Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/24/24


Area Forecast Discussion
National Weather Service Denver/Boulder CO
805 PM MST Sat Nov 23 2024 .KEY MESSAGES... - Mountain snow and light low-elevation snow late Sunday and Sunday night. - Heavier mountain snow late Monday night through Wednesday night with widespread and significant travel impacts likely. - Increasing potential for snow across the lower elevations Tuesday night and Wednesday. - Chilly but mostly dry Thanksgiving Day. && .UPDATE... Issued at 801 PM MST Sat Nov 23 2024 Moisture will move into the nrn mtns late tonight with snow chances confined to zn 31 towards morning. Otherwise, only minor adjustments made to temps and winds overnight. && .SHORT TERM /Through Sunday/... Issued at 146 PM MST Sat Nov 23 2024 Current observations across METARs display afternoon temperatures on track to reach above normal temperatures through the early evening hours across the region. Gusty southwest winds produce wind gusts up 35 mph continue over the higher terrain this evening due to an upper level jet. Cross sections display incoming upper level moisture tonight thus partly cloud skies are expected for most the of the lower elevations and foothills. Additionally, tonight`s temperatures slightly above normal as the plains reach 25-36F and mountains reach 14-27F. Our upper level pattern quickly changes by Sunday afternoon as a shortwave trough brings Pacific moisture through northwest flow. Orographic flow should lead to 2-5 inches mainly for areas above 9 thousand feet north of the I-70 corridor. A few mountain valleys in Jackson and Grand counties could also receive 1-2 inches of snow through Sunday. There is potential for the incoming cold front to arrive late Sunday afternoon shifting surface winds northwest. With mid to upper level cloud cover increasing by Sunday afternoon, it is possible a few areas across the plains may struggle to reach the mid 50s. Thus, this update includes a decrease in afternoon highs across the eastern plains. A few areas along the I-25 corridor will be able to peak through the cloud cover but expect upper 40s to mid 50s for the lower elevations. High temperatures for the high country reach the low 30s to low 40s. && .LONG TERM /Sunday night through Saturday/... Issued at 146 PM MST Sat Nov 23 2024 Widespread snow is expected in the mountains Sunday evening as the tail end of an upper level trough and left exit region provide lift. Cross sections show saturated air up to roughly 450mb. However, lapse rates will only be 5-7 C/km and mountain top winds end up being relatively weak (less than 20 knots). Add this up and the orographic lift component of this system is weak. Going snowfall forecast of 2-6 inches and up to 3 inches in the valleys looks on track. For areas east of the mountains...the foothills, urban corridor and plains, there seems to be decent model agreement between the GFS and ECMWF models and their ensembles with a period of light snowfall Sunday night. However, the NAM/RAP/HRRR models don`t have a clue. NAM cross sections for Sunday night show barely enough moisture for clouds, let alone snowfall. The NAM/RAP/HRRR keep primarily northwest (downslope) winds for most of Sunday night. With surface high pressure building in from the north, we should see a period of northeast to east winds as the GFS and ECMWF are advertising. These east to northeast winds lead to convergence along the foothills and upslope flow. Temperatures appear cold enough for all snow, though can`t rule out a little rain at first. Plan to nudge snowfall amounts up, especially on the west side of the urban corridor, in and near the foothills. Snowfall amounts still look to be on the light side, less than 2 inches, but a better chance for slick roads for the Monday morning commute across western portions of the metro area. It quickly clears Monday morning as upper level ridging and subsidence moves bringing mostly sunny skies. Temperatures will be a little cool with highs in the mid to upper 40s across northeast Colorado. For Monday night through Wednesday night, westerly flow aloft will transport Pacific moisture across the intermountain west resulting in snowfall for the Colorado mountains. For the first part of the storm, orographic lift will produce most of the snowfall across the mountains through late Tuesday. Then an upper level trough moves into the region providing lifting across the mountains and also for the lower elevations Tuesday night through Wednesday night. Still plenty of model differences out there regarding this storm. The latest models move up the timing of the trough passage. The GFS and its ensemble members are on the lower end for snowfall with less than a foot of snow for the mountains. The ECMWF and Canadian ensemble members favor 1-2 feet of snow for the mountains. Will trend the forecast towards the heavier amounts given the amount of moisture being transported into the region and the duration of snowfall being 48-72 hours for the mountains. For the lower elevations east of mountains, the upper level trough should bring a decent shot of snow late Tuesday through Wednesday night. Amounts are still quite unclear this far out, but it`s very likely we will see snow covered roads Wednesday and Wednesday night, leading up to Thanksgiving. For Thanksgiving, the upper level trough and snowfall associated with it shifts southeast of the area, with only a few ensemble members hanging onto snow in the morning. However, even though the snow is expected to be finished, roads will likely be slippery Thanksgiving morning. Northwest flow aloft will prevail behind the exiting system Thanksgiving. This combined with fresh snow covered will produce cool temperatures with highs in the 30s across northeast Colorado. For Friday and next weekend, a longwave trough will reside over northeast North America with a high over low set up along the west coast of North America. This pattern will bring northwest flow aloft to Colorado resulting in cool and dry conditions. Temperatures are expected to be below normal with highs in the 30s to lower 40s during this period. && .AVIATION /00Z TAFS through 00Z Monday/... Issued at 436 PM MST Sat Nov 23 2024 Winds will gradually shift to the south by 01z and then more SSW by 05z. On Sun winds will become SW by 13z. Meanwhile, confidence in wind direction by midday is low at best. HRRR has winds becoming gusty from the west while other models have a Denver Cyclone SW of DIA which leads to a more E or NE direction in the aftn. For now have maintained continuty with previous fcst and kept them from the west thru 22z. After 22z the winds may swicth to a more NW component. Meanwhile VFR conditions will continue tonight thru Sun aftn. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 6 AM Sunday to 6 AM MST Monday for COZ031. && $$ UPDATE...RPK SHORT TERM...AD LONG TERM...Meier AVIATION...RPK
Area Forecast Discussion
National Weather Service Cheyenne WY
640 PM MST Sat Nov 23 2024 .KEY MESSAGES... - Elevated to critical fire weather conditions and strong gusty winds will continue for portions of Carbon, Albany, and Converse counties through the early evening hours. - A storm system will bring colder temperatures and a chance for snow showers Sunday and Sunday night. Light accumulations are expected for the I-80 corridor west of Cheyenne. Winter Weather Advisories have been issued for the mountains. - Another round of snow showers and colder temperatures may impact holiday travel on Tuesday into Wednesday. && .UPDATE... Issued at 631 PM MST Sat Nov 23 2024 Strong winds with gusts over 40 MPH continue for the Arlington/Elk Mountain area this evening. Downsloping winds in this zone are also keeping relative humidity at critical thresholds, despite the sun going down. Observations from this zone show wind gusts between 35 and 45 MPH with relative humidity values below 15 percent. Due to the persistent critical fire weather conditions, did decide to extend the Red Flag Warning for the Arlington zone until 9 PM. Hopefully by then, humidity will recover above critical thresholds with lighter winds. However, will re- evaluate before the Red Flag Warning expires as the HRRR continues to show relative humidity below 15 percent through about midnight. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 200 PM MST Sat Nov 23 2024 A Pacific jet streaming across the Western CONUS this afternoon is producing plenty of mid to high level cloud cover over the area visible on the latest satellite imagery. While a low amplitude but fairly strong ridge is still holding on across the area, this will break down over the next 24 hours as the messy trough over the Pacific Northwest moves eastward. Currently, two distinct air masses are positioned over the area: a warm and remarkably dry airmass covering most of the area, while a surface high to the northeast is keeping cooler and more moist air in place mainly along/north of the North Platte River Valley. The boundary layer is extremely dry for this time of year southwest of the boundary, producing fairly widespread critical fire weather conditions when factoring in the gusty southwest winds. Additionally, gradients are strong enough to produce a few gusts in the 55-60 MPH in Carbon County. As we head into the evening hours, the surface high over western Colorado is expected to weaken, reducing the cross-barrier MSLP gradient and allowing high winds to die down. High Wind Warnings and Red Flag Warnings should be able to expire on time at 6PM, but RH will probably remain near critical to critical for a few hours after. Heading into tonight, an approaching shortwave riding along the jet stream will nudge into the area. Mid-level moisture will rapidly recover this evening, allowing orographic snow showers to return to the mountains after midnight. The boundary layer will still be extremely dry in the valleys, so it may take a few hours to moisten up the lower levels and allow snow showers to spread to the lower elevations. This should happen quickly after the shortwave trough axis and associated frontal boundary arrives, which is expected to be around 12z near Rawlins and Douglas. Expect rapid low- level moistening after this, which will then quickly increase snow shower coverage, driven primarily by frontogenesis. The cool-down and wind shift will happen fairly quickly over the High Plains, but the mid- level boundary and associated lift will be slower to clear out, not finishing up until a secondary trough axis/vorticity maximum clears the area Sunday evening. As a result, snow showers are expected to increase in coverage over the High Plains Sunday late morning into the afternoon, but downslope flow along/south of the North Platte River valley will undercut the lift. Accumulating snow is likely to be focused further north, in the Pine Ridge and vicinity where up to 1-2" will be possible. Further south, expectations are for just a few snowflakes to a half inch or so on the high end. Modest impacts are also likely for the I-80 corridor from the summit westward, where a general 1/2-3" can be expected. There is about a 20% chance of a higher end scenario which would warrant a Winter Weather Advisory for the Rawlins to Arlington corridor, but confidence is too low to issue any products at this time. As usual, the highest amounts will be in the mountains where low end advisory amounts of about 4-9" are expected. Therefore, a Winter Weather Advisory has been issued for the higher mountains in the Sierra Madre and Snowy range. Once the secondary trough axis clears the area Sunday evening, expect a quick end to precipitation as much drier air moves in along a subtle ridge axis. Expect cooler temperatures Monday, but the quick rebound of the ridge should lead to highs ending up just a few degrees cooler than average. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Issued at 200 PM MST Sat Nov 23 2024 Fairly zonal flow aloft expected for Tuesday ahead of an incoming shortwave trough from the northwest. Significant jet energy is expected Tuesday as the upper-level, 160kt jet moves overhead. Westerly flow remains throughout the atmosphere, leading to a 40kt jet across the Laramie Range Tuesday morning. Elevated winds will be likely along and just east of the Laramie Range along the I-25 corridor. High Winds are currently not expected, as the 700mb trough is not quite strong enough and in-house random forest guidance does not favor high winds for Tuesday. Rising motion associated with the upper-level jet combined with westerly to southwesterly 700mb and surface winds favor the development of upslope flow and moderate snow across the Sierra Madre Range, with the Snowies being mostly shadowed due to the wind direction. Near-average precipitable water values will favor continued development of snow showers across the higher terrain. The Sierra Madre Range could see over a foot of snow Tuesday morning through Wednesday evening. However, there is some disagreement between long range models of how much QPF will be available across the mountains. The ECMWF favors much higher QPF throughout the duration, while the GFS keeps slightly lower values. These differences result from the displacement of the surface low between models. the GFS keeps the low further south, while the ECMWF keeps it further north. The further north track is more favorable for heavier precipitation, due to wrap around moisture, while the southern path keeps much of the better moisture out of the region. An attendant cold front associated with the incoming upper-level trough will push through late Tuesday night into early Wednesday morning. Cold temperatures will pour into the region behind this front, with the upper-level trough quickly moving overhead. Long range models have come into better across on the progression of the cold front, with both the ECMWF and GFS pushing the front through by early Wednesday morning. Northerly flow will develop behind the passing front, though winds are expected to remain relatively light. The warmest temperatures on Wednesday are expected around midnight, with temperatures dropping steadily into the 20s and 30s area-wide. Overnight lows will drops into the teens and low-20s Wednesday night into Thursday morning. With the upper-level trough pushing through, rising motion will be present across the region, leading to the threat of isolated to scattered snow showers. The higher terrain is expected to continue to see snow throughout the day Wednesday, with lower-lying areas seeing the potential for snow throughout the day. Accumulations are not expected to be much across the region, outside of the mountains, due to the relatively warm conditions in the days leading up to this event. Any snow that falls will likely melt, due to the warmer ground conditions. The remaining forecast period remains unsettled, as primarily northwesterly flow remains aloft. Snow chances for the lower-terrain taper off by Thursday morning, but snow chances in the Sierra Madre and Snowy ranges continue through the period. With northwesterly flow aloft, winds are expected to remain elevated, especially across the wind prone regions of southeast Wyoming. Temperatures remain in the 30s and 40s as northwesterly flow acts to keep temperatures cooler by bringing in cooler Canadian air into the region. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 444 PM MST Sat Nov 23 2024 An incoming system overnight will increase clouds and precipitation chances over the area. A cold front will move from west to east over the forecast area tonight and through the day Sunday. KRWL will be the first terminal affected with low stratus and scattered snow showers forecast late tonight and early Sunday morning. Expect IFR conditions from both poor visibility in falling snow and low CIGs. Next precipitation and low CIGs will spread into KLAR by Sunday morning. Terminals east of the Laramie Range will see precipitation and low CIGs later in the day on Sunday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Red Flag Warning until 9 PM MST this evening for WYZ427. Winter Weather Advisory from 3 AM Sunday to midnight MST Sunday night for WYZ112-114. NE...None. && $$ UPDATE...SF SHORT TERM...MN LONG TERM...AM AVIATION...SF
Area Forecast Discussion
National Weather Service Quad Cities IA IL
549 PM CST Sat Nov 23 2024 .KEY MESSAGES... - Highs Sunday 8 to 13 degrees above normal. Near normal Monday, then below normal into late week. - One or more systems will be moving through the Midwest during the holiday period (mid week into next weekend). Considerable uncertainty exists regarding the track and potential for any impacts to the area. - The pattern change that occurred last week will remain active through early December. Temperatures will likely (70-90%) be below normal into early December. There is no clear signal that favors above, below, or near normal precipitation, which would more likely be snow with colder temps. && .SHORT TERM /THROUGH SUNDAY/... Issued at 315 PM CST Sat Nov 23 2024 Tonight, light southeast winds and high level clouds will be seen as high pressure drifts east and a low pressure system approaches from the central plains. Some fog is possible along highway 20 mainly mid to late evening into the overnight but confidence is low with light southeast winds increasing enough. Opted not to include in grids. Lows will be nearly steady in the mid and upper 30s. Sunday, the plains low will track over the area. This will usher in seasonable mild temperatures into the area on southwest winds. The gustier winds will be across the southern CWA late morning and early afternoon. As the warm front lifts through, can`t rule out some sprinkles early and then light rain/drizzle. Added some low POPS for light rain generally along and east of the MS River for after sunset into early Monday. Only expect a trace to a few hundredths at best of rain. Highs Sunday were nudged down a bit, but still look on track to be in the upper 40s to near 50 north, to the upper 50s to near 60 south. Normals are in the low to mid 40s. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Issued at 315 PM CST Sat Nov 23 2024 Monday and Tuesday, a high pressure ridge will traverse the area with mainly dry conditions. A cold front will be east of the area early Monday with brisk NW winds increasing through the day while ushering in much colder air. Temperatures won`t see much improvement on Monday, with steady or slowly falling readings in the mid 30s NW to low to mid 40s along and E of the river. Some lingering slight chances for light rain are in the NE Monday morning, and east for the afternoon. Tuesday looks to be quiet and chilly with below normal highs mostly in the 30s, as surface to mid level ridging dominates. Winds will be light west northwest with sunshine giving way to some increase in clouds. The Thanksgiving Holiday time frame remains a focus and potential time for precipitation, but there is still a lot of uncertainty. Through collaboration, bumped up POPS for Wednesday into Thanksgiving as some models hint at an fgen band initially Tuesday night into Wednesday across the north. Then, with a southern system tracking across MO which brings in precip chances across the SE two thirds of the CWA. With placement and timing differences, the end POPS are just slight to low chance (20-30%) with diurnally-driven precip types, snow versus rain. At this time, WPC has QPF focused south of the area, with the CWA remaining dry. Will need to monitor this due to the travel day and expect changes as we get closer. Beyond, confidence remains high on turning much colder and well below normal at the end of November and beginning of December. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 549 PM CST Sat Nov 23 2024 VFR conditions start off the TAF period, with BKN high cirrus clouds overhead. The main focus for tonight continues to be on fog potential for areas north of Highway 30, including the DBQ TAF terminal. Latest models suggest a little later time frame for fog development than previously expected, with the possibility of some IFR visby reductions late tonight, so have made adjustments to capture this. Additionally, strengthening low-level flow aloft will support low-level wind shear at BRL, which is indicated by both the NAM and RAP models. Otherwise, expect southeasterly flow during the daylight hours Sunday, with continued VFR clouds. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...14 LONG TERM...14 AVIATION...Schultz
Area Forecast Discussion
National Weather Service Goodland KS
425 PM MST Sat Nov 23 2024 .KEY MESSAGES... - Patchy fog possible tonight-Sunday morning east of a line from McCook to Hill City. Dense fog is possible. - Precipitation chances (20%-40%) continue Tuesday night through the day Thursday with the emphasis of better chances Tuesday night and Wednesday for light rain showers and snow showers. - Above normal temperatures Sunday fall to below normal levels Monday through Saturday. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 145 PM MST Sat Nov 23 2024 Tonight...the forecast area will be under west-southwest flow aloft with cirrus clouds moving through. Low temperatures are forecast to be in the upper 20s to middle 30s. RAP/HRRR/NAM visibility forecasts are forecasting some fog across the eastern 1/4 or so of the area after about midnight. Dense fog is possible. Sunday-Sunday night...any morning fog across the eastern 1/4 or so of the area in the morning is forecast to dissipate/move out of the area by mid to late morning. Otherwise, an upper level trough passes through the area late in the afternoon, pushing a cold front through the area. No moisture to work with so we`ll continue with a dry forecast during the day. Overnight, the moisture profile in the 850- 500mb layer does improve and for now we`ll keep silent pops going generally north of Interstate 70. High temperatures are forecast to range from the 40s in snow covered areas of Cheyenne/Kit Carson counties in Colorado to the 50s and lower 60s elsewhere. Low temperatures fall into the lower to middle 20s. Monday-Monday night...although the upper trough axis moves away from the area during the day, there is disagreement amongst the NAM/GFS/ECMWF models on the 850-500mb moisture profile with the NAM the driest amongst the three and the GFS/ECMWF models agreeing with each other and the NBM current forecast. High temperatures fall back into the lower to middle 40s with low temperatures in the lower to middle 20s. Tuesday-Tuesday night...zonal flow is established during the day, ahead of an approaching open wave trough that reaches the northern plains southwest into the Colorado high country. Favorable moisture in the 850-500mb layer holds off until the overnight hours when 20%- 30% chances for light rain showers and snow showers reach parts of far eastern Colorado. With NAM/GFS 850mb temperatures warming 9F to 11F compared to Monday, high temperatures in the lower to middle 50s look good. Low temperatures are forecast to be in the 25 to 30 degree range. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Issued at 145 PM MST Sat Nov 23 2024 Wednesday...there is pretty good agreement between the GFS/ECMWF/GEM/GEFS models in supporting 20%-40% chances for light rain showers and snow showers during the day as the upper trough moves through. These models also bring in a lot of dry air behind the trough passage overnight, supporting a dry forecast. The NBM and current forecast has 20%-40% chances for snow showers overnight. We`ll watch upcoming model cycles and see if this trend continues or follows the GFS/ECMWF/GEM/GEFS trends of a dry overnight period. High temperatures are forecast to be in the lower to middle 40s with low temperatures in the upper teens to lower 20s. Thursday...the forecast area is forecast to be under northwest flow aloft. The current forecast has a 20% chance for light snow showers in the morning along and north of Interstate 70 but given the GFS/ECMWF/GEM 850-500mb relative humidity forecasts of rather dry air, I`m doubtful we`ll get any precipitation for the entire day. High temperatures will be rather chilly in the middle 30s to lower 40s. Low temperatures are forecast to be in the teens. Friday...we remain under northwest flow aloft. Presently, the forecast remains dry as the better 850-500mb moisture needed for precipitation remains to the northeast and east of the area. High temperatures are similar to Thursday in the middle 30s to middle 40s with low temperatures in the middle teens to lower 20s. Saturday...not much change in the 500mb pattern nor at the surface with dry weather forecast and high temperatures in the middle 30s to middle 40s and low temperatures in the 10F to 15F range. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 425 PM MST Sat Nov 23 2024 GLD: VFR conditions will rule through the TAF period, with ceilings confined to cirrus at or above ~20,000 ft AGL. Light (5-10 knot) southeasterly or variable winds will prevail through sunrise Sunday. Winds will shift to the N or NNE and modestly increase to ~8-14 knots late Sunday morning (~17Z) and persist through the afternoon. Northerly winds will further increase to 15-25 knots around sunset Sunday evening (~00Z Mon) -- in assoc/w rapid surface pressure rises -- as Canadian high pressure (centered over southern Alberta) builds/extends southward along the lee of the northern and central Rockies. MCK: Fog may develop over portions of south-central Nebraska and central Kansas early Sunday morning (~07-14Z Sun). While fog is possible at McCook.. visibility forecasts via recent runs of the HRRR suggest that locations east of McCook are most at-risk for early morning fog. Otherwise, VFR conditions will rule through the TAF period with ceilings confined to cirrus at or above ~20,000 ft AGL. Light (4-8 knot) southeasterly or variable winds will prevail through sunrise Sunday. Winds will shift to the N or NNE and modestly increase to ~8-14 knots late Sunday morning (~17Z) and persist through the afternoon. Northerly winds will further increase to 15-25 knots around sunset Sunday evening (~00Z Mon) -- in assoc/w rapid surface pressure rises -- as Canadian high pressure (centered over southern Alberta) builds/extends southward along the lee of the northern and central Rockies. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ SHORT TERM...99 LONG TERM...99 AVIATION...Vincent
Area Forecast Discussion
National Weather Service Green Bay WI
500 PM CST Sat Nov 23 2024 Updated aviation portion for 00Z TAF issuance .KEY MESSAGES... - The chances for light rain and snow from Sunday night through Monday night have increased. There is a 40-50% chance of getting at least 1 inch of snow in north-central WI, and a 30% chance to get at least 2 inches of snow. - Light lake effect snow at times over far north-central Wisconsin mid to late next week. Only minor accumulations are expected. - A cooling trend takes hold for the coming week. Highs in the 30s and 40s into Monday will cool into the 20s to 30s by the middle of the week, and into the 20s across the entire area by next weekend. && .DISCUSSION... Issued at 320 PM CST Sat Nov 23 2024 Short Term...Tonight and Sunday Main focus for the remainder of today is cloud trends. Current satellite imagery shows partial clearing across northern WI, while the rest of the region remains under a blanket of mid-level clouds. These clouds are streaming in in advance of an upper trough that is forecast to arrive to the region tomorrow. Radar has picked up a few weak echos early this afternoon across central WI as weak frontogenesis is driving areas of virga. However, area web-cams have shown no signs of any precipitation reaching the region. A weak ridge sliding over the region overnight will keep the dry conditions around through Sunday morning. Warm air advection ahead of the aforementioned upper trough may produce scatter areas of drizzle beginning Sunday afternoon, however, forecast soundings are split as to if any precipitation will make it to the ground. NAM soundings continue to be the most aggressive with sufficient saturation taking place during the afternoon to get areas of drizzle, while RAP soundings are slower to saturate resulting in a later onset of any precipitation. Regardless do not expect any impacts through Sunday afternoon. Precipitation chances do increase Sunday evening as does the chance for accumulating across northern WI. Long Term...Sunday Night Through Saturday A surface low moving from Missouri to Lake Huron will bring some light rain and snow to the region Sunday night through Monday evening. Most of it will fall as rain Sunday night, but the rain should change to snow across north central Wisconsin Monday before it diminishes Monday evening. An inch or two looks likely there with not much elsewhere. Winter will finally begin to arrive during the middle of next week, as the medium range models show an upper ridge begin to build along the west coast, and a trough over central Canada and the Great Lakes region. Temperatures are forecast to be below normal by the end of next week, with subzero wind chills possible Friday and Saturday night. A surface low moving from Oklahoma to the Ohio Valley looks like it could bring some light snow to southern Wisconsin Wednesday night, but otherwise the northwest upper flow will result in dry weather Wednesday through Saturday outside of some light lake effect snow in Vilas county. && .AVIATION...for 00Z TAF Issuance Issued at 500 PM CST Sat Nov 23 2024 High and mid clouds are expected across the area tonight as they stream in from the west. Some MVFR stratus will be possible this evening across the far north with northwesterly flow. VFR conditions will continue into Sunday with thickening and lowering clouds throughout the afternoon. Lower CIGs and precipitation is expected to hold off until Sunday evening as a surface trough tracks through the area. Light surface winds below 10 knots are expected during the TAF period. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....GK/RDM AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service North Platte NE
542 PM CST Sat Nov 23 2024 .KEY MESSAGES... - Patchy fog development tonight into Sunday morning across southwest into south central Nebraska with visibilities of < 1 mile possible at times. - A cold front moving in Sunday will bring much cooler temperatures, breezy winds, and a threat for light snow (< 1") across portions of northwest Nebraska. - Benign weather Monday and Tuesday before an even colder airmass settles into the central US by the middle to end of next week. A threat for wintry precipitation exists, potentially impacting Thanksgiving holiday travel, however, uncertainties remain in regards to snow accumulations. && .SYNOPSIS... Issued at 244 PM CST Sat Nov 23 2024 Recent GOES-16 WV imagery and RAP 500-mb analysis showed a broad ridge extending across the central CONUS. An upper-level low was centered over the north Atlantic, tracking northeast into Canadian Maritimes. Just to the east of this feature, an upper-level trough was sliding southeast across northern Ontario. A robust upper-level low pressure system continues spinning off the coast of British Columbia with a trough extending southwest into the eastern Pacific. Multiple shortwaves and vorticity lobes were ejecting inland within the southwest flow aloft over the Pacific Northwest and northern Rockies. At the surface, a weak back-door cold front was draped across western and central Nebraska. Widespread cirrus clouds continue to move into the area with a stratus deck noted over portions of northern Nebraska. Given the cloud cover, temperatures have trended cooler than previously expected, especially for northern Nebraska, with 2 PM CT temperatures ranging from 30 degrees at Valentine to 54 degrees at Imperial. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 244 PM CST Sat Nov 23 2024 A potent upper-level shortwave will eject from the main system centered off the coast of the Pacific Northwest into the northern Rockies late tonight. As this shortwave moves eastward into the northern Plains, a cold front will be forced southward, moving through the area late tonight into Sunday morning. Ahead of the front, patchy fog development appears increasingly possible across portions of southwest and south central Nebraska resulting in visibilities falling to 1 mile or less at times. Although high clouds may pose a less favorable environment, it appears breaks in the clouds and light winds may be just enough to allow fog to development. Visibility may change rapidly while driving, so Sunday morning travelers over the aforementioned areas should stay alert. As the front clears the forecast area Sunday morning, northwest/north winds will strengthen behind it with 3 to 4mb/3 hour pressure rises and cold air advection (CAA) increasing across western and north central Nebraska. Widespread gusts in excess of 20 mph will be common during the day on Sunday with the strongest gusts of 30 to 35 mph expected across northern Nebraska. As for Sunday`s highs, temperatures will range from the upper-30s behind the front across northern Nebraska to the mid-50s ahead of the front across southwest Nebraska. This frontal passage will bring the first of a series of cold air intrusions expected through the week with Sunday night`s temperatures falling near 10 degrees across northwest Nebraska to near 20 degrees across southwest Nebraska. With breezy northwest winds gusting up to 25 mph through the night, we will see some chilly wind chills falling into the single digits by Monday morning. The cold overnight temperatures, increased moisture and mid-level forcing will present a threat for light snow/flurries across northwest Nebraska Sunday night, potentially extending east into north central Nebraska. Little to no accumulation is expected with current NBM Probabilities of 24 Hour Snowfall > 1" remaining at 20% or less for northwest Nebraska. At this time, any winter weather impacts appear low, though this will lead to much colder temperatures as we head into Monday. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 244 PM CST Sat Nov 23 2024 As the flow aloft becomes zonal and surface high pressure builds southward out of Canada, quiet conditions will settle into the area Monday and Tuesday. With CAA continuing across the region, temperatures will fall into the 30s to low-40s on Monday. Although temperatures moderate back into the 40s as the upper-level ridge flattens over the northern Plains on Tuesday, an even colder airmass settles into the region for Wednesday and beyond. The main focus in the long term revolves around the next system ejecting out of the Rockies mid-week, potentially impacting Thanksgiving holiday travel across our area. This mid-week threat for snow remains low confidence as the deterministic ECMWF, GFS, and Canadian continue to have run-to-run differences on the evolutions of this system. As a heavily tilted upper-level trough extending from the northern Rockies into northern California advances eastward into the Plains through Wednesday, a lee-cyclone will develop across southeast Colorado driven by mid-level height falls and upper-level divergence. The main surface low will track southeast into the Oklahoma/Texas Panhandles, remaining well south of the area. Despite this, a cold frontal passage will bring increased mid- level forcing, resulting in a threat for light snow across western and north central Nebraska. Although discrepancies exist amongst deterministic guidance, 50% or more of the GFS and ECMWF ensemble members highlight the potential for light snow, perhaps accumulating snow. Although uncertainties remain, with such cold air in place, the threat for accumulating snow is non- zero across the area with NBM Probabilities continuing to highlight a 15% chance or less of 1"+ of snow. Thanksgiving travelers should continue to stay up to date on the latest forecast and be prepared to make adjustments to your plans if needed, especially those who may be headed to Colorado where the greater potential for winter impacts exists. The one thing that appears more certain with this system is the northern Plains seeing the most significant cold air outbreak of the season thus far. Ensemble guidance shows a ridge developing over Alaska and northern Pacific, favoring surface high pressure to build southward into the central CONUS by late next weekend, continuing into the 7 to 10 day range. Just how cold it will get remains uncertain at this time, however, confidence continues to increase in a period of sub-freezing and perhaps well-below freezing temperatures to be felt across the region as we head into the first part of December. This is highlighted by CPC`s 6-10 Day Temperature Outlook favoring below normal temperatures across the eastern third of the CONUS. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 541 PM CST Sat Nov 23 2024 For the KLBF terminal: Lower clouds will move into the area overnight with ceilings around 2500 FT AGL. There is also a threat for patchy fog at the terminal with visibilities as low as 2sm during the overnight hours. Skies will scatter out on Sunday with scattered ceilings around 20000 FT AGL. For the KVTN terminal: Expect ceilings below 1000 FT AGL through 08z overnight. Skies will remain cloudy, however, ceilings will increase to around 12000 FT AGL as winds shift to the west then northwest overnight. Lower ceilings will then set back in by mid to late morning Sunday with cloud decks around 2000 FT AGL. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Viken SHORT TERM...Viken LONG TERM...Viken AVIATION...Buttler
Area Forecast Discussion
National Weather Service Marquette MI
704 PM EST Sat Nov 23 2024 .KEY MESSAGES... - Active weather with periodic chances for accumulating snow return next week. Temperatures will begin to trend below normal for this time of year. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 218 PM EST Sat Nov 23 2024 Water vapor imagery and RAP analysis show a low amplitude mid-level ridge across the central U.S. and a mid-level low over the NE U.S. To the n, another mid-level low is centered in nw Ontario. A shortwave extends from that low into northern and eastern Lake Superior. KMQT radar and visible satellite show nw flow lake effect rain and snow showers across much of the fcst area. Latest RAP analysis indicates temps at the base of inversion at 850-800mb are at -7C to -9C, marginal for the ongoing light lake effect pcpn. The aforementioned shortwave could be providing weak enhancement to the lake effect showers. With caa lowering 850mb temps down to -8 to -10C through this evening, expect nw flow lake effect pcpn to continue, especially east where the colder 850 mb temps will be and where the longer fetch will be across northern and eastern Lake Superior. However, with inversions heights only at 4-5kft, and even a little lower over the western fcst area, expect any lake effect pcpn to be light through this evening. Ridging building in from the west, especially late tonight, should taper or end lake effect showers for all areas except maybe the far eastern cwa. Min temps tonight under partly to mostly cloudy skies will be generally in the mid to upper 20s inland to around 30F near the Lake Superior shore. && .LONG TERM /SUNDAY THROUGH SATURDAY/... Issued at 443 PM EST Sat Nov 23 2024 Starting Sunday, a mid level ridge moves east into the Great Lakes. That said, the cloud cover is still expected during the day with troughing building in from the west. Highs on Sunday are forecasted in the mid 30s to low 40s. The dry period then ends Sunday night into Monday as a clipper low approaches from the Canadian Provinces, phasing with a Colorado low that lifts into the Great Lakes on Monday. Isentropic ascent looks to kick off some showers Sunday night from the south, which expand northeast across the UP through Monday as the features phase together and the mid level trough begins swinging through the region. Where there still is some uncertainty in the forecast is the sfc low track. The NAM and much of the high resolution model guidance are in "camp one" where the Colorado low takes a more northerly track over southeastern WI and over northern/central Lower MI. This track which would bring a warmer airmass to our CWA and start precip earlier in the CWA. This solution also would imply a brief period where a wintry mix of rain/snow/sleet, most likely in the interior central UP (near Iron Mountain). Some freezing rain is also possible Sunday night over that region with a marginal warm nose above 5kft. Ice accumulations would likely be sparse at best, around a trace early Sunday night. Otherwise, snow is expected north and west of the wintry mix area and mainly rain showers with some snow mixing in later in the day near Lake MI. "Camp two", being the rest of the guidance such as the GFS and ECMWF, take the sfc low over southern Lower MI. This would result in less wintry mix, which would be mostly rain and snow) and more snow overall in the CWA with a cooler airmass overhead. Either solution looks to result in some light snow accumulations over the north half of the UP and possibly some slippery road conditions going into Monday. Monday night through Tuesday, the mid level trough pivots over the Upper Great Lakes. This is the beginning of troughing period over the Great Lakes, yielding cold northwest to north flow that is expected the rest of the extended forecast. 850 mb temps diminish from around -7C Monday night to around -13C by the end of next week, sufficient for LES (especially with Lake Superior being warmer than normal for this time of year with average sfc temps ~8C). Several inches of snow are likely over the course of next week, especially over the east where some pre treatment from Lake Nipigon is expected. Currently, Wednesday and Thursday look to bring the least amount of precip with weak sfc ridging passing through briefly. Temps trend toward below normal for Thanksgiving weekend. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 703 PM EST Sat Nov 23 2024 Persistent MVFR cigs will continue at IWD and CMX through the night as low level moisture remains trapped under an inversion. Some fluctuation to VFR at SAW is occurring, but expect MVFR to be predominant at SAW as well through the night. No wind impacts, light and variable. && .MARINE... Issued at 443 PM EST Sat Nov 23 2024 Northwest winds of 20-25 kts over the east half of the lake this afternoon diminish this evening, falling below 20 kts across the lake. Winds veer northeast for Sunday then east Sunday night as broad ridging moves through the Upper Great Lakes. While a few gusts up to 20 kts are possible over the western third of the lake late Sunday (~20% chance), winds are expected to hold mainly below 20 kts until Monday night when a Colorado low moves through the Great Lakes. This Colorado low phases with another low approaching from the Canadian Provinces on Monday resulting in an uptick in northwest winds of 20-25 kts Monday night through Tuesday. Strongest winds up to 30 kt are possible on Tuesday, mainly over the waters south of the Keweenaw (~50% chance). Winds then weaken to 20 kts or less again Tuesday evening as the now phased low pulls away towards the Atlantic. With weak impulses from the north moving through the area much of next week, expect the light northwest to north winds mainly less than 20 kts to continue until late next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...Jablonski AVIATION...TDUD MARINE...Jablonski