Moisture Fizzling Out

December 11, 2009

Sure, we will probably wake up to SOMETHING on the ground in the morning, but it may only be a trace of snow or light glaze of ice.  Models have most definitely backed off on moisture through the next 24-30 hours.  Our RPM model has been showing that since 18z.  Now other models have hopped on board…at least the reliable ones.  Considering what I see on radar, that seems very reasonable.  This also fits the “El Nino” pattern perfectly too.  Look!  Moisture is coming up out of California!  We’re going to get soaked!  Oh, it never got here…  Remember those times in the past? 

I’m really glad that we never forecast a significant snow event to start with…at 5pm Steph went with a Trace to 2″ of snow before some freezing rain.  Now I’m just going to say a Trace to 1″ at best. 

So I’m doing some serious forecast surgery on about 12 graphics in the next 45 minutes.  That plus reigning in all the newspeople takes lots of time. 

Light precipitation tomorrow also means a chance for temps to warm above freezing…what a pain to change everything but good times otherwise this evening don’t you think?

Chief Meteorologist Mark Nelsen

Anyone have a question?

December 11, 2009

We’re doing a little mini “Ask Mark” segment at 10:38pm and need about 2-3 more questions about our current weather.  Anyone want to know anything?


Freezing Rain Arriving

December 11, 2009

Looks like widespread freezing rain spreading up through the Southern Willamette Valley right now.  The mid-level warming has arrived as forecast by models.  RAWS sites both east and west of the southern-mid Valley are above freezing and dewpoints are climbing quickly too…that’s a good sign that there is little chance we’ll see snow from Salem south.  In fact it’s looking less likely up here too.  Check out Corbett in the western Gorge at 700′.  East 3 gust 5 mph with all of 1.6 millibars easterly gradient through the Gorge.  There is no fresh source of cold air to move into the metro area.  That’s a huge difference from past snow/ice storms.  The other big difference is pathetic precipitation forecasts.  12z/18z runs of all models I’ve seen have only light precipitation from Portland north, a bit heavier Salem over to north Central Oregon.

So we are forecasting a Trace to 2″ snow in the Metro area tonight.  Most precipitation should fall as freezing rain or ice pellets, more likely just freezing rain.

Chief Meteorologist Mark Nelsen

Morning Storm Update

December 11, 2009

Well, maybe storm is too strong of a word.  But in the TV news world it’s good enough.  We are going to get some frozen precipitation tonight and Saturday.

I still think points #1-4 from the last post are still valid.  I’m thinking the 2 to 4″ of snow before a changeover to freezing rain is a good call by the NWS, but maybe at the heavy end.  I’m thinking just 1-3″ in the city, but whoever gets under a heavier deformation band (maybe south and east of here?) could get a bit more, or heavy freezing rain. 

This is quite a bit different than our past few snow/ice storms.  No massive outflow of cold dry air from the Gorge, but no sign of any low level warm advection from the south or west until the daytime Sunday.  So it’ll be tough to get above freezing tomorrow.  We’ll probably sit within 2 degrees of freezing from tomorrow morning until Sunday morning.  Sunday is a bit different as well.  In any other situation we’d just call for light rain showers in the valley with snow showers sticking around 1500′ or higher.  They may stick a bit lower early in the day, but light onshore flow will be mild and moist, so temps just gradually rise up to around or just above 40 degrees by late in the day.  Northwest flow should also give us sunbreaks which will help.

More later…