Rod's Weather Headlines

Right on cue, mother nature delivers a wild punch, within hours of the Autumnal Equinox at 1:44, Sunday afternoon. 

Here are a few storm headlines:

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Heaviest rainfall:

Astoria 1.22 inches

Seaside 1.22

Kelso .59

Portland metro:  .10 - .30 inches on average

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Peak Wind Gusts:

Garibaldi  64 mph

Newport   56 mph

I-205 at Division  42 mph

PDX  37 mph

Salem  39 mph

Mt. Hood 7,000 feet 63 mph

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The snow level will lower to near 6,000 feet tonight and Monday.  Timberline Lodge may wake up to snow on the parking lot Monday morning!

The Autumnal Equinox will kick-off the fall season this Sunday at 1:44 p.m. pdt.  A true "fall" cold front will arrive hours later, bringing possible high winds to the coast, steady rain to the valley and snow levels Sunday night lowering to Timberline Lodge!

Sunday's rainfall will put Portland over the top for September rainfall.  The monthly average is 1.47 inches.  To date, PDX has 1.45 inches in the rain bucket.  Outlooks from the National Weather Service call for above normal rainfall to continue through October.  The temperature outlook shows no confidence.  However, the 90 day outlook shows above normal temperatures for November and December. 

According to climate records, here is a guideline of what to expect in the coming weeks:

1.  First week of October, the normal high temperature drops into the 60s.  The normal low drops into       the mid 40s on Oct. 13th.

2.  The daily probability of rain goes from 30 percent to 40 percent October 9th.  Meaning, historically, 4 out of 10 days over the past 30 years have seen measurable moisture.  The rain chance increases to 50 percent of October 20th.  On average, November is now considered Portland's wettest month.

3.  October is the month that Portland begins to see more clouds than sunshine.  Depending on weather patterns, the north valley will not see more sunshine than clouds until next April, May or June. 

Tuesday's high of 91 degrees at PDX becomes the ninth day of 90 degree heat this summer.  Other Tuesday highs include:

Salem 92

Vancouver  91

Troutdale 95

Hillsboro 91

McMinnville 94

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Forecasting the return of cooler Pacific air is always tricky, but forecast models suggest 90 degree temperatures will be possible through Saturday.  Several record highs will be in jeopardy.  The PDX record high for Sept. 11th is 94 degrees and the record for this Thursday is 92 degrees.  Perhaps most impressive about our mini heatwave is that 3 or more 90 degree days in a row would become the longest hot streak of our summer season! 

The average number of September 90 degree days is two, but the most on record is 8 days, back in the summer of 1974.  The average number of 90 degree days for the year is 13.  You may recall the summer of 2009, when PDX set the all-time record with 24, 90 degree days.

Stay cool, drink plenty of water and take comfort in the fact that  the sunset starting Wednesday the 11th will be before 7:30, meaning longer nights will bring hours of time to cool off. 

The National Weather Service estimates 50,000 lightning strikes hit the Northwest during the storm event.  The amount of rain & lightning is unusual for September.  An upper low moving inland produced an unstable atmosphere and unleashed the rain and electric storm. 

These rain reports are from the National Weather Service through 5:00 a.m. Friday morning.  Additional amounts of .25" or more is possible in the east metro through noon today. 

Salem:  2.23"

Portland 1.03"

Kelso 1.80"

Scappoose 1.19"

Vancouver 1.10"

Hillsboro 1.16"

Beaverton 1.39"

Gresham 1.20"

Oregon City 1.49"

Tualatin 1.87"

Canby 1.65"

Aurora 1.65"

McMinnville .57"

Newberg 1.75"

Corvallis 1.84"

Aumsville 3.59"

Albany 4.34"

Sandy 1.37"

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Astoria .31"

Newport .65"

Hood River .16"

Daily totals can always be found on the Northwest Forecast Page. Click on the blue climate link on the desktop site and select your option. 

Although the Autumnal Equinox will not turn the calender to fall until September 22nd, what is considered meteorological summer ended August 31st.  The summer forecast for June, July and August turned out to be correct!  Last spring, I told you to expect a nice summer with drier than normal weather and no long stretches of extreme heat.  In fact, my prediction of less than normal 90 degree days is also true so far!

Here is the summer report card for June - August:

Average high temperature:  80 degrees - one degree above normal

Average low temperature:  58 degrees - one degree above normal

Rainfall:  2.13 inches - below normal by .89 inches

Thunderstorms in the metro area:  3 days (not counting last night)

Number of 90 degree days:  8 (normal through October is 13 days)

Hottest temperature:  97 degrees, June 30th

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High humidity as been the story of our summer weather.  The average relative humidity for August was 63 percent, compared to 58 percent back in August of 2012.  The humid air has been brought by several long stretches of a southwest flow pattern aloft with a weak low pressure trough over the area, centered offshore.

Back in June, I wrote an article stating that Portland would likely see fewer than normal 90 degree days this summer.  The forecast was based on historical data showing less than the average of 13, 90 degree days, when PDX did not reach 90 until after June 10th.  This year's first 90 degree day was June 28th.  To date, the warmest temperatures this summer has been 97 degrees on June 30th.  The airport has recorded seven, 90 degree days so far this summer. 

Current forecast models show no chance of 90 degree heat through August 31st.  At this time, there are no signs of a hot September.  The latest date to see 90 degrees in Portland, was October 5th back in 1980.  While it is true that record highs during September are mostly 90 or higher, the record number of 90 degree days for any one September is 8 back in 1974.  The average number of 90 degree September days is two. 

Based on current data, it is unlikely that PDX will see more than 4 additional 90 degree days, which would give the summer of 2013 a total of 11 days, which would be two days below normal.  I hope you are enjoying our pleasant summer weather!

Clear skies Sunday night and Monday will bring three chances to view the International Space Station as it passes overhead.  The space station should be easy to spot.  You will be looking for what looks to be a commercial jet like feature, only higher in the sky.  If you go outside at the times listed below, you should see the flight!

Sunday evening:  10:48 p.m.  The station will move west/southwest to the southeast at 90 degrees in the sky.

Monday morning:  3:40 a.m.  Moving west/northwest to the southeastern sky at 87 degrees.

Monday evening:  10:00 p.m.  Appearing in the southwestern sky, moving to the east at 57 degrees.

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The station will be in orbit at 240 miles above Earth, flying at a speed of 17,500 mph!  The space station is as big as a football field and has a brightness equal to the planet Venus.  Each flight viewing will be visible for roughly 7 minutes.

The month of July ends at PDX with simply a trace of rain.  The lack of moisture becomes one of many years to see just a trace of July rainfall.  The year 1967 holds the dry July record with 0.00 inches.  Here is a list of other July reporting sites:

Downtown Portland (KGW):   0.00 inches ties for the driest

Vancouver:  0.00 inches ties for the driest

Hillsboro:  Trace ties for 2nd driest

McMinnville:  Trace ties for 2nd driest

Salem:  0.00 inches ties for driest

Eugene:  0.00 inches ties for driest

Astoria:  0.03 inches ties for 2nd driest

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You may recall that August 2012 saw only a trace of rain at PDX.  We are clearly in the middle of our dry season.  Current forecast outlooks call for above normal temperatures during the month of August.  July averaged less than a degree above normal for the month.  Outlooks also call for below normal rainfall to continue.  In fact our drier than normal weather pattern may continue through September. 

To date, PDX has had 6 days reach 90 degrees or warmer,  which is normal to date.  The season average is 13 days with 90 degree heat through September.  

90 degree temperatures are in the forecast for the first time this year.  Weather charts show hot weather this coming Sunday, Monday & Tuesday.  As July approaches, it should come as no surprise that hot weather is in the 7day forecast.  Portland averages 13 days each year of 90 degree temperatures and hotter.  Here is a list of the first 90 degree days over the past 10 years:

Year      1st 90 degree day      Number of 90 degree days all year

2003           June   4                                22 days

2004           June 17                               12 days

2005            May 27                                15 days

2006            May 15                                21 days

2007            May 30                                  9 days

2008            May 16                                15 days

2009            June  3                                 24 days  (all time record)

2010            July   7                                 11 days

2011            Aug.  20                                 7 days

2012            Aug.   4                                 11 days

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CONCLUSION - WHAT TO EXPECT THIS SUMMER:

Notice that all years above the average number of 13, 90 degree days had their first hot day before June 10th.  If this summer follows the pattern of the last 10 years, PDX will likely see 12 or less 90 degree or hotter days this summer.

We lucked out and got to see little bit of the "Supermoon" last evening.  The peak viewing will be tonight when the full moon rises at 9:16 p.m.  But, as you likely know, solid cloud cover is expected to cover the show.  Here is all you would ever want to know about what appears to be the largest moon of the year, courtesty of Jim Todd, OMSI Director of Space Science Education:

June's full moon takes place at 4:32 a.m. PDT on Sunday, June 23  It is called the Strawberry Moon; but it can also be called the Rose Moon or Honey Moon. When we look at the full moon on Sunday, it will be just 221, 824 miles away making it the Moon's closest approach to Earth in 2013.
 
Full moons vary in size because of the elliptical (oval) shape of the Moon's orbit. Perigee, or the Moon's closest approach Moon to Earth is about 31,068 miles closer to Earth than the its apogee or farthest distance. The Moon's distance at perigee changes by 3% over a period of 18.6 years, but in general while at perigee, a full moon would appear about 14% bigger and 30% brighter than a corresponding full moon at apogee, but it's not really all that much more dramatic than a regular full moon.
 
In March 2011, the full moon was less than one hour away from perigee, a near-perfect coincidence that happens about every 18.6 years.  On May 2012, the full moon was a minute of reaching actual perigee position.  The point of the moon’s full phase at 4:32 am PDT in June 2013, and perigee at 4:09 am PDT, fall within an hour of each other.  On August 2014, the full moon and perigee will be just 3 miles closer to Earth.
 
Before 2011, the comparable biggest/closest full Moon was March of 1993, and presumably the next comparably large full Moon will be 18.6 years from then sometime in late 2029.
 
Many are calling this full moon the "Supermoon," blaming it for dramatic land and ocean tides which trigger earthquakes. The tides are greatest during full and new moons, when the sun and moon are aligned either on the same or opposite sides of the Earth.  A very small correlation exists between full or new moons and seismic activity, because the stronger tidal forces caused by the alignment of the sun and moon puts added stress on tectonic plates. However, seismologists have found no evidence connecting lunar perigees to heightened seismic activity. Instead, the Earth constantly stores up energy and releases it any time the built-up energy becomes too great.