RAINY WIN­TER IN FORE­CAST

The Tribune (SLO) (Sunday) - - Front Page - BY JOHN LIND­SEY

The storm door has opened, and the Cen­tral Coast is ex­pected to re­ceive above-av­er­age rain­fall this win­ter.

Ranch­ers love the Novem­ber rains as they pro­mote an early start to the grasses that will trans­form our hills to emer­ald green over the next few weeks. That cer­tainly wasn’t case dur­ing the first part of Novem­ber.

Firmly an­chored off the Cal­i­for­nia coast­line, the Eastern Pa­cific High and tran­si­tory high-pres­sure sys­tems at the sur­face moved over the Great Basin — the area be­tween the Sierra Ne­vada range to the west and the Rocky Moun­tains to the east. This con­di­tion cre­ated per­sis­tent Santa Lu­cia north­east­erly (off­shore) winds that brought warm and bone-dry weather.

Then a sig­nif­i­cant change oc­curred in the lat­ter part of Novem­ber; the Eastern Pa­cific High shifted north into the eastern Gulf of Alaska while the south­ern branch of the po­lar jet moved south­ward carv­ing out low-pres­sure sys­tems and trans­port­ing these storms across the ocean to­ward Cal­i­for­nia.

In other words, the storm door is opened.

De­spite the arid con­di­tions dur­ing the first half of Novem­ber, lo­ca­tions through­out the Cen­tral Coast have recorded above av­er­age rain­fall for the month. Paso Rob­les re­ceives typ­i­cally about an inch of rain in Novem­ber, but this past month it recorded 2.34 inches. Cal Poly, which has rain­fall records stretch­ing back nearly 150 years, re­ported 4.18 inches this Novem­ber, nearly dou­ble the typ­i­cal Novem­ber. The Santa Maria Air­port has re­ported about an inch and a half of pre­cious rain, or about 112 per­cent of nor­mal. For the rain sea­son, www.SLOWeather.com is re­port­ing 140 per­cent of av­er­age.

The U.S. Monthly Drought Out­look in­di­cates that the drought clas­si­fi­ca­tions in North­ern and the north­ern half of Cen­tral Cal­i­for­nia will likely be re­moved by the end of the year. Ar­eas south of Paso Rob­les into Santa Bar­bara County will see drought clas­si­fi­ca­tions con­tinue, but will they prob­a­bly im­prove.

So what caused this dra­matic change in the weather pat­tern?

No­body knows for sure, but it may have been caused by El Niño (warmer than nor­mal sea sur­face tem­per­a­tures in eastern Equa­to­rial Pa­cific).

These warmer waters in the eastern Pa­cific pro­duce a more con­sid­er­able amount of evap­o­ra­tion. As this wa­ter va­por as­cends into the at­mos­phere, it of­ten con­denses into thun­der­storms and re­leas-

es tremen­dous amounts of la­tent heat, which fur­ther de­creases the at­mo­spheric pres­sure. This area of low pres­sure, in turn, changes the path of the south­ern branch of the po­lar jet stream, pulling it far­ther south­ward to­ward the Cen­tral Coast.

The Cli­mate Pre­dic­tion Cen­ter is ad­ver­tis­ing that “El Niño is fa­vored to form this win­ter with an 80 per­cent chance.”

More im­por­tantly, the strength of this ex­pected El Niño event should have a bear­ing on the amount of rain­fall the Cen­tral Coast will re­ceive. Typ­i­cally, in San Luis Obispo and Santa Bar­bara coun­ties, the higher the clas­si­fi­ca­tion of the El Niño event, the more rain it will cre­ate.

Neu­tral El Niño con­di­tions — or El Nada or weak El Niño — typ­i­cally don’t pro­duce any re­li­able sea­sonal rain­fall pre­dic­tions along the Cen­tral Coast, but a mod­er­ate, strong or very strong more times than not do.

Over the past month, the nu­mer­i­cal mod­els have in­creased the pre­dicted El Niño cat­e­gory to a mod­er­ate strength level for this win­ter.

This con­di­tion typ­i­cally pro­duces about 110 per­cent of above-av­er­age rain­fall in San Luis Obispo County and nor­mal rain­fall amounts in Santa Bar­bara County.

With that said, here are my rain sea­son’s pre­dicted rain­fall to­tals: Cam­bria, 24 inches; Paso Rob­les, 14; San Luis Obispo, 25; Nipomo, 20; Santa Maria, 14; Lom­poc, 16; and Santa Ynez, 20.

Not only will these storms pro­duce much- needed rain, but also high sea and swell events. At PG&E, the safety of cus­tomers and em­ploy­ees is a top pri­or­ity. If you ven­tured to the coast­line to ob­serve these waves, please re­mem­ber not to climb rock walls or jet­ties, keep chil­dren and pets back from the wa­ter’s edge and never turn your back to the ocean.

THE CLI­MATE PRE­DIC­TION CEN­TER IS AD­VER­TIS­ING THAT ‘EL NIÑO IS FA­VORED TO FORM THIS WIN­TER WITH AN 80 PER­CENT CHANCE.’

John Lind­sey’s col­umn is spe­cial to The Tri­bune. He is PG&E’s Di­ablo Canyon ma­rine me­te­o­rol­o­gist and a me­dia re­la­tions rep­re­sen­ta­tive. Email him at [email protected] or fol­low him on Twit­ter: @PGE_John.

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