I hate to nag about it again this winter, but this morning is an excellent example of why I DON’T THINK WE SHOULD FORECAST SPECIFIC SNOW LEVELS (other than 1,000′ increments) IN MOST SITUATIONS! I know that all caps is annoying, but I’ve really come to that conclusion the last 3-4 winters. As such, I don’t think you’ll ever see me forecast a specific snow elevation below 1,000′ . I haven’t done that for a year or two. One okay situation might be with a stratiform snow event where it’s just solid rain/snow coming down.
This morning reminded me of the La Nina winter 2007-2008. This situation occurred several times in January and February. An organized area of heavy showers move through middle of the Metro area and up into Clark County during the coolest part of the day (6-9am). We also lost the mixing south wind overnight. It was down to less than 2 millibars southerly gradient between Eugene and Olympia. The two combined allowed sticking snow (and decent totals too!) down to sea level (Columbia River). So we ended up with 2.5″ at Battleground Brian’s place at 500′, and 1/2″ totals at 200-300′ westside, while at 1,000′ in Corbett, Sandy, Brightwood and other spots had bare ground. So WE ARE MISLEADING THE PUBLIC by giving such specific elevations. By the way, I’m not really cranky, but hoping other forecasters would clue in to this as well. This morning my wife heard someone on the radio saying something like “they’ve decided to lower the snow level down to 500′ now” Ugghhh!
Last night on-air we said the morning commute would probably not be affected by snowfall except in the hills. That was true, but of course where more than 1/2″ fell there were definitely slippery spots (in Clark County for sure). In my snow graphic we also said “Anyone Could See Sticking Snow” the next few mornings. That was okay too. Although I’d sure like to see some in MY yard!
So what changes the next 24 hours? Not much, except slightly colder airmass tomorrow morning. There’s no reason we couldn’t see a repeat of this morning, but it’s going to all be about the shower placement. I do note the experimental 1 1/3 km WRF-GFS has wind going calm again late tonight and in the morning. So sticking is possible anywhere for the Thursday morning commute again, with more roads (than today) seeing white briefly IF showers show up in your neighborhood. If you commute before 9am, I’d get up a little early and see what’s going on. There does seem to be a bit less moisture to work with, but just one batch of showers could drop a quick inch easily.
Friday morning is dry on the GFS and NAM, but still a little moisture for early snow on our RPM (not much).
Beyond that, the big question mark on the 7 Day forecast is still Sunday and President’s Day. The models are very stubborn with their solutions. The ECMWF for 2-3 runs now has given us dry and mild conditions Sunday and Monday with temps maybe 45-50 both afternoons. The GFS is still drilling a cold front down over us with sticking snow to low elevations. The disparity is due to the ECMWF splitting energy with a deep trough dropping south well offshore. The 12z GFS has a much shorter period of precipitation I notice with a mainly daytime Sunday event and then precipitation is gone by early Monday. If so, it could just be a few hours of wet snow in PDX (no east wind) with a nice 3-4″ dump on the hills and foothills (reminds me of 2007-2008 again). Then real cold (especially for the last week of February!) Tuesday-Thursday.
Chief Meteorologist Mark Nelsen
A short post since there isn’t too much new to talk about. Note that PQR (Portland NWS Forecast Office) recorded a Trace of snowfall, which means the winter total of .3″ still stands. Of course that was the arctic front that came through two days before Thanksgiving. That system brought more of a widespread snowfall to everyone, but I don’t think anyone outside of the hills had more than 1″. Today was heavier and more convective/spotty.
Posted by Mark Nelsen 
