Models flipping rain to snow
Regarding the Thu-Fri system, it now appears more likely (but still
not definite) that northern and southern streams will stay separated
until phasing occurs to the east of our region. This maintains a
more positive/neutral tilt which forces a more offshore track of
surface low, keeping most of its precipitation offshore as well.
That being said, there may be enough lift from northern stream
trough and sufficient moisture to generate some light rain or even
some light snow depending upon surface temperature. Right now models
are showing an initially mild airmass which favors rain, but
eventually colder air is drawn into region behind departing system,
which could result in a changeover to light snow later Thu night
into Fri (assuming enough moisture remains). In any case, this looks
to be a light precipitation event with very minor impacts. We`re
probably not looking for more than an inch or so of accumulation
(especially in the hills) according to ensemble probabilities.
Canadian ensemble is most aggressive and GEFS/EPS less so. But it
should be noted that these probabilities are based upon straight
10:1 snow to liquid ratios and do not take surface temps into
account. It may end up being a little too warm to allow much snow to
stick outside of the higher elevations.