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December 31, 2006

Project Status: 31 December 2006

A weak non-precipitating system is passing through the American River Basin at this time, and is of little interest to HMT. Our attention remains on the system approaching on the 4th and 5th of January.

Current thinking is that this system will produce ~1" of precip in the ARB, though some feel it has the potential to produce closer to two inches at Blue Canyon. Precipitation is expected to begin in the early hours of the 4th (between midnight and 5 am local time) and end by the evening on the 4th: i.e. precipitation onset at 8Z(+) on Jan 4th and ending at ~0Z Jan 5th.

Our logic remains the same: given the paucity of events to date and forecasts of a quiet period for the next few weeks, we'll shoot for IOP #3. TENTATIVE plans at this time: SMART-R crews will travel on the 3rd. Sloughhouse soundings to begin late on the 3rd (though we'll wait to get a better fix on the onset of precip). A final decision can be delayed until January 2nd.

One final remark:
The SAC-WFO has extended an invitation for a visit, if the field crews have a little time. I highly encourage it, time permitting.


December 30, 2006

Project Status: 30 December 2006

Another dry day in the American River Basin today, however:

Our focus is now on the system that is approaching in the January 3-5 timeframe. Though speculative at this time, precipitation is forecast to begin in the ARB at about 4 pm on January 3rd (0Z Jan 4th). Consensus suggests that there could be 1 to 1.5 inches of precip in the ARB. The system appears to be setting up dynamically in a manner similar to the non-IOP event on December 26-27, 2006, which produced a reasonable amount of precipitation.

Thus, tentatively:
Given our discussion of the long range forecast yesterday, which suggested a dry spell over the next 1-3 weeks, I am inclined to call an IOP. This IOP would involve soundings at Sloughhouse (we'll save our special soundings at OAK and RNO for now) and SMART-R operations. A final decision will be made on January 1st. Stay tuned!

Instrument Status:
Final approval has been granted for the ALPS (AWIPS) stations in CNRFC, SAC-WFO, RNO-WFO and MTY-WFO (per Andy Edman, 28 Dec06).


December 29, 2006

Project Status: 29 December 2006

Dry conditions remain in place over the American River Basin. The weak system that is approaching on the 31st-1st is likely to pass south and eastward yielding (perhaps) a trace in the ARB. The next best bet for an IOP appears to be January 3-5, 2007, which could be like the system that impacted the region on Dec 26-27. We'll monitor this one...

Long-range discussion (with Klaus Weickmann and Ed Berry):
The long and the short of the long-range forecast is that the next 1-3 weeks look pretty bleak for the ARB, making the system on the Jan 3-5 potentially our best shot during this time. There is evidence to suggest that late January and February will be more active.

Instrument status issues:
The SMART-R is back at Forest Hill and is waiting for weather.


December 28, 2006

Project Status: 28 December 2006

Dry conditions prevail over the American River Basin today. A weak system may impact the region during the 31 December-1January period but will likely produce no more than 0.25 inches of liquid in our domain. Thereafter, the next good chance appears to be in the 3-4 January time frame. The next several forecast cycles will tell the tale on how that system evovles.

Tomorrow (Friday), Klaus Weikmann will lead a discussion about the long-range outlook. Please take a look at the forecast blog before the call tomorrow to obtain some supplementary material associated with his discussion.

Instrument status issues---

SMART-R: The generator for the radar has been repaired to produce the correct frequency of AC power, which appears to have solved the intermittent transmission problem that often occurred during IOP's 1 and 2.


December 27, 2006

Project Status: 27 December 2006

The precipitation event affecting the American River Basin since yesterday is winding down. Accumulations in the upper part of the basin are up to about 1.5 to 2 inches of liquid. In the lee of the Sierra crest, there have been accumulations of around 0.5 to 0.75 of liquid. The lower part of the basin and the Sacramento area have received about 0.75 to 1 inch of rain. Conditions will be drying out this evening and a ridge building in for dry weather over the next several days. The next chance for a significant precipitation event in our domain appears to be around 3 January.

Status issues--

SMART-R: still on schedule for repairs to be complete by Thursday (tomorrow) afternoon

Surface Met: Software bug for web plots of precipitation at Norden, Onion Creek and Duncan Peak has been corrected. Wet bulb temperature is now being displayed for several sites (Colfax, Big Bend, Blue Canyon, Foresthill, Truckee and Cazadero)

ALPS Workstations: Workstation(s) for Sacramento are almost ready to ship (next day or two). Installation can take place next week.


December 26, 2006

Project Status: 26 December 2006

A significant precipitation event will impact the American River Basin today, tonight and into early tomorrow. Blue Canyon should receive somewhere between 1.5 and 3 inches of liquid. Snow levels will start out relatively high (7-8 kft) but then descend to around 5000 ft. Unfortunately, this event is occurring during our pre-determined hard-down period for the project. We are not scheduled to resume possible IOP activity until Thursday 28 December. The forecast for Thursday into this upcoming New Year's holiday weekend does not indicate any significant precipitation events for our domain of interest. Medium-range models are hinting at a pattern change just after the New Year that may lead to better chances of precipitation in the American River Basin.

Instrument status issues-

SMART-R: An NSSL staff member is going out to northern California to expedite the repair of the radar. At present, the suspicion is that the problem is related to the power generator for the radar. If this suspicion is true, then it is estimated that repairs could be completed by the afternoon of Thursday 28 December (i.e., 2 days hence).

Unattended surface meteorology: The problems with the tipping bucket rain gauge at Foresthill mentioned last week have been repaired. However, we have identified a faulty temperature sensor at Bodega Bay and a faulty disdrometer at Cazadero. Repairs to these sensors are likely to occur during the week of 1 January. Also, some people might have noticed some strange readings from the web plots of precipitation gauge data at Norden and Onion Creek during IOP-2. These issues appear to be related to a software bug in the plotting routine rather than a problem with the instruments themselves. A fix to the software bug is being developed at present.


December 22, 2006

Status: 22DEC06 (sunrise)

The HMT project is now on its pre-determined holiday break. There will be no data collection by attended instruments (SMART-R scanning and Sloughhhouse soundings) on DEC 22, 23,24,25,26 and 27 during the break. Of course, the vast majority of HMT instruments operate unattended, and will continue to monitor weather conditions through the break.

Yesterday's storm did indeed deposit 2.24 inches of precipitation (liq. equiv.) at Blue Canyon and 1.93 inches at Foresthill, and might have made an interesting IOP. Unfortunately, the SMART-R problem caused the IOP to be aborted early on (see yesterday's mid-day status report). The SMART-R problem needs a plan for quick remedy from NSSL and the radar's consortium. The huge storm in Denver (20-30 inches of snow) at holiday time also now forces our SMART-R operator, Bruce Bartram to drive back home to Denver, instead of flying. The only good news from yesterday is that the precip gauge at Foresthill is now working, thanks to another visit by SHS crew member, Danny.

The next HMT conference call will be on December 26th, with Dave Kingsmill presiding.

- Martner

December 21, 2006

Status: 21DEC06 (Thursday, mid-day)

IOP-2 is cancelled in mid stride. The storm is developing pretty much as was forecasted yesterday, but a failure of the SMART-R radar has forced a early end to this IOP. The radar began scanning at 15UTC, 21DEC (7 am PST) and operated for an hour or two before the transmitter began shutting off almost constantly. Bruce Bartram suspects an unstable generator (flakey power) is the source of the problem. His consultantion on the phone this morning with the radar's designer/engineer at Texas A&M did not result in an in-the-field solution. A major repair job is apparently needed. Meanwhile, 3 soundings were launched from Sloughhouse at 12, 16, and 20 UTC this morning, before the IOP was shut down, with the bad news about the radar. Reno NWS also launched a sonde at 18 UTC, on their own funding, because of a rare freezing rain situation there. For the record, the truncated IOP-2 covered 12UTC-20UTC on 21DEC06.

The SMART-R needs to be repaired before another full-blown IOP can be conducted, but the schedule for a repair is very uncertain now because of the holidays. NSSL will come up with a repair plan and will keep the HMT Chief Scientists informed about it.

The predertimed holiday break begins now for the attended instruments. The next conference call will be on December 26.

- Martner

Status: 21DEC06 (morning)

IOP-2 is underway. Light precipitation began at about 14 UTC this morning in the ARB, as predicted. Soundings from Sloughhouse were scheduled to begin at 12 UTC. The SMART-R is scanning and will be operated by a one-man crew (Bruce Bartram) as long as reasonably possible today.

- Martner

December 20, 2006

Status: 20DEC06 (late afternoon)

IOP-2 continues on schedule for a start tomorrow morning. However, JJ Gourley's flight out of OKC to LAX and SMF has been cancelled due to flight disruptions of the Denver storm. Thus, we will attempt to cover as much of the Thursday storm as we reasonably can with only Bruce Bartram operating the SMART-R. Sloughhouse sounding schedule remain unchanged.

- Martner

Status: 20DEC06 (Wednesday)

IOP-2 is still on schedule for the storm that will cross the Project area tomorrow. The latest forecast models show the timing and strength of the storm is about the same as predicted yesterday. Precipitation should begin in the ARB around dawn Thursday and will accumulate 1-2 inches before it's all over on Friday morning.

Soundings from Sloughhouse will begin at 12 UTC on 21DEC (4 am Thursday) and will continue at 4-hour intervals until 08 UTC on 22DEC (midnight Thursday), for a total of 6 soundings. No supplemental NWS soundings are requested. SMART-R crew has Bartram already on hand in Auburn and Gourley arriving late tonight. They should be prepared to begin data collection with the radar as early as 14 UTC, 21DEC (6 am Thursday) and to continue until the pre-dawn hours of Friday morning.

One more daily confernce call will be held tomorrow before the holiday break.

- Martner

December 19, 2006

Status: 19DEC06 (Tuesday, late afternoon)

The models have somewhat intesified the precip predicticed to fall in the project area from a storm that will cross the area on Thursday. QPF is in the 1-1.75 inch range. That's a little below our 2-inch "desirable" threshold. But the precipitable water vapor associated with this case is forecast to be around 3 cm, which is about as high as we've had in December. It promises to be a quick hitting storm with a sharp cold front.

IOP-2 will be conducted on the Thursday storm. Sloughhouse soundings will begin at 12 UTC on 21DEC (4 am Thursday) and will continue at four-hour (not 3) intervals through 08UTC on 22DEC (midnight Thursday), for a total of six soundings. No supplemental NWS soundings from Oakland and Reno are requested. SMART-R crew (JJ Gourley and Bruce Bartram) should be ready to begin scannning before sunrise on Thursday. Bruce Bartram has a flight to Sacramento tonight to beat the snowstorm that is taking aim at Denver tomorrow. JJ has booked a flight that gets him into Sacramento around 10 pm Wednesday. He connects through LA, thereby avoiding the Denver snowstorm. The holiday break will begin when SMART-R operations close down very late Thursday night or before sunrise on Friday. Thanks are exended to everyone for being willing to scramble on this.

The daily conference calls will continue at usual time on Wednesday and Thursday.


December 18, 2006

Status: 18DEC06 (Monday)

Cool, dry weather is expected to continue over the HMT project area through Wednesday. A weak/moderate storm is currently forecast to pass through the area on Thursday. Therefore, it is possible (but not yet likely) that crews will need to travel out to California Wednesday and return home on Friday. We will monitor the situation and update on the conference call tomorrow.

The GSD workstations are still awaiting formal permissions for installation at the WFOs. When those oks come in, one will be installed and tested at the Sacramento WFO first, before the installations at Reno and Monterey.

The HMT pre-determined holiday break is approaching, and that schedule is summarized here:
No data collection by attended instruments (SMART-R and SHS soundings) on 22DEC, 23DEC, 24DEC, 25DEC, 26DEC, and 27DEC. The daily conference calls will resume on 26 DEC. At the end of the break, the SMART-R crew should be prepared to travel to California as early as 27DEC for an IOP on 28DEC, if the forecast warrants it. Of course, most HMT instruments operate unattended and will continue to monitor the weather through the break.

- Martner

December 17, 2006

Status: 17DEC06 (Sunday)

Cool, dry weather will continue over the HMT project area for the next few days. It looks like the next chance for a storm will begin on Wednesday-Thursday.

Meanwhile, no crew deployments and no IOP.

- Martner

December 16, 2006

Status: 16DEC06 (Saturday)

Yesterday Blue Canyon picked up just over 1 inch of precipitaiton. Now the upper-air trough is digging far south and is predicted to cut-off over about Yuma, AZ. That couldl bring wrap-around snow showers to the HMT project area tomorrow, but more likely no precip at all with some downslope wind over the west slopes of the Sierra. The longer outlook is for dry conditions into at least Tuesday.

Meanwhile, no IOP and no crew deployments for now.

- Martner

December 15, 2006

Status: 15DEC06 (Friday)

Orographic precipitation is ongoing in the HMT project area mountains as the trailing cold front from the Oregon storm drags across northern California. The precipitation total at Blue Canyon will probably exceed 1 inch before this storm is finished. Only scatttered light showers are expected tomorrow. After that, colder dryer weather prevails over the area for a few days.

Therefore -- no IOP and no crew deployements for this weekend. Daily conference calls will continue at the usual time through the weekend.

Instrument problems: After two attempts to fix it, the precip gauge at FHL is still not working.

- Martner

December 14, 2006

Status: 14DEC06 (Thursday)

The big Oregon storm will bring a trailng cold front across the HMT project area tomorrow morning. About 1 inch of precip is expected in the ARB from this event by the end of Friday, according to the models and project forecasters. By Saturday morning the long, moderately wet spell may be over. The Sacramento WFO, howver, still thinks the models underplay this storm in N. Cal. and has issued a winter storm watch for the western slope Sierra. We will see if they are more on target than the models. Meanwhile, however, HMT will stick with yesterday's decision. No IOP and no crew deploymnets for Friday, as we save our resources for bigger future storms. The farther outlook suggests colder, dry weather setting in on Saturday.

- Martner

December 13, 2006

Status: 13DEC06 (Wednesday)

A big, wet storm is headed for Oregon in the next two days. However, nearly all of the numerical models and the Project forecasters agree that this storm will stay too far north to bring more than about 1 inch of precip to the ARB. Our forecaster at the Sacramento WFO is the exception, and cautioned us to have skepticism about this pessimism. However, with HMT still having 3 months remaining, we will save our resources for the possibility of bigger future storms that we have more confidence in occuring than this one.

Therefore --- no crew deployments for Thursday evening.

The next system is shown by some models to split and send its precip to Southern California instead of the ARB on Saturday. But that scenario is also in doubt. If tomorrow's forecast runs redirect this system more toward the ARB, the next IOP could begin as early as Friday evening.

The HMT Web page now has a link under "Operations Summary" (left sidebar) to a brief overview of IOP-1, including lots of maps and data products that can serve as a starting point for analyzing that case.

- Martner

December 12, 2006

Status: 12DEC06 (Tuesday)

The next IOP could come as early as Thursday evening for a storm with 2-3 inches of precip. Or it might be a Friday afternoon start up. There are varying opinions among the Projects' forecasters and models about the timing and intensity, but the SMART-R and SHS sounding crews should be aware thay they might be called on to start operations as early as Thursday afternoon. Bruce Bartram is available to start up SMART-R, assuming he can get out there earlier from Colorado than Kevin or JJ can. A decision on whether/when to deploy will be made at tomorrow's conference call. Operations, if initiated might go into the weekend. The oncoming storm does not look impressive enough to warrant supplemental NWS soundings at Oakalnd or Reno.

Wind directions from the SHS profiler have now been corrected.

- Martner

December 11, 2006

Status: 11DEC06 (Monday)

IOP-1 concluded Sunday evening. It covered the period 06UTC, 9DEC to 02UTC, 11DEC. Blue Canyon recorded 2.44 inches (liq. equiv.) of precipitation, including about 9 inches of snow, which accumulated after 07UTC,10DEC. Precip rates at BLU were remarkably steady at about 1.5 mm/hr throughout the IOP, even though rain changed to snow there and Central Valley and lower foothills locations had significant lulls between 3 rainy waves. Some gages in the Coast Range received 5 inches of liquid from the event. With a few rather minor exceptions, the HMT instruments worked well. Some of those instrument problems will be fixed in the next day or two. Overall, IOP-1 was a successfull first event for the HMT season.

The forecast now calls for light precip on Tuesday, but not up to IOP thresholds. The next reasonable storm possibility appears to be on Thurs-Fri.

- Martner

Status: 10DEC06 (Sunday night)

IOP-1 ended at 02UTC, 11DEC (6 pm PST Sunday) as lingering snow showers dwindled in the Sierra. Total precip accumulation for the IOP was about 2.40 inches at Blue Canyon, including about 9 inches of snowfall.

The SMART-R crew will return home on Monday, with Bruce Bartram staying until Monday night, in case he is called on to look into instrument problems at Foresthill and Sloughhouse during the day.

The next IOP-size storm is not expected to arrive until late in the week.

- Martner

December 10, 2006

Status: 10DEC06 (Sunday, mid-day)

IOP-1 is continuing, but the final shot of precip is now crossing the Sierra foothills. Blue Canyon has had about 2.00 inches of liquid equivalent, including about 7 inches of snowfall in the IOP. There has been 10-12 inches of snowfall abouve 7 kft.

Soundings from Sloughhouse have ended. SMART-R will continue scanning until 02UTC on 11DEC (Sunday, 6 pm PST). That will mark the end of this IOP. The radar crew will travel home on Monday or Monday night.

Although a big storm will hit the Pacific Northwest on Tuesday, the forecast models are predicting only minor QPF amounts in the ARB. Thus, no new IOPs are anticipated for a few days.

- Martner

Status: 10DEC06 (Sunday, sunrise)

IOP-1 is continuing. Last night's wave added about 5 inches of snowfall at Blue Canyon and about another 1.00 inches of liquid equiv. That brings the IOP total to about 2.00 inches there. Precipitable water vapor content was about 0.3 cm less in this second wave than in the one Friday night, but still a respectable 2.2 cm at SHS. Temperatures at BLU dropped to -2C. The CFC profiler shows the rain/snow height dropped 0.8 km between 04 and 14 UTC last night. The upper-air trough recently passed the ARB into Nevada. Precip continues in the mountains and Central Valley as one final shot of wetness (maybe including thunderstorms) moves through.

Eleven soundings were launched from Sloughhouse; no more will be done for this IOP. SMART-R will continue scanning at least until mid-day.

Ridging will then move into the area. Models show the next storms being big for Washington and Oregon, but maybe too far north for HMT.

- Martner

Status: 9DEC06 (Saturday evening)

IOP-1 is continuing. After a long lull in the precip, moderately heavy rain is now crossing the Central Valley and entering the foothills as the second wave moves across California. This wave is colder and its precip should be more intense than last night's. Sloughouse is now up to 1.00 inches of accumulation. Cazadero in the Coast Range has had 3.00 inches.

Soundings from Sloughhouse will continue thru 12 UTC, 10DEC (4 am Sunday). SMART-R scanning will continue through the night and beyond.

- Martner

December 09, 2006

Status: 9DEC06 (Saturday, mid-day)

IOP-1 is continuing. Accumulations (liquid equivalent) thus far include approximately 0.3 inches at Sacramento, 0.5 inches at Colfax, and 1.0 inches at Blue Canyon. Now there is a lull, and only light precip is expected in the ARB this afternoon. But tonight, the second wave will move through bringing colder air and more intense precipitation. The snow level may drop to 4.5 kft before sunrise.

SMART-R will continue to scan at least through mid-day Sunday, and probably beyond that. Soundings at Sloughouse will continue unitil 12 UTC, 10DEC (4 am Sunday), for a grand total of 11 soundings in this IOP.

Problems: The precip gage at FHL is not working. The ETI precip gage at Duncan Peak is underreporting. Wind directions aloft from the SHS profiler were reversed from their true directions after a computer re-boot at 11 UTC. Another re-boot will attempt to fix that. Smart-R is experiencing problems with its UPS which caused a loss of 35 minutes of data abound 07 UTC. The crew will keep an eye on the problem and have a work-around plan if it occurs again.

- Martner

Status: 9DEC06 (Saturday sunrise)

IOP-1began at 06 UTC (10 pm Friday night) and is continuing. SMART-R actually began collecting data at 0546 UTC at Foresthill, The first few sonde launches from Sloughouse have gone well and will continue at 3-hr intervals through today. At Blue Canyon precipitation began at 07 UTC and had accumulated 0.6 inches (liquid) by 13 UTC (5 am this morning). Temperatures there dipped to near 0C at 08 UTC and have risen to 3C by 13UTC. At Colfax about 0.4 inches of rain had fallen by 13 UTC. The S-band radar profiler at Colfax-CFC showed a prominent melting layer bright band with the snow/rain height rising by about 0.5 km between 04 and 11 UTC. Precipitable water vapor measured by GPS-Met reached 2.5 cm at Lincoln and Sloughhouse and only 1.0 cm over Truckee.

- Martner

December 08, 2006

Status: 8DEC06 (Friday, mid-day)

The first precip of the HMT season is approaching. However, the forecast models have slowed the progress of the first wave considerably. Precip in the ARB is now expected to begin tonight. The heaviest precip is now expected to occur Saturday night, instead of Friday night, as had been forecast a couple days ago. It could be Monday morning before there's a significant break in the action, and we might get as much as 3 inches (liquid equivalent) accumulated by then. If so, that would make a pretty good IOP. But if even if we get considerably less precip, this IOP will allow us to test systems and get the wrinkles out early in the project.

Hence, IOP-1 will begin at 06UTC on 9DEC (10 pm PST Friday) with the first of the SHS soundings. Soundings will be launched at 3-hr intervals. A total of 10 soundings have been requested for this storm. No supplemental NWS sondings are requested. The SMART-R crew should be ready to begin data collection as early as 09 UTC (1 am PST Saturday) and should be prepared to continue for at least 48 hours. Bruce Bartram will try to fix a couple of instrument problems this afternoon at Alta and Blue Canyon.

Daily conference calls will continue at the usual time through the weekend.

- Martner

December 07, 2006

Project Status: 7 December 2006

We are still expecting wet weather in the American River Basin this weekend, but there have been some changes in the model solutions relative to yesterday's output. First of all, the onset of precipitation for the first system is likely to be about 6 hours later than thought yesterday; some sporadic showers might occur during the 03-06 UTC (9 December) time period with more steady precipitation after 06 UTC. Also, the distinction between the first system and the second system discussed yesterday has become blurred. At this point, it looks like we may have no clear break between the systems. In effect, we may experience intermittent precipitation in our domain throughout the weekend. The total accumulation of precipitation for the weekend might be in the 1-2 inch (liquid) range. Snow levels are likely to start out around 1.8 km, but descend to below 1.5 km by event end. Of course, there still is some uncertainty in this scenario, especially in how the latter half of the weekend weather might play out. This case might serve as a nice model comparison/validation study given the relatively wide range of solutions that we have seen.

We still plan to execute an IOP for this event. We will likely treat the entire weekend as a single IOP rather than as two seprate IOP's. Given the evolution of the model guidance in the last 24 h, we will delay the beginning of 3-hourly Sloughhouse sonde launches from 18 UTC 8 December to 00 UTC 9 December (we are not requesting supplemental releases from Oakland or Reno). At present, the plan is to continue the three-hourly Sloughhouse soundings into mid-day Saturday. Plans for soundings after this time will be refined on Friday based on the latest observational and model guidance.

We are also delaying the beginning of SMART-R radar operations. At present, the crew for the SMART-R should be prepared to begin operating the radar in the 00-03 UTC 9 December time frame (4-7 pm local time). They should be prepared to operate the radar throughout the weekend, perhaps into Sunday evening. An update to this suggested plan will be provided mid-day on Friday based on the latest observational and model guidance. The SMART-R crew should communicate with the Chief Scientist (starting tomorrow, Brooks Martner) before departing for the Foresthill radar site (see project staff telephone list on this blog).


December 06, 2006

Project Status: 6 December 2006

The long advertized shift in the weather pattern for the American River Basin is now materializing. A frontal system will make landfall along the northern California coast on Friday morning and start to impact our domain by the afternoon. This event is not forecast to produce a large amount of precipitation; probably not more than 1.5 inches of liquid before it winds down on Saturday morning. There is another system that may impact our domain on Sunday, but there is a large spread in the forecasts for this potential event. The big concern is that wave energy will get split into two streams; one north and another south of our area, with the southern branch probably being more potent (i.e., good for SoCal).

We have decided to declare an IOP for the system forecast to impact the ARB on Friday/Saturday. Although this system is not particularly impressive, executing an IOP will allow us to work out any kinks in our process, which might benefit us later when bigger systems make landfall.

Staff for operating the SMART-R should depart for the ARB on Thursday and be prepared to start operating the radar between 18-21 UTC on Friday (8 December). They should be prepared to operate the radar Friday night into Saturday morning.

We are NOT requesting supplemental soundings from Oakland and Reno for this event. However, we will be launching sondes from Sloughhouse. The current plan is to commence 3 hourly soundings at 18 UTC Friday (17 UTC release) and continue through 12 UTC Saturday (9 December).

Instrument status issue:

The data acquisition problems with hot plate and disdrometer data at Cazadero, Colfax, Alta, Blue Canyon and Big Bend have been resolved. Data is now being acquired normally.


December 05, 2006

Project Status: 5 December 2006

Conditions over the American River Basin continue to be dry (with the exception of some fog reported in the Sacramento valley). However, changes to the weather pattern will start to impact the area on Friday. The current forrecast calls for a frontal system to make landfall on Friday morning and impact the ARB by early to late afternoon. The effects of the system might last into Saturday mid-morning. The system does not look particularly intense, with forecast precipitation totals of 1-2 inches of liquid. Also, the direction and magnitude of flow at 850 mb is not ideal for orographic enhancement. Another system is on its heels and could start to affect the ARB by early Sunday morning. There are some model solutions that suggest the Friday system will split, with most of its energy moving south of our area. Still other model solutions suggest the same fate for the Sunday system. We will have to closely monitor the model output over the next couple of forecast cycles to see if a consensus solution emerges. If we want to have an IOP for the Friday system, a decision on declaration will have to be made tomorrow (Wedneday, 6 December).

The meduum range model solutions indicate a pattern that leaves the US West Coast susceptible to landfalling storms for the next 10 days or so. The question is whether the storms will take aim at northern California.


December 04, 2006

Project Status: 4 December 2006

Although conditions are currently dry in the American River Basin, the stage is being set for changes later this week that may lead to a series of landfalling frontal systems to affect the area. Current model guidance indicates that the first system may impact the area on Friday into early Saturday and then another system late Sunday into Monday. We will watch the evolution of the model output over the next day or so to determine whether or not to declare an IOP.

Instrument status issues:

The data communication problems at Colfax and Sloughhouse that were reported a few days ago have been resolved. These issues were related to the profilers and surface meteorology sensors at those sites. However, we are now having some acquisition problems with data from disdrometers and hot plate precipitation gauges at Cazadero, Colfax, Alta, Blue Canyon and Big Bend. These problems are being addressed by PSD staff.


December 03, 2006

Project Status: 3 December 2006

Beautiful weather over the American River Basin today, if you are not interested in precipitation. The pattern shift advertized for the past couple of days is under way in the North Pacific. This shift will enhance chances of precipitation in our domain later this week. Thursday is still appears to be the earliest that wet weather could affect our domain, but the probability of wet weather increases as we move to Friday and Saturday. Medium-range statisitical guidance suggests that these events will likely not produce large accumulations of precipitation (i.e., these are likely to be "average" events relative to climatology).

Sounding status issue:

Training of students to launch sondes at Sloughhouse was completed successfully yesterday. When needed, we are now ready to execute sounding operations at this site.


December 02, 2006

Project Status: 2 December 2006

Dry conditions prevail over the American River Basin, a situation that will persist into at least the middle of next week. Medium-range forecasts are still advertizing a weather pattern shift late next week that should lead to a more zonal flow over the Pacific Ocean, which will enhance the chances of tapping into tropical and/or subtropical moisture. At present, the Thursday-Friday timeframe of next week appears to be the earliest that we could see wet weather in our domain. This shift in the weather pattern comes with the distinct possibility of multiple short waves making landfall on the US West Coast after the intial weaather system hits. Time will tell whether the track of these storms will direct them over our domain.

Web page status issue:

Based on suggestions from yesterday's Advisory Panel teleconference, a blog has been added to the project web page that will allow discussion of weather issues relevant to HMT-West. It is called the Weather Forum. You can access the blog by clicking on the "Weather Forum" link under "Project Information". Details on how to add content to that blog will be posted on the Weather Forum blog later today.


Project Staff Schedule

This file contains the project staff schedule:

Download file

December 01, 2006

Project Status: 1 December 2006

Dry conditions continue over the American River Basin. Medium range forecasts are relatively persistent in predicting a weather pattern shift late next week, probably in the Thursday-Friday time frame.

Instrument status issues:

The 915 MHz profiler at Sloughhouse is now installed and its data viewable on the project web page. We are experiencing some data communication problems at our Colfax (CFC) site. These problems are in the process of being addressed.