December 8, 2018
Summary: Upper level high pressure is now directly overhead. The freezing level this morning above Vandenberg AFB had jumped to 11,800 feet. Most locations as of 1:00pm had decent highway visibilities. The ground fog this morning has lifted into a low overcast. Over Bakersfield, the overcast was based at 1,000 feet and just 600 feet over Porterville, 900 feet over Visalia, and Fresno was reporting breaks in the overcast. Some areas will continue to slowly clear before the afternoon is up. Where it does clear, radiational cooling will occur and with dew points in the upper 40s, widespread ground fog will again develop, as early as this evening in some areas. The fog will again rise a few hundred feet off the valley floor by Sunday afternoon with partial afternoon clearing in some areas, though some areas will not clear.
The high will shift eastward Monday, allowing a weak trough of low pressure to move through Monday night and early Tuesday. It appears shower activity will progress no further south than a Monterey/Merced/Yosemite line. This will be quickly followed by an inside slider, a low moving quickly through the Pacific Northwest and in to the interior west Wednesday. The main challenge for Tuesday and Wednesday will be to try to discern if there will be enough low level wind activity to rid the valley of fog and low clouds.
A flat zone of upper level high pressure will extend from the eastern Pacific and across California then into the Great Basin Wednesday through next weekend. Generally, a westerly or zonal flow will maintain above average temperatures above the valley floor. On the valley floor itself, temperatures will be determined by the coverage of fog and low clouds.
Forecast: Widespread fog and low clouds redeveloping tonight through Sunday morning with clearing in some areas during the afternoon. Fog and low clouds Sunday night into Monday morning, becoming mostly cloudy Monday afternoon through Tuesday. Partly cloudy Tuesday night and Wednesday with areas of night and morning fog. Mostly clear Wednesday night through Saturday with decreasing amounts of night and morning fog.
Short Term:
| Madera 37/56/37/57 | Reedley 38/57/39/57 | Dinuba 37/54/37/55 | |
| Porterville 39/57/39/57 | Lindsay 37/57/37/58 | Delano 40/57/41/57 | |
| Bakersfield 44/59/43/58 | Taft 44/62/44/59 | Arvin 41/58/43/57 | |
| Lamont 40/59/41/58 | Pixley 38/57/38/58 | Tulare 37/56/37/57 | |
| Woodlake 38/57/38/58 | Hanford 39/58/39/57 | Orosi 37/58/37/57 | |
Winds: Winds will be generally at or below 15 MPH through Tuesday with periods of near calm conditions.
Rain: Expect dry weather through most of the day Monday and more than likely all of next week. A weak trough will move through Monday night and Tuesday morning but for now it appears rain will progress no further south than a Monterey/Merced/Yosemite line. After Tuesday, it still appears the storm track will migrate back into the Pacific Northwest through Sunday and possibly the first few days of the next week.
Frost Discussion: All locations will be above 32 degrees tonight through Monday night. A low pressure system will be moving rapidly through the Great Basin on Wednesday. On the back side of the low, a brief north/northwest flow will develop, moving marginally cooler air into the region. The big question is whether enough low level wind energy will occur to rid the valley of its fog and low clouds. If dew points remain as they are now, the fog regime will continue and above freezing conditions will be maintained. If skies clear out for a few nights, low to mid 30s will be possible. Overall, however, generally a west/northwest flow will move across the eastern Pacific and into California, keeping temperatures quite acceptable.
Next report: Sunday morning/December 9