September 12, 2018
Summary: A major pattern change is underway. Satellite imagery clearly depicts a large area of low pressure extending from the eastern Pacific off the coast of the Pacific Northwest down into northern California. Already this morning, the freezing level has dropped to 12,900 feet over Oakland and the marine layer, which was a little more than a thousand feet deep yesterday, is more than 3,000 feet deep this morning. Models also show a tightening pressure gradient between the coast and the interior, meaning the onshore flow will become stronger with time, allowing marine air to flood the valley. The combination of the strong onshore flow and cooler air at the mid and upper levels of the atmosphere will mean there will be a touch of early fall in the air through the weekend. Some of the traditionally cooler spots north of Kern County could easily fall into the mid to upper 40s each night through at least Monday morning. The only locations to possibly reach 90 this afternoon will be in Kern County and even there upper 80s are more likely. Readings Thursday through Sunday will only top out in the low to mid 80s.
By Friday, a massive area of low pressure will stretch from northern Canada to northern and central California plus off shore waters, as well. The main low center will be just off the Washington coast, creating a dry southwest flow aloft. We may see some high clouds from time to time embedded within this flow, but even so, mostly clear skies will prevail.
The next warming trend appears to be a minor one and should begin Monday as a high over the Four Corners region tries to expand back over California. However, this doesn’t look like a dominant feature with possibly some lower 90s Monday through Wednesday. After Wednesday, some models, anyway, depict a new trough over the Pacific Northwest and into the northern half of California. This system is weaker, however, with the main effect being near average temperatures for central California and a dry west to southwest flow aloft.
Forecast: Clear and cooler through Saturday. Mostly clear Sunday through Wednesday.
Short Term:
| Madera 86/52/83/51/83 | Reedley 88/53/83/52/82 | Dinuba 87/52/82/51/83 | |
| Porterville 88/52/84/51/82 | Lindsay 88/50/83/49/83 | Delano 89/54/84/52/84 | |
| Bakersfield 89/58/83/56/84 | Arvin 90/56/83/54/84 | Taft 88/62/83/59/84 | |
| Lamont 89/58/83/55/84 | Pixley 88/53/83/52/84 | Tulare 88/54/83/51/83 | |
| Woodlake 88/55/83/50/84 | Hanford 88/53/83/52/82 | Orosi 88/52/83/49/83 | |
Seven Day Forecast:
| Saturday
Mostly clear 52/85 |
Sunday
Mostly clear 52/87 |
Monday
Mostly clear 55/89 |
Tuesday
Mostly clear 56/91 |
Wednesday
Mostly clear 55/90 |
Two Week Outlook: September 19 through September 25: A flat zone of upper level high pressure will dominate California and off shore with mainly a westerly flow moving into the Pacific Northwest. This pattern is not really conducive for above or below average temperatures but this time of year continues to be dry.
September: This model indicates there will be a higher than active monsoon over the Desert Southwest and possibly central and southern California. This typically does not affect the valley floor other than cloud cover but could result in a larger number of days of thunderstorms over the Sierra Nevada and possibly even the Kern County mountains. With generally high pressure over the southwest, temperatures will likely be somewhat above seasonal average.
September, October, November: The first part of this time frame will see a more active than usual monsoon in place for above average rain over the Sierra Nevada and possibly the mountains and deserts of southern California. October and November’s conditions aren’t as easy to determine. At this time we’ll call for generally average values for both rain and temperatures.
Winds: Winds, especially during the afternoons and evenings, will be out of the northwest at 5 to 15 MPH through Saturday with locally stronger gusts. The exception will be portions of the west side, mainly along the I-5 corridor where gusts in excess of 35 MPH cannot be ruled out.
Rain: Expect dry conditions indefinitely.
Afternoon Dew Points Today: Upper 30s to the lower 40s. Kern: Mid to upper 30s.
Humidity: Visalia: 20%/80% Bakersfield: 15%/60%
Actual Humidity September 11, 2018: Delano, 88%/18%, Porterville, 80%/17%
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 100% tomorrow 80% Bakersfield: Today: 100% Tomorrow: 90%
ET Rates Over the Past Seven Days: Stratford 1.72, Parlier 1.52, Blackwell 1.71, Lindcove 1.51, Arvin 1.76, Orange Cove 1.75, Porterville 1.42, Delano 1.56, Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 73, Parlier 77, Blackwell 86, Lindcove, 77, Arvin, NA, Orange Cove 78, Porterville 84, Delano 76,
Record Temperatures: 105/48. Average Temperatures: 92/60
Cooling Degree Days this Season: 1896 +449
Courtesy of the NWS
Average temperature for September so far: 78.9 +3.3
Precipitation: Seasonal total/average/above or below average:
Since Oct 1, 2017 Fresno: 6.73 season. or -4.63. Month to Date: .00
Since Oct 1, 2017, Bakersfield: 3.93, or -2.46. Month to Date: .00
Water year season is from October 1st through September.
Chilling Hours November 1st through February 28: Orange Cove, Parlier, Arvin, Shafter, Stratford, Madera two, Lindcove, Porterville, Hours at 45 or below 45.
Sunrise: 6:40 am Sunset: 7:09 pm. Hours of Daylight: 12:30
Yesterday’s Weather:
MAE : Madera 253 : DH1700 / 98 / 59 / 0.00 /
FAT : Fresno Airport 333 : DH1700 / 96 / 64 / 0.00 /
HJO : Hanford Airport 242 : DH1700 / 97 / 55 / 0.00 /
NLC : Lemoore Naval AS 234 : DH1700 / 97 / 58 / 0.00 /
BFL : Bakersfield Airport 496 : DH1700 / 95 / 66 / 0.00 /
VIS : Visalia Airport 292 : DH1700 / 93 / 55 / 0.00 /
ATEC1 : Avenal 787 : DH1656 / 95 / 62 / 0.00 /
PTV : Porterville Airport 442 : DH1700 / 95 / 58 / 0.00 /
TFTC1 : Taft 759 : DH1657 / 96 / 72 / 0.00 /
LOSC1 : Los Banos 120 : DH1600 / 94 / 62 / 0.00 /
Rainfall: Water year Oct 1st through September 30th
Year % Last Y. % Ave. Annual ave.
STOCKTON 0.00 9.22 67 21.79 158 13.82 14.06
MODESTO 0.00 8.17 63 16.93 131 12.89 13.11
MERCED 0.00 7.06 57 16.03 131 12.28 12.50
MADERA 0.00 7.22 61 14.26 121 11.83 12.02
FRESNO 0.00 6.73 59 17.30 152 11.36 11.50
HANFORD 0.00 4.70 47 11.16 112 9.97 10.10
BAKERSFIELD 0.00 3.95 62 7.83 122 6.41 6.47
BISHOP 0.00 3.08 61 9.18 183 5.02 5.18
SALINAS 0.00 7.16 56 16.49 130 12.68 12.83
PASO ROBLES 0.00 9.62 76 16.17 129 12.58 12.78
SANTA MARIA 0.00 6.01 43 18.91 137 13.84 13.95
Next report: Thursday, September 13