An Atmospheric River Event produced extremely heavy rainfall into portions of NORCAL over the weekend, with rapidly diminishing amts over CENCAL. The storm has moved eastward, with clearing skies over CA. CENCAL experienced its first widespread Fog Event of the Season Tuesday morning, that latest start of the Fog Season in the SJV history. It’s almost time for it to be nearing an end…! So the unusual winter season continues to produce uncharacteristic behavior. Lighter winds should allow for increasing amts of Dense Fog nights and mornings throughout a widespread region of CENCAL during the next several days as a stable atmosphere favors fog formation as soon as the temps reach dewpoints. Afternoon and early morning temps will be a direct reflection of the amt and duration of the fog deck which could grow quite thick in some spots, with widely varied spreads in regional temps caused by the uneven dispersion of the stratus deck before noon. In areas which clear out favorably in the morning the afternoon temps should climb into the 70°’s. Uncertainty surrounds the local impact of a frontal system reaching into CA over the weekend, but the latest GFS charts are trending to dry out the storm. While another prolonged Atmospheric River event will unfold for the far NORCAL coastline with impressively high QPF’s suggesting up to 14 to 17 inches of precip in the next 5-7Days, the CENCAL region is shown to remain mostly dry, except for some possible showers into the Sierra near YNP. The Long Range Charts do not offer relief to the dry conditions over CEN/SOCAL for the next 16Days ending on Thursday, Feb 27th. High Res Visible Color Satellite Image at bottom of report showing close-up of the Southern Sierra Snowpack ↓
Special Notations;
The ‘biggest storm event since Dec 2012’ spread heavy rainfall into most of NORCAL during the weekend with impressive 96hr storm totals. The AR is not quite done as it will continue to flow into CA about 200-250 miles further north than it did over the weekend, bringing the far NW coastal region impressive QPF estimates that range up to 14-17 inches. If this AR event does verify in the next 5Days for the Redwood Country it could potentially produce some hydro issues along the far NW Coastal region, with the Eel, Mad, Mattole, Klamath, and Smith River basins which have already been primed by the past weekend storm, so runoff would be much quicker and greater this next time around, with the RFC suggesting that all mainstem rivers in NORCAL remain below monitor levels thru Saturday. Meanwhile the rest of CA dries out with no significant storm of consequence seen by the GFS for the next 16Days for CEN/SOCAL. This is unfortunate news since the water situation over most of CENCAL did not benefit from being south of the sharp rain/no rain line produced by the Atmospheric River which remained mostly focused primarily upon the North Bay region and into the Northern Sierra. While the Northern Sierra 8-Station Index marked an increase in the monthly February total reaching 7.3 inches, 92% of average for February, by contrast the San Joaquin 5-Station Index only bumped the February monthly total by half that amt to 3.80 inches, 55% of the average for February. Please review the current status of the 8-Station Northern Sierra Index and the San Joaquin 5-Station Index in the charts illustrated above ↑. The Tulare Lake Index watersheds received about ½ of what the San Joaquin Index received over the weekend, with the Kern River basin barely settling the dust with a few hundredths of an inch. An interesting aspect of this unusual Water Year behavior for the Southern Sierra, is depicted by the following example; the 1.17 inches of precip received at Lake Kaweah over the past 12Days is offset by the deficit created by high daily evaporation rates which has been 2.74 inches worth of water since January 15th, leaving a -1.57 deficit after subtracting the recent rainfall from the evaporation which has occurred since Jan 15th. If we tally the numbers since Dec 1, the evaporation which has occurred is 6.40 inches worth of water versus the 1.48 inches of rainfall, creating a net deficit of nearly -5 inches! This upside down water profile is reflected in the lower foothill regions of much of the Southern Sierra, but especially from the Kings River basin southward where warm afternoons and sunny skies have yanked a lot of water out of the soils and forests. The prospect for a respite from this is unlikely, given the 384hr GFS 16Day Outlook and with mid 70°’s most of this week. While Mother Nature recently gifted the Shasta, Feather, Yuba and American River basins with an impressive drenching, the rest of the region is still suffering greatly, with no end in sight. The Drought is not over by any stretch of the imagination even in the regions which had the heaviest rainfall over the weekend, but at least a couple of important river basins did benefit, and the extremely dangerous dry forest conditions have been relaxed.
The 96 hour, 4Day Atmospheric River Storm Event for NORCAL provided some impressive storm totals which spread into portions of CENCAL;
23.51 Middle Pk, Mt Tamalpais, 17.24 Four Trees, 15.68 Huysink, 15.48 Forbestown, 15.22 Felton, 15.02 Occidental, 14.68 Strawberry Valley, 14.31 Brush Crk, 14.08 Deer Crk Forebay, 13.87 Bald Mtn, 12.84 Seedorchard, 12.68 Georgetown, 12.43 Jarbo Gap, 12.38 White Cloud, 12.35 Guerneville, 12.31 Paradise, 12.18 Mill Valley, 12.08 St Helena, 12.03 Bowman Lake, 11.77 Drum Powerhouse, 11.72 Camptonville, 11.59 Blue Cyn, 11.56 Bucks Lake, 11.49 Cazadero, 11.00 Squaw Valley, 10.95 Secret Town, 10.73 DeSabla, 10.30 Ben Lomond, 10.27 Grass Valley, 10.04 Angwin, 10.01 Tiger Creek Pwrhse, 9.77 El Dorado Hills, 9.60 Echo Summit, 9.52 Black Springs, 9.48 Alleghany, 9.32 Black Springs, 9.20 Forni Ridge and Venado, the CSS Lab and Bucks Crk Pwrhse, 9.17 Sierra City, 8.96 Whispering Pines, 8.76 Calavaras Ranger Stn, 8.59 Donner Lake, 8.20 Auburn Dam and Hillcrest, 8.15 Napa Corp Yard, 7.99 Mt Zion, 7.92 Snow Mt and Santa Rosa, 7.51 Stanislaus Mdw, 7.39 Laytonville, 7.38 Potter Valley, 7.36 Shingletown, 7.28 Eel River South Fork, 7.24 Healdsburg, 7.10 Blue Lakes, 6.63 Fairfield, 6.58 Consumnes River NF, 6.48 Willits, 6.28 Oroville Dam, 6.13 Placerville, 6.12 Stouts Mdw, 6.08 Eel River Ranger Stn, 6.00 Ebbetts Pass, 5.88 Brandy Crk, 5.84 Hopland and Shasta Dam, 5.62 Oak Mt, 5.58 Scotts Valley, 5.40 Ukiah, 5.30 Carson Pass and Zenia, 5.19 Orangevale, 5.08 Ft Bragg, 5.07 Camp Six, 4.91 Quincy, 4.90 Heaven Valley, 4.85 Travis, 4.80 Petaluma, 4.60 Mendocino Pass, 4.49 Folsom Lake, 4.36 Lassen, 4.24 Redding FS, 4.08 Brush Mt and Lakeshore, 4.00 Slate Crk, 3.97 Eel River Camp, 3.91 McCloud Dam, Vacaville and Beale AFB, 3.71 Oroville, 3.61 Markleeville, 3.47 Konocti, 3.40 Honeydew, 3.28 Gasquet, 3.20 Soquel, 3.15 Marysville, 3.00 Oakland Dwntwn, Adin Mtn, 2.92 Bridgeville, 2.91 Redding, 2.86 Elk Grove, 2.67 SF Dwntwn, 2.32 SAC Exec, 1.60 Crescent City, 1.59 Chico, 1.32 Mt Shasta, 1.24 Watsonville, 0.23 San Jose, 0.18 Moffett,
Local Rainfall; 7.44 Telegraph Hill, 7.32 Gianelli, 6.59 Mt Elizabeth, 5.30 Leavitt Lake, 5.00 Stanislaus Pwrhse, 3.64 Mammoth, 3.63 Hetch Hetchy, 3.10 Sonora Pass, 2.99 Devils Postpile, 2.90 YNP, 2.80 Kaiser Pt, 2.64 Graveyard and Minarets, 2.60 Chilkoot Mdw, 2.51 Tenaya Lake, 2.40 Nature Pt, 2.34 Wawona, 2.16 Fish Camp, 2.10 Case Mt, 2.08 Huntington Lake, 2.06 Gem Pass, 1.90 Ellery Lake, 1.87 Peppermint, 1.70 Wishon Dam, 1.67 Shaver Lake, 1.64 Bass Lake, 1.57 Dinkey Crk, 1.54 Hockett Mdw, 1.52 North Fork, 1.42 Cedar Grove, 1.37 Clovis, 1.33 Oak Opening, 1.17 Fence Mdw and Park Ridge, 1.15 Balch Camp, 1.13 Rogers Camp and Johnsondale, 1.12 Pine Flat Dam, 1.06 Madera, 1.04 Pacheco Pass, 1.03 Mariposa, 1.02 Pinehurst, 0.96 Trimmer, 0.93 Los Banos, 0.89 Hurley, 0.85 Fresno, 0.84 Friant and Stockton, 0.80 Pascoes, 0.78 Orange Cove, 0.76 Firebaugh, 0.75 Lake Kaweah, 0.72 San Luis NWR, 0.67 Hensley Lake, 0.63 Merced, 0.54 Modesto, 0.28 Lake Success and Tulare, 0.21 Kettleman City, 0.18 Porterville, 0.17 Wofford Heights, 0.13 Delano, 0.05 NAS Lemoore, 0.04 Isabella, 0.03 Buttonwillow, 0.02 Shafter, 0.01 BFL
CA Total Precipitation from Feb 3rd to 9th showing the landfall region of where the Atmospheric River moved into CA at Pt Reyes/Marin Co/Mt Tamalpais and then aimed into the Northern Sierra.
CA Regional Cities Precip Summary as of Mon, Feb 10th, with 96hr Storm Totals, showing a concentration of precip from Ukiah to San Francisco.
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Current Northern Sierra 8-Station Precip Index;
Northern Sierra 8-Station plot graph
Current San Joaquin 5-Station Precip Index;
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San Joaquin 5-Station Index plot graph
An amazing jump in Streamflow for the Russian River during the weekend storm event;
Russian River 7-Day flow plot, showing the flow near 80cfs on Feb 5th rising to nearly 20,000cfs at midnight on Feb 9th.
Feather River basin; Oroville Dam storage from Thu, Feb 8th to 4pm Mon, Feb 10th. Increasing by 71,000 AF, with a peak inflow of 28,075cfs, with a gain of 9 ft in reservoir height.
American River basin; Folsom Lake storage from Sat, Feb 8th to 4pm Mon, Feb 10th. Increasing by 79,588 AF, with a peak inflow yesterday of 29,865cfs, down to 16,776cfs today, with a gain of 20 ft in reservoir height.
However, further south in the Sierra, the impact of the storm was less noticeable;
Stanislaus River basin; New Melones storage from Thu, Feb 6th to 4pm Feb 10th. Increasing by 7,578 AF, with a peak inflow of 4,587 cfs, with a gain of 1 ft in reservoir height. This reservoir inflow profile is fairly representative of the rest of the Southern Sierra, which showed a small increase from the weekend storm series.
FORECAST SUMMARIES
Days 1-7;
Tue, Feb 11th The SJV experienced its first major Tule Fog episode of the winter season, as calm conditions and low level moisture condensed overnight. Feb 11th is the latest start to the Fog Season in the SJV history, due to the exceptional dryness of the atmosphere thus far during the prior months, which exemplifies how ridiculous this winter season has been! As the High Pressure covers CEN/SOCAL, a redeveloping Atmospheric River (AR) begins to advect warm heavy rains back into the PACNW and extreme NW CA. The longwave trough pattern over the NE PAC maintains the long fetched SW flow pattern carrying the AR into extreme NW CA for several days withimpressively high QPF’s estimated up to 14 to 17 inches over the next 5Days. Overnight the moist flow enhances with torrential warm rains north of Cape Mendocino, while skies over CENCAL are calm with variable amts of overcast skies and night and morning Dense Fog.
Wed, Feb 12th Dense Morning Fog; the long-fetched Atmospheric River (AR) stretches back to 20N at the Dateline, with continuing non-stop warm heavy rains flowing into southern Canada down to Fort Bragg. While High Pressure covers CEN/SOCAL with weak steering currents aloft, producing a continuation of conditions favorable for night and morning Dense Fog. Temps will be high dependent upon the thickness and duration of fog during the morning hours.
Thu, Feb 13th High Pressure west of SOCAL allows a SW flow pattern to bring the long-fetched Atmospheric River (AR) with mod/heavy rainfall into the far NW portion of NORCAL from Cape Mendocino northward with fair skies over CENCAL and more night and morning Fog. Overnight the precip shield over NORCAL shifts slightly north, closer to the OR border region.
Fri, Feb 14th Valentine’s Day shows High Pressure continues to cover CEN/SOCAL, providing a SW flow pattern to continue to advect the near steady-state Atmospheric River (AR) into the PACNW and the NW Coastal region of CA with extremely high QPF totals. The calm conditions keep the night and morning overcast/fog regime in place over the SJV, with warm afternoons…providing that the fog burns off. SJV Temps have the potential to reach into the mid to upper 70°’s if the fog does burn off as expected. Overnight the High Pressure noses into NORCAL which diverts the AR a bit further north into SW OR, and possibly Crescent City. Meanwhile a weak cold front and associated trough approach NORCAL and trails off to the SW with a severing tie to the Atmospheric River.
Sat, Feb 15th High Pressure over SOCAL shifts east into the Great Basin as the approaching trough and SW flow pattern reach into the PACNW and the NORCAL Coastal region. The tail-end of the AR is flowing into NORCAL, with partly cloudy skies extending SW offshore west of SFO. Overnight the remnant frontal boundary crosses thru NOR/CENCAL with some rainfall into the northern districts possible, and partly cloudy skies to the south to Kern Co. The strength of this storm system is highly uncertain in model comparisons, so of which show precip reaching into CENCAL, while others remain drier. While not a big rain producer for CENCAL, it should be monitored due to its uncertain future.
Sun, Feb 16th With the High Pressure axis over the Great Basin and troughing in the GOA, the stead-state moist SW flow pattern keeps warm/heavy rainfall into the PACNW, but not reaching into CA. Fair skies and more fog is possible over CENCAL due to calm conditions aloft.
Mon, Feb 17th More of the same…with a warm/moist SW flow barreling into the PACNW with heavy rains, while CA remains fair/mild. Overnight the GOA trough axis approaches the NORCAL Coastal region as the warm/heavy rains return back into the NORCAL coastal region down to Ukiah.
Days 8-16, Long Range into Fantasyland Outlook; Day 8 begins;
Tue, Feb 18th shows the trough axis nearing the NORCAL coastline with the heavy rains spreading throughout NORCAL down to the I-80 corridor, while partly cloudy skies remain over CENCAL. Overnight the precip spreads as far south as YNP into the Sierra, as heavy rains continue over NORCAL. Once again depending upon model choice, some precip could reach into the northern SJV, so this storm event should also be monitored.
Wed, Feb 19th shows the trough axis moving thru CA with rainshowers over NORCAL and chances of showers into portions of CENCAL down to Modesto/Merced to YNP. SOCAL remains fair/dry.
Thu, Feb 20th shows the RRR High Pressure rebuilding at 140W as the trough settles into the Great Basin, providing CA with a drier NW flow pattern with cooler temps.
Fri, Feb 21st shows the RRR High Pressure ridge moves closer to the West Coast with a north flow pattern over NORCAL and NW flow pattern over CEN/SOCAL, with fair skies and cooler temps
Sat, Feb 22nd shows the broad but flat RRR High Pressure ridge moving onshore over the West Coast, with fair skies as the storm track is diverted into southern Canada, and the cool/dry NW flow pattern over CA continues.
Sun, Feb 23rd shows the RRR High Pressure ridge axis shifting to the west, which allows a trough pattern to develop into the NE PAC basin, with an onshore flow bringing additional rains into southern Canada, while CA remains fair/mild and dry.
Mon, Feb 24th shows the RRR High Pressure ridge axis at 150W, far enough west of CA to allow for a stronger NW flow pattern into CA with some moisture possibly reaching into the NE quadrant near Alturas. This pattern continues to keep temps over CENCAL moderate with fair skies.
Tue, Feb 25th shows the RRR High Pressure ridge axis moving to 145W with a trough digging into the Great Basin with increasing NW winds arriving into CA, with much cooler temps. Overnight the flow pattern may veer to the NNE with cold/dry air advecting into CA from the Great Basin…Overnight min’s may dip below 32° at the colder Ag Stations with frost.
Wed, Feb 26th shows the RRR High Pressure offshore and a possible Low Pressure circulation forming near Las Vegas, maintaining a strong N-NE flow pattern into CA from the interior of the PACNW, which continues to advect cold air into the region, with more frost possible into the SJV Ag Districts…if winds are calm.
Thu, Feb 27th shows the trough in the Great Basin shifting east as High Pressure noses into NORCAL and the pressure gradient over CA relaxes. With cold/dry NE flow pattern over all of CA, the region is prime for frosty conditions to continue in the SJV Ag Districts in the mornings, followed by warm/dry afternoons. The offshore NE flow over SOCAL produces Santa Ana conditions with brisk warm/dry winds and a high Fire Danger.
PRECIPITATION FORECAST
Day 1 – 5 QPF:
At 12Z (9am) Monday thru the period Friday night (Saturday @4am) shows;
Tue shows CA dry, except for the far NW Coastal region with up to 0.5 inch into Del Norte Co diminishing to 0.1 inch near Ft Bragg to Redding to Susanville
Wed shows CEN/SOCAL DRY, with NORCAL wet to very wet, showing up to 4-6 inches of precip into the wet spots of the Smith River basin, with up to 2 inches for portions of the Klamath River basin, with rapidly diminishing amts to the south and east, with up to 0.75 inch into the Shasta and Eel River basins, and up to 0.5 inch from the South Fork of the Eel River basin to Redding to Mt. Lassen, diminishing to 0.2 inch from near Ft Bragg to near Red Bluff, to the Lassen region, with >0.1 inch from as far as the Russian River basin NE to near Chico then SE into the American River basin.
Thu shows the same rainfall pattern as the previous day, with reduced amts showing up to 2 inches for Del Norte Co, 1 inch for most of Humboldt Co, with 0.5 inch for northern Mendocino Co up into the Shasta basin, and >0.2 inch from Clear Lake to Marysville, and into the Feather River basin and NE quadrant near Alturas and Susanville. ALL of CEN/SOCAL remain DRY!
Fri shows a 3rd consecutive day with a similar pattern showing DRY conditions over CEN/SOCAL and the a wet pattern over NW NORCAL but with slightly lower QPF amts, showing up to 2-3inches into the wet spots of the Smith River basin, up to 1 inch for most of the Klamath, Eel and Shasta River basins and up to 0.5 inch for northern Mendocino Co and up into the Shasta River basin, with >0.1 inch from near Clear Lake NE into the upper Pit River basin to Alturas.
Sat shows precip spreading southward into portions of CENCAL with light amts in the lowlands and up to 0.2 to 0.5 into the northern portions of the Southern Sierra from the San Joaquin River basin northward, with up to 0.5 inch north of Santa Rosa to near Redding and including all of the Northern Sierra, with up to 2 inches for the Feather, Eel, Klamath and Shasta River basins, with up to 3 inches into the wet spots of the Klamath and most of Del Norte Co.
5DAY ACCUMULATION CHART: showing up to 16+ inches of precip falling into the wet spots of Del Norte Co and the Smith River basin!
16-Day QPF estimates (from the 12Z GFS) for;
Days 1-7; shows NORCAL receiving up to 10-17 inches in the NW Coastal region rapidly diminishing to 2 inches from Ft Bragg to the Lassen region, diminishing to 0.5 inch for the Santa Rosa to SAC to south of the Tahoe region and 0.25 inch from Santa Cruz to Modesto to YNP northward, and >0.1 inch from the Central Coast NE into portions of the Southern Sierra. SOCAL remains DRY.
Comparison 7 Day QPF Charts from Monday and Tuesday showing portions of NORCAL being drenched while most of CENCAL and all of SOCAL remains DRY;
Monday’s 7 Day Chart; showing heavy rains continue into the NW portion of CA with diminishing amts to the south, with >0.1 inch suggested for most of CENCAL, and SOCAL remaining completely DRY.
Tuesday’s 7 Day Chart; shows increased precip for the NW Coastal region with up to 17 inches suggested into Del Norte Co with rapidly diminishing amts to the south, with the rain/no rain line running from near Santa Cruz to Modesto to YNP, with most of CEN/SOCAL remaining consistently DRY.
Days 8-16; shows light amts of precip up to 1 inch for the far NW coastal region, the Shasta basin and portions of the Feather basin, with diminishing amts to the south showing SAC with 0.5 inch, Madera, Fresno, Kings, Tulare, Kern Co with .0.1 inch and SOCAL remaining DRY.
Tuesday’s 12Z 9am GFS 384hr, 16Day QPF Chart, depicting a wet NORCAL, semi-wet CENCAL, and a dry SOCAL. With up to 10+ inches of heavy rainfall along the OR coastline, diminishing to 5+ inches for the far NW CA coastal region, diminishing to 4 inches from Cape Mendocino to the Shasta region, diminishing to 2 inches near Ukiah, to 1 inch in the north Bay region toward SAC and the Feather River basin with up to 0.5 inch from Santa Cruz to YNP, to 0.25 inch from San Simeon to Fresno to Kings Cyn, with >0.1 inch from Vandenberg to the Tehachapi’s and the Kern River basin. SOCAL remains DRY.
SATELLITE
Water Vapor 4KM Image of the West Coast Tuesday, February 11th, 2014, shows High Pressure regaining over CA, which is shunting the moist SW flow pattern into the PACNW with extreme NORCAL on the southern fringe zone of the activity receiving occasional cloudiness.
Visible Satellite Image of the CA Tuesday, February 11th, 2014, shows the first SJV big Tule Fog event with overcast skies filling portions of the valley region, with clear skies over the Sierra and high clouds flowing over NORCAL.
Special HD resolution color Visible Satellite Image of the Southern Sierra, with varying amts of new snowfall. The Tuolumne River basin in the north shows a deeper blanket of snowfall as compared to the South Fork of the San Joaquin, the southern rim of the Kings and from Mt Whitney southward in the Kern River basin. There is still a lot of gray granite showing in the Southern Sierra which should be covered in snow.
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Atmospherics Group International
Dan Gudgel Steve Johnson
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