Rod Hill's Winter Outlook 2018-2019

By Rod Hill on 09-Oct-18 16:38.

Before I begin, it is important to share with you my track record of accuracy for seasonal forecasting, dating back to 2000-2001.  Last winter my forecast was a success, largely because of my 67% confidence call for a below normal water year.  In fact, PDX recorded a water year ending September 30th of 30.03 inches, (normal is 36.03).  My error last season was a projection of below normal temperatures, which was clearly incorrect.  Other points, correctly called for a quiet valley snow year and a call for no significant valley windstorms.  Overall, my seasonal outlooks rate a 66% accuracy rating, compared to an industry standard closer to 55%.

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HERE IS MY 2018-2019 WINTER OUTLOOK  (followed by research discussion)

1.  TEMPERATURE:  Normal to above average, 73% confidence

2.  PRECIPITATION:  Near to below normal.  Best chance 35.40" at PDX  (Normal 36.03")  

3.  VALLEY SNOW:   Less than 6.00 inches, a large snowstorm is unlikely.

4.  VALLEY WIND STORMS:  40% chance of a 60 mph wind event, a significant or above average chance.

5.  MT. HOOD SNOWPACK:  Below normal year, projecting season snowpack at 66% of normal. 

MY RESEARCH NOTES: 

The above conclusions are largely based on the NOAA Enso Outlook calling for a weak to moderate El Nino this winter.  I ran a set of winter seasons dating back to 1950, that are on record with the Enso temperature range of positive departure expected in the coming months.  I also ran years following summers with an extreme number of 90 degree days and multiple year patterns, matching present day.  Below are my findings related to the above Winter Forecast. 

1.  TEMPERATURE:  11 of the 15 winter seasons I consider as analog years showed near to above normal temperatures.  In fact, the last cool year of consideration was the winter of 1979-1980, making a cool winter unlikely. 

2.  PRECIPITATION:  The 15 analog seasons have an average of 35.43 inches, which is near normal and only slightly below. When looking at weak to moderate El Nino winters following hot summers, average precipitation for the complete water year is 35.36 inches.  It is worth mentioning, my research shows a possible range between 25.87" and 43.03 inches.  Again, my number of highest confidence is 35.40 inches.  

If I may, my highest confidence number for last season was 30.10" and PDX received 30.03 inches!

3.  VALLEY SNOW:  Analog seasons show an average of 7.3 inches.  My research gives a 50% of winter snow in Portland being less than 3.00" and a 50% of winter snow being over 8.00".  Average snowfall following a hot summer is 5.4", (last winter recorded 7.6" and the winter of 2016-2017 received 11.7").  The "kicker" for me is my finding that it is extremely rare for PDX to go three winters in a row with 6.00" or more of total snowfall each year.  In fact the last time was 1977 - 1980 and the time before was 1949-1952!  The result is an 8% chance for PDX to receive 6" or more of total snowfall this coming season.  Therefore, I am calling for less than 6.00 inches of total season snowfall for 2018-2019.

4.  VALLEY WIND STORMS:  6 of the 15 analog years had a significant wind event, which is 40% and considered to be an elevated chance of seeing a period of 60 mph wind gusts or higher. In fact the analog winter of 2014-2015, which followed a hot summer, had a December 11, PDX south wind gust of 67 mph, the strongest wind since 1981.  The event lasted 4-5 hours with 40-55 mph consistent wind speeds.  It is worth noting that history overwhelmingly shows Portland's biggest wind storms take place in La Nina and Normal Enso winters, neither of which is expected this year. 

5.  MT. HOOD SNOWPACK:  Analog years show a 50% chance of a 100% of normal snow year, so there is reason to be hopeful for a good season!  However, the analog average is a snowpack of 66% of normal and it is alarming that two of the lowest snowpack seasons ever recorded show up in my data set.  The winter of 2014-2015 produced the lowest season snow total on record at just 25% of normal.  Also in the analog years, is the winter of 2004-2005 when the snowpack was 44% of normal.  Mt. Hood Skibowl's front face was closed much of both seasons. It is worth pointing out that last winter's snowpack was 77% of normal, meaning a forecast of 66% of normal would only be slightly less snow.  A little perspective shows a 25% of normal snow year at Timberline would dump a range of 240-290" of snowfall for the season, depending on water content or weight of the snow, while a 100% of normal year may dump more than 600" at the lodge!  Lots of factors go into labeling a resort ski season as good or bad, including timing of big snowstorms, weekend weather conditions and overall freezing levels on the mountain. 

I hope you find my Winter Outlook to be a valuable tool as you plan the winter season.  As a forecaster, I live in the relm of possibilities and am often reminded that averages are a good method to determine odds of wet or dry, but sooner or later the entire data set range of what is truly possible comes true.

Happy Winter Season   -Rod Hill

July 2018 High Temperature Ties for Warmest All-Time

By Rod Hill on 01-Aug-18 10:04.

The official July climate report for PDX shows an average high temperature of 87.5 degrees, which ties the July of 1985 as the warmest all time.  The mean temperature was 74 degrees, which is the 2nd warmest on record.  The average low was 60.5, coming in as the 5th warmest in recorded history. 

Also breaking records was the 15, 90 degree days.  The total is the highest number of hot 90 degree days for any month at PDX. 

Total rainfall for the month came on July 2nd when .02" of rain fell, average for July is .65 inches.  The July of 1967 saw no rainfall, while several Julys have picked up only a trace of moisture. 

Outlooks from the National Weather Service continue to call for above normal temperature averages through September. 

Rod Hill

 

Heat Wave Likely to Hit Next Week

By Rod Hill on 11-Jun-18 08:58.

Portland will soon be getting into the heat.  Forecast models have been showing for weeks a very warm to hot back half of June.  Right now, 90 degree temperatures look likely next week Monday through at least Thursday and maybe Friday.  Although temps may not reach 100 degrees, humid conditions for such hot weather is expected. 

Above normal temperatues with several runs of 90 degree weather is expected over the next two weeks. PDX records show the most 90 degree plus days in the month of June happened back in 2015 when nine days warmed to 90 or better.   A typical June only warms to 90 degrees one to two times. 

The summer outlook from the National Weather Service continues to call for a hotter and drier than normal summer season.  The record for 90 degree hot days for a year stands at 29 days back in 2015.  It is interesting to note that the 4 hottest summers in terms of 90 degree days have occurred since 1987.  There seems to be plenty of data to support a recent warming trend of Portland summers getting hotter and hotter.  Last summer saw hot weather reaching 90 or better 24 days, including a sizzling August that saw eleven 90 degree days and went on to be the warmest August overall in the record book.  An average year features just 11-13 days reaching 90 degrees.

Meteorologist Rod Hill  (publish update June 14th, 2018)

 

Spring Outlook 2018

By Rod Hill on 20-Mar-18 07:47.

Spring begins with sunshine and 60 degree temperatures for the Rose City, but quickly turns wet and chilly with snow levels near 1,500 feet Thursday, Friday and Saturday. 

Despite the bumpy start, the Spring Outlook for the months of April, May and June looks promising for pleasant weather. Look for temperatures to average near normal to slightly below.  The bigger headline is the continuation of a below normal rainfall pattern.  Keep in mind, that normal spring precipitation for Portland is actually very pleasant with 2 out of 3 days typically being dry. 

You may recall March and April of 2017 dumped soaking rains that equaled nearly a foot of water.  The surplus moisture of more than 5.00" soaked the ground into mid-May.  If the outlook is correct, this spring of 2018 will see plenty of dry days to mow the lawn and enjoy the beauty of the Northwest. 

Meteorologist Rod Hill

 

Mild February, early spring possible

By Rod Hill on 03-Feb-18 17:45.

The outlook from the National Weather Service calls for above normal temperatures for Portland during the month of February.  The outlook for rainfall is less confident but leans toward drier than normal precipitation.  Forecast models also point towards warm and drier than normal weather through the first 20 days of the month. 

Don't forget the Oregon hedgehog saw no shadow, predicting an early spring!

Rod Hill

 

 

 

Total Lunar Eclipse

By Rod Hill on 29-Jan-18 14:25.

Triple treat for January’s second full moon

January’s second full moon will be a triple treat: it will be this month’s second full moon; the second perigee full moon; and best of all, there will be a total lunar eclipse! 

The ‘Super Blue Blood Moon’

The full Moon on January 31st will have its own special show, a total lunar eclipse! The full moon will slide through the dark shadow of the Earth, and for 76 minutes the only light hitting the Moon will be the reddish glow from Earth's sunrise and sunset, resulting in a total lunar eclipse. The totality begins at 4:51 a.m.  with the point of the greatest eclipse occurring at 5:29 a.m..  Astronomical Twilight begins at 5:51 a.m., thus the sky glow emerges above the eastern horizon.  This will diminish some of the redness of the totality on the moon, as well as low above the horizon..  The eclipse’s total phase will last for 76 minutes, ends at 6:07 a.m.. The Moon will be just 20 degrees above the eastern horizon at the instant of the greatest eclipse. Finally, the partial eclipse ends at 7:11a.m.  The sunrise from the east is at 7:33 a.m. followed by moonset in the west at 7:37 a.m. 

Unlike solar eclipses in which the Sun's rays can damage the eyes, lunar eclipses are safe to watch with the naked eye. Lunar eclipses are unique in that no one can predict what color the Moon will turn during totality. Binoculars and telescopes will enhance the view.

The combination of a perigee full moon (or super moon), a blue moon, and a total lunar eclipse is indeed a rarity: the last one occurred December 30, 1982 – not visible in North America.  For observers in Pacific Northwest, it is the first time all three of these phenomena will line up since March 31, 1866.

Information courtesy of Jim Todd - OMSI

Rod Hill's Winter Outlook 2017-2018

By Rod Hill on 25-Oct-17 20:20.

Like many forecasters that attempt long-range, seasonal forecast, I rely heavily on the projected Enso Cycle, which is a reference to projected water temperatures in the equatorial region of the Pacific Ocean.  A forecast for a period of NEUTRAL conditions, LA NINA or EL NINO plays a significant role in weather prediction.  NOAA's projection on October 17th, favors a 55-65% of a developing La Nina this Fall and Winter seasons. The outlook does leave the door open for present NEUTRAL conditions to continue.  

Other weather patterns I have examined for my prediction include winter's following hot summers in terms of 90 degree heat, years following 50" water seasons and winters following big snow seasons.  Last season's long list of big weather events has made my research for 2017-2018 my most difficult call, since I began seasonal outlook prediction back in 2001.  

Rod's Winter / Seasonal Outlook 2017-2018

 

  1.   Total Precipitation:  32 - 39"  /Odds favor by 67% a normal to below normal year.                           

        Would be 11-20" drier than last season.  Normal Water Year at PDX is 36 inches. 

  2.   Valley Temperatures:  1-3 degrees below normal  / Coldest months Dec. & Feb. 

  3.   Valley Snow:  No Confidence / data shows a 50% of a quiet year or a big season. 

        (My Hunch is that we slightly favor a quiet snow year with a trace to 2" of total snow)  

4.     Mt. Hood Snowpack:  A Great Season, 105% of Average or Higher!  

        Timberline 600-700" of total snowfall, Meadows at least 600", both amounts would better last year's 95% of normal  snowpack.

5.    Wind Storms:  No Reason to expect more than a few 50 mph gusts events

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My forecast accuracy for seasonal prediction dating back to 2001 is 66%.  Last winter I correctly predicted at least 5-6" of valley snow and called for a heightened chance of one big storm.  Although I called for an above normal water year, I did not see our 51" of moisture that came raining down. Industry standard for seasonal forecasting is closer to 55%.

Meteorologist Rod Hill

       

                                                         

        

 

 

       

                                                                             

        

 

Saturday Flooding Concerns

By Rod Hill on 20-Oct-17 10:40.

Forecast models show a long stretch of steady, heavy rainfall arriving Friday overnight and continuing into early Sunday morning.  New rainfall on top of what fell Thursday could equal 7" or more over the mountains (snow levels will rise back above 7,000 feet), 3-4" or more at the coast and at least 2.00" over Portland.  Some valley locations could see more than 3.00" of new rainfall over a 30-hour period!  

Intense rain rates with very heavy rainfall Saturday night will bring the greatest risk of street flooding, rising streams and increase the risk of landslides, especially in areas of the Gorge impacted by the Eagle Creek fire. 

Stay alert for possible high water.

Rod Hill

Mt. Hood First Snowfall

By Rod Hill on 19-Sep-17 09:46.

Mt. Hood picks up the first snowfall of the early fall season!  Timberline Lodge at 6,000' reports .27" of total moisture from Sunday night through Monday night.  Surface reports show 2-3" of wet snow on the ground.  Temperatures will hold near 32 degrees through Thursday morning, meaning new snow accumulations will be possible, but snow melt will likely occur as flakes try to stack up.  

(Below are resort observations Tuesday morning)

Mt. Hood Tuesday Morning

Snow levels near 5,000' through Wednesday night will mean all rain over HWY 26 and Government Camp.  Snowfall on the upper mountain will melt away this weekend as dry, warm weather returns.  Stay updated on my Mt. Hood Weather Page.

-Rod Hill

Hot back half of summer

By Rod Hill on 26-Aug-17 10:13.

Portland likely to see 90 degree heat this weekend with temps Sunday rising to near 100 degrees. As of Saturday morning, August 26th, PDX has hit 90 or better 15 days. With forecast models showing possible 90 degree heat through next Tuesday and again Labor Day weekend and another possible heat stretch around September 10th, the number of hot days may rise into the mid 20s, which would put the summer of 2017 on the list of hottest summers. Obviously, my projection of no more than 14 hot days (reaching 90 or better) is turning out to be way off! I simply did not see reason to expect what may be 12 sizzling days in the month of August. The most 90 degree days on record at PDX for August is 13 back in 1967. This month may challenge the record. Also, if Portland hits 90 or higher 25 times, this summer will be second to the hot year of 2015 when PDX hit 90, 29 times. Rod Hill