Showery first half of the week
A South Louisiana winter weather staple… thermostats have switched from heat to air conditioning in just 24 hours.
Today and Tonight: Milder air is in place as a weak cold front has stalled in the region. Highs will make it into the mid 70s. Expect mainly cloudy skies today with a few showers. It will not be a washout and with only about 40 percent coverage in measurable rain, some spots could remain dry. Overnight, clouds will stick and shower activity will increase, especially after midnight. Patchy fog may develop as well—especially in coastal area. Lows will be in the mid 60s.
Up Next: Tuesday will be a bit more unsettled than Monday with scattered showers and thunderstorms bringing a round of rain to most of the forecast area. It will still be mild though with highs in the mid 70s. The cold front will finally kick through on Wednesday with showers ending, clouds breaking and temperatures cooling. Near to slightly below average temperatures are expected to conclude the week.
THE SCIENCE: A zonal upper level pattern will remain in place through Wednesday. A series of fast moving and fairly weak short wave troughs will slide through this zonal flow and bring unsettled weather to the forecast area. The first of these upper level troughs will slip through the region Monday. This system will drag a weak front into the area this morning. However, as the upper level system quickly races east, the boundary will stall over the area. This will serve as a focus for continued shower activity through the overnight hours tonight. Instability will be fairly limited today as the boundary moves in, and only expect to see showers through the day. Heading into tonight, continued weak low level convergence along the front and some isentropic forcing in the mid-levels will keep clouds and a chance of showers in the forecast. With milder temperatures and rain over a recently cooled surface, some fog may develop as well—especially in coastal areas. Temperatures will be quite warm with overnight lows only dipping into the lower to middle 60s. Another fast moving short wave will slide through the Gulf South Tuesday. This system will have more favorable jet dynamics in place, and expect to see more numerous showers and a few thunderstorms throughout the day. The weak boundary will still be over the region, and this will serve as a low level focus for convective activity through the day. Instability parameters also look more favorable tomorrow, as mid-level lapse rates steepen and some marginal CAPE develops. Fortunately, low level wind shear values will remain low, so any thunderstorms should remain on the weak side tomorrow into tomorrow evening. The short wave feature will quickly race to the east tomorrow night, and expect to see the weak frontal boundary begin to push offshore by Wednesday morning. A secondary surge of energy sliding through the Great Lakes will drive the front further offshore by Wednesday afternoon with clearing skies and cooler air feeding into the area. Temperatures should be a good 10 degrees cooler on Wednesday in the wake of the front, and any lingering post-frontal showers should come to an end by the afternoon as increased negative vorticity advection, subsidence, and dry air advection develops. Another short wave feature sliding through the Midwestern states Wednesday Night and Thursday will force an even cooler air mass into the forecast area. Given this, the forecast calls for highs in the lower to middle 50s on Thursday. With a thermal trough and clear skies in place Thursday night, expect to see temperatures cool into the 30s across most of the forecast area. Only areas south of the tidal lakes and along the immediate coast should remain in the lower 40s. Weak shortwave ridging aloft will keep skies clear on Friday, and a gradual shift in the winds to the southeast should allow for a slight moderation in temperatures in the upper 50s Friday Afternoon. Southerly flow should further increase Friday Night and Saturday as a deepening trough develops over the Plains states, and deep layer southwest flow develops in the mid and upper levels across the forecast area. Thunderstorms are expected to develop along a strong cold front that will move into the region by the middle of the weekend. Temperatures will drastically fall behind this front before it stalls in the Northern Gulf keeping showers in place for Monday but with highs only in the 50s.