Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/27/17

Area Forecast Discussion
National Weather Service State College PA
1012 PM EST Thu Jan 26 2017 .SYNOPSIS... Windy and seasonably cold weather with occasional lake effect and orographically enhanced snow is in store right through the end of what has been a very mild month. && .NEAR TERM /THROUGH FRIDAY/... Colder NW flow is establishing behind a secondary cold front that passed late this afternoon. This will set the stage for a prolonged period of breezy NW flow and plentiful cloudiness for much of western and central PA, along with a light to moderate snow event for the western high terrain. The current radar shows numerous snow showers moving into my western higher elevation counties, then dissipating as they down- slope into central areas. The HRRR shows these multiband snow showers continuing non-stop throughout the night into Friday. As a result, the long duration Winter weather Advisory for the Laurels and Warren Co continues through 06Z Sat. && .SHORT TERM /FRIDAY NIGHT/... Nearly constant stream of lake moisture and steady state cyclonic flow will lead to occasional, but generally only light to moderate snow for the Alleghenies/Laurels and Lake Effect Snow Belt. The stronger orographic component orthogonal to and up the steep slopes of the Laurels will generate a more-constant snow than what might occur directly off LE. But most of the moisture flowing into the Laurels will be off distant Lake Michigan. The best dual lake effect (Huron and Erie) will occur across the NW snowbelt, but even there the air/water temp difference is not all that great. However, the combination of these two components will be sufficient to generate numerous LES bands - mainly short in length due to a good amount of speed shear in the vertical. This fetch and overall synoptic set-up are usually only problematic for NW Warren Co. As with storm totals over the Laurels (that could reach 8-10" on the highest ridges west of RT 219 by early Saturday, the 5-8" of expected snow accumulation will fall over a long...36-hour period, but many of those 12 hour periods inside the length of the advy have the potential to get 2-3". Even under such a persistent west-northwest flow pattern with LES conditions, daytime temps will be near to a few deg F above normal. && .LONG TERM /SATURDAY THROUGH THURSDAY/... A long wave pattern of deep troughing in eastern Canada and good flow into the Great Lakes and Mid-Atlantic from the Northwest Territories will result in a mainly dry but lake-effect filled time of seasonable (read: cold) temperatures. A clipper system embedded in the cyclonic flow may expand snow accumulation to the east of the Allegheny Mountains Sun-Mon. A second clipper is forecast to take a similar path midweek. Global model and ensemble consensus keeps a mean trough in the Eastern U.S. next week which should favor continuation of typical late January/early February cold. Within this flow major synoptic scale winter storms are on the horizon. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... The strong westerly flow will keep gusty winds at most TAF sites through the first half of the overnight period. The westerly flow will keep upslope/orographic flow to enhance any low cloud development, which will result in IFR cigs with light snow showers through the NE for reduced vsbys as well. Further east across the Susq Valley, a downsloping/strong westerly flow will yield better flying conditions, with primarily VFR conditions through tomorrow. Itermittent IFR at BFD will continue overnight before lifting/dissipating early Friday morning. IFR and JST will continue as the westerly flow will keep moist low level flow entrenched over the region through most of the day. There should be some improvment of conditiosn to MVFR tomorrow afternoon and evening. Outlook... Fri-Mon...IFR to MVFR in snow showers BFD/JST. VFR- ocnl MVFR east. && .EQUIPMENT... KCCX radar is back up...for now. Technicians will return Friday to affect a more permanent repair. KFIG surface observation will be offline for an extended period of time due to failed power feed to the DCP. && .CTP WATCHES/WARNINGS/ADVISORIES... Lake Effect Snow Advisory until 1 AM EST Saturday for PAZ004. Winter Weather Advisory until 1 AM EST Saturday for PAZ024-033. && $$ SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Lambert LONG TERM...Gartner/Steinbugl AVIATION...Fitzgerald/Ceru EQUIPMENT...
Area Forecast Discussion
National Weather Service Jacksonville FL
844 PM EST Thu Jan 26 2017 ...Much Colder Tonight through Sat... .UPDATE...Surface cold front continued to press south across north-central Florida this evening trailed by a fading thin line of post-frontal light showers/drizzle that was across the Ocala National Forest and southern Flagler county this hour. Much cooler and drier low level air air was funneling across the local forecast area under NW flow up to about 900 mb with surface temperatures falling into the 50s across much of the area. HRRR and NMM guidance suggested another band of spotty showers developing across the forecast area tonight under passing mid level energy tracking over the area form the Gulf. At this time continued to only indicate 10% chances of rainfall as low level airmass was drying very quickly in the wake of the surface front with a low level NW flow...but giving passing energy and mid level moisture over the area tonight...there could be very light non-measurable sprinkles at times overnight through sunrise. Passing mid and high clouds will continue to stream over the area through the night which in concert with dry low level air will prevent fog formation. Low temperatures will fall into the low/mid 40s inland to low/mid 50s coast. && .AVIATION...Prevailing VFR conditions. Breezy WNW winds will develop Friday with gusts up to 15-20 kts at times. && .MARINE...WNW winds 15-20 kts expected over the outer waters tonight where exercise caution headlines will continue. Rip Currents: An extended period of offshore flow is expected through early next week. A low risk of rip currents is expected. && .PRELIMINARY POINT TEMPS/POPS... AMG 43 62 36 56 / 10 0 0 0 SSI 46 63 40 54 / 10 0 0 0 JAX 48 64 39 57 / 10 0 0 0 SGJ 50 64 39 59 / 10 0 0 0 GNV 49 63 37 59 / 10 0 0 0 OCF 51 63 39 60 / 20 0 0 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Enyedi/Zibura/Corless/Guillet
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
932 PM CST Thu Jan 26 2017 .UPDATE... Issued at 932 PM CST Thu Jan 26 2017 Going forecast still looks on track with low clouds staying in over the region much of the night. Have gotten fewer reports of flurries in the last hour. Did some minor tweaking to temperatures based on trends. Britt && .SHORT TERM... (Through Late Friday Afternoon) Issued at 349 PM CST Thu Jan 26 2017 Scattered flurries will continue through the early evening, and some locations could see a light dusting of snow. An elongated trough axis stretched from Ontario to the SoCal coast early this afternoon per water vapor imagery and RAP output. Several embedded vorticity maxima were noted within the trough axis, which will continue pivoting across the country tonight and tomorrow. Clouds and occasional flurries will continue through tomorrow afternoon until the trough axis has moved through the area, leaving northwest flow aloft in its wake. West to northwest surface winds will occasionally gust to around 20 kts on Friday due to diurnal mixing. Kanofsky .LONG TERM... (Friday Night through Next Thursday) Issued at 349 PM CST Thu Jan 26 2017 The synoptic pattern at the start of the long term period will feature an amplifying trough across the east coast, which will place the Midwest within active north/northwesterly flow through the weekend. Some deamplification of the pattern will occur by the beginning and middle of next week as a western ridge attempts to nudge eastward into the Central Plains. Friday night into Saturday will feature the first of two rather potent PV anomalies diving southeast across the region. However, despite the impressive cold pocket of air aloft and associated height falls, this system will have very limited moisture to work with. Forecast soundings depict a shallow near-surface moist layer, but saturation only reaches up to around -6 or -7C. At these temperatures, ice nuclei activation is unlikely, thus will continue to leave flurries out of the forecast for now and just stick with a mostly cloudy forecast an temperatures in the mid to upper 30s. By Saturday night and especially into Sunday, moisture depth will increase ahead of yet another strong PV anomaly diving southeast through the northwesterly flow. The increasing moisture depth coupled with the ascent from the strong shortwave will lead to a better chance of flurries, and even a chance of some light snow showers. By the afternoon, low-level lapse rates will steepen significantly (especially across far eastern MO and western IL) to perhaps produce some convective snow showers, which may be able to spit out some brief/light accumulations. Have upped pops during this timeframe given the latest trends in guidance. By Monday through the middle of next week the flow should begin to deamplify as the eastern trough lifts out and the persistent ridge out west attempts to shift to the east/southeast into the southern and central Plains. This should allow the main storm track to be displaced generally to the north of the region, thus dry weather is expected from Monday onward. Temperatures will moderate into the 40s Monday and Tuesday, but another surface cold front associated with low pressure passing to our north will knock temperatures back into the 30s/low 40s by Wednesday. KD && .AVIATION... (For the 00z TAFs through 00z Friday Evening) Issued at 540 PM CST Thu Jan 26 2017 Light flurries will be possible this evening, and may reduce visibilities within the VFR range temporarily. Otherwise...expect mainly MVFR or low VFR ceilings through at least midday Friday before ceilings improve and eventually scatter out by late in the afternoon. SPECIFICS FOR KSTL: Some light flurries will be possible this evening, but expect VFR visibilities. Otherwise expect MVFR ceiling through mid afternoon on Friday before they rise to VFR and skies eventually scatter out by tomorrow evening. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Pueblo CO
751 PM MST Thu Jan 26 2017 .UPDATE... Issued at 749 PM MST Thu Jan 26 2017 SNOW SHOWERS HOLDING TOGETHER AND ACTUALLY INTENSIFYING OVER PUEBLO COUNTY AT THIS HOUR. LOCAL ACCUMULATIONS UP TO AN INCH POSSIBLE...MAKING ROADS SLICK. ACTIVITY SHOULD CONTINUE SOUTH ALONG THE I-25 CORRIDOR...WITH TROUGH...NEXT FEW HOURS. POPS HAVE BEEN INCREASED ACROSS THE PUEBLO COUNTY AREA TO LIKELY. UPDATE Issued at 528 PM MST Thu Jan 26 2017 IN LIGHT OF ONGOING AND DEVELOPING SNOW SHOWERS DROPPING SOUTH WITH UPPER DISTURBANCE...UPDATED GRIDS AND FORECAST WITH HRRR VERSION OF THINGS FOR THIS EVENING. THE HRRR HAS SNOW SHOWERS DROPPING SOUTH ALONG AND WEST OF THE I-25 CORRIDOR THROUGH THE EVENING AS INSTABILITY ROLLS THROUGH WITH UPPER TROUGH PASSAGE. ACCUMULATIONS SHOULD BE GENERALLY LIGHT...AN INCH OR LESS FOR THE LOWER ELEVATIONS ALONG AND WEST OF I-25...AND GENERALLY 2 INCHES OR LESS FOR THE HIGHER TERRAIN. COULD BE SOME LOCAL ACCUMULATIONS UP TO 3 INCHES ALONG AND SOUTH OF THE WET MOUNTAINS THIS EVENING AS A LITTLE BIT MORE INTENSE CONVECTION DEVELOPS DOWN THAT WAY. && .SHORT TERM...(This evening through Saturday Night) Issued at 321 PM MST Thu Jan 26 2017 Western portion of the deep Great Lakes/Ern Canada upper trough still in place across Colorado today, with another round of flurries and snow showers over mainly the mountains this afternoon. Have also seen just enough weak s/se upslope to generate some flurries near the Palmer Divide and east slopes of the Rampart Range/Pikes Peak, with clouds slow to clear over El Paso county. For tonight, a few mesoscale models suggest mountain flurries/light snow showers will develop from Teller county southward into the Wets and Sangres this evening, though any accumulations will be minor. Remaining mountains will see some flurries as well, with perhaps a brief flurry across nrn El Paso county until shortly after sunset. Expect enough clearing overnight for min temps to fall to fairly cold levels, with San Luis and upper Rio Grande Valleys well below zero once again. On Friday, upper trough drops south of the state, and with warming temps aloft, snow showers should come to an end by early morning and will keep the bulk of the day precip free across the entire area. Max temps will begin a slow climb back toward seasonal values Fri afternoon, though again most interior valleys will struggle to break strong morning inversions and only reach the teens/20s at best. On Saturday, nly flow aloft will actually bring in some warmer air in the mid levels, with max temps back to well above freezing across the plains and I-25 corridor, while mountains and valleys see less dramatic warming with readings creeping up into the 20s at most locations. .LONG TERM...(Sunday through Thursday) Issued at 321 PM MST Thu Jan 26 2017 Not much change the forecast thinking with better agreement between the Ensembles, GFS and ECMWF. This leads to higher forecast confidence through Wednesday before minor differences arise on Thursday. A highly amplified pattern, with a trough over the Ohio Valley, and high pressure along the west coast, will shift east through the extended period and become more zonal with time. Broad northwest flow across the region Sunday into Monday will shift east as the upper ridge moves over head Tuesday into Wednesday. Dry and warm conditions are expected to prevail through Tuesday with highs in the 50s, to perhaps a few low 60s Monday. A cold front is forecast to back west across the Plains Tuesday night. The GFS wants to develop light drizzle across the Plains behind the front late Tuesday night into Wednesday morning, but there is low confidence in this happening at this time. Temperatures on Wednesday will be slightly cooler with lower 50s for highs. By Thursday the upper level flow pattern becomes more zonal. The GFS brings a decent shortwave trough across Colorado with a round of mountain snow. The ECMWF has a much weaker disturbance that moves across the area in the zonal flow, but no precipitation associated with it. At this time based on the ensemble support, kept the forecast dry on Thursday like the ECMWF. Mozley && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 321 PM MST Thu Jan 26 2017 At KALS...main concern is the potential for a brief period of stratus and ground fog near the terminal 09z-16z. Given most model guidance suggest drier air filtering into the valley overnight and lack of any snow melt today, will hold off on any IFR conditions in the TAF and just mention some sct lower clouds. VFR conditions then likely from mid morning through the day Fri. At KCOS...very weak s/se upslope has kept patchy MVFR cigs and flurries going through much of the day near/just north of the terminal, though most cigs have risen to VFR levels as of 22z. Will keep a VCSH mention and VFR cigs in the TAF through about 04z, though very brief MVFR conditions may be possible under any heavier -shsn. Nly flow from late this evening and overnight should end the threat of -shsn and help dissipate any residual cloud cover, with VFR conditions from after 06z through the day on Fri. At KPUB...VFR tonight and Fri with winds becoming light nly. Over the mountains...areas of -shsn will occasionally obscure the higher peaks into the evening, with some partial clearing overnight as showers end. Expect mainly VFR on Fri as threat of -shsn diminishes. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...LW SHORT TERM...PETERSEN LONG TERM...MOZLEY AVIATION...PETERSEN
Area Forecast Discussion
National Weather Service Blacksburg VA
930 PM EST Thu Jan 26 2017 .SYNOPSIS... Our area will progressively trend cooler beginning tonight and lasting into Monday. While dry conditions are expected for most of the forecast area, periods of light accumulating snow showers will develop at times in parts of southeast West Virginia, far southwestern Virginia and into the North Carolina high country through Monday. Temperatures look to be near to below normal into early next week before moderating by mid next week. && .NEAR TERM /THROUGH FRIDAY/... As of 920 PM EST Thursday... Not much in the way of snow showers this evening with main vort lobe tracking north of our CWA, but will see a better vort lobe pass across from southern KY overnight, mainly between 10pm and 2am which should increase the coverage, mainly over the west. Did not change much to accumulations but a half inch to an inch is not out of the question by dawn in western Greenbrier county, with a dusting south to the NC high country. Previous discussion from early afternoon... The central and southern Appalachians into the VA/NC Piedmont continues in a post-frontal west- northwest flow this afternoon in broad cyclonic mid-level flow aloft. Aided by low-level cold advection, winds this afternoon have been breezy to gusty with area Doppler radar wind profilers indicating west-northwest winds of 40 kts through 5000 ft. Visible satellite reveals expansive stratocumulus field to our northwest associated with the cold pool of air aloft. While the forecast area is presently dry, composite radar imagery indicates some light radar returns northwest of Charleston, WV into the Ohio Valley. For the rest of the afternoon: Best WNWly low-level jet should be occurring within the next couple of hours per the 12z 4-km NAM output. To this point, peak winds have only topped out in the lower 40 mph range at sites such as Boone, Roanoke and Hot Springs. Will let the Wind Advisory continue as scheduled through 7 PM. By nightfall, diminishing low-level wind fields and stabilizing low-level lapse rates with cooler temps should reduce magnitude and frequency of gusts. Advancing into tonight...focus then shifts to cooling temperatures and the start of what projects to a long duration light accumulating upslope snowfall for the favored upslope areas in southeast West Virginia, the Mountain Empire/Grayson Highlands and into the NC High Country (continuing at least periodically into the weekend). Cooling thermal profiles aloft and 2-m AGL temps should allow for a transition of light rain over to snow showers. Focus for PoPs being across western Greenbrier County southwestward into Mercer and Summers Counties in West Virginia into narrow bands oriented parallel to the low-level flow (per HRRR and 4-km NAM depictions in simulated reflectivity progs). I kept PoPs in the slight to lower Chance range in far southern Virginia, the Alleghany Highlands and into the mountains of North Carolina. In these areas, there`s some question how far south and east these precip bands actually make it. The best chance for light accumulations is in the southeastern West Virginia county, which through 12z Friday are about a coating to an inch, ramping up to 1-2" in western Greenbrier County. Snowfall amounts are lower than Winter Wx Advisory thresholds, and the accumulation forecast is complicated initially by likely mild pavement temperatures (given several preceding days of above-normal temperatures) that may keep accumulations limited to grassy surfaces until well after dark. Elsewhere, clear skies and cooling temperatures should allow for temps to fall to near freezing along/east of the Blue Ridge, with mid/upper 20s west. For Friday: Continued variable amounts of cloud cover, greatest west in periods of light upslope flow snow. While light upslope snows should continue in southeast West Virginia, the 12z GFS and NAM show a vort max rippling through the broad cyclonic flow in the morning hours that may help lead to a greater coverage of snow showers in southwest Virginia and the NC mountains. So while PoPs are high chance to low likely in most of southeast West Virginia, I upped them in the morning hours in southwest Virginia and northwestern North Carolina. There`s some question if morning snows end in these areas by the afternoon as there`s uncertainty if any additional vorts in the flow may lead to any additional accumulations in Smyth, Grayson, Ashe and Watauga Counties. Those vort energy details probably will be a common question mark in this broad longwave troughiness that we look to be stuck in. Additional light accumulations of a coating to 2 inches for the first half of Friday, greatest in western Greenbrier County. Otherwise, it should feel the coolest it has been in some time for our area as highs only top out near or a few degrees above freezing west of the Blue Ridge into the North Carolina high country, but greater moderation in the 40s along and east of the Blue Ridge where less cloud cover is expected. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... As of 317 PM EST Thursday... During this portion of the forecast, the region will continue to be under the influence of a broad upper level trough with periodic embedded shortwave troughs rounding the base of the main trough. The result will be a prevailing west to northwest flow across the region. For southeast West Virginia south into the Northern Mountains of North Carolina, this will mean a prolonged period of upslope snow showers and abundant cloud cover. The snow will be nearly continuous, but come in heavier spurts, coincident to the passing of the shortwave troughs. The farther east one gets toward the crest of the Blue Ridge, the less snow is expected, as well as somewhat less cloud cover. East of the crest of the Blue Ridge, the prevailing west to northwest flow will yield subsidence with limited cloud cover, and milder conditions. The best opportunity for light snow to progress east of the crest of the Blue Ridge will be late Sunday afternoon into Sunday night when the most vigorous of the shortwave troughs is projected to cross the region. During the time period from tonight through Sunday night the region between southeast West Virginia, south to near Marion and Richlands, VA, and into the Northern Mountains of North Carolina an average of two to four inches of snow is expected. Western sections of Greenbrier County, WV will more likely receive an average of four to seven inches of snow with some isolated eight inch amounts at the highest elevations. At this point, no advisories are being issued given the long duration it will take for this amount of snow to accumulate, and most of the snow will come in distinct bursts. The most likely time period where an advisory may be warranted would be Sunday into perhaps Monday when the strongest of the shortwave troughs passes across the area. At the current time, any accumulating bursts of snow will be addressed within Special Weather Statements. Temperatures during this portion of the forecast will be near, to slightly below normal across the mountains and near, to slightly above normal across the Piedmont. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 317 PM EST Thursday... Monday morning, the influence of the passing vigorous shortwave trough will still be felt across the region with additional light measurable snow still probable across the preferred upslope regions in the west. Monday night through Wednesday, the area may see a small break in the prevailing northwest flow during the Monday night into early Tuesday time period. However, the overall general pattern of a broad trough across the northeast U.S. will continue. Fewer embedded shortwave troughs are progged to swing through the primary trough and impact the western sections of the area. However, the overall general northwest flow pattern will continue to allow for scattered light snow showers across primarily parts of southeast West Virginia. The best chance currently looks like Tuesday night into Wednesday when the added energy of a shortwave trough is expected to cross the region. Wednesday night into Thursday may be the start of a pattern change. Guidance suggests the broad trough in the northeast will be replace by more of a zonal flow. The forecast for this time period offers no precipitation. Temperatures during this portion of the forecast are expected to be near normal Monday and Tuesday, but then trend to about five to ten degrees above normal Wednesday and Thursday. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... As of 730 PM EST Thursday... Higher confidence in conditions east of the Blue Ridge, lower confidence to the west. The Appalachians and central mid Atlantic region will remain between large high pressure over the Rockies and large low pressure north of the Canadian maritimes. This will keep TAF sites in a brisk west/northwest flow of cold air over the region, with upslope conditions west of the Blue Ridge and downslope conditions to the east. As a result, KLYH, KDAN, and KROA can generally expect VFR conditions with gusty winds through Friday, while KBCB, KBLF, and KLWB will have bouts of snow showers/flurries and MVFR/IFR visibilities and ceilings with the gusty winds through the period. The mostly likely timing for sub-VFR conditions in the west will be tonight through Friday morning with some improvement expected heading into Friday afternoon. Winds will also slacken a bit toward the end of the TAF period. Extended Aviation Discussion... Cold west to northwest wind flow will persist into Sunday with mountain snow showers likely for the weekend including sub- VFR cigs/vsbys espcly across the southeast West VA locations. A final weak disturbance could bring more in the way of widespread mountain MVFR/IFR in low clouds and light snow Sunday night into Monday morning. Should finally see improving conditions later Monday with a gradual end of the upslope snow showers in the west, as the persistent northwest flow weakens and turns more westerly. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AL NEAR TERM...AL/WP SHORT TERM...DS LONG TERM...DS AVIATION...AL/MBS