Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/19/24


Area Forecast Discussion
National Weather Service Des Moines IA
817 PM CST Mon Nov 18 2024 .KEY MESSAGES... - Strong, gusty winds across south central and eastern Iowa tonight. Gusts 45+ mph possible. - Large system tracking through tonight/early Tuesday - Rain chances (90 to 100%) through midnight - Conditional severe threat this evening - Possible period of strong winds Tuesday && .UPDATE... Issued at 816 PM CST Mon Nov 18 2024 Strong isallobaric forcing continues to surge through the KC metro this evening with 8+mb three hour pressure rises south of the deepening 984mb surface low just east of Omaha at 8pm. Winds have gusted in excess of 58 mph in and near the KC Metro area ahead of these pressure rises, and the latest RAP and HRRR guidance depicts these strong winds moving across northern MO into eastern IA this evening and shortly after midnight. Thus have issued a Wind Advisory for these areas through 1am. Wind gusts of 58+ mph are possible, but they should remain isolated with 45-55 mph gusts more prevalent. && .DISCUSSION... Issued at 253 PM CST Mon Nov 18 2024 .Short Term /Tonight through Tuesday Night/... Confidence: Medium to High Large cyclone continues to spin north into Iowa this afternoon. Rather potent low expected to pivot through the state tonight. Main concern will be severe chances over the south into the early evening hours. Main window still appears to be 23-00z through around 02-03z when the boundary swings northeast and pinches off the warm sector. Similar to previous discussions a lobe of low level 100 to +300 m2/s2 SRH along with 200 to 300 J/kg 0 to 3km cape could easily be enough for a few storms promoting severe wind gusts or an isolated brief, weak tornado. Temperatures will continue to rise into the evening hours, along with dew points, and should increase to the lower 60s by 00z. As the occlusion pivots, there may be some lingering convection over the east/southeast but that is more conditional at this time. With some return northwest flow by morning, lows will dip to the lower 40s west to the lower 50s southeast with increasing winds. Rainfall totals from tonight into tomorrow will continue to add up to a half to nearly an inch over the north. Tomorrow the main concern will be increasing winds on the backside of the low as it moves away. Currently, we are modeling 35 to near 40kt gusts over the region. For now, given some uncertainty in the coverage and max gust potential, will not issue any headlines for wind just yet. As we move into Tuesday night and Wednesday, eventual wrap-around moisture will allow for snow showers some potential for a dusting of snow over the north and northeast. As we move into tomorrow night, mins will drop to the lower to mid 30s over the entire region. .Long Term /Wednesday through Monday/... Confidence: Medium to High Snow showers will be sporadic but present for most of Wednesday over the north with only a small chance farther south, maybe a flurry or two. Winds will remain rather brisk at 15 to 30 mph, diminishing Wednesday evening. Clouds will likely linger over the east/northeast Thursday with rather chilly highs in the 30s and wind chills in the 20s north to the mid 30s south. The remainder of the extended is still dominated by northwest flow with some weak waves progressing southeast during the period. There will likely be some moderation in temperatures with highs generally in the 30s to 40s during the period. The mildest day is likely to be Sunday as highs reach near 50 in the south. As it stands right now, the forecast looks dry from Friday through the weekend. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 606 PM CST Mon Nov 18 2024 Widespread stratus and showers were in place across central IA with quite variable conditions ranging from LIFR to MVFR, mainly depending on ceilings. IFR conditions are expected to be most prevalent through the night, but with SW-NE improvement 09-15Z as things trend more toward MVFR-VFR and then VFR at 18Z. Intermittent showers are expected to persist through 06z before ending north shortly after 12z. Winds will remain strong and gusty with 25-35kt gusts into Tue afternoon. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Small DISCUSSION...REV AVIATION...Small
Area Forecast Discussion
National Weather Service North Platte NE
616 PM CST Mon Nov 18 2024 .KEY MESSAGES... - Precipitation in the form of rain will continue through late this evening. For areas east of Highway 83, all rain is expected. Closer to the Pine Ridge, a transition to snow is likely with little to no accumulations expected. - The pattern will remain conducive to strong winds each day Tuesday and Wednesday. This will coincide with an influx and dry air and the threat for elevated to near-critical fire weather concerns each day. - Broad upper-ridging will herald dry and mild weather for days 2-5 (Tuesday through Friday) before the next disturbance approaches from the west and brings low-end (< 20%) PoPs for mainly the Nebraska Panhandle. - Signs are beginning to point to a pattern flip late next week that will bring much colder temperatures and the potential for precipitation including snow. This has the potential to have implications for holiday travelers and folks are advised to continue monitoring later forecasts. && .SHORT TERM /THROUGH TONIGHT/... Issued at 340 PM CST Mon Nov 18 2024 Satellite analysis shows a maturing mid-level cyclone lifting north and east across south central and eastern Nebraska. Tell-tale sign includes the comma-head appearance of upper-level imagery including the low-level water vapor band. Radar shows consolidating reflectivity across central Nebraska coincident with the greatest mid-level convergence within the deformation band. Mesoanalysis shows rapid pressure falls east of the Tri-Cities which lines up with the forecast track of the primary surface low which is now sub- 990 hPa over north central to northeast Kansas. Temperatures range from the low 40s under the heavy precipitation at Broken Bow up through O`Neill to the middle 50s further west across the Sandhills into the Nebraska Panhandle. For tonight...the aforementioned surface low will continue to lift north and east across south central and eastern Nebraska. With the local area squarely in the northwest quadrant, main forcing will continue to be from strong mid-level convergence on the backside of the system. Short-term guidance is quick to wane this forcing for ascent as the evening progresses with essentially all associated precipitation expected to wrap up around midnight. Cooler air will quickly filter in behind this activity but the expectation for areas east of Highway 83 is this will be delayed enough to preclude any concerns for a precipitation type transition to anything other than rain. Later this evening, a strong cold front will dive southeast through the area. Rapid pressure rises are expected in the wake of this feature with magnitudes of up to 2-3 hPa/hour possible. This along with an increase in CAA and already constricted pressure gradient should yield strong gusty winds for much of the area overnight. Various high resolution solutions, notably the HRRR and RAP, advertise a very quick increase from 25-35 mph gusts to 35-45 mph gusts in the post frontal environment. While plan view maps advertise gusts nearer to 50 mph, NWP performance for overnight wind gusts has been suspect at best. Further evaluation shows limited signal for > 50 knots (58 mph) anywhere within the lowest 2km of the atmosphere across the forecast area. Utilizing probabilistic data, probabilities of exceeding 45 mph gusts are maximized across far northern Nebraska in vicinity of Valentine where probabilities exceed 70% with greater probabilities immediately north into South Dakota. Further southwest, increased signals also exist across southwest Nebraska outside of the Platte Valley system though not quite as high peaking around 65-70%. The going forecast utilized a blend of 90th percentile values along with some of the high resolution guidance noted previously. This produced fairly widespread gusts nearing 40 to 45 mph with a few locations around Valentine climbing closer to 50 mph. In-house tools suggest this is near the 50th percentile of NBM guidance and while that suggests increases are possible, timing of the peak winds casts some doubt on the higher values panning out. Within the northwesterly flow behind the passing front, flow in the low levels will diverge around the Black Hills but perhaps yield enough lee-side convergence to lead to localized precipitation chances nearer the Pine Ridge. It`s worth noting that few model solutions depict any QPF from this. That said, enough signal exists to warrant inclusion of some low-end PoPs (< 20%). HREF probabilities suggest ptype favoring snow and forecast soundings support this with a shallow saturated layer extending up to the DGZ. Even the most bullish guidance paints very light QPF and so the going forecast is little to no accumulations expected with only a couple hour window for anything to occur. Low temperatures will fall into the middle 20s west to middle 30s east. && .LONG TERM /TUESDAY THROUGH MONDAY/... Issued at 340 PM CST Mon Nov 18 2024 Tuesday and Wednesday...while the local area will see decreasing impacts from the main disturbance tracking to the east, combining factors will still set the stage for strong wind gusts each day. Main upper-level low will continue to lift northeast early Tuesday but will gradually phase back into the flow aloft as another shortwave trough ejects onto the northern Plains. The main surface low will begin to occlude across the northern Mississippi Valley, gradually lifting northwest into southern Canada as it does. As the area becomes pinched off from a high pressure west of the Continental Divide and the deep low to the northwest, steady northwest winds will prevail across the area. Mid-level height contours will relax some however which should allow flow aloft to weaken. This is illustrated by a notable decrease in 0-2km average winds which subside after daybreak as it moves north into the Dakotas. This is likely what will allow for sub-headline winds (High Wind Warning: 58 mph gusts or greater) from occurring. Still, forecast gusts of 35 to 45 mph are expected with the strongest of these values across the north. Though daytime temperatures have actually trended up, maximum apparent temperatures will struggle to climb out of the low to middle 30s. Similar thinking is expected for Wednesday. As the deep low pressure system drifts across southern Canada, strong west to northwesterly winds will again develop for much of the region. A tightening height will maintain strong kinematics aloft with a strong surge of CAA likely Wednesday morning. As this occurs, a stronger PV anomaly will begin to dive east-southeast grazing our northern zones early in the day. This should allow for efficient downward mixing which should crater dew point values into the single digits for much of the area. Casting some uncertainty in peak speeds however is how quickly the boundary layer mixes and taps into the stronger flow aloft. Given little to no decoupling expected Tuesday night into Wednesday, the thought is this occurs quickly and the boundary will tap into 50+ knot h85 flow by late morning. Winds aloft then subside so any threat of High Wind Warning criteria gusts should quickly end. Latest NBM probabilities of seeing > 34 knot (~39 mph gusts) is now higher for Tuesday than Wednesday so this supports latest thinking that the window will be quite short lived on Wednesday and limits confidence enough to preclude headlines. With high temperatures in the middle to upper 40s each day, afternoon humidity minimums are likely to fall into the 20s and possibly even the upper teens respectively Tuesday and Wednesday. This will lead to elevated to near-critical fire weather concerns with more weight given to the expected winds. The latest SPC outlook has introduced a Day 2 Elevated concern for mainly the western zones with mention that later outlooks for Wednesday may need similar. Am in agreement with this as any fire start will likely become difficult to contain in the expected strong winds. Thursday and beyond...the extended forecast calls for a continuation of mostly if not entirely dry weather and abnormally warm temperatures. This is largely due to the return of increasing mid- level ridging expected to develop during the time frame. By Saturday, NWP guidance is in good agreement placing the ridge axis along the spine of the central Rockies and modest northwesterly flow locally in the downstream flow. The next disturbance moving through western CONUS will kick this ridge through the area over the weekend. Temperatures will gradually fall to more seasonable values by early next week. The model blend has introduced Slight Chance (< 20%) PoPs for our far northwest zones Sunday night into early Monday. This is the lone exception to the dry forecast through Day 7. While the NBM probabilities support this, GEFS/EPS probabilities are sorely lacking so confidence is low. Either way, little to no impacts are expected. Heading into the middle to latter half of next week, a pattern change appears likely. EPS/GEFS suggest increasing ridging over Alaska/Gulf of Alaska. This will allow for colder air to spill south across Canada and into CONUS just in time for the Thanksgiving travel window. Both EPS/GEFS showcase negative anomalies for temperatures over much of the Rockies and spilling south onto portions of the Plains. Variability within each ensemble suite remains fairly high, however, with inner-quartile spreads approaching 20 degF. That said, there appears to be a left skew within the data towards the end of the month suggesting more guidance supports colder temperatures than the opposite. This will bear watching for folks with travel plans for the holiday as the colder temperatures will be favorable for wintry weather, even during the daytime. The latest CPC outlook is catching onto this trend with below normal temperatures and above normal precipitation favored in both the 6-10 and 8-14 Day Outlooks so stay tuned. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 614 PM CST Mon Nov 18 2024 Rain will gradually come to an end for areas east of Highway 83 later tonight. IFR/MVFR ceilings across eastern portions of north central Nebraska around ONL will gradually lift late tonight. Winds will then increase from the northwest all areas late tonight and continue through Tuesday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...NJ LONG TERM...NJ AVIATION...Taylor
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
952 PM CST Mon Nov 18 2024 .KEY MESSAGES... - Increasingly strong and gusty winds tonight into Tuesday, gusts to, or even a little over, 40 mph are possible - Unseasonably warm weather will continue through Tuesday, followed by much colder weather, coldest air mass of the autumn - Intermittent light showers possible at times Tues night through Wed night, with some wet snow flakes possibly mixed in - Chance of wet snow or rain/wet snow mix Thursday, low probability of some slushy accumulations, mainly on grassy surfaces && .UPDATE... Issued at 952 PM CST Mon Nov 18 2024 The next round of showers is beginning to lift into the area late this evening and has at times been accompanied with isolated embedded thunderstorms. Due to how close this activity is getting to the area, opted to introduce a slight chance of thunder back into the forecast with the evening update to account for an occasional lightning strike over the next few hours. Wind speeds are also steadily on the increase with peak wind gusts in the 35-40 mph range occurring within the band of rain. Hi-res guidance continues to be rather bullish on how strong the winds increase overnight, likely due to mixing a bit deeper into the strengthening low-level jet overhead. While sporadically higher gusts remain possible, have held off on issuing a Wind Advisory with this update. Will continue to monitor observational trends. Petr && .DISCUSSION... Issued at 259 PM CST Mon Nov 18 2024 Vigorous mid-latitude cyclone over the central U.S. will provide for some active weather over the next 24 hours. At 19Z, a 987mb surface low was analyzed over central Kansas with a warm front extending north extreme northwest Missouri, then east across down state IL. North of this warm front, our CWA is covered with widespread rain, low cloudiness, and light fog this afternoon. As the KS sfc low moves north to near KMSP by daybreak Tuesday, it will drag the warm front north across our area this evening, bringing a temporary end to the rain this evening. The break should be relatively short lived as a prefrontal band of showers across eastern Oklahoma and eastern Kansas lifts quickly northeastward and across our CWA late this evening into the early portions of the overnight period. Guidance is in pretty good agreement that there will be little if any upright instability and given the lack of lightning upstream, think the chances of thunder in our CWA is too low to maintain a chance of thunderstorms in the grids. Having said that, some of the more robust convective-y showers (without lightning) could lead to some locally stronger wind gusts late this evening into the overnight hours. In addition to some stronger gusts in a few of the showers, there is also concern with the potential for strong synoptic winds tonight. As the deep low pressure tracks north into the mid-upper Mississippi Valley tonight, very strong pressure falls (>6mb/3hr) in advance of the low should result in a significant isallobaric response to the winds over the area this evening. Anticipate winds will ramp up to 20-30 mph this evening with gusts of 30-40 mph a pretty good bet. Certainly can`t rule out stronger gusts, particularly if temperatures overperform this evening, but confidence in gusts 45+ mph isn`t high enough to justify issuing a wind advisory, but will brief oncoming evening shift on the potential. Interestingly, behind the band of showers, the HRRR and 3km NAM show another surge of stronger wind gusts (45-50+ mph). This will coincide with very strong low level jet moving across the region with >50kt at 925mb and >70kt at 850mb. By this later tonight, the stronger isallobaric wind component should have shifted north of the area, so confidence in how much of very high momentum air associated with the low-level jet will be able to mix to the sfc in gusts is low. This would also be a period worth monitoring for potential wind advisory should winds overperform. Sfc trough trailing well behind the initial band of showers will move across the area early Tuesday morning. Could be a few hours of stronger southwesterly winds behind that boundary Tuesday morning (roughly 11-17z) with some 40+ mph gusts again possible. Unseasonably warm temperatures are expected tonight. As the warm front lifts north, look for sfc temps to rise into the upper 50s to lower 60s and likely remain there through the night. Just to put into perspective how unusually warm this is, our average high temperatures this time of year are in the 40s! Not going to threaten any daytime record warm low temperatures as temps will Tuesday evening prior to midnight. Confidence in the large scale pattern evolution is quite high for the middle and end of the week, however, unfortunately, confidence is quite low in the finer scale details. Among these "smaller scale details" would include the potential for snow, possibly enough to whiten the ground in portions of our CWA Thursday, To the west of central U.S. cyclone is a vigorous northern stream trough over the northern Rockies and Pacific Northwest. These two troughs are progged to phase over the northern Plains Tuesday night, evolving into a large and deep closed mid-upper level low. In case things weren`t complicated enough already, another shortwave trough and associated mid-upper level jet streak about to move onshore California this afternoon is progged to quickly move eastward on the southern flanks of the powerful northern Plains cut off low. This wave will move across the mid-Mississippi Valley by early Wednesday morning, which could lead to some chance of showers starting Wednesday morning. The 12z ECMWF and 12z GFS both now depicting a fairly fascinating evolution with the aforementioned shortwave now essentially fujiwhara-ing around and phasing with the upper low over the upper Midwest late Wednesday into Wednesday night. Interestingly, that second shortwave is progged to pivot all the way around the mid-upper level circulation and pivot west and southward across Michigan late Wed night into Thursday. Both the GFS and ECMWF depict a new sfc low developing in the vicinity of Lakes Huron and Erie late Wednesday afternoon, then showing rapid deepening of this low as it cyclonically loops north, then west, and eventually southwest across lower Michigan Wed night into Thursday. In this scenario, a band of formidable warm air advection driven precipitation would develop on the north then western flanks of this low. This precipitation is then progged to move southwest into our CWA late Wed night/early Thursday morning. Temperatures initially would likely be cold enough to support wet snow, possibly mixing with or changing to rain during the day Thursday as northerly wind advect in a warmer air mass that will have completely rotated around this cyclone. In this general scenario that the 12z GFS/ECMWF are depicting, some portions of our CWA could see some slushy snow accumulation, mainly on grassy surfaces and away from the immediate lakeshore. Hard to stress just how much uncertainty exists in this forecast for Thursday. Not only was this a very significant change from previous runs, but it is also an extremely complex evolution with many moving pieces. Models often struggle with handling phasing waves and in this case it is 3 main different waves phasing. It is interesting that the operational 12z GFS and ECMWF both made this significant change in unison, but given the complexity of the set-up, I`d be very cautious in putting too much stock in these runs until there is more ensemble support and some run-to-run consistency. In the wake of this system, near average temperatures are expected heading into next weekend with likely drier weather conditions. - Izzi && .AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 600 PM CST Mon Nov 18 2024 Forecast concerns for the terminals... - Another period of showers tonight into early Tuesday morning - Brief period of VFR ceilings this evening becoming MVFR to near IFR tonight then gradually improving Tuesday afternoon - Breezy southeast winds tonight becoming southwest and gusty Tuesday morning with gusts around 35 kts possible An strong storm system continues to intensify over the central Plains this evening and is expected to lift into the upper Midwest overnight. The systems warm front did move through northern IL and northwest IN earlier today which is generating the ongoing showers and LIFR ceilings. As this initial wave of showers tapers over the next hour, ceilings will lift into the IFR category and then eventually VFR between 02z and 03z. Though, pockets of SCT to BKN 2500-3000 ft ceilings may lingering this evening. A second round of showers is expected to move into the area around midnight (between 04z-06z) and persist through the night as the system`s cold front moves through. While the more convective nature of this round of showers should keep ceilings higher, MVFR to near IFR ceilings and IFR visibilities are still expected to occur with the showers overnight. The cold front should exit the area by 12z Tuesday which will allow showers to come to an end leaving dry conditions for the rest of the forecast period. Aside from the showers, winds are expected to increase in speed this evening as the surface low traverses across IA into MN. Gusts this evening will generally be in the 25-30 kt range out of the southeast, but a few higher gusts will be possible in the wake of the showers. Winds will become southwesterly behind the front Tuesday morning along with a quick uptick in winds as the atmosphere mixes into the low-level jet around 12-13z. Therefore, expect a period of 30-35 kt gusts Tuesday morning with locally higher gusts to 40 kts possible. Wind speeds will gradually ease Tuesday afternoon and evening, but a few teen to 20 kt gusts may persist through the end of the forecast period. Finally, any MVFR to near IFR ceilings with the aforementioned showers tonight will lift to MVFR Tuesday morning and continue to gradually improve through rest of the day. However, there is a strong signal in guidance that some 3000-4000 ft ceilings should persist through the end of the forecast period. Furthermore, there is also a potential for some 2500-3000 ft stratus to redevelop Tuesday night but this is somewhat low confidence due to uncertainty in how mixed the atmosphere will remain. Given the notable signal in guidance for this potential have decided to include a SCT025 mention in the 30-hour TAFs as a precaution. Yack && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory until 3 PM CST Tuesday for the IL and IN nearshore waters. && $$ Visit us at weather.gov/chicago
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
527 PM CST Mon Nov 18 2024 .KEY MESSAGES... - A line of showers and isolated thunderstorms will move through the area this evening. There is a low chance that a few storms will be strong to severe across parts of central and northeast Missouri. - After another above normal day on Tuesday, temperatures will be at or below normal for late in the week into the weekend. && .SHORT TERM... (Through Late Tuesday Night) Issued at 233 PM CST Mon Nov 18 2024 The first round of rain from this morning has moved north of the area with an additional batch of rain encroaching into northeast Missouri at the moment ahead of the deep upper low over Kansas. CAMS including the HRRR continue to show that the band of showers and few thunderstorms currently over the Plains ahead of the cold front will move into the CWA late this afternoon and early this evening and move east across the area. The RAP/NAM is still showing 300-500 MUCAPE/minimal SBCAPE with strong low-deep layer shear as storms move across the CWA this evening. The CAMS also show a gradual decrease in simulated reflectivities which also match going thinking that best chance for any strong to severe storms including damaging winds or a brief tornado or two will be over central Missouri early this evening. The band will move east of the area overnight with dry weather expected for Tuesday and Tuesday night. Temperatures have climbed well above normal today in the warm sector. The cold front will only have weak cold air advection behind it, so temperatures will still be above normal through Tuesday night. Britt && .LONG TERM... (Wednesday through Next Monday) Issued at 233 PM CST Mon Nov 18 2024 The GFS/NAM are showing another trough moving across Missouri and Illinois on Tuesday night into early Wednesday. This will bring with it enough moisture to bring a slight chance of light rain over our Illinois counties on Wednesday morning. Then model guidance is showing an upper ridge building into the Midwest late in the week into next weekend with most (>90 percent) of the LREF members dry during this period. Colder air will arrive behind a second cold front with the 850mb temperatures dropping below 0C on Thursday before climbing back to around 5-10C on Sunday. Temperatures will stay at or below normal through the period. Britt && .AVIATION... (For the 00z TAFs through 00z Tuesday Evening) Issued at 514 PM CST Mon Nov 18 2024 A broad band of rainfall ahead of a cold front is approaching the local terminals from the west and will be impacting KCOU and KJEF imminently. As this band moves eastward across the terminals, it will produce steady rain that will reduce visibilities to MVFR flight category, with a low chance of IFR. There also may be a rogue lightning strike or two near KCOU and KJEF, but confidence in this occurring is low. MVFR ceilings are expected to accompany the rainfall, with brief IFR ceilings possible especially for KUIN. Late tonight, dry air will punch into the region, bringing an end to the rain and improving ceilings, though winds will stay gusty into the morning. Elmore && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
1005 PM EST Mon Nov 18 2024 .KEY MESSAGES... - A slow moving system will usher in a wet pattern into the weekend. Precip will mainly be rain, but some snow may be possible Wednesday night. - Widespread strong southeast winds Tuesday will pose some risk for power outages and tree damage. Strongest winds are expected in the Keweenaw, which may approach 50 mph. A Wind Advisory is in effect for Tuesday there. - Strong winds will build large waves on the Great Lakes Tuesday. This may result in minor beach erosion or lakeshore flooding on the southern/eastern lakeshores of Keweenaw County and in Delta County, south of Escanaba and the southern half of the Garden Peninsula. - East to southeast gales, with some storm force gusts, are expected late tonight and Tuesday. Widespread large waves will develop in this period across central Lake Superior. && .UPDATE... Issued at 1005 PM EST Mon Nov 18 2024 Rain showers are spreading into the southern UP this evening, and though winds remain benign so far, expect blustery conditions to set in over the next several hours. This latest update, winds have been adjusted upward slightly - particularly across the western UP and nearer the Lake Superior shoreline in Alger county to align with stronger gusts present in many of the latest hi-res model runs. With the potential for stronger 40-50mph gusts lakeside in Alger county, a Wind Advisory has been issued for Alger county for Tuesday morning and afternoon. && .SHORT TERM /THROUGH TONIGHT/... Issued at 248 PM EST Mon Nov 18 2024 GOES-16 Day Cloud Phase RGB imagery shows clear skies over the UP except for some high cirrus streaming in from the south and west. These are associated with a deepening closed low which the RAP analysis has at 990mb over Kansas at 18Z. This low is expected to continue to deepen as it races northeast, reaching the Minneapolis vicinity at around 983 mb by Tuesday morning per the 12Z GEFS. Precipitation ahead of this system arrives along the MI/WI state line around 00Z tonight. Precipitation totals by 12Z Tuesday look to be a widespread quarter to a half inch of rain, though the upsloping areas of Menominee County and the Keweenaw Peninsula could see near 3/4 inch as easterly winds ramp up and provide an orographic enhancement to precipitation. The winds will present the more hazardous weather conditions, as a tightening pressure gradient, pressure falls, and warm air advection helping mix into a 30-40 kt 925 mb layer will all contribute towards gusty winds overnight into Tuesday morning. The HREF suggests 40-80% chances of 45 mph wind gust potential over the west half overnight, though the HREF tends to overestimate wind gust potential. Still, local guidance suggests the highest gust potential to be over the Keweenaw Peninsula, so a Wind Advisory has been issued for Keweenaw County and northern Houghton County, though the higher terrain of Ontonagon, Gogebic, and Baraga counties may also experience a rare (>20% chance) gust up to Wind Advisory criteria. && .LONG TERM /TUESDAY THROUGH MONDAY/... Issued at 307 PM EST Mon Nov 18 2024 There`s good agreement among the determinsitic models and their respective ensemble packages this morning, suggesting the main item of interest will be the evolution of a closed mid-level low and multiple surface lows through the Great Lakes this week. Current water vapor imagery from GOES 16 and RAP surface/height analysis show the initial closed circulation aloft lifting from the southern Rockies into the southern Plains. As this feature lifts northeast, the mid-level trough will take on a negative tilt, allowing the surface low to deepen as it lifts through the Plains tonight. By 12z Tuesday, GEFS and EPS ensembles show tight clustering of the low being positioned over west/central Minnesota with the system`s occluded front pressing north into the Upper Great Lakes. Frontally forced rain within a swath of deep moisture, in response to increasing upper level divergence will be ongoing Tuesday morning and appears likely to remain through a majority of the day. There`s good agreement among the various guidance packages that a widespread 0.25-0.75 inches of rain will be realzied before the system`s dry slot lifts in late Tuesday. Best chances of exceeding 0.5", per EPS and GEFS are across the south central at 60% or greater. Tightening pressure gradient associated with the lifting low will also result in pressure falls on the order of 7 to 9mb per 6 hours ahead of the front. This will result in strong southeasterly winds overspreading the area Tuesday morning. These winds, particiarly near the lakeshores of the Bay of Green Bay, Lake Michigan, and in the Keweenaw will grow to 35-50 mph while widespread 25 to 30 mph wind gusts are expected elsewhere. Model soundings suggest some potential for gusts >50mph, should mixing be effective. Opted to issue a Wind Advisory for Northern Houghton and Keweenaw counties for Tuesday. Opted to wait on advisories elsewhere for the time being, allowing the next crew a second look. The front looks to lift north in the afternoon, which will kick the winds to the southwest and lighten as the gradient forces relax and daytime mixing ends. The strong winds will result in large waves building on the Great Lakes, which could result in minor beach erosion or minor lakeshore flooding. Opted to issue a Lakeshore Flood Advisory for Delta County for areas south of Escanaba and the southern half of the eastern shores of the Garden Peninsula. Rain will end from south to north late Tuesday as the surface low lifts into Mantitoba. Overnight into Wednesday, the mid-level low will progress southeast while the dry slot of this system moves overhead. As the mid-level feature migrates east, it will again amplify, resulting in a second surface low developing near Lake Huron by Wednesday afternoon. The low will slowly wobble around Michigan while occluding through Thursday before a third low develops off of the Mid-Atlantic coast. This final feature looks to occlude on Friday, then shift through New England through Saturday. The results of this evolution will be to keep synoptic rain possible Wednesday for the east, then lake enhanced precip becoming the norm Wednesday night into Thursday across Upper Michigan. Rain should switch over to snow late Wednesday into night, particularly for any precip away from the lakeshores across the west half and higher terrain spots of the east. Amounts look to be light, mainly an inch or two or less. Eventually, the mid-level low exits east, leaving behind continued cyclonic flow with 850mb temps of -4 to -2C. This should keep lake effect rain/snow showers downwind of Lake Superior into Saturday. Mid-level ridging will eventually filter in from west to east late Saturday/Sunday, with a more uncertain pattern developing aftewards. A brief, psuedo-zonal flow pattern looks to develop across CONUS afterwards but this looks shortlived as an eastward migrating shortwave interupts this for our forecast area late Sunday/Monday. Plenty of uncertainy that far out, but the airmass behind this appears to bring 850mb temps down to -10 to -5C for the start of next week. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 659 PM EST Mon Nov 18 2024 Conditions will deteriorate this evening as a low pressure system approaches the area. This system will bring rain showers, gusty winds, LLWS as well as low ceilings and visiblity. Showers will push from southwest to northeast across the area, arriving at IWD around 02Z and and to SAW and CMX around 05Z. Conditions will deteriorate to MVFR around 05Z at IWD and by 09Z at SAW and CMX, with IFR conditions expected at all terminals by 15Z. LLWS has been added at all sites as a low level jet passes over the UP overnight into tomorrow. && .MARINE... Issued at 307 PM EST Mon Nov 18 2024 Complex evolution of a mid-level low into and through the Great Lakes will result in an active period for the Great Lakes this week. The first surface low will lift into the north-central Plains tonight with strong pressure falls preceeding. A very strong low level jet will produce high end southeast gales late tonight and Tuesday. Interal probablistic guidance suggests a ~25% chance storm force winds may be realized east and north of the Keweenaw. These strong winds along with a long fetch, could support waves above 15 feet across a majority of the middle third of the lake Tuesday. A quick wind shift to the southwest is expected after the front passes Tuesday evening. Recent guidance suggests a few hours of southwest gales to 35kts across the west half of the lake. This low will diminish by Wednesday morning as the mid-level low develops a secondary surface low near Lake Huron. Guidance suggests this low will slowly meander north to near the St. Marys Wednesday evening before falling back south over mainland Michigan Thursday. There`s some uncertainty about how deep this secondary low will end up and exactly where it`ll press, but at the very least, north to northeast winds will increase Thursday morning to near 30kts. Recent model runs have trended toward a deeper surface low, suggesting gales may occur. This will warrent closer. Winds should settle Thursday night as this low diminishes and a third develops off the east coast. Overall though, the cooler airmass and lingering gradient forces should support 20-30kts across a majority of the lake into the weekend. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Wind Advisory from 5 AM to 4 PM EST Tuesday for MIZ001-003. Lakeshore Flood Advisory from 11 AM to 5 PM EST Tuesday for MIZ001. Wind Advisory from 7 AM to 3 PM EST Tuesday for MIZ006. Lakeshore Flood Advisory from 3 AM to 3 PM EST Tuesday for MIZ013. Lake Superior... Gale Warning until 11 PM EST /10 PM CST/ Tuesday for LSZ162. Gale Warning from 4 AM EST /3 AM CST/ to 6 PM EST /5 PM CST/ Tuesday for LSZ241>244. Gale Warning from 4 AM to 7 PM EST Tuesday for LSZ245-264-265. Gale Warning from 4 AM to 4 PM EST Tuesday for LSZ246>248. Gale Warning from 7 AM to 4 PM EST Tuesday for LSZ249-250. Gale Warning from 7 AM to 7 PM EST Tuesday for LSZ251. Gale Warning from 4 AM to 11 PM EST Tuesday for LSZ263. Gale Warning from 5 AM to 7 PM EST Tuesday for LSZ266-267. Lake Michigan... Gale Warning from 4 AM to 1 PM EST Tuesday for LMZ221-248-250. && $$ UPDATE...LC SHORT TERM...GS LONG TERM...JTP AVIATION...RM MARINE...JTP
Area Forecast Discussion
National Weather Service Omaha/Valley NE
506 PM CST Mon Nov 18 2024 .KEY MESSAGES... - Widespread rainfall (100% PoPs) continue through this evening. There is a 5-10% chance of a strong wind gust and/or brief tornado mainly south of I-80 in Nebraska late this afternoon into evening. - Windy and cooler Tuesday and Wednesday with below-normal temperatures continuing into next weekend. && .DISCUSSION... Issued at 245 PM CST Mon Nov 18 2024 This afternoon - Tuesday... A potent low pressure system is moving across the region this afternoon, with the "dry-ish" slot pushing up into southeast Nebraska. This will cause rain to become more showery in nature. If we get any significant breaks in the rain with a few peeks of sun later this afternoon, we could potentially destabilize enough for a couple stronger storms to develop. My hunch is that instability will be too limited for a severe weather threat, but the HRRR shows what may be the "worst-case scenario" producing a few stronger storms. With plenty of low-level wind shear near the center of the surface low, if we can get a stronger storm to develop we could see a threat for damaging winds and a tornado or two. As the low- pressure system exits to the northeast, we`ll see winds ramp up out of the northwest overnight tonight and especially Tuesday morning. Tuesday is going to be a windy, cool day, with wind gusts of 25 to 35 mph. We could potentially get a few gusts up near 40 in northeast Nebraska. With skies clearing, we will see temperatures get up into the upper 40s to low 50s during the afternoon. Winds will make it feel cooler, with max apparent temperatures in the low 40s in northeast Nebraska. Wednesday and beyond... Wednesday, a strong northerly low-level jet sets up as the trough to our east gets stalled, leading to potentially even windier conditions. Right now we have gusts to 35 to 40 mph, but could potentially be higher. With northerly winds advecting in cooler air, highs will only get into the 40s on Wednesday despite another sunny afternoon. Thursday the trough to our east finally breaks loose, allowing the pressure gradient across our area to relax which will decrease winds. With relaxing winds, we should see much more efficient radiational cooling Wednesday night into Thursday morning, bringing temperatures down into the 20s across our area, and a few spots may drop into the teens. With a significantly cooler start and cooler air continuing to advect into the region from the northwest, temperatures during the afternoon on Thursday will likely only get into the upper 30s to mid 40s. Our coldest morning will probably be on Friday as we see winds drop to nearly calm. Temperatures will fall into the upper teens to low 20s across much of our area. Good news for people who don`t like cold weather, though, is that we`ll have a ridge start to build in which will lend toward a warming trend over the weekend. Highs will be in the low-to-mid 40s on Friday, mid 40s on Saturday, and mid 40s to low 50s on Sunday. This ridge will also keep us dry through the weekend. Next week looks like the active pattern will continue with another trough flattening out the ridge and allowing for another potential system midweek. Models are flipping back and forth and keep moving this system around, so confidence is very low in details at this time. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 506 PM CST Mon Nov 18 2024 MVFR to IFR ceilings and occasionally visibility will continue early in the period as rain continues to move through. There remains a small chance (around 20%) of a few thunderstorms at LNK and/or OMA from around 01-03Z, but did not include mention at this time, as lightning should be pretty isolated if it does occur. Expect improvement to VFR conditions as the rain pushes out from 03-06Z, with FEW to SCT passing mid level clouds by Tuesday afternoon. Otherwise, winds will be northwesterly through the period at OFK, gusting 25 to 35 kts. At OMA and LNK, winds will start as southeasterly, but will also become northwesterly fairly early in the period with similar gusts. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...McCoy AVIATION...CA
Area Forecast Discussion
National Weather Service Spokane WA
340 PM PST Mon Nov 18 2024 .SYNOPSIS... Precipitation will be more showery through early Tuesday. Weather will remain unsettled through the week with the next winter storm Tuesday night into Wednesday bringing another round of widespread snow. This will result in moderate to major impacts across central Washington and minor impacts for eastern Washington and north Idaho. Additional systems passing through Thursday through next weekend will bring additional periods of lowland rain and mountain snow. && .DISCUSSION... Tonight and Tuesday: The Inland NW is in a conditionally unstable air mass through Tuesday morning with 500mb temperatures down to 35C leading to steep mid level lapse rates. This will result in continued shower activity over the region, with the highest coverage along the Cascade crest, and Idaho Panhandle with the assistance of low level upslope flow. Although snow levels will be falling overnight down to the valley floors so any showers overnight into Tuesday morning will have the potential to produce slick roads. Tuesday afternoon a brief short wave ridge moves over the region ahead of a strong weather system. JW ...HEAVY SNOW TO IMPACT CENTRAL WA TUESDAY NIGHT INTO WEDNESDAY... Tuesday night through Wednesday: Models continue to remain in good agreement in a low pressure undergoing explosive cyclogenesis as it nears the Washington coast on Tuesday and amplifies an upper level ridge over the interior western US. Deep southwest flow aloft will allow an atmospheric river to take aim at northern California and southwestern Oregon Tuesday night. As this low begins to occlude Tuesday night and gradually shifts northwestward, it will draw warm, moist air into eastern Washington and north Idaho, resulting in widespread moderate to heavy precipitation. The surface looks to start off quite dry and cold Tuesday evening with dew points in the low to mid 20s which will lead to some cooling as the column saturates from the top down. The focus for an anomalous snow event will for the Cascades, the east slopes, the Waterville Plateau, Okanogan valley and highlands as a strong east to southeast pressure gradient of -14 to 18 mb from SEA-GEG will provide favorable upslope flow into these areas. This is consistent with the ECMWF Extreme Forecast Index which highlights these areas for an anomalous snow event Tuesday night into Wednesday morning. Precipitation will fall as snow across the upper Columbia Basin, northeast Washington, Palouse, Spokane area, and the Idaho Panhandle later Tuesday evening through early Wednesday morning. While this will provide the most snow some of these lowland areas have seen so far this year, it is not being highlighted as particularly abnormal. Snow Amounts: Snow will increase over the Cascades and central Washington Tuesday evening. Strong upslope and isentropic ascent into the east slopes suggest periods of moderate to heavy snowfall rates for these areas between 10 PM and 4 AM. Snowfall will spread northeast into far eastern Washington and the Idaho Panhandle late Tuesday night. At this time, our forecast is calling for 6 to 10 inches of snow for the central Washington valleys and 10 to 15 inches for Stevens, Washington, Sherman, and Blewett Passes. There still remains uncertainty in the exact amounts for the Wenatchee area as the winds shift to the south Wednesday morning. Most deterministic models want have 850mb winds shifting to the south-southeast after 10AM Wednesday with downsloping winds off Mission Ridge ending the precipitation, however the GFS wants to hold on to the southeast flow into central WA longer. Further east into the Spokane and Coeur dAlene areas, amounts look to be much less compared to central Washington, but models are suggesting a 3 to 5 hour period of moderate snow rates early Wednesday morning before switching over to rain. There are some timing differences in the high resolution models that are available when this band will move through with the HRRR having the band over the Spokane area around 1AM and transitioning to rain by 4AM. On the other hand, the NAMNest delays the snow over the Spokane area until 4-5AM. With that said, the delayed start time would result in a slick drive Wednesday morning. Warm air nosing north/northeastward Wednesday morning will bring a transition from snow to rain starting in southeastern Washington and working its way east and north with time. Winter Weather Advisories have been issued for the lowland areas where 2 to 4 inches of snow are expected generally along areas north of I-90 from the Basin through the Coeur d`Alene area. Further north across the northeast valleys and northern Panhandle valleys look to pick up between 3 and 6 inches. Areas south of I-90 will generally be less as the warm air results in a quicker transition to rain. Around Moses Lake, snow amounts will be trickier with areas such as Quincy and Soap Lake will hold on to colder air longer with 2 to 4 inches of snow forecasted but areas further south will see less than 1 inch. Winds: The strong east to southeast pressure gradient draped across the Pacific Northwest will result in gusty winds for the Cascades, the upper Columbia Basin, the Palouse, L-C Valley, and the Blues. Ridges in the Cascades have a 50 to 70 percent chance of wind gusts above 45 mph Tuesday night and early Wednesday. Particularly over the Cascades, a Blizzard Warning has been issued for the Stevens Pass area where strong winds and snow will result in significant visibility reductions along US 2. /vmt Thursday Night through Monday: A large closed low continues to spin off the WA/OR coast Thursday Night before moving northeast to just off Vancouver Island Friday into Saturday. The continued southwest flow will send additional rounds of precipitation into the region. The Thursday Night/Friday time frame has the potential to be especially wet with precipitable water values increasing to 200-250% of normal. Ensemble means are currently projecting around 0.40-1.00" of precipitation, mostly in the form of valley rain and mountain snow. The NBM is projecting snow levels of 3500-4500 feet along the East Slopes of the Cascades and up near the Canadian border while at 6000-7000 feet over SE Washington into the Central Panhandle Mountains. The increased snow levels, rain, and low to mid elevation snow melt will contribute to increased water into area rivers and streams. No flooding is forecast at this time but this will continue to be monitored. Over the weekend into early next week the trough finally begins to move inland. As it does so precipitation chances continue, with snow levels Sunday into Monday falling as low as 1500-2500 feet. JW && .AVIATION... 00Z TAFS: A conditionally unstable air mass will continue into Tuesday morning resulting in showers mainly over the Cascades, and eastern third of WA/N Idaho with the assistance of upslope flow. Most of these showers are scattered in nature with a PROB30 group utilized. Tonight as boundary layer winds shift to south- southeast a resurgence of stratus is expected over the northern valleys including KGEG/KSFF/KCOE with a mix of IFR/MVFR CIGS. As south-southeast boundary layer winds intensity further with a deep approaching system Tuesday afternoon that should help clear the stratus out of the Spokane/Coeur d`Alene areas. A band of snow will track across the region Tuesday Night into Wednesday morning with widespread lowland accumulations expected (except Lewiston). JW FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: HREF indicates around a 70% chance of CIGS dropping back down to IFR/MVFR for KGEG/KSFF overnight into Tuesday morning, with a 40% chance for KMWH starting near 15z Tue. JW ----------------------- Confidence descriptors: Low - Less than a 30 percent chance Moderate - 30 to 70 percent chance High - Greater than a 70 percent chance For additional probabilistic information for NWS Spokane airports, please refer to the Aviation Dashboard on our webpage: https:/www.weather.gov/otx/avndashboard && .PRELIMINARY POINT TEMPS/POPS... Spokane 26 37 29 40 31 41 / 20 20 60 90 60 40 Coeur d`Alene 26 37 26 39 31 42 / 50 30 30 80 80 40 Pullman 24 38 29 40 33 42 / 40 30 70 80 60 60 Lewiston 30 43 32 48 38 48 / 20 10 60 60 30 50 Colville 18 34 24 35 25 39 / 20 30 30 90 70 40 Sandpoint 24 34 22 35 29 39 / 60 50 20 100 90 50 Kellogg 26 35 23 39 34 41 / 70 40 20 90 90 70 Moses Lake 25 40 33 46 33 44 / 10 20 90 70 40 50 Wenatchee 28 36 30 39 33 40 / 10 30 100 60 20 40 Omak 24 35 29 38 31 42 / 10 20 80 90 40 30 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Winter Weather Advisory from midnight Tuesday night to 10 PM PST Wednesday for Northern Panhandle. Winter Weather Advisory from 10 PM Tuesday to 10 AM PST Wednesday for Coeur d`Alene Area-Idaho Palouse. Winter Weather Advisory until 6 PM PST this evening for Central Panhandle Mountains. WA...Winter Weather Advisory from midnight Tuesday night to 10 PM PST Wednesday for Northeast Mountains. Winter Weather Advisory from 10 PM Tuesday to 10 AM PST Wednesday for Spokane Area-Upper Columbia Basin-Washington Palouse. Winter Storm Warning from 10 PM Tuesday to 4 PM PST Wednesday for Okanogan Highlands-Okanogan Valley. Winter Storm Warning from 4 PM Tuesday to 10 AM PST Wednesday for Central Chelan County-Waterville Plateau-Wenatchee Area. Winter Storm Warning until 4 PM PST this afternoon for Western Chelan County. Blizzard Warning from 4 PM Tuesday to 10 AM PST Wednesday for Western Chelan County. Winter Storm Warning from 4 PM Tuesday to 4 PM PST Wednesday for Western Okanogan County. && $$
Area Forecast Discussion
National Weather Service Riverton WY
359 PM MST Mon Nov 18 2024 .KEY MESSAGES... - Snow and winds continue this afternoon and linger into the overnight hours. - Cooler Tuesday behind the cold front. - Warming trend through the rest of the week and into the weekend with some minor chances for western mountain snow. && .DISCUSSION... Issued at 1219 PM MST Mon Nov 18 2024 IR currently depicts a pair of classic comma cloud signatures, one across the plains and the other through the northern Rockies. There is a bit of a break with some dry air intrusion from the southwest for much of the CWA, but the next batch of snow is pushing into far western reaches of the area that will spread east throughout the afternoon and into the overnight hours. Several more inches possible for the higher terrain west of the Divide (60-70%) of 4 or more inches for the Tetons and Wyoming ranges, and 2 or more inches for the Gros Ventres and Salts. As this bulk of precipitation moves eastward, it looks to spread across the Bighorn Basin with some flurries before ramping on the upslope of the western Bighorns, where 40-50% probabilities for 6 or more inches progress for the higher elevations. Main impacts to the passes before spreading leeward to the I-25 corridor. Some minor accumulations possible (30-40%) of around an inch, but confidence is low with only the HRRR showing this amount with the ARW showing some but not as much. With breezy winds, this could impacts evening commutes around 5-7PM the best chance for this to occur. Otherwise, the main PVA anomaly will push east through the CWA overnight with some lingering flurries into the morning hours Tuesday around the Casper area with some light accumulations once again for western mountains that will not amount to much. The bulk of the now will be done before midnight tonight Monday. Tuesday will still see some breezy gradient winds in wake of the cold front where west to northerly winds could gust up to 25-30 mph for the main wind corridor areas and higher for the higher terrain of the passes (South Pass especially). Diminishing wind and clearing skies by late afternoon and into the overnight hours as Tuesday will be the coldest day of the week. Beyond that, expect ridging to build back in with increasing convergence aloft. A warming and mainly dry trend for most through the end of the week and over the weekend. However, possible mountain snow chances linger with the jet pattern coming straight in over the ridge from the gulf enriched Pacific northwest moisture. Nothing significant is indicated, just some welcomed light snow periodically for the higher terrain not expecting much if any at all into the lower valleys and basins. The next chance for a wider snow chance will come on Sunday and into early next week as the jet pushes further south around a deep trough off the west coast. Moisture looks to increase and the aforementioned trough to push east towards the CWA by Tuesday-Wednesday next week that could have holiday travel impacts. Stay tuned for updates in the coming days. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 359 PM MST Mon Nov 18 2024 The shortwave trough will exit the region tonight, with winter weather impacts starting to wane through the evening. However, resulting MVFR/IFR conditions, along with persistent mountain obscurations will continue at several terminals at least to start the period. At KJAC, light snow showers will continue to be possible through Tuesday morning, as lingering energy from the exiting trough will bring a few more waves of precipitation through the area. Most of the additional impacts after 07Z tonight will be over the mountains, with the valley being primarily shadowed, however, there was enough confidence to include a PROB30 for the overnight/morning snow showers. KCOD, KCPR, and KWRL terminals will see snow showers early in the period, with improving conditions for KCOD and KWRL by 03Z and at KCPR after 07Z. There is a slight chance (30%) for fog tomorrow morning, most notably for KBPI and KPNA. Have indicated this chance with a FEW002 group. Gusty winds should prevent fog development at other terminals. Winds will be generally through much of the period, with a lull for most terminals overnight. Winds will increase again by 14 to 16Z Tuesday for most terminals, with the rest of the terminals seeing winds increase with gusts to 20 to 25kts by 18Z or 19Z Tuesday. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 10 PM MST this evening for WYZ001-008-024. Winter Storm Warning until 10 PM MST this evening for WYZ012. && $$ DISCUSSION...Lowe AVIATION...Hensley
Area Forecast Discussion
National Weather Service Topeka KS
523 PM CST Mon Nov 18 2024 .KEY MESSAGES... - Showers continue through the evening with a low potential for isolated strong to severe storms this afternoon. - Wind advisory continues for much of the area into the evening hours with winds gusting at 45-50MPH. - Dry with cooler temperatures Tuesday through the end of the week. && .DISCUSSION... Issued at 231 PM CST Mon Nov 18 2024 The well-advertised system has evolved as expected to this point with widespread showers this morning giving way to some dry time and even some clearing this afternoon. The closed low across western Kansas is becoming negatively tilted and will continue to lift north- northeast across the area through the remainder of the day. The surface low currently resides over south central Kansas with a strong pressure gradient and low-level wind field leading to 40-50 MPH wind gusts for the eastern two-thirds of the forecast area. Winds will remain strong into the evening, although there could be a lull in advisory winds before a strong 50-60kt low-level jet moves overhead. The boundary layer will remain well mixed and stronger wind gusts are possible through at least 03z, possibly through 06z or so. As a result, the Wind Advisory has been expanded westward and extended through 9PM. Further expansion west and a later end time is possible; this will be monitored through the evening and updated as needed. In regards to the severe potential this afternoon, SPC mesoanalysis shows 0-3km MLCAPE increasing on the eastern edge of the surface low where a line of showers and storms has formed. As previously mentioned, low clouds have been scattering out with isolated breaks in the mid clouds allowing for full sunshine to return for a very short period of time. As the surface low tracks north-northeast through the rest of the day, dynamic cooling under the closed upper low and subtle heating ahead of the low will support weak destabilization. The HRRR and RAP are the most bullish, showing around 500 J/kg of SBCAPE, while other CAMs depict 100-250 J/kg. Shear values are impressive with effective shear of 50-70kts as the surface low approaches. Even with limited instability, it could be sufficient in the strongly sheared environment to support a few low- topped storms capable of producing damaging wind gusts and small hail. Also of note is the 50-100 J/kg of 0-3km CAPE which could allow a robust updraft to stretch the ambient surface vorticity near the surface low and produce a brief tornado. Forecast hodographs show some weakness in the low-level wind field (veer-back-veer profiles) which could limit the strength of updrafts. Overall, confidence in severe weather remains low and the window for any severe weather is limited to a few hour period, mainly 3-6PM. How the storms across southern Kansas evolve over the next few hours could give an indication as to their severity as they push into the area. Precipitation comes to an end late tonight with west-northwesterly winds ushering in cooler and drier air. Winds weaken Tuesday morning with another perturbation moving through during the afternoon and evening. Deep moisture is lacking and the only impact should be some increased cloud cover. Even cooler air builds in Wednesday through the end of the week with highs in the 40s and 50s. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 523 PM CST Mon Nov 18 2024 MVFR CIGS are expected along with brief periods of IFR cigs through 06Z, then become VFR by 08Z. Winds will be the main issue as the pressure gradient will remain tight through the night as winds shift from the south southeast to southwest early this evening, then westerly as the low pressure moves off to the northeast. Winds sustained near 20kts with gusts to near 40kts possible, then decreasing after 09Z-12Z to around 10kts from the west. && .TOP WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 9 PM CST this evening for KSZ011-KSZ012- KSZ022-KSZ023-KSZ024-KSZ026-KSZ035-KSZ036-KSZ037-KSZ038-KSZ039- KSZ040-KSZ054-KSZ055-KSZ056-KSZ058-KSZ059. && $$ DISCUSSION...Flanagan AVIATION...53
Area Forecast Discussion
National Weather Service Tulsa OK
620 PM CST Mon Nov 18 2024 ...New UPDATE... .KEY MESSAGES... Updated at 620 PM CST Mon Nov 18 2024 - Rain chances stay near 0% over the next 7 days. - Below average temperatures will occur Wednesday through Friday. - Freezing overnight low temperatures possible for locations north of I-40 Wednesday night through Friday night. && .UPDATE... Issued at 620 PM CST Mon Nov 18 2024 Forecast was updated to remove rain chances and to extend wind advisory near the KS border thru 03Z per HRRR guidance. A 983 mb surface low was analyzed just east of Concordia, KS, and a cold front extends south of the low over far eastern OK. Behind the front, winds got real gusty out of the southwest and some 40+mph gusts were observed north of I-44. The HRRR suggests there is still potential for a 40 mph gust thru 03Z near the KS border so the advisory was extended there and removed elsewhere. Updated products have been sent. Lacy && .SHORT TERM... (The rest of this afternoon and tonight) Issued at 213 PM CST Mon Nov 18 2024 Water vapor satellite imagery shows a very distinct negatively tilted mid-level trough moving over the Southern Plains early this afternoon. Associated surface cold front was analyzed across far eastern OK as of noon. Ahead of the front, a relatively weak and instability-limited QLCS/squall line, with trailing stratiform rain, continues to advance eastward, and is currently pushing across northwest AR. Strong wind gusts up to 50 mph will continue to be the main concern with squall line until it exits the forecast area. A few lingering showers and isolated thunderstorms may continue to develop closer to the center of the upper-low, mainly affecting portions of northeast OK, through the rest of the afternoon. Rainfall amounts since midnight have generally ranged from around half an inch to around two inches, with radar estimating isolated areas up to three inches in spots. Because rainfall amounts have generally been underachieving, especially in the Flood Watch area, and have therefore cancelled the Flood Watch early. Gusty winds have been the other headline of the day today. Since this morning, most locations have seen maximum wind gusts of at least 35 mph across the forecast area. Oklahoma Mesonet wind data show an apparent lull in wind speeds between the approaching cold front and the backside of the squall line. However, post-frontal winds will gust between 30-40 mph, locally higher, late this afternoon into this evening but should trend downward early-mid evening as the surface low quickly lifts northeastward and the pressure gradient loosens up. A Wind Advisory remains in effect for much of northeast OK and far northwest AR until 6 PM this evening. Weather conditions will greatly improve west-to-east late this afternoon and through this evening as the aforementioned mid-level trough continues to lift northeastward and drier air aloft quickly filters in. Skies will turn mostly clear by midnight tonight with winds trending near calm everywhere by sunrise Tuesday. Despite the cooler temperatures behind the front, overnight low temperatures will still be about 5 to 10 degrees below seasonal average, ranging from the mid-upper 40s to near 50 degrees in the AR River Valley. Mejia && .LONG TERM... (Tuesday through Monday) Issued at 213 PM CST Mon Nov 18 2024 Mostly quiet and rain-free weather will transpire through the long-term period beginning on Tuesday. Another vigorous mid/upper-level low will become closed-off late tonight into early Tuesday morning over the Northern Rockies and will move over the Northern Plains by midday Tuesday. As the upper-low continues to advance eastward across the northern-tier of the CONUS, it will allow a secondary surge of surface high pressure to move across the forecast area during the daytime Tuesday. Surface winds will shift from southwest early in the morning to north/northwest and increase by mid-late morning. Much cooler temperatures will follow Wednesday into Thursday, with overnight lows dropping into the 30s and 40s and daytime highs reaching the mid-upper 50s and lower 60s. A few locations near the OK/KS and MO/AR borders may reach or dip just below freezing both Tuesday night and again Wednesday night. Strong northwest flow aloft will develop over the Plains on the backside of the upper-low on Wednesday and yet another reinforcement of high pressure will move through the region during the daytime on Thursday, keeping temperatures below average through the remainder of the week. The coldest night of the period will occur on Thursday night into Friday morning with widespread freezing temperatures expected north of the I-40 corridor by daybreak Friday. Its possible that the urban-island- effect may prevent the Tulsa metro from dipping below freezing, but it will be a close call. A warming trend will occur beginning on Saturday as southerly winds make their return, assisting in pushing temperatures back above seasonal average through the upcoming weekend. Forecast uncertainty begins to increase late in the weekend into early next week, with another cold front possible Sunday night into Monday, which may drop temperatures closer average by Monday night. Mejia && .AVIATION... (00Z TAFS) Issued at 509 PM CST Mon Nov 18 2024 Main area of showers/isolated TSRA has shifted just east of the nwrn AR sites as of 23z, and ceilings have improved to VFR behind the exiting precipitation. Expect skies to gradually clear later this evening as mid level trough continues to pull away from the area to the northeast. Gusty swly wind nrn sites will subside by 06z, as pressure gradient relaxes as strong surface low over nrn KS translates into IA. Wind shift to the W and NW late Tuesday as cold front pushes into the area. && .PRELIMINARY POINT TEMPS/POPS... TUL 47 65 37 57 / 0 0 0 0 FSM 49 72 41 60 / 0 0 0 0 MLC 46 71 38 60 / 0 0 0 0 BVO 43 64 33 58 / 0 0 0 0 FYV 44 69 33 57 / 0 0 0 0 BYV 49 67 39 55 / 10 0 0 0 MKO 46 67 37 57 / 0 0 0 0 MIO 46 63 35 55 / 0 0 0 0 F10 45 67 36 58 / 0 0 0 0 HHW 46 70 41 60 / 0 0 0 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...Wind Advisory until 9 PM CST this evening for OKZ054>058. AR...None. && $$ UPDATE...30 SHORT TERM...67 LONG TERM....67 AVIATION...69