Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/15/24


AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
1014 PM EST Sat Dec 14 2024 .SYNOPSIS... High pressure remains north of the area throughout tonight keeping the region cool and dry. A weak disturbance brings a chance for light rain Sunday afternoon into early Monday. Warmer weather arrives next week along with a couple of chances for rain. && .NEAR TERM /THROUGH TONIGHT/... As of 1015 PM EST Saturday... Key Messages: - High pressure keeps the region cool and dry for tonight. - Cloud cover will continue to increase overnight ahead of our next system. Latest analysis reveals 1049+ mb sfc high pressure over southern Quebec and northern New England this evening, with sfc ridging extending south into the lower mid-Atlantic and the Carolinas. Aloft, low-amplitude ridging over the region continues to slowly dampen ahead of a shortwave trough that is currently taking on a neg tilt as it ejects northeast from the mid MS valley toward the western Great Lakes. Regional satellite showing a good amount of mid to high clouds over the region, though some pesky stratocu induced from the onshore flow. Past few runs of the HRRR and RAP continue to show these clouds eventually scouring out overnight. Overall, mostly cloudy overnight with the abundance of cloud cover holding temperatures into the upper 20s to lower 30s across the piedmont to the northern neck/eastern shore, and upper 30s and lower 40s along the coast. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 300 PM EST Saturday... Key Messages: - Chilly weather continues Sunday, with a good chance for light rain for the area. Best rain chances will be over the northern half of the area Sunday afternoon through Sunday evening. - Drying out Monday afternoon as a warming trend commences. A subtle upper level shortwave will traverse the region Sunday bringing a chance of light showers across the area. As high pressure remains dominant over the New England, the overrunning moisture will serve to strengthen the CAD already in place. As the decaying low pressure system moves to the northeast across the Ohio River valley, it will bring in a small chance of light precipitation across the region. Given the weak overrunning and rather dry sub-cloud layer, this would translate to drizzle initially by mid to late morning, though periodic light rain will be possible in the afternoon and evening over the piedmont, as better slug of overrunning moisture pushes into the area. Overall though, the lack of deep-layer moisture and weak forcing will make for very light rainfall totals, with QPF on the order of one-tenth of an inch or less, most of which will be northwest of RIC. These showers will quickly then move off to the east through Sunday evening and into early Monday morning. Monday remains slightly drier across the area with the best chance of Pops residing across the north where the best moisture resided with another system moving across the Great Lakes. As for temperatures, Sunday will be the coolest day and could remain cooler than forecasted as the strong CAD remains in place. Temperatures across the the piedmont are expected to rise into the upper 30s to middle 40s where heavier cloud cover is expected to remain. While along the coast slightly less cloud cover and on shore flow will allow temperatures to rise into the middle to upper 50s. Cloud cover is expected to remain potent through the evening hours and temperatures across the piedmont will not change as much as the temperatures near the coast. Lows will be in the middle to upper 30s across the piedmont and lower to middle 40s along the coast. The CAD will stay in place through Monday with clouds slightly clearing up along the coast. Highs will be in the lower to middle 50s across the piedmont and lower to middle 60s along the coast. Mondays lows will be warmer than previous nights with temperatures falling into the middle to upper 40s inland and lower 50s along the coast. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 300 PM EST Saturday... Key Messages: - Mild temperatures continue Tuesday and Wednesday. A few light showers are possible Tuesday morning along a weak frontal boundary. - A better chance of rain is expected later later Wednesday into Thursday. A weakening front slides through the region Tuesday. The models continue to trend drier with this system as the system is cut off from moisture due the SW flow at the surface and aloft. As such, have confined PoPs to mainly slight chance to low chance in the morning with the highest PoPs at the coast. Warm advection pre-FROPA should allow for mild temps for the whole area, with the current forecast depicting highs in the mid-upper 60s (locally 70 F possible NE NC). Lows Tuesday night in the 30s NW to 40s SE as high pressure briefly settles over the area. Highs again look to be on the mild side Wednesday as there will be very little in the way of cold advection behind the front, with 50s and 60s a good bet. There also appears to be a better chance of rainfall for most of the area from later Wednesday into Thursday as a deep-layer trough and cold front approach. There remain some differences among the 12z guidance about coverage of precip Wednesday, with more consensus about higher coverage Wednesday night and early Thursday. Will therefore keep chance PoPs mainly in the afternoon on Wednesday, but bump PoPs up to likely Wed night. Highs on Thursday will likely be earlier in the day with the FROPA expected in the morning. But highs Friday will likely be much chillier (in the 40s/lower 50s) with strong cold advection expected. Saturday could end up being even cooler with the upper trough overhead. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... As of 715 PM EST Saturday... Predominate VFR conditions (LCL MVFR at PHF/ORF) across local terminals will persist through this evening and through much of the day tomorrow before gradually degrading late in the 00z TAF period. High pressure over New England is wedging down into the area early this evening, producing some low-level stratocu along the coast on light NNE flow. RAP/HREF are in good agreement that these clouds scatter out this evening, leaving predominate VFR overnight. However, have allowed for a brief period of MVFR persisting for a couple of hours this evening at ORF/PHF before CIGs recover to VFR after 02-04z/ Cirrus will also increase and thicken overnight ahead of the next disturbance. NE winds hover around 5 kt late tonight while remaining out of the NE. Overrunning moisture then slowly pushes into the area tomorrow into tomorrow night, with CIGs gradually lowering from late Sunday morning through Sunday afternoon. Rain chances increase Sunday afternoon and night into Monday morning as the next shortwave approaches and onshore flow continues. Sub -VFR conditions are looking likely across the piedmont by late Sunday afternoon, reaching area terminals around and after midnight Sunday/early Monday. Outlook: MVFR conditions with periods of light rain continue inland (along and NW of KRIC/KSBY) on Monday into Monday afternoon. VFR conditions look to hang on along the SE terminals through Tuesday. A weakening cold front slides through the region on Tuesday into Tuesday night, with some scattered precipitation and brief sub- VFR CIGs possible. More widespread showers and sub-VFR CIGS will be possible with a stronger cold front crossing the region late Wednesday into early Thursday. && .MARINE... As of 655 PM EST Saturday... Key Messages: - Small Craft advisories are in effect for portions of the marine area today through tomorrow as strong high pressure builds north of the region. Update: Added the lower James River to SCA headlines as observations show winds increasing to 15 to 20 kt with gusts to 25 kt. Also increased seas to 4-6 ft south of the VA/NC border to better match buoy observations. Remainder of the forecast is on track. Strong 1047mb high pressure is centered from QB into NY, eastern PA and NJ this afternoon. The high will strengthen as it slowly slides E tonight, then `weaken` slightly as it slides offshore from Maine tomorrow. This results in a decent pressure gradient and breezy NE winds through the rest of the weekend. Latest obs reflect NE winds ~15kt for most locations, a few knots higher over NC waters/Currituck Sound. Seas have built to 4-5ft S of Cape Charles Light. SCAs are in effect for the lower bay, southern coastal waters, and Currituck Sound. The SCA for the lower James was cancelled early given obs showing sub-SCA winds for the last couple of hours with no expectation of coming back up. Overnight and into tomorrow, winds will be 15-20kt over coastal waters, 10-15kt in the bay and rivers. Seas will continue to build in the ongoing onshore flow with northern waters reaching 5ft late tonight/early tomorrow. As such, SCAs for these zones start in the early morning hours Sun. The wind diminishes Sunday night and Monday as the high shifts farther offshore with a surface ridge axis lagging into the Mid- Atlantic region. A weak cold front slides across the coast later Tuesday with weak high pressure arriving Wednesday. A SW wind ahead of the front will shift to NE behind the front but is expected to remain less than 15kt. Overall sub-SCA conditions are expected to prevail early-middle of next week once seas subside to less than 5ft. A stronger cold front arrives Thursday with SCA conditions likely later next week. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 4 AM EST Sunday for ANZ632-638. Small Craft Advisory until 6 PM EST Sunday for ANZ633. Small Craft Advisory until 4 AM EST Monday for ANZ634. Small Craft Advisory from 7 AM Sunday to 7 AM EST Monday for ANZ650. Small Craft Advisory from 4 AM Sunday to 7 AM EST Monday for ANZ652-654. Small Craft Advisory until 7 AM EST Monday for ANZ656-658. && $$ SYNOPSIS...HET NEAR TERM...HET/MAM SHORT TERM...HET LONG TERM...MRD AVIATION...HET/MAM MARINE...AM/RHR
Area Forecast Discussion
National Weather Service La Crosse WI
510 PM CST Sat Dec 14 2024 .KEY MESSAGES... - Freezing rain persists into the evening hours with additional ice accumulations possible, especially outside of river valley locations. - Areas of fog will be possible tonight as precipitation exits, some may be locally dense and occur in areas where temperatures are below freezing across southeast MN and northeast IA. - Seasonably mild temperatures with highs in the middle 30s to lower 40s are expected into Monday with returning rain/snow chances (15-30%) north of I-94. && .DISCUSSION... Issued at 308 PM CST Sat Dec 14 2024 Today - Tonight: Wintry Mess Continues Into Tonight A challenging winter weather forecast remains for the rest of today and into tonight with snow, sleet and freezing rain being observed throughout the morning and transitioning mainly to rain/freezing rain for this afternoon. Currently, the surface low responsible for our unsettled weather remains along the souther IA/MO border and is slowly progressing its way east/northeastbound. As this occurs, the broader area of rain/freezing rain/sleet overhead will gradually move east. MRMS 1-hr radial ice accumulation rates within this generally are around 0.01"/hr to 0.03"/hr currently across southwestern WI and northeast IA. Still some uncertainty on thermodynamics throughout the rest of the afternoon and evening with recent RAP soundings at La Crosse still wanting to uncomfortably hold right on the 0 degree C isotherm with an ever so slight warm nose throughout much of the afternoon and into the evening. So while current observational trends favor the ongoing rain/freezing rain, this will need to be taken with the consideration that a slight shift in the low-level thermodynamics could suddenly change precipitation type. This is especially true along and north of I-90 where the 850mb warm nose is less apparent and so snow cannot be ruled out of the equation later this afternoon and evening. Additionally, noting some fairly low MRMS probabilities (20-40%) for below freezing road temperatures with some areas of western Wisconsin, especially in valley locations, seeing above freezing road temperatures. Regardless, the 14.12z HREF still has extremely high confidence (90- 100% chance) of at least a glaze south of I-94 with modest probabilities (70-90% in NE IA) for over 0.1" with MRMS radial ice accumulation already exceeding 0.1" from Fayette to Grant Counties. So given these conditions, travel will be slippery to hazardous this afternoon and evening and should be avoided if possible, especially after sunset where additional freezing is more likely. Looking towards the overnight, precipitation begins to exit with narrowing low-level saturation. However, lingering lift allowing and remaining low-level saturation may provide additional freezing drizzle throughout the overnight in addition to fog development across portions of southeast MN/northeast IA. Fog could be locally dense in some locations going into the morning hours which with below freezing temperatures could lead to additional travel concerns. Overall, the main takeaway over the next 12 to 18 hours or so is that locally hazardous travel conditions will be possible in some spots so care should be taken if traveling through the evening and overnight. Sunday - Early Next Week: Seasonably Mild Temperatures Through Monday As we get past this ice event, some weak upper-level ridging builds in for Sunday and Monday which will allow for our temperatures to warm above freezing with highs in the national blend progged from anywhere in the middle 30s to lower 40s. Our next weather disturbance comes in the form of a fairly decent upper-level trough on Monday. However, given the antecedent warm air ahead of it and its quickly progressing nature, decent probabilities (20-40%) remain for a fairly quick hitting rain with some snow mixed for further north locales. Cold air advection then moves behind this wave with high temperatures cooling back below normal by the middle of the upcoming week with highs in the 20s to lower 30s areawide. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 510 PM CST Sat Dec 14 2024 CIGS: expect IFR/LIFR to quickly return this evening, and should hold there through the day Sunday. MIght not see much improvement until later Sunday night into Monday. WX/vsby: pcpn will persist through the evening. HRRR/RAP soundings favor mostly liquid, but some suggestions a couple hours of SNPL possible between 00-03z. Trends turn to drizzle later this evening/overnight as the depth of the saturation diminishes (keeping ice out of the cloud) and the heavier bands of pcpn shift east with the parent low pressure system. Mostly MVFR vsby impacts with the pcpn, but with the near sfc layer well saturated from the pcpn, SREF/HREF guidances suggest 1/4SM FG will develop at KRST (80% chance) with valley location at KLSE potentially holding more 1-2SM. Fog will linger through Sunday morning with some improvement Sunday afternoon. Models provide a variety of different outcomes (some keep it MVFR, others P6sm). Will keep it MVFR for now. WINDS: easterly through the night, shifting more southeast later Sun morning. Expect some decrease/slackening overnight as sfc low moves just south of the TAF sites, picking back up a few ticks moving into later Sun afternoon/night. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Winter Weather Advisory until midnight CST tonight for WIZ032>034-041-042-053>055-061. Winter Weather Advisory until 3 AM CST Sunday for WIZ017-029- 043-044. MN...Winter Weather Advisory until midnight CST tonight for MNZ079- 086>088-094>096. IA...Winter Weather Advisory until midnight CST tonight for IAZ008>011-018-019. Ice Storm Warning until midnight CST tonight for IAZ029-030. && $$ DISCUSSION...Naylor AVIATION.....Rieck
Area Forecast Discussion
National Weather Service Bismarck ND
949 PM CST Sat Dec 14 2024 .KEY MESSAGES... - Patchy fog is possible through the afternoon across portions of the James River Valley, expanding in coverage and potentially becoming dense tonight. - There are low to medium chances (20 to 60 percent) for a light glaze of ice across most of the west and south central. Ice accumulations up to a tenth of an inch are possible across the far northwest. - There are medium to high chances (50 to 90 percent) for snow accumulations of at least an inch Sunday through Monday morning west and north central. && .UPDATE... Issued at 943 PM CST Sat Dec 14 2024 Low stratus continues across eastern North Dakota and the James River Valley. Winds remain elevated hindering fog formation. No updates needed at this time. && .UPDATE... Issued at 559 PM CST Sat Dec 14 2024 Low stratus continues across the state with visibility reductions in the James River Valley. There is a chance that dense fog could form in the James River Valley into south central North Dakota later tonight, therefore we will continue to monitor it. This could lead to freezing fog and light ice accumulations on surfaces and roadways leading to slick conditions. Precipitation remains out over eastern Montana with the timing still forecast to move into the west early tomorrow. && .DISCUSSION... Issued at 238 PM CST Sat Dec 14 2024 Western and central North Dakota currently sits under a stagnant split flow pattern aloft with a closed low well to our southeast and a deepening Pacific Northwest trough to our west. This pattern has led to plenty of cloud cover, especially across the central and east which is currently socked in with low stratus and patchy fog. Further west, clouds are more of the upper level variety. Patchy fog has been confined mainly to the James River Valley thus far. Guidance does not have a good handle on the afternoon fog, but most short term guidance does have fog becoming more widespread west and north through the night and Sunday morning. For now, we are keeping fog as patchy through the night but based on pattern recognition, would not be surprised if fog becomes dense enough for an advisory at some point. Transient ridging will cross the state tonight, keeping temperatures mild for this time of year with lows mainly in the lower teens to lower 20s. By tomorrow morning, we transition into amplified southwest flow aloft as the western trough approaches. Precipitation chances will also increase with the approach of this trough. As the initial synoptic forcing enters the west late tonight into tomorrow morning, models suggest there will some favorable overlap of moderate midlevel frontogenesis and the stronger synoptic forcing across the far northwest. These features may end up producing a narrow band of locally higher precipitation rates somewhere across northeast Montana and northwest North Dakota. Additionally, the latest HRRR and NAMnest soundings here suggest textbook freezing rain profiles for several hours in the morning. That being said, some uncertainty in precipitation type is still evident as global model soundings suggest a cooler warm nose and much quicker transition to all snow. Deterministically, it seems reasonable that we could see ice accumulation totals up to a tenth of an inch across the far northwest. Further south, another embedded shortwave will skirt the south and may lead to some light freezing rain Sunday morning also, but will not have the added benefit of enhanced frontogensis. Therefore, we have low to medium confidence (20 to 60 percent chance) of ice accumulations up to a light glaze across the rest of the west and portions of the south central. For these reasons, we decided to go ahead and issue a Winter Weather Advisory for most of the west from 06z tonight through 00z Monday. The advisory may need to eventually be expanded into portions of the south central but enough uncertainty remains here to hold off for now. Precipitation chances will move east through the day on Sunday, gradually changing to all snow in the afternoon (the far south may continue to see some light rain or freezing rain but amounts may be limited here thanks to dry slotting). The best chances (50 to 90 percent) for snow accumulations of at least an inch will be across the northern half of the area, mainly along and north of the Highway 200 corridor. Increasing that threshold to two inches and the best chances max out in the 40 to 60 percent range, mainly confined to the Turtle Mountains and vicinity. Thus, it seems a good bet that we will see a swath of 1 to 2 inch totals through Monday morning across the north central with some locally higher amounts in and around the Turtle Mountains. Winds will also shift to out of the northwest and increase late Sunday afternoon through Sunday night, leading to some patchy blowing snow where light accumulations do fall. Precipitation chances move out to the east by Monday afternoon, mainly giving way to breezy/windy conditions. The strongest gusts should be in the vicinity of the James River Valley on Monday afternoon with some gusts in the 40 to 45 mph range possible before relaxing Monday night. A couple other weak waves will move through the quasi-zonal and then northwest flow aloft through the rest of the week (Tuesday and Thursday) with only some light snowfall expected at this time. Regarding temperatures, expect highs tomorrow to range from the mid 20s northeast to the mid to upper 30s southwest before cooling down through midweek. The coldest day will likely be Tuesday, especially north. Highs on Tuesday will range from the single digits above zero north to the upper teens and lower 20s south. Warmer air starts to enter the west on Wednesday but the NBM still suggests highs in the single digits above zero northeast to the mid to upper 20s southwest. Highs will then potentially be warmer Thursday before cooling down again to end the week and start your weekend. That being said, NBM spread is still quite large from Wednesday on with differences up to 20 degrees within the 25th to 75th percentile ranges. Wednesday and Thursday mornings will likely see the coldest lows with some sites potentially approaching 10 below zero across the north but spreads are also quite large for these values as well. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 559 PM CST Sat Dec 14 2024 Conditions west of the Missouri river are forecast to stay VFR with some MVFR CIGs sneaking into KDIK later tonight. Conditions east of the Missouri River will remain under low stratus with MVFR CIGs lowering to IFR later tonight. There is a chance for freezing fog to develop in the James River Valley into south central North Dakota and will continue to monitor conditions. Snow is forecast to move into the area tomorrow morning with the potential for freezing rain ahead of the snow at KXWA. KXWA is on the edge of where the forecast models having freezing rain or not. Therefore, amendment will be made if conditions improve or worsen as precipitation moves into the region. IFR conditions are likely tomorrow as snow moves across the state. && .BIS WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 PM CST /5 PM MST/ Sunday for NDZ001-009-017-018-031>033-040-041-043-044. && $$ UPDATE...Johnson DISCUSSION...ZH AVIATION...Johnson
Area Forecast Discussion
National Weather Service Goodland KS
900 PM MST Sat Dec 14 2024 .KEY MESSAGES... - Patchy freezing fog possible late tonight and early Sunday morning from Norton County in northwest Kansas to Red Willow County in southwest Nebraska. - Elevated to near critical fire weather conditions possible across Yuma county Sunday afternoon. && .UPDATE... Issued at 647 PM MST Sat Dec 14 2024 Update to the going forecast to back off on the potential for fog in extreme E/NE portions of the CWA(eastern portions of Graham/Norton counties in Kansas, eastern Red Willow county in Nebraska). There continues to be a large T/Td spread in this area based on current observations. Guidance continues to show the potential for fog to develop east of the cwa, but the push westward continues to be limited to where the current front meanders through sunrise Sunday morning. Went ahead and took a blend of the latest HRRR, RAP and NamNest for the 06z-15z Sunday timeframe, and fog barely pushes west w/ only patchy fog potential along the county borders. Increased cloud cover from the west currently is keeping temps from dropping from radiational cooling effects, aided also by a light southerly wind. Will continue to monitor guidance later this evening an update if T/Td conditions improve. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 1255 PM MST Sat Dec 14 2024 Upper ridge axis is moving across the area today allowing temperatures to warm into the 50s. However, colder air is lurking just to the east of the area on the other side of a stationary front. Main concern tonight is whether the low clouds and freezing fog will return to those far eastern areas. Models suggest that it will be very close, with reduced visibilities along the Norton/Phillips line and possibly into eastern Red Willow County along the Republican River Valley. The rest of the area will see mostly clear skies and light winds. Lows will be in the 20s. Any fog will quickly retreat east Sunday morning. Shortwave trough moving through in the afternoon will result in an increase in mid/high clouds but no precipitation. In the afternoon will see some marginally breezy northwest winds as winds attempt to mix down behind the trough axis, but only seeing gusts in the 20-25kt range for a few hours in northwest half of the area. Relative humidity does drop to around 20% in the same area, but given the marginal gusts and short duration not expecting to meet critical fire weather criteria. High temperatures will be similar to today in the upper 50s to lower 60s, then cooling into the 20s Sunday night. Zonal flow aloft returns for Monday afternoon with surface high pressure centered over the area. Temperatures will be slightly cooler with highs in the upper 40s to lower 50s and lows in the 20s. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Issued at 120 PM MST Sat Dec 14 2024 Long range guidance continues to suggest that a less- progressive /blocked/ synoptic pattern will evolve over North America late next week as a pronounced upper level ridge amplifies over the western CONUS and deep troughing /cyclonic flow aloft/ envelopes the eastern CONUS.. a pattern often associated with Arctic outbreaks in the eastern US. In such a setup, the High Plains would be situated at an `inflection point` between the pronounced ridge (to the west) and pronounced trough (to the east) -- a region characterized by NW flow aloft and profound synoptic subsidence -- a region that`s typically on the far western fringe of, or altogether removed from, intruding Arctic airmasses. Recent (12Z 12/14) operational runs of the GFS and ECMWF indicate that, by Fri-Sat, the amplifying western CONUS ridge may be situated over the Intermountain West and Rockies -- i.e. in closer proximity to the High Plains (compared to 12Z 12/13 guidance). If this is the case, the Tri- State area would be further removed/insulated from intruding Arctic airmasses. With the above in mind, expect dry conditions and near-average temperatures. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 900 PM MST Sat Dec 14 2024 For KGLD, VFR conditions expected through the forecast period with a mix of SCT-BKN high clouds. Winds, south-southwest around 10kts through 14z Sunday, then west-northwest around 10kts. Gusts to 20kts possible from 17z-21z. For KMCK, mainly VFR conditions forecasted. MVFR fog possible from 06z-10z. Winds light/variable through 18z Sunday, then west-northwest 10-15kts. Gusts to 25kts possible from 03z Monday onward. LLWS 03z-06z Monday 310@50kts. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ UPDATE...JN SHORT TERM...024 LONG TERM...Vincent AVIATION...JN
Area Forecast Discussion
National Weather Service Green Bay WI
956 PM CST Sat Dec 14 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - Hazardous travel due to a light mix of freezing rain and snow is expected this evening into Sunday morning for areas from central to northeast WI including the Fox Valley. Winter Weather Advisories will be in effect this evening into Sunday morning. - Periods of precipitation are possible early next week, but impacts look minimal as temperatures support mainly rain aside from far northern Wisconsin. && .DISCUSSION... Issued at 222 PM CST Sat Dec 14 2024 Short Term...Tonight and Sunday Warm advection in advance of a low pressure system moving into NW Missouri has produced rounds of light snow/freezing rain across portions of southern and southwest WI this afternoon. As the low continues to lift east northeast toward central IL these areas of mixed precipitation will lift northward into central and east- central WI early this evening. RAP soundings suggest snow mixed with freezing rain or sleet will be the primary p-types as precip initially lifts into the region. Forecast soundings then show a compressing saturated layer late this evening and overnight which along with temperatures slightly increasing overnight will lead to a transition to mainly rain/freezing rain depending on surface temperatures. Expect this transition to occur around midnight in the Fox Valley and lakeshore areas, while it may take a few more hours across central and northern WI. The main impacts from this system will be potentially slippery roads this evening into Sunday morning across central and northeast WI including areas in the Fox Valley. With this slight southward shift in areas expecting accumulating ice did extend the Winter Weather Advisory to include counties in the Fox Valley and along the lakeshore, except Door Co. Ice accumulation amounts will range from a light glaze up to 0.1" across most of the region, except along the immediate lakeshore and across far north- central WI. Snow amounts will be on the light slide with most areas seeing less than 1". The area will start to dry out Sunday morning from west to east as the pushes off to the east. However, forecast soundings do show the potential for drizzle/freezing drizzle to linger into the early afternoon, mainly across northeast and east-central WI. Behind the precipitation patchy areas of fog may also develop Sunday which may slow down any Sunday morning travel across the region. Long Term...Sunday Night Through Saturday Main highlights from this forecast period revolve around various chances for light precipitation and temperatures gradually decreasing to below normal by late next work week. Precipitation...A surface low pressure system is progged to track across southwestern Ontario Sunday night through Monday night. The system`s cold front will sweep across the forecast area and bring the next chance for precip. The main forecast challenge will be determining p-type with this system. Forecast soundings indicate the warmer surface air temperatures in east-central WI will result in rain, while colder surface air temperatures in north-central WI will result in snow. However, mid-level moisture appears to decrease at times throughout the timeframe, which may result in drizzle or freezing drizzle. Regardless of the p-type, QPF appears light, but if freezing drizzle occurs, some locations could see travel impacts. Models indicate the next chance for precip may be sometime Tuesday night into Wednesday as a shortwave moves across the region. Again, moisture appears limited, but temperatures would be cold enough for snow to occur. Northwesterly winds follow, resulting in a chance of lake-effect snow in far north-central WI through Thursday. Signs then point to a clipper system that may impact the region to end the work week, but there is too much uncertainty to determine any finer details at this time. Temperatures...A warmer air mass will remain in place for Monday, but will slowly depart over the course of Tuesday and Wednesday from the cold front and shortwave passing overhead. Monday`s highs to range from the middle 30s to low 40s, dropping to the low 20s to low 30s on Wednesday. Much colder air arrives Wednesday night, with highs topping out in the 20s for Thursday and Friday. && .AVIATION...for 06Z TAF Issuance Issued at 956 PM CST Sat Dec 14 2024 Flight conditions will deteriorate overnight with lowering ceilings and visibilities, and a light mix of snow, sleet and freezing rain that will change to rain near the bay and Lake Michigan. IFR conditions are expected across the entire area shortly after midnight. The precipitation will diminish Sunday, but IFR conditions will continue through the day. There could be some improvement late in the day east of a MNM to OSH line. && .GRB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 9 AM CST Sunday for WIZ013-018>021- 073-074. Winter Weather Advisory until 6 AM CST Sunday for WIZ030-031- 035>038-045. Winter Weather Advisory until midnight CST tonight for WIZ039- 040-048>050. && $$ DISCUSSION.....GK/Kruk AVIATION.......RDM
Area Forecast Discussion
National Weather Service North Platte NE
523 PM CST Sat Dec 14 2024 .KEY MESSAGES... - Fog possible tonight in some far eastern areas. - Light precipitation possible in northwestern portions of the forecast area Sunday afternoon/evening and again on Tuesday. - Temperatures will generally be above normal next week with dry conditions expected beyond Tuesday night. && .SYNOPSIS... Issued at 327 PM CST Sat Dec 14 2024 H5 analysis this morning had a closed low over central Kansas with a trough extending south of this feature into northern Texas. East of the trough, ridging extended from the middle Ohio Valley north into the LP of Michigan. West of the low, ridging extended from the Four Corners north into central Montana. Further west, closed low pressure was present off the coast of Washington State, with a trough extending south to approximately 30 miles west of San Francisco CA. At the base of this trough, current WV imagery indicates a decent shortwave. At the surface, low pressure was present just east of Kansas City. Low pressure was also present over northeastern Wyoming. A frontal boundary extended to the southeast of the surface low and was oriented from just west of Valentine Nebraska, to just west of Lexington Nebraska. West of this feature, winds were from the west, while east of this feature winds were light and variable. A shield of clouds extended from around O`Neill south to west of Grand Island. At 2 PM CT, temperatures varied widely across the forecast area and ranged from 28 degrees at O`Neill, to 57 degrees at Ogallala. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 327 PM CST Sat Dec 14 2024 Low amplitude ridging aloft will traverse the forecast area tonight. Winds will remain southerly with an easterly component in the eastern third of the forecast area, while south- southwesterly and southwesterly winds will prevail in the central and western forecast area. With clouds persisting into this afternoon over far eastern portions of the forecast area, and persistent light south-southeasterly winds expected tonight, there will be a decent potential for fog formation in our far eastern four counties. BL RH in the NAM12 soln this morning is near 100 percent, and the 12z HRRR soln this morning has visibilities below 1 mile generally east of a Taylor to Butte line. This is also supported by the latest SREF ensemble visibility product which has a better than 50% chance for visibilities below 1 mile overnight. That being said, will insert a mention of fog across the far northeast tonight. Elsewhere, clear skies and fairly light winds will lead to lower to middle 20s. On Sunday, an upper level shortwave will track into northern North Dakota. Surface low pressure will develop over northern South Dakota, leading to westerly winds across most of the forecast area. Across far eastern areas, winds will be much slower to shift to the west. This will allow low clouds and fog to persist into the early, possibly mid afternoon hours, and will lead to cooler temps Sunday afternoon. Highs Sunday will range from the lower 40s in eastern Boyd and Holt county, to near 60 in far SW Nebraska. The shortwave trough mentioned above, will migrate into southern Ontario and far northern Minnesota Sunday night, forcing a cold front through the forecast area. Northwesterly winds will develop and may be gusty, leading to an increased threat for light precipitation over the Pine Ridge and far NW Nebraska. The inherited forecast had a mention of light precipitation over northern Sheridan into northwestern Cherry county. QPF with this will be on the order of a trace to a couple of hundredths of an inch. That being said, if snow were to develop Sunday evening, impacts should be fairly minimal in these areas given the low QPF. Look for winds to increase from the northwest overnight with the frontal passage, and will lead to elevated min temps Sunday night with readings in the mid to upper 20s. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 327 PM CST Sat Dec 14 2024 Monday will be breezy across the area with windy conditions expected over northern Nebraska. This is behind an exiting cold front and east of high pressure over Colorado. Winds were increased from the NBM more toward the 75th to 90th percentile to account for unidirectional winds noted from H85 down to the surface. Wind speeds approach 45 KTS across nrn Nebraska at the H85 level with this morning`s NAM12 run. Will need to evaluate winds further and may need to trend speeds up Monday afternoon with subsequent forecasts. Winds will shift around to the southwest on Tuesday ahead of another cold front. This front will enter far NW Nebraska late Tuesday afternoon, traversing the FA Tuesday night. In advance of the front, temps will reach into the lower 40s (north) to the lower to middle 50s in SW Nebraska. Beyond Tuesday, temperatures will fluctuate especially in northeastern portions of the forecast area as a couple of arctic fronts are forced into the upper midwest Wednesday and Friday. This will lead to a wide range in temps for Wednesday and Friday with readings ranging from the middle 30s in the northeast to lower 50s in far SW Nebraska. Between the frontal passages, readings Thursday will range from the middle 40s to middle 50s. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 525 PM CST Sat Dec 14 2024 Low stratus with IFR/LIFR CIGs will persist for terminals near and east of HWY 183 tonight, with some westward stratus expansion possible. Additionally, fog formation is expected near and just west of this stratus deck, with MVFR/IFR visibilities. A gradual improvement back to VFR is then expected for all area terminals tomorrow afternoon. Winds remain southerly tonight at around 5 to 10kts. Winds then become west late tomorrow morning, strengthening with gusts of 20 to 30kts tomorrow afternoon. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...Brown
Area Forecast Discussion
National Weather Service Raleigh NC
820 PM EST Sat Dec 14 2024 .SYNOPSIS... Strong high pressure will extend into the region from the northeast through Sunday, as a weakening upper level disturbance passes by to our northwest. The surface high will weaken and push offshore Monday and Tuesday, as a warm front lifts northward into the area and stalls. A strong low pressure system will move through the area Wednesday through early Thursday. && .NEAR TERM /THROUGH TONIGHT/... As of 820 PM Saturday... A 1048+ mb high still exists across southern Quebec and into portions of New England. Ridging from the anomalously strong high continues to extend into the Carolinas. While high-level clouds and moisture continues to slowly increase, the 00z Greensboro sounding showed continued dry air beneath the cirrus shield tied to the shortwave trough across the Mid MS valley. This shortwave is forecast to reach northern IN by 12z Sun, with the bulk of its energy residing to our NW over western VA and the lower OH valley. Isentropic ascent is forecast to increase atop the surface ridging regime, but likely not peak until mid Sun onward when a better batch of forcing moves overhead across the northern and northwest Piedmont. With that, it would appear our best shot of any precipitation could come in the form of light rain or drizzle across the Triad and far northern Piedmont. This would be associated with low-level 925-850 mb southeasterly upslope building around the surface high. Recent obs have show the makings of this, with 2500- 3000 ft ceilings over the Triangle and northern Coastal Plain. This area of low clouds should penetrate westward across the western Piedmont into the overnight hours. The recent runs of the RAP and HRRR also suggest that the developing saturated layer could at times be more than 4 kft deep from about 800 to 5000 ft over the Triad early Sun morning. The NAM and GFS are not as moist in these lowest layers. Nevertheless, we added drizzle to the forecast in the Triad given limited forcing aloft. As for temperatures, lows should hover in the low to mid 30s in our NW zones. And guidance suggests that the lowest saturated layers will be above freezing, so not expecting any ptype concerns. The rest of the forecast area should remain dry with lows in the upper 30s to lower 40s. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... As of 154 PM Saturday... * Waves of light rain will allow for CAD surface pattern to develop and result in up to 20 degree temperature gradient across central NC. A closed low over IL/IN Sun morning will continue to negatively tilt as it shifts into the northern Mid-Atlantic by early Mon morning. This track will direct a plume of PWAT around 1" (100-150% normal for mid-Dec) from the MS Valley into central NC Sun afternoon through Sun night. Preceding this band of deep layer moisture, strong low-level moist isentropic ascent along the 280 to 290K surface will prompt the development of low overcast and CAD regime, maximized over the NC Foothills into the NW Piedmont. Mostly drizzle and passing waves of light rain within this regime will be most likely through the morning hours as surges in low-mid level omega ripple across the area, but lack of deep layer moisture and a shallow saturated layer may prevent much accumulation through the early afternoon. The better chances for light rain accumulation may be as the deep layer moisture arrives late Sun morning, but H5 height falls, on the order of 20-40m, will be lifting off to the northeast into VA/MD and weak shortwave ridging moving overhead. The 12z HRRR is probably the most aggressive among the 12z guidance and depicts an earlier advection of the plume of deep layer moisture that would then overlap the waves of low-mid level omega to produce light to moderate rain, with the most accumulation occurring after 18z. The storm total rainfall from the 12z HRRR through 12z Mon is above the 90th percentile within the 12z HREF guidance. The most likely totals range from as much as trace amounts in the Coastal Plain to less than a quarter inch in the NW Piedmont. Although the surface wet-bulb zero will be draped over the NW Piedmont of central NC initially early Sun morning, marginal preceding dew points, rising temps from downward IR as low-overcast cloud cover develops, lack of a deeper saturated layer at onset, and freezing rain being a self-limiting process, accumulating freezing rain is not expected at this time in our forecast area. Also, while wet-bulb zero would be at or below 32F, precipitation rates will likely not be high enough to lower surface temps to the wet-bulb. High temperatures will be tricky and depend on the exact location the CAD regime develops over the Piedmont. Hi-res guidance suggests temps as high as low-mid 60s on the periphery of the CAD regime. Based on local guidance, will continue to favor the lower end of guidance which results in highs in the upper 30s to low 40s in NW Piedmont to upper 50s and low 60s in the Sandhills and southern Coastal Plain. && .LONG TERM /MONDAY THROUGH SATURDAY/... As of 400 PM Saturday... The CAD will start to erode on Monday with the surface high gradually weakening and moving farther east into the Atlantic. Meanwhile shortwave ridging will briefly move in aloft. This will result in a decreasing trend in clouds and rain chances, with just slight chance POPs early in the day across the far north. High temperatures are a little uncertain as they will depend on how quickly the CAD erodes, but for now lean toward the cooler guidance with highs ranging from the 50s in the far northern Piedmont to mid- to-upper-60s in the south and east. Clouds will increase again on Monday night in advance of a cold front associated with a shortwave and occluded surface low moving NE across the Great Lakes and southern Canada. Thus low temperatures will be quite mild, mid-40s to lower-50s. Rain chances creep back in Monday night into Tuesday, but ensemble output with this is very light if any, as the shortwave will be displaced so far to our north and guidance has trended toward the front struggling to make it past the mountains. So POPs are only slight. Tuesday will continue the warming trend with well-above-normal highs in the mid-60s to lower- 70s. Another pair of shortwaves will approach our region from the west Tuesday night into Wednesday night. These waves may provide better forcing for precipitation across our area as upstream ridging over the Western US allows them to dive farther south, but how much will depend on the degree of phasing that occurs. Both the GFS and ECMWF depict an associated cold front and surface low riding along the front, but the low is farther to our north and west in the 12z guidance. Both models depict the northern and southern stream waves staying separate and have trended toward a more progressive system. So latest ensemble output is pretty low, only around a quarter inch or less, and the best chance of precipitation appears to be on Wednesday and Wednesday night, drying out on Thursday. Still keep some slight to low chance POPs on Thursday as a minority of ensemble members are slower/wetter. Temperatures have trended warmer on Wednesday and Thursday with forecast highs in the mid-60s to lower- 70s and mid-50s to 60 respectively, while lows Tuesday and Wednesday nights are in the mid-40s to lower-50s. Drier and cooler weather will prevail from Thursday night into Saturday as high pressure builds in. Forecast lows Thursday and Friday nights are in the mid-20s to lower-30s, with highs mainly in the 40s (below normal). && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 715 PM Saturday... Current conditions are VFR across W and S sections of central NC, however an area of cigs based at 2500-3500 ft AGL (around the VFR- MVFR threshold) persists in our NE including RDU and RWI. This cloud deck should break up and lift to sct VFR by 04z, but confidence in this is not high, and patchy MVFR-level clouds, with occasional cigs, may linger over the N and E through much of tonight, including at FAY/RWI/RDU. The higher confidence in development of sub-VFR conditions is at INT/GSO later tonight, after 06z, when cigs are expected to drop to MVFR, followed by IFR cigs after 09z, first at INT. Patchy light rain is also possible, mainly at INT, after 09z, with only a small chance for MVFR vsbys. IFR conditions are likely to hold at INT/GSO through Sun, while further E, MVFR cigs are expected to spread into RDU after 20z. Surface winds will be from the NE (ranging from NNE to ENE) at 6-12 kts with infrequent gusts to around 15 kt. Looking beyond 00z Mon, sub-VFR conditions are very likely to hold through Mon morning at INT/GSO/RDU, mainly IFR, while RWI/FAY have a good chance of going down to MVFR late Sun night into Mon morning. Sub-VFR cigs are again possible Mon evening/night and Tue evening/night. The chance for more widespread sub-VFR cigs and vsbys with better rain chances will arrive Wed, lasting into Thu morning, Low level wind shear is possible mainly in the NW Mon night. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Kren SHORT TERM...Swiggett LONG TERM...Danco AVIATION...Hartfield
Area Forecast Discussion
National Weather Service Tulsa OK
752 PM CST Sat Dec 14 2024 ...New UPDATE... .KEY MESSAGES... Updated at 752 PM CST Sat Dec 14 2024 - Dense fog potential tonight into Sunday morning near/along the Red and lower Arkansas River Valleys. Some potential for fog near the Kansas border as well. - High chance of showers and low to medium chance for thunderstorms Sunday night into Monday, with limited heavy rain potential and limited severe weather potential. - Temperatures above normal until a stronger cold front Wednesday, then temperatures near normal late next week. && .UPDATE... Issued at 752 PM CST Sat Dec 14 2024 Strong shortwave trough with embedded H5 low is lifting northeast toward the mid-Mississippi Valley this evening. At the surface, low pressure was centered over NE MO, with a Pacific front extending south over the MO Ozarks and then southwest across western AR, southeast OK and down into northeast and central TX. The southern end of this front has already stalled as the upper support lifts away from the region. As this boundary lifts back north toward Sunday morning, an area of dense fog is expected to develop near/along the Red River Valley. Farther north along the lower AR River Valley of west-central AR, models indicate potential for dense fog as this area saw almost an inch of rain over the past 24 hours and higher surface dewpoints are expected to persist. A dense fog advisory has been issued for west-central AR and Choctaw county in far SE OK from midnight to 9 AM Sunday. The HRRR has also been indicating that fog will develop near and north of the Kansas border as well. Not as confident here regarding coverage of dense fog, but surface temps will be near freezing so there`s a low chance for patchy freezing fog. Will pass these concerns on to the next shift. Lacy && .SHORT TERM... (Through tonight ) Issued at 312 PM CST Sat Dec 14 2024 Area of low pressure as of mid afternoon had moved into Western Missouri with the mid/upper level trof axis having cleared Northwest Arkansas. This had allowed for the back edge of the rain showers to exit into Central Arkansas. Meanwhile...the associated surface frontal boundary was continuing to move eastward over far Eastern Oklahoma and into Western Arkansas this afternoon. Behind the boundary...clearing skies and breezy westerly winds were common across Eastern Oklahoma. Overnight tonight...the western portion of the boundary is expected to hold up over Northeast Texas to just south of the Red River. Behind the boundary...surface high pressure will move through the region with calm to light southerly winds returning by sunrise Sunday. These conditions along with mostly clear to passing high clouds will aid in low temps tonight falling into the 30s for most locations. Temps near the Red River and close to the boundary could remain in the lower 40s. With expected dewpoint depressions of 0-3 deg from this mornings rains...patchy to areas of fog development are forecast tonight over Southeast Oklahoma...Northwest Arkansas and near the Kansas border. Conditions should improve improve during the morning hours as southerly winds begin to increase again across the CWA. && .LONG TERM... (Tomorrow through Saturday) Issued at 312 PM CST Sat Dec 14 2024 Breezy southerly winds quickly return to the region Sunday...which intern will help to lift low level moisture and the frontal boundary back northward through the CWA Sunday afternoon. These conditions will help afternoon temperatures to warm back above the seasonal average with highs in the 60s forecast. As the moisture lifts back into the CWA...slight chances for rain showers return to mainly Southeast Oklahoma Sunday afternoon. Marginal elevated instability could potentially create isolated thunder as well. Rain and thunderstorm chances increase Sunday night into Monday morning in advance of another cold front associated with an area of low pressure moving eastward through the Northern Plains. Increasing low level jet...elevated instability and deep layer shear of 40-50KT could create a few strong to marginally severe storms Sunday night. A limiting factor will be weak mid level lapse rates. The cold front moves southeast through the CWA during the day Monday and should get just south of the Red River before stalling once again. By Monday evening...a slight chance of rain remains near the Red River...depending on just how far south the boundary can get before slowing its progression southeast. Conditions Tuesday look to be somewhat similar to Sunday with the frontal boundary and low level moisture lifting back northward through the region as southerly flow quickly returns. Again will carry slight to chance PoPs for rain showers lifting northward Tuesday. Also with these conditions...afternoon temps in the 60s are forecast for much of the CWA. The trend with the back and forth frontal boundary movement is progged to continue Tuesday night into Wednesday with another cold front dropping southeast through the region as a mid/upper level trof axis moves through the Plains. Marginal elevated instability will allow for chance thunderstorm potentials ahead of the front Tuesday night and Wednesday morning. Precipitation is currently forecast to finally taper off and exit the CWA by Wednesday evening. In the wake of the departing mid week cold front...surface high pressure originating from Western Canada is forecast to drop southeast into the Central U.S. Wednesday night and Thursday. In response...colder conditions with high temps in the 40s are forecast late week. Another shortwave looks to quickly move through the Plains late week with one more frontal boundary across the region. This will help to continue the cool/colder conditions into next weekend. At this time the passage of this boundary should remain dry as moisture looks to be quite limited over the region. && .AVIATION... (00Z TAFS) Issued at 525 PM CST Sat Dec 14 2024 VFR conditions prevail across eastern Oklahoma and western Arkansas this evening. Areas of fog could reduce visibility at some of the northeast Oklahoma and western Arkansas sites late tonight into Sunday morning. Ceilings begin to lower area-wide Sunday as moisture increases across the area. && .PRELIMINARY POINT TEMPS/POPS... TUL 36 66 49 61 / 0 0 80 20 FSM 40 65 58 66 / 0 10 90 80 MLC 39 66 57 65 / 0 10 90 70 BVO 29 66 43 59 / 0 0 50 10 FYV 32 65 55 62 / 0 0 90 60 BYV 35 64 55 62 / 0 0 90 60 MKO 36 66 54 63 / 0 10 90 50 MIO 34 65 46 59 / 0 0 70 20 F10 38 67 54 62 / 0 10 90 40 HHW 42 66 61 67 / 0 40 80 90 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...Dense Fog Advisory from 11 PM this evening to 9 AM CST Sunday for OKZ053. AR...Dense Fog Advisory from 11 PM this evening to 9 AM CST Sunday for ARZ019-020-029. && $$ UPDATE...30 SHORT TERM...20 LONG TERM....20 AVIATION...10