Cross-sections using gridded NUCAPS data in AWIPS

June 21st, 2022 |
NOAA-20 Day Night Band visible imagery (0.70) along with NUCAPS Sounding Availability points, ca. 19z on 21 June 2022 (Click to enlarge)

Gridded NUCAPS data, available from NOAA-20 data within AWIPS, can be used to construct cross-sections in AWIPS. The image above includes an editable baseline J-J’ (one of 10 different lines that can be used for data in AWIPS) from Minnesota into Indiana, roughly perpendicular to a line of broken cumulus over Wisconsin and Iowa.

Equivalent Potential Temperature along line J-J’ as indicated in imagery above (Click to enlarge)

The cross section of equivalent potential temperature, above, shows very warm temperatures over the southern portions of the cross section, with theta-e values around 350 K. Potential Instability, i.e., theta-e values decreasing with height, is widespread along the cross-section. The broken cloud field in the VIIRS imagery on top eventually did initiate convection, as shown in this radar capture from 0012 UTC on 22 June.

How do you create the cross-sections in AWIPS? Use the Volume Browser, as shown in the screen capture below. Select ‘Cross Section’ (vs. ‘Plan view’, for example) from the choices in the Volume Browser right next to ‘File’, ‘Edit’ and ‘Tools’, then choose ‘GriddedNUCAPS’ under ‘Sources’, and choose the correct Plane — as one of the Specified Lines you have previously moved in AWIPS; then choose the variable (possibilities are shown in the image; I chose Equiv Pot Temp).

Volume Browser presentation while creating Cross-Sections using gridded NUCAPS data (Click to enlarge)

Imagery in this blog was created using a cloud instance of AWIPS from the TOWR-S group within NOAA/NWS. Thank you!

Using Polar Hyperspectral Model forecasts of CAPE with a sea breeze front

June 14th, 2022 |
GOES-16 Visible (Band 2, 0.64 µm) Imagery, 1600 to 2100 UTC on 14 September 2022 (Click to enlarge)

One the forecast offices selected on 14 June 2022 in the Hazardous Weather Testbed was Tallahassee (WFO TAE). The animation above shows the evolution of a seabreeze front that moves slowly northward (as a mesoscale complex, part of a system that produced widespread wind damage earlier in the day (storm reports from 13 June and 14 June), moves southward). Convection develops along the sea breeze front. The animation of Convective Available Potential Energy (CAPE), below, from the Polar Hyperspectral Modeling System, shows a local maximum of CAPE along the coast initially; it then propagates inland with time. The 1- and 2-h forecasts predict with accuracy where the CAPE associated with the sea breeze front will be. That’s perhaps easier to view in the animation at the bottom that has the model CAPE field semi-transparent on top of the visible (0.64 µm) imagery.

Forecast fields of Convective Available Potential Energy (CAPE), 1600 to 2100 UTC on 14 June 2022 (click to enlarge)

GOES-16 Visible (Band 2, 0.64 µm) imagery overlain with PHS values of CAPE, 1600 to 2100 UTC on 14 June 2022 (Click to enlarge)

Additional Hazardous Weather Testbed blog posts can be found here. The third and final week of HWT concludes on Friday the 17th.

Using NUCAPS and ProbSevere LightningCast to anticipate a line of showers

June 10th, 2022 |
GOES-16 Day Cloud Phase Distinction and Radar Composite Reflectivity, 2001 UTC on 10 June 2022 (click to enlarge)

A weak line of showers moved through southern Wisconsin late in the afternoon of 10 June 2022, as depicted in the 2001 UTC toggle above of NEXRAD Composite Reflectivity and GOES-16 Day Cloud Phase Distinction RGB. What satellite-based products could be used to anticipate that line?

NOAA-20 orbits over the Midwestern United States on 10 June (shown here, from this site) were configured such that NUCAPS profiles over Wisconsin were derived from two consecutive passes. The toggle below shows derived Total Precipitable Water at ca. 1730 and 1930 UTC. Dry air over northeastern Wisconsin is abutted by greater values of total precipitable water over the southern part of the state.

Gridded NUCAPS estimates of Total Precipitable Water for two times on 10 June 2022. NUCAPS Sounding Points are also shown (Click to enlarge)

Data from NUCAPS profiles can also be used to compute various stability indices, including the Total Totals index, which is shown below from the two passes. Note in particular the gradient in the index over southern Wisconsin at 1930 UTC: a corridor of instability is present, and it is focused in that location mostly because of dryer air to the northeast (click here to view 850-mb Mixing Ratio from gridded NUCAPS at 1730 and 1930 UTC). In addition, diagnosed mid-level Lapse Rates (in this case, 700-500 mb) at 1930 UTC (shown below) show values between 7 and 8 oC/km. (Note to AWIPS Users: Gridded NUCAPS Total Totals index values can be accessed via the Product Browser, under ‘Grids’)

Total Totals index, 1751 UTC and 1933 UTC, 20 June 2022 (Click to enlarge)
700-500 mb Lapse Rates, 1930 UTC on 10 June 2022 (click to enlarge)

ProbSevere LightningCast (link) is a forecast aid created to diagnose (from ABI imagery) the probability that a GLM Lightning observation will occur in the next 60 minutes. It can also alert a forecaster to developing convection, because the satellite signatures that suggest lightning might occur in the next 60 minutes often occur before radar observations of convection. The animation below shows LightningCast at 15-minute time steps, from 1800 to 2000 UTC on 10 June. Note how LightningCast keys on the developing line of cumulus long before showers develop (and more than 30 minutes before lightning occurs!)

LightningCast probabilitt readout, 1800 – 2000 UTC on 10 June 2022 (Click to enlarge)

The animation below shows GOES-16 Day Cloud Phase Distinction overlain with Geostationary Lightning Mapper (GLM) Minimum Flash Area (MFA) observations, from 2001 – 2316 UTC. Consider the smallest MFA values (in yellow) to represent vigorous, new updrafts. Larger MFA (green) are more likely in the anvil.

GOES-16 Day Cloud Phase Distinction RGB, and GLM Observations of Minimum Flash Area, 2001 – 2316 UTC on 10 June 2022 (click to enlarge)

NUCAPS and ProbSevere LightningCast added to Situational Awareness for this event.

Some imagery in this Blog Post was created using the NOAA/TOWR-S AWIPS Cloud Instance. Thank you!

Polar Hyperspectral Modeling at the Hazardous Weather Testbed (Week 2)

June 10th, 2022 |

The second week of the Hazardous Weather Testbed (here is the blog site) ran 6-10 June 2022, and this blog post will discuss one or two of the events that happened this week. I was away from the Testbed on the first two days, and day #4 was not an active day for severe weather during the Testbed hours. The daily maps that summarize the short-term forecasts and the observed severe weather (courtesy Bill Smith, Sr) are shown below. On all days, the STP forecasts and analyses overlapped the region of severe weather.

Forecasts of Significant Tornado Parameter (STP) from different forecast runs (1400, 1800, 2000, 0000) and observed severe weather associated with STP forecasts, Monday 6 June 2022 (Click to enlarge)
Forecasts of Significant Tornado Parameter (STP) from different forecast runs (1400, 1800, 1800, 2200) and observed severe weather associated with STP forecasts, Tuesday 7 June 2022 (Click to enlarge)
Forecasts of Significant Tornado Parameter (STP) from different forecast runs (1800, 2000) and observed severe weather associated with STP forecasts, Wednesday 8 June 2022 (Click to enlarge)

Wednesday’s STP example over southeast Indiana was one of the better predictions of the week (and it’s also discussed in this HWT blog post). The ProbSevere objects contours are surrounding maxima in the STP field. As during week 1, there were many examples that showed ProbSevere signals along the perimeter of large MUCAPE values (Most Unstable Convective Available Potential Energy; that is — in the MUCAPE gradient). Here’s an example from 2000 UTC on 8 June 2022 (the same time as the image below).

2-h forecast of STP valid at 2000 UTC on 8 June 2022, along with ProbSevere contours valid at 2000 UTC (Click to enlarge)
Forecasts of Significant Tornado Parameter (STP) from different forecast runs (2200 UTC and later) and observed severe weather associated with STP forecasts, Thursday 9 June 2022 (Click to enlarge); severe weather on this day mostly occurred after HWT activities ended.

As with Week 1, forecasters found great utility in using PHSnABI model output in anticipating where convection might form; that is, it was most useful in the pre-convective environment, and forecasters found 0-4h forecasts most useful.