Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/01/23

Area Forecast Discussion
National Weather Service Dodge City KS
414 PM CST Sat Dec 31 2022 ...updated aviation... .SHORT TERM...(This evening through Sunday night) Issued at 1202 PM CST Sat Dec 31 2022 18Z obs are showing west to northwest flow in the mid levels and the moisture in the mid levels is currently at a lull which is leading to the sunny skies across western Kansas. Upstream a large area of Pacific moisture is currently streaming from Colorado back to the coast of California. This is ahead of an approaching shortwave which will affect Sunday night through Monday`s weather. At the surface a weak lee side low is located in the Oklahoma panhandle with a surface trough/wind shift line extending into central Kansas. Tonight should be fairly quiet as the surface low moves into western Kansas and the winds should remain light. There will be a few passing high clouds during the night and some approaching mid level clouds from the southwest ahead of the next shortwave towards morning. Overall efficient radiational cooling as lows will fall into the 20s and 30s. Sunday with the approaching upper level trough heading towards the four corners we should see an increase of clouds during the morning and be mostly cloudy for the whole area towards mid to late afternoon. Winds should continue light as the surface low/trough will remain in western Kansas. Highs will be in the mid 50s. Sunday night we should start to see the first bands of precipitation develop along the front range of the Rockies with the approaching storm system. Ahead of the system a warm front will lift towards the I-70 corridor overnight with the HRRR hinting at the potential of some advection fog and/or drizzle towards morning. I kept this out of the forecast as of now but it is something to monitor over the next few forecast cycles. Light rain could begin to develop towards the Colorado border by sunrise however it looks like most of the area should be dry as lows fall into the mid to upper 30s. .LONG TERM...(Monday through Saturday) Issued at 155 PM CST Sat Dec 31 2022 Main story of the long term is the upcoming storm system which will mostly affect northeastern Colorado, northwestern Kansas, and Nebraska with a large winter storm and the trend of being more in the dry slot for much of our area keeping the chances of rain and snow lower and the amounts lower as well. Latest deterministic models have continued the northern track of the 500 mb low through northeast Colorado and most of the better forcing in northwest Kansas. Along with that a pocket of drier air comes in the 700 mb- 850 mb level during the day on Monday. The exception is the latest deterministic Euro which has moved a little further south from the previous run and has introduced rainfall amounts of 0.10-0.25 inch across the area. After collaboration with neighboring offices and WPC I decided to keep the drier solution which would give much of the area little to no QPF with the exception of our northwest and I-70 corridor counties. The ensemble Euro and GFS also continue their respective trends of almost no QPF for the GFS and a few tenths from the Euro. Overall it looks like mainly a wind event for the area as the surface low deepens in eastern Colorado which will produce gusty southwest winds and highs in the mid 50s. Monday night into Tuesday the storm system should exit into northeast Nebraska and on the backside a cold front will usher in colder air and breezy northwest winds across much of central and western Kansas. Any lingering precipitation could quickly switch over to snow mainly along the I-70 corridor with little to no accumulations. Tuesday should remain breezy and cooler with highs in the 40s. The middle of the week we should stay on the cool side of the jet stream and highs will stay in the 40s. By Friday an upper level ridge will usher in warmer temperatures and will be ahead of another large trough in the southwest which could be a potential weather maker for the region for next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 444 PM CST Sat Dec 31 2022 VFR is expected through TAF pd. Winds should remain light and variable tonight and into the AM. A weak backdoor front works in during the day tomorrow with winds becoming NE 5-15 kt in its wake. Any weather impacts with an eventual passing weather system looks to remain outside of this TAF pd. && .PRELIMINARY POINT TEMPS/POPS... DDC 29 54 37 56 / 0 0 10 30 GCK 28 53 35 54 / 0 0 10 30 EHA 36 57 38 56 / 0 0 20 20 LBL 31 55 38 57 / 0 0 10 20 HYS 26 52 34 52 / 0 0 10 40 P28 33 55 40 57 / 0 0 0 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Tatro LONG TERM...Tatro AVIATION...Sugden
Area Forecast Discussion
National Weather Service Grand Forks ND
725 PM CST Sat Dec 31 2022 .UPDATE... Issued at 725 PM CST Sat Dec 31 2022 Areas of fog continue to be reported, with transient pockets of dense fog (1/2-1/4 mile). Conditions are highly variable with reports of riming/heavy frost in the dense freezing fog and very light mist mainly associated with these dense pockets. Actual freezing drizzle in the east may have transitions out of the area, so the main impacts are going to be where this freezing fog develops and tracks and current conditions with the previous advisory are highly variable. High resolution guidance indicates that this will persist and eventually new dense freezing fog may overspread our entire forecast area through the late evening/overnight. The strongest signal for improvement by RAP sounding is when winds finally shift to the west and increase Sunday, but that leave a very moist/stagnant air mass in place overnight matching the idea of expanding impacts. Considering the expected trends I went ahead and expanded the dense fog advisory for our entire area and ran it through 9am Sunday. I`m also using extra caution considering holiday travel tonight. && .SHORT TERM...(This evening through Sunday night) Issued at 220 PM CST Sat Dec 31 2022 Key Messages 1. Dense fog will continue at least through midnight. Fog may persist after as confidence is quite low in duration of the fog. 2. Freezing drizzle is possible tonight, especially in northwest Minnesota near the Red Lakes. Be prepared for slick conditions. DISCUSSION The surface pattern is dominated by a weak surface low over eastern South Dakota, contributing to southerly flow and moisture advection over the Northern Plains. This has allowed for some weak upslope flow in eastern North Dakota which has caused areas of fog. Fog is the most dense along where moisture advection exists ahead of the 850mb trough. It is unclear how long this dense fog may exist, but it does appear like it will at least continue through midnight. With the surface inversion, fog will unlikely get better, so the Dense Fog Advisory has been expanded northeastward and extended through midnight. Weak warm air advection ahead of the 850 trough will allow for some freezing drizzle potential in northwest to north central Minnesota. Soundings indicate a pretty solid moist 1km deep layer associated within this region of WAA. This potential will exist through 09z/3 AM one warm air advection is able to exit the area. For tomorrow, primarily zonal flow will keep us mild and quiet for the most part. Stratus may continue to linger around, but confidence is low in that department as this stratus has hung around for several days. Impacts should remain low for New Years Day. .LONG TERM...(Monday through Saturday) Issued at 220 PM CST Sat Dec 31 2022 Key Messages - *Normal to Above Normal highs and lows for the first part of January *Light snowfall along the ND/SD line into west central Minnesota Monday into Tuesday Ensembles/cluster analysis continues to place more weight on a southern track or soln with the upcoming system Monday into Tuesday. As a result little snow expected from the system along and north of the I94 and Hwy 10 corridor. Highest amounts expected in this forecast area will be for Grant county. The probability of an inch or more is 50% or higher along and south of a line from Havana to Wahpeton to Park Rapids with just a 20% for 4 inches along a line Hankinson to Fergus Falls to Nimrod with higher values to the south as a 40% chance exists in southern Grant at Herman and Hoffman. In the wake of the system some patchy blowing snow will be possible in the southern valley as sustained north to northwesterly winds approach 20mph Tuesday. With the quasi-zonal flow the rest of the week into next weekend temperatures will not vary much this week with highs in the teens and low 20s most days. The exception will be Wednesday in the wake of the system with highs in the single digits and teens. Lows this week will be in the single digits above and below zero. Normals for the first week of January are highs in the mid teens and lows around zero. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 544 PM CST Sat Dec 31 2022 Fog and stratus are likely to continue through the TAF period, with dense fog this evening responsible for lowest visibilities to 1/4 mile or less. How long dense fog lasts is hard to say as there are upstream indications of improvement in the west as winds shift to the southwest, however guidance supports decreasing winds locally and continued pooling of low level moisture which may limit improvement. Eventually winds do shift more to the west Sunday and increase and that should be at least enough for prevailing MVFR rather than IFR conditions. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Dense Fog Advisory until 9 AM CST Sunday for NDZ006>008-014>016- 024-026>030-038-039-049-052>054. MN...Dense Fog Advisory until 9 AM CST Sunday for MNZ001>009-013>017- 022>024-027>032-040. && $$ UPDATE...DJR SHORT TERM...Perroux LONG TERM...JK AVIATION...DJR
Area Forecast Discussion
National Weather Service Wichita KS
525 PM CST Sat Dec 31 2022 .SHORT TERM...(This evening through Monday night) Issued at 300 PM CST Sat Dec 31 2022 FORECAST HIGHLIGHTS THE NEXT 7 DAYS: * Fog potential southeast Kansas late tonight into Sunday morning. * Above normal temperatures through Monday. * Precipitation chances Monday-Monday night. * Near to below normal temperatures Tuesday-Thursday, with a warming trend late week and next weekend. With weak moist advection into a developing warm frontal zone, thinking fog potential will increase late tonight into Sunday morning over southeast Kansas, mainly southeast of the KS Turnpike. Bufkit RAP soundings support patchy to areas of dense fog, so later shifts may need to monitor for a possible dense fog advisory. Fortunately, temperatures should remain above freezing, so patchy slick spots on roads and bridge decks are unlikely. Main forecast highlight is the anomalously deep western CONUS upper trough ejecting onto Mid-America by Monday. Deterministic and ensemble consensus continues to favor the highest precipitation chances associated with this system over eastern Kansas, where deep moisture transport and large scale ascent coincide. Have sided with this model consensus for the official forecast. However, the deterministic ECMWF solution continues to be the deeper and more negatively tilted outlier with regard to the upper system, with also a further south warm frontal position, which would favor a more widespread footprint of precipitation across the region. If the model consensus starts to trend closer to the ECMWF solution, later shifts will need to increase rain chances and amounts further west across the forecast area. Warm thermal profiles support a precipitation type of mostly rain, with a few embedded thunderstorms over southeast KS, amidst anomalous moisture and associated marginal instability. Severe weather isn`t expected, although given the strong wind fields and marginal instability, cannot rule out small hail and gusty winds with the strongest activity. As the system pulls away and colder air filters south, could see a period of a light rain/snow mix over central Kansas Monday night into early Tuesday, especially if the stronger/more wrapped up ECMWF solution verifies. The heavier wintry precipitation should remain well north of the region, so am not expecting impacts from wintry weather across central KS. .LONG TERM...(Tuesday through Saturday) Issued at 300 PM CST Sat Dec 31 2022 Chilly Canadian high pressure building in from the north should support a return to near to below normal temperatures Tuesday- Thursday, with lows in the teens-20s, and highs in the 30s-40s. By late next week and next weekend, model consensus supports temperatures warming back to mostly above normal readings in the 40s- 50s. In wake of the early week system, meaningful precipitation chances look low through next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 519 PM CST Sat Dec 31 2022 Some cirrus clouds will continue to spread eastward across the region through the period. We`re still expecting to see some increasing potential for fog and stratus across southeast KS during the predawn hours on Sun likely lowering flight categories at KCNU while lingering into the morning hours on Sunday before mixing out. Light easterly winds are expected to develop as low pressure organizes over the Southern Plains during the day on Sunday. && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 34 54 43 57 / 0 0 0 50 Hutchinson 32 54 39 54 / 0 0 10 50 Newton 34 54 41 55 / 0 0 0 50 ElDorado 37 54 44 58 / 0 0 0 50 Winfield-KWLD 38 57 47 61 / 0 0 0 50 Russell 27 51 35 52 / 0 0 10 50 Great Bend 29 53 37 52 / 0 0 10 40 Salina 30 52 38 52 / 0 0 10 50 McPherson 31 53 39 53 / 0 0 10 50 Coffeyville 43 62 52 65 / 0 0 0 80 Chanute 40 59 49 62 / 0 0 0 70 Iola 39 58 48 62 / 0 0 0 70 Parsons-KPPF 42 60 50 63 / 0 0 0 70 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...ADK LONG TERM...ADK AVIATION...MWM
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
824 PM CST Sat Dec 31 2022 .UPDATE... Issued at 824 PM CST Sat Dec 31 2022 No significant changes to going forecast this evening. Primary concern continues to be a period of mixed rain/snow/freezing rain this evening from the I-39 corridor east-northeast through the northern Chicago metro suburbs before low level temps and wet bulbs warm solidly above freezing. Did raise pops a bit across the north and made some temp/dew point and wet bulb adjustments based on near term obs trends, but otherwise forecast appears to be in good shape. Have seen some spotty light precipitation early this evening mainly along/north of about a Sterling to Waukegan line. Surface temps were generally in the 32-35 degree range in this area per ASOS/AWOS and private sensors, with RAP soundings depicting sub- freezing wet-bulb profiles below cloud base. This will likely support a brief period of mixed rain/snow and perhaps even a few sleet pellets as precipitation continues to increase in coverage over the next couple of hours. Persistent low level warm advection will gradually warm surface temperatures and dew points solidly above freezing by midnight, with gradual low level saturation working to increase wet bulbs and turn precip to all by midnight. Some patchy slick spots are possible mainly on thinner untreated surfaces such as sidewalks and parking lots this evening however. This precipitation is associated with a pair of mid-level short waves traversing the region. The first, currently transiting WI, largely worked to saturate the mid-levels. The second and stronger wave currently crossing the mid-upper Missouri Valley will bring stronger forcing across the region overnight, expanding rain over the forecast area toward/after midnight. The wave will exit the region prior to sunrise allowing rain to exit to the east early Sunday morning. Lingering low clouds and patchy fog will likely linger into the daytime hours however. Updated digital and text forecasts available. Ratzer && .SHORT TERM... Issued at 243 PM CST Sat Dec 31 2022 Through Sunday night... Main forecast highlights through the period include: * Period of Rain across northern IL tonight, with some potential for a wintry mix far north at onset early this evening. * Some fog plausible late tonight into Sunday morning following the period of rain. * Potential for more substantial low clouds and fog developing Sunday night and persisting into Monday. An upper level 120+ kt upper level Pacific jet streak is currently oriented from the northern Rockies east-southeastward into the Mid-Missouri Valley. The exit region of this jet streak is expected to nose eastward across IA and into northern IL into tonight, and will be accompanied by a quickly moving low amplitude mid-level impulse. Ultimately, these features will support a period of precipitation across a decent portion of northern IL tonight. Increasingly lower-level warm air advection and a lead mid-level disturbance over IA is already resulting in an area of precipitation across eastern IA and far northwestern IL. This activity will be fighting a drier low-level airmass as it continues to move eastward into northwestern IL and southern WI late this afternoon and early evening. While this may result in many of the echos on the radar not reaching the ground initially, evaporative cooling of the lower levels is likely to, at least initially, offset the warming of the column from thermal advection. This may thus support a period the precipitation onsetting as a light wintry mix into early this evening before the warm air advection wins out and warms the column enough to support all rain by mid to late this evening. The main potential for a brief 1 to 3 hour wintry mix looks to be across the northern tier counties in IL near the WI state line. A minor coating of accumulation is possible, but this is not likely to lead to major travel disruptions. Areas farther south look to warm enough prior to the onset of precipitation to support all rain by mid to late this evening. It appears the best period of rain will occur around, or a bit after midnight tonight as the main upper level disturbance and exit region of the upper level jet begin to nose into the area. Forecast guidance even suggests that a band of lower-level frontogenesis may even focus a band of some heavier showers within a region of steepening mid-level lapse rates right across northern IL (north of I-80) for a couple hours overnight during the period of strongest large scale forcing. Currently, the timing of this better period of rain across northeastern IL looks to be in the 12 am to 4 am time period tonight. Accordingly, POP and QPF values have been boosted to 60 to 70%, and 0.25 to 0.5", respectively. As the rain ends from west to east overnight, signs point to low clouds and fog development by daybreak Sunday morning. While guidance has not recently had a good track record with fog development, it appears the increasing low-level moisture from the south may make the fog more likely into Sunday morning. For now, I have added patchy fog wording to the forecast, though if trends continue to support this it may need to be hit a bit harder in the forecast. Aside from lingering morning fog and low clouds, Sunday looks to be primarily quiet. Temperatures should be milder, with highs generally in the 40s. Winds are expected to turn northeasterly Sunday night as a warm front sharpens just south of the area in response to developing low pressure over the TX panhandle. This warm front will gradually shift northward across IL into Monday. The main concern for our area Sunday night into Monday will again be tied to low clouds and fog, some of which could be dense. For now, I have added patchy fog wording for areas generally along and south of I-88 Sunday night through Monday morning. KJB && .LONG TERM... Issued at 333 PM CST Sat Dec 31 2022 Monday through Saturday... Monday begins with a warm frontal boundary approaching the area from the south tied to our next big storm system. 30s and lower 40s in the morning will rise into the mid 40s to lower 50s by Monday afternoon. The front is forecast to move through the area Monday afternoon and evening with efficient WAA continuing to take place through the night. This will result in warming conditions overnight with 40s and lower 50s in the evening followed by 50s to around 60 degrees by daybreak on Tuesday. The Euro is a bit slower to bring the front through which would result in slightly, but notably, cooler conditions, especially in the northern CWA. The widespread rain expected with this storm will begin feeding in from the southwest through the latter half of the evening, perhaps preceded by a few scattered pre-frontal showers through the afternoon. PWAT forecasts Monday evening and night continue to exceed one inch area-wide and push 1.5" across the southern CWA; note that 1.28" is the highest PWAT ever measured by a radiosonde out of ILX through the month of January. Perhaps the most notable change in the forecast since yesterday is the uptick in instability driving up the thunder and heavy rain potential. Anywhere from 100 to 400 J/Kg of elevated low level CAPE, deep layer saturation, and plenty of synoptic support from the left exit region of a 45-60 kt LLJ suggest widespread moderate to heavy rainfall. The GFS, Euro, and NBM like to think areas roughly southeast of I-55 will see heavier rain and, resultantly, higher QPF where PWAT values are expected to be a bit higher, forcing from the LLJ will likely be greater, and where the Euro thinks there will be significantly more instability. The widespread, heavy rain will taper off to the northeast early Tuesday morning with a few lingering showers possible through the morning and perhaps into the early afternoon. QPF across most of the area is averaging out around 0.4" to 0.8". However, as previously mentioned, further southeast in the CWA may see higher rain totals. The GFS is the most aggressive in this area spitting out around 1.5"+ of QPF through Tuesday morning. The Euro is thinking closer to 1" in these parts. Now to touch on the thunder potential. As noted above, the increase in forecast instability has both increased and expanded thunder chances across the area. A thunderstorm certainly seems possible now area-wide, though the greatest thunder chances remain south of I-80 where the greater instability and stronger LLJ are expected. A not- so-terrible shear profile featuring as many as 45 kts of 0-1 km shear and some modest low level veering suggest a non-zero severe thunderstorm potential. Deep convection doesn`t appear too likely given that just about all of our instability will be confined in the lowest 300mb. However, that fact shouldn`t put too much of a damper on a strong wind threat. The majority of Tuesday will be rain-free underneath a sizable dry slot aloft even preceding the passing of the cold front at the surface. The front will be passing over Tuesday evening pulling temperatures from mid 50s and lower 60s Tuesday afternoon back to near or below freezing by Wednesday morning. Highs in the 30s can then be expected through the rest of the workweek. The cooler profile could provide us with some snow showers on Wednesday if moisture and forcing play out as expected. Moisture availability has been shaky for Wednesday, but models have come to a good consensus on a good deal of moisture wrapping around the backside of the system and resaturating the 950-700mb layer, especially closer to the IL/WI state line. Some modest PVA is anticipated through this layer along and east of the low level trough axis. The NBM is still rather conservative on the snow potential compared to other models which have almost all come to agree that we will see at least some snow fall on the area. A lack of additional forcing and little to no snow production within the DGZ should keep snowfall on the lighter side. Plus, the above-freezing surface temps should inhibit accumulation, especially on roadways which will inevitably be even warmer. The greatest potential for snow will be Wednesday afternoon into the earlier part of the evening. Light snow may last through the night for parts of northwest IN and locales closer to the lake. The lake-effect potential we`ve been eyeing is looking modest at best with a lack of forcing and the not-so-impressive cold air mass providing little lake-induced instability. However, some lake enhancement toward the end of the event over the aforementioned areas appear certainly possible. Doom && .AVIATION... For the 00Z TAFs... The primary aviation concerns through the TAF period are as follows: * Period of showers this evening, most likely at RFD but possibly also DPA/ORD/MDW/GYY * Second period of shower after midnight most likely at DPA/ORD/MDW and possibly GYY * Quickly deteriorating cigs/visbys toward sunrise with high confidence in IFR and medium (but growing) confidence in LIFR conditions Regional radar imagery depicts an area of showers stretching from eastern Iowa into southern Wisconsin, which are associated with a compact system lifting northeastward into central Wisconsin. Over the next few hours, the showers should continue eastward through a pocket of dry low-level air may chew up most raindrops before the reach the ground. Confidence is highest in precipitation occurring this evening at RFD where the low-level dry air is least prevalent. For this reason, will maintain the inherited TEMPO group at RFD and VCSH groups at ORD/DPA/MDW/GYY. Cigs and visbys will remain VFR through midnight. After midnight, a second system is expected to track across northern Illinois leading to the development, if not invigoration, of showers primarily over DPA/MDW/ORD/GYY between the hours of 07-11Z. As showers taper toward sunrise, cigs and visbys are expected to rapidly deteriorate thanks to increasing subsidence and a weakening low-level pressure gradient behind the departing wave. High resolution model guidance unanimously shows cigs building below 500 feet and visbys below 1 mile from sunrise to early Sunday afternoon, giving high confidence in IFR and medium (and growing) confidence in LIFR conditions. For now, will introduce 1-2SM visbys and OVC004 to OVC005 cigs at all terminals from 11Z onward keeping in mind even lower conditions may need to be introduced in future TAF packages. Confidence in how fast conditions improve Sunday afternoon is lower than average owing to a lack of traditional mechanisms to scour our low-level moisture. For one, low-level winds will slacken in response to a surface pressure col stalling overhead. As a response, there will be little in the way of moisture or temperature advection, allowing for conditions to more or less stagnate. Interestingly, model guidance ubiquitously advertises a gradual return to VFR conditions Sunday afternoon (maybe thermal mixing even with the low sun angle?), so will hedge optimistically and to the same. However, it would not be surprising in the least to see low clouds remain well into Sunday afternoon and beyond. Borchardt && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Memphis TN
536 PM CST Sat Dec 31 2022 ...New AVIATION... .DISCUSSION... (This evening through next Friday) Issued at 149 PM CST Sat Dec 31 2022 GOES-16 Satellite trends this afternoon place an upper level trough axis stretching from the Northern Plains back through portions of the Mississippi Valley and Southern Plains. Meanwhile, at the surface a weak cold front stretches from New York back through Middle Tennessee and portions of West Tennessee and Arkansas. GOES-16 Visible satellite trends have continued to indicate clearing of the morning fog/low stratus resulting in mostly sunny to partly sunny skies. As of 2 PM CST, temperatures across the Mid-South range from the lower to middle 50s north and 60s south. The potential for fog and/or stratus tonight along with strong to severe thunderstorm potential late Monday afternoon into early Tuesday morning are the predominant challenges in this afternoon`s forecast issuance. Surface and shortwave upper level ridging will build into the Mid-South tonight into New Year`s Day. Short term model soundings indicate the boundary layer will remain moist below a subsidence inversion. This moisture combined with relatively clear skies initially and temperatures falling tonight in the 50s to near dewpoints in the 50s will result in the development of patchy to areas of fog this evening into New Year`s Day morning. Any fog that develops is anticipated to gradually lift into a low stratus layer as boundary layer winds begin to increase towards morning. The evening shift will monitor visibility trends and consider dense fog headlines if conditions warrant. Highs on New Year`s Day will be in the middle 60s to lower 70s with the warmest temperatures over North Mississippi. Highs on Monday will be in the upper 60s to lower 70s. Short term models indicate an upper level trough off the California Pacific Coast will move into the Rockies/Southwest United States Sunday night, then becoming negatively tilted as it moves northeast into the Upper Midwest by Monday evening. Upper level forcing will increase as 60-80 DM 500 mb height falls spread across the Mid-South Monday night into Tuesday morning and favorable upper level divergence produced by the right entrance region of a 180 300 mb upper level jet spread across the Lower Mississippi Valley. Favorable upper level forcing, moderately steep 700-500 mb layer mid-level lapse rates, and favorable kinematics (speed and directional shear) suggest a potential for strong to severe thunderstorms across portions of the Mid-South between late Monday afternoon into Tuesday morning. However, the main limiting factor continues to be the amount of available surface/mixed layer instability during this aforementioned time. GFS/ECMWF ensemble data continues to indicate the best corridor of marginal instability remaining mostly over portions of East Arkansas (south of I-40) and over Northwest Mississippi (west of I-55) late Monday afternoon into Monday evening then tapering off into the remainder of North Mississippi late Monday night into early Tuesday afternoon. An early look at potential times for severe weather would be between late Monday afternoon into early Monday evening as a warm front moves north across the Mid-South and when a quasi-linear line of convection along a cold front moves through the area late Monday night into Tuesday morning. Large hail, damaging winds, and perhaps a tornado or two might be possible but the amount of instability may end up tempering the overall potential and coverage of severe thunderstorms across the Mid-South especially north and east away from the aforementioned areas. Stay tuned... In addition, heavy rainfall will be possible with this convection as precipitable water values rise to above the 99th percentile (1.5 inches) for January with 1 to 3 inches of rain forecast mostly along and west of the Mississippi River. Long term models indicate a couple of mid-level shortwave troughs will rotate around an upper low in the Ohio Valley by the middle of next week. Cooler temperatures but no precipitation is anticipated with the passage of these upper level synoptic features. Temperatures will gradually moderate towards next weekend as upper level ridging builds back into the Mississippi Valley. CJC && .AVIATION...(00Z TAFS) Issued at 526 PM CST Sat Dec 31 2022 Backed off on the low visibility tonight based on latest HRRR and NBM guidance as well as expected wind around 4-5 kt overnight. Low CIGs will still result in LIFR conditions. South wind will increase to around 8-11kt tomorrow and high clouds will overspread the Midsouth. VFR conditions should prevail tomorrow after midmorning into tomorrow night. && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$ PUBLIC FORECAST...CJC AVIATION...JDS
Area Forecast Discussion
National Weather Service Morristown TN
908 PM EST Sat Dec 31 2022 ...New UPDATE... .UPDATE... Issued at 904 PM EST Sat Dec 31 2022 A bit more clearing than earlier forecast, but fog and low clouds are increasing. Some of the fog is locally dense, and an SPS for localized dense fog has been issued. Will continue to monitor in case the dense fog gets widespread enough to trigger a dense fog advisory. Have increased fog coverage with this update, and decreased PoPs/shower coverage as precip has been staying mainly to our north. && .SHORT TERM... (This evening through Sunday) Issued at 320 PM EST Sat Dec 31 2022 Key Messages: 1. Majority of the rain exits east late this afternoon, but a few light showers/sprinkles will accompany the front later this evening. Patchy fog overnight. 2. Clouds hang around through most of the day tomorrow with above normal high temperatures. Discussion: Overview: A cold front moving into middle TN will move across our area this evening, exiting east of our area before midnight. The last of the heavier precip is currently moving through the east TN Valley now. The latest HRRR shows this line exiting east around 4 to 5 PM EST. Then, expect a few light showers/sprinkles to accompany the front later this evening. QPF amounts will be lighter with the activity along the front, where only a few hundredths of an inch of precip is expected. Patchy fog is expected overnight. Overnight lows remain mild as we only dip down into the mid to upper 40s, which is 15 to 20 degrees above normal. With weak westerly flow, low-level moisture remains trapped in the valley tomorrow so expect clouds to be around through most of the day. Some areas could see a few breaks late in the afternoon but expect more clouds than sun. Highs will again be above normal with temps in the upper 50s to mid 60s. && .LONG TERM... (Sunday night through next Saturday) Issued at 320 PM EST Sat Dec 31 2022 Key Messages: 1. A strong storm system will bring a return of rain to the region Tuesday through Wednesday after dry and and unseasonably mild conditions on Monday. 2. High winds are possible in the mountains by Tuesday, in addition to widespread moderate to heavy rainfall and thunderstorms. A few strong to severe thunderstorms are possible Tuesday evening, mainly in southern areas. 3. Cooler temperatures return by Thursday onward. Sunday Night through Wednesday At the start of the period, upper ridging will be building into the region with surface high pressure centered across the southeastern U.S. This will continue a warm and dry pattern ahead of a trough/system initially located over the Rockies. 500mb heights are expected to reach 5,800 meters or higher, values typical in May, which emphasizes the extent of above normal temperatures expected early in the week. Heading through the day on Monday, the aforementioned trough will eject out of the Rockies and become increasingly negative in its tilt as it progresses northeastward into the Great Plains. This will also be coincident with the surface low deepening to 995mb on a similar track. There still remains minor timing and spatial differences regarding the evolution and track of the surface low, but the overall consensus is for it to track up towards Iowa on Monday night as an open wave. Based on the timing and track of the system, PoPs will increase from west to east later on Tuesday and continue through much of the day on Wednesday as a coupled jet structure sets up aloft. As the system follows this trend and progression, the consensus is for the 850mb jet to strengthen to 50 to 60 kts northwest of the region by Tuesday morning. This will also come with a tightening of the MSLP gradient over the mountains and adjacent foothills. As such, confidence continues to increase for potential of mountain wave winds out ahead of the system. With lingering uncertainty in exact details and available data, messaging will be kept largely the same. Regarding the potential for thunderstorms, overall dynamics will support organized, potentially strong convection by Tuesday evening. Deep-layer shear will be in excess of 50 kts area-wide with low- level SRH of over 200 m2/s2. These values will be enhanced by the continually strong 850mb jet. Much of the uncertainty still lies with instability and how far northward it reaches into the area. The 12Z GEFS, for example, shows 80% or more probability of SCP values exceeding 1 in southern portions of the area but only 30% to 40% probability of over 500 J/kg of surface-based CAPE. For the 250 J/kg threshold, however, values are above 60% across the southern half of the region. There is also a slightly slower trend in the arrival of convection with this most recent model run that could shrink the window of concern during this timeframe. Overall, confidence in the dynamics and potential for sufficient instability are both high enough for elevated concern of strong/severe convection. In any case, locally strong winds are certainly possible with any thunderstorm due to the low-level jet. With respect to potential for flooding, anomalous moisture above the 90th percentile and depth to the warm cloud layer will be in place, emphasizing potential for efficient rainfall rates within any convection. At the time of this forecast issuance, the current FFG indicates that rainfall totals of 3" in a 6-hour period would be needed to cause flash flooding. This value will definitely change in the coming days, but the likelihood of two main rounds of rain, one Tuesday evening and one Wednesday morning, will keep concerns for localized flash flooding. This will be maximized in the southern half of the region with better expected coverage. Nevertheless, the downward trend in overall rainfall totals continues with most places unlikely to reach close to this threshold. Overall, messaging for impacts from this system will remain the same with the main difference being a slight increase in confidence for severe potential and a decrease in confidence for flooding based on recent trends. Thursday through Saturday By the end of the period, troughing will build into the region with a more northwesterly low-level flow pattern. This will all make the case notably cooler temperatures than earlier in the period. With some lingering low-level moisture, low-end PoPs were kept in the forecast, focused in the mountains. There is certainly potential for transition to light snow showers, but this looks to be of minimal impact and limited to the highest elevations if it occurs. Dry and seasonally cool conditions will continue into the weekend as strong high pressure sets up in the eastern U.S. && .AVIATION... (00Z TAFS) Issued at 559 PM EST Sat Dec 31 2022 CHA/TYS will likely start off VFR with MVFR to start at TRI, and while the details are still murky at best it appears all sites will deteriorate in fog/low cigs overnight with conditions at least as low as IFR likely by later tonight. Expect some improvement late in the period with VFR conditions expected before the period ends. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 50 66 49 69 / 10 0 0 10 Knoxville McGhee Tyson Airport, TN 48 63 44 68 / 10 0 0 10 Oak Ridge, TN 47 61 44 66 / 10 0 0 10 Tri Cities Airport, TN 47 60 40 67 / 20 0 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...SR LONG TERM....BW AVIATION...
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
427 PM MST Sat Dec 31 2022 .DISCUSSION...(This Evening Through Saturday) Issued at 153 PM MST Sat Dec 31 2022 Upper trough beginning to dig into the western CONUS and will eventually eject into the central plains this week, supporting heavy snow over parts of the region. Confidence in snow amounts remains medium to low on the northern side of this system, which is basically all of the FA outside of scentral SD, due to concerns on dry air to the north and the mean location of the progged LL FGEN max. Weak impulse traversing the region this afternoon, resulting in some light snow over the higher elevations of the central and southern BH, with dry air winning out elsewhere. This band of weak lift will shift SE this afternoon with possibly a few light snow showers lingering over scentral SD this evening. Attention then turns toward the vigorous upper trough taking aim on the region. Lead northern split wave will support a WAA regime over the far SW Sunday afternoon evening, allowing increasing chances for snow there. Snow will then then slowly shift ENE Sunday night into Monday, with snow spreading into most of far southern SD by Monday morning. Forecast models are starting to come into some agreement with the storm track and some of the dynamics, namely where the best FGEN and associated snow band will likely be. Right now most forecast models are progging the axis of strongest FGEN over NE into scentral SD AOA h7. The strongest lift and heaviest snow would be expected just to the south of the FGEN max. This is also starting to be confirmed in the RAP and HRRR, which both support the heaviest snow on the southern side of most medium range model solutions. To the north of the FGEN band, snowfall will be much lighter, with amounts likely in the adv range. However, given the long duration of the event, current forecast amounts come close to low end warning numbers and felt given the continued uncertainty in model solutions a northward extension of the watch was warranted, esp along the eastern foothills of the BH where some upslope enhancement still looks possible. Again, the northward side of the snow shield has the highest uncertainty with large foretasted ranges given intrusion of dry air and potentially weaker lift north of the FGEN max and feel snow amounts are likely over done there. Further west, have opted for an adv over southern Campbell and Weston Counties given an earlier start to snow per the lead trough with 2 day total amounts up to 8 inches possible in the far southern portion of these counties. Still expecting breezy northerly winds Monday night into Tues over scentral SD, with some blowing snow possible. Snow will shift east and end Monday night across the area west to east, possibly lingering over scentral SD into Tues morning. Not much cold air behind this system with seasonal temps the remainder of next week with dry conditions. && .AVIATION...(For the 00Z TAFS Through 00Z Sunday Evening) Issued At 424 PM MST Sat Dec 31 2022 Leftover very light rain/snow showers over south-central SD will end by 03z. VFR conditions are expected through 12z Sunday. An approaching storm system will bring MVFR/IFR CIGS into the far southwest reaches of the CWA Sunday morning, slowly progressing northeast through the afternoon. KGCC won`t be affected before 21z Sunday with KRAP after the forecast period. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Winter Storm Watch from late Sunday night through Tuesday morning for SDZ026-030>032-042>044-046-047-049. Winter Storm Watch from Sunday evening through Tuesday morning for SDZ027-029-041-074. WY...Winter Weather Advisory from 3 PM Sunday to 11 PM MST Monday for WYZ055-058. && $$ DISCUSSION...JC AVIATION...Helgeson
Area Forecast Discussion
National Weather Service Las Vegas NV
645 PM PST Sat Dec 31 2022 .SYNOPSIS...Widespread rain, high elevation snow, and gusty winds will impact the region tonight and tomorrow. Model simulations show that this active weather pattern will continue through the first week of the New Year. && .UPDATE...Current satellite imagery shows moisture streaming into the western United States from the Pacific, which has brought impressive rainfall to parts of California. Snowfall estimates of around a foot are being reported from sites in the eastern slopes of the Sierra. Most of the moisture is being blocked by the Sierra at this time. That being said, rainfall has already started at Bishop and in sections of the southern Great Basin. Short term guidance shows a slower advance of precipitation into the Las Vegas Valley. Confidence is decreasing in precipitation reaching Las Vegas before midnight, thinking it will mainly reach the city in the early morning hours. Gusty southerly winds should persist through the night, but gust intensity is coming into question as observations are around 5 to 10 knots lower than previously expected. && .SHORT TERM...Through Sunday night. Beginning to see more reports of light rain spilling over the southern Sierra into the Owens Valley. Otherwise, the Mojave Desert is windy as south-southwest winds are occurring well out ahead of the potent trough off the central California coast. From snow pillows, I`d estimate between 5-7 inches of snow at the higher elevations in Inyo County. Latest radar imagery show next pulse of heavy rain moving into central California with reflectivity enhancements increasing on the western slopes of the southern Sierra indicating onset of moderate- heavy precipitation. Progressive nature of the trough will push this precipitation shield south into south California late this afternoon/evening. HRRR indicates heavier rain breaking out across the western Mojave Desert this evening before pushing east into southern Nevada later this evening. Onset of precipitation around Las Vegas still continues to be around 9-10 pm, while main band shift through between midnight and 5 am New Years Day. That main band continues east through Mohave County AZ Sunday morning with embedded thunderstorms possible across southern Mohave County where CAPE is the greatest. Wrap around moisture/instability in colder air on backside of trough will keep showers going across southern Nevada and eastern through much of New Years Day as well. Strong wind gusts of 40-50 mph have been observed in northwest San Bernardino County, while Angel Peak in southern Nevada consistently 60-70 mph since 10 am. Pockets of these stronger winds will continue through tonight. Post-frontal winds out of the northwest will remain gusty New Years Day. Am not going to add any additional products to the mix as elevations above 6000 feet in Mohave County will probably see less than 3 inches between late Sunday afternoon and Sunday night. Pleasant temperatures ahead of the storm today but 8-12 degrees colder behind the cold front tomorrow. .LONG TERM...Monday through Saturday. Sunny and dry start to Monday morning expected with below-average temperatures and breezy southwest afternoon winds. Thereafter, there is quite a bit of change to the forecast compared to our analysis 24- hours ago. An additional round of moisture will approach the western CONUS, bringing PoPs to the region Monday night into Tuesday. QPF has dropped substantially, which coincides with IVT plumes indicating the weak atmospheric river will take a further south track inland. That said, QPF has not completely dropped off, with moisture making its way south and around the Sierra Nevada Mountain Range and over the San Bernardino mountains. ECMWF ensemble means put forecast PWAT values around half of an inch across the Mojave Desert Monday night. With this system will come some of the lowest precip-combined snow levels of the season, bottoming out around 2700 feet in Las Vegas. Not expecting anything in the way of accumulation, especially with the greatly diminished forecast precipitation totals, but cannot discount the chance of snow flurries on the western side of the Las Vegas Valley, and even a dusting in higher elevations of Summerlin and Red Rock. No impacts expected with this system other than impacts that accompany snow- related distracted driving. Remember to keep 2 times the distance between your car and the car in front of you, as slick roadways are more often caused by light precipitation than a deluge. A brief break in wintry weather expected Tuesday and Wednesday morning before the next wave approaches. As with the early-week system, this forecast is trending drier with a less favorable trajectory for Mojave Desert rainfall. QPF has dropped for the valleys and inland mountains, but increased for the Sierra Crest, as the bulk of the available moisture smacks into the mountain range and wrings out with minimal spill over. High uncertainty remains with this forecast, so details are subject to change as we approach this event. Through midweek, temperatures will remain a few degrees below seasonal averages, then will gradually increase toward average late- week. && .AVIATION...For Harry Reid... As a storm system moves across the region, conditions will deteriorate at the field later this afternoon and evening. Decreasing CIGs can be expected by late afternoon, falling below 5kft this evening. Showers are also expected in the vicinity of the field after 02Z, with showers becoming likely between 06Z and 12Z. Showers will become more scattered tomorrow after 12Z, but the threat of precipitation and decreased CIGs will persist into tomorrow afternoon. Winds will also become gusty out of the north by Sunday afternoon as a cold front moves through the Vegas Valley. It should be noted that if the New Years Eve fireworks display along The Strip does occur at midnight as scheduled, a period of additional low-level obscuration due to smoke can be expected in the vicinity of the field. For the rest of southern Nevada, northwest Arizona and southeast California...Gusty winds, low CIGs, and areas of light to moderate precipitation will result in poor flying conditions across the region today into Sunday. Additionally, downslope winds off the Sierra near KBIH could lead to sudden cross winds and LLWS in that area. Slowly improving conditions are forecast west to east across the area Sunday afternoon as the storm system exits the region. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Meltzer SHORT TERM...Pierce LONG TERM...Varian AVIATION...Planz For more forecast information...see us on our webpage: or follow us on Facebook and Twitter