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January 31, 2006

Project Status: 31 January 2006 (Tuesday noon)

The mid-week storm is now coming onshore in Oregon. Although the Eureka NEXRAD is showning widespread echo, it is mainly from mid-level cloud and virga so far. Precipitation in the ARB is expected to begin around 10 pm PST tonight and to be heaviest Wednesday afternoon. The research radar crews are on their way to California and should be ready to collect data by tonight. IOP-10 will begin as soon as they judge conditions to be ripe for data collection, but no later than 4 a.m PST, Wednesday. Radar operations might continue into early Thursday morning. Supplemental soundings from OAK will cover 12 UTC on 1FEB to 12 UTC on 2 FEB. Slough House soundings have been requested for the same period, but the crew of local students lined up so far only covers the latter portion of the period.

The deployment and scheduling for IOP-10 has been based largely on the NAM model, which is calling for much more precip (1.5-2.0 inches) in the ARB than do the GFS, Canadian, or European models. It will be interesting to see if the loner (NAM) is right - let's hope so.

The next storm is expected on Saturday, but that currently looks weak.

- Martner

January 30, 2006

Project Status: 30 January 2006 (Monday)

Another weak-to-moderate storm is crossing the ARB today but no intensive operations arel being conducted for it.

The next storm opportunity is in the Tuesday night to Thursday morning time period. Models show huge QPF disagreement for this warm, zonal-flow system, with the GFS expeting less than an inch, and NAM going for up to 3 inches. There is a respectable (1-1.5 inches PWV), but narrow, plume of water vapor from the tropics showing up on all of the models and poining toward north-central California. The next storm on Saturday looks weak now, and there are suggestions that next week might be very dry.

We will go after the Wednesday storm as IOP-10. This is gambling that the dry GFS is wrong. But it's not a wild bet, given that we've saved funds and sondes in the previous two weeks, and if the NAM model is right, the Wednesday storm would be wetter than any we've seen since New Year's.

Radar crews will travel to California tomorrow morning and should be prepared to begin collecting data as early as tomorrow evening, if precipitation begins in the area that soon. They should be prepared fo at least 36 hours of continuous operation. Slough House soundings will be launched at 3-hour intervals for a 24-hour period starting at 12 UTC, February 1st (4 a.m. PST, Wednesday). Oakland supplemental soundings should be launched at 3-hour intervals from 15 UTC, Feb. 1 through 09 UTC, Feb. 2.

- Martner

January 29, 2006

Project Status: 29 January 2006 (Sunday)

IOP-9 ended last night. It involved only soundings from Slough House, which were launched at 3-hr intervals from 12UTC on 28 JAN to 09 UTC on 29JAN. About 1.4 inches of liquid equivalent fell at Blue Canyon in the 24-hr period ending at 12 UTC today; Alta had about 1 inch, Colfax 0.6 inches, Auburn 0.4 inches, and Sacramento about 0.1 inches. In this regard, IOP-9 was similar to IOP-s 7 and 8. Vertical storm structure monitored by the S-band profilers at Colfax and Alta showed the shallow, orographic nature of the storm, with echo tops declining from 4 km early to 2 km late in the storm. A prominent melting-layer bright band was located at about 2 km much of the time.

Tomorrow another modest storm will cross the ARB. It is expected to produce about 0.8-1.5 inches in the ARB. This again is little below our new crew deployment threshold for warm storms, hence we will let this one go by with only the unattended instruments collecting data.

After that, the next storm is in the Tuesday night to Thursday morning time frame. The QPF for this midweek system continues to decline. Now less than an inch is expected from it, unless the long, narrow plume of tropical vapor makes a direct hit on the ARB. The research radar crews should be prepared to travel to California Tuesday morning, but that travel will likely be called off or delayed at tomorrow's conference call. It now also seems unlikely that we will want Slough House or Oakland supplemental soundings for Wednesday, but that remains a possibility to be decided at tomorrow's conference call.

- Martner

January 28, 2006

Project Status: 28 January 2006 (Saturday)

NWS has a winter storm warning out for the western slopes of the northern Sierra. About 1 inch of liquid equivalent is expected in the ARB. IOP-9 is underway on this storm in the form of soundings from Slough House, which are being conducted from 12 UTC today to 9 UTC Sunday. No research radar operations or Oakland supplemental soundings will occur, however, with this modest system.

Next in lne is another warm storm on Monday and perhaps another Weds-Thursday. The Monday storm looks stronger (1.5 inches) than it did in yesterday's forecast, but still somewhat below our deployment threshold. Hence, in the interest of conserving funds and resources for bigger or colder events, there will not be an IOP for Monday. Forecasts for the Wednesday-Thursday storm look less promising now than they did yesterday, but still hold some hope for an IOP-level event.

- Martner

January 27, 2006

Status Report: 27 January 2006

Most forecast models are expecting 0.5-1.0 inches in the ARB tomorrow (Saturday) from the southern end of the big storm in the Pacific Northwest. HMT will conduct a reduced IOP (IOP-9) for this storm with souunding operations from Slough House from 12 UTC Saturday to 9 UTC Sunday. There will not be any research radar opeartions or supplemental OAK soundings, however.

In the medium range, more systems are predicted to cross the ARB next week. The first one on Monday does not look impressive and we will not deploy crews for it. But the one after that, now scheduled for Wednesday-Friday (Feb 1-3) is starting to look pretty interesting. See "Forecast" for details. Maybe groundhog day will be good for HMT. We will eye it carefully on the next few daily conference calls.

- Martner

January 26, 2006

Status: 26 January 2006

Although Oregon will get pounded, the models are expecting only modest precip (~ 0.8 inches) from the south end of the same warm system in the ARB on Saturday. Under the old QPF thresholds this would be tempting, but not under our new interest in concentrating on stronger warm storms henceforth. Dave Reynolds cautions that it would not take much of a southward push to change Saturday from modest storm to big storm for the ARB. Nevertheless, going with the mainstream of forecasts, we will not deploy the research radar crews for the Saturday storm, nor will we request supplemental soundings from Oakland. However, Dave White has lined up the local students to make soundings from Slough House for Saturday 12 UTC to Sunday 9 UTC. That will become IOP-9, with SHS soundings, but no reseach radar operations.

- Martner

January 25, 2006

Project Status: 25 January 2006

Weak precipitation events will affect the American River Basin over the next few days. Probably no more than 0.25 inches of liquid will fall during this period. Another system may influence the ARB late Saturday into early Sunday, but the main part of this system is well north of the ARB. We are not planning on any radar crew deployments or sounding operations for these events. At present, the best chance for our next significant precipitation event in our target area appears to be in the late Monday to early Wednesday period of next week.

Kingsmill

January 24, 2006

Project Status: 24 January 2006

The forecast calls for no more than light precipitation (no more than 0.25 inches) to fall in the American River Basin on Thursday. No radar crew deployments or sounding operations are scheduled for this event. The next possible event would be Sunday. However, the storm track will probably need to sag further south for that event to be significant enough to declare an IOP. Stay tuned.

Kingsmill

January 23, 2006

Project Status: 23 January 2006

The system that we thought might bring significant precipitation to the American River Basin on Thursday is now very unimpressive in the latest forecast simulations, probably less than 0.5 inches of QPF. Therefore, we have opted to not sample this system. The next system to affect the ARB may arrive this weekend at some point.

Given that we will not need to use Tuesday to decide on a crew deployment, let's plan on having a slightly longer coordination call (maybe 30 minutes) that allows us to look retrospectively at what we have accomplished so far and to discuss such things as what has gone well and not well, what have we learned, what has been useful, and what has surprised us. To help provide context for such a discussion, please take a look at the Operations Summary blog, where operations summaries for IOP's 1,2,3,4,5,7 and 8 are accessible. In addition, overview statistics for the project so far are available on that blog.

You may be interested in the fact that HMT-West is now being featured on the NOAA Home Page. Direct access to the story can be obtained by going to:

http://www.noaanews.noaa.gov/stories2006/s2563.htm


Status:

1. The Point Piedras Blanco wind profiler has been repaired and its data are being displayed in real time once again.

2. There will be a power outage in the ESRL building in Boulder this weekend. At present, the outage is scheduled to occur from about 5 pm MST Friday 27 January to 12 noon MST Saturday 28 January. This power outage will result in the project web page being inaccessible (i.e., no access to the status blog or to real-time data).


Kingsmill

January 22, 2006

Project Status: 22 January 2006

Apologies to those who tried to tune in to the call today, but did not get through. I eventually got through to Alan Haynes and discussed the weather situation.

The last few model cycles have produced solutions that are more favorable for our target area. In particular, there appears to be a system that may impact the American River Basin during the day on Thursday. Thereafter, the pattern suggests another system for the weekend and a favorable pattern the following week. In addition, MJO activity in the tropical western Pacific is coming alive, which may bode well for our project.

With the current scenario, decisions on crew deployments and soundings will probably need to be made on Tuesday. Therefore, I think we should postpone the debriefing call to a later date---I really thought the quiescent period would last longer.

Kingsmill

January 21, 2006

Project Status: 21 January 2006

Only very light precipitation (a few hundredths of an inch) fell in our target area during the last 24 hours. The forecast calls for dry weather over the next several days. The next possible significant precipitation event for the American River Basin will not be until at least late next week, and the confidence in that systeme actually materializing is pretty low given the wide ensemble spread.

Kingsmill

January 20, 2006

Project Status: 20 January 2006

Over the next few days, there may be some light precipitation in the American River Basin. However, none of this seems worthy of an IOP. The next significant precipitation event advertized in the models is late next week.

Given our entry into a relatively quiescent period in terms of HMT-West operations, it may be timely to have a somewhat longer call during the early to mid part of next week (tentatively, let's plan on Tuesday 24 January) where we can take a step back and see how things are going in the project so far (e.g., what is working well?, what is not working so well?, what have we learned?, what is useful?, how could we do things better?, etc.). Summaries for IOP's 1-5 are accessible on the HMT-West web site now; I hope to have summaries for IOPs 7 and 8 accessible by the end of this weekend (I need to speak with Dave Jorgensen about the summary for IOP6).

Kingsmill

January 19, 2006

Project Status: 19 January 2006 (noon)

The research radar crews are returning to their home bases in Colorado and Oklahoma today and tomorrow following the completion of IOP-8 yesterday. A weak weather system on Friday-Sunday may bring showers and as much as 0.25 inches of rain to the ARB, according to some models. This is not enough to warrant another deployment of crew. Although the outlook is dry, the conference calls will continue as usual.

- Martner

Project Status: 19 January 2006 (02 UTC)

Precipitation echoes have decreased substantially in the last hour. Therefore XPOL and SMART-R operations stopped at 01 UTC 19 January. This will be the declared end time of IOP 8.

Kingsmill

January 18, 2006

Project Status: 18 January 2006 (22 UTC)

Precipitation has become much more isolated over the last few hours. Radar echoes are mainly tied to the orography and are quite shallow, as one might expect in a post-frontal airmass. However, there is a band of slightly more widespread precipitation that is moving toward the American River Basin from the northwest. At its current rate of movement, it would arrive in about 3 hours if it stays intact. There is also the possibility that convective showers will start to initiate as a result of the cold air aloft and occasional rays of sunlight heating the surface.

The forecast suggests that precipitation will start to taper off after 00 UTC 19 January, with a more rapid drop-off after 06 UTC. Therefore, XPOL and SMART-R operations will continue to 00 UTC 19 January, at which point it will be up to the operators to determine when to shut the radars down.

Three-hourly Sloughhouse sounding operations have been successful since their initiation at 00 UTC 18 January. These operations will end at 00 UTC 19 January.

Given the low chance of significant precipitation during the next 4-5 days, it has been decided to recall the scanning radar crews back to their home bases.

Kingsmill

Project Status: 18 January 2006 (17 UTC)

Over the last couple hours, a few moderately intense bands of precipitation have propagated through our domain. At present, they have moved to the south and most all echoes are tied to the orography. Based on XPOL RHI's, a wedge of colder, drier air has moved into the Sierra foothills. These RHI's show elevated echo between Auburn and Colfax with lowering echo bases upslope from there. This is complemented by visual reports of cloud base at Auburn and Foresthill. Profiling radar data indicates lowering snow levels, now down to about 1.2 to 1.3 km MSL. Interestingly, there has not been a distinct bright band evident on XPOL RHI's during this recent period----earlier, during the passage of the moderately intense bands, strong bright band signatures were evident, with peak reflectivities of 45-50 dBZ.

Status: Dave and JJ repaired the SMART-R power problems. They resumed operations at about 17 UTC.

Kingsmill

Project Status: 18 January 2006 (14 UTC)

Precipitation continues for IOP 8. It was fairly steady in our target area through about 08-10 UTC, the tapered off a bit. Over the last hour or so, echo coverage has increased, but it is still relatively scattered. Snow levels did not continue decreasing overnight and have actually gone up slightly in a few profiles. There is an interesting trend of lower snow levels over the orography (1.4 to 1.5 km) compared to the central valley (1.7 to 1.8 km). This is seen from comparative examination of Sloughhouse and Chico profiler data with the Colfax and Alta profiling S-band data. XPOL has also shown this trend in more detail, with bright bands sometimes tilting downard with range as the beam gets closer to the terrain.

Status issue: SMART-R developed a power problem just before 06 UTC and stopped operating. The problem is not with the generator but with one of the electrical breakers that distributes power to the radar and associated components. For safety purposes, Dave and JJ are waiting for daylight to attempt further diagnosis and repair.

Kingsmill

Project Status: 18 January 2006 (05 UTC)

IOP 8 is underway. A moderately intense band of precipitation is passing through our target area at present. Liquid accumulations so far are about 0.15 to 0.25 inches. Snow levels are about 1.5 km. Snow is accumulating at Blue Canyon and chain requirements are in place along I-80 below Blue Canyon and just above Alta. It is likely that snow will be falling at Alta sometime before the night is through---we will have to monitor whether snow accumulates on the antenna of the S-band at that location.

XPOL began operations at about 0030 UTC 18 January. SMART-R began operations shortly thereafter, about 0040 UTC 18 January. Three-hourly sounding operations at Sloughhouse began at 00 UTC 18 January and are ongoing through 00 UTC 19 January.

Kingsmill

January 17, 2006

Project Status: 17 January 2006 (Tuesday, noon)

NWS has issued a winter storm warning for the western slopes of the northern Sierra for this afternoon to Wednesday afternoon. A cold front is expected to reach the ARB this evening, bringing a good shot of precip with it, to be followed tomorrow with more precip via good upslope forcing. See "Forecast" for details.

IOP-8 will begin at 00 UTC, 18JAN (4 pm today), with the first sounding from Slough House. Soundings will continue there for 24 hours. No sup[plemental soundings are needed from Oakland for this IOP. The ESRL and NSSL crews should arrive from Colorado and Oklahoma at the X-band and SMART-R research radars this afternoon. Data collection with those radars will begin between 4 and 6 pm PST this evening. The radar crews should expect 24-30 hours of continuous operations. The Beale AFB NEXRAD is expected to be back in VCP-12 by this afternoon.

In the longer term, a couple of weak showery "storms" may pass through the ARB on Friday-Sunday, but these look unimpressive in the forecasts now. Folks are getting dismayed by the ongoing trend for the atmospheric rivers of water vapor to dwindle in strength and organization over the Pacific Ocean.

Reminder: ESRL/GSD's high-resolution model forecast maps tailored to HMT are now available on-line on nicely imporved web pages which can be reached through the HMT-06 Project Web page. On the lower part of the left sidebar under "QPF" click on "High-Resolution Models".

- Martner

January 16, 2006

Project Status: 16 January 2006

The current forecast calls for precipitation to begin in the American River Basin on Tuesday afternoon and continue into Wednesday night / Thursday morning. QPF for this event has been increasing over the last couple of forecast cycles, with the current estimate in the 2-3 inch range. Snow levels for the event will start out around 6 kft and perhaps go down to as low as 3 kft, which would be lower than any of the previous systems that we have sampled. With these factors in mind, it has been decided to deploy crews to the area for operation of XPOL and SMART-R during the event. These crews will arrive late morning to early afternoon on Tuesday and should be able to start operations no later than 00 UTC 18 January (4 pm PST Tuesday).

We are opting not to request supplemental soundings from Oakland for this event. However, there will be sounding operations at Sloughhouse. The current plan calls for 3-hourly soundings to begin at 00 UTC 18 January and end at 00 UTC 19 January.

Status: There is a hardware problem with the Beale AFB WSR-88D (KBBX) that presently precludes transitioning the radar from its current clear-air VCP to VCP 12, the desired scan strategy for precipitation. The repair process is underway, but it is not clear whether the problem will be fixed for the upcoming IOP.

Kingsmill

January 15, 2006

Project Status: 15 January 2006 (22 UTC)

Our attention now focuses on the possibility of an IOP during the Tues-Wed-Thurs time frame of this upcoming week. Model guidance indicates that this system will likely be somewhat warmer (i.e., slightly higher snow levels) than the IOP7 event that just concluded. QPF for the upcoming event is likely to be in the 1.25 to 1.75 inch range for the ARB. Precipitation is likely to begin Tuesday night and continue into Wednesday night.

A decision on crew deployments for operation of XPOL and SMART-R will be made on Monday. It is unlikely that we will request Oakland supplemental soundings for this event. However, we are planning on executing sounding operations at Sloughhouse. The current thinking is that we will begin three-hourly sounding operations there at 03 UTC 18 January and conclude at 00 UTC 19 January.

Kingsmill

Project Status: 15 January 2006 (03 UTC)

Precipitation has tapered off considerably in the ARB. Also, scanning radar operations of XPOL and SMART-R have concluded. Will declare the end of IOP7 at 03 UTC 15 January.

Kingsmill

January 14, 2006

Project Status: 14 January 2006 (22 UTC)

The trough axis appears to be coming through the central valley at this time. There are radar echoes to the south of the ARB that may advect into our target area, but nothing much to the west or northwest. Echoes to the SW of our area appear to be propagating to the east or east-southeast. Precipitation totals in our domain are maximizing at about 0.8 to 1 inch of liquid. It appears that about 8 to 9 inches of snow has accumulated at Blue Cayon.

The forecast calls for activity to decline significantly after 03 UTC. Therefore, scanning radar operations will continue to at least 03 UTC. If there are echoes to scan in the ARB after this time, then continued operation of the radars will be at the discretion of the operators. Scanning radar crews will return to their home bases on Sunday.

Supplemental soundings from Oakland concluded at 21 UTC and the last Sloughhouse sonde will be at 00 UTC.

The next system to affect our target area is forecast to arrive early Wednesday morning. QPF for this event is not impressive, probably in the 0.5 to 0.75 inch range. It is unclear whether we will initiate a crew deployment for this event or ask for soundings (Sloughhouse or Oakland supplementals). Let's see how the model solutions evolve over the next day or so.

Status: Real-time data for the Colfax S-band is now updating again (started around 17 UTC)

Kingsmill

Project Status: 14 January 2006 (14 UTC)

Precipitation began in the American River Basin around 08 UTC. XPOL began operations just prior to this time. Presently, there is a moderately intense linear echo through the middle of the XPOL scanning domain. It appear to cut through Foresthill. Snow level appears to be variable. The Alta S-band indicates that it is around 2 km. However, the Blue Canyon surface met indicates that it is about 0 C. Also, the Blue Canyon NWS report indicates that snow is falling there.

Status issue: The Colfax S-band stopped updating on the real time page just before 00 UTC. This is being investigated.

Kingsmill

Project Status: 14 January (06 UTC)

Precipitation has not yet made it into our target area. Some more extensive echo is now coming onshore near San Francisco, but it is making very slow eastward progress. At this rate, I would not expect the precipitation to arrive in the American River Basin for another 5-6 hours, perhaps between 11-12 UTC. XPOL will likely start operating at 08 UTC in an autonomous mode through the night. It is my understanding that SMART-R started operating at 05 UTC and will continue to operate with a shift change sometime during the night.

Although precipitation has not yet started in our area, I will declare the beginning of IOP7 at 03 UTC since sounding operations started at that time.

Kingsmill

January 13, 2006

Project Status: 13 January 2006

The IOP7 precipitation event is still on track to affect the American River Basin starting tonight. However, there is a little uncertainty about exactly when the precipitation will begin to fall. The NAM suggests that the precipitation will begin by 00 UTC, but most of the other models indicate closer to a 06 UTC start. At present, radar echoes are making their way into the northern Sacramento valley, but their movement is more in line with a 06 UTC start to precipitation in the ARB. Therefore, XPOL and SMART-R should be on alert for starting operations by about 05 UTC (9 pm PST). All models are reasonably consistent in suggesting an end to precipitation on Saturday evening.

Sounding operations at Sloughhouse are still on track to begin at 03 UTC 14 January with 3-hourly releases through 00 UTC 15 January. Supplemental soundings at Oakland will be at 03, 06, 09, 15, 18 and 21 UTC 14 January.

The forecast models show that the next system (what might become IOP8) is now slated to arrive in our target area a little later (late Tuesday night into Wednesday morning) and be of shorter duration than our guidance from yesterday. For the moment, let's plan on scanning radar crews being on site Tuesday afternoon. However, we will have to see how this system evolves. If the recent trends continue, the system may slow further or not even make landfall in our target area. We will probably not discuss possible sounding operations for this event until Sunday.

Status:

The Point Piedras Blancas 915 MHz profiler is showing signs of a possible malfunction. In particular, the winds it has been producing look erroneous. ESRL staff are in the process of trying to diagnose and repair the problem.

Kingsmill

January 12, 2006

Project Status: 12 January 2006

The current forecast calls for precipitation to begin in our target area around 03-06 UTC 14 January. Crews for operating XPOL and SMART-R during this upcoming IOP (IOP 7) are already in Auburn and should be ready to begin operating the radars on Friday evening. A more refined estimate on initiation of radar operations will be provided during the Friday coordination call. Precipitation should increase in intensity over Friday night into Saturday. By Saturday afternoon/evening, there will likely be a transition to post-frontal showery type of precipitation. At present, the end of scanning radar operations is not certain; it may be Saturday evening or possibly Sunday morning. However, scanning radar operations will continue no longer than 18 UTC Sunday, so that the radar crews can catch flights back to their home bases.

In terms of sounding operations, Oakland supplementals have been requested for 03,06,09,15,18 and 21 UTC 14 January. At Sloughhouse, current plans call for three-hourly soundings from 03 UTC 14 January to 00 UTC 15 January.

The next precipitation event for the American River Basin is likely to affect the area starting Tuesday. Specific timing of the event is not yet certain, so it is too early to specify timing of sounding operations or when scanning radar operations will need to commence. Hopefully, timing issues for this event will become more clear on Friday.

Status issues:

1. The Sloughhouse profiler is back online after repairs by ESRL staff
2. Surface meteorology data from Foresthill (FHL) is now online (the telephone line to the site was just activated after a lengthy delay). Data from this site has been recorded since the beginning of December.
3. Profiler and surface meteorology data from Point Piedras Blancas (PPB) is now online, but satellite communications are still somewhat unstable. Therefore, there may be occasional data voids in the time series.


Kingsmill

January 11, 2006

Project Status: 11 January 2006

11 January 14Z: IOP6 Status

The SMART-R began operations at 4:45 PM (PST) 10 Jan (0045 UTC 11 Jan). The ETL X-band radar began recording data at 7:53 PM. The first Slough House sounding was at 00Z or 4:00 PM (PST). Therefore, the start of IOP6 will be 4 PM or 00 UTC 11 January 2006.

As of 6 AM this morning, Blue Canyon had received 0.22 inches of precip.

As of the time of the conference call (1930 UTC) the rain had tapered off in the ARB. IOP6 will end as of 1 PM PST.

The next workable event looks like it will start by 06 UTC Saturday 14 January 2006 (10 PM PST Friday night). There is some chance, however, that the synoptic low will cutoff off the coast in which case the low-level flow would not have much of an upslope component and the precip would not make it far up the ARB. A go/no go decision will be made at Friday's conference call.

Jorgensen

January 10, 2006

Project Status: 10 January 2006

IOP6 is slated to begin this evening when the radar crews get their radars running, but no later that 10 PM PST. Zonal flow today brings a nice surge of vapor on west winds increasing to 25-30 kt overnight. Precip water amounts are over an inch during the precipitation period, which appears to start after dark and continue until midday tomorrow according to the NAM model - the GFS model holds on to precip until sundown. Snow level starts out around 9000 ft, lowers to around 7500 ft by the end of the event. Total model precipitation amounts .5 to 1.0 inches.

Supplementary soundings from OAK are slated to start at 03Z Wednesday and continue to 21 Z Wednesday. The Slough House sounding site will launch 3 hourlies starting at 00Z Wednesday to 00Z Thursday, but may be continued one more cycle at 03Z if students can do it and the precip holds out.

Next event starts Friday afternoon. Sharp, fast-moving trough moves in, strong warm advection ahead of it, 850mb winds southerly at 35+ kt bring precipitable water amounts around 1 inch. Precipitation amounts not large (.5 inch) before warm advection gives way to cold advection after dark Friday. Strong cold advection and frontogenesis in predawn hours appear to cause greatest precipitation rates, 1 inch in 6 hrs ending sunrise. Total precip 1.5 to 2 inches, event ends late Saturday night.

The next event following the Saturday storm looks to start the following Tuesday morning (Jan. 17). There will be a change of crews for the SMART-R following the Friday/Saturday event and new crews are alerted for possbile departure on Monday for operations beginning Tuesday morning.

JORGENSEN


Status of HMT Instrument Problems:

The New Years' storms caused problems for various HMT instruments and we are working hard to recover from that hit. Some, such as the surface met stations at Chico and Slough House, have recently been fixed and are back on line. Many of the problems are associated with the communications links; data are being recorded but not displayed in realtime. Other instruments have comm link problems that pre-date the New Years storms. As of this morning, the following HMT sites do not have realtime display of data on the project Web page, but all are being worked on, as shown.

BBY - 915, 449 profilers, sfc met (no realtime display since 1JAN06);
a new phone line is supposed to be installed there early this week.
SHS - 915 profiler (down since 1JAN06);
Jesse Leach will install the repaired transmitter there on Friday.
CFC - S-band profiler, sfc met, disdrometer, hotplate (no realtime display since 6JAN06);
Clark King will be there Wednesday to assess the problem.
PPB - 915 profiler, sfc met (has never been available for realtime display this winter);
Scott Abbott has recovered from surgery and will install a new satellite-comm system there on Wednesday.
FHL - sfc met (has never been available for realtime display this winter);
the small local phone company must install a phone line - we keep pushing them to do it.

As soon as data from any of these sites starts flowing into Boulder, Dave White will get them into the data system and available for realtime display through the HMT-06 web page.

- Martner

January 09, 2006

Project Status: 9 January 2006

The QPF forecast looks good enough to declare the start of IOP6 tomorrow (Tuesday Jan. 10), no later than 10 PM PST. Radar crews will depart tomorrow (Tuesday) and try to get their radars up and running as soon as possible following arrival, but no later than 10 PM PST.

The NAM model is predicting a fairly good event but starting things a bit earlier than the GFS with precipitation commencing Tuesday morning (Jan 10 15 GMT). During the warm advection period the NAM handles the arrival of the moist plume and upslope with more detail predicting 0.7 inches prior to the frontal passage by 08Z on Wednesday. With the front and low static stability predicted by the NAM, there could be some embedded convective cells. The NAM forecasts 1.5 inches at and following the front. So a 2-inch + event is in the offing. Freezing levels are high for this storm starting out at 8000ft and decending to 6500ft., so mostly a rain event.

Supplementary soundings from OAK are slated to start at 03Z Wednesday and continue to 21 Z Wednesday. The Slough House sounding site will launch 3 hourlies starting at 00Z Wednesday to 00Z Thursday.

The next event would be Saturday. At this point the GFS has a major full latitudinal trough reaching the coast with a deep cold front moving through the ARB. Precipitation really doesn’t get going until after frontal passage, so it is predicted to be a cold advection-dominated event. Peak precipitation looks to be mid-day Saturday. A decision on this event, it would be designated IOP7, (i.e., to hold crews over) will be made by Wednesday afternoon.

JORGENSEN.

January 08, 2006

Project Status: 8 January 2006

A shortwave ridge is affecting the ARB today so the skies are clearing. No IOPs will be declared in the next few days.

We've been watching two potential systems in the medium range progs and ensembles: one on Wednesday (Dec. 11) and another on Saturday (Dec. 14). Model runs are beginning to settle down and fall into agreement that about 1" of precip will fall in the ARB from about 06Z to 18 Z on Wednesday (10 PM PST Tuesday to 10 AM PST Wednesday). The GFS, ECMWF, CMC, NOGAPS, UKMET predict that that the Wednesday event is stronger and more consolidated than yesterday’s forecasts. The GFS brings in an IPW plume (with offshore values of 35mm), with values of  24mm into the San Jaoquin Valley during the period of warm advection (10/18Z to 11/09Z). Heaviest precipitation is predicted Wednesday mid-day (11/12-18GMT)…about a half an inch. Freezing levels will start at about 8500ft and drop to 5500 ft by the end of the event

The Saturday system looks less impressive than yesterday, but the ensembles still have considerable variance. A decision on crew deployment for the Wednesday system will be made no later than Tuesday, and hopefully Monday.

January 07, 2006

Project Status: 7 January 2006

The expected shortwave this morning is producing only minor precipitation over the ARB. In the last 6 hours, ending 11 AM PST, Blue Canyon received 0.03 inches of precip. With the flattening of the ridge several waves will continue to produce light precip in the ARB today and tonight. No IOPs will be declared in the next few days for these weak systems.

We've been watching two potential future systems in the medium range progs and ensembles: one on Wednesday (Dec. 11) and another on Saturday (Dec. 14). Althought the Wednesday system has an impressive IPW flux into Northern California, the main flow dynamics has shifted northward in the most recent GFS run as the West Coast ridge starts to return. If this verifies, the ARB would receive only light precipitation on Wednesday night. The Saturday system looks stronger but the ensembles have considerable variance. A decision on crew deployment for the Wednesday system will be made no later that Tuesday, and hopefully Monday.

JORGENSEN

January 06, 2006

Project Status: 6 January 2006

Ridging is now dominating the west coast. No IOPs are planned in the next few days. A shortwave is forecasted to be on the coast by early Saturday (Dec 7 - 08 GMT) which begins the breakdown of the ridge over the western US. As the ridge flattens higher speed zonal flow impacts the west coast and shortwaves can be more effective in producing orographic-enhanced precip.

Two waves of interest will move into central California in the near term: one on Wednesday (Dec. 11 - 18 GMT) and another on Saturday (Dec. 14 - 12GMT). There is potential for both these systems to produce significant precip over the ARB. The earliest a crew alert will be given will be next Monday for possible IOP beginning early Wednesday. However, considerable uncertainty exists in the forecasts, as shown by the wide spread of the ensemble members. The GFS is currently indicating that the Weds. event could be a wet one if it verifies with 1-2 inches of precipitation beginning with a well defined IPW plume with values 40mm off shore and 30-35mm working into the San Joaquin Valley. These next two events likely will be colder than events sampled in December with the freezing level descending to perhaps 4500 ft over the ARB.

JORGENSEN

January 05, 2006

Project Status: 5 January 2006

Light precip continues over the ARB last night. As of 12 Z this morning, Blue Canyon station got an additional 24 h total of 0.11 inches. No IOPs are anticipated during this weak ridging period over the ARB. The ridge begins to flatten starting today culminating in a short wave trough that impacts the ARB on late Friday (6/06GMT) and Saturday. GFS supports a cold frontal passage late Friday. Unfortunately there isn't much water vapor with this system, so the significant precipitation likelihood is low. Consequently, there will be no IOP declared for this system.

A much better chance for significant precip over the ARB occurs next Wednesday. After a brief period of upslope starting early Wednesday morning a cold front pushes through the ARB and the heaviest precipitation appears to be post frontal, thus cold advection dominates. This may be a good rain to snow transition event with the freezing level dropping from 8500ft to 4000ft during the event.

If this scenario holds true crews would be alerted for deployment next Tuesday for radar and sounding operations beginning early Wednesday through perhaps mid-day Thursday.

JORGENSEN

Project Status: 4 January 2006

There is still light precipitation falling in the ARB from a weak system overnight. As of 12Z this morning Blue Canyon had received a 24 h total of 0.32 inches. It is expected that continued precip will be relatively light and is mostly to the north of the ARB. Radar and sounding crews will not be alerted for this sequence of weak systems. However, the autonomous observing systems in our domain are operational.

The longer range forecast calls for more northward storm tracks with northern California possibly affected by the southern extent and trailing cold fronts of these systems. In the longer range (day 2-5) relatively flat ridging offshore may bring a return of significant precip to the ARB, although the ensembles indicate considerable uncertainty about the exact timing and precipitation amounts.

JORGENSEN

January 03, 2006

Project Status: 3 January 2006

Precipitation falling in northern California today will be relatively light and is mostly to the north of our target area. As a result, we will not intensively sample the event with XPOL or SMART-R. However, the autonomous observing systems in our domain will be poised to monitor its evolution.

The longer range forecast calls for the storm track to head northward, with Oregon and Washington getting most of the precipitation, with northern California possibly affected by the southern extent of these systems. At present, numerical guidance suggests that the southern extent of these systems is not likely to influence the American River Basin. However, if the models are overdoing the relatively flat ridge offshore (a bias evident over the last week or so), these systems may sag far enough southward to bring precipitation to our area.

Kingsmill

January 02, 2006

Project Status: 2 January 2006 (21 UTC)

Precipitation will be winding down in our target area after 00 UTC, so we will end IOP 5 at 00 UTC 3 January. The last of the 3-hourly Sloughhouse soundings will be released at 3 pm PST. XPOL and SMART-R operations will end at 00 UTC. The last Oakland supplemental (21 UTC) is currently in flight.

Weather during the rest of the week may involve some light precipitation from systems centered well to the north of our area. However, the dominant weather for the week is more likely to be relatively dry. Therefore, XPOL and SMART-R crews will be recalled to their home bases. Long -range models indicate that a more significant system may affect our area next weekend and into early next week. We will be watchful over the coming days.

Kingsmill

Project Status: 2 January 2006 (18 UTC)

Overnight, precipitation in the American River Basin decreased to almost nothing. However, radar echoes starting moving back into our area around 12 UTC. Precipitation accumulation at Blue Canyon is now just under 2 inches for the IOP. XPOL has been operating continuously since it started around 21 UTC yesterday. SMART-R ceased operations around 09 UTC, but has recently resumed (~15 UTC) to capture the new wave of precipitation. Snow levels are descending, now down to about 1.5 km.

The power situation at Sloughhouse stabilized yesterday evening to allow commencement of sounding operations at 03 UTC (6 pm release). Three-hourly releases have been made since then. Unfortunately, many of the soundings have failed prematurely due to GPS issues (no reported porpoising as of yet). The problem is believed to be associated with the GPS sounding system that we are using---a replacement sounding system is being shipped to the site for use in subsequent IOP's. Three-hourly supplemental soundings at Oakland are continuing---the last supplemental is scheduled for 21 UTC.

As of now, radar echoes in our target area do not show signs of dissipating, so we should plan on operating into the afternoon. A 00 UTC 3 January IOP end time still seems like a good bet, but this will be discussed during the upcoming coordination call.

Kingsmill

Project Status: 2 January 2006 (06 UTC)

Precipitation continues to fall in our domain. Blue Canyon has had about an inch since 20 UTC 1 January. Snow levels are around 2 km based on profiling radar data at Colfax and Alta. KDAX radar echoes are trending toward more of an orographic pattern at this time. The more widespread echoes are further south toward Monterey and Fresno.

Some status updates:

SMART-R starting operations on Sunday at about 1 pm PST (20 UTC 1 January) and will continue through the night

There have been commercial power disruptions at the Sloughhouse field site which have hampered sounding operations this afternoon/evening. At this time, do not know if any lauches have been attempted yet. However, the bigger issue at Sloughhouse is the fact that exceptionally strong winds this afternoon flipped over the 915 MHz profiler and knocked down the suface meteorology tower. Damage to many components was sustained. Thankfully, no one at the site was hurt as a result of the incident. Engineering staff will be coming to the site Tuesday or Wednesday to investigate and attempt repair.

Surface meteorology data from the Alta field site is not updating on the HMT Network page. It is suspected that a data communication problem is the cause. The problem will be investigated further on Monday.

Kingsmill

January 01, 2006

Project Status: 1 January 2006 (22 UTC)

Light precipitation began falling in our domain around 20 UTC. Areal extent and intensity has increased slightly over the past couple hours. Will declare beginning of IOP5 at 21 UTC 1 January. Precipitation should continue in our domain through the night and into Monday afternoon (perhaps evening). Expect IOP5 to last until 00 UTC 3 January. Here are some status updates:

XPOL began operating today at around 2030 UTC.

Unsure of SMART-R status since I have been unable to contact Ken Howard.

Oakland supplemental soundings will begin at 03 UTC 2 January and continue in 3-hourly release mode through 21 UTC.

Sounding operations at Sloughhouse are scheduled to begin with a 3 pm PST release. However, power at the site is down at present, which may delay the first launch. Plans call for 3-hourly sounding operations to continue through tonight and into Monday.

Kingsmill