Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/23/17

Area Forecast Discussion
National Weather Service Cleveland OH
907 PM EST Sun Jan 22 2017 .SYNOPSIS... Low pressure over the Southern Plains will move to the middle Atlantic Coast by Monday afternoon. High pressure will briefly ridge into the region on Tuesday. The next storm system will move into the Central Great Lakes from the Plains on Wednesday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Added a dense fog advisory for Erie and Ashtabula lakeshore and extreme NW PA. Frontal boundary has sagged south off the lake causing dense fog near the Erie lakeshore. Visibilities may well go up and down with the boundary. Original discussion... Surface low should be in nrn GA by 00z and will move slowly to wrn NC by 12Z Monday. East to southeast flow aloft will increase overnight increasing moisture into the region. Expect clouds to continue to fill in through the evening hours. Through the evening hours followed the HRRR in bringing chance pops into the area from the southeast. Overnight followed the GFS trends with pops increasing to likely eastern two thirds of the area. Lows mostly in the mid 40s but coolest in the northwest where cooler air could sneak into the area with stationary front waffling nearby. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/... Low pressure will move from western NC to off the mid atlantic coast by late afternoon. The low will continue northeast off the New England coast through Tuesday night. deep moisture will continue to spread into the area from the east and southeast ahead of the low through the day Monday before beginning to pull east Monday night into Tuesday. Will have categorical pops most places Monday. Monday night pops will decrease west to east as the low pulls further away falling to just chance pops east by morning Tuesday. Tuesday evening should be dry east however another system will be moving out of Missouri. Models differ on track with the NAM taking the low to near South Bend by morning Wednesday while the GFS has the low centered over northern Lake Michigan. Both models however have a swath of moisture moving into the area from the west with a warm front overnight Tuesday night. Will cover with chance pops. Wednesday the system moves through the central lakes. A cold front will move through and wrap around moisture will overspread the area. Will have chance pops increasing from the northwest mainly in the afternoon. Wednesday night will continue with chance pops for rain mixing with snow from the northwest during the night most places and will have likely pops northeast for flow off the lake. Not really cold enough for lake effect but we could see limited lake enhancement as 850mb temps drop to -6C by Thursday morning. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Active northwest flow pattern expected during the long term period Thursday through Sunday. More seasonable temperatures expected beginning Thursday with highs in the mid/upper 30s. A shot of colder air will move in Friday and persist through Sunday, with 850mb temps in the -10C to -13C range. Highs Friday in the low/mid 30s and highs Saturday/Sunday in the upper 20s/low 30s currently forecasted. Prolonged lake effect snow is likely across portions of the snowbelt during this period, with several disturbances rotating through the area bringing more widespread snow chances Thursday afternoon through Friday night and again Saturday night through Sunday night. Forecast is characterized with chance/slight chance pops through most of the period, with some likely pops across the snowbelt. && .AVIATION /00Z Monday THROUGH Friday/... NE flow off of Lake Erie continues to push stratus and dense fog over the northern end of the area. TOL and ERI are already LIFR and should remain that way most of the night. No sign of fog at BKL yet so will keep CLE VFR through the evening. Have slowed the onset of precip down from the earlier package. The rain will start to move in from the southeast after 06z. Cigs will dip to MVFR by that time with IFR cigs developing by 12z all areas. Little improvement is expected on Monday with periods of rain and IFR conditions. NE to E flow will continue overnight. OUTLOOK...Widespread Non-VFR likely persisting on Tuesday across NE OH/NW PA. Non-VFR returns to the area on Thursday. && .MARINE... Northeast winds will continue to increase across Lake Erie tonight as a low pressure system tracks from the lower Mississippi valley towards the Mid Atlantic coast. Winds will be in the 15 to 25 range late tonight through Monday evening, before decreasing and backing northerly by Tuesday morning. Will be hoisting a Small Craft Advisory for portions of the lake from the Islands east through Conneaut with waves increasing to 3-5 feet with the prolonged long fetch despite marginal wind speeds. Winds will increase from the southwest Wednesday as low pressure tracks through the central Lakes. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...Dense Fog Advisory until 10 AM EST Monday for OHZ003-006-007- 089. PA...Dense Fog Advisory until 10 AM EST Monday for PAZ001. MARINE...Small Craft Advisory from 4 AM Monday to 4 AM EST Tuesday for LEZ143>148. && $$ SYNOPSIS...DJB/TK NEAR TERM...TK SHORT TERM...TK LONG TERM...Greenawalt AVIATION...Kubina MARINE...Greenawalt
Area Forecast Discussion
National Weather Service State College PA
1050 PM EST Sun Jan 22 2017 .SYNOPSIS... A multifaceted storm will bring drenching rain, elevation- driven snow and gusty winds to Central Pennsylvania on Monday. High pressure and unseasonably mild conditions will briefly return for midweek before a pattern change brings colder temperatures and lake effect snow to close out the month. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Low visibilities in stubborn denser fog finally rising a bit from Altoona through State College up toward Williamsport where a swath of fog has been persistent through the day and into this evening. PoPs currently trending upward across the region as moisture and lift increases ahead of the strong storm system tracking northeast across the Southern Appalachians. Band of light rain developed over northern mountains this eve, but QPFs were minimal. PoPs increase from south to north tonight, as latest radar and HRRR progs shows rain continuing to spread north of the Mason-Dixon line overnight. Also, winds will pick up from the east over the lower susq toward sunrise, with speeds rising to 20mph and getting gusty later in the morning. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... Rain will increase in coverage and intensity from south to north through daybreak Monday. A tightening pressure gradient between deepening low pressure in the Carolinas and high pressure in eastern Quebec will produce strong/gusty east winds early Monday morning and continue through Monday afternoon. Issued a wind advisory for most of the lower Susquehanna Valley with max wind gusts 45-50mph. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... All model data tracking closed upper low northeast across Virginia Monday. A steady rain will overspread Pa from north to south as strong upper lvl divergence, anomalous easterly low lvl jet/PWATS work into the state. Thermal profiles initially warm enough for rain everywhere. However, dynamic cooling associated with arrival of strongest forcing will likely result in a changeover to wet snow over the higher terrain of central Pa. Forecast soundings suggest the highest elevations of the Laurels/Northern Mtns could mix with or change to wet snow around midday. By later in the day, snow could become more than just a higher elevation threat, with thermal profiles even as far east as AOO/UNV cooling sufficiently for all snow. Limiting factor in terms of accumulation will be marginal boundary layer temps and warm ground. The threat is for several inches of heavy wet snow, especially favoring the higher elevations, across northern Pa. A winter storm watch has been issued for the northern counties, where 6+ inches appears possible, mainly over the higher terrain. Biggest threat across the Lower Susq Valley will likely be gusty winds, the result of tightening pressure gradient between approaching low pressure and high north of New England. Bufkit soundings indicate wgusts in excess of 40kts are likely across southeast Pa, as low lvl jet swings through Monday. Per coordination with LWX/PHI, have issued a wind advisory for this area. Lastly, still monitoring the potential for minor flooding. Target area for the heaviest rain is across the south central part of the state, where orographic forcing at nose of powerful easterly low level jet will play a role. Mean QPF from both SREF and GEFS max out around 1.5 inches in this region, which would be a beneficial rainfall. However, given FFG/FFH values around 2 inches, can`t rule out some minor flooding. The surface low will reach our latitude between about 6-12Z Tuesday, an old rule of thumb that dictated when the steady precip tends to taper off. Upper ridging will quickly build into the region later Tuesday into early Wednesday, bringing a short period of fair and mild wx. A pattern shift is advertised for the second half of the week as low pressure takes up residence over eastern Canada, and despite a tenacious ridge over the northern Caribbean and Bahamas, models carve out a long wave trough over the eastern US with a return to seasonable cold by the end of the week into next weekend. The ridge in the west and trough in the east is also usually a good one for winter storminess, but the deterministic ECMWF and GFS don`t show much more than a series of clipper type systems that promise an extended period of clouds and scattered mainly mountain snow showers that should continue through next weekend into the week after. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... Lowering conditions, now IFR-VLIFR across much of the central and eastern airfields, foretell the trend for this evening. VFR conditions still exist at KBFD/KJST, but with continuing easterly flow, even these airfields will trend lower tonight, with IFR conditions developing at these locations between 06z and 09z. Expect IFR to LIFR conditions across the entire region late tonight and much of Monday, with a widespread rain event moving into the region. Late in the period across the west and north, conditions expected to deteriorate even more as we approach 00z...with rain mixing with and possibly changing to snow. Additionally, strong gusty winds will impact southern airfields beginning late tonight and Monday. KMDT/KLNS may see gusts approaching 30-35+KT. LLWS also likely at most central and southern airfields late tonight and Monday. Outlook... Tue...Widespread sub-VFR with some improvement by aftn. Rain/snow ending in the morning. Gusty winds from NNW decreasing late. Wed...Low cigs/rain possible western 1/2. Breezy late. Thu-Fri...MVFR/IFR in rain/snow showers west. MVFR to VFR east. && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from Monday afternoon through Tuesday morning FOR PAZ005-006-037-041-042. Wind Advisory from 5 AM to 4 PM EST Monday FOR PAZ057-059- 064>066. && $$ Synopsis...RXR/Steinbugl Near Term...RXR/Steinbugl Short Term...RXR/Steinbugl Long Term...Fitzgerald/La Corte Aviation...Jung/Steinbugl
National Weather Service Des Moines IA
545 PM CST Sun Jan 22 2017 .SHORT TERM.../Tonight through Monday/ Issued at 312 PM CST Sun Jan 22 2017 The situation has changed little over the weekend with low clouds and fog trends the primary concerns. While the potent short wave continues to plow through the Gulf Coast states, a weaker wave is caught in our weak flow in MO. This is trying to brush southeast IA with precip and weak forcing and a hint of frontogenetical response but likely isn`t going to result in anything so the forecast remains dry. Stratus and fog continues to blanket IA this afternoon as well as upstream into the Dakotas and MN. With 500m trajectories coming from these same areas, expect little change into the night. The overall flow is very weak with local soundings showing <50kts through the depth of the column. Outside of some brief clearing potential west, NCEP NMM/ARW, HRRR, RAP and SREF all suggest plenty of stratus into the night. The bigger question will be how much fog develops. These same models do not depict much in the way of additional fog formation overnight, which makes some sense. Our low level flow is out of the north rather than south vs this time yesterday, visibilities are higher and the more uniform clouds should preclude much radiational cooling. Thus have some fog wording in the forecast, but confidence is not high enough for another advisory. These clouds should also hold up temperatures so have lows above MOS guidance. .LONG TERM.../Monday night through Sunday/ Issued at 312 PM CST Sun Jan 22 2017 Winter storm potential shaping up for Tuesday into Wednesday across northern Iowa was the main focus of the extended. Some model consensus with storm track and timing for storm Tuesday/Wednesday. The NAM/ECMWF and even Canadian are very similar with the track of the surface low but differ with timing. The NAM is the fastest while the Canadian lags behind roughly 12-18 hours from the ECMWF. As far as timing, the GFS and ECMWF are in decent agreement with the surface low tracking across the region but believe the GFS is too far north with the track. Thus, leaned closer to the ECMWF/NAM blend for pops/qpf. Surface low develops over the central Rockies and transitions across the Plains Monday into early Tuesday before centering over northeast Kansas by midday Tuesday. A decent slug of theta-e advection combined with strong frontogenetical forcing b/t 600-75mb advances north-northeastward ahead of the surface low late Tuesday morning into the afternoon hours. Good omega within the DGZ from a line near Fort Dodge to Mason City west-northwest through the afternoon hours into Tuesday evening. Deep saturation per ECMWF forecast soundings looks to be b/t 15-21z time frame in the aforementioned location. Cross section from southeast to northwest Iowa suggests some negative EPV and possibly releasing CSI over northern Iowa which would enhance the snowfall rates a bit Tuesday afternoon into the evening. There`s also plenty of large scale forcing Tuesday afternoon into the early evening, with a lull in the activity late Tuesday night before the surface low moves east and the wrap around snow develops in the CAA regime overnight towards Wednesday morning. Confident to raise pops/qpf and thus snow amounts across the northern portions of the forecast area, roughly along and north of Highway 20 to the Minnesota border. A band of 4-7 inches seems likely with the higher amounts in the far northern portions of the forecast area and issued a Winter Storm Watch Tuesday into Wednesday afternoon. Strong surface pressure gradient develops on the backside of the surface low Wednesday with the column remaining saturated for much of the morning. Forcing isn`t as significant as Tuesday afternoon/evening time frame, but enough to produce falling snow within the blustery winds. Winds are not strong enough for whiteout conditions, but certainly drifting and visibility restrictions are highly likely. Lingering snow showers seem possible per the ECMWF Wednesday night and added low chance pops across the eastern half of the forecast area but may need to increase if the ECMWF remains consistent with this solution. Thursday into Sunday...Generally north to northwest flow aloft develops during this time frame and puts the state in some colder air through the end of the week. A couple weak shortwaves may bring some light snow showers to the north, but timing between extended models remain inconsistent and thus low confidence with any mention past Thursday. && .AVIATION.../For the 00Z TAFS through 00Z Monday evening/ Issued at 545 PM CST Sun Jan 22 2017 LIFR conditions in low stratus should remain in place through 14Z before improving. Fog should not be as dense tonight through pockets of deeper moisture may be responsible for an occasional 1/2sm to 1/4sm. In general vsbys of 1sm or better are anticipated. && .DMX WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from Tuesday afternoon through Wednesday afternoon for IAZ004>007-015>017-023>028-033>038. && $$ SHORT TERM...Small LONG TERM...Podrazik AVIATION...FAB
Area Forecast Discussion
National Weather Service El Paso TX/Santa Teresa NM
321 PM MST Sun Jan 22 2017 .SYNOPSIS... A ridge of high pressure aloft will continue the mild pleasant weather tonight and Monday across the Borderland. Another Pacific storm system will sweep across New Mexico Monday night and Tuesday. This will give the lowlands a slight chance of rain showers. Over the mountains, mostly snow will fall with as much as 2 to 4 inches possible above 7000 feet. This storm will exit the area Tuesday afternoon, to be replaced by drier west to northwest flow. The remainder of the week after Tuesday should remain mostly clear, but temperatures will also remain on the cool side. && .DISCUSSION... Yesterday`s storm has rapidly exited the area and is well to our east now. Upper ridge building into area ahead of next Pacific storm system, which is moving onshore of the west coast. Expect mostly clear skies tonight, and with light winds, some patchy fog will be possible. The heavier rain yesterday was limited mostly from El Paso westward. Latest HRRR shows smallest dewpoint depressions overnight basically west of the Organ and Franklin Mts, so will keep patchy fog mostly in lowland zones west of the Rio Grande. Upper ridge should allow plenty of warming on Monday, with highs well above normal. Pacific storm sweeps in Monday night. Satellite shows plenty of cold air over the ocean behind the front, so expect another chill down. Upper trough is large feature with surface front near the front edge. Front should reach the area Monday night, with gusty winds just ahead of it. A few showers could develop over the Gila Monday afternoon, otherwise expect showers to develop in more earnest in the evening. Looks like best chances though will remain north and west of Las Cruces. Snow levels will remain above 9000 ft Monday afternoon but then rapidly fall with the passage of the front. Snow levels by Tuesday morning should be around 5000-6000 ft over the Gila and around 6000 ft over the Sacs. Moisture is somewhat limited with max PW`s around .40 inch, so snowfall of 2 to 4 inches is not out of the question, mostly above 7000 ft. This storm exits the area Tuesday afternoon and expect precip to end with this. Winds will be strong Monday/Tuesday, but should remain below advisory. Supporting upper trough is slow to move out, with departure now looking like mid day Wednesday. Some vort maxes remain at the base of this trough moving over the area Wednesday, but just not any moisture left. PW`s should be below .20 inches. Beyond Wednesday upper ridge builds strongly over the west coast as large upper trough exits our area. Weather should remain uneventful, though with the persistent north/northwest winds aloft, temperatures will remain on the cool side. A trough does drop down to the area Friday night. Will leave POPs out of grids at this time as feature is so moisture starved. && .Aviation ...Valid 23/00Z-24/00Z. VFR conditions will continue P6SM SKC-FEW250 with winds 27010KT expected thru 18Z. After 18Z clouds will be on the increase as an upper disturbance near from the west. Expect P6SM FEW-SCT050 SCT- BKN250 along with a general increase in wind speeds from the southwest during the afternoon hours. && .FIRE WEATHER... An upper ridge will keep the region dry and somewhat mild through late Monday before our next disturbance moves in from the west. Wind speeds will be increasing across northern and western zones Monday afternoon with windy conditions prevailing most areas Tuesday... however Min RH values will remain above critical thresholds during this time span. The best chances for wetting precip will remain over the Gila and western zones Monday night and early Tuesday with a few inches of snow at higher elevations. Cooler conditions will follow for the remainder of the week. This will result in a continuation of Min RH values generally above 30 percent all areas to round out the week. Good to very good vent rates are expected Monday with stronger transport winds resulting in excellent vent rates Tuesday before vent rates drop off for the later part of the week. && .PRELIMINARY POINT TEMPS/POPS... El Paso 35 67 44 55 / 0 0 10 0 Sierra Blanca 33 68 39 56 / 0 0 0 0 Las Cruces 31 65 38 51 / 0 0 20 0 Alamogordo 32 62 38 52 / 0 0 20 10 Cloudcroft 27 45 24 36 / 0 0 30 30 Truth or Consequences 31 59 36 48 / 0 0 20 0 Silver City 28 54 29 39 / 0 20 70 30 Deming 29 64 35 50 / 0 0 30 0 Lordsburg 30 63 34 50 / 0 0 50 20 West El Paso Metro 34 67 41 54 / 0 0 10 0 Dell City 30 68 38 56 / 0 0 0 0 Fort Hancock 33 72 39 59 / 0 0 0 0 Loma Linda 34 61 38 50 / 0 0 0 0 Fabens 31 69 39 56 / 0 0 0 0 Santa Teresa 32 66 39 54 / 0 0 20 0 White Sands HQ 34 65 41 53 / 0 0 10 0 Jornada Range 26 63 36 51 / 0 0 10 0 Hatch 30 64 37 50 / 0 0 20 0 Columbus 31 67 38 53 / 0 0 20 0 Orogrande 33 65 40 53 / 0 0 10 0 Mayhill 30 55 30 42 / 0 0 20 20 Mescalero 28 55 29 40 / 0 0 30 30 Timberon 26 53 28 41 / 0 0 20 20 Winston 25 52 27 39 / 0 10 60 20 Hillsboro 30 58 33 45 / 0 10 40 20 Spaceport 25 61 35 49 / 0 0 10 0 Lake Roberts 21 47 24 37 / 0 20 70 30 Hurley 28 57 32 42 / 0 20 60 20 Cliff 26 57 30 47 / 0 20 70 20 Mule Creek 24 53 29 43 / 0 20 70 20 Faywood 29 59 32 44 / 0 20 50 20 Animas 30 66 36 52 / 0 0 50 20 Hachita 28 66 35 50 / 0 0 40 10 Antelope Wells 31 67 36 52 / 0 0 40 0 Cloverdale 34 62 35 47 / 0 0 60 20 && .EPZ WATCHES/WARNINGS/ADVISORIES... NM...None. TX...None. && $$ Hefner/Laney
Area Forecast Discussion
National Weather Service Grand Forks ND
937 PM CST Sun Jan 22 2017 .UPDATE... Issued at 933 PM CST Sun Jan 22 2017 Main issue for the 10 PM update is to begin cutting counties from the dense fog advisory as visibilities for all but Roseau County have improved...with Warroad continuing to show 1/4 SM. Will need to watch counties to the as as Baudette and Waskish have both dropped to 1/2 SM and HRRR guidance had shown this trend but was way too early in timing. Southwest winds not too far behind and once Warroad switches, expect vsbys to improve. With the winds switching over the next hour or two will hold off on adding counties to the east. Also lowered temps in the west a deg or two. UPDATE Issued at 615 PM CST Sun Jan 22 2017 Forecast issue for immediate short term will be dense fog headlines. Some sites have seen an increase in visibility and HRRR does slide lower vsbys eastward while the GLAMP25 guidance improves things gradually in the current area but does not advect the lower vsbys eastward. I prefer the latter...the question is when and how much improvement will we see in the advisory timeframe. At this point, cigs are ranging from 1/4 SM to 3/4 SM along and north of Hwy will keep things in place considering the calm winds...and monitor/consider for early cancellation later in the evening. Only change to ongoing forecast will be to re-run ForecastBuilder to yield snow over freezing drizzle given presence of ice aloft. && .SHORT TERM...(This evening through Monday) Issued at 255 PM CST Sun Jan 22 2017 Fog and light pcpn chances again the main issue for tonight. Narrow band of dense fog just east of the valley showing signs lifting. To the east of this band visibility good so unsure at this point if this band will spread east or continue to lift. For now with improving vsby will allow dense fog advisory expire and will maintain mention of fog through evening to be safe. Weak mid level shear axis skirting the international border mainly affecting far northern Minnesota portion of the forecast area. Weak lift with this feature, Colder air aloft and marginally sufficient RH through the column feel that feel p-type will be mainly snow although cannot rule out a brief mix. Anticipating that snow will be main p-type not feeling there will be any travel issues however evening shift will have to monitor. Elsewhere just looking at mainly clouds overnight. With weak cold advection temperatures will be cooler than previous nights with minimums blo freezing overnight so any wet roadways may get slick. Monday should be mainly quiet with temperatures generally at or blo freezing. Introduced some slight pops across the far sw late in the day as the leading edge of snow shield from next system may reach this area by evening. .LONG TERM...(Monday night through Sunday) Issued at 255 PM CST Sun Jan 22 2017 Watching system ejecting from the Rockies Mon night with latest operational and ensemble guidance indicating the best potential for heaviest QPF will be south of the region. The far southern FA (south of I-94) could receive perhaps one to three inches of snow during Tue/Tue night. The ECMWF has been pretty consistent with a more progressive southern track while the GFS, as often is the case, has been gradually trending farther to the north. The main upper low will move by to the south, but several weak reinforcing shortwaves will be rotating through during the period. This will bring some light snow at times, but pcpn should be very light with minimal accumulations. The shortwaves will also help shift surface winds to a more northwesterly direction and bring some cold air advection dropping mid week temps into the low and mid 20s, still above seasonal averages. (Thu-Sun) Cyclonic flow lingering into Thu could still produce some light snow/snow showers east of the valley. Otherwise dry weather to prevail from Fri into the weekend with temps climbing to the mid and upper 20s for Sat/Sun. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 615 PM CST Sun Jan 22 2017 IFR cigs with vsbys fluctuating from IFR to MVFR in the FAR/TVF/BJI areas. A small hole in the clouds over DVL is working east along Hwy 2 and may cause a break in MVFR cigs over GFK later in the evening but this will be short lived. Expect primarily MVFR around and west of Grand Forks. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...Dense Fog Advisory until midnight CST tonight for MNZ005. && $$ UPDATE...Speicher SHORT TERM...Voelker LONG TERM...WJB AVIATION...Speicher
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
520 PM CST Sun Jan 22 2017 .SHORT TERM...(This evening through Monday) Issued at 316 PM CST Sun Jan 22 2017 An area of low stratus clouds has persisted just to the east of the area across eastern Nebraska this afternoon. Models indicate this area of stratus expanding westward after sunset, and could possibly move into eastern portions of north central Nebraska around Ewing...O`Neill and Bartlett this evening. Patchy fog could also develop along and just west of the leading edge of the stratus. The time lagged RAP model has been indicating a swath of 1/4 mile visibility across much of Holt and Boyd counties around midnight onward. Patchy fog has been added to the forecast to account for this. Will pass the concern along that it is possible that dense fog could form just west of the stratus field across this area. Storm system will be organizing Monday to the west of the area. Mid level clouds will spread/develop eastward across the region ahead of the system, so a mostly cloudy day is expected. Nevertheless, warm temperatures aloft and deep mixing will promote a very mild day, with highs in the mid 40s and even lower 50s across southwest Nebraska. South winds will also increase ahead of the system, with gusts over 20 mph during the afternoon hours. .LONG TERM...(Monday night through Sunday) Issued at 316 PM CST Sun Jan 22 2017 The main sensible weather concern in the long term period revolve around a prospective winter storm affecting the region Tuesday- early Wednesday. The main challenges with this upcoming system, outside of reconciling model differences, include: precipitation type/changeover, location/timing of heaviest snowfall, and snow amounts. Higher confidence in winds with this system with gusts forecast up to 35 mph. Notwithstanding some uncertainty as models continue to show differences in the large scale pattern, there is increasing confidence that the system will impact portions of western and north central NEB. The latest deterministic guidance and ensembles have started to show less spread than the previous days, however, the envelope of solutions still encompasses a moderate area that could be affected by the cyclone. As such, a winter storm watch was issued across the northernmost counties of the local forecast area, also Garfield and Wheeler counties, given the confidence level so far. Beyond Wednesday, minimal sensible weather impacts are anticipated with temperatures expected to gradually trend upwards this weekend. An upper trough will be entering the Northern and Central Plains Monday Night with a closed low expected to develop across the Central High Plains early Tuesday. The mid-level low is expected to move eastward and then lift into southern MN/northern IA by late Tuesday then into the Upper Great Lakes midday Wednesday. Consensus shows a 700 hPa track favoring a path east across NEB into NW IA Tuesday, though there are some differences. Of note, the Canadian has the most favorable 700 hPa track for snow across the local forecast area with a track from southwest NE/northwest KS towards southeast NE, however, it appears to be an outlier compared to rest of the deterministic guidance. A surface low is expected to develop on the Central High Plains Late Monday and will move out eastward across southern NE/northern KS. The surface low is expected to reach eastern IA Tuesday afternoon. The surface low is expected to enter the Upper Great Lakes Wednesday morning. Despite aforementioned uncertainty with phase and amplitude, current thinking for moderate to heavy snowfall lies across roughly the northern-third of the forecast area where favorable deformation will occur. Furthermore, a trowal is expected to setup with the trowal axis anticipated to lie and extend westward across the center of the local forecast area from southeast NEB early on. Given the guidance, and a lean towards the WPC forecast, there is good potential for warning criteria to be exceeded (6 inches) thus the watch. Along with the falling snow, winds will be gusty on the backside of the surface low pressure system Tuesday and Tuesday night as it departs away from western NEB. Gusty northwest winds peaking up to 35 mph will promote blowing and drifting snow in areas. Snow chances then linger on into Wednesday morning. Dry and quiet weather is anticipated Wednesday and beyond. A large amplified pattern will be in place on Wednesday with a broad trough across the central CONUS and a ridge building and moving onto the west coast. Fair agreement exists in this time frame through Sunday despite some large scale differences. The upper level ridge will continue to build over the western CONUS into Saturday wherein the ridge will extend from the Pacific offshore waters near California to the Northern High Plains. The ridge is expected to dominate the Western CONUS in this time period. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 520 PM CST Sun Jan 22 2017 VFR is generally expected overnight through Monday afternoon. Some of the rapid refresh models like the RAP suggest the frontal boundary and MVFR/IFR in fog and stratus across SD will sag into Ncntl Neb late tonight. The area of concern is around KONL. The front would be aligned N/NW-S/SE if enters the area and any obscuration is expected to end by 18z as the front lifts back north into SD. Confidence is low in the MVFR/IFR forecast. This is because it is not the consensus forecast which is for VFR all areas. && .LBF WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from late Monday night through Wednesday morning for NEZ004>010-028-029-094. && $$ SHORT TERM...Taylor LONG TERM...ET AVIATION...CDC
Area Forecast Discussion
National Weather Service Omaha/Valley NE
502 PM CST Sun Jan 22 2017 .SHORT TERM...(Tonight through Wednesday) Issued at 255 PM CST Sun Jan 22 2017 Our main forecast concern is still the potential for accumulating snow Tuesday into Wednesday. Strong jetstream level winds continued from the eastern Pacific into west Texas with 300 mb winds at 12Z as high as 180 knots. System that will affect our area Tuesday into Wednesday was just starting to come onshore this afternoon. Upper air network should sample things better this evening. For tonight in our area, low clouds have been lingering over much of the forecast area through 230 pm, but there has been some erosion west of Highway 81. RAP low level relative humidity progs were used as a proxy for expected cloud cover tonight. There could also be some fog, but will not issue an advisory at this point. Monday could remain partly to mostly cloudy but allowed highs to reach into the 40s at all locations. There is still some model variability in regards to what latitude the system will move across the plains and produce significant snow for Tuesday into Wednesday. The general consensus in regards to the track of the surface low and heaviest QPF has shifted south, compared to 12 hours ago, although the 12Z GFS suggested things would remain farther north. Nevertheless, confidence increased enough and event is now close enough to issue a winter storm watch. That will be in effect for our fiver northern counties from 6 am Tuesday to 6 am Wednesday. Temperatures on Tuesday should reach the 40s in our southern zones and 30s north. Suspect that accumulations during the daylight hours of Tuesday should be limited to maybe 2-3 inches northwest of a line from about Albion to Wayne. Then accumulations should spread into more of the area Tuesday night. As mentioned earlier, the track of surface low suggested by a model blend (except not using the 12Z GFS) would normally put the heaviest snow across northern Nebraska, southern South Dakota and then toward northern Iowa/southern Minnesota. That is our thinking for now. Model forecast soundings were not overly helpful, since there will probably be dynamic cooling of the column in the afternoon. North/northwest winds will be increasing across northeast Nebraska in the afternoon and over all of the area for Tuesday night. It is the combination of snow and wind that we are most worried about, and thus the winter storm watch. .LONG TERM...(Wednesday night through Sunday) Issued at 255 PM CST Sun Jan 22 2017 The chance for any significant precipitation in this period seems pretty low at this time. Current timing would end snow before Wednesday evening, as the system pulls east. 500 mb pattern starts out with a block over southwest Canada and a trough from Ontario back into the central Plains. That ridge is expected to strengthen and build slowly east through Saturday. Highs will start out in the 20s and 30s for Thursday, then moderate to the 30s or lower 40s by Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 500 PM CST Sun Jan 22 2017 MVFR cigs finally clear KOMA to the east just before TAF issuance. Those cigs are forecast to return to eastern Nebraska after 06Z, reaching KOMA and KOFK by 08Z or so, then to KLNK by 12Z. Cigs will likely be in the FL010 to FL015 range, with some minor vsbys restrictions in fog of about 4SM. A gradual erosion of clouds should bring VFR conditions back to the area before 18Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Winter Storm Watch from Tuesday morning through late Tuesday night for NEZ011-012-016>018. IA...None. && $$ SHORT TERM...Miller LONG TERM...Miller AVIATION...Dergan
Area Forecast Discussion
National Weather Service Reno NV
246 PM PST Sun Jan 22 2017 .SYNOPSIS... A strong winter storm will impact the region through early Monday, bringing heavy snowfall to the Sierra and periods of moderate snow for western Nevada. Light snow is possible Tuesday and Thursday but overall dry and cold weather is expected for the middle to end of the week. Strong valley inversions will develop next weekend. && .SHORT TERM... The Forest Service Sierra Avalanche Center issued an Avalanche Warning for the Sierra backcountry in effect through at least tomorrow morning. Heavy snowfall rates and strong ridge winds have created high danger with potential for avalanches to be large, deep and run long distances. Travel near avalanche terrain is strongly discouraged. As the moisture stream shifted south earlier today heavy snow decreased over the I-80 corridor but continued across Mono County with highway 395 closed earlier today between Bishop and June Lake. Current radar shows a north-south cold frontal precipitation band has moved onshore which stretches north to the Oregon border. Meanwhile the air mass upstream has been unstable enough for a thunderstorm to develop north of Sacramento. High resolution HRRR model captures these features well which increases confidence that heavy snow will redevelop in the Sierra this evening from the Tahoe Basin south to across Mono County. The winter storm remains in effect for these locations due to hazardous travel conditions and whiteouts, including for I-80 over Donner Summit and for highway 395 in Mono County. For locations east of the Sierra and north of Mono County, and also north to the Sierra and Surprise Valleys, the unexpected break in precipitation today (the colder air mass was slow to arrive) allowed the snow level to remain higher than expected. Some valley temperatures rose into the mid 30s to lower 40s. The high resolution models indicate the precipitation this evening will come in the form of bands, reaching the highway 395 corridor between 4 and 6 pm and then spreading across the rest of west NV. Because of the higher snow levels and the banded nature of the precipitation, the winter storm warnings for these areas were downgraded to winter weather advisories. These winter warnings and advisories continue until 4 AM Monday morning. Even though snow rates will decrease after 4 AM, there is still potential for hazardous road conditions for the tomorrow morning commute, especially in the mountains. Please check road conditions before leaving home. Latest model simulations show potential for a "slider"-like system Tuesday morning. Predictability is low and moisture will be very limited so it may create only snow flurries with little to no accumulation. However, there is some potential for snow bands to create a quick inch or two of snow which could impact the Tuesday morning commute. JCM .LONG TERM...Wednesday through Sunday... A weak system could still slip under the Pacific Northwest/British Columbia ridge on Thursday and bring some snow showers to northeast CA and western NV. This a low confidence event due to the weakness of the impulse and variance in position among simulations. Friday through Sunday, an upper ridge strengthens over the region for dry conditions. With light winds and subsidence warming under the upper ridge, inversions are expected to strengthen by late week. Freezing fog and stratus are definite possibilities in valley locations, especially those that receive more than a few inches of snow by tonight. Expect poor mixing and particulate build-up in the lower valleys with possible reductions to air quality by next weekend. The good news for those trying to dig out of the incredible amount of snow that had fallen this month is that the long range forecast keeps the area dry through the start of February. As a low confidence heads up, there are some indications that moisture and storms will return to northern California and western Nevada in the February 3rd to 7th time range. Snyder/Dawn && .AVIATION... A second round of organized snow, with a mix of rain and snow below about 5000 feet MSL, is expected after about 00Z/4 PM PST. This should bring one more extended period of extensive terrain obscuration and conditions below airport mins for the northern Sierra including KTRK/KTVL...with Sierra terminals farther south (including KMMH) possibly not seeing a break at all through tonight. Snowfall totals tonight for the KTRK/KTVL terminal areas could reach an additional 5 to 8 inches, with at least 8 inches possible for KMMH. Conditions finally begin to improve Monday with more sporadic snow showers, especially by later morning and in the afternoon. For western and west-central NV, temperatures below 5500-6000 feet have warmed up enough to pretty much eliminate snow accumulations on paved surfaces and tarmacs through the afternoon. The main concern through afternoon will be terrain obscuration in occasional -shsn or -shrasn/-shra below about 5000 feet. For this evening, however, one final wave of snow is expected with intensities possibly moderate to heavy at times. This could bring a quick few inches of snowfall to terminal areas, with slushy accumulations on paved surfaces/tarmacs after dark. After midnight, conditions should improve as an upper disturbance moves off to the east. With a strong jet overhead, turbulence aloft is likely through this evening over the entire region. Some mechanical mixing turbulence is also possible into evening closer to the deck with gusts up to around 25-30 kts. Snyder && .REV Watches/Warnings/Advisories... NV...Winter Weather Advisory until 4 AM PST Monday NVZ005. Winter Storm Warning until 4 AM PST Monday NVZ002. Winter Weather Advisory until 4 AM PST Monday NVZ001-004. Winter Weather Advisory until 4 AM PST Monday NVZ003. CA...Winter Weather Advisory until 4 AM PST Monday CAZ071. Winter Weather Advisory until 4 AM PST Monday CAZ070. Winter Storm Warning until 4 AM PST Monday CAZ073. Winter Storm Warning until 4 AM PST Monday CAZ072. && $$ For more information from the National Weather Service visit...
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