February 18, 2018
Summary: The leading edge of the cold air mass has now moved through the Sacramento Valley and is entering the northern San Joaquin Valley. Even though temperatures are quite pleasant this afternoon, this will change in a hurry tonight through Thursday. Light snow showers are occurring over many mountain areas of northern California. A few snow showers are now beginning to show up just north of Yosemite.
As the low carves out an Arctic trough of low pressure over the interior west, and strong upper level high pressure builds along the Pacific coast and into Alaska, California will find itself right between these two features. This will create a classic freeze configuration. Already this afternoon, winds are picking up out of the northwest at around 10 to 20 MPH and they will only increase tonight and Monday as pressures fall dramatically east of the Sierra Nevada.
Tuesday, Wednesday, and possibly Thursday are the nights I’m most concerned about as winds die off and dew points settle in the low to mid 20s. widespread mid to upper 20s are likely which is discussed in detail in the frost discussion.
Models this afternoon also indicate there may be enough available moisture for isolated showers over the valley, but just about all the action…minimal as it may be…will be over the Sierra Nevada and the Kern County mountains with snow down to 1,000 to 1,500 feet.
Models are also a bit more interesting for Thursday night and Friday. Another very cold low will quickly drop southward and into central California. This system also has its origins in western Canada. There will be a chance of light showers during this time frame with snow again down into the foothills.
Temperatures will remain below average through the weekend and more than likely for next week, as well. However, next week, the flow aloft should be more out of the northwest than directly out of the north as our current configuration is.
Forecast: Becoming partly cloudy tonight and Monday with a slight chance of isolated light showers later tonight and Monday morning. Turning colder. Expect strong gusty northwesterly winds through Monday. Becoming mostly clear Monday night through Wednesday night. Increasing cloudiness Thursday, leading to at least a small chance of light showers Thursday night and Friday. Mostly clear to occasionally partly cloudy Friday night through Sunday.
Short Term:
| Madera 35/53/25/58 | Reedley 34/54/25/54 | Dinuba 33/53/25/54 | |
| Porterville 33/54/25/54 | Lindsay 33/53/24/53 | Delano 35/55/26/55 | |
| Bakersfield 37/54/29/54 | Arvin 37/53/27/54 | Taft 43/54/28/55 | |
| Lamont 37/54/27/55 | Pixley 35/53/25/54 | Tulare 34/53/24/53 | |
| Woodlake 34/54/25/54 | Hanford 34/54/26/55 | Orosi 33/53/24/53 | |
Winds: Winds will increase out of the northwest at 15 to 25 MPH through Monday with gusts to near 40 MPH possible along the west side. Winds will diminish Monday evening, generally becoming light after midnight. It’s possible winds may remain in the 8 to 15 MPH range along the west side Monday night with light winds throughout the valley Tuesday through Wednesday.
Rain: The very cold upper low is currently dropping into northern California. Snow and rain showers are occurring in many locations north of a Bay Area/Yosemite line. Snow showers will spread down the Sierra Nevada tonight with the snow level possibly lowering to 1,000 feet by Monday morning. This is a very moisture starved system, but with a 150 MPH jet stream whipping along above us, there may be enough lift to the atmosphere for a few light showers over the valley floor. Expect dry weather Monday afternoon through Thursday. Models are now suggesting showers may occur Thursday night through Friday from yet another semi Arctic type system. Some models actually give a 60% chance of measurable rain. I’m a bit skeptical of this, but a chance of light showers does seem warranted to add to the report for Thursday night and Friday. From Saturday through the middle of next week, dry conditions will prevail.
Frost Discussion: All locations will be above 32 degrees tonight, but possibly a few river bottom locations may dip into the lower 30s where winds die off and skies are generally clear. The leading edge of the cold air mass has now reached into the northern San Joaquin Valley in the form of a dry cold front. This will rapidly move through the valley tonight. It’s the cold upper low and an aggressive north to south flow from western Canada and into California which will lead to a hard freeze for Tuesday through Thursday mornings. Thursday, though, may see some moderation if clouds arrive in time ahead of another Arctic system which will be diving southward into California. Lows Tuesday morning will drop like a rock into the mid to upper 20s on a widespread basis with coldest locations possibly down to 22 to 23. Under ideal frost conditions in low lying spots, temperatures could be at or below 28 degrees for up to 8 hours.
The inversion Tuesday morning will be relatively weak with temperatures no more than 2 to 4 degrees warmer, possibly less at some locations. Wednesday morning may be equally as cold as generally quiet weather will prevail under mostly clear skies. Thursday morning should see an average of 2 degrees of moderation, but some clouds could arrive during the early morning hours, in which case readings would be somewhat milder.
On Thursday night and Friday, another Arctic type low pressure system will dive southward into central California with even a light chance of showers. Snow will again be down into the foothills. On the flip side, the air behind this system is also cold which, in theory, would keep overnight lows below freezing through the weekend.
More of a northwesterly flow will develop next week, which is somewhat milder. We’ll just have to wait and see if cloud cover arrives. If not, readings could easily be in the low to mid 30s most nights.
Lows Tonight:
All locations will be above freezing tonight.
Next Report: Monday morning/February 19