December 14, 2018
Summary: Extensive cloud cover continues to move over central California ahead of an approaching and weakening trough of low pressure which will spread precipitation over parts of northern California tonight. However, the frontal system will wash out before it reaches central California. A weak ridge will very temporarily move in from the eastern Pacific Saturday afternoon through Sunday morning. While that’s occurring, a powerful low off the coast of British Columbia will dig a trough of low pressure down into California. Light rain will spread as far south as Fresno County by probably roughly midnight Sunday, breaking off into light showers over the south valley late Sunday night and Monday. It’s possible orographic lift could produce about .75 over the foothills and mountains, but generally less than .25 is expected over the valley floor with even lighter amounts towards the extreme south valley.
By late Monday afternoon, the frontal system will push into Nevada with lingering showers over the Sierra and possibly the valley facing slopes of the Tehachapi Mountains. A strong upper high will begin to take shape Tuesday just off the southern California coast, driving the next series of storms northward into the Pacific Northwest. The main challenge, especially from midweek on, will likely be extensive fog and/or low clouds with a good chance of partial clearing in some areas during the afternoons. A weak trough will temporarily move through Saturday, but any precipitation will remain well to our north. The only question is whether there will be enough low level wind energy to break up the warm air inversion.
For now, next week looks dry as a high center develops over northern Baja, maintaining the storm track well to our north. The two week model is now calling for average precipitation, meaning there’s roughly a 50% chance of either wet or dry weather after Christmas.
Forecast: Mostly cloudy before midnight. Partly cloudy after midnight through Saturday night with areas of night and morning valley fog. Increasing cloudiness by Sunday afternoon. Rain will be likely Sunday night, mainly after midnight. Periods of light rain from Fresno County north late Sunday night and Monday morning with light showers in the south valley. A chance of showers Monday afternoon, mainly in Kern County. Mostly cloudy Monday night through Tuesday morning. Clearing Tuesday afternoon. Mostly clear Tuesday night with areas of fog developing. Wednesday through Friday will see extensive areas of fog and/or low overcast with a chance of afternoon clearing.
Short Term:
| Madera 36/60/37/63 | Reedley 35/61/36/63 | Dinuba 34/59/36/62 | |
| Porterville 36/62/37/64 | Lindsay 34/61/36/65 | Delano 37/62/38/65 | |
| Bakersfield 40/64/42/68 | Taft 44/63/44/67 | Arvin 37/65/39/67 | |
| Lamont 38/63/38/67 | Pixley 36/60/37/64 | Tulare 35/59/37/63 | |
| Woodlake 35/61/37/63 | Hanford 37/61/38/64 | Orosi 34/61/36/63 | |
Winds: Winds will be generally at or below 15 MPH through Monday with periods of near calm conditions.
Rain: Dry conditions will continue through Sunday. The chance of rain over Fresno and Madera Counties will begin to increase about midnight Sunday. Light showers will spread into the south valley during the early morning hours, lasting through later Monday morning, tapering off into a chance of showers Monday afternoon, mainly in Kern County. Dry weather will return Monday night and prolonged period of dry weather will be underway, lasting through next week and possibly into the following week, as well. Rainfall amounts from the Sunday/Monday event will be generally less than .25 over Fresno and Madera Counties, .10 to .20 over Kings and Tulare Counties and generally at or less than .10 over the valley portion of Kern County.
Frost Discussion: All locations will be above freezing tonight, but at or slightly above freezing in the coldest locations. Cloud cover will continue to stream in from the west during the first part of the night, breaking off to partly cloudy skies after midnight. I feel there will be enough low level wind energy to mix out the lower portion of the atmosphere and keeping most locations in the mid to upper 30s, possibly higher in some areas. I’m anticipating mid 30s to lower 40s Sunday morning, as well. We could see some cloud cover ahead of a Pacific front that will be moving down the valley Sunday night and Monday, keeping temperatures above freezing.
From Wednesday through the remainder of next week, a strong warm air inversion will develop, resulting in extensive fog and low clouds with partial afternoon clearing. Once the fog lifts into a low overcast, it’s possible we could see little difference between daytime highs and overnight lows. Dry weather will continue well into the following week. I did note that one model this afternoon is showing a possible brief north/south period of winds aloft beginning the day after Christmas and lasting through the following day. It could result in a cooler air mass moving in, but it’s much too far away to even begin to talk numbers.
Next report: Saturday morning/December 15