| Day | Date | High/Low | Forecast |
| Mon | 30th | 77/58 | Amended…Sunny remainder of the day. Clear evening. |
| Tue | 1st October | 83/62 | Amended…Most sunny day with some afternoon high clouds possible. Some evening high clouds. |
| Wed | 2nd | 84/64 | Amended…Mostly sunny day with some high clouds. Some high clouds possible in the evening. |
| Thu | 3rd | 83/63 | Amended…Mostly sunny day with some high clouds possible. Some high clouds possible in the evening. |
| Fri | 4th | 77/62 | Mostly sunny day except chance of early morning low clouds/fog. Mostly clear evening. |
Synopsis
The recent stretch of cooler than normal weather in the coastal plain is on the verge of ending. A shallow but effective marine layer has so far shielded most of the coastline from noticeable warming (at least, as of this writing). High pressure aloft in the Southwest already promoted the recent, noticeable warming for well inland areas. However, the surface, on-shore flow weakened significantly this morning. When I put out the preliminary forecast, I thought the campus area would warm only modestly. Though the current temperature has dropped back more in line with my initial forecast (73 degrees), I decided to amend the temperature forecast (today’s portion is a “post-cast”.
It’s actually possible that the predicted, marginal off-shore flow tomorrow (already present aloft in the higher mountains) will promote greater, daytime warming than my amended forecast numbers. Satellite imagery showed a clearing out of low clouds over much of the eastern Pacific. The various models do predict a lingering, shallow and somewhat diluted, marine layer (areas of early morning, low clouds/fog along the coast still possible). It’s often tricky in predicting (accurately) the extent of a diluted marine layer (less of it making it easier to warm rapidly during the day, especially during the off-shore flow periods). Still, unlike the heat wave early this month, prolonged, warm temperatures into the evening shouldn’t occur at lower elevations. The air mass around the high pressure is sub-tropical in origin but not as warm nor humid as early in the month. The now, significantly longer nighttime should also help in promoting more reasonable, early morning temperatures.
The various models predict some minor weakening of high pressure aloft in the Southwest later this week (late Wednesday into Thursday…leveling off for Friday). This may permit a better on-shore flow though nothing as effective as the past week or so. Confidence is low at this time, but if an effective marine layer forms for Friday morning, areas near the coast may cool back to seasonal levels (leaned campus forecast that way for Friday). However, with only minor changes predicted in the low level, wind flow pattern, any cooling might end up being just a couple degrees or so.
If today’s model consensus is right, renewed warming should occur over the weekend (notably on Sunday). Model consensus is far from great (wide variety of possible outcomes), but some model solutions show a weak but definitive, off-shore flow early next week. That solution would favor 90 degree near the coast (campus included). Triple digit heat could extend to the inland coastal plain for a day or two (not just coastal valleys). Some models show a good cooling trend beginning around the 10th of October, but other model solutions show only modest cooling (potentially staying slightly warmer than normal late next week). Needless to say, the prospects for wet weather remain virtually zero (percent).
Next issued forecast/synopsis may be on Friday, 4 October (return of forecasts twice a week).