The big west coasts event

[uofmiami]

Looks like good Jeb Walking weather up there in Mt Shasta

[Sn0waddict]

Webcam at mount shasta

http://skipark.com/the-mountain/cams

Can't wait to see what it looks like in a few days.

[Dan76]

They need a cam on top

[Stebo]

Max snowfall on this event? 120"? 150"?

Go big or go home, I say 180" for Mount Shasta.

[Quakertown needs snow]

the dream

[aslkahuna]

Actually, the winters of 1952-53,53-54,54-55 in CA were dry in most if not all of CA as we were in another one of the periodic drought cycles that afflicts the Western US. Ecept for the 51-52,55-56,and 57-58 winters the entire decade of the 1950's was dry in CA. We can also get these tropical plumes of moisture in AZ though from a source off Central America rather than near HI. Typically they start up here and become massive by the time they hit TX. Classic case being November 1994 when a plume event dumped 3-8 inches of rain in Cochise County in 24 hours-fortunately we had been dry during the year so flooding was minimal. In 1955 the Sacramento came withing 1 foot of the levee top in the city of Sacramento and the Yolo Bypass was full to capacity. A levee break along the Feather River near Yuba City before it reached the Sacramento thus saving the larger city. Both the Russian and San Lorenzo Rivers (the latter through Santa Cruz) crested above 40 feet. The south SFO Bay Area was shambles with all major highways between SJC and SFO closed by flooding two days before Xmas. San Jose was split in two by flood waters from the Guadalupe River and Los Gatos Creek. In 1955, CA took the wind flow axis and the heaviest dump while the 1964 event was more into OR and about the same time of year.

Steve

[usedtobe]

Actually, the winters of 1952-53,53-54,54-55 in CA were dry in most if not all of CA as we were in another one of the periodic drought cycles that afflicts the Western US. Ecept for the 51-52,55-56,and 57-58 winters the entire decade of the 1950's was dry in CA. We can also get these tropical plumes of moisture in AZ though from a source off Central America rather than near HI. Typically they start up here and become massive by the time they hit TX. Classic case being November 1994 when a plume event dumped 3-8 inches of rain in Cochise County in 24 hours-fortunately we had been dry during the year so flooding was minimal. In 1955 the Sacramento came withing 1 foot of the levee top in the city of Sacramento and the Yolo Bypass was full to capacity. A levee break along the Feather River near Yuba City before it reached the Sacramento thus saving the larger city. Both the Russian and San Lorenzo Rivers (the latter through Santa Cruz) crested above 40 feet. The south SFO Bay Area was shambles with all major highways between SJC and SFO closed by flooding two days before Xmas. San Jose was split in two by flood waters from the Guadalupe River and Los Gatos Creek. In 1955, CA took the wind flow axis and the heaviest dump while the 1964 event was more into OR and about the same time of year.

Steve

Steve, I didn't realize 1955 was also a dry period. It will be interesting to see how this one shapes up and whether it produces the same types of rainfall and flooding. I doubt it but it still looks impressive.

[aslkahuna]

Steve, I didn't realize 1955 was also a dry period. It will be interesting to see how this one shapes up and whether it produces the same types of rainfall and flooding. I doubt it but it still looks impressive.

The 1955-56 winter was wet,very wet but the decade of the 1950's as a whole were dry, very dry. BTW for those interested in Sierra snowfall

aside from Shasta's 189 in in a single storm, there's a 67 inch 24 hour snowfall at Echo Summit (US Highway 50) in January 1982..

Steve

[Amped]

130mph winds. The last one broke the Lake Tahoe Nexrad a few years back.

This may have trouble verifying.

[aslkahuna]

If this system verifies that would certainly make it difficult for that outlook to do so since intense Pineapple events can unload a significant percentage if not all of the average ANNUAL rainfall in parts of CA. Thus was the case for many locales in Northern and Central CA in 1955. Want to imagine the unimagineable- tryi having an 1861-62 event in CA today-the damage would make Sandy look like child's play.

Steve

[usedtobe]

Precipitation during the last 24 hrs. Several 7 inch plus reports. Honeydew, Venado and somewhere near Shasta.

So far a run of the mill big event.

[Eskimo Joe]

I wonder what economic impacts this will have on the California produce and vineyards, as well as the Oregon hops for beer brewing.

[usedtobe]

I wonder what economic impacts this will have on the California produce and vineyards, as well as the Oregon hops for beer brewing.

I think the grapes are already harvested. Not sure about other produce. The 5 day forecast indicates this event is far from over.

[das]

I think the grapes are already harvested. Not sure about other produce. The 5 day forecast indicates this event is far from over.

As do the 7 day estimates. HPC's new experimental 7-day QPF based on the HMT Rapid Refresh (WRF-based) AR model (Link to paper, compliments of AMS http://journals.amet...MS-D-11-00103.1):

HydroMet Testbed has a good writeup for the event going as well as some good Atmospheric River event experimental tools and discussion:

http://hmt.noaa.gov/...012/112712.html

Here's an AR primer from ESRL if anyone is interested:

http://www.esrl.noaa.../psd/atmrivers/

Looking at all this reminds me of my days back in Fresno long ago...

[uncle W]

December 1955 was the driest on record for NYC and one of the coldest...

[usedtobe]

December 1955 was the driest on record for NYC and one of the coldest...

One thing to say about analogs for heavy precipitation is the farther you get away from the area, the less the analog holds. Right now, the pattern looks anything but cold for NYC but it does look really wet for CA.

[uncle W]

One thing to say about analogs for heavy precipitation is the farther you get away from the area, the less the analog holds. Right now, the pattern looks anything but cold for NYC but it does look really wet for CA.

It will warm up in the east but for how long?...The AO is at it's lowest point this fall...It's under -3.000 again...Sooner or later cold air will return to the east coast...

[usedtobe]

3 out of the 5 top CIPPS analogs based on the 48hr NAM are top 20 events since 1950. The closest analog is dec 2002 which was 4th on the list of the twenty top SFO, SAC events based on the unified precipitation data. that may be misleading as the later years had more and better data than back in the 50s. You can look at the precip with the 2002 analog here

http://www.hpc.ncep.noaa.gov/research/California_major_rains_files/Page426.htm

Another CIPPS high ranking analogs was Jan 1995 which ranked 9th on the heaviest event list. IN that storm 42 counties were declared disaster areas. Particularly hard hit was the Napa and Russian Rivers. YOu can see the precipitation with that event here

http://www.hpc.ncep.noaa.gov/research/California_major_rains_files/Page528.htm

The other big event identified by teh CIPPS analogs was the New Years eve/New Years event of 1996-1997. Marty Roos, the big expert of CA flooding has said he thinks the flooding may have rivaled that of legendary flood of 1862. For his graphs and precipitation from the storm, click on the link below. Having worked the January and March 1995 floods, this one event was bigger than either of them.

http://www.hpc.ncep.noaa.gov/research/California_major_rains_files/Page563.htm

I hope someone finds the analogs interesting.

[icebreaker5221]

3 out of the 5 top CIPPS analogs based on the 48hr NAM are top 20 events since 1950. The closest analog is dec 2002 which was 4th on the list of the twenty top SFO, SAC events based on the unified precipitation data. that may be misleading as the later years had more and better data than back in the 50s. You can look at the precip with the 2002 analog here

http://www.hpc.ncep....les/Page426.htm

Another CIPPS high ranking analogs was Jan 1995 which ranked 9th on the heaviest event list. IN that storm 42 counties were declared disaster areas. Particularly hard hit was the Napa and Russian Rivers. YOu can see the precipitation with that event here

http://www.hpc.ncep....les/Page528.htm

The other big event identified by teh CIPPS analogs was the New Years eve/New Years event of 1996-1997. Marty Roos, the big expert of CA flooding has said he thinks the flooding may have rivaled that of legendary flood of 1862. For his graphs and precipitation from the storm, click on the link below. Having worked the January and March 1995 floods, this one event was bigger than either of them.

http://www.hpc.ncep....les/Page563.htm

I hope someone finds the analogs interesting.

Good information Wes! It seems to me that the present event has a particularly interesting evolution in regards to the atmospheric river. And here I use the term atmospheric river to delineate from Pineapple Express. IMO, the trough to the north just isn't quite deep enough / the anticyclone to the south is a bit too strong on the west side for this to be a typical Pineapple Express (originating near HI) with a persistent WSW moisture transport, e.g.:

However, in this case a tropical connection well west of Hawaii has more than compensated. A couple days ago, deep tropical moisture was originally feeding into a system fairly stationary at 40N, 180E. Once this system became occluded, moist southerly flow became deflected to the east ahead of the triple point and trapped along a convergence zone south of the polar low in the Gulf of Alaska and north of a persistent E Pac tropical anticyclone. The net effect is a highly-focused moisture plum trapped between two well-defined subsidence regions with the moisture source originating all the way from the W Pac:

Same net effect, but perhaps somewhat anomalous amongst events that are already infrequent to begin with!

[usedtobe]

Good information Wes! It seems to me that the present event has a particularly interesting evolution in regards to the atmospheric river. And here I use the term atmospheric river to delineate from Pineapple Express. IMO, the trough to the north just isn't quite deep enough / the anticyclone to the south is a bit too strong on the west side for this to be a typical Pineapple Express (originating near HI) with a persistent WSW moisture transport, e.g.:

However, in this case a tropical connection well west of Hawaii has more than compensated. A couple days ago, deep tropical moisture was originally feeding into a system fairly stationary at 40N, 180E. Once this system became occluded, moist southerly flow became deflected to the east ahead of the triple point and trapped along a convergence zone south of the polar low in the Gulf of Alaska and north of a persistent E Pac tropical anticyclone. The net effect is a highly-focused moisture plum trapped between two well-defined subsidence regions with the moisture source originating all the way from the W Pac:

Same net effect, but perhaps somewhat anomalous amongst events that are already infrequent to begin with!

I think it is and isn't anomalous with respect to other such events. Yes the PW plume, atmospheric river came from farther west than many but the analogs based on the forecast mean 500 anomaly pretty much said something big was likely to happen around 2 weeks ago so there were more similarities than differences. Still a really interesting event.

[icebreaker5221]

I think it is and isn't anomalous with respect to other such events. Yes the PW plume, atmospheric river came from farther west than many but the analogs based on the forecast mean 500 anomaly pretty much said something big was likely to happen around 2 weeks ago so there were more similarities than differences. Still a really interesting event.

Agreed. When you look at the big picture at 500 the overall setup matches up well with previous significant events.

[thewxmann]

THE NATIONAL WEATHER SERVICE IN RENO HAS ISSUED A

* FLOOD WARNING FOR

THE TRUCKEE RIVER NEAR TRUCKEE.

* FROM LATE SATURDAY NIGHT TO MONDAY MORNING...OR UNTIL THE WARNING

IS CANCELLED.

* AT 8:30 AM FRIDAY THE STAGE WAS 2.8 FEET.

* FLOOD STAGE IS 4.5 FEET.

* MAJOR FLOODING IS FORECAST.

* FORECAST...RISE ABOVE FLOOD STAGE BY EARLY SUNDAY MORNING AND

CONTINUE TO RISE TO NEAR 8.2 FEET BY LATE SUNDAY MORNING. THE RIVER

WILL FALL BELOW FLOOD STAGE BY SUNDAY EVENING.

* IMPACT...AT 8.0 FEET...MAJOR FLOOD DAMAGE TO HOMES...ROADS AND

BRIDGES ALONG TRUCKEE RIVER BETWEEN SQUAW CREEK AND TRUCKEE. LIKE

FLOOD OF DECEMBER 23 1955...ABOUT 7800 CFS.

[Derecho!]

This article on Atmospheric Rivers was to be published in the January Scientific American but they have put it online early because of the current storm:

http://www.scientificamerican.com/article.cfm?id=megastorms-could-down-massive-portions-of-california

[usedtobe]

THE NATIONAL WEATHER SERVICE IN RENO HAS ISSUED A

* FLOOD WARNING FOR

THE TRUCKEE RIVER NEAR TRUCKEE.

* FROM LATE SATURDAY NIGHT TO MONDAY MORNING...OR UNTIL THE WARNING

IS CANCELLED.

* AT 8:30 AM FRIDAY THE STAGE WAS 2.8 FEET.

* FLOOD STAGE IS 4.5 FEET.

* MAJOR FLOODING IS FORECAST.

* FORECAST...RISE ABOVE FLOOD STAGE BY EARLY SUNDAY MORNING AND

CONTINUE TO RISE TO NEAR 8.2 FEET BY LATE SUNDAY MORNING. THE RIVER

WILL FALL BELOW FLOOD STAGE BY SUNDAY EVENING.

* IMPACT...AT 8.0 FEET...MAJOR FLOOD DAMAGE TO HOMES...ROADS AND

BRIDGES ALONG TRUCKEE RIVER BETWEEN SQUAW CREEK AND TRUCKEE. LIKE

FLOOD OF DECEMBER 23 1955...ABOUT 7800 CFS.

Wow, comparing it to the original analog, pretty cool.

[usedtobe]

Looks like a respite during the day today before another big onslaught tonight and tomorrow.

[aslkahuna]

Some of the flooding in 1997 might have locally rivaled stages and flows from 1861-62 but the earlier flood flood was one that played out over a period of three months so the sheer volume of water was orders of magnitude greater than 1997. My Father experience both 1955 and 1997 and he felt that the two were close to each other but that 1955 was a bit worse overall. Certainly 24 hour and storm total rainfall amounts were very similar.

Steve

[BlizzardWx]

Some of the flooding in 1997 might have locally rivaled stages and flows from 1861-62 but the earlier flood flood was one that played out over a period of three months so the sheer volume of water was orders of magnitude greater than 1997. My Father experience both 1955 and 1997 and he felt that the two were close to each other but that 1955 was a bit worse overall. Certainly 24 hour and storm total rainfall amounts were very similar.

Steve

What was the main synoptic differences between these two? Also, can you tell me a little about why 1861-1862 event was so bad? Thanks

[usedtobe]

Some of the flooding in 1997 might have locally rivaled stages and flows from 1861-62 but the earlier flood flood was one that played out over a period of three months so the sheer volume of water was orders of magnitude greater than 1997. My Father experience both 1955 and 1997 and he felt that the two were close to each other but that 1955 was a bit worse overall. Certainly 24 hour and storm total rainfall amounts were very similar.

Steve

Steve, I got the quote about possibly rivaling the 1861-1862 flood from this publication. The three rivers discussed were the Feather, American and Consommes (sp?) so he may have only been referring to them.

http://www.water.ca.gov/climatechange/docs/Roos-flooding.pdf

Wes

[Kevin Druff]

This article on Atmospheric Rivers was to be published in the January Scientific American but they have put it online early because of the current storm:

http://www.scientifi...s-of-california

What was the main synoptic differences between these two? Also, can you tell me a little about why 1861-1862 event was so bad? Thanks

Blizzard -- I strongly encourage a read of the SciAm article linked above.

[Amped]

What was the main synoptic differences between these two? Also, can you tell me a little about why 1861-1862 event was so bad? Thanks

I'm not steve and we don't have 1861 charts.

So I'll guess. 1861 had blocking which kept the trough over the west coast for almost an entire month, yeilding a pinapple express marathon. This time the trough near the west coast seems progressive a few more days and it's gone.