Polar Hypsectral Sounding and ABI (PHSnABI) Model results during Week 1 of the HWT

May 27th, 2022 |

One of the products being demonstrated at Hazardous Weather Testbed the week of 23-27 May 2022 was a modeling suite that includes Polar Hyperspectral Soundings (PHS, using IASI/AMSU data from the MetopB and MetopC Satellites as well as CrIS/ATMS data Suomi/NPP and NOAA-20) that are associated with Advanced Baseline Imager (ABI) information on GOES-16 through a process known as Data Fusion (or PHSnMWnABI). Previous blog posts on PHSnMWnABI modeling can be viewed here. The summary slides below (courtesy Bill Smith, Sr) show summary results from the four days, including Storm reports from 23 May, 24 May, 25 May and 26 May. Some of the slides are followed by AWIPS screen captures from the various days. Forecasters at HWT were typically active from 1800-2300 UTC on each day.

Monday 23 May 2022

The first day was a day to get one’s feet wet. The WFOs chosen on this day were WFO CAE and WFO LBB. (Here’s the 1630 UTC Convective Outlook for the 23rd; Mesoscale discussions 879, 880, 881, 882, 883, 885, 886 discussed the environment in/around WFO CAE between 1700 and 2100 UTC; Mesoscale discussion 884 focused on the High Plains (CIMSS Blog post on the High Plains convection).

SPC Storm Reports from 23 May 2022, along with Significant Tornado Parameter predictions from PHSnABI (left) and HRRR (right) valid at 2200 UTC (Click to enlarge); HWT CWAs on this day were WFO LBB and WFO CAE.
ProbSevere (Version 3) polygons superimposed on top of a 2-hour forecast of Most Unstable CAPE, all valid at 2200 UTC on 23 May 2022 (Click to enlarge)

A consistent feature of PHSnABI model output of instability over the course of the week was the accurate depiction of instability corridors, as shown above. Invariably, convection formed along the edge of those corridors, on the instability gradient.

Tuesday 24 May 2022

Without doubt this was the most active day of for HWT during this week (CIMSS Blog Post). Forecast offices were WFO MAF, WFO SJT and WFO FWD, a string of offices from the High Plains of Texas to north-central Texas. (Here’s the 1630 UTC Convective Outlook from 24 May.) The summary slide for this day is below. The 3 WFOs chosen this day are aligned with the corridor of stronger SigTor over the high plains of central Texas.

SPC Storm Reports from 24 May 2022, along with Most Unstable CAPE predictions at 1500 UTC (left) and SigTor predictions from PHSnABI, forecast times as indicated (right) (Click to enlarge); HWT CWAs on this day were WFO MAF, SJT and FWD.

For much of this day, I was watching what the forecasters assigned to the San Angelo WFO looked at. The image below shows the Day Cloud Phase Distinction as the strongest storm was starting to form near Tom Green County in west Texas (the country with the odd panhandle!). ProbSevere LightningCast nicely outlines the regions where initiation is ongoing; note the highest values are in a region with lightning observations. That strongest cell is at the intersection of two boundaries, one from southwest to northeast through the developing cell, and one extending east-northeastward from the cell (there’s a prominent wind-shift from southwest to northeast across the line).

Day Cloud Phase Distinction at 2000 UTC on 24 May 2022, along with GLM Observations of Flash Extent Density, and contours of ProbSevere LightningCast (Click to enlarge)

The two-hour forecast from PHSnABI, below, shows largest STP very close to where the convection is shown to be forming above. Note also how STP extends to the east-northeast along the boundary. STP more than once gave a 2-h forecast showing largest values very close to where convection developed, as in this case.

PHSnABI 2-h forecast of Significant Tornado Parameter valid at 2000 UTC on 24 May 2022 (click to enlarge)
3-h forecast of SigTor from PHSnABI, valid at 2100 UTC on 24 May 2022, along with ProbSevere object polygons valid at the same time (click to enlarge)

The largest hail (grapefruit-sized) was reported at 2118 UTC in Tom Green County, shortly after the image above. As on the 23 May, ProbSevere contours are aligned along the PHSnABI parameter, in this case SigTor. The image below shows SigTor predicted values enhanced along the boundary to the east-northeast of the strong storm that by 2200 UTC was east of Tom Green County.

GOES-16 Day Cloud Phase Distinction from 2200 UTC on 24 May 2022, and a 2-h forecast SigTor valid at 2200 UTC (Click to enlarge)

Gridded NUCAPS estimates of 850-mb temperature for this event over the high plains of Texas are shown below. 850-mb temperature north of Tom Green County are around 17oC; to the south they are closer to 23oC: this was a region of warm air advection.

850-mb Temperature fields, gridded from NOAA-20 NUCAPS observations, 1930 UTC on 24 May 2022 (click to enlarge)

Wednesday, 25 May 2022

The summary slide for this date, a much quieter day than 24 May 2022, is shown before (1630 UTC Convective Outlook). WFOs chosen on this day were WFO IWX, WFO MEG and WFO BHM. The tornado on this day (Storm Reports; summary from WFO MKX) was an EF-0 over southern Wisconsin, and SigTor at 2000 UTC on 25 May 2022, and a 4-h forecast valid at 0000 UTC on 26 May 2022 are shown below.

SPC Storm Reports from 25 May 2022, and SIgTor initial field (2000 UTC on 25 May) and the 4-h forecast, valid at 0000 UTC on 26 May (Click to enlarge)

I spent a lot of time on this day watching ProbSevere LightningCast fields over WFO BMX for a simulated Decision Support event related to lightning that is detailed by the NWS forecaster participant here. LightningCast probabilities over Lake Lurlene stayed at/below 50% while western convection moved around the event. Finally, convection moved in from the southwest. An accurate estimate of lightning offset occurred. I was also looking at a line of agitated cumulus moving toward Memphis from western Arkansas that ultimately did nothing. There were subtle features in both PHSnABI CAPE fields and SigTor fields that aligned with this line.

Thursday 26 May 2022

The summary slide for this date is shown below. On Thursday (1630 UTC Convective Outlook), three CWAs were chosen: WFO LMK, WFO GSP and WFO ILX.

Storm Reports from 26 May 2022 (left) and SigTor forecasts at 2200 and 2300 UTC on 26 May 2022 (click to enlarge)

I spent the beginning of the exercise with the Lincoln, IL forecasters; that CWA had mostly sunny skies. The toggle below shows the Day Cloud Phase Distinction at 1900 UTC (shortly after we all started looking at the weather) with the PHSnABI predictions of SigTor and CAPE. The PHSnABI forecasts definitely capture the back edge of the convective field over central Iowa. The strongest cell, isolated within the warm air over the eastern part of the ILX CWA, did eventually become warned as it moved along the border Indiana (Here’s a ProbSevere image from 2000 UTC — from this website). The readout of values within the radar-based object (from this website) are here. SPC storm reports show severe wind at 1947 UTC.

GOES-16 Day Cloud Phase Distinction, 1900 UTC on 26 May 2022, PHSnABI 1-h forecast of SIgTor (overlain with ProbSevere shapefile contours) and PHSnABI 1-h forecast of MUCAPE, both forecasts valid at 1900 UTC on 26 May 2022

Animations of both MUCAPE and SigTor from PHSnABI show features lifting northeastward, as observed.

In the Louisville CWA, widespread clouds were present. The PHSnABI estimate for CAPE, below, show a skinny region of CAPE entering the western part of the CWA.

PHSnABI estimates of CAPE from a forecast initialized at 1800 UTC, 00h – 03h forecasts (Click to enlarge)

I was curious about the region of no CAPE that develops in the northwestern part of WFO LMK at 2000 UTC (which apparently moves out of the LMK CWA by 2100 UTC). Is that convection that the PHSnABI has captured? The toggle below compares the GOES-16 Band 13 imagery, regional radar imagery (overlain with ProbSevere contours) and the predicted MUCAPE at 2000 UTC. The region of very small CAPE is very close to the observed radar convection. (It’s not quite so close in the 2100 UTC imagery.) Note that radar convection has a ProbSevere contour (here’s the image from the ProbSeverev3 website, with the readout for the radar object here), but the presentation from the GOES-16 imagery is not eye-catching. ProbSevere can help focus a forecaster’s attention.

Predicted MUCAPE at 2000 UTC (a 2-h forecast initialized at 1800 UTC), GOES-16 Band 13 Imagery, and regional radar valid at 2000 UTC (Click to enlarge)

The Hazardous Weather Testbed continues on 6 June. Kudos to Kevin Thiel, the SPC Satellite Liaison for GOES-R, and to Kristin Calhoun, SPC, for coordinating this event! For more blog posts from HWT, check out this blog!

GOES-16 GLM Lightning detection over Minnesota

May 12th, 2022 |

Wednesday, 05-11-2022, brought storm damage and copious amounts of lightning over Minnesota and parts of South Dakota, Iowa, and Wisconsin. The GOES-16 Geostationary Lightning Mapper (GLM) detected the flash extent density over these areas. A NEXRAD radar composite shows a large bow echo signature around 05-12-2022 01:25Z that spanned the entire lower half of Minnesota. Storms are still currently pushing through eastern Minnesota and northern Wisconsin and forecast to bring severe thunderstorms throughout the afternoon. There are also continuing threats of flooding in the Twin Cities and surrounding areas.

GOES-16 GLM Flash Extent Density and Band 13 reflectance on 05-12-2022 from 00:03 UTC to 16:43 UTC.
GOES-16 Band 13 reflectance with NEXRAD Reflectivity on 05-12-2022 from 00:05 UTC to 16:45 UTC.

The GOES-16 GLM Flash Extent Density product is available on RealEarth here. Near-real-time GLM visualizations are available as well as archived visualizations of GLM going back 3-4 days.

Using the Night Microphysics RGB and LightningCast probabilities to anticipate nighttime convection and Lightning

May 11th, 2022 |
Nighttime MIcrophysics RGB, 0616 – 0811 UTC on 11 May 2022 (click to enlarge)

The Nighttime Microphysics RGB, above, over central Wisconsin (that’s Green Bay at the northeastern edge, and southeast Minnesota/northeast Iowa over the southwestern part, of the animation), shows a field of low clouds stretching west-southwest to east-northeast. Note however, the occasional appearance of redder pixels within the field (as shown in this annotated image from 0806 UTC), especially in Wood and Portage counties (Click here for a map of Wisconsin counties). That kind of signal suggests that vertical cloud growth is occurring. Do you think convection will occur shortly? What about lightning?

NOAA-20 overflew this region shortly after 0730 UTC, and NUCAPS profiles would have become available in AWIPS at about the time of the end of the animation. What do they show? The image below shows 850-mb Temperature and the 850-500 mb lapse rates computed from gridded NUCAPS fields. The steepest lapse rates and strongest instability is centered on a NUCAPS profiles in central WI (in Adams County) which is just south of the band of clouds identifiable in the Night Microphysics RGB shown above: NUCAPS profiles show ample instability just south of this line (and winds are southerly: 0000 UTC Green Bay sounding).

850-mb Temperatures, 850-500 mb Lapse Rate, and Total Totals Index, 0730 UTC on 11 May 2022 (click to enlage)

The individual NUCAPS soundings in Adams County and Green Lake County, below, show very steep mid-level lapse rates.

NUCAPS Profiles in Adams County (left) and Green Lake County (right) at 0735 UTC on 11 May 2022 (Click to enlarge)

The GOES animation of Nighttime Microphysics above ended at 0811 UTC. What happened in the next 15 minutes? Note a continued development in the amount of reddish pixels! During these 15 minutes, radar is also showing increasing returns.

Nighttime Microphsyics RGB, 0811-0826 UTC on 11 May 2022 (Click to enlarge)

If convection is expected, lightning might also occur. Lightning Cast is a product in the NOAA/CIMSS ProbSevere portfolio, and it’s available online here, and a short training video is here. LightningCast probabilities for the same 15-minute span as above are shown below. Low probabilites are present until 0826 UTC. When do you think lightning might occur with this developing line?

LightningCast probabilities, 0811-0826 UTC on 11 May 2022 (click to enlarge)

The animation below follows the developing cells through the next 15 minutes — from 0826 to 0841 UTC. Nighttime Microphysics (overlain by radar: note the parallax shift, and also note the continued reddening of pixels in the RGB where convection is occurring) is on the left, and LightningCast Probabilities are on the right. Do you think lightning is imminent?

Nighttime Microphysics RGB overlain with 0.5 Base Reflectivity (left) and LIghtningCast Probability (right), 0826 – 0841 UTC (Click to enlarge)

The first GLM observations (with a CONUS time cadence of every 5 minutes) of lightning occurred at 0846 UTC, as shown in the animation of the Nighttime Microphysics RGB below. (Here is LightningCast at 0846 UTC).

Nighttime Microphysics RGB and GLM Flash Extent Density (FED), 0616 – 0851 UTC on 11 May 2022 (click to enlarge)

The animation below shows the NightMicrophysics RGB overlain with LightningCast Probabilities, from 0816 to 0846 UTC.

GOES-16 Nighttime Microphysics RGB with LightningCast Probabilities and GLM FED observations, 0816 – 0846 UTC on 11 May 2022 (click to enlarge)

Gridded NUCAPS fields for this blog post were created using the NOAA/TOWR-S Cloud Instance of AWIPS. Thank you! And here is a link to a presentation detailing how the Nighttime Microphysics RGB can be used in winter!

Hail in Portland OR

May 9th, 2022 |
GOES-17 Visible Band 2 (0.64 µm) imagery, 2201 UTC 8 May 2022 – 0311 UTC 9 May 2022 (Click to enlarge)

Here’s a text received late on 8 May from a kid: “Hail today in Portland”. The animation above shows GOES-17 Visible (0.64 µm) imagery between 2201 UTC on 8 May and 0311 UTC on 9 May. The follow-up text answering the obvious question (What time?) was “Around 5 PM” — that is, around 0000 UTC on 9 May. Infrared imagery (Band 13, 10.3 µm) from GOES-17 over the same time period — 2201 – 0311 UTC — is shown below. This loop uses a default enhancement from AWIPS (which enhancement has as its coolest temperature -109oC, perhaps too cold for this airmass; click here to see an animation with a coolest temperature of -90oC; variability in the cold cloud tops is much easier to visualize in that modified color enhancement).

GOES-17 Infrared Band 13 (10.3 µm) imagery, 2201 UTC 8 May 2022 – 0311 UTC 9 May 2022 (Click to enlarge)

The slower animation below, between 0000 UTC and 0100 UTC, highlights the cold cloud tops (west of Portand) of the system that might have produced hail. The eye is drawn to the developing cold cloud tops with the tweaked (non-default) enhancement. (By this time, having examined the imagery, I wonder about the report of the hail occurring around 5 PM; This event was also mentioned on the NWS Portland Facebook page).

GOES-17 Visible Imagery (left), Infrared (center, with default enhancement) and infrared (right, with a smaller range to the enhancement), 0000-0100 UTC on 9 May 2022 (click to enlarge)

LightningCast Probability is a product in the NOAA/CIMSS ProbSevere portfolio that predicts the likelihood of a GLM Flash Event based on a single time of the GOES-17 bands that are used in the Day Cloud Phase Distinction RGB: Bands 2 (0.64 µm), 5 (1.61 µm) and 13 (10.3 µm). The animation of that field is shown below. Contours denote probabilities of 10% (dark blue), 25% (cyan), 50% (green) and 75% (magenta). One lightning flash is shown at the of the animation; note however how the probability contours center on the strongest developing convective cell early in its lifecyle — even though it never produced lightning as detected by the GOES-17 GLM.

LightningCast Probability, 2335 UTC on 8 May 2022 – 0100 UTC on 9 May 2022 (click to enlarge)

NOAA-20 overflew the Pacific Northwest in the afternoon, with two passes over Oregon, as shown in the toggle below that also shows gridded 850-500 mb NUCAPS Lapse Rates at 1933 and 2113 UTC on 8 May. Even though the westernmost NOAA-20 has truncated data, very steep lapse rates — near 8o C/km — are evident.

Gridded 850-500 mb Lapse Rates, 1933 and 2115 UTC on 8 May 2022 (click to enlarge)

500-mb temperatures are shown below, with Portland deep within the cold air (500-mb temperatures are at/below -30o C!). The gridded fields look smooth despite the abundance of yellow and red points in the NUCAPS fields, designating regions where the infrared retrieval did not converge (yellow) or where the infrared and microwave retrievals both failed! This example shows that profiles that do not converge because of low-level clouds/moisture/rain may nevertheless produce useful upper-air information. The 2113 UTC 500-mb temperature field here, shows a red profile in the Willamette Valley in the northernmost row of profiles, and a green profile in the same row just west of the Oregon Coast. The toggle of profiles at those two points is shown below; both have useful information around 500 mb (and above) even though near-surface values in the red profile are of dubious value. Note the steep lower-tropospheric lapse rates in the sounding that is just offshore!

Gridded 500-mb Temperature derived from NUCAPS profiles, 1933 UTC and 2115 UTC on 8 May 2022 (click to enlarge)
NUCAPS profiles at circled (in black) locations, 2138 UTC on 8 May 2022 (click to enlarge)

NUCAPS imagery was created with the NOAA/TOWR-S AWIPS Cloud instance. Thank you!