Have You Ever Heard Of California's ARKStorm During The Winter Of 1861 - 1862?
Valid @ 5 AM MST This Morning.
GFS 500 MB Analysis.
Valid @ 5 AM MST This Morning.
More Heavy Rain & Snow For California!
(Valid Today Into Monday @ 5 PM MST).
(Valid Today Into Monday @ 5 PM MST).
California seemingly cannot catch a break as yet two more "Atmospheric River Storms" plow into the state today into the first of next week. Total rainfall amounts in some of the lower elevations of the Sierra Nevada Mountains could end up in the 7" - 10" range by Tuesday. Given this winter's pattern of having been very wet one has to wonder if another ARKStorm isn't brewing on their horizon.
An interesting story was published yesterday by:
WUWT-What's Up With That?
California's Past Megafloods And The Coming ArkStorm...Guest Post By Larry Kummer. Posted At The Fabius Maximus Website.
California's Past Megafloods And The Coming ArkStorm...Guest Post By Larry Kummer. Posted At The Fabius Maximus Website.
“Beginning on Christmas Eve, 1861, and continuing into early 1862, an extreme series of storms lasting 45 days struck California. The storms caused severe flooding, turning the Sacramento Valley into an inland sea, forcing the State Capital to be moved from Sacramento to San Francisco for a time, and requiring Governor Leland Stanford to take a rowboat to his inauguration. William Brewer, author of Up and Down California in 1860-1864
, wrote on January 19, 1862, ‘The great central valley of the state is under water — the Sacramento and San Joaquin valleys — a region 250 to 300 miles long and an average of at least twenty miles wide, or probably three to three and a half millions of acres!’
, wrote on January 19, 1862, ‘The great central valley of the state is under water — the Sacramento and San Joaquin valleys — a region 250 to 300 miles long and an average of at least twenty miles wide, or probably three to three and a half millions of acres!’
‘In southern California lakes were formed in the Mojave Desert and the Los Angeles Basin. The Santa Ana River tripled its highest-ever estimated discharge, cutting arroyos into the southern California landscape and obliterating the ironically named Agua Mansa (Smooth Water), then the largest community between New Mexico and Los Angeles. The storms wiped out nearly a third of the taxable land in California, leaving the State bankrupt.
“The 1861-62 series of storms were probably the largest and longest California storms on record. However, geological evidence suggests that earlier, prehistoric floods were likely even bigger. There is no scientific evidence to suggest that such extreme storms could not happen again. However, despite the historical and prehistorical evidence for extreme winter storms on the West Coast, the potential for these extreme events has not attracted public concern, as have hurricanes. The storms of 1861-62 happened long before living memory, and the hazards associated with such extreme winter storms have not tested modern infrastructure nor the preparedness of the emergency management community.”
.DISCUSSION...as of 09:00 AM PST Saturday... The storm system which rapidly strengthened off of our coast yesterday morning has shifted eastward into the intermountain west. Only some diminishing rain showers and breezy winds are persisting primarily over Monterey and San Benito counties in the wake of the last system. This system was the first in yet another series of systems forecast to impact the forecast area. All eyes are now on the next storm system anticipated bring another round of heavy rain and strong winds between late Sunday afternoon into Monday. Lingering showers will then persist Monday before another, yet weaker, system arrives Tuesday into Wednesday. Thursday into possibly Friday looks dry. Model confidence drops off moving into next weekend, however, most model solutions look unsettled, with one system arriving Saturday, and another early next week. For the next system, the most important factor at play is the positioning of the precipitable water plume as it will determine which areas will see the heaviest rainfall as well as the amount of orographic enhancement/rain shadowing possible. Short term models are not currently in agreement with this exact positioning, despite the storm only begin about 36 hours out, thus lowering model confidence of specific positioning and rainfall amounts at this point. That said, on average, models appear to aim the bulk of initial moisture towards Big Sur, before shifting the plume northward towards the Santa Cruz mountains, then towards the North Bay, before shifting southwards once again over the Santa Cruz mountains. Given this trajectory, it seems plausible that the highest rainfall amounts will be over the Santa Cruz mountains through the duration of the event. Rainfall amounts will be highest over the coastal ranges, with 3-6 inches possible over elevated terrain, locally higher over the largest orographically favored peaks. Most valley locations can expect 1-2.5 inches, with locally higher amounts to around 3.5 inches in the North Bay valleys. Gusty southerly winds will accompany this storm as well, however, speeds will not be nearly as strong as with the last system. Pinpointing the rainfall timing and amounts of tomorrow`s system will be the forecast focus of the day. An areal flood watch for the entire forecast area will be issued shortly in anticipation of this system. This storm system is anticipated to further exacerbate deteriorating conditions in and around our area`s infrastructure. Given our already saturated soils, the upcoming rainfall will predominately runoff into streams and river or pool in low lying areas, leading to increased likelihood of urban and small stream flooding. Additionally, increased risk of mud/rock slides are anticipated, especially over steep terrain, which can result in roads being damaged or destroyed, as we have seen already many times this year. Furthermore, downed trees and power outages can be expected as well. Be sure to plan ahead if travel is necessary and check the latest road conditions available from CalTrans websites. Turn around, don`t drown, flooded areas can be deceptively deep. See previous discussion for specifics relating to the current forecast package. Next forecast package will be issued early this afternoon. .PREVIOUS DISCUSSION...as of 03:02 AM PST Saturday...Scattered showers continue to move across the region this morning as the main mid/upper level trough axis shifts inland. Rainfall amounts have been spotty with generally a few hundredths of an inch per hour with locally higher amounts near 0.25"/hr within heavier showers. Expecting showers to diminish in coverage through mid morning with periods of dry weather conditions forecast across the region this afternoon and evening. This "dry slot" can be seen on satellite imagery in wake of the trough aloft and our next system developing out over the Pacific. While most areas will remain dry through tonight, cannot rule out light precipitation across portions of the region. Light rain will increase in coverage early Sunday morning, first across the North Bay and along the coastal ranges deeper moisture offshore advects inland. The forecast models then show a deeper atmospheric river(AR) with PWAT values in excess of 1.25" reaching the Central Coast by Sunday afternoon. At first, widespread rain is forecast to develop across much of the region with the heaviest occuring across the coastal ranges. The AR and associated band of precipitation is then forecast to narrow and potentially work northward resulting in moderate to heavy rainfall as it points toward the central California coast. As typical with any AR event, the main forecast challenge remains exactly where the heaviest band of precipitation will develop as well as the movement or stalling of said boundary. At this time, it appears the main focus will be somewhere between the Santa Cruz Mountains northward into the North Bay from late Sunday afternoon into Monday morning before the system eventually shifts southward and inland in response to an approaching mid/upper level system. Given the fact that the entire region has been battered by system after system so far this winter and soils remain super saturated, widespread flooding will be likely from Sunday into Monday! Not only is widespread moderate to locally heavy rainfall likely, southerly winds will again increase out head of this system and will yet again result in downed trees, power outages and further deterioration of the region`s infrastructure. Flooding of area creeks, streams, low lying areas as well as rises on the main stem rivers will also be likely. While it remains difficult to forecast exact rainfall amounts, there is the potential for widespread 2.50" to 3.50" across the North Bay and 1.00" to 3.00" amounts in other urban areas across the region. Inland valley locations, especially across the Salinas and Santa Clary Valleys will likely see lesser amounts depending on where the AR takes aim. Meanwhile, the North Bay Mountains and coastal ranges southward will likely see rainfall totals of 3.00" to 6.00" with the potential for some areas to pick up as much as 10.00" from Sunday afternoon into Monday. Folks living in flood prone areas are urged to remain vigilant of the latest forecast and should take necessary measures to protect life and property in advance of this upcoming storm system. Lingering showers are then likely from Monday night into Tuesday in wake of the heavier precipitation forecast to shift inland/southward. The forecast models have backed off on the strength of the subsequent system expected to sweep through Tuesday night into Wednesday as a mid/upper level system traverses the region. However, do expect another round of at least light precipitation to move across as the main upper level trough pushes inland. By Wednesday night and especially Thursday, dry weather conditions are forecast to return to the region as high pressure develops in wake of the exiting trough. Temperatures late next week are forecast to be generally below seasonal averages as a cooler air mass settles in over the region. It is worth noting that the GFS shows a cool, weak system dropping in across the region by next weekend while the ECMWF maintains dry weather conditions. At this time, will keep a generally dry forecast from late next week into the following weekend as trends favor drier conditions.
The Truth Is Stranger Than Fiction!
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