The weather story this week is early spring, and not just because Punxsutawney Phil said so. (And can one truly call it an early spring if winter hasn’t really been much of a factor?) Much of the week will be punctuated by temperatures in the low 70s as our lack-of-winter continues thanks to a rather high-latitude jet stream keeping Arctic air locked in to the north.
With this warmth, though, comes the specter of severe storms, and it appears there is some potential for this on Thursday as a cold front approaches the area.
Thursday’s severe potential
There are indications in guidance that a squall line could organize and head our way for the Thursday afternoon/evening timeframe. Said squall line may be capable of producing damaging wind gusts and perhaps a tornado if it can materialize and remain strong as it gets into Charleston. Interestingly, the Storm Prediction Center has been outlining the area in a 15% severe thunderstorm risk for Thursday for the last few days. It’s rather rare to be outlined in a severe weather risk area this far out, but this is largely owed to the consistency in the guidance for an environment favorable to severe thunderstorm development.
Right now — and it is still rather early — we have a couple ingredients working in favor of severe storms (good wind shear and lift via a cold front) and a key ingredient, instability (more specifically, the lack thereof), working against it. Let’s look at these ingredients:
- Wind shear: Check. There will be more than ample shear — needed to separate thunderstorm updrafts from downdrafts to keep them healthy — to allow for the development and maintenance of a squall line as it pushes eastward.
- Strong low-level jet: Check. Guidance continues to hit on a 40-60 knot low-level jet being somewhere over eastern SC by Thursday afternoon into the evening. If the squall line manages to encounter this environment and remain vigorous, damaging wind gusts will certainly be possible in any storm that can tap into this jet.
- Instability: Limited. As is so often the case in winter, this is going to be the governing factor over the extent of any severe weather on Thursday, and what makes this forecast so tricky. Plentiful wind shear can often help storms take advantage of even meager instability (a high-shear/low CAPE scenario) and produce sporadic severe weather. Cloud cover and perhaps some pre-frontal showers will limit how warm we get and how much instability can develop. And, as usual in the cool season, lines of storms have a hard time surviving to the coast as they encounter the cooler and more stable marine layer.
We in #chswx will continue to monitor trends as the next few days go on. Plan for a gusty, stormy Thursday afternoon and evening; if it gets more sinister, we’ll let you know.
Cooldown for the weekend
After the frontal system gets through Thursday, we will see temperatures drop closer to early February norms starting Friday. Expect highs in the low to mid-60s under mostly sunny skies Saturday and Sunday.
If you are looking for full-throated winter, though, don’t get your hopes up. Above-normal temperatures are favored through the end of the month, according to the Climate Prediction Center. (And, for that matter, the groundhog.)
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