Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/01/18

Area Forecast Discussion
National Weather Service Columbia SC
612 PM EST Fri Nov 30 2018 .SYNOPSIS... High pressure will move farther off the Southeast Coast through tonight. The high will direct increased moisture into the forecast area in an onshore flow. The moisture will become deep Saturday with a warm front in the region. The warm front will lift north of the area Saturday night but moisture will remain high in a southerly flow ahead of an approaching cold front. This front will be in the area Monday and may linger into Tuesday. Dry high pressure will approach from the west Wednesday and be over the area Thursday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Tonight: Brief light rain possible across the North Midlands/Pee Dee early this evening. Radar showing more significant rain over north Ga at 23z. These showers expected to stay north and west of the region where low level warm advection will be stronger and ridging weaker. This is supported by latest high resolution HRRR and other guidance. Models indicating there may be a dry period through much of the overnight hours, then towards morning, deeper moisture will be approaching the western cwa from central and southern Georgia. Rain chances will be on the increase late tonight across the CSRA due to this approaching system. Overnight lows in the upper 40s for most areas. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... The models have been consistent showing deep moisture Saturday associated with an onshore flow on the backside of offshore high pressure and ahead of a mid-level shortwave trough. A warm front is forecast to develop just south of the area. The NAM surface-based LI pattern suggests this feature will stay south of the area through the day. The NAM, GFS, and ECMWF maintain surface-based stability with positive LI values. There will be high shear with h85 wind 40 to 50 knots. Despite the shear there is a diminished severe thunderstorm chance because of lacking surface-based instability. We kept isolated thunderstorms in the forecast to account for elevated instability. The NAM indicates the cross total reaching 23 during the afternoon. The models have trended higher with rainfall amounts. The guidance consensus supports amounts of one-half to three-quarters of an inch with the higher values in the southeast section. There is uncertainty because convection closer to the coast may limit moisture and instability farther inland. An in situ wedge pattern supports the lower temperature guidance. Believe the warm front will lift north of the area Saturday night. A warm advection pattern supports continued showers but the chance should be diminished with mid-level drying behind the main shortwave trough. Low-level moisture will remain high. Fog may become an issue especially if the warm front lingers. Much of the NAM and GFS MOS indicate fog. Strong shear is forecast to continue Sunday with h85 wind 40 to 50 knots. The models have been consistent indicating instability as well with surface-based LI values -2 to -4. Severe thunderstorms will be possible but the threat is limited by continued shallow moisture behind the lead mid-level shortwave trough and a lack of significant low-level forcing with the cold front well west of the area. It should be a warm and breezy day. The temperature guidance was close with highs in the middle and upper 70s. Forecast sounding average wind in the mixed layer supports southwest wind gusting near 25 mph. The models keep the deeper moisture east of the forecast area Sunday night. Diminished convergence is depicted along the approaching cold front. The guidance consensus supports chance pops. && .LONG TERM /MONDAY THROUGH FRIDAY/... A cold front will be in the area Monday into Tuesday but the models indicate little convergence with the main front off the coast. Deeper moisture is also forecast to be east of the area. We kept a shower chance in the forecast with the greater chance in the east section closer to deeper moisture. A tight moisture gradient diminishes forecast confidence. The models have shown consistency with dry and cold high pressure in control Wednesday and Thursday. There may be an increase in moisture ahead of the next low pressure system Friday but the GFS and ECMWF keep the bulk of this moisture west of the area. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... Mainly VFR conditions expected most of the overnight. Restrictions expected to develop from southwest to northeast across the region during the 12z-18z period Saturday. Surface ridge offshore extending into the area. Zonal flow aloft early this evening with mid level ceilings across the region. Winds will be backing to southwest ahead of short wave trough and expect ceilings to slower lower as moisture increases late tonight in the low levels. However, relatively high confidence for VFR conditions to 12z. During the morning with stronger isentropic lift and moisture flux, ceilings will lower to MVFR and possibly IFR at times with widespread light rain developing. Heavier showers possible at times mainly in the CSRA near AGS and DNL terminals where instability may develop in the afternoon. However, confidence not high enough for thunderstorms at terminals at this time. Widespread IFR conditions expected after 18z. An increasing low-level jet could cause some wind shear by the end of the period, but should remain below criteria for mention. Winds expected to be light and variable becoming southeast Saturday and possibly increasing in the afternoon. EXTENDED AVIATION OUTLOOK...Periods of restrictions expected Friday night into Tuesday with a stalled front in the area and weak areas of low pressure. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service Charleston SC
1018 PM EST Fri Nov 30 2018 .SYNOPSIS... High pressure will give way to a warm front moving north through the area later Saturday into Saturday Night bringing showers and some storms into early next week until a cold front pushes offshore by the middle of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Late this evening: No significant changes made with this update. Increased sky cover over the next several hours based on recent satellite imagery. Previous discussion continues below. Early this evening: Satellite imagery shows mostly clear skies across the forecast area this evening, with considerable dry air still in place. In fact, based on SPC mesoanalysis, precipitable water values are around 0.8 inches or less. However, you can clearly see in water vapor imagery that increasing moisture is on the way as shortwave energy begins to lift northeastward across the Gulf of Mexico. The main impact of this dry air and clear skies over the next several hours is that we should see good radiational cooling conditions. Therefore, lows have been cooled a few degrees across the board. Current thinking is that we will reach our lows early tonight, with temperatures either holding steady or rising late tonight towards sunrise Saturday. With this window of cooling and clear skies, we can`t totally count out fog in some areas, but will hold it out of the forecast for now. Regarding precipitation, with the considerable dry air in place, it will take some time for the column to moisten. Therefore, based on the dry air and on recent runs of the HRRR and RAP, the arrival of showers has been delayed a few more hours. By sunrise, current thinking is that southeast Georgia will contain the bulk of the coverage with just isolated to scattered coverage across southeast South Carolina. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... Confidence is high that this period will feature warm and unsettled conditions, although the details are still a bit uncertain, especially regarding rain timing and chance for severe weather. Expect showers, moderate at times, to be increasing from the south Saturday as deeper moisture advecting in from that direction combines with a developing warm front and upper level energy. We think instability, especially surface-based, will be too low to cause thunder until possibly later in the day across GA. The warm front should push north of the area Saturday night with a general decrease in rain chances, although a few showers and perhaps a storm will likely linger. Although shear will be plenty strong into Saturday night it looks like instability will be insufficient for any appreciable severe storm threat. However, we think southeast GA would have the best chance later Saturday and Saturday night where the greatest instability should occur. Rain amounts should generally be 0.5-0.75 inches through the period. Temperatures should be steady or even rise during the night. Rain chances should increase at least a bit Sunday as instability increases ahead of an approaching cold front, although it doesn`t appear to be a washout by any means at this time. Rain chances should increase Sunday night, especially toward the Pee Dee/Midlands/CSRA closer to the cold front and deeper moisture. Shear will remain strong so there is a small chance of a severe storm with damaging winds and/or tornado. The front should push into the area Monday with an increased chance of showers and a few storms across the entire forecast area through at least Monday evening, especially near the coast. A low threat for a few severe storms will continue. Another concern will be for some dense fog each morning due to lowering of stratus, but especially Monday morning when there is a better chance for sea fog also advecting onshore. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Confidence increasing in the cold frontal passage Monday night with most of the showers along or offshore Tuesday. High pressure will then build Wednesday and Thursday accompanied by a chilly air mass with temps dipping below climo values at mid week. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... VFR conditions are expected to prevail through the overnight at KCHS and KSAV. There is a low end potential for some fog, but the threat appears to be too low to include in the forecast. The main forecast issue is timing the arrival of showers into the terminals and the lowering of ceilings through the day. Current thinking is that prevailing showers should arrive at KSAV around 13z with MVFR ceilings. Heavier showers with MVFR visibilities and IFR ceilings could arrive around 18z. IFR conditions could then linger into the evening though showers should begin to lessen in coverage. At KCHS, have timed prevailing showers and MVFR ceilings into the area starting at 15z. Heavier showers with MVFR visibilities and IFR ceilings have been timed into the terminal around 20z. Also of note, there could be some LLWS on Saturday as the low level wind field increases. Confidence isn`t high enough at this point to include in the TAF`s. Extended Aviation Outlook: IFR and lower conditions expected to continue through Monday as low clouds and rain impact the area. Reduced visibilities from lowering stratus and/or sea fog also possible at times. && .MARINE... Tonight: Southerly flow peaking 10-15 knots is expected overnight as the coastal waters remain situated between departing high pressure and a cyclone over the central plains. Seas 1-2 ft are expected for nearshore waters, with 2-3 feet offshore. Shower activity will begin to expand northeast across the coastal waters prior to sunrise. Saturday through Tuesday: Conditions will go downhill Saturday night as a warm front moves through and then remain poor into Monday until a cold front passes through. Strong low-level jetting should be limited from reaching the surface in the warm advection pattern, especially over the cooler nearshore waters, but Small Craft Advisories are likely all waters except nearshore GA and Charleston Harbor (starting earliest beyond 20 nm Saturday evening). Otherwise, sea fog could develop across the nearshore waters starting Saturday night as warm and moist air advects into the area. The fog could become dense at times with Dense Fog Advisories a possibility at some point, especially Sunday into Monday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...BSH SHORT TERM...RJB LONG TERM... AVIATION...BSH/RJB MARINE...JMC/RJB
Area Forecast Discussion
National Weather Service Duluth MN
953 PM CST Fri Nov 30 2018 .UPDATE... Issued at 953 PM CST Fri Nov 30 2018 Added a mention of patchy freezing drizzle to Itasca, Cass and Crow Wing counties, and a portion of Aitkin county. Road reports indicate ice formation is occurring. Also added freezing fog to Price County as visibilities have dropped to one half mile. Made some other minor changes. && .SHORT TERM...(This evening through Saturday) Issued at 148 PM CST Fri Nov 30 2018 The extensive cloud cover across the Northland will not be going anywhere anytime soon. The sun was too weak today, considering the time of the year, to break up this thick stratus layer. The lack of wind with the high pressure over us did not help either. Since it will still be here going into sunset, it will surely continue overnight. Leaned on the HRRR and 4km NAM for cloud cover because of how well they performed today. The forecast of cloudy skies tonight meant bumping up the overnight temperatures a bit because of the insulation. Lows will be in the lower 20s. A strong storm system will move into the Central Plains Saturday, and begin to affect the Northland. Breezy east-northeast to northeast winds will develop during the day, and snow will begin to spread into northwest Wisconsin and east-central Minnesota in the afternoon. Gale-force winds will develop over Lake Superior. The humid flow from the lake could result in some bands of light precipitation downwind near the Twin Ports and Ashland areas. The 4km NAM, WRF ARW, and WRF NMM are picking up on this. This drizzle and light rain could be freezing drizzle and freezing rain, but temperatures should primarily be warm enough to prevent significant icing. However, it will be something to keep our eyes on. The lakeshore areas of Duluth and Superior could get wind gusts of 30 to 40 mph, and other areas downwind of Lake Superior can expect gusts of 20 to 30 mph. High temperatures will range from the upper 20s across northern Minnesota to the lower 30s downwind of Lake Superior. .LONG TERM...(Saturday night through Friday) Issued at 148 PM CST Fri Nov 30 2018 A cyclolytic low pressure system will glide across the Great Lakes region. This has some potential to bring snowfall to NW WI, and NW WI may even need an advisory if an FGEN band develops along its northern flank. In this package, continued the trend to minimize the mixed precip keeping anything that falls as snow. Profiles are supportive of just snow until late in the system when temperatures aloft warm. Overall, on its current consensus track, the storm just skirts our area to the south and east. A drift northward could change this, but that does not appear likely. Lake effect snow will likely impact the South Shore of Lake Superior after the system passes as winds turn to the NW. After this system moves eastward, cold air will funnel in and linger for the remainder of the forecast. A clipper system or two should cross on NW flow mid and late week, but it doesn`t look like any significant snow expected in the next week besides this weekends` storm and any lingering lake effect. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 533 PM CST Fri Nov 30 2018 High pressure was in the neighborhood at the start of the forecast. Plenty of low level moisture was around with areas of BR. Widespread IFR clouds covered the terminals. HIB and INl will see cigs improve to VFR through mid morning. Vsbys were in the MVFR/IFR range, with pockets of LIFR and FG, especially at DLH. Vsbys will also improve to VFR at all sites by 12Z. As the high departs, the surface wind will turn northeast after sunrise, and increase in speed with some gusts at HYR/BRD/DLH by late morning or around noon. A system well to the south of the terminals will bring some light precipitation toward HYR by the end of the forecast. Due to low confidence in timing, used a VCSH mention. && .MARINE... Issued at 148 PM CST Fri Nov 30 2018 Gale warnings have been issued for much of Western Lake Superior. The zones north of Taconite Harbor were especially tricky given that the winds will be nearly parallel to the shoreline and the way the terrain is inset may prevent the gale gusts there. So, for that fact left them out of the gale warning though gusts to 30 kt will likely be common. Elsewhere in the gales, winds will be gusting to 35 to 40 kt for many hours out of the northeast. Waves should build above 10 ft fairly quickly after the winds begin to accelerate and should remain high through Monday morning. && .PRELIMINARY POINT TEMPS/POPS... DLH 25 32 24 28 / 0 20 30 20 INL 22 27 19 25 / 0 0 0 0 BRD 25 33 22 26 / 0 10 20 10 HYR 25 34 30 31 / 0 50 70 30 ASX 26 35 30 32 / 0 40 50 50 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...Gale Warning from 3 PM Saturday to noon CST Sunday for LSZ121- 142>148. Small Craft Advisory from 3 PM Saturday to noon CST Sunday for LSZ140-141. && $$ UPDATE...GSF SHORT TERM...Grochocinski LONG TERM...Wolfe AVIATION...GSF MARINE...Wolfe
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
547 PM CST Fri Nov 30 2018 .AVIATION... /00Z TAFs/ Concerns: Convection at the TAF sites and strong west winds on Saturday. A dryline is marching east into the region and storms are developing along and just east of the front. Strong lift associated with a strong upper level disturbance will continue to support storms along this boundary as it moves east this evening. Thunderstorms are likely to impact the Metroplex airports between 02-04Z. These storms could be severe, and a Tornado Watch is in effect. To the south, the thunder threat appears lower as the best lift will remain to the north, and have opted to only mention a VCSH in the KACT TAF between 03-05Z. However, this may need to be amended for a TS mention depending on trends the next 1-2 hours. Breezy and gusty south winds will continue until the convection passes, and then southwest winds are expected for the remainder of the night. By midday Saturday, breezy and gusty west winds of 15-20 kts with gusts around 25 kts will be possible for nearly the remainder of the day. This will have some impacts on area runways. Wind speeds are expected to diminish late Sunday afternoon and back to the southwest. MVFR cigs that developed at sunset this evening will become VFR as the dryline passes, and VFR cigs will prevail through the end of the valid TAF period. JLDunn && .SHORT TERM... /Issued 346 PM CST Fri Nov 30 2018/ /Tonight Through Saturday Night/ We continue to analyze 3-hourly sounding analysis through early this evening, with a mid-afternoon(or 21z) sounding in the air as we speak. These frequent soundings are helping us dissect our thermodynamic profile for the area, as we already know the southwesterly deep bulk shear profiles of 45-50 knots will exist into this evening, as well as increasing large-scale ascent. Earlier, an 18z sounding indicated only a slight weakening of the elevated mixed layer(EML) or cap aloft with bulk of the moisture either contained below 850mb or above 400mb. Some slight increase of MUCAPE was evident with the steepening of mid level lapse rates aloft. This is likely the reason any warm-sector showers or isolated storms have been relegated within a deeper moist axis from far East Texas into Louisiana and the Ark-La-Tex. Around here, it`s been more resistant to development to this point due to it being too dry the 700mb-850mb layer. This layer is critical for the development of deep updrafts and consequently thunderstorms. We should know more after this writing on the extent of weakening of the EML and where best storm initiation will be. At this moment, we still expect the deepest moisture to be across our far eastern counties, where 40-70% POPs will be advertised, with only slight chances across the I-35 corridor and points west. Changes in the SPC risk areas earlier are agreed upon here due to the aforementioned dry and deep EML from earlier today. Current feeling is a shortwave over the New Mexico/West Texas border will continue lifting east toward our area by 5-7 pm with the arrival of a surface trough. Our CAMs (convection activating models) have struggled mightily and now as I write this, the HRRR wants to develop a few supercellular storms further west than what was shown for several hours earlier near Montague Co and across out SW counties. Our other high-resolution models want to wait til closer to mid evening and mainly east of I-35 and with the aforementioned EML overhead in mind, I have leaned toward this solution versus the HRRR with all the storms in the western counties. It definitely bears watching. Otherwise, the strong mid-level shortwave and associated surface trough will track across the area late this evening and through the overnight hours. I have left a chances for storms between midnight and 3 am CST across the far east and southeast counties and with very strong wind shear in place and ascent, even a chance for a severe storm or two in the time window across the areas. As for severe weather modes, all modes of severe weather are possible with any discrete storms through mid evening. Convective activity should congeal more into a semi-linear, broken line of storms or QLCS with a strong LLJ driving more of a damaging winds and marginally severe hail threat. Breezy west-southwest winds and dry air will result in temperatures starting off breezy and cool in the 50s Saturday morning, before gusty west winds 15-20 mph and plentiful sunshine take over for a windy and warm day for December 1st(Saturday). With areas across the western 2/3 of the CWA missing out on the more widespread wetting rainfall, the expected gusty west winds, low afternoon humidity values in the 20s, and warm temperatures will bring an elevated fire weather danger to a good part of the area. Despite the winds, the insolation and westerly flow leads me to believe model blends are trending too cool and have gone more into the lower-mid 70s most areas outside of the immediate Red River valley where cooler 925mb-850mb temperatures will reside. It is possible a low end wind advisory may be needed for especially the northern half of the CWA on Saturday. Mid level flow should continue to deamplify into more of a zonal flow overhead, as our strong shortwave disturbance departs northeast away from the area. The strong west winds will decouple and fall to around 10 mph overnight. Still, the dry airmass in place will allow lows Sunday morning to fall into the 40s areawide. 05/ && .LONG TERM... /Issued 346 PM CST Fri Nov 30 2018/ /Sunday Through Thursday/ Another mid level shortwave arrives Sunday and Sunday night and will amplify the flow aloft enough to support a cold front into the area late in this period(mostly Sunday night). This will bring the normal early December chill back to the region for the first half of next week and have leaned toward colder European and NAM temperatures for this time frame. Highs Monday and Tuesday will likely struggle to get out of the 40s with the expected strong low level cold advection and increasing cloud cover associated with this second shortwave disturbance. A few models are indicating enough frontogenesis within the mid levels from the Red River Valley into Oklahoma that some very light precipitation could develop. Unfortunately, much of this would struggle to reach the surface with much of the atmosphere below 700mb expected to be pretty dry. In addition, temperatures(even lows Monday morning) will remain above freezing, thus no wintry precipitation is expected. Freezing temperatures with continued brisk north breezes continue for Tuesday morning, however by this time all the frontogenetical and isentropic forcing will have exited the area well beforehand. Otherwise, a slow-warming trend occurs after a chilly start Wednesday and continues through the end of the week, as the cold and broad surface ridge slowly shifts east of the area with southerly low level flow and surface winds returning to the area. A strong mid level low or trough will organizes just off the Southern California coastline during this time with increasing low level warm advection and periodic disturbances arriving within the confluent, faster flow aloft over North and Central Texas. I have left a persistent forecast with increasing chances for a cold rain or showers, as highs struggle into the 50s and remain just under seasonal normals for first week of December. At this time, we do not expect any wintry precipitation for the end of the week. 05/ && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 55 75 47 66 41 / 30 0 0 0 5 Waco 53 75 47 72 44 / 30 0 0 0 0 Paris 54 70 45 63 39 / 70 0 0 0 10 Denton 52 73 44 64 38 / 30 0 0 0 5 McKinney 53 72 44 64 39 / 40 0 0 0 5 Dallas 56 74 48 67 43 / 30 0 0 0 5 Terrell 53 74 46 67 41 / 40 0 0 0 5 Corsicana 54 74 47 69 43 / 40 0 0 5 0 Temple 53 75 47 72 45 / 20 0 0 0 0 Mineral Wells 51 73 43 66 37 / 20 0 0 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$ 82
Area Forecast Discussion
National Weather Service Hastings NE
543 PM CST Fri Nov 30 2018 .SHORT TERM...(This evening through Saturday) Issued at 323 PM CST Fri Nov 30 2018 All systems are go for a high-impact winter storm. No changes in Warning/Advisory with this fcst pckg. This storm is on our doorstep. IR satellite is already showing a blossoming baroclinic leaf from Neb-TX. WV imagery shows the trof over the Desert SW has become negatively tilted. Aloft: A low will form over the TX/OK panhandles within the neg tilt trof tonight and head across Ern KS into SW IA by 00Z/Sun. Roughly a track from LBL-MHK-DSM. The low will stall near MHK for a time Sat. Surface: 994 mb low pres is along the CO-NM border at 19Z. The last 2 runs of all available mdls fcst it is deepen to 987 mb over NE KS by 12Z/Sat with it occluding over SE Neb during the day. Rest of this afternoon: Cldy with steady temps in the upr 30s- low 40s. There are some echoes on radar...but these are mid-lvl and falling into very dry air in the 850-700 mb layer. The closest reaching the ground is at HYS and CNK. But expect more and more of this to begin reaching the ground as sunset approaches. The NAM and NAM nest have been given the least weight in our reasoning due to its W bias. Prefer a blend of the 00Z/06Z/12Z GFS and 00Z/12Z EC and RAP mdls. Here is how we currently foresee this evolving: The rain you currently see over KS will blossom/expand as it lifts N and overspreads the CWA this evening. By midnight...the comma-shaped precip shield of rain will have developed and the dry slot will be heading N thru Ern KS. After midnight...the commahead will be rotating cyclonically over the GID CWA as the 700 mb low lifts to near CNK by 12Z/Sat. The temp profile is fcst to cool starting in the W around midnight (MCK-LXN-ODX) and that will begin to change the rain to snow. If sfc temps cool faster from CAA...the leftover warm nose around 780 mb could result in a little frzg rain in the transition. The rain should change to snow from W-E and by dawn most of the CWA should be snow. Mainly snow will fall thru the AM (6 am-12 pm). We are within 24 hrs of the event...and there is still uncertainty on where the dry slot will be at midday Sat. The GFS actually keeps the dry slot E of the CWA Sat with its slightly further SE low position. However ...prefer the EC which has been rock solid consistent on its low close to CNK (but the 00Z run was as far NW as HJH). I like the idea of the dryslot moving into our counties along and E of Hwy 281. The 12Z EC came in a little toward the GFS direction...not completely drying out the DGZ. At the least...we should see snow lighten up for a bit late AM to early afternoon along Hwy 81. If the 00Z EC is right though...snow could end for a bit (although light drzl or frzg drzl will probably be occurring). The 19Z RAP still supports the dry slot moving in E of Hwy 281. Snow will still be falling W of Hwy 281. As the 700 mb low heads E in the afternoon...snow will spread back into area E of Hwy 281. The heaviest rain/snow will fall tonight thru the daytime hrs Sat. Changes since the 4 AM fcst pckg: Used consensus of model 2m temps for tonights lows and tomorrows highs. That translates to temps remaining mostly at or a little above 33F...and less of a threat for icing/frzg rain. The warning/advisory message still mentions a light glaze. It can`t be completely ruled out...but it is not currently expected to be significant. Snow: Most of it will fall late tonight thru Sat...but some lighter snow will cont into Sat night and Sun. The snow character will be hvy/wet until sunset Sat. temps turn colder the SLRs ratios will increase and the snow will become lighter. Current expected accums are not much diff from earlier expectations: 1-3" N-cntrl KS 2-6" from Neb-KS state line up to Hwy 6 4-8" I-80 corridor 6-9" N of the Tri-Cities This has foot potential probably somewhere along and N of Neb Hwy 92. Winds: they ramp up late tonight and are worst thru Sat eve. Current expectation is 20-30 mph with G30-35 mph. Went above MOS based on 00Z/12Z 850 mb EC winds of 35-40 kt. That is disconcerting. The only reason I didn`t try to coordinate issuance of the Blzd Wrng is that the GFS winds are not as strong. If GFS comes in may be issued with later fcst updates. Blowing and drifting will be a problem...espcly after snow becomes lighter. Travel: Not recommended tomorrow. Thankfully this is occurring on the weekend and no commutes are involved. But be prepared for cancellations of scheduled activities. Some county roads could become impassable N of I-80. Expect plowing/de-icing ops at airports. Runway closures likely. accident on a limited access road like I-80 can result in big backups and delays. If it`s snowing heavily...that is bad news. If you plan to travel...take it slow and have blankets/food and water with you in case an accident slows down or halts travel. Do not leave your vehicle if you get stranded. We have coord with NDOT to enhance travel messaging. A conf call was also conducted with other public safety/emergency mgmt partners. Snow Reports: Please submit them via social media or via our webpage under Current Hazards --> Submit a report. We are especially interested on when you reach 6" at your location and any storm total amts. Any reports of mixed precip (frzg rain/sleet or rain/snow mix) will also be helpful. Skywarn/HAMs will be in the office tomorrow to help solicit reports. Thunder: could it occur? Absolutely...but it should be a couple isolated strikes here and there...probably SE of the Tri-Cities. At this point did not want to complicate the fcst further for something that will probably be brief. But know it`s a possibility. Concerns: 1) The changeover from rain to snow. Do we have it timed close? If it occurs later than expected...this will cut into snow amts. Just know that chgovr may be off an hr or 2. 2) Dry slot. It could be a major player and could impact the fcst negatively. If the GFS is right and the dry slot stays over Ern Neb...our current snow amts may not be high enough from Hwy 281-Hwy 81. 3) Associated with the dry slot...will sfc temps even be cold enough for frzg drzl? Consensus of short-term mdls indicates temps will hover around 33-34F. 4) Temps. They will be right on the edge for rain vs snow and are an important component in our precip type algorithm. If our temps are off even a little...this will impact what type of precip we are fcstg and when. 5) Will we need to upgrade to a Blizzard Warning? Am concerned about the stronger low on the EC. The 00Z/12Z EC winds at 850 mb are 35-40 kt 18Z/Sat-06Z/Sun. There is always a surprise with a storm like this. Rain changing to snow is espcly tough because we have to balance how much rain will fall before the chgovr. We have conveyed it the best we can. Minor adjustments probably will occur tonight as we hunker down and ride it out. Extra staffing will be on-hand here beginning at 4 AM. .LONG TERM...(Saturday night through Friday) Issued at 323 PM CST Fri Nov 30 2018 Sat night...periods of lighter snow with minor accum will cont Sat night thru Mon AM...but no appreciable accum is expected after Sun. The persistence of the light snow will be troublesome for those attempting to clear roads/parking lots and sidewalks. It will be periodic. It won`t be snowing all the time. Very little time invested beyond this storm. This sys will establish a new longwave trof over the CONUS with split flow. The EPO will spike negative next wk (AK high over an E Pac low off CA). This pattern always opens the door to direct Arctic discharge into the CWA. Sun begins a multi-day stretch of temps not reaching 32F over most of the CWA. In fact...most places will see highs in the 20s from Sun-Fri. This will probably be the coldest start to Dec since 2005! Tue-Thu are currently dry. Anything that might get added to the fcst later should be insignificant. Certainly some flurries or brief snow shwrs will be possible with the Arctic frontal passage Thu. There will be a late-week trof moving out of the Desert SW into the Srn Plns. Most of the precip is currently looking like it will remain S of the CWA. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday) Issued at 534 PM CST Fri Nov 30 2018 VFR and MVFR ceiling currently prevail at and near the TAF sites, but stratus is forecast to lower with ceilings dropping to IFR over the next couple hours. IFR (or lower) conditions are then expected to continue through the TAF period. Areas of rain are moving into the area currently. Off and on rain will continue overnight before changing to snow around 11-13Z Saturday morning. Model soundings indicate that snow may change to drizzle at times through the late morning and afternoon on Saturday. Wintry precipitation will continue through Saturday night and Sunday. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Winter Weather Advisory from 9 PM this evening to 6 PM CST Sunday for NEZ064-076-077-082>085. Winter Storm Warning from 9 PM this evening to 6 PM CST Sunday for NEZ039>041-046>049-060>063-072>075. KS...None. && $$ SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Mangels
Area Forecast Discussion
National Weather Service Goodland KS
847 PM MST Fri Nov 30 2018 .UPDATE... Issued at 847 PM MST Fri Nov 30 2018 have updated the forecast to add in a mention of an isolated thunderstorm thru 06z saturday for areas along and east of highway 25. a few isolated strikes have been showing up in the last hour. main concern for the mention of thunder is the isolated potential moderate rainfall that could briefly cause ponding on addition to reducing visibility for travelers with fog still around. && .SHORT TERM...(This evening through Sunday) Issued at 310 PM MST Fri Nov 30 2018 The Tri-State area is expected to be situated on the western/ southern periphery of an intensifying mid-latitude cyclone this weekend. Considerable uncertainty persists with regard to precipitation type/amounts -- which will be highly sensitive to the precise evolution of the parent upper wave and attendant surface cyclone lifting northeast from the TX Panhandle into central/eastern Kansas tonight and Saturday. The latest guidance has changed relatively little compared to prior model runs. The overall trend remains the same, i.e. greatest impacts will be north & east of Goodland -- in closer vicinity to the developing deformation band /strongest mid-level frontogenesis/ on the N-NW side of the intensifying surface cyclone. Through Tonight: With little in the way of low-level thermal advection, precipitation type is likely to be rate-driven this evening into tonight (i.e. the heavier the precip, the greater the chance it will transition to snow). High resolution simulated reflectivity products from the NAM NEST and HRRR suggest that convective precipitation may develop in eastern CO and extreme western KS (along/west of Hwy 27) this evening -- or north and east of Goodland overnight -- in association with strong DPVA /layer-lifting/ and the release of convective instability. In the aforementioned areas, locally heavy wet snow /thunder/ cannot be ruled out, though such situations are inherently low confidence. Saturday-Sunday: Strong NW winds are expected on the western periphery of the intensifying mid-latitude cyclone during the day Saturday, with maximum sustained winds in the 30-40 mph range and gusts as high as 50-60 mph, particularly in northeast CO and extreme northwest KS. Winds will gradually subside late Sat into Sat night. The latest guidance continues to suggest that the developing deformation band will narrowly miss the Tri-State area, with the bulk of precipitation falling to the north/east in central Nebraska. At the southern-western periphery of the deformation band in southwest Nebraska, snow accumulations could range from 3-6" (primarily Red Willow county). A tight gradient in snow accumulation is likely invof the NE/KS border. .LONG TERM...(Sunday night through Friday) Issued at 111 PM MST Fri Nov 30 2018 This period will be dry as an omega high develops over the Plains behind the exiting winter weather system. By Tuesday the high pressure will move east, with the upper level flow transitioning to northwest flow. A couple clipper systems will move through, however most of the lift associated with them will be north of the forecast area. Friday night another deepening upper level short wave trough will be approaching from the southwest. Surprisingly at this time the mean of the GEFS is also showing this short wave trough, similar to what the GFS and ECMWF both show. Current track shows most, if not all, of the precipitation remaining south of the forecast area. Temperatures will be coldest Monday and Tuesday, with lows falling into the teens. Wouldn`t be surprised if the lows continue their cooling trend in the coming days given the CAA; especially if the cloud cover is not in place. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 445 PM MST Fri Nov 30 2018 Dense fog transitioning to wintry weather will be main focus for both terminals. Conditions will be IFR or worse thru the forecast period with ceilings OVC002-003. KGLD may see switch to MVFR...BKN025/3sm 16z Saturday...but depends on speed of system. Visibility in snow/fog will be 1 1/2sm or less. Winds for KGLD...ENE around 10-20kts...especially before 03z. By 07z Saturday...N 15-25kts w/ gusts to 40kts after 16z. Winds for KMCK...E around 10kts thru 04z Saturday...becoming N around 10kts. By 07z...N 10-20kts w/ gusts to 35 kts after 12z Saturday. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...Winter Weather Advisory until 5 PM MST /6 PM CST/ Sunday for KSZ001>004-013>016. CO...Winter Weather Advisory until 5 PM MST Sunday for COZ090-091. NE...Winter Weather Advisory until 5 PM MST /6 PM CST/ Sunday for NEZ079>081. && $$ UPDATE...JN SHORT TERM...VINCENT LONG TERM...JTL AVIATION...JN
Area Forecast Discussion
National Weather Service Houston/Galveston TX
844 PM CST Fri Nov 30 2018 .UPDATE... Minor tweaks to the forecast package tonight in terms of temperatures and dewpoints. Main concern over the next few hours and into the overnight hours will be the areas of fog and at times dense fog along the nearshore waters and in both Matagorda and Galveston Bays. Have just gone ahead and added a Dense Fog Advisory in effect for Matagorda and Galveston Bay through 9 AM tomorrow morning. This sea fog does have the potential to drift inland along the coast, potentially hindering visibilities over the coastal counties. The dry line which is continuing to sag southward through the region tonight, and currently draped across the Red River Valley and back towards San Angelo will continue to shift southward through the overnight hours. This will eventually help visibilities to improve by the morning hours as dry air filters in. Besides the fog threat, there remains a chance for showers and isolated thunderstorms tonight. The HRRR at this time appears to be the best performer in terms of short term guidance and has a line of showers and isolated thunderstorms reaching our northern zones from College Station to Crockett between 06-09Z. As the surface low ejects east, the showers and potential for thunder along this boundary quickly dissipate leaving mostly light showers, mainly east of I-45. Otherwise, raised low temperatures overnight a touch to account for the shield of low clouds which should remain over the area through the morning hours. Hathaway && .PREV DISCUSSION... /ISSUED 624 PM CST Fri Nov 30 2018/ AVIATION... Ceilings this evening are making a transition from VFR to MVFR as airmass cools after sunset. Dewpoints in the upper 60s to low 70s will support lower ceilings. Winds should remain 5-10kts so do not expect there to be widespread fog but sea fog may be an issue for KGLS for much of the night. Ceilings should become high end IFR 04-07Z this evening ahead of a Pacific front. There may be some showers and perhaps an isolated storm for KCLL/KUTS but otherwise not expecting much activity tonight. Winds turn SW to W with the front around 10Z to 14Z across the area and drier air should mix and cause clouds to scatter. Look for VFR conditions mainly after 16Z with west winds. There could be some gusts around 20kts with good mixing in the boundary layer during the afternoon. Overpeck && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 59 75 48 75 50 / 40 0 0 0 0 Houston (IAH) 66 78 51 78 55 / 40 0 0 0 10 Galveston (GLS) 66 74 59 73 61 / 30 10 0 0 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION through Saturday afternoon for the following zones: Coastal waters from Freeport to Matagorda Ship Channel TX out 20 NM...Coastal waters from High Island to Freeport TX out 20 NM...Waters from Freeport to Matagorda Ship Channel TX from 20 to 60 NM...Waters from High Island to Freeport TX from 20 to 60 NM. && $$ Update...08
Area Forecast Discussion
National Weather Service Lincoln IL
914 PM CST Fri Nov 30 2018 .UPDATE... Issued at 913 PM CST Fri Nov 30 2018 Dense fog is expanding from east to west generally along the I-74 corridor. HRRR and RAP guidance are pointing toward an expansion of dense fog to the west. For now, the dense fog advisory was only extended westward to Woodford and McLean counties. Other nearby areas outside the advisory could see spotty dense fog as well. Dense fog should improve as rain develops from the south. Low temps have likely occurred in most areas already tonight, with southerly winds, increasing clouds and advancing rains all working to warm the surface temperatures the rest of the night. Main update this evening was to expand fog coverage and intensity. Otherwise, the remainder of the forecast looked on track. Widespread rains should be ongoing in our entire forecast area by sunrise on Saturday. && .SHORT TERM...(This evening through Saturday) ISSUED AT 236 PM CST Fri Nov 30 2018 Areas of fog are possible again tonight with increasing boundary layer moisture. Dense fog is possible this evening especially where deeper/melting snowpack exists across the far north. The dense fog should tend to dissipate after midnight as easterly winds increase in a tightening gradient ahead of deep low pressure over the southern Plains. Forecast focus is on storm system impacting the area tonight and Saturday as an occluded low pressure tracks into southern Iowa by Saturday evening. Elevated warm/moist advection ahead of this system will spread widespread showers across the CWA from south to north after midnight. Moisture transport and forcing suggests 0.50-1.00" rain totals will be common by time the warm advection precip shuts off from south to north during the morning hours. The surface warm front is expected to lift north of I-74 by 21z. South winds gusting over 25 MPH will help push highs in the mid 50s to mid 60s south of the front (except mid 40s where snowpack remains - primarily Knox to Stark counties). Attention turns to the chance for severe thunderstorm development during mid afternoon to early evening. As the dry slot overspreads the area, lapse rates steepen amid strengthening wind fields aloft. Forecast 0-6 km bulk shear of 40-50 kts combined with surface based CAPEs up 500 J/kg will support the potential for severe convection, ahead an approaching shortwave. This is a conditional severe weather threat, much will depend on some clearing to increase surface based instability. If forecast conditions materialize, severe wind gusts within a broken line of cells looks to be the primary severe threat, although the degree of low level wind shear (0-3km SRH 200-300 m2/s2) does suggest a few brief tornadoes possible. CAMs are in fairly good agreement with storm coverage and timing primarily 21z-01z. SPC 1730z/day 2 outlook shows marginal risk for most of the CWA south of where snowpack exists. The severe weather picture will become clearer as forecast details are worked out through tomorrow morning. .LONG TERM...(Saturday night through Friday) ISSUED AT 236 PM CST Fri Nov 30 2018 Low chance pops will remain over the northern third of the area for Saturday night through Sunday night, as the surface and mid level troughs linger over that area. Rain will be the dominant p-type through Sunday afternoon, with some light snow possible Sunday night. No accumulations expected. The remainder of the forecast is primarily dry and cold through the work week. Northwest flow aloft will keep temperatures well below normal with highs not expected to get out of the 30s. A couple weak disturbances for the last half of the week have low chance pops for light snow in the blended forecast. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 604 PM CST Fri Nov 30 2018 A strong surge of isentropic lift ahead of the approaching low pressure system will cause rapid saturation of the lowest levels of the atmosphere. Widespread rain showers will advance northward through central IL after midnight, with IFR, LIFR and even VLIFR conditions possible. LIFR looks to be the primary category at all TAF sites after around 04-07z. Per the latest HRRR, the LIFR clouds will form nearly overhead, or expand from east to west and south to north with time overnight. Very little improvement is expected for much of the day on Saturday, until the dry slot pushes over at least SPI after 21z, possibly bringing MVFR cloud ceilings. LLWS appears likely tomorrow morning, despite gusty surface winds. Will monitor for possible thunderstorm development earlier than 21z, which would preclude the need for non-convective LLWS. Wind directions will remain easterly until tomorrow afternoon, when they shift toward the southeast. Surface wind gusts of 25-30kt are expected during the steady rains late tonight and tomorrow morning. && .ILX WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until 6 AM CST Saturday for ILZ031-038- 043>046. && $$ UPDATE...Shimon SHORT TERM...25 LONG TERM...25 AVIATION...Shimon
Area Forecast Discussion
National Weather Service Paducah KY
901 PM CST Fri Nov 30 2018 .UPDATE... Issued at 901 PM CST Fri Nov 30 2018 Mid-evening update to extend and refine hourly forecasts of temperatures, wind, wind gusts,rain, and thunderstorm chances through 6 pm Saturday evening. From the perspective of the NAM/RAP guidance, mixed layer and most unstable CAPE profiles increase markedly in the surface to 3km layer in the western sections of southeast Missouri of the WFO PAH forecast area shortly after 12z, with a better contribution of CAPE above 1 kilometer through 15z. The RAP guidance this evening signals 0-2km lapse rates rising above 6C/km between 15-16z (9-10 am CST) Saturday over the western four counties of southeast Missouri. Anticipate that any thunderstorms developing in this corridor of sharper lapse rates will lead to a much greater probability of downward transport of winds approaching severe levels. Strong, mainly elevated storms may ramping up as early as 5-6am Saturday over extreme western sections of southeast Missouri. Hail and isolated damaging winds may be an initial concern with elevated storms in the 5 am to 9 am time frame over southeast Missouri. Damaging winds and isolated tornado potential may be slightly better in the 9 am to 1 pm time frame in eastern sections of southeast Missouri. The higher resolution guidance has been supporting a slower departure of deeper layer moisture ahead of the dry slot, so strong to potentially severe storms could linger into the middle of the afternoon east of the Mississippi River. Even with the passage of any line of storms, mixing within the lower levels of the atmosphere will likely generate wind gusts near 40 mph into the early early afternoon along and west of the Mississippi River after thunderstorms have passed through the area. This could place part of southeast Missouri close to Wind Advisory criteria along and west of the Mississippi River. Of course, heavy rain, generally between one and two inches will be most prevalent tonight into Saturday morning over southeast Missouri. If there is any training of storms east of the Mississippi River, locally higher amounts will be possible as well. Will need to watch for localized flood potential with higher rainfall rates. Had strongly considered adding a mention of severe storms in the text, tabular, and gridded forecasts for Saturday with this evening forecast update. However, the evolution and translation of the MCS`s in OK/AR may introduce slight mesoscale adjustments to the overall wind and moisture fields overnight and could impact any timing, intensity, or coverage of strong to severe storms. The same reasoning applies to any consideration of a Wind Advisory for southeast Missouri at this time. && .SHORT TERM...(THIS EVENING THROUGH Saturday) ISSUED AT 214 PM CST FRI NOV 30 2018 A lot going on during this period. Currently a warm front sits along the KY/TN border with 70 degrees to the south and 50s to the north. A few showers were along and mainly south of the boundary. The warm front is expected to lift north tonight as a trough at 500h moves from the southern Rockies into the southern Plains. A 80 kt jet round the base of the trough and subsequently a strong 850h jet of about 60 kts develops over Arkansas. Showers will become widespread this evening with a few thunderstorms as MUCAPE increases. Overnight a dry slot will form over Texas and Arkansas. Stronger storms may move into the far western portions of southeast Missouri toward dawn. The HREF has a few updraft helicity tracks over that area. Carter, Ripley, Wayne and Butler are now in a marginal risk for late tonight. By 12z the 80 kt jet at 500h extends into southwest Missouri along with the dry slot. The 850h jet is forecast to be along the Mississippi River at that time. Several CAMS have a squall line extending from near STL to POF at dawn. The RAP rapidly advances the dry slot and associated dynamics to near I-57 shortly after 15z. Other models hint at the same idea with some differences in timing. Some models push the dry slot through west Kentucky by 18z while others are slower. Ahead of the dry slot MUCAPEs may reach over 1000 J/kg. SPC has most of the area in a marginal risk tomorrow. The risk may be with this main line of convection. A few models hint at some development later in the afternoon over southeast Missouri along the cold front itself. If this occurs there still may be enough instability to produce a few stronger storms. As the dry slot reaches the area, Bufkit soundings suggest we mix to about 850h. This may allow for a few wind gusts to reach wind advisory criteria for a few hours from late morning into early afternoon. Will wait for another round of models before going with any advisories. .LONG TERM...(Saturday Night THROUGH Friday) ISSUED AT 214 PM CST FRI NOV 30 2018 The main story in the long term period will be a return to chilly temps next week. Little in the way of precipitation is expected. A few rain or snow showers cannot be ruled out early next week. There is a chance of some rain or snow toward the end of the week, but most of the precip should occur beyond this forecast period. As for Sunday, dry and mild southwest winds are expected ahead of a cold front over northern Missouri. Highs will range from the mid 50s to mid 60s. Although quite a bit of sunshine is forecast, gusty winds will make it feel cooler. The cold front will cross our region Sunday night, followed by noticeably colder northwest winds. Highs will be in the 40s Monday, then only in the 30s on Tuesday. The models continue to struggle with the timing and location of small 500 mb impulses within the broad trough over the central states. Several models indicate splotches of light qpf over our area Monday through Tuesday. There is not enough of a model signal to disrupt the dry forecast for Monday and Monday night. Will add a slight chance of snow showers for Tuesday in parts of our area, but basically nothing more than flurries is anticipated. Cold surface high pressure will build east across our region Wednesday and Wednesday night, bringing clearing skies and lighter winds. Highs will again be only in the 30s, with lows in the 20s. Thursday into Friday, moisture will begin to increase ahead of a strong Pacific storm system coming onshore across northern Mexico. At the same time, Arctic high pressure over the Plains is forecast to drive a cold front southeast into the lower Ohio Valley. There is a chance of snow showers Thursday night associated with the cold front, although boundary layer temps will be marginal for snow. The forecast for Friday will be mainly dry, following the gfs solution of colder and drier air arriving behind the cold front. For the most part, the 12z model suite keeps the surge of Pacific moisture just to our south on Friday. && .AVIATION... Issued at 533 PM CST Fri Nov 30 2018 For the 00z Saturday WFO PAH TAF issuance, the TAF locations will start out in IFR category with MVFR/VFR visibilities. As the frontal boundary near the KT/TN border works northward, there will be a gradual shift to MVFR ceilings over KPAH, KEVV, KOWB. Visibilities may drop back to down to MVFR and briefly IFR category as showers and storms continue to develop and work northward through the area Saturday morning and afternoon. Once the dry slot and moisture from the weather system moves east, VFR conditions should return for the end of the forecast period. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...Smith SHORT TERM...PS LONG TERM...MY AVIATION...Smith