September 26, 2018
Summary: Strong high pressure at the mid and upper levels of the atmosphere continues to cover the eastern Pacific with the main center off the coast of the Pacific Northwest, extending northward into the Gulf of Alaska. The high will continue to build over California during the next 48 hours, driving temperatures a good 7 to 10 degrees above average. The marine layer this morning is only 1,200 feet deep with no chance of any sea breeze entering the valley, at least temporarily.
In the meantime, we have a low center which is still well off shore, but will be approaching the northern California coast. From there, it will move inland Friday night and Saturday with the beginning of synoptic cooling and a strong on shore flow which will drop temperatures about 15 degrees by Saturday with readings only in the upper 70s to lower 80s Sunday and Monday.
We are closely monitoring Tropical Storm Rosa. As of the last issuance from the Hurricane Center, Rosa was 410 miles southwest of Manzanillo, Mexico. Rosa is projected to take a northwesterly path for a time, then jog towards the northeast towards northern Baja or even a slight chance over extreme southern California. Forecast models are all over the place with this storm, but seem to keep the precipitation a bit further south. However, with the high approaching from the west and a trough of low pressure moving through northern and central California Tuesday, the winds aloft could become southerly, allowing some of Rosa’s remnants to move into central California.
The risk factor, for now, remains fairly low as the various players would have to set up just right. The greatest risk will be Kern County and points south, tapering off further north. For now, I’ll keep this in the small chance category, however we will be dealing with a tropical system which are notoriously difficult to forecast.
Forecast: Other than occasional high clouds, it will be mostly clear through Sunday night. Becoming partly cloudy Monday. Variable cloudiness Monday night through Wednesday with a small chance of showers and thunderstorms late Monday night through Wednesday.
Short Term:
Madera 96/58/98/59/94` | Reedley 96/58/97/59/95 | Dinuba 95/56/96/58/94 | |
Porterville 97/59/98/61/95 | Lindsay 96/56/98/59/95 | Delano 97/62/98/63/96 | |
Bakersfield 97/68/99/70/97 | Arvin 97/65/100/67/98 | Taft 96/71/98/72/97 | |
Lamont 97/64/100/67/98 | Pixley 96/58/98/60/95 | Tulare 95/56/97/59/94 | |
Woodlake 95/57/97/59/95 | Hanford 97/60/98/61/96 | Orosi 96/57/97/58/95 |
Seven Day Forecast:
Saturday
Mostly clear 55/87 |
Sunday
Mostly clear 51/83 |
Monday
Partly cloudy 54/82 |
Tuesday
Chance of showers 54/81 |
Wednesday
Chance of showers 52/86 |
Two Week Outlook: October 3 through October 9: This model shows strong high pressure along the Pacific coast. It also, however, indicates the possibility of moisture moving into Arizona and southern California from the south. Temperatures under this regime would again be above average with a low chance of precipitation.
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 will be mainly less than 12 MPH through Thursday. Winds Friday will be mainly out of the west or northwest at 10 to 15 MPH with local gusts to near 30 MPH along the west side during the later afternoon or evening hours, continuing through Saturday.
Rain: Expect dry weather through at least Monday morning. Models are definitely at war with one another on how to project Tropical Storm Rosa which will be moving northwestward well off the Baja coast this weekend. By Sunday, Rosa will take a jog towards the northeast, possibly moving inland through northern Baja or even a slight chance into extreme southern California. Models also show a trough of low pressure moving through northern and central California Tuesday and Wednesday and place the eastern Pacific high off shore. This could turn the winds from south to north aloft over southern and central California. Theoretically, this could move remnants from Rosa into central California leading to a chance of showers and even thunderstorms. For now, the risk factor remains low as most modeling information show the moisture moving into southern California then off to the northeast further south.
The best course of action for now will be to maintain just a chance of showers in the forecast from Monday night through Wednesday.
The greatest risk will be over Kern County with a decreasing risk factor further north. Keep in mind, this is a tropical system and they are real buggars to forecast.
If the risk factor appears to be increasing, I will be issuing afternoon updates.
Afternoon Dew Points Today: Low to mid 40s. Kern: Low to mid 40s.
Humidity: Visalia: 15%/60% Bakersfield: 15%/35%
Actual Humidity September 25, 2018: Delano, 80%/21%, Porterville, 83%/15%
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 90% tomorrow 80% Bakersfield: Today: 90% Tomorrow: 90%
ET Rates Over the Past Seven Days: Stratford 1.49, Parlier 1.31, Blackwell 1.49, Lindcove 1.30, Arvin 1.52, Orange Cove 1.44, Porterville 1.20, Delano 1.32, Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 71, Parlier 72, Blackwell 81, Lindcove, 73, Arvin, 72, Orange Cove 73, Porterville 78, Delano 71
Record Temperatures: 107/43. Average Temperatures: 88/56
Cooling Degree Days this Season: 2010 +451
Courtesy of the NWS
Average temperature for September so far: 75.5 +1.5
Precipitation: Seasonal total/average/above or below average:
Since Oct 1, 2017 Fresno: 6.73 season. or -4.72. Month to Date: .00
Since Oct 1, 2017, Bakersfield: 3.93, or -2.50. 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: 6:51 am Sunset: 6:48 pm. Hours of Daylight: 11:57
Yesterday’s Weather:
MAE : Madera 253 : DH1700 / 97 / 55 / 0.00 /
FAT : Fresno Airport 333 : DH1700 / 95 / 62 / 0.00 /
HJO : Hanford Airport 242 : DH1700 / 95 / 53 / 0.00 /
NLC : Lemoore Naval AS 234 : DH1700 / 95 / 54 / 0.00 /
BFL : Bakersfield Airport 496 : DH1700 / 94 / 63 / 0.00 /
VIS : Visalia Airport 292 : DH1700 / 93 / 55 / 0.00 /
ATEC1 : Avenal 787 : DH1655 / 92 / 60 / 0.00 /
PTV : Porterville Airport 442 : DH1700 / 94 / 56 / 0.00 /
TFTC1 : Taft 759 : DH1659 / 91 / 70 / 0.00 /
LOSC1 : Los Banos 120 : DH1600 / 92 / 58 / 0.00 /
Rainfall: Water year Oct 1st through September 30th
Year % Last Y. % Ave. Annual ave.
STOCKTON 0.00 9.22 66 21.79 156 13.98 14.06
MODESTO 0.00 8.17 63 16.93 130 13.03 13.11
MERCED 0.00 7.06 57 16.05 129 12.44 12.50
MADERA 0.00 7.22 60 14.26 119 11.97 12.02
FRESNO 0.00 6.73 59 17.36 152 11.45 11.50
HANFORD 0.00 4.70 47 11.21 111 10.06 10.10
BAKERSFIELD 0.00 3.95 61 8.34 129 6.45 6.47
BISHOP 0.00 3.08 60 9.18 179 5.12 5.18
SALINAS 0.00 7.16 56 16.49 129 12.78 12.83
PASO ROBLES 0.00 9.62 76 16.17 127 12.71 12.78
SANTA MARIA 0.00 6.01 43 18.91 136 13.91 13.95
Next report: Thursday, September 27