April 7-11 West (California) Unusually Cold "Winter" Storm, Reality: Short Range [0-3 Days Out] Forecasts & OBS Options

[Artisane]

Looks like we have the potential for a cold cutoff low to come into California this weekend. The models seem to all be in agreement as to the timing, but differ on the amount of precipitation.

GFS is showing a colder and drier system while the NAM shows a slightly warmer, yet much wetter storm. Snow levels may be down to 3000-4000ft depending on which model you look at.

Highs for Palmdale/High Desert look to be barely reaching 50F on Friday/Saturday. The winds will also be an issue with gusts possible +75mph.

http://www.wrh.noaa.gov/lox/scripts/getpro...fd&back=yes

.LONG TERM (FRI-MON)...THE CHANCE POPS CONTINUE IN THE THURSDAY NIGHT TO FRIDAY PERIOD AS THE SYSTEM IS LOCATED NEAR POINT CONCEPTION. THE COLD AIR BEGINS TO ARRIVE ON FRIDAY. LET ME SAY IT AGAIN. THIS IS A COLD SYSTEM WITH THICKNESS DOWN TO 532 AND 500 MB TEMPERATURES DOWN TO -28C...IN APRIL NO LESS. THE COMBINATION OF APRIL SUN AND COLD AIR ALOFT WILL RAISE THE POSSIBILITY OF A SLIGHT CHANCE OF THUNDERSTORMS JUST ABOUT ANYWHERE...WITH THE USUAL POSSIBILITY OF BRIEF HEAVY RAIN. A SLIGHT CHANCE OF THUNDERSTORMS HAS BEEN ADDED TO THE AFTERNOON FORECAST FOR FRIDAY. DUE TO THE EXTREMELY COLD AIR WE COULD SEE SNOW LEVELS COME DOWN TO AROUND 3000 FEET OR EVEN LOWER...IN APRIL NO LESS. THE SNOW COULD BRIEFLY REACH PORTIONS OF THE ANTELOPE VALLEY AND THE UPPER REACHES OF THE SANTA BARBARA MOUNTAINS. IT IS STILL TOO EARLY TO KNOW IF ALL OF THIS IS GOING TO COME TOGETHER AS ADVERTISED BY THE MODELS...BUT CURRENT MODEL CONSENSUS IS REMARKABLE.

This post has been edited by Artisane: Apr 7 2011, 08:47 AM

[Beck]

I like this:

.THURSDAY...PARTLY CLOUDY WITH A SLIGHT CHANCE OF RAIN. HIGHS
59 TO 65.

.THURSDAY NIGHT...CLOUDY WITH A SLIGHT CHANCE OF RAIN. LOWS 41 TO
47.

.FRIDAY...MOSTLY CLOUDY WITH A CHANCE OF SHOWERS AND SLIGHT
CHANCE OF THUNDERSTORMS. HIGHS 50 TO 57.

.FRIDAY NIGHT...MOSTLY CLOUDY WITH A CHANCE OF SHOWERS AND SLIGHT
CHANCE OF THUNDERSTORMS. LOWS 35 TO 43.

.SATURDAY...PARTLY CLOUDY WITH A CHANCE OF SHOWERS AND SLIGHT
CHANCE OF THUNDERSTORMS. HIGHS 53 TO 61.

Does this remind anyone of the April 2001 winter storm?

[Artisane]

I like this:
Does this remind anyone of the April 2001 winter storm?

I don't really recall that storm since I lived in La Crescenta at the time. What were the details on it?

[FrostFuzz]

This storm has kept my attention. Also there is a slight chance of precip from the low coming in from the southwest from tonight through Wednesday, primarily for areas south and east. Not a great chance but it is worth keeping an eye on since these types of events have a history of surprising forecasters and models.

[FrostFuzz]

I like this:
Does this remind anyone of the April 2001 winter storm?

Hmm I don't remember either but looking it up I see three separate thunderstorm events. One on the 9th and another on the 21st that brought significant rainfall and another that lasted 3 days from the 26-28. That is not to mention several other rainfall events looks like an active month

[LALEO]

This is an interesting one and I'm having a difficult time putting my finger on it. I'm concerned about the smaller Low that is relaxing West of the Baja Peninsula right now and slowly moving towards the NE into Southern California. On top of that you have a cut off Low moving in from the NE to the SW swinging down the coast into Southern California....What will happen? I don't have the slightest idea..However...I will add the potential for a wet rain maker is certainly there or things could be a quick hit it and quit it, here's your .10" of rain. At this time I'd imagine LA County to be the red zone with this and these types of storms... Interesting to see what happens..

Off to work for now, You guys enjoy your day!

[Beck]

I don't really recall that storm since I lived in La Crescenta at the time. What were the details on it?

Hmm I don't remember either but looking it up I see three separate thunderstorm events. One on the 9th and another on the 21st that brought significant rainfall and another that lasted 3 days from the 26-28. That is not to mention several other rainfall events looks like an active month

Well, there were two that month: One in early April and one near the end of the month - both of those storms unusually cold, giving us highs in the low to mid 50's and both roughly 0.50" rain each. I'd like that again....

Either way, right now we're looking at around 1/3 of an inch from this storm beginning Thursday night lasting through Saturday. I also like those t-storm chances we have on Friday.

[Artisane]

00Z EURO came in much warmer and with almost no precip.
06Z GFS has .05" of precip spread over three days.
NAM is still running, but it looks warmer as well.

[alxz310]

This is an interesting one and I'm having a difficult time putting my finger on it. I'm concerned about the smaller Low that is relaxing West of the Baja Peninsula right now and slowly moving towards the NE into Southern California. On top of that you have a cut off Low moving in from the NE to the SW swinging down the coast into Southern California....What will happen? I don't have the slightest idea..However...I will add the potential for a wet rain maker is certainly there or things could be a quick hit it and quit it, here's your .10" of rain. At this time I'd imagine LA County to be the red zone with this and these types of storms... Interesting to see what happens..

Off to work for now, You guys enjoy your day!

I have the same thoughts as you. Looks like we might actually get some light precip from that cutoff low (The NAM is outputting 0.02") and the cold low after that is difficult to forecast... The NAM does put out some convective showers, but has very little in the way of precip (0.06"). Could very well get a thunderstorm with the amount of cold air aloft (-33C) and considering it's April. However, from previous experience I know the LA county coast isn't exactly the prime spot for interesting thunderstorms. Other areas (inland, OC) however could be in for a treat. TWC for one appears to be pretty aggressive showing windy conditions and moderate rain...

This post has been edited by alxz310: Apr 5 2011, 07:37 PM

[FrostFuzz]

I think it is kinda strange that the NWS only has a 30% chance of precip but between a third and a half an inch of rain forecast. I wonder what they are thinking...

[Beck]

I think it is kinda strange that the NWS only has a 30% chance of precip but between a third and a half an inch of rain forecast. I wonder what they are thinking...

I agree.....those are rather high amounts for such small chances of getting it in the first place. We have a 40% chance of showers/thunderstorms on Friday, and that's our best.

[Artisane]

Maybe they're expecting very heavy, isolated storms?

[Beck]

Maybe they're expecting very heavy, isolated storms?

Hmm, sounds like monsoon thunderstorms to me

[Artisane]

accuweather has a high of 40F for us on Friday. That's just unreal for April.

[Artisane]

Very low snow levels out of this possible.

http://www.wrh.noaa.gov/lox/scripts/getpro...fd&back=yes

THIS UNSEASONABLY COLD WEATHER SYSTEM IS ALSO EXPECTED DROP SNOW LEVELS SIGNIFICANTLY...DOWN TO AS LOW AS 2000 FT BY EARLY FRIDAY MORNING. IT APPEARS SNOW SHOWERS WILL AFFECT INTERSTATE 5 OVER NW L.A. COUNTY AND OVER THE GRAPEVINE...AND ALSO HIGHWAY 14 THRU SOLEDAD CANYON LATE THU NIGHT INTO FRI MORNING WITH LOCAL MINOR SNOW ACCUMULATIONS POSSIBLE.

[Beck]

Very low snow levels out of this possible.

http://www.wrh.noaa.gov/lox/scripts/getpro...fd&back=yes

As much as I want to believe that, I highly doubt it for this time of year...

It's been cloudy, occasionally fogg, and low visibility all day so far.....some drizzle at random parts of the morning too.

[Artisane]

As much as I want to believe that, I highly doubt it for this time of year...

Both the GFS and NAM have sub freezing temps for us Friday morning, so its possible. Its all going to depend on how much moisture is around.

[alxz310]

Both the GFS and NAM have sub freezing temps for us Friday morning, so its possible. Its all going to depend on how much moisture is around.

Well, the NAM seems to be a bit more generous with moisture in general giving about .10-.25" over most areas, higher over southern Orange and SD counties. Previous runs were drier.

[vb3347]

I've been getting some light drizzle all day here, nothing measurable, just enough to keep the ground wet. Some stations around the valley are reporting 0.01"...

A nice break from the triple digit heat last week

[Artisane]

Well, the NAM seems to be a bit more generous with moisture in general giving about .10-.25" over most areas, higher over southern Orange and SD counties. Previous runs were drier.

I agree, it does seem more generous.