The significant 2008 Summer begins.......

~ Don't extrapolate continuously, but this is the first of many population-critical heat events that will make appearances June-September...

The 1st pitch has been thrown out, the game is underway, so let's review & remind ourselves of some climatological loose ends, forecast warnings, and rumors/pitfalls that still may be floating around.

Top-Ten for the Summer Road:

10.) The climatological building blocks for the 2008 U.S. Summer were established and set in motion months ago. Meteorological Moral of the story: Compared to some of the blistering Summers out West this Decade, 2008 was going to be less about them and more about the Eastern U.S. ( Texas to the Atlantic ). {During the Summer, this hotter-themed pattern would run into some more surface & synoptic resistance across deep New England, Quebec/Ontario, and the Upper Mid-West/Plains, so superfluous Season-long expectations should be tempered there}

9.) From New Mexico to Louisiana and Mexico to Oklahoma , we believed there would be tremendous heat upside potential for the South-Central U.S. this year compared to 2007. For this region, these stark temperature contrasts would be evident beginning in the back-half of May, measured both in CDD's and critical days (as we have already come to live & breathe the past 3 weeks - see stats below for Texas, et al.).

8.) Next on our research docket was more seepage of heat East of the Mississippi River (into the Southeast quadrant), followed by warmth climbing its way up the East Coast in June. By May 31st Richmond Virginia had already broken 90°F (hotter than any day during last May's late warm-up), and now the Big I-95 Cities are preparing for their 1st (of many) Heat Waves this Summer. What goes up must come down, so keep the ebb & flow paradigm in your head fore the next 4 months: a heat wave coming to an end is not a pattern change for a Season.

7.) Not to be used as a meteorological or synoptic comparison (because every year is unique), but 2005 provided the best recent example for us to use in attempting to relay extreme caution for those that started to draw Summer conclusions based on a cool/raw Eastern May. In much the same way that October/November is mutually exclusive of the ensuing Winter, so to is April/May mutually exclusive of the ensuing Summer, and the May 2008 vs. June-September 2008 contrast was going to be dramatic (or shocking for those not prepared).

6.) Whether it was alarming calls for La Niña fading (and La Niña doesn't even shape our Summer temperatures!) or the love affair with the year 2000 (the coldest Summer in the Northeast since 1927!), this pseudo-science began to spread like weeds emanating from the main (short-term) forecast services. And hence their feet were dug in for a Cold June-September Summer Season which quickly became "consensus opinion" in April-May.

5.) Even though May 2008 was the opposite of May 2000 for the Nation, it's going to take a whole lot more than an early-June Heat Wave for this widespread forecast service stance to wither away or be repealed. Remember: it wasn't until the 3rd-4th week of this past January before the Analog/La Niña inspired "Winter is Over" rhetoric was finally muzzled, and that was all amidst the coldest National Winter this Decade. So a cold front here, a moderated week there, a rogue model flip here, and you can bet your bottom dollar the "Heat Haters" will take advantage of these typical Summer undulations and will be out in full force [see #4 and #2 below for guidance]. Our perennial favorite is "temperatures 10 degrees colder!", neglecting to advertise that the drop-off is from +12 anomalies to a +2 anomalies.

4.) We live on Planet Earth, not the Planet Venus: Even a region's hottest Summers in the historical record had plenty of cool episodes, so keep rumors you hear in that context. For practically all Cities/States, 1 Standard Deviation in mean monthly temperature is only around 2°F, thus merely a couple degrees is all that separates a Hot Summer from a Normal Summer. So you don't need those +/-8°F monthly anomalies you may witness in Winter to be an "impressive" month in the Summer (in fact monthly Summer anomalies >4°F are exceedingly rare). So this Heat Wave will of course come and go, and we'll see more ups & downs throughout the Summer, but when people look back on October 1st at the June-September 2008 Summer, heat will easily dominate cold in describing and quantifying Texas to the Atlantic.

3.) In the Winter, computer models' biggest problem is more the flipping & fluctuating on a whim, giving users headaches. In the Summer, computer models' biggest flaw is mean-reverting and diluting anomalous events, so users/forecasters who depend on them are caught off-guard by heat waves (and/or their magnitude). How this manifests itself is the following: A computer model shows some warmth (maybe +4 anomalies) on the 2-week horizon; a week out these are bumped up to +8 anomalies; a few days out these are bumped up to +12 anomalies; and then we wind up experiencing +16 anomalies in actuality. We again caution that this Weekend's event is the first of many you'll see this routine played out, so factor in this model conservatism when warm spells are on their way. {P.S. 12Z GFS solutions are based on a very small climatological reference data-set, so wild solutions - extreme, flipped, or muted - is to be expected as is subsequent "mid-day update drama"}.

2.) From the "Out of Left Field" column this past week came the latest Eastern Trough rumor. Text Book Meteorology states that a re-curving Western Pacific Typhoon portends a large/multi-State Eastern U.S. Trough 6-10 days later. Of course real life rarely follows text book examples and hence the rumors surrounding Typhoon Nakri are coming up flat. The Long Answer: this atmospheric rule of thumb works best in the October-December time-frame (when Canadian Polar Ridges are being established), works best when the Typhoon actually crosses 50°N latitude (to establish enough thermodynamic contrasts), and the associated trough axis has a margin of error of 2,000 miles as an added caveat. The short Answer: having begun its re-curvature early this week, the hyped "Nakri effect" was supposed to create an Eastern-Third Trough in 6-10 days (i.e. as early as June 9th and as late as June 13th). Bottom line: it won't happen, an Eastern Ridge and associated warmth will still be the main feature next week, and no, a Great Lakes Cold Front or a back-door New England cold front doesn't count as validation.

1.) Drought is a big story for many States (especially the Southwest and Southeast quadrants of the Nation), but humidity/mugginess are going to be exceptionally powerful players this Summer for several large metropolitan regions. Similar to how Wind-Chill helped make this past Winter much "colder" than HDD's and Temperatures alone suggested, Temperature Humidity Index [THI] is not accounted for by CDD's or thermometer readings. High soil moisture has the over-simplified reputation of being bearish for heat, but its influence is heavily dependent on Latitude, Urban/Rural terrain, Soil type, and evapotranspiration rates of various vegetation. Cooling hot & dry air is one thing, but cooling hot & humid air is an added labor. And excessive mugginess/particulates help sustain the afternoon's heat well into the night (especially for urban canyons), which will be a frequent scenario in 2008. 1 CDD on a Muggy Day is worth about 1.5 CDD's on a dry day, so do the "Energy Math" before the results for a Week, Month or Season exceed what high/low temperatures alone would insinuate.

Amidst the expected cool/temperate May for the National as a whole, the beginnings of Summer's grasp is emerging and progressing on schedule. Earlier this month it made its debut with a record heat wave for Las Vegas/Phoenix et al. and has since made its eastward slide, focused on Texas and the South-Central region. Folks certainly didn't have to wait long (in May) to see the year-on-year Heat/CDD/Critical Day contrasts peculate up for 2008, and they will continue:

Dallas

May 2007: only 1 day hitting (exactly) 90°F all month.

May 2008: 5 days reaching 95°F or hotter.

Houston

May 2007: only 4 days reaching 90°F all month.

May 2008: 14 days reaching 90°F or hotter.

San Antonio

May 2007: ZERO days reaching even 90°F all month.

May 2008: 14 days reaching 95°F or hotter.

Oklahoma City

May 2007: ZERO days reaching 90°F all month.

May 2008: 6 days reaching 90°F or hotter.

New Orleans

May 2007: only 1 day hitting (exactly) 90°F all month.

May 2008: 6 days reaching 90°F or hotter.

And extending across the Gulf of Mexico .......

Miami

May 2007: only 2 days hitting 90°F all month.

May 2008: 13 days reaching 90°F or hotter.

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