Strong / Damaging Wind Threat Monday PM

Low pressure taking shape over the Southern Mississippi River Valley today – and poised to bring a destructive day of severe weather to the Southern and Southeastern United States – will lift quickly northward over the next 24 hours, crossing through the Central Great Lakes on Monday and lifting into Canada Monday afternoon and night. This storm center, which will deepen rapidly during it’s journey northward, will swing a strong frontal zone eastward through New England during the day on Monday…bringing us pockets of heavy rain, potentially some thunderstorms and certainly some very strong southerly winds.

In response to the approaching cold front, deepening low pressure and tightening pressure gradient, an anomalously strong low level jet stream will take shape and cross the area.

Model guidance is in pretty solid agreement that this low level jet will max out about as strong as they do in these parts…with 850 mb (in this case about 4000 ft above the ground) winds nearing 100 knots (115 mph) and winds at 950 mb (in this case about 1500′ above the ground) in excess of 80 knots. Both of these values are far above climatology…+5 to +6 standardized anomaly.

While the atmosphere won’t be primed for mixing these extreme winds aloft down to the surface, it’s quite likely we’ll have some damaging wind gusts to contend with. With the southerly flow and time of year we can safely assume surface winds will gust to 40-60% of the 850 jet (widespread 40-60 knots)…which would certainly yield some damage/power outages. A few other hints/red flags to consider…modeled 10-meter wind speeds are progged at 35 to 45 knots sustained for a time Monday evening. Similarly, MOS values are between 25 and 30 knots at Hyannis which is very high for that product at that location.

Bottomline: Between 2PM and 9PM…likely focused closer to dinnertime…a period of howling southerly winds is likely to impact the area. Expect power outages and localized pockets of tree and limb damage as winds gust 50 to 70 mph around the Cape. It’s not out of the question that a localized well-exposed location gusts in excess of 70 mph.

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