Get ready for unseasonably warm weather, dirtier air than normal for February, and a growing rainfall and snowfall deficit.
A persistently strong high pressure system off the California coast has prompted various agencies to revise forecasts and issue warnings.
uHighs are expected to be in the low 70s in the upcoming week hitting 72 degrees on Tuesday as well as Wednesday and reaching 73 degrees next Thursday.  Until then highs are expected to stay above the historical Manteca average of 61 degrees for February. The record high for February in Manteca was 78 degrees in 1977, the second year of a two-year drought.
uThe San Joaquin Valley Air Pollution Control District Wednesday issued a health cautionary statement warning stagnant air will likely see an upswing in particulate pollution that can trigger asthma attacks as well as bronchial infections. The district also warns research shows a higher level of particulate pollution can be a contributing factor for heart attacks and stroke which is why they are warning people with health issues to curtail heavy outdoor activities during periods of elevated particulate matter concentrations.
uThe pressure system has pushed back projections for the next possible rainfall and snowfall four days to Feb. 22. A number of forecast models are calling for rain Feb. 22-23 and Feb. 26-28 just as the peak of the critical almond blossom season is typically is reached. Heavy rain, should it occur, can raise havoc with delicate almond blossoms and create potential problems for the South County’s No.1 agricultural crop.
The unseasonably warm weather could force the South San Joaquin Irrigation District to resort to a rare February irrigation run if the soil becomes too dry.
Since the start of the weather year on Oct. 1, Manteca has recorded 3.10 inches of rainfall based on readings at the Civic Center weather station. The historic average for the four-month period through Jan. 31 is 7.07 inches. That means accumulative rainfall is now running 56 percent below normal in Manteca
Average rainfall for Manteca in February is 2.46 inches, in March it is 2.28 inches, and in April it is 0.96 inches. After than monthly averages drop of significantly.
And as disappointing that temperatures and rainfall may be in the Northern San Joaquin Valley the real concern is in the Sierra where the snowpack provides a critical 60 percent of the state’s water needs.
The high reached 69 degrees on Tuesday at Reno-Tahoe International Airport — shattering the previous record of 65 set in 2003, the National Weather Service said Wednesday. The high of 57 at South Lake Tahoe broke the mark of 52 set in 2012.
The balmy weather comes a week after the first series of major winter storms dumped more than 2 feet of snow on top of the Sierra Nevada in the mountains around Lake Tahoe.
The weather service said Wednesday high pressure near the West Coast will keep conditions dry throughout the region with above average temperature and generally light winds for the next seven to 10 days. Highs in the region typically are in the 40s this time of year.
“Highs in the 60s will be common, even in some Sierra valleys,” the service said. “This is a good 15 to 20 degrees above average.”
Statewide, the snowpack is at 30 percent of normal. The last time recorded weather stats had the snowpack that low at the end of January was in 2015 when it was at 25 percent of the historic average. That was followed by a dismal April 2015 snowpack of 55 percent — an all-time low since weather stats started being recorded in the 1860s — prompting Gov. Jerry Brown to declare a drought emergency.
The San Joaquin Valley Air Pollution Control District is encouraging Valley residents to use the District’s state-of-the-art Real-time Air Advisory Network (RAAN) on the District’s website at www.valleyair.org/RAAN that provides all residents with real-time air quality information for neighborhoods throughout the Valley until such time as conditions improve .
The district noted in a release Wednesday that “after decades of investment and sacrifice by Valley businesses and residents, emissions have been reduced by more than 80% and are at historically low levels.  However, these stagnant conditions that the Valley is facing due to extraordinary weather conditions can still lead to elevated particulate matter concentrations.  Particulate pollution is harmful and has been correlated with asthma attacks, bronchial infections, heart attacks and stroke.”
For more information about the Air District, call the  regional office in Modesto at (209) 557-6400 or Bakersfield (661) 392-5500.
To contact Dennis Wyatt, email dwyatt@mantecabulletin.com