Northerly
winds are advecting in a shallow cool layer that is still moist,
leading to low clouds. Satellite shows that low cloud deck is quite
extensive and will likely not break tonight. Combined with light
northerly winds off Lake Pontchartrain, this will severely limit any
radiational cooling, unlike late last week. Some clearing is expected
tomorrow with a modest warm up and the winds being almost calm by then
ending any cold advection. However, Lake Pontchartrain could still add
just enough low-level moisture to sustain the low clouds until early
afternoon, while it clears out elsewhere sooner (other than widespread
thin high cirrus clouds). This is a very tricky situation with the
moisture being quite shallow and marginal for cloud cover, leading to
large uncertainty in the high temperature. ECMWF has 65F but isn't
showing the cloud cover that currently exists, while NAM 3-km is 53F but
usually is overly cold and cloudy.
Very little wind is expected tomorrow, and there won’t be any
precipitation either. With just some high cirrus clouds, albeit
thickening a bit, and no wind tomorrow evening, it is possible that the
low could be attained near the end (Wednesday 06z) due to better
radiational cooling then, though high dew points at the surface will be
an inhibitor.
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| Source: Penn State Meteorology |
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| Source: PivotalWeather |
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