Bay Area residents, brace yourselves for a breezier and slight uptick in the mercury as we push through the final week of February. According to the National Weather Service, southerly flows are set to gradually climb temperatures through midweek. Don't ditch the umbrellas yet. Light precipitation is on the cards for tonight, with a higher chance for widespread showers brewing for Wednesday into the night. "Overall a warmer than normal and drier than normal pattern are expected through the upcoming week," the service predicts, a respite from thoughts of a chill clinging to the air.
Today's forecast hints at a lively show from the elements, with a surface high pressure giving way to a surface low sweeping through the northern Great Lakes. This hand-off will churn up a tightening pressure gradient across parts of the Ohio Valley, escalating to breezy conditions that could see southwest winds gusting to around 25 knots late morning through mid-afternoon. While the boundary layer mixing won't be particularly deep, it's enough to have us chasing down any loose hats with temperatures cresting around 50 degrees up north, and mid 50s down south amidst "some filtered sunshine from time-to-time," although, mostly cloudy skies are expected to dominate, especially in the afternoon.
As night blankets the region, the weather narrative takes a murkier turn with an embedded shortwave digging southeast from the Northern Plains into the Mid Mississippi River Valley. The melee brings with it a fortified southwest low-level jet, fueling both lift and moisture advection. "ISO/SCT SHRA should develop and move quickly through the area tonight into early Tuesday morning," the NWS details, though not everyone will witness the downpour. Some spots may encounter around a tenth of an inch of rain, balancing out the lows in the mid to upper 30s before bouncing back into the lower 50s come Tuesday afternoon, with clouds expected to scatter from west to east as the day ages.
Looking farther into the week, skies clear somewhat Tuesday night, providing a temporary reprieve before rain returns to stage a dusky entrance by Wednesday afternoon. "QPF footprint not overly concerning with this particular system, but a swath of 0.25" - 0.50" is certainly plausible," the NWS projects. Post-cold front, Thursday resets to seasonal normal temperatures, with sporadic precipitation chances extending into Thursday night. Welcoming high-pressure systems could mean sunny conditions as we hit Friday, but keep an eye northward Saturday where a Clipper might just graze the top of our area with colder air to end the week right on Sunday's doorstep.
For those about to take to the skies, pilots can expect widespread cirrus coverage, with broken/overcast high-level clouds hovering through most of the period, supplemented occasionally by mid-clouds in the 10-12kft range. "A moistening of the profile will occur beyond 06z with the approach of a sfc trof," the NWS anticipates, potentially resulting in a descent from VFR to MVFR by Tuesday morning at northern airstrips like KDAY, KCMH, KLCK, and KILN. Isolated to scattered showers and corresponding drops in visibility might also pepper the situation in the wee hours of Tuesday for travelers.
