Rod's Weather Headlines

WINTER OUTLOOK 2016-2017

By Rod Hill on 2016-10-04

Before I announce my projection for the winter of 2016-2017, here is a quick word as to where we are coming from.  Last winter was as expected, a strong El Nino pattern that produced a healthy snowpack on Mt. Hood, much above normal rainfall for the Willamette Valley in terms of the water year dating back to October 1st and ending Sept. 30th and above normal temperatures overall.  Below are a few headlines for the water year:  

1.  Mt. Hood Test Site Snow Ending April 30th:  90" depth, 41.7" of water storage for 67% of normal.

2.  Portland (PDX) Total Water Year Precipitation Oct. 1st - Sept. 30th: 47.02" / 10.99" above normal

3.  Portland Season Snowfall:  1.3"

4.  Highest Wind Gust (PDX)  SW G 55 mph, December 21, 2015

5.  Portland Temperature average:  2.5 degrees above normal mean temperatures.

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The strong El Nino of last winter weakened during the spring and Enso Neutral Conditions are in place.  NOAA projects a 55-60% of Neutral conditions holding through the winter of 2016-2017.  My forecast projection work is based on data sets showing Neutral condtions, dating back to 1950.  I further examined Neutral seasons following a strong El Nino winter.  My outlook is based on averages of the above mentioned data sets. 

Here is my Winter Forecast for the Portland Metro Valley & Vancouver:  

1. Temperatures likely to be near normal or above by no more than 2.0 degrees.

2.  Rainfall: While a dry season is possible, odds favor rain totals near 37.90" / 1.87" above normal.  November and December are likely to combine for a wet start to the rainy season. 

3.  Valley Snowfall:  At least 1 or 2 mini-snow events dumping 3-6" of total snowfall are likely.

Also, I see an elevated chance to see an 8-12" snow event.  The historical average for this winter's pattern is 6" of total season snowfall.  However, odds are equal of seeing a big snow event as to seeing less than 3.00" for the year.  The December snow of 2008 that dumped 19" and the winter of 2003-2004 that produced 12.6" are in the data set. 

4.  Windstorms:  Odds are heightened for valley windstorms with south wind gusts reaching 50 mph or higher. The majority of Willamette Valley windstorms happen in Neutral and El Nino years.  Most recently, Neutral years brought the windstorms of December 2014, when PDX had a 67 mph wind gust, the highest since 1981 and the storm of December 2006, which had a blow of 80 mph in Salem and 70 in downtown Portland, but 53 at PDX.

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Perhaps most important to many is the Mt. Hood Snow Outlook.  My snow records for Mt Hood only go back to 2000.  Of these years, I found 8 seasons in the data set matching this up-coming winter scenario and 6 of the years had solid snowpacks!  The projected snowpack for this up-coming winter is 72% of average, which would be slightly higher than last winter.  I do want to point out that the 2 bad seasons I looked at include the record low snowpack season of 2014-2015.  In otherwords, there is reason to be cautious with the snow projection, but the best bet calls for a solid year with Timberline seeing more than 500" of total snowfall and Meadows more than 400 inches - both would be considered near normal.  Also, odds favor a good start to the season with a decent snowpack build during the month of December.

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My Seasonal Foreast track record dates back to 2001 and has a 67% accuracy rate, including my 2016 summer prediction of 16 total 90 degrees at PDX. The airport hit 90 degrees, 14 times this past summer.  

Industry standards for seasonal prediction is considered to be less than 50% for precipitation and 55% for temperature outlooks. 

-Rod Hill

 

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Portland Hot Weekend Sets Records

By Rod Hill on 2016-06-06

Portland's (PDX) hot weekend sets records both days for warm low temperatures and hot afternoons.  Below are the new records: 

Saturday:  Record high - low temperature of 63 degrees.  The afternoon high was 98 degrees. 

Sunday:  Record high - low temperature of 66 degrees.  The afternoon high was 100 degrees!

At PDX, June 5th becomes the 2nd earliest to reach 100 degrees.  May 28th, back in 1983 also warmed to the century mark.  Assuming the Rose City warms to 90 or hotter on Monday, June 6th, the total for the year and month will be 3 days.  At this point, I stand behind my summer outlook calling for 16 - 90 degree days this year.  Forecast models do not show any hot weather between June 7th and the 22nd.  It is possible that we will not see any additional 90 degree heat this month.  

Rod Hill

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Mercury to pass in front of the sun!

By Rod Hill on 2016-05-09

Mercury Transit Viewing at OMSI

A rare celestial event called a transit of Mercury is set to transpire on Monday, May 9,2016. The Oregon Museum of Science and Industry (OMSI) and the Rose City Astronomers Club will host a transit of Mercury viewing party in OMSI’s east parking lot for this occurrence, not to be repeated until the year 2019! 

A transit of Mercury is the observed passage of the planet Mercury across the disk of the sun.  It occurs when Mercury, orbiting the sun “on the inside track,” catches up to and passes the slower Earth.  To viewers, Mercury will appear as a small dot in the foreground, making its passage (or “transit”) from left to right across the southern hemisphere of the sun.

Transits of Mercury with respect to Earth are much more frequent than transits of Venus, with about 13 or 14 per century, in part because Mercury is closer to the Sun and orbits it more rapidly.

For Portland, the transit will commence at 5:46 a.m. with the sunrise and Mercury appears near the Sun's equator.  The greatest transit movement will occur at 7:13 a.m. when Mercury appears just below the equator of the sun. The transit will end at 11:13 a.m. as Mercury exits to the lower west of the sun. Filtered solar telescopes will be available for safely viewing the sun during this transit.

It is important not to view any of this transit activity without eye protection or without using indirect viewing techniques.  Viewers should use only an approved solar filter which blocks dangerous ultraviolet and infrared radiation as well as visible light.  Special solar viewing glasses are available at the OMSI Science Store.

(The above is courtesy of Jim Todd - OMSI)

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2016 Warmest April on Record at PDX

By Rod Hill on 2016-05-02

It may come as little surprise, that PDX set the all - time record for being the warmest April!  Records go back to October of 1940.  The month set 7 individual temperature records for warm air & now holds the record in all three monthly temperature averages for April.  Here at the numbers:

1.  Warmest average high temp:  68.5 degrees (above normal by 7.1 degrees)

2.  Warmest average low temp:  47.0 degrees (above normal by 3.9 degrees)

3.  Warmest mean temp:  57.8 degrees (abvove normal by 5.5 degrees)

The previous warmest April was 2004. 

Rod Hill

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Rod's Summer Outlook 2016

By Rod Hill on 2016-04-14

After the sizzling summer of 2015, you may be wondering if this summer will be just as hot!  Last year set the all-time record with 29 days reaching 90 degrees or warmer.  The climate average is 11 days. In doing my research, I found that 5 of the 6 warmest summers in terms of 90 degree days were summer months leading into an El Nino pattern.  This summer we will be leaving El Nino and heading toward either a neutral fall or a developing La Nina. 

I further found that overwhelmingly, Portland's coldest and wettest summer months were tied to existing or developing La Nina patterns.  It seems the current weakening El Nino leading into a weak, nearly neutral fall Enso pattern leaves the Northwest with no reason to expect extreme heat or cold as we head into summer. 

Another topic I looked into is the apparent short-term rise of Portland's summer season temperature average.  The number of 90 degree days according the climate average is 11, however, if you run the average since the year 2000, the average number of 90 degrees days is 14 and the average of hot days increases to 16 over the past 10 summer seasons.

The one part of my research that has me perplexed is the summer of 1983, following one of the strongest El Nino winters on record.  That summer of '83 went on to only see three, 90 degree days due to wet weather in June, July and August!  Throwing out 1983, my projection for 90 degree days is a range between 11 and 22 days and my rainfall projection is near normal.

I hope you found the above to be an interesting read.  Below is my 2016 Summer Outlook for Portland:  

1.  TEMPERATURE:  ABOVE NORMAL WITH 16, 90-DEGREE DAYS EXPECTED.

 (The number would be roughly 1/2 of the record summer of 2015)

2.  RAINFALL:  NEAR NORMAL

(June could be near 2.00", but July likely an inch or less and August, likely an inch or less)

The headline of my Summer Outlook is the strong confidence of seeing less than 20, 90-degree days, meaning much cooler weather than one year ago!  While my research found signs supporting a cool-wet summer, the evidence of past years highly supports a sunny Northwest summer without the intense heat of one year ago. 

The National Weather Service currently projects dry and warm weather through the month of June.  I feel Portland has a 50-50% chance of seeing near normal rainfall during May and June. Remember, my projection for a dry April, ending the soaking El Nino rains seems to be correct so far!  My seasonal forecast accuracy going back to 2001 is 65%.  My projection of last winter seeing a good snowpack on Mt. Hood and a good water year for Portland was correct. 

Rod Hill

 

 

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Record high temps at PDX likely this week

By Rod Hill on 2016-04-04

Last Wednesday saw Portland reach 70 degrees for the first time this year.  The high of 74 degrees kicked-off a run of 70 degree warmth that lasted five days!  A similar, but warmer stretch of weather returns this Wednesday.  The Rose City is forecast to hit 80 degrees  Wednesday,  82 Thursday and hold in the 70s through the weekend.  If true, record highs at PDX would be set Wednesday through Friday!  Portland's first 80 degree temperature one year ago, came on the 20th day of April.

Rod Hill

 

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Soaking El Nino Rain to End in April

By Rod Hill on 2016-03-28

Multiple reasons to project a drier than normal April and an end to soaking El Nino rains that produced the wettest winter on record at PDX!

The strong El Nino is weakening and all previous El Ninos of near similar strength saw wet winter months produce above normal rainfall in March but not in April.  Both the wet El Ninos of 1982-1983 and 1997-1998 fizzled during April and saw a return to more normal Northwest weather.

 My projection for April  is 2.25 inches of total rainfall for a month that averages 2.73 inches. 

As of March 28th, the Water Year total at PDX, dating back to October 1st is:  39.48 inches, a surplus of 13.56 inches! Portland's average rainfall for the entire water season, ending September 30th is 36.03.   If PDX did not pick up another drop of rain through this summer, the Water Year would still finish above normal.

Rod Hill

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Sunday Winds From The Coast To The Valley - Likely

By Rod Hill on 2016-03-12

HIGH WIND WARNING SUNDAY 8:00 A.M. - 8:00 PM FOR THE COAST.

A WIND ADVISORY FOR THE VALLEY 12 NOON - 10:00 PM.  AREAS FROM EUGENE TO LONGVIEW WILL SEE GUSTY HIGH WINDS. PEAK SOUTH AND THEN WEST WINDS COULD REACH 45-55 MPH. CONFIDENCE IS HIGH OF SEEING AT LEAST 50 MPH WINDS IN THE METRO.

Sunday winds will likely be at least as strong as the storm March 1st, that produced multiple area wind gusts of 50 mph.  

The map shows possible high wind areas colored in brown, including all areas from the coast to the Cascade foothill. Remember, it is dangerous to drive near tall trees during a windstorm. At least 2 people in our region have been killed this winter when trees fell onto their cars. Stay safe and updated as the wind blows.  PortlandWeather.com & iPhone app & mobile for android:  PortlandWeather.com/mobile

Portland Weather's photo.

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Outlook calls for warm temperatures

By Rod Hill on 2016-02-17

 
Below is a letter I shared wth Mt. Hood Meadows Ski Resort, regarding my outlook through the end of April:
 
 Although the mountain should pick up decent snow Wednesday night, Thursday and Friday, hopefully well over a foot, there are signs that February may struggle to reach normal precipitation totals.  With that said, the previous two strong El Nino seasons both had above normal moisture January, February and March!  Interesting enough, both years also had a dry April. 
 
My thought remains that the mountain is transitioning into 50% rainy days and 50% snowy days as the overall temperature pattern is now rising.  Consider that Mt. Hood Meadows at base elevation has picked up 54” of total snow fall over the past 10 days, but the base amount on the ground has declined from 108” to 93 inches.  In other words, lots of new snow, but even more melting.  
 
As long as March continues to see a good snow event with snow levels down to 4,000 feet, each week to 10 days, the overall base and skiing will likely be in good shape.  But I do believe the temperature table is turning to the warm side. 
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As for Portland, warm temps are an easy forecast outlook to predict.  I also believe a wet March is a good bet, but will stick with a below normal rain total in April.
 
(My latest forecast for the Mt. Hood)
 
Rod Hill

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January rainfall adds to the Water Year surplus

By Rod Hill on 2016-02-01

Rainfall at PDX is 7.10" for the month of January.  Normal for the month is 4.88 inches.  The wet month gives Portland 30.52" of rainfall since the Water Year began back on October 1st.  The surplus of water is 11.56 inches!  

The Rose City needs only 5.51" of moisture through September to reach the normal annual precip total of 36.03 inches.  (The Water Year runs Oct. 1st - Sept. 30th.) Another way to describe our rain surplus is to say, if PDX did not see a drop of rain until mid-May, we would still be on track for the year!  With a wet outlook through March, we may very well reach 36.03" of water for the season this February or March at the latest.  

The snowpack continues to be in good shape. Roughly one year ago, Timberline had 175" for the year. Today, the resort reports a season total of 343 inches. 

Rod Hill

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