Overlapping 1-minute Mesoscale Domain Sectors provided GOES-16 (GOES-East) imagery at 30-second intervals over the Mid-Atlantic states on 20 January 2023 — and Mid-level Water Vapor (6.9 µm) images (above) revealed widespread mountain waves east of the Appalachians (produced by strong westerly flow interacting with the terrain). There were numerous pilot reports of light to moderate turbulence associated with these mountain waves.

The 1200 UTC Water Vapor image with plots of rawinsonde sites (below) indicated that Sterling, Virginia KLWX (which replaced the Washington-Dulles site KIAD) was located within the region of drier air where mountain waves were prevalent at that time.

Plots of GOES-16 Water Vapor spectral band (08, 09 and 10) weighting functions calculated using 1200 UTC rawinsonde data from Washington-Dulles, Virginia (KIAD) are shown below — due to the presence of dry air throughout the middle and upper troposphere over that location (Skew-T plot), the water vapor weighting functions were shifted to lower altitudes; the peak of the 6.9 µm (Band 09) weighting function was at the 617.5 hPa pressure level, with significant upwelling radiation contributions originating from as low as the 700 hPa level.

30-second GOES-16 “Red” Visible (0.64 µm) images are shown below.

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GOES-18 Clean window infrared imagery (10.3 µm, displayed at full resolution in a special sector over American Samoa, in the latest AWIPS build) shows an area of convection, within a region of abundant moisture (GOES-18 Total Precipitable water values are close to 2.5″), approaching the Samoan islands (that are located in the center of this domain). The Pago Pago sounding from 1200 UTC on 20 January is shown below, (from this site), and it also shows moisture (2.15″) over the island. Moisture behind the remains of tropical cyclone Irene are affecting Fiji in this image (Heavy Rains/flooding warnings are occurring), and at the far western edge of the domain, high clouds associated with Invest 92P are apparent.

GOES-18 Level 2 Total Precipitable Water is computed only where clear skies are present. Total Precipitable Water can also be estimated using microwave data; microwave-derived MIMIC total precipitable water fields are shown below. The cyclonic circulations of Irene (passing between New Caledonia and Fiji on 18-19 January) and the developing 92P (near New Caledonia at the end of the animation) are apparent.

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How likely is the tropical development of the disturbed weather over Samoa into a tropical cyclone? Wind shear values from the SSEC/CIMSS Tropical site, shown below, show a region of small shear over the Samoan islands, moving west with time. However, development is not anticipated; the chief threat for this region is likely persistent rains.

The area of disturbed weather (Invest 92P) between Australia and New Caledonia has a moderate to strong possibility of strengthening into a tropical storm, per the RSMC in Fiji, shown below (from this link).

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GOES-18 imagery in this blog post was created using a cloud instance of AWIPS from TOWR-S. Thank you!

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The Storm Prediction Center’s Convective Outlooks for late afternoon on 19 January 2023 contained a region of Enhanced Probabilities for Severe weather (primarily for wind) over portions of Ohio, as shown above. The chief difference between the 1630 and 2000 UTC outlooks was the extension of the Enhanced region to the north/northeast by a county or two at 2000 UTC. The unusually strong convection (for January!) that developed over Ohio on 19 January 2023 did cause a large swath of wind damage as shown by the SPC Storm reports below, mostly in the northern part of the Enhanced Risk. Most of the winds reports occurred between 2200 UTC on 19 January and 0100 UTC on 20 January, and most were within the Cleveland, OH, County Warning Area (CWA). What kind of satellite data could have been used on 19 January for situational awareness as the storms developed?

The toggle above shows thermodynamic fields from NUCAPS profiles from a NOAA-20 overpass just after 1800 UTC. Clear skies (as suggested by the green dots in the AWIPS display) prevailed over much of Indiana and Ohio at this time. The steepest low-level (that is, 850-700 mb) lapse rates were centered over the central Indiana/Ohio border; the largest Total Totals index values, however, were a bit farther north.

Because skies were clear, GOES-16 Derived Stability Indices gave information/could be used on this day. The animation below combines GOES-16 Band 13 imagery (for cloudy regions) and the derived Lifted Index in clear regions. For both of these fields, the default AWIPS enhancements were changed (because, in part, it’s January!) The coldest Band 13 brightness temperatures were -80^oC (vs the default -109^oC) and the Lifted Index is scaled from 0-12 (vs. the default of -10 to 20). It is revealing that the smallest Lifted Indices (around 1 or 2) occur in the northern half of the Enhanced Risk polygon as the convection moves into western/central Ohio. (Here is a still image from 1951 UTC, two hours before the onset of convective wind reports). Could the satellite-diagnosed lower stability in the northern part of the Enhanced Risk (relative to the southern part) help in situational awareness, especially when combined with the NUCAPS snapshot shown above?

Derived CAPE, shown below (and scaled to just 0-50) shows a small region of positive CAPE over north-central Ohio around 2100 UTC.

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Note that the AWIPS default was changed in all the GOES-16 imagery/derived products shown above! Do not always rely on defaults. NUCAPS figures for this blog post were produced using the Product Browser on a TOWR-S Cloud Instance of AWIPS. Thanks!

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True color imagery from the CSPP Geosphere site, shown above (click here for a direct link to the animation), depicts the sudden appearance and equally sudden ending of a small fire on the Texas Gulf Coast in Jefferson County, east-northeast of Houston.

The Fire Temperature RGB also shows the quick development (and cessation) of the fire; this RGB is a good situational awareness tool, as it shows an obvious color change (related to the increase in emissions of shortwave radation) when the fire initiates.

GOES-R has derived products that quantify aspects of the detected fire, as shown in the four-panel image below from 1731 UTC, near the time when the fire was most intense. Note the contributions of the red and green components of the RGB, from the 3.9 µm and 2.25 µm channels, respectively, on GOES-16, have maximized in the center pixel, so that pixel is yellow in the RGB (red + green in an RGB yields yellow); had the 1.61 µm emissions been stronger (that is, had the fire been hotter), the pixel would look whiter. The Fire Products (Area, Temperature, Power) are most useful as data assimilated into models that might simulate the evolution of the fire, or the distribution of smoke.

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The Fire Temperature RGB is one of the few RGB products in AWIPS that has a gamma adjustment. A gamma adjustment alters how the ranges of input values (in this case, 3.9 µm brightness temperatures) are displayed. For the Fire Temperature RGB, the warmest parts of the 3.9 µm brightness temperatures occupy proportionally more of the display space in the RGB, and the cooler parts of the RGB (where fire is unlikely, yet information is still needed!) occupy less.

AWIPS allows a gamma adjustment to be altered (using the ‘Composite Options’ window). The toggle below compares the default RGB to one in which the Band 7 Gamma adjustment has been changed to Gamma = 1, resulting in a very red image (because cooler brightness temperatures — that are not that relevant to the detection of fire — are more emphasized).

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Note: AWIPS users might note that the default Gamma of the RGB is 2.5, but the Quick Guide shows the Gamma to be 0.4 (that is, 1/2.5)! This may be a source of confusion. This website shows a Gamma modification of 1/Gamma — and if Gamma is 0.4, that exponent becomes 2.5, which is what AWIPS shows.

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