Thursday, January 8, 2009

Inauguration Weather Forecast Update: Trending Colder

Today's extended outlook for the 8-14 day interval including Inauguration Day reverses a slight recent trend toward more seasonable temperatures. For the week Jan. 18-22, the predicted area of below-average temperatures has expanded to cover nearly the entire U.S. east of the Mississippi. Northern Virginia, the District of Columbia, and Maryland are now in the southern portion of an area with 50% or greater probability for temperatures below the climatological average.

For precipitation, chances are still 40%+ for below-average amounts.

Following up on yesterday's discussion of model limitations, this morning's 12-day model forecast for 7 am on January 20 shows a stunningly severe cold wave extending as far south as the Gulf Coast and northern Florida, along with frozen precipitation over much of the East Coast. This is a dramatic change from the much less intense cold outbreak and generally dry conditions over the Mid Atlantic area in the forecast from data collected just 24 hours earlier.

As far as the model forecasts for the specific day are concerned, Climate Capitalists should humbly recall the immortal words of the late Louis Rukeyser, "At least some of them will be wrong." See the excellent comments by site visitor SteveT on why even the average range of model predictability is likely to be too optimistic in this case.

Today's temperatures (final):
High 42
Low 30
Departure from average: +1
Month to date: +1.4

Today trace
Month to date 1.78"
Departure from average +0.96"
Days with measurable accumulation: 2
Note: Yesterday's 1.26" of rain was just 0.07" short of the record for the date set in 1908.

Click here for all Inauguration Weather posts.

Images (click to enlarge): 8-14 day temperature and precipitation forecasts from Climate Prediction Center/National Weather Service/NOAA; GFS model output map for sea level pressure, 1000-500 mb thickness, and precipitation, 7 am, January 20, 2009, from NCEP/NWS/NOAA

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Seasonal Outlook

Latest seasonal forecast: Click here.

Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.