Ice floes in Chesapeake Bay

Landsat-8 false-color RGB image [click to enlarge]

Landsat-8 false-color RGB image [click to enlarge]

In the wake of the explosive cyclogenesis off the East Coast of the US on 04 January 2018, very cold air began to spread across much of the eastern half of the Lower 48 states. Focusing on the Hampton Roads area of southeastern Virginia, satellite imagery began to show the formation of ice in the rivers and bays. On 06 January, a 30-meter resolution Landsat-8 false-color Red-Green-Blue (RGB) image viewed using RealEarth (above) revealed some of this ice — in particular, long narrow ice floes (snow and ice appear as shades of cyan) that likely emerged from the Back River (northeast of Hampton) and were drifting northward and southward just off the coast of the Virginia Peninsula.

On the following day (07 January), 250-meter resolution Terra MODIS true-color and false-color RGB images from the MODIS Today site (below) showed that a larger V-shaped ice floe was located just southeast of the Peninsula, with its vertex pointed toward the Hampton Roads Bridge-Tunnel (HRBT). Snow and ice also appear as shades of cyan in the MODIS false-color image.

Terra MODIS true-color and false-color RGB images [click to enlarge]

Terra MODIS true-color and false-color RGB images [click to enlarge]

07 January also happened to be the last full day of imagery to be broadcast by the GOES-13 satellite — a comparison of 1-minute Mesoscale Sector GOES-16 (GOES-East) Visible (0.64 µm) and 15-30 minute interval GOES-13 Visible (0.63 µm) images (below) showed that the V-shaped ice floe continued to drift southwestward toward the HRBT. However, it was difficult to tell whether the ice feature made it over and past the tunnel; even with the improved GOES-16 Visible spatial resolution (0.5 km at satellite sub-point, compared to 1.0 km for GOES-13) and the 1-minute rapid image scans, the ice floe became harder to track during the afternoon hours before high clouds began to overspread the region.

"GOES-16

GOES-16 Visible (0.64 µm, left) and GOES-13 Visible (0.63 µm, right) images, with hourly surface air temperatures (ºF) plotted in yellow [click to play MP4 animation]

However, a close examination of Suomi NPP VIIRS true-color and false-color images at 1826 UTC (below) indicated that some of the ice had indeed moved westward past Fort Monroe (on the far southeastern tip of the Peninsula) and over/past the HRBT.

Suomi NPP VIIRS true-color and false-color RGB images [click to enlarge]

Suomi NPP VIIRS true-color and false-color RGB images [click to enlarge]

On the topic of cold temperatures in southeastern Virginia, a new daily record low of -3 ºF was set at Richmond on the morning of 07 January, and at Norfolk new daily record low and record low maximum temperatures were set (10 ºF and 23 ºF, respectively).

End of Holiday Break Ski Report

Today marks the last day of holiday break at the University of Utah with classes starting tomorrow. 

For the last day of break, the skiing at Alta today was just fine.  It is quite remarkable what a few inches of right-side up snow can do.  Plenty rocky and bony off piste, but the groomers were fine and the weather was as nice as it can get in early January.  I have friends who like to say "if you can't ski good, ski fast," so that's what we did. 


With beautiful clear skies in place, I could have taken a photo of the valley fog or pollution for the weather lesson of the day, but like you, I'm sick of it.  Instead, here are some wimpy cumulus clouds that formed over the south-facing wall of Little Cottonwood Canyon where it is likely that surface heating was driving upslope flow. 


The low sun angle this time of year can sometimes drive a cross-canyon flow as the north-facing side of the canyon remains in the shade, whereas the south-facing side is heated.  Just one thing to look for on days when the large-scale flow is weak and skies are clear.

I took a quick look at the SNOTEL data today and noticed Snowbird has the lowest snowpack water equivalent in the 29-year history of the site.  Data does not extend back to the 76-77 drought season, but I suspect that season will still beat us for worst year on record.  Basically, we're about a month behind, as the 7.2" of water at that site today is the median in the 29-year record on 7 December.  This year, January is the new December.   Let's hope February isn't the new December too. 

Given the limited snow, hats off to the snowmakers and the groomers for their efforts during the holiday break.  I resort skied twice during the holidays and both times conditions were better than expectations.  I did quite a bit of nordic skiing and found conditions at Mountain Dell and Jeremy Ranch to be quite fun.  By and large, it was a good break.  Meteorologically, the big cyclone event also served up a great case for new material for my class this semester.  Students had better be ready!