Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/30/22

Area Forecast Discussion
National Weather Service Gaylord MI
959 PM EST Sat Jan 29 2022 .UPDATE... Issued at 959 PM EST Sat Jan 29 2022 Low pressure center has reached Northern Wisconsin late this evening. Area of widespread light snow continues to develop ahead of this system across much of Northern Michigan. Meanwhile... persistent SW flow lake snow band remains offshore between Beaver Island and our far Northern Lake Michigan shoreline from the Straits thru Grand Traverse Bay. Some higher reflectivities are beginning to develop further south along our Lake Michigan shoreline around Leelanau and Benzie counties...coincidentally where Winter Wx Advisories are in effect. Expect these two counties will see 2 to 4 inches of new snow overnight with the expectation that the SW flow lake snow band will push onshore as low level flow veers to the W/SW later tonight. Will certainly maintain this headline for these counties thru the overnight hours. Rest of our CWA should see an inch or two of new snow from the clipper system. Temps will generally hold in the teens across Northern Lower Michigan thru the night...with temps dropping into the single digits above zero across Eastern Upper Michigan. && .NEAR TERM...(Through Tonight) Issued at 243 PM EST Sat Jan 29 2022 ...Lake enhanced snow for nw lower MI tonight... High Impact Weather Potential...Moderate. Accumulating snow in nw lower MI tonight. 1010mb clipper low pressure is over n central MN. The low will continue se-ward, reaching sw lower MI by daybreak Sunday. A healthy sw-flow lake effect snow band has been marauding for much of the day between Beaver Isl and the mainland of nw lower MI. Ice cover over far northern Lake MI is contributing to minimal penetration of this band into eastern upper MI. Not so visible on radar, but snow showers are also developing into sw sections, with 1-3SM vsbys presently at MBL and Frankfort. This is occurring just as synoptic-scale moisture/ascent is increasing in advance of the clipper. Pure synoptic precip with this system would be anemic, with QPF well under a tenth of an inch, even in favored places left of the surface low track. The parent shortwave is weak, and broad-scale moisture availability is poor in this persistently cold airmass. 850mb warm advection is respectable (and warm advection provides much of our lift), but 850mb temps warming into the lower minus teens still leaves enough instability for lake enhancement in persistent sw flow. Vigorous lake effect earlier today lends a little extra concern. Overnight, 1000-850mb winds veer from sw to n, as the clipper approaches. That will push any stronger offshore bands onshore, just before the event winds down in the morning. Hi-res guidance has been gradually increasing output QPF in nw lower MI tonight. The ever-rambunctious HRRR has localized areas of QPF >0.50" in parts of western Leelanau and Benzie Cos. That seems overdone, but is at least well-placed. Snow-liquid ratios won`t be as high as we`ve seen in some recent events; the DGZ is placed somewhat above the max upward motion (which is in the unstable layer closer to ground/lake level). That should keep SLRs in the high teens, perhaps near 20. Synoptic winds will be light, and blowing/drifting snow not a concern. Total forecast snow accums have been boosted to 2-5" in Benzie/ Leelanau Cos, with the highest amounts within about 10SM of the main body of Lake MI. An advisory has been posted for those 2 counties tonight. Manistee, Antrim, and Charlevoix Cos are the next counties of concern, if the event ends up being a bit more vigorous. Snowfall amounts fall off east of US-131, and those areas (and eastern upper MI) seeing an inch or less. Min temps will be mild tonight thanks to cloud cover, single digits above zero in eastern upper MI, and ranging thru the teens in northern lower. && .SHORT TERM...(Sunday through Tuesday) Issued at 243 PM EST Sat Jan 29 2022 High Impact Weather Potential: Messy precipitation issues possible Tuesday... Pattern Synopsis/Forecast: Negatively tilted trough axis associated with the current east coast storm is off to our east now...associated with a beautiful and stereotypical comma-head-type response on water vapor satellite imagery. A brief bit of ridging aloft has moved overhead (for the Great Lakes) this morning...leading to some breaks in the clouds out there...though some flurries and more intense snow showers do persist. This ridging is the result of another niblet of energy diving through the flow into the Upper Midwest through the last several hours or so...with a surface reflection over southern Manitoba/northern North Dakota this morning, positioned nicely in an inflection point in the baroclinic zone aloft...and with some mid- level moisture ahead of it, approaching northern Michigan attm. Do note a weak surface low developing just north of Lake Superior with an associated wavy surface boundary that extends back to the Manitoba low. Cold front extends back to the northwest from the latter low...and warm front (for a change) extends primarily southward through the Plains, along the cusp of some +0C air out there...ahead of longwave ridging, which continues to persist and spread eastward across the western US, though do note some shortwave troughing still trying to move through it...particularly a southern stream trough approaching the coast of southern California. Moving forward in time...will look for the niblet to our northwest to dive through the region tonight...with additional subtle waves in the upper level flow sliding through the Midwest Sunday into Sunday low off southern California today progresses across the desert southwest in the next 24-48 hours, cutting through the base of the ridge aloft. By Monday...will look for a complex flow pattern across the CONUS...with split flow in play, given that southern stream trough over the Gulf Coast. Northern Michigan will be under the influence of ridging we sit between departing troughing from the weekend...and encroaching northern stream shortwave trough (currently located in the Gulf of Alaska as of this morning) that will have cut the top off the western ridge...and will be propelled southeastward into the northern Plains by the core of cold air aloft dropping back into north central Canada after retrograding a tad over the weekend. Will look for that shortwave niblet in the northern Plains to become negatively tilted as it zips through the flow Monday night into Tuesday...with cold air flooding southward into the northern Plains behind it...setting up a deeply amplified trough aloft and resultant southwest-northeast oriented baroclinic zone across the center of the country going into Tuesday night...potentially into the Ohio Valley. This will have ramifications for the pattern, as well as for our weather...going into the latter half of the week. Primary Forecast Concerns: Winds Monday night into Tuesday...lingering snow Sunday...precip issues for the remainder of the period... Winds Sunday should be generally northerly behind the departing system, and remain relatively light through the remainder of the day and night...becoming west and eventually southerly with time through the response to the developing upstream system. Winds will strengthen with time...particularly going into Monday night and pressure gradient will tighten up ahead of the approaching response to trough aloft becoming somewhat negatively tilted as it passes by to our northwest. Would not be out of the question to see winds in the realm of 10-15+kts Tuesday, likely stronger over the lakes...noting 1000mb geostrophic winds approaching or exceeding 50kts (typically a good proxy for the tightness of the surface pressure gradient to use to estimate surface winds...1/3 the value would be over-land wind values, and 1/2 the value for over-lake values). Low itself should remain to our northwest...which should keep us in a position for warm advection through basically the remainder of the short term. Warm advection concerns may help mitigate some of the stronger winds from mixing down from aloft it will create a more stable atmosphere that is generally unfavorable for transporting those stronger winds downward from aloft...though some mixing may yet occur. Winds not too far off the deck look to run around 50+kts, depending on any marine influences (which may occur on the Lake Huron side this time, given southeasterly flow) and any other forms of mixing during the could be a little on the gusty side, for sure. Something to keep an eye on going forward. Additionally...looks as though a surface trough (potentially a cold front) may attempt to move through from west to east Tuesday afternoon/evening...which attm appears to be associated with a tighter isallobaric gradient...favorable for a period of stronger gusts along this front...actually, in the warm advection under surface pressure falls...though some of the surface pressure rises behind the front should result in a tighter isallobaric gradient as well...which could become a concern for some areas going into Tuesday evening/night. Sunday morning...lingering snow should be winding better moisture departs southeastward through the day with the trough. Subsidence aloft will be on the increase as heights rise behind the shortwave...though there are some signals for some low-level convergence in the vicinity of a lingering boundary across northeast lower behind the initial surface low, which should (in theory) help to squash most activity (for the most part...would not be entirely surprised to see some rogue flurries still hold on in some areas, though). Additionally...overlake instability lingers, with 925mb temps around -10C still sufficient over Lake Michigan; a little colder over Lake Superior suggests a slightly better chance of lingering lake effect across the northern UP, though both areas should remain in the presence of some boundary layer moisture through the day. With some additional mid-level moisture sinking southward Sunday night...may have to watch out for some snow showers/flurries to make it to the surface...given southerly flow over Lake Michigan again, in the presence of some low-level convergence, may be favorable for some lake enhancement/seeder- feeder action...though signals are not incredibly strong attm. Monday...that mid-level/warm advection moisture/meager precip along the thermal gradient aloft will be departing warm advection continues across the Plains and into our area through the day Monday, noting wind profiles beginning to veer with height early in the day. Overlake instability should wane through the warmer air advects in aloft...along with some subsidence aloft beneath ridge ahead of the developing system to our west...suggesting lingering lake effect will wane as the environment becomes less favorable. As we lose moisture aloft...and with the warm advection through the day...if any boundary layer moisture lingers...may have to keep an eye out for some "surprise" freezing drizzle concerns, as we could become too warm in the saturated layer for ice nucleation...particularly across eastern Upper, where boundary layer moisture lingers through much of the day. May have to watch for another round of some meager mid-level moisture approaching for late Monday night into early Tuesday morning...though it looks to be in the presence of some slightly better forcing aloft ahead of the shortwave (best forcing attm looks to remain to our north, closer to the shortwave itself). Things become more tricky Tuesday. From a broad standpoint of precipitation development...will look for some decent upper level forcing in advance of that negatively tilted niblet passing by to our northwest...with signals for mass divergence aloft continuing into the latter portion of the day and the the initial shortwave lifts out...but jet max aloft moves just to our northwest...placing Michigan in the favored right rear quadrant/right entrance region of the jet. Southwest flow/warm advection off the Gulf over the previous day should bring a moist airmass into the area...potentially somewhat anomalous (pwats up into the half inch range)...with surface dewpoints perhaps approaching freezing (suggestive of snowmelt potential...not to mention the potential of liquid precipitation). At note potential for temps aloft to rise above freezing Tuesday...and will therefore have to keep an eye on the surface temperature forecast in the coming it will play a large role in precipitation type issues going forward. All that being said...there are some signals at least part of the area may get in on a dry slot with this system...with the bulk of the precipitation remaining to our south where mid-level moisture appears to be maximized...(though some seems to hold on across the UP as well) will have to keep a close eye on this going it looks like it could be quite a mess. .LONG TERM...(Tuesday night through Saturday) Issued at 243 PM EST Sat Jan 29 2022 High Impact Weather Potential: Watching midweek system for next week...with potential for lake effect behind it... Pattern Synopsis/Forecast: By Wednesday...will look for that aforementioned baroclinic zone to be somewhere across the Midwest/Ohio Valley as a steep but positively tilted trough axis extends from a sub-500dm 500mb low in the Hudson Bay region...southwestward into the Desert Southwest. As colder air advects southward into the region...will look for the upper level jet over the baroclinic zone to intensify in response...and surface pressure falls will also result along this boundary. Guidance is still somewhat unclear on how this evolves...and timing/track seems to be shifting around some as well...but looks like we should remain active through the remainder of the week. Mid-late week system for Wednesday/Thursday...and perhaps now into Friday...? will be the one to there are signals for some anomalously moist air to flood northward along the boundary, given a good tap of Gulf moisture for a change, noting the deep troughing extending into the southwestern US. Exact position, therefore, of the baroclinic zone will need to be watched closely in the coming model it will play a major part in the track of the surface low that develops...among other concerns, including the extent of cold air that is able to break into our region again...and resultant lake effect related to the cold air returning. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 600 PM EST Sat Jan 29 2022 A clipper system currently centered over Northern Minnesota will slowly drop SE thru Wisconsin tonight...reaching the southern tip of Lake Michigan by early Sunday morning. The low will continue to slide SE thru Indiana Sunday morning...reaching the Ohio Valley Sunday afternoon. Light synoptic snow will continue to gradually develop this evening along the eastern side of this system. Sufficiently cold air will provide some SW flow lake enhancement for some locations along the shoreline counties of Northern Lake Michigan. Mainly low VFR/MVFR conditions are expected for the next 24 hours...periodically dropping to IFR within some of the heavier snow showers across far NW Lower Michigan tonight into Sunday morning. Surface winds will remain from the S/SW under 10 kts tonight into Sunday morning...and will then shift to the N/NW on Sunday as the low center passes south of Michigan. && .MARINE... Issued at 343 PM EST Sat Jan 29 2022 A clipper passes to our south early Sunday. Ongoing sw to s winds will veer northerly overnight and Sunday, while remaining on the light side. Stronger southerly winds will develop on Monday (especially on Lake MI), which looks like our next chance for advisory and/or gale-level winds. && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY until 7 AM EST Sunday for MIZ020-025. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...MR NEAR TERM...JZ SHORT TERM...FEF LONG TERM...FEF AVIATION...MR MARINE...JZ
Area Forecast Discussion
National Weather Service La Crosse WI
528 PM CST Sat Jan 29 2022 .SHORT TERM...(Rest of the weekend) Issued at 217 PM CST Sat Jan 29 2022 A mix of sun and mid to high clouds this afternoon with warm air advection underway ahead of a surface low positioned over northern Minnesota. Temperatures will continue to climb through the 20s with a southerly breeze in place. BCK and ONA have even managed to crack 30 degrees at this hour. That surface low and accompanying cold front will drop southeast through the area heading into this evening. Not really impact aside from increasing northwesterly winds. Cold air advection will support some momentum transfer after dark mainly in open areas west of the Mississippi River, where gusts of 20 to 30 mph will be possible for several hours overnight. Rather low confidence in tonight`s low temp forecast given uncertainty about extent of clouds as well as the decent CAA and low level mixing. Not surprising, there`s very wide spread in tonight`s minT guidance. For now have raised minT forecast closer to 50th percentile, which seems reasonable given more clouds/mixing tonight. The pressure gradient quickly relaxes Sunday morning as a surface ridge builds overhead. Maybe a smidge cooler than today, but otherwise a very similar day. A weak mid-level wave will drop through Sunday afternoon-evening, accompanied by a push of slightly greater atmospheric moisture. Depth of column saturation is still uncertain; some forecast soundings show a bit dryness in the low levels, while RAP fully saturates briefly. Regardless, forcing and moisture look marginal, so have just added chance of flurries from late afternoon-evening. .LONG TERM...(Monday through Saturday) Issued at 217 PM CST Sat Jan 29 2022 Rising 500mb heights on Monday will translate into a warmer day across the region with some areas potentially jumping briefly above freezing. A decent shortwave and moisture transport will cross the region late Monday night into Tuesday with the surface low scooting by just north of the Canadian border. QG forcing will be most robust near the surface low, so for our area it only looks like meager support for light snow north of I-94. That said, NBM continues to keep a dry forecast for our area. Tuesday`s temperatures will begin to drop in the afternoon behind the strong cold front. Attention then turns to another blast of arctic air for the second half of the week, along with a midweek system that is largely poised to stay south of our area. 850mb temps will again plunge to the teens to 20 below zero Wednesday through Friday. Expecting low temps to again tumble below zero for most with Thursday night looking to be coldest. Additional wind chill advisories certainly seem plausible for parts of the area through the latter half of the week. Beyond that, looks like some moderation into next weekend. A strong baroclinic zone will set up from the Central/Southern Plains into the eastern Great Lakes by midweek. A pronounced shortwave trough ejecting from the Desert Southwest will interact with this setup, with greatest resultant impacts looking to largely stay well south of the forecast area. That will be thanks in large part to a strong, Canadian surface high building in from the Dakotas and dry northerly flow. There`s been a definite southward shift among GEFS/EPS ensembles within the last 24 hours. Vast majority of EPS members now keep nearly all of our area dry, except for our far southeast (i.e. Grant County). GEFS has a greater number of members still bringing snow a bit further north into our area, but they`re in the minority and largely confined to our far south. Still a number of unknowns, but for our area, confidence is slowly growing toward seeing only minimal impacts from this system. Our far southeast has the biggest question mark, though any potential snow grazing the area look to be on the light side. Nevertheless, there are still some outlier ensemble members suggesting several inches from DBQ to PVB southward. Will continue to closely monitor storm evolution and trends. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 556 PM CST Sat Jan 29 2022 A surface low currently in MN will bring clouds into the area tonight, lowering ceilings from VFR to MVFR conditions first at KRST then at KLSE. Ceilings will continue to lower into the morning, with IFR conditions possible at both TAF sites. Otherwise, southerly winds will become northwesterly, with gusts up to 23 kts possible at KRST for a couple hours overnight. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Kurz LONG TERM...Kurz AVIATION...Dahl
Area Forecast Discussion
National Weather Service Boston/Norton MA
658 PM EST Sat Jan 29 2022 .SYNOPSIS... A powerful winter storm will exit the region as it lifts northeastward into Nova Scotia tonight. Minor coastal flooding will impact much of eastern Massachusetts this evening. Dangerously cold wind chills are anticipated for parts of the region. This is due to the combination of gusty winds and cold temperatures. Drier weather returns with below normal temperatures Sunday before a warm up next week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 645 PM Update... No major changes in the latest update. Main concern is the band of heavier snowfall over central MA into eastern CT/western RI. Expect this band to become more diffuse in the 1-3 hrs as colder drier air advects in from the northwest and the 700 hPa closed low lifts into the Gulf of Maine. Once this wraps up think there will still be some light snow until late tonight, but not anticipating much more in the way of accumulation. Thinking 1-3 inches additionally at the most with the highest totals on the Cape. Rest of forecast on track. Highlights... * Snow coming to an end as the winter storm lifts toward Nova Scotia. * Blowing snow remains an issue overnight as winds remain gusty. Have a very cold airmass moving in behind the system and this in combination with gusty winds will bring dangerously cold wind chills to parts of the region. Closed off 500 hPa low just over/east of southern New England will lift into Nova Scotia by late tonight.The deep cyclone associated with this feature will lift into Nova Scotia late tonight. Behind this system high pressure nudges in from Mid Atlantic/Carolinas. Have kept all Winter Weather headlines including the Blizzard Warnings up as it is still taking a bit for winds to come down and snowfall to taper off. Actually may be able to gradually take down these headlines across portions of the interior as the snow tapers off, but for the most part ending times look good. The other issue we run into tonight is with the fluffy snow and strong winds will have blowing snow reducing visibilities and going over cleared roadways. This could still make travel hazardous, so folks should probably still stay off the roads to allow crews to clear things. Still watching this frontogenetical band over eastern portions of the CWA to lift northeastward. Currently have it pegged just NW of the 850-700 hPa Fgen on SPC Mesoanalysis. The RAP has had a pretty good handle on this for most of the day and expect this to move northeastward. Thinking this ends by roughly 02Z. Still may have some light snow until late tonight until the low moves into Nova Scotia. Anticipate that there could be an additional 1-3 inches of snowfall with the highest amounts over Cape Cod as it will take the longest for snow to end here. Should be over after 06Z. As previously mentioned the main risk will still be blowing snow overnight as gusts will be 25-40 kts until 06Z. Gusts diminish to 10-30 kts with the highest values across the eastern Cape. Will see northwesterly flow advect in -15 to -20 degree air at 925 hPa. Have nudged down low temps into the single digits above zero for most of the area except the Cape/Islands where it is in the low to mid teens. Given the strong winds coupled with the cold temps expecting dangerously cold wind chills down to roughly -15 to -20 degrees Fahrenheit. Have hoisted a Wind Chill Advisory for the eastern slopes of the Berkshires and Worcester county. Not out of the question that portions of CT need a headline in future updates. Coastal flooding... See coastal flooding section for discussion. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Highlights... * Dry and quiet weather with below normal temperatures. Did not pay too much attention to this period given the winter storm moving through the region. Ridge axis builds into the eastern Great Lakes for Sunday before a shortwave lifts through Sunday night into early Monday. High pressure nudges into the region just south of us for Sunday and into Sunday night. No major concerns during this period other than breezy conditions coming to an end Sunday morning. High temps around 10 degrees cooler than normal for this time of year with readings in the low to mid 20s. Low temps Sunday night into Monday generally in the single digits, but not anticipating wind chill issues given the lack of winds. There will be a bit of cloudiness Sunday night. && .LONG TERM /MONDAY THROUGH SATURDAY/... 5 AM update... Highlights... * Quiet and increasingly mild weather to follow through much of the week. * Rain returns Thursday into Friday Details... Sunday and Monday... A trough east / ridge west pattern continues late weekend and early in the week while a ridge of high pressure moves in at the surface. Initial NW mid level flow will bring 850 mb temps down near -15 C on Sunday making for a cold day with highs only in the low to mid 20s; fresh snow cover, though, might keep highs a few degrees lower than that. This, together with breezy winds thanks to the lingering tight pressure gradient means it will feel more like the single digits and low teens. Wind gusts to 25 to 35 mph over the water and the cold temperatures will also lead to freezing spray issues. A Freezing Spray Advisory is in effect Sunday morning. By Monday that steering flow becomes more westerly advecting marginally warmer and more moist air into southern New England. Skies will be clear on Sunday with a mix of clouds and sun on Monday thanks to that increase in moisture. Tuesday through Friday... High pressure moves overhead on Tuesday with an mid level ridge axis and warming temperatures before our next chance of wet weather on Wednesday. This as a low passes to our north over the Great Lakes and northern New England pulling a warm front north across the region early Wednesday. This brings much milder temperatures with it, in the mid 40s Wednesday and near 50 Thursday, along with scattered rain chances on Wednesday. The cold front hangs up to our west, keeping the region beneath moist southwest flow through at least Thursday. PWATs surge over one inch on Thursday ahead of the cold front and incoming mid level trough. Forcing from the trough, cold front, and right rear quadrant of a 150 kt upper jet will work together with all that moisture to bring a soaking rain around Thursday or early Friday. Too soon for details like timing, whether it turns to snow on the back side, etc but this could be a decent slug of rain. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight...High confidence in trends, moderate in exact timing. Moderate snowfall coming to an end with lighter snowfall until roughly 01-04Z for most, but 06-09Z for the Cape. Slowly improving to MVFR and eventually VFR ceilings by late tonight. However, given the fluffy snow and gusty winds will have considerable blowing and drifting snow across the region late tonight. Thinking once the gusts get below 20 kts should see this risk come to an end. Thinking visibilities will be generally in the MVFR range, but may have some spotty IFR in any higher gusts. Sunday...High confidence. VFR with clear skies. Breezy during the morning with W/WNW winds and gusts of 15-20 kts. Not much of the way of gusts during the afternoon. Sunday night...High confidence. VFR with increasing mid to high clouds. Light SW/S winds. KBOS Terminal...Conditions gradually improving to MVFR/VFR with blowing snow until roughly 06-08Z. KBDL Terminal...Conditions improving to VFR. Could have some visibility reductions due to blowing snow until roughly 03-06Z. Outlook /Monday through Thursday/... Monday through Tuesday: VFR. Tuesday Night: Mainly VFR, with local IFR possible. Wednesday: VFR. Slight chance RA. Wednesday Night: Mainly VFR, with local IFR possible. RA likely, chance SN. Thursday: MVFR. Breezy. RA. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight...High confidence. Powerful Nor`easter will lift toward and into Nova Scotia. NW storm-force gusts should continue until roughly 9 PM to midnight, then become around gale force (35-40 kt) for the overnight across the NE waters. Seas will tend to decrease though some initial 20-25 footers still possible thru midnight on the eastern offshore waters. By daybreak, expect seas 6-10 ft on the southern waters, and 9-12 ft with increasing period. Risk for freezing spray will continue, with improving visibility as snow tapers off/shifts NE late tonight. Sunday and Sunday night...High confidence. Freezing spray continues through Sunday morning, but should become lighter by the afternoon as the gusty W winds lessen. Seas of 7-12 feet during the morning diminishing to 4-7 feet by late Sunday afternoon. Seas fall to 1-4 ft Sunday night. Outlook /Monday through Thursday/... Monday through Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Tuesday Night through Wednesday: Winds less than 25 kt. Seas up to 5 ft. Wednesday Night: Winds less than 25 kt. Areas of rough seas. Chance of rain. Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 9 ft. Rain likely. && .TIDES/COASTAL FLOODING... Still expecting minor coastal flooding with this evening`s high tide, thus have kept the coastal flood advisory in effect for this evening. Stevens Institute guidance still looking good with surges around 1-2 feet, but gusty winds will be much less than earlier today along with a lower astro tide. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Storm Warning until midnight EST tonight for CTZ002>004. MA...Blizzard Warning until midnight EST tonight for MAZ005-006-013- 014-017-018-020-021. Coastal Flood Advisory until midnight EST tonight for MAZ007- 015-016-019-022>024. Blizzard Warning until 5 AM EST Sunday for MAZ007-015-016-019- 022-023. Winter Storm Warning until midnight EST tonight for MAZ003-004- 008>012-024-026. Wind Chill Advisory until 10 AM EST Sunday for MAZ002-004-008- 009-012. Winter Weather Advisory until midnight EST tonight for MAZ002. RI...Blizzard Warning until midnight EST tonight for RIZ001>008. MARINE...Storm Warning until midnight EST tonight for ANZ230>237-250- 251-254>256. Freezing Spray Advisory until noon EST Sunday for ANZ231>235- 237-250-251-254>256. && $$ SYNOPSIS...BL/BW NEAR TERM...BL SHORT TERM...BL LONG TERM...BW AVIATION...BL MARINE...BL/BW TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
526 PM CST Sat Jan 29 2022 .SHORT TERM... Issued at 305 PM CST Sat Jan 29 2022 Through Sunday night... Overall, the short term period should be fairly quiet weather-wise. A weak surface low is expected to move across the area late this evening with an associated cold front pushing across the area turning winds northwesterly overnight. Strato-cu should fill in behind the front brining a chance for a few flurries Sunday morning coinciding with a vort max moving overhead. There remains a weak signal for light lake effect snow showers into northwest Indiana during the day tomorrow. Little to no accumulation is expected with this, other than perhaps a light dusting. The ECMWF and even the HRRR trend a bit further west into Cook county rather than into NW Indiana as the NAM suite suggests, so opted to hang on to a mention of flurries across southeast Cook County into the afternoon tomorrow. Overall not expecting much in the way of impacts from this. Will note that there is a non-zero chance for some light freezing drizzle given if the cloud layer temperatures are a bit warmer limiting ice nucleation. Something to keep an eye on. Temperatures tonight will warmer than what we saw last night thanks to some additional cloud cover and warming from today`s southerly flow, dropping into the teens for most areas. High temperatures tomorrow will also be a bit warmer than what we saw today, in the mid to upper 20s. Petr && .LONG TERM... Issued at 320 PM CST Sat Jan 29 2022 Monday through Saturday... Main forecast concern and focus continues to be the potential for a higher impact accumulating snow event Tuesday night through Wednesday night, and possibly Thursday as well. Confidence remains above average in big picture idea of a regional winter event in portions of the Midwest. However, key guidance differences in handling the pattern lend to lower confidence in the answers to the all important questions of when (start and especially end timing), where (the highest totals occur), and how much snow in the heaviest axis. On Monday and Monday night, lead wave and associated surface low from the Canadian Prairies to northern High Plains will drag a warm front gradually northward. Late day highs are forecast to reach the lower to mid 30s after a seasonably chilly start. Monday night will feature steady to slowly rising temperatures amidst breezy southerly winds. The surface low will be near Lake Superior by 12z Tuesday, with its trailing cold front near the MS River. The front will move across the area during the day on Tuesday, with light rain or showers developing in the vicinity of and behind the frontal zone, particularly for the southeast half or so of the CWA. Ahead of the cold front passage, we`re currently advertising most locations tagging 40+ degrees for the first time since January 18-19. Expect steadily falling temps behind the fro-pa. Tuesday evening/night through Wednesday night and into Thursday is the time window of concern for impactful accumulating snow and the important differences in handling the pattern crop up right away. Initial snow would be of the over-running variety. Lead short- wave energy will interact with a sharpening baroclinic zone across the region in the favorable right entrance region of an anti-cyclonically curved jet streak arcing to the north of the Great Lakes. This will occur north of a surface low pressure trough extending northeast from the southern Plains, while strong Arctic high pressure of 1045+ mb builds in from the northern High Plains. Open Gulf of Mexico moisture trajectories into the area will provide plenty of moisture to tap into, with PWAT plume into central IL and IN pushing or exceeding 200% of early February climo. There are key big picture features and other more complex elements, and the evolution of all these moving parts will determine how this all plays out. Big picture features of note include: a deep trough (negative height anomaly) to over the interior west/southwest; a stout tropospheric polar vortex lobe over Hudson Bay; and downstream positive height anomalies over the eastern US and Canada. Another important final piece of the puzzle is a currently subtle short-wave out near the International Dateline southwest of the Aleutians that will round the southwest trough and *potentially* lead to a stronger low pressure to close out the stretch. Here`s a breakdown of 3 general clusters of outcomes, in which the 12z global operational models fit decently into: 1) Weaker and farther north Hudson Bay PV will allow for slightly more pronounced eastern height rises, which enables strong moisture surge Tuesday evening and night to reach farther north into the CWA for potentially significant snow accums into Wed eve. The short-wave out over the eastern Pacific is slower to eject and positively tilted and subsequent stronger synoptic system later Wednesday night into Thursday takes off too far south and east for meaningful additional snow (aside from any lake effect chances). Similar 12z model run: ECMWF 2) Weaker and farther north Hudson Bay PV, more pronounced downstream ridging allows for moderate to heavy overrunning snow. THEN southwest short-wave takes on neutral to negative tilt and ejects out to favorably develop a stronger system with ~1005 mb surface low tracking near or north of Ohio River. This progression would bring another round of moderate to heavy snow along with even stronger winds into or through Thursday, aided by impressive right entrance region jet dynamics. In most amplified ensemble members, could even be some wintry mix p-type issues in parts of the area. Similar 12z model run: GFS 3) Stronger and farther south Hudson Bay PV lobe results in confluence and slightly suppressed positive height anomalies, and the strong/drying influence of incoming Arctic high to have more influence. Result would be banded overrunning precip having a very sharp northern cut off and focus the heaviest precip and snow axis into our southern CWA and points south and east (or even south of CWA altogether in most northern stream dominant ensemble members). Similar 12z model run: Canadian. Suffice to say that all three of these outcomes remain plausible and represented by the distribution of ensemble members of the three parent models. Overall, there is *currently* a slight lean in the ensemble means toward roughly outcome 1, favoring our southeast half or third, occurring amidst brisk northerly winds. For this reason, the most recent WPC Day 5 accumulating snow/sleet outlook appears reasonable with southeast half having higher (50-70% probabilities) vs. northwest (30-50% probabilities). Since the three approximate clusters described above remain plausible outcomes, we continue to urge caution with any individual model run snowfall outputs being shared. Stay tuned for updates as the potential event draws closer when we can be more confident on some of these still uncertain details. How cold it gets in the very cold air mass in the wake of the system will be determined by magnitude of the air mass and also if we can get favorable radiational cooling conditions under surface high pressure. There will also be a risk for lake effect snow showers, location details TBD Thursday night into Friday. This will be followed by moderation but likely still below normal temps for next Saturday. Castro && .AVIATION... For the 00Z TAFs... No significant aviation concerns. A weak cold front will move across the terminals early Sunday morning resulting in a wind shift to the northwest. Maintaining MVFR CIGS in the TAFs for Sunday though confidence in MVFR conditions is low and CIGS may end up being VFR. Given low confidence, opted not to change the previous TAFs which had MVFR cigs. - Izzi && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 223 PM CST Sat Jan 29 2022 Temperatures are higher and dew points are less than originally forecast. Thus, counties west and along a ling from Beatrice to Lincoln to Norfolk have been updated to a Red Flag Warning until 6 PM CST. A cold front will move across the area tonight and make a cooler day on Sunday, with highs in the 40s. Warm advection and southwesterly flow on Monday are expected to make temperatures to climb into the mid to upper 50s. An upper short wave trough moving across the Dakotas will bring a cold front across the area on Monday night. On Tuesday highs will be in the 30s. The aforementioned upper level trough that moves across the Upper Great Lakes, A deep upper level trough starts digging across the central Rockies and Desert Southwest. Isentropic lift and warm advection extending along and north of a front from Oklahoma into Missouri. Models differ in where this front sets up and how much energy comes out of the deep trough. Snow will be north of this front and at this time it appears that the axis of the heaviest snow is expected to be across northern Kansas to northern Missouri. After this system clears out of the area on Thursday, Arctic high pressure moves into the Missouri Valley and temperatures will rise only to the teens on Thursday. Lows on Thursday night are expected to drop below zero.The remainder of the period looks to be dry with a gradual warmup. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 523 PM CST Sat Jan 29 2022 At present, VFR conditions prevail across at all three TAF sites. Northwest winds with gusts 18-23kt at KOFK and KLNK will abate by 01-02Z. Backdoor cold front moving through southern portions of forecast area, cooler and more moist airmass will follow in its wake, lagging 9-10 hours. RAP, HRRR and NAM advecting MVFR ceilings into all three TAF sites between 09-11Z. HSREF hints at development with 20-40% probabilities of ceilings below 1K. Ceilings appear to remain intact through morning, so did not include improving conditions in TAFs for now. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Red Flag Warning until 6 PM CST this evening for NEZ016-030-031- 042-043-050-065-066-078-088-089. IA...None. && $$ DISCUSSION...Smith AVIATION...Fortin