Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/04/17

Area Forecast Discussion
National Weather Service La Crosse WI
554 PM CST Sun Dec 3 2017 .SHORT TERM...(Tonight through Monday) Issued at 255 PM CST Sun Dec 3 2017 At 2 PM, a 998 mb surface low was located over northeast Wyoming. Mid and high clouds ahead of this system were located across the Upper Mississippi River Valley. These clouds were holding down the temperatures some. For tonight, the 925 and 850 mb moisture transport will increase across the area. As this occurs, showers will develop across the area between 04.04z and 04.06z. These showers will then continue through Monday morning. There are even some hints in the soundings that there will be enough elevated instability for an isolated thunderstorm. After a brief drop in temperatures early this evening, strong warm air advection will allow temperatures to rise through the night. By sunrise, temperatures will be in the mid and upper 40s north of Interstate 94 and in the lower and mid 50s elsewhere. On Monday afternoon, the models are coming to a consensus that a dry slot will move into the area. The GFS and experimental HRRR even suggests that we could see some clearing. Temperatures will quickly climb to around 60 south of Interstate 94. These temperatures will be warm enough that a few records may be tied or broken. This near record or record warmth will be short lived as strong cold air advection moves in during the late afternoon. With winds gusts climbing up to 40 mph in southeast Minnesota and northeast Iowa, we will be issuing a Wind Advisory. These strong winds will then continue into Monday night. Unlike yesterday, the soundings look less favorable for thunderstorms on Monday afternoon. This is due to strong capping that develops above 850 mb. Due to this, lowered the thunderstorm chances from scattered to isolated. .LONG TERM...(Monday Night through Sunday) Issued at 255 PM CST Sun Dec 3 2017 High Impact Weather Potential: Watching winds Monday night with gusts of 40-50 mph quite likely. Will need a Wind Advisory for parts of the area (maybe all areas?), with a lower end chance that a few gusts could approach 55 mph in some spots. So, what month is this again? (checks calendar). Yep, that`s what I thought. It IS December. Guess it`s time to start forecasting cold weather again. Hope everyone has enjoyed the recent mild stretch as things come to a crashing end Monday evening and night. As well advertised for about a week now, the ongoing strong east Asian/Pacific jet that has flooded the Lower 48 with mild conditions is in the process of breaking down into a more typical Aleutians trough/western north American ridge, while ridging also builds across Greenland with time. That pattern looks to become rather stable for the next 1-2 weeks, opening the gates for much colder/more typical wintertime chill to spill into the Great Lakes and points farther south and east. The whole change begins Monday night with a rapidly deepening surface cyclone tracking over western Lake Superior, with a strong cold front exiting the area no later than 03Z. Impressive cold advection through the night will quickly steepen low level lapse rates as winds in the mixed layer ramp up into the 40-50 knot range coincident with a strong isallobaric response. Per forecast soundings, looking like a pretty good wind event for a few hours across the area (after Monday afternoon`s possible gusty conditions) with surface gusts of 40-50 mph likely, perhaps even briefly higher in a few open spots or ridge tops. Looking like a solid Wind Advisory event for areas west of the Mississippi River and have issued said advisory for those areas, including a period tomorrow afternoon where we could really mix out if skies clear for a time. Areas farther east into Wisconsin are a little more tricky as we may not see true advisory criteria for many locations (save for the ridge tops) so prefer to hold off at this point. Not looking like we`ll have to deal with much in the way of "wrap- around" deformation-driven snow as forcing across the local area quickly departs after 00Z. However, we will likely deal with periodic flurries or some very light snow at times through Tuesday night as persistent low/mid level cyclonic flow remains and a stratus deck working back across the area increasingly bisects the dendritic growth zone, though winds will gradually subside with time despite remaining on the breezy side. From midweek and beyond, all eyes will be on harder-to-time shortwaves dipping southward into the longwave trough axis centered roughly over the central Great Lakes, though there are persistent signals for the past 24 hours that a stronger wave will drop through the region sometime Thursday night or Friday with perhaps a little accumulating snowfall for some areas. Plenty of time to watch that system over the next few days as well as chances for occasional flurries, with the overall larger theme simply being a return to much colder temperatures for the foreseeable future. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 554 PM CST Sun Dec 3 2017 Multiple challenges through the period as a strong low pressure system impacts the region, including timing of lower ceilings/rain and timing/magnitude of low-level wind shear overnight. Latest sounding guidance suggests MVFR/IFR ceilings may be delayed until later tonight. Moved in that direction, but will need to monitor latest observations for possible amendments. Also delayed rain until later tonight as it will take some time for the low-levels to saturate. A dry slot will move into the region Monday afternoon, so removed rain before the end of the period. Some reductions in visibility into the 3-5 SM range are possible later tonight with the lowering of ceilings and rain. Also could see a few thunderstorms, but timing and coverage are in question, so will not include thunder with 00Z TAFs. Light surface winds this evening will gradually increase, so that by tonight, frequent gusts over 20 kts are likely. At the same time, 45 to 50 kts in the 1500 to 2000 ft agl layer this evening and overnight will result in low-level wind shear at both TAF airfields. Although these concerns wane Monday morning, expect surface winds to increase considerably, with frequent gusts from 25 to 35 kts at both KLSE/KRST. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...Wind Advisory from 3 PM Monday to midnight CST Monday night for MNZ079-086>088-094>096. IA...Wind Advisory from 3 PM Monday to midnight CST Monday night for IAZ008>011-018-019-029-030. && $$ SHORT TERM...Boyne LONG TERM...Lawrence AVIATION...Rogers
Area Forecast Discussion
National Weather Service Columbia SC
958 PM EST Sun Dec 3 2017 .SYNOPSIS... Dry high pressure building across the region will move offshore late Monday. A strong cold front crossing the area Tuesday night into Wednesday will bring widespread showers. Much colder air will settle over the region for the end of the week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... The dry surface ridge will extend through the forecast area during the overnight hours. Nocturnal cooling and light wind may help cause fog. The latest models continue to trend towards fog. For the most part, at this time think patchy fog should be the rule late tonight, although some locations near rivers and low- lying areas may see thicker fog. Overnight lows will be in the 40s. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... High pressure aloft off the East Coast will provide the region with dry and unseasonably warm weather Monday through Tuesday. High temperatures will be 5 to 10 degrees above normal. A strong cold front will sweep across central South Carolina and east central Georgia Tuesday Night into early Wednesday as the Eastern U.S. undergoes a major pattern change. Expect a period of showers associated with the frontal passage and perhaps partial clearing on Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... A deep upper trough descends on the Eastern U.S. and will usher in much colder than normal temperatures from Thursday into next weekend. The front which moved through the region on Wednesday stalls along the coast Thursday into early Friday. Models differ on the exact placement and the amount of development of a wave of low pressure along the frontal boundary. This impacts the amount of rainfall possible during this time period. Another short wave moving through the base of the upper trough pushes the frontal boundary well offshore on Friday into the weekend. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... VFR early tonight. There is potential for fog restrictions toward daybreak mainly at fog prone terminals. VFR after 13z. The ridge will extend through the area tonight. Nocturnal cooling and light wind may help cause fog although the fog may be limited somewhat by the dry air mass and a little mixing. The latest HRRR suggests fog will be limited. This is supported by LAMP. However...based on recent mos trends will leave a period of MVFR with lower visibilities at AGS toward daybreak. East winds develop after 12z mainly light. EXTENDED AVIATION OUTLOOK...MVFR or IFR conditions may occur Tuesday and Wednesday associated with a strong cold front moving into the region. MVFR or IFR conditions may linger into Friday with the front just east of the area. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ S
Area Forecast Discussion
National Weather Service Green Bay WI
527 PM CST Sun Dec 3 2017 Updated aviation portion for 00Z TAF issuance .SYNOPSIS... Issued at 218 PM CST Sun Dec 3 2017 Warm and becoming windy with periods of rain tonight through Monday, very windy Monday night, then much colder for the rest of the week. Amplification of the large scale flow is now underway. During the next several days, a sharp ridge will build along the West Coast, forcing a deep trough near 90W. This round of amplification should peak by the start of the weekend. Though perhaps losing a little amplitude thereafter, the high amplitude pattern is likely to persist for at least an additional week. Temperatures will remain 20-25 F degrees above normal through tomorrow, then drop back to 5 to 10 F degrees below normal by mid-week. The below normal temperatures will linger for the remainder of the forecast period, and quite possibly to the middle of the month. The bulk of the precipitation will occur as a strong cyclone crosses the region the next couple days. The system will access Gulf moisture and should be a pretty good precipitation producer. But having the dry slot drive right through the forecast area will temper amounts. Once that system departs, there are likely to be several additional light precipitation events as shortwaves rotate through the deep eastern North America upper trough. It`s reasonable to expect that most of the area to end up with near or slightly above normal precipitation amounts for the period. && .SHORT TERM...Tonight and Monday Issued at 218 PM CST Sun Dec 3 2017 The latest RAP analysis and satellite/radar imagery show flattened ridging across the western Great Lakes early this afternoon, ahead of a deep trough digging over the western conus. The jet stream is already spreading a thick layer of mid and high clouds across the northern Mississippi Valley ahead of this trough. With broad southerly winds developing across the Plains, the leading edge of Gulf moisture is lifting north into northern Missouri. As the deep trough and associated strengthening surface low move east, forecast concerns revolve around precip trends, chances for thunderstorms, and strong winds on the Bay and Lake. Tonight...Low pressure will emerge from the Rockies and move east across South Dakota/Nebraska. Ahead of the low, mid and high clouds are anticipated to lower some, while Gulf moisture surges northeast across the area during the late evening and overnight hours. The latest guidance and progged soundings suggest that precip may start out as a drizzle over north-central WI late in the evening, before increasing saturation depth changes precip to rain showers overnight. Showers to become more widespread overnight, with elevated instability increasing late, and think there could be a small chance of a thunderstorm over central WI and the southern Fox Valley after 3 am. Temps are expected to remain relatively steady this evening, and then rise overnight. Monday...The low pressure system will strengthen as it swings northeast towards western Lake Superior. With elevated instability increasing up to 500 j/kg and pwats above 1 inch, expect showers and a few thunderstorms to remain widespread during the morning, particularly over northern WI. The mid-level dry slot then lifts into the area during the afternoon, which supports ending of the heavier shower activity, but plenty of low level moisture should maintain a light shower/drizzle scenario. It will become warm and windy, with some gusts between 30 to 40 mph possible over the Fox Valley and Lakeshore. Highs ranging from the low to mid 50s. .LONG TERM...Monday Night Through Sunday Issued at 218 PM CST Sun Dec 3 2017 An intense cyclone will track from the western tip of Lake Superior early Monday evening, to central Ontario by mid-day Tuesday. A cold front wrapping around the system will surge across the area early Tuesday evening. Timing of the FROPA is now forecast to occur a little more quickly than the models indicated yesterday. Regardless, the main impact will be wind. Expect a surge of 45-55 mph wind gusts along and immediately behind the front. This could result in some downed trees and power lines, especially across the north where coniferous trees are more prevalent. Will continue to highlight potential wind impacts in the HWO. Although there are still some model differences with the track of the cyclone, the consensus is now that the track will be far enough west and the movement of the system quick enough that the cusp of the comma head will lift through to the west of the forecast area rather than pivot back into north-central Wisconsin. That will limit the snow potential across the north. But even just an inch of snow could make for difficult travel conditions across the north Tuesday given the wind. Though timing remains elusive, there will likely be additional light precipitation episodes during the remainder of the period as shortwaves rotate through the long-wave trough entrenched across the region. Temperatures will be cold enough for snow, and a light snow cover could gradually begin to become established across the region. Temperatures, especially at night, may require downward adjustment in future forecasts if a snowcover becomes established. && .AVIATION...for 00Z TAF Issuance Issued at 527 PM CST Sun Dec 3 2017 VFR conditions to continue this evening with increasing mid to high level clouds ahead of developing low pressure system approaching from the west. Conditions expected to deteriorate late tonight as cigs lower to mvfr levels and rain becomes widespread. Widespread rain will continue on Monday as conditions lower to IFR. LLWS conditions expected to develop later tonight as well and continue into Monday. && .MARINE... Issued at 218 PM CST Sun Dec 3 2017 A deepening low pressure system is expected to track across the northern Great Lakes region later tonight through Tuesday. South winds will be on the increase late tonight into Monday with gale force gusts starting on Monday morning on Lake Michigan. Then subsidence in the dry slot Monday night will produce westerly gale gusts with the potential of storm force winds toward the open waters. These conditions will persist into Tuesday before gradually tapering off. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS.......Skowronski SHORT TERM.....MPC LONG TERM......Skowronski AVIATION.......Kurimski MARINE.........MPC
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
955 PM EST Sun Dec 3 2017 .SYNOPSIS... High pressure will linger over the region through Monday. A strong cold front will then approach on Tuesday and move east of the forecast area late Wednesday. Below normal temperatures will persist into the weekend. && .NEAR TERM /THROUGH MONDAY/... As of 945 PM: Temps dropping off faster than expected in some spots because of the dry air mass and nearly clear sky. Will make some adjustments to low temps in some of the mtn valleys, especially around Franklin and over the nrn mtns. Otherwise, as an upper ridge axis pivots toward the East Coast tonight into Monday, a high pressure airmass over the Mid-Atlantic region will follow, resulting in a dry northerly flow at the surface with veering winds aloft. Though an upslope flow develops above the PBL late tonight, moisture appears insufficient for much cloud cover to develop. Furthermore, fog will be less expansive tonight than it was last night, with greater sfc dewpoint depressions. Temperatures will run a couple categories above normal in most places. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... As of 200 PM EST Sunday: The short term fcst period kicks off on Monday night amidst a departing upper ridge axis along the east coast making way for height falls consequent of a deep/progressive trof digging across the central CONUS. At the surface, northeast high pressure extending southward in lee of the Appalachians will begin to slide out to sea, all the while allowing flow across the southeast to veer ely/sely into Tuesday morning. By that time the upper pattern will feature a closed low over the upper Midwest while a region of surface cyclogenesis moves in cadence beneath, both driving a cold Canadian airmass and thus surface cold front across the MS valley into the OH valley. Pops will gradually ramp up through the morning hours Tuesday as sly moisture advection leads to weak upglide potential ahead of the front, as well as upsloping along the southern facing slopes of the mtns. The front is set to arrive into the NC mtns Tuesday night with quite a bit a shear to accompany thanks to a nearly 100kt H5 jetmax. Llv flow ahead of the front is somewhat veered, yet strong as guidance favors nearly 50-60kts at H850. Fortunately given the limited window of waa pre fropa, little if any sbcape cape is progged. This will limit not only the deep convective threat, but the sfc momentum transfer component as well which should keep any higher winds confined to elevations above 4-5kft. Therefore, pops will increase further in association with the fropa overnight into Wednesday morning with likely/cat levels favored regionwide. Pops will then taper through the late morning hours Wednesday leading into a dry forecast to round out the period. Falling snow levels across the high terrain could yield some brief snow showers for elevations above 5kft Wednesday morning, yet with little/no accumulation. Caa behind the front could lead to fairly breezy conditions on Wednesday, however at this point below any wind advisory criteria. Lastly, temperatures on Tuesday will hover at near normal levels, before falling post fropa amidst said caa regime with highs on Wednesday a few degrees below normal. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 230 PM Sunday: A deep upper trough will continue to dig across the central CONUS Thursday thru Friday, as a polar vortex drops south into the Great Lakes. The trough axis will remain west of the Appalachians thru Saturday, then begin to pivot east Sunday. The models agree on this general idea, but there is still some disagreement on the details associated with embedded shortwaves rounding the base of the trough. The 12z GFS has come in with a very vigorous vort max diving into the trough and crossing the southern Appalachians Friday night. The 12z ECMWF is a little deeper and bring it thru the area Saturday. Whenever that wave comes thru, it will bring a slug of moisture and likely a round of snow showers in the mountains, possibly with a few showers across the Piedmont, due to the strong forcing. For now will keep PoPs in the slight CHC to low-end CHC range, close to the WPC timing, which is mostly Friday night. The 850 mb flow will be quite backed as the trough axis remains to the west. So there will be a lack of good upslope flow, and hence, not expecting much accums. Regardless of how much snow we see across the area, it will certainly feel like winter, as temps will be well below normal. Highs will be as much as 10-15 deg below normal, and lows around 10 deg below normal. The coldest day being Saturday and Saturday night. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... At KCLT and elsewhere: High pressure over the Mid-Atlantic region will keep VFR conditions across the region this evening and overnight. The main problem will be the potential development of a fog restriction over the Piedmont of NC and how close it will get to KCLT. The model guidance is generally split on this one. In most instances, the fog develops east of KCLT and does not make it past the warmer heat island around CLT, and the airfield remains VFR. That is how we will play it, keeping a prevailing VFR, but a TEMPO will be introduced for the MVFR fog restriction in deference to the more pessimistic RAP model. Any restrictions should burn off by 14Z at the very latest. Thereafter, it will be VFR thru the end of the period. Winds will slowly veer around as the center of high pressure moves off the Mid-Atlantic coast on Monday. There will probably be a period with a light easterly cross-wind during the middle of the day. Right now, have elected to switch the wind around to ESE at 19Z based on LAMP guidance, but it could happen several hours earlier or later than that. Outlook: Restrictions and precipitation develop Tuesday as a cold front moves in from the west. After a brief return to VFR, coastal low pressure developing at the end of the week may lead to more restrictions, particularly in the Piedmont. Confidence Table... 03-09Z 09-15Z 15-21Z 21-00Z KCLT High 100% High 100% High 98% High 100% KGSP High 100% High 100% High 100% High 100% KAVL High 100% High 100% High 98% High 100% KHKY High 100% High 100% High 95% High 94% KGMU High 100% High 100% High 100% High 100% KAND High 100% High 94% High 100% High 100% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JPT NEAR TERM...PM/Wimberley SHORT TERM...CDG LONG TERM...ARK AVIATION...PM
Area Forecast Discussion
National Weather Service Wichita KS
543 PM CST Sun Dec 3 2017 .SHORT TERM...(This evening through Wednesday night) Issued at 207 PM CST Sun Dec 3 2017 Strong post-frontal winds in the cold advection regime behind the cold front on Monday is the main concern. A significant upper trof will continue moving across the western CONUS this evening and tonight, before moving into the northern/central Plains on Monday. There remains continuity and model consensus on the timing of the initial cold front across central Kansas to the turnpike corridor by midday. Steep low level lapse rates are expected in the cooling/much drier regime just behind this front across central Kansas from late morning into the afternoon. The deep mixing will result in transfer of higher momentum air to the surface with winds expected to breach advisory criteria. The lower humidity levels will also elevate the grassland fire danger. Meanwhile, modest low level moisture transport will result in weak to modest instability ahead of the cold front across southeast Kansas. Some early morning drizzle will be possible with widely scattered convection expected to develop by midday or early afternoon. While isolated storms will be possible, it appears the better lift and moisture will be realized as the convection develops just east of the forecast area later in the afternoon where a few strong storms will be possible. The upper trof will deepen as it lifts northeast across the Upper Midwest/western Great Lakes Monday night with the stronger secondary cold front and much colder air plunging south across central and eastern Kansas. This will result in temperatures closer to seasonal climo on Tuesday, though feeling much colder considering the recent stretch of mild weather. West to northwest winds look to become gusty again Tuesday afternoon over central Kansas as well. The first in a series of shortwave upper trofs will begin to move south into the developing eastern CONUS longwave on Wednesday with subtly cooler air settling south into Kansas. Darmofal .LONG TERM...(Thursday through Sunday) Issued at 207 PM CST Sun Dec 3 2017 The deep longwave upper trof over eastern North America and high amplitude blocking upper ridge near the west coast of North America will prevail through the end of the week. Confidence remains high on temperatures trending slightly below climo by Thursday and Friday as rather robust shortwaves dropping south within the mean longwave result in progressively stronger cold air intrusions across the Midwest and lower Plains. Some very light snow, mainly flurries, may also accompany this chilly air across northern and eastern Kansas. There is some indication of the western CONUS upper ridge weakening a bit by the weekend with the mean trof shifting across the northeast CONUS. That said, only minor temperature moderation is expected with readings climbing to slightly above climo by Sunday. KED && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 541 PM CST Sun Dec 3 2017 Main aviation concerns are timing of MVFR ceilings and frontal passage. All models show low level moisture streaming north overnight. RUC appears to have best handle out of the box based on clouds across N TX. This plus its fairly quick movement of front tonight, opted to base forecast on it. This puts KHUT/KSLN right on western fringe of MVFR ceilings. Frontal passage in the morning will shunt low level moisture east fairly quickly. Very strong and gusty northwest winds will develop in the wake of the front. -Howerton && .FIRE WEATHER... Issued at 207 PM CST Sun Dec 3 2017 Strong northwest winds and much drier air behind a strong cold front on Monday will elevate the grassland fire danger into the very high category from the Flint Hills westward across central Kansas. The strongest winds and lowest humidity levels are expected from midday thru the afternoon over central Kansas where a few hours of extreme fire danger is possible. The Fire Weather Watch may be upgraded to a Red Flag Warning with later forecast updates if confidence increases on attaining the much lower dew points in the afternoon. The air will remain very dry on Tuesday with west to northwest winds increasing again in the afternoon across central Kansas, mainly closer to the I-70 corridor. This is expected to result in a few hours of very high grassland fire danger. KED && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 57 64 27 50 / 10 10 0 0 Hutchinson 54 62 25 49 / 0 0 0 0 Newton 55 62 25 48 / 10 10 0 0 ElDorado 58 65 27 49 / 10 10 0 0 Winfield-KWLD 59 67 28 51 / 10 10 0 0 Russell 48 56 21 48 / 0 0 0 0 Great Bend 49 57 21 48 / 0 0 0 0 Salina 54 62 24 49 / 0 0 0 0 McPherson 54 62 24 48 / 0 0 0 0 Coffeyville 60 70 31 51 / 30 50 10 0 Chanute 59 68 29 49 / 30 40 0 0 Iola 58 67 29 48 / 30 40 0 0 Parsons-KPPF 60 68 31 50 / 30 40 10 0 && .ICT WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Monday morning through Monday afternoon for KSZ032-033-047>051-067. Wind Advisory from 11 AM to 6 PM CST Monday for KSZ032-033- 047>051-067. && $$ SHORT TERM...KED LONG TERM...KED AVIATION...PJH FIRE WEATHER...KED
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