CI and Severe CI in northern Nebraska

CI and Severe CI worked better today across northern NE highlighting areas of initiation and potential for severe.

- Jack Swigert

New NUCAPS procedures for HWT...

So, after a few days of discussion and observation, we've revised the NUCAPS sounding Procedure set for HWT.  Here is a short description of the procedures and the reasoning behind each one.  Whenever we refer to NUCAPS soundings, we're referring to the NUCAPS Improved Latency Soundings, with the exception of one procedure that contains the modified soundings.  Example pics of each are included at the bottom. 

Procedure 1.  NUCAPS Soundings & 850 MB Theat-E, GOES-16 Vis (0.64um)

Forecasters need some context for the NUCAPS soundings, so you will see in this procedure and all of the rest (with the exception of one) the inclusion of some form of GOES-16 ABI imagery with the NUCAPS sounding locations.  It's important to know why "holes" appear in the gridded data or why soundings are coded as yellow or red.  The presence of clouds helps to provide the necessary context here.  This procedure includes a simple visible image (0.64 um), but we also included 850 mb theta-e.  Theta-e can include valuable information about the location of frontal boundaries, and can indicate locations for locally higher instability in some pre-convective environments.

Procedure 2.  NUCAPS 850-500 MB Lapse Rate, GOES-16 0.64um and 10.3um

Here, we include NUCAPS soundings along with gridded NUCAPS 850-500 MB Lapse Rate data.  We also include the GOES-16 visible (0.64 um) and the 10.3 um IR "sandwich" product.  The lapse rates seemed appropriate to include with the sandwich product since the inclusion of the IR can also relate something about cooling cloud tops in areas of strong elevated instability or steep lapse rates.

Procedure 3.  NUCAPS Soundings & 850-500 MB Lapse Rates, GOES-16 Vis (0.64um), and MRMS Refl at -10C

Here, is the same as the last, except...we leave out the IR imagery and include MRMS reflectivity at -10C.  Why -10C?  Well, it's the beginning of the mixed phase region, potentially useful for lightning production, showing signs of early convection.  The -10C layer also usually falls somewhere within the 850-500 MB layer.  Ok, closer to 500 mb probably...but well...we had to choose something.

Procedure 4.  NUCAPS Soundings & 400-200 MB RH, GOES-16 Vis (0.64um) and 6.2 um Water Vapor

In this procedure, we include the gridded NUCAPS 400-200 MB RH, along with visible and imagery from the upper-level water vapor band (6.2 um).  We chose 400-200 MB RH since this vertical region corresponds generally well with the weighting function for the 6.2 um band.  We include the visible channel again (although it is layered under the WV channel) for sounding context.

Procedure 5.  NUCAPS Soundings & 850-300 MB RH, GOES-16 Vis (0.64um) and 7.3 um Water Vapor

For this procedure, we employed the same reasoning as above, including the 850-300 MB RH since the weighting function for 7.3 um is rather wide, encompassing this vertical region.  It could probably be argued that this should be narrowed a bit, but AWIPS only allows for specific vertical pressure layers.  This seemed the most appropriate at the time.

Procedure 6.  NUCAPS Modified Soundings & 850-500 MB Lapse Rates, GOES-16 Vis (0.64um)

This procedure contains the modified NUCAPS soundings along with visible imagery and 850-500 MB lapse rates.  We includes these lapse rates since these layers generally offer good retrievals for NUCAPS, and not boundary layer, which is modified in these soundings anyway.  Also, forecasters have suggested it may be good to have other data which would help to identify soundings that are in areas of potentially greater instability.

Procedure 7.  4Panel - 850-500 & 700-500 MB Lapse Rates, NUCAPS/HRRR/GFS20/NAM40

Here, we offer a simple comparison of NUCAPS gridded data with some numerical model data.  In this case, the HRRR, NAM, and GFS.  Of course, there are certainly other comparisons possible, but we wanted to keep it simple at first.  However, please feel free to offer other suggestions!

As promised, here are some sample snapshots of the procedures...

Procedure 1.

 

Procedure 2.

Procedure 3.

Procedure 4.

Procedure 5.

Procedure 6.

Procedure 7.

-Kris and Nadia

CWA TomClemmons RAH 05-10-2018

Synopsis: Well removed from the better upper dynamics/forcing and shear
that will move through the NE US this afternoon and evening,
forcing across central NC will be rather weak, limited to mainly
weak near sfc convergence, as the surface trough crosses the area.
However, strong daytime heating, featuring afternoon temps in the
mid 80s, will result in steep low-level lapse rates. These steep low-
level rates when coupled with with BL dewpoints in the lower 60s,
will fuel moderate instability of 1500-2000 J/Kg that extends well
into the mixed phased region. Despite the deep westerly flow in
place, majority of the CAMS indicate a fairly congealed multi-cell
line segment crossing the area between 18z to 03z. Given 20 to 25
kts of deep layer shear, some of the strongest updrafts will have
the potential to produce severe weather, including, hail and
damaging wind gusts.

Hampered by slow computer systems Tuesday, Wednesday, and Thursday:(

Notice low correlation between  -20 C Isothermal Reflectivity & GLM Total Energy 5min-1min update. Notice storm near the cursor.

In this example the storm is on the northern RAH CWA border, the updraft has pushed 50-60dbz echoes up through the -20 C isotherm, notice this time the GLM Total Energy and the Extent Density (# of Flashes that have crossed a pixel) are both showing high values. This would be a good situation awareness tool during an ongoing severe weather event. This storm was currently producing damaging hail and strong winds.

ProbSevere Wind and Hail:

1.75" hail was reported at 5:25 pm near Bahama.

ProbWind:

3NW of Stovall 2 Trees Down

ProbTor for NE Storms

The evolution of thunderstorms across Nebraska featured many storm splits and mergers and convoluted velocity data. Storms across northern NE north of the warm front exhibited some modest rotation aloft but cells further south across the panhandle into central NE displayed more impressive rotation. ProbTor hit these southern storms with higher values in the 20-30% range with lower values across the north, although the leading storm in central Cherry county had some higher ProbTor values near 20%

- Jack Swigert

Supercell Merger VIA VIS/IR Toggle

Saw this VIS/IR Toggle with the supercells merging across Garden, Sheridan, and Cherry Counties in Nebraska. The coldest cores at the end of the animation are in the eastern portion of Sheridian where the main two supercells merged. Had Prob East on the image and did see where it was showing probabilities of cells along the forward flank could develop.

Supercell

Supercell Merger in NE using ProbTools/GLM

Noticed an issue with all of the Prob products when two supercells merged. Captured an animation, but the probability products merge into one big area and is unable to resolve the individual updrafts as the transition is occurring.

Also, noticed that the GLM Flash Density and Total Energy increased markedly as the merger took place. With all of these updrafts so close together, am also seeing a marked increase in Average Flash Area-especially over Grant/Cherry counties.

Supercell

GLM increased after supercell Split

Noticed that GLM flash density and total energy spiked after the supercells split over Garden County Nebraska. Take a look at the GLM and also the MRMS/Prob Severe loops. Tried to add more images to these loops to look at the progression from where it was in Cheyenne county.

I am not really sure if there is a correlation with the increase in the particular GLM parameters, but did notice the increase after the storm split. Also take a look at the storm over Morrill County where flash density and Total Energy spiked in values. Average flash area is also increasing in between all of these cells showing large flashes.

More to come...

Supercell

GLM offset with ltg jump

GLM overlaid with ENTLN data showing GLM offset to the northwest of the storm.  Ltg jump occurred over the few previous frames as storm seemed to cycle again, with dBZ nearing 75

Splitting of Supercells RGB Satellite Imagery

Here's some awesome satellite imagery from the splitting supercell from Garden County Nebraska off the Day Cloud Convection RGB.

More to come...

Supercell

Splitting of Supercells and Prob Severe/Tor/Wind

A supercell that had been warned on split with the northern storm moving into the more favorable area of instability and the updraft rapidly strengthened to severe. Noticed that Prob Tor has increased to 9% on the northern storm and Prob Hail/Wind are 99%/89% respectively.  Issued a severe thunderstorm warning shortly after the last scan on this animation. Will be monitoring that northern storm for ProbTor. Have seen some upstream storms with strengthening with rotation.

More to come...

Supercell