Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/27/19

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
902 PM CDT Sat Oct 26 2019 .UPDATE... Issued at 859 PM CDT Sat Oct 26 2019 Made a few adjustments this evening. Updated PoPs, and added a bit to QPF progs given latest HRRR runs. This resulted in just a bit more snow vs previous package. Next round of pcpn is forming over the High Plains, and is headed toward the southwest CWA. Temperature forecast looks to be on track. && .DISCUSSION... Issued at 235 PM CDT Sat Oct 26 2019 A cold front continues to traverse the region and will be through the CWA over the next few hours. As expected, post frontal winds have become quite gusty with areas in the western CWA with observed gusts up to 40 mph. Winds will decrease a bit from west to east tonight, although will still remain breezy overall through Sunday. A few light showers (potentially with some snow mixed in) this afternoon will cross over north central South Dakota. These showers won`t produce much in the way of precipitation. More significantly is the potential for snow tonight in central South Dakota as shortwave energy passes through the area. One to two inches of snow is possible in central South Dakota with the highest amounts likely confined to along and south of the I90 corridor. Still, a few tenths to half an inch of snow are certainly possible in portions of northeastern South Dakota as well, especially on the Coteau. Beyond tonight, an upper level longwave trough sets up over the southwest to central CONUS and doesn`t really move much through the workweek. This will lead to colder than average and mostly dry conditions through the forecast period. By the weekend, models indicate the longwave trough will finally kick off to the east and a change to northwest flow will ensue. As mentioned, temperatures take a dive with high temperatures struggling to even make it out of the 30s through Thursday, while lows drop into the teens and 20s. The coldest period as of now looks to be Tuesday through Wednesday night following a fropa Monday night. Highs Tuesday and Wednesday will be in the upper 20s to low 30s with lows in the teens over most, if not all, of the CWA. && .AVIATION...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 614 PM CDT Sat Oct 26 2019 A mix of VFR/MVFR cigs will move from west to east across the CWA overnight. Light rain/snow is also possible, and may occasionally limit vsbys to less than 3 statute miles, especially at KPIR overnight. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...TDK DISCUSSION...Telken AVIATION...TDK
Area Forecast Discussion
National Weather Service State College PA
1143 PM EDT Sat Oct 26 2019 .SYNOPSIS... Low pressure will track north through the Great Lakes tonight, with the trailing cold front coming through Pennsylvania Sunday. High pressure will build into the region early next week, then another low pressure system is likely to track west of Pennsylvania late in the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Radar trends and model data showing best fgen forcing lifting north of Pa late this evening support lowering POPS from south to north between 02Z-06Z. The latest HRRR and 12Z HREFV3 support this scenario, with only scattered showers/patchy drizzle across the central mountains and Allegheny Plateau by midnight. The focus still remains on approach of cold front and heavier rain late tonight. Strong forcing ahead of approaching shortwave, combined with a plume of tropical moisture, will support a period of moderate to heavy rain moving into the western half of the forecast area by dawn. Low level stability fields indicate the surface warm front will surge into the southern and western counties toward dawn, causing temperatures to rise before sunrise. Evening lows are expected to range from the upper 40s to low 50s, but readings by dawn are likely to be well into the 50s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... Latest guidance indicates band moderate to heavy rain will sweep east of the region with cold front by around 15Z. HREFV3 EAS probability fields indicate rainfall totals of around 2 inches are possible across the Poconos, where orographic forcing will play a role. Elsewhere, totals of 1 to 1.5 inches appear likely. These amounts fall short of FFG/FFH numbers, so flooding does not appear to be a significant threat. Strong subsidence behind front should result in breaking clouds across parts of the area during late morning and early afternoon. However, low level instability associated with arrival of cooler air around 850mb should result in plenty of stratocu during the PM hours, especially over the Allegheny Plateau. Temperatures are expected to surge during the morning hours, as chilly air at low levels mixes out. 850mb temps support readings getting into the low 70s across the Lower Susq Valley around midday before increasing clouds and cold advection develop during the afternoon. Elsewhere, expect max temps to range from the upper 50s over the NW Mtns, to the 60s east of the Allegheny Plateau. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... * Dry weather and slightly above normal temperatures for Sunday through early Wednesday * May be a stormy Halloween followed by colder weather with the first mix of snow across the higher elevations Nov. 1 The storm system affecting the near and short term will clear out by early Sunday afternoon (west) and by Sunday evening (east) night, with not much cooling expected behind it and the flow remains out of the southwest aloft. Surface high pressure builds across Monday and moves off the coast Tuesday with a mild southerly flow through PA. Weak disturbance moves across Great Lakes Tuesday night just bringing a slight chance shower to the northwest. Still uncertainty with the timing of the next high amplitude system which is looking to impact Halloween. Increasing chances of rain from slight to chance Wednesday due to the uncertainty of the timing with the next storm system. It may hold until Thursday morning. Another pretty good rain expected as the storm system moves by. Strong cold front with temperatures and thickness dropping behind it. Brought a mixture of rain and snow showers in over the higher elevation areas overnight Thursday and Friday. Post frontal westerly flow will continue into Saturday with dry weather and near to below normal temps for the early part of next weekend. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Rain more spotty as of 11 PM. Minor updates to the TAFS. Earlier discussion below. 00Z TAFS sent. Much of the rain has stayed well to the west of the area, but conditions starting to head down. LLWS will be of concern as well overnight. Expect rain to become more widespread to the southeast later tonight and Sunday morning. Hints since late last evening when I was getting done with the fcst that the system is moving slightly faster now, than what the models showed the other day. Thus improving conditions from west to east during the afternoon Sunday. After Sunday, several real nice days for late October, as high pressure builds eastward into the area. .Outlook... Mon-Tue...Dry with mainly VFR conditions. Wed...Increasing clouds with a chc of rain late. Thu...Widespread showers with restrictions. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Fitzgerald/Lambert NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald/Tyburski LONG TERM...Lambert/Gartner AVIATION...Martin
Area Forecast Discussion
National Weather Service Cheyenne WY
706 PM MDT Sat Oct 26 2019 .UPDATE... Issued at 654 PM MDT Sat Oct 26 2019 Despite the quicker than anticipated frontal passage over the region, light snow has not occurred as far south as anticipated by 01Z. Temperatures are not dipping down to dew point readings and the atmosphere isn`t moistening down to the surface toward the WY/CO border. Due to this observation, snow totals have been decreased a bit to reflect the current situation. It should not take much longer to have light snow in Cheyenne as observations show Wheatland having snow falling as of 01Z. && .SHORT TERM...(This evening through Monday) Issued at 330 PM MDT Sat Oct 26 2019 At 3 pm, the leading edge of much colder air was situated from north of Rawlins and Laramie through Cheyenne and the southern NE Panhandle. The front was 2-3 hours ahead of schedule, and will continue its southward trek into northern CO through late this afternoon and early evening. There was a north to south temperature gradient, ranging from 31 at Casper WY to 71 at Sidney NE. An increasing northeast-southwest band of post-frontal snow from western through northeast WY will settle south across the CWA through this evening. Most high-resolution models and model ensemble blends are consistent with the development of widespread accumulating snow tonight and Sunday. Very deep dendritic growth zone below 0C (up to 10000 ft), significant upward vertical motion in left front quadrant of 140-kt 250mb jet, slow moving 700mb front over southeast WY and moist upslope low-level northeasterly flow are the ingredients coming together for periods of moderate to heavy snowfall. Winter weather headlines were adjusted to account for storm total snowfall, with no changes to the timing of the event (tonight through Sunday night). In addition to Dawes County NE, Winter Weather Advisories were issued for Box Butte, Banner, Scotts Bluff, and Kimball counties. A Winter Storm Warning was issued for South Sioux County NE, as well as the Sierra MAdre Range in southeast WY. Both the Pine and Cheyenne Ridges will measure locally higher totals, with widespread 2 to 8 inches for the NE Panhandle, and 8 to 18 inches for southeast WY. Model ensembles have been trending higher the last few model cycles, while outliers like the NAM are trending lower. Gusty north to northeast winds around 25 mph wil create patchy blowing snow. the combination of falling and blowing snow, slick/snow-covered roads and poor visibility will create dangerous winter driving conditions tonight and Sunday. Snowfall will begin to taper off Sunday night and Monday morning. .LONG TERM...(Monday night through Friday) Issued at 422 AM MDT Sat Oct 26 2019 The active winter weather will persist through the upcoming week, with the next round of snow expected as early as Monday night and Tuesday morning. A reinforcing shot of very cold air and accompanying upper level trough will produce periods of light to moderate snow. At this time, advisory snow amounts will be possible, with 2 to 6 inches for much of southeast WY and the southern half of the NE Panhandle. After this system departs and snow ends Tuesday night, expect bitter cold temperatures with fresh snow cover (lows 5 to -5 degrees and wind chills as low as -20). A slow moderation of temperatures commences Wednesday through the end of the week, but remaining well below normal. An increasing northwest flow aloft and 700-850mb gradients may produce strong winds Wednesday night and Thursday morning for the southeast WY wind corridors. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 519 PM MDT Sat Oct 26 2019 Front has made its way through southeast Wyoming this afternoon and is currently in northeast Colorado. Winds have shifted northeast for locations east of the Laramie upsloping conditions have started. Generally followed HRRR guidance for the 00Z TAFs which shows lower ceilings developing after 03/04Z and continuing overnight. Snow should begin in earnest after 06Z for many locations and continue through much of the day Sunday. LIFR conditions looking likely...especially for KCYS. && .FIRE WEATHER... Issued at 139 PM MDT Sat Oct 26 2019 Warm, breezy and dry conditions early this afternoon will be short-lived as a strong cold front advances south across the districts through late the afternoon and early evening. Sharply colder temperatures will cause rain to quickly change to snow. Widespread snowfall, moderate to heavy at times, is likely tonight and Sunday before decreasing Sunday night. Bitter cold wind chills are expected Sunday night through Tuesday night. Another strong cold front and upper level weather disturbance will bring a continuation of very cold temperatures and additional light to moderate snowfall. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Storm Warning until 6 AM MDT Monday for WYZ101>110- 112>119. NE...Winter Storm Warning until 6 AM MDT Monday for NEZ095-096. Winter Weather Advisory until 6 AM MDT Monday for NEZ002-003-019- 020-054. && $$ UPDATE...BW SHORT TERM...MAJ LONG TERM...AB/MAJ AVIATION...GCC FIRE WEATHER...MAJ
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
939 PM CDT Sat Oct 26 2019 .UPDATE... 939 PM CDT Evening Update... Heavy rainfall has impacted much or northeast IL during the late afternoon and evening hours, with many reports of 2" to 3" amounts as of mid-evening. Getting several reports of street/viaduct flooding around and near the Chicago metro area. Have issued an areal flood warning for much of northeast IL which runs through 845 am Sunday morning. Plan to maintain other headlines (Lakeshore Flood Advisory, etc.) as they are at this time. Vigorous autumn storm system was tracking northeast across the region as of 9 pm, with surface low pressure near 995 mb located near Kankakee. Large deformation zone area of moderate to heavy rain extends from east of St Louis northeast across northern IL into southeast WI, with some decrease in reflectivity intensity noted across the forecast area recently. Radar rainfall estimation has generally been significantly underdone compared to measured reports received this evening, with many spotter reports of rainfall in excess of 2 inches received. Based on this, and many reports of various street and low lying area flooding, have issued aforementioned areal flood warning in effect through the overnight hours and early Sunday morning. Rain will eventually taper off from southwest to northeast during the pre-dawn hours. Otherwise, not much change in thinking or to headlines from the previous shift. Have maintained a special weather statement for gusty 40-50 mph winds across our far southeastern cwa associated with strong isallobaric gradient, as well as lakeshore flood advisory for large waves impinging on the Illinois section of our Lake Michigan shore. Ratzer && .SHORT TERM... 303 PM CDT Through Sunday night... A very potent Autumn storm system will impact the area though tonight. As a result of this storm system there continue to be several concerns, most notably: -Several hours of moderate rain this afternoon and evening, with some concern for some areal and river flooding. -Lake shore flooding this afternoon and tonight due to strong east-northeasterly winds. -A period of strong, potentially damaging westerly winds tonight. Water vapor imagery early this afternoon shows the main mid/upper level storm system now in the beginning stages of transitioning to a negative tilt (northwest to southeast orientation) over the Ozarks. Meanwhile, the associated surface low is now moving northward into far southern IL. As the system continues to take on a negative tilt through the afternoon, expect rain rates to increase some across the area as dynamic forcing for ascent begins to really ramp up over IL. The heaviest rain is likely to occur over northern IL early this evening. This is the time when the strong upper level dynamics will coincide with strong mesoscale forced ascent within a developing deformation zone over the area. While instability is expected to remain lackluster over the area into this evening, negative EPV within this zone of strongly forced ascent could support a few embedded rumbles of thunder into this evening and this could support some locally heavier rainfall rates. Total rainfall amounts through later this evening should end up around 2", with the highest amounts again expected to be centered right across northern IL, in and near the Chicago metro area. This is the area in which a band of strong mid-level frontogenesis will develop within a strengthening deformation zone. The enhanced lift, generated from a ageostrophic response, in this zone will likely drive some locally enhanced rainfall rates this evening. Expect the rain to abate over the area overnight as the storm system quickly shifts to the northeast. The other concern tonight is with the magnitude of the winds. With a surface low this deep, winds are certainly gusty tonight. That said, there is not enough confidence in any one area for a wind headline (regular 45+ mph gusts). Two areas though that winds could briefly top criteria are near the lakefront and then the southeast forecast area overnight. As the low approaches, northeasterly winds will sharply strengthen within the pressure falls this evening. This component will be fully onshore into northeast Illinois thus lowering any frictional aspect and allowing for potential 40+ gusts. For the southeast forecast area, in the immediate wraparound cold advection, there is a surge of pressure rises collocated with mixing (albeit shallow), that potentially supports a brief period of 50 mph gusts. The HRRR has been showing wind gusts of this high, and most models have near or up to 50 kt flow at 925 mb. For now have handled this with a Special Weather Statement, but a short-lived Wind Advisory is possible. Regarding the strong onshore winds in northeast Illinois, this will build waves considerably this evening as more of the fetch is realized with the backing wind direction. Waves of 8-11 ft are likely with some occasional higher. With the high to near-record lake levels, this nears our criteria for a warning, but the somewhat short duration of a great onshore component lowers confidence a bit. Will maintain a strongly worded advisory for now. For northwest Indiana, the waves will take a noteworthy jump in the northwest flow overnight, but that is even short lived, so no advisory needed for now but still some brief high wave action predicted overnight especially for Porter County. After tonight, conditions will improve nicely for Sunday. Lighter winds and clearing skies should set up a nice end to the weekend, with highs likely in the upper 50s to around 60. KJB/MTF && .LONG TERM... 305 PM CDT Monday through Friday... Not much has changed with the forecast thinking in the extended. Please see the previous discussion below for more info. Next week looks to remain active with several periods of precip chances. Highly amplified pattern and a large upper level trough in place across the CONUS will support periodic precip chances through mid week. An upper level low/trough then expected to swing through the region late in the work week and provide additional precip chances. Guidance still varying to the overall evolution to the pattern and systems next week, including the extent and timing of any colder air moving through the region. This will be something to keep an eye on, as this colder air could bring a chance of more wintry type weather. Rodriguez/KJB && .AVIATION... For the 00Z TAFs... 704 PM...Forecast concerns include... Strong gusty northeast winds shifting northwest tonight. Rain with lifr/ifr cigs this evening. Low pressure over east central IL will continue lifting northeast this evening. Strong/gusty northeast winds will slowly turn northerly and then northwesterly and some tweaks to this timing are possible. Wind speeds/gusts may diminish some as the low passes just to the east of the Chicago terminals. Winds will then shift northwest and a period of gusts to 30kts is possible overnight. Winds will turn more west/northwest Sunday morning with speeds/gusts slowly diminishing by midday. Moderate rain is likely to continue through mid evening with light rain tapering to showers overnight. Prevailing vis likely to remain 1.5sm to 3sm for next few hours and will then slowly trend up as rain tapers off. As the low approaches...cigs may trend lower with prevailing lifr expected. As winds shift northwest... cigs will slowly lift through ifr and eventually become vfr Sunday morning. cms && .MARINE... 349 PM CDT This is the prime time for Great Lakes strong wind and high wave systems, and one certainly is impacting southern Lake Michigan through early Sunday. Northeast winds will increase through mid evening across the southern part of the lake, with this direction maximizing the fetch into northeast Illinois, where waves will peak to occasionally over 10 ft. Confidence is a little lower in northwest Indiana, which will realize its best onshore potential overnight and very early Sunday morning. Have expanded the Gale Warning to include northwest Indiana overnight. Winds will be sharply coming down in speed after daybreak Sunday and waves should slowly subside, most quickly along the Illinois shore. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Flood Watch...ILZ006-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020- ILZ021-ILZ022 until 3 AM Sunday. Lakeshore Flood Advisory...ILZ006-ILZ014 until 5 AM Sunday. Flood Watch...ILZ023-ILZ032-ILZ033-ILZ039 until midnight Sunday. IN...None. LM...Gale Warning...IL nearshore waters until 7 AM Sunday. Small Craft Advisory...LMZ740-LMZ741-LMZ742...7 AM Sunday to 10 AM Sunday. Gale Warning...LMZ743-LMZ744-LMZ745...3 AM Sunday to 9 AM Sunday. Small Craft Advisory...IN nearshore waters until 3 AM Sunday. Small Craft Advisory...LMZ743-LMZ744-LMZ745...9 AM Sunday to 1 PM Sunday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Pueblo CO
329 PM MDT Sat Oct 26 2019 .SHORT TERM...(This evening through Sunday) Issued at 254 PM MDT Sat Oct 26 2019 ...Winter returns... Southern Colorado enjoying one last mild autumn day as temperatures have soared into the 60s/70s across the plains with 50s/60s over the mountains and high valleys. The end of the warmth is in sight as strong cold front was racing south through WY this afternoon, driven southward by deepening upper trough over the nrn Rockies. Stuck with the HRRR forecast bringing the boundary through Colorado Springs around 04z, then reaching the CO/NM border by 09z. North winds will become strong for several hours behind the front, gusting to around 40 kts along and east of I-25, before speeds diminish and direction turns more easterly after sunrise. Precip chances overnight look fairly low, with perhaps some flurries or freezing drizzle developing over the Palmer Divide/eastern mt slopes and high terrain south of the Arkansas River as low levels gradually saturate. On Sunday, cold air deepens over the plains and eastern mountains, with wedge of warm/dry air holding on from the Sangres westward. Favored upslope areas along and west of I-25 will see on/off light snow through the day, with precip slowly becoming more widespread toward late afternoon as dynamic lift begins to increase ahead of the upper trough. Not expecting much if any snow accumulation during the day Sunday, with generally a dusting most locations, while Pikes Peak region and Palmer Divide see up to an inch. Didn`t make too many changes to precip chances over the eastern mountains and plains, but did lower pops somewhat farther west over the central mountains, where most models suggest snow holds off until evening. Max temps on the plains won`t rise much from morning lows, with readings steady or evening falling slightly by afternoon. Relatively warmer air holds on across the San Luis Valley and southwest mountains, with only slight cooling from Sat readings. .LONG TERM...(Sunday night through Saturday) Issued at 254 PM MDT Sat Oct 26 2019 Sunday night - Monday night... At the start of this period, the aforementioned southwest-northeast oriented upper trough axis will extend from east-central California through the Great Basin and and into North Dakota. The associated southwesterly jet will be draped across Colorado. Post- frontal surface flow will be easterly across the eastern plains, and snowfall will be increasing in coverage and intensity across the central mountains and Pikes Peak Region southward. Sunday night through Monday morning, the trough axis will shift east across the Great Basin and into Colorado, with considerable QG forcing for ascent and height falls overspreading southern Colorado. Strong upper forcing combined with intense southwest to westerly upslope low to mid level flow will result in accumulating snowfall over the Continental Divide, with greatest amounts over the southwest mountains and central mountains. Heaviest precipitation appears to be focused along a 700 mb front/convergence zone, between 06Z and 15Z Monday morning. Further east, the strong upper forcing combined with continued easterly upslope surface flow across the plains into the eastern mountains will yield widespread snowfall, with greatest coverage/intensity across the I-25 corridor and Wet mountains. Another factor promoting accumulating snowfall will be strengthening isentropic lift during the morning within a saturated dendritic growth zone. Finally, the strong southwesterly upper level jet overhead will support the development of southwest to northeast oriented snow bands, within which locally heavy snowfall may occur. Heaviest snowfall across the I-25 corridor should occur between 12Z and 18Z. Thereafter, snow across the forecast area will decrease in coverage and intensity as the trough axis shifts east out of Colorado, with snowfall ending across most areas by 00Z. Height rises and large scale descent in the wake of the exiting trough will lead to dry weather Monday night. There is limited uncertainty regarding the likelihood of accumulating snowfall with this system, as deterministic runs have shown an acceptable degree of run-run and model-model consistency over the last several day or so. Further, ensembles show only minor timing and QPF differences, hence a slight snow total/timing uncertainty. As for snow totals, currently expecting 4-8 inches across the southwest and central mountains, and 6-12 inches over the eastern mountains, with the Wet Mountains on the higher end of the threshold, and Sangres lower. For the I-25 corridor from Walsenburg to Colorado Springs, expect anywhere from 3-8 inches of total accumulations with this event, while northern El Paso and Teller Counties should see more like 6-10 inches. Snow banding could result in varying snow totals within small spatial areas, including locally higher amounts. Locations across the eastern plains should experience 1-3 inches of snow accumulations, while the San Luis Valley will see snowfall up to one inch. Therefore, have upgraded all zones within the existing watch to a Winter Weather Advisory, with the addition of the northern Sangres. Held off on including the eastern San Juans as models have been inconsistent here, so will wait for the next round of runs in order to gain confidence in this area. Temperatures will dip into the teens across the plains and valleys both Sunday night and Monday night, with highs on Monday struggling to rise above freezing anywhere except in the San Luis Valley. Tuesday - Wednesday... After a brief break Monday night, the next system will dig into the Great Basin and across Colorado Tuesday through Wednesday, sending another cold front down the eastern plains Tuesday night. The latest GFS and ECMWF runs are quite similar with the track, closing off the low over Utah and tracking it east across Colorado. However, the GFS is faster than the ECMWF by about 12 hours. The GFS ensemble mean shows a similar solution, but with considerable timing differences and most members displaying a slower evolution. There is also significant timing and total QPF spread among members. Bottom line, it appears as though a second storm system will bring another round of accumulating snowfall to most of south-central and southeast Colorado sometime during the Tuesday through Wedensday evening timeframe. However, it is still too early to pinpoint the period of heaviest snowfall, and snowfall totals. Temperatures will remain cold, with daytime highs near or below freezing. Overnight lows will be very cold, with single digits forecast over the lower elevations, and below zero temperatures over the mountains and some valleys. Thursday - Friday... Tranquil weather returns to Colorado for the end of the work week as drier air moves into the region and a ridge begins to build over the southwest US. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 254 PM MDT Sat Oct 26 2019 At KALS, VFR the next 24 hrs with increasing s-sw winds by midday on Sunday. At KCOS and KPUB, VFR into this evening. Strong cold front then pushes south through both sites 04z-05z, bringing north winds gusting to 40 kts until 08z-10z. Lower clouds will fill in behind the boundary, with MVFR cigs both terminals by 10z, and areas of IFR/LIFR conditions over the higher terrain just north and west of KCOS. May even see a few flurries or brief freezing drizzle as air mass saturates. Clouds and flurries hang on all day Sunday, with MVFR cigs occasionally lowering to IFR both sites. Snow then becomes more widespread Sun night into Mon with MVFR/IFR cigs and vis possible. && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 4 PM Sunday to 6 PM MDT Monday for COZ058>063-072-073-076>087. && $$ SHORT TERM...PETERSEN LONG TERM...LINE AVIATION...PETERSEN
Area Forecast Discussion
National Weather Service Blacksburg VA
737 PM EDT Sat Oct 26 2019 .SYNOPSIS... High pressure will drift northeast and away from the region as low pressure lifts north through the Tennessee and Ohio Valleys. The approach of this low pressure system, and its associated cold front, will result in plenty of clouds and a slowly increasing threat for rain from west to east with the bulk of the rain to fall tonight into Sunday morning before skies begin to clear from the west following passage of the front. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 720 PM EDT Saturday... Rain and drizzle has been gradually lifting northward along the Blue Ridge into portions of the New River Valley under increasing upslope flow, despite the radar showing little returns, as beam overshoots the lower cloud layer squeezing out the moisture. Showers are also approaching southeast WV early this evening, though appears main line of showers arrives after midnight, while southeast flow induced rain showers increases along and either side of the Blue Ridge. Updated forecast to account for latest radar/high-res model trends with the HRRR handling things fairly well. Updated to include some moderate to heavy rain at times toward dawn as convective elements are likely. Appears just enough instability to arrive in the southern CWA late tonight for isolated thunder chance which includes after 12z Sunday. The Storm Prediction Center is actually showing a marginal risk for severe storms scraping our far eastern counties tomorrow around Halifax/Charlotte due to wind energy with this front. However, timing of this does not favor severe as it moves through prior to 17z, but have thunder in the grids. Wind advisory still looks good with gusts ramping up before midnight, lasting through about dawn, then tapering off, as flow turns south, then southwest. Previous discussion from early this afternoon... Wind Advisory in effect through 10 AM Sunday from western Greenbrier southward to Watauga county. A cold front will slowly move across the area tonight into Sunday. A short wave will track along the front tonight, bringing widespread moderate rain to the area. Low level convergence, strong warm air advection, good moisture transport and jet dynamics may produce isolated heavy downpours overnight. With low level southeasterly flow going up the Blue Ridge this afternoon and overnight, storm total rainfall amount could approach 2 inches. Across the rest of the area, rainfall amounts will range from a half to one inch across the mountains and foothills, to half an inch over the Piedmont. Fortunately, no flooding concerns are anticipated due to initially relatively low creek and stream levels. However, urban street flooding is possible as fallen leaves may clog storm drains. Southeast winds along the Blue Ridge will have an opposite effect along the western slopes from Greenbrier County WV to Watauga County NC. Downsloping winds may gusts up to 50 mph tonight into Sunday morning. The front is expected to clear the mountains by sunrise, then move east of the piedmont by early afternoon. With the early exit of rain and no strong cold air advection behind the front, Sunday afternoon temperatures will warm above normal with upper 60s to lower 70s across the mountains and mid to upper 70s east of the Blue Ridge. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 215 PM EDT Saturday... High pressure will be building into the eastern states for the start of the work week with mild temperatures and sunny skies. the resilient upper level ridge over the southeast will become strongly reestablished on Monday with heights building along the east coast while a upper trough deepens once again over the western CONUS. This has been a familiar pattern for much of the last 6 to 8 weeks. Well above normal highs will be in place for Monday with 70s possible especially east of the Blue Ridge. Surface high begins to retreat to the northeast on Tuesday as upper ridge axis shifts slowly east as well. Highs will again top 70 in much of the area close to 10F above late October climatology. Lows will be upper 40s to low 50s both days. High clouds will increase on Tuesday ahead of the next potential weather-maker over the Midwest. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 300 PM EDT Saturday... A slow-moving front will stretch from the eastern Great Lakes down to east Texas on Wednesday as meridional flow amplifies with the stubborn ridge off the east coast combined with a deepening trough over the Rockies. The return flow of moisture ahead of this boundary will result in increasing clouds and pops during the day with high chance or likely by late afternoon. The slow movement and abundant moisture suggests the possibility of substantial rainfall from this mid-week system with possibly several waves of low pressure developing along the front to slow down the front and prolong rain chances. Early QPF forecasts from WPC suggest another 1 to 2 inches of rain possible before ending late Thursday or early Friday. Temperatures look to be mild through Thursday even with the clouds and rainfall with highs generally in the 60s and lows in the 50s. Slowly clearing skies Friday with more seasonable temperatures likely into the start of next weekend. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 725 PM EDT Saturday... Expect deteriorating conditions tonight into Sunday morning as rain showers increase in coverage. Should see sub-VFR by 05z, then IFR to at times LIFR with moderate to heavier showers as front moves across between 08z-13z in the west, exiting the east by 16z-17z. Southeast winds will be gusty especially at BLF with up to 30-35kts likely this evening into overnight, then slacking off as flow turns southwest after 08z. Cannot rule out some low level wind shear this evening at BLF/BCB, but at the moment kept them out due to showers arriving/convective element. Look for improving conditions from west to east in the 12-17z time frame Sunday to VFR. Winds turn west, and some gusts to 20kts possible in the mountains. .Extended Aviation Discussion... High pressure building in from the west supports VFR weather Sunday night through at least Tuesday. Approach of yet another Gulf Coast system and associated area of widespread rain then expected to bring another period of sub-VFR weather to the region on Wednesday into Thursday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Wind Advisory until 10 AM EDT Sunday for VAZ007-009-015. NC...Wind Advisory until 10 AM EDT Sunday for NCZ001-018. WV...Wind Advisory until 10 AM EDT Sunday for WVZ042-043-508. && $$ SYNOPSIS... NEAR TERM...RCS/WP SHORT TERM...PC LONG TERM...PC AVIATION...RCS/WP
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday night) Issued at 259 PM CDT Sat Oct 26 2019 19Z water vapor imagery showed a closed upper low near the MO boot heel lifting northeast. Another upper low was noted over Manitoba with an upper trough stretching back to the southwest over the northern Rockies. This upper trough was digging south. At the surface, low pressure was moving north along the MS river valley into the Upper Midwest and a cold front was seen moving into the NEB panhandle. For tonight, relatively dry air should remain over the forecast area keeping skies clear ahead of the approaching cold front. With light winds, think low temps will drop off into the mid 30s for most areas. Can`t rule out the possibility for some localized ground fog again, but impact looks to be too limited to include in the forecast at this time. The cold front is expected to move through the area through the morning hours of Sunday. A lack of deep layer moisture and forcing is expected to keep the frontal passage mainly dry. However the NAM and now the RAP still show some potential for the development of drizzle by Sunday evening with some isentropic lift within the stratus deck. The GFS forecast soundings tend to have more dry air below the stratus than other solutions. So am not sure what to believe as the NAM tends to over do the boundary layer moisture. Have left the mention of precip out of the forecast for now, but later shifts will need to monitor trends. For now lows Sunday night are expected to be in the mid and upper 30s across east central KS where the drizzle is more likely. So impacts from any drizzle appear to be negligible. Temps through the day Sunday could be a little tricky. Have trended highs cooler across north central KS where a north wind and mostly cloudy skies are expected to keep temps steady in the 40s to near 50. East central KS could still see a warm up to near 60 where clouds will be slow to move over. .LONG TERM...(Monday through Saturday) Issued at 259 PM CDT Sat Oct 26 2019 The Monday into Monday night periods see a weakening upper trough pass from southwest to northeast across the region with the surface front well south. There are some differences on the wave`s track with the GFS slightly farther south with the main PV anomaly but the lack of consistent, deep saturation with the weakening wave bring only moderate precip chances. Southeastern areas could again see some drizzle along the elevated boundary especially if the wetter NAM-sourced solutions end up being more on target with low-level moisture, and forecast high temperatures could also be a bit warm in this scenario, but an overall 10-15 degree diurnal rise seems in order area-wide. The rapidly-exiting wave should end anything but very light precip amounts by shortly after midnight. Most precip should fall as liquid but some light snow can`t be ruled out Monday morning and evening. The main periods of concern continue to be Tuesday night to late Thursday with the next upper trough`s progressions south over the Rockies then northeast through the central Plains. Reinforcing cold air behind the Monday system will keep temperatures much below normal as this system arrives. The track and timing details of the trough continue to be uncertain, though an overall slower trend is apparent, with the operational GFS still on the fast end of the spectrum. This slower trend could lend itself to a more variety of precip types with some warm nose potential in play. The bottom line at this range is that accumulating wintry precipitation is possible at times for much of these periods. Continued northwest flow keeps temps cool into next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 617 PM CDT Sat Oct 26 2019 For the 00Z TAFs, have maintained LLWS eventhough most guidance suggests it will likely be marginal and only have a short window to develop. Increased LLJ winds ahead of the incoming boundary do look to be around FL 10. In very low lying areas, there could be a short window for ground fog as well. Have not mentioned in the TAFs with overall low potential. FROPA should take place first at KMHK around 09Z and then by 11Z time frame for KTOP/KFOE sites. Low stratus should lag the front into the late morning hours and some gusts up to around 20kts could be common into the afternoon. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Wolters LONG TERM...65 AVIATION...Drake
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
947 PM MDT Sat Oct 26 2019 .UPDATE... Issued at 942 PM MDT Sat Oct 26 2019 Snow is decreasing over the Black Hills so have cancelled the winter wx advisory that was in effect...with additional accumulations around an inch or less. The main band of snow has set up across Fall River county and extends northeast through the Badlands. This heavier band will continue to shift south/east tonight, and taper off by morning. Will keep the advisory in place for Fall River, Oglala Lakota, and Bennett counties where 3 to 6 inches total accumulation are likely. UPDATE Issued at 602 PM MDT Sat Oct 26 2019 The wind advisory has expired, and winds will gradually decrease overnight. No adjustments made to snow amounts or the winter weather advisory at this time. && .DISCUSSION...(This Evening Through Saturday) Issued at 138 PM MDT Sat Oct 26 2019 Upper trough is digging into the northwest quadrant of the CONUS, with the jet across Idaho to Wyoming into western SD. Surface obs show gusty northwest winds across the CWA behind a cold front, with gusts into the 50s across the plains adjacent to the eastern Black Hills. Will let the wind advisory continue. Temperatures have been slowly dropping behind the front. Short to medium range models continue to show a band of rain and snow crossing the CWA late this afternoon through tonight. This band will change to all snow this evening, bringing snowfall to much of the CWA. Accumulations will generally be light. The exception will be across two areas of the CWA...southwest SD and then northern Black Hills. Short range models and Froude plots suggest upslope flow will developing late this afternoon and continue mainly through the evening hours. There is consensus of 3-6 inches of snow across the northern Black Hills. The NAM and more recent runs of the HRRR suggest higher elevations could see localized higher amounts up to 8 inches. Will keep the advisory going given most areas will be in the 3-6 inch range. The bulk of accumulating snow will fall by 06z tonight, but lingering upslope snowfall is expected through the overnight hours. Models are also showing good consensus with 3-6 inches across portions of Fall River County in southwest South Dakota...and 2-4 inches through Oglala Lakota and Bennett Counties. Less amounts of 1-3 inches will be possible overnight across south central SD. Snow will end by mid morning tomorrow, except some lingering light snow across southwest SD ahead of the upper trough axis working its way through the region. Highs tomorrow will be in the 20s to low 30s. Dry weather and slightly warmer temperatures are expected Monday as the region remains in cyclonic flow aloft. A strong upper wave will dig through the northern Rockies late Monday, then cut off across the Great Basin on Tuesday. A cold front is progged to cross the region late Monday into Monday night. Some snowfall will be possible with the frontal passage, but light accumulations are expected at this time. Models show max temps in the teens and 20s on Tuesday. Dry weather is generally expected for the second half of the week along with warming trend. && .AVIATION...(For the 00Z TAFS Through 00Z Sunday Evening) Issued At 514 PM MDT Sat Oct 26 2019 A band of snow will continue to move southeast across the region this evening and overnight. Rather widespread IFR conditions with the snow. Conditions will improve across northeast WY and northwest SD around midnight, with improving conditions spreading southeast overnight. Most areas should be VFR on Sunday. Gusty northwest winds will gradually decrease tonight. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Winter Weather Advisory until 6 AM MDT Sunday for SDZ027-041-042- 044. WY...None. && $$ Update...Johnson DISCUSSION...13 AVIATION...Johnson