Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/08/19

National Weather Service Albany NY
956 PM EST Thu Feb 7 2019 .SYNOPSIS... Rain will continue across eastern New York and western New England overnight with isolated thunderstorms also possible ahead of a warm front. It will turn blustery and colder tomorrow into Saturday with some lake effect snow likely. Seasonable temperatures with increasing clouds for Sunday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 955 pm EST...A region of upper level diffluence continues to be over the region ahead of a strong upper level trough. Deepening sfc low pressure according to the latest RAP is 992 hPa moving into south/southeast Ontario. The isentropic lift continues to increase over the forecast area with mainly light to occasionally moderate rain overspreading it ahead of the warm front. A brief lull is possible over the southern most zones, but that should fill in quickly again based on the latest 3-km HRRR. Some higher elevation sites remain near freezing over the southern Greens and extreme northern Berkshires. We did issue a Special Weather Statement for a brief period of freezing rain to around midnight for some light ice accretions at elevations 2000 feet or greater. Temps remain mainly in the lower to mid 30s to lower to mid 40s. They should be steady or slowly rise overnight. The strengthening low-level jet should help some warmer air reach these higher elevations. Also, the 00Z NAM continue to have Showalter stability indices 0 to -2C especially over the southern zones. We changed the slight chance of thunderstorms back until after midnight. A rumble or two is possible with the elevated instability. Previous near term... AN upper-level trough which will become sharply negatively tilted and close off as we head into the overnight. This will result in the low deepening as it as it tracks toward James Bay. Attendant low- level jet in the warm sector will spread into the area with another surge of moisture as PWATs increase to 1-1.25 inches throughout the forecast area. This is +3 to +5 standard deviations per the NAEFS. Fortunately, this system is a rather quick-hitter, so do not expect excessive QPF (see hydro discussion below). Some showers are also possible ahead of the approach of a strong cold front very late tonight into Friday morning. Showalter indices go slightly negative overnight, so we could hear a rumble of thunder or two, with locally heavy downpours possible. Temps will remain steady or rise somewhat late tonight, quite mild in the mid-30s to mid- 40s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... Wind Advisory in effect for portions of the southern Adirondacks, Mohawk Valley, Schoharie Valley, Capital District, and Helderbergs 1 pm Friday through 1 pm Saturday... A strong cold front Friday morning will drop H850 temps by around 15-20C in 12 hours. While temperatures at the surface may spike early in the morning immediately behind the front due to mixing, strong cold advection should drop temperatures in most areas by the afternoon. A strong post-frontal pressure gradient will set up with deep mixing encouraged by robust cold air advection. Forecast soundings suggest average wind speeds in the mixed layer increase to 30-40 kt Friday afternoon through early Saturday afternoon, with winds at the top of the mixed layer reaching about 50 kt. 6-hour pressure rises are around 5-8 mb from around 18Z Friday to 06Z Saturday, which is respectable. The core of the strongest winds aloft moves in Friday night past the diurnal maximum, but continued cold air advection may continue to support downward momentum transport overnight. While forecast gust values are borderline for advisory criteria, they will occur over a rather long period. A Wind Advisory was issued for the Mohawk Valley/Southern Adirondacks, as well as the Capital District into which the winds tend to funnel from down the Mohawk Valley. The advisory may need to be expanded into portions of the Taconics/western New England, but will hold off for now per collaboration with surrounding offices. Most of the precipitation from tonight`s system should have moved east by the time the colder air moves in. However, lake effect parameters will become increasingly impressive Friday afternoon into Friday evening, with surface to 850 mb delta-Ts increasing to 20C and inversion heights up to 2 km. Winds in the 0-3 km layer will be veering with time, so do not expect a band to remain stationary over a period of time, which should limit accumulations. Late Friday night into Saturday morning, local inland extent program supported by CSTAR research is indicating values near 170 miles, so we could even see a band reach the Capital District to western New England briefly. Wind chills Friday night likely will fall into the single digits above and below zero. Saturday will be continued blustery and seasonably cold, although expanding high pressure will result in sunshine and winds diminishing in the afternoon. The associated subsidence should quickly put an end to any lingering lake effect activity. Highs in the 20s to lower 30s will be back a bit below normal values. Saturday night looks somewhat favorable for radiational cooling, although the center of the strong 1040 mb high will be located to our south over the Mid-Atlantic. Lows in the single digits and teens will be common, with some below-zero readings over the higher terrain. Seasonably cold and tranquil conditions continue Sunday, with clouds increasing late as the high shifts offshore. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... The highlight of this period will be a possible major winter event toward mid-week. Things start off dry with high pressure stretching from western Canada all the way to the northeastern U.S. Sunshine will be the rule on Monday. Meanwhile low pressure is expected to develop off the Colorado Rockies, broaden and intensify as it makes its way towards the northeastern U.S. Models are pretty much in lock-step concerning progression of this system and the fact that it will pretty much all snow. But each model suggests moisture is limited, and only the GFS hints at a marginally major snow event. The relatively low-predicted QPFs is probably because the low is expected to split its energies between the main interior low and a secondary low expected to intensify off the northeast coast as it tracks up toward Cape Cod. So despite its expected widespread impact, being it`s almost a week off, have kept PoPs down in the chance category for this event. From late Wednesday on, precipitation mainly in the form of snow will be limited to the lake effect regions on a westerly flow behind the departing storm. Lake effect cloudiness, however, will likely impact the entire forecast area, though not so profoundly across the southern zones. Daytime highs Monday will range from the upper teens in the Adirondack high the upper 30s in the Mid-Hudson Valley and southern zones. For Tuesday, the high peaks will moderate by several degrees while increasing clouds result in a slight cooldown across the south. Downsloping on westerly winds behind the cold front of the departing storm will spell a warmer day for Wednesday with snow showers turning to rain showers at most locations before the cold air finally intrudes to change things back as the activity winds down. Highs Wednesday are expected to range from around 30 degrees to the mid 40s. Highs Thursday will range from the mid 20s to around 40 degrees. Sunday night lows will range from the upper single digits to mid 20s while Monday night lows will range from the lower single digits to upper teens. Upper teens to upper 20s will be the general rule for Tuesday night; upper teens to mid 20s for Wednesday night. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... Localized IFR conditions in fog can be expected at the TAF sites through about 02z, especially at GFL and POU, then rain will overspread the area around 02z with mainly MVFR conditions in rain and light fog. Areas of IFR will likely develop again late tonight as fog becomes more dense and cigs gradually lower. In addition, a period of low level wind shear can be expected this evening into the early morning hours with 30 to 35 kt southerly winds expected at above 2000 AGL and light winds at the surface. A cold front will move across the area Friday morning ending the rain with conditions improving to widespread VFR with clearing by noon. Light winds will become westerly and increase to 15 to 25 kts with gusts to 30 kts during the afternoon. Friday Night: Moderate Operational Impact. Windy With Gusts To 38.0 Slight Chance of SHSN. Saturday: Moderate Operational Impact. Windy With Gusts To 38.0 NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: No Operational Impact. NO SIG WX. Sunday Night: Low Operational Impact. Slight Chance of SHSN. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: Moderate Operational Impact. Chance of SN. && .HYDROLOGY... Another storm system will bring rain to the area tonight. Total QPF from this system is expected to mainly range from 0.25 to 0.75 inches. The modest snowmelt coupled with the modest rainfall should result in river rises. Some rivers are forecast to reach action stage, but as of now, no flooding is forecast. However, areas where ice jams exist will need to be monitored, as it is possible that the river rises could allow the ice to move, resulting in new ice jam flooding. Locally heavy downpours are possible tonight with isolated thunderstorms. By Friday into the weekend, temperatures will be back toward or below seasonal levels (mainly below freezing) with dry weather expected aside from light to moderate lake effect snow, which should once again promote ice formation and allow river levels to fall. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...Wind Advisory from 1 PM Friday to 1 PM EST Saturday for NYZ032- 033-038>040-047>053-082. MA...None. VT...None. && $$ SYNOPSIS...Thompson/Wasula NEAR TERM...Thompson/Wasula SHORT TERM...Thompson LONG TERM...ELH AVIATION...MSE/Speciale HYDROLOGY...MSE/Thompson
Area Forecast Discussion
National Weather Service Denver/Boulder CO
815 PM MST Thu Feb 7 2019 .UPDATE... Issued at 815 PM MST Thu Feb 7 2019 Forecast looks on track tonight other than the minimum temperatures. As expected the skies have almost completely cleared out across the area save some lingering capping clouds along the Divide. Winds across the Plains, especially along and east of I-25 north of Denver and along I-76 northeast of Denver to around Sterling have diminished, resulting in ideal raditional cooling processes. The areas with good snowpack are seeing temperatures already dropping like a rock with several obs showing -10 to -14 in southern Weld County, and Akron has already hit -8. Even our best numerical models have no idea how to capture the cooling rates. It will be a game of cat and mouse all night tonight with winds vs temperatures. If the winds stay up, the low temps will generally be in the single digits. If the winds go calm for an hour or two in a row before 8 AM, lows will be between 0 and -15. We`ve relied heavily on current observations to identify where the best radiational cooling is already occuring. Right now that is Weld County and the South Platte Valley into Logan County. Washington County too. Along I-25 north of Denver is also already colder than originally forecast and much colder than any model predicted. We`ve updated the grids with new overnight lows for tonight, generally undercutting previous forecasts by 4-10 degrees where we expect winds to remain light. Along the Palmer Divide, within and right next to the foothills, and across much of metro Denver (other than DIA), the minimum temperatures between 0 and 10 look good for now. There should be enough downslope and weak drainage winds plus urban effects to keep those areas from dropping too far. && .SHORT TERM...(This evening through Friday) Issued at 234 PM MST Thu Feb 7 2019 Satellite pictures are showing mostly cloudy skies over the CWA right now. Area radars indicate some snow showers developing over the mountains. Not sure how much snow is hitting the ground, mostly just flurries. Models have west-southwesterly 60-80 knot jet level flow for the CWA overnight. The jet level flow is southwesterly on Friday. The QG Omega fields have downward energy tonight, then weak upward vertical velocity on Friday. The low level wind and pressure fields show weak drainage wind patterns tonight over the plains. There is a bit of a mountain wave set-up tonight, kind of up high, but certainly decent downslope from the divide into the foothills. On Friday, southerly flow is progged over most of the plains. The rest of the CWA had weak flow level flow. For moisture, this afternoon`s cloudiness will be short lived. Cross sections show it to be pretty dry tonight and Friday. Th QPF fields show no measurable precipitation for the CWA through Friday after 03Z this evening. There is a tad in the high mountains early this evening. The thickness fields already show the cold airmass to moderate overnight and Friday`s highs look to be 5-10 C warmer then today`s readings. .LONG TERM...(Friday night through Thursday) Issued at 224 PM MST Thu Feb 7 2019 A low pressure center over the Pacific coast of CA will bring SW flow over the state through Saturday. Warm air advection will continue helping to increase temperatures. Conditions will continue to be dry Saturday with highs in the lower 40s across the plains. By Saturday night, the system over CA will progress into the Great basin as a positively tilted trough. There is moderate levels of QG with this system as a 130+ jet moves into central CO with the right entrance region over the NE. This will promote good lift and instability Saturday night into Sunday morning. Moisture will increase through the mid and upper levels that will help to bring snow showers to the mountains Saturday night and continue through Sunday morning. For the Plains, models are showing another surge of cold air dropping out of Canada that will impact CO Saturday into Sunday. Model upper air soundings show a saturated profile through 500 mb that would help to promote dendritic growth and allow for some light snow overnight Saturday. Will keep a slight chance of snow for the plains through Sunday morning with overnight lows in the teens. Temperatures will have to be monitored to account for the arctic air and how low it could bring temperatures during this period. By Sunday, the disturbance will have moved off to the NE leaving CO once again in SW flow aloft. Cooler air will prevail on Sunday with moderate subsidence and clearing. Models currently have highs in the 30s, but may have to drop lower. For Sunday night into Monday, another upper level disturbance will move SE from the Pacific NW and will be pushing through Utah Monday morning. This will increase moisture over Western CO and the central mountains bringing another round of snow to the high country. Temperatures will remain around normal for the plains with highs in the lower 40s. Entering into mid- week ridging will increase with a period of dry and slightly warmer weather into Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 815 PM MST Thu Feb 7 2019 VFR conditions through Friday. Need to mention the cold temperatures again tonight with 0 to -5 at DEN and between 0 and 5 above at BJC and APA. Winds should be in the 10 kt range out of the south at DEN until 12-14Z or so, then go light and variable. Expect weaker south winds at APA, while at at BJC they will probably remain light and variable tonight into midday Friday though west is the best direction to go with. Winds should pick up and settle on a preferred direction by 18Z, but the certainty on what that direction will be is muddied by the formation of a Denver Cyclone. Strong southerly flow across the Palmer Divide should spin up the cyclone between 18 and 19Z or so. The HRRR has been reasonably consistent at putting the cyclone and it`s line of convergence south and east of DIA. This would mean NNW winds at BJC and APA, while at DEN it they may start off ENE midday then turn to N and NNW thoughout the afternoon and evening as the cyclone migrates off further to the east of DEN. By 01 or 02Z Friday evening winds should weaken across the metro area terminals to 5 kts or less, and probably be variable direction. Tried to handle the turning winds at DEN in the TAF but confidence in the precise timing of the shifting winds is low, just hoping to get the overall pattern correct at this point in time. Drainage winds (SSW at DEN, S at APA, W at BJC) will get going again after 03Z. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Schlatter SHORT TERM...RJK LONG TERM....Bowen AVIATION...Schlatter
National Weather Service Burlington VT
938 PM EST Thu Feb 7 2019 .SYNOPSIS... Very changeable weather and temperatures anticipating the next 12 to 24 hours, before much cooler air arrives for the weekend. Tonight rain with areas of freezing rain will redevelop across the North Country as temperatures slowly warm above freezing in most locations. Ice accumulations up to a tenth of an inch possible, especially northern Saint Lawrence Valley and east of the Green Mountains. On Friday, temperatures briefly jump into the 40s, before a strong cold front with very gusty winds produce sharply falling temperatures in the afternoon. Blustery and cold conditions with mountains snow showers develop Friday afternoon into the upcoming weekend. && .NEAR TERM /THROUGH FRIDAY NIGHT/... As of 938 PM EST Thursday...Precipitation now making its way into the region. Temperatures are mainly above freezing and the precipitation will be rain...but where we have the advisories over the Saint Lawrence Valley of New York and areas east of the Greens in Vermont temperatures are either at or just below freezing. Thus freezing rain advisory continues to look good. Did issue a special weather statement earlier for parts of far northeast New York and far northwest Vermont where some light freezing rain is also possible as temperatures are slow to climb above freezing in this area. Could see a little freezing rain that produces a very light glaze on road surfaces making for slick travel. Rest of forecast in good shape. Previous Discussion... Winter Weather Advisories continues for freezing rain in the Saint Lawrence Valley and eastern Vermont tonight. Wind advisory has been issued for northern NY and most of central and eastern VT, including the Northeast Kingdom from 7 AM Friday to 10 AM Saturday. Water vapor shows digging mid/upper level trof acrs the central CONUS with ribbon of enhanced mid level moisture advects toward the ne conus. This moisture and dynamics from trof and associated jet will produce a period of rain tonight across the North Country. However, northeast winds continue to advect low level cold air down the slv with temps only in the mid 20s, so anticipate areas of freezing rain. Meanwhile, east of the greens temps will drop below freezing this evening, with pockets of freezing rain likely as the rain develops btwn 02-04z. Unlike yesterday we expect the precip to arrive aft the evening rush, so anticipating a better evening commute across the region. Winter wx advisories continue for the SLV and eastern VT tonight. Across the northern CPV (Clinton, Chittenden, Grand Isle and Franklin counties, thinking a few pockets of freezing rain is possible with initial surge of moisture, but winds quickly shift to the south/southeast btwn 00z-03z and I think temps will warm above freezing, so no advisory. However, if wind shift is delayed and temps are at or below freezing some pockets of freezing rain possible, especially northeast Clinton County. Unlike yesterday, qpf will be lighter this event with precip ranging from 0.10 to 0.30 of an inch and total ice accumulation up to a tenth of an inch in the advisory areas. Temps will be complex and challenging with lows generally this evening, before warming occurs after midnight with many locations above freezing. Lows mid 20s SLV/northern CPV to near 30F east of Greens to mid 30s midslopes/ridges with readings warming into the mid 30s to mid 40s by sunrise. Would not be surprised a few readings near 50f across the western dacks/slv near Potsdam/Canton areas. Friday-Friday Night...A mature sub 980mb low pres will quickly lift across the northern Great Lakes and toward Hudson Bay by 18z Friday. Precip will quickly end by 12z as well defined mid/upper level dry slot develops from west to east. This dry slot combined with steepening low to mid level lapse rates associated with strong llvl caa will produce strong/gusty west winds. 15z Rap soundings show bottom of the mixed layer btwn 40-45 knots across northern NY by noon on Friday, which spreads into Vt on Friday aftn/evening. Have noted gusty winds come in several surges with 1st surge btwn 15z-21z Friday, next period around 03z, with the potential strongest surge occurring btwn 09-15z Sat associated with 850mb winds of 60 to 70 knots. Based on this have issued wind advisory for northern Dacks/SLV and locations east of the Greens in VT from 12z Fri to 15z Sat for localized wind gusts up to 50 mph. Thinking strongest wind gusts will be on the east side of the Green Mountains from Ludlow to Waitsfield to Stowe to Newport, with secondary axis of strong winds across the Northeast Kingdom and parts of the lower CT River Valley. Meanwhile, localized gusts up to 50 mph are expected over portions of the SLV and downslope regions of the northern and eastern sections of the Adirondack Mtns. Isolated power outages are possible in the advisory areas from Fri morning into Sat. Expecting a roller coast ride in the temp depart on Friday with warmest values in the morning, before strong cold air advection develops and temps tumble. Based on thickness values reaching 550 to 552 and progged 850mb temps btwn 6-8c around 10z Friday, would not be surprised a few sites touch 50f or so, especially in the southwest to southeast downslope regions. Temps will quickly come crashing down by 18z Friday, with 925mb to 850mb values falling below 0c and near -15c at 850mb by 00z Saturday. Temps should be below freezing all locations by 00z, with summits in the single digits to mid teens. Any precip will become scattered and confined to the mountains on Friday into Friday night. Upslope snow will be limited as moisture profiles and associated qpf are minimal. Maybe an inch or two across the northern Greens and portions of the western Dacks. Some lake effect snow showers are possible as flow aligns off Lake Ontario and colder thermal profiles develop, especially on Friday Night. Given short duration warm up and qpf amounts generally under 0.50 not expecting any hydro related issues. However, cannot completely rule out minor low lying flooding associated with an isolated freeze up jam on a local waterway. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... As of 253 PM EST Thursday...The weekend will be cold and dry as high pressure settles across the North Country. A few snow showers may linger in the Northeast Kingdom Saturday morning, but overall anticipate drying as moisture decreases behind low pressure departing over the Maritimes. Skies will gradually clear as well, but temperatures will only top out in the teens and 20s for highs. It`ll be quite windy as well, with a 50+ kt 850mb jet skirting across the region. This combined with mixing due to cold air advection will result in brisk west to northwest winds through at least the first half of the day, gradually subsiding late in the afternoon and evening. Winds will continue to lessen overnight Saturday night as high pressure builds in and the pressure gradient relaxes. Lows will be in the single digits, below zero in the Northeast Kingdom and Adirondacks and above zero elsewhere. Sunday will see increasing clouds and temperatures a few degrees warmer than Saturday`s readings. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 253 PM EST Thursday...Things become a bit more active for next week as the high builds to the east of the region. A shortwave trough will rotate through the quick flow aloft. The GFS is a bit more amplified with this feature and produces some light QPF across our region Sunday night, while the ECMWF and CMC both keep the best forcing with the shortwave to the north. Have stayed with just low chance PoPs at most for this time period. Either way, the high becomes reestablished for Monday and Monday night, with dry weather to prevail. Our next best chance for precipitation arrives Tuesday as an upper trough digs to our west. Surface low pressure will scoot across the Great Lakes while a secondary low develops off the Mid Atlantic coast Tuesday night. These two lows will both shift northeast, so the question will be the relative strength and placement of the secondary low and hence mixed precipitation potential. At this time, the secondary low is of sufficient strength and is far enough east to keep cold air across the North Country, resulting in just snow for later Tuesday and Tuesday night. However, if the primary low is able to advect warm air northward into northern New England before the secondary takes hold, a wintry mix will be possible. There has been some run-to-run differences with these two scenarios, so this system will need to be monitored. Regardless, once the lows move to our east, we`ll see northwest flow and upslope/mountain snow showers Wednesday into Thursday. Temperatures through the period will be near to below normal. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... Through 00Z Saturday...A wide range of conditions exists with IFR to LIFR ceilings across the area and MVFR to LIFR visibilities. Through 04z there will be periods of VLIFR ceilings and visibilities across northern New York before the precipitation moves in. As precipitation spreads from southwest to northeast it will be a mix of rain and freezing rain before transitioning to all rain between 06z and 10z. The precipitation moves east of the area between 10z and 14z...which is when ceilings and visibilities improve sharply into the VFR category. At that time winds will start to get gusty from the south and southwest...with windy conditions develop between 18z and 20z as winds become more westerly and we see gusts in the 25 to 35 knot range for the remainder of the period. Outlook... Friday Night: VFR. Windy with gusts to 35 kt. Slight chance SHSN. Saturday: VFR. Windy with gusts to 30 kt. NO SIG WX. Saturday Night: VFR. NO SIG WX. Sunday: VFR. Slight chance SHSN. Sunday Night: Mainly VFR, with local MVFR possible. Chance SHSN. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. Chance SN. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Winter Weather Advisory until 7 AM EST Friday for VTZ003-004- 006>008-010-012. Wind Advisory from 7 AM Friday to 10 AM EST Saturday for VTZ003-004-006>008-010-012. NY...Winter Weather Advisory until 7 AM EST Friday for NYZ026-027- 087. Wind Advisory from 7 AM Friday to 10 AM EST Saturday for NYZ026-027-029>031-034-087. && $$ SYNOPSIS...Taber NEAR TERM...Evenson/Taber SHORT TERM...Hastings LONG TERM...Hastings AVIATION...Evenson/LaRocca
Area Forecast Discussion
National Weather Service Caribou ME
1102 PM EST Thu Feb 7 2019 .SYNOPSIS... A large area of low pressure will track from the Great Lakes northeast into western Quebec tonight then into central Quebec on Friday. High pressure will build in from the west Saturday into Sunday. && .NEAR TERM /THROUGH FRIDAY/... 1045 PM Update... Adjusted the hrly temps/dewpoints to fit the latest obs. Overnight temps look like they will hold in the 20s across the northern 1/2 of the CWA while 30s will hold further south. Light snow was occurring across far northern areas but there are signs that light snow is beginning to transition to a period of light sleet or even freezing drizzle. The latest RAP and LAPS sounding show warm layer aloft w/the potential for freezing rain overnight w/some icing, even as far south of Lincoln and Bangor. Icing potential across the Bangor and Downeast region will be short lived as warmer pushes in from the Gulf of Maine. Sfc analysis showed high pres to the ne wedging down into Maine while low pres lifts up across central Canada. This setup is good for a freezing rain scenario w/an icing threat. Given the latest setup, temps might struggle to warm above 32F Thursday morning w/icing being prolonged especially across the Crown of Maine. Therefore, ice accumulation could easily hit one tenth of an inch. Stayed close to the latest setup w/light snow going to a period of sleet and then freezing rain across the northern and Central Maine Highlands, while Bangor and Downeast should transition to rain by daybreak. Previous Discussion... A very large area of low pressure lifting up to our west tonight will pull deep moisture back over the region. High pressure over the Maritimes combined with a weak triple point low moving into the Gulf of Maine will hold cold air onto the surface as precipitation moves in overnight. A mix of light sleet and freezing rain is expected, with boundary layer temperatures warming from south to north overnight. By dawn Friday morning a bit of freezing rain will persist in far northern Maine while plain light rain and some fog will cover the rest of the area to the south. The freezing rain will likely make mostly untreated surfaces, especially driveways, cars and walkways icy. The precipitation will slide east into the Maritimes Friday as the occlusion pushes east. A corridor of dry air will push into the area during the midday and afternoon Friday. This will bring a partly sunny and mild early afternoon before cooler air starts pushing in from the west on gusty westerly winds. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... Fropa occurs late Fri aftn with very steep low-lvl lapse rates resulting in mixing up to nr H8 Fri night. Advisory level wind gusts look to be a pretty sure bet drg this timeframe. Highs on Sat wl be significantly colder than Fri on the order of 25-30 degrees. May see isold snow showers in upslope areas Fri night into Sat as wnw flow conts. Possibility exists for streamers coming off of the St. Lawrence thru the weekend. Pressure gradient wl gradually weaken on Sunday with wnw still rmng gusty but significantly less than earlier in the pd. Temps wl be warmer than Sat but still much blo normal even under full sun. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... High pressure builds offshore of the Delmarva on Wed with another hipres center builds in fm Canada on Monday. GFS bringing upr lvl low into Quebec on Mon with isold-sctd pops mainly ovr Downeast drg the day while EC and CMC much further east and weaker with upr system. For the time being hv gone with a dry fcst for early in the week. Regarding the mid-week system pcpn is fcst to mv into swrn Maine Tue night as light snow. EC and GFS are both indicating a double-barrel low structure on Wed but are having a hard time with the interaction btwn the nrn and srn streams this far out. && .AVIATION /04Z FRIDAY THROUGH TUESDAY/... NEAR TERM: IFR to LIFR conditions in low clouds are expected tonight into Friday morning. Conditions should improve to MVFR late Friday morning, then VFR Friday afternoon. Gusty winds following the passage of an occlusion may result in turbulance Friday afternoon. SHORT TERM: VFR through the end of the period at all terminals. MVFR restrictions possible over the far north Fri and Sat in low stratus. && .MARINE... NEAR TERM: Winds will increase to SCA tonight then remain SCA much of Friday. Increasing westerly winds will begin to approach gale late in the day on Friday. SHORT TERM: Gale warning in effect Fri night into Sat night. Winds diminish to SCA conditions through Mon night. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory until 10 AM EST Friday for MEZ001>004. Winter Weather Advisory until 8 AM EST Friday for MEZ005-006- 010-011-031-032. Winter Weather Advisory until 6 AM EST Friday for MEZ015>017. MARINE...Gale Warning from 5 PM Friday to 7 PM EST Saturday for ANZ050>052. && $$ Near Term...Hewitt Short Term... Long Term... Aviation...Hewitt/ Marine...Hewitt/
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
654 PM EST Thu Feb 7 2019 .AVIATION... VLIFR fog aggressively set in late this afternoon as warmth and humidity was drawn over the shallow surface based cold layer. Impressive surface warm front for beginning of February with DUH and TOL reporting 55/55. This fog will last for another couple of hours before post-cold front mixing scours out surface layer moisture. Convective fine line exists along the surface cold front that is steadily marching into central Lower Michigan. Timing of the cold front has the feature at the western edge of the CWA around 00-01Z and through the far eastern cwa sometime around 03Z. Organization of the cold front is interesting with a couple of dominant channels in KGRR 0.5 reflectivity. The channels signify there are no stability concerns immediately behind the front and low to midlevel subsidence will be unimpeded in its descent to the surface. Best potential for strongest SW wind gusts of 45 knots will exist south of I 94 with frontal passage. The front has surged through TTF and JXN so it appears set to make it through I 94. 900-800mb cold advection will be lagged by a few hours. As as result, mixing depths will increase during the course of the evening and expect winds to steadily increase with this cold air. Most likely area to experience highest wind gusts later on will be north of I 69 between 03-06Z. Cigs should quickly improve this evening predominate MVFR conditions. Lake effect snow shower potential will then increase after 10Z with a decent signal for supersaturation with respect to ice through the - 10 to -15C window. There will likely be a diurnal component to lake effect by midday. For DTW...Warm front will surge through DTW momentarily which may provide a relief from dense fog. Otherwise, strong surface cold front to blast through at 02Z, which will bring SW winds, potentially in the 38 to 43 knot range. Strong SW winds to continue tonight. Low confidence exists in lake effect snow potential beginning 17Z Friday. .DTW THRESHOLD PROBABILITIES... * High for cigs below 5kft through the TAF period. * High for ptype of rain this afternoon and early evening. * High for cigs 200 ft or less and/or visibility 1/2 SM or less until approximately 02z. * Low in thunderstorm occurrence and timing 23z-02z. && .PREV DISCUSSION... Issued at 354 PM EST Thu Feb 7 2019 DISCUSSION... Deepening phase of a particularly dynamic cyclone is underway with system-relative pressure falls of 4mb in the last 3 hours as the surface low moves over Chicago at press time. Latest mesoanalysis indicates a 140-155 kt upper jet in the lee of the approaching trough anchoring a mature jet-front system that extends to the surface where it is defined by a razor sharp baroclinic zone. Fast propagation of gravity waves on Ch 2 is a testament to intense upper- level shear with looping offering a pristine look into the bifurcating warm conveyor beneath a stout descending dry airstream. Another testament to the strong dynamic response is the emergence of a lead PV anomaly adjacent and parallel to the cyclonic side of the upper jet. These features are result of fgen processes taking place at jet level, and the forcing is usually apparent in modeling in the form of lower stratospheric (e.g. 200mb) frontolysis where the descending branch of the thermal circulation can be seen drawing higher PV air downward in advance of the parent PV feature over the Upper Midwest. Dry intrusion has scoured out meaningful precipitation in the winter wx advisory, which will be cancelled. Lingering freezing drizzle will end with temperatures at 32 and rising. In the meantime, the CWA will remain socked in north of the warm front with widespread fog which has been locally quite dense at times per reports in the Novi area earlier today. The upstream cold front will sweep through the CWA between 00-02z, by which time the surface low is progged to be invof the Straits and deeper by another 8mb. The expansive momentum field around the deepening surface low is forecast to have no issue being forced groundward as 850mb temperatures plummet by 20C in the 6 hours following fropa and another 10C in the following 12 hours. The net change of -30C or more will support persistent strong isentropic descent that will continue well into Friday, slowly diminishing in intensity as the low pulls away during the morning. Wind gusts around 45 mph are a foregone conclusion at this point, and the wind advisory has been extended to the southern border. There are two pressing questions with regard to wind potential in the near term, both revolving around the frontal passage itself. The first is the extent to which the warm front is forced north into the CWA given the resident extremely stable airmass. Cross-sections indicate a rather gentle top-down transition to the incoming airmass north of the warm front while any locations in the warm sector will be exposed to a very dynamic surface front. Unstable mixing within the elevated nose of the surface front will be capable of causing a very transient higher end pop of wind upon its arrival. Fortunately, limitations in available momentum in the lowest couple thousand feet will likely cap potential at around 50 mph. The 18z NAM has made a move toward the more aggressive HRRR depictions which indicate the warm sector reaching the M59 corridor between 00-02z, which is reasonable. M-59 south is therefore the corridor within which a brief higher end gust potential will exist during fropa. The second issue is potential for low-topped convection. Deeper convective mixing would yield a low end severe threat. However, convection has been observed to struggle along the front this afternoon and with strongest dynamics rapidly shifting north, strongly suspect that convection will not be an issue. Confidence is further increased by low inversion heights to begin with. Finally, the wind advisory has been extended to 15z Friday morning. The 09-15z period will feature a waning gradient, but developing instability, especially after sunrise, will likely force the regional boundary layer into the typical large eddy outcome. Resultant HCRs, aided by Lake Michigan influence, will carry the potential to produce localized gusts reaching or nearly reaching wind advisory criteria through at least mid-morning. Though the dynamic support will continue through Friday, the diminishing gradient will cap wind gust potential below advisory level by late Friday morning. Wind chills will fall below zero by sunrise Friday where they will stay as temperatures plummet from the 40s today to near 10 by Friday evening. Modest overlake instability and poor convective depths will support scattered to numerous snow showers and flurries through the day Friday with little to no accumulation expected. Extended...Return flow from a departing high pressure system centered across the western Atlantic to allow temperatures to slowly rebound back back into the upper-20s for a high Sunday and back into the lower- 30s Monday across the Metro area. Cooler conditions will hold in place across the Tri-Cities into the Thumb with daytime highs in the mid-20s. Weak frontogenetic forcing in the low to mid-levels coupled with right entrance jet streak dynamics and the quick passage of a weak shortwave will provide the likely chance for snow Sunday night into early Monday morning. Roughly an inch of snowfall accumulation is expected across SE MI with the passage of the shortwave. Otherwise, a Canadian high pressure system will overspread the northern Great Lakes Monday afternoon into the evening and will act to diminish snow chances as the shortwave moves east into New England. A strong PV anomaly preceding a surface low will cross the Plains and travel east into the Great Lakes Tuesday into Wednesday and will bring the next likely chance for precipitation. This upper-level IPV anomaly will travel over a region a strong baroclinicity across the Plains and will help reinforce and strengthen low-level circulation. Long-range models still have not converged on timing of precipitation, but the Tuesday morning into Tuesday night timeframe looks good to see the bulk of precipitation. Internal top-down methodology still consistent will ptypes, starting all precipitation as snow in the morning before transitioning over to a rain/snow to rain solution by the afternoon as a nose of above freezing air enters in the low-levels ahead of the low. A cold front is then expected to sweep across Michigan as the low travels northeast into Ontario, which will act to bring the chance for lake effect snow throughout Wednesday as well as gusty conditions. High pressure to then build in across the Plains into the Great Lakes which will act to diminish snow chances after Wednesday. MARINE... Rapidly deepening low pressure will lift into northern Lake Huron this evening. As the pressure gradient tightens this afternoon and early evening, easterly winds will veer to southerly and increase to 25 kt. The low will drive a strong cold front through the area this evening, turning winds to the west-southwest. Strong cold advection will allow gale force gusts to mix down into all marine zones with a low chance for gusts to storm force briefly possible with frontal passage in the 00-06z time frame. Waves will build to over 10 ft over the northern and central Lake Huron basin by Friday morning with heavy freezing spray expected. Westerly gales will persist through the day Friday with continuing cold advection before gradually weakening below gale strength Friday night. High pressure will build into the region from the northwest on Saturday into Sunday, relaxing winds and wave action. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...Wind Advisory until 10 AM EST Friday for MIZ047>049-053>055-060>063- 068>070-075-076-082-083. Lake Huron...Heavy Freezing Spray Warning from 1 AM Friday to 4 AM EST Saturday for LHZ361>363-462>464. Gale Warning until 7 PM EST Friday for LHZ363-421-422-441>443- 462>464. Gale Warning until 4 AM EST Saturday for LHZ361-362. Lake St Clair...Gale Warning until 7 PM EST Friday for LCZ460. Michigan waters of Lake Erie...Gale Warning until 7 PM EST Friday for LEZ444. Low Water Advisory until 4 PM EST Saturday for LEZ444. && $$ AVIATION.....CB DISCUSSION...JVC/AM MARINE.......TF You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Hastings NE
723 PM CST Thu Feb 7 2019 .UPDATE... Issued at 722 PM CST Thu Feb 7 2019 Made another update tonight to decrease wind a bit faster, as the surface high influence is taking hold. UPDATE Issued at 703 PM CST Thu Feb 7 2019 Updated the forecast for tonight to increase dewpoints by several degrees, based closer to the HRRR solutions. && .SHORT TERM...(This evening through Friday) Issued at 317 PM CST Thu Feb 7 2019 Snow has ended across the area and there are a few cold air stratocumulus that continue to move through the area. Temperatures have warmed a few degrees warmer than forecast, but that is still cold. As the sun goes down this evening, the stratocumulus are expected to dissipate and skies will become clear. The surface high continues to nose into the area tonight and as it moves through the winds should diminish. That will be a good and a bad thing. On the good side, the winds will keep the temperatures from falling off as far as they could, but the bad part is that the winds combined with the cold temperatures will create bitter cold wind chills. Have kept the wind chill advisory as is for now. A few of the locations may not have as cold of a wind chill, but it is still going to feel bitterly cold out there. By Friday morning, the wind will be fairly light and wind chills will start to improve during the morning hours. During the afternoon, there will be some warm advection, especially in the west, and temperatures should warm up fairly quickly. Everywhere will have some warmer temperatures, but the west will see the greatest change. The pressure gradient tightens up on Friday, but winds are not expected to get too breezy during the afternoon. .LONG TERM...(Friday night through Thursday) Issued at 317 PM CST Thu Feb 7 2019 Friday night the pressure gradient continues to tighten and the winds aloft also increase. This will allow the winds to increase during the night, but will still just be a little breezy. By Saturday morning winds at 850mb are 50 to 60 knots. The winds will be a little more breezy during the day. Will need to watch to see if they need to be increased any as the time gets closer. This is another case of good and bad. The winds will help to warm the temperatures and the highs on Saturday will be around normal for this time of year, but with the wind, it will not feel the best. The next upper level wave and cold front will move through the area late Saturday night into Sunday. Clouds will increase Saturday night and there is a small chance for some light snow overnight Saturday night. The best chance for snow will be Sunday morning as the upper wave moves through. There is a good chance for snow, but amounts are expected to be pretty light. The northern part of the forecast area will have the best chance and there will be little to none in north central Kansas. There should be a little break Sunday afternoon and evening, but another system starts to affect the area Sunday night into Monday night. The temperatures are not as cold as we have been having and so there comes the rain/snow concerns. Most of the area will have only snow, but there could be a mix in the south as the temperatures warm a little on Monday. Tuesday through Thursday is expected to be a dry period. Temperatures will be on the cool side, but still warmer than currently. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday) Issued at 550 PM CST Thu Feb 7 2019 VFR conditions are expected. Winds will continue to decrease as a surface high approaches. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Wind Chill Advisory until noon CST Friday for NEZ039>041-046>049- 060>064-072>077-082>087. KS...None. && $$ UPDATE...Heinlein SHORT TERM...JCB LONG TERM...JCB AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Grand Rapids MI
656 PM EST Thu Feb 7 2019 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 330 PM EST Thu Feb 7 2019 -Additional power outages tonight into Friday from high winds gusting to 45 mph; falling ice/tree branch concerns -Standing water freezing abruptly tonight (flash freeze) -Snow showers, poor travel conditions overnight through Friday -Lengthy power outages possible as very cold air, gusty winds, and snow showers hamper recovery efforts on Friday -Risk for ice jams and localized flooding continues && .DISCUSSION...(This evening through next Thursday) Issued at 330 PM EST Thu Feb 7 2019 Kent, Ionia, and Montcalm counties have been hardest hit by ice as this is where the two freezing rain events overlapped (Tuesday night`s event which never melted off and this mornings). Well over 100,000 customers are without power and this number may grow as the winds pick up considerably with the passage of the cold front early this evening. Still some uncertainly if we get enough warmth in the aforementioned hard hit area to melt off all the ice before the winds hit. Latest guidance suggests this area will get to about 40 degrees for a few hours late this afternoon and early evening. We also have the hazard of chunks of ice falling onto cars or pedestrians when temps are warming late this afternoon. Falling tree branches possibly become a hazard as well as the winds begin gusting to 45 mph this evening. Areas north/northeast of Grand Rapids such as Big Rapids, Mt Pleasant, Alma, Clare have newly accumulated ice from this event and have less chance of turning mild enough long enough to have much melting. Therefore the areal extent of the power outages will probably grow/expand north and eastward when the strong winds hit this evening. Timing-wise...areas of dense fog/light rain for the next few hours as the deepening sfc low tracks overhead. The fog threat ends once the strong wind gusts commence around 5-6 PM in far sw Lwr MI per the HRRR then spread north and east across the rest of the area through 8-9 PM. Frequent gusts of 35-40 mph from the west will be common tonight, but a few 45-50 mph gusts may occur. As far as the flash freeze, it is between 10 PM and 1 AM tonight that the rush of cold air sweeps in from the west and sends temps down into the teens rather abruptly. The onset of the snow showers should coincide with the Arctic intrusion. While some briefly intense snow showers are possible overnight into Friday, total accumulations through Friday evening should be held down in the 1-3" category. The strong winds typically makes it difficult to focus heavier snows in a particular location for any length of time, and the bands will extend well inland across the entire state. The highest total amounts should be displaced inland, probably near the Hwy 131 corridor, due to speed convergence - with lesser amounts at the coast. Quiet weather will aid power recovery efforts on Saturday with a 1045mb sfc high overhead. Then a prolonged light snow event appears possible Sunday afternoon and night, although with limited impacts. A more impactful system is possible on Tuesday into Wednesday as another sfc low/occlusion sends more snow and/or mixed precipitation into the area. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 656 PM EST Thu Feb 7 2019 West winds will gust over 30 knots at times through Friday with some gusts over 40 knots possible tonight. There will be areas of IFR conditions through tonight with rain showers transitioning to snow showers overnight. Lake effect snow showers will continue to bring IFR conditions Friday morning into Friday afternoon especially across western Lower Michigan from MKG to GRR. && .HYDROLOGY... Issued at 330 PM EST Thu Feb 7 2019 A very active hydrologic situation continues to unfold across West Michigan with snowmelt runoff combining with ice in the rivers and precipitation events to increase the threat of flooding. Strong rises continued on most of the rivers across the region as snowmelt continues to funnel from the smaller streams into the larger rivers. Many of the small streams are approaching or just past their crests, while the larger rivers will keep rising for several more days. Although widespread flooding is not expected, local flooding is still a concern, as ice in the rivers complicates river flows. Several small ice jams have formed around the area, though only minor flooding is currently occurring. A more significant ice jam continues on the Grand River at Portland, resulting in residential flooding. A flood warning remains in effect for the Grand River at Portland. Additional precipitation events are likely over the next week. Given that ice is currently in many rivers, those with interests along area rivers should continue to monitor the situation as rapid changes may occur. && .GRR WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 7 PM EST Friday for MIZ037>040- 043>046-050>052-056>059-064>067-071>074. && $$ SYNOPSIS...Meade DISCUSSION...Meade AVIATION...Ostuno HYDROLOGY...63
Area Forecast Discussion
National Weather Service Indianapolis IN
1015 PM EST Thu Feb 7 2019 .UPDATE... The Near Term and Aviation sections have been updated below. && .SYNOPSIS... Issued at 205 PM EST Thu Feb 7 2019 Strong low pressure over Illinois is expected push to the Great lakes this afternoon and drag a cold front across central Indiana by early evening. Rain showers along with a few thunderstorms are expected to continue this afternoon along and ahead of the front. Cold Canadian high pressure is expected to build across Indiana tonight and Friday in the wake of the front. This will bring dry weather along with much colder temperatures for the first part of the weekend. A warm front will return to Central Indiana late on Sunday...bringing precipitation chances back to the state on Sunday afternoon. Precipitation chances are expected to linger across the state through at least Tuesday as the frontal boundary lingers near the area and another low pressure system is expected to arrive from the southwest. && .NEAR TERM /Tonight/... Issued at 1010 PM EST Thu Feb 7 2019 Going forecast is in fairly good shape. Per latest HRRR and LAMP hourly numerical guidance, and obs trends, there is a decent chance that we may see the single digits in the northwest by morning, and made some downward adjustment to mins in that portion of the forecast area. Additionally, added a chance of flurries overnight per upstream obs and radar trends. These should be of little significance or impact. Adjusted sky grids closer to satellite trends as well. Decided to go ahead and cancel the flood watch a little early as flooding is ongoing and precipitation has ended across the area. Flooding will continue to be handled with areal and river flood warnings and statements throughout the night and beyond as needed. Will keep the wind advisory going although gusts thus far are largely just below criteria. Cannot rule out a few 45 MPH gusts before all is said and done. Previous discussion follows. Issued at 205 PM EST Thu Feb 7 2019 Surface analysis early this afternoon shows low pressure in place across northern Illinois...along with a cold front stretching southward to southern Illinois and eastern Arkansas. Radar shows abundant rain showers across southern Central Indiana with a line of embedded thunderstorms pushing across the southern forecast area. GOES16 shows a stream of tropical moisture pushing northeast across Arkansas to Indiana and Ohio. Heavy rains were resulting in flooding across Central Indiana. Will continue high pops and the flood watch through the afternoon hours as rain and flooding is expected to be ongoing for several more hours. The GFS and NAM suggest the surface front will be east of Central Indiana by 00Z. This should bring a quick end to all of the ongoing precipitation. Forecast soundings and time heights show plentiful dry air arriving this evening and overnight with subsidence within the column. Thus will trend toward a dry forecast overnight...along with decreasing clouds by morning. Strong cold air advection is expected within the wake of the front as the models suggest 850mb temps falling toward -13C by 12Z. Furthermore a strong lower level pressure gradient is expected overnight and this along with the cold front will result in sub zero wind chills on Friday morning. However at this time values do not appear high enough to suggest an advisory will be needed. Given the cold air advection will trend lows at or below the forecast builder blends. && .SHORT TERM /Friday through Sunday/... Issued at 205 PM EST Thu Feb 7 2019 Dry and cold weather is expected on Friday. this will persist through at least Sunday morning when a warm front arrives from southern Central Indiana. Forecast soundings and Time heights show a very dry column across Central Indiana on Friday through Saturday Night along with good subsidence. This will be due to a few features...namely the weak upper ridging that will be established over the weekend over the plains states...resulting in strong lee side subsidence and a strong associated surface High pressure system. With unreachable convective temperatures along with anti-cyclonic lower level flow in place...only partly cloudy skies will be expected from some passing high cirrus. Thus will use a partly cloud sky and dry weather through Saturday night. Given the cold air mass will trend temperatures at or below the forecast builder blends. By Sunday the strong high pressure system will have drifted east of Indiana and a more zonal flow will be in place aloft. This will result in the beginning of a more southerly surface flow...allowing moisture o return . The GFS shows a short wave passing through the Ohio valley on Sunday as a surface warm frontal boundary sets up amid the return flow from the departing high. These features should be enough to allow a return of pops to the forecast. Forecast soundings suggest precipitation should begin as snow on Sunday as the forecast soundings appear saturated and below freezing during the afternoon and evening. At the moment...some light accumulations appear possible given the expected cold ground. Will trend pops higher and high temps on Sunday cooler than the blends. && .LONG TERM /Sunday night through Thursday/... Issued at 316 PM EST Thu Feb 7 2019 More seasonable conditions will be in place for the long term. Brief upper ridging will move through, but at the same time a front will approach from the south. Best chances for precipitation will move in from the south. Better upper forcing will move in by Monday night. Temperatures will be running near to below normal (with the exception of Tuesday highs which will be a bit warmer) and so these precip chances will be in the form of snow at night, with a rain/snow mix possible at times during the day, changing over to rain on Tuesday. By Tuesday afternoon dry weather could move in, but the pattern is looking fairly progressive so other small upper waves could bring more chances in as we get closer. && .AVIATION /Discussion for the 08/03Z TAF update/... Issued at 1010 PM EST Thu Feb 7 2019 TAFs are in very good shape. Minor adjustments made to bring a couple of the sites closer in line to obs, but general forecasts in excellent shape. Previous discussion follows. Issued at 630 PM EST Thu Feb 7 2019 Predominantly MVFR conditions during the first 5-9 hours of the period, with VFR conditions returning thereafter. A strong cold front has swept through the sites, and with it, precipitation is coming to an end and IFR ceilings will soon move out where they haven`t already. MVFR ceilings will dominate through the evening and into the overnight, before improving late as the clearing line approaches. Winds will be a significant impact much of this period. Winds will generally be from 270-290 degrees. Sustained winds early in the period will be as high as 20-25KT at times with gusts as high as 30-35KT. These sustained winds and gusts will gradually weaken slightly later tonight into Friday, although winds will remain gusty throughout the period. Visibilities should become unrestricted quickly and remain so throughout the period. && .IND WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 7 AM EST Friday for INZ021-028>031-035>049- 051>057-062>065-070>072. && $$ SYNOPSIS...Puma NEAR TERM...Puma/Nield SHORT TERM...Puma LONG TERM...CP AVIATION...Nield
Area Forecast Discussion
National Weather Service Louisville KY
934 PM EST Thu Feb 7 2019 .Forecast Update... Issued at 934 PM EST Thu Feb 7 2019 Went ahead and cancelled the NW portions of both the Flood Watch and the Wind Advisory. It has stopped raining along and north of a Morgantown to Elizabethtown to New Castle, KY line so there is no longer a need for the Flood Watch. That being said, a few areas of standing water near low water crossings will likely hang around into the overnight. Use caution if traveling and never drive into water! Otherwise, will leave the Flood Watch going where it is still raining for another 3 to 4 hours. Also let the Wind Advisory go for areas along and north of that same line as gusts are mostly letting up a little 2 to 3 hours after frontal passage. There could still be some gusts up around 35 mph at times for the next several hours, but overall the threat for gusts over 40 mph is quickly diminishing. Again, will leave the rest of the Wind Advisory alone for another few hours. Wanted to address the other concern about lingering wet roads freezing as temps drop into the teens and 20s by dawn. Was watching a web cam up near Huntingburg, IN all evening and noted that it took about 2-3 hours after the rain to stop for the wind to completely dry the pavement. So, think that the threat for lingering slick spots should be pretty limited due to the wind and dry air making pretty quick work of damp roadways. The only real concern is with any standing puddles that could be a little tougher to eradicate before it freezes. For now, will remain vigilant but not overly concerned with the threat for slick spots by dawn. Nevertheless, folks should use some caution for the morning commute. Previous Update... Issued at 746 PM EST Thu Feb 7 2019 The strong cold front has pushed east of the I-65 corridor and we are seeing a 10-15 degree drop in about 15-20 minutes behind it. In addition, winds are gusting in the 35-45 mph range behind the front, with SDF clocking a peak wind of 44 mph a bit ago. Will keep the Wind Advisory going through the evening hours to get the front through the area. Widespread light to occasionally moderate rain also continues along and behind the front, however this is also pushing slowly east with time. Overall, expect about a 3-4 hour lag between frontal passage and the end of the light rain. Very sharp temp gradient exists as the Lake Cumberland area remains in the low 70s, while Huntingburg has found it`s way into the upper 30s! Could still see some flakes flying on the back side of the precipitation shield, but no accums expected as surface temps will likely lag behind air temps due to the recent mild stretch of weather. Also not overly concerned about slick spots on roadways toward dawn as a several hour stretch of gusty and dry conditions should work to dry surfaces before temps really plummet below freezing. Suppose a few slick spots could be around where water has puddled, but don`t expect it to be an issue. Still monitoring some of the areas up in southern IN that had Flood Advisories and Warnings from earlier. Rain has stopped and will be calling shortly to see if problems have subsided to let the advisories/warnings go. Will also be continuing to keep an eye on area rivers as they continue to rise. Finally, did have to issue a Special Weather Statement for a thin line of convection down near Lake Cumberland where the slightest of instability gradients still exists ahead of the cold front. Seeing some pretty good rainfall rates down there, albeit brief. This could cause ponding of water on roadways and minor nuisance flooding, but should be too short-lived for any advisory or warning product. Will keep an eye on these cells over the next half hour to 1 hour. Overall, everything looks on track and will be looking for opportunities late this evening to dial back advisories and headlines as things wind down. Goodbye mild was a nice run! && .Short Term...(This evening through Friday) Issued at 250 PM EST Thu Feb 7 2019 Watching for stronger storms this afternoon and evening, then much colder air will move into the region to close the work week. Line of storms that formed earlier is in the process of weakening. Noteworthy however is the lack of leading stratiform ahead of it as well as the warm air it is moving into. We have had some record highs ahead of this line. Consequently, we are seeing model forecast soundings show a narrow line of surface-based CAPE as well as plenty of shear. Still think we could see either new development, in the form of spinning low-topped showers or perhaps a reinvigoration of the line, as per the 12Z NamNEST solution or 16Z HRRR run, mainly south of I-64 and east of current convective line. Outside of that severe weather threat, we are seeing winds gusting in the 30-45 mph range. We likely will see this continue for a few hours behind the frontal passage tonight. Not planning any changes to the current wind advisory. Cold air will blast into the area overnight, with lows crashing into the low to mid 20s for many locations, probably even the teens in southern IN. Highs Friday, likely under good insolation, should stay in the 25-30 degree range for southern Indiana and 28-33 for many parts of central Kentucky. .Long Term...(Friday night through Thursday) Issued at 301 PM EST Thu Feb 7 2019 ...ACTIVE WEATHER PATTERN EXPECTED DURING THE FIRST HALF OF NEXT WEEK WITH ADDITIONAL FLOODING POSSIBLE... =================================== Friday Night through Saturday Night =================================== Surface high pressure is forecast to build into the region Friday evening and into the day on Saturday. Combination of clear skies and light winds will result in a decent radiational cooling event. Lows Saturday morning should drop into the 10-15 degree range over southern Indiana and the northern half of KY. Across southern KY, lows of 15-19 are expected. High pressure will result in mainly sunny skies on Saturday but temperatures will remain cold. Highs of 35-40 look likely across the region. By Saturday night, we`ll see winds shift from the east to the southeast and low-level isentropic lift will likely get underway. Cloud cover is likely to increase throughout the night and temperatures are not expected to drop as much. Current data suggests that lows in the 20-25 degree range are likely by sunrise Sunday. =================================== Sunday through Thursday =================================== Moving along into Sunday, the next weather system will make a move toward the Ohio Valley Sunday morning. Overall trend in the models is for precipitation to break out across the region from southwest to northeast by mid-late morning. This is a little slower than in previous model runs. Low-level temps may be marginally cold enough initially to support a wintry mix, but as low-level warm air advection scheme becomes increasingly stronger, temps will warm by early afternoon resulting in plain rain. Highs Sunday afternoon will likely warm into the upper 30s to the lower 40s. A few upper 40s will be possible along the KY/TN border region. Combination of strong isentropic upglide along with a persistent fetch of Gulf moisture should keep widespread rainfall in place across the region Sunday night. Temps may cool into the mid 30s by early Monday morning, but model proximity soundings suggest that rain will be the dominant precipitation type. However, there is a chance that some low-level cold air may work into our northern row of southern IN counties resulting in a mix or change over to some snow. For Monday and Tuesday, overall upper air pattern looks to take on a similar setup to what we saw late last week with a persistent southwest flow aloft with much of the Ohio Valley located in a broad baroclinic zone. Southern IN and central KY are likely to remain within the warm sector of the zone resulting in additional rainfall. Several perturbations will move through the region bringing periods of moderate to occasionally heavy rainfall. Rainfall amounts of 1-3 inches look likely with localized higher amounts possible. Given saturated soil conditions, this will lead to additional localized flooding issues in some areas. The larger story would be that this additional runoff would go right into our rivers which will simply result in a longer period of flooding with some rivers seeing additional rises into higher flood categories. Highs Monday look to warm into the mid-upper 40 across southern IN and northern KY while southern KY sees temps in the lower 50s. Most locations should warm into the 50s/60s on Tuesday when the warm advection scheme is maximized. By Wednesday, surface frontal boundary looks to shunt eastward taking the rainfall away from the region. A cooler airmass will work back into the region with dry conditions expected through Thursday. Highs on Wednesday look to range from 40-45 across the north with mid-upper 40s across the south. Slightly warmer readings are expected on Thursday. Overnight lows through the period will be in the upper 20s to the lower 30s. && .Aviation...(00Z TAF Issuance) Updated at 647 PM EST Thu Feb 7 2019 A strong cold front is pushing through our area at this hour. It has already passed HNB and will pass through SDF/BWG shortly after 7 PM EST. LEX should expect passage around 9 or 10 PM EST. Expect winds to shift to a WNW component around 20 mph and gusting up around 35 mph for a few hours after frontal passage. Gusty WNW winds will then continue through much of the overnight, although slowly backing off more in the 20-30 mph range for gusts. In addition to the gusty winds, light to occasionally moderate rain will continue at BWG/SDF/LEX for a few more hours. Expect the rain to end at SDF/BWG around 10 or 11 PM EST, and LEX around 1 AM EST. Low ceilings in the low MVFR range (below fuel alternate) will settle in behind the frontal passage, with perhaps some brief IFR also. Cold dry air quickly spills in behind the front and should begin to scatter out the low level moisture before sunrise. This will bring a return to VFR, but gusty W wind will continue around 20 mph through near the end of this cycle. Skies should be VFR for the daylight hours of Friday. && .Climate... Issued at 245 PM EST Thu Feb 7 2019 Listed below are the record highs and forecasts for today. Site Rec. (Yr) Fore. SDF 69 (1925) 70** LEX 67 (1925) 70** BWG 71 (1931) 73** FFT 69 (1925) 69** **Record already broken or tied today. Listed below are the record warm lows and forecasts/obs for today. The caveat is that a cold front will move through before midnight, likely pulling readings down below record levels. LEX stands the best chance to break their record, should the timing of the frontal passage slow down. Site Rec. (Yr) Fore. SDF 55 (2017*) 39 LEX 54 (2017) 43 BWG 52 (2017*) 35 FFT 56 (2017) 40 In addition to the warmth, a very moist airmass over the region likely will bring record rainfall. Below are the record rainfall amounts for today for each of our climate sites. Site 2/7 Record (Year) SDF 1.09" (1890) LEX 1.30" (1890) BWG 1.05" (1933) FFT 0.87" (2018) && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...Flood Watch until 1 AM EST /midnight CST/ Friday for KYZ035>037- 039>043-045>049-053>057-062>067-070>078-081-082. Wind Advisory until midnight EST /11 PM CST/ tonight for KYZ035>037-039>043-045>049-053>057-062>067-070>078-081-082. && $$ Update...BJS Short Term...RJS Long Term...MJ Aviation...BJS Climate...RJS
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday) Issued at 240 PM CST Thu Feb 7 2019 Cold arctic air streams southward, bringing dangerously cold wind chills tonight into Friday morning. An elongated meridional high pressure ridge is building into the region this afternoon, its arrival heralded by significant CAA on a northwest wind of 15 to 25 kts, gusting to near 35 kts at times. Differential CAA this afternoon mixed the boundary layer up to around 1-km in depth and allowed for the development of shallow HCR stratocumulus in the wake of last night`s system, but the lack of deeper saturation at the top of the BL limited the production of any precipitation. These winds will keep wind chill values in the single digits below zero for the rest of the afternoon, with winds and the stratocumulus lessening this evening as the surface pressure gradient expands and diurnal boundary-layer decoupling takes place. The combination of the approaching 1043 mb high, lessening winds, dewpoints in the single digits below zero, and (an albeit shallow) snow/ice/sleet pack should facilitate the rapid fall of temperatures tonight. Adjusted lows tonight towards the Canadian/BC RAP solutions; the coldest of the guidance suite. This pushes min temps to around the zero degree mark and wind chills to -10 to -20; coldest along the Kansas/Nebraska border. The surface ridge slides eastward during the day on Friday, but with the H850 ridge not clearing the forecast area until after 00Z, any meaningful WAA takes place after peak heating on Friday and highs should be confined in the 20s. .LONG TERM...(Friday night through Thursday) Issued at 240 PM CST Thu Feb 7 2019 There are a couple of systems of note for the weekend and early next week that could bring a wintry mix to the area. Broad longwave troughing along the North American west coast re- amplifies over the course of the weekend as a PV lobe ejects from the Polar Vortex. A modest shortwave rounds the base of this amplifying trough late Saturday into Sunday, with the main trough ejecting eastward late Monday into Tuesday. Broad zonal flow then sets in for midweek, though model diversity increases as this pattern flattens out. These aforementioned waves will be the main drivers for two periods of wintry precip early Sunday and again Monday into Tuesday. Lee cyclogenesis along the Front Range induces weak 280-290K isentropic ascent over the forecast area late Saturday night into Sunday morning. NAM/GFS bufr soundings do saturate at least the lowest 1-2 km of the profile within this realm of ascent. GFS profiles also saturate through the DGZ, at least for a short while, whereas the NAM is devoid of moisture above -4 C. With surface temperatures in the mid/upper 20s, freezing drizzle would be the most likely precipitation type in the NAM scenario. However, there remain uncertainties in the temporal juxtaposition of the lift and saturation and have left a mixture of snow/freezing drizzle in the official forecast. The H500 wave outruns the surface cyclone and results in cyclolysis Sunday afternoon. The baroclinic zone lifts back northward on Monday as heights fall ahead of the next shortwave in the train. Once again, there is a modest chance of a wintry mix with this system, but confidence in this solution is lower than average at the present time and refrained from specifying a time/location of freezing precip with this forecast. Temperatures for this entire forecast period will fluctuate around or slightly below average for this time of year with the baroclinic zone lingering near, but mainly south of the forecast area. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 506 PM CST Thu Feb 7 2019 Skies continue to clear into sunset with the parent storm system continuing to move further out of the region. Cold air continues to spill into the area, so will maintain some mixed BL with winds around 10kts. Winds gradually veer more southerly by tomorrow afternoon. && .TOP WATCHES/WARNINGS/ADVISORIES... Wind Chill Advisory from 9 PM this evening to 8 AM CST Friday for KSZ008>012. && $$ SHORT TERM...Skow LONG TERM...Skow AVIATION...Drake