Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/16/21

Area Forecast Discussion
National Weather Service Green Bay WI
524 PM CST Mon Feb 15 2021 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Tuesday Issued at 230 PM CST Mon Feb 15 2021 Partly sunny skies prevailed across the region this afternoon. It was still very cold with readings in the single digits above zero, except at Marinette/Menominee where it was 11 degrees. For tonight, have posted a wind chill headline for portions of central and north-central Wisconsin. Decided to add northern Marinette and northern Oconto Counties to the wind chill advisory after running the numbers. Lows tonight will range from a few degrees above near Lake Michigan to near 25 below zero across Vilas County. Attention then turns to the lake effect potential tonight for portions of east-central Wisconsin, especially Manitowoc County. The meso models having a lake effect snow band set up this evening offshore and then heads westward towards the shoreline late this evening and overnight. Latest meso models still give several solutions on how far west the lake band will get which will have a significant impact on snowfall totals. To complicate matters, the latest HRRR keeps the most intense portion of the band remains offshore and pointed towards Sheboygan County. Did contemplate upgrading to a warning, but the above mentioned concerns will result in the Winter Weather Advisory remaining in place for now. If the main portion of the band sets up across eastern Manitowoc County like the ARW model would suggest, totals could be considerably higher which would prompt an upgrade to a winter storm warning. Will pass on concerns to the evening shift. Any lingering snow across east-central Wisconsin will gradually end tomorrow as winds turn more northerly than northeast like tonight. Highs will be mainly in the teens to around 20, which will seem fairly balmy after the last several days. .LONG TERM...Tuesday Night Through Monday Issued at 230 PM CST Mon Feb 15 2021 Cold weather will linger into Tuesday night, but a gradual moderation in temperatures is anticipated through the week, with highs reaching the upper 20s to lower 30 by Sunday, and lower to middle 30s by Monday. Have kept small pops for lake-effect snow showers from Wednesday afternoon through Thursday, as winds maintain an easterly component off Lake Michigan. A short-wave trough may bring some light snow showers or flurries Thursday night into Friday, especially in eastern WI. Models show big differences with a low pressure system moving through the region on Sunday. The GFS has a strong low moving through WI, and bringing heavy snow to much of GRB CWA. The ECMWF is much weaker and farther south, and suggests perhaps an inch or two of snow in the southeast part of the forecast area. Probabilistic forecast information supports the weaker solution, so will just mention chance pops for much of the region for now. && .AVIATION...for 00Z TAF Issuance Issued at 524 PM CST Mon Feb 15 2021 VFR conditions will continue through Tuesday for all the TAF sites except MTW and locations along Lake Michigan. The lower flying conditions will be a result of lake effect clouds and a lake effect snow band moving onshore late this evening and overnight. Ceilings will likely drop to MVFR/IFR while visibilities drop below a mile at times in the heaviest snow band. Intermittent light lake effect snow will likely linger through at least mid week. && .GRB WATCHES/WARNINGS/ADVISORIES... Wind Chill Advisory until 10 AM CST Tuesday for WIZ005-010>013- 018>021-030-035-036. Winter Weather Advisory until noon CST Tuesday for WIZ050. && $$ SHORT TERM.....Eckberg LONG TERM......Kieckbusch AVIATION.......Cooley
Area Forecast Discussion
National Weather Service Lincoln IL
937 PM CST Mon Feb 15 2021 .SYNOPSIS... Issued at 307 PM CST Mon Feb 15 2021 Moderate to at times heavy snow will continue through this evening and eventually taper off to flurries overnight tonight. Temperatures will be cold tonight, falling into the single digits and even below zero is some locations near the Illinois River Valley. Temperatures will warm into the teens Tuesday under partly to mostly cloudy skies. && .UPDATE... Issued at 937 PM CST Mon Feb 15 2021 Tweaked the grids some tonight. Looks like the snow will be tapering off. However, not going to change any of the headlines at this time due to the blowing and drifting snow that will continue through the night. Update will be out shortly. && .SHORT TERM...(This evening through Tuesday) ISSUED AT 307 PM CST Mon Feb 15 2021 Snow is ongoing and increasing in intensity this afternoon across central Illinois. Water vapor imagery reveals a negatively tilted shortwave lifting across portions of mid Mississippi Valley, ejecting out ahead of main upper low centered over eastern KS. Snow is expected to peak across the area through around midnight tonight when the H5 low finally begins to shift across central Illinois marking the back edge of the accumulating snow. No major changes to the going forecast made this afternoon with the heaviest snow still expected to be focused over the eastern part of the state. From this afternoon through tonight, in addition to snow that fell last night into this morning, an additional 3 to 6 inches of snow is possible along the Illinois River Valley (under the Winter Weather Advisory), 4 to 8 inches from the I-55 to I-57 corridors, and 6 to 10 inches east of I-57. Latest RAP does depict a modest layer of FGen over east central Illinois and regional radar does show a couple bands of heavier snow lifting north. Does seem the better banding potential will be through the remainder of the afternoon and then will diminish with time this evening. Under the heavier bands, visibility less than a quarter mile and snow rates of around an inch per hour or slightly higher are possible, at least briefly. Meanwhile, winds will remain breezy out of the north through at least midnight tonight with gusts of 20 to 30 mph. Winds should begin to taper slowly after midnight, but in the meantime the breezy north winds will result in blowing and drifting of snow, especially on east-west oriented roads. Given the high snow to liquid ratio (20+:1), snow is expected to shift pretty easily through tonight. .LONG TERM...(Tuesday night through Monday) ISSUED AT 307 PM CST Mon Feb 15 2021 Expect a brief break in snowfall on Tuesday. Low pressure will exit east towards New England Tuesday while expansive ridge spreads south from the Upper Midwest along the Mississippi River Valley. This ridge axis will shift across Illinois late Tuesday evening. Temperatures remain bitterly cold with highs only in the teens then lows Tuesday night dipping into the single digits and just below zero in some spots. Cloud cover and its impacts on temps will be the primary area of uncertainty Tuesday night. While there may be a window of clearing skies Tuesday evening resulting in otherwise very favorable radiational cooling conditions with fresh snow pack and light winds, do expect clouds to increase from the SW overnight which will help to prevent temps from really bottoming out. Wednesday into Thursday, a strong shortwave will round the base of a deep upper trough centered over the Great Plains and lift northeast across the lower to mid Mississippi Valley. There remains quite a bit of model spread on the evolution of this system, but in general guidance depicts an elongated trough of low pressure centered over the Deep South that lifts northeast along the Appalachians. Models are in generally good agreement that an initial warm advection driven wing of precip will overspread central Illinois Wednesday. Differences grow quickly thereafter with some models (GFS, ECMWF) placing the bulk of the deformation axis snow well to our east while others (NAM, GEM) bring heavier snow across central Illinois. Confidence further out increases again as models indicate another strong high building across the Great Plains Friday and Saturday. Dry weather is expected to prevail during this time. Temps remain bitterly cold Friday, but should moderate Saturday as the ridge axis shifts east and return flow spreads across the Midwest in its wake. Some locations could see temps near or above freezing by this weekend, especially on Sunday into early next week. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 544 PM CST Mon Feb 15 2021 LIFR and VLIFR conditions will continue this evening as moderate to heavy snow continues at all sites. As the system lifts ENE the back end of the heavies snowfall will end around midnight. So will increase vis and cigs a little bit but still seeing IFR conditions. Conditions will improve quickly and expecting VCSH during the overnight hours at all sties with cigs just above 1kft. MVFR cigs will continue tomorrow at all sites but should become broken in the late morning through afternoon. Winds will be northerly through most of the period at 10-15kts. Winds will become northwest tomorrow at around 10kts. && .ILX WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 6 AM CST Tuesday for ILZ038-042>046- 048>057-061>063-066>068-071>073. Winter Weather Advisory until 6 AM CST Tuesday for ILZ027>031- 036-037-040-041-047. && $$ UPDATE...Auten SYNOPSIS...Deubelbeiss SHORT TERM...Deubelbeiss LONG TERM...Deubelbeiss AVIATION...Auten
Area Forecast Discussion
National Weather Service Indianapolis IN
1008 PM EST Mon Feb 15 2021 .UPDATE... The NEAR TERM Section has been updated below. && .SYNOPSIS... Issued at 247 PM EST Mon Feb 15 2021 Heavy snow has returned to central Indiana and will continue through the evening before tapering off after midnight. Snow will continue to blow around through the day tomorrow with the next round of wintry weather arriving Wednesday night into Thursday. Dry and warmer weather then looks to return late in the weekend into early next week. && .NEAR TERM /Overnight/... Issued at 1009 PM EST Mon Feb 15 2021 Surface analysis shows deep low pressure in place over eastern Kentucky. Cold arctic high pressure remained in place over Minnesota. Cold and gusty north winds were the result across the forecast area as strong pressure gradient remained in place. Radar shows the back edge of the expected snowfall approaching Vincennes...pushing northeast. Water vapor imagery is impressive this evening with an upper low found over MO and some dry air working into the system over Wrn TN...Wrn KY and SW Indiana. Best forcing is now pushing much farther north of Indiana across the southern Great Lakes. Radar trends still suggest the next few hours will continue with persistent snow and wind as we have seen the past few hours as the dry air and subsidence arrives across the region. Thus will expect another 1-2 more inches of snow as the last part of this system begins to depart. We have had reports and seen many pictures of significant drifting. This is expected to continue overnight particularly across more rural areas as the pressure gradient is expected to remain in place. Snow drifts of 2ft or more will be common...continuing to keep travel difficult. Ongoing Winter Storm warning will remain. && .SHORT TERM /Tuesday and Tuesday Night/... Issued at 247 PM EST Mon Feb 15 2021 Blowing snow will continue into the day tomorrow with lessening impacts later in the day as snow will have come to an end. The upper level system that brought all this snow will rapidly exit the area with a brief break in the winter weather through tomorrow and tomorrow night. With a thick snowpack, expect temperatures to struggle to break out out of the teens tomorrow before crashing into the low single digits to below zero tomorrow night with partly cloudy skies at the beginning of the night. Clouds though will increase towards sunrise which should limit the fall. && .LONG TERM /Wednesday through Monday/... Issued at 247 PM EST Mon Feb 15 2021 As the long term begins a longwave trough will be in place over the western plains with a broad upper ridge over the Atlantic. The trough will progress eastward, and as it does so, will pull a surface low out of the Gulf and bring it northeastward. The latest operational guidance shows a fair amount of variability with the surface low track, and this lowers overall confidence in the forecast for this system. The upper trough looks more broad than yesterday`s runs, and this should produce weaker but more prolonged forcing over the area. Isentropic lift moves into place Wednesday afternoon and could continue into Wednesday night, with access to a good feed of Gulf moisture on southerly 850 mb winds of 20 to 30 kts. Favorable jet streak dynamics may also be in play on Wednesday night, contributing additional upper forcing into the mix. On Thursday upper forcing in the way of q vector convergence will move through, there are indications in some solutions that a TROWAL could set up somewhere in the vicinity of Ohio or Indiana (although other solutions take the feature further north). At this time the best potential for heavy snow appears to be across the central and southeastern counties, and probabilistic output indicates greater than 30% chance for 6 inches of storm total snow by Friday morning across the southeastern counties. High pressure will slide through the area and bring dry weather with it Friday through Saturday night. Temperatures will remain below normal on Friday through Saturday with the snow pack in place and the base of the upper trough of cold air moving through. Wind chills Friday night/Saturday morning could again approach 10 below zero. A bit of a warm up will be possible starting Sunday. Could see temperatures climb above freezing at that time. Early indications are that another system could move through Sunday into Monday, so will include some low chances for precipitation then, but confidence is low given the variability in models that far out. && .AVIATION /Discussion for the 160000 Tafs/... Issued at 558 PM EST Mon Feb 15 2021 IMPACTS: IFR or worse conditions are expected for the next 6-9 hours. Improvement to VFR is expected by the end of the Taf Period. DISCUSSION: Radar Mosaics across the area show a large band of snow...limiting visibilities to 1/4 mile or less along with CIGS less than 1000ft stretching from the Taf sites across Southern IL to Western Kentucky. This precipitation is expected to continue to track to the northeast over the next 6 hours...resulting in a continuation of the IFR conditions. Deformation band set up is also possible which could result in some higher snowfall rates. HRRR remains on board lifting this precipitation across the forecast area through the next 6-8 hours...resulting in very poor flying conditions. As the Low and upper trough begin to exit the area overnight the precipitation should begin to end...leading to improving visibilities but plenty of MVFR to IFR CIGS will remain across the area as Time height and forecast soundings continue to reveal saturation within the lower levels. Subsidence and drying is depicted within the column as surface high pressure build across the area on Tuesday. Thus will expect a gradual return to VFR on Tuesday late morning. CONFIDENCE: High confidence for IFR conditions this evening and early overnight. && .IND WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 7 AM EST Tuesday for INZ021-028>031- 035>049-051>057-060>065-067>072. && $$ SYNOPSIS...White NEAR TERM...Puma SHORT TERM...White LONG TERM....CP AVIATION...JP
Area Forecast Discussion...CORRECTED
National Weather Service Chicago/Romeoville, IL
836 PM CST Mon Feb 15 2021 .UPDATE... 812 PM CST Not sure what`s left to be said that hasn`t already, but our remarkable snowstorm (considering the magnitude of the arctic airmass in place) is essentially heading into its peak at this time, with snowfall rates maximizing here probably through about midnight to 2 AM. The axis of steadiest snowfall has set up shop roughly east of a Mendota to McHenry line. Lake enhancement is and has been ongoing for a few hours with strong confluence noted with buoys showing northeast winds gusting to 30-35 mph, with northwesterlies just inland. The cooperative observer near Midway recently reported an exceptional 2.9 inches of snow in just about 100 minutes. Think the writing is on the wall at this point given radar trends that the jackpot area for this event will probably be 2-3 miles either side of a roughly Winnetka/Evanston to Midway line. When all is said an done (after lingering lake effect diminishes later tomorrow afternoon), imagine we`ll see a handful of snowfall reports pushing 20 inches in this corridor. The going forecast is in good shape, but did nudge overall amounts through the rest of the night upwards a bit based on recently- observed amounts and reported SLRs. With winds routinely gusting to around 25-30 mph, have also increased our blowing snow wording, especially near the immediate lakefront areas, as well as across more of our open/rural areas, with these effects most notable on east-west oriented roadways. Snowfall rates as a whole look to start diminishing towards 2-4 AM, with any snow of consequence ending across northwest and north-central portions of Illinois around/by daybreak. Steady lake-enhanced snowfall will likely continue through Tuesday morning, and may not full come to an end until early tomorrow evening, although rates during the afternoon will be considerable lower. No changes to the winter headlines at this time. The message is: don`t be out tonight unless it`s unavoidable. Updated products coming shortly. Carlaw && .SHORT TERM... 329 PM CST Through Tuesday night... Bottom line up front...Be prepared for a very messy evening commute, heavy snow tonight, with impacts expected to linger into the morning commute even though the heaviest snow will fall before daybreak Tuesday. Hazardous road conditions and low visibility will be the main concerns and will arrive very quickly late this afternoon and evening. This snow will hit hard and fast. This is certainly one heck of a system, and also impressive in the southern extent with readings in some areas over the Gulf of Mexico at or below freezing! Synoptic snow from the main storm system is knocking at our door as a strong upper level jet pushes into Indiana. This will place most of the area in the left exit region (and even some jet coupling from the northern stream jet) combined with significant upper level height falls will allow the still blossoming snow shield to spread in. Visibility values across most of the southern half of Illinois below three-quarters of mile, many areas much lower. Many areas upstream of here easily reached 6" of snow in the heart of this system. Expect the worst conditions tonight and into the early overnight hours. We will maintain a decent pressure gradient on the back side of the associated surface low, thus blowing snow will be a concern. It is still quite unusual to get such a high QPF system with these really cold temperatures, so the snow will fluffy and blow around easily, which has already occurred at O`hare and will become a higher concern in rural locations tonight. With regards to lake effect/lake enhancement, RAP forecast of convergence suggests that the main band across central Cook county, possibly smack dab between O`Hare and Midway (likely to include Midway airport) and will likely remain the focus of the lake band into this evening. Eventually it will become masked in the broader snow shield, but expect this only to further reduce visibility, with some locations earlier reporting visibility no more than a city block. And while wind chill values have "improved", values of 0 to minus 20, with the lowest readings west of the Chicago, are still significant, thus caution is urged if outside. We did decide that it was prudent to expand the Winter Weather Advisory through the remainder of the area as impacts should be similar across north central Illinois in spite of possibly slightly lower snow amounts. With this light snow, expect blowing snow concerns to linger in rural areas into Tuesday morning, thus we wanted to message this concern as well, along with the cold temperatures. So when will this all end? The main system snow should be done by daybreak in most areas, though it will be slower to exit near the lake. It should generally be shifting east of Chicago after mid- morning with the focus in northwest Indiana from mid morning onward. We envision that lake effect will linger across northwest Indiana longer than the current warning is in effect (9AM CST), so the night shift will need to assess whether we will need to extend this. Breezy northwest winds will continue the drifting snow for open areas most of the day. High pressure will shift into the area Tuesday night. We could drop temperatures pretty fast in the evening out ahead of any incoming mid level clouds. Ensemble guidance has areas in north central Illinois possibly getting down to -10F temperatures, with below zero lows likely area-wide. KMD && .LONG TERM... 329 PM CST Wednesday through Sunday... Majority of the previous shift discussion is still valid through the extended period: Focus in the extended forecast remains primarily on another synoptic snow-producing system Wednesday through Thursday night. Another mid-level wave rounds the base of the long wave upper trough over the western CONUS during the day Wednesday, which is progged to eventually lift out to the northeast cross the upper Ohio Valley and far eastern Great Lakes region through late Thursday. This continues to be a complex evolution involving a couple of northern stream disturbances within the trough across the upper Midwest, and as such continues to produce some spread in model solutions. The general consensus is that the surface low with this system will track from the Louisiana coast northeast into the upper Ohio upper Ohio Valley and eastern Lakes, with the heaviest QPF southeast of the forecast area through the Ohio Valley and eastern Lakes. The GFS/Canadian and their 00Z ensemble means continue to be slightly further to the northwest with the precip shield and higher amounts than the 00Z EC and EPS mean, similar to runs of 24 hours ago. NBM blended guidance continues to favor the southeast half of the WFO LOT cwa for higher pops Wednesday night into Thursday evening, and this remains reasonable at this time, with some accumulating snow fairly likely. Will of course need to continue to monitor this for a better handle on amounts/locations over the next couple of days. Guidance also continues to indicate some potential for lake effect snow across especially northwest IN as the system departs Thursday night into early Friday. Models depict a flattening of the overall pattern at the end of the week, as the deep trough associated with the mid-week storm progresses off to the east. Rising mid-level heights and surface high pressure are indicated across the area later Friday into Saturday, with the coldest 850 mb air also exiting off to the northeast. This would support a moderation in temperatures over the below-average conditions we`ve experienced of late. There`s also indications of another wave moving into the region Sunday, with some additional snow or rain/snow mix potential as temperatures warm. Ratzer && .AVIATION... For the 00Z TAFs... 557 PM...Primary forecast concerns include... Moderate/heavy snow through early Tuesday morning. Strong/gusty northerly winds with blowing snow tonight. A lake effect snow band extends from just east of ord/pwk to mdw. Visibilities are 1/4sm in this band and this lake effect band is likely to continue this evening as moderate snow spreads across the entire area. Still some uncertainty for exactly how fast the snow will taper off but high confidence for an improving trend by daybreak. There will likely still be some lake effect snow showers near ord/mdw at daybreak, possibly just east of those airports but once this shifts east, that should be the end of the snow with the rest of Tuesday dry, with perhaps some flurries. Northerly winds will gust into the mid 20kt range this evening and slowly diminish overnight. Wind directions at ord/mdw will likely fluctuation either side of north as the lake effect band drifts near those sites. Wind directions should favor north/ northwest Tuesday morning and then more northwest Tuesday afternoon/evening with speeds diminishing under 10kts with sunset Tuesday evening. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Winter Storm Warning...ILZ013-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033- ILZ039-ILZ106-ILZ107-ILZ108 until 9 AM Tuesday. Winter Storm Warning...ILZ006-ILZ103-ILZ104-ILZ105 until noon Tuesday. Winter Weather Advisory...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010- ILZ011-ILZ012-ILZ019 until 9 AM Tuesday. IN...Winter Storm Warning...INZ001-INZ002-INZ010-INZ011-INZ019 until 9 AM Tuesday. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
National Weather Service Raleigh NC
925 PM EST Mon Feb 15 2021 .SYNOPSIS... An area of low pressure and immediately preceding warm front will track from the Gulf of Mexico northward across the eastern Carolinas and middle Atlantic coast tonight. Cool high pressure will follow for Tuesday and Wednesday. && .NEAR TERM /THROUGH TONIGHT/... As of 925 PM Monday... Surface analysis show a 1003mb surface low near Morristown TN and associated wedge and warm fronts drape south and east across SC and GA, respectively, while 00Z regional raobs show the strong CAD inversion from GSO to MHX. Radar imagery suggests one MCV moving through the foothills, with another over central SC in closer proximity to airmass boundaries, which should be where the secondary wave of low pressure begins to track toward the eastern Piedmont and coastal plain overnight. There has been a very slow north/northwestward mixing of the warm sector airmass, with 60F dewpoints barely into the Savannah River Basin as of 01Z. An area of showers extends from the western Piedmont south through the GA coast, with pockets of fairly impressive lightning frequency, suggest elevated CAPE above the LLJ and warm nose. As expected the intensity of these storms has waned as they move north and become more elevated. The window for any near surface based convection still looks very short centered around 06Z when 60F dewpoints make a run at the southern coastal plain, and recent HRRR runs have shown a southeastward trend wrt stronger surface-based convection. As such, there is not much to changed in the current forecast, as observed trends have matched pretty well. There could be some concern for isolated flooding in the coastal plain urban areas where better convective rates could develop, but it appears the line of convection is moving a decent clip and should limit QPF to less than 0.75" on average. -bls Previous discussion: Thanks to ongoing CAD, low clouds, fog and drizzle will persist through the evening. Then we turn our attention to the low pressure center moving up out of the northern GOM and across the NC Piedmont overnight tonight...accompanied by strengthening winds aloft ahead of the short wave trough lifting NE across the Miss and OH Valleys. The latest CAMs continue to depict rain showers, some with heavy downpours, overspreading and sweeping across central NC from west to east between 03Z and 09Z tonight. While the CAD and cool near-sfc layer will hold firm across the region west of the US-1 corridor (which is coincident with the track of the sfc low), forecast soundings show the potential for at least some elevated instability, and given the increasing deep layer bulk shear in excess of 50kts, we can`t rule out some elevated thunder with hail being the main concern, particularly from US-1 eastward. East of the low track (basically east the US-1 corridor)...sfc temps will climb pretty quickly after 04z, but even still, enough of a low level inversion will persist to preclude a sfc connection to instability. Rather, it appears that the only place where a sfc connection could be established is near the immediate coast. Nevertheless, it`s a vigorous system, so heavy downpours, a few gusty thunderstorms east of US-1, and potentially one or two with some large hail, is a possibility overnight. Temps tonight will hold steady west of US-1 and rise east of US-1 as the sfc low lifts north. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... As of 304 PM Monday... The showers and tstms will be pushing off the east coast by 12 or 13Z. Behind that, low clouds will be slow to erode across the western Piedmont and Triad since the existing CAD airmass will still be in place (given the low passing by the east). However, from US-1 east, clouds should begin to thin out before noon and there may even be some sunshine by afternoon. Even across the Triad, some sun may break out by mid-late afternoon. Otherwise, CAA in the low levels will result in steep lapse rates in that layer, so it will become rather breezy if not windy at times thanks to good momentum transfer below H9. Frequent wind gusts up around 20kt can be expected during the daytime Tuesday. The steep low level lapse rates may also manifest in some stratocu up around H8 by mid to late afternoon, so any clearing in the early afternoon may be short-lived. With CAA underway, temps will slowly fall during the day through the 50s and 40s (or simply remaining in the 40s across the Triad), then continue to fall Tuesday night under mostly clear skies and lighter winds. Lows Tuesday night from the mid 20s NW to around 30 SE. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... As of 415 PM Monday... Wednesday will be a welcomed dry day with partly sunny skies as high pressure noses in from the north over SE Canada. This CAD regime will result in well-below-normal temperatures, and leaned toward the cooler NAM with highs in the 40s across the area. This dryness will be short-lived, however, as yet another shortwave trough digs south into the southern Plains on Wednesday night and moves into the Deep South on Thursday. At the surface, a low pressure system will develop along the Gulf Coast and move northeast along a quasi- stationary frontal boundary, with another low developing off the Mid- Atlantic coast. This will bring more widespread precipitation to central NC from Wednesday night into Friday morning. The heaviest precipitation will likely come in two rounds, the first being from isentropic lift overnight Wednesday night into Thursday morning, and confidence continues to be high enough for categorical POPs. Confluence between the approaching upper trough and the weakened polar vortex over SE Canada will keep the ~1035 mb mb surface high in place over New England during this period, which looks increasingly likely to result in temperatures just cold enough (30- 32F) for a period of freezing rain in the far northern Piedmont on Thursday morning. The main threat area appears to be similar to the last event, along and north of I-85. Elsewhere only rain is expected. Models still show the high pressure system then retreating north, which will result in temperatures rising above freezing everywhere by late morning Thursday and only liquid precipitation for the rest of the event. The good news is the above-freezing temperatures combined with plenty more precipitation should help to melt whatever ice does accrue in the far north. A warm front with a very sharp temperature gradient (60s to the south and 30s-40s to the north) will try to lift into the area, which makes for a challenging temperature forecast on Thursday. As is often the case, the cold dense air at the surface will likely be very difficult to scour out, and both the GFS and ECMWF continue to trend colder for Thursday. The 12z NAM actually trended warmer and brings the wedge boundary well north into the area, but this is not supported by other guidance and continue to lean toward the colder solutions at this time, with the boundary not getting past the Coastal Plain. Precipitation coverage should lessen somewhat during the day Thursday, especially in the far south and east. While deep-layer shear looks quite prolific (60-80 kts), continue to leave out any mention of thunder at this time with the cooler trend of most model guidance and the likely lack of enough instability. Any convection if it were to develop would be elevated with the best chance in the far south and east. Another band of heavier rain associated with a cold front will then move through from west to east Thursday night into early Friday morning. Total forecast precipitation from the system is currently one and a half to two inches across central NC, highest north where the strongest 500 mb height falls will be. This would be enough for more flooding issues especially with rivers and streams already running high. Westerly flow behind the cold front will result in rapidly decreasing rain chances and clearing skies from west to east on Friday morning and afternoon. High pressure will finally result in some dry weather and clear skies for the weekend. Saturday will be cooler than normal with highs in the 40s and lows in the 20s, before the high moves offshore on Sunday and Monday resulting in temperatures moderating into the 50s. Both the GFS and ECMWF are in good agreement that the next shortwave trough will move into the Great Lakes on Monday, with a trailing cold front bringing precipitation to the area, so introduced low chance POPs on Monday. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... As of 700 PM Monday... LIFR conditions will hold across most of central NC overnight owing to a strong wedge airmass in place. Showers associated with a low pressure system that will track across the eastern Piedmont and coastal plain have begun to move into the vicinity of GSO/INT as of 00Z, and these will shift east overnight, with a thunderstorm possible at any site between 02-08Z, earlier at GSO/INT and later at RDU/FAY/RWI. However, the probability of strong winds in the storms is low, especially at GSO/INT/RDU. In the wake of the departing showers and storms early Tuesday, low clouds an LIFR to IFR conditions will linger through at least mid- morning, and potentially into the early afternoon at GSO/INT, with westerly winds slowly eroding the low clouds and eventually gusting to 20-25kt during the afternoon. Outlook: VFR conditions may briefly return for Wednesday, before the next weather system approaches Wednesday night, bringing another round of IFR or less flt conditions Thursday through early Friday. Also note the possibly of freezing rain at INT/GSO late Wed night through mid-day Thursday, before changing to rain. Flight conditions should improve again late Friday and Saturday. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ NEAR SHORT LONG TERM...Danco AVIATION...bls/mp
Area Forecast Discussion
National Weather Service Blacksburg VA
957 PM EST Mon Feb 15 2021 .SYNOPSIS... Low pressure will move across the southeast tonight giving us mainly rain. Colder high pressure builds in behind this system Tuesday, followed by another winter storm impacting us by Wednesday night.Drier conditions are expected to return for the weekend ahead. && .NEAR TERM /THROUGH TUESDAY/... As of 930 PM EST Monday... ...Some rumbles of thunder overnight give way to breezy conditions and some breaks of sun for some Tuesday... Subtle changes in regards to temperatures, precipitation chances ,winds, and visibility for the overnight period. Heaviest rain and a few rumbles of thunder have been confined in and east of the Blue Ridge Parkway this evening. Waves of moisture continue to funnel in from the south out of Greensboro-Winston Salem as our storm system quickly lifts north. Not much wind can be found so far with any of our rain despite a jet core humming along at 30- 60 knots 4000-7000 feet off the surface. Some gusty winds of 20-40 mph have been noted in elevations above 3500 feet with an occasional gusts upwards of 50 mph across the highest peaks of the North Carolina mountains this evening. Any winds will slowly subside after midnight once the system passes before re-energizing again late Tuesday morning into Tuesday afternoon as the pressure gradient tightens. As for precipitation expect any moderate rain to slowly taper during the wee hours of Tuesday morning east of the Blue Ridge. Some freezing rain may also mix along the parkway leading to a light glaze although impacts look to be minimal. Elsewhere around the region light rain, drizzle, mist, and low clouds will linger into the early morning commute so allow some extra time heading off to work and school. Some fog may also be out there as well but with winds picking up late in the mid morning period that may not be likely. Hi-res guidance along with model soundings also seem to be on that point of thinking for the early morning period. A westerly component to the wind means that many locations from Roanoke to Lynchburg back south to Blacksburg and Danville may actually see that giant orange ball know as the sun pop out in the skies tomorrow. Downsloping will be in play which will allow us to scrub out some of the gray and gloom for a little blue above. It won`t be all that much but maybe just enough to force highs into the mid to upper 40s along the Blue Ridge with low to mid 50s over the Piedmont/Southside. Further west the colder air will remain entrenched with highs in the mid to upper 30s and low 40s underneath more of those gray skies. Confidence remains average to above average in the near term. As of 530 PM EST Monday... Heavy rain moves in this evening/tonight with a brief dry stretch and some hints of sunshine for some Tuesday.. Minor changes in regards to precipitation timing and winds this evening as our next weather maker moves. A nice band of moderate to heavy rain is already showing up on radar from Cincinnati, Ohio back south to , Tennessee. This band will continue to pivot north and east into our region tonight giving us once again another night of miserable weather conditions. Out ahead of this band winds have been gusting 15-30 mph with a good downsloping effect along our western facing slopes warming temps in Richlands toward 50 degrees. Further east the air is lot cooler/stabler with temps 33-37 degrees under a layer of dense fog. The fog should scrub out once the rain overspreads the area from west to east between 7pm-9pm this evening. Even with that said expect pockets of poor visibility to continue through the overnight hours with extra ponding on the roadways. The heaviest rain looks to remain in two corridors one against the western facing slopes with the low crossing along the Ohio River and the other out over the Piedmont with the main surface low pushing up through the central NC/eastern VA into the Delmarva by early Tuesday morning. Rainfall amounts will be on the order of a quarter of an inch to half an inch west of the I-81 corridor with a half an inch to one inch along the crest of Blue Ridge points east into the Piedmont. Locally heavier amounts are possible from the North Carolina Piedmont points north along and east of US-29 corridor where even a little thunder cannot be ruled out thanks to some elevated instability due in part to bulk deep layer shear values humming between 30-50 knots. Flooding does not look to be a concern with this event with the exception of a few poor drainage areas maybe running into some issues. We will continue to keep an eye on the Dan river though at South Boston which crested below minor flood stage earlier today based upon the heavy precip set to move in. Any wintry weather this evening will remain north of the I-64 corridor and along the Blue Ridge Parkway where a period of light freezing rain could occur. Accumulations will be less than a few one hundreths in these locations so no advisories have been issued at this time but a mention has been made in the HWO. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 230 PM EST Monday... Another winter storm may bring an icy mess starting Wednesday night. Upslope snow showers will linger across western Greenbrier County on Tuesday night but should eventually fade by Wednesday morning. High pressure should cross over the southern Great Lakes on Wednesday to bring drier conditions. However, it will wedge southward along the eastern slopes of the Appalachian Mountains by Wednesday afternoon into Wednesday night. Meanwhile, a low pressure system should organize over the Gulf Coast and move northeastward toward the Mid Atlantic. A deep upper level trough will crave itself over the central Plains, while an upper level ridge persists off the East Coast. As a result, the moisture fetch from the Gulf of Mexico will ensue on Wednesday night and persist through Thursday night. It almost looks like a repeat of the ice storm experienced this past Sunday with all the models showing a strong warm nose lifting northward over a cold wedge of high pressure in the lowest layers of the atmosphere. The biggest difference this time is that the high will be in a more ideal location to promote wedging as it will be centered over New York on Wednesday night. Precipitation may start as a mix of snow and sleet along and west of the Blue Ridge with rain changing over to a wintry mix in the Piedmont. By Thursday, most locations may see freezing rain as model soundings show the warm nose reaching up to +10 C by the afternoon. The ice accumulations appear noteworthy, which is a significant concern given how much the Virginia Piedmont is still recovering from the previous ice storm with downed trees and power lines. The freezing rain will slowly change to rain from south to north as surface temperatures struggle to climb above freezing during Thursday afternoon. However, some of the moisture could turn back into sleet or snow as colder air arrives from the northwest on Thursday night. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 230 PM EST Monday... Mountain snow showers, gusty winds, and cold air will persist through Friday and Saturday. Cold air behind the departing low pressure system will arrive by Friday morning. Winds will become gusty from the northwest, and upslope snow showers should crank up along a line from Boone to Lewisburg. Meanwhile, conditions should become dry across the Piedmont. The ECMWF and the GFS models agree on keeping the gusty winds and mountain snow showers through Friday night into early Saturday. Temperatures were steered toward the colder side of guidance, and there may be a few locations testing wind chill advisory criteria by Saturday morning. High pressure will build overhead on Saturday afternoon, which should allow the gusty winds and the mountain snow showers to gradually diminish. With high pressure in control by Saturday night, our weather will finally turn tranquil after an extremely active and wet week. Sunday should see the flow turn around to the southwest, so temperatures could turn somewhat milder as the upper level pattern flattens. By Sunday night, a shortwave trough will cross over the central Plains and approach the Mid Atlantic by Monday morning. A weak low pressure system associated with this trough should bring the next chance of precipitation. This system should exit offshore on Monday evening. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... As of 717 PM EST Monday... Light to moderate rain will continue to overspread much of the area this evening as an area of low pressure and it`s aforementioned front move through. Areas west of KBLF, KBKW, and KLWB look to see ice from this system while areas east of KAVL, KCLT, KGSO, and KDAN look to see thunderstorms. This has been noted on the current radar east of KCLT where several lightning strikes have occurred in the last hour or so. With that said have opted to leave a tempo group out for TSRA at KDAN at this time but may reevaluate based on radar trends in the coming hours. Elsewhere it`s predominantly IFR to LIFR cigs/vsbys especially out over the mountains as our system moves moves through. As for icing concerns they look to remain minimal. KLWB may see some according to the hi-res soundings between now and 6z Tuesday otherwise most of the icing will remain from KCRW, KHTS, and KEKN points west along with the crest of the Blue Ridge Parkway. Low level wind shear will remain an issue through the early evening hours according to the NAM nest and HRRR for KBLF, KLWB, and KTNB before settling down after 6z Tuesday as the low level jet core passes. Improving conditions for our Tuesday at all the TAF sites although winds will remain gusty out the west at 10-20 knots. Some upslope snow showers may also be noted Tuesday morning into Tuesday afternoon west of KLWB and KBLF but do not look to provide any major impacts at these TAF locations at this time. Elsewhere expect a MVFR conditions with some brief periods of VFR cigs/vsbys at KROA, KLYH, and KDAN by Tuesday afternoon. Above average confidence for ceilings, wind, weather. Average to slightly below average confidence on visibility and concern for thunder. Extended Aviation Discussion... Weather pattern is forecast to remain unsettled through Friday with increasing threat for wintry precipitation Wed night-Friday as Arctic air surges further southeast into the eastern United States. Generally MVFR or worse conditions expected through most of the entire period. && .EQUIPMENT... The KFCX radar will be down through about Thursday, February 18 for the replacement of a generator as well as other electrical components powering the facility. In addition, the Richlands NOAA weather radio broadcast will be off the air through at least Tuesday, February 16 due to phone line problems. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...ET/WP NEAR TERM...ET SHORT TERM...PW LONG TERM...PW AVIATION...ET/WP EQUIPMENT...PW