Surface Convective Initiation Application

The CI product is deemed most useful leading up to a severe weather event. As intended, it seems that it can provide at least an idea where convection will occur. There are two things that came to mind when looking at this tool.

On quieter days this tool can become noisy. By editing the colors in the RGB color model, I was able to black out all probabilities below 50% and to clean up the product. This will bring attention to the higher probabilities, as opposed to cluttering the field with lower end probabilities. The threshold (<20%, <30%, <40% etc) a person chooses to ignore is up to the user. To do this, though, you must continually edit the color model. This isn’t difficult, but  takes time. It would be nice if a default button existed that allows you to black out a specified range. Below is a result between the two (normal view 1-100% and 50-100% probabilities, respectively):

The second thought pertains to what application this could have during lake effect snow events. In the proper environment, convective snow banding could lead to heavy, consistent snowfall of greater than 35 Dbz. This may be a useful tool for updates to geographical locations of higher intensity snowfalls in these events.

- Forecaster

ProbSevere Single Site Radar vs. MRMS

The ProbSevere model utilizes Multi-Radar Multi-Sensor (MRMS) data for tracking storms using composite reflectivity as well as maximum expected size of hail (MESH) as a predictor within the model.  When displaying ProbSevere data on single site radar reflectivity, the contours can at times be slightly displaced from the single site radar due to updates to the single site radar data that are not yet ingested within the MRMS data.  The displacement is small and it is still clear which storm a given contour is associated with, but it is something users need to be aware of.  Below are two images with ProbSevere contours overlaid on MRMS (Figure 1) composite reflectivity and KCYS 0.5 degree tilt reflectivity (Figure 2).  The displacement typically only lasts for one to two ProbSevere valid time(s).

Figure 1.  NOAA/CIMSS ProbSevere and MRMS Composite Reflectivity valid at 2204 UTC 5 May 2014.  Notice how the ProbSevere contour very closely matches the MRMS reflectivity.

Figure 2.  NOAA/CIMSS ProbSevere and KCYS 0.5 degree tilt reflectivity, valid at 2204 and 2206 5 May 2014, respectively.  Notice how the ProbSevere contours are slightly displaced from the KCYS storm radar reflectivtiy, because the local radar updated at 2206 UTC.  By 2208 UTC, the ProbSevere contours matched the KCYS reflectivity as the MRMS had ingested the updated KCYS data (not shown).

-Sieglaff

GOES-R-CI in Wyoming

GOES-R CI product shows low chances for convection in EC Wyoming. Isolated weak storms formed just north of the Black Hills with no probability of CI (could be a thin cirrus issue).

- Bthoren

GOES-R CI in TN

CI indicated 83% chance for a cell in Claiborne, Co., TN as of 21:45Z.  Subtle impulse and perhaps outflow from old convection to the east may be puffing up the Cu…we’ll see how it develops over the next hour.

—DB

NOAA/CIMSS ProbSevere Model Introduced at EWP

The NOAA/CIMSS ProbSevere Model is a statistical model that combines, NWP environmental conditions, satellite tracking and growth rates, and radar tracking and storm intensity to predict a developing storm will first produce severe weather in the near future (0-60 min). The NOAA/CIMSS ProbSevere model is being demonstrated to National Weather Service forecasters at 2014 Big Spring Experiment at the Hazardous Weather Testbed. NWS forecasters are encouraged to evaluate the ProbSevere model output as a means to increase confidence and lead-time in issuing initial severe warnings on developing storms. Today the weather is rather quiet across much of the country. A strong storm developed in southwestern Virgina and the evolution of the ProbSevere model performance on this storm is highlighted below. Of note, this storm achieves high probabilities and as of 2030 UTC, has been the only storm over CONUS today to achieve appreciable ProbSevere values.

Figure 1.  The NOAA/CIMSS ProbSevere at 1950 UTC 5 May 2014--the first time the model produced probabilities above 50%.  Radar data is not yet seen in this display as a domain switch was in-progress within HWT.

 The NWS office in Blacksburg, VA issued a severe thunderstorm warning at 1952 UTC.  The following two figures show the continued increase of NOAA/CIMSS ProbSevere probabilities.

Figure 2.  NOAA/CIMSS ProbSevere at 1954 UTC 5 May 2014--probabilities are now 80%+.

Figure 3. NOAA/CIMSS ProbSevere at 2006 UTC 5 May 2014 now exceeds 90%.

This storm went on to produce severe hail (1.00") at 2009 UTC--19 minutes after the initial ProbSevere > 50%.  While this storm was not located in the a CWA of focus for this afternoon, forecasters are using this storm to gain confidence in the ProbSevere model and ask questions about some of the technical details of the model.

-Sieglaff

Western VA High Prob Storm

A storm developed in Western Virginia around Long Spur, just west of Pulaski. In early stages of development, probabilities of severe weather occurring were low. Radar reflectivity was generally between 50-60 Dbz. Severe probability quickly increased from 11% to 96% within 18 minutes. In the same time span reflectivity of up to 71 Dbz was detected. MRMS MESH maximum was 1.74 inches, while there was a notable increase in MUCAPE and EBSHEAR.

- Forecaster

Prob Severe Model

Not really our area today, but prob severe model indicated a 56% chance this storm would produce severe weather at 1950Z .

At 2012Z prob was up to 96%.  Model has low probabilities with other storms in area.

- b thoren

Watching Testbed Tools Cinco de Mayo

Been watching an area of showers across central Virginia…located north and east of a cold front.

Typically would not expect to see vigorous convective development in the relatively stable air here.  The NOAA/CIMMS ProbSevere Model agrees….it’s been outlining some cells, but typically have not seen anything higher than a 10% severe probability.

Of some interest is the GOES-R CI model, which for a time pegged a 60% chance for some more cell development to the south and west of the current area of precipitation in southwest VA.  Surface analysis shows this area to be much closer to a surface boundary separating 80s from 60s.

Some further monitoring of the CI has seen the value dip back into the 40% range within about 15 minutes time.  Will be interesting to see if this parameter continues to move some over the next hour or so…or if any development actually occurs.

UPDATE

Convection developed within the hour…with high severe probs!

Also to be noted after the fact: the forecast theta-e difference between 500 and 780 mb leading into the convection showed a nice and persistent…although not overwhelming in magnitude (-6 at worst)…piece of instability rolling into SW VA.

So far, the forecast tools have done a good job in pointing to an area…even if it was marginally outlooked this morning…of an area of vigorous convection that did develop.

- Forecaster

EWP Big Spring Day 1: 5 May 2014

Day one of our Big Spring Experiment and operations are already well underway.

The focus for today is primarily hands-on training.  The forecasters have been asked to examine all the experimental products and issue occasional blog posts as they see interesting or note-worthy items.  The goal is to develop a familiarity with both the new products and blogging process.

Two forecasters (Thoren / Maples) are localized to the Sterling, VA (LWX) WFO and watching ongoing convection there and areas south including the Blackburg, VA WFO.  The other forecasters (Rudge / Bickford) are localized to the Cheyenne, WY (CYS) WFO, monitoring the region for CI.

As the week continues, are focus will become a little more defined and move to writing mesoscale / forecast discussions and warnings.  Expectations are that the probability for severe convection will increase with each day of operations this week.

-Kristin Calhoun, Week 1 Coordinator

Welcome to Week 1 of the 2014 HWT Spring Experiment

Welcome to the start of the 2014 HWT Spring Experiment. The forecasters are busy getting spun up on all of the products, and writing some initial blog posts. Forecasters for this week are in attendence from Norman, OK, Grand Rapids, MI, Rapid City, SD, and Spartenburg, SC. Visiting GOES-R support for the week includes Steve Goodman, Justin Sieglaff, and Kris White.

GOES-R products being evaluated in the EWP this year include: Synthetic Satellite Imagery, NearCast System, Convective Initiation, Probability of Severe Model, Overshooting Top Detection, PGLM Total Lightning products, Tracking Tool and Lightning Jump Algorithm. Additionally, participants are evaluating the GSD Ensemble LAPS and the OUN WRF. Please view the GOES-R HWT plan for more details: http://www.goes-r.gov/users/docs/pg-activities/2014-HWT-DemoPlan-Spring-Exp.pdf.

This year, we are lucky to have GOES-14 1-minute imagery available from Thursday, May 8 to May 22 over limited domains. This imagery will be available in AWIPS-II for forecasters to view and provide feedback on.

As in previous years, participants, in addition to myself and visiting scientists, will make frequent posts to this blog regarding the days activities, product performance, product feedback, etc.

- Bill Line, SPC/HWT Satellite Liaison