Wednesday, June 3, 2009

Heat Wave

Yesterday (Tuesday) got to 88F at Seattle and today should be very similar. There is one more day of the hot stuff (tomorrow could hit 90F) and then the marine air will move in for cooler temps on Friday and the weekend.

Lets talk about some subleties of the heat. An essential ingredient is the thermal trough (see sea level pressure forecast at 2 PM). If you look closely you will see a tongue of lower pressure extending into western Washington. Also note the low-level winds..they are from the east. Easterly wind bring warm continental air into the lowlands as well as warming due to sinking along the western Cascade slopes.
The profiler gives winds and temperature above Seattle (see graphic). You see easterly flow aloft and near the surface early in the day. Mid-day,northwesterlies and northerlies come in..that is the Sound breeze, essentially a large region sea breeze. Without the Sound breeze, we would be much warmer...like Portland...so you can look at it as our natural air conditioning. By 9 PM the Sound breeze weakens. That is why you should do your kite flying early in the evening...wait too long and the wind dies.

One of the most interesting things the last few days has been the clouds and rain to our south over Oregon and northern CA. The satellite picture below show the clouds over these regions. The origin? A low center off the California coast that has remained quasi-stationary. An interesting aspect of this pattern is that we have been warmer than much of California (see plot of max temps). The whole pattern should shift late tomorrow...with the thermal trough jumping into eastern WA and marine air starting to move in Friday AM.

8 comments:

Sinfonian said...

I have been talking about the AHS heat scale that says we get less than 7 days of 86 degree weather a year. This year we may actually hit that. I don't recall it being this hot this early in the year in my 37 years living here. Wierd stuff. My lettuce wilted in June! Insane.

TrickyCoolJ said...

I traveled to Sacramento yesterday for work and it was indeed cloudy and cool down there. Absolutely mind boggling that I was trying to figure out how to stay cool in my suit because it would be hotter in Seattle when I returned at 5:30pm! I do like the warm weather, it's just a drag to try and get to sleep on a work night without AC.

Script Maven said...

@Sinfonian: I recall a heat wave over the first week of June back in 2000. My ex-wife was in late pregnancy and quite miserable.

WeatherNerd said...

Last year on May 17th it was 84 and on May 18th it was 90, both dates for Seattle. Surely it was warmer away from the water on those dates. So it hasn't been a long time since we had a heat wave this time of the year. Also, last April 12th it was 79 only to have lowland snow the following weekend--now THAT was strange.

mainstreeter said...

South of Portland




SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE PORTLAND OR
431 PM PDT THU JUN 4 2009


MARION OR-CLACKAMAS OR-LINCOLN OR-MULTNOMAH OR-BENTON OR-TILLAMOOK
OR-WASHINGTON OR-POLK OR-YAMHILL OR-
431 PM PDT THU JUN 4 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 500 PM PDT
FOR YAMHILL...POLK...SOUTHEASTERN WASHINGTON...SOUTH CENTRAL
TILLAMOOK...EXTREME NORTHWESTERN BENTON...EXTREME SOUTHWESTERN
MULTNOMAH...NORTHEASTERN LINCOLN...WESTERN CLACKAMAS AND NORTHWESTERN
MARION COUNTIES...

AT 424 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING
DESTRUCTIVE WINDS IN EXCESS OF 70 MPH. THESE STORMS WERE LOCATED
ALONG A LINE EXTENDING FROM MOLALLA TO WHEATLAND TO 15 MILES
SOUTHWEST OF DALLAS...MOVING NORTHWEST AT 25 MPH. THE OUTFLOW WINDS
HAVE
INTENSIFIED OVER THE WILLAMETTE VALLEY AS THE LINE APPROACHES
UNIONVALE...ST PAUL AND MCMINNVILLE.

SEVERE THUNDERSTORMS WILL BE NEAR...
MULINO...UNIONVALE AND HUBBARD...
WHITESON...BUELL...AURORA AND AMITY...
CANBY...ST. PAUL...DONALD AND BARLOW...
WILLAMINA...SHERIDAN...MCMINNVILLE AND LAFAYETTE...
WEST LINN...WILSONVILLE...NEWBERG AND GRANDE RONDE...
CARLTON...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DOPPLER RADAR HAS INDICATED SOME WEAK ROTATION WITHIN THIS STORM.
WHILE NOT IMMEDIATELY LIKELY...A TORNADO MAY STILL DEVELOP. IF A
TORNADO IS SPOTTED...ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A
STURDY STRUCTURE...SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

Joseph Ratliff said...

From wunderground.com at 752pm...

Nowcast as of 7:43 PM PDT on June 4, 2009

Now
Strong gusty south to southeast winds 40 to 55 mph will briefly affect southwest Washington from Olympia eastward to the Puyallup- Orting area.

These winds are a gust front produced by a cluster of thunderstorms that developed south of Lewis County. A weather spotter reported a gust to 54 mph in Yelm around 730 PM. An earlier report from Winlock estimated the gusts around 50 mph.

mainstreeter said...

They haven't revised the forecast for any severe weather for the South Sound but the wind is picking up from the SE and gusting to around 20 so far.

mainstreeter said...

ah, so they have. Thx Joseph