Probably more like cold rain tho...
Welcome to the first day of meteorological winter, which runs from December 1st to the last day of February. As we know, we torched today. Didn't really feel like spring with highs in the upper 60s to lower 70s across the area. That ends tonight. A cold front has passed through and temperatures have plummeted over 4 degrees an hour and 12 in three hours. Tomorrow will be a cold, raw day, as high pressure to the north drives cold air up against the mountains, a process known as Cold Air Damming (CAD) . Highs will be only in the mid 30s with some chilly wet rawness to boot.
A weak wave of low pressure is going to ride up the front, which is forecast to be stalled to the south of us tomorrow. As cold air streams in from the north, moisture will stream in from the south. Perfect, right? Not really. The cold layer will be shallow, as per normal CAD events. So any frozen precipitation will be a mix, likely mainly sleet and rain or sleet and freezing rain, if your surface temperature is below freezing. The surface temperature is even more crucial than the last event because all the cold will be near the surface. Urban and suburban areas will likely stay above freezing, leaving the usual suspects, areas with a location advantage like Damascus etc. to drop below freezing.
Temperatures will drop to the low 30s by daybreak and only slowly rise during the day into the mid 30s. I'd bank on a cold wet day instead of an icy one. There are many factors that go against the idea of having a icy Tuesday.
Reasons that it won't ice on Tuesday:
- No cold antecedent airmass in place. We hit 70 today.
- The cold air has to be shoved in from the north against the influx of warm air.
- The high pressure is moving in tandem with the precipitation so it ends up in a not very ideal position by the end of the event.
- Weak low pressure may not even throw enough precipitation to amount to much
- We are not forecast to drop below freezing for the duration of the event (except for those in the far NW of the county)
Well I should to present the other side right...
Reasons why it could ice on Tuesday:
- Don't underestimate the wedge-cold air is dense and doesn't like to move. Once it is entrenched, we are set.
- Good strong high pressure to shove the cold air in
- It's winter
Whoops... Got your hopes up... Let's crush them again... *Whips out the short term Hi-res models*
This even will be mainly a northwest suburbs event, as depicted by both the High Resolution Rapid Refresh (HRRR) and the Canadian (RGEM). The HRRR doesn't even bring the freezing line far past the Mason Dixon Line for the duration of the event. The CAD signature is obviously there, but the temperatures are too high and the cold too shallow for much frozen precip to fall.
