Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/24/23

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
901 PM CDT Thu Mar 23 2023 .UPDATE... Issued at 853 PM CDT Thu Mar 23 2023 Starting to see our first signs of fog developing across McPherson county. Latest look at available visibility guidance still suggests an increase in areal coverage of fog throughout the night, so not much change to the forecast there. Still dealing with some stratus over central SD, and expect an increase in that through the night as well. No changes to low temp forecast as it remains a tricky and low confidence forecast once again, as it will largely depend on cloud cover. && .SHORT TERM...(This Evening through Friday Night) Issued at 206 PM CDT Thu Mar 23 2023 Sfc high pressure will dominate through Friday night. This will set the region up for dry conditions. However, with afternoon sunshine, llm will be abundant overnight especially after highs jump into the 30s on Friday. Places with melting snow will see fog develop both tonight and Friday night. Fog may be dense at times. Temperatures will be the main forecast challenge given the relatively fresh snow, fog/stratus potential and weak waa tonight then weak caa Friday night. Cloud cover is the biggest question mark. Any breaks in the clouds or drops in the wind will lead to very quick drops in temperatures both night. Went with a blend of the HRRR and NBM 25th to try to capture the potential for overnight lows in the single digits. All temperatures - lows and highs - will remain below normal by 10 to 25 degrees except from Pierre south where highs will be close to normal for late March. .LONG TERM...(Saturday through Thursday) Issued at 206 PM CDT Thu Mar 23 2023 Not much overall going on in the extended. For the most part, a strong southern stream split flow should keep us dry with only weak, subtle features passing through with little continuity between different deterministic families. The one caveat is at the tail end of next week when deterministic models begin to develop a deep trough over the Rockies and eject a Colorado or Texas low type system. Again, zero confidence at these timescales. The only real concerns will be the possibility for some light blowing/drifting snow Saturday. North winds topping out around 20kts at 1/2km and in BUFKIT mixed down nothing earth shattering, however we have a lot of snow sitting around and it remains cold. Speaking of which, highs/lows through the 7 day period range from 10 to 25 degrees below don`t anticipate the snow to go away anytime fast. && .AVIATION...(For the 00Z TAFS through 00Z Friday Evening) Issued at 629 PM CDT Thu Mar 23 2023 Terminals KABR,KATY,KPIR,KMBG MVFR/IFR CIGs/VSBY are once again in the forecast for the TAF period. Only KPIR seeing CIGs around 3000 ft at the start of the period, but models continue to suggest an expansion/development of the lower CIGs as the night progresses, as well as an onset of BR/FG. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...TMT SHORT TERM...Wise LONG TERM...Connelly AVIATION...TMT
Area Forecast Discussion
National Weather Service Burlington VT
1011 PM EDT Thu Mar 23 2023 .SYNOPSIS... Cool and dry weather is expected on Friday as high pressure briefly crosses the region. Then as a strong low pressure system passes to our northwest, an elevationally dependent mixed precipitation and snowfall event will unfold over the region Saturday into Saturday night. Some light snow and ice accumulations are possible. After lingering showers on Sunday, we turn towards drier weather early next week. && .NEAR TERM /THROUGH FRIDAY NIGHT/... As of 1008 PM EDT Thursday...Precipitation has all but come to an end as of 10 PM with just a few spits of rain across central Vermont. Any lingering shower activity will dwindle quickly over the next few hours with dry conditions expected by midnight. The cold front continues to take it`s sweet time as it`s still hugging the International Border near the St. Lawrence River. The latest NAM3 and RAP model suites show the front becomes more progressive over the next few hours which should bring a steady drop in temperatures and dewpoints as winds shift to the northwest. Ahead of this front, however, patchy dense fog continues to plague portions of Vermont given the latest rainfall, warm temperatures, and extensive snow pack. All signs show this fog lifted behind the frontal passage. Previous Discussion...Low pressure currently positioned just to our north will continue to pull away to the east overnight and Friday, with ridging following along behind. Widespread rain this afternoon will taper to showers this evening and come to an end early Friday as drier air spills in behind the low. Temperatures will cool overnight as well, so rain may mix with and/or change over to snow before finally ending, especially in the higher terrain. Clouds will be slower to depart, and expect we`ll have a fairly dreary start to the day Friday. Moisture will continue to thin through the day though, so we`ll see improving conditions with everyone getting at least some sunshine before sunset. The ridge crests directly overhead Friday night, resulting in light winds and at least some clearing, though high clouds will begin to increase in western areas toward daybreak Saturday ahead of our next system. Temperatures tonight will bottom out in the mid 20s to lower 30s, and then we should warm up into the mid 30s to mid 40s on Friday, perhaps even a bit warmer for those areas that get sunshine. Friday night will be chilly under the ridge; lows in the 15F to 25F are expected. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... As of 331 PM EDT Thursday...Still expecting a messy mix of wintry precipitation, though as has been warned over the past couple of days, the details continue to evolve. Main change has been for the warm nose aloft to push further north, meaning more mix, and potentially freezing rain, especially for southern sections/higher elevations. Overall the expected set up remains the same, with an anomalously strong low to lift up to our west. Precipitation will spread northward into the area Saturday, but with dry air in place, it will take a while before the column is able to saturate and precipitation reaches the ground. Models continue to indicate a band of strong frontogenetical forcing to lift northward late Saturday afternoon into the evening hours, and this heavier precipitation will aid to cool the column. Therefore, expect even in areas that warm above freezing, any light rain will mix with/transition to snow, particularly at higher elevations. With an 55+ kt 850mb southeast jet, this first batch of precipitation will focus on the east-facing upslope sides of the southern Greens and Adirondacks. These winds will gradually turn to the southwest during the evening/overnight, ushering in a warmer layer of air aloft. Valley locations may be able to remain mostly rain as temperatures recover after initial burst of heavier precipitation. But higher elevations should turn over to more of a snow/sleet/freezing rain mix, especially along/south of a Massena, NY to Montpelier, VT line. As a secondary low starts to develop off the New England coast Saturday night, temperatures will cool aloft, once again transitioning over to mainly elevation-dependent rain/snow from west to east. At this time, latest forecast calls for elevations below 1500 ft see less than an inch of snow accumulation, with 1 to 4 inches possible above 1500 ft. Ice accumulations would be a glaze to around a tenth, with the best chances for appreciable accretion in the central/southern Greens and Adirondacks. However, we continue to stress that given the complex scenario of elevation vs thermal profiles, these numbers will likely change as the forecast evolves. Also of concern for Saturday afternoon/evening will be the potential for these higher winds to mix down; note the NAM in particular is quite gusty, with 40-45kt mean-mixed layer winds. The western downslope sides of the Greens/Adirondacks would be most susceptible to gustier conditions Saturday afternoon/evening. However, as winds turn to the west/southwest Saturday night, the St Lawrence Valley and eastern sides of the higher terrain would see the higher gust potential. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 331 PM EDT Thursday...Some showers linger around on Sunday as the double-barrel low system continues trek eastward. There is potential for strong surface winds given strong low level westerly/southwesterly flow. Precipitation will taper off by Sunday evening as ridging starts to build in, giving us some quiet weather for the start of the work week. There is a lot of model disagreement regarding midweek and how it plays out, but there is weakening support for a midweek system like previous guidance was showing. At this point, continuing the trend of SChc/Chc PoPs seems to make the most sense given the wide range of possibilities and large amount of uncertainty. Still plenty of time for model consensus to increase, but stay tuned to see how everything will play out. Temperatures look to remain fairly seasonable through the extended forecast, with daytime highs in the mid 30s to mid 40s and overnight lows mainly in the 20s. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Through 00z Saturday...Extremely up and down TAFs this evening. With rain becoming more showery or scattered, the main vis concern will be fog for the next few hours. Fog has already developed in various spots across the forecast area, but the question remains whether they will impact the airports and for how long. It will likely be a very unpredictable few hours as fog moves in and out of sites. Vis expected to drop to 1/4SM at lowest in KMPV. Cigs will gradually lift throughout the period, but this will be another timing issue with plenty of tempo groups, as cigs will go up and down before going solidly VFR. Lowest cigs will be around 300 ft AGL in KMSS, but like the other sites, cigs will likely come up to VFR within the next 24 hours. By around 10z Friday, fog will probably not be a concern anymore, either. Winds calm or southwesterly are expected to turn westerly (KMSS) or northwesterly over the next 24 hours at all sites. Outlook... Friday Night: VFR. NO SIG WX. Saturday: Mainly VFR, with areas MVFR and IFR possible. Definite RA, Definite SN. Saturday Night: Mainly MVFR and IFR, with local VFR possible. Windy with gusts to 30 kt. Definite RA, Definite SN, Definite PL, Chance SHRA. Sunday: Mainly VFR, with areas MVFR possible. Chance SHRA, Chance SHSN. Sunday Night: Mainly VFR, with areas MVFR possible. Slight chance SHSN. Monday: NO SIG WX. Monday Night: Slight chance SHSN. Tuesday: Chance SHSN, Chance SHRA. && .HYDROLOGY... As of 330 PM EDT Thursday...A low chance of river flooding will be monitored for the late tonight into Friday morning period in response to light to moderate rainfall with basin averages of 0.2" to 0.5" and snow melt up to 1". High dew points have helped to ripen the snow pack with continued melting at lower elevations. Therefore, modest to sharp river rises may occur by this evening into Friday in the watersheds with runoff primarily due to snow melt. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Hastings NEAR TERM...Clay/Hastings SHORT TERM...Hastings LONG TERM...Kremer AVIATION...Storm HYDROLOGY...WFO BTV
Area Forecast Discussion
National Weather Service Huntsville AL
1052 PM CDT Thu Mar 23 2023 ...New AVIATION... .NEAR TERM... (Rest of tonight) Issued at 918 PM CDT Thu Mar 23 2023 After a very nice day despite some cloud cover with highs reaching the 80 to 83 degree range in many areas in northern Alabama, temperatures have dropped into the upper 60s to lower 70s in most locations at this time. The cloud cover has not dissipated much north of the Tennessee River yet. Most guidance isn`t picking up on this, but the HRRR does seem to be. In fact, it hints at additional cloud cover developing between 10 PM and midnight tonight further southwest over northeastern Mississippi and NW Alabama. Looking at satellite imagery, there appear to be hints that this will occur over the next few hours. Then HRRR forecasts a lower cloud deck moving northeast into NW Alabama after midnight. This looks to be the more widespread and persistent level of cloud cover overnight. Around daybreak HRRR shows this cloud deck moving east into NE Alabama and southern middle Tennessee. It looks like we could see some clearing east of the I-65 corridor possibly hanging on until just before daybreak, especially south of the Tennessee River. Thus, expect lows to drop lower in those areas. Expect a few isolated valley locations such as Fort Payne will be sheltered from winds as they pick up after midnight for a longer period, so some lows around 57 degrees could occur in extreme northeastern portions of Alabama. Further west, based on expected cloud cover trends and expected winds have raised low temperatures into the 60 to 65 degree range. && .SHORT TERM... (Friday through Saturday night) Issued at 253 PM CDT Thu Mar 23 2023 A low pressure system in western Texas is expected to continue eastward overnight. In response to this, a cold front will form and move into the MS Valley Friday night. Ahead and along the cold front, strong to severe storms are possible. Threats include tornadoes, damaging winds (both non-thunderstorm/gradient and thunderstorm), hail, and flooding. As of now, we have medium confidence in tornadoes and damaging winds-- particularly in NW AL where our shear and instability align. We also have medium confidence in the potential for flooding in NW AL, which is highlighted by a slight ERO from WPC. Model sounding PWAT values are ranging from 1.4-1.7" in this area, which is approaching or breaking SPC sounding climatology values per OHX and BMX for March 25. In addition to this, mid and low level RH values are high (over 75%). The main limitation to flooding will be how fast the storms move through the area and if any training occurs. For now, rainfall totals are expected to remain between 0.5" to 1.5" (with higher amounts in NW AL/southern middle TN and lower amounts in NE AL). As the storms move eastward, through the I-65 corridor, we have low confidence in severe potential due to limited instability. Despite the lack of confidence in a severe threat, we are confident there will be a wind threat in some capacity throughout our entire forecast area both ahead of and behind the cold front. Due to saturated soils and weakened trees, downed trees and subsequent power outages are possible. A Wind Advisory will likely need to be evaluated on the forecast package update overnight tonight to account for gusts up to 45 mph. By Saturday morning, thunderstorm chances end gradually from west to east. However, even after the rain ends, gusty winds will continue to be a threat as a secondary, dry frontal passage is possible. Expect dry weather Saturday afternoon into Saturday night with temperatures reaching the mid to upper 70s before dropping into the upper 40s to lower 50s. && .LONG TERM... (Sunday through Thursday) Issued at 253 PM CDT Thu Mar 23 2023 The main focus in the long term period will be a weak upper disturbance that slides east through the upper Midwest, pushing a second cold front through the area on Monday. The stalled sfc front will begin to lift back north on Sunday, but models continue to keep the best moisture just south of the forecast area. Slight chances for showers (15-25%) will return Sunday morning and increase to 50-60% Sunday evening, primarily south of the TN River. Widespread flooding does not appear likely at the moment, with models trending farther south with the higher rainfall axis, but will continue to monitor trends especially after heavy rain on Friday. Highs will range from the low to mid 70s both Sunday and Monday, before another shortwave reinforces a dry and slightly cooler airmass on Tuesday. Temps will be much closer to seasonal norms through the mid-week period, with highs in the mid 60s and overnight lows in the low to mid 40s. && .AVIATION... (06Z TAFS) Issued at 1052 PM CDT Thu Mar 23 2023 VFR conditions are expected for a few more hours after midnight. Then around 9Z, expected MVFR CIGS to develop and move northeast affecting the terminals. Expect these MVFR CIGS to remain in place through 18Z or 19Z at the terminals before lifting to around 5000 feet. Introduced -TSRA after 4Z at KMSL for a line of convection expected to be moving through the terminal then. KHSV arrival looks a few hours later, so left it out of this issuance for now. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...KTW SHORT TERM....HC LONG TERM....25 AVIATION...KTW
Area Forecast Discussion
National Weather Service Shreveport LA
1103 PM CDT Thu Mar 23 2023 ...New UPDATE... .UPDATE... Issued at 956 PM CDT Thu Mar 23 2023 Evening satellite highlights a deep layer of low level cloud coverage working north associated with stronger moisture advection underway. Sfc obs showcasing dew points in the 70s being present across southern zones near Lufkin, TX. Aloft, SW flow will help to overspread upper level cirrus linked with convection located in N/TX and S/OK. These storms will continue to move east this evening, ultimately ending up in our NW zones, specifically McCurtain County just after sunrise. Looking into the guidance tonight, some concern does exist regarding the potential for rotating sfc based thunderstorms in the aforementioned region just before 7AM. Hi-res guidance suggests sfc based CAPE 1400-1500J/kg, with shear between 30-35kts. Even if rotation does not materialize, hail and damaging winds will be a threat with these storms. Troughing across the SW CONUS will continue to work east overnight, helping to develop the sfc low that will drift a cold front across the Four State Region tomorrow afternoon, igniting a severe weather threat locally where all hazards are in play. This includes but not limited to damaging winds, hail, and tornadoes. Some of those tornadoes may be on the stronger side. Decided to go ahead and add in the severe verbiage to the grids, to then reflect in the zones forecast for all. Overnight crew will digest the latest hi-res, present obs and will have an updated forecast later on in the AM. Temperatures continue to remain on the warmer side overnight. Noticed the advertised forecast was trending cooler than what obs presented. This has been adjusted within this update package. /53/ && .SHORT TERM... (This evening through Friday Night) Issued at 253 PM CDT Thu Mar 23 2023 Very nice spring day in progress with low to mid 80s and southerly winds gusting into the teens and twenties. There are a few peaks better than 25KT, but not too many. We will be partly cloudy into the evening with the HRRR edging some thunderstorms into our NW corner in SE OK after midnight. Not much change overnight as this activity initially parallels the flow aloft with very slow movement southeastward until daybreak. This is in good agreement with the transistion from the SPC day one into day two with our "severe" wording. Also, to be concurrent with WPC day two ERO, for our I-30 corridor with "some maybe heavy" with an inch or two likely in our far north. The model consensus continues to ever so slowly back off on the pace of a solid push with some agreement in what looks like a very stormy spring afternoon right in the heart of our four state area. It looks like some of this severe potential will linger into the early evening for S AR and our eastern LA Parishes with warmer lower to mid 80s found here. Most of us will range in the 70s for highs on Friday. Overall, most of our area will range from a half to inch for this event. And unlike previous systems, not much high pressure arriving, but enough to improve conditions greatly for our early on Saturday. Our lows by daybreak will range from mid to upper 40s in our NW to a wide range of 50s everywhere else. /24/ && .LONG TERM... (Saturday through next Wednesday) Issued at 253 PM CDT Thu Mar 23 2023 In wake of the severe convection Friday afternoon and evening, the dryline is expected to mix ESE out of Cntrl/NE LA into Wrn MS, with deep dry air in its wake yielding continued above normal temps but much lower RH`s areawide with strong insolation. A cool, seasonal night will return Saturday night, before the remnants of the dryline begins to lift back N as a warm front after daybreak Sunday, likely settling into Upper SE TX into Cntrl LA by afternoon. Overrunning is expected to increase along and N of the front Sunday morning, which should result in isolated convection developing over Cntrl LA and spreading NNE and expanding in coverage through the day, aided by weak perturbations in the SW flow aloft. Have undercut the NBM pops during the morning as it is a bit more aggressive, but did maintain likely pops for portions of Deep E TX into Cntrl LA with the expected increase in convection. Weak sfc ridging is progged to shift S into the area Sunday night, reinforcing a drier near sfc air mass back S with the departure of any large scale ascent associated with the weak perturbations departing the area. This bndry should not be deep enough to yield much of a cooldown Monday, as above normal temps return for the afternoon. While the ensembles remain mostly dry Monday night, the deterministic models have trended wetter across much of the region, as the aforementioned sfc bndry retreats back N and becomes stationary somewhere over E TX/N LA. Aside from slight chance pops over portions of Deep E TX into NCntrl LA Monday night, have maintained a mostly dry forecast for now given the uncertainties in the ECMWF/GFS/Canadian on the sfc bndry location as well as ascent needed for convection development. However, stronger sfc ridging is progged to build S into the region Tuesday yielding cooler, more seasonal temps, and drier conditions for midweek. This should change though by Wednesday night and especially Thursday, as a SW flow aloft becomes more established over the region ahead of the next deepening trough moving through the Desert SW. Thus, a return to warmer, more humid conditions is expected by late week, aided by large scale subsidence beneath a building ridge from the TX Gulf coast into the Lower MS Valley. /15/ && .AVIATION... (00Z TAFS) Issued at 720 PM CDT Thu Mar 23 2023 Airspace wide VFR to start the 24/00z TAF period under a mostly clear sky. Light CU field continues to mix in across various terminals with upper level cirrus following the elevated flow working in the extreme NW corner of the airspace. Sat this evening showcases low level coverage working north across the southern airspace, mainly impacting KLFK. Transition overnight to MVFR to low VFR is expected to prevail through the day as CIGs remain lower. The advertised strong to severe storms with all hazards possible (wind, hail, tornadoes) looks to threaten area terminals after 24/20z. During this period, given the enhanced prefrontal sfc southerlies, have elected to keep winds high across area terminals in advance of the passing line of convection. Southerly sfc terminal flow between 15-20kts expected with gust near 30kts, potentially higher with associated storms. /53/ && .PRELIMINARY POINT TEMPS/POPS... SHV 85 69 79 55 / 0 10 90 30 MLU 85 68 84 58 / 0 10 80 70 DEQ 81 66 74 47 / 20 60 100 20 TXK 84 70 77 50 / 10 20 90 20 ELD 83 68 79 52 / 0 10 90 50 TYR 85 69 76 51 / 0 10 90 0 GGG 85 69 77 51 / 0 10 90 10 LFK 86 69 80 54 / 0 0 80 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ SHORT TERM...24 LONG TERM....15 AVIATION...53
Area Forecast Discussion
National Weather Service Salt Lake City UT
451 PM MDT Thu Mar 23 2023 .SYNOPSIS...The active weather pattern will continue. Another round of showers will continue through this evening. A cold front with January-like temperatures and snow levels to valley floors will cross the area Friday morning through Friday afternoon. Below normal temperatures will continue into the weekend. && .SHORT TERM (Through 12Z Saturday)...The short term continues to remain active, with multiple new warnings and advisories issued with this package. Current radar imagery indicates widespread showers continue, with some locations seeing brief slushy accumulations even with the "warm" March sun. Afternoon satellite and upper air analysis indicates a longwave trough across the West. A decidedly cold shortwave trough with an associated jet with an arctic-esque orientation is approaching the Pacific Northwest Coast. This will be the main player through the short term forecast and into the long term forecast period and bring a January-like pattern to Utah. Expect showers to continue through the early evening, decreasing in coverage near sunset. As upper level diffluence associated with the incoming shortwave trough/jet spreads across northern Utah, expect another round of light snow to develop (though some valleys below 4500 feet may mix with rain through around 06Z). A portion of the guidance (~20%) suggests this precipitation may be heavy times, particularly for Salt Lake County between 2-5 AM. The remainder of the guidance suggests relatively light, periodic snow through the early morning period. A stout cold front will cross northern Utah Friday morning (roughly 6-10 AM), bringing a period of moderate to heavy snow, much colder temperatures and gusty winds. Expect northwest winds to gust to 40 mph for many valley locations for 1-3 hours near and behind the cold front. This may also cause some blowing and drifting snow issues for the I-84 corridor from Tremonton to Snowville. Snow will continue, heavy at times, through the early afternoon before again transitioning to snow showers. But this isn`t the end of the precipitation for the CWA as a series of shortwave troughs are lined up behind the first to continue to bring the potential for snow to at least northern Utah through the weekend. It`s actually a very meteorologically interesting pattern...more fully fleshed out in the long term discussion. Given 700mb temperatures near -16C or so and a Great Salt Lake temperatures around 4C or so (which is well below normal climatologically), the threat of lake effect snow will increase Friday night into Saturday morning. Looking at a wide variety of guidance, much of the guidance envelope indicates more than sufficient lake-oriented instability, low level moisture and surface convergence for a well formed area of lake effect snow. Current expectation is a lake effect snow band is likely (>75% chance) impacting an area from near Bountiful to the east side of SLCo. Expect this area may originally develop across the northern extent of this area and then transition south with time. This band is universally supported by CAMS, thought location is less confident. The going winter weather advisory for the valleys is focused on the snow totals for the synoptic portion of this system, but something to keep in mind is that a nearly stationary, long-lived lake effect band will have areas with significantly more snow. This is something that is difficult to latch on to location-wise this far out, so will continue to monitor and adjust the forecast as needed. With the Friday morning commute expecting accumulating snow, especially north of Salt Lake City to the Utah/Idaho border, issued winter weather advisories for the northern and central valleys and western Uintas, Book Cliffs, Wasatch Plateau and central mountains. Given higher expect snow totals in west to northwest flow, issued a winter storm warning for the Wasatch Mountain. As typical in this traditional cold front + northwest flow type event, Utah County from roughly Lehi to near Provo may see the lower end of the snow totals. Additionally, with this strong of a cold front, strong northwesterly flow with sufficient depth for a potential downslope event exists for Castle Country. Currently, there is moderate threat (50-60% chance) for wind gusts to 50 mph in/west of the SR-10 corridor Friday afternoon and evening. Will let the mid shift evaluate with one more set of model runs regarding a potential wind advisory, but the threat of high wind warning threshold being met is low (<10% chance). The final point is temperatures will struggle to reach even January levels by Friday. Anyone with outdoor plans through the weekend should be prepared for a return to winter. .LONG TERM (After 12Z Saturday)...A broad longwave trough will be established throughout the western CONUS Saturday. Utah and southwest Wyoming will have west to northwest synoptic flow with low levels still saturated after a cold front that is expected to push through the day before. With Great Salt Lake temperatures near 3C and 700 mb temperatures near -15C, strong low level lapse rates and instability will also be in place. HRRR and NAM NEST model soundings suggest strongly negative omega, or strong lift through through DGZ. The best lake effect chances are forecast downwind from a roughly 300 degree synoptic wind, which would bring the best chances for snow from northern Salt Lake County into Davis County. Probabilities for high snow accumulations in the urban corridor are low, but snow rates could be sufficient to bring accumulating snow on roads. Temperatures will be some 20-30F cooler than normal throughout southwest Wyoming and Utah to start the weekend. Lake effect snow is likely to taper off during the day, as precipitation transitions more convective throughout southwest Wyoming and northern Utah. With similar conditions through Sunday morning, another push of lake effect snow could occur. The main difference is with wind direction, which will have transitioned more westerly, so snow chances would be best for Davis County. Deterministic models and their ensembles are in good agreement on a ridge building in from the west Monday and Tuesday. That will bring dry conditions each day with temperatures warming, especially Tuesday. The stronger warm air advection by Tuesday will be once the ridge axis tracks through and a digging trough to the west will bring enhanced southwest flow. Ensemble guidance has almost 50% of variance on how fast the trough will push inland. There is high confidence, with all ensemble members bringing enhanced winds Tuesday or Wednesday and precipitation Wednesday and Thursday. The most likely scenario is with enhanced southwest winds Tuesday and precipitation Wednesday through Thursday. && .AVIATION...KSLC...Scattered rain showers will be possible through the evening. There is also a 15% chance of seeing lightning with these showers. Snow is expected to begin around 11Z Friday and last through the morning. MVFR conditions and mountain obscuration are likely throughout most of the TAF period. There is also a 30% chance of seeing IFR conditions due to heavier snow rates. Southerly winds will transition to gusty northwest winds around 16Z when the cold front arrives. Winds could become variable when showers are in the vicinity. CIGS will stay around 6kft after the snow is done. .REST OF UTAH AND SOUTHWEST WYOMING...Light southerly winds will transition to gusty northwest winds Friday morning when a cold front arrives. Scattered rain and snow showers will be possible through the evening before becoming more isolated overnight. There is also a 15% chance of lightning with these showers during the day today. The main band of snow will form Friday morning along and ahead of the cold front. This band will propagate eastward through the morning and early afternoon hours in northern and central Utah. MVFR conditions are likely to occur while it is snowing and there is a 30% chance that IFR conditions will be possible when heavier snow rates occur. Even after the snow is done, CIGS will primarily stay around 6kft for most locations. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Winter Weather Advisory from midnight tonight to noon MDT Saturday for UTZ102>107. Winter Storm Warning from midnight tonight to noon MDT Saturday for UTZ108-110-111. Winter Weather Advisory from midnight tonight to 6 AM MDT Saturday for UTZ112. Winter Weather Advisory from midnight tonight to 9 PM MDT Friday for UTZ113-117. Winter Weather Advisory from 6 AM to 6 PM MDT Friday for UTZ116- 118. WY...None. && $$ Kruse/Wilson/Cecava For more information from NOAA`s National Weather Service visit...
Area Forecast Discussion
National Weather Service Tallahassee FL
947 PM EDT Thu Mar 23 2023 ...New UPDATE... .UPDATE... Issued at 944 PM EDT Thu Mar 23 2023 Overall, forecast is on track with the likelihood of fog very high overnight across the region. There`s been some difference in the guidance tonight favoring dense fog more along the coastal areas from Panama City eastward into Apalachee Bay and then extending northward into Southwestern Georgia. At this time, confidence is sufficient to issue a dense fog advisory for the central portion of the forecast area based on the last several HRRR runs plus the local ECAM guidance. It`s entirely possible spatial expansion of the DF.Y will be necessary overnight. No other changes were made the current forecast. && .NEAR TERM... (Through Friday) Issued at 232 PM EDT Thu Mar 23 2023 The main issue will be development of dense fog overnight tonight, lingering in places until a couple hours after sunrise on Friday morning. Dewpoints have risen into the 60s areawide today, except east of I-75. Underneath dry air aloft, the boundary layer will readily cool off this evening and become saturated. Timing, coverage and density of fog will be similar to last night, making a persistence forecast a good way to go. Will let the evening shift make a final determination on issuing a Dense Fog Advisory, but an advisory seems likely. Lowest confidence for fog will be east of I- 75 and along the Suwannee Valley, while highest confidence will be along and west of a line from Albany to Monticello. Southerly winds will trend stronger on Friday once the nighttime inversion breaks. A warm and somewhat muggy air mass will continue. && .SHORT TERM... (Friday night through Saturday night) Issued at 232 PM EDT Thu Mar 23 2023 An upper level trough is expected to swing through the Tennessee river valley and into the Mid-Atlantic region through Saturday morning. The upper level ridge overhead will predominantly remain in place across much of Florida, which will prevent much of the forcing for ascent to penetrate deep into our region. With the surface front entering our region on Saturday, there will be some instability present with SBCAPE values in the 1500-2000 J/Kg range during the afternoon hours. 0-6km Bulk shear values of 40-50 knots coupled with the aforementioned instability will provide enough of a favorable environment ahead of the front to produce a severe threat. Given these parameters, SPC has maintained a marginal risk of severe weather in our area for Saturday. Overall, temperatures look to remain warm, with highs in the low 80s, and lows in the low to mid 60s. && .LONG TERM... (Sunday through Wednesday) Issued at 232 PM EDT Thu Mar 23 2023 Beyond Saturday`s front, the upper level ridge pushes back into the region. This essentially prevents Saturday`s front from pushing through the region, creating a weak quasi-stationary boundary that is expected to remain across the region through the early portion of the work week. Several mid level disturbances are expected to ride along the northern periphery of the aforementioned upper level ridge. These disturbances coupled with the quasi-stationary surface boundary could provide enough forcing for convection to redevelop along the boundary. The best chances currently look to remain across the northern portion of the forecast area in SE Alabama and SW Georgia. At this time, convection that does develop along this boundary could potentially be strong to severe; however, there are currently no SPC severe risks at this time. && .AVIATION... (00Z TAFS) Issued at 732 PM EDT Thu Mar 23 2023 Mostly clear skies to start the period but low stratus and fog will be moving in around 04Z tonight for TLH and ECP terminals, then quickly spreading further inland, affecting DHN and ABY, then VLD. LIFR vsbys are likely with 1/2SM and 1/4SM affecting all terminals. The fog should begin to start lifting around 14z-16z Friday morning. All sites are expected to be VFR by 17 or 18z tomorrow. && .MARINE... Issued at 232 PM EDT Thu Mar 23 2023 Surface high pressure centered over Bermuda will lead to predominantly southerly flow across all marine zones through Monday ahead of an eventual frontal passage on Tuesday. This front will actually reach the region Saturday; however, it is not expected to clear the region until Tuesday night. This will lead to several days of shower and thunderstorm activity across the marine zones starting Saturday afternoon. Ahead of this front on Saturday, southerly winds will gradually increase to cautionary levels of around 10-15 knots leading to swells of 2-4 feet across the marine zones primarily west of the mouth of the Apalachicola river. Marine zones east of the Apalachicola river are forecast to maintain swells of 2-3 feet through early next week. && .FIRE WEATHER... Issued at 232 PM EDT Thu Mar 23 2023 Southerly winds will increase on Friday. Winds will remain gusty while clocking around southwesterly on Saturday, as a cold front hangs up across central Alabama and Georgia. Increased winds will contribute to high dispersion values, particularly over inland areas. Meanwhile, proximity of the front to our north from Saturday through Monday will bring scattered showers and thunderstorms, some of which could be strong. Otherwise, above normal temperatures will prevail, but the air mass will be somewhat muggy. && .HYDROLOGY... Issued at 232 PM EDT Thu Mar 23 2023 With widespread rainfall totals of less than 0.25 inches expected on Saturday followed by scattered to isolated chances of rainfall forecast through the first half of the work week, there are currently no concerns for flooding at this time. Saturday`s cold front could bring some localized pockets of heavy rain from thunderstorms, but a lack of upper level forcing combined with dry air aloft will lead to reduced amounts of precipitation. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not requested. However, spotters are always encouraged to safely report significant weather conditions when they occur (while following all local, state, and CDC guidelines) by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 58 84 65 81 / 0 0 0 60 Panama City 63 76 67 77 / 10 10 10 60 Dothan 60 82 65 83 / 0 0 20 60 Albany 57 86 64 83 / 0 0 10 60 Valdosta 58 86 62 82 / 0 0 0 50 Cross City 57 83 61 81 / 0 0 0 30 Apalachicola 63 74 66 76 / 0 10 0 50 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...Dense Fog Advisory from 1 AM EDT /midnight CDT/ to 11 AM EDT /10 AM CDT/ Friday for FLZ010>018-026-027-112-114-115-118-127. High Rip Current Risk from Friday afternoon through late Sunday night for FLZ108-112-114-115. GA...Dense Fog Advisory from 1 AM to 11 AM EDT Friday for GAZ142>146- 155>158. AL...Dense Fog Advisory from midnight tonight to 10 AM CDT Friday for ALZ069. GM...Dense Fog Advisory until 11 AM EDT /10 AM CDT/ Friday for GMZ730- 750-752-755. && $$ NEAR TERM...Godsey SHORT TERM...Bunker LONG TERM....Bunker AVIATION...Montgomery MARINE...Bunker FIRE WEATHER...Haner HYDROLOGY...Bunker