NWS Area Forecast Discussion
000 FXUS66 KLOX 302118 AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 230 PM PDT FRI JUL 30 2010 .SYNOPSIS... A FLATTENING OF THE HIGH PRESSURE RIDGE WILL COOL TEMPERATURES A FEW DEGREES OVER THE WEEKEND...THEN BUILD BACK INTO THE AREA EARLY NEXT WEEK...WARMING TEMPERATURES BACK UP. THE NIGHT THROUGH MORNING LOW CLOUDS AND FOG WILL CONTINUE THROUGH NEXT WEEK. && .SHORT TERM (TODAY-MON)...MADE MINOR CHANGES THROUGH THE PERIOD. GUIDANCE INITIALIZED THE MID/UPPER LEVEL MOIST SOUTH WINDS CENTERED OVER THE SOUTHWEST STATES WITH THE WESTERN BOUNDARY OVER THE HIGH DESERT REASONABLY WELL. AND WAS CONSISTENT WITH PREVIOUS RUNS WITH THE PLUME AXIS PERSISTING OVER THE SOUTHWEST STATES WHILE A WEAK UPPER LEVEL TROUGH CURRENTLY OVER CENTRAL TEXAS ROTATES WEST THROUGH SUNDAY. DRIER SOUTHWEST WINDS WILL LIKELY PREVAIL OVER THE AREA AND WILL CONTINUE DRY OVER THE HIGH COUNTY SUNDAY. COOL MARINE AIR AND LOW CLOUDS WILL PERSIST NEAR SHORE WHILE A WEAK/MODERATE ONSHORE PRESSURE GRADIENT PERSISTS. TEMPERATURE TREND WAS MIXED EARLY THIS AFTERNOON AND WERE 10 TO 15 DEGREES BELOW SEASONAL NORMAL EXCEPT AROUND NORMAL IN THE DESERT AND ABOVE NORMAL IN THE HIGH COUNTRY. WILL CONTINUE WITH A SLIGHT COOLING TREND SATURDAY AND A MIXED TREND SUNDAY AS THE MARINE LAYER DEPTH FLUCTUATES. IT IS LIKELY TEMPERATURES WILL CONTINUE 8 TO 12 DEGREES BELOW SEASONAL NORMAL SATURDAY AND SUNDAY. HEIGHTS/THICKNESSES WILL LIKELY RISE/INCREASE MONDAY AS A LONGWAVE RIDGE BUILDS WEST OVER THE AREA. MARINE AIR WILL BEGIN TO RETREAT AND TEMPERTURES WILL WARM THOUGH REMAIN SEVERAL DEGREES BELOW NORMAL AT THE COAST AND COASTAL VALLEYS. .LONG TERM (TUE-FRI)...HAVE ADJUSTED TEMPERATURES UP THROUGH THE ENTIRE PERIOD. MEAN LONGWAVE RIDGE OF HIGH PRESSURE WILL CONTINUE TO BUILD WEST OVER THE AREA AND A WARMING TREND WILL LIKELY OCCUR THROUGH THURSDAY WITH TEMPERATURES 5 TO 10 DEGREES ABOVE NORMAL FROM THE COASTAL VALLEYS EASTWARD. LITTLE CHANGE WILL LIKELY OCCUR FRIDAY AS THE LONG WAVE RIDGE CONTINUES TO SHIFT WEST. && .AVIATION...30/2020Z. A STRONG MARINE INVERSION AND HEALTHY ONSHORE FLOW WILL COMBINE WITH A 1400 FOOT MARINE LAYER TO ENSURE A RETURN OF LOW CLOUDS AND FOG BEGINNING EARLY THIS EVENING. THE LOW CLOUDS AND FOG ARE HUGGING THE COAST AND WILL BE QUICK TO BRING MVFR/IFR CONDITIONS TO COASTAL SECTIONS. THE KLAX TAF MAY NEED AN AMENDMENT TO BRING THE LOW CLOUDS AND FOG IN EARLIER THAN 04Z. KLAX...FAIR CONFIDENCE IN THE 18Z TAF AS WRITTEN. MAY NEED TO AMEND THE TAF TO BRING LOW CLOUDS AND FOG INTO THE AIRFIELD EARLIER. KBUR...GOOD CONFIDENCE. && .LOX WATCHES/WARNINGS/ADVISORIES... NONE && $$ AVIATION...SWEET SYNOPSIS...BARTLING WWW.WEATHER.GOV/LOSANGELES
NWS LOX Office Area Forecast Discussion
Glendora Random Weather Fact
DEW POINT
Dew point is the temperature to which air must be cooled for saturation (100% relative humidity) to occur. The dew point is an important measurement used to predict the formation of dew, frost, and fog. If dew point and temperature are close together in the late afternoon when the air begins to turn colder, fog is likely during the night. Dew point is also a good indicator of the air's actual water vapor content, unlike relative humidity, which takes the air's temperature into account. High dew point indicates high vapor content; low dew point indicates low vapor content. In addition a high dew point indicates a better chance of rain and severe thunderstorms. You can even use dew point to predict the minimum overnight temperature. Provided no fronts or other weather pattern changes are expected overnight, the afternoon's dew point gives you an idea of what minimum temperature to expect overnight.
