Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/06/21

Area Forecast Discussion
National Weather Service Binghamton NY
1041 PM EST Sun Dec 5 2021 .SYNOPSIS... Winds will be increasing tonight with the strongest winds expected in the Finger Lakes region where gusts to 50 mph are possible. A cold front moves through Monday, bringing rain showers tonight into tomorrow morning. Lake effect snow develops late Monday lasting into Tuesday with minor snow accumulation expected in favored areas. && .NEAR TERM /THROUGH MONDAY NIGHT/... 1030 PM Update... Decided to expand the wind advisory to include the Twin Tiers, Otsego and Delaware Counties and also Southern Oneida County. Current thinking is that there may be a few spotty gusts across higher terrain that near advisory criteria in these counties overnight. Already getting some isolated reports of trees and wires down in Broome County and gusts have only been in the 35 to 40 mph range. Tomorrow, with cold FROPA, widespread gusts in the 40 to 50 mph range will be possible. BUFKIT soundings showing momentum transfer over 40 knots in most locations as the mixing layer lifts to near 4K feet behind the front. HRRR is usually a bit overdone with wind gusts, but it is indicating gusts over 50 knots in some spots and widespread 40 to 45 knot gusts just behind the front. There is also some concern further south into the Poconos for tomorrow afternoon and evening, but will hold off from expanding the advisory any further for now, and will let oncoming shifts reevaluate when 0Z model guidance comes in later tonight. 9 PM Update... Temperatures are warming a bit earlier than expected as low level jet starts to punch into the region. Have increased low temperatures overnight as temperatures should continue to warm through the overnight hours and may near 50 degrees in some spots across the Finger Lakes Region and into Syracuse before sunrise. Winds are also increasing, with the wind advisory going into effect in the next hour. So far, a few isolated gusts above 40 mph have been observed, but higher wind gusts will become more widespread and frequent over the next few hours, especially across the higher elevations from Steuben County northeast into Onondaga County. 530 PM Update... Forecast remains mostly on-track at this time. Only change made was to increase cloud cover this evening, as overcast skies have taken over most of the forecast area based on latest satellite and observations. 330 PM Update... The main concern with the near term is the strong winds tonight through tomorrow afternoon. The area of high pressure that brought the quiet weather today is propagating to the east and strengthening. A deepening low in the Great Lakes region moves NE into southern Canada lifting a warm front through the Northeast tonight. A strengthening low level jet develops as the pressure gradient tightens between the strengthening high and the deepening low. 925 to 850 mb winds increase to 45-55 knots across NE PA into the Catskills with 55-65 knots across CNY and the Finger Lakes region. A wind advisory has been posted for most of the Finger Lakes and CNY with downsloping winds helping to mix some of these higher winds down. Forecast soundings do show a strong inversion just above the surface so that will help prevent the strongest winds from mixing down but widespread 40-50 mph wind gusts are still expected with an outside chance of isolated 60 mph wind gusts possible on hill tops and favored downslope areas in the Finger Lakes region. Temperatures increase overnight as 850 mb temps rise to nearly 10C with upper 40s and 50s by sunrise region wide. A cold front then approaches from the west by mid to lake morning Monday with falling temperatures in the afternoon. Rain showers out ahead of the front brings wet conditions to the region most of the morning as well as some fog over the higher terrain of the Poconos and Catskills as low LCLs develop with the moist airmass advecting in ahead of the front. The highest rain totals are expected across the southern Tug Hill as well as south facing slopes of the Catskills and Poconos as upslope flow enhances the precipitation. Winds shift to the W after the cold front moves through. Residual post frontal rain showers transition to snow showers but coverage will be spotty in the afternoon. Lapse rates steepen as CAA takes over with winds still around 35-45 knots at 925 to 850 mb so gusty winds will continue through the afternoon. The wind advisory goes until 7 pm Monday as the winds begin to slacken though gusts to near 40 mph will still be possible through the early Monday evening. As CAA continues at 850 mb and temps fall to around -10c Monday night, lake effect snow develops downwind of Lake Ontario with northern Oneida Co seeing the band. Winds in the lower atmosphere will be shifting through the night from W to NW so the band is expected to be fairly transient and not sitting over one area for too long. Snow accumulations of 1-3 inches with isolated areas of up to 4 inches is possible in northern Oneida and an inch or less further south into the NY thruway corridor. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... 250 pm update... A cool but seasonal air mass will be in place Tuesday and Wednesday with a period lake effect snow on Tuesday, then a broad area of light snow possible late Tue night into Wednesday. A weak cyclonic flow will be in place Tuesday morning embedded within an air mass defined by 850mb temps around -11 to -13 deg C. Low level winds from the west will move over Lakes Erie and Ontario and create lake effect snow possibly into wrn Steuben County, and likely along and north of the NY Thruway. High temperatures on Tuesday will only reach into the lower to mid 30s. Breezy west winds around 10 to 15 mph will make it feel like the lower to mid 20s. A weak high pressure at the surface builds in from the w/sw Tuesday night as the lake effect snow comes to an end Tue evening. The cold air will hold on and some raditional cooling will lead to low temperatures in the upper teens and lower to mid 20s. A developing low pressure system over the southern Atlantic coast will be slowly deepening and lifting to the northeast out to sea on Wednesday. There is still some uncertainty with respect to the northern extent of the light precip shield. The latest GFS still wants to hold onto a broad area of light snow across much of PA and NY. However, much of the other guidance is now leaning toward a relatively dry and cold Wednesday. At this time we have decided to just back off on precipitation chances and still mention a chance of snow. If snow does eventually develop it should be on the light side. Daytime highs on Wed will once again range from the upper 20s to lower 30s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... 250 pm update... Deep low well off the East Coast will allow for the development of a ridge axis along the spine of the Appalachians Wednesday night. This should keep chances for snow to a minimum into Thu morning. Should be another cold night with lows bottoming out in the teens and lower 20s. A low amplitude ridge aloft will arrive on Thursday and re-enforce the surface high moving to the east and keep weather conditions quiet through the day. A pattern change appears to be unfolding Thursday night through Saturday as a deep upper trough looks to dig into the Central Plains which will induce the amplification of an large upper ridge over a good portion of the eastern third of the US. An initial embedded short wave will move quickly across the Northeast Thu night and Friday and produce a period of rain/snow mix into Friday morning, before changing to all rain Friday afternoon. Temperatures start out in the 20s and 30s in the morning and end up in the upper 30s and 40s by the afternoon. As the ridge continues to amplify Friday night into Saturday temperatures will start to rise early Saturday morning back into the mid to upper 40s...and eventually into the lower to mid 50s by Saturday afternoon. During this time there will likely be periods of rain showers...but timing, location and intensity is too difficult to nail down at this time. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... 640 pm update... VFR conditions are expected at all terminals through at least 06z at all terminals. A strengthening low level jet increases the Low Level Wind Shear across all of CNY and NEPA with very strong LLWS developing by 04z. 2k ft winds are around 50 kts from the south shift to SSW. There is uncertainty in the surface winds this evening and overnight due to a strong inversion just above the surface. There is a chance of stronger wind gusts, especially at ITH and SYR tonight if the inversion is any weaker than forecasted. Rain showers will move in around 09z with MVFR cigs. As an approaching cold front nears cigs fall further to fuel alternate and IFR just at AVP/BGM. The front brings a wind shift to west and improved cigs, as well as an end to LLWS. Surface winds from the east and southeast at 10 kts to start increase this evening to 15 gusting to 25 kts. Late tonight the direction shift to south with speeds of 15 to 20 gusting to 25 to 30 kts. Outlook... Monday night through Tuesday...Gusty west winds with lake effect snow showers and resultant intermittent restrictions; mainly NY terminals Monday night and then KSYR-KRME Tuesday. Tuesday night through Wednesday evening...Passing system with snow showers and associated restrictions. Thursday into Thursday Night...Dry with mainly VFR conditions. Friday...Restrictions possible with next disturbance bringing rain and snow showers to the region. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...Wind Advisory until 7 PM EST Monday for PAZ038>040. NY...Wind Advisory until 7 PM EST Monday for NYZ015>018-022>025-036- 037-044>046-055>057. && $$ SYNOPSIS...MDP NEAR TERM...AJG/MPK/MDP SHORT TERM...BJT LONG TERM...BJT AVIATION...TAC
Area Forecast Discussion
National Weather Service Birmingham AL
730 PM CST Sun Dec 5 2021 .UPDATE... Evening Update and 00Z Aviation. && .SHORT TERM... /Updated at 0641 PM CST Sun Dec 05 2021/ Forecast right on track this evening. Positive MUCAPE values and upward motion are hanging north and northwest of the area this evening. The latest model suite continues to hold off convection until right around sunrise in the northwest near Hamilton. The showers/storms will then reach the I-59 corridor by noon and the I-85 corridor by 2-3 pm. It appears that the instability values are slightly better with the latest runs and may have to adjust the Marginal Risk farther into central Alabama overnight. Lower cloud cover will be advertised overnight for a large part of the area instead of the dense fog we have received the past few nights. This is mainly due to increased winds in the lower levels overnight. The one area that may still get the low visibilities will be southeast locations southeast of a line from Troy to Opelika. 75 Previous short-term discussion: /Updated at 1231 PM CST Sun Dec 05 2021/ Through Monday. It`s a "spring" day in December across Central Alabama, with temps now rising into the 70s, and in some cases upper 70s across far southern counties. Convective activity has also developed close to the stalled and now diffuse frontal boundary draped across the Tennessee Valley. Storms have already developed early this afternoon across our northern counties with RAP analysis indicating between 1000-2000 SBCAPE and 0-6km bulk shear values between 20 and 30 knots. Low-level moisture values have increased with dewpoints in the upper 50s to lower 60s. We can expect these scattered showers and storms to continue through the afternoon, decreasing in coverage after sunset. As low-level flow increases overnight tonight the boundary layer should be sufficiently mixed to prevent widespread fog formation, or at the very least much less fog than we`ve seen the past few days. The best chance for fog will be across the far southeast, more removed from the approaching storm system. Attention will then turn to the arrival of the cold front on Monday morning and if we`re able to see any development of severe storms. Following analysis of forecast soundings and model guidance this afternoon, we`re going to include a Marginal Risk of severe storms generally along and north/west of a line from Selma to Clanton to Anniston from 6am to midday on Monday. Marginal amounts of low-level instability with 0-6km shear between 50-60 knots could give us a chance for isolated damaging wind gusts, and we can`t rule out a brief tornado embedded within the line of storms as it moves into our northwest and western counties between 6am and 9am Monday morning. As the line moves farther to the southeast, overall dynamics and shear weaken considerably, and southern and southeast counties are not expected to have a severe weather risk at this time. We certainly can`t rule out some isolated gusty winds at Auburn, Troy, and Eufaula as instability increases during the afternoon, but the best severe weather dynamics will be exiting the area as the line reaches those locations. We`ll continue to watch the latest observation and guidance trends through the evening and overnight hours. 56/GDG .LONG TERM... /Updated at 0138 PM CST Sun Dec 05 2021/ Tuesday through Saturday. The long term period remains complicated and challenging with an active pattern in place across much of the region. Tuesday through Wednesday. A longwave trough will be moving east over Ohio River Valley while a surface cold front will push through the area Monday night. Expansive surface high pressure across the High and Central Plains will build southeast into the region. Fast zonal flow will prevail aloft and will allow a few shortwave disturbances to move over the area Tuesday into Wednesday. The cold front to our south looks to stall late Tuesday and lift north as a warm front into our south- central and southeast counties Wednesday morning while a surface low develops and moves northeast along the front and will enter west-central Georgia Wednesday morning. A longwave trough approach from the northwest during the day Wednesday and this will support another cold front that will move into our northwest counties during the day Wednesday. The result will be lingering showers Tuesday night and Wednesday with the best chances across the southern portion of the area. Rain chances will persist into Wednesday with chances for showers and some thunderstorms across the south and southeast areas that look to reside in the warm sector. A decreased chance of showers is forecast Wednesday night as the cold front pushes back to our southeast. Highs will range from the 50s north to the 60s southeast with lows ranging from in the 30s northwest to the 50s southeast. A light freeze northwest is possible Tuesday morning. Thursday through Friday. Shortwave ridging should move over the area Wednesday night into Thursday while a shortwave trough moves east just to our northwest over the Mid Mississippi River Valley Region. Mid-level ridging will build further over the area Thursday before a shortwave trough moves over the area early on Friday. Mid level ridging becomes firmly established over the Gulf of Mexico with amplified ridging over the area Friday night into Saturday. The result will be a quick end to the cool down we see behind the first cold front as a strong warm advection develops during the day Thursday in concert with the mid and upper level height rises supporting above-normal temperatures as we progress through late week and into the upcoming weekend. An unsettled pattern will emerge with the warmer and more moist airmass in the lower levels with the upper disturbance moving east just to the north of the area. Initially, chance for rain and some storms will be highest south in the more warm and unstable low-level airmass, but we will see isolated shower and some thunderstorm chances as we go from Thursday into Friday. I capped PoPs during this time frame in the 40 percent range to account for uncertainty regarding timing and location of expected convective development. We will experience quite a warming trend with highs ranging from the 60s areawide Thursday to readings ranging from the upper 60s northeast to the mid 70s southwest on Friday. Lows will dramatically moderate with readings from the low 30s northeast to mid 40s south on Thursday followed by readings in the mid 40s east and northeast to values in the upper 50s southeast on Friday. Saturday. A deep, potent longwave trough will approach the region from the west late Saturday. This dynamic system will move over an unstable environment with unseasonably warm temperatures with deep-low level moisture forecast across the area. We will be closely monitoring model trends over the next few days as we begin to enter the range of the shorter-range higher resolution models. There remains notable differences among the currently available global guidance regarding the placement of features and mid-level trough orientations/tilting. We can say at this time the period of time looks stormy to say the least with potential for multiple hazards from severe storms to heavy rainfall. Lows will range from the upper 50s northeast to the mid 60s southwest while high temperatures will range from the low 70s north and northeast to readings in the upper 70s south. Heaviest activity is progged across the northern half of the forecast area but to account for the range and uncertainty, PoPs were capped in the 50-60 percent range. 05 && .AVIATION... 00Z TAF Discussion. All terminals start the period with VFR conditions, but this good flying weather will quickly gain some restrictions overnight. Low level winds increase overnight out of the southwest and near 35kts. This will be below LLWS criteria, but will allow strong isentropic lift on the 290K surface and expect widespread IFR/LIFR ceilings after 06z. Due to slightly increased surface winds, only hit the fog at TOI near sunrise. A cold front moves through the area on Monday with showers and a few storms accompanying it. Winds will be southerly around 10kts ahead of the front and swing around to the northwest and north behind the front 10-20kts. May have to bump winds up slightly Monday afternoon. The winds should start shifting after 18z north and after 21z south. Ceilings and vis improve to MVFR by 15z outside rain areas and hold through the period. Note: AMD NOT SKED is appended at KBHM due to ASOS power loss until further notice. 75 && .FIRE WEATHER... Low clouds and fog may develop overnight, especially across portions of the south and southeast counties and persist into early Monday morning. Low-level moisture content will continue to increase as a cold front approaches from the northwest with widespread rain chances on Monday along with a few thunderstorms. RH values are expected to remain somewhat elevated into next week as a period of unsettled weather could continue to bring periodic rain chances for the next several days. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 58 66 35 53 40 / 20 90 20 30 40 Anniston 60 69 39 56 45 / 10 90 20 40 40 Birmingham 61 67 39 53 44 / 10 90 20 30 40 Tuscaloosa 63 67 40 53 43 / 10 90 20 30 40 Calera 62 68 41 56 45 / 10 90 30 40 40 Auburn 57 70 45 57 50 / 0 80 40 50 60 Montgomery 60 75 47 61 50 / 0 80 40 50 60 Troy 59 75 51 63 52 / 0 80 50 50 60 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$
Area Forecast Discussion
National Weather Service Boston/Norton MA
1052 PM EST Sun Dec 5 2021 .SYNOPSIS... High pressure moves offshore tonight. A warm front lifts north across southern New England Monday morning with a period of showers and isolated thunderstorms possible along with unseasonably mild conditions. A strong cold front sweeps across the region Monday evening which will be accompanied by another period of showers and strong winds Monday afternoon and evening. Dry and cooler than seasonable air works into the region late Monday night and Tuesday. A coastal storm may bring some accumulating snowfall across southern New England Wednesday into Wednesday night, but there is considerable uncertainty. Dry weather returns on Thursday before we become more unsettled late in the week and heading into the weekend with warmer temperatures. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Minor tweaks to the forecast this evening. Tried to update precipitation timing. Thought there was good agreement amongst the near term guidance, especially the HRRR, RAP and 3 km NAM. Used a consensus approach as the basis for changes. Still looking complicated for early Monday morning. Lots of helicity is still projected, but not much instability to tap into it. Will need to monitor any convection early Monday morning. If it gets strong enough, it could develop some rotation. Brought temperatures and dew points in line with observed trends. Still thinking there is a really low risk for some light icing along and north of Route 2 late tonight. Based on latest guidance, this window should only last for 1-2 hours. Still do not have enough confidence for any headlines at this time. It may be a last minute thing. Yet another aspect of the forecast to monitor closely overnight. 645 PM Update... No changes in the latest update other than making minor adjustments to cloud cover to move more in line with current obs. Rest of forecast is unchanged. Previous discussion... High pres moves offshore tonight as potent mid level trough and shortwave moves across the Gt Lakes. A lead shortwave within the SW flow aloft and attendant surface low lifts north along the mid Atlc coast overnight. CAMs all show convective showers developing over the ocean overnight within an area of marginal elevated instability. These showers will move up along the south coast into portions of CT, RI and SE MA toward daybreak. Meanwhile, some spotty light precip may develop late tonight across western MA. Temps tonight will drop to near freezing or a bit below in the interior before slowly rising late tonight. If precip develops early enough, there is a low risk for isolated light freezing rain across portions interior northern MA along route 2 corridor to the east slopes of the Berkshires. However, this risk is quite low and areal coverage would be very limited. The more likely scenario is that temps will be a bit above freezing when precip moves in. Will have to closely monitor this overnight. Otherwise, temps will be rising through the 40s near the coast as SE winds increase. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Monday... Convective showers lift north across SNE during the morning as warm front moves northward. There is marginal elevated instability with HREF indicating MUCAPE of 200-500 J/kg across eastern New Eng so can`t rule out an isolated t-storm across eastern CT, RI and eastern MA during the morning. While, low level shear values are impressive soundings show a rather pronounced low level inversion in the morning which would preclude any stronger convective winds from mixing down to the ground. Warm sector airmass overspreads SNE in the afternoon with temps soaring into the mid 50s higher terrain to lower 60s coastal plain. Expect a period of dry conditions late morning into the afternoon before deeper moisture moves in from the west as strong cold front approaches. A band of showers expected to move into western MA/CT late in the day. Strong winds are other concern for Monday afternoon and evening as 60+ kt low level jet develops across SE New Eng. Given SW flow, mixing will be deeper than what we normally see with a S or SE wind. Forecast soundings show potential for a period of 40-50 mph gusts across SE New Eng late Mon into Mon evening. As a result we issued a wind advisory for Cape/Islands into SE coastal MA and Newport county in RI. Elsewhere, gusts 30-40 mph are possible. Monday night... Cold front moves across SNE during the evening and will be accompanied by a period of widespread showers which move off the coast just after midnight. Turning colder with partial clearing developing overnight with lows upper 20s to mid 30s. The rain may end as a brief period of snow over the higher terrain. Strong pre-frontal SW winds in the evening, gusts 25-40 mph except 40-50 mph SE New Eng coast where wind advisory continues. Post- frontal W winds will be less but it will still be blustery overnight. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Highlights... * Drier with near to cooler than seasonable temperatures on Tuesday. * Potential for accumulating snowfall late Wednesday into Wednesday night. However, it is still too early to hone in on specific amounts and the exact details as there is considerable uncertainty in the track/intensity of the low passing by. Travelers will want to stay tuned to future updates. * Drier on Thursday as a weak high builds in. Unsettled late in the week and heading into the weekend. May start off as snow before it transitions to rain. Seasonable readings on Thursday before we trend warmer than normal on Saturday. Tuesday and Tuesday night... Cyclonic flow in place across much of the US. Fairly weak mid level ridge builds from the eastern Great Lakes/Quebec into northern New England/eastern Canada. A trough digs into the Mid/Upper Mississippi River Valley late on Tuesday. A the surface weak high builds into the region from Quebec/eastern Great Lakes. The high shifts into eastern Canada by late Tuesday night. Dry and quiet weather anticipated across southern New England. Will start off a bit blustery due to a tightened pressure gradient, but will relax as the high gradually builds in. Did bump up high temps slightly due to W/WNW flow aloft at 925 hPa resulting in some downsloping. Went with the 75th percentile of guidance, which is roughly seasonable readings for this time of year, but will be much cooler in comparison to Monday. Highs in the mid/upper 30s across the higher terrain and the low/mid 40s elsewhere. Will see increasing mid/high cloud cover late on Tuesday and especially Tuesday night ahead of the next incoming system. Should remain dry with high pressure still in control, so dialed back the default NBM precipitation chances based on the latest guidance. Think that we will remain dry until a bit later in the day Wednesday. Given the cloud cover will be tough for temps to really plummet, but given the highs position could have some cold air drainage due to a northerly ageostrophic wind component. Low temps in the 20s for most except along the immediate coastline where readings are around 30. Wednesday into early Thursday... Lots of uncertainty during this timeframe there is potential for widespread accumulating snowfall, but really too early to tell given the spread amongst guidance. A positively tilted trough will be situated over the Mid/Upper Mississippi River Valley will dig into the central Great Lakes/Ohio Valley and become neutrally tilted during the afternoon. The trough then lifts into the Mid Atlantic becoming negatively tilted by the evening and through New England by early Thursday. At the surface, low pressure will develop offshore from the VA/NC coast and lift northeastward south of southern New England late on Wednesday. The low lifts offshore to the east/southeast of southern New England by late Wednesday/early Thursday. Still have considerable uncertainty in this timeframe with respect to QPF/snowfall amounts and anticipated impacts. The reason for the uncertainty is due to both the intensity and track of the surface low. Lots of spread amongst guidance with the current trend being the system being weaker and staying further offshore to the S/SE. No point in getting into the specific details at this point as we still need to really hone in on the track of the surface low to determine the impacts. The GFS right now features more of a snow lovers track passing just to the SE of the benchmark, whereas the ECMWF/GEM/NAM give us not much of anything. Within this window have honed in more on the EPS/GEFS ensemble guidance, which also have been showing trend of the low staying further offshore at this point in time. There are 5/30 GEFS members indicating there could be warning level snowfall accumulation assuming a 10-1 SLR. Whereas 14/30 show not much if any snowfall accumulation. The EPS features no members showing warning level accumulations with the 10-1 SLR and the vast majority showing not much if any accumulations. Both EPS/GEFS members have been trending in the wrong direction for snow lovers with probabilities of amounts AOA 1 or 3 inches. Given the uncertainty have stuck with the NBM guidance at this point in time and nudged down WPC precip slightly. Given we are still talking 4- 4.5 days out will need to see if this trend continues and get better consensus amongst guidance. If folks have travel plans they will want to stay tuned to future updates. Appears at this time given the progressive nature of the system that if there were impacts to travel it would be more for the late afternoon/evening commute. Given the progressive nature of the system precip should be over with before daybreak. High temperatures on Wednesday will be cooler than seasonable with readings generally in the 30s, but the Cape/Islands could see readings in the low 40s. Low temperatures heading into Thursday morning would be fairly widespread 20s with low 30s across the Cape/Islands. Thursday... Weak high builds over southern New England in wake of the exiting system. Will have cool NW/N flow aloft, which advects colder air into the region. High temps will be below normal for this time of year with fairly widespread 30 degree readings. Some uncertainty with respect to the temps heading into Friday morning. Models spread out on how strong a warm air advection we get ahead of the next trough lifting in. Have stuck with NBM, but not out of the question we are too cold at the moment give some models 925 hPa temps. Right now lows in the 20s across the interior and low 30s for the Cape/Islands. Friday and Saturday... Given the uncertainty earlier in the forecast, have not put much emphasis this far out. Does appear that we have shortwaves/troughs lifting into the region. This could bring us some light snow/flurries heading into Friday. Does appear at the moment that based on temp profiles would see precip change over to rain for Friday and also for Saturday. Should be much warmer than normal during this timeframe with pretty good consensus in a warm up. High temps on Friday in the 40s with some low 50s along the south coast. For Saturday, right now have widespread highs in the 50s. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight...High confidence in trends, but moderate in specific timing. VFR to start with conditions gradually deteriorating to MVFR/IFR around 08-12Z as ceilings lower. Will see scattered showers moving in during this timeframe as well. Coverage still expected to be the greatest near the south coast. Have also added a VCTS mention to the Cape Cod/Island terminals as think this is where the risk is highest heading into the AM push. Low risk for isolated freezing rain in northern MA along route 2 corridor to the east slopes of the Berkshires. Increasing SE wind Cape/Islands late tonight. Not out of the question there may be some 20-25 kt gusts, but have added LLWS mention per RAP BUFKIT soundings until mixing appears more likely within the boundary layer. Monday...Moderate confidence. Mix of MVFR/IFR conditions. Showers lifting north across SNE in the morning with isolated thunder possible in RI and eastern MA. Have added the thunder mention to Cape/Islands terminals, but may be needed for PVD/BED/BOS. Have held off on PVD/BED/BOS for now as confidence is lower in how widespread the coverage will be. A period of dry weather in the afternoon with another round of showers moving into western MA late in the day. Increasing S/SW winds with gusts 25-35 kt developing, strongest SE New Eng. Areas of LLWS in the afternoon across Cape/Islands. Monday night...Moderate confidence. MVFR with areas of IFR as showers move across the region during the evening, then improving to VFR from west to east. Showers may end as snow showers over the higher terrain. A period of SW gusts to 40 kt possible in the evening over Cape/Islands and adjacent SE MA, with 25-35 kt gusts elsewhere, diminishing overnight. KBOS TAF...High confidence in trends. Moderate confidence in timing and exact details. Not out of question there is a thunderstorm or two roughly in the 11-15Z window, but confidence too low to add in the TAF at the moment. KBDL TAF...High confidence in trends. Moderate confidence in timing and exact details. Outlook /Tuesday through Friday/... Tuesday: VFR. Breezy. Tuesday Night: VFR. Wednesday: Mainly VFR, with local IFR possible. Chance SN, RA likely. Wednesday Night: Mainly VFR, with areas MVFR possible. Breezy. Chance SN. Thursday: VFR. Breezy. Thursday Night: VFR. Chance SN. Friday: Mainly VFR, with areas MVFR possible. Chance SN, slight chance RA. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Increasing SE winds later tonight then a period of SW gusts to 35- 40+ kt developing in the afternoon/evening as 60 kt low level jet develops. Gale warnings continue on all waters. Winds shift to W Mon night behind the cold front with gusts gradually diminishing to 25- 35 kt. Scattered showers with an isolated t-storm possible late tonight and Mon morning, then another period of showers Mon night, clearing late. Outlook /Tuesday through Friday/... Tuesday: Low risk for Small Craft Advisory winds with local gusts up to 30 kt. Areas of rough seas. Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Rain likely. Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Rain likely, chance of snow. Thursday: Winds less than 25 kt. Rough seas up to 10 ft. Slight chance of rain, slight chance of snow. Thursday Night: Winds less than 25 kt. Areas of rough seas. Slight chance of rain, slight chance of snow. Friday: Winds less than 25 kt. Areas of rough seas. Chance of rain. && .TIDES/COASTAL FLOODING... The following are the astronomical heights of upcoming high tides and do not include surge values from local wind/weather conditions. Boston12.0 feet - 1214 PM Monday Nantucket4.4 feet - 120 PM Monday Providence 5.8 feet - 917 AM Monday Given southerly winds, not expecting much surge on the east coast with tidal anomalies less than 0.5 ft. Worst case along the east coast is minor splash over for most vulnerable shoreline roads. Along the south coast, a surge of 0.5-1 ft is possible but this will likely occur after the high tide so not expecting any impact on the south coast for the Monday morning high tide. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Wind Advisory from 1 PM Monday to 1 AM EST Tuesday for MAZ019>024. RI...Wind Advisory from 1 PM Monday to 1 AM EST Tuesday for RIZ007- 008. MARINE...Gale Warning from 10 AM Monday to 7 AM EST Tuesday for ANZ231>235-237-250-251-254>256. Gale Warning from 10 AM Monday to 1 AM EST Tuesday for ANZ230- 236. && $$ SYNOPSIS...KJC/BL NEAR TERM...Belk/KJC/BL SHORT TERM...KJC LONG TERM...BL AVIATION...Belk/KJC/BL MARINE...KJC/BL TIDES/COASTAL FLOODING...Staff
Area Forecast Discussion
National Weather Service Grand Forks ND
955 PM CST Sun Dec 5 2021 .UPDATE... Issued at 945 PM CST Sun Dec 5 2021 Lengthened the blizzard warning to 3am with gusts up to 40mph expected to persist per HRRRTL and also added Wilkin and Richland county to the warning per conditions and webcams. Went with the wind chill advisory in the Devils Lake basin ending the warning as winds and visibility have improved there. Temps continue to plunge with near zero in the north now and teens in the south. These colder conditions really help snow flakes fragment and loft more easily reducing visibilities. UPDATE Issued at 622 PM CST Sun Dec 5 2021 Upgraded to blizzard warning with white out conditions reported and seen on webcams across the northern valley behind the cold front which is dropping temperatures a quick 10 degrees into the teens. These lower temps along with the northerly wind gusts of 40 to 50 mph measured will continue blow the snow more easily than the temps in the 20s we saw earlier today. Conditions are obviously much worse in open country than they are in town or within shelterbelts. HRRR maintains winds through about midnight and then lessening. && .SHORT TERM...(This evening through Monday night) Issued at 256 PM CST Sun Dec 5 2021 Low pressure at 20z east of Fargo and just southwest of Detroit Lakes moving east. Upper low just east of Grand Forks. There will continue to be light snow around the upper low as it moves east with light snow ending in RRV by mid evening and in the far east after midnight. Seeing winds turning north in the RRV and E ND at mid aftn with gusts into the 25-30 kt range. Question remains blizzard potential. Blowing snow model has 60 percent chance of vsbys to 1/2SM in the mid RRV 00z-04z. Max winds low level reach 40 kts for mixing per soundings but as 930 mb and below cool there remains a steep inversion and warm layer up thru 850 mb this evening and the 850 mb layer doesnt cool until overnight. But by then the mixed layer winds are not as strong. So if there is a time when the colder air first comes in and low level winds are 40 kts is when blizzard conditions are most likely and this would look to be 04-05z. So a 1-3 hour period of widespread vsbys 1/4sm or less seem at least possible (50 percent chance). At the time of this snow is not expected to be falling. However will need to watch arctic front as some light snow is progged with it into central ND and there is light snow upstream near Brandon and thru SW Manitoba. Net result of all this is the office consensus to continue winter storm warning. Main snow is done, but impacts from still falling snow combined with wind warrants keeping warning thru valid time of 06z. If conditions are worse and more widespread, then blizzard warnings can be issued (40 percent chance of that happening). Very cold overnight and wind chills drop into the -25 to -35F range by 09z-14z in NE ND, nrn RRV. Wind chill advisories likely needed but will hold until this storm event is done. Cold day Monday with highs single digits above. .LONG TERM...(Tuesday through Sunday) Issued at 256 PM CST Sun Dec 5 2021 .LONG TERM...(Tuesday through Saturday) Overview... Aside from a chance for light snow in the north on Thursday and in the south on Friday, impactful weather is not anticipated throughout the remainder of the long term period. Otherwise, a gradual warming trend will be the story for the week ahead into next weekend. Discussion... Synoptically, northwesterly flow aloft looks to continue through midweek. At the surface, this flow pattern will be accompanied by generally quiet weather and a gradual warming trend. While Tuesday is expected to remain cold with highs in the teens, with southerly return flow inching into the region, warmer, near normal, temperatures are anticipated moving into Wednesday. A quick moving shortwave and its attendant cold front may introduce a glancing blow of light snow to portions of the northern forecast area on Thursday. Ensemble guidance is in varied agreement on this solution and as a result, we are looking at a roughly 20-30% chance for some light snow with this system. Following this system, ensemble guidance is picking up on an upper trough that looks to traverse the central Plains. While main impacts should remain to the south of the forecast area, some light snow impacts cannot be ruled out for those south of the I-94 corridor on Friday. However, confidence in the exact track of this trough and its precipitation impacts is low at this time. As the main upper trough exits the region, zonal flow looks to take its place. This will lead to yet another quiet pattern with varying degrees of gradual warming moving into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 622 PM CST Sun Dec 5 2021 Winter storm creating IFR or MVFR conditions across the area tonight with north winds gusting over 40kts in the valley. Will see conditions improve overnight into Monday morning. VFR expected tomorrow daytime. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Winter Weather Advisory until 3 AM CST Monday for NDZ038-049-052. Blizzard Warning until 3 AM CST Monday for NDZ007-008-016-027- 029-030-039-053-054. Wind Chill Advisory until 10 AM CST Monday for NDZ006-014-015- 024-026-028. MN...Winter Weather Advisory until 3 AM CST Monday for MNZ030-031-040. Winter Storm Warning until 3 AM CST Monday for MNZ005-006-008- 009-013>017-022>024-027-028-032. Blizzard Warning until 3 AM CST Monday for MNZ001>004-007-029. $$ UPDATE...JK SHORT TERM...Riddle LONG TERM...Rick AVIATION...JK
National Weather Service Jackson KY
1105 PM EST Sun Dec 5 2021 .UPDATE... Issued at 1105 PM EST SUN DEC 5 2021 The first of the convection is entering the JKL CWA - targeting our northwest counties initially with the steadier rains and some embedded thunderstorms. Some training of the cells will be a concern in this area as well despite the dry conditions out there. Have updated the forecast to beef up the PoPs and thunder chances. The current obs and trends for the T/Td were also included with the update. In addition, a fresh set of zones and SAFs were issued. UPDATE Issued at 755 PM EST SUN DEC 5 2021 00Z sfc analysis shows high pressure slipping out of the area to the southeast ahead of an approaching cold front. The fairly tight pressure gradient between these two features is supporting breezy south to southwest winds throughout the area - at 10 to 15 mph with some occasional gusts to 25 mph or higher around. These winds are keeping the boundary layer well mixed with temperatures mainly in the upper 50s to lower 60s while dewpoints are running in the upper 40s to lower 50s. The front is pushing some broken showers and even a few thunderstorms out ahead of it - in the south - the strongest storms are mainly affecting locations well southwest of the JKL CWA - but will need to be watched. The forecast is on track with the approaching front and convection arriving into the CWA later tonight. Accordingly, have mainly updated the grids to incorporate the latest obs and trends for the T/Td ones. The sky cover and PoPs were also adjusted into the night per the current conditions and latest consensus CAMs guidance. These updates have been sent to the NDFD and web servers. && .SHORT TERM...(This evening through Monday night) Issued at 455 PM EST SUN DEC 5 2021 Late this afternoon, an upper level ridge was centered southeast of Bermuda with another upper level ridge centered over portions of the eastern Pacific and extended into the western Conus. Meanwhile, a broad trough extended from central and eastern Canada south into the central Conus. A shortwave trough was moving across the southern Appalachian/northeast GA western SC area while another shortwave trough was working from OK into AR. Further north a much more significant upper level low was centered in the vicinity of far western Ontario/north central MN with an associated shortwave trough south into the northern to central Plains regions. Further upstream, another shortwave trough digging southeast extended from the Hudson Bay region southwest across Manitoba an into Saskatchewan. At the sfc, high pressure was centered over the northeast Conus while a stationary boundary extended west across southern NC, before turning north and becoming a warm front and crossing the crest of the Appalachians to the Big Sandy region and then turning west near the OH River and then west northwest to a triple point sfc low pressure in the MS Valley while the parent sfc low was centered over MN. Warm air advection behind the north and northeastward lifting warm front and in advance of the area of low pressure to the west and northwest, combined with the recent dryness and downslope southerly to southeast component to the flow, has led to breaks in the low level clouds and very mild temperatures for early December. Temperatures outside of the highest elevations ranged through the 60s as of 4 PM. This evening and tonight, the shortwave trough is expected to pass south and east of the area, while the shortwave southwest of the region in the OK/AR is expected to track toward the OH and TN Valley regions. This system will begin to interact with the upper level low that is expected to weaken to an open wave and track into the Great Lakes and the associated shortwave trough approaching the MS River and lower OH Valley. This upper level shortwave trough will continue east during the day on Monday and cross the OH Valley region as well as the Commonwealth and rotate into and across the Northeast and into Canada through Monday night as an upper level low closes off over Quebec. This will result in a broad trough extending from Canada into portions of the Central to eastern Conus as the end of the period. Meanwhile, at the sfc, the warm front will continue lifting north and east of eastern KY this evening as the main sfc low tracks into the western Great Lakes. This sfc low will continue into the northern Great Lakes late tonight with the trailing cold front moving across western and into central portions of the Commonwealth through dawn on Sunday. This sfc low will track into Quebec through late Monday and into the Maritimes through the end of the period. Sfc high pressure will build east from the Plains and MS Valley region and into the OH Valley behind the front to end the period. The pressure gradient across the region will increase this evening and into tonight ahead of the approaching front and lead to 850 mb winds in the 45 to 55KT range or so late tonight through early Monday. This will lead to increased shear as well as the potential to transfer some of this momentum to the sfc at least at times in some locations in advance of the front itself and an anticipated convective line. Instability will be limited from late this evening into the overnight hours, but some thunder cannot be ruled out in this low end CAPE somewhat high shear environment. SPC has highlighted areas of the western edge of the CWA in a Marginal risk for severe thunderstorms, where moisture and instability should be greatest combined with a bit greater shear. Given the strength of the LLJ and forcing from the approaching shortwave trough, thunder cannot be ruled out over the entire area late tonight, though chances appear best across the western half of the area prior to dawn. There is a bit of uncertainty as to just how quickly the convective line will move east as well with some run to run and model to model variability among the CAMS. The HRRR also has at times had a tendency to move the line a bit too slowly downstream. Given all of this, thunder chances were included as far east as all of Pike County late. The front and any remaining convective line should continue east and southeast during the first couple hours after sunrise on Monday with some needed showers continuing for a few hours behind the front. Drier air will begin to move into the region by midday into the afternoon with chances for precipitation near the VA border ending around or just after sunset on Monday evening. High pressure building in will lead to clearing skies on Monday afternoon to Monday evening with mainly just passing high clouds on Monday night. This will set the stage for seasonably colder temperatures on Monday night compared to the mild lows will experience tonight. Moisture and forcing appears best across the northwest half of the area and average QPF greatest there, nearing on inch if not more, while, areas further southeast with the downslope component to overcome should average in the 0.4 to 0.8 tenths range. .LONG TERM...(Tuesday through Sunday) Issued at 511 PM EST SUN DEC 5 2021 We start the extended in the middle of a very brief break from any precipitation Tuesday, but an active pattern quickly resumes as we head further into the middle of the week. The upper level pattern Tuesday mainly consists of broad troughing across much of the CONUS, with a few shortwaves embedded within the flow. Of particular interest to our area, is one shortwave coming up from the Southern Plains through the Lower Mississippi Valley, as well as a northern stream wave coming down from the Northern Plains, and the potential interaction between the two and how that effects the details of a developing surface low. Though the overall pattern is fairly well agreed upon, the differences that do exist over the smaller details are contributing to continuing uncertainty around the specifics of potential impacts felt by our area. Guidance has trended towards a more suppressed system that stays further to our south, leading to colder temps and less precip falling in our area Tuesday night and Wednesday. The cooler trend has increased confidence in at least some of this precip falling as snow for portions of our area Tuesday night. However, the uncertainty in the finer details, such as the low intensity and exact track, lends to less confidence in precip amounts and the location of where rain ends up transitioning to snow. While the exact amounts are still subject to further refinement, generally expect that light accumulations are possible. Temperatures at the beginning of the period average normal, with highs Tuesday and Wednesday in the upper 30s to low 40s, and lows in the mid 20s to around 30. We see a breif dry period Wednesday night through most of Thursday as modest ridging passes aloft. Rain chances return late Thursday into Friday as more shortwave energy approaches the region, though exact timing is still yet to be completely worked out. Things turn potentially more active over the weekend as a sharper trough supports a more potent system that pushes a strong cold front through the region. With abundant moisture being brought in ahead of the front (PWATS more that 2 standard deviations above climatological norms), there exists the potential for some within the region to see some heavier rain with this front. Recent forecast soundings also show at least limited instability and plenty of shear. However this system is still far out in the forecast period, and specifics can change as finer details like timing and intensity become better resolved with time, but trends will continue to be monitored. Under increasing southerly to southwesterly flow, temperatures Thursday and beyond see a warming trend, ending up well above normal by the weekend, before potentially dropping for the end of the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 710 PM EST SUN DEC 5 2021 Aside from some upper end MVFR ceilings at LOZ - VFR prevailed throughout the CWA at the start of the period. VFR conditions are expected to be the rule through around 06Z for most places. By that point though, moisture, as well as increasing and lowering clouds and some convection, will move into eastern Kentucky in advance of a well defined cold front. This front will bring showers and perhaps a brief convective line at the boundary along with potential for some thunder. This is most probable during the 09 to 14Z timeframe as the front progresses through the forecast area. An eventual deterioration to MVFR ceilings will follow with this - possibly some MVFR VIS along with brief IFR conditions accompanying the convection right along front, too. Locations south and east of JKL may remain VFR until around 12Z due to a downslope component to the flow. South winds averaging 10 kts will continue through the evening and increase into the 10 to 15 kt range from west to east between 02 and 07Z. As the front passes, between about 11 and 16Z, look for the winds to become more westerly. A few gusts into the 20 to 30 kt range, at least at times, appear probable during the 02 to 15Z timeframe as the front approaches and crosses the area. In addition, winds off the surface will become much stronger this evening, with some low level wind shear likely transitioning from west to east between 02 and 14Z. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...JP LONG TERM...HAS AVIATION...JP/GREIF
Area Forecast Discussion
National Weather Service Lake Charles LA
858 PM CST Sun Dec 5 2021 .UPDATE... Evening update. && .DISCUSSION... Some low-level clouds are currently moving through the area this evening. Winds are expected to be higher tonight which should keep the chances for fog formation low. However, some patchy fog will be possible. Therefore, patchy fog was added to the forecast for the overnight hours into the morning as the front starts to approach the area. Precipitation chances in the forecast appear to be on track so far, with the 00Z HRRR showing the bulk of the precipitation starting to enter the area in the morning hours. Precipitation chances will continue through the day. Showers and thunderstorms will be expected. SPC has our area in a Marginal Risk of severe weather as the front makes it way through the area. 55 && .PREV DISCUSSION... /issued 528 PM CST Sun Dec 5 2021/ DISCUSSION... For the 06/00Z TAF Issuance. AVIATION... Tighter pressure gradient between low pressure over the Plains and high pressure off to the east will allow for stronger southerly flow in the boundary layer. Thus, restrictions from fog is not anticipated as it was the past few nights. Instead low clouds with MVFR to IFR ceilings with developing showers will be the issue overnight. On Monday, a cold front will move across the forecast area with showers and thunderstorms developing ahead of it. In general, MVFR conditions are expected during the day. However, worse conditions will be possible if any of the stronger convection passes over a terminal. Rua PREV DISCUSSION... /issued 404 PM CST Sun Dec 5 2021/ DISCUSSION... SHORT TERM [Rest of today through Tuesday Night]... Tonight going into tomorrow will be the highlight of this forecast as a cold front slides into our CWA. While the PW from this mornings sounding was not as high as yesterday, its still close to the 75th percentile. In addition to that, PWs ahead of the front range from 1.4 to 1.8, to which the lower end of that range is at the 90th percentile. 24H QPF totals will be around a half of an inch to two inches, with higher amounts possible. Despite the fact that we have been on the dry side as of recent, flash flooding is not out of the realm of possibility. We remain in SPCs marginal risk for severe thunderstorms which was expanded to cover the entire CWA. The main threat will be damaging wind gusts however hail and isolated tornadoes cannot be ruled out. Instability is not all that impressive but there is sufficient low and deep layer shear to support modest updraft organization. With this front moving thru over the Monday, temperatures will be similar to what we are experiencing today. Monday night will be nearly 15 to 20 degrees cooler with temps in the 40s to lower 50s. Tuesday will be cooler with temps struggling to make it into the mid 60s at the most with overcast skies and scattered chances of showers and storms. 87 LONG TERM [Wednesday through Sunday]... A near zonal flow will develop aloft in wake of Tuesday`s departing shortwave...however some lingering convection should be continuing over lower Acadiana at the beginning of the day on Wednesday where better lift/moisture will be last to depart as well as its proximity to the old frontal boundary meandering over the nrn Gulf. The boundary is progged to begin lifting back nwd as a warm front on Thursday, with srly flow ushering in a moderation of temps as well as the potential for a few showers as another weak impulse crosses the region. Increasing srly flow through the column will allow deeper moisture to pool over the forecast area on Friday...however building heights/warmer air aloft will effectively cap the atmosphere, keeping rain chances fairly slim through the day. Temps are progged to warm to around 80, with lower 80s possible in places...15-20 degrees above seasonal norms and approaching records for the date. The weekend shows the approach/passage of a more significant shortwave aloft and an associated sfc front which will provide the basis for additional convection/higher rain chances. Forecast soundings are showing some potential for severe weather around the time of the frontal passage...this will be monitored in the days ahead. Precip should be ending from west to east by the end of the period. 25 MARINE... Onshore flow will begin to tick upwards this afternoon and continue a steady trend upwards tonight before weakening. Rain chances will begin in earnest Monday morning and ratchet up during the day as a cold front approaches in the late afternoon and evening. The front will stall Tuesday morning and meander about over the waters before washing early Thursday morning. Winds and seas will remain elevated during this first half of the week. && .PRELIMINARY POINT TEMPS/POPS... AEX 62 71 43 57 / 50 100 20 20 LCH 65 75 48 61 / 40 100 40 30 LFT 65 78 51 64 / 30 90 40 40 BPT 65 76 49 63 / 40 90 30 20 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...Small Craft Exercise Caution through Monday morning for GMZ450- 452-455-470-472-475. && $$
Area Forecast Discussion
National Weather Service New Orleans LA
554 PM CST Sun Dec 5 2021 .AVIATION...Valid through 06z Tuesday... Challenging forecast with this TAF cycle. First challenge is determining extent of fog and low cigs tonight into Monday morning. Still ample low level moisture in place, but low level winds will be a bit stronger than the last few nights. That being said, would only take a brief period of very light to calm winds for vis and cig to drop like a rock. Have gone ahead and kept LIFR/VLIFR conditions to TEMPO groups near daybreak for this issuance. Once any fog dissipates, the next challenge is timing the frontal passage. Have generally gone with a consensus of the short range guidance as the CAMs are in fairly good agreement within a couple hours of each other for timing. Squall line should affect northwestern terminals around midday and progress southeastward through the afternoon. As the squall like progresses southeastward, expect it to lose some of its push, so gust potential at the southeastern terminals is a bit lower than the northwestern terminals. With the front expected to stall near the coast, scattered showers could remain in the area even after 00z Tuesday. && .PREV DISCUSSION... /issued 356 PM CST Sun Dec 5 2021/ SHORT TERM (This evening through Tuesday Night)... Starting off with late this afternoon/early evening, overall is looking rather pleasant with only some patchy low-level cu or stratocu areawide bringing partly to mostly cloudy skies. Current state of the atmosphere reveals steady and persistent onshore moist return flow in progress with subtle veering low-level/near surface winds. We will continue to see low-level flow slowly increase throughout the night tonight in response to a strengthening low-level jet/attendant tightening height gradient to nearby or just to our northwest. This is in association with a deepening positive-tilt shortwave trough axis and attendant surface low/cold front diving east and southeast into the Great Lakes/MS valley region overnight tonight that we will talk more about shortly. But meanwhile here, the first item to focus on will be the potential for fog once again later tonight and into early Monday. There are subtle environmental differences, including a slight increase in low-level winds mentioned before that could throw a wrench in either the expected coverage and/or density owing to a lower-confidence forecast. Combing through a large suite of model guidance this afternoon shows a bit of a spread, but enough to build a consensus especially after closely analyzing select short-range model soundings. The previous mornings fog processes have generally been a mixed/conglomerate radiative/advection process, with developmental emphasis moreso near areas near better moisture sources with air/water temperature differential (particularly near and within northern portions of the MS river where the thickest fog has been maintained now for the past several days). Closely looking at soundings show the increase in winds roughly from around 150-200m AGL and above, but with only very little increase below and to the surface. This will be important as winds are technically forecast to be just a few MPH higher than the previous mornings, but the question is how much will this harm the production of widespread, dense fog. Advertising for now that the potential of widespread dense fog will be lower than the previous few days, but not entirely out of the question especially anywhere where winds can shut down enough to aid in a more radiative fog development process. Otherwise, guidance also suggests shallow surface fog to maintain or increase along coastal Terrebonne parish, transporting inland given favorable wind advection regime. Because of this, will mention the greater potential for another round of fog for western areas, or generally along/west of I-55, with less potential east. Due to a lower confidence forecast, will hold off on any dense fog highlights for now, and will refer to subsequent forecast shifts to re-analyze model guidance should the threat increase later this evening. Any fog around may linger, through mid-morning on Monday, but should be quick to dissipate as surface winds continue to increase out of the west/southwest. From here, the next focus as mentioned earlier will be on an approaching cold front and associated line of showers and storms entering our NW CWA areas late AM/early PM. Thumbing through individual HREF members shows somewhat ok confidence in regards to speed/timing with the main line, with the spread being around 50 miles or so on average from the slowest to fastest member. HRRR creeps this line in northwestern areas around noon as a few members have it in an hour or two earlier. The Storm Prediction Center does highlight a large portion of our CWA in a Marginal Risk for severe weather, highlighting particularly on low TOR and Wind probs. Taking a closer look at available shear with this line looking at the synoptic hour HRRR runs, we see a transitioning low-level vertical wind profile as this line progresses south and east. Early monday morning, surface winds begin more southerly (or from the SSW) which aids in a slight bump up in low-level 0-1/0-3 SRH of around 100-200m2/s2. But this is well ahead of the front with the line of showers then over northern LA/central MS. As the shortwave trough/attendant surface low continues to eject east into the Northeast, the aforementioned low-level jet discussed earlier flattens out and deamplifies with time. Surface winds transition more out of the southwest to eventual west-southwest which reduces necessary low- level shear/curvature to support the potential for rotating updrafts. Meaning, SRH lowers by the time the line enters out CWA likely becoming cold-pool dominant at some point, reducing the tornado risk. Having said all of that, storms within the line will need to be monitored across far northwestern areas, but the threat will likely diminish as the line sags south into central areas early afternoon. HRRR Neural Network Convective Hazard probabilities also illustrate this exact process with lowering probabilities as the line swings southeast aiding in confidence in the lowering TOR risk. Damaging winds may be the only (albeit still low) risk, with the potential for some sub-severe wind gusts along the line, particularly for northern and western areas of the CWA. We do see some very subtle phasing/matching of the weak subtropical jet lining up with the axis of the deeper shortwave trough axis to our north, but with max H5 winds in the 45-55kt range. Low-level winds diminish as mentioned earlier which reduces the threat even more to around 20-25kt meaning even where downward transfer occurs, even nearby the strongest updraft, we should only see generally sub-severe wind gusts in the 35-45mph range, maybe isolated higher but will remain also a minimal risk. Will just have to monitor for small bowing segments or for any cells that could initiate ahead/merge with the line over southern/southwestern MS and east of I-55 Monday afternoon; but the threat should diminish thereafter. Should mention the threat for hail is non-zero, with H5 temperatures in the -12 to -14C range, but should updrafts ascend high enough to tap into some of the colder air aloft, could see some isolated small hail collocated within any stronger storm. The line steadily diminishes as cold pooling overtakes the leading updraft ingest down to more of a line of showers across coastal LA and MS Monday afternoon/evening, with the stratiform precip shield diminishing with time. We should see the front settle into the northern Gulf Monday evening, eventually seeing most precipitation diminishing at that point only with perhaps some isolated/scattered showers around. Monday evening/night, a close upper-low over northern Mexico finally drifts east and weakens/stretches some, but provides enough downstream divergence coupled with lingering surface frontogenetic to re-enhance spotty shower coverage, mainly after midnight Monday night into Tuesday morning. Tuesday offers a bit of difficulty in the temperature forecast, but with persistent post-frontal moisture advection leading to mostly cloudy to even overcast skies, with some (but enough) ongoing low-level to near surface CAA, have decided to lean on the lower end of the very wide ensemble spread for MaxT`s. This places many areas just around 2-3 degrees below deterministic values (upper 50`s north/60`s south). Be aware that this could be even cooler with thicker clouds or post-frontal showers, OR could lead in the wrong direction should CAA relax and/or sunshine find it`s way to the surface but will target temperatures below guidance for now given the setup at hand. What is left of the weakening shortwave impulse pushes east late Tuesday going into Tuesday night, leading to a drying trend but we may likely be stuck in low-level post- frontal clouds. LONG TERM (Wednesday through Sunday)... Clouds try to break up going into the daytime on Wednesday, with a steady return flow setting back up over the northern Gulf coast. This will lead to a warming trend starting mid-week, going into the rest of the week ahead. We see a weak/broad trough swing through Wednesday during the day, which tries to squeeze out some showers near our area, but better coverage will exist with surface cyclogenesis/frontogenesis over the mid-Atlantic states. We stay in this relatively moist environment thereafter as temperatures continue to build. Kept a warmer bias going on Thursday and Friday, placing areas into the 80`s and overall pleasant. Late this week, large-scale ridging remains in control of the Gulf of Mexico, meanwhile deeper longwave troughing builds into the intermountan west. Trends with the GFS keeps this large NE to SW oriented positive tilt axis drifting east into the MS valley region late Saturday into Sunday, with some sharper curvature at the base of the trough pulling into the Arklatex region. The GFS and ECMWF solutions are split on the amplitude/intensity of the "tip end" shortwave axis which has everything to do with the potential for severe weather downstream. The ECMWF suggests higher amplitude troughing to promote enough downstream divergence along the front to produce surface cyclogenesis, and should this happen this could help to back surface winds/increase shear ahead of what could be a quick-moving line of showers/storms. However, the GFS suggests less overall amplitude with the mid-level trough that never helps to deepen a surface low leading to less surface/low level backing in a primarily unidirectional vertical wind profile, limiting severe weather potential. Overall, many doubts here but will advertise the next chance of rain with this front at some point this upcoming weekend, with details including any severe weather potential forthcoming in the next several days. KLG MARINE... Onshore southerly flow will continue to build later this evening through tonight and during the day on Monday, with exercise caution headlines in effect later this evening, tonight and through Monday. Some extension or upgrade to advisory criteria will be possible, but should remain generally in the 15-20kt range. The next front will swing through later Monday afternoon/evening before stalling over the northern Gulf. The front will return north with onshore flow persisting through the middle to later parts of the week. Additionally, southerly fetch increases as surface southerly winds build with increasing wave heights before the next cold front swings through following into next weekend. && .PRELIMINARY POINT TEMPS/POPS... MCB 63 72 46 57 / 20 100 50 40 BTR 63 76 49 61 / 20 100 50 40 ASD 61 78 49 64 / 10 80 50 50 MSY 65 79 56 66 / 10 70 50 50 GPT 62 76 50 61 / 0 70 50 40 PQL 61 76 49 63 / 0 60 50 40 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$ Aviation...95/DM Prev Discussion...KLG
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
922 PM CST Sun Dec 5 2021 .UPDATE... Issued at 922 PM CST Sun Dec 5 2021 The forecast remains on track with the main concern being the strong winds beginning late tonight and through the day on Monday. Current observations show that most of the CWA has dried behind a cold front which is sitting along a line from Bloomington, IL to Valparaiso, IN. Along the front, is a line of lingering showers which will be departing the area with the front by midnight. While most of the area will remain precipitation free tonight there is a chance that the residual lower atmosphere moisture and steepening low-level lapse rates could generate a few flurries for areas north of I-80 through daybreak. Behind the front, winds have veered to the west-northwest and have started to gust into the lower 20 mph range in a few locations. Winds will continue to increase in strength overnight as a tightening pressure gradient and the afore mentioned lapse rates allow 40 to 45 mph gusts to be transferred to the surface. These strong winds will persist through Monday afternoon before they slowly begin to ease from west to east across the CWA. Temperatures on Monday will be cold with highs struggling to make it above freezing in the upper 20s and lower 30s. Even colder temperatures are expected Monday night with lows dipping into the single digits and lower teens. Yack && .SHORT TERM... Issued at 310 PM CST Sun Dec 5 2021 Through Monday night... The main concern in the short term is strong winds late tonight into Monday morning, in which a Wind Advisory has been issued for locations along and north of the I-80 corridor. Scattered light rain and drizzle/mist continues to fall this afternoon within continued warm, moist advection aloft north of an approaching warm front. These light showers will continue through early evening before pushing slowly off to the east ahead of a 1002 mb low pressure lifting northeast over the area. MUCAPE values of around 100 J/kg as analyzed by the RAP may still result in a couple thunderstorms in/near the eastern CWA before the showers depart, and earlier there was some lightning in central Illinois. Meanwhile, temperatures will continue to warm through about 8 PM as a warm frontal boundary inches into the southern CWA this evening. Seeing that much of the area will remain north of the boundary, we will see a sharp north-south temperature gradient this evening with the far southern CWA warming into the lower to possibly even mid 50s while areas north of I-88 will be stuck in the upper 30s. As the storm`s low pressure center passes to our northeast, a strong cold front will pass through the area sending temperatures downwards. Behind this cold front, westerly winds will markedly uptick overnight within the cold advection regime and robust pressure gradient between the deepening low and an incoming Canadian high pressure around 1035 mb. The steepened low-level lapse rates and unidirectional boundary layer flow look to support decent momentum transfer to at least 2,000 ft where there is 45 to 50 mph flow, despite the time of the day. It`s possible the overnight hours keep gusts a little down from peak gust potential, but in the morning hours the cold conveyor belt is potent enough that the 45 mph gusts should at least occasionally materialize. There is a consistent signal of stratocumulus wrapping around in the morning but this looks fairly thin and should not retard much of the momentum transfer. With the cloud layer, albeit thin, overlapping the -8C to -13C layer, some "low quality" flurries are likely to pop up primarily in the northern CWA. These should not be a big deal, but with the wind there could be some brief visibility reductions. Winds will gradually ease late morning into the afternoon from west to east. The cold advection will not allow temperatures to recover on Monday, with possibly a couple degree climb at best in the afternoon. Wind chills will be in the teens much of the day. The high pressure will spread over the area during Monday night with winds dropping off. Before they do, some single digit wind chills may unfold during the evening. Low temperatures Monday night have the potential to drop down widespread into the single digits (even a -1 from the 12Z MET guidance for Rochelle). One fly in the ointment to that is the likelihood of incoming high to mid clouds late Monday night/early Tuesday morning. We accounted for those in the forecast, but if the clouds look less likely, the lows will need to be inched downward. Doom/MTF && .LONG TERM... Issued at 233 PM CST Sun Dec 5 2021 Tuesday through Sunday... Guidance continues to fade away from any substantial precip across the area Tuesday into Tuesday night as a trough embedded in an expansive longwave trough across central and eastern North America becomes rather sheared over the Great Lakes region. An exceptionally dry antecedent airmass marked by sub-zero surface dewpoints and pwats at or under 0.25" will inhibit widespread precip potential even with modestly favorable mid and upper-level dynamics in the region. Initially Tuesday morning, weak WAA and fgen under the right entrance of an upper jet streak west of the CWA may generate enough precip aloft for some flurries to reach the surface into the northern CWA. A second area of light snow may then develop later Tuesday into Tuesday evening ahead of a jet streak approaching southern IL. Finally, light snow potential will linger overnight into Wednesday as the embedded trough swings through the area. Overall, most of the period will likely be dry, with the setup favoring a period or two of higher probability light snow with little to no QPF/accumulation. Tuesday will be the coldest day so far this season with highs struggling to rise into the mid 20s under decent cloud cover. Winds should be fairly light in the morning, but wind chill values near zero are likely across much of northern Illinois around daybreak. Another deep trough with an expansive low-level WAA and surface trough response is progged to bring a bout of more unsettled weather to the area Thursday into Thursday night. Thermal profiles support mostly liquid precip given a notable warm nose advecting in from the south, but some mixed precip potential exists at onset with low- level wetbulb temps initially below freezing. Another strong wave late Friday into Saturday will bring more unsettled weather to the Great Lakes region. Given the variability in guidance this far out, little detail can be provided. However, the pattern favors some wintry precip during late week through the weekend. Kluber && .AVIATION... For the 00Z TAFs... Aviation Forecast Concerns: * IFR/LIFR ceilings and IFR vsbys this evening. * Strong west winds developing later tonight, and persisting Monday. Strongest winds with gusts near 40 kt through Monday morning, easing gradually afternoon/evening. Surface low pressure was over the upper Mississippi Valley early this evening, with an occluded cold front stretching southeast to a triple point with a warm front over northern IL. Light winds and light rain/moist low level conditions across the forecast area had resulted in LIFR cigs and IFR visibilities across the terminals this afternoon, with ceilings 200-400 feet and visibilities of 1 1/2-2SM common in drizzle/fog. These conditions will persist for another couple of hours, though should begin to improve as the surface frontal trough moves slowly east across the terminals. Stronger west winds will lag the front a bit, but will become strong and gusty late this evening/overnight. With the stronger winds, an intrusion of drier low level air will allow for rapid improvement to MVFR/VFR cigs and VFR visibilities. As the main upper trough moves over the area Monday morning, a period of high- MVFR cigs and a few snow flurries or light snow showers are possible, though VFR conditions will return by afternoon. As winds shift westerly later this evening, speeds will increase with gusts 25-30 kt. Strongest winds look to arrive shortly after midnight however, as strong low level cold advection maximizes mixing and frequent gusts around 40 kts develop. This persists through Monday morning, before a very gradual decrease occurs during the afternoon/early evening. Direction should be pretty consistent in the 280-300 degree range during this time. Ratzer && .MARINE... Issued at 310 PM CST Sun Dec 5 2021 South to southwest winds to around 25 kt early this evening. A lull in the winds is expected mid evening ahead of a trailing strong cold front. This front will sweep across southern Lake Michigan early overnight, shifting winds to the west/northwest with speeds increasing to gales to 40 kt. These stronger winds will continue through Monday morning and begin to slowly diminish Monday afternoon into Monday evening. cms/MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Wind Advisory...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ019-ILZ020-ILZ021-ILZ103-ILZ104-ILZ105- ILZ106-ILZ107-ILZ108...2 AM Monday to noon Monday. IN...Wind Advisory...INZ001-INZ002...2 AM Monday to noon Monday. LM...Gale Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...midnight Monday to 3 PM Monday. Small Craft Advisory...nearshore waters until midnight Monday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
815 PM CST Sun Dec 5 2021 .UPDATE... Issued at 754 PM CST Sun Dec 5 2021 The forecast is progressing much as anticipated. At 800 PM the front looks to be stretching from near KIJX to KSTL to just north of KVIH to just north of KJLN. It should pick up some speed to the southeast as the mid/upper level trough continues to dig into the Upper Mississippi Valley and the eastern Plains. Convection allowing models, particularly the HRRR, has been very consistent in developing convection between 02-04Z. This looks reasonable particularly in light of the accelerating warm front producing additional low level convergence, in addition to more robust low level warm advection due to the strengthening low level jet just ahead of the front. GOES is showing rapidly increasing low level clouds ahead of the front...most likely in response to the aforementioned warm advection. Indeed, convection has increased a bit in coverage in the past 15 minutes or so as I`m writing, and this trend should continue. Latest RAP analysis shows around 1000 J/Kg MLCAPE and 1000-1500 J/Kg MUCAPE along with 40+ kts of deep layer shear over the eastern Ozarks and south central/southwest Illinois. 0-1km helicity is 300 M2/s2 and and the bulk shear is 30-40kts. This would be pretty favorable for rotating updrafts and therefore severe storms. Damaging wind and a few tornadoes will likely be the primary threats from any storms that can develop strong enough updrafts. Carney && .SHORT TERM... (Through Late Monday Night) Issued at 224 PM CST Sun Dec 5 2021 The primary item of interest in the short term will be the potential for showers and thunderstorms across southeast Missouri and southwest Illinois later this evening, along and ahead of an advancing cold front. Earlier today, scattered elevated showers along the leading edge of an advancing warm front moved through parts of the area, producing occasional bursts of moderate rain and a few lightning strikes. This activity has finally moved northeast of the area, leaving behind a stubborn deck of broken stratus. Temperatures have warmed nicely into the 60s in parts of central Missouri where clouds have begun to clear, with cooler temps in areas that have yet to see much sunlight today. These clouds are expected to gradually thin a bit more over the next few hours, although some areas may not completely emerge from them until the cold front sweeps through late this evening. Meanwhile, surface observations indicate that abnormally rich low- level moisture has begun to surge northward into the mid-Mississippi River valley, with dewpoints in the low 60s now across the bootheel region of Missouri. This is expected to continue over the remainder of the afternoon, and by the time the cold front arrives during the evening, much of the area will see surface dewpoints well above the 90th percentile for this time of year. While mid-level lapse rates will be poor, this abundant low level moisture will likely be enough to generate at least marginal instability, perhaps between 250 and 750 J/kg across southeast MO and southwest IL. As the front approaches from the north, the increased forcing is likely to trigger at least scattered convective development during the evening hours. The primary question will be exactly where this occurs, as CAMS continue to exhibit some disagreement even now. This will most likely occur south of the I-44 corridor, although it`s not completely out of the question that a few of the initial cells could begin to form as far north as St. Louis. In any case, it does appear that this activity will not reach maturity until late in the evening and well south of the St. Louis/Columbia/Jefferson City metro areas. While instability will be marginal, strong forcing and ample shear may provide enough ingredients to produce a strong, maybe even severe, thunderstorm or two in the areas where storms manage to form. Again, it seems like the bulk of this threat will be farther south across the bootheel region and far southern Illinois, but it can`t be completely ruled out farther north across parts of the Ozarks either. Where this occurs, large hail, gusty winds and even a brief tornado can`t be ruled out. Areas north of the I-44 corridor can expect mostly dry conditions the rest of the night, aside from a few weak showers in the evening right along the advancing front. Showers and storms will quickly move southeast, and will likely be out of the area by midnight or so. Otherwise, gusty southerly winds will turn to the northwest overnight as the front passes, and may gust up to around 30 or 35 mph at times. This will continue through Monday afternoon before winds finally weaken. Dry, sunny, blustery conditions can be expected Monday, with temperatures about 5 to 10 degrees below average. BRC .LONG TERM... (Tuesday through Next Sunday) Issued at 224 PM CST Sun Dec 5 2021 The forecast for most of the work week continues to trend towards the dry side, particularly regarding the potential for wintry precipitation Tuesday and Wednesday. While temperatures will certainly be cold enough to support frozen precipitation during this timeframe (lows will fall into the 20s both Tuesday and Wednesday mornings), latest model trends continue to suggest that precipitation will be difficult to come by, and very light if it does precipitate at all. It remains possible that some light snow may fall at various times between Tuesday morning and Wednesday morning, but it may only amount to some flurries with little to no accumulation. Otherwise, expect temperatures to only reach the 30s Tuesday afternoon, and back up to near normal Wednesday afternoon. Over the latter half of the week, another rapid warming trend can be expected thanks to the return of building high pressure aloft and southerly low level flow. As such, temperatures Thursday and Friday are likely to climb back to well above seasonal averages, particularly Saturday when most ensemble members produce high temperatures at least 10 degrees above average. While a weak disturbance may move through the area sometime Thursday, this period is also expected to remain dry. Models continue to hint at the possibility of more active weather returning over the weekend, but model spread remains too great to make too many definitive proclamations just yet. BRC && .AVIATION... (For the 00z TAFs through 00z Monday Evening) Issued at 508 PM CST Sun Dec 5 2021 A cold front which is currently moving through northwest Missouri will pass through the forecast area this evening. The primary impacts from this frontal passage will be showers and thunderstorms across the eastern Ozarks into southwest and south central Illinois as well as a wind shift to the northwest and wind gusts of 20-30kts behind the front. Some of the storms in southeast Missouri and southern Illinois could produce wind gusts in excess of 45kts as well as a tornado or two. Thunderstorms could also reduce the visibility to IFR in heavy rain. Rain and storms should move southeast of the forecast area by 06Z or shortly thereafter. VFR flight conditions with gusty northwest winds will then prevail through Monday. SPECIFICS FOR KSTL: The cold front should pass through Lambert between 03-04Z. Current indications are that any showers and storms that form will stay south-southeast of the terminal...but it looks close. Gusty northwest flow and VFR flight conditions are expected to prevail after FROPA. Carney && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Mobile AL
600 PM CST Sun Dec 5 2021 .AVIATION... 00Z issuance...Brief periods of IFR to LIFR ceilings due to low clouds and fog can be expected tonight, however widespread dense fog is not expected due to the cloud cover. A band of rain showers and possible embedded isolated thunderstorms will move into inland portions of SE MS and SW AL after mid-morning Monday, resulting in localized MVFR ceilings and visibilities. /13 && .PREV DISCUSSION... /issued 348 PM CST Sun Dec 5 2021/ NEAR TERM UPDATE /Now Through Monday/...A shortwave trough over the central and northern Great Plains will move to the eastward through the near term. The axis is forecast to shift east of the Mississippi River Monday morning, and amplify on Monday as the trough digs across the Upper Midwest and adjacent Great Lakes and Ohio Valley region. A southerly low level flow pattern will be prevalent through tonight as low level ridging extends across the western Atlantic and much of the eastern and southeastern U.S. The moist southerly flow will keep skies partly to mostly cloudy early this evening, with clouds continuing to thicken overnight. Dry conditions will remain through tonight, with patchy inland fog developing tonight over a small portion of south central AL. A Dense Fog Advisory is not expected at this time due to the patchy nature of the fog and increasing cloud cover inhibiting radiational cooling. Winds will shift southwesterly Monday morning ahead of a cold front approaching from the northwest that will advance close to the I-65 corridor by late Monday afternoon. A zone of enhanced deep layer ascent will become focused along the cold front during the day Monday, and the latest short range model guidance remain in good agreement with the development of a forced line of convection advancing into our southeast MS and interior southwest AL counties during the late morning hours on Monday. This line will then continue to move southeastward across the remainder of CWA by late Monday afternoon. There will be up to around 40 knots of deep layer shear available across interior southeast MS and southwest AL as the convective line approaches these northwestern counties during the late morning and early afternoon hours. The higher resolution HRRR and NAM guidance also indicates some weak instability in this region with up to 500-1000 J/KG of MLCAPE available during peak heating, so a couple of embedded stronger storms within the line may become briefly capable of producing localized 40-60 mph gusts. SPC has outlined a Marginal severe risk over much of our area, but the best potential of a strong to marginally severe storm will probably be most favored along and northwest of I-65 during the early to mid afternoon hours prior to the gradual weakening of the line. Rainfall amounts will not be overly heavy, but there could be a few spots that receive between 0.5 to 1 inch of rain within the heaviest convection along and northwest of I-65. Lows tonight range from the upper 50s to lower 60s, with the exception of mid 60s at the beaches. Highs Monday will range from 72 to 77 degrees, with a few upper 70s across portions of south central Alabama. /22 SHORT TERM /Monday night Through Wednesday night/...A busy short term period lies ahead as our initial upper level trough shifts northeast across the northeastern U.S. and a surface cold front pushes through the area. The cold front likely stalls somewhere near the coast Monday night into Tuesday morning before beginning to slowly lift back north as a warm front Tuesday afternoon into evening. Another pair of shortwaves move through the area, first one embedded within the subtropical jet Tuesday afternoon, and the next one associated with a broad upper level trough Wednesday afternoon. Prior to their passage, some attempt at warm air advection is made over our coastal zones, seemingly in a battle against the surface high to the north providing for cold air advection over the area. As a result of this, expect a general isolated to scattered coverage of showers and thunderstorms, primarily elevated, across the area Monday night through Tuesday night. Warm air advection prevails with better synoptics moving in Tuesday night into Wednesday which should allow for the warm front to finally surge inland, perhaps allowing for a few surface based showers and storms to manifest over the coastal counties Wednesday morning into afternoon. Prospects for severe weather potential remain a bit uncertain, with initial threat for isolated damaging winds and perhaps an isolated tornado early on Monday evening associated with the cold front where marginal CAPE and ample shear are present. Any future chances at severe look meager beyond this except for perhaps Wednesday morning into afternoon across far southwestern AL into the Fl panhandle where some surface based convection seems possible amidst meager SBCAPE and 50 to 60kts of sfc-6km wind shear. Temperatures are going to solely rely on the evolution of the cold front and when that lifts back north as a warm front. Currently it looks like a majority of the CWA is in for a relatively chilly Monday night and Tuesday with the front remaining along the coast or just offshore in the marine zones. Lows dip into the lower to middle 40`s over far interior southwestern AL and southeastern MS, with lower to middle 50`s along and southeast of the I-65 corridor. Highs struggle to climb with extensive cloud cover, rain, and cold air advection ongoing in the low levels with middle to upper 50`s inland and lower to middle 60`s along the I-65 corridor. Some isolated upper 60`s are possible across the FL panhandle if the front doesn`t quite clear the area. Tuesday night features little diurnal change in temperatures with lower to middle 50`s for most locations, and perhaps upper 50`s to lower 60`s along the immediate coast as the warm front begins to lift north into the area. Wednesday will offer some improvement on temperatures, reaching the lower to middle 60`s for most locations. Across the coast, highs in the upper 60`s to lower 70`s can be expected. Lows Wednesday night will fall into the middle to upper 40`s inland and lower 50`s across southeastern MS, southwestern AL and the FL panhandle. It`s important to note that there continues to be great uncertainty in the temperature forecast as models continue to differ on the exact placement of frontal features and their evolution, and there will likely be changes to the current temperature forecast moving forward, particularly for the Tuesday into Tuesday night time frame. MM/25 EXTENDED TERM /Thursday Through Sunday/...The extended term relaxes a bit early on as the upper level pattern reloads. A weak shortwave tracks to the north Thursday as upper level ridging settles in across the central Gulf of Mexico, putting us in generally zonal to southwesterly flow aloft for Friday and Saturday. A potent upper level trough begins to dig across the western U.S. into the central Plains states Thursday night into early Saturday before shifting east across the southeastern U.S. Saturday night into Sunday. At the surface, high pressure over the southwestern Atlantic noses west, allowing for surface southerlies to take hold and a general warm air advection regime to set up shop for a majority of the extended period into Saturday night before a cold front moves through the area Saturday night into Sunday. Overall weather is going to be Spring-like with isolated to scattered showers and thunderstorms possible each day. Saturday into Saturday night bears watching still as a favorable synoptic setup exists for the potential of severe thunderstorms across the southeastern United States. Trends in model guidance will be monitored moving forward. An anomalously warm air mass takes shape across the area during the extended period with temperatures warming into the lower to middle 70`s Thursday, and middle to upper 70`s for Friday and Saturday. It`s not out of the realm of possibility temperatures can trend a little warmer and flirt with record highs Friday into Saturday. Sunday in the wake of the cold front temperatures will only reach the lower to middle 60`s. Current forecast low temperatures are nothing short of remarkable, with Thursday and Friday nights featuring lows in the lower 60`s to perhaps even middle 60`s across far southeastern MS and southwestern AL/FL panhandle. To put this into perspective, our typical average highs hover in the lower to middle 60`s for this time of year, with average lows in the lower to middle 40`s. Saturday night will likely feature cooler temperatures in the upper 40`s to lower 50`s. MM/25 MARINE...Small craft should exercise caution after midnight beyond 20 nm due to southerly winds increasing to 13-18 knots. Otherwise, a light to moderate onshore flow will persist through Monday, followed by a light to moderate offshore flow developing over the near shore waters Monday night as a cold front moves just offshore and stalls. A light to moderate onshore flow will resume Tuesday afternoon, shifting westerly on Wednesday momentarily, then back to an onshore flow through the remainder of the forecast. Small craft will need to exercise caution at times later in the week as southerly winds increase. /22 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at:
Area Forecast Discussion
National Weather Service Norman OK
550 PM CST Sun Dec 5 2021 ...New AVIATION... .SHORT TERM... (This evening through Monday) Issued at 138 PM CST Sun Dec 5 2021 Very warm and slightly breezy conditions have developed this afternoon ahead of an approaching cold front, now nearing central KS. Southwest winds will decrease around sunset as decoupling occurs. However, later tonight a tight pressure gradient and a warm boundary layer will result in very breezy north winds with fropa as remixing occurs. 45-50 kt speeds will be present around 10 PM to midnight near the top of the mixed layer. The HRRR continues to suggest a very brief period around 11 pm to midnight of gusts near 45 to 50 kt across west central OK. For this reason we`ve decided to issue a wind advisory west of I-35 and along/south of I-40. This advisory might be expanded northward depending on early trends this evening. Moist convection will also accompany the front this evening into the overnight hours mainly across SE OK where moisture will be sufficient. Enough deep layer shear and elevated instability could support storm organization over far SE OK, where marginally severe hail and damaging winds would be the main threats late tonight. Do not anticipate widespread storm coverage, however, and most of the PoPs will quickly decrease below mentionable by 4 am. && .LONG TERM... (Monday night through next Saturday) Issued at 220 PM CST Sun Dec 5 2021 A surface ridge, centered over Oklahoma Monday night, will allow temperatures to cool quickly during the evening. Overnight, the wind will increase some along with a gradually increase in high clouds over the northern half of Oklahoma. The circulation around high pressure over the Upper Midwest/Ohio Valley Tuesday will keep most of the state on the cooler side Tuesday. Low pressure will deepen over eastern Colorado on Wednesday as a low amplitude wave approaches. Breezy to perhaps windy conditions may result, especially by afternoon. Moisture return will keep afternoon humidity from falling too much, but the exception might be parts of western Oklahoma. Will need to keep an eye out for possible fire weather concerns Wednesday. A weak frontal boundary will move through part of the state on Thursday but will do little to keep temperatures from warming back into the upper 60s and 70s. A lead shortwave trough will move across the central Plains on Friday. Breezy and very warm conditions will at least elevate fire weather conditions during the afternoon. This wave will also push a front through the state Friday night. Enough cold air may overspread the region for wintry precipitation Friday night into parts of the day Saturday. This system will move east of the area by early Sunday with another warming trend possible into early next week. At this time, any winter weather precipitation that occurs Friday/Saturday should be light. && .AVIATION... (00Z TAFS) Issued at 549 PM CST Sun Dec 5 2021 VFR will apply through the forecast period, although gusty north winds will accompany a cold front tonight. Expect winds to shift to the NW and then N around 02 to 05Z for all terminals. Gusts may briefly near or exceed 40 kt around 03-10Z. A few high clouds are expected but any precipitation/tsra should remain east and south of the terminals across SE OK. && && .UPPER AIR... Issued at 138 PM CST Sun Dec 5 2021 An Upper Air flight is not planned for tonight. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 35 46 27 52 / 10 0 0 0 Hobart OK 34 48 25 54 / 0 0 0 0 Wichita Falls TX 39 52 28 59 / 0 0 0 0 Gage OK 26 43 24 48 / 0 0 0 0 Ponca City OK 31 45 27 47 / 0 0 0 10 Durant OK 42 54 32 56 / 60 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...Wind Advisory from 10 PM this evening to 4 AM CST Monday for OKZ014>018-021>025-027>029-033>039-044. Wind Advisory until 2 AM CST Monday for OKZ004>007-009>012. TX...Wind Advisory from 10 PM this evening to 4 AM CST Monday for TXZ083-085. && $$ SHORT TERM...03 LONG TERM....06 AVIATION...09
Area Forecast Discussion
National Weather Service Pueblo CO
731 PM MST Sun Dec 5 2021 .UPDATE... Issued at 710 PM MST Sun Dec 5 2021 ...Key Messages - Continued strong winds tonight before decrease after midnight. - Light snow expected tomorrow night into Tuesday. - Still watching the track of the end of the work week system... UPDATE Issued at 612 PM MST Sun Dec 5 2021 The strong cold front that blasted through the region this afternoon and evening continues to cruise southward leaving behind gusts 35-50 MPH. This trend will continue for the next few hours before decreasing enough to allow folks to get some peaceful sleep. Also watching a deck of stratus work it`s way in from the north so expecting we do fill in quite a bit overnight as the east-southeast flow becomes established. && .SHORT TERM...(This evening through Monday) Issued at 253 PM MST Sun Dec 5 2021 Cold front racing southward through the plains of northeast Colorado this afternoon, as upper level trough over the nrn plains heads into the Great Lakes. Ahead of the front, very dry/warm/windy conditions were noted over southeast Colorado, and Red Flag Warning was verifying along I-25 and back into the eastern mountains as humidity has dropped below 10 percent at many locations. For this evening, cold front will continue to drop quickly southward through the plains, driven by large (5mb/3hr) surface pressure rises over ern WY and nern CO. HRRR suggests a brief period of gusts over 50 mph immediately following the frontal passage, mainly over the plains east of I-25, and given upstream observations, expect some brief blowing dust in open areas as well. Over the mountains and interior valleys, breezy w-nw Winds will gradually diminish this evening, though higher peaks will likely see gusty winds persist through the night. As winds gradually subside and turn s-se on the plains after midnight, some model soundings suggest stratus may develop over El Paso County, as rather narrow saturated layer forms under increasing upslope flow. Min temps will end up fairly chilly at many locations, with teens widespread and some single digits over high mountain valleys. On Monday, much cooler conditions area-wide in the wake of the cold front, and a few spots near the Palmer Divide may stay only in the 30s as clouds linger into early afternoon. Winds will be lighter than Sun as most locations, though with lee trough deepening along I-25 in the afternoon, south winds over the eastern plains toward the KS border will likely gust 20-30 mph in the afternoon. .LONG TERM...(Monday night through Sunday) Issued at 253 PM MST Sun Dec 5 2021 Monday night-Tuesday... Late Monday into Tuesday, westerly flow aloft will increase ahead of the next upper-level trough, and the transported moisture and upslope flow will allow for orographic snowfall across parts of the Continental Divide and central mountains. As the system translates across the Rockies, the San Juans will be picking up around 1 inch of snow, while some parts of the Continental Divide could be seeing 2-4 inches over some of the taller peaks. Other higher-elevation areas could be seeing a light dusting as the system passes by, with light isolated to scattered showers over our higher terrain, depending on local orographic interactions. Temperatures on Tuesday will be slightly above average, and a few degrees above Monday, with high-40s and low-50s anticipated over most of the area. Wednesday-Sunday... Northwest flow aloft increases starting early on Wednesday before becoming more westerly ahead of some more Pacific energy digging into the region late Wednesday into Thursday. This will lead to warmer and drier conditions over the plains both days, with low-60s expected in most areas. Over the mountains, snowfall chances will increase Wednesday night into Thursday along and west of the Continental Divide as the moisture and westerly flow set up supporting orographics again. Models continue to disagree on the exact of the upper trough into next weekend. However, the majority of ensemble solutions and some of the deterministic guidance shows the trough deepening and digging into the southern states, as well as slightly slowing down the progression of the system, which will increase chances for more widespread precipitation over the mountains as well as the eastern plains. Temperatures Friday and Saturday are expected to cool down closer to seasonal averages, before warming significantly on Sunday as upper- level ridging is currently expected to return. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 253 PM MST Sun Dec 5 2021 At KCOS, VFR into early evening, with a cold frontal passage 23z- 01z, then MVFR stratus developing by 06z and persisting into midday Mon before slowly clearing. North winds will gust 30-40 kts following the fropa this evening, before weakening and turning s-se Mon morning. At KPUB, VFR the next 24 hrs, with a period of low VFR cigs developing toward 06z tonight and persisting into midday Mon. Winds will become n-ne behind a cold frontal passage 00z-02z, with gusts over 30 kts until 06z. Lighter s-se winds then develop Mon morning. At KALS, VFR tonight and Monday, with winds staying under 15 kts through the period. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HEAVENER SHORT TERM...PETERSEN LONG TERM...GARBEROGLIO AVIATION...PETERSEN
Area Forecast Discussion
National Weather Service Springfield MO
508 PM CST Sun Dec 5 2021 ...00Z AVIATION UPDATE... Key Messages: 1. Strong to isolated severe storms tonight south of I-44. 2. Cooler and drier weather early next week - Elevated Fire threat. 3. Another warm up likely by late week. 4. Additional precip chances next weekend. .SHORT TERM...(This evening through Monday) Issued at 145 PM CST Sun Dec 5 2021 It was a warm and breezy afternoon as widespread clear skies have allowed for mixing of higher winds to the surface. Wind gusts to 40mph have been observed so far. Temperatures were in the upper 60s to lower 70s. Big changes are on the horizon however, as a strong cold front was currently working its way southeast through central Kansas. Storm Potential Tonight: The cold front will likely enter the northwest CWA by 6-7pm. The airmass currently is capped and will likely remain capped as the front enters the area. Strong lift, associated with mid level disturbances to the north and south of the area, will allow for convection to develop as the front nears the Interstate 44 corridor as early as 8pm. 12Z HREF analysis suggests that updraft probabilities will increase to the southeast of Interstate 44 as the front moves through. Updraft helicities are strongest from the Missouri-Arkansas border and points south. RAP forecast soundings from Branson to West Plains are consistent in showing about 1000j/kg of ML cape, 40kts of 0-6km shear, and steep mid level lapse rates. Therefore the ingredients are there for a few strong to severe storms. The low level hodograph shows a southwest to west flow, which should keep the tornado threat very low. Higher QLCS potential with more organized storms looks to remain just south of the area. Storms will be fast moving with most areas seeing less than 0.50 in of rainfall. Storms will be out of the area by 1-2am. A strong cold front will usher in dry and cold air overnight, with most locations seeing wind gusts up to 35 mph and temps in the 30s by sunrise Monday. HREF cloud data suggests that skies should remain partly cloudy during the day, and with strong cold air advection, highs will struggle to warm into the lower to middle 40s. Lower humidity and gusty winds will lead to elevated fire weather conditions Monday. .LONG TERM...(Monday Night through Sunday) Issued at 145 PM CST Sun Dec 5 2021 Zonal to slightly northwest flow aloft will persist Tuesday into the mid week period. A weak disturbance moves into the area Tuesday night into Wednesday. Moisture looks to be limited, with the NBM only showing a 10-15 percent chance for measurable precip. More than likely only a few flurries or sprinkles will occur with this system. A steady rise in temperatures looks likely as we head to the end of the week. Ensemble cluster analysis shows good consensus in another mid level ridge developing over the central US. NBM temperatures support 50s Wednesday and 60s Thursday and Friday. The flow turns more southwesterly on Friday, with cluster analysis showing the potential for max temps to reach 70 degrees. This is also seen in the 75th percentile of NBM guidance. Next Weekend: While ensembles are in decent agreement that a upper level trough will develop across the Rockies, there is disagreement in the timing and structure of the wave as it ejects into the Plains. At this time, NBM probabilities for precip are highest across the southeast half of the area Saturday into Sunday(40-60 percent). This also matches the ensemble cluster analysis and CIPS extended analogs. Current probabilities for any measurable snow are quite low at this time (20 percent). NBM temperatures generally keep highs in the 40s to around 50 with lows in the 30s during this time. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 453 PM CST Sun Dec 5 2021 Current models show a strong cold front pushing through the region this evening after 00Z, bringing a chance of thunderstorms, mainly at KBBG around 03Z. Cannot rule out a storm at KSGF, although chances are low at this point. Current southwest winds will shift behind the front towards a more northwesterly direction, and gusts up to 30 kts will be likely into Monday. VFR flight conditions look to persist through the rest of the TAF period, however visibilities and ceilings could lower with the stronger storms. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ SHORT TERM...Burchfield LONG TERM...Burchfield AVIATION...Schwartz