Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/29/21

Area Forecast Discussion
National Weather Service La Crosse WI
535 PM CST Thu Jan 28 2021 .SHORT TERM...(This afternoon through Friday) Issued at 1242 PM CST Thu Jan 28 2021 At 18Z, surface high pressure was over the area with light winds and broken sunshine. Further west, over western MN/IA, a sharp increase in the pressure gradient is causing some blowing snow with gusts to 30 mph in SW MN and visibility reductions. Low clouds are streaming northward along a moisture axis from eastern KS into this same area, converging into trough/wind shift across southern MN. While temperatures at the surface dont exhibit this, aloft a warm front and warm advection is occurring west of I-35. Morning RAOB temperatures at 850mb of -11C/-1C at MPX/ABR indicate the strong front in place. This entire area of warm advection, convergence, and cloud will translate east overnight to about the Miss river with about 1-1.5 km of low-level saturation. Most of the warm advection is centered near 850mb and remains west of the Miss river, strongest around midnight and weakening into the morning per RAP analysis. Both the latest RAP and NAM have this same suggestion and do dribble some light QPF out...mainly flurries or drizzle. Forecast soundings would suggest temperatures in the near-ice nucleation region of -10 to -12C but warming overnight in the warm advection. Thus, flurries look to be mainly the type should enough lift occur along the warm front in eastern MN/IA overnight. Worst case scenario some patchy freezing drizzle occurs. At this time, it appears FZDZ is too low a probability outcome to include in the forecast. But, will add flurries west of the Miss river and monitor this evening and overnight. .LONG TERM...(Friday night through Thursday) Issued at 206 PM CST Thu Jan 28 2021 Model solutions continue to settle down and offer similar solutions for the upcoming weekend system. Good consensus now that the system will track from the Texas Panhandle northeast to the lower Great Lakes/Ohio River Valley area from Saturday morning through Sunday. This will take the strongest forcing from the short wave trough by just to the south of the area, but still close enough that there will be plenty of lift that spreads across the area. As the system approaches, a general 2 to 4 ubar/s of up glide on the 290K isentropic surface will spread over the area to help form the initial precipitation Saturday afternoon. Looking at forecast soundings for this period, there will initially be some dry air to overcome which could lead to a short period of some freezing drizzle before the column saturates deep enough for a change over to all snow. This change over will be aided by the development of a mid level frontogenesis band that develops on the north side of the surface low Saturday evening but moves pretty quickly off to the northeast overnight into Sunday morning. This signal for some mixed precipitation continues to be seen in some of the 28.06Z GEFS members as well. Once the precipitation switches over to snow, the various ensemble members have settled in to showing about 3 inches up into the Interstate 90 corridor with around 5 inches for the far southern sections of the area. This looks to be a pretty solid advisory with the small threat of some warning criteria snows across the south. The ECMWF EFI continues to be between 0.8 and 0.9 with this system suggesting most of the members indicate a decent system, but likely not strong enough to make it significant with widespread warning criteria amounts. This seems reasonable with the 28.00Z NAEFS holding steady with precipitable water amounts about 1 standard deviation above normal with amounts above 0.5 inch but less than 0.75 inch. Based on this assessment, not planning for any headlines with this system at this time. Looking out past the weekend system, there appears to be another on the horizon for the middle of the week. Initial indications are this may be a stronger system than the upcoming weekend one but also take a more northwest track. This could mean more of mixed precipitation scenario. For now, will let the model consensus grids do their thing with this system. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 535 PM CST Thu Jan 28 2021 Feed of moisture ahead of low pressure over the High Plains will produce widespread MVFR/IFR stratus at the KLSE/KRST sites later tonight int Friday (KRST after 04z/KLSE after 07z). A few flurries will be possible as well mainly at KRST from 04-14z but no reductions in vsby expected. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Baumgardt LONG TERM...04 AVIATION...DAS
Area Forecast Discussion
National Weather Service Dodge City KS
531 PM CST Thu Jan 28 2021 ...Updated Aviation... .SHORT TERM...(This evening through Friday) Issued at 248 PM CST Thu Jan 28 2021 The trend is for much warmer air over the extreme southwest counties late this afternoon, much like the HRRR model output. Highs can reach the low 60s over the Cimarron grasslands...and still only to just above the freezing point north of the K-96 corridor. The breezy conditions will likely slack off with the the diurnal trend. However the southerly winds will persist overnight. The surface high pressure center and axis of coldest air this evening will be centered over northcentral/northeast Kansas. This will leave southeasterly winds early , becoming more southerly overnight. The models that can produce visibility fields are all in agreement on a layer of freezing fog in the BL basically centered over northwest kansas. The uncertainly lies in if the fog develops as far south as the KS/OK line as the WRF models suggests (unsupported by the HRRR/RAP). Overnight lows again spatially look to be most mild over the red hills and south central Kansas counties, , generally in the upper 20s...with more variability in the upper teens and low 20s across west central Kansas (Hays-Dighton-Syracuse). .LONG TERM...(Friday night through Thursday) Issued at 248 PM CST Thu Jan 28 2021 Friday will be a challenging afternoon for the temperature forecast with downsloping wind becoming more pronounced and the large area of snow cover needed to melt away to achieve maximum temperatures. Windy conditions are expected on Saturday as a front swings though the area in the morning with a decent gradient over western Kansas through the day. Not necessarily a perfect high wind scenario, however the GFS and ECMWF at this time have solid 30 to 35 knot winds in the 850 mb layer at 18Z Saturday. A decent belt of warm advection precipitation out ahead of the developing surface low will offer a chance for rain over just about anywhere, but even a few thunderstorms the farther southeast toward the OK line. A very amplified system, tapping arctic air comes out of the west next week, shown by the Canadian/GFS/ECMWF. This will develop an intense cyclone over the central plains, leaving large uncertainty at this time yet where the main axis of wintry impacts will be. The one constant for our area of Kansas looks to be strong to high winds (if dry slotted), which very well could be the case, the GFS is showing at this time. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 525 PM CST Thu Jan 28 2021 VFR flying conditions are expected this TAF period for all terminals except HYS which could drop to MVFR/IFR owing to fog development roughly in the 05-11Z time frame. Low level wind shear is also expected to impact all terminals overnight as a 35-45 kt southwesterly low level jet overspreads southwest Kansas. Winds will stay light to moderate roughly out of the south, but could become gusty at times at DDC and LBL. && .PRELIMINARY POINT TEMPS/POPS... DDC 28 54 35 49 / 0 0 10 30 GCK 22 53 31 49 / 0 0 0 10 EHA 34 66 36 56 / 0 0 0 0 LBL 29 62 35 56 / 0 0 10 10 HYS 22 41 28 38 / 0 0 0 30 P28 29 55 41 54 / 0 0 20 60 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...Springer
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
611 PM EST Thu Jan 28 2021 .AVIATION... MVFR to lower VFR stratus will persist overnight, but trend from OVC to BKN with time as drier low level air works gradually into the area as a ridge of high pressure settles into the central Great Lakes. This trend will continue into Friday with SCT conditions developing. A weak pressure gradient associated with the high will also favor light winds under 10 knots this forecast with a slow backing from NW to WNW/W. For DTW...This will remain aob 5kft tonight, but scatter out on Friday as high pressure builds into the area. WNW winds under 10 knots will prevail for the forecast period. DTW THRESHOLD PROBABILITIES... * High in ceilings at or below 5000 feet through this evening. Moderate tonight and low Friday morning. && .PREV DISCUSSION... Issued at 433 PM EST Thu Jan 28 2021 DISCUSSION... Meridional surface pressure ridge axis (+1032 mb, 90th climatological percentile per NAEFS/ECMWF climatology...per overnight afd last night) is in place from Far-Northwestern Ontario southward through Lake Superior to Wisconsin. The position of the surface high is leading to cold north gradient flow across Southeast Michigan. The surface ridge is forecasted to hold position through the next 24 hours. 850mb temperatures this afternoon are running at -17 to -18C and has activated high amount of lake effect stratocumulus downwind of the Lake Superior and the N. Lake Michigan- Huron aggregate. Boundary layer depths are running some 3.5 kft this afternoon which is extending into -12C to -14C isotherms for ice nucleation. Latest radar imagery depicts light returns across the forecast area, flurries are expected to persist throughout the remainder of this afternoon and into the evening. The question for tonight centers on the cloud forecast. Uncertainty exists with the typical moist NAM holding saturation sub 4.5 kft agl base. On the other hand, the RAP is drier at the top of mixed layer after 09Z bringing a clearing trend particularly across the southern cwa daybreak Friday morning. Pattern recognition of cold northerly flow sides with a more pessimistic forecast which favors the inherited cloudy forecast. Do actually favor more clearing for late Friday afternoon as models show a very aggressive increase in anticyclonic flow trajectories late afternoon with very efficient dry isentropic downglide. The inherited forecast has this clearing forecast for late Friday well in hand. The focus of the Medium Range is centered on the accumulating snow potential early Sunday morning through Monday/Mon evening. Remarkable intra-model/run-to-run continuity has existed with regards to both the low pressure track and the axis of heaviest precipitation. No real surprises with the 28.12Z deterministic solution output with heaviest precipitation axis remaining south and west of Lower Michigan. From a big picture dynamic view, rapid cyclogenesis will be supported in the lee of Rocky Mountains/Central Plains as dynamic Potential Vorticity anomaly ejects rapidly out of the 4 Corners. Very favorable upper level left exit region jet dynamics will support sub 998mb surface cyclone across Missouri and western IL Sat night. The low is then forecasted to weaken rapidly as it crosses the Mississippi River. Sharpness to the composite trough is lost with the upper level low closing off and becoming vertically stacked. Main dynamical reasoning is that trough remains fairly progressive and gets caught up within a very impressive zone of upper level confluence off of preceding jet max. Given the setup and separation between the upper level jet cores there is high confidence in this weakening and zonal track of the low pressure Sunday. In fact, there is a very low amount of variance that is depicted in the Ensemble Cluster EOF technique. So the questions for Southeast Michigan are: 1. How progressive will main warm advection snow be after 09Z Saturday night (Important for both the start time of accumulating snow and how far north the accumulating snow will make it on the front end.) 2. How formidable will the dry air feed be funneling directly into Southeast Michigan from the east Sunday (Given the strong east to west gradient flow any more weakening of the barotropic low should significantly undercut the northward transport of moisture, i.e. increase in bust potential here locally). With that stated the heaviest QPF placement is immediately south of the forecast area so margin of error is less for Monroe and Lenawee counties. Given a survey of EPS members along with latest Probabilistic forecast information offered by NBM, favor a solution that calls for categorical/likely PoPs for accumulating snow late Saturday night and Sunday. Highest confidence exists in accumulations of a couple of inches or more south of 8 mile. Given forecast soundings and plan view of thermals, higher than normal confidence exists that all precipitation will fall in the form of snow with this event. Another uncertain aspect of this event is whether or not the potential for accumulating light snow may extend into and throughout the Monday/Monday evening timeframe. Models are showing that absolute vorticity energy may consolidate on back edge of the trough and lead to a persistence of inverted troughing northward through western Lake Erie back into far eastern Lower Michigan. It is always difficult forecasting exact absolute vorticity energy and deep moisture/saturation evolution at these timescales within broad troughs. The potential is certainly there for grinding out light snow through Monday evening. This would most likely be east of U.S. 23. Given Southeast Michigan`s proximity along the northeast fringe of precipitation swath, did want to refrain from getting too specific in messaging today. MARINE... Elongated high pressure moves over Lake Michigan tonight with northwest wind around 15 to 20 kt, gusts 25 to 30 kt over Lake Huron, continuing into Friday. Extended the Small Craft Advisory around the Thumb into Friday with wave heights reaching near or just above 4 feet expected to persist across the nearshore waters. The high pressure slowly drifts east over the central Great lakes by early Saturday with winds then becoming light and variable. Low pressure then moves from the mid-Mississippi Valley into the Ohio Valley by Sunday, shifting winds from the east and northeast by late Saturday. Winds will remain below gales but the easterly trajectory brings onshore wave activity that will likely necessitate another round of Small Craft Advisories beginning early Sunday. The system brings a good chance for a period of snow across Lakes Erie and St. Clair for Sunday into Monday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Small Craft Advisory until 4 PM EST Friday for LHZ421-441>443. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....DG DISCUSSION...CB MARINE.......TF You can obtain your latest National Weather Service forecasts online at
National Weather Service Hastings NE
522 PM CST Thu Jan 28 2021 ...AVIATION UPDATE... .DISCUSSION...(This evening through Thursday) Issued at 316 PM CST Thu Jan 28 2021 Fog from this morning was slow to clear, but has largely mixed out as of this afternoon. Stratus remains in place across most of the area (except for our southern most KS counties). As a result, temperatures have struggled to rise any higher than the low to mid 20s for most locations. A few breaks in the clouds are possible late this afternoon and evening, but additional low stratus and fog is expected to redevelop again tonight. The HRRR and RAP show the thickest fog developing over northwestern portions of the area. Therefore a dense fog advisory was issued for this area. Dry conditions are expected on Friday, but lingering fog and cloud cover will make for another cold day. Temperatures were nudged down several degrees, and many locations will remain below freezing. Friday night, a quick moving shortwave trough will push across the southern Rockies, lifting towards local area early Saturday morning. This will bring a chance for precipitation to the area during the day on Saturday. Most models continue to show the bulk of the QPF remaining largely east of the local area. Even still, we could still see some light freezing drizzle at the onset, followed by flurries or light snow/sleet, and then possibly another round of light freezing drizzle on the back side of the system. This may be just enough to lead to spotty slick roads across the area. In addition, northwest winds will also pick up on the west side o the system on Saturday. While not excessively strong, we may have wind gusts up to 35 MPH at times. The concern here is that some locations (especially the west) will remain cold enough that the existing snowpack will not have an opportunity to crust over. Therefore some patchy blowing snow was added to the grids. Mid and upper level ridging will return for early next week. This will lead to a bit of a warming trend, but this will be rather slow given the deep snow cover. High temperatures are forecast to return to the high 30s to low 40s on Tuesday. The next storm system is forecast to impact the area late Wednesday into next Thursday. While this has the potential to be a significant winter storm, model ensembles have actually backed off on its strength over the past couple model cycles. Nevertheless, this will be something to continue to monitor over the coming days. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday) Issued at 518 PM CST Thu Jan 28 2021 Cigs continue to flirt the line between MVFR and IFR but should be improving more solidly to MVFR over the next few hours. Fog is the main concern again tonight, especially for KEAR where fog is expected to be dense at times during the early morning hours and possibly into the mid morning. KGRI will likely see fog as well, though visibilities are likely to be slightly better than KEAR. Fog will likely linger again through a good part of the day as it did today. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Dense Fog Advisory from 9 PM this evening to noon CST Friday for NEZ039-040-046-060-061-072-073-082. KS...NONE. && $$ DISCUSSION...Mangels AVIATION...Shawkey
Area Forecast Discussion
National Weather Service Las Vegas NV
656 PM PST Thu Jan 28 2021 .SYNOPSIS...Heavy snow will continue in the eastern Sierra through the evening hours. Rain and mountain snow will spread across the Mojave Desert and southern Great Basin late tonight and into the afternoon on Friday. Drier conditions expected over the weekend with moderating temperatures. && .UPDATE... Plume of moisture that brought significant amounts of rain and snow to portions of California has started to pivot east this evening. So far, precipitation has remained west of the Sierra Crest, but over the next couple of hours snow will once again start increasing across the Eastern Sierra Slopes. This will lead to a few more inches of snow in places like Aspendell where they have already received around 40 inches of new snow. With the warmer air that has advected into the Owens Valley, snow levels are currently around 5000 feet. As the precipitation moves into the area, we don`t see those snow levels falling very much, at least initially. By the time temperatures drop to allow for snowfall in the Owens Valley most of the precipitation will have moved east. However, it is still possible that places like Bishop could see some snow accumulations up to an inch or two in the morning. Very little change with the timing of the precip as it moves through the CWA Friday. Latest HRRR showing rain moving into western San Bernardino County around midnight and then working east and arriving in Las Vegas just before sunrise with widespread light rain expected for the morning commute. Most areas below 5500 feet will see rain as this main band pushes through. The main band of precip looks to push east by late morning, but as the base of the trough moves overhead we could see additional showers develop with snow levels dropping to around 4000 feet in the afternoon. This could potentially bring some snow accumulations to Mountain Springs and Mountain Pass. We will also have to watch for the potential of thunderstorms Friday afternoon across far southern NV and Mohave County as strong dynamics associated with the low interacts with afternoon heating. Current forecast on track and no evening updates needed. && PREV DISCUSSION 115 PM PST Thu Jan 28 2021 .SHORT TERM...through Sunday night Latest satellite imagery continues to show the plume of moisture into central California. This plume will continue to become more north to south oriented during the course of the afternoon. Steady southerly winds continue to funnel up the Owens Valley with gusts generally in the 30-40 mph range. That has increased temperatures and snow levels to above 5000 feet. As the trough begins to push across Inyo County overnight snow levels will drop again but any snow accumulation in the Owens Valley is expected to be less than an inch. The heaviest snow in the eastern Sierra will begin to diminish toward midnight, but lighter snow will continue into Friday. The latest, 12Z runs of the HREF as well as the HRRR show the progression of the band of rain and snow showers pushing south and eastward overnight. Expect the leading edge to reach the Barstow area around midnight, Mountain Pass and the Spring Mountains between 2 and 4 am, and into the Las Vegas Valley by daybreak. Snow levels will initially be around 5500 feet and then fall to around 4500 feet during the morning. Mountain Pass is expected to initially start out as rain but transition over to snow with the potential to receive a quick couple of inches of accumulation. The winter weather advisories across southern Nevada remain in place. The latest HREFs have trended upward somewhat with the snow amounts in the Spring Mountains and the latest forecast reflects this. Elsewhere, the biggest change in the forecast is the issuance of a Winter Weather advisory for the higher terrain above 5500 feet in Mohave County from 5 am Friday through 5 pm where 3 to 6 inches can be expected. Snow levels will fall to around 4000 feet during the afternoon, but accumulations in the 4000 to 5500 foot elevation range should be no more than an inch or so. Lastly, the EMC HREF is indicating sufficient CAPE and instability to produce some shower activity behind the main precipitation band and underneath the cold core of the trough. This will also provide some isolated lightning strikes in far eastern San Bernardino and Clark Counties as well as across Mohave County on Friday afternoon. The trough axis will push to the east on Friday night with a shortwave ridge building into the area for the weekend. This will provide some drier conditions, although temperatures will remain at or slightly below the climate normals. .LONG TERM...Monday through Thursday The next trough of low pressure will begin to approach the area on Monday with southwest flow beginning to increase. Precipitation will begin to move into the eastern Sierra by Tuesday morning with the trough axis approaching the northern and central California coastline. The 00Z WPC Clusters are showing one scenario where about 20 percent of the ensemble is indicating a tap of moisture into southern California and southwestern Arizona. None of the members were from the GEFS, but the 12Z GFS does indicate that potential as their is a plume of 200-300 units noted. I suspect with the 12Z Clusters we will see an increase in the probabilities somewhat. At this point no significant changes were made to the forecast during this period. Widespread PoP chances are in the forecast area wide on Wednesday. As the trough exits on Thursday there is the potential for some stronger northerly winds, particularly down the Colorado River Valley. && .AVIATION...For McCarran...Ceilings will remain aoa 15 kft through about midnight. More uncertainty regarding the wind forecast. Wind speeds expected to remain below 10 kts, however some guidance suggests several hours of a southeast wind direction late this afternoon into early evening. If that does not materialize the direction looks to stay favorable today before shifting to the typical downvalley direction this evening. Period of light rain, lower ceilings and visibility making for MVFR conditions for the morning push Friday morning. Visibilities could lower 3SM in moderate rain with ceilings 2-3 kft between 13Z and 19Z Friday. Turbulence forecast below 18 kft along with mountains obscured. Conditions will improve Friday afternoon as the weather system moves east. For the rest of southern Nevada, northwest Arizona and southeast California...Tonight and Friday, a storm system will move east across the region bringing with it lower cigs/vsby and widespread rain and snow to the mountains. Snow could mix with rain for a period tonight at KBIH. Otherwise, MVFR conditions with ceiling 1-3 kft AGL and vsbys falling to 3SM in light to moderate rain. Turbulence for below 18 kft with mountains obscured. Conditions will improve from west to east throughout Friday as the system moves east. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Gorelow SHORT TERM...Czyzyk LONG TERM...Czyzyk AVIATION...Pierce For more forecast information...see us on our webpage: or follow us on Facebook and Twitter