GeoMan's Southern California Weekend Storm Forecast

[wxmann_91]

Here is that AFD that you mentioned:

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 920 PM PDT THU OCT 13 2005

.SYNOPSIS...HIGH PRESSURE ALOFT AND WEAK OFFSHORE FLOW WILL BRING ANOTHER SUNNY AND WARM DAY FRIDAY. UPPER LEVEL LOW PRESSURE APPROACHING FROM THE NORTHWEST WILL CAUSE A DEEPENING MARINE LAYER AND COOLING SATURDAY. THE LOW WILL BRING MUCH COOLER WEATHER...LOCAL GUSTY WINDS AND A CHANCE OF SHOWERS AND THUNDERSTORMS SUNDAY INTO TUESDAY. FAIR AND WARMER DURING THE SECOND HALF OF NEXT WEEK.

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

NO MARINE LAYER LOW CLOUDS THIS EVENING AS WEAK OFFSHORE FLOW CONTINUES. STILL EXPECTING AN AREA OF STRATUS TO FORM OVER THE SOUTHERN SAN DIEGO COUNTY COAST LATE TONIGHT DUE TO SAN CLEMENTE ISLAND WAKE TURBULENCE. THAT WILL LIKELY CAUSE PATCHY DENSE FOG IN THAT AREA AS WELL. INVERSION IN THE PM SOUNDING WAS AT 1500 FEET...BUT EXPECT THAT TO LOWER TO 800 FEET OVERNIGHT AS WINDS RELAX AND AIR COOLS.

HIGH PRESSURE ALOFT WILL CONTINUE THROUGH FRI. THERE WILL BE LOCAL GUSTY WINDS THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES...MAINLY IN SAN COUNTY FRI MORNING. SUNNY AND WARM FRIDAY.

THE TROUGH IS STILL FORECAST TO CLOSE OFF NEAR SRN CA SUN. EXPECT DEEPENING MOISTURE SUN WITH MUCH STRONGER WINDS ALOFT AND ONSHORE FLOW AND COOLING ALOFT. EARLIEST START OF LIGHT SHOWERS SHOULD BE EARLY SUNDAY MORNING AS THE 554 LOW SETTLES OVER SCALIF. THE COLDER AIR ALOFT COULD PRODUCE THUNDERSTORMS SUN AFTERNOON. COOLER SAT AND MUCH COOLER SUN. THE SNOW LEVEL SHOULD BE ABOUT 6500-7000 SUN. THE 2 DAY SUN/MON RAINFALL TOTALS SHOULD REMAIN UNDER ONE HALF INCH MOST AREAS.

THE LOW WILL SLOWLY DRIFT SW...THEN MOVE BACK OVER THE AREA ON TUE. AS IT COMES WEST AGAIN...IT COULD TAP SUBTROPICAL MOISTURE AND BRING .75 TO 1.5 INCH RAINS ON TUE DUE TO THE INITIAL PLUME AND THE WRAP AROUND MOISTURE. TOO EARLY TO UP QPF...BUT THIS PATTERN BEARS WATCHING.

It can be found at this link. (time sensitive)

If the NWS says it; it's possible (they are right most of the time "note the word MOST").

Thanks for the link weatherlover.

[TT-SEA]

Yeah... I read about the fault slip.

The area north of San Francisco up to Oregon does get slammed.

We were looking for an area that is not too cold and not too hot. Gets regular storms. And is green with lots of trees. And we needed a big city for good jobs!! So we decided on Seattle.

I used to agonize over each storm down there. Waiting for some rain in the fall so it might turn a little green again. Knowing if a storm misses SoCal it could be 2 months before the next one hits. Last year was certainly an exception. I know whats it like to love storms and live in Southern California!!

Now I do not worry about any individual storm. I know if one misses there are 10 others waiting to hit!! I just hope we get more than last year... and much more snow. We had one good snowstorm last January at our house. The ski resorts in the mountains had their worst year ever.

[Geomagnetic Man]

Alright new model runs of the GFS, the model of choice in this system. It's showing a more storm pattern with the center moving West of Los Angeles a bit, and offshore, giving a southern like flow with heavy rain possible in spots. This should be watched, and it's going to be exciting.

[TT-SEA]

The NAM has been the model of choice with this system so far up here.

[weatherlover427]

Tim, I accept your apology btw. Should have stated that sooner but was busy on other sites.

Our local NWS offices seem to be going with the GFS for this system. They seem to think that it is handling the positioning and strength better than the NAM has, at least so far.

[TT-SEA]

Yesterday's runs of the GFS showed the initial upper low going to the northwest of Seattle this afternoon. The NAM showed it weakening and moving towards Astoria, Oregon.

The GFS was much stronger.

Today the NAM verified almost perfectly with this system.

For what its worth...

[TT-SEA]

I did not realize how miserably hot it was down there still. At least that will end either way!!

[TT-SEA]

Wow. The NAM really came around. Watch out guys... it will be exciting!!

[Geomagnetic Man]

Here's todays forecast I wrote up just now. Even threw in some watches out there to test. the watches are not official, but if I was forecasting 24hrs out, i'd put them there how I did it. enjoy.

...SHORT RANGE DISCUSSION...

MODEL ANALYSIS...Winter Storm Andrew is still on the track it showed yesterday. The GFS Analysis takes Andrew to the West of the forecast area over the LAX area by 5am tomorrow morning. Rush hour is around then, but since it's Sunday, less accidents will be reported. Given the location of the storm, the winds around Andrew will rotate from the southern direction, and give us moisture needed for a rain event. Andrew sticks around the coast till Tuesday night, when it's flushed out of here.

THE RAIN CHANCES...Winter Storm Andrew will be a light to moderate rain producer depending where you are. The further south you are from a mountain, the less rain you will receive out of this. Areas along the Santa Ana, San Gabriel, and San Bernardina Mountains will be most favorable. By 11pm tonight, expect few scattered showers around as the start of the lower level moisture arrives. by 5am this gets a bit more numerous as the almost full blunt of the moisture hits. Confused whether to add rain in this forecast, but if we are going to do this right, we will say scattered showers, and thunderstorms by sunrise Sunday. Look like from sunrise to 11am it will be rather drier. That will be the resting period, until after the noon hour. Moisture will be on the increase then, and we will then again sport the chance of rain. Heavy at times. Overnight on Sunday, into Monday, the rain chances are on the increase as 90% RH at 850MB settles over the area. Monday looks wetter, and even Monday night. This should just stick around till Tuesday Morning, then it's all gone. This will not be a flooding event, so a flood watch will not be posted.

THE THUNDERSTORM CHANCES... Andrew's chances for thunderstorms will begin Tonight at 11pm. Isolated at best, but increasing chances as we go toward sunrise. The value tonight goes from a 26, to a 27 by sunrise, however the RH is lower at the 11pm hr, than sunrise tomorrow, so the increase should give us Thunderstorms. With a 27C difference from 850 to 500MB Sunday Afternoon looks great for thunderstorm development. If we can get clear skies, and less high cloud cover, we could even be talking about the possibility of a Low Topped Super cell Thunderstorm. Maybe even a few of them. These storms can produce hail, gusty winds around them, and funnel clouds, or a weak tornado. Helicity around this time shows a value of 150-200 at 10,000 feet. This could be enough for a Tornado Watch Sunday Afternoon. This will cover the entire forecast area. Expect Monday to be the same. I'll update you tomorrow on a short and quick forecast on what to expect tomorrow. It will not be as long as these.

WIND CHANCES... Winter Storm Andrew will not be a hurricane like Hurricane Andrew, not even winds that close will be recorded from this. The dynamics needed for the bow echo type systems, the frontal winds will not hit the forecast area this time as far as current trends look. So winds do not look like a problem, and no wind watch will be needed at this time.


MEDIUM RANGE DISCUSSION...After Andrew, all looks calm again.



...WATCHES / WARNINGS / ADVISORIES...TORNADO WATCH, SEVERE THUNDERSTORM WATCH

Tornado Watch...A Tornado Watch for the entire forecast area. A Tornado Watch means that conditions will become right for tornadoes or waterspouts. This watch goes from 4am Sunday Morning, and ends at 7pm Sunday Night. New watches will be made if needed for Monday.

Severe Thunderstorm Watch...A Severe Thunderstorm Watch for the entire forecast area. A Severe Thunderstorms Watch means that conditions will become favorable for Severe Weather conditions. This case being an isolated tornado, wind, and hail. This will start at 4am Sunday Morning, and end at 7pm Sunday night. New watches will be made if needed for Monday.

ACTIVATED ALERTS...ACTIVATED

Winter Storm Andrew will stay a Category 3 Storm as it hangs around the forecast area. Rain, with Thunderstorms, minor flooding, and minor winds expected. Andrew will not be upgraded to a Category 4 storm.

GeoMan James

[wxmann_91]

Raining outside right now as I type...

[weatherlover427]

Funny, I go outside at 9:45pm top talk to a friend and it's dry. I go outside at 11:15pm, and the ground is wet. Wish the radars would update so I could see where this band came from.

[wxmann_91]

Some moderate rains an hour ago. There are some echoes north of Los Angeles, but everywhere in between here and there is dry.

This rain is associated with the weak and pretty much washed-out front, a sign of things to come. Both TWC and NWS have raised POPS significantly for Monday.

[wxmann_91]

Update...

The sun has come back out the last few hours, and thus the atmosphere has been destabilizing. An area of heavy showers and thunderstorms is currently training across the area from an Anaheim-Temecula-Borrego Springs-El Centro line southward to a Campo-Escondido-San Clemente line.

Severe Thunderstorm Warning in effect for Imperial County for five more minutes, and with this deep, rich plume of moisture directly from the Sea of Cortez, expect more warnings, possibly even Flash Flood Warnings. Flash Flood Watch in effect for eastern San Diego County, central Riverside County, and southwestern San Bernardino County. This watch does not include the cities of San Diego, Riverside, or San Bernardino, but does include this cities of Julian, Palm Springs, and Victorville.

[wxmann_91]

Another update...

Skies have rapidly turned dark around here, winds have suddenly turned from breezy to calm. The crows that I usually see and hear every day are gone. Eerily quiet and dark. The only thing that is not quiet are the planes that I hear periodically due to the Miramar Air Show today. Batten down the hatches!

EDIT: I hear thunder now! Gosh I am so excited! (Gosh I am also quite a freak am I not, I get excited for just a little rain?)

Radar image (composite reflectivity):

[wxmann_91]

Code: Select all

   MESOSCALE DISCUSSION 2338
   NWS STORM PREDICTION CENTER NORMAN OK
   0504 PM CDT SUN OCT 16 2005
   
   AREAS AFFECTED...SRN CA
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL...HEAVY RAINFALL
   
   VALID 162204Z - 170100Z
   
   HEAVY RAIN...ALONG WITH ISOLATED SVR HAIL AND/OR WIND IS EXPECTED
   THROUGH EVENING.
   
   LOW LEVEL MOISTURE APPEARS TO BE INCREASING INTO THE LOWER CO RIVER
   VALLEY AND SRN CA.  NEARBY GPS WATER VAPOR MEASUREMENTS INDICATE
   ANYWHERE FROM 1.00-1.25 INCHES BUT MODIFIED FORECAST SOUNDINGS YIELD
   ONLY MARGINAL INSTABILITY WITH AROUND 500-1000 J/KG MUCAPE.
   
   LOW LEVEL UPSLOPE FLOW WILL PERSIST THROUGH THE EVENING
   HOURS...WHICH WILL LIKELY ALLOW FOR REGENERATION OF STORMS MAINLY E
   OF THE COASTAL RANGE. COLD TEMPERATURES ALOFT AND WIND PROFILES
   SUPPORTIVE OF SUPERCELLS SUGGEST HAIL IS POSSIBLE...AND TO A LESSER
   EXTENT STRONG WINDS. INCREASING MOISTURE AND PERSISTENT UPSLOPE
   SUGGEST LOCALLY HEAVY RAIN AND POSSIBLE FLOODING MAINLY E SLOPES.
   
   ..JEWELL.. 10/16/2005
   
   
   ATTN...WFO...PSR...VEF...SGX...
   
   32641633 33371646 33781675 34041681 34131659 33971620
   33601553 33271501 32691459 32591605

[Geomagnetic Man]

Here's today's forecast discussion, remember these are my forecasts, and not officially a NWS forecast. For NWS forecasts, visit http://www.nws.noaa.gov and click on your region. Thank you.

WINTER STORM ANDREW FORECAST

ANDREW UPGRADED TO CATEGORY 4 WITH RAIN, AND THUNDERSTORMS, WITH MAJOR FLOODING EXPECTED TOMORROW EVENING!

DISCUSSION ... FOR ALL OF SOUTHWESTERN CALIFORNIA INCLUDING ALL OF ORANGE COUNTY ... SOUTHERN LOS ANGELES COUNTY ... WESTERN RIVERSIDE COUNTY ... AND SOUTHWESTERN SAN BERNARDINO COUNTY ...

SYNOPSIS....Winter Storm Andrew passed us this morning, and is now South of the forecast area. Expect Andrew to gain strength out there, and move back inland tomorrow evening, as a Category 4 Storm, The 2nd highest of the Levels.

PRE-STORM FACTS: We use this section to tell you the conditions before the storm. If we tell you a condition and it comes true when we say it, expect the storm to be on track! The condition will be nothing, the Storm is here.

...SHORT RANGE DISCUSSION...

MODEL ANALYSIS...Winter Storm Andrew is South of us, and West of San Diego. The GFS continues to show it moving out of the area by Tuesday. Moisture in the models is saturated tomorrow afternoon, into the night,

THE RAIN CHANCES...Winter Storm Andrew will be a moderate to heavy rain producer South of the San Gabriel and San Bernardino Mountains. Areas along the foothills, and close by will receive the most rain. Today, it rained as forecast. Light to Moderate, as forecast. So we are right on the money with this system. Tonight, the low level moisture will be on the decrease tonight, so rain chances will go down, to none tonight, however this will happen rapidly after midnight. Rain before then, like this evening should be moderate. A plume of moisture coming in from thunderstorm complexes near Yuma, Arizona will drift overhead this evening, and create rain showers. The increase in rain will happen again tomorrow morning after sunrise, and into the afternoon, when daytime heating occurs, and creates instability. The rain chances will be the greatest Tomorrow evening from 5pm, to 11pm. This will be an amazing rain event for this time of year. The southerly winds will hit the Mountains north of here, bounce back, and great a massive rain shield covering from Los Angeles, to Palm Springs. Most favorable will be in the Los Angeles County Northward, and eastward into Northern Riverside County. Northern Orange County will have a good chance as well, but not as good because of orthographic lifting is sparse there. Southern Orange County will see the least rain coverage. Throughout the night after midnight Monday, into Tuesday Morning, the rain will move to the North of the forecast area, in the Lancaster area, and be done with us for good. The heavy rains will have passed us by Sunrise Tuesday. Not much rain expected throughout the day Tuesday.

THE THUNDERSTORM CHANCES... Andrew's chances for thunderstorms will exist throughout the forecasted period, from tonight, till Tuesday. Although not much expect tonight, we could see numerous thunderstorms tomorrow evening, and into the night! Thunderstorms could be severe in spots. No watches or warnings will be posted for tonight, but one will be posted for Monday Evening, into the night.

WIND CHANCES... Winter Storm Andrew will not be a hurricane like Hurricane Andrew, not even winds that close will be recorded from this. The dynamics needed for the bow echo type systems, the frontal winds will not hit the forecast area this time as far as current trends look. So winds do not look like a problem, and no wind watch will be needed at this time.


MEDIUM RANGE DISCUSSION...After Andrew, all looks calm again.

GeoMan James

[wxmann_91]

It has been raining nonstop for almost three hours now (since I last posted, in fact).

24 hour precip totals so far (note that some places have already received more than an inch of rain): RIGHT HERE

Storm total precip so far: RIGHT HERE

[wxmann_91]

Flash Flood Warning for San Diego County:

Code: Select all

CAC073-170430-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN DIEGO CA
730 PM PDT SUN OCT 16 2005

THE NATIONAL WEATHER SERVICE IN SAN DIEGO HAS ISSUED A

* FLASH FLOOD WARNING FOR..
EAST CENTRAL SAN DIEGO COUNTY IN SOUTHWEST CALIFORNIA

* UNTIL 930 PM PDT

* AT 724 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
FLASH FLOODING FROM THUNDERSTORMS ALONG A LINE EXTENDING FROM 10
MILES NORTH OF OCOTILLO WELLS TO 6 MILES SOUTHWEST OF OCOTILLO
WELLS...MOVING NORTHWEST AT 25 MPH.

* THUNDERSTORMS PRODUCING FLASH FLOODING WILL BE NEAR..
OCOTILLO WELLS AT 740 PM PDT
BORREGO SPRINGS AT 750 PM PDT

RAINFALL AMOUNTS OF ALMOST AN INCH IN A HALF HOUR HAVE BEEN
OBSERVED. ADDITIONAL RAINFALL AMOUNTS OF ANOTHER HALF INCH ARE
POSSIBLE IN THE WARNED AREA.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

LAT...LON 3339 11608 3300 11609 3309 11651 3340 11647

$$

BALFOUR

[Geomagnetic Man]

Yup, if I were forecasting for your Area Tim, it would be alot to talk about alot in these storms, but my window only goes down to the Northern Tip of San Diego County. Anyway, I expect a round tonight, then drying, then a major deluge tomorrow evening! Cant wait! Was that a BUST Tim?

I am continuing the upgrade from 3 to Category 4 from Andrew at landfall tomorrow!

GeoMan James

[wxmann_91]

Yup, if I were forecasting for your Area Tim, it would be alot to talk about alot in these storms, but my window only goes down to the Northern Tip of San Diego County. Anyway, I expect a round tonight, then drying, then a major deluge tomorrow evening! Cant wait! Was that a BUST Tim?

I am continuing the upgrade from 3 to Category 4 from Andrew at landfall tomorrow!

GeoMan James

I am Jim.

Of course it was not a bust but I was concerned that it would be again. And the drying tonight/tomorrow morning and deluge tomorrow evening scenario was what my local met was saying also.