December 20, 2019
Summary: Temperatures as of 1:00pm were climbing into the upper 50s and lower 60s, despite the amount of cirrus clouds moving in from the west. The freezing level above Vandenberg has climbed all the way to 12,100 feet as warm air moves in aloft ahead of a developing trough of low pressure. That trough stretches from northeast to southwest from British Columbia to roughly 800 miles off the central coast. As the trough approaches, significant differences in pressure will set up between the interior west and off shore. Winds could increase near the base of the Tehachapi Mountains as early as late tonight. they’ll slowly increase Saturday all the way into Sunday morning before decreasing Sunday afternoon as the trough begins to move on shore behind a cold front. More is discussed in the wind summary below.
High clouds will slowly begin to thicken and lower Saturday with precipitation spreading in ahead of a cold front during the day Sunday. Models continue to indicate strong rain shadows will develop along the west side and, of course, in Kern County. This could affect rainfall amounts even on the east side before the air is lifted over the Sierra Nevada where heavier amounts will fall. Once the trough sets up over and along the west coast Sunday, it will dominate our weather all the way through the day after Christmas. There will be periodic chances of rain during this entire time with possibly a break Christmas Eve afternoon and night.
A very cold low will move in on Christmas Day, renewing the chance of showers with snow possibly down into the higher foothills. Yet another system will dive southward the day after Christmas, however it’s unclear at this time whether most of the energy will dive into Nevada or if the low will pass far enough to the west for additional cold precipitation.
After Thursday, a chilly north/northwest flow will fill in behind the trough which by then will be moving into the Rockies, possibly setting the stage for some frosty mornings, although that is not a high confidence forecast for now. We’re in the heart of fog season, so it’s possible fog and low clouds could be major factors between next Friday and the first of the year.
Forecast: Partly cloudy tonight. increasing cloudiness Saturday. cloudy Saturday night. periods of rain Sunday through Monday night. Showers likely Christmas Eve morning, becoming partly to mostly cloudy Tuesday afternoon and night. a chance of showers Christmas Day through Friday.
Short Term:
| Madera 36/64/40/60 | Reedley 36/64/41/61 | Dinuba 34/63/40/60 | |
| Porterville 35/65/41/63 | Lindsay 34/64/40/62 | Delano 37/65/42/61 | |
| Bakersfield 43/70/50/65 | Taft 45/68/50/65 | Arvin 43/71/44/65 | |
| Lamont 41/69/47/65 | Pixley 37/66/41/63 | Tulare 35/63/40/60 | |
| Woodlake 36/64/41/61 | Hanford 37/65/42/62 | Orosi 34/65/40/61 | |
Winds: Winds this evening will be at or less than 7 MPH with periods of near calm conditions. In Kern County, we could see winds begin to increase at locations like the bottom of the Grapevine before sunrise with strong, gusty, south to southeast winds possibly exceeding 50 MPH near the base of the Tehachapi Mountains Saturday through Sunday morning. wind gusts in excess of 35 MPH are possible as far north as Bakersfield. North of Kern County, winds late tonight through Sunday morning will be generally out of the east to southeast at 10 to 20 MPH with stronger gusts, mainly from Fresno County northward. Winds gusting near 40 MPH are possible along the Interstate 5 corridor Saturday into Sunday morning. later Sunday afternoon through Monday, winds will generally be out of the southeast at 8 to 15 MPH with stronger gusts.
Rain: The chance of rain will begin to increase as early as Sunday morning, becoming likely at times Sunday afternoon through Tuesday morning. models do suggest that this event will have a strong rain shadow along the west side and in Kern County. This shadow could extend over much of the valley, really zapping the potential rainfall amounts. Rainfall amounts along the west side will range from probably no more than a tenth or two and maybe .10 to .15 in the valley portion of Kern County. In Madera County and eastern Fresno County, amounts should range between .20 and .33. If timing is correct, we should see a dry slot Christmas Eve afternoon and night. right behind Santa, however, more showers should increase Christmas Day with a continuing risk of showers Thursday with even a slight risk on Friday.
Frost Discussion: All locations will be above freezing tonight but only slightly above in the coldest locations. High clouds and a southeasterly surface flow up the valley will keep most locations in the mid 30s to the lower 40s. we’re entering an active pattern now which will keep temperatures above freezing through probably Friday of next week. It’s possible that on any relatively clear night between systems, lower 30s could occur, but for now that’s not in the forecast. After Friday, we could see some frost nights as the flow aloft on most models is out of the north/northwest, generally overwater, precluding any chance of a major freeze event.
Next report: Saturday morning/December 21