Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/04/21

Area Forecast Discussion
National Weather Service La Crosse WI
602 PM CST Wed Feb 3 2021 .SHORT TERM...(Tonight through Friday) Issued at 310 PM CST Wed Feb 3 2021 All eyes on the WINTER STORM for late tonight-Thu night. A wide variety of impacts - potentially HIGH END impacts. Snow, wind with a brief wintry mix possible. FORCERS/FUEL: shortwave trough still on track to drive from western Canada to across the plains/upper mississippi river valley Thu. The trough is expected to strengthen/deepen as it does, thanks in part to a 300 mb jet streak riding through the base, enhancing the available lift. A closed upper level low with deepening sfc low are expected as the system moves through, gradually lifting into southeast Canada later Thu night. Strong pressure gradient will develop in response, and strong/gusty winds will result for the afternoon/night time hours of Thu. Good frontogenetic response along/ahead of the north-south running cold front with some indications for secondary banding post the front in the 600:700 mb layer, within the deformation region. Broad isentropic upglide on the 280:295 K push northward and across the area overnight tonight, strongest during the morning/early afternoon hours. An anomalously mild/moist airmass will fuel the system, with NAEFS PWS upwards of +2.5 and 850 mb temps around +1.5. GEFS and EC ensembles favor at least 1/2" of liquid, with a fair amounts of members north of 3/4". Canadian is rather dry and tossing that out for now. The storm has a lot going for it... PCPN TYPES/TIMING: with warm air a loft (850 mb temps via NAM/GFS/EC all from +1 to 4C) ahead of the front - evidenced in west-east running x-sections and bufkit soundings - full to partial melting is likely, roughly in a 1-3 hour window. This brings sleet, freezing and even rain (sfc temp dependent) into the picture. The models have been consistent with this. In addition, some models point to a loss of ice in the cloud layer, with freezing drizzle the likely result (although some hints of seeder-feeder process too). The higher wintry mix threat looks to be mostly confined to the overnight hours, roughly 06-12z. Snow should take over as the main ptype by early to mid morning, persisting into early evening and likely exiting northeast by 06z Fri. The bulk of the QPF should fall during the day Thu. SNOW: the speed of the system and the north-south orientation of the main snow band will be limiting factors with this storm, even with stronger dynamics and a impressive fetch of low level moisture. Low snow ratios will hurt amounts at the outset, but those should climb post front with colder air working in. However, by the time the DGZ deepens to more than 100 mb, the snow is over. All said, amounts looking a bit less than previously, mostly in the 2 to 4 inch range with higher still generally confined to the I-94 corridor northward. ICE: still see some threat for a light glaze early Thu morning from 2-4 hour window of mixed pcpn. If it would occur, there would be impacts to the morning commute. WIND/BLOWING & DRIFTING SNOW: wind will be cranking up Thu afternoon, staying strong and gusty through the night. Mix down in bufkit soundings via the GFS and NAM both suggest gusts in the low 30s mph with the RAP a tad less. A slight downward trend compared to previous soundings in the GFS and NAM, but still windy. EC ensembles have been steady in the low 30s too. Sustained winds in the lower 20s still expected in the usually windy areas of SE MN/NE IA. With lower snow ratios (wetter) snow at the outset, becoming a bit drier post front in colder air (higher snow ratios), questions abound in how much this snow will blow. Wet snow would be hard to lift, with mainly drifting concerns. Light snow and/or stronger winds will lift the snow to impact vsbys - and there comes the possible ground blizzard conditions. That would mostly hold in the open and unsheltered areas west of the Mississippi River. With a lot of variables in play and not clear, believe blowing and drifting WILL be a problem, but not sure it makes blizzard. We have to keep a very close eye on that though. HEADLINES: opted to go with Winter weather Advisories for the entire area. Contemplated some warnings - mostly for ground blizzard conditions across parts of SE MN and NE IA. At this time, confidence wasn`t high with the type and amount of snow expected, another with the winds. That said, a bit more snow and a tad higher winds and that threat increase. We will have to monitor closely... .LONG TERM...(Saturday through Wednesday) Issued at 310 PM CST Wed Feb 3 2021 It`s going to be a cold weekend, and latest GFS and EC are suggesting this cold will hold through the new work week. UGH. Exiting winter storm will ushering in cold, arctic air starting Friday, continuing into the start of the new work week. Latest model runs suggest another shortwave trough will pinwheel around upper level low anchored over southern Canada, sending another push of cold air southward across the region by mid week. 850 mb temps progged to drop into the low -30s from time to time while NAEFS 850 mb anomalies hover around -2 through the period. A lot of support from various ensemble members in both models that lows in sub -20 F will be reached. Will continue to side with the model blend for highs/lows through the period - but get ready for an extended period of cold winter temps. Might not see normal temps until the following weekend. In addition, winds will be a player as even relatively light winds will create wind chills from -20 to -35 F at times. Expect on and off Wind Chill Advisories for parts (or all) of the area starting Sat night into Thu. Cold wind chills more likely across the open areas of SE MN/NE IA where winds are more of a factor. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 602 PM CST Wed Feb 3 2021 A winter system looks to bring a wintry mix and snow with IFR to LIFR conditions to the TAF sites late tonight/early Thursday morning, with gusty winds and blowing snow possible Thursday afternoon. For this evening, south winds could gust to near 30 kts at KRST, with patchy blowing/drifting snow possible. In addition, strong winds just above the surface will lead to low-level wind shear at both TAF sites. Very tricky TAF forecast for the rest of the night into Thursday, with lowering ceilings and increasing precipitation chances ahead of a low pressure system developing to our west. Right now, the highest precipitation chances look to be Thursday morning, but will have to watch for light precipitation developing earlier than expected overnight as forcing increases, though there will be initial drier air to overcome. A wintry mix of rain/freezing rain/sleet is possible for a couple of hours at onset Thursday morning given warm air aloft and surface temperatures near freezing, but this should change over to snow quickly as the column cools. KLSE may be warm enough that this ends up being mainly light rain/snow at onset before changing over to snow, however. IFR to LIFR visibility reductions and IFR ceilings are expected with snow. The bulk of the snow tapers off by afternoon, but northwest winds will increase to 15 to 25 kts, with gusts of 30 to 35 kts, which could lead to blowing snow and visibility reductions, especially toward KRST. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Winter Weather Advisory from 3 AM Thursday to midnight CST Thursday night for WIZ017-029-032>034-041>044-053>055-061. MN...Winter Weather Advisory from 3 AM Thursday to midnight CST Thursday night for MNZ079-086>088-094>096. IA...Winter Weather Advisory from 3 AM Thursday to midnight CST Thursday night for IAZ008>011-018-019-029-030. && $$ SHORT TERM...Rieck LONG TERM....Rieck AVIATION...Lee
Area Forecast Discussion
National Weather Service Dodge City KS
455 PM CST Wed Feb 3 2021 ...Updated Aviation... .SHORT TERM...(This evening through Thursday) Issued at 1218 PM CST Wed Feb 3 2021 Short range models indicate an upper level shortwave trough dipping southeast across the Northern/Central Rockies this evening and farther southeast into the Western High Plains overnight, sending an attendant cold front through western Kansas into northern Oklahoma by daybreak Thursday morning. As the upper level system approaches, surface low pressure developing in eastern Colorado will deepen as it begins to push into western Kansas this evening, and onward into eastern Kansas by early Thursday morning as the cold front moves through southwest/central Kansas. Despite a lack of moisture as indicated by model soundings, light snow will be possible for a few hours Thursday morning across west central, central and possibly portions of southwest Kansas as H7 frontogenetic banding shifts southeast across the area in conjunction with the arrival of a strong +150kt upper level jet max nosing eastward into southwest Kansas. There is a general model consensus showing fairly weak QPF signals suggesting relatively minimal potential snowfall amounts, including anywhere from a dusting to maybe a few tenths or so. Colder air will spill into western Kansas late tonight dropping temperatures well into the 30s(F) by daybreak Thursday morning. A few mid/upper 20s(F) are likely farther north/northwest. Highs are only expected up into the 40s(F) Thursday. .LONG TERM...(Thursday night through Wednesday) Issued at 1252 PM CST Wed Feb 3 2021 Quieter conditions are likely Thursday night into Friday as a much drier air mass dominates across the Western High Plains. Another cold front is projected to push into western Kansas Saturday as a secondary upper level shortwave digs southeast out of the Northern Rockies into the Western High Plains. However, the bulk of the system and associated moisture is expected to track southeast out of Nebraska through eastern Kansas during the afternoon limiting any snow chances primarily to central Kansas. Colder, but more tranquil conditions return Sunday into early next week as a zonal flow sets up across the Western High Plains. High temperatures may rebound somewhat Friday as a westerly downslope flow sets up across the Western High Plains. Under decreasing cloud cover, expect afternoon highs pushing the upper 40s(F) to the lower/mid 50s(F). The next cold front is projected to surge southward through the Northern Plains Saturday and into northern Kansas Saturday night before stalling out. This is expected to drop temperatures below the seasonal average by the early part of next week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 455 PM CST Wed Feb 3 2021 VFR will continue this evening with broken cirrus and south winds of 10-15 kts. HRRR places a 995 mb surface cyclone near HYS around 05z. After 06z, the associated strong cold front will sweep through the airports during the 06-08z time range, with an abrupt shift to intense north winds. Gusts as high as 40 kts are expected during the 06-09z time range. After 09z, consensus of short term models indicates a period of post-frontal MVFR stratus for a few hours at all airports. A band of post-frontal light snow showers is also indicated, most aggressively by the HRRR, during the 09-12z Thu time frame. Included some fleeting visibility reductions in some of the TAFs, but any impacts from passing snow showers overnight should be limited. Will readdress this issue with the 06z TAF update. Expect N/NW winds to gradually decrease Thursday morning, with ceilings quickly returning to VFR. && .PRELIMINARY POINT TEMPS/POPS... DDC 33 47 22 52 / 10 20 0 0 GCK 30 46 20 50 / 10 30 0 0 EHA 33 49 22 51 / 10 20 0 0 LBL 35 48 19 51 / 10 20 0 0 HYS 30 42 21 48 / 20 30 0 0 P28 37 48 25 54 / 10 10 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JJohnson LONG TERM...JJohnson AVIATION...Turner
Area Forecast Discussion
National Weather Service Lincoln IL
800 PM CST Wed Feb 3 2021 .SYNOPSIS... Issued at 522 PM CST Wed Feb 3 2021 Rain will overspread central Illinois late tonight into Thursday, ahead of a strong cold front which will sweep across the Midwest. Some of this rain may initially be mixed with some light snow or freezing rain, but a more widespread change to snow will begin toward sunset before the precipitation ends in the evening. Significantly colder air will spread into the area Thursday night and Friday, but a more intense period of Arctic air will arrive for the weekend. && .UPDATE... Issued at 800 PM CST Wed Feb 3 2021 Higher clouds streaming in quickly this evening, with mid level clouds steadily dropping southeast through Iowa. Temperatures not really expected to drop off any more at this point, with southeast winds already 5-15 mph. Evening sounding from our office shows temperatures near 40F at 3,000 feet above the surface, and HRRR forecast soundings show this persisting into tomorrow morning. While a bit of freezing rain can`t be ruled out at the beginning of the event, currently think that temperatures will be warm enough that most areas will start off as rain. High-res models hint at an hour or so of possible dry weather late morning between the WAA precip and the cold front, but will not get that fancy in the grids and keep the PoP`s maximized during the afternoon hours. Updated zones/grids have been sent. && .SHORT TERM...(This evening through Thursday) ISSUED AT 522 PM CST Wed Feb 3 2021 Surface high pressure has shifted east this afternoon allowing the return of southerly flow. Temperatures will drop slightly after sunset but will actually rise through the night thanks to WAA and increasing cloud cover ahead of the next system. Speaking of which, this next system is currently sitting lee side of the Rockies in Colorado. Powered by a strong jet, the low will speeds into the region by Thursday morning bringing mixed precipitation, strong winds, and very cold air. Western IL will see the first chance of precipitation early Tuesday morning with coverage expanding eastward through the morning hours. Most of the CWA will see only rain tomorrow. However, northern and western counties will have better access to the colder air allowing snow to start mixing in with rain early in the afternoon. By the evening commute, rain transitions to snow for areas along and west of I-55. Rain will be a limiting factor on snowfall and have kept total new snow to less than an inch for the majority of our area. Our northernmost counties could see an inch or two depending on when the rain/snow switches to only snow. At this time, leaning towards lighter snow accumulations since surfaces should remain above freezing most of tomorrow and considering the speed of the system. The cold front will leave as quickly as it arrived, exiting the state before midnight. Winds will start to increase ahead of the front this evening but the strongest gusts will accompany the front Thursday. Expecting gusts up to 30-35 mph which will especially impact the evening commute, when more widespread snow is expected for the western half of the CWA. Blowing snow will be an issue in areas where snow is still on the ground, specifically for Knox, Stark, and Marshall counties. For this reason, a winter weather advisory has been issued. Cold arctic air will follow the front Thursday, dropping temps into the teens and low 20s. Wind chills, fueled by the continuing gusty winds, will drop to below freezing in northern IL. && .LONG TERM...(Thursday night through Wednesday) ISSUED AT 522 PM CST Wed Feb 3 2021 Dry and much colder conditions can be expected Friday behind Thursday`s cold front. As the low lifts off to the northeast, winds will taper off ending any lingering blowing snow. Expect highs ranging from near 20 along I-74 to mid 30s south of I-70. An arctic cold front will arrive Saturday, bringing temperatures plunging again along with a chance for light snow accumulations. Highs may be early in the day, especially north of I-72, with highs in the teens to low 20s, while areas south reaching mid 20s to low 30s, although uncertainty in timing of the arctic air could result in some significant uncertainty in temperatures. The cold air looks to peak by Sunday, with lows likely to be near zero, and only rising to single digits for highs many areas north of I-72. Current wind chill forecast is for a minimum of 15 to 25 below zero north of interstate-72, and 0 to 15 below zero south. The very cold air mass is likely to linger for several days, with typical lows near zero and highs teens to lower 20s into midweek. A series of disturbances propagating through a longwave upper trough over the area will bring frequent chances for light snow through midweek. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 522 PM CST Wed Feb 3 2021 Quiet weather in the short term, though LLWS will begin to impact the TAF sites after 06Z ahead of a strong cold front. Core of the low level jet will actually be moving through Thursday morning, around the same time that surface gusts pick up to 25-30 knots. Beginning around 12Z, light rain will begin moving in from the west, and ceilings and visibilities will steadily deteriorate. By midday, IFR/LIFR conditions will be prevailing as ceilings drop below 1,000 feet. The arrival of the front itself will bring an abrupt wind shift from south-southeast to the west, with rain beginning to change over to light snow. This is generally expected between the 21-24Z period. && .ILX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from noon Thursday to 6 AM CST Friday for ILZ027-028-030. && $$ UPDATE...Geelhart SYNOPSIS...Geelhart SHORT TERM...Roberson/Geelhart LONG TERM...37 AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1006 PM CST Wed Feb 3 2021 .UPDATE... 956 PM CST High pressure has moved to our east with decent southerly flow and weak warm air advection (WAA) to our west ahead of an approaching trough and 996 mb low pressure system presently centered over western Kansas. Sites are reporting gusts ahead of the front/low in the mid-20 mph, with occasional gusts in the lower 30 mph range, while gusts as high as 45 mph can be seen behind the front. A 140 kt jet max`s left exit region will approach very closely to our CWA late Thursday morning, providing good upper level divergence supporting the surface systems. Cloudy skies should keep low temperatures Thursday morning from becoming too cold, and overnight WAA will bring surface temperatures to above freezing in many locations, and forecast soundings show a fairly good warm nose around 900mb, creating potential rain to freezing rain with arrival of precipitation, which models initially indicated should occur around 12Z-14Z (6-8 AM). Once precip begins, the column cools quickly to below freezing, switching precip over to snow within a couple of hours of initial precipitation, sometime between 9 to 10 AM. Snowfall rates can be occasional high as some models pick up on fairly strong upper level lapse rates (8.5 C/km), and some indication of elevated CAPE around 40 J/kg by early afternoon (02Z RAP run). Greatest amounts are still expected in the northwestern counties, decreasing in amount as you move further south and east. There is some uncertainty in how much precip southern counties will get; some model precipitation amounts are a bit higher, indicating snow amounts may be greater than presently thought, but need to see if more model guidance starts trending in that direction. Front will move through sometime around 05/00Z, turning our winds northwesterly, and bring in cold air. 850 mb temperatures will plummet from +3 to almost -20 in 24 hours, with strong wind gusts up to 45 mph expected Thursday evening into Friday early morning. Cloud cover is expected to decrease somewhat Friday, especially in the southern counties in the wake of this system, but temperatures will struggle to climb into the mid-teens for most locations. BKL && .SHORT TERM... 420 PM CST Through Thursday night... Bottom Lines Up Front: The Winter Storm Watch has been converted to a Winter Storm Warning for Lee, Ogle, Winnebago, and Boone Counties, with a start time that`s been moved up slightly to 10 AM Thursday. While snowfall amounts have not materially increased in the warning (3-5" with isolated amounts to 6" possible), the combination of a period of rather heavy, convectively-driven rates coinciding with the afternoon/evening commute, rapidly increasing snow:liquid ratios and a likely period of fairly strong westerly winds gusting to 40 if not 45 mph by later Thursday afternoon and evening were concerning enough to warrant an impacts-based warning there. To the east of the warning, we`ve layered on a Winter Weather Advisory where slightly lower snowfall amounts (generally in the 2-5" range, although we`ll note a potential for overperformance given the impressive lapse rate plume with this system) and a slightly shorter window of stronger winds are expected to help mute impacts a bit more. Still, as it stands right now, guidance suggests that the Thursday afternoon/evening commute won`t be terribly pleasant, with a period of potentially heavy snowfall coinciding with the rush. Marginal surface temperatures near or even just above freezing may help blunt the threat for accumulation on the main thoroughfares (outside of heavier rates), but reduced visibilities, and the potential for sharply falling temperatures into the evening spells at least a non-zero potential for a flash freeze scenario where wet roadways remain. Think the threat for accumulating snowfall is more or less over by midnight Thursday night, but the threat for blowing snow will continue overnight and into Friday. Full technical discussion... Our powerhouse cold front is finally making an appearance in the surface observations, with 35 to 45 mph northwest wind gusts noted pushing across the Dakotas and into northwest Nebraska. This front will surge into the region through Thursday afternoon and evening, delivering sharply falling temperatures and a likely period of fairly strong wind gusts. The main focus here remains on the relatively brief window for precipitation, developing across our I-39 corridor locales towards mid-morning tomorrow, and spreading east by late-morning and early-afternoon. The parent shortwave trough axis will be gradually acquiring a neutral tilt as it approaches our longitude. Quite the shift in the thermal profiles (towards a colder note) over the last few days with an overall somewhat deeper system with a developing 990s mb surface low through the day. From a dynamics/kinematics perspective, this incoming system is definitely checking quite a few boxes. With strong system- preceding DCVA, plus robust upper divergence in the left exit region of a cyclonically-arcing 130+ kt jet streak, it`s no surprise to see layer Q-vector convergence maximized over our region in the roughly noon-7 pm timeframe. This forcing will arrive with the addition of another anomalously moist airmass, characterized by PWATs pushing 0.6 to 0.7". One of the somewhat concerning aspects (outside of the wind potential) is the presence of impressively steep lapse rates. Cross sections through the incoming baroclinic zone show a deeper-than-typical layer where theta-e lapse rates trend towards 0 or even locally negative for a time tomorrow afternoon. The NAM/NAMNEST which, admittedly have their issues with what look like some contamination in regional soundings, actually carve out pockets of MUCAPE in excess of 50 J/kg, and this is seen across the suite of afternoon guidance. Given the brief overlap of strongest ascent during this period, don`t think it`s overly outlandish to expect a brief window where thundersnow is a possibility. Ptypes at precipitation onset are a bit uncertain, with it possible that things start very briefly as rain or freezing rain. However, Bourgouin-based layer energies suggest snow will very quickly become the predominant p-type as dynamic cooling sends the entire atmospheric column below freezing. Thus, not too concerned about an icing threat, especially with air temperatures hovering near to just above freezing. The other potential fly in the ointment here is if true upright convection becomes as prevalent as some guidance suggests, latent heat release in the mid-levels could favor sleet at times before the column has time to more homogeneously cool through the evening. This signal isn`t high, however, with the current thinking that snow will be the most favored p-type Thursday afternoon and evening. With snow expected for a longer duration in northwest Illinois, amounts are overall a bit higher there, with 3-5 in the gridded forecast, but convective rates could easily support higher amounts. We`re a bit concerned that snow ratios may also be somewhat underplayed in recent guidance given the magnitude of forcing through such a deep layer. While these will undoubtedly start off low (6-8:1), think these may increase rapidly above 10:1 through Thursday afternoon, muted to some degree by a good deal of riming/aggregation. Finally, respectable isallobaric component post-FROPA with steepening low-level lapse rates suggests a window late Thursday afternoon and into the evening where wind gusts could approach 45 mph. It`s always tough trying to predict the magnitude of blowing snow, but for the above-mentioned reasons, thinking this will cause impacts--most notable across northwest Illinois. That said, blowing snow could realistically occur across the entire`s just difficult to say how the magnitude of impacts will play out at this time. The Winter Storm Watch was converted to a Warning for Lee, Ogle, Winnebago, and Boone counties for these reasons, as well as a desire to reduce the potential for muddling our forecast message by flipping from a Watch, to an Advisory, potentially back to a Warning if conditions end up deteriorating substantially. Finally, am leaving the door open for overperforming snow totals south of the current Advisory area (south of I-80) given the impressive lapse rate plume in place. Regional GEM certainly is playing this card, but given the somewhat marginal surface temperatures, it really will take these (conditional) rates to accumulate, so at this time just something we`ll need to keep an eye on. Forcing pushes east quickly, such that any precipitation of consequence is probably dwindling through Thursday evening and especially by midnight or so. Latest guidance suggests we may dry out just in time to limit a true flash freeze set-up, but temperatures will be plunging through the evening. Any lingering wet spots that aren`t dried up by the gusty winds could freeze quickly. Just another aspect of this multi-faceted system to continue to monitor. Carlaw && .LONG TERM... 255 PM CST Friday through Wednesday... A very active and very cold period of weather is appearing likely during the long term period. This will be all thanks to the development of strong high latitude blocking of high pressure in the mid and upper levels of the atmosphere associated with the negative phase of the AO/NAO. The net result of this evolving hemispheric pattern will be the southward displacement of a lobe of the tropospheric polar vortex into parts of south central Canada and possibly into the northern Great Lakes into next week. Not only does this look to drive an arctic airmass southward into the central CONUS, but it also looks to set up a period of active weather for the region. With this in mind, the main forecast challenges and concerns during this period revolve around both the temperature/wind chill magnitudes, and the chances and timing of several additional rounds of accumulating snowfall this weekend into next week. The coldest air mass of the season remains on track to arrive this weekend and continue next week. This cold air mass may support dangerously cold wind chills, approaching advisory level criteria (-20), both Saturday and Sunday nights. While the current forecast reflects this, there is some concern that a couple of weather disturbances moving across the area this weekend may produce enough cloud cover overhead these nights to limit the very cold temperature and wind chill magnitudes. For this reason, confidence in reaching wind chill advisory level criteria is somewhat low. A rather robust lower level baroclinic zone looks should set up over our area this weekend as the core of this arctic airmass begins to spill into the northern CONUS. This in combination with a developing active belt of westerlies overhead looks to set the stage for several periods of accumulating snowfall this weekend into at least early next week. The first disturbance of note for light to moderate snow accumulation potential has had a consistent signal among guidance (including ensemble) consensus of arriving Saturday afternoon and scooting out Saturday evening. Given the cold airmass in place this would be a dry and higher ratio type of snow, with a couple inches certainly possible. Additional rounds of snow look probable Sunday through early next week, and the potential exists to experience several more inches of snow accumulation during this period. Expect temperatures to remain quiet cold during the period, with highs only in the low to mid teens at best. KJB && .AVIATION... For the 00Z TAFs... 551 PM...Primary forecast concerns include... Period of moderate/heavy snow Thursday afternoon. Possible brief wintry mix before snow. Strong/gusty south/southeast winds Thursday. Strong/gusty westerly winds with blowing snow Thursday night. For the rest of tonight, prevailing winds will become light south/southeast and gradually increase in speeds by morning with gusts developing after sunrise with increasing mid level clouds. Precipitation will quickly spread across the area during the mid and late morning hours with a wintry mix possible as precip starts. Best confidence for a few hours of a mix is at rfd but by the time precip arrives at the Chicago terminals, intensity may be increasing to the point that it quickly becomes snow and just started precip as snow for the Chicago terminals. A short tempo may be needed for a brief wintry mix late Thursday morning as trends emerge. A period of moderate to heavy snow is expected at all the terminals Thursday afternoon. Vis is likely to drop into the 1/2sm range with some 1/4sm possible. The snow is expected to taper off by 00z and should end early Thursday evening. South/southeast winds will continue on Thursday with gusts into the mid 20kt range expected. Wind speeds/gusts may diminish some during the heaviest snowfall and will slowly turn southwest by late afternoon. The snow will likely be wet when it begins but should gradually become drier by the time it ends, allowing for blowing snow to develop. Winds will shift westerly early Thursday evening with gusts into the mid 30kt range, possibly higher at times. This should allow blowing snow to continue into Thursday night. Wind speeds and gusts will only slowly diminish early Friday morning. cms && .MARINE... 430 PM CST The Gale Watch has been converted to a Gale Warning for Thursday evening into Friday afternoon, with a run-up Small Craft Advisory going into effect later tonight. There may be a brief window Thursday evening as winds shift to the west where occasional wind gusts may approach 40-45 kts, but in general, winds are expected to remain into the 35 kt range within the duration of the Gale Warning. Freezing spray becomes more of a risk through Thursday night into Friday, away from any ice cover. Carlaw && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Winter Storm Warning...ILZ003-ILZ004-ILZ008-ILZ010...9 AM Thursday to noon Friday. Winter Weather Advisory...ILZ005-ILZ006-ILZ011-ILZ012-ILZ013- ILZ019-ILZ020-ILZ021-ILZ103-ILZ104-ILZ105-ILZ106-ILZ107- ILZ108...11 AM Thursday to noon Friday. IN...Winter Weather Advisory...INZ001-INZ002...11 AM Thursday to noon Friday. LM...Gale Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...6 PM Thursday to 3 PM Friday. Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...3 AM Thursday to 6 PM Thursday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion...UPDATED
National Weather Service Omaha/Valley NE
915 PM CST Wed Feb 3 2021 ...Updated to start Winter Weather Advisory a few hours earlier in northeast NE... .UPDATE... Issued at 915 PM CST Wed Feb 3 2021 Increased precipitation chances a bit sooner across northeast NE and started the advisory sooner, based on recent HRRR and RAP13 model output. Also bumped up QPF slightly, mainly northern 1/2 of the forecast area, which increased snow amounts slightly. Added a bit more blowing snow to forecast for late tonight and Thursday morning. Other changes to temperatures and winds overnight were minor. && .DISCUSSION... Issued at 245 PM CST Wed Feb 3 2021 ...Brief Period of Blizzard-Like Conditions and Potential Flash Freeze Early Thursday Morning... Fog was able to dissipate more quickly this morning, given the ample sunshine. Southerly low level flow strengthened ahead of an approaching midlevel trough, pulling warmer temperatures into the region. Afternoon temperatures were able to reach into the upper 30s and 40s by 2 PM, despite the deep, cold, reflective snowpack. 50s were even realized near the KS border. Hopefully you were able to get out and enjoy the weather today, because this will likely be our last above normal day temperature-wise for a while. A significant change in our relatively mild start to February will arrive tonight as a strong cold front associated with the previously mentioned trough blasts through the region. Initially, light rain will be possible ahead of the front. Temperatures in the mid to upper 30s around midnight will quickly drop into the 20s Thursday morning as the front moves in. This could lead to flash freezing of any rainfall or melted snow on the relatively warm ground. Strong northwest winds will accompany the front as well, sustained 15 to 20 mph with gusts up to 30-45 mph possible. Strong winds and a quick shot of snow, could lead to a brief period of blizzard-like conditions early Thursday morning. Thankfully, precipitation looks to move through fairly quickly, exiting the area before noon, and likely precluding the need for a Blizzard Warning. However, even without a true blizzard, that`s not to say the morning commute won`t be messy. In addition to icy patches, blowing snow is expected to continue through the morning hours, and into the afternoon. Winds will eventually diminish around 6 PM. When all is said and done, snowfall totals look to be around 1-2" for most of the forecast area, though it will be tough to measure given the wind. Quiet weather returns for Friday, with high temperatures only in the 20s and lower 30s. A large upper trough establishes itself across the nation as we head into the weekend, with a handful of precipitation producing perturbations rippling through the region. Our next chance for snow and first reinforcing shot of cold air arrives Saturday morning. High temperatures will only make it into the teens across most of eastern Nebraska and southwest Iowa. Temperatures continue to fall Saturday night/Sunday morning with lows in the single digits above and below 0, although it will feel more like -10 to -15 in northeast Nebraska and western Iowa. Yet another chance for snow will come Sunday morning, as temperatures struggle to make it out of the single digits and low teens. In fact, we have several bitterly cold days ahead of us. Temperatures will continue to struggle into the single digits and lower teens, with minimum apparent temperatures dropping into the negative teens to -20 each day through the middle of next week, at least. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 535 PM CST Wed Feb 3 2021 There will be some low level wind shear at KOMA this evening, possibly around KLNK as well. Expect deteriorating conditions later tonight, which will happen rapidly when then do change. Ceilings will drop to MVFR with a brief period of a rain/snow mix, then look for IFR conditions for several hours with visibilities below 1 mile in snow. Winds behind the cold front may gust to 30-35 knots or more, which could cause some blowing snow. Expect that ceilings should start to improve back to VFR at KOFK by around 12-13Z, 15-16Z at KOMA and KLNK. There is uncertainty as to how much blowing snow there will be once the falling snow ends. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Winter Weather Advisory from 2 AM to noon CST Thursday for NEZ034-044-045-051>053-065>068-078-090-091. Winter Weather Advisory until 9 AM CST Thursday for NEZ015-018- 030>033-042-043-050. Winter Weather Advisory until 9 AM CST Thursday for NEZ011-012- 016-017. IA...Winter Weather Advisory from 2 AM to noon CST Thursday for IAZ043-055-056-069-079-080-090-091. && $$ UPDATE...Miller DISCUSSION...KG AVIATION...Miller
Area Forecast Discussion
National Weather Service San Diego CA
152 PM PST Wed Feb 3 2021 .SYNOPSIS... A low pressure system moving southeastward through the Great Basin today will bring cooling, coastal low clouds and patchy fog, along with gusty west winds for the mountains and deserts through this evening. The flow will turn offshore on Thursday with warming west of the mountains, cooling in the deserts, and gusty northeast winds along and below the coastal slopes of the mountains. Friday and Saturday will warm with northeast winds weakening and becoming more localized. For Sunday through Tuesday, there will be a return of onshore flow spreading slow cooling inland. There will also be periods of high clouds with night and morning coastal low clouds and fog. Dry weather will prevail into next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... -Forecast Highlights- * Dry weather pattern will prevail into next week * Temperatures will be seasonable, warmest this weekend An upper shortwave will move southeast over the Rockies tonight. This is bringing gusty west winds to our desert mountain slopes and parts of the deserts, which will last through the evening hours before dying off overnight while winds switch to offshore out of the northeast. Winds will increase below especially the Cajon Pass late tonight, peaking Thursday morning, before subsiding. Peak winds will mostly be 30-40 mph through Thursday in the windy corridors, locally to 50 mph at the wind prone locales. Low cloudiness and patchy fog will continue near the coast before moving offshore late tonight. HRRR keeps visibility mostly above 3 miles, so if there is any dense fog tonight, thinking it will be patchy. Sunshine will prevail everywhere tomorrow. An upper level ridge will build over California and the western U.S. on Friday and through the weekend. This will lead to tranquil, dry and warmer weather conditions this weekend. Offshore winds will prevail and could be gusty below passes, especially the Cajon Pass, but winds right now look insignificant. The ridge de-amplifies some next week, but the global models and their ensembles favor a dry weather pattern prevailing through next week as the storm track remains off to the north. Temperatures will cool a bit, but will be near seasonal norms, mild days but chilly nights. && .AVIATION... 032100Z...Low clouds continue to stick to the beaches and a few miles inland. Bases are ranging from 300-800 ft MSL, locally up to around 2000 ft MSL. Local vis restrictions of 3-5SM BR in areas of low clouds. Cigs will spread into portions of the valleys this evening. Low clouds should clear by 16Z Thu. Westerly surface winds 15-25 knots gusts 30-35 knots over the mountains and desert slopes after 22Z. Winds will transition to north/northeast over the mountains, and into the foothills after 11Z Thu. Peak gusts of 35 kt. Areas of LLWS and mod up/down drafts possible over and west of the mountains. && .MARINE... Wind gusts of 20-25 kt from the northwest will increase through early Thursday over the outer coastal waters. These winds could create hazardous boating conditions, and a Small Craft Advisory has been issued. No hazardous marine conditions are expected Thursday through the weekend. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory until 3 AM PST Thursday for Waters from San Mateo point to the Mexican Border Extending 30 to 60 nm out including San Clemente Island. && $$ PUBLIC...Gregoria AVIATION/MARINE...CO