textproduct: Los Angeles

SYNOPSIS

08/1052 PM.

It will be cooler today. Friday and the weekend will see stormy conditions with showers and a chance of thunderstorms along with a dramatic decrease in daytime temperatures.

LONG TERM (SUN-WED)

09/220 AM.

On Saturday night a colder and more vigorous upper low will move into nrn CA. It will bring a wetter and much more dynamic front into the area. There is a greater than 80 percent chc that all areas will see rain overnight. The front will likely produce a number of TSTMs. It will have at least advisory level southerly winds in the mtns and interior vlys and perhaps over the Central Coast as well. The south winds will bring enhanced precip totals and rates to the transverse ranges. Any TSTM that forms will also bring enhanced precip totals and rates to areas they pass over.

At this point it looks like the flatter portions of the csts and vlys will see a half to three quarters of an inch of rain overnight with inch plus amounts on the across the foothills and coastal slopes and any area affected by TSTMs. Most rainfall rates will be between 0.25 to 0.75 in/hr but higher rates will be possible under any TSTM that develops.

Snow levels will fall to about 5500 ft and accumulating snow will fall above 6000 ft.

These rainfall and snowfall numbers are still preliminary and are still subject to change. The most likely factor that would change the numbers are the speed of the front (slower = more rain / faster = less rain) and the trajectory of the parent upper low. Still confidence in this forecast is higher than it has been.

The main front will exit LA county sometime between dawn and mid morning on Sunday. There will be some shower activity behind the front but additional rainfall amounts will not amount to much. It will feel more like a rainy January day with max temps only in the lower to mid 60s.

There is a 20 to 30 percent chc of lingering showers Sunday night and a low by non zero chc Monday morning. These showers should just be stray nuisance showers. By mid morning Monday dry NW flow will set up over the area. Sunnier skies and rising hgts will bring 2 to 4 locally 6 degrees of warming to the area. Max temps, however, will be 8 to 12 degrees blo normal.

Tue and Wed will see a nice warming trend as the cold air moves out of the area and high April sun angle combine to bring 4 to 8 degrees of warming Tuesday and 2 to 4 additional degrees on Wednesday. Wednesday's highs across the csts and vlys will almost all be in the 70s.

AVIATION

09/0549Z.

At 0508Z at KLAX, the marine layer was 1200 ft deep. The top of the inversion was at 2900 ft with a temperature of 20 C.

Good confidence in TAFs for KBUR, KVNY, KPMD and KWJF.

Moderate confidence in remaining TAFs. Timing of flight cat changes may be off +/- 2 hours and cig hgts by +/- 300 ft.

KLAX...Moderate confidence in TAF. Low clouds could arrive as early as 09Z or as late at 13Z. Cigs could range between 008 and 012. Good confidence that any east wind component will be under 7 kt.

KBUR...High confidence in VFR TAF.

MARINE

08/1053 PM.

Current small craft advisories and GALE Warning are on track, but winds should be lighter for the near shore waters from southeastern Santa Barbara County to Los Angeles County. Refer to MWWLOX for more details regarding the Small Craft Advisories (SCA) and Gale Warning. Another round of borderline SCA level winds are possible south of Point Conception this afternoon.

A storm system bringing showers and a chance of thunderstorms will move across the coastal waters starting late tonight and will continue through the weekend. Stronger showers and thunderstorms can bring heavy downpours, dangerous cloud to ocean lightning, small hail, and erratic gusty winds. Boaters, especially those with small vessels should avoid these hazardous conditions.

LOX WATCHES/WARNINGS/ADVISORIES

CA...NONE. PZ...Small Craft Advisory in effect until 11 PM PDT this evening for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 11 AM PDT this morning for zone 673. (See LAXMWWLOX).