Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/05/17

Area Forecast Discussion
National Weather Service Denver/Boulder CO
846 PM MST Wed Jan 4 2017 .UPDATE... Issued at 845 PM MST Wed Jan 4 2017 Drier air noted on satellite recently passed overhead to weaken snowfall over the area. Some areas have completely stopped snowing. Do not be fooled and let your weather preparedness guard down. Additional moisture is seen upstream, especially on radar over the Salt Lake City area and pushing into western Colorado. Colder air expected to push in overnight will combine with the incoming moisture to ramp up snowfall, likely around or after midnight. Due to this, will not be adjusting snowfall totals. UPDATE Issued at 450 PM MST Wed Jan 4 2017 Have added winter weather advisories for the rest of the Northeast plains of Colorado with the exception of Lincoln county. Already reports of 2-3 inches of snow in Sterling and radar indicates some banding precip as well and potential developing further south as the night goes along. Overall 3-6 inches possible over the far plains. Elsewhere, heavier snow is developing over the adjacent plains and everything else appears is on track. Will watch the development of the heavier banded snowfall this evening and adjust forecasts as needed. && .SHORT TERM...(This evening through Thursday) Issued at 224 PM MST Wed Jan 4 2017 Overview: A significant snowstorm looks on track for much of Colorado today through Thursday morning. The primary mid and upper level vorticity maximum is located across central Oregon this afternoon. It is pulling an impressive stream of moisture from the Central Pacific into CA and Nevada. Downstream of the vorticity maximum the nose of a West-Northwest 130 kt jet stream will push across Colorado this overnight. By Thursday morning the northern half of Colorado is located under the left entrance region of the jet, and by Thursday afternoon the jet stream dynamics shift to the south of Colorado and winds turn west at the jet stream level. The 500 mb low moves very slowly tonight through Thursday setting the stage for a prolonged period of snow across Colorado but especially in the mountains. By Thursday evening the 500 mb low moves to western Utah, keeping very strong west-northwest flow at 500 mb of 70 kt over Colorado. At 700 mb flow remains out of the west through Thursday given the fact that the mid level vorticity max is moving into a long wave trough over C. and E. Canada. Arguably the most impressive aspect of this system is the availability of moisture. Upstream Precipitable water values via raobs and via satellite derived products are twice the normal amount and above the 90 percentile relative to normal for January 4. This set up favors sustained, moist, strong WNW flow through Thursday midday and significant snowfall. Mountains: Warning criteria snow amounts over the mountains and west slope will be met easily over the next 24 hours. Snow is ongoing this afternoon and will continue tonight and tomorrow morning. With the strongest jet dynamics shifting south by Thursday afternoon and some drying at and above 700 mb, expect snow will taper off most of the mountains by Thursday evening, other than the favored westerly upslope areas of Summit and Park Counties. Steep lapse rates between 700 and 500 mb overnight and the presence of the jet streak favor convective bands across the mountains this evening and overnight, most likely occurring after 8 PM. HRRR and ESRL HRRR both indicate banded precipitation over the mountains through about 3 AM. While pinpointing where these mesoscale convective bands set up is not possible, it is important to note that where they set up will lead to hazardous travel given intense snow rates of 1-2 inches per hour, lasting for several hours at a time on top of the orographic snow that had already been piling up. The bands should translate slowly southward overnight and do not appear likely after sunrise in the mountains. All mountain areas should do quite well in terms of storm total snow amounts with the moist upslope flow and potential for heavy bands to set up for several hours. Amounts will be highest across the west slope of the Continental Divide from Rocky Mountain NP southward to Gilpin and Clear Creek Counties and for the Medicine bow range....2 feet or more is possible in those areas. Elsewhere in the mountains 8-16 inches are expected with locally higher amounts occurring along westerly upslope areas and anywhere the mesoscale bands develop. Plains: Snowfall amounts across the Plains are trickier for this storm. With a lack of deep easterly upslope flow the forecast snow amounts are somewhat challenging. First, lee troughing under WNW flow begin in earnest this afternoon and is strongest south of the Palmer Divide. This area of surface low pressure doesn`t move much, extending from southern Colorado into northern New Mexico overnight through Thursday. The response is a reinforcing surge of cold air from the north this afternoon across the northern third of the Plains of Colorado. Trajectories our of the ENE at the surface favor upslope flow along and west of the I-25 corridor and along the north side of the Palmer Divide. Additional lift will be provided by low level frontogenesis later this evening in the vicinity of the frontal boundary. Latest high res model guidance does not show significant banding east of the mountains, other than the 3km NAM. HRRR, HRRRX, RUC do not seem to think banding will occur east of the mountains. There is evidence to suggest banding is possible...the Northern Front Range will be in the right exit region of a strong jet tonight and decent frontogenesis will occur associated with the front. Anywhere a band develops would result in snow total on the high end of the current snowfall totals shown on our probabilistic snowfall graphics, e.g. what is shown in the 90% graphic. Even without snowbands, light to moderate rates along and west of I-25 overnight into tomorrow morning with result in significant travel impacts across the urban corridor, with the best chance of getting over 12 inches in and very close to the foothills, 6-12 inches for the I-25 corridor, and far less amounts across the far eastern forecast zones. Finally, we went a bit above the GEFS and SREF ensemble mean totals. Snow should end all areas of the Plains by late Thursday. Snow will likely be falling in the Winter Storm Warning area at 11 AM when the warning expires, but latest thinking is that any additional accumulation will be on the light side. .LONG TERM...(Thursday night through Wednesday) Issued at 224 PM MST Wed Jan 4 2017 The jet will continue to sink south Thursday night taking the snow with it. Light snow will remain possible over the mountains, mainly south of Interstate 70 and along the Palmer Divide. Additional snow is expected to be light with up to 2 additional inches in the mountains. It is expected to clear out Thursday night over the northern Colorado. The clear skies, fresh snow, and light winds will allow temperatures to plummet Thursday night. Low will fall below zero, well below zero in the northern mountain valleys. Warming trend begins Friday as an upper level ridge begins to build over the western CONUS. Highs Friday will be cool with readings mainly in the 20s. Low lying areas, like the South Platte River valley, and mountain valleys will be cooler. The upper level ridge will shift east over the Central Rockies this weekend. Dry conditions and mostly clear skies are expected to prevail under his ridge. Temperatures will continue to warm through the weekend. For Sunday, highs may reach the lower 50s along the base of the foothills. However, the low lying areas could be as much as 20 degrees cooler for highs. Latest models show Pacific moisture moving back into the mountains Sunday and will add pops to the forecast for this. A strong Pacific system will move onto the west coast early next week. This will push the upper level ridge over the Central Rockies east of the region and replace it with a strong zonal flow. Models showing two systems embedded in the westerly flow that is expected to bring snow to the mountains. The timing among the models is off though. Will go with a good chance for snow in the mountains, Monday through Wednesday. Downslope flow will keep the Front Range and eastern plains mild, dry and windy at times. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 845 PM MST Wed Jan 4 2017 Snow is very banded in nature this evening, allowing for drastic changes in ceilings and visibility. Drier air evident on satellite overhead will push east with greater moisture to move in just before midnight. This coupled with colder air pushing down should reintensify overall snowfall, with banding still possible. Snowfall rates will then be one-half to one-inch per hour through the rest of the night. Will continue to try and time some of the heavier snowbands tonight, still expecting a period of heavier snow from 08z- 11z. Total snowfall at KDEN and KAPA is expected to be 6 to 8 inches. If a heavy snow band sets up, snowfall amounts will be higher. KBJC should see a couple more inches of snow than KDEN, 9 to 12 inches. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 11 AM MST Thursday for COZ042- 044>046-048>051. Winter Storm Warning until 11 AM MST Thursday for COZ030>036- 038>041-043. && $$ UPDATE...Kriederman SHORT TERM...Schlatter LONG TERM...Meier AVIATION...Kriederman
Area Forecast Discussion
National Weather Service Cheyenne WY
537 PM MST Wed Jan 4 2017 .UPDATE... Issued at 535 PM MST Wed Jan 4 2017 Went ahead and upgraded advisories for Laramie and Saratoga this evening as we are still looking at an additional 2-4 inches of snow overnight. Talking with the Albany County EM, there are developing impacts in Laramie as crews are having a hard time keeping up with the roads. Updates have been sent. && .SHORT TERM...(This evening through Friday) Issued at 230 PM MST Wed Jan 4 2017 Main difficulty will be additional snowfall amounts overnight before the snow comes to an end late tonight/early Thursday morning. Light snow continues to fall across the CWA this afternoon with some bands of moderate to heavy snow close to the Colorado border. Determining where these bands will be will be the critical factor in where heavier snow falls. Boundary has pushed south across far se Wy this afternoon...a little faster than anticipated...and current radar depicting a heavier snow bands along the Wy/Co border just south of Cheyenne and Laramie. Believe this is where the heavier snow will fall the rest of this afternoon into this evening with lighter snow to the north...over much of the CWA. As a result total snowfall looks to be a little less across far se Wy but totals still decent...generally in the 5-7 inch range outside of the mtns...with snow cover higher from earlier snow. Will keep current winter hilites as is. The snow will taper off from north to south overnight as an upper trough moves south across the region with snow expected to clear the CWA by late Thursday morning. Colder arctic air will build in over the CWA overnight with mins below zero over most of the CWA. The coldest will be over northern parts and with even light winds the wind chills will drop to very cold levels so will continue the wind chill advy for that area into Thursday morning. Clearing and cold Thursday with highs in the single digits to teens. Coldest night will be Thursday night as light winds...mainly clear skies and snow cover will allow temps to fall well below zero across the CWA. Will likely need additional wind chill hilites for that. Warmer temperatures ensue Friday as the cold arctic high slides southeast of the area and downslope flow returns. .LONG TERM...(Friday night through Wednesday) Issued at 230 PM MST Wed Jan 4 2017 A quiet weather pattern should prevail early in the forecast period with upper-level ridging in place over the central Rockies. We will likely see a gradual warming trend through Sunday as H7 temps climb to +2 to +4 deg C along/east of the Laramie Range. The medium range models are in good agreement w/ moist southwest flow aloft from Sun onward, leading to an increase in precipitation chances to the west of the Laramie Range. Westerly downslope flow will likely keep much of the high plains dry through early next week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 429 PM MST Wed Jan 4 2017 Slowly improving conditions this evening as an arctic front begins to move south into Colorado this evening. KRWL and KCDR will see these improvements intially with southern airports improving by late evening. Last airport to improve will likely be KLAR which will be the last location for snow to end. Followed latest HRRR guidance on timing. VFR all locations Thursday, but very cold. && .FIRE WEATHER... Issued at 230 PM MST Wed Jan 4 2017 See no concerns for the rest of the week with snow cover and cold temperatures over the area. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Wind Chill Advisory from 11 PM this evening to 11 AM MST Thursday for WYZ101-102. Winter Weather Advisory until 6 AM MST Thursday for WYZ103>105- 107>109. Winter Storm Warning until 6 AM MST Thursday for WYZ106-110>119. NE...Wind Chill Advisory from 11 PM this evening to 11 AM MST Thursday for NEZ002-003-095. Winter Weather Advisory until 6 AM MST Thursday for NEZ019-020- 054-096. && $$ UPDATE...GCC SHORT TERM...RE LONG TERM...CLH AVIATION...GCC FIRE WEATHER...RE
Area Forecast Discussion
National Weather Service Quad Cities IA IL
504 PM CST Wed Jan 4 2017 ...AVIATION UPDATE... .SYNOPSIS... Issued at 320 PM CST Wed Jan 4 2017 Arctic airmass was in place across much of the Midwest and there has been plenty of sunshine for much of the day in the dvn cwa. 3 pm temperatures ranged from 7 above at Dubuque to 21 at Keokuk. Elsewhere, a short wave trough was spreading an area of light snow into western Nebraska with high level clouds pushing eastward into the dvn cwa. && .SHORT TERM...(This Evening through Thursday) ISSUED AT 320 PM CST Wed Jan 4 2017 Forecast focus on snow tonight in our southern cwa. Tonight: Operational models similar in tracking a short wave trough across the area. Overlaying the dendritic growth zone (-12 to -18C) with the 100 percent RH and omega (vertical motion)the best location for the highest snow accumulations will be south of the dvn cwa. Across southeast IA, northeast MO and western IL the mean RH is about 85 percent, and farther north the saturation and lift decreases rapidly. The highest pops will be in our far south with only chance pops along Interstate 80. Farther north no precipitation is expected. The HRRR suggests the snow spreading into our southern counties during the mid to late evening then ending rather quickly by sunrise. Snowfall amounts should range from 1 to 2 inches in our far southern cwa, to up to 1/2 inch at Burlington. Farther north not expecting any accumulation. Lows will range from around zero along Highway 20 to around 12 in far northeast MO. During the snowfall the winds will be rather light so impacts appear minimal. Therefore, winter weather headlines will not be issued at this time. Thursday: In the wake of the trough even colder air builds southward with 850 mb temperatures dropping to -23C in our far north. 500 mb temperatures will be as cold as -36C which will set up steep lapse rates during the afternoon. Time height sections indicate limited low level moisture but there may be enough to support scattered flurries. Highs will be mainly in the teens, except around 10 along Highway 20. .LONG TERM...(Thursday Night through Wednesday) ISSUED AT 320 PM CST Wed Jan 4 2017 The main forecast concerns will be chances of precipitation through the period as well as wind chills. The models are in good overall agreement through the period. Below normal temperatures are expected through Sunday with a a deep trough across the eastern third of the US. Warm advection ahead of next weeks systems will raise temperatures back above normal on Monday and Tuesday with temperatures near normal by the middle of next week. In addition to the cold temperatures, wind chills may be an issue north of US Highway 30 on Friday morning and again on Sunday morning with wind chills of -15 to -20 below possible on both days. The active pattern continues through the long term with transitions from northwesterly flow to start to more of a zonal flow by early next week. Disturbances will pass to our north Friday night into Saturday as well as Sunday night into Tuesday. Currently, it looks like both systems will be moisture starved with the better chances of precipitation near the best support. An open/neutral 500 hpa wave will move across the region toward the end of the long term period on Tuesday and Wednesday with strong warm advection ahead of the wave. This will bring a warming trend as well as a chance precip changing from snow over to rain through the day on Tuesday and then back again overnight as slightly cooler air overspreads the region. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) ISSUED AT 459 PM CST Wed Jan 4 2017 Light snow expected to impact KBRL overnight, with mainly MVFR ceilings and visibilities after 05Z. The snow should end near 10z, followed by continued MVFR ceilings. Little or no snow expected to the north, with mainly low VFR ceilings developing overnight and continuing through the day Thursday. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...Haase SHORT TERM...Haase LONG TERM...Cousins AVIATION...RP Kinney
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
930 PM CST Wed Jan 4 2017 .UPDATE... /INCREASED LOW CLOUDS TO ALTER MINS...ADD DRIZZLE SE THURS/ Surface winds over the Rio Grande Plains can be seen turning southerly, and the BL winds on the recent RUC runs and VAD wind profiles confirm that the low cloud deck will mix out a bit more this evening, then surge north again. By daybreak, enough isentropic lift looks present to generate some light rain or drizzle over the Coastal Prairies on Thursday. Min Temperatures were modified slightly upward over the SE counties and downward slightly near Burnet. Given a longer period of cloud cover for tomorrow, Thursday Max T was lowered slightly over the eastern counties. && .PREV DISCUSSION... /ISSUED 548 PM CST Wed Jan 4 2017/ UPDATE... 00Z Aviation Update Below. AVIATION... A BKN stratus deck around 4K feet SAT-AUS may lower slightly through the evening. There is a chance it could lower into high end MVFR. The cloud deck should move east early Thu morning. Otherwise VFR conditions until Thu evening, at which time a MVFR stratus deck may develop behind another cold front. Weak SE-NE winds around 5 kts or less this evening. The winds should become light from the SW overnight and Thu morning at SAT/AUS. Pre-frontal SW-W 5-9 kts winds will develop Thu afternoon at SAT/AUS. The aforementioned cold front will arrive at AUS around 22Z Thu, SAT around 00Z Fri, and DRT 03Z Fri. N to NE winds 12-18 kts will initially develop behind the front, then strengthen and become gusty Thu night at SAT/AUS, with gusts 25-30 kts possible. PREV DISCUSSION... /ISSUED 209 PM CST Wed Jan 4 2017/ SHORT TERM (Tonight through Thursday Night)... Upper air analysis this morning showed zonal flow across the southern part of the country. At the surface, winds were from the north to northeast behind a cold front. Temperatures and dew points were five to ten degrees lower than 24 hours ago. The frontal boundary will come back through as a warm front tonight. Another cold front will drop through our CWA Thursday. This will all mean shifting winds and a warm day Thursday ahead of the front. Temperatures will drop Friday morning behind the cold front with freezing along and northwest of I-35. LONG TERM (Friday through Wednesday)... Friday the front will continue moving slowly away from our area and there will be a slight chance for precipitation across our south and east. Any precipitation should be in areas that stay above freezing and be rain. Friday night there could be some lingering rain in the extreme southeast. Saturday upper level ridging will build in from the west and move slowly across the Southern Plains over the weekend and into the beginning of next week. This will mean a dry period through the end of the forecast period. Cold air will settle in for the weekend and then temperatures will warm Monday through Wednesday. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 39 61 30 38 26 / 0 10 - 10 10 Austin Bergstrom Intl Airport 38 64 31 38 26 / 0 10 - 10 10 New Braunfels Muni Airport 41 67 32 39 26 / 0 20 - 10 10 Burnet Muni Airport 34 54 25 34 22 / 0 - - 10 - Del Rio Intl Airport 43 70 37 45 29 / 0 0 - 10 0 Georgetown Muni Airport 35 56 27 35 23 / 0 10 - 10 10 Hondo Muni Airport 43 71 35 41 26 / 0 0 - 10 - San Marcos Muni Airport 40 64 31 39 26 / 0 20 - 20 10 La Grange - Fayette Regional 42 63 34 40 28 / 0 20 - 20 10 San Antonio Intl Airport 43 69 33 39 28 / 0 10 - 10 10 Stinson Muni Airport 44 70 35 40 29 / 0 20 - 20 10 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...Runyen Synoptic/Grids...Oaks Public Service/Data Collection...Williams
Area Forecast Discussion
National Weather Service Hastings NE
542 PM CST Wed Jan 4 2017 .SHORT TERM...(This evening through Thursday) Issued at 355 PM CST Wed Jan 4 2017 The biggest issue will be determining snow amounts and this could be a bit tricky. Temperatures are cold enough for 20 to 30:1 snow ratios, and even though there is not a whole lot of moisture, the light and fluffy snow could add up to a good couple of inches this evening for some spots. After all is said and done, our total amounts should be in the 1 to 3 inch range with a localized 4 inch here or there. I like the HRRR the best for timing, and the snowfall could vary quite a bit with just a difference of a couple hundredths qpf. For now, I tamped down snow amounts a bit on the Nebraska side this evening, while later on tonight I increased amounts for north central Kansas to the 1 to 2 inch range as the band shifts south. Models indicate a potential of some lingering snow in the early morning on Thursday, but qpf amounts generally look fairly light. We`ll have to keep a close eye on north central Kansas in case they wind up with a bit more qpf, but I`ve already gone a few hundredths greater than Superblend as it stands now. Nonetheless, there could be a narrow band that develops that gives us more. .LONG TERM...(Thursday night through Wednesday) Issued at 355 PM CST Wed Jan 4 2017 For the rest of the forecast, the arctic blast persists for the work week and into Saturday, with a ridge ensuring a modest warmup into the 40s for Sunday into next week. Not much at all change has occurred from the previous forecast here. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday evening) Issued at 542 PM CST Wed Jan 4 2017 The main aviation forecast concern is the continuation of snow and how that will impact visibilities and ceiling height. Currently ceilings are hovering around 3000ft...but upstream, ceilings are in the MVFR range and expect that is possible at both KEAR/KGRI as well through the majority of the snowfall. Visibilities will drop with more moderate snow, but MVFR visibilities are also expected. Brief periods of lower visibilities are possible if a heavier band moves through, but this is not expected to be long lived. Will monitor this and amend if necessary. Winds are generally light and north to northeasterly. They will become more northwesterly through the period and gusty by afternoon Thursday. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Winter Weather Advisory until 6 AM CST Thursday for NEZ039>041- 046>049-060>064-072>077-083>087. KS...None. && $$ SHORT TERM...Heinlein LONG TERM...Heinlein AVIATION...Billings Wright
Area Forecast Discussion
National Weather Service Houston/Galveston TX
900 PM CST Wed Jan 4 2017 .DISCUSSION... Latest IR/11-3.9 micron satellite imagery shows low stratus clouds moving into SE Texas from the SW over S Texas. Obs show ceilings anywhere from 1500 to 5000 feet coming into the area. Latest HRRR seems to have initialized well enough with this scenario and analysis of 295K/290K shows some isentropic lift coming from the SW in line with cloud development in the satellite. This also corresponds well with warm advection in the 925-850mb layer. This means that temps overnight may actually warm a bit from current readings. Temps may drop another degree or two over the next couple of hours, but should rebound with increased cloud cover and warm advection. Based on hi-res mesoscale models, 20 PoPs were added to the forecast for tomorrow morning along the coast and ahead of the front tomorrow afternoon. Cold front pushes through SE Texas Thursday afternoon and evening. Look for temperatures to slowly fall with strong cold advection. Temperatures may only remain steady for slowly fall through the day Friday. That brings us to Friday night when a embedded short wave trough moves along the Red River. The NAM is a good 3-6 hrs faster with this shortwave than the GFS and the ECMWF is about 3-6 hrs slow. Canadian and GFS are fairly close. All the models show a weak vorticity max that appears to be getting stretched. Front at 850mb will be pushing through 00-06Z Saturday so there will be some low level lift along with Q-G large scale ascent. But looking at model soundings, moisture will be really limited. Doubt there will be any precip at all except along the coast after 06Z Saturday. Model soundings do moist below 700mb from 21Z Friday to 03Z Saturday but there is practically no moisture above -10C height. Temperature profiles do slide below freezing by 03Z Saturday in areas from Madisonville to Lufkin but due to the lack of moisture, precipitation type will likely be drizzle or freezing drizzle should surfaces be cold enough. Decided to modify the forecast for rain/drizzle/freezing drizzle precip type based on this as it will be hard to get any other precip type. Should there be much stronger lift than what is being shown by the models, then sleet will be possible. Overall this winter precip event for the northern most counties of the forecast area is very borderline, and there is a much higher chance of it not occurring than occurring. Overpeck && .PREV DISCUSSION... /ISSUED 543 PM CST Wed Jan 4 2017/ AVIATION... With clouds at MVFR levels beginning to crop up at several sites, have sped up the onset of MVFR ceilings a little bit this evening. Still unsure on low level moisture return, so hitting visibility reductions late tonight/tomorrow morning a little softer than the guidance still, and keeping them restricted from DWH/IAH coastward. With a cold front beginning to enter from the northwest at the end of the period, a wind shift will be in the offing, but at the end of this forecast period, only the northernmost sites should see that impact, and CXO to a limited extent. Luchs PREV DISCUSSION... /ISSUED 348 PM CST Wed Jan 4 2017/ DISCUSSION... Visible satellite imagery currently shows a high cloud deck scattered over much of SE Texas this afternoon. Expecting saturation to rise as winds shift from the north to out of the southwest, enhancing moisture due to weak onshore flow beginning Thursday morning. Forecast soundings have precipitable waters on the rise Thursday after the wind shift, and PoPs will rise slightly over the offshore waters. Therefore, a slight chance of showers can be expected over the offshore waters and along the eastern coastal zones Thursday afternoon. Early Thursday evening, a strong cold front begins to slide into the forecast area and will eventually clear the coast by Friday morning. Chances for precip will be on the rise ahead of the cold front Thursday evening. Overnight, in the northeastern zone of our forecast area will see some mix of light drizzle and wintery precip. Model guidance, especially indicative in the forecast soundings show dry air aloft in the mid to upper layers with a small layer of saturation closer to the surface. Temperature will be warmer than freezing at the surface while the precip is falling, and conditions will be drier than previous forecasted. Therefore, it appears as though the models are lacking confidence towards the precip being more ice pellets or sleet, but instead will more likely be drizzle or light rain. Eventually a large part of forecast area will fall below freezing temperatures, once the precip has pushed southward. Cold air will usher in behind the front, leaving temperatures below normal climatology for this time of year. High pressure will build in following the front. Expect the impact from this front to linger through the weekend, keeping things cold and breezy. A Coastal Wind Advisory may be needed along the immediate coast beginning sunrise Friday and through the afternoon. Friday and Saturday night we will see low temperatures slightly below normal climatology, remaining quite chilly. The warm up will begin Sunday, as the winds begin to veer Sunday afternoon. By next week temperatures will be back above normal for this time of the year. Hathaway MARINE... Maritime northeasterly winds will weaken through the overnight hours...becoming light onshore early Thursday as surface high pressure transitions from eastern Texas into the eastern United States. A light south to southwesterly wind over low seas with periods of light precipitation Thursday. A cold frontal passage Thursday evening will back winds around to the northwest to northeast while strengthening to advisory criteria during the day Friday. Post frontal cold air moving into the area tightening the offhsore pressure gradient will produce cautions for the bays and Gulf advisories through Saturday morning. As of now...there will be occasional gusts to near gale across the far offshore waters Friday that may prompt a Gale Watch. East winds will weaken going into and through Sunday. Friday wave heights will reach near 9 feet offshore...around 6 to 7 feet 20 nm from the response to those advisory level northerlies. Increasing moisture over cooler nearshore and bay waters early next work week heightens the late period sea fog threat. 31 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 42 62 34 41 26 / 0 10 10 20 10 Houston (IAH) 47 63 41 45 31 / 0 20 10 30 20 Galveston (GLS) 54 64 47 49 38 / 10 20 20 40 30 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ Discussion...39
National Weather Service Jackson KY
937 PM EST Wed Jan 4 2017 .UPDATE... Issued at 937 PM EST WED JAN 4 2017 Clouds are starting to make their way into north central KY ahead of the incoming disturbance. Updated sky grids to push clouds in an hour or two earlier than originally forecast, but overall the change is subtle. Pops and weather still seem reasonable with latest hi-res guidance, so did not adjust at this time. Loaded in the latest observations for temps, dew points, and winds to make sure the near term forecast was on track with the current conditions. Despite some slightly quicker temp drop offs so far this evening, expect incoming cloud cover to prevent continued steep falls throughout the overnight once it moves in. Otherwise, will continue to monitor temps in case the diurnal curve and/or low`s need to be adjusted. All changes have been published and sent to NDFD/web. A new forecast package will be sent out next hour to change to overnight wording. An updated WSW will also be issued before 11 pm, though overall information is expected to change little. UPDATE Issued at 653 PM EST WED JAN 4 2017 Clear conditions this evening across eastern Kentucky, with the loss of daytime heating allowing winds to calm over the last hour or so. Main update was to make sure the near term forecast reflected the ongoing conditions, so loaded in the latest observations from the last hour into the forecast. All changes have been published and sent to NDFD/web. No updates to the forecast packages will be needed at this time. && .SHORT TERM...(This evening through Thursday night) Issued at 425 PM EST WED JAN 4 2017 20z sfc analysis shows high pressure quickly building into the area with west to northwest winds bringing in colder air. Thanks to the sunshine this afternoon, and despite the CAA, temperatures did manage to tick up a notch this afternoon from morning lows. They still are running in the mid to upper 30s most places with low 30s found in the northwest. Dewpoints have come down through the area and are now in the 15 to 20 degree range most places. The models are in good agreement aloft through the short term portion of the forecast. They all depict a series of moderately strong short waves scooting through Kentucky in advance of a larger northern stream trough pivoting south into the Ohio Valley on Thursday and Thursday night. A 300 mb jet streak passing through Kentucky will help to generate lift through the area, particularly Thursday evening. Given the model agreement and trends have favored the model blend with a strong lean toward the HRRR in the near term and the NAM12 thereafter - through 12z Friday. Sensible weather will feature a chilly night under mostly clear skies through midnight. Clouds will increase, though. as a clipper system rapidly approaches. This moves into the area shortly after dawn with quick saturation of the lower levels and good lift into the dendritic zone from midday Thursday into the evening across the area starting in the northwest early and then spreading into the southeast toward sunset. The snow will continue into the night for most locations before tapering to light amounts and flurries Friday morning. The models have come into a consensus for a high range advisory snowfall for most places - the exception will be western parts of the Cumberland Valley where amounts will average from 1 to 2 inches. A WSW has been issued for the entire area starting Thursday morning and going into Friday morning. The CONSShort and ShortBlend provided a good starting point for most of the wx elements with only minor adjustments made to QPF to better hit the terrain effects and some spot temperature tweaks tonight/Thursday night. Also, beefed up the blended PoPs Thursday and Thursday night to hit 100 percent for a good portion of the time. .LONG TERM...(Friday through Wednesday) Issued at 508 PM EST WED JAN 4 2017 Models are in general agreement with mid/upper level synoptic scale features. And despite a very progressive pattern our weather will remain fairly quiet through the bulk of the extended. A deepening trough does sweep across the southeastern CONUS late Friday through Saturday, following on the heels of a first disturbance which will be exiting to our east early in the period. But the effects of this second storm system remain for the most part south of our area. Another trough then marches across the CONUS and into the Ohio Valley by the end of the extended. For sensible weather snow showers will be tapering off through the day Friday as our initial disturbance moves off to the east. However, precipitation associated with the second storm system tracking through the deep south may reach far enough north to affect our southernmost zones late Friday into Friday evening, effectively keeping some light snow going along the Kentucky- Tennessee-Virginia state line Friday evening. The ECMWF favors this solution but is a bit more of an outlier when compared with the GFS and Canadian. For now leaned towards the drier GFS and Canadian solutions for late Friday and Friday night. Another storm system will approach the Ohio Valley by Tuesday with precipitation possible over our Bluegrass counties early as Tuesday morning. Much colder air will be invading the area during the upcoming weekend. We will drop below freezing Thursday night and remain there through Monday morning. With H850 temps dropping to near -20 C, high temperatures will only climb into the 20s both Saturday and Sunday. Lows are expected to drop into the single digits Sunday and Monday mornings for a good portion of eastern Kentucky, especially our colder valley spots as a center of surface high pressure transits our area. Overnight lows could be even colder depending on how much snow cover we get with the exiting system Friday. Temperatures will dip back down into the mid 20s Tuesday morning after reaching the mid 30s on Monday. Thus any precipitation that overspreads the area Tuesday may begin as a wintry mix at the onset. But temperatures appear to increase quickly enough that precipitation should switch to just rain through the morning Tuesday and remain so through Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) ISSUED AT 707 PM EST WED JAN 4 2017 Clear conditions this evening across eastern Kentucky, with the loss of daytime heating allowing winds to calm over the last hour or so. VFR conditions will remain in place through much of the night. A disturbance will move across the region tomorrow, bringing chances for precip in the form of snow throughout much of the day and into the overnight Thursday night. CIGs will lower throughout the day Thursday, reaching low end MVFR by the end of the TAF period. Wouldn`t be surprised if CIGs deteriorated into IFR after this point. Snow will arrive in the afternoon at most TAF sites, though as early as 14Z at KSYM. Tried to time out scattered snow in the forecast with VCSH in the TAFS, and then numerous snow showers with predominate -SN. Llvl winds should remain light during this time with a surface high pressure center sitting across KY, however winds will increase substantially as you go aloft, with 50 knots expected through much of the day tomorrow above 7k feet as a mid level jet sets in across the region. Will not rule out some possible wind shear concerns during this time. && .JKL WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 8 AM Thursday to 8 AM EST Friday for KYZ044-050>052. Winter Weather Advisory from 10 AM Thursday to 8 AM EST Friday for KYZ058>060-068-069-104-106>109-111-112-114. Winter Weather Advisory from noon Thursday to 8 AM EST Friday for KYZ079-080-083>088-110-113-115>120. && $$ UPDATE...JMW SHORT TERM...GREIF LONG TERM...RAY AVIATION...JMW
Area Forecast Discussion
National Weather Service Omaha/Valley NE
627 PM CST Wed Jan 4 2017 .SHORT TERM...(tonight through Saturday) Issued at 245 PM CST Wed Jan 4 2017 Snow event tonight and temperatures during the period will remain primary concern in this forecast. A narrow band of light snow has persisted for much of the day across far southeast nebraska with more significant snow reported in western parts of the state. Surface reports and DOR cameras show little if any accumulation up to this point in southeast Nebraska with primary period of snow still indicated after 00Z. Recent RAP model however is trying to show a gap developing in the snow band across southeast Nebraska with primary axis focusing across northern Missouri. At this time will continue with current headlines across southern parts of the area for tonight along with 1-3 inch potential. Temperatures remain quite cold this afternoon ranging from near 10 north to the mid teens south at 20Z. Not much change expected in temperatures tonight into Thursday with readings similar to this morning and this afternoon as clouds hang on acrossd the area. As skies clear Thursday night and winds diminish should our coldest temperatures on Friday morning with most of the area seeing subzero lows. Depending on actual snowfall tonight the lows Friday morning may be even colder than current forecast. Slight moderation on Friday as winds become southwesterly but still rather cold into Saturday before a warming trend begins on Sunday. .LONG TERM...(Saturday night through Wednesday) Issued at 245 PM CST Wed Jan 4 2017 Upper ridge begins to build over the western CONUS Saturday night then works slowly east by Monday before flattening as next strong trough heads into the west coast. As the trough pushes eastward Monday night into Tuesday potential exists for another round of mixed precipitation but current models keep better chance to the north and east of the area. Not much change indicated to the overall pattern with strong zonal flow remaining through the upcoming week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 621 PM CST Wed Jan 4 2017 Forcing related to an upper level trough/mid level frontogenetic band/lift through the frontogenetic layer will yield MVFR/IFR conditions (FL015-035 and vsbys 1 to 5) with snow for the TAF sites through the evening hours. Patchy MVFR conditions will persist, however there will be general improvement to VFR 06Z to 09Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Winter Weather Advisory until 6 AM CST Thursday for NEZ065>068- 078-088>093. IA...Winter Weather Advisory until 6 AM CST Thursday for IAZ090-091. && $$ SHORT TERM...Fobert LONG TERM...Fobert AVIATION...Zapotocny
For frequently asked questions about the Area Forecast Discussion
Area Forecast Discussion
National Weather Service Topeka KS
937 PM CST Wed Jan 4 2017 .UPDATE... Issued at 919 PM CST Wed Jan 4 2017 Snowfall reports suggest that the forecast of very high snow:liquid ratios in the 17-22:1 range is coming to fruition as very light returns on radar are resulting in dendrite flakes and accumulating snow. Visibility has dropped to 1 mile or less at times. Current focus is over northeast KS mainly north of a Belleville to Holton line where the heavier snow should fall through 11 PM. Then a second focus is in the next wave producing areas of moderate snow in NW KS. This will move into the forecast area but may focus along and just south of I-70 with support from several updated model runs on that solution. Have thus increased snow amounts over southern parts of the area and now have a forecast of 1-3" for the entire forecast area and expanded the winter weather advisory accordingly. Still see potential for parts of Brown Marshall and Nemaha counties in particular to approach 4 inches. && .SHORT TERM...(This evening through Thursday) Issued at 309 PM CST Wed Jan 4 2017 Westerly to slightly northwesterly flow aloft this afternoon as water vapor imagery shows a shortwave trough deepening southward across the Dakotas. Meanwhile an elongated trough axis was stretched just off the Oregon coastline through Oregon into Idaho. In response at the sfc, a few areas of low pressure have developed across the northern CO and UT areas. Narrow area of frontogenesis ahead of the sfc low in northern CO stretched across southern NE has developed areas of light snow this afternoon. Despite the dry airmass below 850 mb, persistent evaporative cooling has allowed a few locations near the Kansas and Nebraska border to observe light snow falling for a brief time, therefore have kept the chances for light snow near the border through 00Z. Forecast for the evening has remained mostly unchanged with the exception of slight changes in snowfall amounts being increased west of the previous Winter Weather Advisory. Current analysis was mostly driven by short term guidance from the 4 km WRF solutions along with the several runs of the HRRR and Rap models. These models have been fairly persistent in developing snowfall across the northern portions of the cwa in the 00-03Z time frame, with snow chances becoming likely for much of the CWA by 06Z. Cross sections reveal a brief time aft 06Z of mid level frontogenesis being aligned with slightly negative epv values to enhance snowfall rates across areas along and just north of Interstate 70. Short term guidance would also suggest the heavier qpf amounts and associated snowfall to push east towards far east central Kansas from 09Z to 12Z on Thursday. This would differ slightly with the ECMWF, GFS, and SREF which produce a few hundredths more of qpf, commence snowfall earlier this evening and end precip later on Thursday, resulting in snowfall amounts up to 4 inches in Brown county. Overall consensus lead me to adjust snowfall totals to add higher amounts further west towards the Concordia and Manhattan areas from 1.5 to 2 inches. Another tier of counties was added to the Winter Weather Advisory still expected to go into effect at 00Z tonight. Total snowfall accumulations still reside in the dusting to 3 inch range, with locally higher amounts up to 4 inches possible. Snowfall tapers off Thursday late morning from west to east as residual lift from the upper wave exits the area. Skies remain mostly cloudy through the day with lows starting out in the teens. Highs are mostly in the upper teens to near 20 degrees. Winds tonight are not too much of an issue from the north at 5 to 10 mph, however they increase Thursday afternoon from 10-15 mph sustained, causing some blowing or drifting snow. .LONG TERM...(Thursday night through Wednesday) Issued at 309 PM CST Wed Jan 4 2017 Once the quick storm system passes east of the area on Thursday, models show dry conditions prevailing for the region through early next week. With the mid-level trough shifting to the east and surface high pressure advancing into the Northern and Central Plains Thursday night, the northwesterly flow over some snow pack will support caa into Friday. As a result, frigid conditions are expected Thursday night with lows near the 0 degree mark and wind chill values plunging into the -3 to -12 range. High temperatures on Friday will be well below the seasonal normals with readings only in the upper teens to low/mid 20s. This weekend the mid-level trough will be stretched across the eastern U.S. with a ridge in place over the western U.S. With surface high pressure slowly shifting east of the area, temperatures will gradually moderate over the weekend into early next week with the return of southerly flow. Surface low pressure will move into the High Plains region Sunday night into Monday with the decent southwesterly flow supporting waa over the CWA. As a result, high temperatures should rise into the 40s on Monday and into the 50s for Tuesday before a weak cold front tracks eastward Tuesday/Tuesday night. There is still model uncertainty with whether or not any precipitation will develop along the front, but have dry forecast going at this time. The frontal passage will likely drop high temperatures back into the 40s for Wednesday. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 919 PM CST Wed Jan 4 2017 Snow will impact all TAF sites this evening through approximately 08Z-10Z before coming to an end. Within the snow, expect visibility to periodically fall to 1SM but should otherwise be mainly in the 3-5SM range. Cigs will generally be in the 1000-2000 ft range during snow, increasing to VFR as snow ends. While a few snow showers may continue after 10Z, VFR conditions are likely. && .TOP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 AM CST Thursday for KSZ008>012- 020>024-026-034>040-054>056-058-059. && $$ UPDATE...Barjenbruch SHORT TERM...Prieto LONG TERM...Hennecke AVIATION...Barjenbruch