Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/11/21

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
805 PM CDT Thu Jun 10 2021 .UPDATE... Issued at 803 PM CDT Thu Jun 10 2021 Heat indices will continue to fall this evening, therefore allowed the Heat Advisory to expire. No changes made to winds or temperatures at this time. Things still look on track for a line of thunderstorms to track across the CWA overnight, with strong winds expected to be the main threat. && .SHORT TERM...(This Evening through Friday Night) Issued at 311 PM CDT Thu Jun 10 2021 An active overnight is expected. A decent looking wave on water vapor imagery is lifting northeast through the basin this afternoon. This system will continue to lift out to the northeast, and across the western Dakotas late tonight/early Friday. Ahead of the system, strong WAA/UVM will spread across the High Plains and into the Dakotas overnight. Plenty of moisture/instability/shear should allow for supercell development out west this evening, with forcing later on leading to MCS development, especially around the Missouri valley. The activity should ride the LLJ east overnight. All severe modes appear possible out west this evening, with max STP values progged over western ND. Later in the evening H5 winds increase substantially over central/western SD as trof lifts into the region, and this increase in winds aloft could lead to bowing line segment(s) overnight with threat of strong winds. As the MCS moves east it may outrun some of the upper support, and therefore the strong wind threat is lower in the eastern CWA. Warm temps aloft may also hinder things a bit in the east. That said, all CAMS are pretty aggressive in moving an MCS over basically the entire CWA tonight, with some rainfall amounts even possibly exceeding an inch. The last couple runs of the HRRR have been the slowest, but not sure if that makes it the model of choice or not. Any rain will be welcome. Temperatures will cool down a bit for Friday, but then rebound again for the weekend as upper ridge re-establishes itself. Friday will also be much more comfortable as dry airmass advects into the region behind departing frontal boundary. .LONG TERM...(Saturday through Thursday) Issued at 311 PM CDT Thu Jun 10 2021 To start the period, upper level ridging is in the process of building over the area and remains the story through the entire period. Supported by southerly flow at the surface, temperatures will once again be quite toasty with highs reaching the 90s in most locations every day. The occasional 100 degree temperature is not out of the question either. The one fortunate thing is that unlike this past week, moisture looks more limited and thus conditions will be a little less stifling. Presently, mostly dry conditions are expected through the forecast period. There are indications a trough may begin to flatten the ridge towards the latter half of next week potentially bringing relief to the region just beyond the range of this forecast. && .AVIATION...(For the 00Z TAFS through 00Z Friday Evening) Issued at 624 PM CDT Thu Jun 10 2021 Terminals KABR,KATY,KPIR,KMBG VFR conditions will prevail across the area into the mid to late evening hours. A line of thunderstorms will then track from west to east across the area, exiting to the east early Friday morning. Periods of MVFR cigs and vsbys and gusty winds are possible with the storms. Once the line of storms exits, VFR conditions will then prevail through the remainder of the day Friday. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Parkin SHORT TERM...TDK LONG TERM...Telken AVIATION...Parkin
Area Forecast Discussion
National Weather Service Binghamton NY
1015 PM EDT Thu Jun 10 2021 .SYNOPSIS... Dry weather continues into tonight before a couple disturbances bring in a chance for stray showers and some thunder Friday and Saturday. Showers and storms become more likely for Sunday, with more or less seasonable temperatures through the weekend. && .NEAR TERM /THROUGH FRIDAY NIGHT/... Mostly clear skies and comfortable temperatures are on tap for tonight. With dew points in the lower 50s, temperatures will fall to between 53 and 58 degrees along the NY/PA border. Winds will remain light. 4 PM update... Skies are staying sunny with light and variable winds behind the front that has dropped down into southern PA. Temperatures are peaking in the upper 70s and lower 80s across much of the area, and in the mid 80s in the typically warmer valleys. Mainly clear skies are expected overnight while winds stay light, and this may help temperatures to quickly fall back as far as the upper 40s in the higher terrain of the Catskills and Poconos. Meanwhile, the rest of the area should bottom out in the 50s. Clouds will begin to move back in early Friday as the front starts to lift northward once more. This may touch off a few showers into the late morning, and showers and perhaps a few rumbles of thunder will be possible through the afternoon as a weak shortwave, currently analyzed over Lake Superior, passes through the area. Given weak forcing and only a couple hundred j/kg of CAPE at most, showers and storms should be pretty hit and miss, and not very concerning. A general lack of moisture present in soundings would also indicate fairly light accumulations. A slightly cooler airmass and clouds should keep highs in the 70`s to low 80`s for most of the region, but where we can see rain showers, some cooler readings are possible. A few stray rain showers are possible into Friday night, mainly north of the NY/PA border ahead of yet another wave that will drop through into Saturday. Otherwise, expect partly to mostly cloudy skies while temperatures drop back once more into the 50s. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... For Saturday, an upper level wave will be dropping southeast across NY and New England. This feature will push a weak front southwest into central NY and northeast PA during the day. Models indicate some moisture will linger at 925 mb and and even 850 mb especially into the afternoon. With northerly flow and dry advection occurring during the maximum heating of the day, we could see isolated showers popping up. NBM has a good handle. Models show a capping inversion to preclude deep convection and thunderstorms so have slight chance for showers mainly Saturday afternoon. Then for Saturday night, there will be lingering isolated showers in the evening. Later Saturday night into the overnight hours Sunday morning, another more defined upper level wave will approach and bring more showers as cooling aloft combined with low-level moisture advection increases instability. Have chance POPs between 06z and 12z Sunday. For Sunday this wave is overhead and the models differ as to how much instability is available for the afternoon heating. NAM has much of northeast PA/central NY more stable suggesting southeast low-level flow leads to more of a stable marine layer advecting north. The GFS has more south to southwest flow and lacks this more stable marine layer. Hence there is more instability available on the GFS. For now, have chance for thunderstorms with chance to likely POPs for showers as this wave passes by. The GFS has decent mid-level winds 40-50 knots at 500 mb or around 6 km. GFS CAPE which can be underdone is around 500 to 750 J/kg. This suggests some potential for severe weather Sunday. Since it is day 4 and there is a lot of uncertainty related to the marine layer and instability Sunday, we will hold off on any mention of severe weather. SPC has predictability too low at Day 4 as well. && .LONG TERM /MONDAY THROUGH THURSDAY/... For Sunday night, another upper level wave drops in quickly behind the one on Sunday and continues the unsettled weather pattern with more showers. There might be a few thunderstorms Sunday evening with lingering instability. Another upper level trough pushes through on Monday with a stronger front. GFS CAPE is over 1000 J/kg along an axis ahead of front and the shear is decent. Monday could be a severe weather event for our area and we will have to keep an eye on this. Tuesday will see more of the same with another stronger upper wave and more showers and thunderstorms. Once this wave passes it looks like drier weather will be in store for Wednesday and Thursday. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... VFR conditions are forecast to prevail through the taf period areawide. Expect SKC conditions overnight, with perhaps just a few mid or high level clouds skirting northward at times. Some model differences heading into Friday for the sky forecast. The 3km NAM is more pessimistic, showing mid level clouds quickly filling in from the south, and north by mid to late morning, presumably aided by cumulus development. These clouds would be in the 4-8k ft agl level. Meanwhile, the latest 21z HRRR shows the strato-cu development remaining only across NE PA through Friday morning (15z) with another area of sct to bkn higher level clouds from SYR/RME northward. For the TAFs trended toward a blended solution...but leaned a bit more optimistic (HRRR solution). For now, in the taf have bkn CIGs around 4k ft agl at AVP Friday afternoon, but some of the guidance suggests this may be an upper end MVFR cloud deck, between 2.5 to 3k ft agl. This will be another trend to keep an eye on. Another thing to watch will be the possibility for some patchy fog/mist early Friday morning at ELM. Do not think the fog would be nearly as widespread or thick as what was observed early this morning. However, overnight lows dip down close to the crossover temperature (low 50s) with clear skies, and light winds. Therefore, cannot rule out localized shallow fog along the river near sunrise. Light and variable winds tonight turn over to the southeast at around 5 to 8 kts Friday. Outlook... Friday Night...MVFR CIGs possible from an east-southeast flow marine layer, then a cold front dropping south late at night. Saturday...MVFR or lower CIG restrictions likely in the morning, then gradually becoming VFR by afternoon (north to south). Low chance for a few rain showers. Sunday through Tuesday...Chance for afternoon SHRA/TSRA and associated restrictions each day. Otherwise, mainly VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...HLC NEAR TERM...DJP/HLC SHORT TERM...DJN LONG TERM...DJN AVIATION...HLC/MJM
Area Forecast Discussion
National Weather Service Cheyenne WY
503 PM MDT Thu Jun 10 2021 .SHORT TERM...(Tonight - Saturday night) Issued at 300 PM MDT Thu Jun 10 2021 High Wind Warnings remain on track this afternoon & tonight across all of southeast Wyoming and the northern Nebraska Panhandle. Wind gusts to 50+ MPH have been observed across much of Carbon & Albany counties this afternoon w/ winds likely to increase further during the next few hours post-fropa. 700-800 hpa flow increases markedly to 55-65 knots over much of the CWA after 00z along with excellent low-level gradients and intense downward omega comparable to major bora events that typically occur in winter time. MAV/MET sustained winds of 30-40 knots at several sites is a good indication of high wind (50+ knot) potential and a variety of in-house guidance still leads to exceptional confidence in the development of strong winds over much of the area by early this evening. In the Neb Panhandle, the higher terrain along the Pine Ridge will stand the best chance to see locally higher gusts approach 70 MPH. No changes needed for inherited High Wind Warnings. Winds should diminish for most areas by early Friday AM. A highly conditional threat for strong/severe thunderstorms exists later this afternoon through this evening across our eastern zones in the moist low-level environment east of the dryline. A strongly unstable air mass is present in these areas with 3000-4000 J/kg of MLCAPE alongside favorable effective bulk shear of 35-45 knots. As such, any storms that develop in the next few hours could have the potential to develop into significant supercells with large hail & damaging winds the primary hazards. However, the HRRR has been the most consistent high-resolution model with very little activity in our CWA. NAM soundings suggest initially poor moisture quality and a slight inversion aloft, which may suppress initiation until deep layer forcing increases after 02z with the short wave & associated cold front. Highest probability for severe storms today will be in the northern Nebraska Panhandle around CDR/AIA. Slight possibility that a couple of storms may develop southwest toward BFF, but this would be heavily dependent on outflow boundaries. Much cooler Friday in the post-frontal air mass. Highs will likely be around 15 degrees cooler for most areas w/ little if any chance for precipitation. Upper-level ridging builds back into the region on Saturday w/ warm and dry conditions returning. .LONG TERM...(Sunday - Wednesday) Issued at 330 AM MDT Thu Jun 102021 A persistence forecast will be the theme for the long term as the CWA will be dominated by a amplifying large scale ridge pattern. The center of the 500mb ridge will retrograde west to the vicinity of the Four Corners early next week. 700mb temperatures will range from 18 to 20 degrees Celsius at this time, resulting in afternoon highs in the 90s to near 100. Large scale subsidence and lack of moisture will unfortunately preclude any mention of precipitation. Lowest relative humidities (7 to 12 percent) will be west of the Laramie Range where fuels will be drying out. Fortunately, wind speeds will be below fire weather headline criteria. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 500 PM MDT Thu Jun 10 2021 VFR conditions likely through the forecast period for all terminals. Main concerns for the forecast period exist with any thunderstorm activity across the Nebraska Panhandle. Current HRRR guidance has a primarily dry forecast across the Nebraska Panhandle, with most of the precipitation in the northern boundary of the CWA, and northward into South Dakota. Confidence has remained low for any thunderstorm development across the Nebraska terminals. However, with sufficient energy across the domain, any atmospheric push could get convection started, just not seeing the moisture required. As a result, went ahead and left VCTS wording in the TAFs. Otherwise, gusty conditions will prevail as the front pushes eastward through late tomorrow morning before calming down to light and variable. && .FIRE WEATHER... Issued at 300 PM MDT Thu Jun 10 2021 Extremely critical fire weather conditions continue this afternoon for areas along & west of the Laramie Range with RHs as low as 5 % and wind gusts up to 60 MPH. Winds become more widespread tonight, but RHs will begin to recover. Improving conditions are likely for Friday in the post-frontal air mass with much cooler temperatures. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Warning until 6 AM MDT Friday for WYZ101-102-106>108- 116>119. High Wind Warning until midnight MDT tonight for WYZ104-105- 109>111-113-115. NE...High Wind Warning from 8 PM this evening to 6 AM MDT Friday for NEZ002-003-095-096. && $$ SHORT TERM...CLH LONG TERM...MJ AVIATION...MD FIRE WEATHER...CLH
National Weather Service Sioux Falls SD
1031 PM CDT Thu Jun 10 2021 .SHORT TERM...(This Evening through Friday) Issued at 305 PM CDT Thu Jun 10 2021 Early this afternoon, temperatures have risen to the lower to upper 90s across much of the region, with an axis of locally higher dew points in the upper 60s to lower 70s and thus heat index readings across south central SD. Quiet but hot weather is expected through around midnight tonight as the region remains primarily influenced by strong upper ridging and breezy southerly flow. Late this afternoon through early evening, strong to severe thunderstorms are expected to develop in the western Dakotas as strong shortwave ejects from the Northern Rockies into North Dakota. As a strong jet streak rounds the west side of the upper ridge over the Central U.S. and the low level jet develops lee of the Rockies through the evening, attention turns to storms tracking east with cold pools conjoining and growing upscale into several complexes of strong to severe thunderstorms. The latest HREF guidance still favors the southernmost complex of storms reaching the MO River Valley in south central South Dakota after midnight, likely not until 07-09z. With the majority of severe wx threat occurring between 2am and 8am, it is important for folks to have a means of receiving severe wx warnings overnight tonight. Initially, storms will encounter an environment ripe for severe weather across south central SD with potential for for large hail up to quarter size, brief tornadoes, and damaging winds potential 80+ mph west of the James River basin. This occurs amidst an axis of 2.5- 4.0 kJ/kg MLCAPE, mid level lapse rates around 8C/km, 30-40 kts 0- 3km shear oriented mostly normal to the line, and DCAPE upwards of 2000 J/kg. Model soundings show a mainly west or southwest profile above the boundary layer and nocturnal decoupling inducing a stable near sfc layer in the early morning hours. This combined with the strong LLJ (around 50 kts), a NW-oriented CLMW, and forcing for ascent along a frontal boundary/upper trough axis supports a transition to a mainly damaging wind threat as the complex tracks east of the James River early in the morning. HREF updraft helicity tracks and most model reflectivity fields show the main threat area shifting to the southern portion of the line south of I-90 in the early morning hours. This southern area is more likely to bow southward and turn more ESE creating a more widespread damaging wind threat south of the I-90 corridor, fed highly downstream unstable air from the LLJ. Uncertainty remains regarding how far east the complex will progress before the southern portion turns more southerly and becomes more of a widespread wind threat - as early as 07z or as late as 12z. Further north along and north of I-90, severe weather threat will start to wane as sunrise approaches and storms approach the I-29 corridor, but there is still potential for scattered up to 70 mph wind gusts and up to quarter sized hail with the complex. This will likely affect areas along I-29 close to when the morning commute occurs. Further east in southwest MN and northwest IA, storms probably won`t move in until after sunrise with isolated hail and wind threat persisting (highest along/south of the Hwy 20 corridor) through the morning. Tonight`s system is not expected to be a major rain-producer, though it`ll be the most rain we`ve had here in a while. The best chance of an inch or more of rain is for areas west of I-29 where thunderstorms will be more numerous overnight. Areas along and east of I-29, especially further north, will likely see a half inch of rain or less. After storms move out of the area Friday morning, the 18z HRRR does depict potential for a wake low or locally higher areas of winds, so this threat will bear watching through mid morning as well. Overall Friday should be a milder and drier yet breezy day behind the passing front. There is some uncertainty in high temperatures, depending how quickly clouds can clear out, but generally expect temperatures to only rise into the 80s with dew points at a more pleasant 45-60 degrees. Northwest winds will be breezy and gusty early in the day, immediately behind the front, and weaken as sfc high pressure builds in. .LONG TERM...(Friday Night through Thursday) Issued at 305 PM CDT Thu Jun 10 2021 After temperatures take a brief dip with the departing disturbance on Friday, highs will once again rise into the 80s and 90s for Saturday and beyond as southern stream upper ridging takes hold of the Central U.S. again. While humidity levels will stay milder than they`ve been over the last few days as Gulf moisture remains mostly blocked from the region, hot and dry weather remains the theme through at least the first half of next week. Cannot rule out a period of spotty rain chances early in the week if a shortwave can survive northwest flow aloft over the ridging, but it`s more likely that any decent rains will hold off until late week. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1027 PM CDT Thu Jun 10 2021 A line of thunderstorms is expected to move into central SD by 07Z, then track into the the KHON vicinity around 09Z, and KFSD and KSUX around 11-12Z. These storms may have damaging winds in excess of 40 kts as they move through. Showers and storms will push out of the area by late morning on Friday. Winds will transition from southerly to northwesterly by Friday morning, gusting 20 to 25 kts through the afternoon. Winds will diminish on Friday evening. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...BP LONG TERM...BP AVIATION...JM
Area Forecast Discussion
National Weather Service Lincoln IL
823 PM CDT Thu Jun 10 2021 .SYNOPSIS... Issued at 232 PM CDT Thu Jun 10 2021 While primarily dry conditions will prevail, there will be at least a chance of showers and storms each afternoon and evening through Saturday. Meanwhile, temperatures will warm into the lower 90s Friday and Saturday with heat indices in the 95-100 degree range. && .UPDATE... Issued at 823 PM CDT Thu Jun 10 2021 Mostly quiet conditions expected to start the night as flow aloft remains weak. Patchy fog remains possible late tonight across eastern and southeast IL where the lightest winds are expected in the vicinity of a trough axis. However, anywhere the boundary layer remains moist from earlier precipitation could develop brief periods of patchy fog further to the north and west. Mid-level ridging moves overhead going into Friday with temperatures expected to climb into the upper 80s to low 90s once again. && .SHORT TERM...(This evening through Friday) ISSUED AT 232 PM CDT Thu Jun 10 2021 Hot and humid conditions are in place across much of the Midwest. A surface trough is in place along the Ohio River Valley this afternoon which is supporting scattered showers and thunderstorms across the area. Some of this convection extends into portions of central and southeast Illinois but the greatest coverage of precip is expected to stay in the vicinity of the I-70 corridor and areas south. Dew points near 70F and temperatures well into the 80s are contributing to moderately strong instability with the latest RAP showing MLCAPE values peaking generally between 1500-2000 J/kg. Flow aloft remains very weak which is resulting in slow storm motions and an overall low threat for severe weather given the weak deep layer shear, though couldn`t rule out a storm pulsing to severe limits briefly given the amount of instability. Cloud bearing mean flow remains fairly weak as well, generally out of the north at 5-10 kts this afternoon, so any stronger storms could produce locally heavy rain as they slowly move over an area. Coverage of showers and storms will diminish after sunset with loss of daytime heating. Cumulus should dissipate as well leaving mostly sunny skies and continued muggy conditions. Patchy fog development is possible across the area, but especially in the I-70 corridor where winds are lightest near the trough axis. 500mb ridge will begin to shift across the Mississippi River Valley tonight with subsidence helping to provide mostly sunny skies Friday and temperatures warming into the lower 90s. Heat index values will top out in the 95-100F range Friday. .LONG TERM...(Friday night through Thursday) ISSUED AT 232 PM CDT Thu Jun 10 2021 Forecast details are still a bit fuzzy over the weekend though hot and humid conditions should be the primary story. Weak low pressure is expected to move east across the Canadian Prairies Friday through the weekend with the tail end of a cold front pushing across portions of the plains and Midwest where it will tap into moderately strong to strong instability along with some accompanying higher deep layer shear values sufficient to support more organized thunderstorm evolution well to our west. Saturday will be the best chance to see any precip locally as the synoptic trough moves through the region, but mesoscale details may end up telling a different story. Once the trough passes through though, precip chances will diminish later Saturday into Sunday. Expect afternoon highs near 90F or into the lower 90s this weekend. Most of the upcoming week looks to be dry across central Illinois. The local area will remain on the eastern periphery of a strong upper ridge centered over the Great Plain. Meanwhile, an expansive surface high will build from the Canadian Prairies to the Midwest through the week providing some break from the muggy conditions with dew points generally staying in the 50s despite temperatures continuing to run slightly above normal. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 624 PM CDT Thu Jun 10 2021 Widely scattered showers and storms will come to an end here shortly after 00Z. Winds become light and variable overnight before taking on a more northwest direction on Friday. Patchy fog is possible overnight from 09Z through about sunrise. The latest guidance continues to keep the majority of fog development over eastern and southeast IL. Cannot rule out a brief period of fog at CMI or DEC, though confidence remains too low to introduce into TAF. Will re- evaluate for 06Z issuance. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...NMB SYNOPSIS...Deubelbeiss SHORT TERM...Deubelbeiss LONG TERM...Deubelbeiss AVIATION...NMB
Area Forecast Discussion
National Weather Service Louisville KY
734 PM EDT Thu Jun 10 2021 ...Updated Aviation Discussion... .Mesoscale Update... Issued at 615 PM EDT Thu Jun 10 2021 Have been watching scattered cells over central KY and southern IN this afternoon, which have so far stayed well north of the Cumberland Pkwy. Mesoanalysis has roughly 2000-2500 J/kg of SBCAPE with no effective shear to speak of. Moderate CAPE has (and will continue for the next few hours) allowed for decent updrafts and relatively cold cloud tops. However, with weaker flow aloft and no wind shear to support organization, cells have remained rather disorganized and slow moving. PWATs are in the 1.9-2.1" range, and combined with slow moving cells, has led to some training and heavy downpours, resulting in isolated areas meeting or slightly exceeding 3 or 6 hour FFG. Primary hazard for this evening will be localized flooding issues, so will be keeping eyes on radar and MRMS flash flood guidance products. && .Short Term...(This evening through Friday) Issued at 246 PM EDT Thu Jun 10 2021 Persistent pattern continues as the upper level low has now become absorbed into the upper flow with troughing extending SSE across the OH Valley. Surface analysis places a center of low pressure along the OH River in western KY with troughing extending NE across central KY and southern Indiana and 70 degree isodrosotherm encompassing all of the CWA. Radar is currently showing scattered showers and a few isolated thunderstorms across the area as KY Mesonet shows temperatures in the upper 70s to mid 80s. SPC Mesoanalysis shows a bullseye of surface convergence near the low center in western KY and extending NE along the OH river coincident with SBCAPE maxima of 2000 J/kg. This is where the best chances of thunderstorms will be, though RAP model soundings have been advertising a subtle warm nose around 700mb that could inhibit robust thunderstorm development through the afternoon. Several observations so far have reported 1/4SM within heavy rain showers, so main threat continues to be brief torrential rainfall with flash flooding potential. General flow appears to be progressive across most of KY with storm motion approximately 260/20kt, but in southern Indiana mean flow is noticeably weaker where radar shows storm motions closer to 10kts. Southern Indiana is also where flash flood guidance is lowest due to consecutive days of showers, so will keep a close eye on radar and flood potential throughout this afternoon and into the evening hours. Tonight, expect to see convective activity wane as we lose surface heating. Some clearing across the area will lead to low stratus and fog development by early morning and persist through mid morning. Low temperatures Friday morning will range between 66 and 71. As the surface low pushes ENE across the OH Valley tonight through tomorrow afternoon, the region will remain within a sultry environment with surface dew points in the low 70s and PWATs remaining around 1.80 inches. Expect another day of mainly diurnally driven showers and isolated thunderstorms with high temps in the mid 80s. .Long Term...(Friday night through Thursday) Issued at 218 PM EDT Thu Jun 10 2021 The weekend: A weak cold front will approach the region Saturday and push through the area late Saturday night into early Sunday. With the warm, humid air mass still in place ahead of this feature, scattered showers and thunderstorms can be expected...particularly Saturday afternoon and evening when instability peaks around 2000 J/kg SBCAPE with 20-25kt bulk shear. High temperatures will be from the mid 80s to around 90. In the humidity ahead of the front Saturday afternoon heat index readings will climb into the middle 90s west of the Blue Grass. Next week: Overall, next week looks primarily dry as a couple of surface ridges slide southward through the area. One possible interruption will be the trough located between those two ridges. The ECMWF brings this feature through Monday night but the operational GFS waits until Tuesday and brings it through at a time of better instability. As a result, the GFS develops a significant band of showers and storms in the Ohio and Tennessee Valleys coincident with it. However, the ECMWF and CMC so far have remained dry. Most members of the ENS EC are dry, as are almost all members of the GEFS. Given that the operational GFS is an outlier at this time, will stick with a dry forecast for now. However this will be something to watch -- the GFS has had good run-to-run consistency over its past four runs, generating precipitation Tuesday. Unfortunately the Desert Southwest will bake next week as a powerful upper ridge sets up over the Four Corners. However, for us we`ll be watching a corresponding upper trough dropping from southeast Canada into the eastern United States, keeping our temperatures in check. Highs for us each day should generally be in the 80s (can`t rule out a few spots touching 90 on Monday...and the Blue Grass will peak in the 70s on Wednesday). && .Aviation...(00Z TAF Issuance) Issued at 733 PM EDT Thu Jun 10 2021 IMPACTS: Scattered showers and storms ending this evening. MVFR conditions likley overnight with patchy dense fog. DISCUSSION: Convection has continued to diminish in intensity this evening with the loss of heating. Expect scattered convection to continue to wind down as the evening wears on. Overnight, clouds and low-level moisture will remain and cigs should build downward with time. MVFR fog is possible at the terminals, though KHNB may drop down below IFR overnight. The lowest cigs/vsbys look to be between 11/08-13Z. Low clouds are expected to linger into Friday morning with cigs returning to VFR by mid-late morning Friday. CONFIDENCE: Medium on all elements. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Mesoscale...CJP Short Term...CG Long Term....13 Aviation.....MJ
Area Forecast Discussion
National Weather Service Memphis TN
919 PM CDT Thu Jun 10 2021 .DISCUSSION... An upper low continues to linger over the region. Scattered showers and thunderstorms have developed across northern parts of the Mid-South where the greatest instability is located. Latest CAMs have this activity shifting east and percolating over West TN overnight mainly near the TN River valley. A few strong storms with locally heavy rain are possible. The main question is what will happen across North MS. The setup is similar to the last few nights with a stable low level airmass across the region attm. Later tonight low level flow increases slightly to 15-18 kts from the west which will feed moist and unstable air over that stable low level airmass resulting in more showers and thunderstorms. Latest CAMs are not nearly as aggressive as the past few nights so perhaps with the upper trough shifting slightly east, the low level flow a touch weaker, PWATs a touch lower, the setup is not quite as good. Nevertheless, given the threat for at least some additional rainfall on saturated soils will leave the flash flood watch as is for now. SJM && PREV DISCUSSION... /issued 331 PM CDT Thu Jun 10 2021/ Latest KNQA radar shows scattered storms across northeast Arkansas, the Missouri Bootheel and West Tennessee. North Mississippi is currently getting a much needed break from activity this afternoon, however, impacts from days of flash flooding are being felt across the area. Since midnight portions of this area has seen roughly 6 to 10 inches of rainfall. Aside from what is occurring across the northern portion of the CWA, additional storms are developing across Central Arkansas and Central Mississippi this afternoon. Latest runs of the HRRR and 3kNAM do indicate the possibility of additional redevelopment of storms across portions of North Mississippi and East Arkansas tonight into Friday. Though coverage is not anticipated to be as widespread any additional rainfall will certainly pose a threat given heavily saturated soils. Given the possibility of redevelopment, the Flash Flood Watch was extended through Friday evening. Heat could be another potential issue heading into Friday and Saturday. Despite temperatures in the upper 80s, heat indices will could rise to near 100F as a result of evapotranspiration. This will need to be watched closely. Latest model guidance indicates the upper trough will finally lift out of the area on Friday. At that point, northwest flow will set up across the Mid- South as the area will be in between an upper trough across the East CONUS and a building upper ridge to the West. Another shortwave will rotate around the upper ridge prompting additional showers and storms on Saturday. This will be followed by a weak cold front that is expected to move through on Sunday. There is a light at the end of the appears upper ridging will start to build into the region on Monday and remain in place through at least mid-week next week. Beyond that point, guidance start to diverge and differs on how to handle an upper low across the northeast. 17 && .AVIATION... 00Z TAFs MVFR ceilings have already begun to spread back in at MEM/MKL over the past couple of hours. Current trends suggest MVFR ceilings should overspread TAF sites again tonight with potential development of IFR ceilings overnight towards sunrise Friday. Conditions will gradually improve to MVFR/VFR throughout the day. VCSH/VCTS possible at JBR/MKL through mid-evening with VCSH possible overnight at TUP. VCTS possible Friday afternoon at sites during peak heating. CJC && .MEG WATCHES/WARNINGS/ADVISORIES... AR...Flash Flood Watch through Friday evening for Lee AR-Phillips. MO...None. MS...Flash Flood Watch through Friday evening for Alcorn-Benton MS- Calhoun-Chickasaw-Coahoma-DeSoto-Itawamba-Lafayette-Lee MS- Marshall-Monroe-Panola-Pontotoc-Prentiss-Quitman- Tallahatchie-Tate-Tippah-Tishomingo-Tunica-Union-Yalobusha. TN...None. && $$
Area Forecast Discussion
National Weather Service Marquette MI
809 PM EDT Thu Jun 10 2021 .SHORT TERM...(This evening through Friday) Issued at 249 PM EDT THU JUN 10 2021 Showers and thunderstorms moved through the west and Lake Superior this morning ahead of a surface cold front moving into the western part of Lake Superior. Cloud cover associated with these really delayed warming through the day. By 10am, ob sites in the Keweenaw were still in the low 60s and the west was only in the mid 70s. Fog that developed after the rain moved through certainly helped keep temps low, particularly in the Keweenaw. In areas where shower and thunderstorm activity has been absent, temps warmed up into the mid- upper 70s to near 80F in some interior locations this morning. Closer to Lake Michigan, temps so far have topped out near 70F. This afternoon, models are queuing in on another round of convective activity across the west half. The driver appears to be an upper level shortwave diving southeast across the lake and into the west. There are some differences among the guidance, and likely some exaggeration by some, mainly the NAM, but generally expecting 1-2000 j/kg of MLCAPE with minimal CIN to allow for activity to start firing close to 18z. Limitations on sustaining updrafts will be weak deep shear, but low level shear of 20-30 kts could sustain some thunderstorms, particularly if the lake breeze is in the vicinity. CAPE profiles, DCAPE and steep low-level lapse rates suggest severe wind and hail could be possible. Convection should dissipate overnight. However, recent HRRR runs try to maintain activity a little longer over eastern Lake Superior, which would then move into the east. Persistent surface moisture and patchy dense fog should help to maintain above normal lows, particularly in areas where it does end up raining. Overall, expecting lows to bottom out near 60F with some mid 50s possible in the mid 50s. Upper level ridging will persist over the western half of our forecast area, forcing an upstream low to drift north from the Dakotas into Manitoba. Surface front tied to this low is expected to move into the western half of our forecast area by afternoon, helping to once again set the stage for another round of showers and thunderstorms by afternoon. Highs tomorrow look to be in the 80s inland and high 60s to mid 70s by the lakeshores. .LONG TERM...(Friday night through Thursday) Issued at 358 PM EDT THU JUN 10 2021 A cold front is expected to move through the U.P. Friday night and Saturday. Some thunderstorms and showers are expected in the west early Friday night with this cold front, but as the night continues, expect thunderstorm activity to diminish; by Saturday morning, only rain showers are expected to continue across the eastern half of Upper Michigan. After the cold front moves through on Saturday, there may be a chance for some light rain Sunday evening. Otherwise, no additional precipitation is expected until next Thursday, when some models hint at a possible cold front moving through the area. Expect cooler and drier conditions early next week, with temperatures being much closer to climatologically normal. However, by the end of the extended period, temperatures across the area could again become well above average. As a low pressure continues to lift northeast in Canada, a cold front is expected to push through the U.P. Friday night into Saturday. This front should bring some much needed rainfall across the area. There`s a chance for some thunderstorms in the western half of the CWA early Friday night as the cold front is progging through the area. However, as the front weakens and as CAPE decreases (due to lack of diurnal heating), thunderstorm chances should diminish the further east the front travels. No more than a stray thunderstorm should happen by Saturday morning when the front is making its way through eastern Upper Michigan. No severe weather is expected with the thunderstorms over the west early Friday evening, although a wind threat could be possible if there is enough organization of the convection to form a line of thunderstorms (like a QLCS). Bulk shear, though, doesn`t look all that impressive, so, again, it`s not expected. As for flash flooding, it is not expected either at the moment. Once the cold front moves through, there may be a string of light showers and a thunderstorm or two that moves over the area. However, did not increase the pops or cloud cover, as I was 50/50 on putting slight chances in the grids, and I didn`t hear back from my neighbors. Also, chances are above 10%, so I feel confident enough to leave it in for now, but could see these chances increasing as we approach next week. Otherwise, dry and cooler weather is expected as a low sits over the East and a ridge builds over the Plains. Eventually, this ridge should build over us during the middle of next week. This should progressively increase temperatures to what we`ve been seeing recently throughout the week, with the warmest day Thursday as the ridge moves over us. This would put us in the warm sector ahead of an upcoming cold front, which should probably arrive Friday (although there is a chance it could arrive Thursday or Thursday night instead). && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 807 PM EDT THU JUN 10 2021 Some additional showers and possibly a thunderstorms may brush locations near KCMX and KSAW this evening. Otherwise, with lingering low level moisture under a developing inversion, expect areas of fog to develop along with low ceilings. Guidance brings all three terminals down to LIFR conditions before conditions slowly improve through the day tomorrow. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 249 PM EDT THU JUN 10 2021 Winds are expected to be 20 knots or less for most of the forecast period. As a cold front passes through the lake today, thunderstorms are expected to develop. Some could product some gusty winds and hail. After the front, lingering moisture atop the cool lake will create pockets of dense fog. Areas of fog are expected at times through the weekend as well, particularly in areas that have experienced any rain fall. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JP LONG TERM...TAP AVIATION...JLB MARINE...JP
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 413 PM CDT Thu Jun 10 2021 After a stretch of monotonously quiet weather that lead to the expansion of drought conditions across the area, the forecast is heating up. Today is the warmest day of 2021 so far for most locations with numbers at 20Z generally in the mid-90s. Heat indices have sneaked up to 100 in spots. A heat advisory continues through 8pm for far eastern and far northeastern Nebraska which includes the metros of Omaha and Lincoln. These last two areas deal with the urban heat island effect which can leave downtown temperatures hotter than surrounding neighborhoods with the asphalt and steel holding the heat longer into the night. Temps tonight will generally hold in the 70s as a mesoscale convective system approaches from the west. As of 21Z, convective initiation is just beginning in eastern Montana ahead of a negatively tilted shortwave trof. This is where the NAM predicted CI. The NAM also suggests upscale growth quicker than the HRRR... leading to a faster arrival time of about 08Z in the NW corner of the CWA and 11Z for Lincoln and Omaha. The HRRR is about three hours later. I`ve split the difference with the knowledge that CAMs sometimes under estimate the forward pace of the cold pool. Regardless of arrival time, the tornado and hail threat will be greatest well west of our area earlier in the evening and by the time the system works into the more stable (less unstable?) environment of eastern Nebraska, the threat will be damaging wind gusts. Still, 1500 J/kg of CAPE overnight is nothing to sneeze at. A half of a much needed inch of rain is possible with localized areas maybe getting the whole inch. Models are in general agreement that the system tends to weaken through the early morning hours, reducing the wind threat for areas south of interstate 80. However, any ongoing storms may find themselves in a moisture-rich and rapidly heating environment where Missouri / Iowa / Nebraska and Kansas come to meet. T-storm mode may revert to supercellular growth as the sun grows higher in the sky on Friday. This would bring another severe threat for Friday afternoon for the extreme SE corner of the CWA or points SE of there. Also tedious were the continued SSE winds that have helped keep the temps high all week. They`ll finally turn to the NW on Friday behind the departing system. A short-lived break from the oppressive heat will leave highs ranging from low 80s along SD to low 90s closer to Missouri. Dewpoints fall into the 50s through the day as the cooler air is markedly drier, too. Occasional gusts up to 30 mph are possible north and west of Lincoln and Norfolk mid-day Friday as the new airmass works into the area. Friday night should be pleasant with relaxing winds and lows near 60. Highs begin climbing again with the redevelopment of the mid-level ridge on Saturday. It grows increasingly amplified through the weekend. By Monday, mid-90s find their way back onto our digital thermometers. All guidance shows a cold front working through the area Monday evening tied to a shortwave rounding the Hudson Bay. At this point, only the GFS produces precip and perhaps severe weather. Have kept the forecast dry for now, but will continue to monitor. Overall, the forecast remains warm and mostly dry. Here`s to hoping that tonight`s convection brings more rain than wind as precip chances are anemic for the remainder of the forecast. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 616 PM CDT Thu Jun 10 2021 The 00z TAF period is set to kick off quietly with cumulus at around FL070 and some cirrus even higher. The main focus of the TAF period will continue to be the morning thunderstorms Friday. Short-term model guidance differ by up to 2 hours in terms of the onset of the storm complex, but nonetheless thunderstorms look likely from 11 to 17z from KOFK to KOMA. Wind gusts over 40 kts are possible with the onset of the storms, and rain will likely last for 2 to 3 hours after onset at a particular location. After storms move out of the area, mid/high clouds are expected to stick around along with the northwesterly winds to close out the TAF period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Heat Advisory until 8 PM CDT this evening for NEZ011-012-015>018- 033-034-044-045-051>053-066>068. IA...None. && $$ DISCUSSION...Nicolaisen AVIATION...Petersen