February 15, 2019
Summary: Right on cue, a line of thunderstorms has developed in Fresno County. In fact, it just went through the city of Fresno within the past hour. Isolated thunderstorms will continue to be possible into the evening hours. Low pressure is now over northern California with a cold northwest flow swinging into central California. Heavy snow is occurring along the entire Sierra Nevada above roughly 3,500 to 4,000 feet. It will slowly lower through the weekend as each wave of low pressure will be colder than the one before. Snow levels could potentially reach 1,500 feet Sunday and Sunday night, bringing snow to the lower foothills.
Thunderstorms will again be possible Saturday and Sunday afternoons and evenings, especially as sunshine reaches the ground, warming the earth and allowing currents of warm air to move skyward. It then mixes with very cold air aloft, creating volatility and eventually forming thunderstorms. There will be a chance of thunderstorms at any given time from now through Sunday night and early Monday morning. Rainfall amounts will vary from no more than a tenth or two to well over a half inch in those locations in the path of a thunderstorm.
The cold trough will finally shift eastward Monday. On both Monday and Tuesday we will see a north/northeast flow wrap around the back side of the exiting arctic low, pumping very cold air into the valley. We could possibly see some well below freezing temperatures Monday but more likely Tuesday, which is discussed in the frost section below.
Clouds will be on the increase once again Wednesday as the next modified arctic system dives southward from northwest Canada and into northern and central California. This system appears to be taking more of an overland path, meaning it may carry only minimal amounts of moisture. Still, a chance of light showers with very low snow levels can be expected Wednesday afternoon into Thursday. This pattern is not going to go away any time soon as models for next weekend show a broad area of arctic low pressure extending from central Canada to off shore California. This would allow impulses of very cold waves of low pressure to move through from time to time with repeated chance of showers later next weekend and into the following week. After that, models do trend towards the dry side.
The two week model looks fairly dry, but also gives an 80% chance of well below average temperatures through the first of March.
Forecast: Showers and isolated thunderstorms through this evening, tapering off for a while after midnight. Showers will increase again by mid morning with periods of showers Saturday afternoon through Sunday night and a chance of isolated thunderstorms both Saturday and Sunday afternoons. Any thunderstorms that develop will be accompanied by localized heavy rain and hail. Partly cloudy later Monday. Mostly clear to occasionally partly cloudy Monday night through Tuesday night. increasing cloudiness Wednesday leading to a chance of light showers later Wednesday afternoon through Thursday with very low snow levels. Partly cloudy Thursday night and Friday and continued cold.
Short Term:
| Madera 39/51/38/48 | Reedley 40/52/38/49 | Dinuba 38/51/37/47 | |
| Porterville 39/52/37/49 | Lindsay 38/52/37/48 | Delano 40/52/39/49 | |
| Bakersfield 41/52/39/49 | Taft 41/52/37/50 | Arvin 41/50/37/48 | |
| Lamont 40/52/39/50 | Pixley 38/51/38/48 | Tulare 38/50/37/48 | |
| Woodlake 39/51/38/48 | Hanford 38/51/38/49 | Orosi 38/50/37/49 | |
Winds: Winds will be mainly out of the south to southeast at 10 to 15 MPH through Saturday night with gusts to near 25 MPH near showers and especially thunderstorms. Winds Sunday will be out of the northwest at 10 to 20 MPH with stronger gusts, diminishing Sunday evening and becoming generally light after midnight. Winds will be mainly out of the northwest Monday at 5 to 10 MPH.
Rain: There are some briefly very heavy thunderstorms pounding from north of Hanford to the east of Sanger at this hour which are accompanied by heavy rain and hail. Storms could pop up anywhere but especially north of Kern County this afternoon and evening. There’s a chance of thunderstorms Saturday and Sunday afternoons and evenings, as well. Rainfall amounts from now through Sunday night will vary widely. Some locations may only record a tenth or two, but as is being demonstrated this afternoon, locations hit by a thunderstorm could pick up more than a half inch along with small hail and localized gusty winds.
Showers will begin to taper off after midnight Sunday night, followed by roughly 72 hours of dry weather. The chance for scattered light showers will increase again later Wednesday afternoon through Thursday. This system is also very cold and will potentially take an overland trajectory, meaning moisture will be limited.
Dry weather will return Friday through Saturday, however some of the medium range models are indicating an increasing chance of showers again during the second half of next weekend as a broad arctic trough extends from central Canada to off the central and southern California coast.
Models for later next week look considerably drier, as does the two week model which now extends through the first of March.
Frost Discussion: The very active weekend has begun with periodic showers expected well into Monday night. Monday morning has the potential of dropping into the 27 to 31 degree range but only under ideal frost conditions, such as at least several hours of mostly clear skies and little to no wind. It’s possible residual moisture in the form of cloud cover may bank up against the west facing slopes of the Sierra Nevada and north facing slopes of the Tehachapi’s which, in theory, would keep temperatures in the lwo to mid 30s in those areas. There’s no guarantee of this, however. The potential Tuesday morning for readings down into the 27 to 31 degree range will be higher as for now we expect skies to be relatively cloudless and winds to be light to calm. It’s possible an isolated river bottom with sandy soil could drop down to 25 or so, but that would certainly be an outlier. Wednesday morning’s temperatures will highly depend on the arrival of cloud cover from the next modified arctic low moving in from Canada. If clouds arrive in a timely manner, temperatures will remain in the 30s. if not, upper 20s and lower 30s cannot be ruled out. Low to mid 30s are certainly possible Friday morning then hopefully, over the weekend, a broad area of low pressure will stretch from central Canada to off the central and southern California coast. This would favor more showers with very low snow levels, especially during the second half of the weekend and into early next week. Conditions for later next week appear dry but still cold. For now, we’ll keep frost out of the forecast for that time frame, but my confidence level on this is low. As stated above, the two week model gives an 80% chance of well below average temperatures right into the first day or March.
Next report: Saturday morning/February 16