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33 degrees at Tye Mill this morning...

Welcome back Fall! While the official first day isn't until Friday, the meteorological autumnal shift has begun. A large, well defined low pressure system and associated cold front swept into the region last night bringing a dramatic change in temperatures and the first significant precipitation to the PNW since early June.

Over the next few days we will see copious moisture, penetrating into Eastern WA at times, freezing levels around 5500-6000', and NW-W upper level flow bringing spotty convergence showers to parts of King and Snohomish counties. Sounds like a January discussion! Mt. Baker will of course be the center of many rumors regarding 37" of new snow on the summit (happens every year ;). This event should go a long ways to help with the regions many wildfires, and hopefully we've seen the last of the hot, smokey days for 2017.

By the end of the week things dry out and we should enjoy some absolutely gorgeous early Fall weather: cool nights, warm afternoons,…

Spring has Sprung

Have a great spring  summer ya all.   See ya in the fall.

jM

Weather Forecast Accuracy

FYI: I was asked to clarify a statement that was made on the last weather report about forecast accuracy being +- 2%.  Dan and Jack (avalanche forecasters) record the forecasted snow totals along with their daily weather observations.  The goal for this was to statistically provide an accuracy % for our internal forecasts. The scientific method was a simple record of snow totals forecasted (see example below) and then compare that spread with what actually fell.   So if the forecast was for 3-5” and what fell was within that spread, that was a score of 100%.  Plus or minus percentages correlates with how far off from the forecasted spread the actual snowfall was.
Example: 24hr Precipitation ending at 4 am: Today 24hr water = .25-.5 snow = 3-5   - actual = 4”  100%
As stated in the last forecast of the season with the seasonal stats, the accuracy was +-2%.  Another way to look at this is:  The forecast for snow totals was 98% accurate – or 98% of the time, the actual snowfall fell within for…

Seattle Wettest Winter on Record

Even though the mountains  got a relatively normal amount of snow this year, Seattle had its wettest period on record.   Seattle has soaked up 44.67 inches of rain since October 1, according to the National Weather Service.
That makes this October-through-April the wettest such period since record-keeping began in the city in 1895.

The normal amount of rainfall for the October-through-April period in Seattle is 30.9 inches, according to the service...

Full story:  http://www.seattletimes.com/seattle-news/weather/seattle-just-broke-a-122-year-old-record-for-rain-because-of-course-it-did/
JM

9:00 Start for Teardown, Monday April 24

Sleep in a little bit and take it easy out there.

MOUNTAIN WEATHER FORECAST

Time and Day:  Sunday 0700  (Last day of this great season) 
The Snapshot:   Dan V says it is mostly cloudy and 35degrees this morning.  Rain this afternoon with mixed rain and snow on the upper ridges.   Another short dry period tomorrow morning with rain expected on Tuesday.
The Science:  Some weak upper-level ridging has provided a short period of dry but cloudy conditions over Stevens Pass.   Radar shows more precipitation to the west which should reach the mountains around noon or so.   A similar pattern emerges tomorrow with weak upper-level ridging providing a dry and partly cloudy morning with rain moving in tomorrow night and Tuesday.   
What a great winter:  Some seasonal stats to add to your memory of the great powder we all enjoyed:
443” of snow fell   Nov        40 Dec        133 Jan         42 Feb         90 March   105 April      18 (thru 4/22)
Best storm/powder cycles: December 1-6 we got 51”, February 26-March 9 we got 88”.
Forecast accuracy for snow totals  had an error of +-2…

8:00 Sunday April 23rd no ABS

MOUNTAIN WEATHER FORECAST

Time and Day: 0700 Saturday
The Snapshot:  Increasing clouds today with light rain reaching Stevens Pass by mid-afternoon or so.  Cooler tonight with mixed rain and snow showers tomorrow.  
The Science:  It’s a balmy 400f  this morning with high clouds moving in.  Moisture ahead of an approaching cold front will bring light rain to Stevens Pass this afternoon with freezing levels +- 7000’.  Once the front passes east of the crest, freezing levels will drop to around 4500’ with light snow possible overnight.  A weak ridge forms behind the front which will produce some partial clearing tomorrow morning with mixed rain and snow showers re-developing through the day.  
The Long Range:   A steady stream of precipitation takes aim at the PNW next week.
24hr Precipitation ending at 4am: Today 24hr water = lt .25  snow = trace Tomorrow’s 24hr water = .5  snow = 1-3
Trend and Timing: Light rain develops this afternoon with light mixed rain and snow tomorrow.  

24hr temperature ending at 4 am:…

MOUNTAIN WEATHER FORECAST

Time and Day: 1100 Friday
The Snapshot:  A beautiful sunny day today with high clouds developing tonight.  Dry for most of tomorrow with light rain developing late afternoon.   Sun breaks with light passing rain/snow showers can be expected for the final day of the season.
The Science:  A high pressure ridge has produced a beautiful clear day over the North Central Cascades.   The eastern basin is heating up with Wenatchee temperatures possibly reaching into the 70’s today and tomorrow.   The warm air will also make its way west with freezing levels over Steven Pass peaking +7000’ during the heat of the day tomorrow.  Good pond skimming.
A cold front will move through late tomorrow, lowering temperatures and bringing light mixed snow and rain with it.  The atmosphere will remain unstable under WSW flow through Monday with light mixed rain and snow showers persisting.
The Long Range:  The wet spring weather pattern will continue through at least the middle of next week.
24hr Precipitati…

MOUNTAIN WEATHER FORECAST

Time and Day: 1000 Thursday
The Snapshot:  Looking ahead to the weekend, tomorrow and the second half of Saturday will be mostly dry, warm and partly sunny.  Light rain enters the scene on Saturday afternoon with light mixed rain and snow persisting through the final weekend of the season.  
The Science:  These light snow showers will taper off today as high pressure ridge moves in.  A low-pressure system developing way out in the Pacific will pull warm and dry air up from the south with the moisture eventually making its way into the region on Saturday.   Light showers with sun breaks will continue through Sunday.   

The Long Range:   This active weather wet weather pattern will persist through most of next week.
jM