Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/21/23


Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
315 PM AKDT Wed Sep 20 2023 .SYNOPSIS... A long wave trough complex with a handful of embedded features crosses the state through the close of the workweek with unsettled, showery conditions in the west and steadier precipitation overspreading the eastern Interior to the Brooks Range shifting east through tomorrow. High pressure builds behind the system with cooler, drier Arctic air bringing fair weather to much of Northern Alaska by the end of the week. With high pressure centered over the Interior heading into the weekend, rainy weather is generally deflected to the periphery, mostly along the North Slope and the Yukon Delta. && .DISCUSSION... Current Upper Levels and Analysis... Looking through RAP analysis and the satellite feed this afternoon...a three-pronged upper level trough complex stretches from the Arctic coast through western Alaska down to dominant low pressure over the Alaska peninsula. Generally showery weather with lowered ceilings accompany the surface trough through the west, with areas of fog showing on webcams and surface stations along the Arctic Coast. Meanwhile a surface occlusion/warm front aloft associated with the low pressure circulation near the southern coast continues to push northward through the Whites with KAPD reflecting this nicely. SE flow behind this feature continues across the eastern Alaska Range, spreading precipitation through the eastern Interior and toward the eastern Brooks Range tonight. Precipitation chances diminish from west to east tonight and Thursday with a Pacific ridge poking north into the Bering Strait, tracking west into Alaska tonight into Thursday. The exception is along the North Slope as low pressure north of Nuiqsut/Deadhorse draws an onshore/upslope flow into the Brooks Range through Thursday night. High pressure and dry weather generally prevails heading into the weekend. Model Discussion... Large scale wind and pressure fields are in relatively good agreement at the jet level across the major model suites through the end of the day Friday, then start to show disagreement as the long wave trough begins to interact with a weak rex block near the central Canada/CONUS border. Middle and lower level fields show more disagreement as multiple trough features interact, however these impacts appear to remain primarily south of the Alaska Range. By this weekend, model differences center primarily around the persistence of upper level ridging through central Alaska extending to northwest Alaska. In general the ENS solutions favor a more amplified pattern featuring a stronger ridge and deeper trough lingering over the northern Alcan border...and another through the Bering sea... vs the GEFS. The timing and position of these features however are very similar, and the broad ensemble suite suggests accumulations associated with troughing features to the northeast and southwest would be light at any rate. Central and Eastern Interior (AFG)... Precipitation associated with low pressure along the southern coast will continue to spread north through the central and eastern Interior tonight. Noteworthy accumulations are expected to remain mostly at elevation with valley liquid amounts generally expected to be AOB 0.15". Snow levels remain around 2 kft, except in the upper Tanana valley southeast of Fairbanks where warmer temperatures aloft have snow levels closer to 4 kft. A briefly gusty downslope wind is possible between around Dry Creek and Tok in the upper Tanana Valley late tonight, but otherwise wind will remain light and variable before returning out of the west and the system departs on Thursday. A cooler and drier Arctic airmass invades Thursday and Friday although the mixing accompanying it should support valley temperatures in the 40s with ceilings lifting and perhaps a few peaks of sunshine. The dry trend continues into Saturday with high pressure moving overhead. West Coast and Western Interior (WCZ)... Low ceilings and unsettled weather shift east while northerly flow diminishes and shifts northwesterly as high pressure builds across the West Coast tonight Thursday. Fair weather prevails under high pressure thereafter. The exception is the approach of the next coastal low from the west... odds are good that most of the precipitation activity will remain south of the area over the Bering Sea toward the Alaska Peninsula with high pressure centered over the interior deflecting the system south, however the Yukon Delta still likely sees spotty rain showers amounting to a few hundredths Friday into the weekend along with a modest, increasing offshore wind. North Slope and Brooks Range (NSB)... Low pressure north of the Arctic Coast keeps an onshore flow along the coast west of Nuiqsut/Deadhorse where low ceilings, areas of fog, and showers continue... and upsloping into the eastern Brooks Range where up to 2" of snowfall potential exists. This general set up shifts east over the next couple of days with near-shore flow turning westerly and upslope snowfall diminishing by Friday. The low lingers over the Arctic Ocean north of the Alcan border into the weekend however with lowered ceilings... marine fog... light showers... and cool, raw weather continuing. Extended Forecast Days 4-7... Blocky upper level pattern brings inherent uncertainty to the long range forecast with a nebulous upper air pattern. Ensemble fields however suggest ridging to the east and troughing to the west with light precipitation amounts centered on the west and southwest. No hazardous weather is expected. Coastal Hazard Potential Days 3 and 4... Elevated surf along the Arctic Coast at Utqiagvik develops this evening spreads east of Utqiagvik late tonight and Thu and continuing into Fri. Northwest winds increasing to 20 mph along the Arctic Coast near Utqiagvik tonight will continue into Thu and spread east along the Arctic coast, then turn west on Thu night and continue into Fri. && .HYDROLOGY... Rivers steady or slowly falling as snow levels drop. && .AFG WATCHES/WARNINGS/ADVISORIES... AK...None. PK...Small Craft Advisory for PKZ801-854. Small Craft Advisory for PKZ802-850-853. Small Craft Advisory for PKZ805-857. Small Craft Advisory for PKZ806-807-816-817-856. Small Craft Advisory for PKZ813. Small Craft Advisory for PKZ851. Small Craft Advisory for PKZ852. Small Craft Advisory for PKZ858. Small Craft Advisory for PKZ859. && $$
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
1007 PM CDT Wed Sep 20 2023 .UPDATE... Issued at 959 PM CDT Wed Sep 20 2023 Late this evening, we have started to see some lightning activity develop with the radar echoes across the far south near the South Dakota border, mainly over Sioux county and portions of the southern James River Valley. A much larger complex of stronger storms continues to slowly move towards the area from north central South Dakota. Thus far, RAP mesoanalysis suggests the MUCAPE gradient drops off quickly with northward extent, mainly in the 100 to 250 J/kg range over far south central North Dakota, but an axis of 500 to 1000 J/kg should continue to advect north from South Dakota. Thus, storms and heavier rainfall should become more and more likely across portions of the south over the next few hours. For this update, just tweaked precipiation chances through much of the day tomorrow based on some of the latest high resolution guidance and radar trends. UPDATE Issued at 628 PM CDT Wed Sep 20 2023 Currently, a broad area of light to moderate rain showers is noted on radar over portions of western and much of central North Dakota. This activity will continue to move off to the east northeast through the evening. The next subtle short wave (currently located in the vicinity of eastern Wyoming and western South Dakota) will move up into south central North Dakota later tonight. The high resolution models continue to show a number of various different solutions with the 3 km NAM Nest and HRRR being the most aggressive in developing a complex of showers and thunderstorms across the south central after 03z or so. While instability will be rather limited early, NAM soundings do suggest some MUCAPE in the 1000 J/kg to 1500 J/kg range across the far south overnight. Whether parcels can access this instability is another question. Deep layer shear is forecast to generally range from 30 to 40 knots here. Thus, there is a conditional risk for a strong storm or two across the south central and southeast overnight into Thursday morning. Small hail would be the most likely threat, but some brief gusty winds are not out of the question. As an additional note, with various rounds of convective showers and storms forecast over the next several days, we are likely to see periods of heavy rain rates under the more intense showers and storms (most likely over the southern half of western and central North Dakota). This could lead to some locally heavy runoff which may become problematic for some small streams, urban areas, and low lying areas. For this reason, we still start to message the potential in the Hazardous Weather Outlook for tonight through the weekend. While we are not expecting any kind of large scale flooding, it is not out of the question that we could see some localized flooding depending on how this system evolves over the next several days. && .SHORT TERM...(This Evening through Thursday Night) Issued at 249 PM CDT Wed Sep 20 2023 The short term is highlighted by increasing chances of showers and thunderstorms this afternoon through Thursday, with potential for a few stronger thunderstorms on Thursday afternoon. This afternoon, deep troughing extended across the western CONUS, with closed lows placed over both the Pacific NW and southern California. Southwest flow aloft existed across the Northern Plains in between this and ridging over the Great Lakes region. At the surface, a broad surface high was centered over southeast Saskatchewan, while a weak surface trough/boundary exists over central North Dakota. On the west side of this boundary, a broad line of rain showers continues from north central through southwest North Dakota. A few isolated thunderstorms have developed in central South Dakota as of 1930 UTC. Shower activity is expected to diminish some through this afternoon as the boundary moves east, before increasing again as an embedded impulse moves north from South Dakota. Chances for showers and thunderstorms increase through this evening and are highest after midnight across south central North Dakota. Instability is low enough to limit the severe thunderstorm potential, although there could be a few stronger storms that could produce gusty winds and small hail, mainly across the south central tonight where there is the most favorable overlap of shear (30-40 knots) and instability (~500 J/kg). As the trough to our west deepens and emerges as a somewhat stationary closed low somewhere over eastern Oregon into Idaho, impulses will continue to eject out of the trough base and into the Northern Plains, bringing continual chances for precipitation. Thursday currently has the highest likelihood of some stronger thunderstorms as a continuation of tonight`s activity, with precipitation chances expanding north through the morning and afternoon. Strong southerly flow aloft is projected to overlap with a swath of low- level warm air advection, steep lapse rates, and instability on the order of 1000 J/kg. Weak bulk shear favors pulse-y thunderstorms that could produce small hail and gusty winds, especially as they collapse, although there are some differences among deterministic guidance regarding the strength of shear which will likely be dependent on where and when storms end up. Can`t rule out an isolated severe storm if parameters end up overlapping more favorably than expected, or if a pulse thunderstorm manages to get strong enough for a brief period of tine. Extended high- res guidance is beginning to advertise a second round of thunderstorms moving through the southern half of the forecast area Thursday night, but earlier convection could mitigate the environment. CSU machine learning does have a low but non- zero probability of severe hail across much of the area. Lows tonight will range from the mid 40s far west to the upper 50s southeast. Highs on Thursday have warmed up slightly for the James River Valley, into the mid to upper 70s, with the remainder of the forecast area in the upper 60s to lower 70s. Patchy smoke is projected to linger across parts of the south tonight into Thursday, with a few locations reporting reduced visibilities in the 6 to 8 mile range today. .LONG TERM...(Friday through Wednesday) Issued at 249 PM CDT Wed Sep 20 2023 Wet and cooler weather through the weekend highlights the extended period. The deep upper low begins to surge east on Friday, bringing more widespread and consistent chances for precipitation through most of the weekend as the low moves into the Dakotas. Blended POPs still has the highest and most widespread swath of precip chances Friday night through Saturday as the main deformation band moves north through the area, with the center of the low progged to be over the Dakotas on Sunday, although there are still slight differences in the speed amongst ensemble members. Probabilities have remained fairly consistent over the past day, with the highest rainfall totals favored across parts of the southwest and south central, in an area from Dickinson to Washburn and south. The probability of at least 1" of rain is still at least 50% along and south of Highway 2, with higher amounts to the south, although probabilities are also below 50% in the eastern James River Valley. The probability of at least 2" is maximized around 60% in between Dickinson and Bismarck, with the potential for at least 3" highest in this same area, around 40%. Highs during this period (Friday through Monday) will generally be in the 60s, with overnight lows in the mid 40s to mid 50s. With the strength of the upper low, expect breezy winds with this system, coming from the east on Friday and Saturday before becoming northerly on Sunday. Current blended guidance is advertising POPs tapering off from west to east on Monday, although it is frequent for wrap-around precipitation to persist longer than expected. Ensemble guidance then favors ridging building in over the central CONUS in response to a large upper trough developing off the West Coast, which indicates a slight warming trend bringing highs back to the upper 60s to lower 70s for the first half of the work week. No notable precipitation signals for this period, although CIPs Extended Analogs start skewing wet late next week so we could potentially get more active again. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) Issued at 628 PM CDT Wed Sep 20 2023 Currently, light to moderate rain showers are moving east northeast across portions of western and much of central North Dakota. This activity may cause brief visibility reductions into MVFR categories. More showers and thunderstorms are likely to develop later tonight across the south central, eventually moving north northeast into the vicinity of the Devil`s Lake Basin overnight and into Thursday morning. These showers and storms may be heavier and are most likely to impact KBIS, KJMS, and KMOT. Here, we could see brief visibility reductions into MVFR or even IFR categories. We may then see a break in precipitation from mid to late morning and into the early afternoon hours. More showers and thunderstorm are then forecast to develop later in the afternoon hours and through the end of the forecast period. The one site that may not see many impacts from this activity will be KXWA. Winds may become gusty and erratic in the vicinity of any heavier showers or storms. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...ZH SHORT TERM...Jones LONG TERM...Jones AVIATION...ZH
Area Forecast Discussion
National Weather Service Burlington VT
1037 PM EDT Wed Sep 20 2023 .SYNOPSIS... High pressure is moving into the North Country, with several days of pleasant weather expected. Cool nights and warm days are expected, with seasonal fog in the river valleys likely the next several days. A gradual warming trend is expected throughout the rest of this week. A low pressure system will move up the Atlantic coast, but some uncertainty remains on how far north precipitation lifts into the region. At the very least, there will be increasing cloud cover heading into Sunday and a halt to the warming trend. && .NEAR TERM /THROUGH THURSDAY NIGHT/... 1030 PM UPDATE... Forecast remains very much on track so only made minor changes to bring it up to date with current obs. Nighttime microphysics satellite shows some patchy lower stratus development across locations that have dipped below crossover temperatures. However, webcams are now showing fog development yet so SLK, which is currently at 41F, has a good chance of reaching the forecast low of 32F. If it were to occur, this will be the first 32 deg reading of the season for SLK. Looking at climate history, the mean date for the first 32F or lower for SLK is September 8. Existing Frost Advisories also remain in effect. PREVIOUS DISCUSSION... Surface high pressure building overhead will continue to be the dominate weather feature over the next few days, bringing a stretch of dry and pleasant weather. As skies clear towards the overnight, good radiational cooling conditions are expected across the region. Overnight low temperatures will fall into the 40s, with locations along Lake Champlain closer to 50. A Frost Advisory is in effect for parts of northern New York as low temperatures drop into the lower to mid 30s across portions of the Adirondacks. Given the synoptic set up and the radiational cooling tonight, fog development is expected across much of the area, especially the favored river valleys. Another beautiful late September day is in store for the region tomorrow. Skies will be mostly clear with some fair weather cumulus popping up, although skies might be a little hazy with the HRRR showing some wildfire smoke aloft moving into the Northeast. Temperatures tomorrow will be seasonable, although a few degrees warming than today. Daytimes high will be in the upper 60s, with the broader valleys reaching the low 70s. Thursday night will be another great night for radiational cooling and fog development, with overnight lows generally in the 40s. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 343 PM EDT Wednesday...The quiet stretch of weather continues into Friday as surface ridge of high pressure gradually shifts east. Our forecast area will remain on the western periphery of the anticyclone, with a southeasterly onshore flow in place. High temperatures on Friday will be in the low to mid 70s. Going into Friday evening, will see high clouds begin to spread overhead associated with a low pressure system to our south, with clouds expected to thicken and lower through the night. Lows will be in the 40s. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 343 PM EDT Wednesday...The forecast trends more uncertain going into the weekend with a coastal low pressure system advancing northward up the East Coast. Models still don`t have a good handle on what path the system will take after tracking over the Mid Atlantic Coast, with potential interaction with northern stream shortwave energy shunting the system south and east of our area before being carried out to sea. This scenario would mean few impacts to our area from the system outside of some increased cloud cover and some rain for our southern counties. This scenario lines up with the latest GFS/ECMWF deterministic forecasts, and is supported amongst the ensemble guidance as well (GEFS and ECENS showing only 20-30% chances of southern VT receiving over 0.1 inch rain over the weekend, with even lower probabilities further north). We are noting the NAM has a very different and much wetter forecast for our area, but this is towards the end of the NAM forecast and we are leaning away from this scenario at this time. Our current forecast has most of our area dry through the weekend, except southern Vermont, where we carry a 20-40 percent chance of showers mainly Saturday night. However, this is subject to change as models get a better handle on the forecast, so keep on top of latest forecasts if you have plans this weekend. The forecast for next week is looking very quiet as a surface ridge sets up over Quebec. Have forecast temperatures near seasonable norms for mid/late September and low chances of precipitation. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Through 00Z Friday... All terminals are currently VFR with mostly clear skies and light winds. The VFR conditions will continue through the overnight hours except where fog develops from strong radiational cooling. Currently fog is expected to form at SLK, MPV and EFK. There is high confidence of fog at SLK and MPV while there is less confidence at EFK, but still enough to put fog in the TAF. SLK could see fog around 04Z which is earlier than usual on radiational cooling nights as the 00Z temperature is much closer to its crossover temperature than normal at this point in the evening. MPV and EFK will likely see fog after 06Z. The fog should lift shortly after sunrise and all locations will improve to VFR through the end of the TAF periods with mostly clear skies and light winds. Outlook... Thursday Night: VFR. Patchy BR. Friday: VFR. NO SIG WX. Friday Night: VFR. NO SIG WX. Saturday: VFR. NO SIG WX. Saturday Night: VFR. Slight chance SHRA. Sunday: Mainly VFR, with local MVFR possible. Slight chance SHRA. Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. && .EQUIPMENT... The KCXX radar will be down for radome repairs, with a return to service around September 21st. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...Frost Advisory from 2 AM to 8 AM EDT Thursday for NYZ029-030. && $$ SYNOPSIS...Kremer NEAR TERM...Chai/Kremer SHORT TERM...Duell LONG TERM...Duell AVIATION...Myskowski EQUIPMENT...WFO BTV
Area Forecast Discussion
National Weather Service Quad Cities IA IL
653 PM CDT Wed Sep 20 2023 ...AVIATION UPDATE... .SHORT TERM...(This evening through Thursday Night) Issued at 240 PM CDT Wed Sep 20 2023 Key Messages: * Spotty showers and a couple storms in northeast Iowa through early evening, followed by gradually increasing showers south of U.S. Highway 34 tonight * While still uncertainty in specifics for Thursday, confidence is higher in rain in parts of northwest/north central Illinois, including potential for locally heavy rain during the P.M. hours in namely Bureau and Putnam Counties A broad upper low sprawled across Iowa, Missouri, and western Illinois will slowly creep east-northeast the next 24 hours. This low is comprised of multiple MCV centers, including one over northeast Iowa that will continue isolated showers in its immediate vicinity. Early afternoon environmental and satellite trends support some lightning within this north of Highway 30 the rest of this afternoon. Locally heavy downpours and lightning are the main notes with these. If some of this area were to clear this evening, patchy fog would be probable tonight. A more potent short wave circulation that has characteristics of an MCV, is located in northeast Missouri this afternoon and is progressing north-northeast. Despite its close proximity in space and time, this upper disturbance has been cumbersome for short- term models to handle both its track and evolution tonight into Thursday. Observational trends support a little more western track than some of the morning guidance indicated, which would yield rain in the immediate Mississippi River Valley and points east, especially late tonight and Thursday. The RAP has been consistent with an even further west solution and providing a soaking rain as far west as the Quad Cities on Thursday. Given the nature of this system with a closed circulation and PWATs near the 90th percentile for the of year, felt comfortable boosting PoPs from the Mississippi River eastward, especially in our eastern-most CWA Counties during the afternoon and evening on Thursday, where synoptic- and meso-scale forcing are juxtaposed. In terms of hazards and impacts, elevated lapse rates are forecast to be very weak, resulting in MUCAPE profiles being tall and narrow in the vertical (i.e. non-rapid updraft accelerations and unlikely to be widespread thunder or severe). In the far eastern counties (Bureau and Putnam in IL) and/or just east-southeast of there, a signal exists in convection-allowing models (CAMs) of localized heavy rainfall. This includes the 12Z HREF local probability matched mean indicating a narrow 2-4 inches just east of the CWA. So will need to keep an eye on that, as localized over-performing rain swaths can occur near slow- moving mid-level lows with anomalous moisture, such as this wave. Otherwise, lowered forecast highs for Thursday with the anticipation of more and deeper cloud cover, especially southern and eastern locations. .LONG TERM...(Friday through Wednesday) Issued at 240 PM CDT Wed Sep 20 2023 Key Messages: * Unsettled weather pattern, however low confidence in specific evolution; highest chances for rain currently Saturday night- Sunday * Depending on timing, a severe risk is possible in mainly eastern Iowa later Saturday/Saturday night, and then an even lower confidence in possibly locally heavy rain early next week The disturbance for Thursday/Thursday Night noted in the Short Term Discussion should be exiting the region early Friday. Some brief suppression may be seen in its wake, but the pattern remains moist and ensembles indicate low chances of rain on Friday are warranted. On the broader synoptic scale, a deep, closed low is expected to progress from Montana on Friday into the Upper Plains by midday Saturday. Ridging ahead of this provides subtle heights rises over the area Friday night and during the day Saturday, with an overall slower eastward progression of shower and thunderstorm chances on Saturday. Supporting this outcome is also a subtropical system that will move northward into the Mid-Atlantic states, and often such a pattern can result in a slowing of system movement at the same latitude. So have collaboratively trended down NBM forecast PoPs for the Mississippi River and points east during the day Saturday, and that trend may need to be the case for the entire CWA in future shifts. By Saturday night into Sunday, height falls do creep over the area as does a zone of forcing ahead of the surface cold front. But these features do slow as the wave gradually occludes during the middle portion of the weekend. Hence why confidence is low on details. The system has a magnitude and low-level moisture return worthy of a severe risk, but right now that seems better aligned in peak heating and the hours just after on Saturday toward the Mid-Missouri River Valley region. Certainly plenty of time for things to shift. Beyond, the then meandering upper low is naturally a challenge for long range guidance to handle. Large discrepancies from model-to- model and run-to-run with this and make blended or even probabilistic data difficult to interpret still at this point. Because of this, tough to stray much from the NBM forecast of "chance of rain with slight chance of thunder" Sunday-Tuesday. If the wave were to slowly move over our region and maintain its anomalous depth (similar to last evening`s 00Z ECMWF run), there there would probably be localized heavy rainfall. But just way too much uncertainty with such a pattern in Days 4.5 to 6 to hang our hat on. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 644 PM CDT Wed Sep 20 2023 A weak, slow moving weather system will track in from the south overnight into Thursday, bringing occasional chances for showers mainly to BRL and MLI. Brief MVFR ceilings and visibilities are possible in the vicinity of any heavier showers. There is also potential for shallow fog to develop late tonight into early Thursday AM near CID, but have low confidence on coverage and severity at this time. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SHORT TERM...Friedlein LONG TERM...Friedlein AVIATION...Uttech
Area Forecast Discussion
National Weather Service Grand Rapids MI
959 PM EDT Wed Sep 20 2023 LATEST UPDATE... Update .UPDATE... Issued at 959 PM EDT Wed Sep 20 2023 The upper pattern across the Lower 48 this evening is dominated by a trough in the Pacific Northwest and ridging (or at least higher heights) across the eastern third of the country. The main feature of note for our weather tonight is a compact low/vort center embedded within the higher heights over our area moving slowly northward across Illinois. There is some light rain/drizzle across Southern Illinois associated with the mid level vort, but any precipitation is expected to remain south of our area per the HRRR and the 12z HREF. The main affect from this vort on our area tonight will be that mid and high clouds will remain in place or even thicken. The clouds and a light southeast wind will keep temperatures up a bit with lows expected to be in the mid to upper 50s in most areas. The values are slightly above normal for late September. && .SHORT TERM...(This evening through Thursday night) Issued at 303 PM EDT Wed Sep 20 2023 - Isolated shower/storm Thursday afternoon north, marine zones Thursday night A weakening mid level wave will be located over WI during this time. This feature may provide enough lift to support an isolated shower/storm Thursday into Thursday night. The area will be in the entrance region of the low level jet though, which may limit the low level lift. Weakness in the stability and even slight instability will be around so, an isolated storm is possible. The latest SPC HREF LPMM QPF does show a few spots around Big Rapids and Baldwin with afternoon QPF Thursday. We will feature very low POPs for that location. Currently several models show a better area of organized rain lifting northward through Southern Lake MI Thursday night and they pull it westward into WI overnight. Assuming that stays west of our area, only very low POPs are needed for our marine zones Thursday night. - Warming up Gradual warm air advection will continue into Thursday as 925 mb temps climb another degree or two, with much of the CWA in the low 20 deg C range during the afternoon. Mixing to that level allows for max temps to reach 80 degrees. Many locations saw high temps today in the 75 to 80 degree range. There will be some more clouds around Thursday but that should not stop temperatures from topping out around 80 degrees. The slightly warmer temperatures are supported by the most recent ensemble model runs. .LONG TERM...(Friday through Wednesday) Issued at 350 PM EDT Wed Sep 20 2023 Models have been fairly consistent of late in showing a weak blocking pattern over the Great Lakes as a result of low pressure developing off the southeast coast of of the US. This block will help to keep high pressure over the state along with above normal temperatures as we head into Autumn this weekend. The first chance of precipitation really doesn`t arrive until Sunday night and even then chances aren`t high. The models (especially the ECMWF) are trying to move the eastern US low away from the coast which allows the Wisconsin low to drift in our direction. The ECMWF is much more bullish on precipitation late Tuesday into Wednesday. Whereas, the GFS takes the precipitation well south of the state. Thus confidence isn`t exactly high on precipitation chances next week. One thing that will probably occur, though, is that we`ll begin to pick up more of an easterly or northeasterly flow with time from the high over Ontario/Quebec, which will send some cooler air into the cwa. Even then, by the middle of the week, temperatures will still be near normal. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 741 PM EDT Wed Sep 20 2023 VFR conditions will continue through Thursday. Winds will be light and variable overnight. Cloud bases will be AOA 10 kft AGL. && .MARINE... Issued at 303 PM EDT Wed Sep 20 2023 Marginal conditions for small craft/beach hazards continue for northern zones this afternoon. The pressure gradient weakens this evening and that should result in diminishing winds. The next increase in wind/waves may occur Thursday night...but it will be offshore flow for most zones so the impacts will be limited. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...Duke SHORT TERM...MJS LONG TERM...MJS AVIATION...Ostuno MARINE...MJS
Area Forecast Discussion
National Weather Service North Platte NE
635 PM CDT Wed Sep 20 2023 ...00Z AVIATION UPDATE... .SYNOPSIS... Issued at 323 PM CDT Wed Sep 20 2023 Key Messages: - Active weather pattern expected Thursday through Saturday with the greatest precipitation chances Thursday night through Saturday. There is a small threat for storms tonight. - Severe storms are possible Thursday evening then again Friday afternoon through Friday night. - Cooler and windy conditions expected Saturday afternoon through Sunday. - Seasonal and dry conditions Monday through Wednesday. H5 analysis this morning had closed low pressure over northern Washington State. Downstream of this feature, shortwaves were noted over southern Alberta and northern Saskatchewan. A second closed low was located over the LA Basin of California. Across the central CONUS, weak disturbances were noted. The first over northern Utah and a second over Wyoming. Another stronger disturbance was located over the Ozarks. At the surface, a weak boundary was present from around Valentine to North Platte and McCook Nebraska. This was more of a moisture boundary with 60+ dew points east of this boundary and 40-50s dew points west of this boundary. Winds were light westerly west of the boundary with light easterly winds east of the boundary. Skies were mostly clear and 3 PM CDT temperatures ranged from 78 degrees at O`Neill to 89 degrees at Thedford. && .SHORT TERM...(This evening through Thursday night) Issued at 323 PM CDT Wed Sep 20 2023 Over the next 36 hours, upper level low pressure will drift south from northern Washington state south into southeastern Oregon. The east ward progress of this feature will be hampered by a southeast to northwest ridge, oriented from North Dakota into northern portions of Saskatchewan and northern Alberta. Over the next 36 hours, there will be three possible episodes of thunderstorm chances. For tonight: Currently there is some agitated CU off to the west of the forecast area over the Cheyenne Ridge, as well as some developing cloud cover over western portions of the forecast area. Looking at the short range CAMS today, two pockets of precipitation look possible. The first over central into northeastern portions of the forecast area, and second over the northeastern Nebraska Panhandle. Yesterday, we saw thunderstorm development over the central Sandhills with surface dew points in the upper 30s and lower 40s. With additional moisture noted this afternoon and similar flow aloft, believe pops are warranted here. Late tonight into early Thursday morning, a second area of storms may develop and push into the forecast area. The models are hinting at some decent mid level warm air advection late tonight entering southwestern Nebraska. This mid level lift will advect over a moistening boundary layer, leading to possible development of showers/thunderstorms Thursday morning. During the day on Thursday, low level moisture will continue to advect into western Nebraska thanks to deepening low pressure over eastern Wyoming into eastern Colorado. By 21z Thursday, a distinct dry line will develop from the southern panhandle into far southwestern Nebraska. This will serve as the focal point for thunderstorm development Thursday afternoon. ATTM, the latest NAM12, NAMNST, and 12z HRRR develop storms along the dryline Thursday afternoon. As this activity lifts east, it will encounter SB CAPES of 2000 to 3000J/KG and deep layer shear of 30 to 35 KTS. This will favor severe storms with hail and winds being the main threats. One caveat to the severe threat is low cloudiness. If stratus should persist into the afternoon, it will have a limiting effect on severe potential Thursday afternoon and evening. This stratus development is more favorable if...no warm air advection storms materialize overnight tonight. So in short, storms overnight tonight in SW Nebraska may limit severe potential in the west and southwest Thursday afternoon/evening. Given the uncertainties listed above, I have limited confidence in the severe threat for Thursday/Thursday night. .LONG TERM...(Friday through Wednesday) Issued at 323 PM CDT Wed Sep 20 2023 On Friday, the upper level low will migrate east from southeastern Oregon into far western Wyoming. Surface low pressure will remain nearly stationary along the front ranges of Colorado and Wyoming with robust southerly and southeasterly boundary layer winds continuing. By late afternoon, a dry line will become oriented from the southern panhandle into far southwestern Nebraska. By late afternoon, a strong shortwave will approach the Black Hills and the Nebraska Panhandle. Thunderstorm initiation appears possible INVOF the dry line from the northern panhandle into far southwestern Nebraska. The chance for initiation appears to highest from north to south across the forecast area as mid level temperatures are coolest across the Black Hills and this area is in a more favorable position with relation to an approaching H250 jet streak. That being said, coverage of thunderstorms appears to be best in the north and northeast Friday with more widely scattered to isolated coverage in SW Nebraska. Now, if any storms do develop in SW Nebraska, available CAPE is favorable for severe storms, however, deep layer shear of 50-65 KTS in SW Nebraska may a tad high and may lead to "orphan" storms early on. Not ready to rule out the severe threat in the SW, but it appears to be more focused further east and north of SW Nebraska. Friday night into Saturday, the upper level low will migrate from far western Wyoming into South Dakota. Storms should clear the northeastern forecast area later on Saturday with a On Friday, the upper level low will migrate east from southeastern Oregon into far western Wyoming. Surface low pressure will remain nearly stationary along the front ranges of Colorado and Wyoming with robust southerly and southeasterly boundary layer winds continuing. By late afternoon, a dry line will become oriented from the southern panhandle into far southwestern Nebraska. By late afternoon, a strong shortwave will approach the Black Hills and the Nebraska Panhandle. Thunderstorm initiation appears possible INVOF the dry line from the northern panhandle into far southwestern Nebraska. The chance for initiation appears to highest from north to south across the forecast area as mid level temperatures are coolest across the Black Hills and this area is in a more favorable position with relation to an approaching H250 jet streak. That being said, coverage of thunderstorms appears to be best in the north and northeast Friday with more widely scattered to isolated coverage in SW Nebraska. Now, if any storms do develop in SW Nebraska, available CAPE is favorable for severe storms, however, deep layer shear of 50-65 KTS in SW Nebraska may a tad high and may lead to "orphan" storms early on. Not ready to rule out the severe threat in the SW, but it appears to be more focused further east and north of SW Nebraska. Friday night into Saturday, the upper level low will migrate from far western Wyoming into South Dakota. Storms should clear the northeastern forecast area later on Saturday with a chance of wrap around pcpn lingering into Saturday night across northern portions of the forecast area. As the system exits Saturday into Sunday, gusty westerly winds will be possible Saturday into Saturday night. Winds will relax on Sunday as high pressure builds into the area. Ridging aloft will build into the central plains early next week with dry and seasonal conditions expected through Wednesday. chance of wrap around pcpn lingering into Saturday night across northern portions of the forecast area. As the system exits Saturday into Sunday, gusty westerly winds will be possible Saturday into Saturday night. Winds will relax on Sunday as high pressure builds into the area. Ridging aloft will build into the central plains early next week with dry and seasonal conditions expected through Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 631 PM CDT Wed Sep 20 2023 VFR conditions are expected through the period outside of convection. New development southwest of VTN will threaten the terminal over the next few hours but impacts should remain brief therefore will cover with a tempo group. Impacts are possible at LBF as well, however, may exit the area prior to the beginning of the new forecast period so will limit to VCTS. After convection exits, only passing high clouds are expected with light winds favoring the southeast at less than 10 knots. Expect increasing wind gusts Thursday out of the southeast with peak speeds around 25 knots. Attention turns to addition rain and thunderstorm chances during the late morning and afternoon, particularly for VTN. At this time, greatest confidence in seeing activity remains northwest of the terminal so will omit mention for now but later forecasts may include mention. As low-level winds increase, low to mid level stratus will increase with the greatest impacts likely to occur just beyond the end of the valid period. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...NMJ
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1032 PM CDT Wed Sep 20 2023 .UPDATE... Issued at 825 PM CDT Wed Sep 20 2023 Tweaked PoPs for the rest of the night to reflect current trends. I think the CAMs, particularly the HRRR, are developing too much convection over the next few hours, so I tweaked PoPs downward a category across the entire area. This fades 20-50 PoPs from eastern Missouri into southwest Illinois, and ~60 PoPs across south central Illinois. This corresponds to an area of low level moisture convergence which develops east of the Mississippi River which the RAP develops between now and midnight, and lifts north- northeast through the overnight hours into central Illinois. This area of moisture convergence is also apparent in the GFS, though it develops much less precip than the RAP, and again seems more likely given the current trends. Carney && .SHORT TERM... (Through Late Thursday Night) Issued at 220 PM CDT Wed Sep 20 2023 Compact midlevel low is currently over east-central Missouri. This feature has predominantly been producing very light rain or sprinkles over the past 6-12 hours along/ahead of it, and this should continue through the overnight period. Best chances early this evening for light rain will be along the Mississippi River in eastern Missouri and southwest Illinois, moving northeastward into south-central Illinois gradually through the night. Elevated instability increases overnight so a few rumbles of thunder are also possible. A southwesterly low-level jet strengthens late tonight into Thursday morning, so isolated to widely scattered (15-30%) showers are possible further to the southwest into southeast Missouri and southwest Illinois predominantly. The low- level jet weakens toward 1500 UTC Thursday, so expecting at least a brief period of dry or at least mostly dry conditions across the CWA during the late morning/early afternoon hours. A slight uptick in coverage probably will occur in by mid/late afternoon into the early evening as diurnal instability peaks. This is mainly true in parts of western Illinois which will be on the western periphery of the departing midlevel closed circulation. There is also some slight chances (15-25%) further southwest roughly along a west-east front front. This front is forecast to slowly move northward Thursday night and could help provide the focus for more showers and a few thunderstorms as the low-level jet intensifies and a weak midlevel shortwave approaches from the west. Temperatures are forecast to rebound on Thursday, as thicker cloud cover departs off to the northeast and low-level warm air advection strengthens. Highs are forecast to top out in the mid 70s to low 80s from north to south, slightly above normal for the date. Overnight temperatures will remain on the mild side with lows both tonight and Thursday night in the low to mid 60s. Gosselin .LONG TERM... (Friday through Next Wednesday) Issued at 220 PM CDT Wed Sep 20 2023 (Friday - Friday Night) The retreating warm front may be in at least northern sections of the forecast area Friday morning, but should continue to move north through the day. Attention will then turn upstream as deterministic guidance continues to show signs of a subtle vorticity maximum moving through the region within the quasi-zonal flow aloft. This feature may help yield at least isolated to scattered showers and a few thunderstorms within the warm sector, but confidence is not particularly high in this scenario. Guidance shows building upper-level ridging at least through the first half of the day, which may suppress any development due to increasing subsidence. Six-hour probabilities for measurable rainfall max out in the 30-40% range over most of the area Friday afternoon/evening on the grand ensemble, which looks pretty reasonable. Temperature wise, we are expecting more of the status quo to end the work week. Slightly above normal values are favored, but particularly at night due to persistent southerly winds and at least some cloud cover Friday night. (Saturday - Sunday) Spread in the track and timing of a closed mid/upper level low moving out of the northern Rockies and into the northern Plains this weekend has continued to decrease. By 0000 UTC Sunday, this feature is most likely to be located over the western Dakotas, which is slightly further northwest than compared to what it looked like 24 hours ago. This means a slightly later arrival of the surface cold front into the bi-state area, with an approach into central Missouri most likely between 0600 and 0900 UTC Sunday. Ahead of the front, dry weather is looking more likely with mid/upper level ridging overhead and no real forcing mechanisms to help initiate any convection within the warm sector. Therefore, reduced PoPs quite a bit from the previous forecast, more toward slight chance/low chance (15-35%) which agrees well with latest probabilities from the grand ensemble. Widespread showers and thunderstorms are forecast along the cold front, aided by strong low-level moisture convergence and mid/upper level diffluent flow aloft. However, this area of convection should weaken considerably Saturday night due to a multitude of factors including: 1) waning nocturnal instability, 2) weaker shear (propensity for outflow to outrun storms; cold pool/shear imbalance), 3) abating low-level moisture convergence, and 4) surface cold front becoming less defined by 1200 UTC Sunday/weakening convergence along the front. Some of the rain along with a few thunderstorms are very likely (~80 percent) to reach central Missouri, but chances gradually wane toward and especially east of the Mississippi River. By Sunday morning, there may be some remnant shower or weak thunderstorm activity, but chances should tick up at least slightly by the afternoon as diurnal instability increases. There is some uncertainty as to how well-defined the cold front will be by Sunday afternoon. In fact, some of the latest deterministic guidance suggest the boundary may just wash out entirely. Above normal temperatures will continue ahead of the cold front on Saturday, with highs mostly in the upper 70s to mid 80s. Slightly cooler readings are favored to end the weekend into next week, closer to normal for late September. At least low chances of rain will continue through the period, as a majority of all ensemble members (80%) suggest the closed mid/upper level low will get "trapped" beneath a very anomalous (+3 sigma) ridge centered to its north west of Hudson Bay. This blocking high will at least dramatically slow the eastward progress of the mid/upper level low across the northern Plains/Upper Midwest, and could even send it further to the south closer to our area heading toward the middle of next week. Gosselin && .AVIATION... (For the 06z TAFs through 06z Thursday Night) Issued at 1026 PM CDT Wed Sep 20 2023 Showers continue to rotate around an upper level low which is passing over the Mid Mississippi Valley. VFR flight conditions are expected to continue to prevail outside of these showers. CIGS/VSBYS could drop to MVFR in the heaviest showers across southwest into south central Illinois into early Thursday morning. It is possible, depending on exactly how and where the heavier showers develop, that they could briefly affect the St. Louis Metro terminals, however confidence is low on the precise track of the showers and height of the ceilings, which may pass just east of the Metro Area. After the morning showers exit to the north- northeast, scattered showers will continue to be possible through the day, but VFR flight conditions are likely to continue. Carney && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service San Francisco CA
846 PM PDT Wed Sep 20 2023 ...New UPDATE... .SYNOPSIS... Issued at 1040 AM PDT Wed Sep 20 2023 NW to N winds are bringing wildfire smoke from NW California and SW Oregon to the Bay Area. The HRRR model suggests the smoke will stay with us for the next couple of days. Otherwise conditions will be fairly standard for this time of year through the weekend with morning stratus clearing by mid-day and near normal temperatures. A Red Flag Warning is in effect for the North Bay Mountains tonight into Thursday afternoon. && .UPDATE... Issued at 823 PM PDT Wed Sep 20 2023 Current obs show a mix of wind directions in the North Bay with some onshore flow still present, especially across lower elevations. RDD-SAC pressure gradient strengthening over the past hour, suggesting northerly flow along ridgetops should be imminent within the next couple of hours. RH below about 3200 feet still well into the 60s and 70s south of Lake county and west of the Vaca Range. Above 3200 feet in these areas, such as Mt. Saint Helena, is drier with RH in the 40-50% range. Do expect lower RH values to spread to lower elevations once the northerly winds kick in, likely down to about 1500 feet, roughly where the top of the stable marine layer resides based on the 00Z OAK sounding. Otherwise the forecast and highlights look on track for the winds to decrease Thursday afternoon with good RH recoveries Thursday night/Friday morning. && .SHORT TERM... (This evening through Thursday) Issued at 210 PM PDT Wed Sep 20 2023 Water vapor imagery shows a trough of low pressure moving into the Pacific Northwest this afternoon, with a couple of weak disturbances off the Central California Coast that are finally shifting south as a result. Meanwhile, current visible imagery shows that skies are predominately sunny, except for the immediate coast, which remain blanketed in low clouds. As a result, coastal areas are running between 5 and 10 degrees cooler at this time than this time yesterday, while inland areas are for the most part similar to their temperatures yesterday. Another area of interest for today remains with the smoke that has filtered into the area from our north. At this time, the majority of our observing stations are reporting visibility between 4 and 6 statue miles in either haze or smoke. Given that the upper level north to northwesterly flow will continue through the next 24 to 48 hours, expect the smoke from the fires in Northwestern California and Southwestern Oregon to continue to filter into the area. Meanwhile, the weather main story for tonight and tomorrow will be the developing offshore winds across North Bay. At this point in time, the models are showing that the northerly gradient will increase this evening, and then peak during the late night and early morning hours. The 925 mbs winds increase to between 25 to 35 kts tonight between 9z and 12z, with 850 mb winds not quite as strong. At this point in time, think some local gusts upwards of 45 mph will be possible at the gustiest locations over the peaks. Given the lack of upper level support, not expecting these winds to mix down into the valley tonight. In fact, valley locations will likely be dealing with our marine layer low clouds, as the Fort Ord profiler is showing that the marine layer is around 2500 feet deep this afternoon. The offshore winds will weaken during the day tomorrow, but still expect dry conditions to prevail across the higher elevations. Otherwise, expect conditions to be similar to or slight cooler for the day on Thursday. Palmer && .LONG TERM... (Thursday night through next Tuesday) Issued at 210 PM PDT Wed Sep 20 2023 Overall temperatures trending cooler than average through Tuesday with highs expected to be in the mid to high 70`s inland and high 60`s along the coast. Weak upper-level shortwave ridging will warm temperatures slightly on Saturday/Sunday but temperatures are only expected to be a few degrees higher than the rest of the period. As the shortwave ridge moves in overnight Thursday and during the day on Friday, wind directions will shift from northwesterly to westerly/southwesterly. This will help to clear smoke out of the Bay Area. Confidence is increasing that North Bay will experience some precipitation between Monday and Tuesday. There is continued potential for South Bay to receive some rainfall as well however confidence is lower for South Bay than it is for North Bay. Model guidance suggests that the most likely timing for precipitation will be overnight Monday into Tuesday but beyond this the exact timing and amount are still unclear. We will continue to watch this system to see how it will develop. && .AVIATION... (00Z TAFS) Issued at 647 PM PDT Wed Sep 20 2023 Wildfire smoke and haze continue to mix with coastal stratus, per metar observations surface visibilities are 5-9 miles /MVFR-VFR/ and ceilings vary from 1600 ft to 2000 ft /MVFR/. The marine layer depth varies from 2100 ft Bodega Bay, 2900 ft Fort Ord to 2700 ft Point Sur. A 4.2 mb ACV-SFO pressure gradient is juxtaposed to a 3.1 mb SMX-SFO pressure gradient (both are underforecast by the latest NAM and HRRR models approx 1 mb and 2 mb respectively), SFO-SAC is onshore 2.4 mb. Pressure gradients initiate atmospheric motion effecting near surface to surface winds and in this case the advection of current stratus. Stratus clouds continue converging along the coast from Point Reyes to Point Conception, the larger scale pattern forecast to arrive from the northeast blending in with the coastal stratus pattern overnight. 00z TAFs are adjusted to account for underforecast gradients and winds, a very challenging forecast, for example near 3 mb SNS-SJC pressure gradient currently, yet there`s still a northwest wind 10 knots at KSJC (vs southeast wind which is forecast to develop early this evening, PG&E weather stations show southeast winds nearby). As best can tell from model forecasts low level wind shear (LLWS), including across the North Bay should be minimal tonight and Thursday morning, thus at present time LLWS was not added to KSTS, KAPC 00z TAFs. Vicinity of SFO...VFR. Southwest wind 10 to 13 knots early this evening, surface wind shifting to a light southeast wind by mid to late evening; still waiting for KSJC wind to shift to southeast direction. With surface cyclonic wind flow west of the SF Peninsula early Thursday morning, wind shifting to light northeast direction then by late afternoon shifting over to west wind near 10 knots, though the late afternoon wind shift is a low confidence forecast. SFO Bridge Approach...Reductions in slant range visibility due to wildfire smoke and haze continuing, especially during sunset and sunrise. Otherwise similar to KSFO. Monterey Bay Terminals...MVFR-VFR and visible satellite imagery shows stratus curling around the Monterey Bay reaching over to KWVI and KSNS, while ongoing southwest wind & downsloping drying wind at KMRY keeping VFR going so far. The marine layer depth per Fort Ord and gradually easing southwest wind will eventually allow stratus clouds /MVFR/ to reach KMRY, tempo MVFR 02z-05z this evening. Otherwise KSNS already with MVFR stratus ceiling this evening and a northwest wind. Stratus filling across the north Central Coast, a favorable area for gradually arriving lower level cooling, a greater deepening of the marine layer and mixing out the lower level temperature inversion, including /not currently in 00z KMRY or KSNS TAFs/ patchy light drizzle with upslope cooling winds tonight and Thursday morning. && .MARINE... (Tonight through next Monday) Issued at 541 PM PDT Wed Sep 20 2023 Strong northerly winds today in the coastal waters with frequent gale force gusts anticipated in the northern outer waters. Winds and gusts will begin to diminish Thursday, becoming light to moderate by the weekend. Northwesterly swell begins to diminish on Thursday, with a new swell train arriving late in the weekend. && .FIRE WEATHER... Issued at 1040 AM PDT Wed Sep 20 2023 The Fire Weather Watch has been upgraded to a Red Flag Warning from 11 pm tonight to 5 pm on Thursday. As a deep upper low drops into interior CA from the Pacific NW, it will set up a short window for some offshore winds early AM hours on Thursday. Peak winds will be overnight tonight into Thurs morning with winds of 10 to 20 mph and gusts up to 30 mph. Relative humidity values overnight will be marginal and not critically low, making this a marginal case. By the morning, RH will drop to 25-30% in conjunction to breezy north winds. Winds turn onshore during the afternoon Thurs when RH drops further into the low 20s. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Red Flag Warning until 5 PM PDT Thursday for CAZ504. PZ...Small Craft Advisory until 9 PM PDT this evening for PZZ540. Gale Warning until 9 AM PDT Thursday for PZZ570. Small Craft Advisory until 3 AM PDT Thursday for PZZ575. && $$ UPDATE...Behringer SHORT TERM...Palmer LONG TERM....Kennedy AVIATION...Canepa MARINE...DialH Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/nwsbayarea www.twitter.com/nwsbayarea www.youtube.com/nwsbayarea
Area Forecast Discussion
National Weather Service Paducah KY
620 PM CDT Wed Sep 20 2023 .UPDATE... Issued at 609 PM CDT Wed Sep 20 2023 Updated aviation discussion for 00z TAFs. && .SHORT TERM...(Tonight through Friday night) Issued at 251 PM CDT Wed Sep 20 2023 Rain continues to inch closer to the region, reaching the far western counties this afternoon. Surface high pressure and weak forcing aloft has kept heavier rain out of the forecast and appears to be somewhat verified today. RAP soundings have shown relatively dry air aloft in and around this weak system. No significant moisture is being observed to promote higher confidence in heavier rain as the precipitation travels east. Therefore, expect light showers to move east throughout the CWA this afternoon through tonight with light accumulation of less than 0.1". Tomorrow morning should yield drier weather as the main frontogenetic forcing moves off to our north and east. However, there is a chance the vorticity maximum associated with this mid level disturbance might retrograde west to the north of the CWA. This would keep some higher PoPs in our northern counties throughout the day tomorrow, but no significant precipitation amounts are expected. Temperatures will likely be in the low 80s in the east with upper 70s across areas that experience more cloud cover and rain. General high pressure should eat away at the strength of this disturbance into Thursday night and Friday morning with 500mb height rises helping clear out any precipitation. Some stubborn cloud cover might still exist due to lingering moisture in the wake of precipitation-driven wet bulbing. Nonetheless, the main headline for Friday is that the weather should be dry with temperatures in the mid 80s. .LONG TERM...(Saturday through Wednesday) Issued at 251 PM CDT Wed Sep 20 2023 The ridge strengthens slightly on Saturday keeping us mainly dry with continued lower to mid 80s. Then as the northwestern low moves east over the Northern Plains and Northern Midwest precip chances begin to increase Saturday evening onward. Things get a little more uncertain from there as the low lingers but the exact placement is uncertain. The EC moves the low south and east over our area by Wednesday whereas the GFS keeps it over the Great Lakes. Temperature wise we start to cool down on Sunday with highs back down into the 70s by Monday. Lows will generally still be in the 60s. && .AVIATION... Issued at 609 PM CDT Wed Sep 20 2023 Scattered light showers will continue to drift NNE this evening and overnight. Can`t completely rule out an isolated lightning strike. Some of this activity may linger into the first half of the day tomorrow across mainly northern terminals. A few of the heavier showers may produce very brief vsby reductions. Otherwise, VFR conditions expected with primarily a mid cloud deck around 5-10kft. Some guidance is suggesting a little fog development possible across southeast Missouri late tonight. There`s low confidence in this though, and it`s contingent on clouds clearing enough and winds becoming calm. Winds will range from easterly to SSE and primarily between 4-8 kts through the period. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...SP SHORT TERM...SHAWKEY/JAB LONG TERM...SHAWKEY AVIATION...SP