Val­ley tops charts for rain, heat

High overnight tem­per­a­tures drive up Al­len­town’s av­er­ages

The Morning Call - - FRONT PAGE - By Stephanie Si­gafoos

This sum­mer, Al­len­town, like much of the rest of the coun­try, has been ab­nor­mally hot. Tem­per­a­tures ticked up in May, and then June. The lin­ger­ing sun of late July proved pos­i­tively blis­ter­ing. And as swel­ter­ing Au­gust af­ter­noons slipped into sweaty evenings, the ther­mome­ter con­tin­ued to crest above av­er­age.

If your elec­tric bill soared these past three months, take com­fort in know­ing you were not alone.

When the sum­mer is said

and done, Al­len­town will rank among the top 35 ma­jor cli­mate sites in the North­east for high tem­per­a­tures and pre­cip­i­ta­tion at a time when ex­treme weather and wide­spread heat seem to be the new sea­sonal norms. Heat waves may not have been un­prece­dented this sum­mer, but are hap­pen­ing now on a planet that is see­ing hot­ter nights than be­fore.

“There is some­thing anoma­lous about all of this data for Al­len­town, and it’s the overnight tem­per­a­tures. It’s all re­lated to the overnight lows,” said me­te­o­rol­o­gist Ed Vallee of Em­pire Weather, not­ing how the in­crease in sum­mer night­time tem­per­a­tures are an ex­am­ple of how small shifts in av­er­age tem­per­a­ture can lead to over­all ex­tremes.

Ac­cord­ing to the North­east Re­gional Cli­mate Cen­ter, 32 of the re­gion’s 35 ma­jor cli­mate sites ex­pe­ri­enced a warmer-than-nor­mal Au­gust, with 10 rank­ing this Au­gust among their 20 warm­est on record. At the top of the chart was Al­len­town, with an av­er­age Au­gust tem­per­a­ture of 75 de­grees, or 3.3 de­grees above av­er­age (and good for the city’s 11th-warm­est Au­gust on record). At least 18 nights were above 64 de­grees.

It fits with a na­tion­wide trend high­lighted last year by the Na­tional Oceanic and At­mo­spheric Ad­min­is­tra­tion, which showed that na­tion­wide, sum­mer nights have warmed at nearly twice the rate of days, with overnight low tem­per­a­tures in­creas­ing 1.4 de­grees per cen­tury since 1895, when na­tional tem­per­a­ture records be­gan.

No other cli­mate site in the North­east was close to Al­len­town last month in terms of ex­ceed­ing its nor­mal tem­per­a­ture. Bal­ti­more’s de­par­ture-from-nor­mal was 2.8 de­grees. Har­ris­burg was 2.7 de­grees. Scran­ton, Bos­ton and Wash­ing­ton, D.C., all saw tem­per­a­tures 2.0 de­grees above nor­mal.

Au­gust pre­cip­i­ta­tion, hit or miss across some of the ma­jor cli­mate sites, was cer­tainly a “hit” in Al­len­town. The city had 4.79 inches of rain, 130% of nor­mal. It was tied for the eighth-wettest cli­mate site in the North­east for the month, with the mea­sure­ment ty­ing Dulles Air­port, Vir­ginia.

For over­all sum­mer pre­cip­i­ta­tion, Al­len­town was near the top again among all ma­jor cli­mate sites. Twenty were wet­ter than nor­mal, data show, with Al­len­town tops on the list at 20.10 inches, but se­cond over­all in per­cent above nor­mal. Scran­ton had 18.87 inches, or 168% of nor­mal, while Al­len­town was 155% above nor­mal.

It will rank as the city’s fifth­wettest sum­mer over­all, with mul­ti­ple dates where record rain­fall oc­curred. On July 12, 2.75 inches of rain fell at the air­port and smashed the pre­vi­ous record of 1.17 inches set in 1950. A record rain­fall of 2.50 inches fol­lowed on July 23, beat­ing the old record of 1.54 inches for the date set in 1938.

“When you have more mois­ture in the at­mos­phere, just in terms of ther­mo­dy­nam­ics, it’s harder to cool the at­mos­phere down,” Vallee said, not­ing that a com­pli­cated range of fac­tors af­fect these over­all num­bers in­clud­ing pre­cip­i­ta­tion, dew points, pre­vail­ing winds, prox­im­ity to the ocean, and green spa­ces (or lack thereof ) in neigh­bor­hoods.

Im­per­vi­ous, heat-ab­sorb­ing sur­faces, for ex­am­ple, can el­e­vate tem­per­a­tures in ci­ties well be­yond the norm.


A blue heron looks for din­ner in July af­ter heavy rain brought flood­ing to Cedar Beach Park near the Rose Gar­den in Al­len­town. When the sum­mer is said and done, Al­len­town will rank among the top 35 ma­jor cli­mate sites in the North­east for high tem­per­a­tures and pre­cip­i­ta­tion.

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