Tuesday, October 18, 2011

Heat Surge

Today is going to be a MUCH warmer day than yesterday and far warmer than the National Weather Service is forecasting.   The NWS is going for 66 at Seattle---mid 60s are their forecast for the Puget Sound region and they are going 67-69 on the eastside.   Folks...I am convinced we are going to see 70s today at many locations away from cool water and mid-70s at some spots on the eastside.

Compare the temperatures aloft of today versus previous days from the Seattle profiler at 6 AM. HUGE warming above 400 meters--we are talking 10C (18F)--warmer at 600 meters.  Yesterday hit 61F at Sea-Tac:  you do the math (no, it probably won't get as high as 79F--but it will surge)

There is a thin veneer of cool air near the surface, chilled by infrared cooling to space under nearly clear skies. Above that cool air there is a strong inversion in which temperature warms with height.

Easterly flow aloft has really started cranking up as shown by the profiler winds and temperatures shown in this figure (y axis is height in meters, x axis is time in GMT--later to the left):
 20 knot easterly winds above 400 meters!

Here is the pattern of surface (2-meter) temperatures from our super-high resolution numerical weather prediction model for 2 PM today, clearly showing some 70s near Seattle and lots of 70s to the southwest:
But most important, there is probcast....our ensemble-based statistical forecasting tool that is very good in warm-up situations--it is showing mid 70s on the eastside and torrid conditions in the Willamette Valley.


 The only subtleties to this forecast is how high the air will mix vertically under the modest sun of this time of the year and how well the easterlies will mix downward.  In the summer, when the sun is strong, this would be an easy forecast.

Well, it is going to be fun (and very pleasant) to watch the day evolve....I am betting that many of you will experience 70s today.  If all of you stay in the mid-60s, it will be back to the drawing board for me.

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