textproduct: Los Angeles

SYNOPSIS

10/609 PM.

A cooling trend will continue through Thursday, with cooler than normal temperatures expected across the area into the weekend. There is a chance of mountain and occasional lower elevation convection through at least Wednesday night. More robust marine layer cloud coverage is likely this week, however, higher clouds may disrupt the formation of the marine layer at times.

LONG TERM (THU-SUN)

10/206 PM.

Weak upper level troughing will continue into the weekend. However, 500 mb heights are expected to steadily climb Saturday through Monday. The EC and GFS are in fairly good agreement that 500 mb heights will rise to around 590-592 dam by Sunday. Beyond Sunday is where a significant disagreement occurs. Yesterday, the EC favored another troughing pattern and the GFS favored the ridging building back in. Today the two models have completely flipped. There is even quite a range of outcomes starting Monday within the EC Ensemble members. To say there is considerable uncertainty for Monday and beyond would be an understatement.

What does seem likely is much lower chances of any sort of convection as much of the monsoonal mositure moves back to the south and east. However, there still remains a very low chance (5%) for thunderstorms to develop virtually anywhere into the weekend and the trough along the coastal will try to pull in some remnant monsoonal mositure. Any sort of forcing from the trough will attempt to create a build up. With generally limited moisture, we would expect storm threats to generally be dry lightning or gusty outflow winds rather than downpours.

Slightly increasing temperatures into the weekend also appear likely. The good news for folks tired of the hotter than normal temperatures is that current forecast high temps will still remain below mid-August normals. One wrinkle is that onshore flow is expected to steadily weaken into the weekend and the cooling effects of nature's air conditioning will decrease. The magnitude of the decrease in onshore flow will certainly influence maximum temperatures for this weekend into Monday.

AVIATION

11/0547Z.

At 0512Z at KLAX, the marine layer was 800 feet deep. The top of the inversion was at 2400 feet with a temperature of 27 C.

High confidence in TAFs for the valleys and deserts.

Low confidence in TAF for KLGB with a 40 percent chc of OVC008 conds 13Z-17Z.

Low confidence in TAFs for remaining sites with a 40 percent chc of no low clouds.

There is a 30% chc of -TSRA at KWJF KPMD through 03Z 22Z-02Z.

KLAX...Low confidence in the 00Z TAF. There is a 40 percent chc of no low clouds. There is also a 5% chance of -TSRA 22Z-02Z. High confidence in minimal or no east wind component.

KBUR...High confidence in TAF. There is a 5% chance of -TSRA 22Z-02Z.

MARINE

10/750 PM.

High confidence that conditions will remain below Small Craft Advisory (SCA) across all of the southwestern California coastal waters through at least Friday night. Patchy dense fog are possible on the Central Coast each morning. There is also a 5-10% chance of a thunderstorm over the coastal waters Tuesday through Wednesday.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory in effect until midnight PDT Wednesday night for zones 349-350-354-362-366. (See LAXCFWLOX). PZ...NONE.