Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/19/16


Area Forecast Discussion
National Weather Service Burlington VT
944 PM EST Fri Nov 18 2016 .SYNOPSIS... Ridge of high pressure will crest overhead today keeping the North Country dry with above normal temperatures through Saturday. Late on Saturday a deep trough with an associated cold front will bring rain and terrain driven snow showers Saturday night and Sunday. The chance for precipitation will continue through Monday night, with persistent cold air advection seeing the rain transition to snow late in the weekend and into Monday morning. && .NEAR TERM /UNTIL 6 PM SATURDAY EVENING/... As of 944 PM EST Friday...Just some additional minor tweaks to sky/weather across the northern tier of NY into far northwestern VT through the overnight hours per latest hi-res modelled cloud cover and visibility progs. Patchy dense fog has bled down into portions of the northern Champlain Valley as of 900 pm and per HRRR output this could hang on a few hours longer before developing southerly flow on back side of departing ridge leads to dissipation. Stubborn low stratus still making a run at northern SLV as well, though outside this immediate area mainly clear skies are expected with some customary mist/fog developing across eastern VT counties later tonight. Current forecast has this well covered. Low temperatures a bit trick per radiational effects and building warm thermal advection aloft. Case in point is Mt. Mansfield summit which current sits at 57F while Whiteface summit near 4900 feet sits at 54F. Meanwhile lower elevations dropping into the 30s to around 40 in most spots. The fog should lift quickly tomorrow as we mix during day break and tomorrow afternoon should be another pleasant day through the afternoon with clouds increasing from the west during the late afternoon. High temperatures again running quite mild from the upper 50s to around 60 in eastern VT, and in the lower to mid 60s from the Champlain Valley west. Get out and enjoy it. This will be the last mild weather for quite some time. && .SHORT TERM /6 PM SATURDAY EVENING THROUGH SUNDAY NIGHT/... As of 304 PM EST Friday...Winter storm watches have been posted for late in the weekend across portions of the North Country, including the Northern Adirondacks, St. Lawrence Valley, and central VT, including the western slopes of the Green Mountains. Snow levels expected to drop during the day Sunday, with potential moderate snow accumulations areawide during Sunday night. Active period of weather as large upper level low shifts from Southeastern Ontario and the ern Great Lakes early Saturday night, and then slowly across northern New York and northern New England through 12Z Monday. Widespread precipitation will develop from west to east across the area during Saturday night and continue into Sunday before slowly becoming more terrain driven Sunday night. Precipitation will initially fall as rain given very mild air mass in advance of the upper trough. However, associated surface frontal zone shifts east of the Adirondacks by midnight Saturday night, and gradually allows colder air to filter in across nrn NY, and eventually across VT during the daylight hrs Sunday. This will allow snow levels to gradually fall across the region. By 06Z Sunday, snow levels should drop to around 1500-2000ft, which allows for a change over to snow across nearly all of the nrn Adirondack Region. Should see at least a couple of inches of snow accumulation by mid-morning Sunday in the Adirondacks. Elsewhere in nrn NY, will see some wet snow mixing in Sunday morning, and snow levels falling to the valley floors by early Sunday afternoon. A bit slower transition in VT with slower arrival of colder air, but should see accumulating snow above 1000` Sunday in VT. As the upper level low moves east- northeast Sunday night that will put the area in a more favorable northwest flow pattern and orographic snows should really develop at that point and increase snowfall rates. At the same time...colder air will finally make it down to the lower elevations in VT, and just about everyone will have the potential to see accumulating snowfall during Sunday night. This will be the first snowfall of the season on some valley roadways, and absence of antecedent road treatment will leave most paved surfaces quite prone to becoming snow covered/icy. Thus, the Monday morning commute could be very slow across the region, including in the Champlain Valley. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 304 PM EST Friday...Long-duration orographic snowfall expected to continue Monday into Monday night. Vertically stacked low pressure will move very slowly ewd across central and nrn ME during the period, with a persistent moist NW flow regime across nrn NY and Vermont. Snowfall will be intermittent in the valleys, but orographic/upslope forcing should result in continued frequent snow showers along the wrn slopes of the Green Mtns, nrn Adirondacks, and adjacent areas thru Monday night. Storm total snowfall amts could reach 12"+ for the higher summits of nrn Adirondacks and central/nrn VT. Generally 4-8" across the wrn slopes of the Green Mtns and in the immediate St. Lawrence Valley. Lower snowfall amts in the Champlain Valley, but again, Monday morning commute will likely be very slow with slick, snow covered roadways even with lower accumulations. The vertically stacked low eventually shifts into the Canadian Maritimes, with higher elevation snow showers diminishing late Monday night into Tuesday. High pressure should bring a quieter period of weather later Tuesday through Wednesday. Progressive mid-upr level flow pattern brings next frontal system ewd from the Great Lakes Wednesday night into Thanksgiving day. Still considerable differences in low track between 12z GFS and ECMWF, with ECMWF suggesting less direct impacts to the North Country, while the GFS suggests mixed wintry precipitation is possible with some travel impacts later Wednesday night and Thanksgiving Day. Current forecast is for 40-50PoPs during the period. Will continue to monitor this possible system for the holiday period. && .AVIATION /03Z Saturday THROUGH Wednesday/... Through 00Z Sunday...Mix of flight categories is expected over the next 24 hours with primarily VFR at KBTV/KPBG/KRUT. At KMPV and KSLK, like last night expect VLIFR radiational fog to develop around 06Z give or take an hour, and continue through 12-14z. At KMSS, upstream near Montreal low IFR stratus deck has developed and hi-res model progs show it slowly building southwestward on light northeast flow into the northern St. Lawrence Valley. Time of arrival is around 06z, and when it builds in it should last until 12-14Z accompanied by some MVFR vsby. After 14z, all site trend back to VFR. Outlook 00Z Sunday through Wednesday... 00Z Sun - 12Z Tue: VFR trending to MVFR/IFR as a strong cold front brings rain/snow showers to the region. Gusty winds and LLWS possible. 12Z Tue - 00Z Wed: MVFR trending to VFR with high pressure returning. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Winter Storm Watch from Sunday morning through Monday evening for VTZ003-006-008-016>019. NY...Winter Storm Watch from late Saturday night through Monday evening for NYZ026-027-029>031-034-087. && $$ SYNOPSIS...Deal NEAR TERM...JMG/Deal SHORT TERM...Banacos LONG TERM...Banacos AVIATION...Lahiff
Area Forecast Discussion
National Weather Service Cleveland OH
715 PM EST Fri Nov 18 2016 .SYNOPSIS... Low pressure over the western Great Lakes will move east and reach Maine by early Sunday. A strong cold front associated with this low will sweep east across the local area late tonight and early Saturday. High pressure will begin to build over the region from the southwest on Sunday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Regional radars depict a line of showers and thunderstorms moving east across Indiana early this evening. Several severe thunderstorm warnings have been issued with peak wind gusts in the 60-65 mph range. The stronger part of the line of convection is expected to move northeast into Michigan. The airmass east of the line becomes increasingly less favorable for convection with a cap aloft and dewpoints in the 40s. Storms are both expected to continue weakening as they approach the area with the near surface environment becoming less conducive for strong wind gusts to reach the surface. Whatever stable layer develops will be shallow however so we will continue to monitor convection closely as it moves into the area over the next couple hours. Wind gusts to 40 mph seem the more likely scenario but can not rule out an isolated stronger gust. Sheer aloft is tremendous with the VAD wind profile off the IWX radar showing 50 knots near 4000 feet. Previous discussion... Clear skies to begin this evening but clouds will increase from the west during the evening. Have rain moving into western counties after 8pm. The nam12 shows capes of 200to 800j.kg get into the western counties this evening and lightning data shows a decent amount of lightning along the front in eastern Illinois so will have a slight chance of thunder west half through the evening. Temps at 850mb will drop below freezing after 09z in the western counties so all precip should be rain. will have categorical pops for all and attempted to move the band of rain east across the area through the night in the grids. Temps ahead of the boundary will be quite mild into the night with warm advection ahead of the system. Used HRRR and rap13 for insight into hours temps with cold advection moving in from the west after 06z. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/... Cold air will continue to fill in saturday behind a strong cold front that will be exiting the area around sunrise. Initially...slightly drier air and subsidence will fill in behind the front but wrap around moisture will fill back in during the day so will keep pops high chance to categorical with best chance north. Precip type should be all rain to start but -8c air at 850mb fills in quickly from the west during the morning. This should allow snow to mix in from the west during the morning with the transition shifting east through the day reaching eastern counties mid/late afternoon. Accums should not be much of anything as ground temps will remain above freezing and air temps as well should remain above freezing through the day. Saturday night most precip will be snow except possibly over the lake where low level warmth off the lake will change the snow to rain near the surface. Based on Bufkit forecast soundings and coordinating with WPC and surrounding offices...best snow accums should occur across NWRN PA inland with the lakeshore likely too close to the warm Lake Erie to accumulate warning criteria snow. Inland however...expect the event to drop upwards of around a foot in the highest elevations east. Have issued a Lake Effect Snow Watch. Started it at 21z Saturday to cover any mix or transition but best chance for lake effect snow comes after midnight. Lake/850mb instability reaches extreme and winds stop consistent from the northwest after midnight Saturday continuing into Sunday night before tapering early Monday so will continue the watch through Monday morning. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Cold air will continue to flow across the warmer waters of Lake Erie on Monday. So this will keep Lake Effect snow showers going through the day across NE OH in NW PA. They will likely linger the longest over the higher terrain of inland NW PA. The snow should end at some point Monday evening as high pressure increases its influence. This area of high pressure will then become the dominant feature through Tuesday afternoon. Models are then in good agreement on the movement of another strong storm system that will emerge from the Southern Plains. All locations will warm ahead of this low Tuesday into Wednesday. Locations that do not get significant snow this weekend will warm to near or slightly above seasonal levels. The cold front will sweep across the area Wednesday night with another round of showers. Winds will again increase with this storm system. && .AVIATION /00Z Saturday THROUGH Wednesday/... A season changing low pressure system will move across the Great Lakes tonight...with multiple aviation concerns. Convective line across eastern IN has run out ahead of the cold front and will pose a threat to TOL/FDY. There are stronger elements within the line where a gust in excess of 40 knots is possible...with 30 knots more likely. The line will continue to the northeast...with expected diminishment over the next couple of hours. Outside of the showers VFR conditions will continue through the early evening hours. Additional showers possible overnight with the frontal passage. Best estimate on timing would be around 06Z TOL to 10 or 11Z CLE. Non- VFR possible again with the showers and likely for a couple of hours behind it. Winds will abruptly shift to the west with the passage of the front and gusts will commence...continuing through Saturday. Gusts to 40 knots possible. Lesser confidence on what ceilings will do for the daytime Saturday...but thought is that we will see a period of VFR before wrap around moisture overspreads the entire area from midday through the late afternoon. The transition to scattered snow showers reaches western terminals late afternoon and evening across central terminals. OUTLOOK...Non-VFR conditions in showers will change to snow Saturday night and linger into Monday...primarily across extreme NE OH and NW PA. Non-VFR possible again Wednesday. && .MARINE... Strong area of low pressure will move across the western Great Lakes tonight then redevelop over southern Ontario on Saturday. Expect the pressure gradient to increase ahead of this storm system tonight but the strongest winds will develop as the cold front passes. Strong cold advection in the wake of the front will assist in bringing stronger winds down to the surface. It appears gale conditions will develop late Saturday morning into the afternoon then continue into Sunday. Will go ahead and change the Gale Watch to a Gale Warning shortly. Winds will decrease Sunday night with an extended period of small craft conditions expected into Monday night. High pressure will then briefly take control of the region Monday night into Tuesday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...Lake Effect Snow Watch from Saturday afternoon through Monday morning for PAZ002-003. MARINE...Gale Warning from 1 PM Saturday to 4 AM EST Monday for LEZ061- 145>149-165>169. Gale Warning from 10 AM Saturday to 4 PM EST Sunday for LEZ142>144-162>164. && $$ SYNOPSIS...TK NEAR TERM...KEC/TK SHORT TERM...TK LONG TERM...Mullen AVIATION...Oudeman MARINE...Mullen
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
948 PM EST Fri Nov 18 2016 .SYNOPSIS... A strong cold front will move across the Carolinas from the west on Saturday, bringing increased rain chances along the North Carolina and Tennessee border. Temperatures in the wake of the front will drop to approximately ten to fifteen degrees below normal on Sunday and Monday before moderating through midweek. Another cold front will approach the area by the middle of next week. && .NEAR TERM /THROUGH SATURDAY/... (Please also see updated Fire Wx section below.) As of 930 PM: A vigorous upper level trough will lift NE out of the lower MS Valley tonight and across the CWFA on Saturday. It will take on a negative tilt and bring only a brief shot of strong DPVA and some moisture along the TN/NC border Saturday morning. Guidance is in good agreement on a weakening line of showers crossing the TN Valley overnight and reaching the Smokies just before daybreak. 00z NAM is generally a little drier than the 18z; QPF has trended down over the past few HRRR runs, which is an even worse sign as it so often overdoes precip. So there still appears no need for mentionable PoPs east of the mountains. Temps will be above normal tonight, as SWLY flow increases. Expect good radiative conditions to persist thru the early morning hours before cloud cover ramps up and winds start to stir up the PBL. On Saturday the big concern will be winds and fire danger (see fire weather section below). As the upper trough axis shifts east, a trailing NWLY upper jet will punch into the CWFA, and push a dry cold front thru the area early in the morning. 18z NAM/GFS did not trend significantly earlier/later with the frontal depiction than the 12z runs, so timing of the effects still looks good. At 850 mb, winds will increase and veer to NW at about 35 to 45 kts behind the front by early afternoon. A tight temp gradient will result in very strong CAA, with 850 mb temps plummeting from around 10-12C at 12z to -5c by 00z Sunday along the northern Blue Ridge escarpment. Gusty winds will approach wind advisory criteria across the highest peaks of the NC mountains, generally along and NE of the French Broad Valley. The gusty winds will continue into Saturday night (3rd period), and given some uncertainty, I will hold off on any wind headlines with this forecast package. Temps will have a non-diurnal trend in the mountains due to the CAA, with highs around mid-late morning, then falling temps in the afternoon. Temps in the Piedmont will be tricky in the afternoon, as well, but still expecting low-mid 60s, which is near normal. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 215 PM Friday, An anomalously strong long wave trough along the East Coast will result in unseasonably cool and very dry conditions across the forecast area through the short term. These conditions will create very low afternoon RH across the area Sun and Mon. Fire Wx concerns will therefore persist through the period. Please see the Fire Wx discussion for details. Wind concerns become amplified on Sat night, mainly along the eastern escarpment of the Blue Ridge, as deep/unidirectional and strong NW flow, with attendant strong mountain wave signal depicted in model cross-sections. H8 winds in the latest NAM guidance are as high as 55 kts near the Blue Ridge Sunday morning. This is still quite strong, but about 10 kts less than yesterday`s guidance. There is still concern that a nocturnal downslope/mtn wave high wind event could occur along/near the eastern escarpment during this time, but considering the trends in guidance, do not plan to issue a High Wind Watch at this time. Otherwise, winds will gradually diminish on Sunday, while cool temps will prevail through the period, with temps averaging 5-10 degrees below climo. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 215 PM EST Friday, no significant changes to earlier thinking with regard to Monday night and Tuesday, as models show an upper ridge to the west and high pressure at the surface. This should keep dry weather in place thru the end of Tuesday. Then, our attention turns to the next system expected during the middle of the week. Once again, the model guidance strongly suggests that precip will not reach the fcst area before daybreak Wednesday. The new ECMWF has the leading edge no closer than middle TN at 12Z Wednesday, and the GEFS has NO members with precip at KAVL by that time. Even the faster op-GFS does not have precip reaching the mtns until after 18Z Wednesday, so like yesterday, the onset was pushed back until later in the day. As for precip potential, the models have taken a slightly more encouraging trend with better moisture transport from the Gulf, altho forcing looks a bit weaker. Right now, think the moisture is the more important factor. At least the downward and drier trend has been halted, so precip probability still ramps up to the chance range everywhere Wednesday evening. That being said, there will probably be a lot of losers with this one, at least E of the Blue Ridge. Precip amts are likely to be on the order of a quarter-inch for those lucky ones. The precip should move east quickly as the front passes in the early morning hours Thursday. Will hold onto a slight chance over the Piedmont zones into Thursday morning in deference to the slower ECMWF, altho the timing of the GFS is preferred. Some light precip should linger on the TN border of the nrn mountains into early Thursday afternoon. The rest of the fcst will be dry as the next high pressure air mass moves in from the west. Temps should remain fairly close to normal thru the period as the air mass change behind the front will be offset with downslope warming, with the expected nearly zonal flow aloft. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... At KCLT and Elsewhere: Though the area will remain dry overnight, pressures fall ahead of a swift cold front that will move through in the morning. Winds will continue out of the SW, generally being light overnight, but picking up rapidly after daybreak. KAVL may see a westerly crosswind for a time near daybreak before the low level flow veers solidly NW. WSHFT should reach KCLT by around noon. A brief period of low VFR cigs is expected near the wind shift line. Otherwise, the only restrictions (if any) around the region will be due to smoke, with relatively dry and increasingly breezy conditions precluding AM fog development. Smoke from the foothills wildfires will linger near KAVL/KHKY tonight. These plumes should be carried downwind into the eastern Piedmont (and KCLT) in the late morning; strengthening winds and deeper mixing should improve vsbys at midday. Outlook: High pressure basically prevails into next week, with fire wx conditions worsening as cold and dry Canadian air pushes in Saturday and keeps humidity exceptionally low for several days. Winds will remain strong over the high terrain Saturday night, with gusty conditions returning to the Piedmont Sunday. Smoke concentrations across the region will remain a concern for the foreseeable future, especially during nights, when vsbys fall into the MVFR range in some spots as the boundary layer decouples. Confidence Table... 02-08Z 08-14Z 14-20Z 20-00Z KCLT High 100% High 100% High 100% High 100% KGSP High 100% High 100% High 100% High 100% KAVL High 83% High 83% High 98% High 100% KHKY High 83% High 100% Med 70% High 100% KGMU High 100% High 100% High 100% High 100% KAND High 100% High 100% High 100% High 100% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: www.weather.gov/gsp/aviation && .FIRE WEATHER... Red Flag Warning in effect for Upstate SC Saturday. Fire Danger Statement for the remainder of our area Sat through Sunday. A cold front will cross the region from the west Saturday morning. The area with the best chance of rain will be the NC mountain counties along the TN border, with some snow possible on the high peaks and ridge tops of the Smokies. Even in these areas, any precipitation will be very light. Winds will come up sharply from the northwest behind the front. Wind gusts of 25 to 40 mph are likely across much of the area Saturday, and across the mountains Saturday night. Winds may even be stronger in locations along the Blue Ridge, esp Sat night. Gusty conditions will gradually diminish Sunday. Although RH is not quite expected to reach criteria on Saturday (25-30 percent across the Upstate and generally 30-45 percent across much of western NC, based upon the volatile conditions re: fuels, collaboration with the USFS, SCFC, and the Pinnacle Mountain Incident Command Team has resulted in a decision to issue a Red Flag Warning for Upstate SC for tomorrow. A Fire Danger Statement will be issued for the remainder of the forecast area Sat through Sunday. Very dry high pressure building into the area early in the week will result in very low afternoon RH Sunday through at least Tue. Meanwhile, winds will remain gusty across the mtns through part of the day Sunday. While the current forecast does not feature an overlap between RFW criteria winds and RH, it will be close. Hence, a Fire Danger Statement has already been issued valid at that time. Some offices/agencies are already interested in an "impact-based" Fire Wx Watch for at least the NC Mountains, and parts of Georgia. Rather than make a decision on such a watch this evening without being able to consult land managers and fire officials, we opted to let the Fire Danger Statement ride for now, and will advise next shift to reach out to those representatives. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...Fire Danger Statement from 9 AM EST Saturday through Sunday evening for GAZ010-017-018-026-028-029. NC...Fire Danger Statement from 9 AM EST Saturday through Sunday evening for NCZ033-035>037-048>053-056>059-062>065- 068>072-082-501>510. SC...Red Flag Warning from 11 AM to 8 PM EST Saturday for SCZ001>008-010>013-019. && $$ SYNOPSIS...JPT NEAR TERM...ARK/Wimberley SHORT TERM...JDL LONG TERM...PM AVIATION...Wimberley FIRE WEATHER...JDL/Wimberley
Area Forecast Discussion
National Weather Service Wilmington OH
1013 PM EST Fri Nov 18 2016 .SYNOPSIS... A cold front will push through tonight, bringing showers and gusty winds. Colder air will settle in behind this front for the rest of the weekend with bluster conditions, along with the possibility of the first snow flakes of the season. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Cold front is just west of the CWFA this evening. Showers continue along and behind the front. Latest 00Z NAM and 02Z HRRR indicate that the front will become more anafront in nature, with precipitation along and mainly behind frontal passage. This is in part to digging s/wv energy within a large scale mid level trough, along with upper level divergence from a the RR quad of an upper level jet. So, will maintain categorical PoPs overnight with showers. Winds will shift to the west and will become gusty with gusts in the 25 to 30 knots. Much colder air will filter in behind the front, with lows ranging from the upper 30s west to the lower 40s east by sunrise. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Mid/Upper level trof to pivot east through the Great Lakes Saturday/Saturday night. In the wake of the overnight cold frontal passage strong CAA will be ongoing Saturday morning. Expect near steady temperatures on Saturday. In strong CAA pattern low level lapse rates steepen leading to scattered showers with the best chance of showers north. The rain will showers transition to snow showers late in the afternoon into early evening. Looking at forecast soundings and using the momentum transfer technique expect wind gusts up to 40 mph. As the upper trof axis pivots east, surface high pressure will begin to southwest Ohio. Precipitation will diminish, ending from sw to ne Saturday night. Expect lows from the mid 20s sw to near 30 ne. Northwest flow aloft with surface high pressure building southeast into the region Sunday. Cold temperatures Sunday with highs from the upper 30s ne to the lower 40s sw. Light winds, clear skies and dry airmass will allow for cold temperatures Sunday night. Expect lows in the lower and middle 20s by Monday morning. && .LONG TERM /MONDAY THROUGH FRIDAY/... Monday will have dry weather under high pressure. Dry conditions will continue through Tuesday as the high gradually moves east, though clouds will increase well ahead of the next low pressure system. Vigorous low pressure and its associated cold front will bring the likelihood for showers on Wednesday. A few showers will linger into Thursday in the chilly northwest flow behind the low. High pressure centered to the southwest should provide dry weather for Friday. Temperatures will start a bit below normal, with highs Monday in the low to mid 40s. Modest warm advection will allow near normal to slightly above normal highs in the mid 40s to mid 50s for Tuesday through Friday. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... As low pressure rotates northeast into the Great Lakes tonight, a trailing cold front will push east through the region. It appears that instability will wane this evening that showers/storms associated along and ahead of the front will be just showers as they affect the terminals. MVFR ceilings and visibilities can be expected with showers overnight. Once behind frontal passage, a dry slot will move into the region. Any wrap around precipitation will be of low coverage, and probability, across the northern terminals as not to mention. Winds will veer to the west behind the front with gusts in the 25 to 30 knot range. On Saturday, surface low pressure and its parent mid level low will occlude and rotate southeast across the eastern Great Lakes. Predominate MVFR ceilings can be expected at the terminals until the 18Z to 20Z time frame, when ceilings should lift to VFR. The combination of a tight pressure gradient at the surface and diurnal mixing will push winds gusts into the upper 20s to the lower 30s by this time. For Saturday night, clouds may scatter near the southwest terminals of KCVG/KLUK while they linger across the north. A few snow showers will be possible downwind of Lake Michigan near the northern terminals. Gusty winds will gradually lower overnight. OUTLOOK...MVFR ceilings and visibilities possible on Wednesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hickman/AR NEAR TERM...Hickman SHORT TERM...AR LONG TERM...Coniglio AVIATION...Hickman
Area Forecast Discussion
National Weather Service New Orleans LA
956 PM CST Fri Nov 18 2016 .UPDATE... We made some changes to the precipitation field to fit the ongoing trend. As stated in an earlier sounding discussion, this evening sounding revealed strong cap with temp increase with height of 4C from 830mb to 810mb. Line of convection pushing into the area struggled to hold and weakened as forecast. We lowered rain chances but maintained a slight chance for most points overnight. && .PREV DISCUSSION... /issued 705 PM CST Fri Nov 18 2016/ SOUNDING DISCUSSION... Routine release terminated near Interstate 10 mile marker 40 in Harrison County Mississippi at a height of 107,400 feet or 20.3 miles above the surface. A little more moisture in tonight`s sounding with the precipitable water value at 0.90 inches. There is some moisture below an inversion based near 825 mb, as well as above 400 mb, with very dry air in between. Moisture levels will increase during the evening, as the 00Z LCH sounding has a precipitable water value around 1.4 inches. The dry layer on the LCH sounding is only between 700 and 550 mb. The inversion on the LIX sounding has things capped presently, but this is expected to erode as the front nears. With the loss of surface heating, however, we should lose some of the instability. Anticipate a weakening trend to the thunderstorms approaching the west end of our CWA. Freezing level tonight is near 13,800 feet with a wet bulb zero level at 8,000 feet. The -20C level is near 22,500 feet. Southeast winds at the surface became southwest by 925 mb, then westerly through 800 mb, then primarily southwest through 50 mb with a brief exception between 340 and 270 mb. Peak wind through 50 mb was a 50 knot wind near 47,000 feet. 35 PREV DISCUSSION... /issued 351 PM CST Fri Nov 18 2016/ SHORT TERM... The upper level ridge that was over the area is quickly progressing east today while a trough is moving across the central/high plains. A strong cold front on the leading edge of the trough is currently moving across north Louisiana Friday and should entering the northwestern CWA between sunset and 03z. Shouldn`t take but about 6 hours for the front to move completely across the forecast area. In terms of rain, radar trends over the last few hours shows some filling in of the line as it moved from TX into LA. The HRRR and even medium range models shows this holding together through the northwestern third of the CWA before breaking up and diminishing in coverage from there southeastward. The latest forecast pops were adjusted to attempt to show this with near 50% chance of rain NW of BTR down to 20-30% along the LA coast. LONG TERM... Post frontal air mass will be the coldest temperatures the region has seen since last spring. Highs over the weekend will barely reach into the lower 60s. Elevated winds behind the front will keep temps from falling too much Saturday night, but still likely to see mid to upper 30s in the northern half of the CWA (40-50 south). Monday morning will be the coldest and dropped forecast lows a couple more degrees from the previous forecast. MAV/MET guidance looks to better capture the clear/calm conditions compared to blended models, so thinking lows in the lower to mid 30s along and north of I-12 in LA and I-10 in MS with a handful of locations dropping to freezing or even just below 30. Widespread frost is expected in those areas. Temperatures will then begin to moderate Monday and Tuesday as a weak upper ridge slides across the northern Gulf Coast. Following on its heels, a more southerly oriented trough will pass across the Rockies Tuesday and shoot off to the northeast Wednesday. This will bring another front to the forecast area but with the upper trough moving away from the area then, the front will likely washout as it gets here. Some rain expected but should be fairly weak convection an decreasing in coverage as the boundary moves in. Meffer AVIATION... mostly VFR conditions are expected through Saturday. The exception will be as a convective band of isolated to scattered SHRA and a few TSRA, associated with a strong cold front, move through southeast LA and south MS from northwest to southeast between 03z and 11z Saturday. Isolated SHRA could also develop late this afternoon and early this evening in advance of the main band. Some lower MVFR category conditions due to CIGS and/or VSBY may impact the terminals, so have indicated VCSH or PROB30 -SHRA. Stronger and gusty northwest to north winds will follow cold frontal passage late tonight into Saturday. 22/TD MARINE... Strong cold front is expected to move through Lakes Maurepas and Pontchartrain between 2 and 3 am tonight and the sounds and coastal waters between 3 am and 9 am Saturday. Small Craft Advisory (SCA) conditions with occasional gusts to near gale force are expected to develop fairly quickly behind the front, so the timing of the start of SCA headline has been set accordingly. SCA conditions are then to continue through at least mid morning on Sunday as colder air and high pressure build into the region. The exception is Lakes Pontchartrain and Maurepas where there should be a drop below SCA Saturday afternoon before winds and waves pick back up in the evening and overnight hours Saturday night. High pressure will build in closer to the coast Sunday afternoon, then gradually move east Monday into Tuesday. Winds and seas are expected to subside from late Sunday morning through Monday. Another weaker cold front is expected to move through the marine area Wednesday night shifting winds from southerly back to northerly again, but staying below SCA criteria. 22/TD DECISION SUPPORT... DSS code: Blue Deployed: None. Activation: None. Activities: Drought Monitoring, Enhanced Fire Danger Risk Saturday, and Small Craft Advisory late tonight through Sunday morning. Decision Support Services (DSS) Code Legend Green = No weather impacts that require action. Blue = Long-fused watch, warning, or advisory in effect or high visibility event. Yellow = Heightened impacts with short-fused watch, warning or advisory issuances; radar support. Orange = High Impacts; Slight to Moderate risk severe; nearby tropical events; HazMat or other large episodes. Red = Full engagement for Moderate risk of severe and/or direct tropical threats; Events of National Significance. && .PRELIMINARY POINT TEMPS/POPS... MCB 47 61 34 63 / 50 0 0 0 BTR 50 62 35 62 / 50 0 0 0 ASD 53 63 37 63 / 20 0 0 0 MSY 56 62 45 62 / 30 0 0 0 GPT 56 65 38 62 / 20 10 0 0 PQL 55 65 36 63 / 20 10 0 0 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...Small Craft Advisory from 6 AM Saturday to noon CST Sunday for GMZ532-534-536-538-550-552-555-557-570-572-575-577. Small Craft Advisory from 3 AM to noon CST Saturday for GMZ530. MS...None. GM...Small Craft Advisory from 6 AM Saturday to noon CST Sunday for GMZ534-536-538-550-552-555-557-570-572-575-577. && $$
Area Forecast Discussion
National Weather Service San Francisco Bay Area
337 PM PST Fri Nov 18 2016 ...Widespread Rain Expected Over the Weekend... .SYNOPSIS...Widespread rain is forecast to spread from north to south across the district beginning tonight through Saturday. Periods of rain will continue on Sunday. Dry weather will likely return by Monday, but rain is possible once again by the middle of next week. && .DISCUSSION...As of 3:00 PM PST Friday...In general everything appears to be coming together for a substantial change in the weather this weekend as a Pacific Storm System continues to approach the West Coast. Currently the center of circulation is around 750 miles west of Seattle while a longwave trough stretches southwestward. At the same time a substantial cold front ahead and south of the low will advance to the coast later today with associated rainfall forecast to move into the North Bay starting this evening. KBHX radar nicely shows the leading edge of precipitation which the HRRR appears to have initialized close to reality. Rainfall will move to the NW Sonoma coast close to 8 PM and then down to San Francisco around 4 AM. Rain will continue to progress to the south and be in the Monterey Bay Region just after sunrise. Rain rates will pick up during the day as the cold front moves to our CWA which could lead to moderate or even briefly heavy rainfall at times. Behind the front rain is still expected to continue through Sunday, although coverage and amounts will be considerably less. Totals are only slightly different from yesterday and the overnight shift with the greatest numbers still forecast for the North Bay. Still looking at 2-4" for the North Bay Mountains with 1-2" for the rest of the North Bay and the Santa Cruz Mountains. Around SF Bay generally 2/3" to 1 1/3" can be expected with lesser amounts to the south. Winds will be the other story with gusty southerly winds forecast just ahead of the front. Based off of latest guidance which now has speeds near 50 KT just above the surface both along the coast and some of the higher elevation spots, a wind advisory is now in effect (please see SFONPWMTR for details). Even locations around San Francisco Bay will see gusty conditions -- possibly to around 40 MPH on Saturday. After a dry Monday and Tuesday the models indicate that two more systems will move through the remainder of next week. Timing has gotten a bit better with most of the solutions now brining rain through on Wednesday and Friday. Neither of these systems appear strong. Both the 6 to 10 and 8 to 14 day outlooks continue to favor wetter than normal conditions. && .AVIATION...As of 3:35 PM PST Friday...For 00z tafs. Approaching storm system will bring deteriorating ceilings, rain, and increasing southerly winds through tonight and into Saturday. Cigs generally VFR this evening then decreasing down to MVFR from north to south tonight and Saturday morning as front approaches. Rain will begin to move into the North Bay as early as 04Z Sat before spreading southward through the remainder of Friday Night and Saturday. In addition, southerly wind gusts will strengthen as the front approaches with local gusts up to 35 mph expected late tonight and through much of Saturday. Vicinity of KSFO...VFR through the evening rush. Then becoming MVFR late tonight into Saturday morning as front approaches. Rain will begin after midnight and continue through much of Saturday. Visibility and cigs will likely decrease briefly during periods of heavier rain, mostly likely on Saturday morning. Southerly winds will gradually increase overnight with gusts up to 30 KT possible late Friday Night and through much of Saturday. Confidence moderate. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VFR expected through Friday night. MVFR cigs likely to develop by late Saturday morning as frontal rain band approaches. Rain will then continue through Saturday afternoon with brief reduced visibility and lower cigs with heavier rain on Saturday afternoon. Southerly winds will increase on Saturday morning and continue gusty through Saturday afternoon. Confidence moderate. && .MARINE...as of 02:21 PM PST Friday...Southerly winds will increase significantly tonight and into tomorrow ahead of an approaching storm system. gale force gusts and periodically moderate to heavy rain are expected as the front moves into the area. gusts will generally range from 35 to 45 kt with localized bursts to 50 kt possible. winds will veer northerly behind the front by sunday with a building nw swell. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...Wind Advisory...Coastal sections as well as the East Bay Hills and Santa Cruz Mountains. SCA...Pigeon Pt to Pt Pinos 0-10 nm SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm GLW...Pigeon Pt to Pt Pinos 0-10 nm from 4 AM GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm from 4 AM GLW...Pt Arena to Pigeon Pt 10-60 nm SCA...Mry Bay until 1 AM SCA...Pt Reyes to Pigeon Pt 0-10 nm until 1 AM SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 1 AM GLW...Pt Reyes to Pigeon Pt 0-10 nm from 1 AM GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 1 AM SCA...Pt Arena to Pt Reyes 0-10 nm until 7 PM GLW...Pt Arena to Pt Reyes 0-10 nm from 7 PM SCA...SF Bay from 1 AM && $$ PUBLIC FORECAST: Bell AVIATION: Dykema MARINE: DRP Visit us at www.weather.gov/sanfrancisco Follow us on Facebook and twitter at: www.Facebook.com/nwsbayarea www.twitter.com/nwsbayarea
Area Forecast Discussion
National Weather Service Mount Holly NJ
923 PM EST Fri Nov 18 2016 .SYNOPSIS... High pressure will remain across the area tonight before moving offshore saturday morning. A strong cold front will cross the area Saturday evening as low pressure strengthens over eastern Canada. The low will influence our weather into early next week. High pressure will build across the area Tuesday and Wednesday. Another disturbance will approach the region later next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Surface high pressure/upper ridge will remain positioned along the eastern U.S. seaboard through tonight. During this time, the forecast area will remain situated between a downstream low located about 500 miles east of the mid-Atlantic coast and an upstream low that will be moving through the Upper Midwest. Under clear skies, temperatures will drop quickly once the the sun sets and the boundary layer decouples. Undercut stat guidance, especially in the usual locales that radiate effectively (e.g., rural areas, sheltered valleys, Pine Barrens), by several degrees. Conversely, raised temperatures for tonight from stat guidance along the ridges of northeastern PA and northwestern NJ. The presence of a shallow thermal inversion near the surface will result in overnight temperatures at these higher elevations (above 1000 ft ASL) that area 10F or more higher than the nearby valleys. Temperatures in these locations have been quite variable this evening and may trend a few degrees up or down overnight. Bufkit analysis of the RAP and NAM both show the potential for for the surface to become saturated toward sunrise for most of the region. With light winds, some patchy fog is likely to form. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... Low pressure is forecast to track northeastward toward the St. Lawrence Valley on Saturday. Meanwhile, a strong cold front with this system will cross the Appalachians in the morning and then move in from the west during the mid to late afternoon. Saturday looks to be the last mild day in the foreseeable future with the region situated in the warm sector ahead of the cold front. Although temperatures will drop quickly in wake of the fropa, the front looks to arrive late enough in the day to allow temperatures across the forecast area to climb well into the 60s during the afternoon. Temperatures in the low 70s are reachable, especially in the coastal plain, where thicker cloud cover has the best chance to hold off until after peak heating. A band of showers are likely to accompany the front late in the day. Despite a limited moisture feed, strong low-level convergence along the front and DPVA with an upper shortwave trough will provide enough lift for precip. Model soundings show meager instability in the warm sector, so thunderstorms were not put in the forecast. S-SE winds ahead of the front will increase during the day and could gust to around 20 mph during the afternoon. Winds sharply veer out of the NW behind the front and quickly become breezy late in the day (initially across E PA and E MD). && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... The big changes that have been advertised for the past few days will arrive at the beginning of the long term. A sharp cold front will be in the process of crossing the area Wednesday evening. Strong gusty winds and colder temperatures will push across the area. Temperatures will plummet through the 50s and 40s overnight and eventually bottom out in the 30s across the region. The gusty winds will create a unpleasant wind chill by Sunday morning in the 20s area-wide. The best chc for showers with the front will be across the srn Poconos and nrn NJ with some likely pops there, elsewhere pops will only be in the chc range with more limited moisture and dynamics in those areas. Winds will shift to W or NW behind the front and gust to 30-40 mph for the overnight period and into Sunday morning. A wind advisory may be needed if speeds a few more mph are indicated in future fcsts. The rain showers across the north may change over to snow showers by Sunday across the srn Poconos and Sussex county NJ with the colder air arriving. The gusty winds and cold conditions will continue Sunday and into Monday across the area. Showers will be confined to the nrn areas where rain and snow showers will occur. It`s possible that some small accumulations and some lower visibilities with snow showers may occur up north. We will keep the mention of that in the HWO for now. Highs both Sunday and Monday will be in the 40s for most areas and 30s across the north. These temps are some 20 to 25 less than what will occur on Saturday. High pressure will build across the area later Monday and remain in control of the weather into the middle of next week. We will have fair weather in this period with temperatures continuing to run several degrees below normal. Winds will remain gusty Monday, but should be quieter Tuesday. Another disturbance will approach towards the end of next week. Presently the latest 12z ECMWF is slower with the system compared to the 12Z GFS. We will continue with slight chc pops for Wed night and Chc pops for Thu into Friday. Temperatures will continue seasonably cool this period, the precip should be rain over most areas, but could be some nighttime snow showers across the climatologically cooler areas (Srn Poconos and nrn NJ). && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Patchy ground fog may develop toward sunrise at most TAF sites. Have only included MVFR visibilities in the TAFs of KRDG, KABE and KMIV where the risk is the highest in these fog prone terminals. SE winds increase to 5-10 kt during the late morning and afternoon. A few gusts of 15-20 kt are possible during the afternoon. Winds sharply veer out of the NW behind the front and quickly become breezy from west to east between 21Z Saturday and 00Z Sunday. Showers become more likely by 22z for KRDG and after 00Z E of KPHL. OUTLOOK... Sat evening...Restrictions in showers possible early. Gusty W/NW winds. Sunday thru Monday...VFR and gusty winds. Few showers far N/W. Monday night thru Wed...VFR expected. && .MARINE... Light and variable winds through tonight. Seas will be below 3 ft. Southeasterly winds will strengthen on Saturday ahead of a cold front. Poor lapse-rates should inhibit stronger winds aloft from mixing down to the surface except maybe right along the coast. Gusts to near 25 kt may develop in these near-shore waters later in the afternoon but did not issue a short-duration SCA with a Gale Warning going into effect Saturday evening. OUTLOOK... Sat night thru Sun night...Gale warning. Sct showers Sat evening. Monday thru Tue evening...SCA conditions with fair weather. && .TIDES/COASTAL FLOODING... Strong northwesterly flow developing Sat night/Sunday with a chance of blowout tides with the Sunday Evening high tide, primarily on the bay where funneling effects will increase the risk. However, the wind direction isn`t directly down-bay, so there remains uncertainty of exactly how low the water levels will be. We will continue to monitor as we get closer. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Gale Warning from 6 PM Saturday to 6 AM EST Monday for ANZ430- 431-450>455. && $$ Synopsis...O`Hara Near Term...Gaines/Klein Short Term...Johnson Long Term...O`Hara Aviation...Gaines/Klein/O`Hara Marine...Klein/O`Hara Tides/Coastal Flooding...
Area Forecast Discussion
National Weather Service Denver/Boulder CO
207 AM MST Sat Nov 19 2016 .SHORT TERM...(Today and tonight) Issued at 207 AM MST Sat Nov 19 2016 The mid and upper-level ridge axis will shift over the state of Colorado throughout the day and will keep us dry today and tonight. At the surface, high pressure over the Central Plains states will continue to shift east. Combined with weak lee troughing caused by westerly flow over the mountains, southerly flow across the eastern quarter of Colorado will prevail. One pretty significant change to today`s forecast is the expected high temperatures. With lingering snow cover across the NE quadrant of Colorado, a very strong low-level temperature inversion has developed. Downslope flow is not expected to penetrate this inversion, instead we expect the warming flow to be confined to the foothills and higher terrain. There does not appear to be any well-defined mechanism to mix out the low-level inversion as surface winds will be light and out of the ESE in between the Cheyenne Ridge and Palmer Divide and points to the east across much of Weld County. All the high res models keep the inversion in place, with the NAM the coldest of all guidance. Am inclined to follow the HRRR and RAP solutions with upper 30s for highs across the snow cover areas and where the inversion is strongest, roughly just west of I-25...to north of the C-470 beltway and I-70...and east to the Kansas Border. The foothills and Palmer Divide should warm into the low 50s. Tonight we expect wave clouds to develop which would keep min temperatures in the low 30s across the plains adjacent to the foothills and across the urban corridor. Across the plains of NE CO after an expected cold day with little snow melt, lows could dip into the upper teens across the favored locations of Weld, Morgan, and Logan Counties. Expect low to mid 20s elsewhere across the Eastern plains. The mountains should see lows in the 20s. .LONG TERM...(Sunday through Friday) Issued at 207 AM MST Sat Nov 19 2016 The upper ridge will begin flattening and moving east Sunday as a system digs into the western Great Basin overnight. Forecast cross sections and soundings show wave clouds likely over the area starting in the morning, which should limit how cold we start the day out. 700 mb temperatures won`t be changing much over today, yet expecting some warming with the inversion not being so strong, but may be impacted by the wave clouds. The system should push moisture into southwestern Colorado Sunday night, but should stay out of the northern and central mountains. The NAM is the slowest with the incoming system, though takes a piece of jet energy and shows precipitation over the northern mountains already after midnight. For now will ignore the outlier. The upper trough will push into the state Monday with snow beginning over the northern and central mountains. Could see some banding of snow with this as the southwest-northeast oriented jet moves east across the area. Snow levels look to be around 9-9.5kft during the day. A surface low will deepen over the central to southeastern plains, which will likely start pulling in cooler air from the north during the afternoon. With some weak to moderate upward QG motion over the area, could see some rain and possible snow mixed in over the plains. The surface low heads out southeast and into Kansas overnight which may downslope some of the southern metro and foothills areas, but the QG may be able to overcome this. Snow levels are progged anywhere between 4000 ft on the CMC to 7000 feet on the EC, with the NAM and GFS closer to 6000 ft Monday night. Tough to decide at this point with the model variability. Modeled snow accumulation shows mainly less than an inch over most of the plains except 2-4 inches over the areas closer to the foothills and Palmer Divide. Not confident in amounts however due to potential downsloping. Over the mountains however, more impactful amounts are possible, with several inches at higher elevations. Possible banding could produce more in localized areas. May need a highlight for Monday afternoon through Tuesday morning, will continue to assess. Strong north to northwesterly winds are expected after midnight and into Tuesday afternoon before they decrease quickly. As the upper trough pushes into Kansas, moisture on the backside will keep snow going over the mountains most of the day while areas of rain and snow and much cooler temperatures over the plains should push east out of the area by the afternoon. Skies should clear overnight for cold minimum temperatures. Upper ridging re- establishes itself for Wednesday, then a couple weak shortwaves pass through the almost zonal flow aloft for Thursday and Friday with little impact, both in moisture and temperature, though the northern mountains may see a few snow showers. Saturday will have the best shot of seeing any moisture as a deeper trough is expected to push in from the west, but this should stay in the mountains. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 207 AM MST Sat Nov 19 2016 VFR conditions expected through Saturday night and into Sunday morning. Winds should be 10 kts or less all terminals. At KDEN expect the wind direction out of the ESE this afternoon then going to southerly after 02Z. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Schlatter LONG TERM...Kriederman AVIATION...Schlatter
Area Forecast Discussion
National Weather Service Lincoln IL
315 AM CST Sat Nov 19 2016 .SHORT TERM...(Today and tonight) ISSUED AT 315 AM CST Sat Nov 19 2016 The pressure gradient between a 996mb low over Lake Superior and a 1037mb high across western Kansas will remain sufficiently tight to produce wind gusts of 35 to 40mph through the morning. Even though sustained winds and gusts will likely remain just shy of advisory criteria, decided to extend the Wind Advisory through noon along/north of a Rushville to Bloomington line. As the low slowly shifts further northeastward and the gradient begins to relax, wind gusts will drop to less than 30mph this afternoon. Skies will initially be overcast early this morning: however, low clouds will steadily advect/dissipate from west to east across the region as the day progresses. Latest HRRR suggests skies will become mostly sunny across all but the far E/NE KILX CWA from Bloomington to Paris by midday...then everywhere by late afternoon. Thanks to strong CAA, high temperatures will be considerably colder than yesterday...with readings ranging from the upper 30s north of I-74 to the middle 40s far southwest around Jacksonville. Winds will continue to decrease tonight, although with the Plains high remaining west of the Mississippi River through 12z Sun, think 8-12mph winds will continue throughout the night. This will help keep the atmosphere mixed and limit maximum radiational cooling, resulting in lows remaining in the lower to middle 20s. && .LONG TERM...(Sunday through Friday) ISSUED AT 315 AM CST Sat Nov 19 2016 Cool/dry weather will prevail through Monday, before the next storm system approaches Illinois by mid-week. 00z Nov 19 models have continued the recent trend of slowing the system and tracking it slightly further north...with both the GFS and ECMWF now developing a surface low in the lee of the Rockies across eastern Colorado Monday night, then tracking it E/NE into northeast Iowa by 12z Wed. This particular track will put central Illinois in the warm sector of the storm, with profiles supporting all rain. Given slower arrival, have removed PoPs entirely for Tuesday morning with rain developing across the area mainly Tuesday afternoon and evening. GFS MUCAPE values remain negligible at this point, but given track of surface low to the W/NW, isolated thunder may be possible. Once the low lifts into the Great Lakes, wrap-around moisture will bring a continued chance for rain showers into Wednesday before conditions dry out for the end of the forecast period. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1124 PM CST Fri Nov 18 2016 West winds trying to diminish a bit late this evening, but the pressure gradient remains tight enough that frequent gusts of 25-30 knots are likely into much of Saturday, before finally diminishing late afternoon. Large stratocumulus area has been on the low end of the VFR range, but the western fringes are showing some brief dips to near or below 3,000 feet. Have included TEMPO periods at all sites late in the night as the back edge of the cloud shield arrives. General clearing trend will take place mid to late morning at all TAF sites. && .ILX WATCHES/WARNINGS/ADVISORIES... Wind Advisory until noon CST today for ILZ027>031-036>038-041. && $$ SHORT TERM...Barnes LONG TERM...Barnes AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Midland/Odessa TX
1140 PM CST Fri Nov 18 2016 .UPDATE... Issued update to include Gaines County in the Hard Freeze Warning. && .DISCUSSION... Temperatures are already in the mid 30s in Gaines County and are expected to decrease throughout the night. The RAP13 model is showing temperatures in the mid 20s by 12z and the HRRR is showing temperatures of lower to mid 20s across western sections of Gaines County. With temperatures likely to reach 28 degrees or below for a good portion of Gaines County, the Freeze Warning has been upgraded to a Hard Freeze Warning. && PREV DISCUSSION... /issued 229 PM CST Fri Nov 18 2016/ DISCUSSION... A strong cold front moved through the area this morning and it will bring the first freeze of the season to many areas north of I-10 tonight. Brisk north winds will subside after sunset and combined with clear skies will provide optimal conditions for radiational cooling. A hard freeze is possible across much of southeast New Mexico and the Davis Mountains which would require a little extra precaution, mainly in the protection of exposed outdoor pipes. Cold air behind the front will dam against the Guadalupe Mountains causing strong northeast winds at Guadalupe Pass tonight and tomorrow morning. Wind speeds may briefly reach high wind warning criteria but the event will be marginal and very localized so opted against issuing a warning at this time. The upper air pattern is progressive so the cold air will not last long with warmer temperatures expected Sunday and Monday before the next upper trough arrives Tuesday. This trough will move across the Rockies and into the Central Plains in a trajectory that is unfavorable for precipitation. Winds ahead of the trough will push most moisture east of our area before the upper lift arrives making rain doubtful, so have only gone with slight chance PoPs for Tue. The trough will bring our next front on Wednesday which will not be as strong as the one seen today with lows holding above freezing and highs near normal for this time of year. Hennig && .PRELIMINARY POINT TEMPS/POPS... Big Spring 30 56 37 67 / 0 0 0 0 Carlsbad 27 56 29 69 / 0 0 0 0 Dryden 39 60 37 66 / 0 0 0 0 Fort Stockton 33 59 40 74 / 0 0 0 0 Guadalupe Pass 30 52 37 65 / 0 0 0 0 Hobbs 27 54 31 67 / 0 0 0 0 Marfa 26 56 26 67 / 0 0 0 0 Midland Intl Airport 30 56 36 67 / 0 0 0 0 Odessa 31 56 36 67 / 0 0 0 0 Wink 31 58 32 69 / 0 0 0 0 && .MAF WATCHES/WARNINGS/ADVISORIES... NM...Freeze Warning until 8 AM MST Saturday for Guadalupe Mountains of Eddy County-Southern Lea County. Hard Freeze Warning until 8 AM MST Saturday for Central Lea County-Eddy County Plains-Northern Lea County. TX...Freeze Warning until 9 AM CST /8 AM MST/ Saturday for Andrews- Borden-Crane-Dawson-Ector-Glasscock-Guadalupe Mountains- Howard-Loving-Martin-Midland-Mitchell-Reagan-Reeves County and Upper Trans Pecos-Scurry-Upton-Van Horn and Highway 54 Corridor-Ward-Winkler. Hard Freeze Warning until 9 AM CST Saturday for Davis/Apache Mountains Area-Gaines-Marfa Plateau. && $$ 99/99
Please see the previous forecast discussion below for more details
on this winter storm and the active weather pattern through the
week. && .AVIATION...19/06Z TAF cycle...Rain continues to overspread the area from the southwest as a front approaches this evening. Flight conditions will be a mix of VFR and MVFR through the evening, then lowering to IFR at times as heavier precipitation associated with the front itself moves through late tonight and early tomorrow. The most likely locations for the lower conditions will be along the coast and in the mountains as well as near Mt. Shasta where snow is expected to develop overnight. Low level wind shear will also be an issue as the front approaches, especially along the coast. Strong winds have already developed in the Shasta Valley and east side and will continue until through Saturday. Therefore, turbulence will be increasing over California, near and to the north of the Siskiyous and east of the Cascades. -Wright/SK Note: The ceilometer at FAA site KOTH is out of service, so there will be no ceiling observations available generally between the hours of 04Z and 14Z. && .MARINE...Updated 1030 PM PST Friday 18 November 2016...A strong cold front is moving through the waters this evening. Gales will continue through the evening most areas, then winds will drop below gales later tonight as the front moves onshore, but seas will remain very steep due to a mix of wind wave and fresh swell. Gales will redevelop tomorrow afternoon and evening as another low pressure system moves inside 130W and pushes a front toward the coast. We will see a break in winds and seas Monday, but another front brings south gales and very steep seas Tuesday. The stormy pattern continues for the foreseeable future with cold fronts roughly every other day all the way into next weekend. -Wright && .PREV DISCUSSION... /Issued 320 PM PST Fri Nov 18 2016/ SHORT TERM...A front is located about 150 miles off the Southern Oregon coast. This front will gradually move inland across the area tonight and Saturday morning. Ahead of and with the frontal passage expect strong gusty winds over portions of the area. Also southwest portions of the area, mainly Curry and Siskiyou counties, will see moderate to heavy precipitation. South winds have increased this afternoon in the Shasta Valley, over the mountains and for areas east of the Cascades. South winds have also begun to increase in the southern Rogue Valley. As a jet aloft moves into the area this evening and tonight and the surface pressure gradient increases, expect winds gusts up to 65 mph in the southern Shasta Valley with winds gusting to 45-50 mph in the Rogue Valley. Winds will increase during the evening and remain strong overnight and into Saturday morning. Winds are expected to lower behind the front late Saturday morning and Saturday afternoon but remain breezy. East of the Cascades strong gusty winds are likely over the mountains, including the Warners, Hart Mountains and Summer Rim area, and in the Paisley to Silver Lake area with winds peaking late this evening through Saturday morning then continued gusty winds into Saturday night and Sunday morning as another weaker jet max move into the area. For details on the winds see the NPWMFR. As the front moves inland tonight, moderate to heavy precipitation is forecast into Curry and Siskiyou counties. Heavy precipitation amounts around the Mount Shasta in south central Siskiyou county combined with lowering snow levels will bring winter storm conditions. Due to upslope effects from very moist air and a mid level jet, snow levels are expected to lower to 4000 feet in the Mount Shasta area during the evening then down to near 3500 feet elevation late tonight and early Saturday morning. Snow accumulation of 5 to 10 inches is expected above 3500 feet elevation for southern Siskiyou County with higher amounts above 6000 feet elevation. Of note, a heavy wet snow is expected for the 3500 to 4000 ft elevations and snow accumulations may vary significantly with some areas seeing more and other less. This may be of most concern near Mount Shasta City where snow accumulations around 4 to 7 inches are possible. For mountain passes such as near Snowmans Summit on highway 89, expect greater snow accumulations tonight through Saturday with accumulations around 6 to 12 inches. For details on the winter storm warning conditions see the WSWMFR for details. West of the Cascades in Southern Oregon expect snow levels to remain fairly high around 5000 to 5500 feet with a mix of light to moderate precipitation. Over the Siskiyous and from the Cascades east in Southern Oregon as well as into Modoc County expect snow levels to lower to around 4000 to 4500 feet tonight and Saturday morning with light precipitation. This will result some light snow accumulation possible especially over the mountains. Behind the front, an upper level trough moves into the region Saturday afternoon through Sunday night. Shortwaves embedded in this trough will move into the region late Saturday through Sunday bringing additional precipitation with snow levels varying from around 4500 to 5500 feet. During this period expect the focus for precipitation to be from the coast into Siskiyou County for this period but all areas will see period of light or moderate precipitation. Lastly, behind the frontal passage and with the upper trough expect instability over the coastal waters with a slight chance for thunderstorms tonight through Saturday. Early next week, expect a break in the pattern with a shortwave upper level ridge moving into the region late Monday with diminishing shower chances over the area. This break in the active pattern is expected to be brief though. LONG TERM...Tuesday through Friday Night...Models are in good agreement regarding the wet and active pattern during the long term. While there are some variations in the strength and timing of the individual features, there is much less uncertainty regarding the overall pattern. It would be very safe to say that the area will see a continuation of the wet weather through the remainder of next week. Very deep troughing over Siberia will throw off several waves during the week, each passing across the north Pacific in quick succession. The first of the three systems expected during the long term will arrive on Tuesday, followed by another Wednesday night into Thanksgiving, and yet another Friday night. Each system will have a brief break in between, but in some cases, this will be barely noticeable. There are no particularly telling features appearing in any of the model suites that would single out any of these system as particularly strong or exceptional, but this could easily change in coming model runs. For now, have trended the wind and rain forecasts during each system towards values typical with our normal wet season storms, with heavy rain and gusty winds at the coast, and strong winds across the East Side and in the Shasta Valley. One item of note will be snow levels, which are expected to hover between 3000 and 4000 feet throughout the week. This would mean that each system will likely produce snow at most of our area passes. This is particularly concerning when considering the upcoming busy holiday travel. Those planning on traversing the area next week would do well to stay up to date with the latest forecasts and make the necessary plans to account for the likelihood of wintry weather. -BPN && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Wind Advisory until 10 AM PST Sunday for ORZ026-030-031. Wind Advisory until 1 PM PST Saturday for ORZ029. CA...Wind Advisory until 10 AM PST Sunday for CAZ081-085. Winter Storm Warning until 10 AM PST Saturday ABOVE 3500 FEET for for CAZ080>083. High Wind Warning until noon PST Saturday for CAZ081. Pacific Coastal Waters...Small Craft Advisory until 4 AM PST Sunday for PZZ356. Gale Warning until 4 AM PST Sunday for PZZ350-356- 370-376. $$ NSK/BPN/TRW
Area Forecast Discussion
National Weather Service Lincoln IL
511 AM CST Sat Nov 19 2016 .SHORT TERM...(Today and tonight) ISSUED AT 315 AM CST Sat Nov 19 2016 The pressure gradient between a 996mb low over Lake Superior and a 1037mb high across western Kansas will remain sufficiently tight to produce wind gusts of 35 to 40mph through the morning. Even though sustained winds and gusts will likely remain just shy of advisory criteria, decided to extend the Wind Advisory through noon along/north of a Rushville to Bloomington line. As the low slowly shifts further northeastward and the gradient begins to relax, wind gusts will drop to less than 30mph this afternoon. Skies will initially be overcast early this morning: however, low clouds will steadily advect/dissipate from west to east across the region as the day progresses. Latest HRRR suggests skies will become mostly sunny across all but the far E/NE KILX CWA from Bloomington to Paris by midday...then everywhere by late afternoon. Thanks to strong CAA, high temperatures will be considerably colder than yesterday...with readings ranging from the upper 30s north of I-74 to the middle 40s far southwest around Jacksonville. Winds will continue to decrease tonight, although with the Plains high remaining west of the Mississippi River through 12z Sun, think 8-12mph winds will continue throughout the night. This will help keep the atmosphere mixed and limit maximum radiational cooling, resulting in lows remaining in the lower to middle 20s. .LONG TERM...(Sunday through Friday) ISSUED AT 315 AM CST Sat Nov 19 2016 Cool/dry weather will prevail through Monday, before the next storm system approaches Illinois by mid-week. 00z Nov 19 models have continued the recent trend of slowing the system and tracking it slightly further north...with both the GFS and ECMWF now developing a surface low in the lee of the Rockies across eastern Colorado Monday night, then tracking it E/NE into northeast Iowa by 12z Wed. This particular track will put central Illinois in the warm sector of the storm, with profiles supporting all rain. Given slower arrival, have removed PoPs entirely for Tuesday morning with rain developing across the area mainly Tuesday afternoon and evening. GFS MUCAPE values remain negligible at this point, but given track of surface low to the W/NW, isolated thunder may be possible. Once the low lifts into the Great Lakes, wrap-around moisture will bring a continued chance for rain showers into Wednesday before conditions dry out for the end of the forecast period. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 502 AM CST Sat Nov 19 2016 Gusty west to northwest winds are expected to slowly diminish this afternoon as the storm system that affected the area yesterday continues to shift well off to our north and east. Low VFR cigs have dominated the area during the early morning hours with the latest satellite data and surface observations indicating a narrow band of MVFR cigs pushing in from the northwest over the past several hours. Forecast soundings have trended slower with the clearing across the TAF sites, especially across the east for this afternoon. Low VFR with occasional cigs dropping to MVFR category, around 2500 feet this morning, will slowly scatter out this afternoon with a mostly clear sky expected tonight as high pressure moves in from the west. Surface winds will be out of the west to northwest and range from 25 to 30 kts, with an occasional gust up to 40 kts this morning, before northwest winds begin to diminish this afternoon to between 15 and 25 kts. Tonight northwest winds will range from 10 to 15 kts. && .ILX WATCHES/WARNINGS/ADVISORIES... Wind Advisory until noon CST today for ILZ027>031-036>038-041. && $$ SHORT TERM...Barnes LONG TERM...Barnes AVIATION...Smith
Area Forecast Discussion
National Weather Service Melbourne FL
927 AM EST Sat Nov 19 2016 .UPDATE... Today...High pressure ridge that has been slow moving along the eastern seaboard was shifting south ahead of an approaching cold front. The axis of the ridge across central Florida will provide a northwest-north wind flow. This will maintain the capped, dry and stable air mass we currently have over the area. The area of stratocumulus across southern sections has been diminishing so it will be a mostly sunny day. With primarily an offshore wind flow and plenty of sunshine, max temps will reach to around 80 across the area. Tonight...The latest guidance is showing a dry cold front reaching northern sections a little after sunset and then shift into south Florida before sunrise Sunday. The HRRR simulated IR satellite image showed very little frontal band cloudiness remaining as it traverses the local area. MOS guidance is showing cooling into the mid/upper 40s working down the peninsula behind the front though there is some disagreement amongst the models of how far south this occurs. Some places should have there coolest temps of the season. && .AVIATION...VFR. && .MARINE... Today...A high pressure ridge axis has settled across the waters, which should keep the flow out of the northwest from about Canaveral northward. South of there the winds will be out of the north. Speeds look 10 knots or less except maybe 10-15 knots offshore. This will result in good conditions for small craft near shore with seas 1-3 feet, but it will be a little more bumpy offshore at 3-4 feet. Tonight...A cold front will surge through the waters during the late evening in the north and a little after midnight in the south. A period of winds around 25 knots is likely right behind the front. Seas will build quickly to 5-7 feet and up to 9 feet in the Gulf Stream. No changes to the current forecast. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory from 9 PM this evening to 7 AM EST Monday for Flagler Beach to Volusia-Brevard County Line 0-20 nm- Flagler Beach to Volusia-Brevard County Line 20-60 nm. Small Craft Advisory from 11 PM this evening to 7 AM EST Monday for Volusia-Brevard County Line to Sebastian Inlet 0-20 nm- Volusia-Brevard County Line to Sebastian Inlet 20-60 nm. Small Craft Advisory from 1 AM Sunday to 7 AM EST Monday for Sebastian Inlet to Jupiter Inlet 0-20 nm-Sebastian Inlet to Jupiter Inlet 20-60 nm. && $$ Forecasts...Lascody Impact Wx...Spratt
Area Forecast Discussion
National Weather Service San Francisco Bay Area
406 AM PST Sat Nov 19 2016 ...Widespread Rain and Breezy Conditions Today... .SYNOPSIS...Widespread rain is forecast to spread from north to south across the district through the day. Periods of rain will then continue from tonight through Sunday Evening. Dry weather will likely return by Monday, but rain is possible once again by the middle of next week. && .DISCUSSION...As of 3:20 AM PST Saturday...As forecast, rain is currently moving across the North Bay at this hour with amounts since last evening ranging from just a few tips to all of the way over an inch near Venado. KMUX radar has nicely picked up the rain as it approached and eventually moved into our CWA with a few echoes exceeding 45 DBZ. The HRRR (both operational and experimental) initialized well starting yesterday afternoon and both locked on solutions that area varying only small amounts run- to-run. Therefore, confidence is higher than normal during a storm with timing and the overall forecast in the short term. The band of rain will work its way south to around SF starting around 4 AM, to Santa Cruz 8-9 AM and then finally to the remainder of the Monterey Bay region up to Santa Clara Valley early in the afternoon. The rain will works its way down to the southern portion of our CWA during the afternoon or early evening hours. At the same time, a strong surface cold front (clearly indicated on satellite this morning) will move into our CWA and eventually sweep across our entire region. Associated with this feature will be cooler, more unstable air, plus higher wind speeds (925 MB speeds likely to exceed 50 KT) associated with it. As the front nears, winds will ramp up at many spots with southerly winds expected to gust over 35 mph in many locations. A few higher elevation and coastal spots will likely see gusts to around 50 mph. The wind advisory will be continued and unchanged with the morning package. As cooler and more unstable air moves in behind the front, showers will be triggered across our region along with a slight chance for thunderstorms. MUCAPE value are forecast to possibly exceed 700 J/KG with zero CIN on Sunday suggesting that small hail will be a concern as well. Also appears that the rain will be focused more to the south for Sunday. If any moderate convective cells happen to go over the Sobranes burn scar, it will be a cause for concern. Rain will mostly come to an end the second half of Monday with rainfall totals still expected to be 1-3" for higher elevation locations and generally .5" to 1.5" for urban spots. Depending on how fast clearing occurs Monday night, temperatures Tuesday morning could be on the chilly side. Three additional systems are lined up beyond Monday (favoring Wednesday, late Thursday into Friday, and late Saturday into Sunday). All three appear fairly weak, although the three together could provide a nice boost in our rainfall totals. Thanksgiving right now appears it will start dry with highs mostly in the 60s. Longer range guidance through December 2nd favors wetter than normal conditions. ECMWF ensemble mean indicates around 2/3" in San Francisco for that period. && .AVIATION...As of 03:52 AM PST Saturday...For 12z TAFs. Currently seeing some showers across the North Bay along with increasing southerly winds. Will begin to see cigs lower over the next few hours as rain moves further south. Expect showers and gusty winds to continue throughout the day. Vicinity of KSFO...VFR cigs will gradually lower to MVFR early this morning as the front approaches. Rain will begin early this morning and continue through much of today. Visibility and cigs will likely decrease briefly during periods of heavier rain. Southerly winds will gradually increase with gusts up to 25 KT possible. Confidence moderate. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VFR cigs will gradually lower to MVFR by late this morning as the front approaches. Rain will begin early this afternoon continuing throughout the day with brief reduced visibility and lower cigs with heavier rain. Southerly winds will increase this morning and continue to be gusty through this afternoon. Confidence moderate. && .MARINE...as of 03:51 AM PST Saturday...Strong southerly winds will impact the waters today as a storm system approaches. gale force gusts and periods of moderate to heavy rain are expected as the front moves through. gusts will range from 35 to 45 kt with localized bursts to 50kt possible. winds will become northerly behind the front by sunday night with a building nw swell. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tday...Wind Advisory...Most of the San Francisco and Monterey Bay Region GLW...Pt Reyes to Pigeon Pt 0-10 nm until 3 PM GLW...Pigeon Pt to Pt Pinos 0-10 nm until 3 PM GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 PM GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 PM SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pt Arena to Pt Reyes 0-10 nm until 12 PM SCA...Rough Bar Advisory for SF Bar until 3 PM SCA...Mry Bay from 12 PM SCA...SF Bay until 3 PM && $$ PUBLIC FORECAST: Bell AVIATION: Anna MARINE: Anna Visit us at www.weather.gov/sanfrancisco Follow us on Facebook and twitter at: www.Facebook.com/nwsbayarea www.twitter.com/nwsbayarea
Area Forecast Discussion
National Weather Service Bismarck ND
223 PM CST Sat Nov 19 2016 .SHORT TERM...(This evening through Sunday) Issued at 223 PM CST Sat Nov 19 2016 The main concern in the short term period will be stratus and fog potential tonight into Sunday. Surface high pressure was in control of the region`s weather this afternoon. The high will gradually shift east tonight with low level south to southeast flow taking hold. The latest short term models suggest some potential for stratus and fog development tonight into Sunday, especially across parts of western North Dakota. The HRRR has been fairly consistent with this from run to run, and have opted to add patchy fog for tonight. The HRRR suggests visibilities could drop to well below 1 mile, so this will be something for later shifts to monitor. The low clouds and fog should diminish on Sunday, though NAM BUFR soundings suggest the clouds could be slow to erode, especially from central North Dakota towards the James River Valley. The clouds could also have some impact on temperatures if they are slow to leave. For now, have gone with highs from the lower 30s east, to the 40s west. Another potential concern for tonight is a weak upper wave moving across southern Canada. Some of the short term models hint at the potential for light precipitation, but for now did not add into the forecast with not enough consensus amongst the models. .LONG TERM...(Sunday night through Saturday) Issued at 223 PM CST Sat Nov 19 2016 The primary concern in the long term period will be the passage of an upper trough early next week. The 12z global suite continues to advertise this system, but there remains some disagreement in the details. Will center the best precipitation chances from Monday night into Tuesday which seems to line up with most guidance. Precipitation type remains a potential concern with thermal profiles suggesting warm enough air aloft for a potential wintry mix to start. There are also some signs wet-bulb effects could also play a role as the precipitation begins. Snow ratios remain low through the event which could help limit snow amounts. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 223 PM CST Sat Nov 19 2016 VFR conditions are forecast for this afternoon. MVFR-IFR stratus and fog is being advertised by most forecast models developing into southwest North Dakota this evening first impacting KDIK, then spreading north to KISN by 06Z, then shifting east impacting KBIS between 10-13Z Sunday morning. KMOT more uncertain, with KJMS remaining VFR through the 18Z period. Low clouds expected to burn off for KDIK mid morning around 15-16Z, but perhaps lingering through 18Z for KISN and perhaps more so for KBIS. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CK LONG TERM...CK AVIATION...NH
Area Forecast Discussion
National Weather Service Denver/Boulder CO
229 PM MST Sat Nov 19 2016 .SHORT TERM...(This evening through Sunday) Issued at 219 PM MST Sat Nov 19 2016 Main issue to contend with tonight into Sunday will be a developing mountain wave in the Front Range Mountains and Foothills. The upper level ridge axis will be over central CO at 00z with a moderate westerly flow aloft. The mdls shift this axis east overnight with a moderate west-southwesterly flow over CO. The RAP and NAM12 mdls both indicate an amplified wave developing after 03z, strongest at 12z Sunday, it then breaks down by 18z. Lee side surface trough over eastern CO 06z to 12z then the feature shifts further south by 18z, shifting the surface pressure gradient In the mountains, winds around 650 mb at 40 kts, which appear to translate downslope in the foothills overnight. It does not appear to be strong enough for highlights but gusts in the 45-60 mph range more likely. Temperatures in and near the foothills will also moderate with the gusty winds in place overnight. On Sunday, better temperature recovery progged for the Urban Corridor and Northeast Plains, but a lingering snowfield should keep it a little cooler north and east of Akron. In the mountains and foothills, stronger winds in the mountains and foothills will decrease as the wave break down by Sunday afternoon. .LONG TERM...(Sunday night through Saturday) Issued at 219 PM MST Sat Nov 19 2016 A southwest flow aloft will prevail over Colorado Sunday night as an upper level trough moves across California. This trough will move into the Desert southwest Monday. Moisture will increase through the day. This combined with orographic lift and a jet overhead, is expected to produce snow showers in the mountains. Snow should become widespread over the mountains Monday night as the trough moves across the Central Rockies. Precipitation will then spread onto the Front Range and eastern plains through the night. Temperatures look to be just warm enough for mainly rain along the Front Range Urban Corridor. The upper level low/trough and a surface low reform over western Kansas late Monday night. Northerly winds on the back side of this system will help pull cooler air into the area. This will likely cause the rain to change to snow over the plains, especially where precipitation is moderate to heavy. Northwest flow behind the exiting trough will usher in colder air. This cold air advection combined with a moist airmass is expected to produce snow showers over the mountains most of Tuesday. By Tuesday evening snow will be light and eventually end. Rain/snow over the plains is expected to end Tuesday afternoon as the trough exits the region. A ridge in the westerly flow aloft will move across Colorado Wednesday. Dry conditions will return to the area. Temperatures will be cool with highs in the 40s. On the heels of this ridge, a trough will race across Wyoming and northern Colorado Wednesday night and early Thursday. Will have low pops in the mountains for this system. For the Front Range and eastern plains, this will likely bring dry and windy conditions. A progressive westerly flow aloft will remain over the Central Rockies Friday and Saturday. Temperatures will be near normal under this pattern. The next wave is progged to affect the mountains Friday night and early Saturday. Will have low pops in the mountains for this system. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 219 PM MST Sat Nov 19 2016 VFR with light and variable winds this evening. weak easterly winds this aftn then southerly winds developing this evening at KDEN and KAPA. Downslope winds are expected near the foothills after 03z, so could see a window of gusty westerly winds at KBJC depending on how well the mountain wave forms. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Cooper LONG TERM...Meier AVIATION...Cooper
Area Forecast Discussion
National Weather Service State College PA
258 PM EST Sat Nov 19 2016 .SYNOPSIS... Strengthening low pressure will track north of Pennsylvania this afternoon. A cold front trailing south from this low will plow east across Central and Eastern Pennsylvania during the mid to late afternoon hours. Temperatures will drop sharply by 20 to 25 degrees within just 2 to 3 hours of the frontal passage, and west to northwest winds will gust between 35 and 45 mph through tonight. The deep, cold upper low will pivot over the region Sunday with unseasonably cold air, snow showers, and occasional wind gusts around 50 mph lasting into Monday. this weather feature will slowly lift out to the northeast of the region early next week. Low pressure will likely track north of Pennsylvania late next week. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... 130 pm update... Cold front shows up nicely on regional 88D mosaic as a fine line in the reflectivity field (likely attributed to dust stirred up/concentrated right along the boundary). The front was nearing a line from KELM to KIPT and KHGR at 1830Z. Frequent wind gusts from the West of 35 to 45 mph will be common through dusk...but will likely stay just under Wind Advisory Criteria, then slacken by 5-10 kts early tonight as the primary area of significant sfc pressure rises slides east of the region, with about 30-40 deg of directional shear between the sfc and 850 mb. Area of precip lags the actual sfc cfropa by about 40NM and will occur initially in the form of a chilly rain, before quickly mixing with or changing to a few hour period of snow with a coating to 2 inches likely by 00Z Sunday across the higher terrain of northern and western PA. The precip shield is forecast by the latest...17Z HRRR to hold together fairly well as it slides across the Central Mtns late this afternoon...and early this evening across the Middle and Lower Susq Valley. Slick travel and a quick freeze-up is likely late today and this evening west of the I-99/Route 220 corridor. Temps that reached the 50s in most areas late this morning...and 60s to Lower 70s in the Susq Valley will likely not be seen accompanying nearly full sunshine until later this winter or early in the Spring. Temp drop in the wake of the cold front was on the order of about 25 deg F in just 2-3 hours. If you plan to travel west on I-80 from Berwick to Dubois this afternoon, hold onto the wheel (considering the 35 to 45 mph headwind) and plan to take a winter coat as you`ll experience a 35 to 40 deg temp drop by the end of your 2-2.5 hour trip. && .SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SUNDAY/... Considering the nose of very deep cold air with -7 to -9C 850 temps spreading across the region (and still warm Lower Glakes with temps of 10-13C), there will be very steep low-mid level lapse rates and an excellent setup for an early season significant Lake Effect and orographic moderate to heavy snow event across the NW Mtns and Laurels. NCAR ensemble indicating a general 3-6 inch snowfall across the Allegheny Plateau by 00Z Monday. However, believe higher amounts are likely across the snowbelt of NW Warren county. Downsloping flow and warmer blyr temps should limit any accumulations to a coating in the ridge/valley region and no accumulation expected across the Susq Valley. Very tight llvl pressure gradient will result in strong, gusty west to northwest winds, causing considerable blowing/drifting snow in open/exposed locations of the NW Mtns and Laurel Highlands. Bufkit soundings suggest the best mixing and strongest wgusts will occur across the southeast part of the state during the daylight hours of Sunday, with gusts in excess of 40kts likely. Have therefore issued a wind advisory for this region 12Z Sunday through 05Z Monday. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Accumulating lake effect snow will persist Sunday night across the Allegheny Plateau. However, the intensity is likely to diminish as inversion heights begin to lower. Northwest flow will persist into Monday with lingering snow showers downstream of Lake Erie, but dry and cold in the S/E. The Strong NW flow ushering in cold air will continue on the backside of the storm system that came through Saturday as long as the storm`s low pressure center is deepening. Low is finally forecast to start filling late Monday up over Maine. A strong ridge of high pressure moves in across PA Tuesday into early Wednesday bringing fair weather and warming temperatures. A warm front will move through Wednesday afternoon as the next storm system moves into the Great Lake Region. GFS and ECMWF differ on how fast the precip and cold or occluded front associated with this storm moves into PA with the GFS beingthe fast one bringing it in early Wednesday night and the euro moretoward Thursday morning. Temperatures have warmed enough that anyprecipitation Wednesdaynight and Thursday will be rain. Both models hen develop a secondary low on the VA Coast whichdeepens as it moves off to the northeast. This will help to bringsome colder air in by Thursday night to northern PA with just aslight chance of mix rain and snow showers there. A clipper systemmoves quickly through Friday night and Saturday with a better chanceacross the north for mix rain and snow showers with snow chances inthe higher elevations. Cold air sweeps in behind this and some lakeenhancement could change over to snow showers by Saturday afternoon. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... Big changes are on the way! The last vestiges of sunny skies and light wind are seen east of the Susq mainstem at mid afternoon. West winds will sharply increase over the eastern PA airfields as a strong cold front pushes across the region between 19-22Z...while winds continue to frequently gust between 32-37 kts across the central and western part of the state through 00Z. This front will bring a big change in weather regime. Initially, gusty rain showers (as winds increase and turn to the west) reach the central terminals 18-20z, and the Susq River Valley 20-23Z. Colder air surging in behind the front will bring a brief period of light to moderate rain, then a quick change to mixed rain and snow (or even all snow for an hour or so across the nrn mtns of PA). Cig and vsby reductions into the low MVFR or IFR range are expected for a few hours in the Central ridge and valley region and Susq Valley late this afternoon and evening...before climbing back to mainly MVFR or VFR SE of a KAOO to KIPT and KAVP line. Over the NW mtns and Laurel Highlands...expect more solid IFR conditions in frequent snow showers/upslope stratus with brief increases to MVFR between the snow showers. Starting later tonight, a period of even stronger and gusty WNW winds will develop - peaking Sun into Sun night with frequent surface gusts of 40-50mph. A period of more intense/widespread lake effect snow showers with IFR cigs/vsby likely at KBFD/KJST by mid evening and continuing right into Mon. Generally lighter snow showers will spread into central mtns (KUNV/KAOO) Sun night into Mon. Outlook... Tonight-Mon...Strong/gusty NW winds. Gusts frequently between 35-45 mph later tonight through Sunday night. Snow showers/IFR reductions likely at KBFD/KJST. Ocnl MVFR cigs with flurries and brief snow showers across the Central Mtn airfields - KAOO, KUNV and KIPT with mainly VFR invof KMDT, KLNS and KTHV. Tues...Morning MVFR cigs possible across the northern and western mtns of PA...otherwise decreasing wind and improving conditions to mainly VFR. Wed...No significant weather expected. Wed night and Thursday...MVFR to IFR conditions as periods of rain spread east across the state. Mixed precipitation possible across the northern and western mountains of PA. && .CTP WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 7 AM Sunday to midnight EST Sunday night for PAZ019-025>028-034>036-041-042-045-046-049>053-056>059- 063>066. Winter Weather Advisory until 7 AM EST Monday for PAZ012-017- 018-024-033. Lake Effect Snow Advisory until 7 AM EST Monday for PAZ005-006- 010-011. Lake Effect Snow Warning until 7 AM EST Monday for PAZ004. && $$ SYNOPSIS...Fitzgerald/Lambert NEAR TERM...Lambert SHORT TERM...Fitzgerald/Lambert LONG TERM...Watson AVIATION...Lambert/RXR
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
240 PM CST Sat Nov 19 2016 .SHORT TERM... 152 PM CST Through Sunday night... Winter is making a brief though abrupt appearance here across the region in wake of the first real storm system of the season. While winter precipitation impacts were low with this one, today is our first day of below normal highs in quite some time with readings holding in the 30s and wind chills in the 20s. The strong low will continue northeast through Quebec tonight and the high pressure ridge across the plains will also edge closer to the area tonight. This will maintain northwest winds across the area though with a gradual decaying trend. Rap lower level moisture progs suggest a quick clearing to the cloud deck later this afternoon and evening. This should set up a colder night area wide, with upper teens to lower 20s common and near single digit wind chill readings. Evening wind chills fall into the teens to low 20s. The surface high will move overhead tomorrow afternoon, providing for plentiful sunshine in spite of some passing higher clouds, along with much lighter winds. While highs will be similar to today, the light winds and sunshine will make it feel quite a bit better. One more cold night is in store for Sunday night as high pressure remains in place. KMD && .LONG TERM... 152 PM CST Monday through Friday... The coming holiday week will start off with dry and seasonal conditions (mid to upper 40s) as an upper level ridge moves overhead. Light winds will become easterly as low pressure organizes in the southern Rockies in response to a southern stream trough axis. Tuesday/Wednesday appears to be the most active portion of the extended period. The broad upper trough will eject out of the Rockies on Tuesday and then slowly progress east through the midwest on Wednesday. Several guidance sources bring a weak wave through ahead of the trough late Monday night into Tuesday but keep it dry. If any wet bulbing were to occur or forcing stronger there could be some light mixed precipitation initially, and the GFS is a bit more aggressive with the low level warm advection ahead of this system, depicting surface wet bulb temps just below freezing and actual surface temps close to freezing. At this point will stick closer to the full suite of models given the antecedent dry conditions and precipitation likely being lost to evaporation, plus this suite still largely maintains a drier solution for Tuesday morning. Feel confident in breezy southeast winds developing Tuesday as this trough organizes a surface low in the central/southern plains. Better combined forcing and moisture arrives later Tuesday into Wednesday which looks to be a wet period as the surface and upper lows move overhead and get seasonally elevated precipitable water values advected in on a modest low level jet, so expect wet roads for the busy travel day. The low will pull away Wednesday night, with some wrap around precipitation expected to largely remain liquid. This will also make way for dry conditions and once again seasonal temperatures for the Thanksgiving Holiday. A progressive upper level pattern remains in place for Thursday night/Friday as a shortwave moves through, but some significant differences in extended guidance regarding the track of the corresponding low and surface temperatures during the period of interest. Fortunately precip looks on the lighter side. KMD && .AVIATION... For the 18Z TAFs... We find ourselves sandwiched between departing low pressure across southeastern Quebec and strong high pressure across the plains. Pressure rises behind the low coupled with strong cold advection is resulting in decent mixing, though somewhat regulated by the cloud deck in place. Gusts have generally settled into the upper 20s to lower 30s with some higher gusts mixed in, with earlier gusts to 40 kt. Have held onto the lower 30 kt gusts which are the most common and these should likely hold for a good portion of the afternoon. Gustiness will continue this evening, though some decrease is anticipated late this afternoon, then more so overnight. Winds will be shifting to more northwesterly through the period. The low VFR deck will also erode from west to east, lingering a bit longer across the eastern half of Lake Michigan and into parts of NW Indiana. KMD && .MARINE... 240 PM CST Low pressure continues to pull off to the northeast this afternoon as high pressure builds across the plains and midwest. A strong pressure gradient still exists between these two features with solid gales across the south half of Lake Michigan and 10-13 ft waves. Several observations across the northern tier of the lake are also near storm force (along the shore, so likely higher across the open waters), and this supports no immmediate change to current headlines across Lake Michigan quite yet. Once storm force winds ease across the north, it is likely gales will continue for at least another 6 hours if not a bit longer, with gales finally easing Sunday morning. Winds do weaken more Sunday afternoon but waves will take a bit longer to subside. High pressure will translate over the lake Sunday night and Monday. Another weaker low will take aim at the southern tip of Lake Michigan Wednesday, with breezy southeast winds ahead of the low expected Tuesday and Tuesday night. Winds look to remain below gale levels, but this will build waves across the west side of the lake. KMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Wind Advisory...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 3 PM Saturday. IN...Wind Advisory...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 3 PM Saturday. LM...Gale Warning...NEARSHORE WATERS UNTIL MIDNIGHT Sunday. Gale Warning...LMZ777-LMZ779 UNTIL 9 AM Sunday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Marquette MI
425 PM EST Sat Nov 19 2016 .SHORT TERM...(This evening through Sunday) Issued at 425 PM EST SAT NOV 19 2016 Water vapor imagery and RAP analysis show a sharp mid/upper level trof over the Great Lakes. Lingering deep layer forcing associated with the trof is still over eastern Lake Superior. Combined with 850mb temps around -12C, lake enhanced snow is ongoing into the e half of the fcst area. To the w, subsidence and much drier air noted on the 12z CYPL sounding and in particular the 12z KINL sounding along with inversion down around 850mb have strongly limited LES today off western Lake Superior. Combined with the strong winds, there has not really been much in the way of shsn activity until well inland from the lake where orographic lift becomes sufficient. With inversion steady around 4kft over the w tonight, not expecting anything more than sct -shsn into the western fcst area. Coverage may increase a bit during the night as nocturnal cooling around the lake and increasing land breeze component to wind increase low-level convergence. However, any additional snow accumulations should only be an inch or less. To the e, lingering deep layer forcing pulls out this evening and is replaced by strong deep layer qvector divergence/subsidence with inversion falling to around 5kft. So, the current widespread lake enhanced snow over the e will evolve into a more typical multi-band les scenario by late evening. After this occurs, the main point of interest will be banding connected to Lake Nipigon preconditioning. Should see a dominant band set up into western Alger County tonight. High res model output is all fairly well clustered on this scenario with all also showing this band drifting w into Marquette county during the night into Sun morning though with different timing. Depending on how quickly the band shifts and how organized it becomes, it could produce a few inches of snow accumulation in a short period of time. Will be something to monitor. As for headlines, all headlines w of Marquette/Delta counties have been dropped. Maintained ongoing headlines elsewhere with the exception of dropping Marquette to winter wx advy. Nighttime snow accumulations should be on the order of 1 to 4 inches in the headline areas, with perhaps as much as 5 inches in far western Alger County associated with aforementioned band that develops from Lake Nipigon preconditioning. Winds will continue to diminish. Light les will continue on Sun, but will slowly diminish from w to e during the day. There may be some locally mdt/hvy snow in eastern Marquette county in the morning as discussed above. .LONG TERM...(Sunday night through Saturday) Issued at 316 PM EST SAT NOV 19 2016 Only significant weather in the long term is mid-week with potential for advisory (or possibly low end warning) level snow. An upper trough is modeled to move through the area mid-week, bringing a 1007mb SFC low from southern WI through central lower MI Wed and Wed night. Widespread precip may move into the W or SW by late Wednesday, and the bulk move out by Wed night. Models are in good agreement overall, but the GFS has the most QPF at up to 0.75" while the ECMWF only has up to around a half inch. Most of the precip falls as snow, with the exception possibly of the south- central where a transition to rain is more likely. If the events plays out as currently modeled, winter weather advisories would be needed over a good portion of the area, with potential for some warning amounts if the GFS amounts verify. For now, given the inherent uncertainty at that time frame with this type of system, will just mention of the HWO. Definitely will have to keep a close eye on the system given the high-impact travel day. Lighter snow is possible Thursday and Friday, but certainly not looking at any significant amounts right now. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1231 PM EST SAT NOV 19 2016 In the wake of the strong storm system that has moved across the Upper Great Lakes, cold air mass will generate lake effect shsn thru this fcst period with MVFR conditions generally prevailing at KIWD/KCMX/KSAW. Some periods of IFR are possible, especially at KSAW thru mid aftn. Influx of drier air will result in diminishing shsn with time so that periods without shsn become more frequent and longer duration. Meanwhile, the strong/gusty winds will gradually diminish from w to e. During the aftn, expect winds to gust to 30- 40kt, strongest at KCMX/KSAW. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 425 PM EST SAT NOV 19 2016 As pres gradient weakens as low pres moves farther away and high pres ridge approaches, ongoing gales over central and eastern Lake Superior will end tonight. While the high pres ridge and light winds will reach western Lake Superior Sun aftn, the ridge won`t reach eastern Lake Superior until Mon night. As a result, winds on eastern Lake Superior will remain in the 20-30kt range during Sun and won`t fall blo 20kt until later Sun night/Mon. Winds will increase across the lake later Tue into Wed as the next low pres system moves into the Great Lakes region. The strongest winds, 20-30kt, will occur over central and eastern Lake Superior on Wed. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory until 1 AM EST Sunday for MIZ005-013-014- 085. Coastal Flood Warning until 1 AM EST Sunday for MIZ006-007. Winter Storm Warning until 1 AM EST Sunday for MIZ006-007. Coastal Flood Warning until 7 PM EST this evening for MIZ005. Lake Superior... Gale Warning until 4 AM EST Sunday for LSZ248>251-265>267. Gale Warning until 1 AM EST Sunday for LSZ243>245-264. Gale Warning until 7 PM EST /6 PM CST/ this evening for LSZ240>242-246-247-263. Lake Michigan... Gale Warning until 4 AM EST Sunday for LMZ221-248-250. && $$ SHORT TERM...Rolfson LONG TERM...Titus AVIATION...Rolfson MARINE...Rolfson
Area Forecast Discussion
National Weather Service Portland Oregon
256 PM PST Sat Nov 19 2016 .SYNOPSIS...Broad low pressure will linger off the Pac NW coast into Sunday, producing showers and isolated thunderstorms...especially near the coast. The low will weaken and lift north into BC Sunday and Monday, with showers decreasing Mon/Mon night as transitory high pressure moves across the region. The next front moves in on Tuesday, bringing another round of rain and some coastal wind, followed by more showers Wednesday. Another Pacific frontal system is expected Thanksgiving Day. Snow levels will remain near the Cascade passes through Monday, then each frontal system will bring progressively colder air and lower snow levels through the end of the week. && .SHORT TERM...Tonight through Tuesday...WPC-analyzed 982 mb low pressure centered near 45N/130W is beginning to drift northward per latest satellite imagery, while pushing a secondary cold front into the Pac NW coastal waters this afternoon. Instability appears to be best over the coastal waters due to the relatively mild sea surface temperatures, driving a line of showers and thunderstorms along the cold front. With tops up to 22-24 kft, some of the cells are tall enough to produce a few lightning strikes, and this should continue to be the case as the front approaches shore. KLGX VAD wind profile seems to indicate winds are fairly unidirectional with height aside from some decent E-SE flow in the lowest 1-2 kft...which seems consistent with the idea that the best shear may have passed with the shortwave and occluded front that moved through this morning. While a stray spinup of a waterspout is possible with the cold front this afternoon and evening, the environment does not look quite as favorable as it did this morning despite the decent line of showers/ t-storms moving toward the coast. Convective-allowing models seem to hold the majority of showers and thunderstorms over water this evening...which makes sense considering the loss of daytime heating and the resulting stabilization over land. Some debris from convection firing off the S OR/N CA coast may hold together enough to bring some decent showers N-NE into our CWA overnight just ahead of the front...though it appears the latest HRRR and WRF and may be a little overdone in holding convection together over inland areas tonight. Decided to keep thunder mention restricted to the coast and waters, with a chance of showers east of the Coast Range overnight. Weakening front and upper level trough axis will drift through western WA/OR Sunday, keeping us unstable enough for plenty of showers. 1000-500 mb thicknesses and 850 mb temps remain marginal for snow at the Cascade passes...suspect there may be a wet coating from time to time during the night and morning hours, then melting during the day. It is interesting to note that there was a dusting of snow as low as 2000-2500` around Trout Lake and Parkdale this morning, with temps lingering in the mid to upper 30s through the day. Easterly gradients ahead of the cold front will continue to lock this cool air in place until - ironically - the cold front moves through Sunday to mix out the cool air. Fairly typical pattern for that part of our forecast area in the wintertime. Impacts should be negligible this time around, but this type of pattern may come into play again as the week progresses. Showers will decrease Mon/Mon night as the upper trough weakens and transitory high pressure moves across the Pac NW. Skies may clear enough for a chilly night with lows dropping toward the upper 30s in cooler portions of the Willamette Valley. It will likely be cooler in the Hood River Valley and near Trout Lake, which may result in some precipitation-type issues in those cooler valleys if precipitation arrives early enough with the next front Tuesday. However, 12z ECMWF/GFS suggest precip will arrive late enough in the day to allow temps to rise above freezing Tuesday...likely resulting in a similar event to today. Front will likely be splitting as it moves onshore, capping winds around 40-50 mph near beaches and headlands. East winds will be blustery through the Columbia Gorge and across the PDX Metro as the front approaches the coast. Weagle .LONG TERM...Tuesday night through Saturday...The above-mentioned Pacific frontal system will move across the district Tue night, with some modest precipitation and lowering snow levels. 18z GFS and 12z ECMWF suggest 850 mb temps will drop to around -2 deg C, which would correspond to a general snow level around 3000` through Wednesday as the associated upper trough swings through the region for more showers. This will be enough to set the stage for wintry driving conditions across the Cascade passes for the upcoming holiday weekend. Similar to Tuesday, there is also an outside chance of some precipitation-type issues in the Columbia Gorge Thanksgiving Day due to cold air east of the Cascades, depending on timing of the next front Thursday. Cool and unsettled weather will likely continue through the holiday weekend, with snow levels remaining near or below the Cascade passes and another potent front possible next weekend. Those with travel plans across the Cascades or Siskiyous during the upcoming holiday weekend should stay tuned to the weather, as there is decent potential for at least some weather impacts in the upcoming cool and unsettled pattern. Weagle && .AVIATION...Primarily VFR across the area, with the possible exception of localized MVFR in the Cascades. Little change in overall flight conditions through tonight, with the primary frontal zone remaining offshore. Instability will lead to a threat of thunderstorms over the coastal areas through Sun. The weakening frontal zone drifts Sun, with an increasing chance of MVFR for the coastal TAF sites. East wind 20 to 30 kt with gusts to 40 kt will continue at the west end of the Columbia Gorge through this evening. KPDX AND APPROACHES...VFR expected through Sun afternoon. More frequent shower activity Sun afternoon, but cigs to remain VFR. East wind 20 to 30 kt with gusts to 40 kt will continue near KTTD and the west end of the Columbia Gorge through this evening. This may result in localized LLWS. Weishaar && .MARINE...A 982 mb low pres area located near 45N and 130W early this afternoon will continue to track N to NE through tonight. Convective line along the frontal zone near 126W has had some lightning strikes early this afternoon. ASCAT pass indicated 35 kt wind along the convective line supporting the current gale warning. 12Z NAM valid 21Z today matched reasonably well with the ASCAT data. However, the GFS boundary layer wind speeds seemed to be a little strong. Gale force wind will continue over the outer waters through tonight. Opted to end the gale 14Z Sun, a little earlier than previous forecasts. NAM indicates 25 kt boundary layer wind speeds 12Z Sun. It will be tough to get gale force wind gusts into the inner waters due to the surface pressure orientation...but gusts to 35 kt a good bet near the 10 nm boundary through tonight. Wind direction will veer south to southwest over the outer waters tonight and more toward the south over the inner waters late tonight. Models show wind speeds falling below 15 kt late Sun night and continuing through Mon evening. Looks like another potential gale event late Mon night through Tue, followed by yet another possible gale Thu. Seas over the outer waters expected to peak in the 16 to 19 ft range by this evening, with localized 20 ft not out of the question. Seas over the inner waters will not be as high, generally 14 to 17 feet. There will be mix of primary SW swell, a large south fresh-swell and then a lower but longer-period west swell from a distant source region. Seas gradually ease Sun, falling to around 12 feet by late Sun afternoon. However, guidance suggests seas building to the upper teens Wed night and Thu, then possibly exceeding 20 ft next Fri. Weishaar && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Gale Warning until 6 AM PST Sunday for Waters from Cape Shoalwater WA to Florence OR from 10 to 60 nm. Small Craft Advisory until 4 PM PST this afternoon for Coastal Waters from Cape Shoalwater WA to Florence OR out 10 nm. Gale Warning until 6 AM PST Sunday for Coastal Waters from Cape Shoalwater WA to Florence OR out 10 nm. Small Craft Advisory for Rough Columbia River Bar until 1 PM PST Sunday. && $$ Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. The area is commonly referred to as the forecast area.
Area Forecast Discussion
National Weather Service Charleston WV
146 PM EST Sat Nov 19 2016 .SYNOPSIS... Upslope snow lingers into Sunday night in strong, cold northwest flow. High pressure early next week. Another front mid week. && .NEAR TERM /THROUGH SUNDAY/... As of 130 PM Saturday... Winter making its first appearance this weekend, in the wake of a strong cold front that whipped through the area this morning. Large upper level short wave trough swinging through the area this afternoon takes on a negative tilt tonight, and then closes off over the northeast U.S. atop surface low pressure, as a stacked system. Strong cold advection west to northwest flow on the back side of the system will continue to drive temperatures down. This will transition wrap around rain showers over to snow showers from west to east and high terrain to lower terrain by tonight, and then the precipitation transitions into an upslope event tonight, as the upper level trough axis pushes east of the area. Upslope precipitation will be enhanced by plume off lake Michigan across northern portion of forecast area, which may enhance snowfall amounts in the northern mountains. This is already reflected in the forecast, and overall no changes were needed to the snow amounts. Have a borderline advisory event for snow, along with a solid wind advisory event, for the higher terrain portions of Randolph, Webster and Pocahontas counties. Wind gusts may actually trough 50 kts across the very highest terrain overnight tonight. The upslope snow showers start to wane late Sunday, as approaching high pressure starts to slacken the pressure gradient. Temperatures similar to previous, fine tuned / updated via the HRRR, RAP and NAM. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 145 PM Saturday... Still a few light upslope snow showers lingering across the northern mountains Sunday night, but overall, will be tapering off, as flow starts to back and become less favorable, as high pressure gradually builds into the region. Sunday night will continue to be cold, and windy, with wind chills in the teens to single digits across the higher terrain, particularly across eastern zones where tighter pressure gradient will exist as high gradually tries to nudge east. Dry, with gradually warming conditions Monday and Tuesday, as high pressure surface and aloft continues to take hold. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... As of 145 PM Saturday... Clouds will be on the increase across the area on Tuesday, as a warm frontal boundary lifts north across the region. Showers will overspread the area again by Wednesday as low pressure, and associated cold front approach from the west, but enough warm air should be in place owing to strong southerly flow, that bulk of precipitation will be in the form of rain. Another system approaches the area next weekend. At this point, the exact track, and thus precipitation type is very uncertain, but could be at least a light snowfall for the higher terrain, along with the possibility for a rain/snow mix at times across some lower elevation locations. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... As of 130 PM Saturday... Strong west to northwest flow will continue this period, in the wake of a cold front that blew through the area this morning. Winds will strengthen this evening, with gusts of 30 to 35 kts across the lowlands, and 30 to 35 kts in the mountains. These strong winds will start to slowly diminish Sunday morning. MVFR ceilings will be prevalent, lifting to VFR at times across the lowlands this afternoon, and in ernest across the lowlands late Sunday morning. VFR visibility may drop to brief MVFR in rain showers this afternoon, and to MVFR or IFR in snow showers in the mountains tonight, when MVFR visibility may be more persistent at EKN amidst occasional IFR visibility in heavier snow showers. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY... FORECAST CONFIDENCE: Medium ALTERNATE SCENARIOS: Ceilings and Visibilities will be highly variable in snow showers in the mountains. The strong gusty winds will fluctuate. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 CRW CONSISTENCY H H H H H H M H L M M L HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY L L L L L L L L L L L L EKN CONSISTENCY L L L L L L L L L L L L PKB CONSISTENCY L M H H H M M M M L M L CKB CONSISTENCY M H H H M H M L M L L L AFTER 18Z SUNDAY... IFR possible within upslope snow showers into Sunday night across the mountains. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Winter Weather Advisory until 4 AM EST Monday for WVZ522-523- 526. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/SL NEAR TERM...TRM SHORT TERM...SL LONG TERM...SL AVIATION...TRM