Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/15/22

National Weather Service Sioux Falls SD
518 PM CST Fri Jan 14 2022 .SHORT TERM...(This Evening through Saturday) Issued at 232 PM CST Fri Jan 14 2022 The winter storm will continue to wind down this evening. Warm advection to the east of the inverted trough will continue late this afternoon. As the low and upper wave continue to move southward, ascent will gradually weaken and accumulating snow will be ending by 00Z around KHON and K9V9 and by 06Z in all by the Hwy 20 corridor in northwestern Iowa. The heaviest snowfall amounts this evening will be in northwestern Iowa where up to 2 inches additional snow could fall. Over the remainder of the area additional snowfall will be less than an inch. Another concern will be winds which will be increasing as they back to the north behind the inverted trough. The strongest winds will be in south central South Dakota which will see gusts up to 45 mph through early evening. Winds will gust from 30-40 mph over the remainder of the area with the exception of areas east of the Buffalo Ridge in southwestern Minnesota where winds aloft are closer to 25 kts, so gusts should remain from 25 to 30 mph. With this mind, we will be canceling the winter weather advisory in south central South Dakota since the threat of any freezing drizzle has ended. We will also allow the advisory in the James Valley from Huron to Yankton to expire at 00Z since snowfall has been less than 2 inches and no additional freezing drizzle is expected. No other changes are planned for advisories or warnings at this time. With strong cold advection late this afternoon and tonight, temperatures will be falling the next 18 h. 925 mb temperatures down to -15 are expected over the area by 12Z Saturday. With fresh snow cover in southwestern MN, lows will be from 0 to -5. Elsewhere, lows will be in the single digits. The combination of wind and cold temperatures will produce wind chills from -10 to -20 east of the James River. Otherwise, clouds are expected to remain over much of the area overnight. There could be some clearing for a few hours in portions of southeastern South Dakota as a small area of clearing moves through overnight. Additional stratus is expected to follow behind this clear patch within a few hours such that skies should be mostly cloudy by Saturday morning. Many models, including the RAP and GFS, are slow to move these clouds out as high pressure results in a fairly strong inversion and light winds in the morning. As the high moves south of the area, southwesterly winds should help to erode the clouds and advect them to the northeast. Even if there is sun, with very cold air centered over MN, highs will be from 10 to 15 east of I-29. Warmer air associated with the southwest winds will allow temperatures to rise into the 20s to around 30 in the James and Missouri Valleys. .LONG TERM...(Saturday Night through Friday) Issued at 232 PM CST Fri Jan 14 2022 Surface ridge slides east of the forecast area Saturday evening, with increasing south-southwest flow at the surface and aloft. Model soundings showing 40-50kt aloft, roughly 1-2kft AGL in southwest MN. Given the higher elevation of the Buffalo Ridge, would anticipate some stronger wind gusts along and east of the Ridge Saturday night, and blended some higher-res wind guidance in with the NBM to bump up speeds in this area. The gusty winds will bring the potential for patchy blowing/drifting of the recent snowfall, primarily in these higher elevations. On a more widespread scale, the increasing winds along with an increase in higher level clouds through the night, should also result in rising temperatures through the latter half of the night. This will lead into a more mild day on Sunday, with temps climbing into the lower 40s west of the James River, where snowfall today has been quite limited. Meanwhile the areas east of I-29, where snowfall was heaviest, should be limited to highs right around freezing. A mid-upper level trough slides southeast across the northern Plains Sunday night, but upper ridging quickly builds back in, so the mild conditions are expected to continue through the early part of next week. This pattern breaks down midweek, as a stronger trough drives an arctic front south into the Plains. Especially given the recent snowfall in eastern portions of the forecast area, expect to see temperatures return to well below seasonal normals for a couple of days, with highs Wednesday-Thursday in the single digits east, and possibly even struggling to reach zero in some areas on Wednesday. Likewise, nighttime lows will be back below zero early Wednesday through Friday morning, with periods of wind chill readings in the teens and 20s below zero. The coldest air slides east of the forecast area by Friday, and we may see a brief moderation in temperatures before another surge of cold air pushes southward. However, models showing little consensus on timing of the weak upper ridging and trailing wave, so confidence in temperatures by Friday is on the low side. As far as precipitation chances, cannot completely rule out some light precip with any of the aforementioned waves, but the lack of model consistency in timing/strength precludes including any mention of precip in the mid-long range periods for now. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 514 PM CST Fri Jan 14 2022 Snow continues to settle southward this evening. We`re gradually seeing the back edge of snow move south of Highway 14 early this evening. 1/2 to 1 1/2 mile visibility will remain in snow, with gradually improving ceilings as dry air begins to filter southward. That said, anticipating at least a chance for MVFR ceilings to continue into Saturday morning, and they could linger well into the daytime hours. Northerly winds will relax through the night, becoming light and variable by mid-morning Saturday. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Winter Weather Advisory until 3 AM CST Saturday for SDZ070-071. Winter Storm Warning until midnight CST tonight for SDZ039-040- 056. Winter Weather Advisory until 6 PM CST this evening for SDZ038- 052>054-059>061-065-066-069. Winter Weather Advisory until midnight CST tonight for SDZ055- 062-067. MN...Winter Storm Warning until midnight CST tonight for MNZ071-072- 080-081-089-090-097-098. IA...Winter Weather Advisory until 3 AM CST Saturday for IAZ020-031. Winter Storm Warning until 3 AM CST Saturday for IAZ001>003- 012>014-021-022-032. NE...Winter Weather Advisory until 3 AM CST Saturday for NEZ013-014. && $$ SHORT TERM...Schumacher LONG TERM...JH AVIATION...Dux
Area Forecast Discussion
National Weather Service Wilmington NC
1002 PM EST Fri Jan 14 2022 .SYNOPSIS... High pressure will extend in from the north tonight. Low pressure approaching from the west late Saturday will deepen rapidly by Sunday bringing heavy rain that will start as a period of freezing rain away from the immediate coast. Breezy and cool on Monday behind this system with the remainder of the week remaining cool and dry. && .UPDATE... No big changes necessary from the ongoing forecast with this update. && .NEAR TERM /THROUGH SATURDAY/... Gusty NW winds on the back end of deepening low pressure system lifting off to the NE will diminish into this evening as the gradient relaxes. High pressure over Canada will extend down into the Carolinas as low pressure system develops and dives down from the Midwest toward the Gulf coast states tonight into Saturday. This will kick winds around from the N to NE becoming more on shore as winds aloft increase out of the SW ahead of approaching system. Moisture will increase through the column with scattered mid to high clouds tonight increasing and thickening through the day on Saturday. Overall, shallow cool air will remain in place with fairly decent radiational cooling, but increasing mid to high clouds will increase and should help to level off temps inland toward morning. Should see lows near freezing with highs tomorrow struggling to get through the 40s inland in thickening clouds and continued cold air in place. Temps near the coast should reach 50 and slightly warmer over coastal SC. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... Temperatures on Saturday night should drop rapidly after sunset due to the building high pressure and cold air advection. Along with the cold air advection, most of the area will see dew points drop into the lower 20s (a few upper teens possible along our northern CWA border). This dry air advection will be important to monitor as mid- level and low-level moisture spreads across the area through 03-06Z. Should start to see light radar returns between 03Z-06Z during the early development of isentropic upglide. It is unlikely that any precip will make it to the ground at this stage, but should be the first step in saturation from south to north. Temperatures quickly dropping as virga saturates the area, with the near-surface layer dropping to below freezing across much of the CWA. Our first observed precip should start in the form of freezing rain away from the immediate coast. Points along the coast could see a brief period of freezing rain, but we expect this quickly to become all rain and confidence in this occurring is low (i.e. all rain likely even from onset). Models continue to vary greatly on the duration of freezing rain across the area. The GFS continues to be the warmer solution while other major global models are slightly further south with more cold air available at the start of the event. Soundings do support this given the dry air available and timing of precip arrival. High pressure to the north also leaves some lingering questions. This feature has been wavering in location and intensity and a slight shift southward, as in the ECMWF/CMC, would lead to better cold/dry air advection, potentially producing more ice accumulation along and west of I-95. As we get closer to the event, we are finally starting to see some of our high-res model guidance pick up on system evolution. Given its track-record with good handling of cold air damming, the NAM is being heavily considered for this event. I have blended some of its temperatures and dew points in this forecast update and this has reflected a slight shift southward in overall freezing rain potential. The vertical resolution of the NAM and HRRR are likely to handle the physical low-level mechanisms that could prolong periods of freezing rain. It is prudent to note that both show a stronger low-level jet overtaking the area during the day with a faster low overall. For now the forecast reflects another southward shift with a wider coverage of freezing rain to start and slow regression of the freezing line through late Sunday morning, clearing the CWA by early Sunday afternoon. This would produce around a quarter of an inch of ice accrual along the I-95 corridor. Again, subtle changes could lead to slightly larger or smaller amounts, bullseye still well west of our area. As the system transitions to all rain on Sunday afternoon, the center of the low is likely to track near the Cape Fear region, either just offshore or just inland. It is likely that a portion of the area will exist within the warm sector of the deepening low. Within this area, we could have our strongest land-based wind speeds. Gusts of up to 35 mph are possible along the immediate coastline with the NC coast having a shot at slightly higher wind gusts. This could produce some minor impacts, especially with the rain-soaked soils (e.g. branches or trees down, isolated power outages, and misplaced outdoor items left unsecured). Rain could be heavy at times and could create some travel headaches in itself: reduced visibility, ponding on roadways, and slick surfaces in general could be enough to cause some minor impacts. Current storm total QPF shows between 2-3 inches of rain along the coast and 1-2 inches of rain inland. It is important to mention that this too will change with the track and observed p-type on Sunday. While this will be welcomed for most of us, some low-lying and poor drainage areas are likely to have some minor flooding issues throughout the day. Rain is likely to end across the area from south to north on Sunday night. Winds on the back side of the system will continue to be worthy of monitoring with some of our coastal areas seeing ongoing gusts up to 30-35 mph late Sunday night into early Monday morning. This is likely to be aided by a tongue of dry air progressing within the hook of the deepening low by sunrise. The lack of moisture on the back side of this system will also rob us of seeing any lingering flurries on Sunday night or Monday morning. && .LONG TERM /MONDAY THROUGH FRIDAY/... Low pressure moves away from the coast late Monday, remaining breezy late in the day as high pressure builds into the area. Temperatures on Monday remaining below normal with cold-advecting NW wind. Highs only in the mid or upper 40s. Cold overnight Monday into Tuesday morning with lows in the mid and upper 20s. High pressure will bring a quiet Tuesday and below-normal temperatures. High pressure allows for good radiational cooling Tuesday night into Wednesday morning, lows again in the upper 20s to around freezing. Sunshine is able to really have an impact on Wednesday high temperatures under clear skies. Highs back to normal and could potentially rebound to a couple degrees above normal. Cold front will move through the area on Thursday and could bring some precip as it moves through. Much colder air should follow with strong Canadian high pressure moving into the central US. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... VFR through the 00Z TAF period. Just some high clouds tonight with very light N/NW wind potentially becoming calm. Light NE winds can be expected as we begin to mix on Saturday, up to 5 to 10 kts. Very dry air will keep fog potential low Saturday morning, with clouds starting to thicken through the day ahead of the next low pressure system. Extended Outlook...Mostly VFR outside of a high potential for IFR Saturday night through Sunday with a developing low pressure system to bring RA and FZRA to the area. && .MARINE... Through Saturday...Lingering gusts to 25 kts over waters N and E of Cape Fear will come to an end this evening as exiting low moves farther off to the northeast, allowing gradient to relax. Offshore flow keeping highest seas well offshore with 2 to 4 ft most waters and down less than 2 ft over nearshore SC waters. A minimal easterly swell will mix in and become more dominant as winds drop into Sat. Northwest winds will gradually veer to northeast overnight. Speeds dip under 15 kt around midnight and continue trending down through the early morning hours. Saturday night through Tuesday...Rapid deterioration of conditions is expected late Saturday night ahead of a surface low over the southeastern US. Deepening low pressure will lead to a quick increase of the gradient winds on Saturday night through Sunday morning. Expecting sustained winds 25-30 knots, gusts 35-40 knots through the majority of the day on Sunday. Gale conditions are likely to develop with this system and a Gale Watch has been issued for all of our nearshore coastal waters. Conditions will be at their worst Sunday afternoon and through the overnight period. Surface low will begin to exit the region by Monday morning. Seas 6-10 feet late Sunday as the center of this storm passes near the coastline. Conditions will improve during the day on Monday and Monday night. Returning to near normal by Tuesday with offshore winds 10-15 knots and seas 3-5 feet and decreasing. Clear and mostly calm on Wednesday with southerly flow increasing ahead of a cold front later in the week. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Winter Storm Watch from late Saturday night through Sunday afternoon for SCZ017-023-024-032-033. NC...Winter Storm Watch from late Saturday night through Sunday afternoon for NCZ087-096. MARINE...Gale Watch from Sunday morning through Monday morning for AMZ250-252-254-256. && $$ SYNOPSIS...ILM UPDATE...MAS NEAR TERM...RGZ SHORT TERM...21 LONG TERM...21 AVIATION...MAS MARINE...RGZ/21
Area Forecast Discussion
National Weather Service Jackson MS
950 PM CST Fri Jan 14 2022 .UPDATE... Updated for evening discussion. && .DISCUSSION... Plenty of high clouds streaming into the region on satellite imagery this evening. For the most part, clouds remain above 12kft, but some of those are getting picked up on radar. Any sprinkles that might be coming out of those clouds would never make it to the ground given the deep dry boundary layer on the 00z JAN sounding. Not much in the way of updates anticipated for the overnight. Forecast on track for increasing clouds and lows mainly in the 40s. Some showers may be encroaching on the Mississippi Delta just before dawn in advance of the next storm system. Prior discussion below: Tonight through Tomorrow... In the near-term, weather will remain quiet. Shortwave ridging over our region has kept weather dry today, but the approaching upper- level shortwave trough can be seen on water vapor satellite imagery diving southward from the Northern High Plains this afternoon. High clouds associated with this system are moving across our forecast area, but increased low clouds and rain chances don`t arrive until tomorrow morning time frame. As the trough dives southward, a deepening low pressure system will close off from the flow aloft, and the surface low pressure center will slide east from Texas across Louisiana and Mississippi. The surface cold front should enter northeast LA around sunrise tomorrow and pivot across our forecast area through the afternoon hours. Forcing along the front and enhanced lift through the upper-levels will support a good line of showers as the front moves east. Some elevated instability will also support a little thunder mixed in with this daytime activity. Temperatures will warm into the mid 60s ahead of the cold front in our southern areas, while temperatures in the Delta will warm only to a more mild mid-50s range. Then attention quickly turns to our winter weather potential. /NF/ Saturday night through next Thursday... Sat night-Sun: Main focus remains on winter weather event likely Sun. Cold core will continue diving to the E-SE, with center of cold core over the central Plains by Sat morn, ArkLaTex by Sat aftn & MS River to I-55 corridor by midnight Sun. This highly dynamic system will bring a TROWL & wrap around moisture, broad sfc low pressure/baroclinic zone centered off to the E-SE by Sunday. Increasing isentropic ascent/convergence into strong deformation zone & conditional symmetric instability (CSI) will be present. Strong ascent will keep broad deformation axis of rain changing over to snow generally along & W of MS River by midnight, W of I-55 before daybreak & E of I-55 through Sun aftn, with some lingering light snow psbl in E-NE MS into early Sun aftn. There remains uncertainty on how much WAA in the TROWL will occur to see some warmer low-level temps & rain lingering longer. There has been a continual S trend to the center of the strong cold core in recent global guid consensus. Strong dynamic cooling underneath & some heavier QPF/snow are possible in areas of temps hovering right around or just above freezing. Low-level thermal warmth less than 1000ft could keep it just rain/snow & less precip type issues. Heavier bands will remain difficult to pin down. However, there remains enough confidence that areas in the N-N central MS, far NE LA & SE AR remains probable for accumulating snow & some potential of some approaching or possibly exceeding winter storm criteria. HRRR has some small trends with some stronger WAA, less totals along & E of the Natchez Trace. 12Z runs indicate some higher end potential to easily exceed winter storm criteria. For now, with limited probs > 2 inches into our NW, main adjustments were to adjust the "Limited" graphic further S closer to the I-20 corridor & SW & somewhat to the E along the Hwy 82 corridor just W of the AL state line. Lows that morning will only peak near or just above freezing, with best snowfall potential areas only falling near the freezing mark, then only climbing into the mid- upper 30s in E to low 40s in SW. Leaned towards raw blend of guid for highs. In addition, TROWL situations & with strong gradient, efficient gradient winds could approach +30-35mph at times, with some sustained near wind advisory possible Sunday. This could bring visibilities down & create additional travel difficulties. With potential for heavy wet snow banding at times, combined with gusty gradient winds, some power outages could be possible as well. Held off for now in the HWO, but a "Limited" gradient wind will likely be needed. Lastly, some areas in E-NE MS could see some convective rain prior, with some QPF totals in excess of 1-2 inches. For now, something to monitor but will hold off in the HWO. Next week (Mon-Thurs)... Mon: As sfc high builds off to the W & clouds clear & winds lighten, efficient rad cooling is psbl with lows falling near or below freezing. This will especially be the case in any areas of snowpack. This could cause any lingering snow on elevated sfc, including bridges or overpasses, & could keep slick travel conditions through early Mon morning, mainly through 7-8AM. Highs will warm & some of that will go into melting of the lingering snow, so high temp fcst could be in flux to start the week. Highs will generally be near climo in the upper 40s in NE to low-mid 50s in the S. Tues-Thurs...As sfc high builds E & broad blocking pattern persists, expect any quick zonal flow to give way to another amplifying mean trough out of the NW by late week. This will help some increasing WAA & temps moderating above climo into the low 60s N to low 70s S by mid-week, before rain & some storm chances move through by Wed aftn & move out through Thurs. Highs will fall back near climo into the low-mid 40s N to mid 50s S. /DC/ && .AVIATION... 00Z TAF discussion: VFR conditions overnight with light southeasterly winds. Conditions will start to deteriorate tomorrow mid morning as a cold front move into the region ahead of the next storm system. Models persist on dropping to MVFR conditions around midday with showers...and then to IFR cigs and/or vis in most locations before sunset. Towards the end of the fcst pd and behind the front, the winds become more westerly and brisk, gusting to 20-25kts. && .PRELIMINARY POINT TEMPS/POPS... Jackson 47 60 33 39 / 4 92 63 16 Meridian 43 60 35 38 / 3 95 83 37 Vicksburg 49 59 33 43 / 7 82 54 8 Hattiesburg 44 65 34 41 / 1 95 46 6 Natchez 51 61 33 45 / 6 79 33 3 Greenville 47 55 31 40 / 11 89 80 16 Greenwood 47 56 32 38 / 8 93 83 46 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ HJS
Area Forecast Discussion
National Weather Service New Orleans LA
938 PM CST Fri Jan 14 2022 .EVENING UPDATE...No adjustments made to tonight`s forecast but we did adjust tomorrow and tomorrow nights forecast. Timing is still similar with tomorrow`s activity. First round of convection appears to be associated with waa possibly a warm front sliding north. One thing to watch will be how far east that can move and how fast. If that activity is slower to move out or is anchored closer to the coast then we will struggle to recover and the amount of convection that will be associated with the cold front tomorrow afternoon will be far lower than currently forecasting. On the other hand of that activity moves to the east and northeast a little faster it will allow for better destabilization and perhaps a few strong storms...can`t rule out one or two severe but the most likely risk of strong/severe weather will be quick weak tornadoes early in the afternoon. These could very well develop on showers, so yeah no lighting with some of these is possible. The best directional shear will be from morning and into the early afternoon but winds quickly become unidirectional mid afternoon and ahead of the cold front. As for Winter Weather, the key will be the path of the mid level low. The trend had been a little south so we shall see if that continues. If the low can get a touch farther south then light snow would be possible in southwest MS, not just flurries. Flurries do look likely in southwest MS and the adjacent LA parishes but could even be possible down to I-12. The next thing to watch which we wont see till tomorrow evening will be how much moisture can wrap around it. All indications suggest there could be a rather decent amount of moisture wrapping around, probably due to what looks like an impressive TROWAL ahead of it across MS and AL. We did bring flurries a little farther south with this update but holding off on any real accumulating snow at this time. Grids and zones will be out shortly. One thing to mention...confidence is low and there is a chance that Winter weather could over preform. The key again is that wrap around moisture. Numerous forecast soundings over the last 12-18 hours has indicated there could be a brief window of rather decent waa/lift in the dendritic zone. At the same time the column looks pretty well saturated from the sfc and perhaps all the way to h7. If, and this is a big IF, that happens we could be see a window of moderate snow possibly leading to some light accumulations. If that happens it would most likely be in southwest MS. At this time the potential for any meaningful snow is rather low in SELA and coastal MS but southwest MS will need to be monitored. This could make travel along I-55 from the LA/MS border north through the state rather dangerous to drive on. /CAB/ .AVIATION...06z TAF Package...VFR conditions will likely continue through the night but shortly after 12z look for conditions to begin to deteriorate with most terminals likely seeing MVFR conditions near 18z and then IFR conditions later in the afternoon and early evening. Winds will also begin to pick up tomorrow out of the southwest but the strongest winds will likely hold off until later into the evening behind the cold front and out of the northwest. Strongest winds will as always be along the southshore of Lake Pontchartrain and perhaps along the MS coast. /CAB/ PREV DISCUSSION... /issued 406 PM CST Fri Jan 14 2022/ NEAR TERM (This evening and Tonight)... Splitting up the short-range discussion between the near term and weekend system to allow better focus on both. For a detailed analysis on the weekend system divided by potential hazard, scroll down. As far as the near term goes, all is quiet. Continuing to see thin upper-level cirrus advecting in from the northwest within a pocket of H2 to H3 moisture ahead of an amplifying positive tilt trough pushing south along the eastern Rockies/central Plains. Upper-level clouds will continue tonight, becoming thicker with time into daybreak Saturday. No major adjustments performed to minimum temperatures, just a slight nudge down for drainage basins as winds could remain light (just enough) early Saturday morning. Based on trends this afternoon, also slightly slowed the increase in dewpoints as there appears there may be a slight lag due to southeasterly winds persisting overnight. KLG WEEKEND SYSTEM (Saturday morning through Sunday Night)... Synopsis... A shortwave trough axis originating from the PacNW continues to phase with a lead shortwave trough across the northern Plains, diving southeast into central US. The PacNW trough/remnant energy aloft and evolution of the upstream ridge axis building east into the northern Plains will act to enhance/deepen the trough axis, eventually closing off as an upper-level low diving southeast into the Arklatex Region Saturday afternoon and evening. NAEFS Mean Geopotential height and Climatology Percentiles analyzed per layer reveals an overall extremely low height anomaly associated with this deep 5460m H5 center, progressing east just barely to the north of the area late Saturday and into Sunday. Meanwhile at the surface, an elongated surface trough axis extending from central TX, northeast into MO will progress east along a strengthening baroclinic zone/frontal boundary. We are already seeing surface low cyclogenesis along this trough over northern Texas, with this low expected to progress east just to the north of the CWA and an attendant strong cold front swinging through the northern Gulf coast Saturday through Sunday. Upper-low position and orientation does not typically favor a severe weather or notable winter weather risk for our location, however each contain a non-zero chance. Each potential hazard is discussed in more detail below. Convection... Any threat of strong or severe storms will be hard to come by with the lack of deep Gulf moist return flow. Seems like recent frontal boundaries over the past weeks have pressed dry, continental air deep into the Gulf with very little opportunity for us to build back deep enough moisture ahead of the eastward surging low to our north. Keeping this in mind, there are some features to mention. There is some weak reflection of a subtle impulse riding along strengthening WSW to ENE flow aloft, which CAMs depict as a cluster of showers mid to late Saturday morning across the area, with the potential for deeper convection across coastal SE LA (within somewhat better Gulf moisture/instability). Can`t rule out a strong storm or two over marine areas generally confined to what could be a weak warm front surging north. Anything further north would likely be elevated, with barely any thunder to come by. Stronger forcing arrives just barely with the frontal boundary, entering our NW CWA late Saturday morning/early afternoon. Noticing CAMs have been trending slightly higher with surface dewpoints (low 60 Td`s) to the north ahead of this boundary matched with stronger low to mid-level winds. However, should coastal convection/stratiform precip be more widespread early on, this could starve necessary deep moisture to support convection along the boundary. Recent synoptic hour 18Z run of the HRRR shows very little activity along the front early in the afternoon, but intensifying dynamic ascent attempts to overcome by producing individual cells near or north of I-10/12. Modest shear within limited instability... taking into consideration so many struggles here... really going to be difficult to get any severe weather, but the two areas to monitor may be for coastal convection earlier on, and for any shallow cells that could try to develop along or near the front within a thin zone of combined better forcing and thin, skinny return of MLCAPE ~250-700J/kg meaning, will advertise a non-zero isolated tornado risk. What is left of this threat fades into nothing as we lose sunlight later into the afternoon. Winds... Largest concern for winds will be primarily associated with CAA on the back side of the front. Continuing to confidently introduce the 90th percentile NBM into the forecast for all areas.. with a slight nudge even above for marine zones. This will present gale conditions beginning Saturday evening, lasting through Sunday afternoon. Per our local Wind Advisory criteria, even pulling sustained winds well above deterministic guidance, still am coming in shy of advisory highlights. This may change, but due to low confidence, will let subsequent shifts re-analyze and issue should need be. Areas with the strongest winds will likely be along the southshore and parts of coastal SE LA, especially across marine areas and any north-facing shorelines from Saturday night through the day on Sunday, finally tapering off as the system pulls away and attendant SLP weakens with surface high building in from the west Sunday night. Temperatures... No question about it, temperatures will drop like a rock following the front. Aimed at the lower end of NBM ensemble guidance for lows Sunday morning, but not too cold as winds will remain very much elevated with cloud cover. Did take a close look at the possibility of clouds lingering during the day on Sunday, which is looking more likely with plenty of wrap-around 925mb moisture behind the surface low. Given persistent CAA and low-level stratus/stratocu... highs will struggle to reach out of the mid to upper 40`s. Felt more confident as this has been an ongoing trend, but cloud thickness will not be deep only a few thousand feet thick meaning, if clouds break up early or erode west to east earlier than anticipated, there could be further adjustments but for now, confidence is high enough to aim lower than blended guidance. As winds taper going into Monday morning and clouds break up/pull out of the area, still anticipating Monday morning to be the coldest morning due to strong radiational cooling promoted by nearby surface high pressure. Again, well below the NBM placing many areas in the low 30`s to some upper 20`s which will bring widespread frost. Southshore/NOLA and surrounding areas still looking likely in the mid 30`s even with this colder nudge. KLG Winter Weather... Since it has been a bit of a discussion lately, and since we rarely get to analyze the potential for winter weather here... sure let`s analyze it! As the low presses east, as mentioned with plenty of wrap around low-level moisture sliding behind the low (prominent TROWAL looking at 700 and 500mb ThetaE). This has been a very interesting trend closely looking at the CAMs trying to pull precipitation deeper into our CWA (12 and 18Z HRRR really standing out). Model soundings for SW MS illustrate enough deep moisture within the DGZ pulling atleast into parts of the northern Florida parishes. Temperatures will be falling, but question will be how fast will they fall and how far will they go. Even with the re-adjustment in colder temperatures daybreak Sunday, we generally see temperatures in the 34-37 degree range for northern areas. With dynamic lift in place (850-500mb PVA), combined with DGZ/ice crystal growth all within wrap around low- level moisture/TROWAL... that could very well be enough to get some wet snowflakes to the surface, perhaps mixed with rain in some spots further south. This may be a brief window only for a few hours spanning somewhere between 09 to 15Z, with the greater potential along the northern parts of the Florida Parishes and SW MS. For now, have introduced Rain/Snow for parts of SW MS to flurries just barely farther south (lower confidence). Yes, this does have the potential to over (or under) perform... so confidence is low at this time and am NOT advertising measurable accumulations at this time. However, a light dusting could be possible especially on elevated surfaces. This will be something we will have to closely monitor should anything change as the system develops and evolves. KLG LONG TERM (Monday through Thursday)... After a very cold morning, we warm up into the upper 50`s to nearing 60 for a few. This moderation trend persists into mid-week before the next cold front swings through late Wednesday/early Thursday. Large disagreement in late-week guidance at this time with a large ensemble spread in temperatures, likely due to frontal speed and where it may stall near the area. But, not going to get too caught into details this far out in advance. Will take a closer look once guidance aligns better after we pass this weekend system. KLG AVIATION (18Z TAF DISCUSSION)... VFR conditions will prevail this afternoon, evening and portions of overnight tonight with only patchy upper-level cirrus and light surface winds expected. Low clouds build back in early Saturday morning as return southeasterly flow develops leading to primarily MVFR flight categories beyond after daybreak. Light showers will increase in coverage across coastal SE LA early to mid-morning Saturday, with a strong cold front swinging west to east across the area thereafter Saturday afternoon and evening. At this time, mentioning SHRA ahead of the front to a few western and central terminals where guidance is in better agreement. There is the potential for TSRA for central and southern terminals after 18Z, but chances remain low. Will revisit this in subsequent TAF updates. KLG MARINE... Light winds and calm wave/seas will continue this evening. Winds will steadily increase out of the south during the morning hours on Saturday. Showers and a few strong storms may be possible mid to late morning Saturday, before a strong cold front swings through Saturday afternoon and evening. Behind this front, strong winds will be building to gale force, with all Gale Watch headlines now upgraded to Gale Warning. Additionally, waves/seas will be quickly building behind the front, reaching 10-15ft+ for outer 20-60nm zones to 3-6ft for lakes/sounds. Gale Warning headlines will remain in effect through Sunday evening, likely being transitioned into a Small Craft Advisory to follow due to linger winds and waves/seas. Thereafter, high pressure builds into the region with conditions becoming more calm. The next front will be possible mid to late-week either passing through coastal waters or stalling near or potentially south of marine zones. KLG && .PRELIMINARY POINT TEMPS/POPS... MCB 48 64 33 43 / 0 80 30 10 BTR 51 66 35 48 / 0 70 10 0 ASD 48 70 36 46 / 0 90 40 0 MSY 54 71 38 48 / 0 90 20 0 GPT 50 68 36 46 / 0 90 60 10 PQL 47 70 35 45 / 0 90 70 10 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...Small Craft Advisory from noon to 6 PM CST Saturday for GMZ530- 532-534-536-538-550-552-555-557-570-572-575-577. Gale Warning from 6 PM Saturday to 6 PM CST Sunday for GMZ530- 532-534-536-538-550-552-555-557-570-572-575-577. MS...None. GM...Small Craft Advisory from noon to 6 PM CST Saturday for GMZ532- 534-536-538-550-552-555-557-570-572-575-577. Gale Warning from 6 PM Saturday to 6 PM CST Sunday for GMZ532- 534-536-538-550-552-555-557-570-572-575-577. && $$
Area Forecast Discussion
National Weather Service Louisville KY
925 PM EST Fri Jan 14 2022 .Forecast Update... Issued at 924 PM EST Fri Jan 14 2022 Evening satellite and observations reveal mostly cloudy skies across southern Indiana and much of northern Kentucky with low overcast hanging on strong. Further south over southern KY skies were clear to partly cloudy with some light mist/fog being reported. Temperatures across the region were generally in the lower 30s, though some lower-mid 40s were noted over far southwestern KY. Current forecast remains on track for the overnight period. We will continue to see clouds increase across the region. The clouds will likely keep temperatures in the lower 30s for much of the night. As well advertised weekend system approaches off to the west, still think we`ll have some light snow showers and/or flurries develop across southwest Indiana and the western part of KY (mainly west of I-65). Amounts still look to be very light and with temps staying at or above freezing, the impacts here still look limited at this time. As for the rest of the forecast, no headline changes will be made this evening. The afternoon data from the NAM, HRRR, and Canadian GEM continue to be on the south edge of the model guidance keeping much of the region dry on Saturday and Saturday night before bringing wintry weather back to east-central and southeastern KY on Sunday. The 18Z GFS and the 18Z Euro runs continued to support our wintry mess within the current watch area for Sunday. Looking at the 00Z upper air obs and comparing them to the earlier GFS/Euro runs, the mid-level heights from the northern Plains down through the east-central Plains remain higher than the GFS forecast, meaning that the ridge out to our west remains a little stronger, or, it could also mean that the lead wave is weaker than forecast. The overall speed of the system seems to be on track, perhaps ever so slightly slower. However, if the lead wave is actually a bit weaker, I would suspect that the 00Z models may drift a bit back to the north with their runs this evening. This is already evident in the 00Z HRRR runs with a more northward precipitation shield being depicted across TN and into southern KY. The snow amounts from the HRRR are lower, likely due to snow accumulation loss to expected mixed precipitation cutting into those totals. I suspect we`ll see a northward trend in the NAM guidance as well, but I also suspect that we may see a bit more mixed precipitation initially with the band lifting into east-central and SE KY which may cut into snow totals. Overall, we should cool fairly rapidly late Sunday afternoon changing everything back to snow. The westward expansion of the precipitation shield as it comes northward remains problematic as there are indications it could go back as far as the I-65 corridor. Given the current spread in the guidance and the lack of new 00Z guidance, confidence remains limited and no headline changes will be made with this evening`s update. && .Short Term...(This evening through Sunday Night) Issued at 330 PM EST Fri Jan 14 2022 ...Winter Storm Potential Still Carries Much Uncertainty... ...No Changes To Current Headlines Planned At This Time... Currently, our region is bisected by a deck of stratus that has been slow to erode today. South central KY is under clear skies with temps in the 40s. Even seeing some upper 40s near the KY/TN border. Farther north, we are seeing some signs of the deck eroding across southern IN and north central KY, however by the time these clouds give way we will likely be past any chance to "warm". So, have gone pretty pessimistic with the temps heading into this evening/night. Current values are in the mid to upper 30s under the persistent cloud deck. As we move into tonight, temps are expected to fall into the upper 20s and low 30s under a steady NE surface wind/cool advection. We`ll see increasing upper sky cover tonight ahead of the clipper that will be diving into the mid Mississippi River Valley. However, any light precipitation expected with a lead band of moisture is likely to hold off until early to mid Saturday now. No changes with that expected snowfall (perhaps a rain/snow mix with marginal low level temps) as only a dusting to half an inch at most west of I-65 would be expected. Models have been trying to warm temps up into the mid and upper 30s for much of the area on Saturday, however given steady NE surface flow and heavy cloud cover those temps might be too aggressive. We might very stay confined to the low to mid 30s during that time. So, any precipitation (not much expected) will have a chance to be rain/snow. Little to no accum expected. Saturday night now looks mostly dry across our area as the much anticipated storm system closes off over the lower Mississippi River Valley. The farther south solution that has been trending in the models is also translating to a slower onset time. So, Saturday night should now be mostly dry outside of areas right along the KY/TN border. Snow will be the main p-type, with a possible mix of sleet at times, thanks to a marginal warm nose hovering right around the 0 C line through a fairly deep layer above the surface. Surface temps will be at or just below freezing in this area, so some light accums around 1 to 2 inches along the state line are possible by sunrise Sunday. The main show is then expected mainly along and south of the Parkways from around sunrise through around Midnight EST on Sunday as the storm traverses the Gulf Coast states and heads up the Appalachian spine to the mid Atlantic. We`ll be in a favorable region of the storm such that mid level deformation will have some residence time over our southern and eastern CWA, more specifically the general Winter Storm Watch area. Here, look for widespread line snowfall, with the potential to develop a moderate to occasionally heavy band of snow thanks to a frontogenetical component producing good lift through a saturated DGZ. Here, 1 to 2" per hour rates will be possible, which is most likely to occur somewhere along and southeast of a Scottsville, to Campbellsville, to Lexington, to Carlisle line. In the Watch area, expect a wide range of 3 to 6 inch amounts possible, however a locally higher/narrower band of 6 to 8" is possible, likely somewhere closer to the I-75 corridor. Outside of the watch area, expect only light snow, although it will persist for a good portion of Sunday into Sunday evening. So, a broad area of 1 to 3" is still possible south of the Ohio River. Areas closer to the Watch will have the better chance at the higher totals, and will likely need to be in a Winter Weather Advisory should the current forecast hold. Across southern Indiana, very little if any snow is expected with this system. The event ends late Sunday night into Monday morning across our far east. Confidence: Overall confidence remains quite low with this system due to several factors. 1.) the complexity and evolution of the system has been giving forecast models trouble, and while overall trends are noted, run to run inconsistencies are hurting confidence. For instance, the 18z HRRR is a complete miss and dry for our entire CWA, while other models show a significant event still occurring in the Watch area. Even ensemble members still show a pretty wide spread at this point in the game. 2.) Precipitation type is a bit more in question with this system given the aforementioned marginal warm nose across our south and east. This is also where our highest totals/larges QPF reside so any mixes in p-type could really put a dent in expected snow totals. Perhaps confidence will improve if a more clear trend begins to show itself, but for now expect that confidence will remain low if we don`t get good model consistency or some clarity on the potential warm nose across the SE CWA where the Watch is. The Watch: At this time, plan no changes to the current headline other than to freshen up the wording. It looks pretty well placed and give a continued steady SE trend in the models, it could even be overdone if that trend continues. It should be noted that if the current forecast holds areas outside of the Watch will likely still need to be in an Advisory with lesser totals. However, since the main event isn`t until Sunday we`ll still have time to make that decision. Could This Storm Still Be Significant? Absolutely. Right now, the current sentiment is a little more pessimistic due to recent model runs trending drier, however a slight shift in the track, or if the deformation band really does get going could still bring some higher totals. One thing worth noting is that even though the models are struggling with p-type, a healthy snow band could easily overcome any marginal thermal profile to keep it all heavy, wet snow. Could This Storm Be A Bust? Yep. In fact, some of the shorter term/higher res models coming in this afternoon are keeping our entire area dry and storm free. It is entirely possible that the current Winter Storm Watch could be dropped with little fanfare if the latest trends hold in the coming shifts. Bottom Line: Pay attention to the latest forecasts through this holiday weekend as we gain more confidence. Sometimes it is easy to be confident in a storm. Other times it is not due to the complexity of how the storm forms, and/or interacts with other atmospheric disturbances. This could still go either way. .Long Term...(Monday Morning through Friday) Issued at 245 PM EST Fri Jan 14 2022 Long term period begins Monday morning, where the primary winter low will be pushing up the Appalachians and impacting the northeast. A mid-level vort max associated with the thermal shortwave will track across the region, which looks to spark an additional light round of snow for areas east of I-65 Monday morning. Flurries to a very light dusting is possible, with the highest 6-hr snow accumulation (a few tenths) forecast for our Bluegrass region. With northwesterly flow taking over, temperatures will struggle to get out of the 30s for Monday. Drier air and low level ridging sets up for Tuesday, with a broad sfc high located across the Gulf Coast. We`ll see cloud cover decrease through the day as temperatures return to near normal (generally in the 40s). It`s not until Wednesday that the forecast introduces our next shot at wet weather. A shortwave will pivot across the northern US border, bringing the associated sfc low across the Great Lakes region. A trailing cold front will connect to a secondary low over the ArkLaTex region. Temperatures ahead of the front look to be above freezing, resulting in light rain showers for our region. Some model spread on timing limits confidence, but cold air will quickly rush in behind the frontal passage. Lingering precip just along or behind the front may mix with colder air, resulting in a possibility of light snow Wednesday evening and night. && .Aviation...(00Z TAF Issuance) Issued at 616 PM EST Fri Jan 13 2022 IMPACTS: - MVFR/IFR cigs this evening - Some snow flurries and light snow showers possible overnight DISCUSSION: MVFR cigs are in place at KSDF/KLEX and will likely become prevailing at KHNB this evening. VFR conditions are likely at KBWG this evening, but we expect their cigs to come down after midnight into the MVFR range. Northeast winds will be seen this evening with speeds of 5-10 knots. Overnight, some light isentropic lift may produce a few light snow showers and/or snow flurries at the sites. Higher confidence on snow flurries/showers at KBWG/KHNB, but lower at KSDF and KLEX. Generally overcast conditions are expected on Saturday with northeast winds of 10-15kts. Confidence: Medium on cigs and winds Low-medium on snow flurries/showers overnight && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...Winter Storm Watch from Sunday morning through late Sunday night for KYZ055>057-064>067-074-076>078. Winter Storm Watch from Sunday morning through late Sunday night for KYZ041>043-048-049. Winter Storm Watch from late Saturday night through Sunday evening for KYZ073-075-081-082. && $$ Update.......MJ Short Term...BJS Long Term....CJP Aviation.....MJ
Area Forecast Discussion
National Weather Service Nashville TN
841 PM CST Fri Jan 14 2022 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Cool and cloudy at update time. Pretty quiet out there. We`ll take it because the next couple of days are going to be hectic. I`m not going to go into a bunch of in-depth analysis here, mainly because the 00Z model suite hasn`t come in yet. I`ll leave that to the overnight crew. What I will say is that several places in Middle TN look like they`re going to get more snow than they bargained for Saturday night and Sunday. Yes, models are all over the place as far as positioning where the heaviest snow is going to fall, but if there`s anything they agree on, someone (or a large swath of someones) is gonna get hammered. Of note, the 00Z HRRR has finally started to show heavy snow accumulation. I mention this, because arguably, the HRRR did the best with the last two snow events across the mid-state. That said, I have also seen evidence of forecast soundings showing strong Omega signs in the dendritic growth layer across a good swath of I-40 and south. How`s that for scientific? Basically, it means heavy snow for a period of time. All of this is leading to potentially 4-8 inches of snow across a good portion of the area and I wouldn`t be surprised to see a couple of spots see more and even a few spots (probably our far northwest counties) see something closer to an inch. I think the bottom line is: be prepared. Many places are going to get a bunch of snow and everyone knows how even an inch of snow can cripple TN when it comes to travel and traffic. Be prepared for major travel impacts by late Sunday morning, lasting through the night and probably even worse Monday morning in the aftermath as temperatures in the morning should bottom out in the 20s, freezing over anything liquid on the roads. Afternoon temperatures Monday will try to inch towards 40 but I`m seeing a lot of clouds Monday, so the sun may not be out to help melt anything on area roadways. Hopefully by Tuesday, we can start getting things back towards normal. && .AVIATION... 00Z TAF DISCUSSION. VFR conditions continue currently with conditions expected to begin deteriorating beginning with CKV ~14Z, BNA/MQY ~17Z, and CSV ~19Z. MVFR vis and cigs expected as SHRA/VCSH moves through the area mainly after 18Z through the remainder of the TAF period. Winds will remain from the NE, with winds increasing by mid- morning. Gusts upwards of 15 to 25 kts can be expected at CKV after 18Z and BNA/MQY after 22Z. I will note, there is a small chance that a few flurries could mix in with SHRA mainly at CKV between 10Z and 14Z. Confidence is low which is why it was not included in the TAF, but worth mentioning. && .OHX WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from Saturday evening through Sunday afternoon for all of Middle TN. && $$ DISCUSSION......Unger AVIATION........Adcock