GOES-R Convection Initiation NW OH

The 1930 UTC GOES-R Convective Initiation image on May 13, 2014 depicted yellow  (65%), green (58%), light blue (46%), and several darker blue pixels (less than 40%) across northwest Ohio ahead of a line of storms.  There was a small cell that developed near the green pixel at 1945 UTC (third image below) moved northeast at 1958 UTC (fourth image below).  A cell developed and moved into the yellow and light blue pixel areas at both the 1945 UTC and 1958 UTC images below.

This product seems to do a good job highlighting higher potential areas for convection initiation (if 50% or greater) compared to lower chances (50% or less).

Michael Scotten

Tuesday 19Z – NSSL WRF Simulated Imagery

Just a quick blog update to show how the NSSL simulated satellite imagery is behaving.  It is not doing all that well, unfortunately.  It seems well overdone across central Indiana, where outflow from earlier storms has undercut convection and largely caused it to die out.  In our area of the day (Detroit CWA), the convection is well underdone.  We have ongoing strong to  locally severe storms, that the model does not have a handle on at all.

The simulated imagery is on the left-hand column, with the observed 19Z imagery on the right.

-Deitsch

NOAA/CIMSS Prob Severe Model – Idea for Improvement for Linear Storm Modes

The CIMSS Probability Severe Model indicated low probability for severe storms 5-10% for a fast moving line of storms over eastern Michigan (northern part of line moving 50-60 mph) at 1928 UTC on May 13.  It seems to be a good idea to include DCAPE as a displayable variable in addition to MUCAPE, EBShear, MESH, Vertical Growth Rate, and Glaciation Rate and use this variable for calculating SVR PROBs.  The low probabilities are likely due to MESH values well below 1 inch (closer to 0.25 to 0.50 inch) as well as EB Shear generally 20-25 kt.

Michael Scotten

EWP Status for 12 May 2014: 12:30-8:30 pm Shift

Today, the threat for severe weather appears to be quite marginal, the bulk of which will be forced by the eastward propagating cold front. We have two forecasters operating in the Detroit CWA, and two in the Cleveland CWA. Similar to yesterday, convection was already ongoing this morning when participants began operations. However, there has been some new development out ahead of the front.

Today's domains were chosen in part based off of input from the EFP. You can see from the image below, the EFP expects the greatest likelihood for severe weather to be in eastern Michigan south into western Ohio.

- Bill Line, SPC/HWT Satellite Liaison and Week 2 EWP coordinator

Daily Summary: Week 2, Day 1

Much of the focus for day one was hands-on training for each of the evaluation products. After some initial familiarization with AWIPS-II, the various PI's worked with forecasters on how to interpret the products, and what to look for during the week. Forecasters also became familiar with saving images, and posting to the blog. By the end of the day, participants had already made several informative blog posts.

Today we operated in the Davenport and St. Louis CWA's. Since many of the products being demonstrated have their greatest benefit in the pre-storm environment, forecasters were unable to experience their full potential given the ongoing convection at the beginning of operations. The Prob Severe and Overshooting Top Detection products seemed to have the most utility in this situation. Additionally, forecasters appreciated the availability of the GOES-14 1-minute imagery.

Tomorrow, we will start activities at 12:30 in the Dev Lab for the daily debrief before moving to the HWT for the EFP briefing. Operations will likely take place somewhere in the Ohio Valley region.

NearCast

• I worked a lot with the theta-e difference field. I focused on a line of storms in central Missouri, theta-e difference in front of storms was -20 K. That was consistent through the forecast as storms moved forward. A bow echo formed, pop up storms filled in the area where high instability was, then the line accelerated.
• There was a lack of data in the area today

GOES-R CI

• There was a differential heating boundary in northern Illinois. CI did provide lead time to a few isolated showers and storms (45 min) around 22Z. 
• So much high level cloud cover along and ahead of front prevented usefulness
• Pop up short lived pre-frontal showers. In SW Missouri I saw 90%, storms popped up and then fizzled. Then more development and more fizzle.
• CI did not pick up on a storm near Chicago

Prob Severe

• Large cell kept maintaining a high prob (>80%), and stayed severe.
• 50 to 60 to 77, then storms produced severe weather
• I liekd having CAPE and shear output. It gave me good situational awareness about the environment.
• It would be great to use SPC mesoanalysis data
• In a field where there is a lot of storms popping up, it does well at highlighting ones to watch

Tracking Tool

• I like the trends, but getting the storm motion was difficult (it was intensive to move each circle for each time).

Overshooting Top Detection

• I liked it, but I found that it was more useful just to examine the one minute data with the human eye during the day
• Might be good for flash flood situations, providing lead time
• I liked looking at it for the overall trends. Cold pool developed that overran front, OT's went away, then storm weakened. 

GOES-14 SRSOR (1-minute imagery)

• I don't know anyone who wouldn't like this
• Removed from wow factor, the things you see makes it worth it
• Around great lakes looking at advection fog, I wish we had 1 minute updates so we could see how much fog is spreading inland.
• I see value especially in radar sparse areas
• Examples of features seen in 1 minute that you didn't see in 15 min?
• Watching a storm with an enhanced V and OT, the OT collapsed, and I issued a warning. This had positive lead time to hail reports
• I was looking at a differential heating boundary. North had cirrus, south had a lot of bubbly.  As soon as the cu moved into the cirrus, it died off. It is something that in 15 minute scans you just couldn't see. 

- Bill Line, GOES-R SPC/HWT Satellite Liaison and Week 2 EWP Coordinator

Tracking storm development in MO with Theta-e differentials

On Monday afternoon, a line of storms developed and propagated eastward, essentially bisecting Missouri by late afternoon. Here’s a look at the base reflectivity for the radar at KLSX (St. Louis) at 22Z (about 4pm):

In the same timeframe, the CIMSS NearCast model was projecting a fairly high Theta-e lapse rate.

The box in the top right corner shows this GOES- derived Theta-e difference of around 20-21K in an area west of St. Louis. Interestingly enough, this ΔTheta-e maximum is aligned with the area of convection, seen in the radar imagery above. Will the storm cells continue to propagate eastward and will they actually strengthen as they enter this area of higher instability?

By 23Z, We’re starting to see some individual storm cells develop out ahead of the bow echo.

This would indicate that the area of high instability on the NearCast model is starting to produce some convectively-driven storms. The highest value I found in this image in the newly-formed cells was 56dBZ. So in the near term, it appears the NearCast is correctly predicting convective initiation through the ΔTheta-e product. How about at 0Z itself?

The stronger line behind the pop-up cells has accelerated and swallowed up the smaller individual cells! That is a straight line of storms if I’ve ever seen one. I suppose the ΔTheta-e could be used in this situation to predict that this storm line would evolve in this way. More cases will have to be examined in order to see if this parameter is consistently usable for this purpose!

ProbSevere in Illinois

The NOAA/CIMSS ProbSevere model picked up on some warm sector convection in Illinois (neighboring our operational domain) during the evening of May 12. Figure 1 shows that the storm in the center with the hovering read out had a strong satellite normalized growth rate and strong glaciation rate at 22:15 UTC. The strong growth rates, MESH of 0.92", and large MUCAPE ( > 3000 J/kg) contributed to the probability of severe of 92%. The NWS issued a severe thunderstorm warning (Figure 2) on the center cell at 22:53 UTC (no reports yet received).

Figure 1: Storms developing in northern Illinois exhibit strong satellite growth.

The storm to the west also had a high probability of severe. It too exhibited strong satellite growth rates (though not as strong as the center storm), and MESH over 1". It was never warned on and no reports have been received. There may be some model overforecasting bias in high CAPE / lower shear regimes (as noted in the training), so forecasters should consider this while using ProbSevere guidance during warning operations. One forecaster also noted that the MESH seemed to be overforecasting hail size, based on the reports coming in.

Figure 2: NWS thunderstorm warning issued at 22:53 UTC, shortly after ProbSevere forecasted over 90% probability on this storm.

EDIT

More storms have been warned in northern Illinois. The storm that traveled near Chicago has been highlighted via AWIPS-II readout (see animation below). It had strong satellite growth rates well before a warning was issued (it merged together with other satellite-identified storms objects), which contributed to a high probability of severe. The first probability of severe greater than 50% was forecasted 37 minutes before the first NWS warning. The last image also shows additional NWS severe thunderstorm warnings on storms to the southwest, which also had strong satellite growth rates and probabilities of severe.

-Cintineo

GOES-R Convection Initiation Product Handles Convection Developing in Northern Illinois 5/12

The GOES-R CI product did a fine job depicting convection growing in northern Illinois. The top image at 2145 UTC depicting values around 74% and the second image at 2200 UTC depicting 89%.  The radar images below at 2203, 2222, and 2240 UTC depicted a few developing showers and storms near the CI values below.   The product gave 15-45 minutes of storm lead time.  These storms did not become severe.

Michael Scotten

Value of 1-Minute Satellite Imagery

Monday, May 12, 2014 Mike Smith

Two situations worthy of note:

I “issued” a special weather statement for Winnebago Co. At 2:47pm for 3/4 inch hail and gusts to 40 kts. Using ONLY surface obs and 1-minute satellite data.

At 2:59pm, I issued a severe thunderstorm storm warning for the same county, based on a Fujita U with overshooting then collapsing top in 1-minute data.

NWS issued severe at 2:56pm (unknown to me). Both warnings verified with 1.75” and 2.0” hail reports.

I observed a downburst south of Sullivan, WI and based on the right moving cell, I thought the RFD would intensify at 4:12pm for Walworth Co. Predicted 55 kt and 2” hail. Unknown if it verified.

The right mover got more pronounced and at 4:22pm, I issued a tornado warning for the southeast third of Walworth Co. This was due to the wrapping pattern of the outflow air (into RFD), the 1-minute satellite U and collapsing top, the persistent right movement and high spectrum width in the inflow. NWS issued a tornado warning for the same area at 4:45pm. While a pronounced hook formed, it never quite formed a tight couplet.

ProbSevere highlights strong cored storms. MRMS MESH seems overdone.

The ProbSevere Model is doing a great job highlighting the strongest cells. In this image from 2208z the ProbSevere Model is overlaid on top of the MRMS reflectivity above the -20C isothermal level. The cells annotated with an arrow across eastern IA, southern WI, and north-central IL have 50dBz echoes above the -20C isotherm and the model indicates an 80+% prob of severe.

There were hail reports from three of the four cores highlighted. The lower left produced Quarter sized hail in Henry county IA with the MESH indicating 2.5in, The upper left storm produced reported penny sized hail in Johnson county IA with MESH of 0.89in and the upper right storm produced nickel sized hail in Racine county WI with a MESH of 1.13in. The MESH product is overdone in this example.

Shawn Smith