Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/15/21

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
743 PM EDT Thu Oct 14 2021 .AVIATION... Widespread shower and thunderstorm activity along the cold front has cleared the forecast area to the east. Post frontal winds have been relatively weak at 10 knots or less. Modest surface based cold advection tonight with lack of sharp lower tropospheric temperature inversion will allow for rapid improvement of ceiling heights to VFR during the first 1-2 hours of the TAF period. Moist surface conditions will likely result in shallow ground br/fg and MVFR ceilings during the late evening. Frontogenesis and associated moisture advection leads to prevailing shower activity between 15-22Z Friday. For DTW...Prevailing rain showers with IFR expected 15-22Z Friday. .DTW THRESHOLD PROBABILITIES... * High for ceilings aob 5000 feet late tonight and Friday. && .PREV DISCUSSION... Issued at 409 PM EDT Thu Oct 14 2021 DISCUSSION... Linear convection has organized along a line from Cass City to Fowlerville with modest rainfall rates. So far observations have come in with minimal wind (peak 20KT at MBS) given some degree of inhibition within the boundary layer. EMC RAP mesoanalysis depicts broad area of 800 J/kg of DCAPE amongst reservoir of 500-1000 J/kg of SB/MLCAPE. EBS is there to preserve mature updraft structure (40- 50 knots) and expect several strong structures to expand further south over the next several hours until the surface front makes further inroads and diurnal enhancements fade with sunset. Weak inversion/capping south of M-59 is expected to soon erode for the southern half, unlocking some additional buoyancy by the time the line arrives. Lapse rates remain meager, suppressing updraft speeds. Based on orientation of wind shifts relative to radar thus far, convection appears mainly coincident with the frontal slope. The pre- frontal showers never really materialized earlier today, thus further trimmed near-term Metro area PoPs to align with ongoing convection. It will take some time for the frontal slope to clear SE, particularly south of I-94. An embedded shortwave impulse is forecast to lift through overnight providing another opportunity for precip. Given the elevated and shallow nature depicted via forecast soundings, nocturnal thunderstorm activity will be limited. Large temperature gradient develops overnight with clearing skies and upper 40s to near 50F for northwestern locations while lingering cloud cover and delayed FROPA keeps overnight lows in the upper 50s to near 60F for the Metro region. The axis of the aforementioned upper trough will tilt meridionally on Friday bringing stronger jet energy and notable DCVA to the Great Lakes. Plenty of available moisture to work with in the mid-upper levels from the cooled airmass frontal wake. Wavy low-amplitude shortwave height field suggests numerous rounds of showers and perhaps a few embedded thunderstorms, predominantly during the PM hours on Friday. Surface low approaches Friday night amongst increasing deformation forcing for a persistent period of lift. Sensibly cooler conditions arrive, approaching seasonal normals, especially along/north of I-69. H8 temp trends drop into the low single digits Friday night highlighting the degree of cold advection and veering northwesterly flow. Saturday will be the chilliest day (highs stuck in the 50s) with dwindling shower chances as the day progresses. More cohesive NW flow with steep BL lapse rates help bring a period of gusts in the 20-30 mph range. Lake Michigan moisture flux will maintain ample cloudiness if not a few lake- effect showers. Upper level confluence ensues Sunday through Tuesday supporting a period of drier weather. Minor height rises hint at a gradual warming trend back toward climatological normals by mid-week with increasing ridge amplitude across the Midwest. Stacked low brings rain back by Thursday with increasing southwest flow. MARINE... Ongoing passage of a cold front has and will continue to produce a line of showers with embedded thunderstorm activity that will sweep across the Great Lakes through the evening. The last of the activity will linger across Lake St. Clair and Lake Erie late this evening. Wind direction will veer more westerly following the passage of the front as winds remain light. A low pressure system will then move northeast from the Ohio Valley through Lake Erie on Friday which will push a stronger cold front across the Great Lakes later on in the day. This system and front will produce widely scattered to numerous showers with embedded storms throughout Friday, lasting into Saturday morning. A much better lake response will come with the push of cooler air behind the front as wind direction veers northwesterly. Sustained winds nearing 20 knots looks likely across Lake Huron on Saturday, with gusts around 25 to 30 knots. Small Craft Advisories will be possible for the nearshore zones on Saturday. HYDROLOGY... Showers and thunderstorms are on-going along a cold front dropping through Lower Michigan. More substantial and widespread rainfall is expected on Friday as an area of low pressure skirts past eastern SE MI. Similar available moisture aloft on Friday compared to today, but better vertical distribution and longer duration forcing will produce between 0.50-1.25 inches of rainfall by Saturday morning. The highest totals are expected across the southern four counties. Max rainfall rates generally remain below a quarter of an inch minimizing impacts to ponding along roadways, poor drainage, and low- lying areas. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....CB DISCUSSION...KK MARINE.......AM HYDROLOGY....KK You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Green Bay WI
959 PM CDT Thu Oct 14 2021 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Friday Issued at 223 PM CDT Thu Oct 14 2021 The latest RAP analysis and satellite/radar imagery show low pressure spinning across northeast Manitoba and an occluded/cold front moving east over the lower Peninsula of Michigan. Within a shallow, colder airmass, a large area of stratus has made little progress to the east across northwest and north-central Wisconsin so far today. The rest of the region has seen clearing skies as mid-level clouds have exited east with the front. Forecast concerns mainly revolve around cloud trends and very light precip chances through Friday. Tonight...The low pressure system over south-central Canada will lift northeast towards Hudson Bay while the occluded/cold front will move over the eastern Great Lakes. Meanwhile, weak high pressure will build into the state from the central Plains. As the low pulls away, the low stratus deck over Minnesota and northwest Wisconsin will lift north with the low, but still graze north- central Wisconsin. Other mid-level clouds will also stream overhead from the southwest ahead of the longwave trough. The combo of clouds and winds should prevent tanking temps at the cold spots and any risk of frost. Lows will range from the upper 30s to near 50 by Lake Michigan. Friday...The upper trough will continue to move east and spark a weak surface wave along the old cold front positioned across the Ohio Valley to the eastern Great Lakes. Northeast Wisconsin will be on the back edge of the precipitation generated from this surface wave. Most precip will remain southeast of the region as a result, but its possible a few sprinkles or very light shower could fall out of a mid-deck in the afternoon over northeast WI. Areas further west should enjoy more in the way of sunshine. Temperatures will be several degrees cooler than today, and range from the middle to the upper 50s. .LONG TERM...Friday Night Through Thursday Issued at 223 PM CDT Thu Oct 14 2021 Models continue to advertise a progressive mean flow across the CONUS into early next week, before the pattern begins to slow and amplify mid to late week. One upper trough departs the Great Lakes early this weekend, to be replaced by a weakening upper ridge to start the work week. Other than a very small chance of light showers over far east-central WI Friday evening, a dry stretch of weather is expected through at least Tuesday. Models then struggle with the eastward movement of a mid-level shortwave trough mid- week which brings low confidence on when to bring precipitation chances back into the forecast. Temperatures will settle closer to normal Friday into Saturday, but then return above normal through Wednesday. Friday night and Saturday... A small part of east-central WI may still be clipped by light showers Friday evening as a surface wave rides northeast along a frontal boundary to our east and the upper trough moves across WI. Behind these systems, partly to mostly cloudy skies are expected for the rest of the Friday night with enough of a pressure gradient to prevent much in the way of frost formation even as temperatures drop into the middle to upper 30s over northern and central WI. Min temperatures over eastern WI to drop into the lower 40s. Increasing sunshine is forecast on Saturday as the trough pulls away from the region. A ridge of high pressure to be situated over the central CONUS, but northeast WI to still be in a northwest flow aloft. 8H temperatures to be around +2C, thus temperatures will be closer to normal which would be a switch from the mild conditions so far this month. In addition, gusty west- northwest winds will make it feel cooler. Saturday night and Sunday... The surface ridge axis is expected to reach the Upper Midwest Saturday night, bringing clear skies to northeast WI. Winds are not forecast to completely decouple overnight, so the question becomes on how extensive any frost may become. North-central WI would be most vulnerable with min temperatures in the lower to middle 30s. Other parts of far northeast and central WI should drop into the middle to upper 30s. A Frost Advisory may eventually be needed. Min temperatures for east-central WI to hold in the lower 40s. Plenty of sunshine can be expected across the region on Sunday as the surface ridge to move overhead by the afternoon. We will still have a west wind of 10 to 15 mph, but with the onset of WAA, look for max temperatures to rebound mainly into the 60-65 degree range. Sunday night and Monday... After another chilly night with more frost expected over parts of northern and central WI Sunday night, more sunshine is forecast on Monday as the surface ridge slowly slides to the east. On difference will be winds where a southerly component is anticipated. These winds, coupled with a stronger push of WAA, will bring max temperatures on Monday into the lower to middle 60s near Lake MI, middle to upper 60s inland. Monday night through Thursday... Dry and mild conditions look to persist through Tuesday, but forecast confidence takes a big hit thereafter as models significantly differ with the movement of a shortwave trough and a surface cold front. The ECMWF is almost 30 hours faster than the GFS/CMC models with respect to the shortwave trough. A slower solution would keep Wednesday dry and mild whereas the faster solution would bring chance pops and cooler conditions to the area. Until this picture becomes more clear, will need to defer to the consensus solution which brings small chance pops across northeast WI for both Wednesday and Thursday. One aspect the models seem to agree on is the return to normal or even slightly below normal temperatures by next Thursday. && .AVIATION...for 06Z TAF Issuance Issued at 955 PM CDT Thu Oct 14 2021 Generally good aviation weather conditions are anticipated tonight and Friday. Relatively light surface winds are expected overnight. Incoming high and middle clouds streaming across the area should help prevent widespread fog formation, though patchy MIFG is possible. Otherwise, anticipate mainly VFR conditions for the next 24 hours. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Kallas AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Indianapolis IN
1137 PM EDT Thu Oct 14 2021 ...Updated Aviation Discussion... .Forecast Update... Issued at 944 PM EDT Thu Oct 14 2021 Surface analysis late this evening shows a boundary stretched from NW OH across Central Indiana to SRN IL. Water vapor imagery continues to show a tropical plume of moisture stretching from Louisiana and the Gulf of Mexico to points NE including the Ohio Valley. Radar shows scattered showers with isolated thunder along and near the stalled boundary...while more widespread rain was found over Central Illinois...moving NE within the flow aloft. Dew point temps were in the middle 60s. HRRR shows much of the moisture over Central IL pushing NE and crossing the NW parts of Central Indiana. Meanwhile the isolated thunder in place near the boundary is expected to push northeast and also diminish. Thus has trended pops highest across NW parts of Indiana through about 300AM...while keeping chance pops elsewhere where areal coverage is much less. kept any thunder mention to the warmer air along and south of the stalled boundary. Given the clouds and precip expected, will trend lows near dewpoints. && .Short Term...(This evening through Friday night) Issued at 312 PM EDT Thu Oct 14 2021 Radar trends and CAMS support occasional showers and embedded thunderstorms over areas from around Winchester to Indianapolis to Sullivan and north tapering off to chance PoPs far southeast. Marginal Risk for severe thunderstorms late this afternoon and early evening due to strong deep shear and weak to moderate instability with surface based CAPEs currently maximized along the Interstate 69 corridor at around 1000 J/KG. Front was moving into northwest Indiana and will stall tonight somewhere near the Interstate 70 corridor as surface waves move along the front and waves eject northeast across the area ahead of a vigorous High Plains trough. Precipitable water values maximized for this time of year over 1.5 inches, the synoptic forcing and sufficient instability will also support heavy rain at times with over an inch possible at some locales. In fact, central Indiana is in a Marginal Risk for flooding tonight per the Day 1 WPC Excessive Rainfall Outlook. All the ingredients for the potential for more moderate to heavy rain and isolated severe thunderstorms on Friday as the cold front slides southeast across central Indiana courtesy of an approaching sharp upper trough and surface high pressure over the Rockies and High Plains. Low level 30 knot jet pointing in from western Kentucky will keep precipitable water amounts near max for this time of year. This deep moisture will combine with strong deep layer shear of over 50 knots and low level shear near 50 knots to support the potential for a few severe thunderstorms per the SPC DAY2 Severe Weather Outlook. Although, damaging winds will be the main severe threat, would not rule out a brief tornado or two late in the day if there are enough breaks in the clouds to result in enough instability for prolonged updrafts. Otherwise, the weak instability with mixed layer CAPEs less than 1000 J/KG will be the main limiting factor to severe weather. With the front moving through, best chances of severe storms will be southeast of a Muncie to Indianapolis to Vincennes line. 115 plus knot upper level jet streak lifting northeast around the base of the trough over northeastern Illinois late in the day supports moderate to heavy rain and the threat for minor localized flooding per the day 2 WPC excessive rainfall outlook. 1 to near 2 inch storm total rainfall looks reasonable. Needless to say, 80 to 90 plus percent PoPs look good. The rain will move east into Ohio overnight Friday night into Saturday morning. Look for storm total rainfall of half an inch to over an inch over most or all locations. && .Long Term...(Saturday through Thursday) Issued at 312 PM EDT Thu Oct 14 2021 Much cooler weather is on the way following the passage of a strong cold front Friday night. In the wake of this front, strong CAA will build surface high pressure, co located with depressed heights and cold air aloft. This will lead to sunny skies and below seasonal temperatures Saturday, with highs in the upper 50s to low 60s across central Indiana. Expect winds to be brisk on Saturday within the strong CAA. Nearly clear skies and steep PBL lapse rates should create mixing in the afternoon, pushing even stronger winds to the surface with gusts up to 30mph. In what will be a fairly progressive pattern along a strong Polar Jet, these cool conditions will swing back towards seasonal rather quickly. Ridging aloft will quickly move over the Ohio Valley early next week, backed by a significant area of low level WAA east of a broad low. This will push temperatures back into the low 70s, for most of next week. With high pressure still providing broad subsidence over the region for early next week, conditions are expected to remain dry. Forecast confidence lowers for the end of next week, as another wave approaches from the west. For this reason, small chances for PoPs have been introduced for Day 7. && .Aviation...(06Z TAF Issuance) Issued at 1137 PM EDT Thu Oct 14 2021 IMPACTS: - Flying conditions will deteriorate to MVFR and possibly worse IFR predawn. - Isolated lightning possible mainly near BMG. - A return to MVFR on late morning and afternoon...but more rain will be expected aft 152200Z. DISCUSSION: An area of showers associated will push across NW parts of the forecast area impacting the LAF and HUF and IND taf sites early in the TAf period. A weak boundary was stalled across the southern parts of Central Indiana...but still north of BMG. As the rain as seen on radar moves across the area...IFR cigs are expected to develop near daybreak...but conditions should improve through the morning hours as the forcing with the showers exits and daytime heating resumes. Kept any thunder mention closer to BMG where instability appears to be a bit stronger. Another surge of moisture and forcing within the tropical flow aloft is expected to arrive on Friday afternoon and Friday night. This will bring a return to more MVFR Cigs and areas of rain. Winds will be northwest at most of the TAF sites...with the exception of BMG as that location will be ahead of the stalled frontal boundary. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...Puma Short Term...MK Long Term...Updike Aviation...JP
Area Forecast Discussion
National Weather Service New Orleans LA
649 PM CDT Thu Oct 14 2021 .AVIATION (00Z TAF DISCUSSION)...Conditions look favorable for a widespread fog and low stratus event to impact all of the terminals between 08z and 15z. Light boundary layer flow of less than 15 knots will support boundary layer decoupling. As the boundary layer decouples and a deep inversion forms, high relative humidity values will support fog development. LIFR and VLIFR conditions are expected to occur for several hours at KASD, KHDC, and KMCB. Visibilities may fall to near zero at times at these terminals around 12z. By 15z, increased thermal mixing within boundary layer will lead to improving conditions at all of the terminals. VFR conditions should be in place by 18z. There will be a risk of some scattered convection between 18z and 00z, but the threat is too low to include in the forecast at this time. PG && .PREV DISCUSSION... /issued 402 PM CDT Thu Oct 14 2021/ SHORT TERM (This evening through Sunday Night)... Partly cloudy skies and warm temperatures will end the day today, similar to the past several days. Glancing at GOES-16 Ch.2 VIS late this afternoon shows patchy cumulus ongoing, with radar showing little, if any light shower activity which was anticipated for today. Soundings illustrate what was discussed in the morning update with southerly to southeasterly winds helping to increase moisture, extending in depth aloft in the lower troposphere. This helped pop up a few isolated showers today, and checking over recent HRRR runs shows an isolated shower or two may still be possible through the evening and overnight hours. Otherwise, expect the cumulus field to dissipate as we decouple this evening, with only some patchy upper-level cirrus advecting along westerly flow in the 200-300mb layer, sheared off from convection ongoing across coastal Texas. The main focus for tonight will be areas of fog developing generally in the same areas we saw earlier this morning, however deterministic and blended probabilistic guidance is coming in a bit stronger with the potential for dense fog formation. At this time, likelihood for dense fog has been highlighted by a Dense Fog Advisory which will go in effect at 5AM through 9AM, as we very well could see a few hour window of dense fog issues. Without getting too cute on specific areas, the focus will be from Baton Rouge, generally along and also north of I-10/12 over the northshore to coastal Mississippi. Less confidence for areas further south - but will monitor for possible expansions/cancellations per trends in observations. Meanwhile overnight tonight, above the surface, deep-moist ascent will continue to ascend/lift and dissipate the inversion that has kept us mostly dry over the past several days. What this in turn will do is lead to another day of pop-up showers, perhaps with a bit more coverage thanks to the inversion eroding (enough) to help parcels ascend in vertical depth, plus with a bit more available moisture to work with, it will not take much to get some showers going. However, with what is left of the inversion still there, lifting a SB parcel only reveals a small slither of available energy in the H7 to H5 layer and above. Showers, should they grow tall enough will struggle to produce lightning - and have kept any thunder wording out of the forecast for now. Ofcourse, a stray rumble or two can not be ruled out, but too small of a risk to mention in the forecast. Focus shifts back to the west at a cold front, picking up pace towards the east approaches our area. Taking a step back and looking at the entire US reveals this to be quite the potent front with deepening western US troughing quickly accelerating east allowing for large-scale ridging to build out west, with plenty of upper-level convergence to support a nice, big surface high to slide in from the intermountain west. Downstream of the trough axis (moreso an embedded shortwave) will be a weak surface low, progressively deepening as it races northeast from the mid MS valley region into the Ohio Valley region. Meanwhile for us, all we are left with is a quasi-zonal west to east flow from the near- surface and aloft as better dynamics and associated height falls remains well to our north. No real modification is done in the mid-levels to the left over inversion, which keeps us under an overall "warm" thermal profile in the vertical revealing -5 to -6C H5 temperatures and lapse rates in the 5 to 5.5C/km range. As we heat up during the day tomorrow, we will still build enough instability to support showers as mentioned before, but the only real forcing available will be from the front itself. Meaning, this will likely be a thin line that ignites Friday afternoon along the front from coastal Texas, northeast across central LA and north-central MS during peak afternoon heating. But that is pretty much all that is fueling this line of showers and a few storms, combined with the only forcing being along the front because once this line enters the far NW portions of our CWA around 8 to 10PM, it will steadily fall apart. One thing to mention, CAM`s typically decay convection forced along a front too quickly after sunset, meaning this line could progress enough into our CWA for most folks to see rain (mainly areas along/west of I-55), but east of I-55, there may not be much left of this line, even going into parts of southeastern LA as well. Overall with all said, not anticipating a washout or any severe weather, but a quick burst of rain will be possible followed by a sharp change in northerly winds and cooler temperatures to follow going into Saturday morning. Saturday is still promising to look very nice with cobalt blue skies and cool temperatures. A breezy north wind will make it feel very nice, but will be even more windy along north-facing shorelines including the southshore and will be very windy along nearby area lakes/sounds with offshore flow. As mentioned earlier, the caveat in the forecast was the potential for some upper-level clouds building in from a shortwave trough riding northeast underneath large-scale ridging in the western US. The GFS has backed off on the speed of clouds getting in here fast enough to impact overnight lows Saturday night/Sunday morning. Seeing the NBM starting to stairstep back down again placing many areas along/north of I-10/12 into the upper 40`s, well below deterministic blended guidance. The only thing to watch will be if winds can calm enough to support maximized radiative cooling processes, but am feeling comfortable in these values regardless, maybe a bit cooler in typical cooler drainage areas along the northshore and coastal MS. Sunday will be another gorgeous day yet again and feeling cool, with winds not as breezy as Saturday thanks to the surface high finally settling in. However, the same trough mentioned before creeps into southern Texas, so does supportive, downstream upper-level divergence and upper-level cloud cover. We will see cirrus increasing through the day, but still a nice day overall. By Sunday night/Monday morning, thicker cloud cover builds in which even though winds finally relax enough to support radiational cooling to take over, an increase in mid and upper-level clouds could offset this effect leading to temperatures several degrees warmer than what is forecast Sunday morning. NBM is capturing this temperature trend nicely and should not (hopefully) have to make too many more adjustments. Besides all of this, a cool, dry and pleasant weekend awaits! Enjoy! KLG LONG TERM (Monday through Thursday)... The surface high pressure system will slide to the east on Monday turning winds more easterly. A weaker upper level shortwave does move through the area during the day, but this isn`t expected to bring any moisture with it. This keep conditions dry and quiet for Monday. As the surface high pressure system continues to move eastward of our CWA wind will eventually turn southeasterly into Tuesday and Wednesday which will help pull some moisture from the Gulf back up over land. With the flow expected to be on the weaker side most moisture looks to effect coastal and marine areas but we may see some isolated inland areas with a shower or two. Thus isolated to scattered PoPs are in the forecast for Tuesday and more so into Wednesday, mainly along coastal areas. After Wednesday we see a big deviance in the GFS and ECMWF, with the former showing a good amount of moisture moving into our region with a frontal passage associated with a low pressure system over the Midwest. The ECMWF does not show the associated low pressure system over the Midwest nearly as strong as the GFS, resulting in it showing little to no moisture for our CWA. Given this big difference in model data, expect changes in the PoPs for late next week. High temperatures are expected to be cooler on Monday after the cold front, with values in the mid 70s for most. Low temperatures dropping all the way into the upper 40s to low 50s for some northern areas overnight and the mid to upper 50s for areas closer to the coast. Tuesday through Thursday high temps return to the low 80s and low temps sit in the low to mid 60s for northern areas and the mid to upper 60s along the coast. -HL AVIATION (18Z TAF DISCUSSION)... Expect primarily VFR conditions this afternoon, with intermittent MVFR due to periodic lower CIG`s from patchy low-level cumulus through sunset. Few light showers between MSY, NEW and ASD, with the mention of VCSH in these terminals, otherwise these showers will not pose a significant impact other than temporarily reduced VIS leading to a quick reduction in flight categories. Otherwise, we dry out tonight with VFR prevailing after 00Z. After 06 to 09Z tonight, widespread fog and low CIGs will likely develop across the same areas as we saw this morning, perhaps a bit more coverage east to ASD and HUM. Some areas, especially BTR, HDC and MCB may likely see periods of dense surface fog, with LIFR/IFR conditions for a few hours. Conditions will improve around daybreak or shortly thereafter, revealing primarily VFR/MVFR conditions into the morning hours. KLG MARINE... Persistent southeasterly onshore flow will continue through Friday, before a cold front swings across coastal waters early Saturday morning. Expect winds to increase from the north behind the front, likely reaching Small Craft Advisory as waves/seas also increase thereafter into the upcoming weekend. Generally expecting around 2 to 4ft waves for protected waters, to 4 to 9ft for outer 20-60nm zones at this time with the peak highest waves during the day on Saturday through Saturday evening. Thereafter, winds and waves/seas diminish steadily going into early to middle parts of next week, with winds transitioning from the east and staying light. KLG && .PRELIMINARY POINT TEMPS/POPS... MCB 71 88 58 72 / 10 30 30 0 BTR 71 88 59 73 / 20 40 20 0 ASD 70 89 62 77 / 0 30 40 0 MSY 73 89 67 76 / 0 30 40 0 GPT 71 87 65 77 / 0 20 50 10 PQL 69 87 64 78 / 0 10 40 10 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...Dense Fog Advisory from 5 AM to 9 AM CDT Friday for LAZ036-037- 039-047-048-050-071-072-075. GM...None. MS...Dense Fog Advisory from 5 AM to 9 AM CDT Friday for MSZ069>071- 077-080>082. GM...None. && $$
Area Forecast Discussion
National Weather Service Marquette MI
639 PM EDT Thu Oct 14 2021 .SHORT TERM...(This evening through Friday) Issued at 353 PM EDT THU OCT 14 2021 Water vapor imagery and RAP analysis show a trof over the Rockies with a well-defined shortwave lifting nne vcnty of the Manitoba/Ontario border. Mid-level dry slot associated with this feature overspread the fcst area late night/this morning, and it remains over the area. Low-level moisture swinging around the system is brushing the western fcst area, leading to sct-bkn stratocu there. Right entrance of jet streak across the Upper Lakes led to considerable high cloudiness across the area this morning. With that jet streak shifting off to the ne now, skies have become sunny across the central and eastern fcst area. Current temps range from the mid 50s at KIWD to the mid 60s central and e. Sunny skies and downslope warming under ssw/sw winds has pushed temps toward 70F from around Marquette to Munising. So yet another aftn of above normal temps over all but the far w. Western trof will shift e tonight/Fri with axis approaching the Mississippi Valley by Fri evening. 850mb temps currently range from around 2C at KIWD to around 11C at KERY. By late Fri aftn, 850mb temps will range from around 1C at KIWD to around 3C at KERY. So, gradual cooling will continue, more notably into the eastern fcst area. Expect min temps tonight from the mid 30s F interior w to low/mid 40s e and near the Lakes. Highs on Fri will be back on track with mid Oct normals, particularly across the w. Readings will range from the lwr 50s F w to around 60F e and s central. Abundant low-level moisture to the w across the eastern Dakotas/MN will be advecting e and ne, though some will be mixing out for the remainder of the aftn. The resulting stratocu will be confined to the western fcst area tonight. On Fri, this moisture combined with the cooling air at 850mb should result in a little more stratocu development across the fcst area as daytime heating gets underway. With 850mb temps dropping to around 0C tonight/Fri across western Lake Superior and with sfc water temp around 14C, some lake effect -shra should begin to develop later tonight. There is enough westerly component to the wind to warrant a schc mention of -shra n of KCMX late tonight thru at least Fri morning. Shortwave moving thru the base of trof will spin up low pres that will track to the Lower Great Lakes Fri evening. This wave will pass too far to the s and e to bring pcpn to the fcst area. There will be some upper diffluence associated with the streak on the front end of the trof. This will support increased mid/high clouds Fri, especially across the e half of the fcst area. Lower levels appear too dry for any pcpn concerns. .LONG TERM...(Friday through Wednesday) Issued at 305 AM EDT THU OCT 14 2021 Overall not expecting widespread impactful weather over the next week. The main story will be closer to normal temperatures for the weekend along with lake effect showers. Thereafter it begins to warm for early next week. The pattern will be progressive through early next week with ensemble mean 500mb height anomalies showing troughing/negative height anomalies over the Great Lakes this weekend with ridging/positive height anomalies building into northern and central Canada early next week, keeping our area under a northwest flow aloft. The result will be cooler, closer to normal temperatures this weekend with another period of daytime temperatures running around 10 degrees above seasonal averages early next week. As far as precipitation the upper level trough swings in this weekend the main jet dynamics and forcing will remain south and east of the area with a surface low pressure progged to deepen as it lifts north into NW Ohio Friday and Ontario/Quebec on Saturday. Locations in the eastern U.P could be on the western fringe of the precipitation shield Friday but a better chance for showers will come as the low levels cool enough for lake effect rain showers to develop late Friday night into Saturday for the west and northwest wind belts. While 850mb temperatures are not impressively cool, they fall to around -2C on Saturday and given lake surface temperatures running well above average, around 15C, the delta-T of around 15 to 17C with inversion heights above 5kft should be sufficient for at least moderate lake effect rain showers. A surface ridge and drier air moves in for Sunday ending the lake effect showers for most areas though the east could hold onto at least a few showers into the afternoon. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 639 PM EDT THU OCT 14 2021 There will be MVFR conditions overnight at IWD and CMX, otherwise it will be VFR through the period. SAW will stay VFR through the whole period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 353 PM EDT THU OCT 14 2021 With low pres lifting thru eastern Manitoba toward Hudson Bay tonight, sw winds up the w half of Lake Superior will continue to gust to around 30kt tonight, especially during the evening. Expect a few gale force gusts to around 35kt at higher obs platforms as well. Gusts to 20-25kt will be more common across eastern Lake Superior. Winds veer slightly more westerly on Fri and then to the nw on Fri night. Gusts to around 25kt will be common during this time. Over the weekend, a seasonal air mass will be over the area, leading to unstable conditions over the lake and more efficient mixing of winds in the lower levels. Result will be nw winds gusting up to 30kt Sat/Sun, especially on Sat when air mass will be cooler and the pres gradient tighter due to low pres lifting across western Quebec. There may be some gale force gusts to 35kt Sat/Sat night over central and eastern Lake Superior. A high pres ridge will arrive Sun night/Mon, bringing lighter winds under 20kt. Winds will increase some on Tue as the ridge shifts e. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...NL AVIATION...07 MARINE...Rolfson
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 305 PM CDT Thu Oct 14 2021 Pretty quiet across the forecast area this afternoon aside from increasing mid-level clouds. Temperatures at 3 PM ranged from the mid 50s toward central Nebraska to the lower and mid 60s in eastern Nebraska into southwest Iowa. The main forecast challenge over the next 24 hours will be chances for light rain overnight. Radar imagery has shown returns gradually strengthening/increasing in coverage from central Nebraska into southwest Nebraska, likely tied to some weak mid-level frontogenesis per SPC Mesoanalysis. That said, ground truth observations have been rather spotty owing to some dry air in the low levels. However, RAP guidance shows the frontogenesis strengthens and deepens a bit as it progresses eastward this evening and overnight. In addition, some shortwave energy currently seen rounding the base of a larger scale trough centered over the Rockies will provide some additional support for shower development. The main question will be how much actually reaches the ground due to the aforementioned dry air in the low levels, but given the upstream observations and strengthening forcing, should be enough to warrant at least some low precip chances overnight. The trough passes through the area on Friday leading to the coldest day of the week as temperatures across the area are expected to be in the mid 50s to right around 60 degrees. Surface high pressure will also be building in and lead to decreasing clouds, but will also bring somewhat breezy northwest winds. The clear skies should lead to another cool night with lows in the 30s for possibly the entire area along with widespread frost. However, the surface high will be passing well to the south leaving the forecast area under at least somewhat of a pressure gradient, so winds could stay up and lead to slightly warmer temperatures than we`d otherwise see (i.e. it`s looking unlikely we see a hard freeze anywhere). Upper level ridging will build in heading into the weekend and early next week, leading to some dry and rather pleasant October weather, with widespread highs in the 70s Sunday and Monday. Heading further into next week, guidance is in good agreement of the ridging quickly pushing eastward while another fairly potent cutoff low approaches the area sometime Tuesday into Wednesday. However, there remains significant model spread in timing and track of the system, so confidence in exact precip timing remains quite low, though it seems we`ll see at least some low end chances at some point pending how much moisture is available. In addition, we`ll likely be cooling back down toward the middle to latter part of the work week. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 625 PM CDT Thu Oct 14 2021 Still on track with lowering cigs, I`ve bumped our expected cigs a bit lower based on upstream obs. A few light showers remain possible at all three TAF sites... as reflected in "VCSH" mention. Expect skies to mostly clear by noon tomorrow as wind speeds pick up. Will see some Friday afternoon gusts of 20-25 knots. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...CA AVIATION...Nicolaisen
Area Forecast Discussion
National Weather Service Norman OK
538 PM CDT Thu Oct 14 2021 ...New AVIATION, UPPER AIR... .SHORT TERM... (This evening through Friday) Issued at 222 PM CDT Thu Oct 14 2021 Currently, there is a surface low centered over Harper County with a dryline extending southwest to near Erick, with another weak surface low near Childress. The previous quasi-stationary front has since lifted northward into southern Kansas. Showers and thunderstorms will likely develop over west-central Oklahoma late evening (around 04Z) as the cold front progresses into northwest Oklahoma and as the low heads eastward from Childress towards Vernon. With mostly elevated instability, large hail up to the size of half dollars are the main threat. The 18Z HRRR suggests weak surface instability on the order of 500 J/kg, and marginal 0-1km shear of 15-20 kts. Therefore, confidence is low on the tornado threat. Scattered storms will grow upscale into a line along the front and progress across central Oklahoma overnight (06-08Z). Locally heavy rainfall may also lead to flash flooding, mainly across east-central Oklahoma. Tomorrow, clouds are expected to diminish from west to east, with gusty north winds and highs in the 60s for most areas. Showers/storms are expected to exit by mid-morning. Thompson && .LONG TERM... (Friday night through next Wednesday) Issued at 324 PM CDT Thu Oct 14 2021 The mid-level trough axis and the cold front will be moving away from the area by 00Z/16 and precipitation will be well east of the area. And this is the beginning of a period of dry weather and near or below normal temperatures for the next few days. Mid-level ridging will move into and hang out over the area through the weekend. The mid-level ridge will finally move to our east early next week. A mid-level trough is expected to move from western Oklahoma into the central/northern Plains, and the main forcing with this currently looks to remain northwest of the area, although there is some potential for shortwaves to move in from the west or southwest that may give at least low precipitation potential early/mid week. && .AVIATION... (00Z TAFS) Issued at 532 PM CDT Thu Oct 14 2021 Some residual MVFR ceilings across north central Oklahoma may linger through the evening. Othewise, expect to see redevelopment of MVFR ceilings most other locations this evening outside of CSM/WWR. To go along with this, storms development is anticipated around 02-03Z across western Oklahoma, which will then translate east and northeast ahead of a cold front. Storms expected to impact OKC/OUN/SWO/PNC. This activity will move by with slow clearing of lower clouds Friday morning. Behind the front south winds will shift to the north and then increase mainly after sunrise into the mid-morning hours. Gusts of 25 to over 30kts likely. && .UPPER AIR... Issued at 532 PM CDT Thu Oct 14 2021 An Upper Air flight is planned for 00Z this evening. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 54 62 42 68 / 70 10 0 0 Hobart OK 50 67 39 72 / 70 0 0 0 Wichita Falls TX 55 68 42 71 / 10 0 0 0 Gage OK 44 63 36 71 / 10 0 0 0 Ponca City OK 51 63 38 68 / 50 20 0 0 Durant OK 63 70 45 71 / 30 20 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$ SHORT TERM...01 LONG TERM....26 AVIATION...30