Dec 16 - ? West (California) Winter Storm OBS, Last Minute Forecasts & OBS Options

[Al.J]

Based on latest forecasts there exists the possibility of a major shift in the weather pattern over California producing copious amounts of rainfall from the northern to the southern parts of the state. The GFS and the Euro both project several inches and in some cases close to a foot of rainfall over the course of 4-5 days starting late next week and continuing into the the week of Christmas. We could even see low snow levels( possible white Christmas for those who don't usually see it). More to come in the days ahead, especially if the model projections pan out.

[Al.J]

Just took a quick glance at what the MJO discussion was and it seems that the MJO signal is strengthening at a good rate with an eastward propagation. What this means, we could be looking at a real storm threat and what the models are portraying may actually be what they are projecting because of the MJO activity. In other words, this may be the real deal here

[alxz310]

Things aren't looking too bad for us yet. Most areas as of the end of Nov are running around average for rainfall so far (some above even, with the exception being Downtown LA). The 00Z GFS brings 0.46" within the 192hr period for us.

[Al.J]

Obvious warning from the NWS in SF on the upcoming pattern change:

"THEN ALL SIGNS ARE POINTING TO A POTENTIAL MAJOR PATTERN SHIFT TO WET AND UNSETTLED WEATHER FROM THURSDAY AND INTO NEXT WEEKEND. OBVIOUSLY SEVERAL DAYS OUT BUT
PRETTY GOOD MODEL CONSENSUS FOR A LARGE SCALE TROUGH OFF OUR COAST
THAT WILL PERIODICALLY TAP INTO SUB-TROPICAL MOISTURE...JUST AS THE
BUSY HOLIDAY TRAVEL PERIOD BEGINS. LONG RANGE FORECAST WILL BE
INTERESTING TO WATCH THE NEXT SEVERAL DAYS."

Source: http://www.wrh.noaa.gov/total_forecast/get...R&version=0

[Al.J]

Awaiting the 12Z Euro but so far it's looking very wet as well. One thing that bears watching is that there will be cold air around, which means some places will get snow when they don't normally receive it as 850MB temps fall to -2C and heights at the 500MB fall to 530DM.

[Al.J]

Euro shows 1.36" for Napa next Thursday from just one storm but that's not the only rain for next week, 0.52" is forecast by the Euro for Tuesday. Looks wet and for the extended wetter by each successive run. Here we go, the MJO is beginning to throw some decent storms our way!

[alxz310]

Euro shows 1.36" for Napa next Thursday from just one storm but that's not the only rain for next week, 0.52" is forecast by the Euro for Tuesday. Looks wet and for the extended wetter by each successive run. Here we go, the MJO is beginning to throw some decent storms our way!

Do you know of any free site that offers Euro text output.. or even precipitation maps for that matter? I know the GFS, NAM and GEM have those but I've only been able to find 850mb temps and upper atmosphere maps for the ECMWF.

The 12Z GFS now gives us 0.96" of precipitation within the first 192hr period. GGEM Ensembles give us around 1.00"-1.25" through the next 10 days.

This post has been edited by alxz310: Dec 11 2010, 02:15 PM

[Al.J]

Do you know of any free site that offers Euro text output.. or even precipitation maps for that matter? I know the GFS, NAM and GEM have those but I've only been able to find 850mb temps and upper atmosphere maps for the ECMWF.

The 12Z GFS now gives us 0.96" of precipitation within the first 192hr period. GGEM Ensembles give us around 1.00"-1.25" through the next 10 days.

I honestly don't, in fact until recently even Accuweather PRO didn't even have that available. My best advice to you is go with the 30 day free trial of Accuweather PRO

The GFS gives Napa about 4.7" which is a massive amount of percip, hope it continues to show that

[Al.J]

18Z GFS just initializing right now, more to come soon

[Al.J]

Oh yeah the GFS is showing a massive storm for next weekend, looks like the models are locking in on an increasing possibility of a major storm for the end of next week and into next weekend. Will it happen? I don't know, but it's looking more likely with each successive run on the GFS and the Euro.

[Al.J]

To give everyone an idea, the 18Z GFS is showing 4.5" from next Thursday thru the following Monday for the Napa area along with winds gusting to near 60MPH.

[Al.J]

From the NWS in SF, their afternoon discussion for today:

"RIGHT NOW WEDS LOOKS LIKE THE BREAK DAY WITH DRY WEATHER. THE LAST
TWO GFS RUNS BRING STEADY RAIN BACK BY THURSDAY WITH A SUB-TROPICAL
TAP WHILE THE ECMWF HOLDS OFF UNTIL FRIDAY. BOTH MODELS AND
ENSEMBLES SHOW WET AND UNSETTLED WEATHER CONTINUING THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK. ANY DETAILS ARE MURKY AT THIS
TIME BUT POTENTIAL FOR SIGNIFICANT RAINFALL WITH SUB-TROPICAL TAP
AND COPIOUS SNOW IN THE SIERRA AS WE HEAD INTO THE BUSY HOLIDAY
TRAVEL PERIOD. WILL CONTINUE TO MONITOR LONG RANGE TRENDS. "

Source: http://www.wrh.noaa.gov/total_forecast/get...R&version=0

[Beck]

I envy your forecast

Updated signature, a bit late this time.

[Weatherjunkie]

Yeah, we'll see if the MJO shift can bring the GOA low into the Pac NW and drive in the Pineapple express for much of the W US seaboard. An active MJO into phase 6 could be interesting. Generally that type of shift raises the chances of above average temps in the SW US, so there may be a battle zone for Cali. I suppose you can't have a major storm without the threat of above average temps now can ya? Or does that only happen in the MW/E US ?

[Al.J]

I envy your forecast

Updated signature, a bit late this time.

You'll be getting wet as well Beck, in fact the GFS is showing nearly 2" for SNA for that same time period. It's going to be a statewide event.

[Al.J]

Yeah, we'll see if the MJO shift can bring the GOA low into the Pac NW and drive in the Pineapple express for much of the W US seaboard. An active MJO into phase 6 could be interesting. Generally that type of shift raises the chances of above average temps in the SW US, so there may be a battle zone for Cali. I suppose you can't have a major storm without the threat of above average temps now can ya? Or does that only happen in the MW/E US ?

Hey, weatherjunkie, glad to see you on the West Coast thread. Your analysis of the MJO is much appreciated

Do you think that the models are capturing a possible scenario because of the MJO activity currently or is there more to come from the MJO?

[Weatherjunkie]

Hey, weatherjunkie, glad to see you on the West Coast thread. Your analysis of the MJO is much appreciated

Do you think that the models are capturing a possible scenario because of the MJO activity currently or is there more to come from the MJO?

I think they have the MJO understood as forecasts have it going into phase 6 and potentially briefly into 7 which subsequently is pushing the GOA low E into the W US along with solid Pac moisture flow.

It does look like for your neck of the woods the temps will be just fine, but inland towards the four corners region and up toward Wyoming there exists potential for above average temperatures. I'm not too familiar with the topography, so those above average temps may be meaningless.

This post has been edited by Weatherjunkie: Dec 11 2010, 06:14 PM

[Al.J]

I think they have the MJO understood as forecasts have it going into phase 6 and potentially briefly into 7 which subsequently is pushing the GOA low E into the W US along with solid Pac moisture flow.

It does look like for your neck of the woods the temps will be just fine, but inland towards the four corners region and up toward Wyoming there exists potential for above average temperatures. I'm not too familiar with the topography, so those above average temps may be meaningless.

Given that information, what's the worst case scenario in your opinion in terms of a major storm in such a MJO phase and conditions?

With 850MB temps in the low single digits that would put surface temps in the low 50's for my area and snow levels based on the 500MB heights down to about 4000ft.

[alxz310]

I envy your forecast

Updated signature, a bit late this time.

Have you looked at the 18Z GFS? Because all I can say is HOLY *bleep*. It gives us 3.18" of precipitation by the end of next week! That's an IMMENSE amount of moisture for us. Looks like a strong subtropical moisture tap

[Al.J]

Have you looked at the 18Z GFS? Because all I can say is HOLY *bleep*. It gives us 3.18" of precipitation by the end of next week! That's an IMMENSE amount of moisture for us. Looks like a strong subtropical moisture tap

Absolutely correct, this would be quite a bit of percip. I think this is the real deal here, the pineapple express is coming to town!