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RE: RTMA temperatures near Page, Arizona

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AT
Andrew Taylor, modified 6 Years ago.

RTMA temperatures near Page, Arizona

Youngling Posts: 3 Join Date: 9/24/12 Recent Posts
Hi all,

A concern was brought up at our morning briefing that temperatures for Page, Arizona were being underforecast.  Many of our staff regularly populate temperature grids with the NBM, and that is what was used on the mid shift.  Looking more closely, the temperature forecast at the grid points directly over Page appear to be reasonable.  There is a grid point just east of Page, as well as grid points farther to the north and east, that are as much as 10-12 degrees F cooler.  This same effect is happening in the RTMA/URMA.  I'm guessing it's trying to capture influence on temperatures from Lake Powell.

Though the only observing station nearby is the Page ASOS which is not right next to the lake, I'm somewhat doubtful the lake is having this much influence on MaxT, especially along the narrow portions of the lake in Arizona.  We've had several hot days in the Lake Powell area this summer, and a mix of grid points like this can make interpretation difficult when deciding on issuing heat warnings/advisories.  It also could be confusing if residents of the Page area click ever so slightly away from the city; they may get a drastically different forecast.  This is a popular recreation area on both the Arizona and Utah sides, with many owning houseboats.  It's important that those spending time at Lake Powell have as accurate a temperature forecast as possible.

The influence on MinT's is not nearly as much, not this time of year.  Looking back at the winter, the influence of the lake shows up in the RTMA/URMA MinT grids.  Thank you in advance for taking a look at this.

Andy

Andrew Taylor
Science and Operations Officer
National Weather Service Flagstaff
(928) 556-9161 x 224
http://weather.gov/flagstaff


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Jeffrey Craven, modified 6 Years ago.

RE: RTMA temperatures near Page, Arizona

Youngling Posts: 90 Join Date: 9/24/12 Recent Posts
Andy, do you have anyone that could take some air temperature measurements over the lake?  How about a local lake “patrol”?  

Would be interesting to get some estimates during the afternoon.

Differences of 5-8F seem reasonable.

JPC

On Mon, Aug 13, 2018 at 2:30 PM VLab Notifications <VLab.Notifications@noaa.gov> wrote:
Hi all,

A concern was brought up at our morning briefing that temperatures for Page, Arizona were being underforecast.  Many of our staff regularly populate temperature grids with the NBM, and that is what was used on the mid shift.  Looking more closely, the temperature forecast at the grid points directly over Page appear to be reasonable.  There is a grid point just east of Page, as well as grid points farther to the north and east, that are as much as 10-12 degrees F cooler.  This same effect is happening in the RTMA/URMA.  I'm guessing it's trying to capture influence on temperatures from Lake Powell.

Though the only observing station nearby is the Page ASOS which is not right next to the lake, I'm somewhat doubtful the lake is having this much influence on MaxT, especially along the narrow portions of the lake in Arizona.  We've had several hot days in the Lake Powell area this summer, and a mix of grid points like this can make interpretation difficult when deciding on issuing heat warnings/advisories.  It also could be confusing if residents of the Page area click ever so slightly away from the city; they may get a drastically different forecast.  This is a popular recreation area on both the Arizona and Utah sides, with many owning houseboats.  It's important that those spending time at Lake Powell have as accurate a temperature forecast as possible.

The influence on MinT's is not nearly as much, not this time of year.  Looking back at the winter, the influence of the lake shows up in the RTMA/URMA MinT grids.  Thank you in advance for taking a look at this.

Andy

Andrew Taylor
Science and Operations Officer
National Weather Service Flagstaff
(928) 556-9161 x 224
http://weather.gov/flagstaff



--
Andrew Taylor RTMA/URMA Discussion Group Virtual Lab Forum http://vlab.noaa.gov/web/715073/home/-/message_boards/view_message/4623670 VLab.Notifications@noaa.gov
--
Jeff Craven
Chief, Statistical Modeling Branch
National Weather Service, W/STI-12
Meteorological Development Laboratory (MDL)
Room 10410, SSMC2
Silver Spring, MD 20910
(301) 427-9475 office
(816) 506-9783 cell/text
@jpcstorm
AT
Andrew Taylor, modified 6 Years ago.

RE: RTMA temperatures near Page, Arizona

Youngling Posts: 3 Join Date: 9/24/12 Recent Posts

Hi Jeff,

 

We could contact Glen Canyon NRA and see if anyone up there has the ability to collect air temperature measurements over/near the lake.  Perhaps someone at Wahweap (the 89 F grid point near the Utah state line).  I agree with you that over the wider/deeper parts of the lake it makes sense that there is some influence from the water on the air temperature.  I'm somewhat surprised at the magnitude of the influence (often 10-14 degrees).  We are also concerned about grid points which seem to be heavily influenced by water but, in reality, don't have much water in them.  The grid point east of Page (91 F in the image is the Page Airport ASOS, so the lake shapefile is a bit overdone) is almost completely land, but has a temperature almost 7 F cooler than the grid point to the west.  This grid point also contains lower Antelope Canyon, another popular tourist attraction which is entirely slick rock.

 

At the very least, would it be possible at some point to change the classification of some of the "water" grid points immediately north/east of Page to "land"?  That might take care of a majority of the issues.  I'll keep you posted on what I can dig up regarding lake/near lake air temperature readings.


Thanks,

Andy

Jeffrey Craven, modified 6 Years ago.

RE: RTMA temperatures near Page, Arizona

Youngling Posts: 90 Join Date: 9/24/12 Recent Posts
Was this grid point preference indicated in the Unified Terrain? We have had several iterations of the Unified Terrain to account for items like this, which are coordinated with the EMC/URMA folks and the regions. 

I would recommend making requests like this through your RH.    Updates to Unified Terrain should only be every 1-3 years but at least you can get it into the que.

JPC

On Mon, Aug 13, 2018 at 6:15 PM VLab Notifications <VLab.Notifications@noaa.gov> wrote:

Hi Jeff,

 

We could contact Glen Canyon NRA and see if anyone up there has the ability to collect air temperature measurements over/near the lake.  Perhaps someone at Wahweap (the 89 F grid point near the Utah state line).  I agree with you that over the wider/deeper parts of the lake it makes sense that there is some influence from the water on the air temperature.  I'm somewhat surprised at the magnitude of the influence (often 10-14 degrees).  We are also concerned about grid points which seem to be heavily influenced by water but, in reality, don't have much water in them.  The grid point east of Page (91 F in the image is the Page Airport ASOS, so the lake shapefile is a bit overdone) is almost completely land, but has a temperature almost 7 F cooler than the grid point to the west.  This grid point also contains lower Antelope Canyon, another popular tourist attraction which is entirely slick rock.

 

At the very least, would it be possible at some point to change the classification of some of the "water" grid points immediately north/east of Page to "land"?  That might take care of a majority of the issues.  I'll keep you posted on what I can dig up regarding lake/near lake air temperature readings.


Thanks,

Andy


--
Andrew Taylor RTMA/URMA Discussion Group Virtual Lab Forum https://vlab.noaa.gov/web/715073/discussions-forums-/-/message_boards/view_message/4624664 VLab.Notifications@noaa.gov
--
Jeff Craven
Chief, Statistical Modeling Branch
National Weather Service, W/STI-12
Meteorological Development Laboratory (MDL)
Room 10410, SSMC2
Silver Spring, MD 20910
(301) 427-9475 office
(816) 506-9783 cell/text
@jpcstorm
JC
Jacob Carley, modified 6 Years ago.

RE: RTMA temperatures near Page, Arizona

Youngling Posts: 69 Join Date: 12/17/14 Recent Posts
Hi Andy,

In addition to the points that Jeff has already raised I wish to note that the RTMA/URMA development team is aware of these lake temperature issues.  Similar comments have been expressed in the past from other WFOs as well.

This is a complex issue as in-situ data is often lacking, the lakes themselves are often only partially resolved at 2.5 km, if at all (and that's stretching that a bit at times).  Furthermore - we don't capture the diurnal variation in shallow lakes.  This is just a short list - but if you look through some prior discussion on this listserv you'll see the topic comes up so I won't list everything again here.

Here's where we're at now: the development team is now beginning a project with NESDIS to improve lake temps via the use of satellite-derived temperatures.  In addition to this we're considering including a lake parameterization/model in future convective scale model implementations (i.e. FV3-based CAM system).  We're at the early stages here and thus a bit light on the details, and this will take time, but we're moving in a good direction.

Thanks,
Jacob [RTMA Project Lead]

On Mon, Aug 13, 2018 at 6:58 PM, VLab Notifications <VLab.Notifications@noaa.gov> wrote:
Was this grid point preference indicated in the Unified Terrain? We have had several iterations of the Unified Terrain to account for items like this, which are coordinated with the EMC/URMA folks and the regions. 

I would recommend making requests like this through your RH.    Updates to Unified Terrain should only be every 1-3 years but at least you can get it into the que.

JPC

On Mon, Aug 13, 2018 at 6:15 PM VLab Notifications <VLab.Notifications@noaa.gov> wrote:

Hi Jeff,

 

We could contact Glen Canyon NRA and see if anyone up there has the ability to collect air temperature measurements over/near the lake.  Perhaps someone at Wahweap (the 89 F grid point near the Utah state line).  I agree with you that over the wider/deeper parts of the lake it makes sense that there is some influence from the water on the air temperature.  I'm somewhat surprised at the magnitude of the influence (often 10-14 degrees).  We are also concerned about grid points which seem to be heavily influenced by water but, in reality, don't have much water in them.  The grid point east of Page (91 F in the image is the Page Airport ASOS, so the lake shapefile is a bit overdone) is almost completely land, but has a temperature almost 7 F cooler than the grid point to the west.  This grid point also contains lower Antelope Canyon, another popular tourist attraction which is entirely slick rock.

 

At the very least, would it be possible at some point to change the classification of some of the "water" grid points immediately north/east of Page to "land"?  That might take care of a majority of the issues.  I'll keep you posted on what I can dig up regarding lake/near lake air temperature readings.


Thanks,

Andy


--
Andrew Taylor RTMA/URMA Discussion Group Virtual Lab Forum https://vlab.noaa.gov/web/715073/discussions-forums-/-/message_boards/view_message/4624664 VLab.Notifications@noaa.gov
--
Jeff Craven
Chief, Statistical Modeling Branch
National Weather Service, W/STI-12
Meteorological Development Laboratory (MDL)
Room 10410, SSMC2
Silver Spring, MD 20910
(301) 427-9475 office
(816) 506-9783 cell/text
@jpcstorm

--
Jeffrey Craven RTMA/URMA Discussion Group Virtual Lab Forum http://vlab.noaa.gov/web/715073/home/-/message_boards/view_message/4624897 VLab.Notifications@noaa.gov

SL
Steven Levine, modified 6 Years ago.

RE: RTMA temperatures near Page, Arizona

Youngling Posts: 174 Join Date: 11/13/14 Recent Posts
I see Jacob beat me to the punch on this...I'll try to save you a bit of archive-searching...

These sort of issues (cooler daytime temps over smaller inland lakes) almost always originate with the HRRR forecast we use as a background/first guess, and that appears to be the case here as well - see attached panel plot showing first guess vs analysis values for the maxT analysis yesterday.  Note that since the ob over Page was very close to the background temperature at that point, the background/analysis difference is less than 2 F - not enough to show up with the colorbar used on the viewer.

It is worth noting that the land/water influence wall for obs we use in RTMA/URMA does not apply over these small inland lakes, however the higher terrain around the lake would keep it relatively confined..  I suspect that even if obs were available over the lake, this would warm temps over the lake but also further warm the land area around the lake, including over Page itself.  The high land/water temperature difference would remain.

As Jacob mentions, I think the ultimate solution is improving temperature forecasts in our high-res/convective-allowing modeling systems.

Steve

On Mon, Aug 13, 2018 at 6:58 PM, VLab Notifications <VLab.Notifications@noaa.gov> wrote:
Was this grid point preference indicated in the Unified Terrain? We have had several iterations of the Unified Terrain to account for items like this, which are coordinated with the EMC/URMA folks and the regions. 

I would recommend making requests like this through your RH.    Updates to Unified Terrain should only be every 1-3 years but at least you can get it into the que.

JPC

On Mon, Aug 13, 2018 at 6:15 PM VLab Notifications <VLab.Notifications@noaa.gov> wrote:

Hi Jeff,

 

We could contact Glen Canyon NRA and see if anyone up there has the ability to collect air temperature measurements over/near the lake.  Perhaps someone at Wahweap (the 89 F grid point near the Utah state line).  I agree with you that over the wider/deeper parts of the lake it makes sense that there is some influence from the water on the air temperature.  I'm somewhat surprised at the magnitude of the influence (often 10-14 degrees).  We are also concerned about grid points which seem to be heavily influenced by water but, in reality, don't have much water in them.  The grid point east of Page (91 F in the image is the Page Airport ASOS, so the lake shapefile is a bit overdone) is almost completely land, but has a temperature almost 7 F cooler than the grid point to the west.  This grid point also contains lower Antelope Canyon, another popular tourist attraction which is entirely slick rock.

 

At the very least, would it be possible at some point to change the classification of some of the "water" grid points immediately north/east of Page to "land"?  That might take care of a majority of the issues.  I'll keep you posted on what I can dig up regarding lake/near lake air temperature readings.


Thanks,

Andy


--
Andrew Taylor RTMA/URMA Discussion Group Virtual Lab Forum https://vlab.noaa.gov/web/715073/discussions-forums-/-/message_boards/view_message/4624664VLab.Notifications@noaa.gov
--
Jeff Craven
Chief, Statistical Modeling Branch
National Weather Service, W/STI-12
Meteorological Development Laboratory (MDL)
Room 10410, SSMC2
Silver Spring, MD 20910
(301) 427-9475 office
(816) 506-9783 cell/text
@jpcstorm

--
Jeffrey Craven RTMA/URMA Discussion Group Virtual Lab Forum http://vlab.noaa.gov/web/715073/home/-/message_boards/view_message/4624897VLab.Notifications@noaa.gov

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AT
Andrew Taylor, modified 6 Years ago.

RE: RTMA temperatures near Page, Arizona

Youngling Posts: 3 Join Date: 9/24/12 Recent Posts

Ah, yes.  I've attached a HRRR forecast T grid for 20Z today for the Page area.  Looks like a familiar pattern.  I do now remember this HRRR lake temperature issue coming up previously.  Thanks, all, for jogging my memory and for sharing such helpful information about future plans for improvements.

 

Just for curiosity's sake...I called the Wahweap Marina on Monday afternoon.  The temperature was 98 F at 335 pm (near the lake but not right on the shore), while RTMA (HRRR-influenced cool grid point) analyzed 91 F.  The temperature in Page was 100 F.  Unfortunately, they hadn't collected any air temperature data from over the lake.  They did say the water temperature is 80 F.

 

Thanks again for your help and your responsiveness.  You make an outstanding team.

 

Andy

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DV
Darren Van Cleave, modified 6 Years ago.

RE: RTMA temperatures near Page, Arizona

Youngling Posts: 37 Join Date: 1/8/14 Recent Posts

Thanks to Andy for bringing this up! We at SLC share Andy's concern of users happening to click on the "wrong" point around lake Powell and getting a forecast that does not represent the heat threat there. We are using the RTMA/URMA as the background for MatchObsAll, so this effect does find its way into our official forecasts. Of course it also shows up there when the NBM is used. I found the average difference between the pixels that the HRRR thinks are the lake vs. non lake are 8-12° in both our forecasts and the NBM.

I attached some screenshots from today's MaxT (8/15). Hopefully they will find their way into the VLAB thread.

First is an overall map of the area, area.png. The state boundaries (which happen to divide WFO Flagstaff and Salt Lake in this area) are the thick lines. 

Next is a zoomed-in look at our official forecast, i.e. what we're sending out to the public, publicForecast.png. Note the large differences of up to 12°. Flagstaff's points have the update time appended to the sample point.

For reference, here is our local bias correction consensus from all models (using RTMA/URMA as the background for BC'ing), BCCONSAll.png.

And here is the NBM ver 3.0, NBM3p0.png.

I'm cc'ing our WCM in case he has any contacts who could get some ground truth on the temperature difference. 

On Wed, Aug 15, 2018 at 11:48 AM, VLab Notifications <VLab.Notifications@noaa.gov> wrote:

Ah, yes.  I've attached a HRRR forecast T grid for 20Z today for the Page area.  Looks like a familiar pattern.  I do now remember this HRRR lake temperature issue coming up previously.  Thanks, all, for jogging my memory and for sharing such helpful information about future plans for improvements.

 

Just for curiosity's sake...I called the Wahweap Marina on Monday afternoon.  The temperature was 98 F at 335 pm (near the lake but not right on the shore), while RTMA (HRRR-influenced cool grid point) analyzed 91 F.  The temperature in Page was 100 F.  Unfortunately, they hadn't collected any air temperature data from over the lake.  They did say the water temperature is 80 F.

 

Thanks again for your help and your responsiveness.  You make an outstanding team.

 

Andy


--
Andrew Taylor RTMA/URMA Discussion Group Virtual Lab Forum https://vlab.noaa.gov/web/715073/home/-/message_boards/view_message/4636097VLab.Notifications@noaa.gov



--
Darren Van Cleave
Science and Operations Officer
NWS Salt Lake City
(801) 524-5196
weather.gov/slc | @NWSSaltLakeCity

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  • 2011 RTMA Paper (Weather and Forecasting)

    The most recent peer-reviewed paper on the RTMA. Published in Weather and Forecasting in 2011.
    7 Visits

  • Public RTMA/URMA Viewer

    Another viewer of the current RTMA/URMA, with an archive going back 24 hours. This version is open to the public, but does not contain information about the (many) restricted obs used.
    54 Visits

  • RAP downscaling conference preprint (23rd IIPS)

    This link is to a presentation from the (then) RUC group on how the downscaling process works. Although we now use the RAP, HRRR, and NAM, the logic of the downscaling code is mostly unchanged from this point.
    2 Visits