Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/15/18

National Weather Service Kansas City/Pleasant Hill MO
503 PM CST Sun Jan 14 2018 .Discussion... Issued at 229 PM CST SUN JAN 14 2018 Pretty solid warm air advection across the area has brought temperatures to around freezing/melting, mainly across the southern half of the forecast area. Southwest winds around 10 to 15 mph and good sunshine has allowed for these temperatures to come up. Areas north of the river will only get to about 25 to 30 degrees this afternoon, but this "warm up" will be very brief as another very potent cold front is diving south toward the area. By this evening, around 02z the front will nose into northwest Missouri. Low level frontogenesis along the surface and low level front will be responsible for another round of some light snow later this evening. Mid level ascent associated with the trough over the Great Lakes will arrive a bit later, so the bulk of the lift associated with this widespread round of light snow tonight will be in the lower levels as the cold air moves in. HRRR soundings taken in the early hours of the event indicate that the atmospheric profile might struggle to saturate into the Dendritic Growth Layer, which might lead to some light freezing drizzle before snow begins to fall once the column saturates. Given QPF amounts around or less than .10" if any of it falls as light drizzle it would likely cut into any forecast amounts. The quick duration of the frontogenetic lift will also limit the amount of snow production. Right now the forecast calls for about another inch of snow, give or take a couple hundredths. The quick duration of the frontogenetic lift will also limit the amount of snow production. Behind the cold front, and lasting much longer than the falling snow, is very cold temperatures, which will overspread the area through the day on Monday. Temperatures through the day on Monday will be falling, resulting the high temperature occurring early in the day. Winds will be in the 10 to 20 mph range, which will bring wind chill values down to around zero through the day. By Monday evening/Monday night time frame widespread wind chills will be down to around 10 to 20 below, with some areas of far northern Missouri dropping to around 25 below. Surface ridging will dominate the area for the middle part of the week, with below normal temperatures and dry conditions. By Friday a surface trough will form to the west of the area, and mid level ridging will form ahead of a deepening mid level trough for next weekend. Good warm air advection ahead of the surface trough will bring temperatures above freezing for Friday. Warm air advection continues for Saturday, likely bringing day time highs well above normal, with temps in the middle 50s. The evolution of the trough next weekend still bears some watching as confidence is growing that this trough will eject into the plains and affect the area with some precipitation. The questions lie with track, timing, and intensity of the wave as GFS and EC are both still very divergent in their solutions. && .Aviation...(For the 00Z TAFS through 00Z Monday Evening) Issued at 455 PM CST SUN JAN 14 2018 Current VFR conditions should quickly transition to MVFR with the arrival of light snow and reduced ceiling heights through the latter half of the evening into the early overnight. Snow should taper off shortly after 06Z, though MVFR stratus will linger until sunrise. At that point, mixing and resulting gusty winds should lift ceiling heights slightly through the remainder of the period. Surface winds will transition to northwesterly in the wake of a passing cold front. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...Winter Weather Advisory from 11 PM this evening to 9 AM CST Monday for KSZ057-060-103>105. Wind Chill Advisory from 6 PM Monday to noon CST Tuesday for KSZ025-057-060-102>105. MO...Winter Weather Advisory from 11 PM this evening to 9 AM CST Monday for MOZ007-008-015>017-021>025-028>033-037>040- 043>046-053-054. Wind Chill Advisory from 6 PM Monday to noon CST Tuesday for MOZ013>017-020>025-028>033-037>040-043>046-053-054. Wind Chill Advisory from 3 PM Monday to noon CST Tuesday for MOZ001>008-011-012. && $$ Discussion...Leighton Aviation...Welsh
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
931 PM CST Sun Jan 14 2018 .UPDATE... No major changes needed to the short-term of the forecast tonight, as the previous forecast is mostly on track. Only changes were made to the hourly grids based on current trends. 00z guidance is beginning to come in and a full update to the package will be done tonight regarding the upcoming winter weather on Tuesday. && .PREV DISCUSSION... /ISSUED 622 PM CST Sun Jan 14 2018/ AVIATION... /00Z TAFS/ SREF cig/vsby probabilities show low probabilities of cigs and vsbys to build over I-35 through 09z, so will maintain the more- conservative-than-MOS-guidance trend for another TAF cycle. Light decoupled evening winds may also play a role in the slow to return clouds. CIRA-SIMWRF fog product is more agreessive and shows cigs spreading west rapidy toward DRT by daybreak. Boundary layer moisture look less saturated at DRT based on the RUC soundings for 10-12Z, so conditions could potentially drop to lifr there. Once the moist layer is established will defer to the more pessimistic NAM guidance on an afternoon return to vfr skies and mid evening return back to mvfr. PREV DISCUSSION... /ISSUED 250 PM CST Sun Jan 14 2018/ SHORT TERM (Tonight through Monday Night)... With southerly flow in place temperatures overnight tonight into Monday will be warmer than we have seen the last few days. Clouds will also be on the increase overnight and will remain in place during the day on Monday. Highs Monday will top out in the lower 60s and will be the warmest temperatures Central Texas will see through the work week. Models have trended a bit earlier with the cold front passage with the NAM, GFS, and ECMWF bringing it into the Hill Country and Austin area by midnight, Del Rio and San Antonio around 3am, and into the Coastal Plains by daybreak on Tuesday. Precipitation due to isentropic lift will be ongoing ahead of the front and will continue into Tuesday. Temperatures will plummet behind the front. To use Austin as an example temps will go from the upper 50s Monday evening, to around 48 at midnight, to 35 at daybreak (behind the front), and continue dropping into the mid to upper 20s by Tuesday afternoon. See the LONG TERM discussion below for a more in depth look at the wintry precipitation forecast beginning Monday Night. LONG TERM (Tuesday through Sunday)... Bottom line up front is a wintry mix of precipitation and very cold temperatures are likely across most of Central Texas beginning Monday night through Tuesday. Synoptically isentropic lift and dynamic lift from impulses embedded in the longwave 500mb trough will help produce precipitation ahead of the front moving through Monday night into Tuesday and continue precipitation through the day on Tuesday. Precipitation will linger into the afternoon hours behind the front but begin to clear from north to south late Tuesday afternoon and evening. Atmospheric soundings from the NAM and GFS show precipitation transitioning from rain to freezing rain and sleet to snow across western and northern parts of Central Texas. The GFS soundings in these northern area are more moist in the dendritic growth zone which will favor a switch to a snow/ice mix across these areas. This leads to a discussion on precipitation types. Based on the timing of the front and the strong cold air advection behind the front the Hill Country and Austin Metro area could see the wintry mix beginning after midnight and continuing through 6am. This transition will happen between 6am and noon for San Antonio and the U.S. HWY 90/I-10 corridor, and during the afternoon and evening for the far southern areas. Initially the mix will mainly be sleet and freezing rain, but as the atmosphere continues to cool as discussed above some snow could possibly be mixed in across the Hill Country and Austin area during the afternoon, and across parts of the Rio Grande plains during the afternoon and evening. As precipitation exits late in the day into the overnight hours parts of the coastal plains could also see some of the wintry mix before precipitation ends. In terms of accumulations and impacts as of right now we are looking at possible accumulations of 1/10 of an inch of freezing rain and sleet with some isolated higher accumulations possible up to 1/4 of an inch. This does not include any possible snow accumulations, remaining less than 1/2 an inch, which will again be focused across the northern and southwestern areas. With this much ice and temperatures expected to dip down into the 20s Tuesday afternoon the icing could impact not just the typical bridges and overpasses, but also primary and secondary roads. This would create significant travel impacts during the day on Tuesday into Tuesday night as temperatures remain well below freezing. Now that we have covered the precipitation expected we do need to talk briefly about temperatures which will fall through the day on Tuesday. Model guidance is dropping temperatures by Tuesday afternoon into the upper 20s across parts of South Central Texas, including the Austin and San Antonio metro areas. Coupled with the strong north winds this will create windchill values in the teens for most areas. These windchill values will continue overnight as lows drop into the low 20s and upper teens. So after the precipitation ends the cold will continue to be a concern. This also means that any ice/snow that does accumulate will stick around through the night Tuesday into Wednesday morning until temperatures rise above freezing Wednesday afternoon. There is only a 5 to 8 hour window on Wednesday afternoon where temperatures will be above freezing before dropping again for Thursday night. The GFS and ECMWF are now more in line with one another clearing out precipitation late Tuesday evening from the Interstate 35 corridor and out of Central Texas completely by Wednesday morning. Wednesday will be dry and cold with temperatures slowly rising above freezing by the afternoon. Another strong upper level disturbance will approach and move through South Central Texas Wednesday night and Thursday. With the cold airmass in place and more precipitation expected, a second round of wintry precipitation will be possible overnight Wednesday across the Edwards Plateau and Rio Grande Plains, stretching into the Hill Country by Thursday morning. The 12z GFS has shifted the focus of this freezing rain and sleet event further west than previous runs. Confidence for this second event remains low to moderate as some differences in the models exist with temperatures and the location of the wintry precipitation. For now have gone with low end PoPs and a rain/sleet/freezing rain mix. Of note is the colder trend in the GFS and ECMWF with temperatures. This would result in a larger area being impacted by wintry precipitation. Temperatures warm above freezing by noon Thursday transitioning all precipitation to rain as the system exits. Southerly flow returns Friday with dry and warmer weather Friday and Saturday. The next trough will move across Texas late Saturday into Sunday dragging a cold front with it. Models are showing slight rain chances across areas east of Interstate 35 along the front as it moves through for Saturday night and Sunday. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 42 62 28 29 22 / 0 10 70 60 10 Austin Bergstrom Intl Airport 40 62 29 30 23 / 0 10 70 60 20 New Braunfels Muni Airport 40 63 30 30 23 / 0 10 60 60 30 Burnet Muni Airport 40 58 24 25 18 / 0 10 70 60 10 Del Rio Intl Airport 42 61 34 34 27 / 0 - 60 50 10 Georgetown Muni Airport 40 60 25 27 19 / 0 10 70 60 10 Hondo Muni Airport 41 64 33 33 24 / 0 10 60 60 20 San Marcos Muni Airport 40 63 30 30 22 / 0 10 60 60 20 La Grange - Fayette Regional 40 64 31 31 22 / 0 10 50 50 30 San Antonio Intl Airport 43 62 32 32 25 / 0 10 60 60 30 Stinson Muni Airport 43 64 34 34 26 / 0 10 50 60 30 && .EWX WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from late Monday night through Tuesday afternoon for the following counties: Bandera...Bastrop...Bexar...Blanco... Burnet...Caldwell...Comal...Edwards...Fayette...Gillespie... Gonzales...Guadalupe...Hays...Kendall...Kerr...Kinney...Lee... Llano...Medina...Real...Travis...Uvalde...Val Verde...Williamson... Wilson. && $$ Mesoscale/Aviation...Oaks Synoptic/Grids...Hampshire Public Service/Data Collection...33
Area Forecast Discussion
National Weather Service Lincoln IL
926 PM CST Sun Jan 14 2018 .UPDATE... Issued at 926 PM CST Sun Jan 14 2018 Decided to adjust some of the snow totals for tonight. Seeing some reports already of 1-2 inches so have adjusted snowfall totals up some with this update. UPDATE Issued at 909 PM CST Sun Jan 14 2018 Light snow continues to fall across most of central and eastern Illinois this evening. It is beginning to end just west of I-55 so there will be a break in the snow late this evening. Then the snow associated with the main vort max/cold front will move into the CWA around midnight and then continue overnight. Reports have been very few, but looks like around an inch has occurred with some of the heavier pockets. Another 1-2 inches still possible overnight with round #2. Current forecast is looking fine, but will make some tweaks and send an update shortly. && .SHORT TERM...(This evening through Monday) ISSUED AT 300 PM CST Sun Jan 14 2018 Light snow associated with increasing warm advection ahead of a weak short-wave trough has developed across west-central Illinois this afternoon. 20z/2pm radar imagery and area surface obs suggest snow is falling along/west of a Galesburg to Jacksonville line. This is a fairly narrow band of precip, with the snow coming to an end further west across north-central Missouri. Based on latest HRRR forecast, it appears the snow band will spread eastward to the Indiana border by early evening...with the snow tapering off and perhaps temporarily coming to an end behind the initial band by mid-evening. Given the current dry airmass and the transient nature of the band, am expecting little more than a dusting of snow early this evening. The more significant snow will not arrive until later tonight as a vigorous wave over South Dakota dives southeastward into the region. Models have been fairly consistent with their solutions...bringing a band of light to moderate snow associated with the second wave and its associated cold front into the NW KILX CWA late this evening...then spreading it further east and south overnight. NAM time-height cross-sections indicate a 3-4 hour window of time when deep-layer omega is maximized and the highest snowfall rates will be achieved. Despite moderately strong lift and ample profile moistening, the progressive nature of this system will limit snowfall totals. Amounts will generally be on the order of 1 to 3 inches...with the highest totals perhaps close to 4 inches focused north of the I-74 corridor. The snow will linger across the E/SE through Monday morning before quickly exiting into Indiana by afternoon. Will be issuing a Winter Weather Advisory for all of central and southeast Illinois from 9pm tonight through noon Monday to cover the accumulating snowfall and the distinct possibility of blowing/drifting snow Monday morning. Strong W/NW winds in the wake of the system will bring sharply colder air into central Illinois...with temperatures falling into the single digits and teens by afternoon. .LONG TERM...(Monday night through Sunday) ISSUED AT 300 PM CST Sun Jan 14 2018 Bitterly cold conditions will prevail Monday night as overnight lows drop to around zero. Thanks to continued brisk northwesterly winds, wind-chill values will plunge to between 15 below and 20 below zero. As a result, will be issuing a Wind Chill Advisory for all of central and southeast Illinois Monday night into Tuesday morning. With a sharp upper-level trough rotating through the Great Lakes/Midwest, cyclonic flow will result in plenty of clouds and perhaps a few snow flurries Tuesday/Tuesday evening before the trough axis settles southeastward into the Ohio River Valley. After that, the very cold weather will persist into Wednesday before the prevailing upper trough flattens and a pronounced warming trend develops by the end of the week. High temperatures will climb into the 30s by Thursday...then will soar into the upper 40s and lower 50s by Saturday. The next significant weather-maker will not impact the region until late next weekend when temps will be warm enough to support rain by Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 600 PM CST Sun Jan 14 2018 The waa segment of the clipper system is moving through the area currently and based on local and mosaic this will last couple more hours at PIA and BMI. It has already diminished some at SPI/DEC but has not started at CMI yet. So for these three sites will have VCSH for this evening with MVFR cigs around 2.5kft at SPI and VFR cigs at DEC and CMI. MVFR clouds should move into DEC and CMI in a few hours. PIA and BMI will be MVFR predominately, but IFR vis of 2sm is occurring now with light snow. Have tempo at each site to cover the IFR conditions. By 05z at PIA and 06z at BMI/SPI/DEC and 07z at CMI, the main wave of snow will begin and there will be tempo groups at each site for worse conditions of 1sm and cigs below 1kft. These conditions will improve in the early morning hours at all sites but VCSH of scattered light snow or flurries will continue during the morning hours til close to noon. Will keep MVFR cigs around 2.5kft going at all sites after the snow ends even into the afternoon. Winds will be southerly this evening but become southwesterly during the morning hours. Then around noon, the winds will become west-northwesterly after a cold front moves through the area...and the associated snow. Will be some gusts at times through the period around 20kts. && .ILX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until noon CST Monday for ILZ027>031- 036>038-040>057-061>063-066>068-071>073. Wind Chill Advisory from 6 PM Monday to noon CST Tuesday for ILZ027>031-036>038-040>057-061>063-066>068-071>073. && $$ UPDATE...Auten SHORT TERM...Barnes LONG TERM...Barnes AVIATION...Auten