Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/17/25


AREA FORECAST DISCUSSION
National Weather Service Albany NY
1034 PM EST Sun Feb 16 2025 .SYNOPSIS... Strong winds usher in lake effect snow showers and colder temperatures through Tuesday. Cold temperatures linger through Wednesday as winds and lake effect snow showers finally diminish. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Key Message: - Strong winds with gusts up to 40 to 50mph continue overnight. Ice covered tree branches will be more susceptible to breaking/snapping from the strong winds, enhancing the potential for power outages tonight. - Lake effect snow develops downwind of the Great Lakes overnight and extends down the Mohawk Valley, Capital District, western MA, and southern VT. Discussion: As of 950 PM EST, our winter storm is quickly exiting into northern New England this evening and rapidly deepening into a sub-980 hPa low per the latest RAP guidance. This "bomb cyclone" is responsible for the very strong wind gusts that have developed this evening with gusts on NYS mesonet stations and ASOS sites reaching up to 45 - 50mph. We ended winter weather advisories and winter storm warnings except in the southern Adirondacks, Upper Hudson Valley, and southern VT where upslope snow continues (especially in southern VT). Will allow this product to continue through 06 UTC. Otherwise, still monitoring power outages tonight due to ice covered tree branches snapping in response to the strong winds. Lake effect snow quickly developing downwind of Lake Ontario as strong cold air advection ensues behind the departing storm and the CMC-reg shows lake effect streaming down the Mohawk Valley into the Capital District and even western MA later tonight as the multi-lake connection develops. Previous discussion...Low pressure is crossing New York state this afternoon with the low expected to redevelop off the New England coast by this evening and rapidly strengthen to near 970 hPa as it enters Atlantic Canada. Precipitation will continue into the early evening hours. Most areas are now seeing either freezing rain or plain rain but some northern areas could be seeing some snow or sleet. Temperatures in many areas are between 30 and 35 degrees with the cold spots along the CT River Valley and across portions of the Adirondacks which are in the mid to upper 20s. Storm total liquid equivalent precipitation amounts generally range from 0.75 inches to 1.50 inches with most of this falling as a mixture of frozen precipitation. A strong cold front will cross the region by early this evening as temperatures quickly fall back below freezing. Any remaining areas of standing water or untreated surfaces could become icy. In addition, a brief period of snow looks to return to the region, especially for areas around the Capital District and points north and west, where an additional coating to 2 inches of accumulation can occur in some locations. Wind will also begin to pick up by the early evening hours. These strong winds along with the weight of snow and ice on trees could result in downed trees and power lines resulting in power outages. The return of cold air will also result in the development of lake effect snow which will generally focus itself across the Mohawk Valley. More on the lake effect snow event can be found in the short term discussion below. Temperatures will fall back into the single digits and teens for most by early Monday morning. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... Key Messages: - Strong winds continue on Monday with gusts up to 65 mph possible in some areas. Windy conditions will continue on Tuesday as well but not be as strong as on Monday. - Lake effect snow will continue through mid week with locally heavy amounts especially for the western Mohawk Valley and southern portions of the Adirondacks. - Bitter cold temperatures with increasing confidence of feels like temperatures below -15 to -20 F Monday and Tuesday nights especially for higher elevations. Discussion: A strong pressure gradient will be in place across the region on Monday with forecast soundings suggesting winds at the top of the boundary layer approach 60 kt at times. Deep mixing up to this layer could lead to wind gusts between 45 and 60 mph across most of the region on Monday with some localized gusts to 65 mph also possible. The strongest winds will likely occur within the region of the Mohawk Valley, Capital District and Berkshires due to channeled flow. High Wind Warnings and Wind Advisories remain in effect with no changes at this time. These strong winds along with the weight of snow and ice on trees could result in downed trees and power lines resulting in power outages. While strong winds will continue into Tuesday, the pressure gradient will begin to wane so gusts look to generally be in the 35 to 45 mph range. It is possible some wind advisories may be needed for Tuesday. The cold air and strong winds, along with a multi-lake connection, will result in a band of lake-effect snow. Wind flow generally in the 270-290 degree range will mostly direct this band down the Mohawk Valley. Fragments of this band will likely extend into the Hudson Valley, including the Capital District, as well as western New England. Upslope snow showers will also occur across the southern Greens and Berkshires. Snowfall rates in excess of 1 inch per hour is likely to occur at times across the western Mohawk Valley with the very strong winds leading to near blizzard conditions at times. Snowfall amounts have increased with this update with amounts exceeding 10 inches across much of southern Herkimer County with 5 to 10 inches now possible across western portions of Fulton and Montgomery Counties. As a result, southern Fulton and Montgomery counties have been upgraded to a Lake Effect Snow Warning. Light snowfall amounts are possible within the Hudson Valley (a coating to 2 inches) with 2 to 5 inches of lake effect and upslope snow across the Taconics into western New England. As noted, much colder weather will result in highs both days only reaching the teens and 20s with feels like temperatures much lower than that. Lows both nights fall back into the single digits to around 10 with below zero readings across the Adirondacks. Feels like temperatures will fall below zero both Monday and Tuesday night for many areas with the colder readings (-15 to -20 degrees) across the higher elevations, where some cold weather advisories may be needed later in time. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Key Messages: - Bitter cold temperatures to persist through Thursday before moderating through the end of the week and into the weekend. - Continuing to monitor the trends of a coastal system that could bring snow to portions of the region late Wednesday night through Thursday. Though the system looks to largely pass us by to the southeast, there is still about a 10-30% chance of 4" of snow or greater from the Capital District south and east. Discussion: Though the long term period opens with dry weather, conditions will be rather uncomfortable as bitter cold temperatures persist. With highs in the 10s-20s and wind gusts of 15 to 30 mph across much of the area, maximum apparent temperatures will be widely in the single digits to 10s with pockets of low 20s in the Mid-Hudson Valley. Lows Wednesday night will then fall widely to the single digits with low 10s in the Mid-Hudson Valley and -3 to 0 in portions of the Southwest Adirondacks, though apparent temperatures will be closer to the true lows considering winds will be decreasing during this time. We are continuing to monitor the main chance of precipitation for the long term period which comes late Wednesday night through Thursday in the form of a northeast-tracking coastal low pressure system. While the latest guidance indicates this feature remaining off to our south and east, NBM probabilities for at least 4" of snow remain relatively stagnant from the previous iteration at ~10-30% from the Capital District south and east. The highest probabilities for this accumulation lies in Dutchess and Litchfield counties which will be closer in proximity to the track of the low. We will continue to monitor the situation closely as a slight shift north and west in the system track could mean greater and more widespread snowfall for our CWA, being that we are on the cold side of the storm. However, regardless of the track of this storm, there is a chance that most areas could see some snow showers during this same period due to the track of an upper-level shortwave/weak closed low through the region. But these should be relatively light in nature as moisture looks somewhat limited within this disturbance. Highs Thursday will still be rather cold, though a few degrees warmer than Wednesday with upper 10s to 20s and apparent temperatures primarily in the 10s. Lows Thursday night will then fall to the single digits to 10s. A much needed respite from winter weather comes at the end of the week through the weekend as high pressure encompasses much of the eastern CONUS. Joining the welcome tranquility will be moderating temperatures and decreased wind speeds, making conditions overall much more tolerable. Friday will see highs in the upper 10s at higher elevations up to low 30s in the Mid- Hudson Valley. Temperatures then gradually increase such that highs rise into the mid/upper 20s to low and possibly even mid 30s by Sunday. Low temperatures Friday night and Saturday night will remain in the single digits to 10s with lows Sunday increasing to more widespread 10s. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... As the back end of our winter storm exits this evening, rain and freezing rain has transitioned over the a burst of wet snow at ALB, PSF and GFL resulting in IFR visibilities and ceilings. POU remains mainly rain. The burst of snow (rain at POU) will end by 03-04 UTC this evening. Then, IFR cigs will trend upwards to MVFR and low end VFR and remain as such through the end of the TAF period. While widespread rain/snow ends before Midnight, we will be monitoring lake effect snow showers overnight. Snow showers may extend down the Mohawk Valley into the Capital District and western MA by 06 - 12 UTC tonight resulting in MVFR visibilities and ceilings. Should a steadier snow showers occur, brief periods of IFR vis cannot be ruled out but not enough confidence at this time to include. After 12 UTC, snow showers will still be tracking down the Mohawk Valley towards ALB and PSF. Given low confidence on exact placement and timing, only showing MVFR vis at PSF and VFR at ALB. Otherwise, GFL and POU will return to VFR by 06 - 12 UTC and remain VFR through the end of the TAF period. Low level wind shear is still on track for this evening into the end of the TAF period for all TAF sites as a southeast low level jet between 35 to 50 knots at 2000 ft AGL moves across eastern New York and western New England. Winds shift sharply to the west this evening by 02 - 04 UTC and increase to 12 to 25 with gusts reaching 30 to 35 knots. After this wind shift, winds subside a bit but remain breezy overnight sustained 8-15kts and gusts up 20 - 30kt. Winds quickly turn strong after 12 UTC as daytime heating enhanced boundary layer mixing with gusts reaching 35 - 50kts at ALB and PSF. Not quite as strong at GFL and POU with gusts up to 30 - 40kts. Outlook... Monday Night: High Operational Impact. Very Windy With Gusts To 41 kts. Chance of SHSN. Tuesday: Moderate Operational Impact. Windy With Gusts To 37 kts. Chance of SHSN. Tuesday Night: Low Operational Impact. Breezy. Slight Chance of SHSN. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: Low Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Chance of SHSN. Thursday Night: Low Operational Impact. NO SIG WX. Friday: Low Operational Impact. Breezy. NO SIG WX. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...Wind Advisory until 7 PM EST Monday for CTZ001-013. NY...Wind Advisory until 7 PM EST Monday for NYZ032-033-041>043- 059>061-064>066-082>084. High Wind Warning until 7 PM EST Monday for NYZ038>040-047>054- 058-063. Lake Effect Snow Warning from 1 AM Monday to 6 AM EST Wednesday for NYZ032-038>040. Winter Storm Warning until 1 AM EST Monday for NYZ033-039- 041>043-050-082>084. Winter Weather Advisory from 1 AM Monday to 6 AM EST Wednesday for NYZ033-082. MA...High Wind Warning until 7 PM EST Monday for MAZ001-025. VT...High Wind Warning until 7 PM EST Monday for VTZ013>015. Winter Storm Warning until 1 AM EST Monday for VTZ013>015. && $$ SYNOPSIS...Rathbun/Speck NEAR TERM...Rathbun/Speciale SHORT TERM...Rathbun LONG TERM...Gant AVIATION...Speciale
Area Forecast Discussion
National Weather Service Denver/Boulder CO
640 PM MST Sun Feb 16 2025 .KEY MESSAGES... - Mountain snow becoming heavier tonight through Monday night. Significant travel impacts expected. - Very cold air returns to northeast Colorado Monday night through Thursday morning with periods of light snow. - Another system will bring another round of snow to the mountains Wednesday night through Thursday with a chance of snow across the rest of the area. - Temperatures across the plains will slowly moderate from Thursday through Friday. && .SHORT TERM /Through Monday/... Issued at 210 PM MST Sun Feb 16 2025 Satellite showing the next swath of clouds and moisture moving into northwest Colorado with the next system. Radar is starting to fill in over northwest and north central Colorado. Webcams are just starting to show snow falling over the north central/central mountains. Already moved up the start time of the warnings and advisories to begin now. A strong (~100-120 knots) west-northwest flow aloft will prevail through Monday afternoon. This strong moist flow moving across the mountains is expected to produce light to moderate snow. Some bands of moderate to heavy snow will occur as well due to the jet overhead. In addition to the heavy mountain snowfall, winds gusting to 40 mph will produce areas of blowing and drifting snow, especially over the mountains passes. For the Front Range and eastern plains, the temperature forecast will be the biggest challenge. Not surprising, winds on the backside of the Denver Cyclone has helped hold colder air in place today with only a slow moderation of the airmass. Highs to the north of Denver will struggle to top 30F. Westerly winds above to colder air in the southern foothills is resulting in temperatures in the lower 40s. The battle between these two airmasses continues tonight and Monday. The foothills and Palmer Divide are expected to be the warmest tonight as will with lows in the 20s. The low lying areas north and northeast of the Denver metro will be the coldest with lows in the 5F to 15F degree range. May see another round of fog again tonight and Monday morning to the north of Denver in this colder airmass. Temperature setup Monday will be somewhat similar today. Northeast to easterly low level flow will hold colder air over much of northeast Colorado. Then by early to mid afternoon arctic air begins to back southwestward. Still looks like the HRRR and NAMNest are running about 10 degrees too warm for highs across parts of the area, including Denver. We will see a large temperature gradient as well with highs in the upper 40s in the foothills southwest of Denver to the lower to mid teens over the northeast corner of the state. && .LONG TERM /Monday night through Sunday/... Issued at 210 PM MST Sun Feb 16 2025 Cold and snow continue to be the main focus for the long term forecast period, which starts in the midst of our current winter weather headlines. By Monday evening, cross sections show deep moisture persisting over the mountains and pushing eastward onto the plains. Heavy mountain snow is expected to continue overnight, with the heaviest amounts shifting southward into the Vasquez Mountains and Gore Range for the evening as steady QG ascent continues ahead of an approaching shortwave trough. Across the plains, our first wave of arctic air will move into the northeastern corner of Colorado by Monday evening. With the arrival of cold air, a swath of frontogenesis will stretch across the plains. As the aforementioned moisture pushes east, snow is expected to develop across the lower elevations for the evening and overnight hours. While accumulations are expected to be light, with frontogenesis in play and a jet overhead, there is potential for some banded snowfall to bring areas of heavier amounts where the bands develop. Snow chances will remain through the day on Tuesday as the shortwave trough passes across the forecast area, and some steeper lapse rates remain through the afternoon. Increasing NW flow is expected overnight Tuesday as a 150kt jet streak stretches from NW to SE across the WY/CO border. While cross sections show a more shallow moisture profile in place, there will be enough to allow for some additional light snow to accumulate over the northern plains. A surface anticyclone over southern Canada will keep the cold air flowing into eastern Colorado via a general easterly surface flow through Wednesday, with a more prominent cold wave expected Tuesday night into Wednesday. Ensembles continue to show varying solutions for how cold it will get, however, the spread in values has decreased as we get closer to the event. The GEFS continues to be the warmest solution with keeping the coldest air to the north and east of the urban corridor, but has slowly trended towards the colder solutions of the Canadian and Euro ensembles. Will continue to blend towards the Euro mean for this package as it remains the middle of our ensemble guidance. As of now, guidance doesn`t push the coldest air as far west as the foothills, but in these cold air events, this tends to happen. Have gone ahead and issued an Extreme Cold Watch for Sedgwick, Phillips, Logan, and Washington Counties for now, as the current forecast has periods where wind chills as cold as -30F will occur between late Monday night through Thursday morning. This may need to be pushed west in the coming packages when confidence increases with regards to how far west the cold air makes it. But for now, be prepared for extremely cold temperatures this week, and put on extra layers if you must spend any time outside! There will be additional chances for mountain snow with another shortwave trough expected Wednesday night into Thursday. Temperatures are expected to moderate beginning on Friday as ridging builds over the west. Ensembles show temperatures quick to rebound into the 60s for the weekend. Opted to go on the low side of guidance for now as this seems a tad fast for the cold air to move out, but we are expecting to see much warmer temperatures for next weekend! && .AVIATION /00Z TAFS through 00Z Tuesday/... Issued at 639 PM MST Sun Feb 16 2025 A weak Denver cyclone is in place across the plains with it`s center around the southeast corner of Weld County. As a result, weak west and northwesterly winds should continue at DIA well past midnight tonight. Currently, at DIA, the ASOS is indicating 6SM BR. Not certain how dense the fog will eventually become, as a number of models do not even show low level Stratus whatsoever. I may need a TEMPO group for some lower visibilities, we`ll see. I will keep a VCFG going in the DEN TAF for a few hours this evening into the overnight period. Will also put SCT low clouds in. No precipitation overnight and Monday morning. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 5 AM MST Tuesday for COZ031-033. Winter Weather Advisory until 5 AM MST Tuesday for COZ032-034. Extreme Cold Watch from late Monday night through Thursday morning for COZ048>051. && $$ SHORT TERM...Meier LONG TERM....Bonner AVIATION.....rjk
Area Forecast Discussion
National Weather Service Billings MT
641 PM MST Sun Feb 16 2025 .KEY MESSAGES... - A persistent period of snow is occurring for central and western portions of the forecast area (including Billings) through Tuesday. Heavy snow accumulations are expected during this prolonged snow event. - Bitter cold temperatures and wind chills continue through Wednesday. - Much warmer temperatures arrive for the end of the week into next weekend. - Windy conditions expected next weekend in the foothills. && .UPDATE... Ongoing winter storm is on track and have made no changes. Have extended the cold highlights, which were set to run til 19z tomorrow, through noon Wednesday. Snow has picked up over the past couple hours. Latest mesoanalysis shows a few interesting features. First, a NW-SE oriented band of mid level frontogenesis matches up well with a similar axis of a deep DGZ. Second, as trof moves thru the PacNW, cooling temps aloft are increasing mid level lapse rates, and latest 700-500mb values are 7C/km in Park County, and 6.5C/km as far east as Park City. So there is some instability helping the snow production. Dendrites have definitely gotten larger since sunset. Band of heaviest precip is impacting Billings but is a bit more intense just to our west and south (roughly Columbus & Joliet to Fort Smith). Appropriately, latest HRRR runs have painted highest snow amounts along this axis. Have raised pop/QPF/snow a little in this area, up to 4" of snow from 00-12z. Billings should see ~3" in this same time period. Overall, these are minor adjustments and are consistent with our highlights. Will need to watch the evolution of the frontogenesis and steepest lapse rates. JKL && .DISCUSSION... Tonight through Tuesday... Arctic air in place at the surface and moisture overrunning the cold was bringing light to moderate snow over central and western areas this afternoon. A fairly deep dendritic layer remains in place over the region, and an area of strong isentropic lift/frontogenesis will situate its self from a Harlowton to Billings to Lodge Grass line by this evening. Expect snowfall to increase in intensity this evening and overnight into Monday morning with the increased forcing. Periods of snowfall will continue over the area Monday into Tuesday, as moisture continues to stream into the region. Snowfall will gradually come to an end from north to south Tuesday afternoon and evening. Guidance has remained fairly consistent in snowfall totals, with a large swath of 6 to 12 inches of snowfall under the aforementioned frontogenesis band, with lesser totals to the northeast, and the southwest. Snowfall totals still look to be in the 4 to 8 inch range down into the foothills, with 2 to 6 inches from Rosebud County and south into Sheridan County. With this forecast package, snow totals have gone up for Powder River County, with 2 to 5 inches now expected there. For the mountains, 1 to 2 feet of snowfall is expected in the western mountains, with greatest amounts on west aspects. The Bighorns/Pryors still look to see between 7 to 14 inches. Overall, the winter highlights look to be in good shape, with the only change to add Powder River County to the Winter Weather Advisory. Temperatures will remain cold through Tuesday, with high temperatures Monday and Tuesday ranging from the single digits above and below zero for many areas, with some locations over the far east potentially staying in the teens below zero. Lows tonight and Monday night are expected to range from the single digits to 20s below zero, coldest over the east. Have issued a Cold Weather Advisory and Extreme Cold Warning for portions of the east and the north for tonight and tomorrow morning. Additional cold weather highlights will likely be needed for Monday night and again Tuesday night. Continue to monitor the forecast on this cold and extended snowy period, making sure you are prepared if you must travel. STP Tuesday Night through Monday... The coldest temperatures of the season are expected Wednesday morning following the departure of our current weather maker. Models are trying to hang on the the cloud cover a little longer in recent runs which would prevent us from being able to fully use the fresh snowpack to help radiate out all the daytime heat. That being said, temps will still be bitterly cold as the arctic front exits to the east. Areas in the north and east of the CWA could touch -30F while areas near Billings should be able to reach -20F. Wind chill values will be 10-15 degrees below the air temperature at all locations which would allow for frostbite to occur in as little as 10 minutes. After the arctic front makes its full exit by Thursday there is excellent agreement amongst the long range models, and their ensembles, that we will rapidly warm up back to average. While the warmth and break from precip may be welcomed by some, this could also bring a few hazards itself. The lower elevation MT Mesonet stations in the central part of the CWA are showing that there has roughly been 1" of SWE that has fallen in the past 30 days with the possibility of an additional ~0.5" over the next couple of days with this current system. In some of the higher hills out to the east as well as the Wolf Mountains there is presently 2-4" of SWE sitting on the ground there. When looking at the frost depth these values range from 4" in Billings to nearly 40" out near Miles City. All of this means that with temps quickly warming into the low 40`s this snow will start to melt before the ground has a chance to thaw out which will allow for water to runoff as it will not be able to be absorbed into the frozen ground. There are also a few ice jams that have been observed from the USGS river gauges, and there could be more that are not near the gauges. This sudden warm up combined with the in flux of water in all of the rivers and streams could break up the ice and thus is something that will need to be monitored closely over the weekend into early next week. Also over the weekend, we move into more of a zonal flow pattern which will allow the high pressure over Yellowstone National Park to make its return aided by the new snowpack. This will allow the gap wind machine to turn back on for the western foothills. The GFS is presently showing a 20hPa gradient between IDA and LWT for Sunday. Of course, this is a week away and specifics will change but the windy areas can expect to become windy yet again. WMR && .AVIATION... IFR conditions will prevail over the next 24 hours with occasional dips into LIFR during periods of heavy snow. KMLS and areas in southeast Montana should prevail as VFR for the period with small chances (30%) for a dip down to MVFR. Mountains will be obscured for the entire period. WMR/LT && .PRELIMINARY POINT TEMP/POPS... Mon Tue Wed Thu Fri Sat Sun ----------------------------------------------------------- BIL 905/901 910/901 918/005 906/024 014/038 027/043 034/046 ++/S +7/S 11/B 24/S 20/U 00/B 01/N LVM 002/008 905/007 904/020 010/036 021/040 026/044 033/046 +9/S +7/S 21/B 56/S 21/N 01/N 11/N HDN 905/004 915/001 923/010 911/021 007/040 020/046 029/048 ++/S +8/S 21/B 14/S 21/B 00/B 11/B MLS 915/904 915/903 925/002 912/013 001/028 019/040 030/044 23/S 43/S 00/B 01/B 10/B 00/B 00/B 4BQ 908/001 911/000 922/006 910/018 005/035 022/043 031/047 66/S 74/S 10/B 01/B 10/B 00/U 00/B BHK 924/909 924/908 927/903 917/007 904/027 016/040 025/043 01/I 22/S 10/I 00/B 10/B 00/B 01/N SHR 902/008 907/005 915/015 901/026 010/039 018/047 027/050 8+/S 98/S 31/B 14/S 21/B 00/B 00/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Winter Storm Warning in effect until 5 PM MST Tuesday FOR ZONES 29-34-40-42-57-63-65-67-68-138-141-169-170-172-173-228-235. Winter Weather Advisory in effect until 5 PM MST Tuesday FOR ZONES 30-31-36-56-58-64-66-139-171. Cold Weather Advisory in effect until noon MST Wednesday FOR ZONES 30-31-36-63. Extreme Cold Warning in effect until noon MST Wednesday FOR ZONES 32-33-37. WY...Winter Weather Advisory in effect until 5 PM MST Tuesday FOR ZONES 198-199. && $$ weather.gov/billings