Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/20/24


Area Forecast Discussion
National Weather Service La Crosse WI
606 PM CST Thu Dec 19 2024 .KEY MESSAGES... - Second round of widespread snow moves in later this afternoon and comes to an end from west to east after midnight. Highest amounts of 2 to 4 inches are looking to fall along and south of I-90 and the winter weather advisory has been expanded southward to account for this trend. - Cooler and drier for the weekend. - Warming up for next week with several potential rounds of snow. && .DISCUSSION... Issued at 150 PM CST Thu Dec 19 2024 This Afternoon - Tonight: Snow Continues, Gradually Ends This was a challenging storm to nail down even at the 11th hour as the compact wave that drove our round of heavy snow this afternoon took a southerly track, bringing the axis of heaviest snow farther south along with it closer to the I-90 corridor. Early amounts of 4 to 7 inches have been reported within the current warning outline. Upstream, a secondary vort lobe is tightening on water vapor imagery over eastern South Dakota and preparing to eject eastward along the MN/IA border. A narrow region of isentropic ascent and frontogenesis is manifesting itself over southwestern Minnesota and progged to slide ESE this afternoon and evening, affecting mainly areas south of I-90. Did expand the winter weather advisory southward to account for these latest trends, with matches the recent morning outputs from the HRRR as well. Did downgrade areas north of I-94 to an advisory with this southern track and most areas in the warning likely will only see another 1-3 inches of snow before the storm system departs overnight. Winds increase out of the northwest late tonight into Friday morning in the wake of the surface low that tracks through the region this afternoon and evening. Could see some drifting given the light nature of the snow that may keep roads slick into the morning hours on Friday. Friday - Sunday: Cooler and Drier Longwave ridging builds west of the region for the end of the week and the weekend, keeping the threat for impactful weather at bay. We will end the week on a cold note in the wake of today`s system with high temperatures falling into low 20s and lows in the single digits for Friday night. Surface high pressure slides east of the region by late Saturday, allowing for warmer air to return gradually Sunday and into next week. Highs for the next week look to climb back into the mid to even upper 30s, but the new snowpack may modulate these temperatures downward. Monday: Next Round of Snow An active zonal to northwesterly upper level flow ushers in another clipper wave off the Rockies and through the region on Monday. Current trends have been favoring the system to impact mainly Wisconsin with majority of the the ensemble members clustering around 1 to 2 inches for snow. Given the fast-moving nature of this system, this remains a sensitive forecast and could easily shift over the next several days. There is some signal for another round of precipitation for the end of next week, but there exists a large spread in the guidance on if/when that might happen. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 605 PM CST Thu Dec 19 2024 Snow continues trudging east to southeast through the area this evening, with reductions in visibility down to 1-2SM miles. A lull in the snowfall is expected to move northwest to southeast across the area over the next several hours behind the current snowfall, although snow flurries may continue during this period. The next main bout of snow is currently across northwestern Minnesota, and is expected to make its way into the area around 05z. This snowfall looks to be lighter and does not look to be as impactful as what has transpired today, but visibilities of 1-3SM are possible as it passes through the area. MVFR to IFR ceilings continue overnight, but scattering and lifting of the cloud deck begins Friday afternoon. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Winter Weather Advisory until 3 AM CST Friday for WIZ017-029- 053>055-061. Winter Storm Warning until 3 AM CST Friday for WIZ032>034- 041>044. MN...Winter Weather Advisory until 3 AM CST Friday for MNZ086-087- 094>096. Winter Storm Warning until 3 AM CST Friday for MNZ079-088. IA...Winter Weather Advisory until 3 AM CST Friday for IAZ008>011- 018-019-029-030. && $$ DISCUSSION...Skow AVIATION...Falkinham
Area Forecast Discussion
National Weather Service Columbia SC
754 PM EST Thu Dec 19 2024 .SYNOPSIS... The end of this week looks mostly cloudy and cooler. A cold front clears skies out Friday into Friday night, with breezy conditions possible later in the day. This will be followed by several days of cold weather with subfreezing temperatures at night. A warming trend is expected towards Christmas along with the next chance of rain. && .NEAR TERM /UNTIL 7 AM FRIDAY MORNING/... Key Message(s): - Considerable clouds and cooler tonight. Surface cold front has pushed offshore with upper troughing moving over the forecast area, ushering in a colder air mass tonight with cold advection at the surface. Low level moisture trapped beneath deep layer dry air will continue to support low level clouds across the area which will limit the degree of cooling overnight. Temperatures expected to drop into the mid to upper 40s. Some HiRes guidance is indicating the potential for light showers near daybreak with warm advection around 850mb providing some limited lifting. With PWATs around or below 0.6 inches across the area, however, it will be tough for any light showers to produce measurable rainfall through tonight. && .SHORT TERM /7 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... Key Message(s): - Decreasing cloudiness behind a cold front on Friday with similar daytime temperatures to today. - Breezy conditions possible behind the front. A Lake Wind Advisory may be needed if trends continue. - Noticeably colder on Saturday with subfreezing temperatures at night. A series of shortwave troughs will be moving through the region during the period. At the surface, a clipper system will move from Indiana southeast into North Carolina on Friday, with a cold front clearing out the persistent cloud cover over the FA from southwest to northeast. The passage of the first shortwave on Friday could trigger isolated showers but with limited moisture confidence is low, less than 20 percent, with the highest probabilities across our northernmost counties. Given the stronger winds aloft, breezy conditions may develop behind the cold front and could require a Lake Wind Advisory for at least the CSRA with the next forecast package. Daytime temperatures will be similar across the Northern Midlands and 5-10 degrees cooler in the Southern Midlands and CSRA. With clear skies and cold air advection, temperatures will fall into the upper 20s to lower 30s by daybreak on Saturday. The cooling trend continues into Saturday as high pressure builds in from the west, weakening the pressure gradient. Having said that, winds may start off on the breezy side making temperatures feel even colder. This will be the first of several days of below normal temperatures. Conditions will be more favorable for radiational cooling Saturday night, allowing temperatures to fall into the 20s. Even colder temperatures are expected the following night. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Key Message(s): - Sunday and Monday are the coldest days of the period, followed by a warming trend. - The next storm system arrives around Christmas Day. Surface high pressure will pass to our north on Sunday and Monday, maintaining a cold, dry air mass over the region. Temperature and moisture advection occurs Tuesday and Wednesday as the high moves offshore and the next storm system approaches. Confidence remains high that there will be several days of below normal temperatures, falling below freezing each night. The period of greatest concern remains Sunday night when wind chill values could approach Cold Weather Advisory criteria across portions of the CWA. Regardless of whether advisory criteria is met, it is important that cold weather preparations are made ahead of time, especially for those who will not be home during this period. Temperatures and PWATs increase during the middle of next week, but an approaching storm system will bring the chance for rain around Christmas Day. Timing of this system is low so it is not a guarantee that Christmas will be wet. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... MVFR ceilings expected to deteriorate to IFR possible overnight. Widespread low clouds continue across the area with MVFR cigs at all terminals, although cigs have been bouncing around between MVFR/VFR at AGS/DNL which is on the edge of the cloud field. However, latest trends in satellite are showing reformation in the CSRA so expect MVFR cigs all terminals through the evening hours. Cigs are expected to lower through the night and could lower into the IFR range as HRRR and some MOS guidance suggests, although some guidance keeps cigs in the MVFR range so lower confidence in the IFR cigs at AGS/DNL. An approaching upper trough will increase low level flow from the south during the predawn hours and lower clouds should begin to erode from southwest to northeast through the day Friday. Expect VFR cigs to return at AGS/DNL by 12z and at CAE/CUB/OGB by 16z. Winds should be light from the north to northeast overnight before shifting to the southwest around 12z-13z then as a cold front crosses the region by late morning winds shift to the west and increase to around 10 to 15 knots with gusts over 20 knots through the afternoon. EXTENDED AVIATION OUTLOOK...No significant impacts to aviation. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$
Area Forecast Discussion
National Weather Service Charleston SC
853 PM EST Thu Dec 19 2024 .SYNOPSIS... High pressure will prevail through Friday. A dry cold front will move through Friday night, followed by arctic high pressure this weekend into early next week. A trough will develop over the area by the middle of next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Sea fog has managed to spread through the coastal waters into coastal Georgia and parts of coastal South Carolina in the last hour or two. This has prompted the issuance of a coastal Dense Fog Advisory and marine Dense Fog Advisory...valid through the night. Previous discussion... KCLX radar from late afternoon revealed a sea breeze boundary pressing inland off the Atlantic, intersecting the southeastward moving arctic boundary (leading edge of the CAD)...which is now slipping down through southeast Georgia. Even had a few showers pop across the CHS area along the boundary intersection. Behind the boundary, low stratus is expanding quickly southeastward through the local forecast area. Per recent RAP guidance, arctic boundary might get hung up across the far southern part of the forecast area in the next several hours, although guidance RH forecasts suggest low cloud cover will continue to ooze down through the rest of the forecast area. Thus cloudy skies/becoming cloudy will be the rule through the night. Temperatures will dip into the middle 40s to lower 50s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... Considerably cooler, drier air will spread in from the west during the day Friday. Sky cover will diminish from west to east late morning to early afternoon, with mostly sunny skies for most areas during the afternoon. Downslope flow will help push temps up a couple degrees, allowing lower 60s to be attained. A reinforcing, dry cold front will sweep through Friday night, followed by Arctic high pressure Saturday through Sunday. Highs on Saturday will be in the 50s while Sunday stays in the upper 40s across southern SC and southeast GA climbs briefly into the lower 50s. Cold advection and some radiational cooling Saturday night will allow temps to dip into the upper 20s away from the coast. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Sunday night will be quite chilly due to cold advection and some radiational cooling. Wind chill values will likely dip into the 15-20 degree range for a couple hours late Sunday night into Monday morning, and a Cold Weather Advisory is possible. Monday will again be chilly, though temperatures will rapidly rebound Tuesday into Thursday as the Arctic high shifts offshore. A few coastal showers are possible Tuesday as a coastal trough develops just offshore. Wednesday into Thursday, at least scattered showers will be possible across the area as a potent upper trough approaches and low pressure moves in from the southwest. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Surface boundary will slip through portions of southeast Georgia this evening. In it`s wake, low (IFR-MVFR) stratus has quickly expanded through southeast South Carolina and southeast Georgia over the last several hours with conditions quickly trending IFR-MVFR at the terminals...a bit quicker than previously forecast. Latest terminal forecasts feature IFR-MVFR ceilings at all terminals through the overnight hours. Drier air spreads quickly into the region on Friday with conditions rapidly improving to VFR at the terminals, first at KSAV around sunrise and at KCHS/KJZI Friday mid morning. Lighter winds tonight. Westerly winds increase on Friday with some modest gustiness anticipated during the afternoon. Extended Aviation Outlook: VFR. && .MARINE... Tonight, a sfc low off the Carolina coast will continue to develop, tracking slowly to the ENE. A sfc trough is expected to slowly drift over the marine zones through late tonight. This pattern should result in a surge of NE winds across the SC nearshore waters this evening, gusts approaching 25 kts at times. Winds should settle to around 10 kts by late tonight. Seas are forecast to generally range between 3 to 5 ft through tonight. NW winds will increase Friday night as a reinforcing cold front slides through. Gusts to 25 kt expected across all waters except Charleston Harbor (where 20 kt gusts are more likely). Seas should briefly build to 6 ft over outer reaches of the offshore GA waters as well. We issued a Small Craft Advisory for these waters from 4pm Friday through 10am Saturday. Conditions will improve a bit on Saturday, though we cannot rule out additional advisories from time to time due to a persistent tight gradient and potential for 25 kt wind gusts through Monday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...Dense Fog Advisory until 7 AM EST Friday for GAZ117>119- 139>141. SC...None. MARINE...Small Craft Advisory from 4 PM Friday to 10 AM EST Saturday for AMZ350-352-354-374. Dense Fog Advisory until 7 AM EST Friday for AMZ352-354-374. && $$ NEAR TERM...Adam/NED SHORT TERM...JRL LONG TERM...JRL AVIATION...Adam/JRL MARINE...Adam/JRL/NED
Area Forecast Discussion
National Weather Service State College PA
909 PM EST Thu Dec 19 2024 .SYNOPSIS... * Widespread light snow accumulation on Friday-Friday night before another arctic cold snap arrives this weekend * Chilly and dry start next week followed by a gradual warmup and mixed precipitation potential Christmas Eve and Christmas Day && .NEAR TERM /UNTIL 7 AM FRIDAY MORNING/... Meso models continue to generate more than trace amounts of precip before sunrise (just about as late as sunrise can get, now). Have bumped the PoPs up into likelies (60s) for all the western-most counties of the CWA before 12Z. Will add just 0.1" onto those that didn`t have before then which certainly does not bump anyone into a widespread 3+" for the event. Prev.... Clouds aloft are already spreading over the Alleghenies, only furthering the cloudy narrative for tonight. Breaks are possible in the s-cent counties. Developing easterly flow will continue to veer overnight, and draw moisture in from the south as the storm approaches. Broad-scale lift over PA and seeding of lower cloud layer should result in light snow beginning late tonight/before sunrise over the central mtns and Alleghenies. The temps should be able to creep into the m20s for most of the area overnight. Temp/moisture profile aloft is favorable for OK but not giant, fluffy dendrites N of I-80, and SLRs are progged to be very close to climatology (10:1 S and 15:1 N). This is a little lower than most Clippers. So, if anyway, the SLRs may go upward. && .SHORT TERM /7 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... As forcing continues to increase from the approaching Clipper system, coverage of light snow will expand across central PA by mid to late morning. Parent trough feeds significant secondary development off of the mid Atlantic coast late Friday as the upper trough takes on a negative tilt. Focus by this time will hinge on strength of llvl easterly flow and convergence axis progged to setup beneath the left exit region of a mid/upper level jet streak. Potential interaction of these features could allow for a slowly pivoting NNW-SSE oriented band of deformation snow (NORLUN trough) to organize over the far eastern part of the forecast area Friday afternoon through Friday night, potentially favoring higher snowfall totals, but certainty for this remains on the lower side and will need further evaluation this evening and overnight. For now we`re staying close to NBM/WPC QPF/Snow output and SLRs with overall amounts ranging from 1-3" in the western and northern mtns to a coating-1" for most areas along and to the southeast of the I99/I80 corridor from the south central Alleghenies through the mid and lower Susquehanna Valley. Increasingly colder NWly upslope flow on the backside of the system may also enhance snow totals over the Laurel Highlands through Friday night. WPC probs are slightly better than 50/50 for >4" of snow in the typically favored windward slopes, ski areas, and summits above 2000ft particularly in western Somerset County near intersection of Westmoreland/Fayette line. Some discussion about potential headlines for this with neighbors for later Friday, but consensus was to hold off and SPS the morning arrival of snowfall if necessary Friday morning. The pattern turns brisk and much colder to start weekend with lake effect snow showers and flurries into Saturday night. Models show a potential Huron connection over the western mtns with an additional inch or so possible in the higher terrain. Highs on Saturday will be 10 to 15 degrees below the historical average with max temps in the 20-30F range. A brisk and gusty NW wind will make it feel like the single digits/teens to around 20F. Saturday night will be quite cold with min temps in the +single digits to upper teens with minimum wind chills from -5F to +10F into early Sunday morning. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Northwesterly flow continues into the beginning of the long term, with lingering lake effect snow showers across NW PA finally tapering off on Sunday. It will be another cold day, however, with highs across Central PA running well below average (mid teens north to upper 20s south). The sfc high is progged to drift of the East Coast Sunday night into Monday, with a light southeasterly flow developing. After a very chilly start to the day, Monday afternoon will be a few degrees milder than Sunday but still chilly. CLouds will be on the increase Monday night, with our next weather maker bringing light snow or a rain/snow mix into the region late Monday night into Tuesday. The weather will remain a bit unsettled through the middle of next week, although we should continue to see a trend towards slightly milder temperatures as the week progresses. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Recent observations outline VFR prevailing across much of the forecast area outside of the western (BFD/JST) airfields. At JST, recent GLAMP/RAP model soundings outline some potential for scattering of the low-level deck which reasonably (50-60% confidence) will allow for a brief period of VFR conditions in the 03-06Z window. Alternative solutions are that low-level clouds scatter out slightly earlier and allow for a longer period of VFR flight conditions with the latest reasonable time for conditions to dip down towards MVFR ~08Z Friday with enhanced low-level moisture and cloud cover making way into the airfield ahead of precipitation. Consensus of recent model guidance keeps borderline MVFR-to-IFR conditions at BFD throughout the entire TAF period, so have outlined ceilings below IFR thresholds throughout the majority of the TAF period with moderate-to-high (70-80%) confidence outside of a brief window of MVFR ceilings in between 03-06Z progged by model soundings and GLAMP guidance, with the latest reasonable timing of MVFR ceilings resolving towards MVFR ~09Z Friday. Around 10Z Friday, snowfall is progged by the bulk of model guidance to enter the western airfields with BFD/JST the first airfields to remain/resolve towards IFR thresholds based on visibility. Restrictions will continue to spread towards all airfields of central Pennsylvania, reaching MDT/LNS closer to the 14Z Friday timeframe. There remains some uncertainty with regards to the initial fall in ceilings/visibilities at MDT/LNS with GLAMP guidance outlining an initial fall towards MVFR ceilings before IFR prevails 1-2 hours later with RAP model soundings outlining a more drastic fall in visibilities. For this TAF package, have veered closer to the GLAMP solution based on some uncertainty on initial low-level moisture at MDT/LNS; however, could realistically see a more drastic drop in visibilities if snow showers makes way into these airfields closer to the 15-16Z Friday timeframe. Some heavier bands of snow could bring localized drops towards LIFR, with recent HREF probabilities outlining the best chances at BFD/JST but confidence remains too low (~30%) to include outright in the form of a FM group; thus, have included mentions with a PROB30. Outlook... Sat...Lingering SHSN NW/SW PA; Gusty winds ~25-30kts across the higher elevations during the late AM/PM hours. Sun...SHSN Far NW PA; otherwise, no sig wx. Mon...No sig wx. Tue...Snow enters W PA AM, overspreads area by afternoon. && .CLIMATE... Astronomical winter (solstice) begins on Saturday, December 21st at 4:19 a.m. EST. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir/Steinbugl NEAR TERM...Dangelo SHORT TERM...DeVoir/Steinbugl LONG TERM...Evanego/NPB AVIATION...NPB CLIMATE...Steinbugl
Area Forecast Discussion
National Weather Service Blacksburg VA
758 PM EST Thu Dec 19 2024 .SYNOPSIS... Low pressure over the Upper Mississippi Valley will sweep across the Ohio Valley on Friday then off the New England Coast by Saturday bringing snow to the mountains. Colder temperatures with high pressure follow for the weekend. Temperatures warm on Monday and Tuesday ahead of low pressure over the Southern Plains. && .NEAR TERM /THROUGH FRIDAY/... As of 730 PM EST Thursday... Key Messages: 1) Winter Weather Advisories issued for the mountains of SE WV, SW VA, and NW NC for snow and gusty winds. 2) Elsewhere west of the Blue Ridge, expect mainly rain, with the piedmont staying mostly dry. Made a few adjustments to temperatures for the overnight based on the overcast cloud cover across the area. Areas of stratus had encroached from both the WNW and the SW this evening. A wedge of high pressure over the NE counties of VA will weaken tomorrow morning as 1. low pressure moves out of the OH Valley, and 2. low pressure off the Mid Atlantic coast organizes. This will allow for precipitation to develop as a short wave dips into the Mid Atlantic region. The highest amounts of snow will be in the 2 to 4 inch range for our higher peaks, and models are indicating an area west of a line from Lewisburg, to Burke`s Garden, to Boone to have the best chance for +1 inch of snow. Lower elevations in the mountains will see mostly light rain with some snow possibly mixing in towards Friday evening. A couple things to note, moisture will be limited due to the low moving up the Eastern seaboard, robbing us of some QPF. Additionally, the wind trajectory is more westerly until the cold front pushes through tomorrow late, not providing the best angle for upslope snow during the day. The upper trough digs so deep that the strongest part of the short wave may miss us to the SW, but we should still have enough lift for accumulations in the western mountains. Confidence in accumulating snow is high for the western mountains. Confidence in the rest of the area seeing much precipitation through Saturday is low. As of 120 PM EST Thursday... Key messages: - Clipper will bring snow to the mountains starting Friday afternoon Robust short wave and surface low pressure system over the Upper Mississippi Valley will reach the Mid Atlantic region on Friday. Cloud cover fills in this evening and overnight. Isolated to scattered light rain and snow showers are expected to cross the area Friday morning with little impact. The more organized area of snow will remain confined to the mountains. HRRR and FV3 models show about a six hour period of moderate snow Friday afternoon and evening before the precipitation becomes primarily upslope driven overnight. Probabilistic guidance maintains up to 40 percent probability of 2 inches of snow by Friday evening, with the highest potential from Tazewell County through western Greenbrier County. The surface cold front crosses through the area on Friday with the wind becoming northwest and the cold air advection becoming stronger by Friday afternoon. Similar to conditions Thursday morning, temperatures will only see minimal warming on Friday due to all the clouds. Not much deviation from guidance needed for lows tonight. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... AS OF 300 PM EST THURSDAY... KEY POINTS: 1) Areas west of the Blue Ridge will see scattered snow showers Friday afternoon through midday Saturday. 2) Much colder air will move into the region, keeping temperatures well below average through the period. As the axis of an upper-level trough moves across the area Friday evening, snow showers will persist through the overnight along and west of the Blue Ridge as northwesterly flow will cause orographic lifting. East of the Blue Ridge, isolated showers may bring a trace of rain to parts of the piedmont, but mostly dry conditions will continue. Snow accumulations have trended up since yesterday, especially for the NC/VA mountains, where 1-2" is expected with the higher elevations seeing 2-4". The same can be expected for Summers and Mercer counties in WV. Western Greenbrier County in WV will see the highest accumulations, around 3-5" and possibly up to 6". Along the Blue Ridge, little accumulation is expected with a trace to a few hundredths expected. The snow showers continue through midday Saturday before the trough moves off to the east, with drier air filling in which will shut off the snow showers. Saturday will be breezy, especially along the Blue Ridge, with wind gusts over 35 mph before reducing Saturday night. Saturday night into Sunday and Monday will be very quiet, as a large high pressure system over the northeastern US will dominate the weather pattern for several days, slightly wedging the RNK CWA in through Tuesday. Temperatures will remain well below average through the weekend, with highs in the 30s and 40s, with higher elevations remaining in the upper 20s. Monday`s highs will be in the 30s area-wide. Low temperatures will be in the 20s Saturday morning before falling into the teens and 20s Sunday and Monday morning. A few single digit lows will be possible Sunday morning in the highest elevations. Winds will remain light during the coldest period, with wind chill not being a hazard. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 300 PM EST THURSDAY... KEY POINTS: 1) Temperatures rebound to near normal for the entire period. 2) Quiet weather will continue until late on Christmas Day, when another system moves into the area. High pressure will continue to control the weather pattern for Christmas Eve and part of Christmas Day, with dry weather persisting. 500mb heights will continue to slowly rise, which will allow temperatures to return to around normal. Early Christmas morning, a stray rain shower may move into the piedmont as high pressure backs out to the northeast, with a warm southerly flow bringing moisture back into our area. A few locations may initially see rain mixed with snow in the WV/VA Highlands, but will quickly turn to rain. Models do not agree on whether this will occur, therefore confidence is low and PoPs are also kept low, around 20%. As a low develops across the Mississippi Valley and moves east, it will begin to weaken as it approaches. Most locations will receive rainfall from this system as it arrives late on Christmas Day overnight into Thursday. Models again disagree on the strength of the system, with the ECMWF having very scattered precipitation across the CWA, while the GFS has more widespread rainfall. Nonetheless, rain showers will continue through the end of the period. Temperatures rebound nicely midweek, with highs in the 40s, rising further into the 40s and 50s late week. Low temperatures will also slowly rise mid to late week with 20s on Tuesday morning rising into the mid 30s by Thursday morning. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS of 700 PM EST Thursday... A mix of MVFR and VFR stratus was currently over the region, with some mid and high clouds also in the area. Expect lower MVFR conditions to develop overnight into early tomorrow morning for ROA, LYH, and DAN, with rain developing tomorrow afternoon. BLF and LWB will see IFR/LIFR conditions at times, and are more likely to see a changeover to SN in the afternoon. Elsewhere, rain/snow chances will diminish in the evening. A cold frontal passage will bring gusty WNW winds to the beginning tomorrow afternoon into Saturday, with gusts in the 20 to 30 kts range, except for DAN and LYH which will be lighter. EXTENDED AVIATION OUTLOOK... -SHSN chances continue for BLF and LWB into Saturday morning, and could drop vsbys as low as IFR. The mountains return to VFR for Sunday morning. Dry and warmer VFR conditions are expected Monday and Tuesday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Winter Weather Advisory from 1 PM Friday to 1 PM EST Saturday for VAZ007-009-015. NC...Winter Weather Advisory from 1 PM Friday to 1 PM EST Saturday for NCZ001-018. WV...Winter Weather Advisory from 1 PM Friday to 1 PM EST Saturday for WVZ042-043-508. && $$ SYNOPSIS...AMS NEAR TERM...AMS/SH SHORT TERM...JCB LONG TERM...JCB AVIATION...SH
Area Forecast Discussion
National Weather Service Topeka KS
433 PM CST Thu Dec 19 2024 .KEY MESSAGES... - Winds pick up this evening with sharply colder air arriving tonight into Friday morning. - Warmer conditions return by Sunday with mild temperatures through the Christmas holiday. - Mainly dry weather is forecast aside from a chance of rain (15- 40%) Monday night into Tuesday morning for east central KS. && .DISCUSSION... Issued at 159 PM CST Thu Dec 19 2024 The upper air pattern early this afternoon consists of northwest flow over the Northern and Central Plains ahead of a ridge over the Intermountain West. Eastern KS finds itself in the southwest quadrant of a low pressure system centered over IA, and winds are slowly turning to the west and northwest as a result of that system progressing across the Upper Midwest. The cold air behind the associated sfc front is still well north of the area into NE and SD as of 19Z. Guidance has CAA strengthening into the area after 00Z, at which point northerly winds should also start to increase with quicker pressure rises behind the front. Wind gusts look to be at their peak between 00-06Z before gradually diminishing through the night and eventually subsiding by mid-day Friday with the sfc high overhead. Still can`t rule out a few gusts around advisory criteria this evening with 40-45 kt gusts aloft, although the HRRR is notably the most robust in bringing advisory-level winds to the surface whereas all other models fall just short of criteria. Additionally, the HREF probabilities of 45+ mph gusts are generally 40% or less across the area except for a few isolated locations for an hour or so. Based on this, it would seem reasonable to expect brief wind gusts to this magnitude at some locations, but still did not have the confidence in widespread advisory-level winds for a long enough duration to warrant an advisory. Winds still look gusty overnight but to a lesser extent before decreasing Friday. This strong push of cold air will allow temperatures to plummet to the teens by morning with wind chills in the single digits, even around zero in some locations. High temperatures Friday will struggle to reach the freezing mark for the vast majority of the area. Transitioning into the weekend, the aforementioned upper ridge will help temperatures to moderate with highs reaching the 40s Saturday and eventually back to the 50s in some places by Sunday. The upper ridge flattens Sunday as a shortwave trough moves through the Northern Plains and brings another associated cold front through the region. This doesn`t look to have much of an impact on temperatures, but could bring some rain to east central KS where PoPs are currently forecast at 15-40% for Monday night into Tuesday morning. Otherwise, dry and mild weather looks to continue through Christmas Day with highs in the upper 40s to 50s and lows in the 30s. There is more variation in the guidance in the Wednesday night to Thursday time frame, but there are indications of another trough swinging across the region with perhaps better precipitation chances across the area. However, there are plenty of differing ideas on the timing, strength, and track of that system so confidence in its evolution remains rather low. Temperatures do still look warm enough to support rain. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 433 PM CST Thu Dec 19 2024 Dry air advection behind the front will keep VFR conditions in place. Post frontal winds look to remain gusty through the morning Friday. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Picha AVIATION...Wolters