Rare Early Season Rainfall Possible in Southern California

[aveosmth]

We have a very unique situation building in SoCal as a low pressure system is currently parked offshore, spinning up tropical moisture from the remnants of TS Max.

All areas of Southern California could see some showers and even thunderstorms the next two days. Hopefully, we'll get something out of it, as this is very abnormal for us this time of year.

[wxmann_91]

Yes, dark skies to my southeast.

Is this (the green over the word San Diego) groundclutter or actual echoes?

(base reflectivity)


(composite reflectivity - better for mountainous areas like Southern Cali.)

[wxmann_91]

NEVER MIND it's the real deal!!!

BIG clap of thunder just heard to my southeast!!!!!!

YAY the first big weather I've seen for two months (since that freak thunderstorm that just happened to pass over my house at 3 AM)

EDIT: Thunder reported at Lindbergh Field.

[wxmann_91]

Interesting how this line of storms moved from SE to NW... usually it's the opposite way.

Moderate rain falling now.

[wxmann_91]

Love talking to myself ...

Satellite images show this line of storms.

[aveosmth]

These storms should be up here by midnight then! It is getting cloudier by the second, and we should have an interesting night!

[wxmann_91]

These storms should be up here by midnight then! It is getting cloudier by the second, and we should have an interesting night!

If you live in Los Angeles (which is where I think you live), then you probably won't get them today. The daytime heating is rapidly decreasing and the radar trends indicate weakening with the storms.

You might get it if you live in Orange County or up in the Oceanside and Escondido areas, but well before midnight.

Just as I am typing this, another squall moves by, another bout of moderate rain.

And more chances of rain tomorrow.

[aveosmth]

Yeah, youre probably right...the forecast was for the rain to hit tonight, but w/the loss of daytime heating it may be tough for those showers to make it.

Tomorrow looks like the day for us & it looks like our neighbors up north will get in the action as well.

I just looked at the 18Z NAM/ETA, and I know that's not going to verify, but we would be in for a nice dumping if it did

[wxmann_91]

Interesting...

A LOW OFF THE COAST AND A LARGE HI TO THE E WILL FUNNEL TROPICAL
MOISTURE OVER THE AREA THROUGH TUE. THIS WILL BRING A SLIGHT CHANCE
OF SHOWERS AND THUNDERSTORMS. MID LEVEL FLOW IS FAIRLY STRONG WITH
20 TO 30 KT AT 700 MB A LITTLE STRONGER WINDS ABOVE WHICH WILL TEND
TO SHEAR THUNDERSTORMS. LOOKS LIKE THE BEST CHANCE OF PRECIP WILL BE
TUE. THE UPPER LOW OFF THE COAST MOVES OUT TO THE NE WED AND DRIER
SW FLOW DEVELOPS ALOFT. RAINFALL TOTALS SHOULD REMAIN LESS THAN A
QUARTER OF AN INCH.

.SHORT TERM...POTENTIALLY INTERESTING SCENARIO SETTING UP FOR
TONIGHT. BOTH THE NAM AND GFS SHOWING A DECENT AMOUNT OF MID AND
UPPER LEVEL MOISTURE ADVECTING INTO OUR AREA FROM THE SOUTH. COMBINE
THIS WITH SOME UPPER LEVEL DIFLUENCE, A NORTH-SOUTH ORIENTED JET MAX
NEAR SBA AROUND 12Z, AND A PRETTY DECENT THETA-E RIDGE AXIS AND THIS
COULD BE ENOUGH TO SQUEEZE SOME RAIN OUT OVER OUR AREA OVERNIGHT AND
INTO TUESDAY MORNING. STILL A LOT OF FACTORS NEED TO PLAY OUT JUST
RIGHT FOR THIS TO HAPPEN BUT THE MODELS HAVE BEEN CONSISTENT THE
LAST FEW RUNS IN SUPPORTING THIS SCENARIO. NATURALLY THERE ARE
DIFFERENCES BETWEEN THE TWO, BUT THE OVERALL PATTERN IS VERY SIMILAR
AND EVEN PRECIP AMOUNTS ARE RELATIVELY CLOSE. THE MAIN DIFFERENCE IS
WHERE THE AXIS OF RAIN WILL OCCUR, AND IT'S MAINLY FOR THIS REASON
THAT I'VE BLANKETED THE AREA WITH 30 POPS RATHER THAN TRYING TO
HIGHLIGHT ANY ONE PARTICULAR AREA. THE GFS IS FARTHER EAST WITH THE
PLUME OF MOISTURE AND THETA-E RIDGE AXIS, MAINLY FROM LA COUNTY
STRETCHING NORTH-NORTHWEST INTO INTERIOR SLO COUNTY, WHILE THE NAM
IS CENTERED CLOSER TO THE CHANNEL ISLANDS. WILL BROAD BRUSH THINGS
FOR NOW AND WE CAN REFINE THIS AS THINGS DEVELOP (OR DON'T DEVELOP).

LATEST SAT IMAGERY IS INCONCLUSIVE WITH REGARDS TO PRECIP
DEVELOPMENT OVERNIGHT. THE GOES PW CHANNEL IS SHOWING HIGHER PW'S
DRIFTING UP THE BAJA COAST, BUT WE'RE STILL QUITE A BIT BELOW WHAT
THE MODELS (ESPECIALLY THE NAM) WERE FORECASTING FOR THIS AFTERNOON.
NOT REALLY IMPRESSED YET WITH THE AMOUNT OF MID LEVEL MOISTURE
SHOWING UP ON THE IR, BUT THIS COULD EASILY CHANGE ONCE THE MOISTURE
STARTS MOVING INTO THE DIFLUENT PART OF THE FLOW JUST EAST OF THE
UPPER LOW. LOW LVL MOISTURE ON BOTH OF THE MODELS IS NOT GREAT, BUT
PROBABLY ENOUGH TO SUPPORT SOME PRECIP AT THE SURFACE IF THE OTHER
FACTORS ARE IN PLACE. AGREE WITH THE LATEST SPENES MESSAGE WITH
REGARDS TO THE UPPER LOW ORIENTATION AND WILL HAVE TO SEE HOW THIS
EVOLVES OVERNIGHT.

SO OVERALL, NO MAJOR CHANGES TO THE PREVIOUS THINKING. GIVEN THE
BETTER MODEL TO MODEL AND RUN TO RUN CONSISTENCY WE'VE UPPED THE
POPS ONE CATEGORY. CONCERN FOR FLASH FLOODING IS LOW GIVEN THE WIND
SPEEDS ALOFT IN EXCESS OF 40 KTS, THOUGH THERE STILL COULD BE SOME
BRIEF HEAVY RAIN IN ISOLATED AREAS, ASSUMING ALL THE ELEMENTS COME
INTO PLACE.

THESE SITUATIONS TEND TO DEVELOP PRETTY RAPIDLY OVERNIGHT AND WE
SHOULD HAVE A PRETTY GOOD IDEA BY MIDNIGHT IF ANYTHING IS GOING TO
DEVELOP AND WHERE. BY TUESDAY AFTERNOON MOST OF THE ACTION SHOULD BE
NORTH AND EAST OF OUR AREA, LEAVING US MOSTLY CLEAR TUESDAY NIGHT
INTO WEDNESDAY.

.DISCUSSION...POTENTIALLY ACTIVE WEATHER SCENARIO TO PLAY OUT OVER
THE NEXT 24 HOURS. AFTER A SPARKLING SUNNY AND WARM MONDAY...RAPIDLY
INCREASING SUB-TROPICAL MOISTURE AND UPPER LEVEL DYNAMICS ARE SET
TO BRING US OUR FIRST MEASURABLE RAINFALL IN MONTHS IN THE FORM OF
SCATTERED THUNDERSTORMS...A FEW POTENTIALLY QUITE STRONG. AFTERNOON
SATELLITE IMAGERY SHOWS CLEAR SKIES ACROSS THE ENTIRE DISTRICT...
WITH LOW CLOUDS AND PATCHY DENSE FOG HUGGING THE IMMEDIATE COAST.
LOOKING SOUTHWARD...GATHERING MID AND HIGH LEVEL MOISTURE CAN BE
SEEN NOW JUST ENTERING THE GOLDEN STATE...WITH ENTRAINMENT FROM
TROPICAL STORM MAX. OFFSHORE CUTOFF LOW APPEARS NEARLY STATIONARY...
AS IT HELPS TO PULL THE MOISTURE NORTHWARD IN A DEVELOPING DEEP
SOUTH TO SOUTHEAST FLOW.

[wxmann_91]

Well, perhaps I was wrong, Los Angeles might get this rain after all. (look at radar images I posted)

[aveosmth]

Yep, these cells are popping up very quickly, its really encouraging for tonight!! The familiar areas up here like Palos Verdes are already seeing some heavy showers and those should drop into Long Beach shortly.

I'm about 10-15 miles up the coast from PV, so I think I'll start seeing something later on tonight...

[weatherlover427]

We just had a nice shower here in Costa Mesa about 15 minutes ago, it was enough to wet the ground. I saw a good sized rainbow just to my east, as well as a couple lightning flashes further off in the distance.

[aveosmth]

The main band of moisture is now speeding up the coast and is now affecting portions of Orange County w/rain, thunder & lighting!

[weatherlover427]

Oh. My. Gosh.

We just had some of the loudest thunder and lightning I can recall here in quite some time. It must have only been a few hundred feet away because it was bright enough to trick the day/night sensors on the streetlights!

No strong winds with the line nor any hail that I could determine but there was heavy rain for a short duration. With this being the first rain since April, the roads are now very slick and I am sure there will be many accidents in this area tonight and tomorrow.

Here are some pictures and videos of the storm so far (56K users should only download pics with (Small) in the title):

http://www.blowsomesteamoff.net/miscell ... 9-19-2005/

[TT-SEA]

Where are you weatherlover427??

[aveosmth]

The LA NWS just stated that isolated areas of the forecast region may get up to an inch of rain!!!!

[weatherlover427]

I am where this white circle is:



Getting ready for round 2 as we speak...

[Geomagnetic Man]

Then the guy in this thread was telling the TRUTH?!!?
http://www.storm2k.org/phpbb2/viewtopic.php?t=74619

Because everything was as he said it was gonna be. I didnt even see the National Weather Service AFD discussions go into the detail that service provides.

Lightning, Thunder, Rain, Humid, its all here! Got time to prepare thanks to that service, I think it was Ontario Weather Service. They should join this forum and post forecasts for Southern California I think. Salute!

Stormy skies!

[wxmann_91]

Our second (major) round of rain is approaching just as I'm going to sleep. But there was a little bout of rain just a few minutes ago along with a pretty bright lightning bolt to the just to the south.

Good night!

[Geomagnetic Man]

Offically 12+hrs of straight thunderstorms, not one freakin break. If I didn't see lightning, then i heard the thunder from distant storms, but all in all, this was Record Breaking.. 12+ full hrs of thunder in southern california.