September 7, 2017
Summary: That upper low which has been off the coast of San Francisco the past few days is finally moving eastward. Projections are that it will move through northern California today. Already there is some thunderstorm activity over the northern Sacramento Valley. We may see some cloudiness at times, especially over the northern half of the valley, this afternoon and tonight.
We have a rather complex issue for Saturday through Monday. A cut off low is projected to form off the northern or central California coast while an upper high builds over the Rockies. This will turn the winds aloft south to southeast over California, dragging moisture northward from northern Mexico. Models are pretty consistent in showing a chance of scattered showers and thunderstorms over the mountains and deserts of southern California and up the Sierra Nevada. Activity over the valley floor is not out of the question, though it will depend on how close this low is to the coast. If it is fairly close, it could add enough convection for isolated showers and thunderstorms over the valley floor, especially over the south valley. I feel the need to reflect that in the forecast beginning Saturday, but especially for Sunday and Monday when the deepest moisture is close.
Models also show this low hanging off shore all the way through Wednesday then moving inland about Thursday of next week. This will maintain a south to southeast flow through mid week with thunderstorms certainly possible over the mountains, but for now we’ll keep the forecast dry for Tuesday and Wednesday for the valley.
As the low moves inland Thursday, it’s possible more activity could occur, depending upon where the storm tracks. Over the weekend, as high pressure inland begins to build, our temperatures will move up but for now nothing excessive is expected. The next cooling trend will be about Thursday as that low moves inland, bringing in cooler air aloft and no doubt a big burst of marine air.
Forecast: Mostly clear through Friday but with occasional clouds, mainly from Fresno northward. Mostly clear to occasionally partly cloudy Friday night. Variable cloudiness at times, mainly late Saturday through Monday with a small chance of isolated showers and thunderstorms, especially in the south valley. Clearing Monday night. Becoming mostly clear to occasionally partly cloudy Tuesday and Wednesday. Partly cloudy with a slight chance of showers and thunderstorms Thursday.
Short Term:
| Madera 91/62/91/62/92 | Reedley 92/63/91/63/92 | Dinuba 91/61/91/62/91 | |
| Porterville 93/62/92/63/93 | Lindsay 92/62/91/63/91 | Delano 93/65/92/66/92 | |
| Bakersfield 94/69/92/69/93 | Arvin 94/66/92/66/93 | Taft 91/73/92/70/92 | |
| Lamont 94/66/93/67/92 | Pixley 93/64/92/64/92 | Tulare 91/61/91/63/92 | |
| Woodlake 91/61/92/63/91 | Hanford 93/64/92/63/93 | Orosi 91/62/91/63/91 | |
Seven Day Forecast:
| Sunday
Slight chance of showers 66/92 |
Monday
Slight chance of showers 70/93 |
Tuesday
Partly cloudy 70/96 |
Wednesday
Partly cloudy 66/91 |
Thursday
Slight chance of showers 66/88 |
Two Week Outlook: September 14 through September 20: This model indicates another regime of above average temperatures will be at hand. Persistent upper level high pressure is the dominant feature, allowing the chance of afternoon and evening storms over the mountains during this period. For now, we’ll keep the chance of precipitation out of the forecast for the valley floor while strictly monitoring conditions.
September: This model shows upper level high pressure more dominant over the western U.S. There’s no clear indicator of above or below average rainfall as we move into the fall season. With that in mind, we’ll call for near average precipitation for the month.
September, October, November: It appears temperatures overall will rise to above average values for the bulk of this time frame. Upper level high pressure is also more dominant with precipitation, believe it or not, predicted to be somewhat near average.
Winds: Winds will be generally less than 15 MPH through Sunday and mainly out of the northwest afternoons and evenings.
Rain: Dry conditions will continue into Saturday morning. From Saturday afternoon through Monday, things will be a bit dicey. A cut off low is expected to form probably off the central coast during the weekend and drag up some monsoonal moisture, spreading scattered showers and thunderstorms over the mountain and desert regions of southern California and the Sierra Nevada. My main concern is the off shore low. If it centers fairly close to the coast line, it may add enough lift to sustain isolated showers and thunderstorms over the valley floor, especially Sunday through Monday. For now, it appears most locations will remain dry, but there is certainly a small risk factor. Dry conditions are expected Tuesday through Wednesday night with the same low moving inland Thursday, possibly creating another slight risk of activity over the valley floor. Beyond Thursday, expect dry weather.
Afternoon Dew Points Today: Mid to upper 50s. Kern: Mid to upper 50s
Relative Humidity Forecast: Hanford, 30%/75% Bakersfield, 30%/65%
Actual Humidity September 6, 2017: Delano, 79%/33%, Porterville, 80%/27%
Percentage of Sunshine Today/Tomorrow: Visalia: Today 90% tomorrow 90%, Bakersfield: Today 100% tomorrow 80%.
ET Rates Over the Past Seven Days September 6, 2017: Stratford 1.79, Parlier 1.43, Blackwell 1.92, Lindcove 1.44, Arvin 1.64, Orange Cove 1.63, Porterville 1.43, Delano 1.57, Madera Two 1.46 Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 76, Parlier 84, Blackwell 84, Lindcove 80, Arvin 1.89, Orange Cove 84, Porterville 87, Delano 83, Madera Two 84
Mean Temperatures for September Month So Far: 87.3+11.3
Record Temperatures: 106/49. Average Temperatures: 94/62
Cooling Degree Days This Season: 1929, +543 Courtesy of the NWS
Precipitation: Seasonal total/average/above or below average:
Since September 6, 2017, Fresno: 17.20 season. / +5.86 or +5.86 Month to Date: T
Since September 6, 2017, Bakersfield: 7.89, or 1.45, Month to Date: .01
Water year season is from October 1st through September.
Chilling Hours November 1st Through February 28: Orange Cove, Parlier, Arvin, Shafter, , Stratford, Madera two, Alpaugh, Delano, Lindcove, Porterville, Hours at 45 or below 45.
Sunrise: 6:35 am Sunset: 7:18 Hours of Daylight: 12:39
Yesterday’s Weather
MAE : Madera 253 : DH1700 / 98 / 70 / 0.00 /
FAT : Fresno Airport 333 : DH1700 / 97 / 74 / 0.00 /
HJO : Hanford Airport 242 : DH1700 / 98 / 73 / 0.00 /
NLC : Lemoore Naval AS 234 : DH1700 / M / 73 / 0.00 /
BFL : Bakersfield Airport 496 : DH1700 / 98 / 76 / 0.00 /
VIS : Visalia Airport 292 : DH1700 / 96 / 71 / 0.00 /
ATEC1 : Avenal 787 : DH1637 / 98 / 70 / 0.00 /
PTV : Porterville Airport 442 : DH1700 / 97 / 69 / 0.00 /
TFTC1 : Taft 759 : DH1651 / 94 / 73 / 0.00 /
LOSC1 : Los Banos 120 : DH1600 / 95 / 69 / 0.00 /
Rainfall:
To date Last year Average Annual ave
STOCKTON 0.00 21.79 158 16.69 121 13.78 14.06
MODESTO 0.00 16.93 132 15.61 121 12.86 13.11
MERCED 0.00 16.03 131 14.66 120 12.22 12.50
MADERA 0.00 14.18 120 12.96 110 11.78 12.02
FRESNO T 17.20 152 14.29 126 11.34 11.50
HANFORD 0.00 11.05 111 8.26 83 9.93 10.10
BAKERSFIELD T 7.83 122 5.43 85 6.40 6.47
BISHOP 0.00 9.18 184 3.88 78 4.99 5.18
SALINAS T 16.45 130 13.47 106 12.66 12.83
PASO ROBLES T 16.16 129 8.06 64 12.56 12.78
SANTA MARIA 0.06 18.69 135 9.00 65 13.82 13.95
Rainfall season from October 1st through September 30th
Next Report: Friday, September 8