Severe CI Probs but is it true

Looking at 1 min GOES Ch2, Ch13 Satellite data while overlaid with Severe CI showed several areas that have quite high severe CI probabilities initially but then trend downward with probabilities. This is apparent over the NW portion of the LBF forecast area (north Platte) close to the warm front. So, not sure of the effectiveness of the severe CI data. Included a screen shot here.  Also, noticing convection protruding from a perhaps a dry line across eastern Wyoming. Seeing that developing with the 1 minute imagery was quite valuable. Will try to upload an animation to show but proving to be problematic to create an animation of this particular data within AWIPS.

 

 Here's the animation...

More to come...

Supercell

Cheyenne WFO severe warning w/ minimal ProbSev

Storm was severe warned, ProbSevere shows less than 10% of severe probabilities on hail/wind/tor.  No LSRs as of yet

GOES All Sky LAP vs Derived CAPE/PWAT

Comparing the CAPE and PWAT over Nebraska and Wyoming. Over Nebraska the GOES Derived was sufficient. However, over Wyoming, where convective initiation began along the moisture and instability gradients in SE WY, the GOES Derived products were blacked out due to cloud cover. The LAP products filled in the missing data quite nicely as convection fired off 18-19Z.

- Jack Swigert

CI Low but Severe CI High?

Today's CI products seemed to pinpoint the initial convection for the day the best so far this week across SE Wyoming. However, CI was highlighting convection potential at 30-40% but Severe CI was highlighting areas 80-90% off convective clouds off Snowy Range and Laramie Mountains. Why would it only be a low chance of convective initiation but a higher chance of severe convection?

Update #1: Severe Warnings were issued for these storms around 2030Z
Update #2: No severe reports across WY were in as of 0045Z

- Jack Swigert

NUCAPS depicts instability gradients across the Piedmont Region...and other thoughts about Best Practices...

Hi all, it's your friendly NUCAPS representatives here, Kris and Nadia. So, here we are on the last day of HWT operations, digging into the data.  Initially, we took a look at the lapse rates aloft and a nice W-E gradient in NUCAPS lapse rates values was displayed across the Piedmont region.  This is shown in Figure 1 below.

Figure 1.  NUCAPS sounding locations (green, yellow, red dots), layered on top of NUCAPS gridded 850-700 MB Lapse Rates (C/km).  Also shown are GOES-16 Vis (0.64 um) imagery and MRMS isothermal reflectivity at -20C (dBZ). 

In Figure 1, notice the W-E gradient in 850-500 MB lapse rate values.  Higher values can be observed immediately on the eastern side of the Appalachians, with gradually lower values sloping off to the east across the Piedmont into the Coastal Plain.  The orange colors indicate values generally above 7 C/km, certainly conducive for the maintenance of strong updrafts in deep convection.  The highest values are generally observed in portions of west-central North Carolina.  The sounding shown in Figure 2 is from the peak value in lapse rates, near Hickory, NC.

Figure 2.  NUCAPS Sounding from near Hickory, NC at approx. 18 UTC 10 May 2018.

In this sounding, the steep lapse rates can be visually observed between 850-500 MB.  In fact, steep lapse rates can be seen extending from the surface.  Of course, upon looking at the surface temperature and dew point temperatures in the area, the NUCAPS sounding shown is too cool at/near the surface for these values.  So, resulting CAPE and other instability parameters will likely be higher.  Nevertheless, the application for quickly honing in on regions with relatively higher instability is helpful.

On another note, one of the forecasters here at HWT this year, Michelle Kennedy, made mention earlier that we should have a means for highlighting soundings that should catch the attention of forecasters due to the presence of relatively high instability values or severe weather parameters.  This was the purpose of putting the data into a gridded format, so that forecasters wouldn't have to click on and analyze numerous soundings.  It may be a best practice at least for now, to load the NUCAPS sounding availability along with select NUCAPS gridded values that contain measurements of higher instability.  This will help to shape our procedures and best practices going forward.   

SimpleWVRGB Compared with NUCAPS

Just playing with some RGBs...

Noticed that the Simple WV RGB was showing fairly continuous moisture returns at all levels across the LBF and GLD areas which is good verification that ample moisture is available over this area. Also, seeing the gravity waves to the SW stretching from San Diego CA to the Rockies within the more upper level moisture return (green colors).

Here is a NUCAPS sounding taken from eastern WY:

Here is a forecast sounding from the NAM12 from pretty much the same location

What I was trying to do was compare the nearly saturated environment shown on the Simple WV RGB with what I am seeing with NUCAPS and also NAM12 Sounding data around the same general vicinity of Wyoming.  What I think could be inferred is that the NUCAPS sounding is capturing the higher moisture better than the NAM12 all the way down to ~ 700 MB.  It may also be useful to compare multiple soundings around the eastern WY and NE area to see how it changes over time compared to the Simple WV RGB.


More to come...

Supercell

Week 2, day 4

Final day of operations for week 2.  To begin the day, we placed the forecaster pairs in two completely different environments.  One group, starts in North Platte, NE where we have a high potential for severe weather a bit later.  The second group begins in the Raleigh, NC where a line of storms are moving in from the west into a region of increased instability.  It will be interesting to see how the various GOES-E (16) channels and derived products are able to pick up on differences in the environments and storm behavior.

SPC day 1 outlook for 10 May 2018

CAPE axis extending into North Platte, NE at the start of operations on 10 May 2018. 

Line of marginally severe storms moving into western NC and across VA at the start of operations on 10 May 2018. 

CAPE values from NUCAPS...

Hi all, this is from NUCAPS product reps, Kris and Nadia.

So, the gridded NUCAPS data can potentially be a useful tool for assessing temperature, moisture and related parameters across the satellite pass swath, rather than clicking on individual soundings.  When making assessments of instability, one of the most sought after parameters is CAPE, whether in terms of MLCAPE, MUCAPE, SBCAPE, or whatever...CAPE is desired and utilized.  However, the computation of CAPE in AWIPS for NUCAPS data is not well understood at this time.  If forecasters attempt to load gridded NUCAPS CAPE values through the Volume Browser, then they'll see quite a number of options, many of which may not make a lot of sense.  For example, if they load "Computed CAPE" under the Stability pull-down menu, then a number of pressure field levels will be available (in addition to other options from the Theta, Hgt, Temp, Radar and Misc menus).  Unfortunately, there are no surface-based or mixed layer options under the Planes sub-menus.  So, we did a little deeper investigation today, attempting to answer the question...what is AWIPS computing when a forecaster selects CAPE at 850 MB, for example?  So, we *think* we know, although some further investigation will probably be necessary.  It appears that AWIPS lifts the parcel exactly at that layer and computes the CAPE value.  The same can be said for any other layer available, say 925 MB for example.  Image 1 shows NUCAPS 850 MB CAPE values from the 18 UTC data today, 9 May 2018.  Image 2 shows NUCAPS 925 MB CAPE values from the same pass.  Individual sounding locations are also included in the images.

Image 1.  NUCAPS 850 MB CAPE values overlaid with NUCAPS sounding locations

Image 2.  NUCAPS 925 MB CAPE values overlaid with NUCAPS sounding locations

Although they look fairly similar, there are certainly differences between the two sets of data.  We looked at several individual soundings from locations which had relatively large differences and manually computed the CAPE differences from that location when lifting the parcel from different levels.  It seemed to match pretty well.

Basically, in the future, we'll need to address this issue with CAPE and also address the lack of other important parameters missing from the NUCAPS gridded data suite.

-Kris and Nadia

CWA TomClemmons LOT 05-09-2018

Synopsis:An upper level trough of low pressure will move across the LOT CWA this afternoon during peak heating. The upper level system is forecast to push the sfc cold front across the area.

Problems with NUCAPS Sounding Availability - DB Modified, did not process the 18z sounding data over the LOT CWA. Here is a stability 4-Panel showing how much instability was available from the All-Sky Lap Stability Products.

GLM Upticks before warning issuances

We issued four severe warnings for northern Indiana and southern Michigan. All storms displayed good dual pol signatures, but we also noticed a sharp uptick in GLM Total Energy and Event Density on the storms we issued for. This increased our overall confidence in warning issuance.

Must be careful in areas of poor or no radar coverage if you want to issue based off GOES East Satellite data. Even in Indiana, the parallax offset between strongest radar returns and ground network lightning sensors with highest GLM total energy and event density is quite noticeable.

- Jack Swigert