re: Snow Tease for Baton Rouge (Saturday) UPDATE (1/20)

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National Weather Service New Orleans LA 251 PM CST Sun Jan 16 2022 .SHORT TERM... Tonight through Tuesday... Tonight, the upper level low is forecast to continue moving off the east coast of the US. Strong northwesterly flow will help to continue to advect cold and dry air into the region. Overnight lows tonight into Monday morning are forecast to be in the mid 30s to upper 30s. Most locations are not expected to touch freezing, but it will be close. Monday, northerly flow continues to advect cold and dry air into the region for another day. Upper level ridging will dominate the pattern. Looking at the models, rain is not expected Monday. Similar to Monday morning, the lows on Tuesday morning are forecast to be in the mid 30s and low 40s. Tuesday, zonal flow aloft will dominate the upper level pattern. Surface winds will shift from northerly to southerly during the morning hours, which will allow for the reintroduction of moisture and warm air into the region. Weak upper level divergence will allow for some lifting in the environment to occur as well. Based on the models and patterns, rainfall is not expected on Tuesday. MSW .LONG TERM... Wednesday through Saturday... Zonal flow will continue to dominate the upper level pattern Wednesday into Thursday. A shortwave upper level trough is expected to influence the area Wednesday into Thursday, enhancing rain chances for the area. Southerly surface winds will act to enhance warm air and moisture advection into the area, which will increase some instability in the environment. Upper level divergence will also help to enhance some lifting in the environment. Scattered to numerous showers will be possible Wednesday afternoon through early Thursday morning as the front moves through the area, looking at the current models. The main threats associated with the frontal system would be gusty sub- severe (30-60mph) winds and lightning. The models are still showing disagreement on the strength of the system and overall instability looks fairly limited based on the current models, but we will be watching how it develops over the next few days. Behind the front overnight Wednesday into Thursday, strong cold air advection will set up over the area, and northerly surface winds will help funnel the beginning of this cold air into the region. As a result, lows on Thursday morning area forecast to be in the upper 30s and low 40s, as cloud cover will help to moderate the temperatures some. Thursday and Friday, as the low moves off the east coast of the US, zonal flow will set up over the area. Northerly surface winds will help to enhance cold air advection and dry air advection into the region. Weak upper level convergence Thursday will help to increase the sinking and stable air in the environment. As a result, lows on Friday will be very chilly, looking at the models, with lows in the upper 20s to low 30s. Strong cold air advection behind the front and a lingering low level cloud deck could cause some winter precipitation to develop. Some of the models are indicating the potential for some isentropic lifting continuing into Friday, while some, like the GFS, push the front offshore quickly. If the rain lingers longer over the area due to isentropic lifting, then there will be a better chance to see some winter precipitation. But the timing will be key for this to occur, and there are still a lot of uncertainties/disagreement in the models. On Friday, some weak upper level divergence associated with a weak upper level trough will help to increase some lifting in the environment, but strong northerly flow will keep temperatures below average with lows on Saturday morning forecast to be in the mid 20s to low 30s. Saturday, the models are very uncertain on the upper level pattern and timing of the different troughs. Looking at the general model consensus, a shortwave upper level trough is expected to influence the area, enhancing rain chances. Strong northerly surface winds will act to limit instability and moisture in the environment. Weak upper level divergence will act to enhance lifting in the environment. Overall, rain chances will be fairly low, given the uncertainty of the system and lack of moisture in the environment. It will be interesting to see how these patterns develop over the next week. MSW

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