February 14, 2019
Summary: It is turning out to be a wild afternoon in central California. The atmospheric river of air which has resulted in 3 to 6 inches of rain over the higher elevations of the Sierra Nevada has now moved southeast of our region. We are now in the conflict zone between colder air moving southward and a layer of warm, moist air already in place. Numerous thunderstorms are breaking out along the Sierra Nevada from the Kern County line northward to Mariposa County. Isolated thunderstorms are beginning to pop in western Fresno County. Very sharp differences in surface pressure has arisen just in a short distance on the valley floor. This has resulted in high winds north of Kern County but Kern County will be on the receiving end next.
Some peak wind gusts as of 2:00pm are as follows: Fresno 47, Visalia 35, Lemoore 40, Porterville reported a wind switch in the last hour with sustained winds of 22, Hanford has gusts to 37, and Madera 39. The latest report out of Bakersfield shows a wind switch with gusts to 37 MPH.
The current temperature at Madera is 66 degrees while up at Modesto it’s just 52. You can see the large differences in temperatures as the cold front marches through.
Showers and thunderstorms will taper off later this evening but then will increase again later Friday as the first of three very cold arctic type low pressure systems dives southward between high pressure off shore and a very cold trough over the Great Basin. Periods of mainly light showers could occur at any time from later Friday through early Monday. With very cold air moving in aloft and the stronger February sun, isolated thunderstorms will again by a possibility each afternoon through Sunday.
Conditions later Monday through Wednesday will be dry but very cold for the time of year. Models have reduced the chance of showers for Wednesday night and Thursday. some other models are showing a different very cold trough moving southward from Canada into the western U.S. next weekend,
This has been an incredibly resilient weather pattern, one that has been absent in recent years. The latest two week model is indicating well below average temperatures continuing through the end of the month with precipitation near to marginally below average.
Forecast: Showers and a chance of thunderstorms through this evening, tapering off later tonight through Friday morning. There will be a high risk of showers at any given time later Friday through early Monday with a chance of isolated thunderstorms each afternoon Friday through Sunday. Thunderstorms, where they do develop, will be accompanied by localized heavy rain and small hail. Partly cloudy Monday afternoon through Wednesday night. mostly cloudy Thursday.
Short Term:
| 43/54/40/52 | Reedley 43/55/40/53 | Dinuba 42/54/39/53 | |
| Porterville 42/54/40/53 | Lindsay 42/55/39/54 | Delano 44/55/41/53 | |
| Bakersfield 45/56/41/55` | Taft 45/56/43/55 | Arvin 44/56/42/54 | |
| Lamont 45/56/41/54 | Pixley 43/55/40/53 | Tulare 43/54/39/52 | |
| Woodlake 43/54/40/53 | Hanford 43/55/41/53 | Orosi 42/53/39/53 | |
Winds: Winds at all locations between Bakersfield and Merced have reported gusts between 30 and 40 MPH within the past 90 minutes. The Fresno Air Terminal reported a gust to 47 MPH. Currently, we are in a conflict zone between the warm moist air of the past couple of days and the cooler air moving in above. As soon as the cold air fills in, the winds will die off and will generally range between 10 and 15 MPH with local gusts to 25 MPH, especially in the vicinity of showers. Winds Friday through Sunday will be generally out of the west to southwest at 10 to 20 MPH at times with higher gusts in the vicinity of showers and thunderstorms.
Rain: Suddenly, the foothills of the Sierra Nevada are peppered with fast moving thunderstorms which are dumping copious amounts of rain and no doubt some hail in those regions. A few isolated storms are popping up over western Fresno County and could occur just about anywhere from now through the early evening hours. The activity will taper off later this evening and may actually end for a while later tonight and for a time Friday morning. Rain fall amounts will vary widely between now and then, ranging from a few hundredths to as much as a half inch anywhere a thunderstorm occurs. The chance for mainly light showers will increase again Friday with a good chance of periodic showers Friday afternoon through early Monday. With very cold, unstable air moving in from the north, isolated thunderstorms will be possible Friday through Sunday afternoons through the early evenings. Thunderstorms, of course, where they do occur, will bring localized heavy rain and small hail. Dry weather will return Monday and last through at least Wednesday. Some models seem to be backing off now on the chance for showers Wednesday night and Thursday but are increasing the chance of another round of cold, showery weather next weekend. Models going out through the end of the month show the persistent February pattern of storms diving southward from western Canada and into the western U.S. although this afternoon’s models are inconclusive as far as precipitation chances go. One thing I’m pretty certain of, though, and that’s the likelihood of the weather feeling more like winter than spring.
Frost Discussion: It may not feel like it quite yet, but the leading edge of the first cold air mass is m oving into central California, setting off numerous thunderstorms over the mountains and isolated storms over the valley floor. Temperatures in Fresno and Madera Counties are currently in the mid 60s but up in Modesto the temperature is only 51, so obviously a cold front is moving through.
Tonight through Monday morning, readings will continue to be above freezing. It is possible Monday morning that, if skies clear earlier than expected, upper 20s and lower 30s are possible, but for now not likely. Although I haven’t determined the particular threshold of this incoming air mass, coldest readings down to 28 to 32 seem plausible for Tuesday, that’s if skies clear and winds are calm. For Wednesday and Thursday, temperatures will be determined by the amount of cloud cover from a very weak front moving through, bringing with it another round of very cold air. Models are also hinting at the possibility of another very cold low diving southward from western Canada and into California next weekend to begin the pattern anew. This persistent pattern this month of high pressure just off shore and a dominant northerly flow sandwiched between that high pressure and a very cold trough over the west continues to show up all the way through the end of February. At the very least, for the next ten days we can expect well below average temperatures.
Next report: Friday morning/February 15