HAPPY VALENTINE’S DAY!
A weak Atmospheric River Event continues to flow into the extreme NW coastal region of CA with abundant warm rains which occasionally spread into the Shasta and Feather River basins bringing some additional beneficial moisture to key reservoirs in the State Water project. We’re not so lucky further south into the Central or Southern Sierra unfortunately. Rainfall amts rapidly diminish over NORCAL. This pattern is to continue thru next Wednesday when the atmosphere will undergo a fundamental pattern change into a more amplified ridge/trough configuration. The longer range outlook remains dry for most of CA during Week #2 with colder temps. The GFS 384hr 16Day Outlook now extends thru the end of the month into March 1st. The final week of February should end the February monthly summary for the Northern Sierra Index…above normal for the first month this Water Year…and for the first time since Dec 2013, 14 long months ago! That’s the good news. Now the not so good news …it appears as though the month of February will end with a worsening Drought deficit for the Central Sierra and especially for the Southern Sierra within the Tulare Lake Index.
PRECIP past 24hrs over NORCAL; 1.40 Fort Dick, 1.32 Orick, 1.29 Orick and Somes Bar, 1.28 Elk Valley, 1.15 Crescent City, 1.06 Pit River Powerhouse #5, 0.94 Arcata, 0.92 Hoopa and Orleans, 0.88 Taylor Ridge, 0.84 Sawyers Bar, 0.82 Big Hill, 0.72 Bonanza King, Snow Mtn and Hirz, 0.64 Ruth Lake and Slate Crk, 0.60 Trinity, Oak Knoll RS and Coffee Ridge, 0.55 Mud Springs, 0.52 Fort Stewart and Miranda, 0.50 La Porte, 0.44 Humbug, 0.40 at Leggett and Shasta Dam, 0.36 Lassen, 0.33 Montague, 0.32 Mt Shasta City and Gold Lake, 0.24 Diddy Wells, Brandy Crk, Battle Ridge, Bucks Lake and Huysink, 0.23 Weed, 0.20 Sand Flat and Willits, 0.19 Brush Crk, 0.17 Blue Canyon, 0.15 Alturas and Redding, 0.13 Prattville and Alpine Village, 0.12 Alleghany, 0.09 De Sabla, 0.08 Yorkville, 0.06 Ukiah, 0.04 Four Trees, 0.02 Red Bluff, 0.01 Sierraville
FORECAST SUMMARIES
Days 1-7;
Fri, Feb 14th Valentine’s Day 582dm High Pressure continues to cover SOCAL with the ridge axis over CA, providing a SW flow pattern to continue to advect the near steady-stateAtmospheric River (AR) into the PACNW and the NW Coastal region of CA with extremely high QPF totals accompanied with high snow levels. This moisture is originating from near Hawaii. The calm conditions keep possible patchy night and morning overcast/fog regime in place over the SJV, with mostly sunny warm afternoons. SJV Temps have the potential to reach into the mid to upper 70°’s at the hottest Ag Stations. Overnight the High Pressure building northward and expanding into the Great Basin diverts the AR a bit further north into SW OR, and possibly Eureka or Crescent City. Meanwhile a trough approaches 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 accompanied by a tight pressure gradient which intensifies the heavy rains along the PACNW coastal region and into the NORCAL coast. As the tail-end of the ARcontinues to flow into NORCAL, partly cloudy skies extend SW offshore west of SFO. Overnight the remnant frontal boundary crosses thru NOR/CENCAL with some rainfall into the northern districts of CENCAL near the Delta possible, and partly cloudy skies to the south into Tulare and Kern Co.
Sun, Feb 16th Flat High Pressure extends over CA and a deep storm system is located in SW Alaska with the associated trough covering most of the GOA. The stead-state moist WSW flow pattern keeps warm/heavy rainfall into the PACNW, but not reaching into CA. Fair skies over CENCAL with a cooling trend due to an increase onshore flow. Overnight the wet storm activity returns into the far NW coastal region of CA.
Mon, Feb 17th More of the same…as the flat pressures over CA keep the warm/moist SW flow barreling into the PACNW and the NW Coastal region of CA with heavy rains, while the reminder of CA remains fair/mild. Overnight the GOA trough axis approaches the NORCAL Coastal region as the warm/heavy rains continue into the NORCAL coastal region down to Ukiah.
Tue, Feb 18th As the trough axis nears the NORCAL coastline with the heavy rains gradually spread over NORCAL down to near Marysville/Oroville, while partly cloudy to sunny skies remain over CENCAL. Overnight the RRR High Pressure ridge begins to rebuild over the MidPAC basin which realigns the flow pattern over NORCAL to the WNW as rains begin to diminish and temps begin to lower slightly.
Wed, Feb 19th The trough axis moving thru CA deepens with rainshowers over NORCAL intensifying, with chances of showers into reaching into portions of CENCAL down to Modesto/Merced to YNP. SOCAL remains fair/dry. The NW flow pattern continues to bring cooler temps to most of CA.
Thu, Feb 20th The RRR High Pressure shifts to 140W as the trough begins to settle into the Great Basin, providing CA with a drier NW flow pattern with cooler temps and diminishing shower activity. Overnight the pressure gradient over CA tightens with brisk NW winds and cooler temps.
Days 8-16, Long Range into Fantasyland Outlook; Day 8 begins;
Fri, Feb 21st shows the RRR High Pressure ridge moves closer to the West Coast with a NNW flow pattern over NORCAL and a N flow pattern over CEN/SOCAL, with fair skies and cooler temps advecting into the region with brisk winds continuing. Much drier air also reaches into CEN/SOCAL, with lowering dewpoints, with overnight patchy frost possible at the coldest Ag Stations.
Sat, Feb 22nd shows the broad 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 with calmer winds which may allow for more widespread frost overnight.
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. Overnight a minor shortwave trough dips into the NE quadrant of CA near Alturas bringing a chance of precip into then northern Sierra.
Mon, Feb 24th shows the minor shortwave which reaching into NE CA overnight drops southward to near YNP/Bishop and develops into a closed Low Pressure circulation with backwash type cloudiness reaching into the Sierra, with possible snow flurries along the Crest region. The RRR High Pressure ridge axis noses NE, extending into the PACNW, producing a cold/dry NE flow pattern into CA with colder temps. Overnight cloudiness over the SJV may dampen the potential frost conditions, otherwise if skies clear, then temps could produce widespread morning frost.
Tue, Feb 25th shows the RRR High Pressure ridge axis moving to 130W with the trough shifting into the Great Basin with increasing N to NE winds arriving into CA, with drier air and 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 dip below 32° at the colder Ag Stations with frost.
Wed, Feb 26th shows the RRR High Pressure ridge axis moving onshore over CA with a cold N flow pattern over CA producing Santa Ana conditions over SOCAL and clear skies over CENCAL, with overnight temps once again possibly producing patchy frost at the coldest Ag Stations.
Thu, Feb 27th shows the RRR High Pressure axis steepens and builds northward into western Canada, with the eastern downwind flank advecting cold Polar air into the Rockies and then into the Midwest producing yet another ARCTIC blast for the midsection of the nation! Earlier charts had this cold air dipping southward into the Great Basin, which would have been dangerously close to CA, but the more recent model trend is to shunt the bulk of the coldest air into UT instead of NV, which saves CA lots of heartache. This still should be monitored since the GFS shows a -38°C ARCTIC blast diving southward thru ID into UT…which is not that far away. Overnight as the ARCTIC blast dives into UT/CO, the flow pattern along the backside of the storm produces winds aloft over CA veering to the NORTH with cold/dry air from OR dropping into NORCAL.
Fri, Feb 28th shows the RRR High Pressure ridge axis moves over CA, with calm/clear skies and cool temps, with possible frost at the colder Ag Stations.
Sat, Mar 1st shows the RRR High Pressure ridge weakens over CA as a weak trough nears 140W with a limited moisture supply which produces high clouds over NORCAL. CEN/SOCAL remain fair/dry with a warming trend.
Special Notations; In the short term forecast period the moist Atmospheric River should continue to drench the PACNW and portions of NORCAL with heavy/warm subtropical rainfall with high QPF’s, with questionable amts of precip reaching further south, possibly reaching portions of CENCAL, and with higher probability for at least the Northern Sierra to receive some additional rains. The question of how far the moisture shield will expand southward into CA depends upon how far the shortwave carves out the western trough. Freezing/Snow Levels should gradually decline with time as temps cool dramatically as the zonal-type flow switches off. The recent forecast models have been consistently trending toward a transition from a low amplitude, progressive pattern toward a more amplified western trough/ridge pattern regime which eventually ends the zonal-type AR storm activity over NORCAL and the PACNW by next Thursday as the pattern buckles and amplification occurs. The model spread is still somewhat moderate for the leading features embedded within the fast flow aloft, but it is encouraging to see the GFS and EC models nearly in synch with each other on the large scale pattern solutions. It appears highly likely that most of CENCAL and all of SOCAL will end the month of February with record-setting dryness, compounding the deepening seriousness of the CA Drought. Analysis of the Northern Sierra 8-Station Climate History and the San Joaquin 5-Station Climate History will commence next week. In the meantime, we hope that you will tune in to the radio broadcast on Saturday morning with Rich Rodriguez as we take an early peak into some of the chart analysis that will be released next week.
TEMPS
Minimum Temps this morning at the Paramount Citrus Stations ranged from the coolest minimum of a 39° at Loma and Comanche, rising to the warmest minimum of 42° at Root Crk and Rayo.
Maximum Temps this afternoon at the Paramount Citrus Stations ranged from the coolest maximum of 71° at Horizon, rising to the warmest maximum of 78° at Ducor.
PRECIPITATION FORECAST
Day 1 – 5 QPF:
At 12Z (9am) Thursday thru the period Sunday night (Monday @4am) shows;
Thu shows the same rainfall pattern as the previous day, with reduced amts showing up to 2 inches for portions of Del Norte Co, 1 inch for most of Humboldt Co, with 0.5 inch for northern Mendocino Co up thru the Shasta basin, and >0.2 inch from Pt Arena to Red Bluff, and into the Feather and Yuba River basin and the Warner Range in the NE quadrant near Alturas. ALL of CEN/SOCAL remain completely DRY!
Fri shows the 3rd consecutive day with a similar pattern showing DRY conditions over CEN/SOCAL and the a wet pattern over NW NORCAL but with slightly higher QPF amts, showing up to 3-4.5 inches into the wet spots of the Smith River basin, up to 2 inches for most of the Klamath, with up to 1 inch for the Eel and Shasta River basins and up to 0.5 inch for northern Mendocino Co and up into the Lake Shasta then NE along the Pit River, with >0.1 inch from near Clear Lake NE into the Red Bluff area and toward Susanville.
Sat shows heavy precip continuing into the far NW Coastal region with up to 3 inches in the wet spots of the Smith River basin diminishing down to 1 inch for the reminder of the NW coastal region, the Shasta River basin, and the wet spots of the Feather River basin, with up to 0.75 inch from the Russian River basin northward along the coast over to Redding then southward into the Sierra down to the American River basin, with up to 0.5 inch from the Santa Cruz Mts northward along the coast to near Red Bluff then southward into the Sierra down to near the Stanislaus River basin, with 0.2 inch from Watsonville NE to Stockton then eastward into the Tuolumne River basin, with >0.1 inch from near San Simeon to Merced to near Pine Flat Dam and the middle fork of the Kings River basin.
Sun shows a drying trend with light amts of precip into portions of NORCAL from the Eel River basin thru the Shasta basin then southward down the Sierra to include the Kings River basin with >0.1 inch. Up to 0.2 inch falls from the Feather River basin south to the Tuolumne River basin. The remainder of CA stays DRY.
Mon shows up to 1 inch of precip into Del Norte Co, with rapidly diminishing amts to the south with drop down to >0.1 inch at Clear Lake to near Red Bluff and into the Feather River Basin. The remainder of CA stays DRY.
5DAY ACCUMULATION CHART: showing up to 9-11+ inches of precip falling into the wet spots of Del Norte Co and the Smith River basin!
Tuesday’s 7 Day Chart; shows increased precip for the NW Coastal region with up to 10-12 inches suggested into Del Norte Co with rapidly diminishing amts to the south, with the primary Mork rain/no rain you-get-none line running from near Santa Cruz to Modesto/Merced to Kings Cyn, with most of SOCAL and a portion of Kern Co remaining consistently DRY, except for some possible light showers along the coast. The Northern SJV is depicted with up to 0.25 inch with Madera Co south with >0.05 inch.
16-Day QPF estimates (from the 0Z GFS model) for;
Days 1-7; shows NORCAL receiving up to 10-12 inches in the NW Coastal region rapidly diminishing to 2 inches from Ft Bragg to the Lassen region, diminishing to 1 inch for Santa Rosa to Marysville to near the YNP region and 0.25 inch from Monterey to Modesto to Kings Cyn northward, and >0.1 inch from portions of the SOCAL Coast NE thru the Tehachapi Mts into portions of the Southern Sierra. SOCAL and a portion of SW Kern Co remains DRY.
Days 8-16; shows most of CA remaining DRY, except for the far northern Counties near the OR border region, with 0.1 inch thru the period ending March 1st. Colder temps begin Week #2 with possible AM Frost around Feb 22nd and 24th.
Tuesday’s 12Z 9am GFS 384hr, 16Day QPF Chart, depicting a wet NORCAL, semi-wet CENCAL, and a dry SOCAL. With up to 10-11 inches of rainfall along the OR coastline, diminishing to 5+ inches for the far NW CA coastal region, diminishing to 4 inches from near Eureka to the Shasta basin region, diminishing to 2 inches near Fort Bragg, to 0.75 inch in the north Bay region toward SAC and the Feather River basin with up to 0.5 inch from near Santa Cruz to near YNP, to 0.25 inch from Big Sur to near Merced to near Kings Cyn, with >0.1 inch from Vandenberg thru the Tehachapi’s and the Kern River basin. SOCAL and the SW portion of Kern Co remains mostly DRY.
SATELLITE
Water Vapor 4KM Image of the West Coast Thursday, February 13th, 2014, shows an Atmospheric River of moisture flowing over the top of High Pressure and into the PACNW, with the south flank of the event bringing variable amts of cloudiness into portions of NOR/CENCAL, while most of SOCAL remains clear.
Visible Satellite Image of the CA Thursday, February 13th, 2014, shows considerable cloudiness over NORCAL, with mostly clear skies over CEN/SOCAL. A standing, stacked, mountain wave cloud, lenticularis, has formed east of YNP to south of Mammoth Mt.
Radio Dialogue with Talk Show Host, Rich Rodriguez on “Powertalk 96.7 FM” in the Central Valley, and “1400 AM” in the South Valley on Saturday morning 8:30am.
The topic of discussion will be the current Drought situation. We’ll discuss this issue in detail and also taking an early peak at the Climate Analysis charts which we just completed regarding the drought impact upon both of the leading Sierra Precip Indexes. These charts will be discussed in detail with perhaps some surprising revelations. These charts will be released next week. In the meantime, we hope that you will tune in or call the Station if you’d like to ask questions during the broadcast.
If you have any questions please call or text at any time of day or night.
Comments and suggestions always welcome.
Atmospherics Group International
Dan Gudgel Steve Johnson
559-696-9697 559-433-7316