Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/23/19

Area Forecast Discussion
National Weather Service Denver/Boulder CO
849 PM MST Fri Feb 22 2019 .UPDATE... Issued at 842 PM MST Fri Feb 22 2019 Heaviest band of snow is shifting slowly southeast and roughly along a line from Fort Morgan to Denver. Snowfall rates of 2"-3" per hour have occurred in some areas with up to 6" in portions of Denver. Another few inches may fall in Denver but will keep advisory in place an not upgrade to a warning since heaviest bands are shifting southeast. Meanwhile have decided to upgrade areas from Akron to Limon eastward to a warning as heavy snow will spread into these areas overnight and continue into Sat morning. Winds will also increase late tonight through sat morning with quite a bit of blowing snow as well. UPDATE Issued at 546 PM MST Fri Feb 22 2019 Banded snow is increasing southeast of Greeley to Boulder line extending into the srn Foothills. At some point these seperate bands will likely form into one area of heavier snow over the Denver area and then move east and southeast across the plains late this evening and overnight. Appears now amounts in the nrn Foothills and northern areas of the I-25 urban corridor to the WY border will not see much snow. Thus will likey have to adjust highlights by mid evening. && .SHORT TERM...(This evening through Saturday) Issued at 255 PM MST Fri Feb 22 2019 A digging trough is seen on water vapor satellite with a warm conveyor belt extending from the Gulf of California to western Colorado. Underneath this conveyor belt, moderate to heavy precipitation has been reported across the Desert Southwest. At the surface, a cyclone has developed near Centennial with clearing to the south and east and with low clouds and fog to the northeast of the cyclone. Visible satellite and radar indicate snow showers developing over the north central mountains and increasing in coverage and intensity. An analysis of model sounding data shows that there are good mid level lapse rates which may lead to upright convection in the mountain showers this afternoon. These showers will continue to develop and will move eastward over the urban corridor and eastern plains late this afternoon and evening. While there are weaker lapse rates over the plains, model cross sections indicate the potential for CSI to be released this evening. Since there is a considerable amount of upright and/or slantwise instability within the atmosphere this afternoon and evening, the potential exists for strong bands of snow to develop with snowfall rates of up to 1.5 inches per hour. Individual model runs are all over the place on where these heavy bands will setup so there is low to medium confidence in snowfall amounts at any particular location across the urban corridor and eastern plains. With that being said, 2 to 6 inches is still expected over the urban corridor and eastern plains and the message of the Winter Weather Advisory remains the same, that there will be hazardous travel conditions underneath the snow bands during the commute this evening. One potential area that may have a higher potential to see a snow band impact the evening commute is Estes Park, Fort Collins and Loveland. This is because a band that is currently aligned over the higher mountains from western Summit County to southern Larimer County will move northeastward toward the aforementioned areas. This is supported by recent HRRR and RAP solutions as well as the increase in radar reflectivities. Storm total snowfall is not expected to be above the 2 to 6 inch forecast in these areas, however, because during the rest of the event, downslope flow will hinder snowfall rates. An area of potentially higher storm total snowfall amounts is the Palmer Divide. An initial band of snow may move through that area shortly after 00Z and then strong upslope flow with ascent aloft will enhance snowfall throughout the rest of the event. If the initial band does setup over the Palmer Divide, there is potential to see amounts above 6 inches which could require an upgrade to a Winter Storm Warning. The evening shift will monitor the potential for an upgrade there. Tomorrow morning, the snow will depart the eastern plains and then mainly dry conditions are expected the rest of the day. Strong wind gusts are expected over the eastern plains and Cheyenne Ridge with gusts up to 50 mph possible. .LONG TERM...(Saturday night through Friday) Issued at 255 PM MST Fri Feb 22 2019 Colorado will be under the influence of a zonal flow aloft through much of the period which should result in dry and warmer weather across north central and northeastern Colorado through Thursday. There may be enough moisture to produce isolated to scattered light snow showers across the high country at times with the best chance Saturday night and Thursday. The plains should see dry weather with temperatures at or above normal values. The far northeast plains may see breezy conditions Sunday evening due to the pressure gradient between the northern plains states and Colorado. Tuesday and Thursday look to be the warmest days of the week due to some weak ridging. Thursday night into Friday there are some inconsistencies in the models. The GFS has an upper level trough moving across the central and northern Rockies with a 140+KT upper jet over southern Colorado. The ECMWF and GEM show no such ridge, and has Colorado under the influence of a moderate to strong northwesterly flow aloft. Despite the differences, either solution could produce accumulating snow in the mountains and colder unsettled weather across the plains. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 842 PM MST Fri Feb 22 2019 Heaviest snow has moved se of DIA but light to moderate snow will continue for a few more hours with additional accumulations up to 2". Snow should begin to decrease by midnight. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 11 AM MST Saturday for COZ048-050- 051. Winter Weather Advisory until 2 AM MST Saturday for COZ034. Winter Weather Advisory until 8 AM MST Saturday for COZ036- 039>045. Winter Storm Warning until 11 AM MST Saturday for COZ046-047-049. && $$ UPDATE...RPK SHORT TERM...Danielson LONG TERM...Kalina AVIATION...RPK
Area Forecast Discussion
National Weather Service Des Moines IA
716 PM CST Fri Feb 22 2019 .UPDATE... Issued at 716 PM CST Fri Feb 22 2019 Updated WW.Y to begin now over portions of southwest, west, and south central as light freezing rain already beginning. With warm air advection advancing north, this area will gradually drift north and expand between now and 9 pm. The far northern counties remain dry for the next 1.5 to 2 have left the start time along the northern 2-tier Iowa counties at 9 pm. Roads already seeing some icing on 141 around Dedham, Iowa near Coon Rapids on the IDOT page this evening. Remainder of the headlines are the same as afternoon issuance. /rev && .SHORT TERM.../Tonight through Saturday/ Issued at 419 PM CST Fri Feb 22 2019 Confidence On Storm Tonight Through Sunday: High on freezing drizzle/rain tonight. Medium to high on temperatures which could allow temperatures to warm faster than anticipated resulting in less icing especially on the southern edge of the advisory area tonight. Medium to high on the storm track. Slight chances could change the track of the heaviest snow for Saturday night. High on timing of changeover to snow and strong gusty winds/blizzard conditions Saturday night. Medium to high on blizzard conditions continuing into Sunday. With the lack of falling snow, visibility restrictions may still be less than 1 mile in rural areas, but widespread blizzard conditions are still somewhat uncertain. Very strong and potent storm system still on tap to impact the state through Sunday. Currently the upper level system is located over the desert southwest and is expected to quickly lift northeastward through the region Saturday, with the surface low to track across southeast Iowa Saturday afternoon into southern Wisconsin by Saturday night. Strong and gusty winds aloft to allow moisture to surge northward into the state tonight and continue through Saturday. Low level isentropic plots show low level moisture increasing and isentropic lift increasing tonight so expect precipitation to begin to spread into the forecast area by mid evening. Strong WAA and moisture moving in overnight with instability will allow freezing drizzle to change over to freezing rain across central/north central Iowa late tonight. The strong push of moisture to also push dewpoints up and expect much of the south to change over to all rain and some isolated to scattered thunderstorms possible with MUCAPE values around 100 J/Kg late tonight in the southeast. Further north, heavier freezing rain still possible but rain rates should allow most of the freezing rain to runoff limiting icing to maybe a tenth to as much as two tenths in spots along the Hwy 30/Hwy 20 corridors. Surface temperatures continue to warm into Saturday with much of the forecast area changing over to all rain as thermal profiles rise to freezing or above. Tried to time precip chances toward the HRRR with a decent handle on the waves of precip with as the WAA wing of precip moves in through Saturday. Trowal feature aloft to result in a heavy band of snow across the north/northwest/west central toward late Saturday afternoon into Saturday evening, with a quick 4 to 6 inches of snow becoming widespread and narrow band of 8 to possibly as high as 10 inches possible. Latest storm track indications suggest the band may orient itself from around the Carroll area up through Fort Dodge into the Mason City area. Small changes in the track of the system not likely known until Saturday could cause this heavier band of snow and ultimately the entire higher accumulations of snow to still shift some. The northern side of the band of snow will be have a tighter gradient due to drier air moving in from the back of the system, and the southern edge will have a gradient providing even more uncertainty due to the storm track and the orientation or more rain/snow and timing the changeover. Therefore some solutions are starting to place more the heavier snowfall toward the DSM metro area and areas to the north. Therefore some adjustments to the headlines are still possible moving into Saturday. Little changes with the wind forecast for Saturday night into Sunday. Therefore have tried to place the Blizzard Warning in the area where the best chances of 4+ inches of snow expected with the Winter Weather Advisory in areas of accumulating snowfall. Some question as to the extent of blizzard conditions into Sunday given the falling snow will have ended and relying solely on lofted blowing snow. Given much of the snow more likely to be a heavier, wet snow the blowing snow potential may be somewhat limited on Sunday, allowing visibility restrictions to not be as bad as expected (i.e. less than a mile or half mile versus true blizzard conditions less than 1/4 mile or zero Sunday). Therefore have the blizzard warning continuing into Sunday, but could see some of this maybe adjust based on observations into Sunday and how the blowing snow materializes. Expanded the advisory for tonight given the areas of icing, and went with the advisory across the north tonight through Saturday for the potential of freezing drizzle through the morning and then the snow starting up Saturday afternoon before the winds really pick up by Saturday evening transitioning to the Blizzard Warning. .LONG TERM.../Saturday night through Friday/ Issued at 419 PM CST Fri Feb 22 2019 .Overview: Temperatures will be below normal through this next week, especially Monday through Wednesday. Periodic chances for light snow are expected Monday through early Wednesday and perhaps again late this week. Details: Pressure gradient will be weakening across the state allowing for winds to decrease and blowing and drifting snow to end Sunday evening. Surface high pressure will try to nose into the state on Monday, but some uncertainty on whether any light snow will occur. With weak warm air advection ongoing, the NAM and GFS saturate the low and mid-levels per cross sections and soundings. Meanwhile, the ECMWF cross sections show some drier air in low levels. At this time, the best agreement for location of any light snow will be over northern Iowa and that is where PoPs are the highest. If precipitation does occur, there could be some freezing drizzle on the southern periphery as drier air works into the ice introduction layer. Given uncertainty about occurrence of precipitation, will keep all snow for now. A better surge of isentropic lift/warm air advection is expected to develop late Monday into early Tuesday that will spread light snow across the forecast area. Trends have taken this snowfall farther northward with the exception of the Canadian. Temperatures the first part of next week will be well below normal with high temperatures averaging 15 to 20 degrees below normal and low temperatures around 15 degrees below normal. By the middle to latter part of this next week, differences in deterministic runs is above average, especially late this week, with poor model run to run consistency. By Wednesday morning, the CMC and GFS are more zonal while the ECMWF is a bit more amplified across the CONUS. Significant differences revolve around the handling of an upper low pressure near/off the Pacific Northwest late this week. The GFS charges southeastward and develops a mature cyclone as is swoops south of the state and then heads into the Great Lakes. Meanwhile, the CMC and ECMWF are delayed with the low`s eastward movement. Therefore, late this week have held to model blend. && .AVIATION.../For the 00Z TAFS through 00Z Saturday evening/ Issued at 554 PM CST Fri Feb 22 2019 Light -fzdz/fzra entering northwest Iowa now with VFR cigs beginning to drop to MVFR. Trends general downhill from 00z onward as cigs lower to MVFR/IFR over northwest/central between 03-06z. Light -fzra mixed with PL will occur north sites and briefly central between 03z to around 09z KDSM while southeast KOTM should escape any freezing rain. Will be monitoring for convection. Have mentioned at both KDSM/KOTM between 09z to 15z. Rain likely south Saturday most of remainder of period aft 09z while north/northwest sites see changeover to -SN aft 21z. Looking ahead: Strong NW winds arrive northwest aft 00z Sun...spreading southeast. Likely to cause visby under 1/4sm northwest/north areas. /rev && .HYDROLOGY... Issued at 419 PM CST Fri Feb 22 2019 Complex hydrologic situation continues likely this weekend. Combination of warm temperatures along with rain...possibly heavy...will lead to significant snowmelt especially across the southeastern CWA. This rain plus snowmelt will lead to significant runoff into area streams which may result in flooding. Ice jams are also possible if enough runoff makes its way into the streams. && .DMX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 9 AM CST Saturday for IAZ026-036- 037-047-048-058>060-070>073. Winter Weather Advisory from 6 PM Saturday to 6 PM CST Sunday for IAZ027-028-038-039-048>050-059>061-071>073-081>083-092-093. Winter Weather Advisory until 6 PM CST Saturday for IAZ023>025- 033>035-044>046-057. Blizzard Warning from 6 PM Saturday to 6 PM CST Sunday for IAZ004>007-015>017-023>026-033>037-044>047-057-058-070. Winter Weather Advisory until 9 AM CST Saturday for IAZ027-028- 038-039-049-050-061-062. Winter Weather Advisory until 6 PM CST Saturday for IAZ004>007- 015>017. && $$ UPDATE...REV SHORT TERM...Beerends LONG TERM...Ansorge AVIATION...REV HYDROLOGY...Zogg
Area Forecast Discussion
National Weather Service Hastings NE
539 PM CST Fri Feb 22 2019 .SHORT TERM...(This evening through Saturday evening) Issued at 352 PM CST Fri Feb 22 2019 Main concern is precip tonight from isentropic lift, ahead of the powerful winter storm, and then the storm itself as it comes through Saturday. Some leftover convective snow continues to head north northeast this afternoon as soundings indicate that we will soon lose our dendritic growth layer in mid-levels that will promote freezing drizzle for most of the CWA tonight. The lowest confidence will be in our far southeast where it may be just above freezing. However, the HRRR and CONSShort hits us fairly hard with fog tonight, so with locally dense fog a factor, I figured it would be prudent to go ahead and throw everybody into an advisory for tonight into 15Z Saturday as temperatures approach dewpoints and low-level moisture flux increases. In our south, we may even get some legitimate light rain or light freezing rain as our maximum temperature aloft will be a bit warmer there. As for storm track on Saturday, I still favor the consistent ECMWF. The GFS is stubbornly farther north, but the overall band that it produces has sagged south. The 18Z NAM solution is slightly farther north than the ECMWF, with an added smaller-scale band over the tri-cities. I prefer the stability of the ECMWF ensemble means, which puts the heaviest band of snow over our southeastern CWA. Convection tomorrow may rob us of expected return flow, and I suspect that we don`t want to get much more than the 4 to 6 inch amounts that we currently have going, with an occasional 7 incher thrown in there. Even the 12Z ECMWF ensemble means have scaled back snow amounts from the previous forecast, but keeps the track nearly the same as previous solutions. Strong 850 mb winds leave no doubt that the wind will howl on Saturday, as wind speeds of 50 to 55 kts should help get wind gusts to 45 mph and above. With wind this strong, it would only take a few inches for blizzard conditions to develop, hence the Blizzard warning in roughly the southeastern third of the CWA. Kept an Winter Weather Advisory going for the rest of the CWA with a solid 1 to 3 inches in the forecast, and with blowing wind like we will have, this would be a solid advisory (granted that we get some snow). The freezing drizzle tonight should help cut down on blowing snow that is already on the ground. Precip type should transition from freezing drizzle to perhaps some sleet to snow by Saturday afternoon for most areas. This system still looks like it moves right along, so by Saturday evening, precip will wind down, and wind speeds will eventually let up noticeably by midnight. The Advisory/Blizzard goes until midnight due to continued blowing snow as it takes the wind awhile to decrease sufficiently. .LONG TERM...(Sunday through Friday) Issued at 352 PM CST Fri Feb 22 2019 Maybe a little snow possible with another wave come Thursday night into Friday next week, and perhaps a blip come late Monday night, but less of a chance. Kept it cold for the rest of the forecast, and in fact for most days I lowered high temperatures from Superblend and favored a combination of ECMWF/CONSRaw/CONSAll, or at least went in that direction based on the stubborn cold pattern that we are in. Since we are so anomalously cold, Superblend relies too much on climatology in outer periods, as well as the fact we have snow cover on the ground. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday) Issued at 533 PM CST Fri Feb 22 2019 Forecast is a challenge. Much of the night should have some fog and freezing drizzle at times. There could be a little lull in the morning before snow spreads into the area along with gusty winds which could cause blowing snow and reduced visibilities. A slight improvement is expected at the very end of the period. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Winter Weather Advisory until 9 AM CST Saturday for NEZ064-076- 077-085>087. Blizzard Warning from 9 AM Saturday to midnight CST Saturday night for NEZ064-076-077-085>087. Winter Weather Advisory until midnight CST Saturday night for NEZ039>041-046>049-060>063-072>075-082>084. KS...Winter Weather Advisory until 9 AM CST Saturday for KSZ005>007- 017>019. Blizzard Warning from 9 AM Saturday to midnight CST Saturday night for KSZ005>007-017>019. && $$ SHORT TERM...Heinlein LONG TERM...Heinlein AVIATION...JCB
Area Forecast Discussion
National Weather Service Green Bay WI
559 PM CST Fri Feb 22 2019 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Saturday Issued at 210 PM CST Fri Feb 22 2019 The latest RAP analysis and satellite/radar imagery show high pressure stretching from the northern Mississippi Valley to the eastern Great Lakes early this afternoon. Meanwhile, light snow is occurring from northern Kansas into North Dakota within a warm advection zone and ahead of shortwave troughing moving over the Rockies. The primary system remains in the base of the trough located over the desert southwest. However, cloud cover is shifting northeast into Minnesota and Iowa and poised to move into Wisconsin later today. As warmer air aloft surges into the state tonight into Saturday, potential snow and ice accumulations are the main forecast concerns. Tonight...Clouds will continue to increase from the southwest and lower at the same time as warm advection aloft moves from west to east across the state. With increasing mid-level moisture transport and decreasing stability, many of the higher resolution models indicate a band of light snow surging northeast across north-central WI after 09z. Meanwhile, guidance has slowed down the arrival of the snow into central WI almost to 12z Sunday. Therefore lowered accumulations some across the I-39/Hwy 51 corridor, where a half inch to an inch of accumulations will be possible by 6 am Saturday. Temps will most likely steady out in the evening before warming a few degrees overnight, particularly over eastern WI where wind directions will become east off Lake Michigan. Saturday...Precipitation will slowly shift east during the morning, though models indicate low level dry air will hold off precipitation arriving over eastern WI until 15z or later. Precip should be mainly snow until this time, before warmer air aloft starts to invade from the south to north across central to northeast WI. This will lead to an increasing threat of freezing rain particularly over central WI and the southern Fox Valley by mid to late morning. Because temps start to approach freezing, and the road temperature forecast calls for readings to warm above freezing after around 10 am, the warming temperatures will mitigate the risk of freezing rain somewhat. Higher uncertainty will be over east-central WI due to the expected later arrival of the precip. The freezing rain/drizzle threat may not ramp up until late morning or early afternoon across northern WI where temps struggle to reach the freezing mark. Models, in general, increased qpf through the day, which increases the threat of hazardous travel. Due to the potential for 1-3 inches of snow and some ice accumulations, will issue a winter weather advisory for the morning for central WI, and from late tonight through the afternoon for northern WI. .LONG TERM...Saturday Night Through Friday Issued at 210 PM CST Fri Feb 22 2019 Once our main storm departs Sunday night, the main story for next week will be the well-below normal temperatures as an upper high builds toward Alaska and displaces a chunk of arctic air southward into the northern Plains/Great Lakes. Snow chances next week appear confined to Tuesday/Tuesday night with the passage of a weak clipper to our south and perhaps next Friday with a stronger system moving through the Great Lakes. Surface low is forecast to lift northeast into central or east- central WI Saturday evening and intensify in the process as the accompanying negatively-tilted shortwave trough moves across the Midwest. Besides strong lift from the deepening surface low, northeast WI to reside in the favorable left exit region of the upper jet for additional lift. Moisture will not be a problem with models showing PW values of 0.50 to 0.75" which is about 200 percent of normal. In the mid-levels, models are indicating strong Q-G forcing over the entire forecast area, while the strongest frontogenetical forcing exists across northern/parts of central WI. Thermal profiles show enough warm air across east-central WI to keep precipitation as all rain, while north-central WI to be all snow with a wintry mix in between. By later Saturday night, the surface low tracks toward eastern sections of Upper MI with snow everywhere except east-central WI where the wintry mix to be located. Snow accumulations by daybreak to range from 2 to 5" central/far northeast WI, 6-9 inches north-central WI. Due to impending headlines for Saturday, prefer to hold on to the winter storm watch for now to avoid additional headlines with the caveat that winter storm warnings will eventually be needed. Snow will continue Sunday morning as the shortwave trough moves into the Great Lakes and a cyclonic flow to be in place. Additional accumulations of an inch or less can be expected central/east-central WI, 2 to 5" for northern WI. The main story for Sunday will be the strong west-northwest winds with a sustained 20 to 30 mph and gusts of 40 to 50 mph. Even as the snow either ends or becomes light Sunday afternoon, anticipate plenty of blowing/drifting snow especially on north-south roads. Visibilities would be significantly impacted and traveling would be hazardous. Max temperatures to be in the upper 20s to around 30 degrees central WI, lower to middle 30s eastern WI around midday with falling temperatures in the afternoon. Any lingering light snow over far northern WI will end Sunday evening as the system pulls farther away and high pressure begins to build east from the northern Plains. Skies should begin to clear during the overnight hours with strong CAA sending 8H temperatures down into the -18 to -22C range by 12Z Monday. Winds are forecast to weaken a bit (still 10 to 20 mph) and when combined with min temperatures of zero to 5 below central WI, 5 to 10 above zero eastern WI, wind chills of -15 to -25F are expected with possible headlines for central WI. This high pressure to stretch from southern Saskatchewan to the western Great Lakes region on Monday and help to keep sky conditions generally partly cloudy through the day. Max temperatures for Monday to be much colder than previous days with readings only from 5 to 10 above central WI, 10 to 15 degrees eastern WI. Models continue to struggle with a system headed toward WI on Tuesday. The main culprit for the indecision appears to be the strength of a Rockies upper ridge. The GEM and GFS are rather weak, thus shortwave energy takes aim at WI, along with an inverted surface trough. The GFS starts up light snow across northern WI Tuesday morning, while the GEM holds off on any snow until Tuesday evening. The ECMWF has the stronger upper ridge, thus shortwave energy dives to our south and we remain dry on Tuesday. Prefer to focus higher chance or likely pops from Tuesday afternoon into Tuesday night, however there is too much uncertainty yet to mention accumulation potential. The snow chances would then carry over into Wednesday morning until the shortwave/surface trough exit the area. Improving conditions are then expected for Wednesday afternoon as another high pressure starts to build into WI. Max temperatures for Tuesday and Wednesday to remain well-below normal (teens on Tuesday - upper teens to lower 20s on Wednesday). The high pressure is forecast to move into the Midwest Wednesday night and across southern sections of the Great Lakes on Thursday. Quiet and continued cold conditions to persist with max temperatures again in the upper teens to lower 20s. Models are all over the place with the handling/timing of the next system for late Thursday night into Friday. The GFS is faster/ stronger with the system, the GEM is faster/weaker with the system and the ECMWF is slower/stronger (holding off precipitation until Friday night). For simplicity sake, will follow the consensus solution which brings a small chance for light snow into northeast WI on Friday. Max temperatures for Friday to be in the lower to middle 20s north-central WI, upper 20s to around 30 degrees east- central WI. && .AVIATION...for 00Z TAF Issuance Issued at 559 PM CST Fri Feb 22 2019 VFR conditions are expected overnight except the area north of Rhinelander where light snow and MVFR conditions are possible after 09z. An approaching winter storm will produce periods of light precipitation across the area Saturday, with ceilings and visibilities falling to IFR by afternoon in most places. Freezing rain, sleet or rain is possible mainly east of an IMT to AUW with snow further west. The precipitation will change to all snow late Saturday night or early Sunday. && .GRB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 6 AM to noon CST Saturday for WIZ020-021-030-031-035>037-045. Winter Storm Watch from Saturday evening through Sunday afternoon for WIZ005-010>013-018>021-030-031-035>037-073-074. Winter Weather Advisory from 3 AM to 6 PM CST Saturday for WIZ005-010>013-018-019. && $$ SHORT TERM.....MPC LONG TERM......Kallas AVIATION.......RDM
Area Forecast Discussion
National Weather Service Houston/Galveston TX
946 PM CST Fri Feb 22 2019 .UPDATE... Longwave upper-middle level trough digging down into Arizona this evening will be placing Texas in the more diffulent region of the southern branch jet through Saturday afternoon. As this trough axis tilts out and lifts northeast into the western Plains overnight, the surface reflection will be one of lee cyclogenesis that will aid in drawing the region`s quasi-stationary/warm frontal boundary, and subsequently highly moist (low 70F Td) air, further north. Mucky weather will persist downstream of the eastward-advancing cold front that will be reaching Central Texas around sunrise Saturday. 60 to low 70F dew point air overspreading most of the CWA may allow for the further expansion of dense fog. A Dense Fog Advisory is in effect for the nearshore, bay, coastal and eastern CWA this evening. Western visibilites are already beginning to fall to around a mile or below this hour so this Advisory may likely expand westward by Midnight tonight. Low to mid 50s across the far northwestern CWA, or northwest of the near stationary/warm front with all communities south of this boundary remaining in their current average middle to upper 60s. The cold front will cross the CWA tomorrow morning during the daytime hours. With the region falling under the right rear entrance quadrant of the jet mid to late Saturday morning, along with mid-layer cooling brought on by the vicinity upper trough axis, this will create near 6C sfc-3km lapse rates and keep the threat for early day thunderstorms alive. There may be enough late morning mid-layer cooling to weaken cap in tandem with upper diffulence to produce strong to severe thunderstorms across the northeastern CWA. SPC has the southwestern 2/3rds of the forecast area under a Marginal risk with Slight risk just clipping eastern Trinity and Polk Counties. The good news is that this frontal passage will quickly scour out any remaining dense fog, cirrus remains by the close of business tomorrow. Saturday MaxTs will average in the upper 60s to lower 70s. Cold air advection brought on by moderate north winds, with mainly clear overnight skies, will have many interior locations falling into the low to mid 40s / lower 50s along the coast Sunday morning. 31 && .PREV DISCUSSION... /ISSUED 605 PM CST Fri Feb 22 2019/ AVIATION... LIFR ceilings and fog will persist overnight and into the morning hours Saturday. There could be some brief improvement near any isolated light/moderate showers overnight, but that won`t be the norm and isn`t indicated in the TAFs. Cold front and associated band of shra & embedded tsra should push thru se Tx from northwest (CLL) to se (GLS) between 13-19Z. Ceilings should gradually lift into VFR territory a few hours after the front passes and rains end. Look for wind gusts 15-25kt out of the wnw behind the front. 47 && PREV DISCUSSION... /ISSUED 322 PM CST Fri Feb 22 2019/ SHORT TERM [Tonight Through Sunday Night]... Latest mesoanalysis shows the warm front has moved inland basically from north of Palacios to Houston HOU to north of Beaumont. T/Td are in the 70s south of the front as we can confirm here at the office. North of the front temperatures are still in the 60s to 50s in the Brazos valley. Temperatures may drop a little bit tonight but largely remain steady. If anything temperatures may increase a bit as the warm front moves more north after midnight tonight. There will continue to be chances of showers and maybe an isolated thunderstorm. Jet streak and vorticity max seen on water vapor imagery has move into the area but any convection with it is located north of the area towards the Arklatex. There is a thin band of showers from College Station down to Victoria but this activity should not develop much more than it has. AMDAR airplane soundings show capping at 800-700mb and 700mb temperatures are pushing 8C-10C based of this an RAP mesoanalysis data. Cap should hold overnight going into tomorrow morning. Upper level trough over the southern Rockies should rotate east into the Plains by mid day Saturday. Surface low should deepen near the upper low and push a Pacific cold front into the area. Largely this means there will not be much of a temperature difference, but the airmass will be significantly drier. WRF model runs agree with a broken line of convection moving along the front from 12Z to 18Z Saturday. A few storms could be strong but given the capping, it will be a battle for significant deep convection to develop. SPC has most of the area in a marginal risk and this looks on track. Greatest threat will be east and northeast of the area. Storms could still produce gusty winds, lightning and brief heavy rainfall. While soils are rather moist, flooding should not be a concern with storms moving through the area quickly. Front should be of the coast and east of the area by 18Z to 21Z based on WRF model runs along with the NAM/GFS. Airmass should be much drier and should cool off overnight. Low temperatures Sunday should be in the 40s most areas with a nice warm up into the 60s for high temperatures Sunday. Overpeck LONG TERM [Monday Through Friday]... Moisture return looks to set up once again Monday night into Tuesday. Forecast will keep an increase in rain chances for the Tuesday time period. Beyond Tuesday all of the models really struggle with finding a common solution. Best chance of rain next week does look to be on Tuesday, but depending upon the model, there could be some low end rain chances for much of the week after Tuesday. Right now think the ensemble/blended model approach looks to be best course of action for the forecast. Usually the models have had a least some consistency with only some slight timing problems, but lately that has not been the case. Overpeck && MARINE... Will be keeping the Marine Dense Fog Advisory in place for the bays and nearshore waters through 9AM Sat morning. Some brief periods of slightly improved visibilities are possible the rest of this after- noon, but should fall once again this evening/overnight. This Advisory may be extended a couple of hours tomorrow morning...depending on the timing of the next cold front. Per the models...the front is expected to reach the coast around noon (Sat), with scattered showers and isolated thunderstorms along/ahead of it. Moderate/strong N to NW winds in the wake of the front will help clear the fog out of the marine areas late Sat afternoon/early evening. SCEC flags could also be posted very briefly over the coastal waters Sat night. How- ever, with the surface high building in quickly over the region, we will likely see winds decreasing once again by Sun morning. Winds will turn easterly late Sunday and slowly strengthen Mon/Tues as the fetch deepens. As a result, tide levels are forecast to rise to around 2.5 ft above MLLW. Will have to watch for possible run-up issues from mid-week on. Otherwise, unsettled weather should return to the coastal waters Tues along with onshore winds. 41 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 52 69 41 64 41 / 40 80 0 0 0 Houston (IAH) 64 73 47 67 45 / 30 80 0 0 0 Galveston (GLS) 64 73 55 65 53 / 20 70 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Dense Fog Advisory until 10 AM CST Saturday for the following zones: Brazoria Islands...Chambers...Coastal Brazoria... Coastal Galveston...Coastal Harris...Coastal Jackson... Coastal Matagorda...Galveston Island and Bolivar Peninsula...Houston...Matagorda Islands...Montgomery... Northern Liberty...Polk...San Jacinto...Southern Liberty... Trinity...Walker. GM...Dense Fog Advisory until 10 AM CST Saturday for the following zones: Galveston Bay...Matagorda Bay. Dense Fog Advisory until noon CST Saturday for the following zones: Coastal waters from Freeport to Matagorda Ship Channel TX out 20 NM...Coastal waters from High Island to Freeport TX out 20 NM. && $$ Discussion...31/47
National Weather Service Wilmington OH
911 PM EST Fri Feb 22 2019 .SYNOPSIS... A few showers will be possible during the overnight hours. On Saturday, south winds ahead of a vigorous system in the midwest will lift more widespread showers northward along with a warm front. A cold front will pass east through the region Saturday night, and could bring a round of thunderstorms with it in addition to very heavy rain and strong, potentially damaging winds. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Temperatures have dropped off this evening, however a few locations have already started to level off. Expect temperatures to slowly rise during the second half of the night as thicker cloud cover moves into the region. Dry conditions are currently in place, however as the night progresses a few showers will begin to work northwards. Any precipitation activity during the overnight hours is expected to be light with most of activity near and south of the Ohio River. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... A strong surface low will track northeast from the plains to the midwest on Saturday, and then to the Great Lakes region Saturday night. Ahead of it, 60kt lljet will transport a moisture plume to the region. Showers that occur in the warm sector ahead of the front may wring out a period of moderate to heavy rain as a warm front either meanders over the forecast area or lifts northward depending on the model being spoken to. Attm, the progressive nature of the RAP lifting the warm front north seems more likely with the strong lljet versus the models that are wringing out this rain over KY and southern CWA during the day. As the dynamics approach with the front, if the warm air noses well north, the chances for severe thunderstorms will increase rapidly. Regardless if the area gets nicely warm-sectored, the front is vigorous and may contain damaging winds regardless of the amount of instability that may be present to produce thunderstorms. Kept the thunderstorm chances during the nighttime hours and associated them with likely pops. Likewise, associated the moderate rainfall with likely pops through the day and overnight Saturday. As the front crosses overnight, rapid stabilization will occur and showers will end from west to east. Marginal instability to develop into the region with the warm front lifting into the area. Temperatures will warm 10-15 deg above normal with highs from near 50 north to around 60 south. Do not have any additional thoughts on the flood watch but did shave back the amount of rain expected - a little. Storm total rainfall of 1 to 2 inches remains likely with locally higher amounts possible. An already saturated ground with area rivers and streams running high keeps this rainfall as an active threat for flooding. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Secondary front will sweep across the region at the beginning of the period. Strong pressure rises along with cold air advection will result in robust winds, both sustained and gusts. Latest guidance suggests that speeds might fall short of warning criteria, but it is close enough to continue with the high wind watch. Cannot rule out a few showers with this boundary, but any additional precipitation amounts will be light. After initial drop in temperatures Sunday morning, readings will have little or no recovery in the afternoon. Pressure gradient will start to relax Sunday night with winds dropping off quite a bit by Monday as high pressure builds in. ECMWF remains steadfast in having the ridge extend into the area through the rest of the week with colder temperatures compared to other guidance. Have leaned towards GFS/Canadian which break off a piece of the high and passes it to the east Monday night into Tuesday. Then in response to a short wave, low pressure develops and moves across the Great Lakes with a trailing cold front crossing the area on Wednesday. This could bring some light precipitation. Uncertainty increases further late in the week with the potential for an inverted trough which would bring another chance of precipitation. Temperatures are forecast to be below normal through the period. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... VFR conditions will start out the TAF period with mid and high clouds moving across the TAF sites. As a warm front pushes northward showers will move into the TAF sites late in the overnight hours and continue off and on through the remainder of the TAF period. Winds will shift and then increase during the day, however most of the wind gusts will hold off until near or after the end of the TAF period. Some low level wind shear will be possible at that time too. Cigs will lower during the morning and mid day hours on Saturday, however will see some improvement to MVFR at some of the TAF sites late in the period. A few isolated thunderstorms cannot be ruled out Saturday afternoon, however the better chance for thunderstorms will be after the end of the TAF period and therefore decided to leave out of the TAFs at this time. OUTLOOK...MVFR conditions are possible from Saturday through Sunday. There will be a chance of thunderstorms on Saturday night. Strong winds are expected on Sunday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...High Wind Watch from late Saturday night through Sunday evening for OHZ026-034-035-042>046-051>056-060>065. Flood Watch from 7 AM EST Saturday through late Saturday night for OHZ079-081-082-088. KY...Flood Watch from 7 AM EST Saturday through late Saturday night for KYZ094>100. IN...High Wind Watch from late Saturday night through Sunday evening for INZ050. && $$ SYNOPSIS...Franks/Novak NEAR TERM...Novak SHORT TERM...Franks LONG TERM... AVIATION...Novak
Area Forecast Discussion
National Weather Service North Platte NE
543 PM CST Fri Feb 22 2019 .SHORT TERM...(This evening through Saturday night) Issued at 257 PM CST Fri Feb 22 2019 Freezing drizzle with patchy fog to areas of fog mixed with light snow at times will continue tonight. A transition to snow and fog will occur across the northwest Sandhills late evening and move east to near an Ainsworth through Sutherland and Imperial line late tonight. Chances for freezing drizzle, fog, and light snow all areas to the east overnight. An amplified upper trough currently just west of the Four Corners Region will take on a negative tilt with a closed low into the Texas Panhandle by 12Z Saturday. A 700mb trough will become a focus for mid level frontogenesis tonight as a surface cold front moves into western Nebraska tonight. New snow accumulations 1 to 2 inches west of Imperial through Mullen, and a dusting to less than an inch elsewhere. On Saturday, the main upper trough swings across. 2 to 4 inches expected along and south of I80. Models are in fair agreement on a deformation zone to move east across the area. The GFS remains to most organized in showing this, while the NAM indicates a much weaker deformation zone. The HRRR, RAP and NAM Nest models have increasingly shown QPFs and snowfall amounts trending toward forecast amounts, so confidence is increasing on overall model consensus. Only expecting an inch or less near and north of highways 2 and 91. Across the southern half of the forecast area, northwest winds will increase to 25 to 35 mph by late Saturday morning through the afternoon with gusts as high as 45 mph. This may cause areas of blowing snow and low visibility. Extra caution should be used if travel is necessary on Saturday. Snow ends west of Valentine through Ogallala by 18Z, with snow completely east of the area by Saturday evening. A winter weather advisory will remain in effect for the entire western and north central Nebraska counties through Saturday afternoon. See the latest headline for additional details about this storm. Clear and cold Saturday night with lows into the single digits to around 10 above. Wind chills late night could reach 10 below north central. .LONG TERM...(Sunday through Friday) Issued at 257 PM CST Fri Feb 22 2019 For Sunday through Friday, temperatures will remain much below normal each day with highs mainly in the 20s, with only teens some areas Monday through Wednesday. A bocking ridge over Alaska will continue to transport arctic air from central Canada southward into the Plains and Great Lakes region next week. A modest warmup into the 30s to near 40 by Thursday as an upper trough moves into the Pacific northwest. Small snow chances Sunday night into Monday morning north central, otherwise mainly dry until that upper trough in the Pacific Northwest swings across Thursday night and Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 533 PM CST Fri Feb 22 2019 IFR and periodic LIFR conditions expected overnight across much of western Nebraska as freezing drizzle and snow moves into the area from the west. Expect brief periods of LIFR to impact KVTN shortly after 23/00z and KLBF shortly after 23/02z. LIFR conditions will be periodic before conditions improve after 23/15z as ceilings rise. Winds will shift from the east prior to dawn to northwest by early afternoon with gusts approaching 30 to 40 knots. && .LBF WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 PM CST /5 PM MST/ Saturday for NEZ004>010-022>029-035>038-056>059-069>071-094. && $$ SHORT TERM...Roberg LONG TERM...Roberg AVIATION...Buttler/Jurgensen
Area Forecast Discussion
National Weather Service Louisville KY
1014 PM EST Fri Feb 22 2019 .Forecast Update... Issued 1005 PM EST Wed Feb 20 2019 Some of the latest 00z model guidance that has come has shifted the heaviest precipitation axis to our south for the overnight hours. Much of this is due to the warm front moving a bit slower northward than what guidance was suggesting 12-24 hours ago. Take the NAM, for example... the 00z NAM from yesterday has the warm front in parts of central Kentucky by 12z Saturday morning, whereas the most recent NAM has it in southern TN by 12z Saturday morning. Have updated the forecast to account for less precipitation overnight. There is still lots of uncertainty going into tomorrow`s forecast, much of which will be dependent on how far north the warm front lifts and how much destabilization we see. Some high-res models, like the 00z HRRR, are quite aggressive with the advancement of the warm front and advection of higher Td air into the region. Should the HRRR solution play out, there could be a severe weather threat as early as the afternoon hours. Other models, like the 00z NAM, would keep the severe threat limited to the evening/overnight hours tomorrow when a plume of higher Td air and instability pool ahead of a potential line or broken line of convection. Even then, though, model soundings from the 00z NAM show small surface inversions in place ahead of this line, which would indicate elevated convection and a lesser risk for wind and isolated tornadoes. The greatest threat for tomorrow will continue to be the flooding, given how wet we`ve been and how much potential moisture may fall from storms. The severe threat continues to be conditional on the development of instability, and if we can get surface based convection (vs elevated). Still thinking the timeline for the best severe chances in the region will be between 7pm EST and 2am EST. && .Short Term...(This evening through Saturday Night) Issued at 315 PM EST Fri Feb 22 2019 ...Heavy Rain & Flooding Late Tonight Into Saturday... ...Severe Thunderstorm Threat Saturday Evening... Things are quiet across the CWA at this hour with cloudy skies and temps mostly in the mid to upper 40s. Light rain has been persistent across southern KY, and this will continue through the afternoon and early evening. Amounts have only been between a tenth and a quarter of an inch across our southern tier, so rates haven`t been impressive to this point. Tonight - Saturday... A strong upper impulse will eject out of the SW CONUS spawning surface cyclogenesis from the lee of the Rockies up into the Great Lakes by late Saturday. A frontal boundary stalled to the south of the CWA will slowly lift north across our area on Saturday, with moderate to heavy rainfall rates slowly lifting north with the feature through the day. This will bring a continued Flash Flood threat to the area, along with an elevated storm threat through the afternoon hours. Given a very strong vertical shear profile, some rotating elevated storms will be possible in the afternoon (more on the severe threat later in the evening below). Expect things to get going as we move past Midnight as low level jetting beneath an anticyclonically curved upper jet increases from south to north. The associated moisture transport will increase after 06z, and especially toward dawn across our south. Expect to see an increase in precipitation coverage and rates by this time. In addition, some elevated instability is also expected to be available by this time, adding a convective element to rainfall potential. 1 hr Flash Flood guidance values are as low as 1 inch in an hour in spots across our SE CWA, and mostly between 1 and 2 inches everywhere else. Given that increased coverage and rates will be very slow to move north with the frontal boundary there is high likelihood that Flash Flooding will occur early Saturday morning with the threat lasting through the day. Did go ahead and back up the start time of the Flash Flood Watch by 6 hours as it does not look like any decent rates will be into our area until after 06z, and more specifically toward dawn. The heaviest rain is still expected to fall across southern and central KY through Saturday where 2 to 3 inches are expected, and locally higher amounts are certainly possible with some training and repeated convective cells. Temps tonight will mostly sit in the 40s north of the warm front. As the weak warm sector gets established over the area tomorrow, temps will rise into the 60s with dew points also rising into 55 to 60 range. Saturday Evening - Saturday Night... By Saturday evening, a weak and short-lived warm sector will be established across our area, where a meager axis of instability will be possible just ahead of the cold front. The latest data still only suggests around 100-300 J/KG of surface or near surface based instability will be possible along and west of I-65 from 00 to 06z. This is where a broken line of convective clusters including supercell storm modes and bowing segments capable of mesovortice generation will be possible. Still like the idea of advertising a damaging wind threat, along with an isolated tornado threat during that time. Like the Day 2 SPC convective outlook update the re- introduces the Slight Risk to our SW CWA. In addition to the short- lived severe threat, this final round of convection could add to or agitate any Flooding concerns, although storms should be moving fairly quickly. Strong winds aloft will remain over the region as the cold front passes through the area, and expect some of these winds are going to be able to be mixed down in the post-frontal regime overnight. Gusts in the 35-45 mph range may be possible and a Wind Advisory may have to be considered into Sunday morning. Overall, have high confidence in the Flash Flood Threat Saturday morning through Saturday evening, especially across central and southern Kentucky. The severe threat confidence is a little lower, given that it is conditional upon the weak instability axis developing. .Long Term...(Sunday through Friday) Issued at 245 PM EST Fri Feb 22 2019 ...Windy Sunday, Then Much Quieter Weather... An expansive wind field around powerful low pressure lifting from the upper Great Lakes to near James Bay on Sunday will reach all the way back into the Ohio Valley. Winds gusting 40-45mph will be possible, especially in southern Indiana and north central Kentucky. Fortunately the air mass will not be particularly cold, with expected high temperatures near normal for late February. A few sprinkles will be possible in the morning before clearing in the afternoon. Monday and Tuesday will be dry with a long ridge of high pressure moving from the northern Plains to the East Coast. Wednesday through Friday the models are not in good agreement, but basically we`ll have zonal flow aloft with just a few subtle ripples moving through. What precipitation does fall during this time should be light and scattered according to current progs. Temperatures should remain near normal. && .Aviation...(00Z TAF Issuance) Updated at 605 PM EST Fri Feb 22 2019 Active weather expected in the short term. A warm front currently across central AL/MS will begin lifting northward tonight. Ahead of it, IFR/MVFR stratus and widespread showers will move into central Kentucky and southern Indiana after midnight. The rain could be heavy at times, and isolated thunderstorms will be possible. Poor flying conditions will continue through most of the day tomorrow, though depending on how far north the warm front lifts, we could see some higher (VFR) ceilings and drier conditions move into southern portions of Kentucky during the afternoon hours. A line or broken line of thunderstorms are then expected ahead of a front, and some of the storms could be strong to severe. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...Flash Flood Watch through late Saturday night for KYZ023>031- 033>043-045>049-053>057-061>067-070>078-081-082. && $$ Update...DM Short Term...BJS Long Term...13 Aviation...DM
Area Forecast Discussion
National Weather Service Marquette MI
646 PM EST Fri Feb 22 2019 .SHORT TERM...(This evening through Saturday) Issued at 324 PM EST FRI FEB 22 2019 Surface ridge axis passes overhead this evening through the wee hours of Saturday morning. As winds go nearly calm, have dropped lows into the mid teens over the east. Did not go too low, however, because WAA clouds aloft will inhibit radiative cooling. For the day Saturday, looking at a mid-level shortwave in SW flow passing through Wisconsin and clipping Upper Michigan. Will see a broad region of WAA/isentropic lift out ahead of the wave, but in addition, meso models show an fgen band around 700 mb lifting across central and western Upper Michigan late morning through the afternoon Saturday. This could lead to enhanced snowfall in these areas. So for precip, leaned towards hi-res models as there is a solid consensus in them for a broad band of QPF exceeding 0.3" and perhaps a narrower band embedded in there with QPF in excess of 0.5". While all of the U.P. will see at least light accumulations, this heavier band is most likely to set up along a SW to NE axis through Iron, Baraga, and Marquette Counties, and perhaps northern Dickinson. The DGZ will be pretty high (around 600-700 mb and above) and pretty thin (only about 100 mb thick) which, along with fairly strong winds below the dendritic growth layer shattering the dendrites, will probably lead to smaller flakes and therefore lower SLRs of around 10-12:1. Still, given the QPF, this results in 3-5" of snow for the aforementioned heavier snow areas and generally 1-3" elsewhere. Since this predominantly falls in less than 12 hours and since it will be a wetter snow, have opted to hoist a Winter Weather Advisory for Saturday ahead of the main event even though snow amounts are a bit on the marginal side. There are two close calls here: Iron Mountain is tough as most hi- res guidance keeps them right on the edge of the heavier snow to their west. So is the Keweenaw as the ARW and extended HRRR put the band over them, so we`ll need to watch things closely to see if a small shift in snow placement drastically changes snow totals in either of these places. For temps on Saturday, also tended towards the hi-res models on land. Did this assuming that they`re probably handling evaporative cooling under the heavier snow better than the coarser global models. Big system moves in very late in the period and will be covered in the long-term section. .LONG TERM...(Saturday night through Friday) Issued at 523 PM EST FRI FEB 22 2019 ...SIGNIFICANT WINTER STORM TO IMPACT THE REGION STARTING SATURDAY NIGHT... Very strong, dynamic system moves in Sat night and Sun. Model generally in good agreement with even the NAM now coming onboard with the rest of the model solutions. Strong negatively-tilted shortwave trough and associated sfc low will lift up from the Central Plains (near se IA) at 00Z Sun to near Manistique in Upper MI by 12Z Sun while the surface low deepens to near 980 mb! The low keeps a quick pace and moves into northern Quebec by Sun evening. Models have been fairly consistent with the placement and amounts of precip and the strength of the system, although I`m a little concerned with some of models indicating the possibility of a dry slot moving into the south central and southeast U.P late Sat night/early Sun which could cut into mixed pcpn/snow amounts there. Given that there is some uncertainty regarding this dry slot and where exactly the mixed pcpn/freezing rain axis will be, have decided to keep the winter storm watch posted for now, which is also consistent with adjacent offices. Main hazards are very heavy snowfall (especially over the NW half), a snow/sleet/freezing rain combo SE, and strong winds (especially near Lake Superior) developing on Sunday. Heavier synoptic pcpn moves in from the south by mid-late Sat evening and largely exits by midday Sunday with nw flow lake effect snow remaining. Current forecast for west and north central generally hasn`t changed much with 10+ inches of snow, much of which falls between 06Z and 18Z Sun. Snow will be wet and heavy. Over the SE half where dry slot will cut into accums, 2-7 inches of snow (least along Lake Mi and Bay of Green Bay) is expected along with sleet and freezing rain accumulations, which are less certain. NW winds increase dramatically on Sun when the system bombs out and continues to quickly lift NE. Currently forecasting NW gusts to 55mph over east half of Lake Superior and shoreline areas east of Marquette, with gusts of 35-45mph elsewhere, but could end up higher given the strength of the system. Blowing/drifting snow and some power outages will be the primary impact from the wind. Blowing snow near Lake Superior E of Harvey could lead to impossible travel Sun into Mon with whiteout conditions and considerable blowing/drifting of snow. Expect general diminishment of wind and LES from the west late Sun night into Mon with minor snow accums, but much colder conditions will be highlighted during this time as minimum wind chills could drop close to advisory criteria. Periods of light nw flow LES will continue through the rest of the week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 638 PM EST FRI FEB 22 2019 The ongoing VFR conditions won`t last for much longer, with KIWD the first terminal to see lowering ceilings, followed by visbys. Shortly thereafter, KCMX and eventually KSAW will follow suit, with MVFR or lower prevailing throughout the remainder of the TAF period. Moderate snow currently looks to impact the terminals tomorrow morning at KIWD and KCMX, with moderate snow looking more likely later in the morning at KSAW. As for winds, they`ll remain relatively light with a slight uptick tomorrow evening, with the much more robust winds holding off until Sunday. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 324 PM EST FRI FEB 22 2019 Quiet through Saturday night with winds less than 25 knots. Northerly gales expected Sunday morning across Lake Superior, building to storms to 50 knots over the eastern arm Sunday afternoon and night. Gales subside over the western arm Sunday night and over the eastern arm midday Monday. After that, quiet conditions expected through the middle of next week with gusts less than 20 knots over the western arm and less than 25 knots over the eastern arm. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory from 7 AM EST /6 AM CST/ to 7 PM EST /6 PM CST/ Saturday for MIZ001>005-009>011-084. Winter Storm Watch from Saturday evening through late Sunday night for MIZ001>005-009-084. Winter Storm Watch from Saturday evening through Monday afternoon for MIZ006-007-085. Winter Storm Watch from Saturday evening through Sunday evening for MIZ010>014. Lake Superior... Storm Warning from 10 AM Sunday to 4 AM EST Monday for LSZ249>251-266-267. Gale Warning from 7 AM EST /6 AM CST/ Sunday to 1 AM EST /midnight CST/ Monday for LSZ162-240>248-263>265. Lake Michigan... None. && $$ SHORT TERM...RJC LONG TERM...Voss AVIATION...lg MARINE...RJC
Area Forecast Discussion
National Weather Service Morristown TN
1040 PM EST Fri Feb 22 2019 .DISCUSSION... Many updates to the forecast tonight with additional chances of heavy rainfall. Additionally, high winds across the mountain zones Saturday night is beginning to look increasingly likely. Overall, temperatures were on track and am not planning any updates. Skies remained cloudy tonight while the main axis of rainfall, aligned along a zone of enhanced 850mb convergence, continues to lift northward. To the south, a warm front analyzed across northern Georgia, Alabama, and Mississippi continues its northward movement with a poleward transport of low level moisture. Area radar shows an area of heavy rainfall forming again across north Mississippi and west Tennessee along and ahead of the front aided by an 850mb jet and associated warm air advection. Closer to our CWA, areas of rainfall are starting to fill in and will continue to push northward into southern Tennessee. Latest short term and hi-res models indicate a band of enhanced rainfall along the advancing warm front. The main differences in models are where exactly the axis of greater 850mb winds will set up. The HRRR is more east with this zone, and as a result places the heavier QPF axis further into the MRX CWA. The NAM is a bit further west, which keeps the higher QPF totals closer to middle Tennessee, although higher totals are still seen across the Cumberland Plateau. No matter these differences, it seems increasingly likely that heavy rainfall will move back into the region in the morning hours with heavy precipitation rates given the strength of upper level diffluence and accompanied low level convergence along the front. As of this update, 1-3 inches of additional rainfall seems possible across the Plateau area. While instability looks limited, any elevated convection could enhance rainfall rates, and contribute to additional amounts of rainfall. These areas have already seen plenty of rainfall, and any additional rain could cause flooding. As a result, have extended the flood watch timing through Saturday night and added a couple of additional counties to better match the forecasted QPF axis. The other item of interest was to issue a high wind watch for the mountain zones Saturday night. The orientation of 850mb winds is not favorable for a true mountain wave event, however, enhanced 850mb winds in excess of 50-60 knots in addition to an enhanced pressure gradient would support high winds across the mountains. The updated zones have already been published. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 50 61 51 59 / 70 50 90 10 Knoxville McGhee Tyson Airport, TN 49 61 51 59 / 80 80 80 10 Oak Ridge, TN 49 59 51 58 / 90 90 80 10 Tri Cities Airport, TN 46 56 49 58 / 80 90 80 20 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...Flood Watch until 7 AM EST Saturday for Cherokee-Clay. TN...Flood Watch until 7 AM EST Saturday for Blount Smoky Mountains- Bradley-Cocke Smoky Mountains-East Polk-Hamilton-Jefferson- McMinn-NW Blount-North Sevier-Northwest Cocke-Northwest Monroe-Sevier Smoky Mountains-Southeast Greene-Southeast Monroe-West Polk. High Wind Watch from Saturday evening through Sunday morning for Blount Smoky Mountains-Cocke Smoky Mountains-Sevier Smoky Mountains-Southeast Greene-Southeast Monroe. Flood Watch through late Saturday night for Anderson-Bledsoe- Campbell-Claiborne-Grainger-Hamblen-Hancock-Hawkins-Johnson- Knox-Loudon-Marion-Meigs-Morgan-Northwest Carter-Northwest Greene-Rhea-Roane-Scott TN-Sequatchie-Southeast Carter- Sullivan-Unicoi-Union-Washington TN. VA...Flood Watch through late Saturday night for Lee-Russell-Scott- Washington-Wise. && $$ AD
Area Forecast Discussion
National Weather Service Nashville TN
527 PM CST Fri Feb 22 2019 .UPDATE... FOR 00Z AVIATION DISCUSSION. && .DISCUSSION... Warm front is located over central AL late this afternoon. Deep southwesterly flow will act to lift this boundary northward this evening. Vorticity looks as though it will align more favorable to the height values as boundary begins to approach. Favorable 850 mb wind curvature will ramp up as speeds increase. Thus...with enhanced lifting will come the heavier rainfall. Hrrr and current fcst appears to be on track. It appears that the heavier rainfall will begin as we approach midnight with the most favorable window for heavier rain occurring from midnight to 6 am. Greatest amounts appear to be targeting our northwest half with 1 to 2 inch amounts expected. If there is any good news to be found...the warm front will continue to lift northward with the area returning to a more moderate rainfall scenario after sunrise. Otw, a slow rise in temps overnight can be expected. Can see no reason for any grid update at this time. && .AVIATION... 00Z TAF DISCUSSION. Warm front over central AL will work quickly to the north as a warm front tonight. 850 mb flow off the surface will ramp up with lift increasing as the boundary approaches. Look for moderate rainfall to become heavier after 06z across the CKV and BNA areas. Conditions will remained socked in after sunrise though the rainfall will decrease some in intensity. Still looking at the potential for a round of thunderstorms across western middle TN aft 20z. Instability values will be much lower near CSV where a lesser threat of convection resides. && .OHX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Saturday evening for Bedford-Cannon- Cheatham-Clay-Coffee-Cumberland-Davidson-De Kalb-Dickson- Fentress-Giles-Grundy-Hickman-Houston-Humphreys-Jackson-Lawrence- Lewis-Macon-Marshall-Maury-Montgomery-Overton-Perry-Pickett- Putnam-Robertson-Rutherford-Smith-Stewart-Sumner-Trousdale-Van Buren-Warren-Wayne-White-Williamson-Wilson. && $$ AVIATION........21
Area Forecast Discussion
National Weather Service Pueblo CO
839 PM MST Fri Feb 22 2019 .UPDATE... Issued at 829 PM MST Fri Feb 22 2019 Evening run of the NAM and HRRR suggest that Crowley and Otero counties will have more snow than originally thought, from late tonight and into early Saturday, and thus will add them into the Winter Storm Warning. Have also increased snow amounts along portions of the I-25 corridor based on latest models. && .SHORT TERM...(This evening through Saturday) Issued at 340 PM MST Fri Feb 22 2019 ...Winter storm trending towards higher impacts with heavier snow for southern CO... Upper low over Arizona will continue deepen as it lifts northeastward into the TX and OK panhandles by early Saturday morning, and into central KS by mid day Saturday. Overall trends have been for higher snowfall amounts and greater impacts for southern Colorado as the storm wraps up more quickly to the south and sends a wave of showers northward across the plains this evening in the warm advection portion of the storm. A second more intense phase is expected late this evening into Saturday morning as the TROWAL takes shape with a band of heavy snow developing along the I- 25 corridor which then shifting eastward across the plains. Strong north winds will spread south of the Palmer Divide around 10 PM with gusts in the 40-50 mph range spreading southeastward after midnight into Saturday morning across much of the plains. This will set up a brief period (3-6 hour period) of intense wind driven snow across much of the plains, with the greatest impact portion of the storm running from midnight to 10 AM. In spite of the strong northerly winds (a downslope component off the Palmer), models show a good period of isentropic lift across southern El Paso and Pueblo counties between 11 PM and 3 AM as the intense snow band develops, so think this will overcome the downslope influences and provide a brief period of impactful wind driven snow across all of the I-25 corridor. Have included these zones in a winter weather advisory to account for this. However, area of greatest concern will be far eastern counties where conditions could be border-lining on blizzard conditions. Current package has winter storm warnings out through Saturday morning. It will be a heavy wet snow so this may limit the amount of blowing snow some as it may be difficult to loft snow once it hits the ground. And storm will be quick moving in nature which to some degree could limit accumulations as well. Have made some extensive modifications to highlights today with winter storm warnings for the eastern areas and winter weather advisories for the remainder of the southeast mountains and plains. For now it appears H7 winds stay a tad too northerly to provide a focused window of upslope for the southeast mountains to help enhance snowfall amounts. Areas of concern will be the Palmer Divide and far eastern plains for possible upgrades to highlights due to potential for higher snowfall amounts. This will all depend on how quickly the storm intensifies and how far west the wrap around band takes shape. Timing of the rain/snow switch over is another complicating factor with switch over to snow in Pueblo possibly holding off until 10 PM and towards 1-3 AM for the remainder of the southeast plains. Storm pulls away to the east on Saturday though conditions will still be quite bad for travel with snow and blowing snow for the far eastern plains through the morning. Temperatures will rebound for the I-25 corridor and adjacent plains with mixing bringing temperatures back up into the 40s. For the western mountains and valleys, snow will continue until 11 PM then diminish during the overnight hours. The San Luis Valley will pick up a quick 1 to 3 inches overnight, but without the wind, don`t think impacts will be as bad. Again winds don`t appear to shift easterly in direction enough to bring high impacts from the plains westward into western Fremont and central Chaffee current thinking is these areas may see more in the 1 to 3 inch range depending on location. This is a dynamic storm with the potential for more changes to the forecast. Bottom line tonight: Don`t travel if you don`t have to... check the latest forecast and road conditions first if you must, and make sure you have a winter storm kit in your car. .LONG TERM...(Saturday night through Friday) Issued at 340 PM MST Fri Feb 22 2019 Saturday night-Sunday night...Moderate to strong northwest flow aloft is progged across the region Saturday night, which becomes more westerly through the day Sunday, as the quick moving storm system continues to lift out across the Central High Plains and into the Upper Midwest, as another embedded wave translates across the Northern Rockies. The westerly flow aloft and some embedded moisture and lift associated with the second wave could bring some light snow showers to the Central Mts Saturday night, and along and west of the ContDvd Sunday afternoon, though any accumulations are expected to be mainly light and over the peaks. Temperatures to warm slightly through the day Sunday, though still look to be below seasonal levels with highs mainly in the 40s across the lower elevations and in the 20s and 30s across the higher terrain. Monday-Tuesday...Weak to moderate westerly flow aloft continues through mid week, with flat upper ridging building across the Rockies. This will allow for mainly dry weather area wide with temperatures warming back to at and above seasonal levels, with highs in the 50s to lower 60s across the Plains, and 30s and 40s across the higher terrain, warmest on Tuesday. Wednesday-Friday...Lower confidence forecast through the rest of the extended period, as the latest GFS is faster and further south with more Pacific energy translating across the Great Basin Wednesday, which then continues and spreads snow across Rockies on Thursday. ECMWF remains further north with said system, with the blended model solution keeping slight pops across the ContDVD in the Thursday timeframe. Models also hinting at the potential for a cooler airmass to slide across the Eastern Plains on Wednesday, as a cool Canadian surface high pressure system builds across the Upper Midwest and across the High Plains through the middle of the week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 340 PM MST Fri Feb 22 2019 A fast moving storm system will bring a quick shot of snow to the terminals this evening, with the greatest impact expected across the far southeast plains late tonight into mid day Saturday, with snow and blowing snow. For COS and PUB, light snow looks to develop between 02Z-04Z with MVFR and IFR conditions expected through 08z-10Z when northerly winds increase to between 25-35kts and end the snow between COS and PUB. Quick movement of the system will limit snow at the terminals, with 1 to 2 inches possible. VFR conditions with decreasing northerly winds expected at COS and PUB through Saturday morning and afternoon. For ALS, breezy southerly winds of 20-30kts will continue through the afternoon, with showers VC the terminal late in the afternoon. There will be a quick shot of snow and MVFR/IFR conditions at the terminal through the evening, with breezy northwest winds and VFR conditions expected again through the early morning hours, on the subsident backside of the system. && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until noon MST Saturday for COZ089-093>099. Winter Weather Advisory until 7 AM MST Saturday for COZ081-082- 084-087-088. Winter Weather Advisory until 5 AM MST Saturday for COZ072>075- 079-080. Winter Weather Advisory until 2 AM MST Saturday for COZ058-060- 061. Winter Weather Advisory until 6 AM MST Saturday for COZ086. Winter Storm Warning until 11 PM MST this evening for COZ066-068. Winter Weather Advisory until 6 AM MST Saturday for COZ085. Winter Weather Advisory until 11 PM MST this evening for COZ063. && $$ UPDATE...28 SHORT TERM...KT LONG TERM...MW AVIATION...MW