Convection Developing in LOT CWA

Starting to see development across the LOT CWA and allows for a comparison of the Day Cloud Phase and radar data.

In the first image, the Day Cloud Phase is showing increased yellow colors that highlights higher cloud tops and increasing ice in the clouds.

Over southern Lk Michigan, there is more of a green tint (increased ice) to the cloud tops and that matches with the location of the strongest storms in that area.

Here is a loop of the Day Cloud Phase over the last couple of hours.

Finally, I would like to some nice quick guides for interpreting the GOES RGB products (expand current ones to all RGBs).  There is a decent spin up period in understanding what is being shown and during an active weather period, the quick guides will make the products more usable.



-GOB

GOES16 derived instability products is showing a CAPE gradient over western IL.  There is one pixel of CAPE approaching 3,000 J/kg.  Granted it is one pixel within a lack of surrounding data.  It seems plausible considering the gradient is increasing in that area.  Looked at mesoanalysis and it lines up well with GOES derived CAPE.

--Dan S.

Prob Severe Spike Again

Prob severe now up to 62% again and seems to have coincided with a lightning jump as well.  Fortunately, still in the original warning that was drawn from satellite imagery.  Wind threat is now up to 26% with hail still dominating at 62%.  Again, wind remains the main threat with the inverted V signature down low.  The wind algorithm doesn't seem to account for the favorable low level moisture fields.  Otherwise, I would think the threat would be more equal or wind perhaps being the greater threat.

-ISU2004

GLM & GOES-16 Parallax

While waiting for convection to develop in LOT's CWA, decided to look at convection farther to the west in eastern ILN CWA.

Looking at the image, the MRMS RALA is in the upper left, GOES-16 sandwich is in the upper right, GLM in the lower left, and ENTLN in the lower right.

If you look at the convection in northern Madison County, you can see parallax in effect on both the GOES-16 Visible/IR product (shifted farther to the northeast) and the GLM data (shifted farther to the east (around a half a county).  A zoomed in image is below:

-GOB

GOES-16 Simple Water Vapor RGB

Four panel comparison of the three available water vapor channels, Upper Level: 6.19um, Mid-level: 6.95um, and Low Level: 7.34um to the Simple Water Vapor (RGB): 10.35um/6.19um/7.34um. Interesting imagery, with contributions to Red from the Clean Window IR ~10.33um, and contributions to the Green and Blue from Upper WV and Lower WV, respectively. In the example below, there across the Continental U.S. (CONUS), the only contributions from Red (Clean IR) are in the regions under greatest cloud cover, it appears to be the ones with most glaciation, thunderstorm cloud tops. Dry air aloft is depicted by basically zero contributions from Red, Green, or Blue. This channel is somewhat helpful, when one is not sure to which WV channel they should be using. However, subtle features, such as short waves, etc. are difficult to pick out with the default color curve, and easier to see, for the Idaho/Montana example on upper and mid-level WV.

Clockwise: Upper Level WV, Mid-level WV, Low Level WV, Simple WV (RGB).

Simple Water Vapor (RGB)

Dale Doback

New Warning

We issued a new warning solely based on the cloud top cooling noted on the 10.35um IR channel.  In fact drew up the warning on the satellite image, but ended up being a bit too far north due to parallax error. Did try to shift it south knowing that factor, but still did not go far enough south.  ProbSevere has also trended upwards with this cell. Did a screen capture with satellite and radar side by side for comparison.  As you can see the cooler cloud top is displaced much farther to the north.

-ISU2004

GOES16 WV channels showing shortwave

Severe thunderstorm development is expected within 1 to 2 hours at the time of this post at 20:15Z.   Using the different WV channels in the lower to mid and upper levels on GOES16 allows me to see a definitive shortwave moving into a highly unstable area in western IL.  A large deck of clouds will be moving into the unstable region in N IL.  This will prevent additional GOES16 derived instability products, but we already know the CAPE ranges in the 2,000 to 4,000 J/kg range.  An MCD was issued by the SPC for this same area.  I also noticed a healthy cu field in the exact location.  Initiation is almost imminent.

--Dan S. 

Spurious GLM Data in LOT/DVN CWA

While getting some displays setup for convection in the LOT CWA, I noticed one of the issues that was highlighted in this mornings GLM overview.

In this case, the GLM Event/Flash data was indicating three flash/events (one in LOT and 2 in DVN's CWA).  In all three cases, there was no convection in the area and little to no cloud cover.

The ENTLN data in the lower right image had no total lightning data during that same time.

-GOB

Meso-sector Visible

GOES-16 Visible satellite this afternoon shows decent convection developing across western MT with new development occurring on the south side.

The red lines show the CWA boundaries.  Not much cloud development back to the east over central MT right now, but convection will continue to move east.  Lack of clouds to the west show storms will remain elevated as they push on east.

-ISU2004

Comparison of RAP and GOES-16 CAPE values

While waiting for convection to form in or around the LOT CWA, decided to compare the GOES-16 CAPE data with the RAP 2hr forecast.

In the screenshot below, the RAP BL CAPE is on the left, while the GOES-16 CAPE is on the right.  Both CAPE imagery use the same colortable and values go from 0-5000 J/kg.

In this case, the BL CAPE value from the RAP (18Z run) is significantly higher than the GOES-16 data.  Prior training highlighted the need to focus more on the gradients and less on the values and the GOES-16 data has a fairly decent gradient from higher (2000+ J/kg) to lower (1400-1500 J/kg) values across the ILX CWA.  This gradient matches up fairly well where the edge of the developing cloud field is located.

-GOB