Active weather pattern (San Mateo: swimming, county, summer)

[BayAreaHillbilly]

MORE NOTABLE IS THE LATTER PART OF THE FORECAST WHERE ANOTHER LATE- SEASON
RAIN EPISODE IS POSSIBLE. THERE IS CONSISTENCY NOW AMONGST THE MODEL RUNS
CONCERNING AN UPPER LEVEL LOW PROGGED TO DROP SOUTHWARD OFF THE NORTHERN
CALIFORNIA COAST BY LATE TUESDAY AND WEDNESDAY. LATEST RUNS OF THE GFS AND
ECMWF STILL BRING A DEEP UPPER LOW OFF THE COAST BY NEXT TUESDAY NIGHT
WITH RAIN CHANCES REACHING INTO OUR CWA. HAVE ADDED POPS TO THE
FORECAST...SLIGHT CHANCE FOR NOW...WHICH CAN BE ADJUSTED AS IT GETS
CLOSER. GIVEN THE DEEPNESS OF THE LOW CENTER AS WELL AS ITS
PROXIMITY...THUNDERSTORMS ARE ALSO POSSIBLE AND THIS WILL NEED TO BE WATCHED.

================================================== =========

This is bad news on multiple levels. Ag could be harmed especially if serious thunderstorms happen.
And those storms, if not moisture rich, could start many wildfires. Something like that happened in nothern parts of Norcal
a couple years ago. Several fires burned for a month, the smoke from them combined, and it was like a
mini nuclear winter over a major part of the state. It actually reduced the wine grape crop.

[KC6ZLV]

There isn't much chance of a fire beyond a small grass fire. It is still damp in the foothills, wet in the mid-elevations, and a good percentage of the forest roads are blocked by snow above 7000 feet.

[tstieber]

Originally Posted by BayAreaHillbilly

In any case, we may be looking at another weak, minimal summer. The weather in Central CA and even parts of SoCal may end up being more like far NorCal this summer.

Definitely a "wow" weather pattern, but we had some good inland heat last week (finally) and 90s are slated to return a few days after this trough goes through. It just looks more inconsistent than normal for this time of year. I've been in San Diego and the beaches have been pretty socked in with marine layer, but farther inland, it's been nice, pretty much the same as the Bay Area. I wouldn't call it comparable to "far NorCal" but definitely cooler than average. We didn't even get a real heat wave last week, just into the 80s inland.

The weird thing is that these winter-like patterns in the off-season don't correspond to other seasons. In mid-November, it was still 80 degrees in the Bay Area, and in January and early February, we were having unusually dry and warm weather. So it seems we're getting more fluctuations in the patterns in both directions, bringing unusually good or bad weather to the state at random times of the year.

Still, one rain shower compared to the frequency of rains in most of the country this time of year isn't all that horrible.

[KC6ZLV]

Northern California pretty warm during the summer unless you are on the coast or at a high elevation.

[tstieber]

It's up to a 50 percent chance of precip, with about a half inch predicted for most of the Bay Area. Combined with late season rains in early June, this may well be the wettest June ever recorded! (Average for the entire month in SF is 0.13", so we'll be about 15 times average). Then, major heatwave again for the weekend, near 100F inland again. Crazy!

[BayAreaHillbilly]

Yes. This is really firming up.

NOW SHOWING UPWARDS OF 1.8 INCHES IN THE NORTH BAY THROUGH TUESDAY EVENING...WITH LESS THAN A HALF INCH ELSEWHERE. THE GFS AND ECWMF FORECAST CONSIDERABLY LESS RAINFALL IN THE NORTH BAY...GENERALLY ONLY ABOUT A HALF INCH. LATEST AMSU PW OUTPUT SHOWS A MOIST PLUME OF AIR WITH PRECIPITABLE WATER VALUES IN EXCESS OF 1.5 INCHES IS FEEDING INTO THIS SYSTEM ALONG 40N. SO THE POTENTIAL IS CERTAINLY THERE FOR RAINFALL TOTALS TO APPROACH THOSE FORECAST BY THE NAM. THE AIRMASS WILL BECOME SOMEWHAT UNSTABLE ON TUESDAY AS COLDER AIR BEGINS TO MOVE IN ALOFT...BUT WIDESPREAD CLOUDINESS WILL INHIBIT SURFACE HEATING ON TUESDAY AND LESSEN POTENTIAL FOR THUNDERSTORMS. IN ANY EVENT...THEIR MAY BE ENOUGH FRONTAL LIFT FOR EMBEDDED CONVECTION ALONG THE FRONTAL RAIN BAND. SO WILL KEEP SLIGHT THUNDERSTORM CHANCES IN THE FORECAST FOR TUESDAY AND TUESDAY EVENING.

[BayAreaHillbilly]

Interesting stats, for my CWA:

SAN FRANCISCO BAY AREA .
LOCATION............JUNE 30.....ALL OF JUNE.....DAILY
SANTA ROSA.........0.70/1991....2.43/1929......1.65/(6/2/1967)
KENTFIELD..........0.30/1952....3.42/1967......1.94/(6/2/1967)
SAN RAFAEL.........0.30/1991....2.33/1967......1.97/(6/2/1967)
NAPA...............0.40/1991....1.95/1967......1.22/(6/2/1967)
SAN FRANCISCO......0.22/1952....2.57/1884......1.34/(6/2/1967)
SF AIRPORT.........0.14/1992....0.97/2011......0.81/(6/2/1967)
OAKLAND............0.21/1991....1.47/2011......1.47/(6/4/2011)
OAKLAND AIRPORT....0.21/1952....1.09/2011......0.92/(6/2/1967)
RICHMOND...........0.16/1991....1.46/1993......1.42/(6/4/1993)
LIVERMORE..........0.07/1991....0.83/1929......0.60/(6/16/1995)
SAN JOSE...........0.02/1952....0.90/2011......0.88/(6/4/2011)
GILROY.............0.00/........0.91/1967......0.77/(6/2/1967)

MONTEREY BAY AREA .
LOCATION............JUNE 30.....ALL OF JUNE.....DAILY
MONTEREY...........0.02/2001....1.56/1967......0.99/(6/16/1995)
SANTA CRUZ.........0.21/1991....1.75/1929......1.63/(6/4/2011)
SALINAS............0.01/2001....0.59/1995......0.47/(6/16/1995)
SALINAS AIRPORT....0.01/2005....0.70/1934......0.58/(6/5/1934)
KING CITY..........0.00/........1.00/1931......0.78/(6/9/1929)

We've already eclipsed all time records for all of June and given day in June for a number of locations.

The other thing I see here is the impact of SW Monsoon events in terms of the 6/30 records. I can recall very clearly and we had no late cold fronts in either 1991, 1992, 1995 or 2001, but we did have Monsoonal flows reaching well north those years. I was not around in 1952 so cannot comment about that one. As for why June 30 and not June 28, I suppose that is the closest day with actual June rainfall to the likely day of this event, or a mistake. If they get eclipsed it will probably be the first time a significant cold front came this far south this late in June, at least since these types of records started being kept during the late 1800s.

[BayAreaHillbilly]

There is now a Winter Weather advisory up for the Sierra high country.

[Gentoo]

The Bay Area getting rain. Rain sounds wonderful but wishful thinking for me. Hopefully the approaching front will cool things off here at the very least.

[bhcompy]

On the flip side summer is here early compared the to the last two years in So Cal. Hardly any marine layer and we're hitting 80 at the beach. Shaping up for a hot 4th, too