Monday, September 1, 2014

A Summer for the Record Books

The National Weather Service has released the latest climate statistics for August, and the combined July/August temperatures are really amazing.

Seattle had its warmest July/August on record.

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE SEATTLE WA
500 AM PDT TUE SEP 2 2014

..WARMEST JULY AND AUGUST ON RECORD IN SEATTLE...
..SECOND YEAR IN A ROW WITH A WARM MIDDLE OF THE SUMMER...

THE AVERAGE TEMPERATURE FOR JULY 1ST THROUGH AUGUST 31ST THIS YEAR 
IN SEATTLE WAS 69.2 DEGREES. THIS IS THE WARMEST AVERAGE TEMPERATURE 
FOR THIS TWO MONTH PERIOD ON RECORD BREAKING THE OLD RECORD OF 68.8 
DEGREES SET IN 1967.

This is also true at Spokane, Wenatchee, and Lewiston

Here are the numbers from the NWS.

SITE: SPOKANE (RECORDS BEGAN 1881)
JULY/AUGUST AVERAGE TEMP    YEAR    RANK
74.0                        2014    1
73.5                        1998    2
73.3                        1958    3
73.1                        2013    4
72.9                        1930    5
SITE: LEWISTON (RECORDS BEGAN 1881)
JULY/AUGUST AVERAGE TEMP    YEAR    RANK
78.5                        2014    1 (TIED)
78.5                        1939    1
78.1                        1898    3
77.9                        2013    4
77.7                        1906    5
SITE: WENATCHEE AIRPORT (RECORDS BEGAN 1959)
JULY/AUGUST AVERAGE TEMP    YEAR    RANK
78.9                        2014    1
77.8                        1961    2
77.3                        1998    3
77.0                        1967    4

76.7                        1971    5

 Olympia had their second warmest July/Augusts on record.

The record-loving folks among you will now turn to the official summer season ending on September 21st.  We are going to warm up later this week, so we have a shot at it.  Stay tuned.

Sunday, August 31, 2014

Major Precipitation Contrast and Holiday Forecast

Saturday was a day of real precipitation contrasts as the first fall weather system moved through.  Here are the totals for the 24-h ending 9:15 AM on Sunday. The red boxes were over 2 inches, yellow 1.5-2, dark green 1-1.5. In contrast, only a few hundredths fell over Northwest Washington, the eastern slopes of the Cascades, and over SW Washington and the north Washington coast.


The reason for this contrast?  A narrow zone of precipitation associated with yesterday's disturbance, enhancement on the western slopes of the Cascades, and a weak convergence zone over central and southern Puget Sound.

And the Camano Island radar broke as well for virtually all day Saturday.  You feel naked as a meteorologist without your radar!  Fortunately, the new Langley Hill coastal radar provided a lot of information about the approaching system, such as the image at 5 AM Saturday that showed the limited region of moderate precipitation moving our way (see image).

The good news is that the Camano Is. radar is repaired (our colleagues at the NWS are on the job 365-24-7) and the regional radar image this morning shows a relatively dry pattern, except for some showers on the windward (western) side of the Cascades.


This showers should fade during the afternoon, but a hike on the western slopes today might be drizzly and cloudy.  Head to the eastern slopes.

A weak disturbance is now approaching us and could bring some clouds and showers to the northern portion of Washington tonight. The infrared satellite pic at 9:30 AM shows it offshore.


But today should be decent for most of you, with highs getting to around 70 or a bit above, with partly cloudy skies away from the western slopes.

Monday looks quite good, particularly over the interior and mountains.  Eastern WA will be warm.  Go hiking, hit Bumbershoot, or paint your fence.

A much stronger disturbance will come in Monday night and Tuesday, but the action will not reach the interior during the day Monday.  So Tuesday will see clouds and rain...but you have work or school anyway, right?





Thursday, August 28, 2014

The Sign of Fall

After a beautiful summer, with warmth and relatively dry conditions from mid-July to mid-August, a reminder that we are living in the Northwest often comes in late August:  the first passage of the first fall-like system, usually a weak frontal passage.  And just on schedule, one is now approaching us.   As proof here is an infrared satellite image for 9:15 PM, Thursday.


You can see the frontal cloud band stretching from the central Pacific into British Columbia, with the swirl of a low pressure center off of SE Alaska.   A visible satellite view of the frontal cloud band at 5 PM is shown below. Looks impressive!

The fact that the clouds are quite white in the infrared suggests the cloud tops of the band are fairly cold and high.  Our coastal radar at Langley Hill, near Hoquiam, clearly delineated the rain within the front (at around 5 AM on Friday).


The latest forecast models suggest this band will spread over us Friday afternoon and Saturday.   So Saturday should be the worst day of the holiday weekend.

Here is the forecast 24-h precipitation ending 5 AM on Saturday.  Avoid British Columbia...that is where most of the rain will be.  Washington and Oregon are generally dry except for some light showers on the windward slopes of the Cascades.  True Northwesterners laugh at such light precipitation.   But temperatures on Friday won't get much above 70F.


The next 24-h (ending 5 AM on Saturday) will be wetter, particularly over western Washington.  But cross the Cascades and you will be out of it and most of Oregon should be dry, except its far NW corner.

For the 24h ending Monday at 5 AM, precipitation is mainly limited to BC and NW Washington.  Again, heading to eastern WA or Oregon is the ticket to a dry outing.  A Vancouver or Whistler trip could be wet, although a stop for dim sum in Richmond, BC. always good.  Most of the rain comes in late Sunday and


thus most of the day will be dry. That is illustrated by the 3-h precipitation forecast ending 2 PM on Sunday. So Sunday is better than Saturday for most of western WA.

Monday will have light showers over western WA.  Here is the forecast precipitation for the 3-h ending 2 PM.

So to reiterate my advice for enjoying dry outdoor activities this weekend:

Head to eastern WA or all of Oregon (except the far NW coast).
Sunday afternoon looks like a gap between weak systems.
Take your Gore-tex garments out of deep storage.

Tuesday, August 26, 2014

The Hazy Pacific Northwest

More than one person has commented to me about about how hazy the skies have been lately.  In contrast, early in the summer, the skies were often starkly blue with the mountains sharply silhouetted on the horizon.

Want to see the difference between early July and now?  Look at these samples from the Puget Sound Clean Air Agency visibility cameras, one from July 7th and the other from yesterday morning:


The reason for the loss of visibility?

Smoke from wildfires all around us.  There are many fires in British Columbia to our north (see map)

And lots of fires over Washington, Oregon,  Idaho, and California (see image)

So if the winds are from North to East to South, smoky air is moving over us.  During the past few days we have gotten smoke from British Columbia fires, smoke that first moved west and then south.   Here is the MODIS satellite imagine on Monday...can you see the smoke over the interior of BC that is moving towards the coast?


We can run a trajectory calculation (Hysplit) to see where the air over us Monday night came from (see graphic)...yep...from coastal British Columbia.

The wildfire smoke has caused the air quality in a number of Northwest locations to decline to moderate.  Here is an example from Seattle...Queen Anne Hill.


This is not the only summer we have experienced worsening visibility from regional wildfires and won't be the last.

Sunday, August 24, 2014

Yakima and and Central/Southern WA Cascades Gets Hit by Thunderstorms

This is really getting to be an amazing year for thunderstorms over the Cascades and the eastern Cascade slopes.   It just doesn't stop!

Today's storms were focused from Yakima into the central and southern Washington Cascades.  The 24-h rainfall ending 7:30 PM Sunday is shown below: 1/2 inch in Yakima, with as much as .80 inches near Snoqualmie Pass and .5-1 inch over the eastern slopes of the northern Oregon Cascades.

Rain gauges can, of course, miss some significant rain features, particularly from thunderstorms.  Here are the "storm totals"--mainly for this afternoon-- from the Pendleton, Oregon radar.  In limited areas along the eastern slopes of the WA Cascades there was 1-2 inches.



The National Weather Service had a flood warming out this afternoon for the Yakima area and there was some localized flooding over roadways.  Here is a report from a NWS spotter near Tampico (east of Yakima, see map below).  The spotter estimated 2 inches of rain (consistent with radar) and water running over Ahtanum Rd.

Date:08/24/2014
Time:0340 PM
Event:HEAVY RAIN
Magnitude:E2.00 INCH
Location:2 E TAMPICO
County:YAKIMA
State:WA
Source:TRAINED SPOTTER
Remarks:ESTIMATED 2.0 INCHES OF RAIN. WATER 4 INCHES DEEP RUNNING DOWN 1 LANE OF AHTANUM ROAD



A storm-total precipitation map from the Portland radar shows the Yakima precipitation and the heavy rainfall south of Hood River.


The thunderstorms today brought lots of lightning...here is the lightning strike map for the 24h ending 9 PM Sunday.  Lots of lightning over the central and southern WA Cascades, as well as eastern Oregon. Some new fires have been reported.


For example, one small fire started near Selah, Washington, but was quickly extinguished (see picture)

Picture courtesy of MASON TRINCA/Yakima Herald-Republic

It looks like the lightning and thunderstorms will take a break for a few days, staring tomorrow (Monday)