Mesoscale Analysis in Des Moines

GOES-16 upper-level water vapor imagery reveals a closed upper low advancing east across southern Nebraska early this afternoon.

Visible imagery shows low clouds across much of the CWA, with cu beginning to develop across the far southern portions in the warm sector of the storm system

Morning GOES-16 Derived Motion Winds revealed a 110+ knot 300 mb southwest to northeast oriented jet core across Iowa. This agrees with the GFS depiction of the jet in that area, which has that jet exiting and a jet entrance region poking into southern Iowa later today. Winds in the 750 mb to 850 mb layer are generally 15-25 knots from the south/southeast, with slightly stronger winds advancing towards our south implying increasing LL WAA.

The default LAP products have very little data given low cloud cover over the region.  However, the all-sky LAP products have a lot of cloudy sky retrieval pixels, filling in those gaps, in addition to some clear sky pixels moving north into the CWA. From 1730 to 1900, all sky LAP CAPE has increased from 500 to 700 j/kg, and TPW has increased from around 1.32" to 1.36". CAPE over 1000 j/kg reside just south of our warning area. These trends imply the atmosphere is becoming more favorable for the development of severe storms.

 The LAP Layer PW product, comprised mostly of clear sky and cloudy sky retrievals across the domain, shows some significant features. Clockwise from top left PW sigma layers: sfc - 0.9, 0.9 - 0.7, TPW, 0.7 - 0.3. The two lower layers show fairly high levels of moisture, while the upper level reveals a nose of dryer air advancing toward the CWA. This trend would imply increasing convective instability as we advance through the afternoon.

- Bucky

OUN Mesoscale Analysis

GOES-16 water vapor imagery reveals a broad closed mid-level low advancing into the 4-corners region with energy rounding the eastern side of the trough through west Texas.

GOES-16 Derived Motion Winds show the southwest to northeast oriented upper-level jet shifting east into west Texas, OK panhandle, and western Kansas. Diffluent flow is apparent in the winds over south-central Kansas into the Texas panhandle on the east side of the jet where convection is already ongoing and initiating. As the upper forcing shifts east, so will the convection. Given the high cloud cover, mid-level winds are not available over the region. Winds in the 850 mb to 950 mb layer are available over much of central Oklahoma, indicating 25-35 knot low level southerly flow advecting moisture into the region. Some of the lowest level winds, below 950 mb, are indicating more backing toward south-southeast, which would imply a favorable shear environment for supercell thunderstorms.

Given the cloud cover, the LAP fields have very limited data across much of OUN. However, the all-sky product does have many cloudy sky pixels, a benefit of this product over the operational LAP product. Within these pixels, CAPE ranges from 1500 to 2000 j/kg across the CWA a reduction of close to 1000 j/kg over the GFS first guess. SPC meso-analysis indicates MLCAPE between 2500 and 3000 j/kg, implying LAP CAPE is too low. Boundaries are not easily identified in the retrieval data given the cloud cover.

MetOp-A NUCAPS soundings were available over the region for the 1630 UTC pass. The surface was adjusted to match the conditions present in the NWS Norman special 18Z sounding (surface of 78F T and 68F Td). Comparing the two, the NUCAPS sounding captures the EML, though it is with much less detail. NUCAPS tries to represent the temperature inversion, but it is too coarse to be operationally useful. The drying aloft is also present, though too high, with moistening above. The general shape of NUCAPS is on par with the raob. As for the CAPE fields, NUCAPS is a little hot with MU and SB CAPE compared to the raob, while MLCAPE is slightly too low.

Expecting all three severe threats today with convection moving through the area.

- Bucky

Bismark CWA Derived Wind Analysis

Quick look at the derived wind fields across Bismarck CWA. Still a lot of clear skies, but sum information can be gleaned from image below (upper left 300mb, upper right 500mb, lower left 700mb):

Think lack of elements to track at the moment have lowered my confidence in some of the values, but in areas with  more extensive cloud cover seems to be picking up jet at 300mb.  Think best track to take is to monitor how these fields change over time as tracking elements begin to increase.

One concern I have is the color and labeling scheme. The current default is the same as VWP where red corresponds to poor data quality and green is good. This could be fairly confusing. Instead of coloring by speed, perhaps coloring by pressure level would be better?  As it stands you could not overlay several layers over an image and use it easily.


-JRM

DMW with 4 panel Water Vapor

I was looking at the GOES-16 derived motion winds alongside a 4 panel of the 3 water vapor channels and the simple water vapor RGB with another forecaster. A few thoughts: First, for the most part, the winds seem to match up pretty well with the motions observed on the three different water vapor channels. Looking over north central Missouri, we notice the anticyclonic motion in the mid and upper level water vapor channels. Looking closer at the low-level water vapor loop there is evidence of some more cyclonic motion due to a remnant MCV from morning convection. The winds pick up pretty well on these differential motions. Some thoughts for improvement from me and the forecasters here at the experiment are that it would be nice to first see the winds time matched to each other at the same time. Some levels of winds show up at different times than winds at other levels and makes looking at a loop of winds very difficult. Also it would be good if the winds stay on the screen the entire time until a new update comes in. Just keep the previous barb up until a new update instead of the winds just flashing on and off as the loop rolls. Lastly, it would be more helpful to see the wind barbs color coded by level instead of speed. The barb already has the speed on it and when multiple levels are loaded it is tedious and difficult to tell what level you are sampling.

-Michael

Derived Wind - Colored By Height

It has been mentioned by several post about the difficulty in displaying multiple levels of the GOES-16 Derived Wind data.  I thought I would post an idea of how to display the data in the future (see below).  While the colors may not be perfect, having each level being colored the same makes it much easier to understand.

GOES-16 Derived Winds - Colored by Level

In this case, the warm colors highlight the jet level winds, while the cooler colors are in the lower levels. 

-GOB

GOES-16 300mb Derived Winds

With more clouds and convection over the area, the GOES-16 300mb Derived Winds are a little more reasonable today than they were yesterday.  In this case, the derived winds are colored in green/yellow/red based on speed (would prefer to have them grouped as a specific level so it is easier to compare levels) and the 300mb RAP data is in white.

300mb GOES-16 Derived Winds

Unfortunately, when looking at 850mb data, the values vary a little more.  In the diurnal CU area over the southern CONUS, the values are very variable.  But looking up in northern ND/MN, the values seem to match up fairly well with the RAP data.

850mb GOES-16 Derived Winds

-GOB

GOES Dervied Winds and You...

Where to start with the GOES Derived Motion Winds. I can see utility in having satellite derived winds, but there are some issues that need to be sorted out first before they can really be useful to an operational forecaster. First, the plotting convention, there is no need to plot three separate colors for Winds <30kts, 30<= Winds < 50 kts, winds > 50 kts. The barb tells you what the speed is, we don't need to color code these three levels. Additionally, when you load up all the mandatory levels, you end up with too many categories of winds. Considering the cloud heights play into where the winds are generated/plotted by GOES-16, a forecaster will need to plot all the mandatory levels, and with three categories for each, that is 27 different wind barb sets, which is unnecessary. Timing is an issue, as well, Wind data is sporadic, not with every GOES scan. For the gif example below, this is conus scale for both the mid-level water vapor and the winds. Notice the variation of wind data to each 6.95um (mid-level water vapor scan).

Dale Doback

Goes-16 Derived Winds

First look at the GOES-16 derived winds this week.  Overall, not impressed with the utility of this product as it seems sporadic at best and not very continuous as it's highly dependent on cloud cover at whatever level you are looking at.  Also, on occasion winds are way off from model fields, nearly 180 degrees off at times.  This really lowers confidence on using the wind fields in an operational sense.  Here is the most recent loop over the northern plains.

-ISU2004

Derived Winds - Initial Feedback (Part 2)

Expanding on the derived winds, I decided to add 700/500mb winds with the 850mb winds.  This leads to the inability to determine what level the winds are at.

As you can see in the image above, the Green/Yellow/Red colors are the same for each level.  This keeps you from being able to determine what level the winds are at with the default colors.  To be honest, I don't think there is much need to have the winds color coded by wind speed.  The barbs highlight that information.  Having the derived winds highlighted by their level would be much more helpful in displaying data at different levels.

In addition, when sampling the data, it does not label what the level is.

-GOB

Derived Winds - Initial Feedback

While getting setup for the MPX CWA, decided to take a look at the GOES-16 derived winds since I didn't get a chance to look at it yesterday.

I intially loaded up the 850mb winds and there wasn't anything in the MPX region. But looking farther to the southwest, there were some derived winds in the lee of the Rockies.  Here is an image of the 850mb derived winds:

There was a lot of variety in the speeds and directions (possibly due to limited cloud cover), and opted to overlay RAP data to see how they compared.  Overall, not so good:

Notice how the winds in eastern WY varied by 180 degrees (and were around 45-50kts), while the RAP had northwesterly winds around 5-10kts. There were similar values with most 850mb winds, for example the diurnal CU field in Missouri and Arkansas showed wind directions 180 degrees from the RAP values. 

-GOB

Derived Wind pictures

Worlds greatest upper divergence in far southeast NE? Flow around updraft? Flow outside of anvil into central IA?

Benjamin

speed max through west central Nebraska help storm development and sustenance. Upper level derived winds on water vapor.

GOES-16 DMW Display

NWS forecasters have commented on the present display of the Derived Motion Winds (DMW's) in AWIPS-II. They do not like the display, and would prefer it be made similar to the current GOES-13/15 operational satellite-derived winds.

To start, we review the display of the operational GOES-13/15 satellite-derived winds below. Displayed are all of the winds by pressure level. One can load winds by pressure level, and wind barbs and labels are color coded by pressure level. When sampling the winds in the AWIPS-II display, the output includes: time, wind derived from IR or VIS, temperature at pressure level of wind, pressure level of wind, wind direction and wind speed. Forecasters think this display is great. They like the color coding by height, and they like all of the output that is shown when a wind is sampled. An improvement would be to get more specific about the channel from which the wind was derived (WV, IRW, SWIR, VIS). Ideally, this is what the display would look like for GOES-16 DMW's in AWIPS-II. Unfortunately, it is not...

... Below is a display of of the GOES-16 DMW's in AWIPS. Similar to what we did for the GOES-13 winds above, we loaded all of the GOES-16 winds by pressure level. Instead of by height, the winds are color coded by speed for each level. For each level, winds are grouped into a >=50 kts bin, <50 kts bin, <30 kts bin (3 bins for each level). This creates a lot of separate products to be listed. Instead, all winds for a pressure level should be loaded together in one label. When sampling the wind data, the only output is time, direction, and speed. No indication of wind level, temperature, or channel from which the wind was derived from, is given. Forecasters do not like this display, and find it makes the winds less usable. Forecasters would much prefer a display like that from the GOES-13/15 satellite-derived winds, shown above.

- Bill Line, NWS

Derived winds

Today was my first real chance to glance at the Derived Winds.  They don't seem to be doing very good.

I plotted 1000 mb winds.

Looking along the LA coast SE of Cindy's center, we get a "red" wind that is from the 87 deg, 20 knots.  Winds should be from S/SW.  Also, "red" is supposed to be >= 50 knots.  Flag shows 20 knots.

"Yellow" flag is 58 deg, 42 knots.  Again direction should be S/SW.  Color is right this time, though.

Davis Nolan
WKRN Meteorologist

Derived Motion Winds from GOES-16

This was the first time I had a chance to look at the derived motion winds from GOES-16. I loaded them on several different pressure levels and it became very difficult to figure out what pressure level a specific wind barb is coming from. I turned on sampling and did not see a pressure level indicated.

I recommend adding the height of the specific wind barb when sampling is turned on.

-Ironman

Significant Issues with Dervived Motion Wind

With tropical storm  Cindy in the Gulf of Mexico, it seemed reasonable to use the derived motion wind to estimate the strength of the tropical storm. I went ahead and loaded the visible satellite imagery with the associated derived motion wind vectors:

Unfortunately, the performance of the derived motion wind was poor. There were a lot of spurious wind vectors across southern Texas and Mexico, which had values between 50-80 knots.  These are likely due to the algorithm tracking small areas of cumulus.

In addition, the  wind vectors across the southern part of the tropical storm were in the opposite direction. These winds should be from the west instead of the east.

The overall poor performance of the derived motion wind gives me zero confidence in operational utility of the data.

-Lost Met

Dervived Motion Wind Issues

There are some inaccuracies with the derived motion winds when compared to surface observations. Here is an example with the 1000 mb wind speeds (near surface) and METARs:

Note the significant discrepancy in both speed and direction.

It also appears the clouds are moving southwest to northeast (opposite of the wind barbs).

In addition, I would suggest color-coding by pressure level rather than wind speed because wind barbs (by definition) already provide the wind speed information.

-Lost Met