Southern California/Arizona must read

[aveosmth]

This is from the Los Angeles NWS:

NEW GFS SHOWS NO RELIEF IN SITE. SATURDAY LONG WAVE SOUTHWESTERLY
MOIST ZONAL FLOW SETS UP AS POLAR JET AND SUB TROPICAL JET MERGE INTO
A DOUBLE JET STRUCTURE WHICH WILL PROVIDE THE DYNAMICS. CURRENT MDLS
KEEP THIS FLOW PATTERN OVER US FOR THREE DAYS. IF IT HAPPENS IT WILL
BE THE FIRST "PINEAPPLE EXPRESS" SINCE 1995. THIS COULD POTENTIALLY BE
A VERY LARGE/DANGEROUS HYDROLOGIC EVENT AND WILL HAVE TO MONITORED
VERY CLOSELY.

I remember the 95' storms and they were absolutely unbelievable...our major freeways were flooded...many accidents and lives lost...the pineapple express is a subtropical system that extends from the Southwest all the way west near Hawaii(hence the name). With all of the snow at higher elevations, this warm rain would cause extreme flooding....

[PurdueWx80]

Perfect weather for the largest annual gathering of meteorologists in San Diego starting this Friday. Not so perfect for anyone whole lives in the SW though. Deep tropical convection is prevalent between Hawaii and Cali, and the Pineapple Express looks to be setting up as we speak. Note the greens flowing just north Hawaii towards CA.

[aveosmth]

Youre absolutely right...this system concerns me deeply because we just got a ton of snow in our higher elevations this week...we also had severe fires a little over a year ago and much of the vegetation has not grown back as well...This will be a severe weather event of this happens.

[weatherlover427]

The San Diego AFD sounds even more ominous...

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 330 AM PST WED JAN 5 2005

.SYNOPSIS...COOL CONDITIONS AND PARTLY CLOUDY SKIES ARE EXPECTED TODAY. THEN...THE CHANCE OF RAIN INCREASES AGAIN LATE THURSDAY INTO FRIDAY WITH HEAVY RAIN POSSIBLE. UNSETTLED CONDITIONS WILL LINGER INTO EARLY NEXT WEEK WITH PERIODS OF RAIN LIKELY TO CONTINUE.

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES.

564 MOIST ZONAL FLOW TODAY FOR PARTLY CLOUDY SKIES AS EXTREME POS TILT TROF UNDERCUTS THE 570 GOA HIGH. PATTERN IS A CHANGING...AND IT LOOKS LIKE WE ARE MOVING INTO A PINEAPPLE EXPRESS MODE AS OPPOSED TO THE COLD GOA LOWS THAT HAVE BEEN DROPPING DOWN. BY THU THE GOA OMEGA IS 584...AND THE UNDERCUT STRECTCHES ALL THE WAY BACK TO HAWAII. SO WHEN THE 530 LOW DROPS DOWN THE EAST SIDE OF THE OMEGA INTO CEN CALIF...IT INTERACTS WITH A VERY MOIST AND STRONG SUBTROPICAL JET. GUESS THAT IS WHY THERE IS 1 INCH BULLSEYE OF PRECIP COMING THRU SCALIF FRI PM INTO SAT AM. GOOD SNOW MAKER WITH THE FRI SYSTEM WITH 558 HEIGHTS WITH SNOW LEVEL ABOVE 5000 FEET. BUT THAT SHORT WAVE APPEARS TO BE THE GATE OPENER...BECAUSE AFTER THAT...THERE SEEMS TO BE AN ENDLESS STREAM OF TROPICAL AND MID LATITUDE MOISTURE BEING DRAGGED IN BY THE SUBTROPICAL JET. SO HEAVY RAIN INDICATED SAT-TUE WITH 4 INCHES OF RAIN POSSIBLE IN THE COASTS AND VALLEYS...MUCH MORE IN THE MTS WITH STRONG SW WINDS ALOFT AIDING OROGRAPHICS. FLOW IS 564 TO 570 SW...SO A WARM RAIN WITH RAPID SNOW MELT AND POSSIBLE FLOODING. A LARGE COLD UPPER LOW PUTS AN END TO THE TROPICAL FLOW BY WED OF NEXT WEEK. BUT LONGER RANGE MAPS HINT AT THE PINEAPPLE PUMP RETURNING BY FRI OF NEXT WEEK.

[frankthetank]

What does this mean for the rest of us? With all of the subtropical moisture streaming in, will the rest of us see a milder pattern set up?

[weatherlover427]

Well a southwest flow generally means milder air, but however with this pattern I am not sure how far north (meaning your area specifically) it will make it.

[Scorpion]

Well, I guess we can be happy that this will help the drought situation .

[aveosmth]

This has got to be the highest rainfall totals I've ever seen...from the Los Angeles NWS.......

RAINFALL PREDICITIONS THROUGH THE WEEKEND WILL BE EXTREMELY
IMPRESSIVE. THERE IS THE POTENTIAL FOR UP TO 20 INCHES IN THE
MOUNTAINS BY MONDAY AND 4 TO 8 ALONG THE COAST AND IN THE VALLEYS.
THIS WILL PUT US WELL PAST OUR FULL SEASON'S WORTH OF RAIN FOR MOST
AREAS, ESPECIALLY SOUTH OF POINT CONCEPTION, AND WE'RE NOT EVEN TO
MID JANUARY YET.

Here in L.A. we are already past our season;s (July 1st-June 30th) rainfall....before this weekend there is another storm that could be drop an additional 1-3 inches....also, with the tropical warm nature of the rain, melting snow will be an issue & we have tons of it....not good at all.

[frankthetank]

So we're talking a solid 3+ feet snowfall in the Sierra??? I was looking @ some snowfall obs out there from the past storm...some were over 50inches for the past seven days...thats insane ...wow...

[weatherlover427]

Due to the nature of this setup, snow levels will be very high, so some snowmelt will occur. However, for those areas that DO get snow, they will be in for it, so to speak.

[Guest]

20 inches of rain = 20 feet of snow! lol its gonna be the day after tomorrow... except out west. But really guys, I hope you do get this storm. You really need the rain.

[frankthetank]

Yeah...i read that about the subtropical air getting involved, creating snow melting conditions...but still, there is plenty of ground over 8K feet...

[weatherlover427]

Yeah...i read that about the subtropical air getting involved, creating snow melting conditions...but still, there is plenty of ground over 8K feet...

True, we do have plenty of mountains out here that are that high, even some over 10K feet in elevation.

I myself haven't been that high before, but still it must be pretty nice to live up in the mountains...