High was 38F at the beginning before the snow started and became heavy almost all day, with occasionally up to 2”/hr of snow accumulation for a total of at least 8”! However, the heavy snow cooled it down to 27F in the late morning, staying there for the rest of the day, and there is unexpectedly severe undercatch with only 0.23” so far – ridiculous for the Gulf Coast!
It will likely warm up a bit this evening as the snow stops, but clearing skies and fresh snow cover will lead to some radiational cooling later tonight, though the northerly wind off Lake Pontchartrain will probably never completely calm down, limiting the cooling a bit. However, the winds will be light enough late in the night that there is a chance of the land breeze kicking in and shutting off the wind off the lake just around sunrise, leading it to cool down a bit faster late in the night, with large model disagreement on this (HRRR shows this while NAM 3-km doesn’t; KMSY is just west of Kenner). Sunshine and light winds will lead to a gradual warmup tomorrow mitigated by the rare deep snow cover, which again models disagree on. The snow cover is leading to greater than usual uncertainty on temperatures for a quiet day! It's also such a rare setup that there isn't really past data to base off as analogs.
Winds will be at the maximum at the beginning of the period (Wednesday 06z), with increased instability from the warm lake influence counteracting the nocturnal inversion's suppression of winds mixing down to the surface, before gradually tapering off as surface high pressure moves in. I suspect that the USL shows a bit too much lake influence with a bit too strong of winds and warm temperatures.
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| Source: PivotalWeather |
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| Source: weather.us |
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