Forecast Discussions mentioning ACARS, received at FSL on 06/05/99

...SYNOPSIS... A COLD UPPER LOW NEAR LAS VEGAS WILL KEEP A FEW SHOWERS OVER THE NORTHERN MOUNTAINS AND DESERTS THROUGH THIS EVENING. A MODERATE ONSHORE FLOW WILL KEEP LOW CLOUDS WEST OF THE MOUNTAINS THROUGH TONIGHT. HIGH PRESSURE WILL BUILD OVER THE COAST SATURDAY AND SUNDAY FOR CLEAR WARMER WEATHER AFTER NIGHT AND MORNING COASTAL LOW CLOUDS.

...DISCUSSION... VISIBLE SATELLITE IMAGERY INDICATES THE CLOUDS HAVE DIMINISHED OVER THE NEAR SHORE COASTAL WATERS AND ALONG THE IMMEDIATE COAST BUT ENOUGH INSTABILITY AND THE MODERATE ONSHORE FLOW HAS KEPT CLOUDS AND SCATTERED SHOWERS OVER THE INLAND AREAS FROM THE MOUNTAINS WEST THROUGH THIS AFTERNOON. CONVERGENCE BANDS FROM THE OFFSHORE ISLANDS ARE SHOWING UP. ONE EXTENDS FROM SANTA CATALINA ISLAND INTO SOUTHERN ORANGE/NORTHERN SAN DIEGO COUNTIES. A SECOND BAND EXTENDS FROM SAN CLEMENTE ISLAND INTO POINT LOMA/OCEAN BEACH AREA OF SAN DIEGO.

12Z MODELS BRING ANOTHER WEAKER VORT MAX SOUTHEAST ACROSS THE AREA LATER THIS AFTERNOON AND EVENING WHICH SHOULD KEEP A FEW SHOWERS OVER THE NORTHERN DESRTS AND MOUNTAINS...ESPECIALLY THE NORTH SIDE OF THE SAN BERNARDINO MOUNTAINS THROUGH THE EVENING. RECENT ACARS SOUNDINGS OUT OF LAX SHOW A FAIRLY STRONG SUBSIDENCE INVERSION ABOVE 10 THOUSAND FEET AND INDICATIONS THE FREEZING LEVEL WILL BE JUMPING TO 10 THOUSAND FEET VERY SHORTLY. ONE SOUNDING FROM AN AIRCRAFT DECENDING INTO LAX HAD THE FREEZING LEVEL AT 10 THOUSAND FEET ALREADY BUT A COUPLE OTHER AIRCRAFT SOUNDINGS SHOWED A NEARLY ISOTHERMAL SOUNDING BETWEEN 7 AND 10 THOUSAND FEET. THE INVERSION SHOULD HELP CAP OFF ANY CONVECTION OVER THE MOUNTAINS PREVENTING ANY THUNDERSTORMS.

RIDGING TONIGHT AND THROUGH THE WEEKEND AS INDICATED BY THE MODELS SHOULD BRING CLEARING MOST AREAS ON SATURDAY ALONG WITH WARMING. MODELS INDICATE GOOD THICKNESS RISES THROUGH SUNDAY BUT THINK NGM MOS TEMPS FOR THE COACHELLA VALLEY INTO THE UPPER 90S MAY BE A BIT FAST. WILL SCALE BACK TO THE MID 90 DEGREE RANGE FOR SUNDAY FOR PSP AND TRM.

COASTAL WARMING MAY BE HELD DOWN SHOULD AN EDDY SPIN UP OFFSHORE. GUSTY NORTHWEST WIND NEAR POINT CONCEPTION FAVORS THE FORMATION OF AN EDDY SO ONE CAN NOT BE RULED OUT.

LONGER RANGE MODELS STILL SLIDE THE NEXT S/WV INLAND ACROSS THE PACIFIC NORTHWEST AND SOUTHERN CANADA WITH SOME TROUGHINESS INTO SOUTHERN CALIFORNIA BUT HEIGHTS REMAIN FAIRLY HIGH. MAIN IMPACT SHOULD BE A DEEPER MARINE LAYER WITH FURTHER INLAND PENETRATION OF THE LOW CLOUDS...ALONG WITH COOLING MONDAY AND TUESDAY. HAVE TO WATCH FOR ANY FURTHER DIGGING OF THIS S/WV.

SAN 0000

.SAN...SMALL CRAFT ADV (SEE LAXCWFSGX).

HORTON

...SYNOPSIS... DRIER AND MUCH WARMER FOR THE MOUNTAINS AND DESERTS THIS WEEKEND AS THE COLD UPPER LOW FROM FRIDAY MOVES EAST AND WEAK HIGH PRESSURE BUILDS OVER SOUTHERN CALIFORNIA. ALONG THE COAST...TEMPERATURES WILL RETURN TO NEAR NORMAL WITH SEASONAL NIGHT AND MORNING LOW CLOUDS AND FOG. IN THE VALLEYS...GRADUAL WARMING TODAY WITH GREATER WARMING FOR SUNDAY.

...DISCUSSION... ACARS SOUNDINGS EARLY FRI EVENING SHOWED THE HEIGHT OF THE MARINE INVERSION NR 7000 FT WITH A LATER 06Z SOUNDING FM ONT SHOWING A DECR IN THE INVERSION HEIGHT TO AROUND 5000 FT. ADDITIONAL LOWERING AND STRENGTHENING OF THE MARINE INVERSION IS EXPECTED DURG THE NEXT TWO DAYS AS 1000-500 MB THICKNESSES AND 850 MB TEMPERATURES RISE SUBSTANTIALLY FM THE SEASONALLY VERY LOW LVLS OF FRI WITH 850 MB TEMPERATURES RISING 8 TO 10 DEG C FM FRI AFTERNOON TO SAT AFTERNOON...AND ANOTHER 2 TO 4 DEG C FM SAT AFTERNOON TO SUN AFTERNOON FOR THE PREFERRED ETA. ONSHR FLOW REMAINS WK SAT...THEN STRENGTHENS SUN AFTERNOON. SIGNIFICANT WARMING SHOULD OCCUR TODAY IN MTNS AND DESERTS WITH LESSER WARMING CST AND VLYS. FOR SUN...SOME ADDITIONAL WARMING FOR MTNS AND DESERTS WITH GREATER WARMING FOR THE VLYS. WARMING FOR CST ON SUN WL BE MODULATED BY INCRG ONSHR FLOW. CSTL EDDY POSSIBLE SUN NIGHT AT SOONEST. SURF FM S SWELL PEAKED FRI AFTERNOON WITH MAX SETS TO AROUND 6 FT WITH DOWNWARD TREND IN S SWELL EXPECTED TO CONTINUE THRU THE WEEKEND.

SAN 000

.SAN...NONE.

MARTIN

UPDATED TO REMOVE PRECIP TODAY. DVN SOUNDING TOGETHER WITH DENSE ACARS DATA FROM CHICAGO OHARE CONFIRM STRONG 700 MB CAP. CONVECTIVE TEMPERATURE IN MIDDLE 90S...AND DONT THINK MESOSCALE VORT MAX OVER CENTRAL IA WILL BE ENOUGH TO BREAK CAP TODAY IN IL.

PASS THE CROW...

.CHI...NONE.

BROWNING

SATELLITE PICTURES SHOW COLD FRONT ALONG E SLOPES OF THE CASCADES AT 15Z. FRONT WENT THROUGH KSEA ARND 12Z. VERY NICE VISIBLE IMAGE AT 15Z SHOWING FRONT...CONVERGENCE ZONE WHICH QUICKLY FORMED IN THE WAKE OF THE FRONT...AND LEADING EDGE OF MUCH COOLER AIR ASSOCIATED WITH UPPER LEVEL LOW OVER THE QUEEN CHARLOTTES JUST REACHING CAPE FLATTERY. LITTLE CHANGE IN THE FORECAST WITH FIRST LOOK AT NEW MODELS CONTINUING TREND OF LOW SLOWLY DROPPING DOWN THE COAST WITH THE COLDEST AIR ALOFT MOVING OVER WRN WA TONIGHT AND SUN. IN THE MEANTIME...ACARS DATA HAS NUMEROUS SOUNDINGS WITH SWLY WINDS AROUND 25 KTS RIGHT OFF THE GROUND. WITH AMS SMWHT UNSTBL THESE WINDS WILL MIX DOWN TO THE SURFACE MAKING FOR A BREEZY DAY. WITH SWLY FLOW ALOFT EXPECT CONVERGENCE ZONE TO REMAIN NORTH OF DOWNTOWN SEATTLE TODAY. FLOW THROUGH THE STRAIT DIMINISHES TONIGHT AND SUN AS SURFACE AND UPPER LEVEL LOW ALONG BC COAST MOVES SOUTHWARD. BETTER DYNAMICS SUNDAY WITH COLDER AIR ALOFT AND VORT LOBE ROTATING AROUND THE LOW OVER WRN WA LATE IN THE DAY SO WILL LEAVE THUNDERSTORMS IN THE FORECAST. MAX TEMPS BOTH DAYS STRUGGLING TO GET TO 60 DEGREES...OR WHAT WOULD BE NORMAL FOR THE MIDDLE TO LATE PART OF APRIL. FELTON

UIL 888 SEA 546 OLM 546

.KATX...VCP21/CSR21...OPERATIONAL. .SEW...GALE CENTRAL AND EAST ENTRANCE TO THE STRAIT SCA ALL OTHER WATERS.