Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/20/23

Area Forecast Discussion
National Weather Service Louisville KY
933 PM EST Thu Jan 19 2023 .Forecast Update... Issued at 930 PM EST Thu Jan 19 2023 Low stratus deck is now settling across the Ohio Valley in the wake of the surface cold front which rolled through this afternoon. Winds, which gusted upwards of 50 mph across the area earlier today, have begun to relax with the low-level jet core off to the east and some nighttime stabilization of the boundary layer occurring. However, gusts of 30 to 35 mph are still being observed at this hour, and wind gusts of 25 to 35 mph are expected to continue thorugh sunrise tomorrow. Trapped low-level moisture has been sufficiently deep across portions of southern IN this evening for a few sprinkles/light rain showers to develop. While soundings suggest that moisture depth is relatively shallow (mainly in the 800-900 mb layer in HRRR soundings), still think there could just be enough moisture and dynamic lifting from mid-level cyclonic flow aloft to squeeze out some light rain/snow showers or sprinkles/flurries later tonight. Impacts are not expected from precipitation, and temperatures should remain at/above freezing throughout the night. Updated products will be published shortly. && .Short Term...(Tonight through Friday evening) Issued at 250 PM EST Thu Jan 19 2023 Key Messages: - Wind Advisory in effect through the rest of the afternoon. - Isolated damaging wind threat for southern Indiana, and less likely the Bluegrass, during the next couple of hours. Synopsis...A sharp shortwave trough moving along the base of the Great Lakes upper low will induce a strong mass and thermodynamic response in the Ohio Valley. This weather system is dragging a cold front through central Kentucky and southern Indiana where convection have started to congeal and will continue for a brief window this afternoon with a marginal severe wind threat. The rest of the forecast period will see the upstream side of the upper low moving across the lower Ohio Valley with subtle mid-level heights rise. This Afternoon...Latest regional radar imagery shows scattered low- topped convection developing along and ahead of the westward moving cold front. Surface analysis depicts a marginally conducive environment for updraft strengthening and maintenance, so current activity will struggle to tap into the strongest winds aloft and induce downward momentum transfer. Therefore, possibility of damaging winds is still considered low and mostly concentrated in southern Indiana and less likely the Bluegrass later on in the afternoon as the gusty showers migrate westward. Best mesoscale forcing due to low-level frontogenetical forcing will be located in central Indiana and especially Ohio, but pulse convection can still render severe wind gusts, and that`s the reason why SPC included Jefferson and Trimble counties, Indiana, in the Severe Thunderstorm Watch # 26. The greatest uncertainty for convective initiation and strengthening resides in the dewpoints as the strong winds can support a greater mix-down than actually represented by models. Most, if not all, shower activity should be out of the area by 19/21Z; however, conditions will remain windy behind the convective line with some gusts approaching 50 mph, as already reported. A Wind Advisory is in effect until 20/00Z for anomalous wind speeds outside the shower activity. Tonight...Winds will eventually subside to below-advisory criteria, but gusts between 20-30 mph will still be common. In addition, there is still low confidence on a flurry/sprinkle scenario tonight. GFS and CMC have some ensemble members supporting light snowfall rates with forecast soundings showing better low-level saturation. On the other hand, ECMWF relies on a drier night with perhaps sporadic sprinkles. All in all, followed a persistence forecast and indicated a low possibility of flurries and/or sprinkles. Friday...As the upper low departs to the Northeast US, winds will continue decreasing with westerly wind gusts around 15-20 mph in the afternoon. Low-level clouds will stay around for most of the day, but dry weather is expected with a clearing trend starting in south central Kentucky late in the afternoon as the upper-level heights rise. && .Long Term...(After midnight Friday night through Thursday) Issued at 213 PM EST Thu Jan 19 2023 An active pattern looks to develop with multiple systems taking aim at our region through next week. We`ll start off Saturday dry and sunny, but a trough will dig into the Plains and quickly race eastward. Gulf moisture will be drawn northward as the trough advances toward us Saturday night into Sunday, and we`ll likely see precipitation develop in response to modest isentropic lift by Sunday morning. Temperature profiles continue to be a bit tricky in terms of p-type, with precip primarily being a cold rain or wet snow. Best chances for any snow will generally be north of the Western Kentucky and Bluegrass Parkways, though overall snow amounts should stay on the low side. 12z GEFS 1" snow or greater probabilities peak around 50-60% for the duration of the event, with ensemble means generally staying under 1" in the northern CWA. The system should kick on out of here by Monday and give way to a brief dry lull, but another system will be right on its heels and likely move into the region late Tuesday into Wednesday. Like the previous system, this one will be a bit tricky in terms of p-type (but primarily rain or snow), which will be largely influenced by the track of the system. Given the spread in models, will keep some mention of snow in the forecast, with the highest probabilities off to the north for now. && .Aviation...(00Z TAF Issuance) Issued at 635 PM EST Thu Jan 19 2023 Impacts: - Gusty westerly winds continuing, easing somewhat overnight - MVFR ceilings expected for most of the next 24-30 hours - A few light rain/snow showers possible tonight at SDF/LEX/HNB Discussion: A cold front is departing the region to the east at this hour; however, gusty winds are expected to continue overnight tonight as a strong low-level pressure gradient remains over the area. Expect gusts of 20-30 kt to gradually ease over the next 6-12 hours, with wind direction remaining fairly constant out of the west. Low-level moisture will become trapped later this evening, allowing for the development of MVFR ceilings across the region. The moisture should be sufficient for a few isolated rain showers to form over the next few hours, with rain changing to snow or a rain/snow mix after midnight tonight. Precipitation should be light enough with above- or near-freezing ground temperatures such that impacts to operations are not expected. Low stratus is expected to stick around into the day on Friday, with ceilings remaining between 1500-2500 ft for most of the day. Winds will finally relax more toward sunset tomorrow night near the end of the current forecast period. Confidence: Medium-High in winds, medium in ceilings, low-medium in VCSH && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...CSG Short Term...ALL Long Term...DM Aviation...CSG
Area Forecast Discussion
National Weather Service Pueblo CO
248 PM MST Thu Jan 19 2023 .SHORT TERM...(This evening through Friday) Issued at 241 PM MST Thu Jan 19 2023 Key Messages: 1. Mostly quiet tonight into the first half of Friday. 2. Weather system bringing snow moving in from the west Friday afternoon. Currently... The region is currently influenced by a high pressure ridge, which is moving to the east. Downsloping winds along the I-25 corridor is warming temperatures in the plains, and keeping humidities from going up. Skies are mostly clear in the plains, and cloud cover is currently beginning to encroach into the Continental Divide. Tonight into tomorrow.. The high pressure ridge will move further to the east, making way for the approaching mid level low pressure system. This system will be a closed low, which will be wrapped in moisture. As the low moves closer to the region, snowfall will begin to invade the region from the west mid to late morning, first affecting the eastern San Juan and Sawatch Mountains. This snowfall, according to NBM, GFS and HRRR models, will move further east into areas along the I-25 corridor early to mid Friday afternoon. Heaviest snowfall amounts during this time are expected to be near the Raton Mesa, Southern Sangre de Cristo Mountains, the Eastern San Juan Mountains and counties along the I-25 corridor eastward, except for El Paso county, which is expecting lighter snow amounts. A Winter Weather Advisory will be in effect from 2 PM Friday for Pueblo and Crowley Counties, as well as the Wet Mountains, and will last until the following day. A Winter Storm Warning will be in effect from 2 PM Friday for Las Animas, Baca, Huerfano, Otero, Bent, Prowers and Kiowa Counties. This warning will also be in effect until beyond the forecast period. This occurrence will be ahead of an approaching cold front from the west. Low temperatures Thursday night into Friday morning will be in the teens in the plains, single digits in the mountains and mountain valleys, and the San Luis Valley will range from -5 to 10 degrees. High temperatures Friday afternoon will be in the 30s along the I-25 corridor, 40s in the eastern plains and teens, 20s and 30s in the mountains and mountain valleys. -Riser .LONG TERM...(Friday night through Thursday) Issued at 241 PM MST Thu Jan 19 2023 Key messages: 1) A Winter Storm Warning has been issued for much of our southeastern mountains and southeastern plains, where 4 to 10 inches of snow is expected between tomorrow evening and Saturday evening. 2) A Winter Weather Advisory has been issued for Pueblo and Crowley counties, along with the Wet Mountains. 3) A secondary storm system will bring a better chance of snow for the plains and a colder shot of air by late Sunday through Monday. There will be snow for the mountains, with the southeastern mountains receiving the highest amounts. 4) Persistent northwesterly flow in the mid levels will keep chances of snow continuing over the higher elevations. Tomorrow Night and Saturday Models are coming to a consensus on Friday night`s system, closing off a low around the Texas and Oklahoma panhandles by around 5pm tomorrow evening. This system is very compact, meaning that small changes in track could greatly impact expected snow totals across our plains. Though the potential for convective snow squalls is lacking with this system, very heavy snowfall rates are possible. Strong 700mb warm air advection, along with high omega values and isentropic upglide will likely lead to periods of very heavy snowfall at times, mainly late Friday night. High res models depict heavier bands developing slightly further north, over the Kiowa county area, while ensemble guidance keeps heaviest amounts further south, closer to Baca county. The NAM also shows a dry slot pushing all the way back into Baca county, which could limit snow potential for our furthest southeastern plains. For now, 4 to 8 inches is expected across portions of our southern Sangres, along with the Raton Mesa, Las Animas, Bent, Prowers, Otero, Baca, and Kiowa counties, where a Winter Storm Warning has been issued for tomorrow afternoon until Saturday evening. Winds are expected to gust up to 35 mph with this system as well, which could degrade visibilities and lead to hazardous travel conditions, especially along Highway 50 Friday night. Lesser amounts of generally 2 to 7 inches are expected for Pueblo and Crowley counties, along with our Wet Mountains, where a Winter Weather Advisory has been issued for tomorrow afternoon until Saturday evening. El Paso county could be added to the Advisory later, especially if the storm track changes as it evolves over the next 24 hours. For now, El Paso county is expecting anywhere from 1 to 3 inches. Sunday night through Tuesday morning... A deepening major shortwave embedded within the longwave trough is going to begin to propagate over the region, with snow beginning by later in the evening on Sunday. Given the orientation of this system, it will bring down a much colder cP airmass with it. Snow will be over the Palmer Divide by around 4 to 5 PM, and then spread southward throughout the evening and into the morning over the plains. Also due to the orientation of this wave, mountain snow will be more confined to the southeastern mountains with this system, although the San Juan Mountains could also do well with higher snowfall totals, depending on how close the low gets in proximity with the CWA. There will be some favorable isentropic accent over the Raton Mesa area and southern I-25 corridor, which will be the areas that likely receive the highest snowfall amounts through Tuesday morning. Upsloping will also play a role in allowing for there to be higher amounts along the eastern facing slopes of the southern Sangre de Cristo Mountains. Ensembles are beginning to close in with better confidence on just how cold this airmass will be, with high temperatures on Monday being around 20 degrees colder than the seasonal average for most locations. Deterministic models are still a little out of sync with the location of the associated low pressure center with this trough, which will have implications on which areas receive higher amounts of snow. The ECMWF has been the model that is more of the outlier with positioning the low much further to the southwest in comparison with the other models. The GFS20 keeps the low closer to the Four Corners area at around 5 AM on Monday morning, whereas the ECMWF has the position much further to the southwest, nearly over the center of Arizona. The Canadian is in much better agreement with the GFS20, although it has the low being a little slower in propagation, with the low being over the southeastern corner of Utah. If the GFS20 and Canadian models have a better handle on this system, we will likely receive higher amounts of precip over southeast Colorado. Tuesday afternoon through Thursday... There will be a break in precip as snow tapers off by later in the day on Tuesday and a shortwave ridge moves in behind it. However, with the longwave trough over the eastern CONUS, and a persistent northwesterly wind over the CWA, temperatures will remain relatively cold through Thursday. The northwesterly mid level flow will also keep chances of snow over the higher elevations from Tuesday afternoon through Thursday, with the rest of the CWA remaining dry. There will also be a third trough that will begin to approach the region, just beyond the forecast period, and could bring more snow chances to the plains again by the late part of next week. Ensembles keep temperatures on the colder side, but do have more dispersion towards the end of the forecast period. -Stewey && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 241 PM MST Thu Jan 19 2023 KCOS and KPUB... VFR visibility and ceilings with light winds under 10 KTS at at TAF stations KCOS and KPUB. However, due to forecasted light snowfall around at KCOS around 22Z, and KPUB around 21Z, ceilings and visibility may lower to MVFR. KALS... VFR visibility and ceilings along with light winds until around 17Z as the weather system will start moving in from the west. According to models, KALS will have light snow showers around 22Z. Ceilings and visibility at that point will be at MVFR conditions. -Riser && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 2 PM Friday to 5 PM MST Saturday for COZ074-075-087-088-093>099. Winter Weather Advisory from 2 PM Friday to 5 PM MST Saturday for COZ079-080-086-089. && $$ SHORT TERM...RISER LONG TERM...EHR/STEWARD AVIATION...RISER