Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/16/19

Area Forecast Discussion
National Weather Service Bismarck ND
917 PM CST Sun Dec 15 2019 .UPDATE... Issued at 917 PM CST Sun Dec 15 2019 A thin band of snow moved southeast through Bismarck about an hour ago and dropped barely enough snow to cover the parking lot here at the office. Adjusted POPs both south-central and up north in the Minot area where light snow is moving east. Although visibilities are still fine everywhere, opted to continue the patchy fog in the southwest for a few more hours, and slightly increased the spatial area as well. The latest RAP and HRRR runs are becoming more insistent on dropping visibilities overnight, and BUFKIT soundings for points in the far southwest and across the border into Montana also signal fog development. UPDATE Issued at 553 PM CST Sun Dec 15 2019 Low stratus deck is overtaking the northern and east-central parts of the forecast area, with mid-level clouds southwest. Expanded POPs slightly to the south with Beach reporting snow as of 2330 UTC. Also added in patchy fog in the southwest for the next few hours, with a few travel webcams showing fog near the ND/MT border. BUFKIT soundings and high-res model guidance are somewhat consistent with areas of fog developing overnight, so will keep an eye on things and possibly expand patchy fog east with the next update. && .SHORT TERM...(This evening through Monday) Issued at 150 PM CST Sun Dec 15 2019 A warm front continues to push eastward through the state this afternoon and a cold front is diving south out of Canada. There may be a brief period late this afternoon when some clearing occurs across the southwest, but all areas are expected to once again fill in with stratus as the cold front quickly advances. Some real light and brief snow is possible across western North Dakota this evening as the short-term models show a small area of mid-level lift associated with the passing wave. Tomorrow will be a near carbon copy of today with perhaps less cloud cover. .LONG TERM...(Monday night through Sunday) Issued at 150 PM CST Sun Dec 15 2019 Dry and milder weather highlight the extended forecast. The 12 UTC global suite favors a transition from northwest flow aloft to mean upper level ridging across the Northern Plains mid and late next week. Thus a period of above normal temperatures is expected mid to late next week with widespread highs in the 20s and 30s, and maybe even a few 40s across the far southwest. This is also favored by ensembles as well which depict a much higher than average temperature signal favored through next weekend. At this point, no precipitation is in the forecast in the extended. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 553 PM CST Sun Dec 15 2019 Widespread stratus across western and central North Dakota with an IFR cloud deck overtaking northern and east-central ND, and VFR ceilings southwest. Some scattered light snow is possible tonight, but low confidence in exact location so only have VCSH at KDIK/KXWA. Patchy fog is also possible in southwest North Dakota through the night. Winds will generally be from the west at 5 to 10 knots, increasing to 10 to 15 knots tomorrow afternoon. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...MJ SHORT TERM...AJ LONG TERM...AJ AVIATION...MJ
Area Forecast Discussion
National Weather Service Dodge City KS
450 PM CST Sun Dec 15 2019 ...Updated Aviation... .SHORT TERM...(Today and tonight) Issued at 300 PM CST Sun Dec 15 2019 Winter weather event Number 1 has come and gone without much fanfare across southwest Kansas. We had one narrow band of moderate snow develop and move across the area earlier in the day, but this didn`t leave any more than around a half inch of snow at any one location. Round Number 2 is still on the way, and appears to still be on track for affecting areas mainly south of the Arkansas River to the Oklahoma border. The last several runs of the HRRR have lined up fairly well with the other 12Z high resolution model runs, if not maybe a little bit north closer to the Arkansas River. It all depends on how far north (if at all) the 700mb baroclinic zone can push back into southwest Kansas after the first wave pushed it south a bit. The latest Snow Amount grids will show around an inch of snow south of a Richfield to Sublette to Greensburg to Pratt line with around 2 inches from Ashland to Medicine Lodge. We will maintain the same counties in the Winter Weather Advisory, but we will need to watch areas like Liberal to Meade and perhaps even Ford County should the mid level frontogenetic zone shift farther north than currently expected. All snow should exit the DDC forecast area by late Monday morning. Temperatures will not rise much above the lower 30s most areas on Monday behind the storm system. .LONG TERM...(Monday through Saturday) Issued at 330 PM CST Sun Dec 15 2019 Very quiet weather is forecast the remainder of the week as large scale high pressure ridging develops across much of the western and central CONUS. A small upper low will undercut this ridging late week, but it should pass far enough south such that it will not impact western Kansas much at all, other than a wind shift. Temperatures will continue to warm through the week with highs in the 50s starting Wednesday. The end of this forecast period looks particularly mild, if not warm Sunday as good downslope conditions develop, allowing the 700-850mb temperatures to really warm up across the Central and Northern Plains. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 449 PM CST Sun Dec 15 2019 An upper level wave will move from the four corners region into southwest Kansas tonight which will drop the cloud ceilings to IFR conditions for all TAF sites with possible LIFR conditions for DDC and LBL. Light snow will develop mainly after 03Z for LBL and surface visibilities will be reduced from 05Z-10Z. Snow showers could be in the vicinity of GCK and DDC during this time as well however the snow band from forecast models will be in a narrow corridor (as a result amendments are possible). As the wave departs eastward cloud ceilings should rise to MVFR conditions after 14Z and VFR conditions after 20Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 19 36 17 41 / 40 30 0 0 GCK 19 37 15 41 / 30 10 0 0 EHA 21 37 16 42 / 70 30 0 0 LBL 19 37 14 42 / 70 60 0 0 HYS 15 35 15 41 / 20 10 0 0 P28 20 34 17 42 / 70 70 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until noon CST Monday for KSZ065-066- 078>081-084>090. && $$ SHORT TERM...Umscheid LONG TERM...Umscheid AVIATION...Tatro
Area Forecast Discussion
National Weather Service Hanford CA
206 PM PST Sun Dec 15 2019 .SYNOPSIS...High pressure ridging Monday and Tuesday will keep weather quiet before another possible storm system impacts Central California during the middle of next week. High pressure will return for late in the week with dry weather and a warming trend. A potentially stronger storm may impact the area next weekend. && .DISCUSSION...Visible imagery shows some upslope low clouds banked up along the valley facing slopes of the Tehachapi Mountains and over the far south end of the San Joaquin Valley while some strato-cumulus is developing over the Sierra foothills. Skies are mainly clear elsewhere in out area at this time. Mesowest observations are indicating winds have been decreasing today after frequently gusting above 45 mph overnight and this morning across the Kern County mountains and Deserts. HRRR indicating winds will continue to decrease through this evening as high pressure builds inland into CA. Temperatures are generally running 3-6 DEG F below yday at this time as a cooler airmass settles into the area. WRF indicating an a dry upper ridge pushes inland into CA. This will result in skies clearing out and decreased winds across the area. Radiational cooling in the San Joaquin Valley will allow for some patchy fog to develop overnight. With lows anticiapted to be in the mid 30s tonight at most locations areas of frost are likely although a freeze is not anticipated. The ridge is expected to continue building inland Monday through Tuesday. An offshore gradient developing over Socal on Monday will result in a Santa Ana type wind event Monday night and Tuesday which might impact Kern County. Later shifts will need to monitor this situation for possible wind highlights for the Tehachapi and Fort Tejon areas Monday night through Tuesday evening. The offshore winds will result in some additional drying over the area and may allow for temperatures to drop below the freezing mark at some locations in the San Joaquin Valley if skies remain clear. The offshore gradient will decrease by Tuesday night as the next upper level low pressure system approaches central CA. This system is progged to move through the area on Wednesday. RH progs are not showing much moisture with this system and progged QPF`s are generally very light. Between a tenth and a quarter inch of liquid precipitation for the central Sierra and just a few hundredths of an inch at most for the remainder of our area. The medium range models and their ensemble means are in good agreement with another dry ridge pushing through CA Thursday and Friday which will bring another period of dry weather to our area along with a warming trend. A fairly strong trough is still anticiapted to impact our area next weekend agreement with a the models coming into better agreement with a Saturday night to Sunday time frame as a period of significant precipitation across our area. && .AVIATION...Areas of MVFR and mountain obscuring IFR in low clouds over the Tehachapi Mountains near Fort Tejon and Tehachapi thru 04Z Mon. Areas of MVFR and local IFR in mist over the San Joaquin Valley between 10Z Mon and 18Z Mon. Otherwise, VFR conditions will prevail across the Central CA Interior for the next 24 hours. && .AIR QUALITY ISSUES...On Monday December 16 2019... Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno and Kern Counties. Further information is available at && .CERTAINTY... The level of certainty for days 1 and 2 is medium. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ public...DS aviation....DS
Area Forecast Discussion
National Weather Service Wichita KS
603 PM CST Sun Dec 15 2019 .SHORT TERM...(This evening through Monday) Issued at 216 PM CST Sun Dec 15 2019 Water vapor imagery shows initial impulse lifting across central/eastern KS with a more pronounced piece of energy approaching the For Corners region. Upgraded a few of our northeast counties to a warning a few hours ago to account for ongoing banded snow along with the potential for additional snow Mon morning. Impressive area of banded snow has been ongoing over the last several hours over northeast into parts of central KS with numerous snow reports around 6 inches with moderate to heavy snow still occurring. Even had some lightning show up GLM southeast of Saline county a couple hours ago. Morning runs of both the NAM and RAP did a good job showing enhanced area or frontogenesis along with increased omega in the snow growth region. This area of enhanced snowfall is expected to be moving out of our forecast area by around 4 pm. Further south, have had steady freezing drizzle since early this morning for areas generally south of Highway 50. This also should slowly diminish as the better low level isentropic lift shifts east. Attention then turns to the main vort max which is expected to move out into the Plains late tonight into Mon morning. Short range models have come into good agreement in developing another band of snow across south central KS, generally starting around 3 am. There is good model agreement in some impressive elevated instability at the onset of the precip, along with good frontogenesis. So not out of the question to see some thundersnow/sleet as the initial mid level warm advection moves into south central KS. There is some differences with the placement of the heavier snow. The NAM/RAP lift it a bit further north, more along a Hutch to Marion line, with the GFS/ECMWF more along a Wichita to Emporia line. So at this point feel confident enough to increase snow totals after midnight for much of south central KS into the 2-5 inch range. Snow should decrease from west to east Mon afternoon with most of it gone by 00z Tue. .LONG TERM...(Tuesday through Sunday) Issued at 216 PM CST Sun Dec 15 2019 Upper trough will stretch from the Ohio Valley into the southern Plains by 12z Tue as upper ridging builds over the western CONUS. Upper ridging will pass over the area through Thursday with good agreement between the GFS and ECMWF in a shortwave moving out into the Plains Fri. With lack of moisture, not expecting this wave to have much of an impact. We look to get back into a warming pattern for the weekend as the upper low pushes off to the southeast. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 545 PM CST Sun Dec 15 2019 Widespread MVFR and IFR cigs remain across the area in the wake of the initial shortwave trough. Meanwhile, another robust mid/upper trough can be seen spinning across the central Rockies. This system will continue moving eastward emerging across the Central Plains late tonight and into Monday bringing another round of snow and a continuation of IFR and MVFR cigs and visibilities to much of the region. Snow is expected to expand in coverage after 05-07Z and linger across much of south central and east central Kansas through 20-21Z on Mon. Northerly winds will persist across the region with speeds in the 10-15 knot range for most areas. && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 21 31 16 39 / 70 80 0 0 Hutchinson 20 31 16 39 / 50 80 0 0 Newton 20 29 16 37 / 50 80 0 0 ElDorado 20 29 16 37 / 50 90 10 0 Winfield-KWLD 22 32 18 41 / 70 80 0 0 Russell 16 32 15 39 / 20 20 0 0 Great Bend 16 33 16 40 / 30 30 0 0 Salina 17 32 15 38 / 30 40 0 0 McPherson 18 31 16 38 / 40 60 0 0 Coffeyville 25 33 20 43 / 50 50 10 0 Chanute 23 30 17 38 / 40 70 20 0 Iola 22 29 16 36 / 40 80 20 0 Parsons-KPPF 24 31 19 41 / 50 60 20 0 && .ICT WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 PM CST Monday for KSZ032-033-047- 048-050-067>072-082-083-091>096-098>100. Winter Storm Warning until 6 PM CST Monday for KSZ049-051>053. && $$ SHORT TERM...RBL LONG TERM...RBL AVIATION...MWM
Area Forecast Discussion
National Weather Service Lincoln IL
835 PM CST Sun Dec 15 2019 .SYNOPSIS... Issued at 835 PM CST Sun Dec 15 2019 Snow will continue to impact a large part of central Illinois through the evening, while it mixes with or changes to freezing rain near and south of I-70. This precipitation will taper off after midnight, though some patches of light snow or freezing drizzle may linger. Monday morning should be dry in many areas, before the next round of precipitation arrives around midday. Locations near and south of I-72 will be most impacted by this second wave of precipitation, which will linger into Monday evening. && .UPDATE... Issued at 835 PM CST Sun Dec 15 2019 Winter Weather Advisory was expanded northward to include the remaining 5 counties in the northern CWA until midnight. Recent reports around 2 inches have been received in the Peoria area, and the snow will continue the remainder of the evening there, before tapering after midnight. Elsewhere, heaviest snow has occurred from near Charleston to just south of Springfield, with 4 to 6 inches reported thus far. Significant forcing occurred in this area earlier, though the greatest EPV has shifted into Indiana. Latest radar mosaics showing this same area as the southern edge of the main snow area. South of that, surface reports near and south of I-70 have steadily been showing a transition to unknown precip on the automated obs, which generally indicates sleet or freezing rain occurring. Last few runs of the HRRR had a good handle on that, and show this occurring through midnight. Based on forecast soundings showing a loss of ice crystals after that, freezing drizzle was added after midnight as far north as I-72. && .SHORT TERM...(This evening through Monday) ISSUED AT 255 PM CST Sun Dec 15 2019 Analysis of the progression of the storm through today was shown by the radar mosaic, with banded pcpn pattern over MO, having moved into Illinois this afternoon. SPC mesoscale analysis indicated strong warm advection forcing by 850mb southerly jet from AR into southern Mo and IL, with very good 850mb moisture transport. Isentropic lifting therefore significant in the frontal zone from east central MO into souther central and central IL, which is expected to continue through evening hours. Banded pcpn with this system still seems to be significant, with lift enhanced by EPV forcing shown in SPC mesoanalysis ahead of the 850mb low in KS. Moisture channel satellite imagery continued to define the main upper jet axis across northern MO into northern IL. Jet axis north of the main low level frontal zone and serving to enhance the lift of the warm advection, isentropic lift. Loop of the IR imagery has been depicting development zone of the pcpn over central MO and this area advected into IL. This trend of banded snow development should be the main focus through evening hours. Satellite also shows the back edge of mid level short wave from eastern NE into northern central OK. Movement eastward will continue on this feature, as it reaches IL overnight, and finally ends the pcpn by morning. Then, before the next system, there will be a lull through much of the day on Monday. The next system is more upper level dynamic driven, as the main upper short wave trough is progged to move through. Difference in today`s model forecast is the low level boundary by Monday will be farther southeast and so when the upper level system moves through Monday afternoon, the amount of lift will be weaker and the tap of moisture will be more limited. Snow amounts with that system will be less. With the ongoing pcpn impacts expected, will keep the current warnings and advisories going and as conditions warrant, they will be updated appropriately. .LONG TERM...(Monday night through Sunday) ISSUED AT 255 PM CST Sun Dec 15 2019 Pcpn continuing into the overnight hours, ending by Tuesday morning. Rest of forecast period is dry. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 534 PM CST Sun Dec 15 2019 Mosaic radar display continued to show banded snow in east-west orientation over central IL in the strong warm advection pattern over region. SPC analysis continued to show the strong isentropic lift region, with upper shortwave gradually advecting east over western IA. Cigs and Vsbys are extremely variable in the banded pcpn pattern, with IFR conditions when a heavy snow area moves through and then some improvement in Vsbys after it passes. TAFs reflect variability. Models continue to move snow development region to the east later tonight, keeping the cigs down in the IFR category. Next wave on Monday afternoon, brings Vsbys down again in southern TAF sites, but not as strong as with this first wave. && .ILX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until midnight CST Monday night for ILZ036>038-040>048-071>073. Winter Storm Warning until midnight CST Monday night for ILZ049>057-061>063-066>068. Winter Weather Advisory until 6 AM CST Monday for ILZ027>031. && $$ UPDATE...Geelhart SYNOPSIS...Geelhart SHORT TERM...Goetsch LONG TERM...Goetsch AVIATION...Goetsch
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
930 PM CST Sun Dec 15 2019 .UPDATE... Issued at 915 PM CST Sun Dec 15 2019 I have made some big adjustments to the forecast for Monday. In the short term the tonight period is evolving pretty much as expected. The coverage of snow continues to diminish this evening across the northern CWA as forcing shifts to the east with the translation of a weak low amplitude short wave, and any additional snow accumulations will be quite light this evening. This area will eventually see a loss of cloud ice overnight and transition to freezing drizzle with light glazing possible. Further south we have already lost cloud ice across most of the area along and south of I-70 and thus freezing drizzle will dominate the remainder of the night with light glazing expected. The new 00z NAM and at least the last 3 runs of the RAP are now indicating much higher snow totals on Monday. An impressive deformation zone is expected to evolve in response to large scale forcing for ascent associated with a impressive migratory short wave, strengthening mid level frontogenetic forcing, and divergence within the entrance region of an ULJ streak. This band should evolve during the morning and strengthen thru the afternoon spreading from southwest/south central MO along a Rolla- St. Louis-Litchfield line. Snow should exit to the east during the evening. Snowfall rates within this band will approach an inch per hour at times. I think additional snow accumulations with the band will be in the 3-5 inch range along the aforementioned axis centered through St. Louis. No changes to headlines are warranted at this time. Glass Issued at 727 PM CST Sun Dec 15 2019 I have made a quick update for this evening to account for the more persistent narrow snow band currently extending from near Wellsville MO through Kampsville to Palmyra IL. This band is likely producing rates up to an inch an hour. I think it will persist another hour or two gradually pulling east-northeast and weakening. Storm totals within the vicinity of this band could be in the 6-8 inch range. Along and south of I-70 the loss of cloud ice has brought an end to measurable snow tonight and freezing drizzle should be the predominant ptype with light ice accumulations. Glass && .SHORT TERM... (Through Late Monday Night) Issued at 331 PM CST Sun Dec 15 2019 Early this afternoon, a very broad-based TROF extended over much of the CONUS with a W-SW flow aloft/WAA regime over our region. The strong storm system that we have been watching carefully was near the Four Corners region in the southwest CONUS. At the surface, an area of high pressure was centered over northern Illinois and central Indiana with easterly flow over our region. A developing surface inverted TROF was poking into southwest MO. Skies were overcast across our region. Of most note was the heavy snow band as forecast, but this has now drifted through much of the I-70 corridor and is looking to settle a bit more in position through early this evening. Temperatures were in the 20s for areas near and north of I- 70 and into the low 30s for areas south of I-70. The WAA snow, locally enhanced by strong frontogenesis with that heavy snow band just north of I-70, will gradually exit this evening being replaced by a regime exhibiting a loss of cloud ice and weak WAA. In addition, the inverted surface TROF will track east across Missouri and southern Illinois and should create low level convergence to develop areas of freezing drizzle for much of tonight. This will continue into early Monday morning. The main system is still expected to track E-NE through the main flow and approach and move by our region later on Monday and into Monday night. Lift will deepen, restore cloud ice to much of the area, and result in an expansion of snow later on Monday morning and continue through Monday evening before finally pulling out. The best areas for additional snow accumulation look to be near and north of I-70 with a snow/freezing rain scenario continuing for areas further south. The upper level LO tracks continue to favor what looks to be an additional 2-3" of snow possible for many of the same areas affected by the heavy snow band today. Between the already fallen/expected snow accums and forecasted ice accums, much of the Warning/Advisory stratification looks justified and will continue with this issuance. TES .LONG TERM... (Tuesday through Next Sunday) Issued at 331 PM CST Sun Dec 15 2019 The weather still looks relatively quiet for Tuesday through next Sunday. Cold temperatures are still expected Tuesday and Wednesday as a cold high pressure system builds into Missouri and Illinois behind the storm...especially Tuesday night when light wind, fresh snow and clear sky will produce excellent radiational cooling conditions. Highs mainly in the low to mid 30s and lows in the teens to low 20s continue to look reasonable. Wind turns back to the south on Thursday as high pressure moves into the Ohio Valley and further east. Widespread highs in the 40s with even some low 50s in southeast Missouri look likely with lows mainly in the 30s. There`s still a possibility of a little rain on Friday. The ECMWF and GFS are in good agreement that a shortwave trough will move from the Great Plains through the Midwest Friday into Friday night. However, the GFS has a more progressive trough than the EC does. It`s also been consistently printing out very light QPF ahead of the trough, while the ECMWF has been alternating dry-wet-now dry again. Am keeping the forecast dry at this time as the QPF that the GFS prints out is very light and will likely have little or no impact even if it does rain. Saturday and Sunday continue to look dry with highs in the 40s and lows in the 30s. Carney && .AVIATION... (For the 00z TAFs through 00z Monday Evening) Issued at 542 PM CST Sun Dec 15 2019 Poor flight weather is expected across the region through the period. Along and axis from KCOU to the St. Louis metro there could be a mix of ptypes for the first part of this evening including -SN, -IP, and -FZDZ however the tendency as the evening progresses should be for predominately freezing drizzle producing light ice accumulations. At KUIN, snow will prevail until around mid evening and the tendency should be for freezing drizzle as well. Another round of snow will spread across the area on Monday morning. Flight conditions will be dominated by IFR across the region. SPECIFICS FOR KSTL: Poor flight weather is expected across the region through the period with IFR flight conditions dominating. There could be a mix of ptypes for the first part of this evening including -SN,-IP, and -FZDZ however the tendency as the evening progresses should should be for predominately freezing drizzle producing light ice accumulations. Another round of snow will spread into the terminal around 14-15z Monday morning. Glass && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Winter Weather Advisory until midnight CST Monday night for Crawford MO-Iron MO-Knox MO-Lewis MO-Madison MO-Marion MO- Reynolds MO-Saint Francois MO-Sainte Genevieve MO-Shelby MO- Washington MO. Winter Storm Warning until midnight CST Monday night for Audrain MO-Boone MO-Callaway MO-Cole MO-Franklin MO-Gasconade MO- Jefferson MO-Lincoln MO-Moniteau MO-Monroe MO-Montgomery MO- Osage MO-Pike MO-Ralls MO-Saint Charles MO-Saint Louis City MO-Saint Louis MO-Warren MO. IL...Winter Weather Advisory until midnight CST Monday night for Adams IL-Brown IL-Randolph IL. Winter Storm Warning until midnight CST Monday night for Bond IL- Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey IL- Macoupin IL-Madison IL-Marion IL-Monroe IL-Montgomery IL- Pike IL-Saint Clair IL-Washington IL. && $$ WFO LSX
Updated for 00Z Aviation Forecast Discussion below.

&& .PREV DISCUSSION... /issued 314 PM CST Sun Dec 15 2019/ DISCUSSION... A potent trough continues to take shape over the Southern Rockies this afternoon. Mid-level height falls are spreading eastward into the Plains aiding in the development of a surface cyclone along a stationary front in central TX. The cold front that moved through the Mid-South yesterday is now lifting poleward across north MS as a warm front. Analysis as of 3 PM places this front from near the Interstate 40 corridor. Warm sector dewpoints are creeping back into the 50s with temperatures approaching 60F in a few areas. North of the front, temperatures are mainly in the 40s. Strong, quasi-zonal flow aloft will gradually become more southwesterly through tomorrow as the trough approaches. The attendant upper-tropospheric jet will begin to shift to the east tonight, placing the Mid-South in the right entrance region, a favorable location for forced ascent. We`ve already seen scattered light radar returns in the warm sector but rain and drizzle will continue to develop north of the warm front as moist, isentropic ascent continues over the frontal zone. Light rain may be widespread north of I-40 by sunset and will continue through the overnight hours as the warm front stalls. Some elevated instability will be present late tonight and may support a few rumbles of thunder. As the trough approaches the region tomorrow, the TX surface low will zip northeastward along the stationary front. This will maintain the warm sector over northeast MS (and possibly into extreme southwest TN) as southerly winds continue east of the surface cyclone. Instability is forecast to increase in the warm sector with MLCAPE peaking between 500-1000 J/kg tomorrow afternoon. Shear will be quite strong across the region with long, cyclonically curved hodographs. There remains a potential for some strong to severe storms, mainly during the afternoon hours across north MS, while the threat will be minimal north of I-40. The primary hazard will be damaging wind, but there is also a threat for large hail and a tornado or two. CAM ensemble guidance continues to show the most significant updraft helicity swaths south of the CWA, perhaps as far north as Tupelo. Post-frontal rain will end from west to east Monday night as the upper-level trough axis crosses the region. There is a brief window where some lingering light rain could mix with light snow, but it shouldn`t amount to anything as it quickly ends before sunrise. A cool and dry air mass will settle over the region Tuesday with temperatures in the mid 40s. Shortwave ridging aloft will promote light winds and clearing skies, setting the stage for a chilly Wednesday morning. Expect lows in the low/mid 20s in most areas. We`ll otherwise see a nice weather period midweek as the dry spell continues through Thursday night. Temperatures will moderate back into the lower 50s for highs and 30s for lows, which is pretty close to climatology for mid- December. A progressive trough will move across the region Friday into Saturday, providing another chance of rain for the Mid-South. QPF doesn`t look impressive with this system and dry weather should return by Saturday evening. Medium range models indicate some upper-level ridging Sunday into early next week. This should provide for a quiet start to the work week with temperatures on a slow warming trend. MJ && .AVIATION... 00Z TAFs Weak surface front along a MEM-MKL line will sharpen up this evening, with influx of additional maritime moisture. KGWX VAD wind profiler showed FL030 winds from 210 degrees at 65 to 70 knots just prior to 00Z. Despite clearing noted on GOES IR imagery lifting into north MS, expect the maritime air to cloud up at least a bit through the evening. Regarding TS chances, HRRR and NAM 3km convection-allowing models (CAMs) did not depict much in the way of TS overnight, while GFS LAMP guidance painted a broad swath of 40 to 50 percent chance TS through MEM and MKL. For the 00Z TAFs, have left VCTS in overnight - but with lower than normal confidence. Main impact will be LLWS, associated with the aforementioned FL020 winds. PWB && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion
National Weather Service Nashville TN
830 PM CST Sun Dec 15 2019 .DISCUSSION... Rain event is underway as strong WAA has commenced over our area, with a warm front now having moved northward to near a Waverly to Livingston line. Warm front should continue northward but stall near the KY border before oscillating back and forth over our northern zones through the day tomorrow per HRRR model. Showers that developed earlier over our northwest counties continue to increase in coverage and intensity, and GFS forecasts K-index values to rise well into the 30s in the next couple of hours. Thus anticipate some thunderstorms to develop over our northwest zones as well. Rain and thunderstorms should continue to focus near and on the cool side of the stationary boundary tonight into tomorrow, leading to an southwest to northeast axis of heavy rainfall somewhere over our northwest half. Exactly where this axis sets up remains somewhat in question as models continue to differ with placement from north to south, with NAM furthest north and GFS furthest south - but model consensus shows the most likely scenario to be a swath of 1 to 3 inches of rainfall in the vicinity of a line from Linden to Nashville to Westmoreland. Some flooding will be possible along this axis of heavier rainfall on Monday, especially in the afternoon and evening, when rainfall rates are heaviest. Have adjusted temps and pops based on this latest forecast reasoning, radar trends, and surface obs. Concerning the severe potential, models are keeping most of the warm sector free from thunderstorm activity until very late tomorrow afternoon and mainly tomorrow evening when the main surface low ejects northeastward across our area. With the low track bisecting Middle Tennessee, main severe weather threat will remain off to our south across Mississippi and Alabama, but cannot rule out a strong or severe thunderstorm across our far south and east counties. MLCAPE will struggle to reach 500 J/Kg in our area, but low level and deep layer shear will be extremely strong, so a few storms could contain damaging winds and hail. This is true even along the cool side of the stationary front due to considerable elevated instability. If enough instability can make it this far north, an isolated tornado is not out of the question in our far southern and eastern Middle Tennessee, but this remains questionable. The midnight shift should get a better handle on the severe weather threat as the full suite of CAMs comes into range overnight. && .AVIATION... 00Z TAF DISCUSSION. BNA/MQY/CKV...VCSH has already started with VFR skies. Expect skies to become MVFR by 03Z. Gusty westerly winds of 15-20 kts expected through the night and becoming southerly. -DZ should begin around 03Z for CKV and -SHRA after 06Z for BNA and MQY. Also expect LLWS from 06Z-15Z. By sunrise CIGs will become IFR/LIFR as the rain increases in intensity. Also including some -TSRA after 21Z. CSV...VFR will take some time for the showers to reach the terminal in the east and have this happening after 05Z when CIGs become MVFR. Winds will be southerly and gusty 10-20kts. Also expect LLWS from 06Z-15Z. As the cold front sweeps through tomorrow IFR/LIFR conditions expected along with -TSRA. && .PRELIMINARY POINT TEMPS/POPS... Nashville 52 61 37 42 25 / 90 100 100 10 0 Clarksville 45 50 34 41 24 / 100 100 100 10 0 Crossville 47 62 40 41 22 / 50 100 100 30 0 Columbia 54 65 37 43 25 / 90 100 100 10 0 Lawrenceburg 54 67 39 44 25 / 70 100 100 10 0 Waverly 49 54 35 41 25 / 100 100 100 0 0 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......Shamburger AVIATION........12
Area Forecast Discussion
National Weather Service Pocatello ID
140 PM MST Sun Dec 15 2019 .SHORT TERM...Tonight through Wednesday. Early afternoon satellite imagery was showing low clouds throughout the Snake River Plain and Eastern Magic Valley as a broad disorganized trough advanced through the region. Light snow was noted in the Missoula area as a weak disturbance rotated SE through the panhandle on the WRN periphery of the aforementioned trough. The numerical models continue to show some light seeder-feeder snowfall within the Snake River Plain and ERN mountains tonight (although not as robust as previous model runs) as that disturbance shears SE through the region. Additional weaker disturbances follow Monday afternoon/evening while a ridge of high pressure expands along the NW coast. We should see progressively drier/clearer conditions work into the region Tuesday and Tuesday night as the ridge builds inland. The clearing will promote strong radiational cooling and well below normal temperature`s Monday through at least Wednesday morning with some recovery Wednesday afternoon as the flow aloft becomes more southwesterly ahead of the next incoming Pacific storm. Huston .LONG TERM...Wednesday night through next Sunday. A moist, westerly flow remains on tap following Wed`s dry trough passage. The Canadian model initiates precip into the Central Mntns much earlier (Wed eve) than the GFS/ECMWF (midday Thurs), and we considered it an outlier. Continued to run with the reasonable NBM solution, which spreads snow showers across the forecast area late Thurs AM into the afternoon. Once again, the flow will target the higher-elevation, west-facing slopes for greatest accumulation, but this still isn`t looking like a major event. Even looking at the NAM 75th percentile on 48-hour accumulation Thurs/Fri, most of the CWA picks up almost nothing, and the Central Mntns west of Challis/north of Hailey stay under 1 foot. AND, the long-range models are a bit more progressive in shutting off that moist flow with a building longwave ridge of high pressure by Fri night. Snow showers at lower elevations and in the Snake Plain may end up being pretty light and hit-and-miss. So, at this time, nothing looks particularly high impact outside of the Central Mntns as we finish out the week. Dry conditions are now expected Sat/Sun, with the region largely under the influence of the ridge. Temps look to increase a few degrees each day through the latter part of the week, trending a bit above climatological norms for this time of year. - KSmith && .AVIATION...The main concern for aviation over the next 24-48 hours will be continued low stratus and patchy fog due to a very moist, post-storm low-level airmass. Generally MVFR cigs are expected to continue throughout the afternoon/eve, with almost no guidance lifting anything above 3,000 feet. Given the continued low-level saturation and lack of significant wind or any new system to clear things out, this makes perfect sense. Stratus should again intensify and lower tonight, probably back into IFR at KPIH/KIDA, and perhaps KDIJ (less confidence there), supported again by very light winds and the recent snowfall. We again used a combination of MOS guidance and the HRRR cig/vsby products to develop our cigs and FG/BR expectations in the TAFs (with the LAMP and the auto-generated MOS- based TAF guidance used as a sanity check). They aren`t always right, but they have been doing well at capturing the flavor of things in these recent post-storm airmasses, and the degree of moisture running around right now makes the NAM time-heights and even some of the BUFKIT soundings nearly useless. Once again, we expect the stratus to be the greater issue, with fog more patchy due to the insulating cloud cover above. The greatest potential for LIFR and near-closure conditions exists at KIDA, especially after 11-12z. Meanwhile, KSUN should remain VFR for cigs/vsbys throughout the next 48 hours. We do have a weak shortwave dropping across the region this afternoon/tonight, and some of the coarser, deterministic model projections do generate some snow shower/flurry activity with this. It stands to reason that any mid-level clouds associated with this feature (some observed upstream on satellite) moving over the low stratus could contribute ice nuclei to the lower deck and set up a seeder-feeder process. However, most of the high-res guidance (particularly the HREF ensembles) are fairly dry, so our confidence in snow showers hitting a given terminal is extremely low. Blanketed the TAFs with VCSH for now, and will make any needed adjustments based on radar/observational trends. - KSmith && .PIH WATCHES/WARNINGS/ADVISORIES...None. && $$
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Monday night) Issued at 340 PM CST Sun Dec 15 2019 Snowfall should gradually end from west to east late this afternoon and evening as isentropic upglide and frontogenetical lift cease with increasing northerly flow through the column. Current radar trends still show elevated CSI being realized as banded snow from Dickinson to Jackson counties. These bands should decay from west to east with the loss of forcing. CAM guidance and short-term trends are in very good agreement in the snow coming to an end across the entire area by 9pm, which is the end time for both the northern Winter Weather Advisory and the Winter Storm Warning. Overall snow amounts have been coming in at around 3 to 6 inches, with localized amounts over 8 inches being reported as well. A brief lull in the snowfall will continue for most of the overnight hours with subsidence occurring until the second round begins in east central KS a few hours before sunrise. This next batch comes ahead of the main trough axis swinging through western KS, and the CVA associated with this wave looks to be the main driver of this phase of the event as the baroclinic zone pushes south and east of the area, taking the frontogenetical forcing with it. Any cloud ice that would be lost this evening should be a non-issue for Monday due to the DGZ re-saturating once we get forcing for vertical motion in the morning. As such, have kept all snow through the day with the highest chances along and south of a line from Topeka to Council Grove. Models still vary slightly as to how far north we`ll see any snow, so it`s possible Topeka stays dry completely. Regardless, the northern half of the CWA should avoid this round of snow with east central KS expected to see it taper off in the evening as lift and saturation both decrease. Additional accumulations look to be another inch or two with potentially some locally higher amounts as the 18Z HRRR has hinted at some more narrow bands developing tomorrow. Have trended high temperatures a bit cooler in eastern KS for tomorrow, in part because of the CAA regime expected to dominate the period, and also to account for the new snow pack in east central KS in particular. Most areas are forecast to stay in the upper 20s with north central KS reaching the low 30s, where snow amounts have been lower. With clouds clearing overnight after the system moves out, lows are forecast to drop to the teens area- wide. .LONG TERM...(Tuesday through Sunday) Issued at 340 PM CST Sun Dec 15 2019 Dry weather is expected for the rest of the week as ridging builds in behind the Monday system. Another mid-level trough does look to deepen to our west on Thursday and pass south of the area on Friday, but precipitation is forecast to remain south at this time with our only impacts being increased cloud cover and breezy southerly winds. Temperatures are still dependent on snow pack and how quickly it melts under sunny skies, especially on Tuesday, but a general warming trend is expected late in the week with WAA returning late Wednesday into Thursday. If this trend verifies, more seasonal temperatures in the 40s would return for the second half of the week, if not slightly above average. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 539 PM CST Sun Dec 15 2019 Conditions improving somewhat with snow moving east, though MVFR ceilings should persist for much of this forecast. Confidence in the next round of snow reaching the terminals is too low for restrictions with it. && .TOP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 9 PM CST this evening for KSZ009>012-021-034. Winter Weather Advisory until 6 PM CST Monday for KSZ040-054>056- 058-059. Winter Weather Advisory from 3 AM to 6 PM CST Monday for KSZ022>024-026-035>039. Winter Storm Warning until 9 PM CST this evening for KSZ022>024- 026-035>039. && $$ SHORT TERM...Picha/Skow LONG TERM...Picha AVIATION...65