Cold high pressure over the Four Corners brought a 3rd consecutive night of widespread freezing temperatures to some lower valleys in southwest Colorado.
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The episode as NWS GJT wrote it up.
Cold high pressure over the Four Corners brought a 3rd consecutive night of widespread freezing temperatures to some lower valleys in southwest Colorado.
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 May 19, 10:02 PM MST, 4 hours 7 minutes earlier.
Area Forecast Discussion National Weather Service GRAND JUNCTION CO 1102 PM MDT Fri May 19 2017 .SHORT TERM...(Tonight through Saturday night) Issued at 225 PM MDT Fri May 19 2017 The upper level low responsible for producing significant snowfall across the mountains and northern valleys the last couple days is slowly shifting eastward, and weakening as it does. The center of this low circulation is hard to pinpoint exactly, but seems like it is centered along the central divide (near Vail to Monarch Pass vicinity). Some moisture is still rotating around the broad circulation with the bulk of the energy directed over the Plains, but overall appears disorganized across the western slope. Some convective showers are occurring, but seems hit or miss and not very widespread. A couple inches of snow are possible over the northern and central higher terrain through this evening but roads should remain wet where showers fall and according to webcams are dry elsewhere, as enough sun is breaking through the clouds to help melt snow on the pavement as it falls. Previous winter highlites were cancelled this morning and this forecast appears on track with improving conditions from west to east today as the system moves further eastward. The slow movement of this upper low will also keep clouds hanging around overnight for the central and northern areas, limiting sufficient radiational cooling for areas like the Grand Valley and Montrose to see widespread freezing temperatures. Temperatures may approach freezing in Montrose, but areas north of there from Delta to Hotchkiss appear to remain above freezing. Therefore, cancelled the Freeze Watch for tonight for COZ011 (Delta-Montrose area). This has also been the trend the last couple of days with cloud cover despite colder air moving in, where majority of those areas were above freezing. Southwest Colorado valleys, however, will see more clearing on the southwest end of that low and should drop below freezing, as temps the past couple nights were in the upper 20s to low 30s. So, upgraded COZ020 (Paradox Valley) and COZ021 (Cortez area) to a Freeze Warning for tonight through Saturday morning. This should be the last freeze products issued for a while as a warming trend is in store through the coming week. A dry day is in store for most of the area on Saturday as the upper low moves into the central high plains and high pressure tries to build over the west coast. A weak disturbance will clip our northern mountains for some light snowfall, but accumulations appear minimal at this time. Temperatures should slowly rebound for a milder day but still a few degrees below normal. .LONG TERM...(Sunday through Friday) Issued at 225 PM MDT Fri May 19 2017 The GFS and ECMWF are in pretty good agreement through Friday, leading to higher confidence in the going forecast although some discrepancies lie in a few details. As the upper low moves into Ontario and the northern Great Lakes by Sunday, a few weak disturbances will move around this large scale circulation through Tuesday as the low remains over this region. This will result in a chance of afternoon showers and storms mainly over the higher terrain each day with some spread into adjacent valleys. The northern and central mountains look favored at this time but snowfall accumulations in the mountains look minimal with a couple inches at best with each disturbance. The Sunday disturbance looks a little more robust than the others, resulting in a bit better coverage of showers. Temperatures will be on a slow warming trend with values near normal through Tuesday. Drier air will encompass much of the region by Tuesday afternoon through Thursday as the ridge of high pressure over the west slides over the region. This will also lead to temperatures rising to above normal levels through the end of the week. A couple weak shortwaves move in from the Great Basin and across the northern portion of the area towards late Thursday into Friday, resulting in a few showers and storms once again over the higher terrain. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1102 PM MDT Fri May 19 2017 Clouds will gradually clear with cigs slowly lifting as the strong low pressure system continues to drift east. A few isolated showers and lower cigs will persist as a result of residual moisture but otherwise, VFR conditions are expected for all TAF sites. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Freeze Warning until 9 AM MDT Saturday for COZ020-021. UT...None. && SHORT TERM...MDA LONG TERM...MDA AVIATION...MMS
Hazardous Weather Outlook National Weather Service GRAND JUNCTION CO 125 PM MDT Fri May 19 2017 COZ001>014-017>023-UTZ022>025-027>029-201930- Lower Yampa River Basin-Central Yampa River Basin- Roan and Tavaputs Plateaus-Elkhead and Park Mountains- Upper Yampa River Basin-Grand Valley-Debeque to Silt Corridor- Central Colorado River Basin-Grand and Battlement Mesas- Gore and Elk Mountains/Central Mountain Valleys- Central Gunnison and Uncompahgre River Basin- West Elk and Sawatch Mountains-Flat Tops- Upper Gunnison River Valley-Uncompahgre Plateau and Dallas Divide- Northwest San Juan Mountains-Southwest San Juan Mountains- Paradox Valley/Lower Dolores River- Four Corners/Upper Dolores River-Animas River Basin- San Juan River Basin-Southeast Utah-Eastern Uinta Mountains- Eastern Uinta Basin-Tavaputs Plateau-Arches/Grand Flat- La Sal and Abajo Mountains-Canyonlands/Natural Bridges- 125 PM MDT Fri May 19 2017 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...This Afternoon and Tonight Scattered snow showers will continue periodically throughout the day over the mountains of western Colorado before tapering off this evening. A couple inches of additional accumulation is possible but roads are expected to remain wet. Overall, improving conditions will be seen from west to east today with periods of clouds and sun as the system moves east of the divide. Meanwhile, overnight lows will fall below freezing again tonight for some southwest Colorado valleys, posing a threat to sensitive vegetation. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Periodic disturbances in northwest flow will bring additional showers, mainly to northwest Colorado, off and on through the early part of the coming week. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
954 PM MDT FRI MAY 19 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0700 AM HEAVY SNOW 2 WSW MEEKER 40.04N 107.92W
05/19/2017 M8.0 INCH RIO BLANCO CO UTILITY COMPANY
STORM TOTAL SNOWFALL, MEASURED ON DECK. THE
DURATION OF THE HEAVY SNOW EVENT WAS 24
HOURS.
&&
MMSThe national radar mosaic for the moment the first event began.
2 avalanche. Local standard time, as filed.
Over half of the forecast zone experienced low temperatures that ranged from 29 to 32 degrees F.
Over half of the forecast zone experienced low temperatures that ranged from 23 to 32 degrees F.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2017Every state in 2017This day in weather historyWarnings in Colorado, May 2017
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: 691448, 691449.