A ridge of high pressure moved into the desert southwest in the wake of a strong winter storm system that impacted the region last weekend. Strong low level inversions beneath the ridge and melting snow cover increased the potential for an extended period of low clouds and freezing fog. The MODIS Nighttime Micropyhsics product valid at 0501 UTC November 29, 2013 showed low clouds and possible areas of freezing fog along the I-70 corridor over and west of Grand Junction. Observations at Grand Junction verified IFR low clouds at 900′ with visibilities above 6 miles. The following VIIRS Nighttime Microphysics product at 0904 UTC November 29, 2013 showed low clouds and freezing fog expanding eastward into the Colorado, Gunnison, and Uncompahgre River Basins and the Grande Valley south of Grand Junction. Visibilities have been significantly reduced to 1/4 mile at Montrose and farther south at Cortez. The ceiling at Montrose is 200′ with visibility at 3/4 mile. The nighttime microphysics product shows exceptional detail within the narrow valleys along Roan Creek to the northeast of Grand Junction. Notice the fog and low cloud deck is very close to Rifle at 0904 UTC but the observation still suggests clear skies. 31 minutes later at 0935 UTC the observation at Rifle dropped to LIFR at 400′ however visibilities remained at or above 6 miles.
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A strong winter storm system that impacted NM over the weekend delivered the first round of significant widespread snowfall for the 2013-2014 winter season. Major impacts to travel were reported across much of the area along with record to near record cold temperatures. The VIIRS DNB Reflectance imagery after the storm showed several interesting features over the area. Crisp city lights over central and eastern NM on top of areas of light yellowish reflectance values contrast the more blurred city lights over western NM with the same light yellowish reflectance. The VIIRS Nighttime Microphysics from the same time provides much better insight into what is happening over the region. Thick low clouds are detailed very well over western NM while central and eastern NM remain clear.
The MODIS Snow Cloud RGB product dives even deeper into the story. Much of central and eastern NM are snow covered and several well defined snow bands can be seen. There are even some low clouds still hanging tough over northwest NM. The composite radar reflectivity from the 24th shows how these snow bands set up over the area. Minor impacts to aviation occurred over western NM as MVFR conditions impacted Farmington and Gallup with 12 to 24 hours of broken ceilings.
The explosive Rim Fire in California has garnered significant media attention across the world as it burns within portions of Yosemite National Park. Satellite imagery of this incident over the past few days has provided some stellar images of the wildfire smoke plume and hotspot. In particular, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on board the Suomi National Polar-orbiting Partnership (NPP) satellite that observes the Earth and atmosphere at 22 visible and infrared wavelengths has produced several stunning images. The first image below is the VIIRS True Color RGB product showing the Rim and American Fires at 252pm PDT August 26, 2013. This imagery provides a “true color” view of the landscape as viewed from above. Smoke from these fires can be seen in thick shades of brown.
The following image is the VIIRS day-night band (DNB) Reflectance product. This imagery illustrates a night-time image of reflected and emitted light, but with the resolution of day-time visible imagery. Analogous to how visible imagery uses reflected sunlight, the DNB uses reflected moonlight to see small-scale features at night that are not as readily seen in standard infrared satellite channels.
Numerous showers and thunderstorms over eastern NM on Wednesday, July 31, 2013 left behind significant atmosphere moisture and wet soils over the region. A low cloud deck that was expected to develop over eastern as indicated by several guidance members did not pan out. The day shift aviation forecaster anticipated broken low cloud development at the Las Vegas (KLVS) TAF site around 10Z Thursday, August 1, 2013. The following shift continued to mention the MVFR low cloud ceilings on the 06Z TAF cycle. The 850-700mb layer humidity from the 08Z RUC13 model still indicated low cloud development over much of eastern NM (Figure 1). A VIIRS satellite pass at 0816Z across this region indicated low cloud development was not occurring around Las Vegas. The hybrid 11-3.9micron imagery at this time showed a mixed area of low and mid level cloud cover as indicated by the blue and yellow pixels over northeastern NM and southeastern CO (Figure 2). The Colorado Springs, CO observation supports the low cloud deck at 2,200′ where a widespread area of yellow is observed. The VIIRS Reflectance RGB imagery (Figure 3) indicates cloud cover over this area but does not offer much information about its thickness or height on first inspection. There are a few interesting features in this image including lightning flashes over eastern NM and city lights around Colorado Springs. The low cloud cover in this area must then be very thin. The NT Microphysics shows the most significant amount of detail in this area. The low clouds clearly stand out from the mid level cloud deck over the entire region. Given the lack of low cloud development based on satellite imagery and observations, the KLVS TAF was amended to remove the mention of a broken MVFR cloud deck prior to the issuance of the 12Z TAF cycle.
The Four Corners region is no stranger to poor radar coverage. The lowest slice on the Albuquerque radar is roughly 15,000′ above ground level. The radar image shows despite the site reporting light rain there is no reflectivity present. The VIIRS nighttime microphysics image from 0753UTC on July 17, 2013 shows where a well defined area of mid level clouds and the associated showers are moving across the area. The traditional GOES 11-3.9 micron imagery shows very little detail to this cloud feature and does not provide a clear picture between low, mid, and high level cloud cover. We can use the nighttime microphysics imagery to infer that there are showers across this region not seen on radar. The cloud cover and visibility were not low enough to impact aviation across this area however overcast skies and brief showers lingered through sunrise.
The VIIRS DNB Radiance and Radiance RGBs showed an increase in fire activity on the night following record high temperatures and unstable conditions over northern NM. The Thompson Ridge Fire is nearly 22,000 acres, the Tres Lagunas Fire 10,000 acres, and the newly started Jaroso Fire is approximately 1,000 acres. The DNB products showed the increased radiance between Monday, June 10th and Tuesday, June 11th, especially for the Tres Lagunas Fire. The new Jaroso Fire to the north of Tres Lagunas is clearly visible on the nighttime product on the morning of the 11th. Some cloud cover is also visible on the Radiance RGB to the north of the Thompson Ridge Fire on the 11th.
NWS ABQ continues to research the MODIS RGB airmass imagery and its potential to improve prediction of significant fire weather, wind, and dust events across New Mexico. The MODIS satellite captured a stunning example of a dynamic dry slot within the base of a strong mid latitude cyclogenesis over the central Rockies. Blowing dust in association with the strong jet core sliding directly over eastern NM produced very hazardous conditions for much of the afternoon. The lead meteorologist from Cannon Air Force Base reported visibilities down to around 100 yards at times with the sky completely obscured for roughly 5 hours. This was the worst dust storm for the region that he could remember going back to 2006. He also mentioned the region is about as close to the Dust Bowl as he can imagine with essentially no top soil left after multiple strong wind events already this season and persistent severe to extreme drought.
The heaviest snowfall from the blizzard of February 24-25, 2013 can still be seen on satellite imagery across portions of east central NM. The 1km True Color imagery shows a very well defined area where the heaviest snowfall occurred and the 500-meter Visible imagery from this same area details some interesting terrain features. The satellite images were posted as a Graphicast today and shared via Facebook. The snow pack is still having a significant influence on humidity and temperature forecasts in this area and forecasters continue using the imagery to provide greater accuracy. The snow cover imagery validated the 12 hour snowfall forecast during the heart of blizzard conditions with exceptional accuracy. Snowfall amounts were slightly less than forecast however the areal coverage was pinpointed very well.