[pct-l] Fw: [DCSAR] Interesting and ominous weather predication

[Bill Burge]

Thanks for posting this!  The last paragraph is probably the important  
part:

>  In short, the next 2-3 weeks (at least) are likely to be more  
> active across California than any other 2-3 week period in recent  
> memory. The potential exists for a dangerous flood scenario to arise  
> at some point during this interval, especially with the possibility  
> of a heavy rain-on-snow event during late week 2. In some parts of  
> Southern California, a whole season's worth of rain could fall over  
> the course of 5-10 days. This is likely to be a rather memorable  
> event. Stay tuned.


I was trying to figure out how to post this.  I received it through a  
Govt mailing list that I'm not allowed to forward.  I was going to see  
if I could figure out how to get the information via a different  
source that I could post without violating any previous legal  
obligations.

BillB



On Jan 16, 2010, at 10:32 AM, <ned at pacificcrestcustombuilders.com> <ned at pacificcrestcustombuilders.com 
 > wrote:

> I received this just this morning from the Search and Rescue Unit I  
> work with here in South Lake Tahoe. As with any mountainous weather  
> expectation, we'll see what we get, however, the next 2-3 weeks  
> ought to be interesting.
>
> Everyone, be careful out there!
>
> Ned Tibbits
> Mountain Education
> South Lake Tahoe, Ca
>
> ----- Original Message -----
> From: Greg Felton
> To: dcsar at yahoogroups.com
> Sent: Friday, January 15, 2010 8:22 PM
> Subject: [DCSAR] Interesting and ominous weather predication
>
>
>
>
> This forecast is focused on CA but much of it clearly applies to us.  
> Make sure you have gas for your generators and snow blowers. Make  
> sure your pack is ready. It wouldn't hurt to check your food and  
> water supplies as well, and put some firewood inside should you need  
> it for heating. This could be quite a January.
>
>
>
>
> ------------------------------------------------------------------------------
>
>
>
>  Currently, the strong El Nino is reaching its peak in the Eastern  
> Pacific, and now finally appears to be exerting an influence on our  
> weather. The strong jet has been apparent for quite some time out  
> over the open water, but the persistent block had prevented it from  
> reaching the coast. Now that the block has dissolved completely, a  
> 200+ kt jet is barreling towards us. Multiple large and powerful  
> storm systems are expected to slam into CA from the west and  
> northwest over the coming two weeks, all riding this extremely  
> powerful jet stream directly into the state. The jet will itself  
> provide tremendous dynamic lift, in addition to directing numerous  
> disturbances right at the state and supplying them with an ample  
> oceanic moisture source. The jet will be at quite a low latitude  
> over much of the Pacific, so these storms will be quite cold, at  
> least initially. Very heavy rainfall and strong to potentially very  
> strong winds will impact the lower elevations beginning late Sunday a
> nd continuing through at least the following Sunday. This will be  
> the case for the entire state, from (and south of) the Mexican  
> border all the way up to Oregon. Above 3000-4000 feet, precipitation  
> will be all snow, and since temperatures will be unusually cold for  
> a precipitation event of this magnitude, a truly prodigious amount  
> of snowfall is likely to occur in the mountains, possibly measured  
> in the tens of feet in the Sierra after it's all said and done. But  
> there's a big and rather threatening caveat to that (discussed  
> below).Individual storm events are going to be hard to time for at  
> least few more days, since this jet is just about as powerful as  
> they come (on this planet, anyway). Between this Sunday and the  
> following Sunday, I expect categorical statewide rainfall totals in  
> excess of 3-4 inches. That is likely to be a huge underestimate for  
> most areas. Much of NorCal is likely to see 5-10 inches in the  
> lowlands, with 10-20 inches in orographically-favored areas. Mo
> st of SoCal will see 3-6 inches at lower elevations, with perhaps  
> triple that amount in favored areas.
>
>  This is where things get even more interesting, though. The models  
> are virtually unanimous in "reloading" the powerful jet stream and  
> forming an additional persistent kink 2000-3000 miles to our  
> southwest after next Sunday. This is a truly ominous pattern,  
> because it implies the potential for a strong Pineapple-type  
> connection to develop. Indeed, the 12z GFS now shows copious warm  
> rains falling between days 12 and 16 across the entire state.  
> Normally, such as scenario out beyond day seven would be dubious at  
> best. Since the models are in such truly remarkable agreement,  
> however, and because of the extremely high potential impact of such  
> an event, it's worth mentioning now. Since there will be a massive  
> volume of freshly-fallen snow (even at relatively low elevations  
> between 3000-5000 feet), even a moderately warm storm event would  
> cause very serious flooding. This situation will have to monitored  
> closely. Even if the tropical connection does not develop, expected  
> rains in t
> he coming 7-10 days will likely be sufficient to cause flooding in  
> and of themselves (even in spite of dry antecedent conditions).
>
>
>
>
>
>  In addition to very heavy precipitation, powerful winds may result  
> from very steep pressure gradients associated with the large and  
> deep low pressure centers expect ed to begin approaching the coast  
> by early next week. Though it's not clear at the moment just how  
> powerful these winds may be, there is certainly the potential for a  
> widespread damaging wind event at some point, and the high Sierra  
> peaks are likely to see gusts in the 100-200 mph range (since the  
> 200kt jet at 200-300 mb will essentially run directly into the  
> mountains at some point). The details of this will have to be hashed  
> out as the event(s) draw closer.
>
>  In short, the next 2-3 weeks (at least) are likely to be more  
> active across California than any other 2-3 week period in recent  
> memory. The potential exists for a dangerous flood scenario to arise  
> at some point during this interval, especially with the possibility  
> of a heavy rain-on-snow event during late week 2. In some parts of  
> Southern California, a whole season's worth of rain could fall over  
> the course of 5-10 days. This is likely to be a rather memorable  
> event. Stay tuned.
>
>
>
>
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