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Posted at 10:30 AM ET, 05/28/2008

Capital Weather Gang's 2008 Summer Outlook

By Matt Ross

It's almost June, and those hazy, hot, humid days are just around the corner. Alas, our 2008 summer outlook is here.

The task of doing a summer outlook is no easy one. First, with few exceptions, summer in the D.C. area is mainly hot. Does Joe Public really care if it's 88 and humid or 93 and humid? Second, the weather varies less during the summer than it does during the the rest of the year (especially compared to winter), with the vast majority of summer months finishing within a few degrees of normal. So, it follows that when putting together a summer outlook we're less likely to see the signals for extreme warmth or cold that we sometimes see in advance of winter.

Nevertheless, we will do our best to convey what we expect for summer 2008...

Keep reading for our summer outlook. For weather in our more immediate future, see our full forecast through the weekend.

The main methodology in creating the outlook was the use of analog years. Analog years are past years in which conditions leading up to summer most closely resemble conditions leading up to summer 2008. Analog years are far from a perfect predictor due to the complexities of weather, as no two years are exactly alike. However, they can be of considerable value in giving us a general idea of what to expect. Below are the factors we consider to be of the greatest value in picking analog years.

THE FACTORS

The following factors were given the most consideration in preparing the outlook. It should be noted that any one factor does not necessarily correlate with a particular kind of summer (e.g., warm, cool, dry or wet).

El Niño/La Niña:

We are currently experiencing a weakening La Niña event that peaked during the winter. La Niña is an oceanic phenomenon in which the equatorial waters of the Pacific Ocean are anomalously cool (the opposite of El Niño, when the same waters are anomalously warm). Currently, sea-surface temperatures in these waters are quickly approaching normal.

Winter Conditions:

This past winter was a relatively mild one for our region with very little snow. Most of the East Coast experienced warmer-than-normal temperatures, with the coldest areas in the Northern Plains and Desert Southwest. We saw large precipitation deficits in much of the Lower Mid-Atlantic and Deep South, while much of the Ohio Valley and Northeast experienced an abundance of precipitation.

Spring Conditions:

Spring temperatures have been quite warm in our area until the last few weeks. Nonetheless, spring has been quite cool over most of the country with the exception of California, Texas, the Lower Mid-Atlantic and Southeast. Precipitation this spring has been well above normal in the Mid-Atlantic, Ohio Valley and Lower/Western Plains, while the rest of the country (especially the West Coast and Southeast Coast) has been relatively dry. Severe weather has been prominent in the favored areas of the Deep South, Ohio Valley, Midwest and Lower Plains.

Intangibles:

*This May will be the first month since April 2007 to finish with below-normal temperatures.
*22 of our last 30 summers have finished with temperatures at or above normal, including the last three in a row.
*8 of our last 10 Augusts have finished with above-normal temperatures.

Analog Years

Primary Analog Year (or best match): 1974
Secondary Analogs (close matches): 1971, 1976, 1985, 1989, 1999, 2000

The weather during the summers of the analog years serves as the basis for our outlook.

THE FORECAST

Temperatures:

summer-temp-probs.gif
Probability of average, below-average and above-average temperatures in the metro area during June-July-August. Average is defined as within plus or minus two degrees of average.

June: Normal to 1 degree below normal
July: Normal
August: Normal to 1 degree above normal

Overall: Normal to Slightly Above Normal

As our probabilities shown to the right suggest, confidence is fairly high temperatures will be pretty close to average for the summer.

90-degree days: Normal (about 30)

Precipitation: Slightly Above Normal

FORECAST SUMMARY

We think this summer will be our coolest since 2004, but that isn't saying much considering we've had three consecutive hot summers. At the same time, this probably won't be one of our colder summers, either. As usual, expect plenty of hot, humid days with highs in the upper 80s to low 90s, especially in the heart of summer between mid-June and mid-August. However, this summer may seem more moderate, as the extended heat waves that plagued the last three summers are not as likely.

Stay cool.

By Matt Ross  | May 28, 2008; 10:30 AM ET
Categories:  Capital Weather Gang, Local Climate  
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Comments

Didn't temperatures top 100 F in late June/early July in 1999?

Posted by: Murre | May 28, 2008 12:13 PM | Report abuse

I honestly have no idea what the numbers say, but I wouldn't categorize this Spring as "quite warm." Maybe it is just perception, but I can remember only a few warm, nice Spring days this year.

Posted by: Southside FFX | May 28, 2008 12:32 PM | Report abuse

Murre....Yes 1999 was a hot summer...Those analogs are just for guidance....I do not think this summer will be as hot as 1999

Southside....Spring will probably finish around 1.5 degrees above normal....But you are right...May has been cool

Posted by: Matt Ross, Capital Weather Gang | May 28, 2008 1:05 PM | Report abuse

Matt, any thoughts on summer precip?

Posted by: ft washington | May 28, 2008 1:28 PM | Report abuse

I'm seeing this as a "La Nina" summer ~ possibly warmer than normal, with enhanced risk of Atlantic and Caribbean tropical cyclones. Will we get a June tropical storm or hurricane? Possibly: the risk is above normal this year. However, the United States may not see a landfall since it is landfall and storm tracks and not the intensity of the season which determines whether or not a hurricane season is "memorable". Please note that 1992 was regarded as a "memorable" hurricane year for the continental U.S. even though there was a below-average number of named tropical systems. That is because the one major hurricane,"Andrew", tracked across southern Florida and into Louisiana, causing a lot of damage. Last year had an above average number of named systems but only "Humberto" hit the continental U.S. It was a "memorable" season mainly for Mexico and Central America since three major hurricanes tracked across that area on a westward course but never touched the continental U.S.

Posted by: El Bombo | May 28, 2008 3:06 PM | Report abuse

Darn, I was hoping for a lot of cloudy cool days, but little rain. It sucks to study for the bar when it is beautiful outside.

Posted by: ep, jd | May 28, 2008 5:38 PM | Report abuse

Nice Blog, It makes sense to me looking over the fading La Nina and all. We here at myweatherlive.com would be love it if you could blog on our site. Check it out if you get a chance.

Posted by: rob guarino | May 28, 2008 6:43 PM | Report abuse

Matt:
I believe your outlook is right on target. I do not believe the s.e. ridge will be as dominant or persistent as last year. This summer should be a lot closer to "normal"

With the Enso condition expected to be closer to neutral next winter, let me be the first to predict a memorable winter next year!!!!

Posted by: Augusta Jim | May 28, 2008 7:45 PM | Report abuse

Fading La Nina means more snow next winter right??

Posted by: Period | May 28, 2008 11:59 PM | Report abuse

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