Sunday, February 9, 2014
Temperatures have warmed as forecast, and I had 3” of wet and heavy snow on my deck this morning, though most of that fell last evening before midnight. The Steamboat ski area reported 7” mid / 6” top at 5am, with 4” of that coming yesterday. As of 11am, only an additional 1” was reported at mid mountain, though some sort of light precipitation is still falling on the hill.
As I mentioned in the last forecast blog, I still don’t expect better quality snow until tonight when the atmosphere finally sees some cooling ahead of a well defined wave that passes over the area on Monday. There is not a lot of cool air associated with this wave, and temperatures are again expected to oscillate around the its arrival, but I would expect 4-8” to be reported by Monday morning with an additional 4-8” by Tuesday morning, with most of that occurring during the day Monday.
Snow looks to mostly end by Tuesday morning, though light showers may reoccur on the hill by the afternoon. Temperatures will warm again on Wednesday in advance of another possible long-duration event beginning later in the day. As in the last storm cycle, this event is forced by a warm and moist polar jet heavily modified by subtropical moisture and warmth. I would expect similar results to this storm, with Thursday and Friday being warm and windy with snow before some cooling occurs later Friday or early Saturday. Snows look to continue through most of Saturday before a quick moving ridge warms temperatures further by the end of the weekend.
Weather then turns dry for a few days before there is general model agreement of a storm for around midweek.
Saturday, February 8, 2014
The Steamboat ski area reported 3” mid and 3.5” top at the 11am update, and I see light snow on the upper mountain looking out my window. This weather pattern continues to make the forecast difficult for Steamboat as atmospheric temperatures are expected to stay mostly static or slightly warm until Sunday evening when some cool air finally works into the area. I’m inclined to dismiss what I consider the wildly optimistic Denver forecast of 22-36” by Sunday night for the Gore range and side closer to the saner 16-20” forecast for the Park range by Monday afternoon from the Grand Junction office.
We will get some snow in this pattern, but it will be heavy and wind-affected. And if valley temperatures rise much further, which they are forecast to do, we may even see the ‘R’ word (rain) down here by tomorrow. Since about 3” has already been reported, I would expect 4-8” to be reported by tomorrow morning. While light snow will continue during the day Sunday on the mountain, moderate to heavy snow will likely accompany the front bringing the cooler air into the region Sunday evening.
Snows will continue Monday and taper off by Tuesday morning. I would expect 6-12” by Monday morning, with an additional 3-6” reported by Tuesday morning.
Temperature will warm again by Tuesday afternoon ahead of the next wave currently timed for midweek. There is model disagreement with respect to the strength of this wave so snowfall amounts are uncertain at this time. The moist and relatively warm polar jet is forecast to continue over out area through the workweek and into the weekend keeping warm and unsettled weather over the region.
Thursday, February 6, 2014
The Steamboat ski area reported 1” mid / 2” top early this morning, and the 11am update had an additional 1” mid / 2” top falling between 5am and 11am. We currently have cold air near the surface being overrun by northwest flow contained within a moist and relatively warm branch of the polar jet. Forecast snow amounts will be tricky as two different physical processes compete. Generally, a warming airmass in the mid-levels is not conducive for significant snow accumulations as the warming increases stability and decreases relative humidity. However, this relatively warm airmass is being lifted over the cold air entrenched in the Yampa Valley, and this extra ingredient means light snow accumulations will continue. I might expect a 3-6” report by tomorrow morning.
Continued light snow should occur through Friday before an embedded wave races by to our north Friday night. This will bring some cooling to the atmosphere, increasing snowfall rates through early Saturday before the atmosphere warms again earlier in the day, likely ending snowfall for a very brief period. Snow accumulations may be in the 4-8” range by Saturday morning.
Atmospheric temperatures are then forecast to hold mostly steady through Sunday even as valleys likely warm above freezing on that day. Light snow should redevelop by Saturday afternoon and persist Sunday before another stronger wave passes over the area late Sunday or early Monday. Probably another 3-6” by Sunday morning, and 8-16” spread between the Monday and Tuesday morning reports. The timing of the Sunday night/Monday wave will be refined in later model runs and will determine whether significant snows occur early enough to be included in the Monday morning report.
Snows will likely end for a short time sometime on Tuesday before another embedded wave in the persistent northwest flow will repeat the above pattern midweek.
Tuesday, February 4, 2014
Snows are forecast to continue for the next week, and long term models indicate an active pattern for much of February will follow this week’s accumulations.
The Steamboat ski area reported 2” / 3” at mid/top this morning which fell during the day Monday and made yesterday’s skiing excellent. As of 11am, the updated report has an additional 1” / 7” (!!) at mid/top, so I expect continued great skiing today.
Snows will decrease by tomorrow morning after another 3-6” falls mostly this afternoon and into the overnight hours, leaving a 3-6” report at mid and a 8-12” report at the summit by Wednesday morning. Very cold air from Siberia captured in cross polar flow splits as it flows across Canada creating a broad zonal (east-west oriented) flow that keeps what is forecast to be an active polar jet stream near us. There may be little or no breaks in the snow as persistent light to moderate snowfall is projected to continue over our area Thursday, with 2-5” of snow forecast for Friday morning.
Lighter snowfall will continue early Friday before a well defined wave in moist and cool northwest flow increases snowfall rates by later in the day. This wave will bring a cold front with increased snowfall though the area early Saturday before snows taper off through the day and end by the evening. The timing of this cold front will determine when most of the snow falls, but I would expect 6-12” when both Saturday and Sunday morning reports are added.
Snowfall will pick up again Sunday as another wave embedded within the northwest oriented polar jet approaches. Cool air arrives later Sunday increasing snowfall rates further, and snowfall is expected to become heavy by Sunday night or Monday morning, and persist until Tuesday morning. We should do quite well from this pattern, seeing around 8-16” reported when both Monday and Tuesday’s reports are added.
Long term models keep a zonal polar jet with embedded disturbances over or near our area through at least mid-February keeping an active and more or less snowy pattern throughout.
Sunday, February 2, 2014
After a beautiful day today, a couple of complex storm systems will affect our area this workweek and this weekend. Another very cold wave rotating around the Hudson Bay vortex will force the low currently just off the northern California coast to drop southeastward along the coast today and then westward along the Old Mexico border Monday. We may see some snow showers during the day tomorrow as the upper level flow backs to the southwest, moving moisture and warmer temperatures into our area.
I don’t expect much accumulations from this until the very cold wave mentioned above approaches our area early Tuesday. Temperatures should fall through the day and snow increase as the very light winds turn to our favored northwest direction. Even though wind speeds will be low, I expect signficant accumulations by Wednesday morning as the snow will be of very low density - maybe as much as 6-12”.
Current forecasts have this Hudson bay wave mixing with some newly arrived Siberian air and briefly cutting off from the main flow over the Washington / Oregon area by Thursday. The end result is the bitterly cold temperatures on Wednesday will moderate a bit as the flow once again backs to the west and warms. But snows are unlikely to take more than a brief break as bits of energy ejecting from this spinning low to our northest will keep showers going.
Models then have Pacific energy phasing with this spinning storm creating a powerful storm that is currently forecast to move over our area late in the workweek or early in the weekend. Very substantial accumulations are expected before current iterations of the models then indicate a hemispheric pattern change to warmer and more zonal (east-west oriented) flow.