CU Field Behind the Cold Front

In the image above the NearCast model indicates a gradient in the theta-e across western into northeast Nebraska. The visible satellite image (upper right) indicates a line of congestus along this gradient from near the SD border into central Nebraska. The GOES-R CI indicates some fairly high probability of initiation in this CU field. It is interesting though because this area is behind the surface front and there is little surface forcing for CI. Given the large-scale and mesoscale forcing in this area it seems like CI would be unlikely.

-JB

A Comparison Update

Looking forward two hours at the simulated IR/WV imagery versus observed (and remaining focused near the WY/NB border), the spatial placement is fairly good but intensity continues to be overdone. Here’s a snapshot at 22Z:

As aforementioned, the simulated product provides some confidence in where to remain situationally aware but does not give confidence if taken strictly at face value when taking the overall picture into consideration.

~Linda

Tracking Meteogram

When using the tracking meteogram product, I found that while using it with a gridded radar it dropped data.  The second problem I found was I can’t edit the meteogram itself.  When products are hidden in the main AWIPS screen, they should also be hidden in the  meteogram.  Another suggestion, is that you should be able to reload the last tracking you did so it saves you extra work and time.  I really do like the concept of this and the reason I am suggesting these changes is because I would like to use the product in the future!  It is useful! – Vollmar

Combined Prob Severe and NearCast

A stronger convective cell attempted to develop to the north of Scottsbluff, NE. As the radar indicated higher reflectivity the GOES Porb. Severe Model jumped to 62 percent with strong satellite growth rate. This cell quickly dissipated though and did not produce severe weather. Analysis of the NearCast System indicated that the strongest instability was located farther to the east into western and central Nebraska. While values near the cell indicated marginal instability. Using these two products in tandem may have been helpful. It will be interesting to see if this weak convection moves into the North Platte CWA as it gets into better convective instability.

-JB

Watching Towers Grow

Using the 1 min GOES rapid scan to view individual towers grow is great. Being able to see individual convective attempts and failures is very useful. On radar I was not able to tell that the convective tower had failed, but with the visible imagery I was able to see that the tower had failed to mature and soon the radar echo dissipated. Pretty cool.

-JB

A Quick Comparison

Getting a handle on the area of interest across southwestern Wyoming and the panhandle of Nebraska, we see a few cells popping up near the WY/NB border. Taking a look at the four-panel image below, you’ll see the CIRA/RAMMB NSSL-WRF simulated satellite imagery on the left hand side (IR on top, WV on bottom) and observed on the right (time: 20Z). So far, the simulated imagery seems to have a decent handle on storm initiation near the WY/NB border in particular, which allows for increased confidence in its forecast, even if the spatial placement isn’t necessarily exactly spot-on.

The simulated satellite imagery seems to be overdoing it just a bit so it’s not as helpful if you’re trying to assess specifics but if you can compensate by interpolating down in your mind’s eye, it is still a good product to increase situational awareness.

Linda Gilbert

GOES-West capturing CI in SE Wyoming

Convection is developing along the front range of the Rockies over SE Wyoming this afternoon, with GOES-West capturing some of the development. Earlier versions of GOES-West had issues with the 4 minute scan of GOES-West where cloud objects consistently ran "hot". This is a sample 4 minute scan from GOES-West, where only one object at the current time (1945 UTC) displayed higher probabilities (>70%) of CI. Additional database training for GOES-West has helped temper 4 minute scans and brought it more inline with the probabilities seen from GOES-East.

1945 UTC GOES-West CI imagery

NOAA/CIMSS ProbSevere model display

It's a quiet start to the 3rd week of the HWT Spring Experiment. As forecasters become acquainted with the various products being evaluated, we've seen some convection fire in southeast Wyoming, but it hasn't amounted to much yet.

The NOAA/CIMSS ProbSevere model is a statistical model that fuses together satellite growth rates derived from GOES cloud products, MRMS Maximum Expected Sized of Hail (MESH), and RAP MUCAPE and effective shear (EBShear) to predict the probability that any given storm will produce severe weather. The idea is to use the 1st-order NWP environment predictors and observed satellite growth rates to give forecasters more confidence and hopefully more lead time on issuing severe weather warnings.

Figure 1 shows the display of ProbSevere in AWIPS-II. It is driven by shapefiles, which are contoured around radar-identified storms. By scrolling over the storm, you can see the ProbSevere readout. The probability of severe (SVR PROB) is first. This storm in southeast Wyoming had a 17% probability of severe. Next we see the environmental MUCAPE (949 J/kg) and EBShear (48.3 kts) computed from the RAP NWP model. Next is the MRMS MESH, equal to 0.26 inches. Lastly, the normalized vertical growth rate, characterized as "strong", and the cloud-top glaciation rate, characterized as "moderate". The strongest satellite growth rates in a storm's lifetime are used in the model. These growth rates occurred 1.25 to 1.75 hours ago. Beyond 2 or 2.5 hours, the satellite growth rates may not be that relevant to incipient storm development. This is something the forecaster should bear in mind when using ProbSevere, as well as other important environmental aspects. Recent research has shown that severe storms tend to exhibit faster satellite growth rates than non-severe storms.

Figure 1: NOAA/CIMSS ProbSevere model display, overlaid MRMS merged composite reflectivity.

-Cintineo

Wyoming and Nebraska CI

Good afternoon all. Grant H. signing on for the first blog post of the first day of the HWT. In learning about the GOES Convective Initiation (CI) tool, I felt this might be a good first place to start. CI seems to be the most useful in hunting down areas where convection will begin over the first 2 hours of and event. I can see this being good from the warning coordinator/mesoscale forecaster perspective in making decisions on where/how to divide up/sectorize radar mets in ops.  The stuff off to the left over eastern Nebraska in blue has a very low probability of initiation around 10 to 20 percent. Meanwhile, the cumulus field over the southeastern Wyoming in the Cheyenne area is reaching up to 50%. This helps to force focus to the locations of interest. I do see some problems here in that the algorithm has troubles IDing areas that transition from stratus to cumulus or from cirrus with cumulus embedded underneath such as in northwestern Nebraska… very little CI color is showing up, other than the sheared area in this image.

Grant H.

EWP Operations Update – Monday 5/19

Forecasters are getting acclimated to AWIPS-2 as we sit and wait for convective initiation ahead of a shortwave trough in SE Wyoming and W Nebraska. We are currently operating from the Cheyenne (CYS) and North Platte (LBF) CWAs.

The downgrade of the “SLGT” risk to a “SEE TEXT” at the 20z SPC Day 1 Outlook and the “WATCH UNLIKELY” Mesoscale Discussion will not dampen our spirits.

2000z SPC Day 1 Outlook for May 19.

Mesoscale Discussion graphic issued at 2012Z.

KCYS is showing the first 40+ dBZ echo of the day in Goshen County, WY and with the airmass over the region continuing to destabilize, we are holding out hope that we will see some isolated convection in both CWAs in the next few hours.

First 40+ dBZ echo in Goshen County, WY.

-Darrel Kingfield

EWP Week 3 Coordinator