A weakening Pacific trough brought some snow to portions of the Four Corners region.
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The episode as NWS GJT wrote it up.
A weakening Pacific trough brought some snow to portions of the Four Corners region.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Grand Junction, CO wrote its last area forecast discussion before the first event at Dec 31, 4:06 AM MST, 1 hour 54 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 406 AM MST Sat Dec 31 2016 .SHORT TERM...(Today through Sunday) Issued at 406 AM MST Sat Dec 31 2016 This morning's synoptic pattern featured a broad trough over the Upper Midwest, a closed low pressure system over the northern CA coast, and another low centered near Las Vegas. According to latest models, the formerly closed low over Las Vegas appeared on track to bring snow and some rain to southeast UT and Southwest CO today and into tonight. Meanwhile, areas north of the Abajo and San Juan mountains will see increased clouds, but no chance for precipitation. Latest mosaic of radars indicated precipitation just beginning to push into southeast UT. Surface observations reported lowering clouds over Blanding, UT with a mid-level cloud deck over southwest CO. Precipitation will spread from southeast UT and southwest CO as the low drifts eastward across northern AZ and northern NM as an open wave trough. The 7H low associated with this system passes just south of the UT/CO border which, when combined with 7H specific humidity a juicy 3.5 to 4 g/kg, improves precipitation chances across these areas. Consequently, raised PoPs significantly, especially during the morning period. As mentioned in previous discussions, lift, both dynamic and orographic not all that impressive with this system so kept snow accumulations pretty light. Snow levels rise to near 6000 to 6500 feet during the afternoon which will limit accumulations for lower elevations. After a lull this evening, precipitation will redevelop across southeast UT and southwest CO later tonight, mainly as snow, as the closed low over northern CA drops southward to southern CA. Models then take the low eastward New Years Day moving it over the border areas of southern AZ and NM. As the system shifts east it opens and phases with a weak shortwave trough ejected from another low pressure system over the Pacific Northwest. Dynamic lift provided by jet level divergence on the nose of the 135 kt polar jet combined with increased orography and and positive vorticity advection will cause snow to spread into the central mountains and adjacent valleys. At this time, does not appear additional snow accumulations warrant winter weather highlights. Today's temperatures will be a bit cooler, especially across the south due to clouds and precipitation. Meanwhile, areas to the north will be impacted more moderately, but should also be a bit cooler. Tonight's lows should be just a bit more moderate, though inverted valleys like Gunnison and Craig will remain quite cold. The passing shortwave trough mentioned previously may generate sufficient wind to mix out the inversion over the Gunnison Basin so went along with more moderate highs provided by model guidance. .LONG TERM...(Sunday night through Friday) Issued at 406 AM MST Sat Dec 31 2016 Activity will become more widespread Monday under the influence of the polar jet. Available moisture and upper level support will generate light to moderate snow showers for the mountains with some significant accumulations possible. The chance for showers, with periodic breaks, looks to continue through at least midweek as a series of embedded waves move across the area. A strong cold front will push through on Thursday and leave an arctic airmass in its wake. More on that below. Behind the front, models show dry northwesterly flow setting up. Temperatures for the extended forecast ended up being one of the bigger challenges. While the first push of arctic air looks to arrive by Tuesday, the extent of its reach depends heavily on how far south the upper level trough drops. A second, more potent, shot of cold air is indicated to move in by Thursday as the axis of the trough and associated cold front treks across the CWA. Temperatures behind the front were previously progged to drop well below normal for the latter half of the work week. However, latest model guidance not as bullish with the intrusion of Arctic air. Understandably, confidence in temperature forecast during the latter part of the forecast period remains low. Regardless, a transition to colder days does appear to be on track for the first week of the new year. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 406 AM MST Sat Dec 31 2016 A Pacific storm system will pass south of the UT/CO border area during the day before pushing east of the Continental Divide around 00Z/Sun. Impacts to TAF sites will be limited to KDRO and possibly KTEX. At KDRO, snow will break out around 15Z causing CIGS to lower below ILS breakpoints with IFR VSBY. Brief LIFR conditions are possible. There is a 30 to 40 percent chance for snow at KTEX, but it is more likely that CIGS will approach ILS breakpoints during the day. Snow chances will be significantly reduced for KDRO and KTEX after 00Z, but another Pacific storm will extend the potential for snow at KDRO into the night. The remaining TAF sites are not expected to be impacted by the systems discussed previously, therefore expect VFR conditions to persist. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...NL LONG TERM...TGJT AVIATION...NL
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
The national radar mosaic for the moment the first event began.
1 winter weather. Local standard time, as filed.
Up to 2 inches was measured above the 5000 foot level, including the Blanding area where the roads became snowpacked.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2016Every state in 2016This day in weather historyWarnings in Utah, December 2016
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 702142.