CIMSS Turbulence Fields changed

May 27th, 2022 |
GOES-17 Band 8 (“Low-level water vapor”) Infrared (6.19 µm) fields, 1910 UTC on 27 May 2022, along with derived Turbulence Probability for 30-33 kft, 34-37 kft, 38-41 kft (Click to enlarge)

At the request of AWC and WFO HNL, the turbulence probability fields for AWIPS have been changed (the website — here — is unaltered as of now). The turbulence probability is split into 3 layers that are each 3000 feet thick: 30000-33000 feet ; 34000-37000 feet; 38000-41000 feet. The AWIPS plugin used to display the information has also been changed, so that contours are drawn, as shown above. This will affect AWIPS performance if you are displaying the full disk imagery (because there are so many contours to draw!)

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!

High-altitude turbulence over the Southern Plains

May 25th, 2022 |

GOES-16 Upper-level Water Vapor (6.2 µm) images, with pilot reports of turbulence (cyan) — with and without contours of RAP40 model Maximum Wind Speed (yellow) [click to play animated GIF | MP4]

GOES-16 (GOES-East) Upper-level Water Vapor (6.2 µm) images with pilot reports of turbulence — with and without contours of RAP40 model Maximum Wind Speed (above) showed an anomalously-deep 500 hPa trough over the Southern Plains, where there was an anomalously-strong 250 hPa jet streak developing along its forward (eastern) edge. A number of pilot reports of moderate to severe turbulence were seen within the exit region of this jet streak.

In GOES-16 Upper-level Water Vapor images with and without an overlay of a Turbulence Probability product (below), higher probability values were apparent in the area near/along the axis of the 250 hPa jet streak (and the related pilot reports of turbulence).

GOES-16 Upper-level Water Vapor (6.2 µm) images, with pilot reports of turbulence (cyan) — with and without an overlay of Turbulence Probability [click to play animated GIF | MP4]

View and animate GOES-16 and GOES-17 Full-Disk IFR/Low IFR Probability fields in RealEarth

May 25th, 2022 |

GOES-16 and GOES-17 Full-Disk IFR and Low IFR Probability fields are now available in RealEarth. IFR (Instrument Flight Rules) Probability estimates the likelihood that IFR conditions are occurring. You can view and animate real-time satellite IFR probability in RealEarth.

Finding IFR and Low IFR fields in RealEarth for GOES-16 and GOES-17 full disk.
Comparing GOES-17 IFR and Low IFR for 05-25-2022 at 15:10UTC, and animating GOES-17 IFR fields in RealEarth over Hawai’i for the last 12 available GOES-17 time steps (10-minute resolution from 13:10 to 15:20UTC).