December 24, 2018
Summary: Santa has read his weather report and checked it twice. He, along with his reindeer, will be soaking wet when he moves through the valley. Nevertheless, he guarantees me the job will be done. We have been in touch so he knows to wear his waterproof coat this year.
The center of circulation of our Christmas Eve storm is just off the northern California coast with its associated cold front ranging from near Redding southwestward out to sea near Marin County. This storm is rolling southeastward at a pretty good clip so light showers are possible by early evening with the main event during the overnight hours. Some of the models this afternoon even indicate a small chance of isolated thunderstorms later tonight and early Christmas morning. Since this is a relatively fast moving event, most of the active weather will have ended no later than midmorning, if not before.
Lingering showers will continue through the day over the Sierra Nevada and Kern County mountains. However, for all intent and purposes, the rain will be over for the valley floor.
A relatively strong push of northwesterly winds will follow the low, creating upslope conditions against the Kern County mountains and, to a lesser extent, the western facing slopes of the Sierra Nevada, especially in Tulare County. Clearing should take place as early as Christmas afternoon along the west side as drier air penetrates the west side of the valley. The air mass behind the exiting system is colder but not excessively so.
A second system is already moving out of the Gulf of Alaska and will charge through the Pacific Northwest then into the Great Basin Thursday. No precipitation is expected over the valley with just a small chance of snow showers over the high country. Behind this system, the winds at both the surface and aloft will become north/northeast. This always makes for somewhat of a difficult forecast as far as the fog is concerned. It’s possible these off shore winds will blow over the top of the valley, leaving the valley floor relatively undisturbed. More often than not, though, dry air moves down the west side and eventually fills the valley, leading to a greater chance of frost Friday through Sunday mornings. For now, nothing critical is expected.
Models this afternoon are again different for the pattern beginning New Year’s Eve and lasting through January 3. Our projected massive high still shows up over the eastern Pacific, however the westerlies are shown trying to break through into the Pacific Northwest. If this occurs, it would block the potential modified arctic air mass from moving into California. By no means am I eliminating the chance of a cold weather episode beginning the first of the year, but this afternoon’s models are somewhat of a Christmas gift, if indeed Mother Nature follows suit.
Forecast: Periods of rain spreading southeastward down the valley this evening, continuing through the night into the predawn hours. A chance of lingering showers for a time Christmas morning. Becoming partly cloudy by afternoon. Mostly to partly cloudy Tuesday night and Wednesday morning, especially in Tulare and Kern Counties with partly cloudy skies elsewhere. Partly cloudy Wednesday night through Thursday. Becoming mostly clear Thursday night and Friday. Mostly clear to occasionally partly cloudy Friday night through New Year’s Eve.
Short Term:
| Madera 47/54/37/54 | Reedley 49/55/37/54 | Dinuba 46/53/36/53 | |
| Porterville 47/53/38/55 | Lindsay 46/53/36/54 | Delano 48/55/40/55 | |
| Bakersfield 49/54/40/55 | Taft 49/56/42/55 | Arvin 48/53/40/55 | |
| Lamont 48/55/41/55 | Pixley 47/54/38/54 | Tulare 46/53/36/54 | |
| Woodlake 47/54/36/54 | Hanford 48/55/37/55 | Orosi 46/54/36/54 | |
Winds: Winds will be mainly out of the southeast tonight at 5 to 15 MPH, continuing through the late evening hours. Winds later tonight and Christmas Day will be out of the northwest at 10 to 20 MPH, decreasing to 5 to 10 MPH Christmas night. winds Wednesday and Thursday will generally be light and variable with the possible exception of the far west side which may observe winds out of the north or northeast at 10 to 20 MPH.
Rain: Light rain has progressed down to San Francisco with a few light showers showing up northwest of Monterey Bay. Periods of light rain will spread rapidly southeastward over the valley this evening. A couple of models even show a slight chance of isolated thunderstorms overnight, but if this occurs at all, it would be very isolated. Lingering showers may last into mainly early Christmas morning with dry weather returning later in the morning and through the night. dry weather will begin Wednesday and continue through the remainder of the year and at least through the first few days of January. Rainfall amounts for mainly tonight and early tomorrow may range from .25 to .33 from Fresno County northward, possibly upwards of .25 in eastern Tulare County and .10 to .20 over western Tulare County, and Kings and Kern Counties.
Frost Discussion: All locations will be above freezing Christmas morning and more than likely Wednesday morning, as well, due to cloud and wind conditions. We should observe variable amounts of cloud cover Thursday morning which should keep most locations in the low to mid 30s. low pressure will be gliding through the Great Basin Thursday followed by a north/northeast flow Thursday night through Saturday. The flow both at the surface and aloft will be off shore, moving drier air down the west side of the valley and possibly the remainder of the valley. If fog and/or low clouds take over, conditions will be milder. For now, temperatures from 27 to 30 seem plausible for Friday through Sunday mornings.
Models have flip flopped again in trying to nail down a pattern for New Year’s Eve through January 3. That massive upper high over the eastern Pacific still tries to build into Alaska, but about the 2nd, some models show westerly winds aloft trying to break into the Pacific Northwest. This would be very effective in blocking modified arctic air from moving into central California. Considering the inconsistencies on models, we cannot discount the possibility of arctic air moving into our region, but hopefully we’ll get a Christmas present and these later model runs will be what occurs.
Next report: Tuesday morning/Christmas Day