Here we go again in southern California

[weatherlover427]

Just when we thought that we could dry out ... more rain is on the way. We need it but not all at once.

SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE SAN DIEGO CA 945 PM PDT SAT OCT 23 2004

...

A STORM SYSTEM FORMING OVER THE GULF OF ALASKA WILL MOVE SOUTH AND REACH PARTS OF SOUTHERN CALIFORNIA BY TUESDAY. THE BRUNT OF THE STORM WILL ARRIVE IN SOUTHWESTERN CALIFORNIA TUESDAY NIGHT AND WEDNESDAY. HIGH AMOUNTS OF MOISTURE COMBINED WITH STRONG WINDS ALOFT AND INSTABILITY WILL RESULT IN LOCALLY HEAVY RAINS...ESPECIALLY ALONG THE MOUNTAIN SLOPES. STRONG GUSTY WINDS WILL OCCUR OVER THE MOUNTAINS AND DESERTS...AND LOCALLY AT THE COAST. SNOW WILL FALL OVER HIGHER ELEVATIONS...MAINLY ABOVE 6000 FEET DUE TO UNUSUALLY COLD AIR ALOFT...ESPECIALLY LATE IN THE STORM.

RAINFALL ESTIMATES ARE FOR ONE TO LOCALLY TWO INCHES IN THE COASTAL AREAS AND VALLEYS...TWO TO FOUR INCHES ON THE WEST AND SOUTHWEST FACING MOUNTAIN SLOPES...AND LESS THAN HALF AN INCH IN THE DESERTS. HIGHEST RAINFALL TOTALS WILL BE ON THE SOUTHWEST FACING SLOPES OF THE SAN BERNARDINO COUNTY MOUNTAINS WHERE LOCALLY 5 INCHES OF RAIN COULD FALL.

FLOODING PROBLEMS WILL BE POSSIBLE FROM MOUNTAINS WEST TO THE COAST. MUD SLIDES AND DEBRIS FLOW IN AND BELOW THE RECENTLY BURNED AREAS COULD CAUSE ROAD CLOSURES AT TIMES.

THE STORM WILL MOVE EAST THURSDAY...BUT ANOTHER SYSTEM COULD BRING SHOWERS FRIDAY OR SATURDAY.

MAXWELL

[weatherlover427]

Look at this monster vort that is projected to plow through my area at day 3.5 (by the AVN / GFS model) :



I live approximately where the white square is in the inset (hand crafted by me ). That is one big huge vort.

Not only that but tonight's run of the GFS (which our local NWS is blending with the ETA model to forecast this storm) is now forecasting more QPF, colder temps aloft, plus this big huge vort (which is up from only 30 in the last run ). We will see how it all plays out.

[aveosmth]

What are the chances of seeing thunderstorms tomorrow or Wednesday with this storm?? It been just about a year to the day when we had that HUGE hailstorm here in Los Angeles....I remember some areas getting 18 inches of hail....that was one amazing storm.

[weatherlover427]

They are looking rather good. The San Diego NWS has increased their thunderstorm wording from slight chance to chance. Plus the SPC has this area in a 5% risk for severe storms on days 2 and 3. So we shall see what happens. The ingredients appear to be coming together for some good storms, particularly on Wednesday IMO.

[yoda]

Stay safe out there guys!

[riverratmike]

what about thunderstorm chances here in Lake Havasu City, AZ? Anyone know

[yoda]

what about thunderstorm chances here in Lake Havasu City, AZ? Anyone know

No Tstorms there... sorry bud...

http://www.crh.noaa.gov/forecasts/AZZ00 ... avasu+City

[yoda]

Watch out Josh!!!

ELSEWHERE...PRESENCE OF 50-60 KTS OF MIDLEVEL FLOW MAY AUGMENT STORM
ORGANIZATION WITHIN THE FRONTAL RAINBAND AS IT MOVES E INTO THE
CNTRL VLYS AND S INTO SRN CA LATE TUESDAY. SET-UP APPEARS FAVORABLE
FOR ISOLD DAMAGING WINDS WITH ANY STRONGER STORM... THOUGH HEATING
WILL BE MITIGATED BY CLOUDS. SLIGHTLY STRONGER INSTABILITY WILL
EXIST ALONG THE TAIL END OF THE FRONT TUESDAY NIGHT ALONG THE SANTA
BARBARA/LOS ANGELES COASTS. ETA FORECAST SOUNDINGS SHOW A 2-4 HOUR
PERIOD WHERE LOW-LEVEL HODOGRAPHS BECOME ENLARGED WITH 0-1 KM SRH IN
EXCESS OF 200 M2/S2. THUS...IT IS CONCEIVABLE THAT ISOLD TORNADOES
COULD OCCUR LATE TUESDAY NIGHT.



from SPC Day 1 Outlook

[aveosmth]

I've never been even close to a tornado & the idea that there is even a remote chance is very scary!!!! I don't even know how we would be warned here in SoCal at that time of night.....there may be something in place, but I doubt it...Ill keep you guys posted.

Aveo

[yoda]

I've never been even close to a tornado & the idea that there is even a remote chance is very scary!!!! I don't even know how we would be warned here in SoCal at that time of night.....there may be something in place, but I doubt it...Ill keep you guys posted.

Aveo

1300 Discussion from SPC ( http://www.spc.noaa.gov )

..CA...
AN UPPER-LEVEL LOW WILL DIG SWD ALONG THE WEST COAST TODAY SPREADING
A BAND OF STRONG LARGE-SCALE ASCENT ACROSS NRN AND CNTRL CA THIS
AFTERNOON. IN RESPONSE TO THIS...STORMS WILL CONTINUE TO MOVE SSEWD
TOWARD LAX THIS AFTERNOON. ALTHOUGH INSTABILITY WILL BE RELATIVELY
WEAK...LAPSE RATES WILL STEEPEN AS COLD AIR ALOFT ADVECTS SWD. THIS
COMBINED WITH STRONG VERTICAL SHEAR WILL BE SUPPORTIVE OF STRONG
MULTICELL STORMS WHICH WILL BE EMBEDDED IN THE HEAVIER RAIN. THE
STRONGEST CELLS WILL BE CAPABLE OF MARGINAL WIND DAMAGE AND/OR HAIL
CONSIDERING THE STRONG SHEAR AND STEEPENING LAPSE RATES. AS THE BAND
OF MODERATE TO HEAVY RAIN MOVES FARTHER SOUTH AND SFC TEMPS WARM
UP...A FEW MINI-SUPERCELLS WILL BE POSSIBLE CONSIDERING 0-6 KM SHEAR
WILL EXCEED 50 KT. IN ADDITION...FORECAST SOUNDINGS SUGGEST
LOW-LEVEL SHEAR WILL INCREASE OVERNIGHT WITH 0-1 KM SHEAR VALUES
REACHING 25 KT IN THE LA VICINITY. THIS SHOULD RESULT IN A MARGINAL
TORNADO THREAT WITH ANY MINI-SUPERCELLS THAT MOVE INLAND ALONG THE
IMMEDIATE COAST.

[aveosmth]

Thanks for the update...I live right along the coast in Los Angeles county, so I'll be watching this very closely....should be a long night for us out here.

[Tornado_Chaser2005]

What do you think? A Severe Thunderstorm Warning was for San Luis Obispo. I snapped the radar images that show what I believe might have been rotation within the line.
On the first photo , you can clearly see the rotation. I marked the area by the white arrow.


On the second images is the same exact one of the top one, but it's zoomed in. I can see what I believe to be a clear area of Inflow coming into that rotation, which is a sign of possible rotation even more. The arrow on top shows the rotation center, the arrow on the bottom shows the Clear slot next to it.

[aveosmth]

I wonder when those cells are going to get to us here in LA County....they already are strong as is and they are going to be even more enhanced tonight....wow that is scary....btw, excellent work on the analysis...any thoughts as to the strength of those cells when they reach socal?

[Tornado_Chaser2005]

Those cells yes, are very strong now, and will only be more stronger in our area. I cant believe the look in it. By the way, I have another radar image for you. This just came out of the Vandenberg Radar. Is that what I think it is? THe arrow shows the main updraft rotation with hail core to the North. This is a classic look of what could possibly be a mini supercell.

aveo, Ill be on all night tonight, and I will supply radar images like this on here when awesome storms happen. The radar image is smoothen down to show the direct detail ALL radars should. Thanks!

[aveosmth]

I really appreciate the radar images...those are much, much better than the ones I'm used to....My buddy at Cal Poly San Luis Obispo just told me they had gusts up to 65 mph come through there....he said it lasted for like 30 min to an hour and the rain was falling sideways....if this thing is going to get stronger as it approaches this could turn downright scary....I know we are not prepared here for major wind gusts here in the South Bay...once again thanks for the radar AND analysis, it is very much appreciated!!!!!!!!!

[Tornado_Chaser2005]

More cells are starting to show themselves. Its like these are quick supercells, then they vanish fast. The hold rotation for about 15 minutes before fading. This area is under 150 1km helicity right now. Those of you in the Los Angeles Area, where I am, the latest models indicate helicity approaching 250 at 1km tonight through tomorrow morning. That is our window to see supercells here. Numerous rotation signatures are already showing up in the Vandenberg Area North. The radar loop looks like a tidal wave coming into California, where the lead edge is sharp as all heck. This is another radar image of what looks like another hook echo. It was very short lasting as well, but look at the characteristics there. You can see the inflow into the hook as noted from the white arrow I put there.

[aveosmth]

It looks like another strong cell was just offshore as well on that last radar image. I thought most of the instability would happen on the back side of this front when the cold core of the low came onshore...it looks like with this storm these embedded cells are going to give us our first shot of strong to severe tstorms....so, we may have two bouts of severe weather, one caused by the leading edge of the front & the second due to the combo of diurnal heating & the cold core of the front tomorrow afternoon....WOW...have you seen anything like this in SoCal in October?? I can't think of another time....this is much more like Jan or Feb....this would even be crazy for those months.

[Tornado_Chaser2005]

Your welcome Aveo, wow those are some high wind numbers! I am very excited about this event tonight through tomorrow. Everything points to Supercells here in Los Angeles Area. Looking at the latest models, we have -20c 500mb Temps coming overhead at peak helicity time, so that is more than enough instability to cause Thunderstorms. With the shear profiles over our area during that time, it looks favorable for these thunderstorms to start rotating. They are saying LA Coast, but looking at latest models, it seems the most likely area will be inland LA county, near the Riverside county Line, probably Chino area, maybe Ontario as the highest helicity profiles of nearing 275-300 at 1km hit that area. sure LA will see the chance of supercells even with it's 200 helicity at 1km. The Tornado Threat looks to stop directly by mid morning for the LA area, but continue in the Inland Empire areas. The 500mb temps will still be very cold aloft, so waterspouts can be possible in the coastal waters off any of the county coasts tomorrow, but funnel clouds inland will not be. This looks to be a quick moving helicity area lasting about 4 hrs. But you never know. That four hrs might be the worst Severe Weather Southern California has seen for a long time. Glad you like the radars, they will keep coming.

MESSAGE TO THE ADMINS:
I will be posting images on this thread, however when the storm passes, they will be gone to free up the forum space.

[Tornado_Chaser2005]

Just saw your post again, you asked if I seen anything like it. Not at all for October, not even any other month really for the longest time I can reemember. I do remember some years back a Valentines Severe Tstorm Event. That was pretty amazing. Look at the Vandenberg Radar. Loop it if you can. This is why its happening on this side. You dont even need models to see the helicity. You can definetly see it on radar. Look at the front coming in. You can see which way its moving. Look ahead of the front when an echo appears. Its going to the North along the front as the front plows in from the west. That is excellent proof that rotation exists in this right now:)

Tornado Chaser

[Tornado_Chaser2005]

Looks like the Vandenberg Radar was wiped out. It no longer updating , and very high winds were in the area near the time, so It's gone for a bit.