Cold Models

March 22, 2013

This is pure weather geek info below, ignore this posting if you aren’t a geek!

Earlier this week I had noticed how unusually cold models were.  This afternoon I wondered…how did they do?  I had some time this evening, so I figured this would be a better use of my time than Facebook or planning the next vacation. 

Take a look at the 850mb temperature forecasts; that’s the temperature (in celsius) around 4-5,000 ft.  The forecasts are for the past 3 days leading up to today.  So all model forecasts under “5am” are for 5am Friday going back 3 days.  The actual conditions are from the twice daily balloon sounding over Salem.

 

5am

5pm

Actual SLE 850mb Temp Today

-6.7

-5.7

 

 

 

FCST ON THURSDAY

 

 

12z NAM

-8

-8

12z GFS

-7

-6

12z ECMWF

-8

 

FCST ON WEDNESDAY

 

 

12z NAM

-9

-8

12z GFS

-7

-6

12z ECMWF

-7

 

FCST ON TUESDAY

 

 

12z NAM

-9

-9

12z GFS

-8

-7

12z ECMWF

-8

 

The NAM was definitely too cold, but even the other models ended up slightly on the cool side.  They did improve a bit as the “event” got a little closer.  You would expect (hopefully) numerical modeling to latch onto reality a bit more as we get closer too.

Chief Meteorologist Mark Nelsen


Hockinson Tornado Video

March 21, 2013

This came in late this evening from a viewer.  Jason Williams lives right beside the field the tornado ripped through today.  It appears to be the end of the event.  At the very beginning of the video you can see a leftover circular motion to the aluminum roofing flying across the field:

Chief Meteorologist Mark Nelsen


Tornado Near Hockinson Today

March 21, 2013

6:40pm Thursday…

And exciting couple of hours from 5-7pm as we heard of a possible tornado in the hills just northeast of Hockinson around 4:10pm.

Irene, whose barn it partially destroyed, says it was quick.  A bang, and then chunks of her barn were flying away. Most important, she told us twice on-air that she could see a swirling “whitish” mass down over the barn.

The NWS folks are out there right now and we’ll hopefully find out if it was a tornado or not.

7:15pm update…

NWS says it WAS a tornado.  EF0 rating.  Here’s the statement:

“PRELIMINARY REPORT. ROOF PARTIALLY TORN OFF A BARN CONFIRMED. DEBRIS SPREAD OUT IN A 120 DEGREE CONE FROM THE BUILDING WITH THE LARGEST OBJECTS THROWN TO THE NNE OF THE STRUCTURE. LIGHTER OBJECTS WERE MOSTLY HUNG UP ON A NEARBY FENCE TO THE E AND SE OF THE BARN. NO OTHER DAMAGE WAS NOTED TO NEARBY TREES…STRUCTURES AND OTHER VEGETATION AROUND THE BARN. THE TIME IS ESTIMATED FROM RADAR AND REPORTS.”
 

Chief Meteorologist Mark Nelsen


A Stormy Wednesday

March 20, 2013

3:00pm Wednesday…

WIND
Lots of action the past 12 hours…peak gusts were the strongest we’ve seen since December along the Coast! Lots of 60-70 mph reports. Very impressive for a couple days before Spring Break don’t you think?

MarkCoast_PeakWindGusts

Here in the valley peak gusts were generally in the 30-40 mph range, with most areas seeing the peak gusts as showers roll through around midday. 

PLOT_Wind_Metro_Valley

That wind will back off quickly this evening.  Eastside I see The Dalles had a peak gust of 59 mph!  Very impressive even for  the east of the Gorge in spring.

THUNDERSTORMS
Only one strike so far west of the Cascades, north of Bonneville.  But it’s a sure sign of spring that the cold front plowing through NE Oregon is spawning a nice line of thunderstorms currently moving quickly through Wallowa and Baker counties. 

KPTV_Default

On the backside of the front Meacham has gone from 50 to snow on the side of the freeway in a little over an hour!

MeachamWestbound_pid637

The wind dies down, the thunderstorms move east the next few hours.  That leaves us with diminishing showers the next two days west of the Cascades as a much colder airmass moves in.  Expect a dusting of snow anywhere above 1,500′ overnight, and possibly as low as 1,000′ in the Coast Range and west slopes of the Cascades.  It’s unlikely we’ll see a dusting to 1,000′ in the metro area since showers will be mainly light overnight.

Thursday night and Friday morning any showers left over should be at least a mix of rain/snow or just all snow even to sea level with a very cold airmass for late March.  However, moisture seems to be lacking if you want sticking stuff down at the lowest elevations.  In this pattern you want a heavy snow shower to suddenly drag the snow down to sea level; I don’t see that.  In fact our RPM is mainly dry during that period.

Drier and slowly turning milder this weekend and early next week.  Here is the 12z ECMWF ensemble chart:

tseries_850t_000-360_Portland

Chief Meteorologist Mark Nelsen


Wind, Rain, and Snow

March 19, 2013

11pm Tuesday…

A bit late posting tonight, but everything is progressing pretty much like expected. East wind has been gusty in the Gorge, peak gusts 50-60 mph earlier. South wind just now starting to appear at the Coast and it’ll ramp up quickly the next few hours. South wind arrives in the Valley by daybreak too.

Nice and wet out there and mostly steady rain should continue until daybreak. Then it’s on to the shower/sunbreak/hail spring routine.

I’ve been analyzing all the maps/models with regard to low snow levels…I’ve got a few thoughts:

All models are very chilly Thursday morning through Saturday with snow levels (especially overnight hours) regularly down to 1,500′ or lower. Each afternoon it’ll be up around 2,000′ or even a little higher…it’s Spring and sunbreaks do wonders. But for several reasons I don’t think we’ll get snow much lower than 1,000-1,500.

1. NW Oregon is really on the southern edge of significant moisture during this period, for example it’s mainly dry from Florence over to Eugene. Not totally dry, but the deeper moisture is farther north closer to the upper-level disturbances passing by.

2. Without the good moisture, I don’t expect real heavy showers to drag the snow level down much below 1,000′. Our RPM has NO precipitation over Portland from Thursday evening through Friday evening. The 4km WRF-GFS is similar.

3. There may be sticking snow lower than 1,000′ in the Coast Range and maybe some spots on the west slopes of the Cascades.

Any of us could see snow mixed in with the showers Thursday and Friday…it’s going to be a chilly couple of days!

For skiers, as I mentioned not a ton of moisture, so a nice snowstorm, but not a huge one. Maybe 12-18″ the next 3 days up there: Here’s our evening RPM model snow forecast:

RPM_72_SNOW_00z

Keep in mind the forecast snow for Hood River and The Dalles is just due to contouring issues on the map…it won’t snow in those locations.

Milder, and drier weather returns next week for Oregon’s Spring Break. Definitely not DRY, but DRIER.   Here is the 00z GFS ensemble chart showing upper-level temperatures returning to average next week:

tseries_850t_000-384_Portland

Chief Meteorologist Mark Nelsen


A Wet Week Ahead; Chilly Start to Spring Break

March 18, 2013

A very nice looking low pressure center will be spinning up quickly the next 24 hours well offshore and head for northern Vancouver Island. Even with a forecast pressure around 985 millibars, it’s too far to the northwest to give us real strong wind either at the Coast or here in the Valleys. That said, gusts 60+ at the Coast and 30-40 mph are likely later Tuesday night and very early Wednesday morning just ahead of the cold front passage. We’ve seen very few (maybe only 1 or 2?) of these strong low pressure centers since late December, so it’ll be a refreshing change. Ahead of this we get a good 6-7 millibars easterly gradient developing through the Columbia River Gorge by sunrise. So those of you out in Corbett and Washougal expect to hear the wind roaring with gusts up around 50+ mph in the next 12 hours. Luckily this time of year the afternoon heating east of the Cascades doesn’t allow the high pressure to linger east side long so that wind will be gone by evening.

Plenty of rain with this system tomorrow and especially tomorrow night and Wednesday.  This is good news because:  1) We’re well below average January-March, and,  2) I just planted 100 Douglas Firs and they need a good soaking to settle in!

What caught my eye today and this evening is how cold the two upper-level troughs are going to be after the cold front passes through. The first comes through early Thursday morning, the 2nd late Thursday night and Friday morning. The NAM model has been “over-chilling” 850mb temps recently; not sure why. For example last weekend it was forecasting around a -7 or -8 and we bottomed out at -6 Saturday morning (or was it Sunday?). Anyway, it’s saying -7 to -8.5 now with a 2nd trough late Thursday night!  The GFS and ECMWF are a bit more reasonable in the -6 to -7 range.  That temp combined with showers could easily allow sticking snow down to 1,000′ or even a little below in the overnight hours.  The issue for Wednesday night is that we still have breezy southwest wind (onshore flow) and showers seem to taper off during the overnight hours.  Then on Thursday night surface high pressure is building in from the SW so we may not have much of any moisture.  It’s something to keep an eye on but I think lack of moisture is going to be an issue if you want anything more than a dusting down to 1,000′. 

Forget about sticking snow in the city of course…it’s too late for that unless we have some sort of solid and heavy precipitation with those chilly upper-level temps.

Friday between 2-4pm Spring Break begins for most Oregon schools and it appears to start chilly.  Not much rain this upcoming weekend but definitely cool.  Good for skiing! 

Models do imply more reasonable temps, but not necessarily dry beyond Sunday.  Here is the 18z GFS ensemble chart, click for a “non-gray” view:

tseries_850t_000-384_Portland

You can see temps go to average or a bit above for next week, so Spring Break may not be a total loss.  But what would that week be without some hail, gusty wind, and occasional downpours?  I spent every Spring Break week of my school career (except one) somewhere between Seattle and Salem and I think I remember 1, or MAYBE 2 that had some sort of sunny and warm weather.

Chief Meteorologist Mark Nelsen

 


Climate Tribes…Great Post By Professor Cliff Mass

March 18, 2013

I just read this wonderful (my opinion) overview of the stalemate/impasse in the global warming issue.  I think Cliff sums up the current situation quite well.  This is one of several reasons I rarely mention global warming in my nightly weathercasts.  In fact I can’t remember the last time I did!

http://www.cliffmass.blogspot.com/2013/03/climate-tribes.html

earth

Chief Meteorologist Mark Nelsen