00z GFS Ensemble Chart

February 16, 2012

A few interesting things on the 00z GFS. 

– This weekends trough looks cool, but maybe slightly warmer than what we just saw the other day, it’s going to be tough to get sticking snow below 1,500′ except in a very heavy shower; nothing new there.

– The actual maps and model run now looks quite similar to the earlier 12z ECMWF with a sharp and cold trough dropping over us the end of NEXT week.  Confidence is growing that snow levels will be quite low at the end of next week, although precipitation is pretty much gone next weekend on both models so far.

– The operational run (blue) is a bit slower on the trough; a lot of the ensemble members are 12-24 hours earlier on the coldest air.

– As earlier, still no sign of an “arctic blast” or cold easterly flow like we saw last year at the same time.


ECMWF Weekly Maps

February 16, 2012

Fresh batch from last night’s ECMWF 00z run.  It had a pretty cold trough quickly moving through here about 10 days from now (the 12z does too).  Definitely good for snow into the hills around the Valley, and possibly lower if everything were to work out right before it dries out.

Week1 (remember this is averaged for a whole week):

Week2, starting on Sunday the 26th.  Interesting to note that the cold trough at Day 10 hardly shows up here due to ridging just before and just after it:

Week3, starting Monday, March 5th.  Newer trough to the north is a bit farther west with slightly below average heights over us:

Week4, looks cool and wet with a trough just off the West Coast, this is Monday the 12th-Sunday the 18th…mid-March:

As for that 12z ECMWF, I was “alerted” to it by Steve Pierce via a voicemail. So as soon as I got to work, I looked it up. Definitely cold at Day 9 & 10 (NEXT weekend, not this coming weekend). 850mb temps as a shot of cold air comes in from the north/northwest behind a cold front. I was scared for a minute after yesterday’s pronouncement.  But after checking some other data I felt better.

1.  The 12z ECMWF ensemble chart shows the operational one is the 2nd coldest on the morning of Sun, the 26th out of 51 ensemble members:

2. The GFS and GEM are milder, with weaker troughing:

Compare that with the ECMWF ensemble map for the same time:

We still have a cool trough this weekend, although not too chilly with the freezing level not even getting down to 2,000′ until possibly Sunday morning. Those of you at/above 1,500′ have a good chance at a few inches of snow Saturday through midday Sunday. Below that it will be either nothing or brief accumulation of snow/hail in a downpour Saturday.  It’ll be a strong onshore flow (SW wind) all day Saturday which isn’t very helpful to keep snow levels low either.

All models show a brief 2nd surge of chilly air around the 24th-26th, with the GFS a bit faster than the ECMWF.   No models show a blast of arctic air with northeast or east wind like we had in February 2006 and February 2011.

Chief Meteorologist Mark Nelsen