move through the area Wednesday night into Thursday, followed by a cold frontal passage Friday. Chances of showers and thunderstorms are in the forecast during this time.
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