Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/11/18


Area Forecast Discussion
National Weather Service Burlington VT
756 PM EST Sat Feb 10 2018 .SYNOPSIS... A quasi-stationary frontal zone extending from western New York into far northern Vermont will maintain cloudy skies with periods of snow across the North Country through this evening. A wave of low pressure moving into the region along the frontal boundary will bring warmer air aloft, with periods of sleet and freezing rain mixing in with the snow tonight into Sunday. The best chance for mixed precipitation will be across central and southern Vermont tonight. High pressure will ultimately bring drier air to the region Monday and Tuesday. && .NEAR TERM /THROUGH SUNDAY/... As of 612 PM EST Saturday...Latest radar shows central and southern portions of the CWA are now precipitation free south of the front with more widespread snow persisting across northern New York and portions of northern Vermont. Hi-res models such as the NAM3, HRRR and locally run 4km WRF all handling the current trends very well, and show mainly dry weather persisting south with a brief period of rain possible as the front sags southward and weak low pressure tracks along the boundary through the mid-Atlantic and southern New England states. To the north snow remains widespread through the midnight hour, but rapidly decreases in coverage thereafter through the remainder of the night. With this in mind, have cancelled the winter weather advisory for central and southern Vermont, while continuing it northward where additional snow accumulations of up to 2 inches is possible through midnight. No other changes made to the forecast at this time. Previous Discussion...The Winter Weather Advisory remains in effect through 7 am Sunday. Snow is spreading back across the North Country this afternoon as weak low pressure moves along a nearly stationary boundary. This boundary has lifted just to our north today, allowing temperatures to warm into the 30s in many spots away from the Saint Lawrence Valley, but it will slowly sink south overnight. In fact, it has already begun its southward trek as evidenced by northwest winds at Plattsburgh and Burlington. As such, although precipitation may initially start as rain or a rain/snow mix, it should transition over to all snow by sunset. The snow will continue through this evening, particularly over the north until the low moves east. Meanwhile, another low will move to our south later tonight, which will transition the precipitation more toward southern sections of the forecast area. Cold air at the surface will undercut warmer air moving in aloft, resulting in a wintry mix of precipitation, mainly south of a St Johnsbury to Montpelier to Elizabethtown line. Additional snow accumulation through tonight will be 1 to 3 inches, with a glaze of ice possible. For Sunday...expect a good part of the area will be dry as we remain sandwiched between low pressure to our south and a second low approaching to the west. Far southern areas will see a wintry mix continuing early in the morning, but warm advection will begin in earnest by early afternoon, turning the mix over to rain as temperatures rise above freezing. This wintry mix will shift northward through the afternoon as the more northern low approaches. The low will slide along the St Lawrence Valley toward evening, and temperatures will rise into the mid and upper 30s away from the St Lawrence Valley by early evening. As such, precipitation will likely change over to rain just about everywhere for a time Sunday afternoon/evening. Once the low moves to the east, colder air will rush in from northwest to southeast, turning precipitation back over to all snow, starting roughly around midnight. However, moisture will quickly get shut off, so snow will taper to showers and then come to an end by daybreak Monday. Additional snow accumulations overnight Sunday night will be less than an inch. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 255 PM EST Saturday...Quiet weather is then expected Monday and Monday night in a post- frontal airmass under northwesterly flow which will trend light as 1040 mb polar high settles overhead by Tuesday morning. Outside a lingering mountain flurry early mainly dry weather is expected with increasingly sunny/clear skies. Temperatures to generally range within a few degrees of mid-February seasonal norms with highs in the upper 20s to lower 30s and corresponding lows in the single digits to around 10 above in warmer locations of the Champlain and southern Vermont valleys. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 255 PM EST Saturday... A seasonal, though fairly active weather pattern looks to continue for the middle and later portions of next week as near-zonal flow becomes slightly more amplified over time. The polar front will be draped across the northern tier of the lower 48 and waffle north and south across our area through these periods. Decent stretches of dry weather are expected, but given the proximity of the frontal boundary clouds will be more common than sunshine. No large-scale precipitation events are expected with the best shot of light precipitation occurring Tuesday night as the boundary pushes north with accompanying warm thermal advection, and then again by Thursday/Thursday night as it passes back through as a cold front. Temperatures should top out in the 20s to lower 30s on Tuesday, Friday and Saturday, though trend milder into the upper 30s/lower 40s during Wednesday/early Thursday with the front lying to our immediate north. Given these temperatures lie either side of the 32F mark, precipitation will be characterized as rain/snow showers at this point with some minor additional snowpack additions to mainly higher terrain locales. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... Through 00Z Monday...Light snow continues across the region as of 00z. IFR conditions will be likely through 06z Sunday due to snow and mixed precipitation. Precip will wind down thereafter as drier air works into the region, allowing conditions to improve to MVFR. Mixed precipitation will spread northward through Sunday 18z, with the wider valleys turning to plain rain Sunday afternoon. MVFR conditions will prevail through then, though local IFR will be possible. Outlook... Sunday Night: MVFR/IFR conditions possible. Chance RA, Likely FZRA, Slight chance SHSN. Monday: VFR. NO SIG WX. Monday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. Chance SHSN. Wednesday: Mainly MVFR, with local IFR possible. Slight chance SHRA, Slight chance SHSN. Wednesday Night: Mainly VFR, with areas MVFR possible. Slight chance SHSN. Thursday: Mainly MVFR, with local IFR possible. Chance SHRA, Chance SHSN. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Winter Weather Advisory until 7 AM EST Sunday for VTZ003-004- 006-007-016-017. NY...Winter Weather Advisory until 7 AM EST Sunday for NYZ026-027- 029>031-034-087. && $$ SYNOPSIS...Hastings NEAR TERM...Hastings/Lahiff SHORT TERM...JMG LONG TERM...JMG AVIATION...Hastings/Neiles
Area Forecast Discussion
National Weather Service Wilmington OH
940 PM EST Sat Feb 10 2018 .SYNOPSIS... A cold front will continue to push slowly southeast. Meanwhile, a series of low pressure systems riding northeast along the front will lead to occasional chances for precipitation through Sunday night. With cooler air moving in behind the front, there is chance for a wintery mix of pcpn northwest of I-71. Drier conditions will work in for Monday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Temperatures have dropped off in the early evening. But it appears that they should become fairly steady until closer to morning. At that point, expect temperatures to start to slowly rise as low pressure approaches. There will be another surge of rain across southeast counties overnight, and it is not out of the question that the northern edge of this could be freezing rain. Not a lot of confidence in this, but it will have to be monitored. North of the precipitation shield there may be some drizzle which could increase in coverage later in the night as the low gets closer. Will not make any changes to the advisory at this time. If sufficient drizzle breaks out in sub freezing temperatures, this may have to be expanded for a period of time. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Rain will develop early in the period along and behind low pressure and a cold front that will track northeast across the area. HRRR and RAP runs show that the precipitation will be rather transient, likely only lasting a few hours at any one location. But it appears that there will be a lingering chance of precipitation through the afternoon as additional energy lifts across the area. Details of temperature forecast become more uncertain further out in time, but boundary of winter weather advisory seem sufficient to capture the area where freezing rain is likely. Temperatures will rise into midday and then start dropping from west to east starting in the early to mid afternoon. After 00Z Monday, a shortwave in the northern stream will be swing through the flow. Models are trying to develop a streak of snow with the feature Sunday night, but are differing on the exact placement. THe NAM has it across ne KY and the lower Scioto valley, while the other models keep it farther se. Will keep low chance PoPs in the se Sunday night. Temperatures and thicknesses will be cool enough that the pcpn should be snow, with a quick half inch possible. && .LONG TERM /MONDAY THROUGH SATURDAY/... A system will be exiting the region at the start of the long term Monday morning. High pressure and dry conditions will then work into the region. Some off and on drizzle or light rain will move across the region Tuesday through Thursday with southerly flow. Cannot rule out some brief snow across northern portions of the region. Better precipitation chances will be present Thursday evening into Friday as a cold front approaches and moves through. There will also be some snow with the front as colder air works in. A frontal boundary with additional disturbances will linger around the region for the weekend keeping precipitation chances in the forecast. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... While there could be a few breaks in the lower clouds early, IFR conditions will prevail through much of the period. Some locations are expected to fall to LIFR late tonight into Sunday morning. At the terminals there may be some drizzle from time to time, and temperatures may get cold enough for this to be freezing drizzle. As low pressure tracks across the region on Sunday, there will be a period of rain associated with it. Ceilings and visibilities will improve slightly and winds will shift to west to west northwest. KDAY to KCVG/KLUK may rise to MVFR late in the period. OUTLOOK...MVFR conditions are possible Wednesday into Thursday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...Winter Weather Advisory from 1 AM to 4 PM EST Sunday for OHZ026-034-035-042>046-051>054-060>062-070. KY...None. IN...Winter Weather Advisory from 1 AM to 4 PM EST Sunday for INZ050-058-059-066. && $$ SYNOPSIS...JGL/Sites NEAR TERM... SHORT TERM.../Sites LONG TERM...Haines AVIATION...
Area Forecast Discussion
National Weather Service Jacksonville FL
837 PM EST Sat Feb 10 2018 .UPDATE...Marine fog will continue for the nearshore waters along the First Coast and Coastal Southeast Georgia, so the Dense Fog Advisory for the marine waters through Sunday afternoon. With the lowest level winds becoming southerly, have hoisted a Dense Fog Advisory for Coastal Glynn County with the areas that will be most susceptible to the lowered visibilities include: Saint Simons Island, Wesley Oaks, Glynn Haven, Sea Island, Wimberly on the Marsh and Jekyll Island. Sea fog will develop over the western peninsula coastal waters overnight. A southerly wind will make for a peninsular flow, and good mixing immediately above the surface at 20 to 25 knots combined with plentiful moisture above 550 mb is not ideal for radiational fog. The best chance of fog will be more maritime advection fog over southern part of coastal Glynn due to the nature of the southerly flow. The HRRR hourly runs over the last few hours continues to indicate that marine fog will continue over our coastal waters and along much of western Florida without much advection inland across our region but rather up the U.S. Route 319 corridor north of the Big Bend area well west of the region due to the southerly flow. Over most the region, a hybrid of low stratus and patchy fog looks like the best bet, except near the immediate coast. During the rest of the night, we will continue to monitor area observations if fog develop deviates from this latest thinking. There could be an influx of moisture moving through Atlanta by early morning, translating south and east through the pre-dawn hours where a few showers can reach near or just west of the door step of the far NW interior zones of SE Georgia by daybreak. Otherwise, the rest of the region will remain dry. Overnight lows will be mild in the lower 60s. && .AVIATION...Sea fog will continue to impact KSSI through most of the TAF period. Light southerly surface winds anticipated overnight. Plenty of high level clouds will prevail through the period. Low stratus and patchy MVFR fog is forecast to develop a couple hours after midnight through the early daylight hours, with southerly LLJ increasing around 20 to 25 knots. Daytime mixing and heating will scour stratus between 16 and 18z with southerly surface winds at 10 to 15 knots. While sea fog will continue at SSI through late morning or early afternoon. Isolated to widely scattered showers with a couple thunderstorms are possible in during the mid to later part of the afternoon over area terminals. && .MARINE...Sea fog will continue for the nearshore waters, especially from St. Augustine northward. The flow will shift to the south and southwest overnight tonight, which should keep the sea fog away from the immediate coast of northeast Florida, but still along the coast of southeast Georgia. Dense sea fog will likely continue over the nearshore waters during the next few days as high dewpoints stream over relatively cold waters. Scattered shower and thunderstorm activity will increase Monday, and especially Tuesday as a weak backdoor cold front moves into the region. Surface high pressure will then build over the waters in the middle of the week. Rip Currents: Moderate risk will continue in the onshore flow. && .PRELIMINARY POINT TEMPS/POPS... AMG 63 77 63 75 / 10 40 50 70 SSI 62 74 62 70 / 10 10 30 60 JAX 62 82 62 76 / 10 20 30 70 SGJ 62 80 63 75 / 10 30 40 60 GNV 62 80 64 79 / 10 20 30 60 OCF 63 82 64 80 / 10 20 30 60 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...Dense Fog Advisory until 9 AM EST Sunday for Coastal Glynn. AM...Dense Fog Advisory until 1 PM EST Sunday for Coastal waters from Altamaha Sound to Fernandina Beach FL out 20 NM-Coastal waters from Fernandina Beach to St. Augustine FL out 20 NM- Coastal waters from St. Augustine to Flagler Beach FL out 20 NM. && $$ Cordero/Enyedi/Peterson
Area Forecast Discussion
National Weather Service North Platte NE
710 PM CST Sat Feb 10 2018 .UPDATE... Issued at 710 PM CST Sat Feb 10 2018 Based on current radar trends, as well as the latest HRRR and 4KM NAM nest model, have decided to cancel the winter weather advisory for Hayes and Frontier counties. The back edge of the precipitation has moved east of the area, with some flurries/very light snow occurring across Frontier county. This should come to an end in the 9 to 10 PM CST time frame. Elsewhere, will probably need to evaluate low temps for tonight, given the degree of clearing. Fortunately with light winds, the threat for dangerous wind chills appears minimal attm. && .SHORT TERM...(This evening through Sunday) Issued at 213 PM CST Sat Feb 10 2018 The latest model consensus places the deformation band just south of our southern three counties across southwest Nebraska. The band has largely set up in that location, and based off of upstream obs, moderate to heavy snow is occurring. Expected snowfall as the band lifts east northeast will produce an additional 2-3" across eastern Hayes and Frontier Counties late afternoon and evening. The frontogenesis is strong aloft with some omega in the DGZ and indications of weak slantwise instability. Under the right conditions, snow accumulations of an inch per hour would be possible. Along I80, light snow is possible under much weaker lift and lesser moisture. Snow amounts will remain at a half inch or less. Will continue the WWA for Hayes and Frontier counties due to the expected snow late this afternoon and evening. The advisory expires at 06z tonight. The overnight temperature forecast was derived from a blend of guidance with the WFR_ARW. This produces sub zero lows across our north with single digits elsewhere. This seems reasonable given weak downsloping winds and waa from the west. Am a bit concerned though that the recent snows with clear skies will yield much cooler lows like we saw last night. Will need to monitor. The temperature forecast has big implications as cooler temperatures would allow for dangerously cold wind chills. Given the latest data, we feel that wind chills will remain warmer than minus 19 F, but will monitor closely. Otherwise dry conditions and slightly warmer temperatures are forecast for Sunday. The temperature forecast is a result of blended guidance, but then lowered to account for the deep snow pack. .LONG TERM...(Sunday night through Saturday) Issued at 213 PM CST Sat Feb 10 2018 Minimal to low sensible weather concerns in the long term period. The main weather highlights include: cold wind chills early Monday morning in far northern NEB, flurries/light snow possible Monday, well-below normal highs Monday, and temperatures warm up peaking into the lower 50s Wednesday. Large scale pattern will feature an amplified longwave trough over much of the CONUS early Sunday evening with shortwave troughs near northern CA and another digging into the Pacific Northwest. Meanwhile, west northwest flow prevails overhead. An elongated upper level trough will then form over the West Coast- Northern Rockies Monday. Deterministic guidance are in fair agreement with the development of a closed low over the Pacific offshore waters off CA by Tuesday, elsewhere a sheared disturbance will be moving east through the Northern/Central Plains. A cold front will advance into western NEB from the north by early Sunday evening and should exit by late Sunday night. Meanwhile, surface high pressure builds across the Missouri Valley and Upper Midwest overnight with colder air filtering in. While high clouds are anticipated, lows 5 to 15 degrees below seasonable normals are expected with most locations expected to see lows in the single digits above zero Sunday night. Winds will be light and breezy as well so there are heightened wind chill concerns across far northern NEB wherein wind chills approach the upper teens below zero early Monday morning. However, wind chills do not appear to reach advisory levels at this time. Monday will be cold with highs forecast in the teens to 20s, warmest across far southwest NEB. There are also low-end chances for light snow Monday as well. Winds become westerly from the surface up to the lower-levels with the passing of 850 hPa shortwave trough early Tuesday. This will promote warming temperatures, albeit highs are expected to read slightly below- normal Tuesday. Warm up trend continues Wednesday with highs mostly 10 degrees above seasonable normal values at this time. Wednesday night and beyond, a weak surface cold front advances across the local forecast area late Wednesday and that will drop temperatures for Thursday. Highs Thursday and beyond are forecast to generally by slightly below to near-normal. Differences between guidance in the large scale pattern become more apparent with differences in both phase and amplitude noted. While there are low-end chances Friday-Saturday, confidence in timing and location is below-average. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 549 PM CST Sat Feb 10 2018 Cloudiness will gradually shift south and east of the area overnight with clearing expected across northern Nebraska by mid evening and across southwestern Nebraska overnight. In the meantime, expect ceilings of 5000 FT AGL at the KLBF terminal through mid evening, with scattered clouds around 15000 FT AGL through the overnight. Clear skies are expected on Sunday. For the KVTN terminal, expect clearing skies after mid evening. Clear skies will persist through Sunday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Buttler SHORT TERM...Jacobs LONG TERM...ET AVIATION...Buttler
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
808 PM CST Sat Feb 10 2018 .UPDATE... 808 PM CST Evening Update... Moved up start time to the southern portion of the winter weather advisory to 9 pm CST, with light mixed precip already developing across central IL. No other significant changes made to going forecast for overnight/early Sunday. Surface stationary front was analyzed from the Arklatex to south of the Ohio River this evening. 00Z upper air analysis continues to show a very strong thermal gradient aloft north of the surface front over our region, associated with the elevated frontal zone. This baroclinic zone will continue to be the focus for another round of wintery weather tonight through Sunday morning, as a short wave trough propagates across the region. Low level warm advection/isentropic ascent was already occurring across MO into central IL, which was working to enhance the already strong thermal boundary and force ascent. 00Z ILX sounding shows temps near 0C around/above H8, and RAP forecast soundings depict this warm layer increasing across the southeastern tier of LOT cwa counties overnight. Already seeing mixed precip (snow, freezing rain and the dreaded "unknown precip") reported from SPI to CMI, along the ILX/LOT border. Thus have adjusted start time for winter weather advisory a few hours earlier, due to the potential for the potential for some light glazing in any freezing rain. Farther north, mid-level frontogenetic forcing was producing banded light snow from Nebraska/Kansas northeast across Iowa. Radar returns over northern IL likely not reaching the ground just yet, with cloud bases still generally above 10 kft. Guidance indicates frontogenesis will strengthen across the area overnight, with gradual top-down saturation leading to snow developing toward or just after midnight. New 00Z NAM data is arriving, and see nothing from it to change much of going forecast at this point. Thus, moved southern cwa counties advisory start time to 9 pm, and otherwise have only made minor tweaks to hourly temp trends and pops here this evening based on observations/radar trends. Ratzer && .SHORT TERM... 310 PM CST Through Sunday... In collaboration with surrounding WFOs, have issued a Winter Weather Advisory for the whole CWA, in effect from midnight CST tonight to noon CST on Sunday. For most of the area, looking at a 2-5" snowfall range. This appears to be another set-up where low and mid level frontogentically driven banding component will play a role, along with fairly steep midlevel lapse rates aiding in snow intensity in at least transient more intense bands. Should a persistent more intense band develop, currently appearing to most likely to happen if it occurs north of I-80 in IL and IN, then a narrow swath of localized 5-6" amounts will be possible. Expecting snow rates to max out generally in the moderate intensity half inch to inch per hour range, though again if a more persistent intense band forms, then heavy rates of 1-2" per hour are possible at least briefly. Model forecast soundings do indicate favorable overlap of moderate to strong lift with the DGZ to support the above potential. For the southeast CWA counties (Ford, Iroquois, Newton, Jasper, Benton), have concern for mixed precipitation overnight, including sleet and even freezing rain/freezing drizzle. NAM soundings (using LAF as a proxy on BUFKIT) indicate an isothermal warm nose of about 2-3 Celsius for a few hours, with GFS only about +1 Celsius. Assuming enough ice crystal presence in the DGZ, then it appears that low level cold wedge would be enough for more of a sleet concern. However, the ice presence issue is an uncertain one as the DGZ remains on the drier side/marginal. Therefore, it`s also possible that freezing drizzle/light freezing rain could occur at times, with freezing rain also possible if refreezing of hydrometeors is less than anticipated. Have a second segment of the Winter Weather Advisory for these counties with 1-3" of snow/sleet accumulation and light glaze of ice potential mentioned. The snow/precip will overspread the area late this evening into the overnight and continue through Sunday morning before ending by around mid day. Would like to note that there is a bit of uncertainty on the start time of the snow/precip, with latest NAM and short-range guidance on the slower side. For now felt comfortable with 06z/12am CST start time, as most of the steady light/moderate to briefly heavy snow should be confined to the overnight through early-mid Sunday morning. The snow will come to an end after the passage of a mid-level short-wave trough, though it`s possible flurries could hang on through early afternoon. Temperatures will be in the teens to around 20 tonight and top out in low-mid 20s on Sunday. Wind will be fairly light northerly 10-15 mph or less tonight, shifting to northwest then west- northwest on Sunday, so blowing/drifting is not expected to be an issue. Castro && .LONG TERM... 220 PM CST Sunday night through Saturday... The main concern early in the period will be with the very cold temperatures Sunday night into Monday. However, a quiet and mainly dry period of weather is looking likely Monday through at least Wednesday. A surface ridge of high pressure is expected to build into the region Sunday night. However, the center of this high is likely to remain well northwest of the area in the Dakotas into Monday. While clear skies and a fresh deep snow pack certainly point to a very cold night across the area Sunday night, there remains uncertainty on how low temperatures will drop. This is mainly due to the fact that a light northerly wind component may continue through the night and this could keep temperatures from tanking into the teens below. However, if the winds do become very light, expect temperatures in the favored cold spots to possibly drop several degrees colder than the current forecast. Either way, it will still be a cold night across the area. Temperatures on Monday are likely to remain in the 20s for highs as the surface high gradually sags southeastward over the Lower Great Lakes. As this high shifts to New England by Tuesday, expect the surface flow to turn southerly, which should result in warmer temperatures over the area for the middle of the week. The main concern I have is that the models may be warming things to fast at the surface over the area. With snow depths across much of northern IL in excess of a foot, this does not bode well for a quick warm-up response in temperatures too far above freezing. For this reason, I have backed off on highs a bit for Wednesday and Thursday. Generally, I am keeping areas with the highest snow cover in the mid to upper 30s instead of into the 40s. Our warmest period may end up being Wednesday evening right ahead of the next cold front. This is the time when the highest dewpoints, possible into the upper 30s will try to advect northward into the area just ahead of the approaching frontal boundary. This may also set the stage for a period of very low clouds and visibilities with fog and drizzle Wednesday evening. The cold front looks to push over the area sometime on Thursday. While it then looks to get colder again later in the period, there are uncertainties on how active the weather pattern will be over the area going into next weekend. Due to these uncertainties, I will continue with a small chance of precipitation going into next Saturday. However, this chance may be able to be removed with future updates. KJB && .AVIATION... For the 00Z TAFs... Primary weather related aviation concern this TAF cycle is with the snow overnight into Sunday morning. Previous TAF had a good handle on what looks to be the evolution with snow starting toward or just after midnight with snow picking up enough to knock VSBYs down to primarily IFR. There will likely be some variation in the snow intensity which could result in periods of light snow (MVFR VSBY) and perhaps some brief periods of heavier snow (LIFR VSBY). The model consensus would favor 09-14z time frame for best chance of heavier snow and have nudged the TEMPO for LIFR VSBY forward just a bit, though suspect that LIFR VSBY would be the exception not the rule, if it happens. After picking up a couple/few inches of snow, look for snow to end later Sunday morning with guidance strongly suggesting skies clearing out in the wake of the snow Sunday afternoon. - Izzi && .MARINE... 344 pm... A trough of low pressure will shift eastward across the Ohio Valley Sunday into Monday. Another area of low pressure will quickly shift east across Ontario on Sunday, while a potent area of high pressure sets up over the northern Plains by Monday. These two pressure systems will tighten the gradient across Lake Michigan Sunday night with a period of 30kts expected. The high will move across the lakes region Monday and Monday night. Another area of low pressure is expected to quickly move across Ontario Wednesday night. This system will likely push a cold front over the western lakes region sometime on Thursday. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Winter Weather Advisory...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008- ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032...midnight Sunday to noon Sunday. Winter Weather Advisory...ILZ033-ILZ039 until noon Sunday. IN...Winter Weather Advisory...INZ001-INZ002...midnight Sunday to noon Sunday. Winter Weather Advisory...INZ010-INZ011-INZ019 until noon Sunday. LM...None. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Mount Holly NJ
954 PM EST Sat Feb 10 2018 .SYNOPSIS... Low pressure organizing over the Lower Mississippi Valley will lift to the north starting tonight, and then propagate through the region tomorrow. A cold front slides through the region Monday, and then high pressure passes north of the region Tuesday. A warm front moves into the region Wednesday before stalling. Another cold front is expected late in the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Several waves of rain will continue to track northeast into the region along a stalled frontal boundary. Through the overnight, the new 00z NAM and the HRRR are concentrating the heaviest rain across southern New Jersey south into Delmarva. Another inch or so of rain could fall which could create some local high water issues, see hydro section. Another concern overnight is fog. It has become widespread and locally dense in spots. A look at the NARRE indicates the fog will reach peak intensity and coverage during the early morning hours. However, I suspect the fog may remain widespread through most of the overnight given light winds and a high amount of moisture around. Locally heavier downpours could mix/lift the fog as well in a few spots. Temperatures should be steady throughout most of the overnight or even slowly rise with most locations in the 40`s and 50`s, some upper 30`s for the southern Poconos and northwest New Jersey. Given this is my last scheduled forecast shift (departing for WFO BGM next weekend) I want to say thank you to everyone for giving me the opportunity to serve and provide updated weather information to you. It has been a great honor. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... The axis of a positively tilted trough will approach the central Great Lakes and Ohio Valley by late Sunday. A southwest flow aloft will continue downstream with continued low-level warm air advection. The thermal advection is the most pronounced along and east of the I-95 corridor. A more pronounced short wave within the southwest flow aloft looks to move across our area through about midday. It is this feature in combination with upper-level jet forcing along with frontogenetic and frontal forcing when a band or bands of heavy rain occur. In addition, a more pronounced wave of low pressure will track along an incoming front through early afternoon. The more widespread heavier rain looks to occur through early afternoon. An initial warm front or coastal front looks to be lifting northward across Delmarva into southeastern New Jersey in the morning, however this feature may dissipate as the aformentioned main surface low arrives. However, the placement of boundaries will be key as bands of enhanced rainfall is quite possible in the vicinity of them. Some of the guidance continues to show some weak instability working northward, however this may end up not being enough to produce lightning. Despite this, the presence of a low-level jet and stronger theta-e advection may allow for some rumbles of thunder especially in Delmarva to southern New Jersey. Any convective elements will enhance the local rainfall. Given the meager look to the instability and after collaborating with WFO`s Sterling and Wakefield, we did not add thunder. For the flooding potential, see the hydrology section below and also the flood watch product. High temperatures were mostly a blend of several pieces of guidance and continuity. There may very well be a decent temperature gradient somewhere in the I-95 corridor based on the thermal fields and the placement of low-level jets. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Thanks to a progressive mostly split flow pattern, much of the long term period, especially with respect to timing of fronts and precipitation, is uncertain. Sunday night into Monday...Cold front is expected to sweep through late Sunday night. There is considerable cold air advection behind the front, with temperatures on Monday 10 to 15 degrees lower than Sunday (this is still at or slightly above normal). An even more impressive part of this front is the dry air advection behind the front. Dewpoint temperatures could be 30 degrees lower behind the front than what we saw on Sunday. Consequently, we should see the rain come to a quick end with the front. Expect a non-diurnal temperature trend through this period with the highs likely being reached early in the day. Monday night and Tuesday...A high builds closer, though the center of the high will actually pass to the north of our region. Still close enough to give us mostly dry conditions through this period. Temperatures should be near or slightly below normal. Wednesday...A warm front is expected to move into the region, but may stall over or just north of our area. As mentioned previously, a split flow pattern is expected through this period and the latest model runs show our area in between the northern and southern streams. If this trend continues, there may be little if any synoptic scale lift. Though there may be enough weak low level lift along the front for light precipitation. Thursday...One surface low may pass east through Ontario and Quebec early in the day, bringing the first chance for precipitation. However, the main focus, for now is on the second low, moving from the Ohio Valley into New England, which could not only bring another chance for precipitation late in the day, but also a strong cold front Thursday night. Friday through Saturday...Precipitation should move out of the area, at least temporarily behind the cold front. However, some long range models depict the front stalling to our south. If it stalls close enough to our area, and if we are in a favored area for lift underneath the upper level jet, we could have another period of precipitation to start the weekend. For now, there remains poor model agreement so have stayed close to the previous forecast. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...IFR and LIFR as moderate to heavy rain occurs especially overnight along with some fog. Light and variable surface winds to generally light southerly. Southwest winds near 2,000 feet increase gradually overnight to between 30 and 45 knots from about the I-95 corridor terminals on eastward, therefore low- level wind shear is maintained in the 00z TAFS. Moderate confidence. Sunday...Generally IFR or LIFR conditions with periods of rain some of which will be heavy at times through about midday. Some fog also expected. Southwest surface winds mainly less than 10 knots through the morning, however low- level wind shear due to winds at 2,000 feet around 45 knots from mainly the PHL area eastward. Surface winds increase in the afternoon, lowering LLWS risk in the afternoon. A few 20-25 knot gusts possible at KACY with a window for raised ceilings to MVFR for a few hours. Moderate confidence. Outlook... Monday and Tuesday...Mostly VFR conditions. Northwesterly winds decreasing through the morning Monday, should be less than 10 KT. Moderate confidence. Tuesday night through Thursday...VFR conditions with periods of MVFR as rain moves in. Winds less than 10 KT through the period, though direction will be variable. Low confidence. && .MARINE... South-southwest winds are expected to increase overnight as a low- level jet arrives and continues on Sunday. However, warmer air over the colder waters will reduce the overall mixing. Given the warmer air and higher dew points over the colder waters, some fog should occur although there is low confidence regarding the extent of it given the flow just above the surface. Seas have been slow to build tonight and continued to slow this trend with the evening update. A Small Craft Advisory is effect starting at 4 AM Sunday for the Atlantic waters, with conditions expected to remain below criteria in Delaware Bay through the night. Small Craft Advisory conditions Sunday on all zones with gusts 25-30 knots. Areas of fog have developed and may become locally dense overnight. Given the likelihood for visibilities below a mile, a marine dense fog advisory has been issued which runs through the overnight. Outlook... Sunday night...Winds and seas are forecast to slowly decrease through the overnight hours. Moderate confidence. Monday...Lingering showers over southern NJ/DE waters in the morning. Winds and seas should be mostly below SCA criteria. High confidence. Tuesday through Thursday...winds and seas should be mostly below SCA criteria. Moderate confidence. && .HYDROLOGY... Some flooding is possible later tonight and Sunday, and a Flood Watch remain effect through Sunday evening for much of the region. Rainfall amounts of 2-3 inches are forecast along the I-95 corridor. While the first few inches of soil may be soft, a frozen ground lies underneath mainly along and north of I-78. Given this and the moisture in the ground, runoff will be very efficient. The heaviest rain is expected to occur later tonight through about midday Sunday. The potential for low-lying flooding will begin later tonight and continue as long as the rain falls. The potential for river flooding exists Sunday and Monday. The heaviest axis of precipitation is expected to be along or near the I-95 corridor. Rivers in southeast Pennsylvania including the lower Schuylkill, and rivers in central and northern New Jersey including the Raritan and Passaic could all approach flood stage or experience minor flooding. If the Raritan basin sees the brunt of the rainfall, the Millstone River could experience moderate flooding. Visit the AHPS web site to see where our main concerns are. && .CLIMATE... Record highs for today, 2/10... ACY 60 in 2001 GED 70 in 1960 For February 11th, at this time the only climate site that may have their record high temperature challenged is Georgetown, Delaware. The current record high temperature for this location is 71 in 2009. We are also looking at possible record daily rainfall for either today or Sunday. The records are below for reference. 2/10 2/11 ACY 0.90 2010 1.70 1886 PHl 1.10 2010 1.85 1983 ILG 0.90 2010 1.62 1983 ABE 1.40 2010 1.40 1983 TTN 1.20 2010 1.60 1983 GED 1.30 1967 2.10 1994 RDG 1.50 2010 1.26 1886 MPO 2.74 1998 2.47 1960 For 2/10 the water equivalent is probably just that, an estimate from a snowstorm in 2010. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Flood Watch through Sunday evening for PAZ060>062-070-071- 101>106. NJ...Flood Watch through Sunday evening for NJZ007>010-012>027. DE...Flood Watch through Sunday evening for DEZ001-002. MD...Flood Watch through Sunday evening for MDZ008-012-015-019-020. MARINE...Dense Fog Advisory until 6 AM EST Sunday for ANZ430-431- 450>455. Small Craft Advisory from 4 AM Sunday to 6 AM EST Monday for ANZ450>455. Small Craft Advisory from 10 AM to 6 PM EST Sunday for ANZ430- 431. && $$ Synopsis...Johnson Near Term...Gaines Short Term...Gorse Long Term...Johnson Aviation...Gaines/Gorse/Johnson Marine...Gaines/Gorse/Johnson Hydrology... Climate...
Area Forecast Discussion
National Weather Service Blacksburg VA
910 PM EST Sat Feb 10 2018 .SYNOPSIS... A front to the west will stall overnight allowing for a soaking rain to impact the region into Monday. The front will eventually move through on Monday and be replaced by high pressure for Tuesday and Wednesday. Another cold front will move through the forecast area late in the week. && .NEAR TERM /THROUGH SUNDAY/... As of 905 PM EST Saturday... Rain remains widespread across the region with the heaviest axis now out along the Blue Ridge where seeing some elevated convective elements embedded within the main shield of rain. However this where flash flood guidance remains higher so plan to keep the going watch where already in place and not expand east at this point. Otherwise main threat continues over the far west where have seen nearly continuous rainfall since late this afternoon with totals now around 1.5 inches in spots. Latest short term guidance showing perhaps a slight diminishing trend over the next few hours as an initial wave exits before more fills in overnight. Appears rates may also decrease a bit but something to watch. Temps remain slow to rise given heavier rainfall and the southwest jet aloft basically stuck above a decent low level inversion. Thus have lowered readings to start and cut back on rises some until late when the inversion may finally mix out. Previous update as of 638 PM EST Saturday... Many locations in the VA/NC Piedmont are currently experiencing a good amount of fog, as these areas have cleared from rain at least temporarily. Lynchburg, Danville and Brookneal have seen visibilities in fog as low as 1/4 SM, and this fog also extends down into the NC Triad, especially in the Greensboro area. Further west, we also see some patchy mist or fog interspersed with light/moderate rains, but visibilities here are expected to be a little greater given start of heavier rains (mentioned below). I`ve added patchy fog across essentially much of the forecast area through tonight, and also issued a special weather statement to address fog potential, with stronger wording for occasional, though transient, dense fog in the Piedmont. Steady light to moderate rain has now overspread most locations from the VA/NC foothills westward. However, an uptick in rainfall intensity is anticipated for these locations through 8 PM through extrapolation of heavier bands of rain in the TN Valley and per high-resolution model guidance. Do think that the WRF-NMM model is a bit aggressive in terms of simulated reflectivity and rain totals. For timing purposes, I shaped PoPs using a blend of some of the better-performing HRRR and 3-km NAM into the current forecast. Would expect onset of steadiest moderate to heavy rain to be around 01-02z in the far southwest and advancing to the northeast/east as the overnight progresses. Main message is that the first burst of heavier rains is expected during the late-evening/overnight hours. At least in the next 3-6 hrs, will need to keep close watch on rivers/streams in Tazewell County and into the upper reaches of the Tennessee River with the approach of steadier/heavier rainfall. Already noting some modest to moderate response on some of these river gages in the Clinch and Holston basins. No other changes needed to other elements attm. Previous discussion issued at 345 PM... Cloud cover will continue to be persistent over the region through the forecast period. Temperatures will struggle to warm as high as previously forecast however there really is no diurnal trend to speak of during this time period. That being said, temperatures may continue to warm a few more degrees after the typical peak heating time under strong southerly flow, per high resolution guidance. During the evening, forecast lows will not vary much from the forecast highs with several high-minimum temperature records in play for the 11th. Winds will be light for much of the forecast period but will tick up a bit in the early morning hours into the day Sunday as the low center passes just to the west of the region. The band of rain that traversed the forecast area earlier in the day continues to pour on the northern counties. A surface boundary to the west will stall near the region overnight. The baroclinic zone associated with that boundary will begin to impact the region this afternoon as it enters from the west. This combination will make for conditions of regularly moderate or heavier intensity rain across much of the forecast period through Sunday. During the afternoon on Sunday, a significant warmup into the 60s for many under continued strong southerly flow can be expected. Further, as the low passes nearest the region early morning into the day tomorrow shear will increase and slight chances for thunderstorms will exist, mainly in the piedmont. The flood watch remains for areas near the Blue Ridge and west through 7AM Monday. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 240 PM EST Saturday... Overall little change this period as front stays situated along and just south of the forecast area Sunday night into Monday. Question will be drying out on the northwest side before colder air works in changing any precip to a wintry type. At the moment models are leaning toward little wintry precip across the Alleghanys into WV, with the colder air staying further north, so all rain for us. The rain will be more numerous Sunday evening, then in the southeast Monday as another wave of low pressure moves along the front across GA/SC with easterly flow keeping deeper moisture in the Carolinas and southern VA. Strong high over the Great Lakes looks to push the precip further south by Monday night, but on the backside an inverted trough sets up along the southern Appalachians. Though deeper moisture is gone, low level moisture remains so kept chance pops around for most of the forecast area. May start to see wintry precip, light in intensity by late Monday night/early Tuesday as colder air works into the low levels as a wedge sets up. At the moment, have it as rain vs snow. Temps this period will be close to normal. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 300 PM EST Saturday... Somewhat active pattern as southwest flow becomes more zonal midweek. High pressure works over the area but models are slow in dispelling all the moisture such that will keep low chance pops around. Front arriving Thursday will slide in from the northwest, then orient itself from east to west keeping a fairly decent threat of rain Thursday into possibly Friday. Still a lot of variability in the models on this set up. Therefore kept pops around into Saturday. If colder air can push in with the front set up to our south, we could see another shot of wintry wx, though upper pattern favors more rain vs wintry mix as opposed to snow, with wedge in place, but for now keeping it rain vs snow. Temperatures will be seasonably cool Tuesday with wedge, then we warm up Wed-Thu, with some cool down Fri-Sat. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... As of 638 PM EST Saturday... Significant impact to aviation operations in the 00z TAF period from IFR to LIFR conditions from both ceilings, fog and heavier rains, mtn obscuration as well as low-level wind shear. With very few exceptions, most TAFs are presently IFR to LIFR. LIFR fog is most common in the Piedmont (affecting Lynchburg and Danville) as these areas have cleared of rain, while MVFR- IFR visibilities in rain/fog more common across the rest of the TAFs. Would expect fog to thin as heavier rains move in after 02z, but visbys still commonly 2-4 SM in moderate to at times heavy rain overnight. Ceilings generally expected to be rather stable LIFR/IFR. Strong winds aloft will also contribute to areas of low-level wind shear tonight into early morning Sunday as winds will be light to calm. Likely to have continued moderate/heavy rain lingering into the early morning hours, but a little bit of a break should allow for more IFR to MVFR conditions by late morning. Next round of rain and even some possible thunder toward Sunday afternoon. Timing this next round of rain is low and will only leave VCSH or a VFR -RA late in the TAF period. South winds increase to 6-12 kts Sunday. Moderate confidence in ceilings. Low to moderate confidence in visbys. High confidence in winds. Extended Aviation Discussion... Mainly MVFR ceilings and reduced visibilities will continue through Sunday night. High pressure begins to build into the region Monday and ceilings are expected to lift to VFR at most locations, with some upslope low clouds still probable at KBLF/KLWB. A low level wedge will then develop by Tuesday as a weak system scoots by to the south and helps low level moisture return into Tuesday night. This may keep sub- VFR around wit low ceilings again Tuesday/Tuesday night before some slow improvement occurs as the wedge weakens on Wednesday. && .HYDROLOGY... As of 350 PM EST Saturday... Flood watch remains in effect from this evening through Monday morning for areas near the Blue Ridge and West. The entire forecast area is expected to get 1-4 inches of rain from Saturday through Monday, with the heaviest rain expected to occur on Sunday. Streams across the entire service area are expected to rise, with significant rises anticipated for mountain streams. The headwaters of the Greenbrier River and upper reaches of the James River will also receive contributions from snowmelt. This will add to the flood potential. At this time, the river basin which will likely be most effected from snowmelt is the Greenbrier. Upwards of an inch of liquid equivalent water is suspended within the snowpack. If this snow melts at the same time as the occurrence of the heaviest rain, then flooding will become likely along the Greenbrier River. Confidence is increasing that minor to potentially moderate flooding may occur during the Sunday to Monday time frame for the Greenbrier River at Alderson. Those living particularly along the Greenbrier River should begin taking precautions. The river level at Alderson is already half bank full from the previous rain event, which means it will not take as long to reach flood stage if heavy rain occurs upstream. You should monitor later forecasts and be alert for possible Flood Warnings. Those living in areas prone to flooding should be prepared to take action should flooding develop. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Flood Watch through Monday morning for VAZ007-009>020-022>024- 032>035. NC...Flood Watch through Monday morning for NCZ001>003-018-019. WV...Flood Watch through Monday morning for WVZ042>044-507-508. && $$ SYNOPSIS...JR NEAR TERM...AL/JH/JR SHORT TERM...KK/WP LONG TERM...KK/WP AVIATION...AL/JR HYDROLOGY...KK/PM
Area Forecast Discussion
National Weather Service Shreveport LA
807 PM CST Sat Feb 10 2018 .AVIATION... For the 11/00Z terminal forecast will prevail all the sites across the Four State Region with IFR and below for the overnight and through most of the first of Sunday. MVFR ceilings will be returning during the early to middle morning for parts of East and Northeast Texas and the more Eastern sites in the middle to late afternoon Sunday. Surface winds will be light Southeast out to the East of a cold front and to the West and Northwest 10-15 knots in wake of the boundary. /06/ && .PREV DISCUSSION... /issued 331 PM CST Sat Feb 10 2018/ DISCUSSION... Large area of shwrs associated with a series of shortwaves and a cold front has pushed ewd, and is only affecting our far sern parishes. Meanwhile, shallow cold airmass continues to bend around the Ouachita Mountains of SE OK/SW AR and spill into N TX. As a result, cold air has begun to spill in to portions of E TX, while leaving our SW AR counties still in the upper 50s and lower 60s. Model solutions vary, and in general do not handle the shallow cold airmass damming across our nrn areas, but the cold air will eventually get deep enough to overcome the terrain tonight. HRRR seems to be handling the hourly evolution of temps well, so have used this in the short term. Patchy light rain and drizzle will continue to be possible through the overnight hours, as sw flow aloft overruns the cold air at the sfc. This will coincide with temperatures near or just below the 32 degree mark across portions of NE TX, SE OK, and SW AR, especially after midnight. Any accumulation will be very light and mostly confined to elevated surfaces, including bridges and overpasses. The potential impact to travel across these areas has led to the issuance of a Winter Weather Advisory from midnight through 10 am Sunday. Temps should warm above freezing Sunday morning, ending any ongoing travel impacts. Isold to sct shwrs will continue to be possible Sunday and Sunday night before a drier airmass sinks swd Monday. However, swly flow aloft will keep us in an unsettled pattern, with rain chances returning Tuesday and remaining through the work week. Chances for more widespread, heavier rain will come into play Friday through the weekend, as a strong disturbance over the Desert SW moves ewd into the Southern Plains. Temperature trends this pd will be below normal through Monday, but a warming trend will take us into the 70s for some areas by mid week. /12/ && .PRELIMINARY POINT TEMPS/POPS... SHV 39 47 37 51 / 50 40 20 10 MLU 50 53 38 48 / 60 50 30 20 DEQ 31 42 29 52 / 40 20 20 0 TXK 35 43 32 50 / 50 20 20 0 ELD 43 47 34 50 / 60 40 20 10 TYR 32 40 32 53 / 30 30 20 10 GGG 34 43 34 53 / 40 30 20 10 LFK 40 47 37 55 / 50 30 20 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...Winter Weather Advisory from midnight tonight to 10 AM CST Sunday for ARZ050-051. LA...None. OK...Winter Weather Advisory from midnight tonight to 10 AM CST Sunday for OKZ077. TX...Winter Weather Advisory from midnight tonight to 10 AM CST Sunday for TXZ096-108>111-124-125-136. && $$ 06/12