December 19, 2017
Summary: An impressive looking low pressure system is currently diving southward off the coast of the Pacific Northwest. The associated cold front is already moving through southern Oregon and will move as far south as Merced County Wednesday morning, moving quickly down the valley during the day and exiting the region by evening. Satellite imagery shows a popcorn appearance to the cloud cover behind the front. This is indicative of very cold air. This air will be invading the valley Wednesday afternoon and night.
In the meantime, after the trough goes through, a low center will develop over Utah and northern Arizona while a big upper high juts northward into Alaska and the Yukon Territory of Canada. This will create almost a north/south trajectory of the winds aloft and will also generate a brief but strong off shore flow. The main concern is for Friday and Saturday mornings when widespread low to mid 20s are likely with continuing very cold conditions Sunday morning, as well.
If some of these models are correct, there could even be an isolated pocket or two out there that could briefly dip into the upper teens, although that’s the minority view.
From the 26th through the 1st, only slow moderation will occur as a layer of cold dry air settles into the lower thousand feet of the atmosphere and onto the valley floor. Where dew points end up will be the prime factor as to just how cold this cold string of nights will be.
For now, models do not look favorable for rain after tomorrow through New Year’s. It’s possible both Fresno and Bakersfield could be completely dry for the entire month of December, although a few hundredths of an inch are possible Wednesday as the front moves through.
Forecast: Mostly clear to occasionally partly cloudy this evening. Becoming mostly cloudy late tonight. Mostly cloudy Wednesday with a chance of light showers. Rapid clearing Wednesday night with the possible exception of Kern County where upslope clouds may develop against the north facing slopes of the Tehachapi Mountains. Lingering clouds in Kern County Thursday morning. Otherwise it will be mostly clear and cold Thursday and potentially very cold Thursday night. mostly clear Friday and mostly clear to occasionally partly cloudy at times Saturday through Tuesday.
Short Term:
| Madera 35/54/25/52 | Reedley 33/56/24/53 | Dinuba 34/55/25/52 | |
| Porterville 33/56/25/53 | Lindsay 32/56/24/53 | Delano 36/56/26/53 | |
| Bakersfield 37/56/29/55 | Arvin 33/56/25/53 | Taft 41/56/30/54 | |
| Lamont 36/56/29/55 | Pixley 34/55/25/52 | Tulare 32/55/24/53 | |
| Woodlake 32/55/24/53 | Hanford 32/55/24/53 | Orosi 32/55/25/53 | |
Winds: Winds will be generally less than 10 MPH tonight, becoming out of the southeast after midnight. Winds Wednesday will be out of the northwest at 10 to 20 MPH with gusts to 35 MPH possible along the west side. Winds Wednesday night will be out of the north to northwest at 10 to 15 MPH along the west side and will be light elsewhere. Winds Thursday and Friday will be generally less than 10 MPH with periods of near calm conditions.
Rain: A rapidly moving cold front will move down the valley Wednesday for a chance of light showers along the cold front. Any chance of precipitation will be over by late afternoon or early evening. Rainfall amounts will range from nothing to possibly .05. expect dry weather Wednesday night through Christmas Day. Even though models vary, they indicate the possibility of rain is quite low from the 26th through New Year’s Eve.
Frost Information: some of the coldest locations tonight may briefly make it to the 32 degree mark or a tad below, generally for just a short time before increasing clouds during the early morning hours begin to shut down the radiational cooling effect. Most locations will end up in the low to mid 30s tonight with a chance coldest locations could drop to 29 to 32. Of course, the main concern is for Thursday through Sunday mornings. As cold air is squeezed southward between a high building into the Yukon Territory and a low center over Utah and Arizona. Lows Thursday morning will be on the chaotic side as wind conditions and the associated mixing will likely drive temperatures all over the place. We may even see some upslope clouds against the north facing slopes of the Tehachapi Mountains in Kern County, but that’s not a guarantee. Lows Thursday morning in areas with little wind or mixing and a clear sky could drop down to 22 to 25 with most locations between 23 and 28.
Above freezing temperatures are even possible along the west side as wind conditions could stay up all night. But even there, if winds die off, those frigid temperatures are possible.
Friday and Saturday mornings are of a concern as low to mid 20s still seem likely throughout the region. One model even suggests river bottom locations could briefly dip below 20, although that’s not the majority consensus. There will likely be some modification Saturday morning with subfreezing conditions continuing Christmas Eve and Christmas Day.
After Christmas, very slow modification is anticipated, but even then, until some kind of weather system exchanges the air mass out of here, frigid conditions are possible.
Lows Tonight:
| Terra Bella
31 |
Porterville
AF |
Ivanhoe
32 |
Woodlake
AF |
| Strathmore
AF |
McFarland
31 |
Ducor
AF |
Tea Pot Dome
AF |
| Lindsay
30 |
Exeter
29 |
Famoso
AF |
Madera
AF |
| Belridge
32 |
Delano
AF |
North Bakersfield
AF |
Orosi
31 |
| Orange Cove
32 |
Lindcove
29 |
Lindcove Hillside
AF |
Sanger River Bottom
28 |
| Root Creek
32 |
Venice Hill
32 |
Rosedale
AF |
Jasmine
32 |
| Arvin
AF |
Lamont
AF |
Plainview
32 |
Mettler
AF |
| Edison
AF |
Maricopa
32 |
Holland Creek
AF |
Tivy Valley
32 |
| Kite Road South
AF |
Kite Road North
31 |
Next Report: Wednesday morning, December 20