November 18, 2019
Summary: Skies are clear over central California but are still hazy. To our south, clouds are increasing over the southern ¼ of California and to our north they are increasing over northwest California. The center of circulation of a developing low pressure system is west of Portland, Oregon this evening and will move rapidly southeastward into northern and central California Tuesday afternoon. In the meantime, a cutoff low off the northern coast of Baja, which has tapped into the subtropics, will spread showers and possible thunderstorms over much of southern California Tuesday into Wednesday as the northern system spreads showers over northern and central California during the same time frame.
Models show the center of circulation of this storm moving over northern California Tuesday evening and center it somewhere near Santa Barbara Wednesday morning. The counterclockwise circulation around the low will have winds out of the northeast above central California, creating somewhat of a reverse rain shadow. The Owens Valley side of the Sierra Nevada will be on the upslope side, receiving the heaviest precipitation while the San Joaquin side will be robbed of moisture, thus rainfall amounts will be quite light. As stated in the morning report, heaviest precipitation will be along the Sierra Nevada foothills and possibly over the valley portion of Kern County.
By Wednesday evening, the storm will have already progressed over southeast California and western Arizona for a decreasing chance of showers by Wednesday evening. The low will race eastward Thursday into the Four Corners region for a return to dry but cool weather.
Models have changed somewhat for the basic pattern Friday through Sunday. Some models are showing an upper low just off the central coast, meaning pressure patterns over central California will be quite weak. As a result, no significant warm up will occur. Fog will become more of a problem, as well, unless that off shore flow develops enough lift to keep the potential inversion over the valley floor too weak. At any rate, temperatures Saturday and Sunday will only rise into the mid to upper 60s.
A cold low will drop southward from western Canada Monday and Tuesday and into the interior west, but there won’t be any precip associated with it. The flow aloft on the back side of this system will create a brief northerly flow over California, possibly injecting colder, drier air into the valley with possible local frost as early as Monday morning with a greater risk Tuesday and Wednesday. no real cold weather episode is expected.
Forecast: Mostly clear tonight with patchy fog late tonight and early Tuesday morning. Increasing clouds on Tuesday with a chance of showers by evening. Light showers Tuesday night through Wednesday. a slight chance of showers Wednesday evening with mostly cloudy conditions later Wednesday night through Friday morning. Mostly clear Friday afternoon. Mostly clear to occasionally partly cloudy Friday night through Sunday night with areas of night and morning fog and low clouds. Mostly clear Monday.
Short Term:
| Madera 41/71/45/59 | Reedley 42/73/46/58 | Dinuba 40/71/44/58 | |
| Porterville 41/73/45/59 | Lindsay 40/74/45/59 | Delano 46/74/46/58 | |
| Bakersfield 50/74/48/58 | Taft 53/74/47/59 | Arvin 46/75/46/57 | |
| Lamont 47/74/47/57 | Pixley 41/74/45/59 | Tulare 41/71/44/58 | |
| Woodlake 41/72/45/57 | Hanford 42/73/45/58 | Orosi 40/73/44/58 | |
Winds: Winds will be generally at or less than 6 MPH with periods of near calm conditions tonight and Tuesday morning. Winds Tuesday afternoon and night will be out of the west and eventually the northwest at 10 to 15 MPH with local gusts to 25 MPH. Winds Wednesday through Wednesday evening will be variable at 5 to 15 MPH with locally stronger gusts. Winds Wednesday night and Thursday will be generally at or less than 8 MPH with periods of near calm conditions.
Rain: The players are in motion this afternoon that will lead to an increasing chance of light showers, possibly as early as late Tuesday afternoon. The risk factor will go up Tuesday night, becoming stronger Wednesday morning. Clouds are already increasing both to our south and our north as a low will drop rapidly southward into California Tuesday morning, centering near Santa Barbara by Wednesday morning. Meanwhile, a second low will be moving into southern California and southwest Arizona. It’s not often we have a reverse rain shadow, but on rare occasions they can develop along the Sierra Nevada rather than the Coast Range and that will be the case this time around. The heaviest precipitation will be over the Sierra Nevada and the Owens Valley side of the range. Rainfall amounts on the valley floor from Tuesday night through Wednesday evening will be generally at or less than .10, however amounts upwards to .25 would not be a shock, primarily along the eastern rim of the valley in Tulare County and over the valley portion of Kern County. Models are showing this system as moving faster than earlier projections had indicated, so the bulk of the action will be over by Wednesday evening with dry weather going out from that point into the following week.
Frost Discussion: The air mass behind the incoming low pressure system will be cool, but nothing unusual. Lows Friday through Sunday morning in the coldest locations could tease with the freezing mark, but most locations will be in the mid 30s to the lower 40s. from Monday through Wednesday of next week, there will be the potential for local frost due to a possible cold low diving into the interior west, briefly creating a northerly flow over California. This could, in theory, inject colder, drier air onto the valley floor for at least lower 30s, but I must continue to emphasize nothing unusual is expected.
Next report: Tuesday morning/November 19