Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/15/23

Area Forecast Discussion
National Weather Service Burlington VT
905 PM EST Sat Jan 14 2023 .SYNOPSIS... Low clouds will prevail across most of the North Country tonight with some clearing possible over the St Lawrence Valley, where temperatures may drop into the single digits. On Sunday we should see increasing amounts of sunshine with temperatures warming to seasonable levels by afternoon. A storm passing to our east may produce a few scattered snow showers on Monday, with warming temperatures back above normal by early this upcoming week. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 902 PM EST Saturday...Snow chances have been increased over our high terrain areas. In particular, we`re receiving reports of coating on the roads from light snow across the Adirondacks. Additionally, forecast soundings indicate cooling to be enough that there should be some saturation in the DGZ as the low stratus lingers. Orographic forcing should be enough to squeeze some light accumulations overnight. General timing looks to end about 5 AM, but could be as late as 7 to 8 AM depending on how quickly we dry out overnight. Added 0.2" of snow and increased PoPs to 30 to 50 percent over a large swath of the Adirondacks. Have a great night! Previous Discussion... Fcst challenge tonight wl be areal coverage of clouds/potential clearing acrs the SLV and impacts on temps. Water vapor shows large scale subsidence/dry air aloft directly acrs our cwa this aftn associated with building hghts, while vis satl pic shows plenty of low stubborn clouds. The classic setup of sfc to 900mb moisture trapped below thermal inversion, which looks to persist into the overnight hours. Have noted some clearing trying to advance acrs the SLV with lower dwpts upstream at Ottawa in the single digits. Following the RAP/HRRR sounding profiles, does support clearing skies overnight, which should result in temps cooling to near 0F, with maybe some patchy/shallow fzfg. RAP sounding shows very sharp/shallow inversion profiles, with temp falling way below cross over value, supporting this potential, even with some lowering dwpts. Otherwise, clouds wl drive overnight low temps with many locations holding in the mid/upper teens, except some single digits where clearing develops toward sunrise on Sunday. Sunday/Sunday night no large scale changes made to the crnt fcst as mid/upper lvl ridge and associated deep dry layer builds acrs our western/central cwa. This should eventually erodes llvl moisture with increasing amounts of sunshine anticipated on Sunday. However, last place to see the sun wl probably be the eastern CPV and Western Slopes based on northerly flow/convergence and lingering moisture per soundings at BTV. Temps wl be the coolest northern SLV and northern CPV valleys with values l/m 20s, while midslopes and ridges warm into the mid 20s to lower 30s, due to inversion/thermal belt. A challenging temp fcst again overnight Sunday night as sharp llvl inversion prevails with deeper/protected valleys dropping quickly as winds decouple. Have lows generally ranging from 0F SLK/northern SLV to 15F eastern/southern VT where some high clouds may develop. Also, have bumped pops up toward chc by 12z Monday for eastern VT, which is supported by ECMWF/CMC and NAM retrograding some mid lvl moisture back toward our cwa. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 335 PM EST Saturday...As an area of low pressure over the Atlantic passes to the east, moisture on the western edge of the system may extend into eastern Vermont. Model guidance suggests that precipitation will be confined to northeastern Vermont, although there is some disagreement. For example, the GFS shows precipitation remaining to the east of our CWA while some Canadian guidance is showing the potential for precipitation to reach as far west as the Champlain Valley. Light snow showers appear likely for the areas east of the Green Mountains, however there is the potential for wintry mix Monday night which will continue to be monitored. Overall, no major impacts are expected with this system. Temperatures will continue to be on the colder side due to northerly winds, with high temperatures in the mid and upper 20s in most places. Low temperatures will be in the single digits to mid teens, however lows in northeastern Vermont will be milder due to low cloud cover associated with the moisture from the low pressure system. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 341 PM EST Saturday...No big changes to the midweek system that will weaken as it traverses the Great Lakes region and brings light mixed precipitation into our region. Have added some light ice accumulation in the Tuesday afternoon/evening period across southern St. Lawrence County given strong signals for a shallow warm layer while surface temperatures remain below freezing. The potential for freezing rain over mainly southern portions of northern New York and Vermont does look fairly high and will likely lead to hazardous travel. Thankfully amounts will be on the light side before precipitation trends towards either plain rain or snow by Wednesday when somewhat heavier precipitation arrives associated with cooling aloft. Wednesday looks to be the mildest day of the week with temperatures well above freezing in most locations with southerly low level flow, in at least the early part of the day, prior to a frontal passage. A moisture laden low pressure system still is on track to impact the region in the Thursday afternoon through Friday time frame and again will likely be messy with regards to precipitation type given marginally cold air. Southwesterly flow aloft will tap into the Gulf of Mexico and Atlantic during the event, and a dual upper jet structure looks favorable for a strengthening low pressure system, so heavy precipitation amounts are possible. At this time, we continue to favor snow based on the model consensus/NBM. Predictability remains lower than average with large spread in storm track, although timing is in reasonably good agreement. Quite a few ensemble members draw enough warm air aloft to change precipitation to a wintry mix and/or rain before a secondary low to our southeast can draw colder air back into northern New York and Vermont. Therefore, was not willing to go with only snow as the precipitation type, especially given the recent weather pattern and the lack of support for an all snow event from the GFS ensemble. However, even the latest GFS has a CIPS analog to a heavy upslope snow event from February 24, 2012, so ingredients for significant snowfall are definitely in place. Stay tuned as to how much snow as we can solidify the event details in the coming week. Ultimately, the storm will pass to our east towards late Friday with steady precipitation becoming limited to dwindling snow showers on Saturday. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Through 18Z Sunday...MVFR ceilings prevail at TAF sites attm. While conditions will generally improve to VFR overnight, have taken a more cautious approach at BTV due to low clouds from lake response and SLK given ample moisture locked into the terrain. MSS at the edge of cloud shield, which poses another concern...namely fog development. Have increased patchy fog across the St. Lawrence Valley (and northern Adirondacks), but have stayed away from taking restrictions at MSS (or SLK for that matter) thus far. Have maintained the BCFG comment at MSS instead. By 14-15z Sunday, expecting widespread VFR conditions with light north/northeast winds of 5 to 10 knots. Outlook... Sunday Night: VFR. NO SIG WX. Martin Luther King Jr Day: VFR. Slight chance SN. Monday Night: VFR. NO SIG WX. Tuesday: VFR. Chance SN. Tuesday Night: Mainly VFR, with local MVFR possible. Likely RA, Chance SN, Likely FZRA. Wednesday: Mainly MVFR, with areas IFR possible. Chance SHRA, Chance FZRA, Slight chance SHSN. Wednesday Night: Mainly MVFR, with local VFR possible. NO SIG WX. Thursday: Mainly VFR, with local MVFR possible. Chance SN, Slight chance RA, Slight chance FZRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Taber NEAR TERM...Haynes/Taber SHORT TERM...Kremer LONG TERM...Kutikoff AVIATION...Taber
Area Forecast Discussion
National Weather Service Billings MT
756 PM MST Sat Jan 14 2023 .UPDATE... Forecast looks to be on track tonight with low temperatures in the low 30s to 20s across the region. Adjusted cloud cover up to the south and east of Billings as mid to high-level clouds moved in a little early. Even with the 0.05" of rain at Miles City, dew point depressions between Miles City and Baker remain above 5 degrees, keeping fog chances low for now. HRRR continues to keep visibility up overnight. Arends && .DISCUSSION... Tonight through Monday Night... The weak shortwave that moved out of the Great Basin and into Montana this morning has mostly moved north of the area. Miles City did pickup 0.05" with the activity, but the rest of the day should be quiet across the area as the energy has moved on. Given the increase in lower-level moisture associated with the wave, cannot rule out some fog mainly around Miles City and Baker, but the current HRRR keeps visibility up. The next issue on the horizon is the trough moving off the Pacific. This will continue to push the ridge east bringing lower heights and increasing cyclonic flow. It will also provide a little more moisture. The best chance for snow remains in the mountains where the 24 hour total Snow Monday remains around 70%. The ensembles have trended higher with the precipitation for the lower elevations, so have a little more snow on the lower elevations. Twenty-four hour amounts are still generally an inch or less. Additionally, Monday morning in eastern Montana the temperature profiles continue to support some light freezing drizzle or freezing rain. There is a saturated layer below freezing, but it does not support ice being present to produce snow. The NBM has started to introduce some chance for freezing rain now, still of a slight chance (less than 30 percent), but has added it to the grids. Reimer Tuesday through Saturday... The theme for the mid- to late-week forecast period is changing weather. Several shortwave troughs and ridges will move over the Northern Rockies, bringing periods of dry weather and periods of light snow in parts of the region. On Tuesday, a weak shortwave trough will be over the region but the forcing is so weak, we think that the only effect will be mostly cloudy skies. Tuesday night-Wednesday, the shortwave trough will exit MT to the east, and shortwave ridging will move in behind it. This ridge will facilitate decreasing cloudiness Tuesday night and mostly sunny skies Wednesday. Wednesday night through Thursday night, the shortwave ridge will exit MT to the east again, and a stronger shortwave trough will move over our region. This trough will bring a 30-50% chance of snow to and near the Beartooth/Absaroka and Crazy Mountains and adjacent foothills Wednesday night, then a 20-70% chance to much of the lower elevations and all area mountains Thursday (greatest chance in the mountains). Models are suggesting a northwesterly flow upslope-downslope precipitation reduction/enhancement pattern, so areas northwest of Billings would receive the least amount of snow while areas southeast of Billings and mountains would receive the most precipitation. As of now, though, the probability of at least one inch of snow is near or greater than 50% only in the foothills of southern Big Horn and Sheridan Counties and in the mountains, with the chance decreasing away from those areas to near 10% for Billings and Baker and lower values north of these areas. Friday into Saturday, an upper ridge will build over the eastern Pacific and Pacific Northwest, extending to the Northern Rockies. The ridging will cause any snow to diminish early Friday, and dry weather then through most of Saturday. Furthermore, stronger mid- level winds crossing the Rocky Mountains will produce downslope warming on Saturday. Later in the day Saturday, models then suggest the upper flow should turn more northwesterly over our region with a disturbance moving through the flow and a 20-40% chance of snow showers. High temperatures will generally be in the 30s and 40s Tuesday, Wednesday and Saturday and 30s Thursday and Friday. RMS && .AVIATION... VFR will prevail across the area through the TAF period, under scattered to broken mid/high clouds. Isolated snow showers are expected over the Beartooth/Absaroka Mountains tonight into Sunday. Mountains will be occasionally obscured. JKL && .PRELIMINARY POINT TEMP/POPS... Sun Mon Tue Wed Thu Fri Sat ----------------------------------------------------------- BIL 030/044 031/043 026/043 023/042 027/038 025/039 025/042 00/E 33/S 10/B 00/U 13/S 21/B 12/S LVM 028/043 030/041 022/038 019/037 023/033 019/032 019/038 02/S 41/E 00/B 00/B 34/S 21/B 12/S HDN 021/040 025/038 022/040 018/040 020/038 021/037 019/041 00/B 34/O 10/B 00/U 14/S 21/B 12/S MLS 022/036 024/032 023/035 019/038 021/036 022/034 020/037 00/B 13/S 20/E 00/U 02/S 21/B 11/B 4BQ 025/043 027/036 026/040 023/040 021/038 024/034 022/038 00/B 34/S 21/B 00/U 02/S 31/B 11/B BHK 022/038 022/030 020/034 018/035 017/033 017/029 015/034 00/B 12/S 10/E 00/U 01/B 21/B 01/B SHR 025/042 026/037 021/037 017/038 016/034 019/032 014/038 01/B 56/S 21/B 10/U 14/S 42/S 12/S && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Las Vegas NV
713 PM PST Sat Jan 14 2023 .SYNOPSIS...Active weather will continue across the area through the Tuesday. The first round of mountain snow, valley rain, and Mojave wind will continue through this evening, with dangerous mountain travel expected. After a brief break on Sunday, the second round of heavy mountain snow and valley rain spreads over the area Monday into Tuesday. Dry, cooler weather is forecast for the remainder of next week with temperatures 8 to 10 degrees below normal. && .UPDATE...Update focused on lowering QPF for the higher elevations in the first 6 hours (00Z-06Z) this evening. Nearly an inch and half for the Spring Mtns looked unattainable based on previous observations late this afternoon where SNOTEL were reporting about 0.20"/hour. So blended the latest NBM with HRRR and NAM to reduce values. Rain has been light across Las Vegas Metro with amount generally less than 0.10" so far. Outside of the valley, have seen some higher amounts between 0.50"-1.00" within the Pahrump Valley, central Nye County, Owens Valley and parts of San Bernardino County. Latest NBM shows PoPs starting to decrease late this evening across Inyo, Esmeralda and western San Bernardino Counties. That line advances east through Clark County between midnight and 2 am, finally exiting eastern San Bernardino and southern Mohave Counties between 4-6 am PST/5-7 am MST Sunday. Need to monitor parts of southeast San Bernardino and southern Mohave Counties overnight as some nuisance flooding is possible with pockets of moderate rain overnight. && .DISCUSSION...Tonight through Tuesday. The first wave of a two part AR event is underway with radar showing returns over the Sierra and also the Western Mojave Desert. As of noon, observations sites in the Western Mojave Desert were reporting up to tenth of an inch with snow piling up quickly in the Sierra where Snotel sites have reported 4-13 inches since 10 am this morning. The heaviest period of snowfall for the Sierra will continue through 10 pm this evening before showing signs of tapering off. Total snowfall from this first wave of 1-2 feet is expected along the upper eastern slopes of the Sierra by 10 am Sunday with higher amounts up to 3 feet above 9000 feet. Expect rain and high elevation snow to spread across the region this afternoon and continue overnight. Snow was already falling in the Spring Mountains at noon and is expected to become heavy at times this afternoon and evening before tapering off by daybreak on Sunday. Widespread light showers are expected through mid afternoon in the valleys then moderate to heavy rain at times late in the afternoon and this evening. Rain and high elevation snow will continue after midnight but should begin winding down in our western areas but continuing in our eastern areas. Went with a Winter Weather Advisory for the Sheep Range and elevations above 5500 feet in Mohave County. The highest impact areas could see 4-7 inch snowfall with higher amounts in the highest elevations where impacts are limited. Sunday will be mostly an in between day as we wait for the second wave to push into the area Sunday night and Monday. Lingering precipitation on Sunday in mainly Mohave County could lead to additional snow accumulations in the Arizona Strip and Hualapai Mountains. Shower chances increase over much of the area Sunday night but overall precipitation amounts will generally light. The main concern will be lower snow levels between 4-5k feet. This colder air could coat some lower elevation highways such as 395 in the Owens Valley with an inch of snow making travel hazardous. As precipitation intensifies on Monday, the snow level will increase to about 4500-5000 feet across our northern zones and 5500-6500 feet across our central/southern areas. Significant snowfall is forecast again for the mountains with widespread rain across the valley on Monday. A Winter Storm Warning is already in effect through Tuesday morning for the Sierra and White Mountains with additional headlines in other areas likely needed. Wednesday through Saturday...the water hose for our area shuts off as one more system is forecast to move from the Gulf of Alaska through the Great Basin. This one looks dry and could be mainly a wind maker for our area. What is notable is the cold air that settles into place from mid week into the weekend. Temperatures are forecast to be 8-10 degrees below normal.E && .AVIATION...For Harry Reid...Light rain will move across the terminal this afternoon, decreasing CIGs to 3-5kft. The heaviest precipitation is expected this evening when CIGs may lower to 2 to 3kft during periods of heavier rain. While most of the rain should end by midnight, a few lingering showers will continue for a few more hours, especially over the higher terrain surrounding the valley. Winds will remain southerly into tomorrow morning, gusting up to 25kts at times overnight. Winds will turn more westerly after daybreak on Sunday, and decreasing clouds are expected by the afternoon. For the rest of southern Nevada, northwest Arizona and southeast California...Extensive clouds and periods of rain will affect all TAF sites this afternoon and tonight. CIGs decreasing to 3 to 4kft is likely, with CIGs potentially falling to below 2kft during periods of heavier precipitation. The rain may also mix with or change over to snow at KBIH overnight before ending. Winds will generally be south to southwest and gusty at times, especially at KDAG. All sites should see improving conditions tomorrow morning and afternoon before another system approaches from the Pacific Sunday night. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Pierce DISCUSSION...Salmen AVIATION...Planz For more forecast information...see us on our webpage: or follow us on Facebook and Twitter