Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT" or "AMDAR" received at FSL on 04/30/03

.SYNOPSIS...AN AREA OF LOW PRESSURE OVER THE REGION WILL KEEP THE AIR MASS UNSTABLE ENOUGH FOR A THREAT OF SHOWERS THROUGH WEDNESDAY. THIS FEATURE WILL WEAKEN THURSDAY...WITH THE CHANCE OF PRECIPITATION BECOMING CONFINED TO THE MOUNTAINS. A DEVELOPING STORM SYSTEM OFF THE CANADIAN COAST WILL BRING AN INCREASING THREAT OF SHOWERS TO THE AREA THIS WEEKEND.

.DISCUSSION...SATELLITE IMAGERY SHOWS UPPER LEVEL LOW STILL NEAR BROOKINGS. NWS AND ACARS SOUNDINGS INDICATE LITTLE FLOW ALOFT WITH WINDS LESS THAN 20 KNOTS BELOW 20000 FEET. SURFACE GRADIENTS WEAK ONSHORE WITH THE AIR MASS SLIGHTLY UNSTABLE. NO CHANGE IN THE SURFACE OR UPPER AIR PATTERN TODAY WITH THE UPPER LOW CONTINUING TO SLOWLY WEAKEN OVER SOUTHERN OREGON. MODELS DON'T INDICATE ANY VORT LOBES MOVING THROUGH THE CWA BUT CONVECTIVE TEMPERATURES OFF THE SOUNDINGS ARE IN THE UPPER 50S...NEAR THE MAX TEMPS FOR THE DAY...SO WILL KEEP THE CHANCE OF SHOWERS IN THE FORECAST WITH THE BEST CHANCES LATE AFTERNOON AND EARLY EVENING HOURS. LOW DISSIPATES SOUTH OF THE AREA ON THURSDAY. AIR MASS REMAINING SLIGHTLY UNSTABLE BUT MODEL CONVECTIVE TEMPERATURES IN THE MID 60S FOR THURSDAY. MESO ETA GENERATES LARGE CAPE VALUES OVER THE CWA WITH SOME VERY LOW LIFTED INDEXES IN THE AFTERNOON...-5 AT KSMP. FLOW ALOFT REMAINS LIGHT AND CANNOT FIND ANY UPPER LEVEL SUPPORT FOR MUCH CONVECTIVE ACTIVITY. WITH THIS IN MIND WILL CONFINE THE SHOWERS/THUNDERSTORM CHANCES TO THE CASCADES THURSDAY. CWA IN BETWEEN SYSTEMS ON FRIDAY WITH ANOTHER UPPER LEVEL LOW SPINNING UP OFF NORTHERN CALIFORNIA AND AN UPPER LEVEL TROUGH MOVING DOWN THE BRITISH COLUMBIA COAST. SURFACE GRADIENTS REMAIN LIGHT ONSHORE SO WILL KEEP MAX TEMPS NEAR NORMAL WITH THE SUNSHINE. .EXTENDED...WEEKEND WEATHER GOES DOWNHILL FAST AS UPPER LEVEL TROUGH MOVING DOWN THE BRITISH COLUMBIA COAST REACHES THE LATE SATURDAY AND DOES NOT REALLY KICK OUT OF THE AREA UNTIL EARLY MONDAY. GFS NOW INDICATES A WEAKENING SYSTEM MOVING THROUGH WESTERN WASHINGTON ON TUESDAY. WILL ADD A CHANCE OF PRECIP FOR TUESDAY AND MOVE POPS INTO LIKELY CATEGORY FOR SATURDAY NIGHT. FELTON

UIL 22- SEA 44- OLM 331

.KSEW...SMALL CRAFT ADVISORY CENTRAL STRAIT OF JUAN DE FUCA.

.KATX...VCP21/CSR21...OPERATIONAL.

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QUIET WEATHER TODAY EXCEPT FOR SOME MORNING CLOUDS AND EVEN SOME VERY LIGHT PRECIP ALONG THE NORTH SLOPES OF THE SBA/VTU/LA MTNS. THESE SHOULD BE CLEARING THIS AFTERNOON AS THE AIRMASS DRIES OUT. ACARS AND RAOB SOUNDINGS INDICATE A SLIGHTLY WARMER AIRMASS IN PLACE TODAY AND TEMPERATURE TRENDS THIS MORNING ECHO THIS IDEA. THIS COUPLED WITH SLIGHT OFFSHORE PRESSURE GRADIENT TRENDS SHOULD LEAD TO A WARMER DAY OVERALL.

ONSHORE TRENDS WILL RETURN THURSDAY AS WE TRANSITION TO THE NEXT SYSTEM APPROACHING THE WEST COAST. MODELS INDICATE A LOT OF MID AND HIGH LEVEL MOISTURE MOVING IN DURING THE DAY AND IR SATELLITE IMAGERY CONFIRMS THIS. THUS, PARTLY TO MOSTLY CLOUDY FORECAST LOOKS GOOD. WE ALSO WILL SEE SOME PATCHY MARINE LYR CLOUDS REFORMING, BUT NOTHING REAL SOLID.

THINGS STILL ON TRACK FOR RAIN FRIDAY AND SATURDAY. TIMING STILL A LITTLE UNCERTAIN BUT IT CERTAINLY LOOKS LIKE A GOOD BET THAT IT WILL RAIN EVERYWHERE IN OUR CWA AT SOME POINT IN THAT PERIOD. THE 12Z MESO ETA WAS A LITTLE FASTER WITH THE RAIN THAN LAST NIGHT'S GFS BUT I'LL PROBABLY NOT CHANGE THE POPS MUCH UNLESS THE 12Z GFS GOES ALONG WITH THIS IDEA. MAIN BRUNT OF THE STORM WILL BE FROM LATE FRIDAY AFTERNOON THROUGH SATURDAY MORNING WITH SOME PRETTY IMPRESSIVE RAINFALL TOTALS EXPECTED.

LAX 000. WOFFORD

.LOX...SMALL CRAFT ADVISORY (SEE LAXCWFLOX).

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