Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/12/21

National Weather Service Albany NY
945 PM EDT Sat Sep 11 2021 .SYNOPSIS... Dry and tranquil conditions to prevail through tonight. A warmer and more humid airmass will arrive Sunday ahead of an approaching cold front. The cold front is expected to bring scattered showers and thunderstorms Sunday into Sunday night. Some thunderstorms could become strong to severe with locally heavy rainfall. Following the passage of the cold front, dry weather briefly returns to the area on Monday before another round of showers and thunderstorms arrive Tuesday into Wednesday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... UPDATE...Generally clear skies as winds have generally decoupled across the region. Did make some adjustments per NY Mesonet and METAR observations with wind, temperature, dewpoint grids. Also, minor update to overnight lows as a few areas across the terrain have already attained the expected low temperatures. Overall, a quiet forecast overnight. Some increase in cloud coverage is expected over the Adirondacks late. Prev Disc... Tranquil conditions expected this evening as high pressure shifts eastward off the Mid Atlantic coast, with just some patchy mid/high level clouds around. Temperatures will be cooling into the upper 50s to lower 60s prior to midnight. A slight southerly breeze will continue overnight, resulting in better mixing in some spots. High and mid level clouds will also increase after midnight associated with an upper level trough moving eastward through central/southern Quebec, so temperatures will not be as cool as last night with mainly mid/upper 50s for lows. A cold front will be approaching from the St. Lawrence valley, which could bring a few showers to the western Adirondacks late tonight. Fog is generally not expected due to increasing clouds and the southerly breeze. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... The main concern in the short term will be the potential for strong to severe thunderstorms and locally heavy rainfall late Sunday afternoon into Sunday night. Our region will be in a zonal westerly flow aloft Sunday into Sunday night. At the surface, a cold front will gradually be moving southward across the area but is expected to slow its southward progress as the flow aloft becomes parallel to the front. The front may stall around or just south of I-90 late Sunday. Forecast soundings indicate fairly strong capping through much of the day, so chances for thunderstorms should remain fairly low until late afternoon to early evening. Temperatures will warm well into the 70s with even lower 80s south of Albany ahead of the cold front. Cooler 60s for the western Adirondacks where the cold front will pass through earlier. Dewpoints are forecast to rise into the mid 60s along and ahead of the front, signaling a return in humid conditions. The cap will erode Sunday evening, as an upper level disturbance moves through from west to east. Latest CAMs indicating potential for multiple rounds of convection focused along and south of the front late Sunday into Sunday night. Potential for severe storms continues to increase, as guidance indicating enough instability (HREF mean MUCAPE of 700-1500 J/Kg from around I-90 south) and abundant 0-6 km shear of 40-50 kt for storm organization and upscale growth. Main threat looks to be damaging wind gusts, although hail will be possible with 700-500 mb lapse rates of around 6-7 degC/Km forecast. At this time there doesn`t appear to be enough buoyancy for large hail but will continue to monitor trends. Also of concern will be potential for locally heavy rain with possible convective cells repeatedly moving over the same areas. PWAT anomalies forecast from the NAEFS to increase to +1 to +2 STDEV, so will have to watch for isolated flash flooding in addition to severe threat. Main time frame for strongest storms looks to be from early Sunday evening through a few hours after Midnight. As with most convective situations, there are some timing differences in the guidance with the HRRR showing the greatest threat around 8 PM to 1 AM, while the NAMNest is later around 10 PM to 3 AM. With zonal flow aloft, confidence is fairly low with regards to timing, but higher for storm potential and impacts. At this time most of the region from around I-90 and Capital District south is in a Marginal Risk Outlook, with a Slight Risk in the eastern Catskills, but will monitor for possible eastward expansion of the Slight Risk area in subsequent outlooks. At this time Monday looks to be a tranquil day, with subsidence and northwest flow in wake of Sunday night`s cold front/upper level disturbance passage. Temperature will be cooler, but still near normal for mid September with highs in the mid 60s(mountains) to mid/upper 70s(valleys). A surface anticyclone is expected to build eastward across southern Quebec into northern New England Monday night providing mainly dry/seasonable conditions. However, some guidance showing a few showers developing north of the stalled front. Will just mention slight/low chance pops south of Albany at this time. With surface winds expected to become light, patchy fog will be possible in favored sheltered valleys and locations near bodies of water north of Albany. && .LONG TERM /TUESDAY THROUGH SATURDAY/... It appears out long term forecast will be quite active as autumn attempts to make some inroads across the northern Conus and summer hanging on across the southern portions of the Conus. At this time, seems the northeast and middle Atlantic will be the dividing zone with active weather. The other concern is ongoing/developing tropical activity in the Gulf of Mexico and just eastward of the Bahamas. Tuesday, per global model consensus, our frontal zone to the south of the region is forecast to return back as a warm front as upstream potent jet approached the western Great Lakes. Main question is will there be enough lift for elevated or even surface based convection to develop during the afternoon hours. As it is a non- zero probability, we will place higher PoPs just to the northwest of Albany which would be closer to upper support and stronger low level jet support. Highs climb well into the 70s with dewpoints climbing back into the 60s. Tuesday night into Wednesday night, this appears to be the most active portion of the long term forecast. The aforementioned warm front is expected to rise northward as surface low tracks across southeast Canada. Its associated cold front remains upstream Tuesday night and begins the approach during Wednesday. A rather warm, humid and unstable air mass is expected across the region. A noticeable low level jet with magnitudes at or above 25kts is progged along with dewpoints well into the 60s ahead of this cold front should result in a line of convection(s). At the moment, this frontal boundary is expected to drop southward Wednesday night. However, the large unknown at the moment will be what if any tropical activity will have on the synoptic environment across the region. If something were to develop in the Gulf, potential for some of this moisture to become entrained within the southwesterly flow. If something were to develop off the southeast coastline, this too will have some potential impact with a slower frontal progression than currently forecast. This too will have implications Thursday into Friday with a very low confidence forecast at this time. So we followed a combination of ensemble MOS and WPC forecast synoptic features with a slight chance to chance of showers/t-storms with near to above normal temperatures. For information on the tropics, please refer to the latest information from the National Hurricane Center (NHC). && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Through 00z Monday...Near ideal flight conditions this evening with VFR category through tonight. Southerly winds will prevail as well with speeds around 10kts or less. LLWS will increase ahead of the approaching frontal system from the west and north. Some increase in high and mid level cloud cover expected later tonight. Through Sunday, combination of increasing humidity and low level jet, the threat for convection increases Sunday afternoon. While VFR conditions should prevail through most of the day, chance of convection will increase the potential for MVFR conditions in the afternoon. Outlook... Sunday Night: High Operational Impact. Definite SHRA...TSRA. Monday: No Operational Impact. NO SIG WX. Monday Night: Low Operational Impact. NO SIG WX. Tuesday: Moderate Operational Impact. Chance of SHRA. Tuesday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Wednesday: Moderate Operational Impact. Likely SHRA...TSRA. Wednesday Night: Moderate Operational Impact. Chance of SHRA. Thursday: Moderate Operational Impact. Chance of SHRA...TSRA. && .FIRE WEATHER... Dry and tranquil conditions to prevail through tonight. A warmer and more humid airmass will arrive Sunday ahead of an approaching cold front. The cold front is expected to bring scattered showers and thunderstorms Sunday into Sunday night. Some thunderstorms could become strong to severe with locally heavy rainfall. Following the passage of the cold front, dry weather briefly returns to the area on Monday before another round of showers and thunderstorms arrive Tuesday into Wednesday. Relative humidity values will increase to between 75 and 95 percent tonight. Relative humidity values will drop to minimum values of around 55 to 75 percent Sunday afternoon. RH values will increase to between around 100 percent Sunday night. Winds tonight will be south-southwest around 5 to 15 mph, becoming southwest at 10 to 15 mph on Sunday with gusts of 20 to 25 mph. Winds Sunday night will shift to the northwest around 5 to 10 mph. && .HYDROLOGY... Dry conditions expected to prevail through tonight into Sunday morning, except for a few showers well north and west of Albany. Showers and thunderstorms will develop ahead of a cold front late Sunday afternoon into Sunday night. Anomalously high moisture will be in place. Some areas could see repeated rounds of thunderstorms with downpours, which could result in poor drainage flooding of urban, poor drainage and low lying areas as well as isolated flash flooding. Drier weather is expected on Monday, followed by renewed chances for showers and thunderstorms Tuesday into Wednesday as a frontal system moves across the region. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Evbuoma/JPV NEAR TERM...BGM/JPV SHORT TERM...JPV LONG TERM...BGM AVIATION...Main/BGM FIRE WEATHER...Evbuoma/JPV HYDROLOGY...JPV
Area Forecast Discussion
National Weather Service La Crosse WI
959 PM CDT Sat Sep 11 2021 .SHORT TERM...(Tonight through Tuesday) Issued at 210 PM CDT Sat Sep 11 2021 Cold front slipping south/southeast across the region later this afternoon/evening...roughly along/south of I-90 around 00z. Ample low level warming (+13 C 700 mb ahead of the boundary) will keep the atmosphere deeply capped with not enough forcing from the front to spark any convection through the afternoon/early evening. With the stable layer extending upwards of 700 mb, the usual standbys for nocturnal convection of 850 mb jet/moisture transport won`t help. Looking higher a loft, RAP 700 mb winds/moisture transport does show the potential for a sheared ribbon of convergence roughly around I- 90, kicking in near 05z. Some sloping frontogenetic lift north of the sfc front could support this area. Might be enough to kick off isold/scattered convection. Beefy instability aloft is on the wane by that time, but enough that if storms due manifest, a few could become strong with a hail threat. Minimal wind shear support (perhaps 30 kts in the 2-7 km layer). The front sets up shop west to east across southern IA/northern IL for Sun/start of the new work week. Bits of upper level energy could traverse eastward, north of the front, providing enough lift for a few showers/isold storms. Along and south of the front remains capped off. Better chances will be tied to an upper level shortwave trough which the NAM/GFS/EC bring across the region Mon night/Tue morning. Bulk of the upper level energy could hold across northern portions of MN/WI, but the system will drag a cold front along with it, providing another means of lift. Low level moisture transport will help fuel the chances. Progressive system, and most of the rain threat could/would exit east/south of the local area by the afternoon. That said, if it`s a bit slower, convection could respark along the front with the aid of afternoon instability...potential impacts for northeast IA into central WI. Severe threat looks minimal at this time. After a summery day of highs in the 80s and relatively high humidity, the colder/drier post the front will round out the weekend on a rather cool note. Highs closer to 70 - roughly 10 to 15 degrees cooler than today - with much less humidity. .LONG TERM...(Wednesday through Saturday) Issued at 210 PM CDT Sat Sep 11 2021 Quick moving, zonal flow a loft is promised by the GFS and EC for much of the new week. A few shortwave troughs could slip through bringing rain chances, with Thu/Thu night currently showing the most promise. Both the GFS and EC drive upper level energy across the northern plains Thu night, with a cold front well ahead of it. Low level moisture transport northward into the boundary could fuel areas of showers/storms. The GFS hints at a bit of shortwave energy moving in from the southwest, ahead of the front and northern trough. The EC doesn`t depict this and GEFS ensemble members show little support. Looks like an outlier at this time. Will keep with blend for now. A smattering of rain chances after that, mostly with lingering frontal boundary and weak ripples a loft. No clear signal on where/when for any chance greater than a 20/30. Looking for a dry day? Wed looks to be the day with high pressure moving overhead post the Tue system. Temperatures could take a brief upswing back to summer for the following weekend with both models suggesting some shortwave ridge building. Any warm up looks brief, currently centered on Sunday (mid-upper 80s?). && .AVIATION...(For the 06Z TAFS through 06Z Monday morning) Issued at 1000 PM CDT Sat Sep 11 2021 Continuing to monitor rain chances developing late this evening into the early morning hours of Sunday. Weak forcing behind a cold front stalled well south of the TAF sites may trigger scattered showers overnight - already seeing a few elevated radar returns to the north (not yet making it to the ground due to dry low levels). Weak moisture transport is contributing to a developing VFR stratocu deck south of I-90 at this hour. Hi-res models show that cloud deck thickening/expanding slightly as we approach 06Z with potential for showers developing thereafter. There is a conditional threat for a thunderstorm as well, with plenty of instability aloft. However, weak forcing is expected to limit the likelihood of storms the rest of tonight. Hi-res models suggest shower activity will be mainly focused just north of the TAF sites and the I-90 corridor through daybreak, so have maintained VCSH. The low levels dry out again to some extent by midday Sunday. While some weak energy aloft will ripple overhead during the day and potentially generate additional rain chances, it`s doubtful any rain chances would manifest as anything more than sprinkles or a brief shower at the TAF sites so have continued VCSH for now. Winds generally north to northeast through the period around 10 knots or less. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Rieck LONG TERM....Rieck AVIATION...Kurz
And with that, I conclude my final forecast discussion as a
National Weather Service meteorologist. I`m honored to have
served my community and worked with the finest minds and friendliest men and women of the scientific community. It has been a wonderful three decades. - Dan Padavona Mid-Atlantic River Forecast Center June 1994 to August 1995 NWS Taunton MA August 1995 to January 1996 NWS Binghamton NY January 1996 to September 2021 345 PM Update... Ridging over the region flattens out tonight and a cold front will drift southward out of Ontario, Canada and with zonal flow developing. The flow becomes zonal with strong westerlies aloft pushing eastward over New York. The aforementioned cold front eventually makes it over Central NY and stalls. It is still unclear exactly how far south this front will make it, but it will be the focus of strong to severe thunderstorms Sunday evening as a short wave pushes eastward out of the Great Lakes. Models are currently showing convection developing across Michigan tomorrow afternoon. As short wave pushes east, it will encounter an EML plume over Michigan/Great Lakes Region, with steep mid level lapse rates over 8C/km. How this convection evolves will determine the severe threat in our area tomorrow evening/night. A strong MCS may develop and track along the axis of the front and across Central NY and the Southern Tier. Damaging winds will be the main threat from this MCS. Also, PWATs climb to about 1.75" and the mean flow will be aligned with the front with short Corfidi vectors that may support backbuilding/training convection and localized flash flooding will be possible. Have significantly increased thunderstorm chances for tomorrow evening, and some areas may see localized rainfall amounts over 2". What remains a bit uncertain for tomorrow is how far south the front will make it, and thus where exactly does this corridor of heavy rain/thunderstorms track. Model guidance is now clustering most of the activity between the Southern Tier and the NYS Thruway Corridor, so that is where the highest PoPs are at this time. && .SHORT TERM /MONDAY THROUGH TUESDAY/... An active pattern sets up through the short term period as a series of disturbances run through mainly zonal flow across the Northeast. On Monday, there`s some uncertainty early in the morning for lingering showers behind one passing wave that is likely to have brought showers in overnight Sunday-Monday. Will leave a short period of chance PoPs from 12Z-15Z before being fairly certain that most of the remainder of the day will be precip free as we get between waves with some high pressure nosing in from Quebec. Then, later in the afternoon into Monday night, another upper wave will approach the region offering another chance at showers and thunderstorms. There will also be a warm front lifting into WNY and NWPA to provide low level support. The upper feature will again be moving quite fast through the area within the stout jet level flow and it seems likely that PoPs will be lowering by Tuesday morning. On Tuesday, an upper midwest/south central Canada system will lead to increased low-level southwesterly flow, enabling a northward push to the low-level warm front into northern NY and New England by Tuesday night. Increasing low-level convergence and instability is expected as we break into the warm sector. Surface based CAPE is juiced up into the 1500-2500 J/kg by both the 12Z NAM and GFS models which is an uptick from previous runs. 0-6 km bulk shear will be around 25 to 35 knots. Given the uncertainty in the timing crossing the late afternoon/night threshold, we will stick with mainly chance POPs for showers and storms, especially in central NY to Catskills where front will be moving through. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... The upper midwest/central Canada system progresses east on Wednesday with the cold front moving through region during the prime time of day. It will have good instability and bulk shear to work with leading us to believe the day will be moderately active with showers and thunderstorms. NBM continues to suggest likely PoPs and this seems reasonable that many areas will see at least showers. Could be a rather stormy afternoon with the heating providing fuel for sustained thunderstorm activity. The frontal system looks to hang up over northern PA, or possibly even south central NY for Wednesday night and Thursday. The remainder of the week looks quite uncertain with the near stationary front lingering in the area into Friday, followed by models suggesting a tropical system lurking to our south and being off the DelMarVa coast on Friday...then slowly moving north into saturday. The GFS captures the low near Cape May as it gets stuck beneath surface high pressure over New England, while the ECMWF is more progressive to kick the feature out to the east. Regardless of which scenario plays out, we would still have to deal moisture interacting with a cold front approaching from lower Ontario and unsettled conditions would be the case for late week. Chance PoPs carry us through much of this period with mild and muggy conditions. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... VFR conditions are expected through the majority of the period, though some restrictions will be possible at some of the NY terminals during the second half of the period. LLWS is expected tonight, beginning between 03 and 05z at all terminals and lasting until 11 or 12z. AVP is the exception as LLWS is only expected for a short period of time. Some rain showers will be possible at SYR and RME tomorrow morning beginning around 09z, but confidence was too low to include at SYR at this time. SYR and RME will also fall to Fuel Alt tomorrow afternoon as ceilings drop ahead of an approaching cold front. Ceilings are expected to lift near the end of the period. Storms will be possible at ITH near the end of the period. SYR and RME could also see some storms, but confidence is too low at this time to include in the TAFs. For now, no restrictions are expected but winds could be gusty in the storms. Winds throughout the period are going to remain gusty with gusts of 15 to 20 kts possible through the majority of the period. Winds become calmer tomorrow evening. Outlook... Sunday Night...There is potential for thunderstorms across central NY late Sunday night into early Monday morning and brief restrictions will be possible. Monday through Thursday...Chance for some scattered showers and thunderstorms each day, especially during the afternoons. Brief restrictions possible, but otherwise mainly VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...MPK NEAR TERM...DJP/MPK SHORT TERM...JAB LONG TERM...JAB AVIATION...BTL/MPK
Area Forecast Discussion
National Weather Service Des Moines IA
626 PM CDT Sat Sep 11 2021 ...Updated Aviation Discussion... .DISCUSSION.../Today through Friday/ Issued at 231 PM CDT Sat Sep 11 2021 Forecast Highlights: -- Temperatures approach records this afternoon -- Periodic storm chances tonight through early next week -- Briefly cooler on Wednesday, then heat and storms return Details: It is a hot and humid September day across the state with the only saving grace being patchy broken clouds over northern Iowa and high level smoke across the state. While there is an opaqueness to the sky aloft over central Iowa, the highest concentration of smoke via GOES-East GeoColor is shown over eastern Iowa and south into Missouri. This smoke and clouds will keep temperatures a few degrees from their full potential and in line with midshift`s forecast as well. This hot and humid weather is ahead of a front, which has made its way into northern Iowa and is near or just north of Spencer, Algona, and Mason City. The drier air/lower dewpoints are lagging behind the boundary with the above mentioned sites still around 70 degree dewpoints. While forecast soundings have shown that mixing today is limited due to the inversion aloft (700mb temperatures around 14C), drier air has not mixed down as of yet this this afternoon. The HRRR and RAP continue to show middle 60 dewpoints by late this afternoon as drier air mixes down. The end result -- whether that is because the temperatures are lower and the dewpoint is higher or temperatures are higher and dewpoints are lower -- will be a heat index peaking in the upper 80s over northern Iowa and 90s elsewhere. Tonight into early next week, the boundary will remain over the region with fast, zonal flow impinging and eventually settling through the state. For tonight, the boundary will remain over the northern part of the state and the 850mb low level jet will increase over Iowa into Minnesota. Most guidance shows any isolated storms relegated to areas north of Iowa, but have kept low end PoPs over northern Iowa tonight into early Sunday. As a shortwave trough moves across region with the boundary still over northern Iowa, there should be a slightly higher chance of some showers and storms Sunday night. Any storms would be elevated with a very low severe risk given the strong deep layer shear, but weak instability via plane view and soundings. The boundary wavers northward on Monday in advance of another shortwave trough advanced from the west. While the highest storm chances will likely be north of Iowa Monday night in conjunction with the shortwave`s path, some storms may cross over northern Iowa. Further, the boundary will be pushed back into the state yielding scattered storm chances Monday night into Tuesday and eventually moving out Tuesday night into Wednesday. The 00z/12z Euro and 12z CMC remains faster compared to the 00z/12z GFS and the 00z CMC. So, while there is a period of PoPs Tuesday night into Wednesday, if the faster solution becomes more likely will be able to shorten that period. High pressure will settle in behind this boundary with more seasonable temperatures. However, those will be short-lived as southwesterly flow develops ahead of a more significant long wave trough that will move over the Canadian provinces into the northern states. This will result in highs back above normal by late in the week with storm chances returning to the forecast. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 623 PM CDT Sat Sep 11 2021 VFR conditions can be expected throughout the TAF period. Some weak mixing should diminish by 03z or sooner. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...Ansorge AVIATION...Podrazik
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1151 PM EDT Sat Sep 11 2021 .AVIATION... Strong upper level low pressure tracking across far northwestern Ontario has led to stout geostrophic southwesterlies across Southeast Michigan. Dynamic upper level jet packet will cruise eastward this evening creating the impetus for a surface cold front to push southward across the Straits region and through Lower Michigan overnight. Isolated convective showers have only now developed along this front near the Tip of the Mitt and over the northern Lake Huron basin. Convergence axis will sag southward throughout the evening with potential for shower/tstorm activity remaining to the north and east of the terminals across the Thumb and Lake Huron. Cold advection in the wake of the front will lead to some saturation and MVFR stratus development at MBS and FNT. The front will stall out invof PTK on Sunday. Winds are expected to become variable or light westerly along the front with southwesterly winds 10 to 20 knots at DTW. A secondary jet max will then bring a period of frontogenesis Saturday afternoon. Uncertainty exists on likelihood for shower and thunderstorm development Saturday afternoon. Low confidence in spatial details but the most probable location would be on the cool side of the frontal zone across the northern cwa. .DTW THRESHOLD PROBABILITIES... * Low for ceilings AOB 5kft Sunday * Low for thunderstorms late Sunday afternoon && .PREV DISCUSSION... Issued at 315 PM EDT Sat Sep 11 2021 DISCUSSION... Surface high pressure system has gradually meandered east across the Mid-Atlantic South, while a strong low pressure system continues to travel east across Ontario through the afternoon. Return flow from the high and increasing proximity to the low pressure system has resulted in a slight backing of surface and low-level flow, along with a tightening of the pressure gradient and uptick in wind speeds aloft. Diurnal mixing and the enhanced gradient will continue to promote breezy conditions through the remainder of the afternoon and evening, with southwest gusts around 25-30 mph. Warm air advection also remains underway with h850 temperatures now residing between 13- 16C. This has allowed for a nice warm up of surface temperatures back into the lower 80s. Strongest surge of waa pushes across SE MI late tonight and overnight, with h850 temperatures rising around 16- 18C between 00Z-12Z Sun, while h700 temperatures surge to a seasonally impressive 8-12C. Enhanced capping and antecedent dry conditions has and will continue to produce nil weather for the remainder of the afternoon and evening. Overnight temperatures will remain mild across the Metro region and south into the Ohio border, with lows holding in the mid to upper 60s. Progression of the Ontario low will draw a cold front across northern lower Michigan between 00Z-04Z, before driving south across the Tri-Cities and northern Thumb closer to 06Z, while an enhanced jetlet at h700 sags south with the front. Frontal forcing and right entrance dynamics will produce the chance for showers and thunderstorms over this area given the building mid-level lapse rates aoa 7 C/km and waning CAPE around 500 J/kg. HRRR suggests elevated thermal profiles will limit convection and produce more of an elevated threat, while the NAM is slower with the waa, thus better capping holds until after 06Z. Overall, the risk for stronger storm development looks limited over the northern Thumb especially given the unfavorable time profile of storm development, but cannot totally rule out an isolated gust to 60 or hail to an inch along the boundary given the sufficient effective shear in place. The cold front will continue to push into southern lower Michigan before stalling on Sunday afternoon while brisk westerly flow aloft holds over southern Michigan. This will invoke positive theta-e advection of northern Plains origin and will draw moisture-rich air over the cwa through the entirety of the day. Isolated to widely scattered showers and thunderstorms will be possible along the baroclinic zone with strong mid-level lapse rates holding in place. Shortwaves rippling across relatively zonal flow across Wisconsin could also aid in developing and pushing showers and thunderstorms from the west through the afternoon. This shortwave feature will draw across SE MI around and after 21Z while low-level convergence enhances slightly with a southward push of the front. This will bring better coverage of precipitation (widely scattered to numerous) along and especially north of m59. Theta-e axis and shortwave features will hold through Monday morning, bringing the continued chance for shower and storm potential through late Monday morning. This is a well capped high shear low SBCAPE regime and thus most activity is expected to remain elevated, however, SWODY2 places a marginal risk north of I-94 with the thinking that some organized convection will be possible coming in from Wisconsin given the high effective bulk shear under the energetic mid to upper-level flow scheme. Hail to an inch and some isolated damaging wind gusts would be the main concern for stronger organized convection. Otherwise, temperature highs will be variable across SE MI, with temperatures rising firmly into the 80s in the warm sector (making a run towards 90 closer to the MI/OH border), and will hold in the lower 70s across the Tri-Cities and northern Thumb. Less certainty exists for temperatures highs closer to the stalled frontal boundary, given boundary placement, cloud cover, and rain chances. The uncertainty is observed in the NMB interquartile range where a +/- 9 spread potential exists across Pontiac up to Flint, with potential highs ranging between 78 to 87 & 75-84, respectively. An active pattern will hold through the midweek period as the stalled frontal boundary again holds near the MI/OH border for the first part of the day on Monday before pushing north late Monday into Tuesday as low pressure pushes northeast into the Midwest. Precipitation chances will hold across the Tri-Cities and Thumb given the better proximity to the front. This system will continue northeast into northern lower/U.P late Tuesday into Wednesday, eventually drawing a cold front across Southeast Michigan, bringing continued rain and thunderstorm chances for all of SE MI. MARINE... Tightened pressure gradient keeps southwest winds sustained around 15-20 kts, with gusts to 25 kts along the nearshore waters through the evening. Strongest gusts to be felt closest to the shoreline, as offshore flow combined with better mixing depths allows stronger winds to reach the surface. Cold front still on track to drop through the region late tonight, with isolated shower/thunderstorm activity along the boundary and a shift to lighter winds from the northwest. The front then stalls across southeast lower MI, setting the stage for additional thunderstorm development tomorrow afternoon and evening, in which briefly enhanced winds and waves will be possible. Expect periodic rain chances to continue through early next week as additional disturbances track along the lingering frontal boundary. HYDROLOGY... A stalled frontal boundary will produce isolated to widely scattered showers with some thunderstorms starting throughout Sunday morning and afternoon. An uptick in coverage is expected mainly north of m59 throughout Sunday afternoon and evening. Any repeated rain and thunderstorm activity will have the potential to produce between .25 to .75 inches of accumulation. Any repeated stronger thunderstorm activity has the potential to produce localized higher amounts between 1-2 inches north of m59 through late Sunday evening. Poor drainage and urban flooding will be possible with this activity. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....CB DISCUSSION...AM MARINE.......MV HYDROLOGY....AM You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Green Bay WI
628 PM CDT Sat Sep 11 2021 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Sunday Issued at 222 PM CDT Sat Sep 11 2021 The latest RAP analysis and satellite/radar imagery show a cold front stretching across west-central to far northeast Wisconsin early this afternoon. Surface temperatures are lagging behind the projected heating curve so far today, which has inhibited convective cloud and instability development. As a result of poor low level lapse rates, the shower and storm threat looks low enough to remove from the forecast for all areas except for far NE WI where moisture convergence is the highest and cu looks the most bubbly. As this front continues to move into southern WI, thunderstorm chances remain the focus for tonight and Sunday. Tonight...The cold front will continue to slowly move south where it will stall across southern Wisconsin. Meanwhile, a shortwave currently over Montana will track east into the northern Mississippi Valley after midnight. Slight backing of the winds aloft will likely lead to ascent over the stalled front across southern Wisconsin. Central WI south of HWY 29 will likely be on the northern fringes of any shower/storm development after 4 am. Elevated instability less than 1000 j/kg and relatively weak ascent could lead to a few storms, but the severe weather threat appears low. Cooler temperatures are expected due to northeast winds, with lows ranging from the upper 40s north to low 60s south. Sunday...The chance of showers and a few storms will continue south of HWY 29 during the morning, before exiting east in the afternoon. Instability is even less than overnight, so again, the risk of severe weather appears low. Over northern WI, partly to mostly sunny skies are expected. Cooler highs in the upper 60s to low 70s. .LONG TERM...Sunday Night Through Saturday Issued at 222 PM CDT Sat Sep 11 2021 A stationary front will be positioned to our south Sunday night into Monday, with central and east central WI close enough to the moisture/elevated instability gradient to support a chance of showers and isolated thunderstorms. The front will lift north as a warm front Monday night, as low pressure moves through western WI into the Upper Peninsula. Showers and thunderstorms will become more widespread as a 35-50 knot low-level jet takes aim on the forecast area. Deep layer shear is quite strong, but instability looks too marginal to support a significant severe threat. Suspect that heavy rainfall will be the main concern, as PWATs increase to 1.5-1.7 inches across the forecast area. A cold front will sweep through the area late Monday night into Tuesday, and bring a continued chance of showers and storms through early afternoon. High pressure should bring mainly dry conditions Tuesday night into Wednesday night, but another frontal system will bring a chance of showers and thunderstorms late Thursday into Thursday night. Generally dry weather returns with the arrival of high pressure Friday into Saturday. Temperatures will remain near normal through the period. && .AVIATION...for 00Z TAF Issuance Issued at 628 PM CDT Sat Sep 11 2021 A cold front moving south across the area early this evening will shift winds from the southwest to the northwest. Chances of showers or storms continue to be very low, so no mention in the early portion of the TAF. High clouds and some smoke in the mid to upper-levels of the atmosphere will linger through much of the night. Moisture overrunning the front may produce some light rain or possibly a thunderstorm or two from a mid cloud deck south of a Wausau to Green Bay line late tonight into Sunday morning. Otherwise, good flying conditions are expected with this TAF issuance. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Kieckbusch AVIATION.......Cooley
Area Forecast Discussion
National Weather Service Indianapolis IN
1136 PM EDT Sat Sep 11 2021 ...Updated Aviation Discussion... .Forecast Update... Issued at 941 PM EDT Sat Sep 11 2021 Surface analysis shows quick SW flow in place across Indiana amid a tight pressure gradient. Strong high pressure was found across the Carolinas...while a low was pushing into the western Plains. Aloft...ridging was in place over the plains states and was allowing some high clouds to stream across the upper midwest and into Illinois and Indiana. Dew point temps remained in the 60s. Little overall change is expected overnight. The strong pressure gradient in place will allow some mixing overnight and should prevent too much radiational cooling within this warm air advection pattern. Thus expect low temperatures a bit warmer than the past few nights. Otherwise expect mostly clear skies as forecast soundings and time heights show a dry column. significant changes to the overall forecast. && .Short Term...(This evening through Sunday night) Issued at 300 PM EDT Sat Sep 11 2021 The short term period will consist of warm and windy conditions. Strong, southwesterly warm advection will return above normal temperatures to the area, providing lows in the upper 60s to near 70 and highs tomorrow that will top out from near 90 and possibly as high as the low to mid 90s for some locals. Limited moisture is expected with this advection as seen in model soundings, so will keep PoPs essentially non-existent through the period. Models show persistent tight low level pressure gradients overhead, lasting throughout the period, as central Indiana will be sandwiched between surface high pressure to the SE and a cold front to the NW. This will create sustained winds of 10 to 20 mph, with gusts over 25 mph possible at times. The HRRR continues to show increasing smoke aloft today that will continue beyond the short term. This smoke will filter some out sunshine and if thick enough, could keep temperatures from getting too extreme tomorrow. For now, going to back off by a degree or two with the high temperatures in anticipation of the smoke. This will also prevent sky from being clear as it would otherwise be within this dry environment, so have also upped the sky coverage some. && .Long Term...(Monday through Saturday) Issued at 300 PM EDT Sat Sep 11 2021 The long term forecast begins with upper ridging in place over central Indiana, and this will keep well above normal temperatures in the forecast early in the week. While 500 mb heights start to fall as the ridge axis moves to the east on Monday night/Tuesday, the well above normal temperature signal continues in the ensemble situational awareness tables until Wednesday and will follow this trend. After that, above normal temperatures continue to look likely with the possible exception of during/just after frontal passage, but these will be closer to normal (low to mid 80s for highs) than early in the long term. Chances for showers will return Tuesday afternoon and stick around through Wednesday night as a cold front approaches from the northwest and moves slowly through the area. This will bring an increase in cloud cover and decreasing temperatures for Wednesday as well. Still some uncertainty regarding coverage of the showers and while thunderstorms are possible given the instability, confidence is low enough at this point to cap at slight chance or isolated mention with the exception of Wednesday afternoon when instability and forcing are maximized. Thursday into Friday, variability in the model solutions increases and confidence in the upper pattern decreases with some solutions showing more upper ridging and some stalling the front while others bring up a wave from the southwest. Thus will keep some slight chance (overnight) to mid range chance (afternoon) PoPs going for Thursday and Friday. && .Aviation...(06Z TAF Issuance) Issued at 1136 PM EDT Sat Sep 11 2021 IMPACTS: -VFR Conditions are expected. -Southwesterly surface winds at 10-20 kts with gusts around 25 knts throughout daytime heating hours on Sunday. -Wind shear 020/23040KT starting overnight. DISCUSSION: A strong pressure gradient in place over Indiana along with LLJ max axis around 40 knts will provide breezy conditions overnight and through the day on Sunday. A strong SW flow will continue across the Ohio Valley as Indiana is caught between high pressure over the Carolinas and Low pressure over the western plains. Models show a 850mb LLJ over the area through Sunday afternoon. The gusty winds aloft and strong gradient will result in some LLWS overnight...mainly in the form of speed shear. Forecast soundings continue to show a dry column overnight and into Sunday. Thus only some high CI passing will be expected. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...Puma Short Term...KH Long Term...CP Aviation...JP
Area Forecast Discussion
National Weather Service Marquette MI
631 PM EDT Sat Sep 11 2021 .SHORT TERM...(This evening through Sunday) Issued at 341 PM EDT SAT SEP 11 2021 Water vapor imagery and RAP analysis show mid-level ridging over the southern Rockies out into the Plains. Two vigorous shortwave are noted, one over northern MT/sw Saskatchewan and a second (closed mid-level low) over northern Ontario. The latter feature was responsible for the elevated shra and few tsra that moved across Lake Superior earlier today in association with low- level jet. Some of these shra brushed the tip of the Keweenaw. Shra/tsra are still firing in a narrow band over eastern Upper MI/Whitefish Bay with the development zone into Luce County at times. Cold front associated with the northern Ontario wave currently runs from far eastern Upper MI, just s of Sault Ste Marie, wsw to Menominee County. MLCAPE ahead of the front has increased to around 500j/kg. With just enough capping, no sfc based convection has managed to develop vcnty of the front yet. Even if sfc based convection tried to take off, very strong deep layer shear of 60+kt would probably be too much for the low MLCAPE to sustain any convection. Current temps range from the upper 60s w and n close to Lake Superior to the lwr 80s F s central. Sfc high pres ridge currently over s central Canada will build se, reaching the fcst area on Sun. This combined with current exiting of the cold front to the s and e of the fcst area would suggest a dry fcst tonight/Sun. However, there are some pcpn considerations. First, progression of 120+kt upper jet streak supporting the wave across northern Ontario will result in the right entrance of the jet streak shifting across Upper MI tonight. Some of the models suggest that a few -shra/sprinkles could streak across the fcst area in response to the upper diffluence. At this point, given the dry lower levels and mostly a complete lack of any mid-level instability to support some vertical growth of clouds, did not introduce any pcpn mention tonight. On Sun, the vigorous shortwave currently over MT will be weakening as it moves into a more confluent flow regime over the Upper Great Lakes. With the drier low-levels over the fcst area and today`s cold front well to s extending from IA across far southern Lwr MI, pcpn should not be a concern. In addition, the jet streak associated with the shortwave will move across Upper MI, supporting better overlap of upper diffluence and low to mid-level moisture to the s of Upper MI. For the fcst area, the net result of the upper diffluence will be considerable high and mid-level cloudiness thru Sun morning with clouds then thinning out from w to e during the aftn. As for temps, expect lows tonight in the mid 40s to mid 50s F, coolest interior w. Clouds will aid a cooler day on Sun, but readings won`t be too far from mid Sept normals. High temps will range from the low/mid 60s closer to Lake Superior to around 70F s central. .LONG TERM...(Sunday night through Saturday) Issued at 354 PM EDT SAT SEP 11 2021 A mixed pattern of ridging and troughing looks to dominate the extended period. This should keep temps near to slightly above average, and give us plenty of chances for precip for this upcoming week (CPC 6-10 day temp and precip forecast follows this vein of thought). More details below. Ridging should build over us Sunday night as cool Canadian air in the lower levels remains. Model guidance has indicated an increase in cloud cover Sunday night, particularly in the upper levels. Therefore, mostly clear skies are expected to become partly cloudy later in the night as the dewpoint depression in the atmospheric profile across the U.P. decreases ahead of an approaching shortwave. The NBM seems to pick up on this and has a slight increase in low temps Sunday night across the CWA; therefore, I went with that model solution for the Sunday night temps. We could still see some of the cold spots in the interior west get into the upper 30s, but now it does seem a little less likely. Also, temps should be a little bit higher in the east, where model guidance has suggested that there will be greater cloud cover later during the overnight hours. On Monday, expect WAA over us in the afternoon hours as a shortwave from the Northern Plains approaches. Expect just about your average September day Monday; pleasant weather, highs in the upper 60s to low 70s, partly cloudy skies, and fairly light winds. The shortwave should move over us Monday night. Models have trended towards more precip occurring over the area, as the NAM, Canadian, and Euro all have the shortwave low moving over us Monday night and Tuesday. Meanwhile, the GFS still has the shortwave low moving over the western and central lake. However, it now is trending toward a weak front bringing higher QPF amounts over us Monday night and Tuesday as well. Therefore, while I`m not quite sold on a soaking rainfall event quite yet, if the Euro, Canadian, or NAM solutions come to pass, we could definitely see one across the area (although the Keweenaw may miss out on getting a soaking rainfall). Even if the GFS solution turns out to be true, there should be at least a modest light rainfall event. In regards to thunderstorms with the passage of this shortwave, they don`t seem likely, as there is a fairly decent cap near 850mb Monday night and Tuesday as the shortwave moves through the area; there just might be enough instability in the south central Monday night (and very possibly Tuesday morning too) to get break through the cap and produce a few rumbles at most is what I`m thinking. Would not be surprised to see thunder chances vanish completely if the cap remains and doesn`t weaken with subsequent model runs. Behind this shortwave, expect more ridging. Highs should be in the 70s Wednesday and Thursday, progressively warming each day as another trough to the west brings WAA over the U.P. Wednesday night. Low temps are looking to bottom out in the low 40s in the cool spots in the interior west during the middle of next week as the ridge remains. As an Alberta Clipper approaches us Thursday, the better forcing associated with its cold front looks to be north of us. Therefore, I would not expect much, if any, rainfall over the U.P. Thursday. However, a shortwave associated with the troughing from the Clipper system looks to move northeast across the U.P. Thursday night and Friday, possibly bringing a widespread rainfall (rainfall might start late Thursday afternoon in the west, but the better chances are definitely looking to be Thursday night into Friday). Model guidance differs on whether there will be thunderstorms or not Thursday night and early Friday associated with the shortwave; felt safe going with NBM and keeping the slight chances for Thursday night (although I could see thunderstorms occurring in the east Friday too). Model guidance diverges significantly after the shortwave`s passage Friday. The GFS holds onto rainfall across the area until the end of the extended period; the Euro shows a weak ridge dominating until the end of the period; the Canadian shows a weak ridge early Friday evening giving way to a shortwave over the west late Friday night. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 630 PM EDT SAT SEP 11 2021 VFR conditions will prevail at KIWD/KCMX/KSAW thru this fcst period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 341 PM EDT SAT SEP 11 2021 With high pres ridge building se, reaching the northern Great Lakes on Sun, winds will be diminishing across Lake Superior. Some gusts to 25kt are expected tonight from Isle Royale to around Whitefish Pt. Otherwise, winds should be mostly under 20kt tonight and mostly under 15kt on Sun. These lighter winds will linger into at least Mon morning. Expect some increase in winds later Mon as the next low pres trough approaches. That trough will cross Lake Superior on Tue. SE to S wind gusts ahead of the trough may reach 25-30kt Mon night/Tue, maybe locally higher, and that will depend on a potential low pres wave that may develop on the trough and track ne across Lake Superior. Winds will then diminish w to e into Wed as high pres moves e to the Great Lakes. Southerly winds will then increase later Wed night/Thu ahead of the next low pres trough that will reach Lake Superior Thu evening. Would not be surprised to see 20-30kt gusts develop ahead of the trough, especially across the e half of Lake Superior. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement until 8 PM EDT this evening for MIZ014. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...TAP AVIATION...07 MARINE...Rolfson
Area Forecast Discussion
National Weather Service Reno NV
1214 PM PDT Sat Sep 11 2021 .Synopsis... Typical autumn conditions are expected into mid-next week with dry and warm days, cool nights, and occasional gusty winds. Low pressure may bring stronger winds and cooler temperatures late next week but precipitation potential appears minimal. && .Discussion... Typical dry early autumn weather pattern for the region into mid- next week with warm days and cool nights. We could see an uptick in W/SW breezes Sunday as a weak short wave moves through, but nothing more than 20-25 MPH for most areas and 30 MPH in wind prone spots. Minimal smoke concerns into Monday based on latest fire activity and HRRR Smoke model. Honestly the most interesting part of the forecast is late next week into the weekend of 9/18-19. Ensemble guidance pointing toward development of a trough, possibly significant and cold, along the west coast. This is likely to bring strengthening breezes starting next Friday based on NBM and ECMWF EPS, along with much cooler temperatures. A non-trivial number of models in the NBM have highs for RNO only in the 60s on 9/19, for example. Precipitation potential with this trough pattern seems low right now. Dry airmass looks to remain in place and most of the Pacific moisture tracking well north over the Pac NW per atmospheric river landfall charts. -Chris && .AVIATION... A quiet weather pattern is expected for the remainder of the weekend into early next week. Expect VFR conditions at Nevada and Sierra terminals. Smoke impacts are largely confined downwind of the Dixie Fire into southern Oregon with limited smoke coming off the Caldor Fire at this time. Otherwise areas of valley fog will be possible through the Martis Valley with patchy fog potentially impacting visibility at KTRK pre-dawn on Sunday. Expect typical afternoon gusts across all terminals around 20kt Sunday afternoon. Fuentes && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Springfield MO
619 PM CDT Sat Sep 11 2021 ...00Z Aviation Forecast... .SHORT TERM...(This evening through Sunday) Issued at 140 PM CDT Sat Sep 11 2021 Temperatures have underperformed model guidance today, likely due to the smoke aloft. HRRR indicates that the smoke will persist (if not increase some) on Sunday, so temperatures may need to be scaled back some. Even without any adjustments, Sunday highs in the low to mid 90s do not lead to excessive heat concerns due to limited moisture preventing heat index values from rising more than a degree or two above ambient temperatures. Guidance does not suggest ground level smoke concentrations substantial enough to reduce visibilities at all. No rain forecast through Sunday. .LONG TERM...(Sunday Night through Saturday) Issued at 140 PM CDT Sat Sep 11 2021 Continued warm on Monday, then a little cooler Tuesday as the upper ridge over the area flattens and shortwave energy begins to impact the region. Chances for showers and storms return late Tuesday due to shortwave energy and an approaching front. Guidance varies on the progression of the front, with solutions for the front to stall north of the area, push quickly through the area, or stall overhead Tuesday night into Wednesday. While there is considerable uncertainty, this period will bring the highest chances for rain through the forecast period. At this time, no severe weather is anticipated. Off and on low end chances for rain exist in the forecast late in the week as weak shortwave energy may impact portions of the region. Temperatures look closer to normal for late week. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 618 PM CDT Sat Sep 11 2021 As an upper level ridge situates itself over the region, dry and calm weather will continue through the TAF period. VFR conditions can be expected for all TAF sites through the TAF period. Looking into tonight and early Sunday morning, low level wind shear can be expected at KSGF and KJLN during the 06Z-13Z time frame. Wind gusts of 20-25 knots out of the south-southwest will be present Sunday afternoon at KSGF and KJLN. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ SHORT TERM...Titus LONG TERM...Titus AVIATION...Burchfield/Langfeld