Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/21/20

Area Forecast Discussion
National Weather Service La Crosse WI
1049 PM CDT Sat Jun 20 2020 .SHORT TERM...(This evening through Sunday) Issued at 246 PM CDT Sat Jun 20 2020 Afternoon water vapor imagery reveals a vigorous shortwave advancing through southern Minnesota. A weak surface low reflection was present over southwest Wisconsin, with the quasi-stationary front still hanging out over our far southern counties, stretching from southwest Iowa to the eastern UP. Widespread morning cloud cover has given way to some breaks in the clouds over much of the area, with some clearing on our western doorstep. Today`s cloud cover and earlier rain has kept temperatures on the cool side once again, ranging from the mid 60s to mid 70s across most of the area as of 2PM. Dewpoints remain in the 60s to low 70s, highest near and south of the front. With the breaks in the clouds, instability has been increasing over the last few hours, especially south of I-90 where MLCAPE has climbed to 500 to 1000 J/kg per RAP analysis. There is 40 to 50 knots of 0-6km shear associated with that incoming shortwave, but this only favorably overlaps the instability this afternoon across a small portion of the area, generally northeast Iowa into far southwest WI. This area near the boundary will be the area to watch through early evening for the greatest potential for storms, perhaps a few on the strong side. Main threats with stronger storms through early evening will be locally gusty winds and perhaps some small hail. Can`t rule out a funnel cloud or two along the boundary given weak low level wind fields in place. And as we`ve seen lately, they will also be efficient rainers with PWATs >1.5" and warm cloud depths >3500 meters. CAMs show the activity progressive enough to suggest a lower threat for any flood potential, but will have to watch where this activity becomes focused, given a long, broad swath of 1 to 2+" antecedent rainfall since last night from Chickasaw County all the way to northeast WI. If storms repeat over this area, could see localized exceedance of flash flood guidance. Guidance in good agreement with the focus for rainfall largely diminishing and exiting the area by early evening, though isolated convection may linger through around midnight. Skies will partially clear from the west tonight with continued light winds. Given the abundant low level moisture and recent rainfall, looks like a decent setup for fog development, especially near and east of the Mississippi River. Not a slam dunk fog forecast given some breezy winds developing just off the surface late tonight, but the general setup certainly looks plausible. Lows in the 50s to low 60s. Sunday starts out with some sunshine and a southwesterly breeze, which will promote much warmer temps than we`ve seen the past couple days. Clouds will spread in during the afternoon as another shortwave approaches, bringing the next round of showers and storms to the area. The warmer temps will foster greater instability with MLCAPE of 1000-2000 J/kg possible west of the Mississippi. Looks like meager deep layer shear of barely 30 knots, but conditions will be a little more favorable just upstream so will need to keep an eye on how things evolve as the convection approaches. CAMS seem to each have their own idea of exactly how this will evolve, but as of now timing for our area generally appears focused on Sunday evening and SPC has expanded their day 2 convective outlook eastward into our western half (more below). .LONG TERM...(Sunday night through Saturday) Issued at 246 PM CDT Sat Jun 20 2020 The active weather pattern will continue as an approaching shortwave trough drives a cold front across the area Sunday night into Monday with associated thunderstorm chances. On Sunday evening/night, boundary parallel deep layer shear around 30-35 kts may lead to upscaling of storms into the area from the north and west along the front, with some potential for a few strong or severe storms. Deep warm cloud depths, high pwats, and moisture transport/plenty of MUCAPE ahead of the boundary would support a heavy rain threat with the storms. The timing of the front and degree of destabilization will help determine the severe weather threat on Monday as a stronger upper trough approaches. Guidance remains somewhat at odds with the speed of the front, which may be impacted by the evolution of earlier convection, but a slower passage could increase potential for stronger storms at least for southern areas on Monday afternoon. Northwest flow develops behind the front into mid-week with a drier airmass and comfortable high temps in the 70s. There will still be some shower/storm chances around as weak shortwaves rotate through the longwave trough/cool pool aloft. Late in the week the flow pattern loses amplitude with a few shortwave troughs possibly impacting the area. Gradually warming temps are expected, but predictability is low with timing of precip chances in this pattern. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1051 PM CDT Sat Jun 20 2020 Patchy to areas of fog are possible tonight across western and central Wisconsin, which could impact KLSE late tonight. If clouds clear completely at KLSE, MVFR conditions in BR can be expected and cannot rule out brief IFR conditions in FG. Showers and thunderstorms look to impact both TAF sites tomorrow evening with periods of MVFR to IFR conditions possible. A few thunderstorms may also produce gusty winds tomorrow evening. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Kurz LONG TERM...JM AVIATION...Wetenkamp
Area Forecast Discussion
National Weather Service State College PA
1131 PM EDT Sat Jun 20 2020 .SYNOPSIS... Little change to our current weather pattern is expected through the first half of the upcoming week. Warm and relatively humid conditions will combine with a pool of cool air aloft to fuel scattered to numerous afternoon and early evening showers and thunderstorms. Any thunderstorms are expected to remain below severe limits, but they may produce locally heavy downpours and their slow-moving nature could lead localized flooding of poor drainage areas. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 7 pm update... Showers and thunderstorms have begun to diminish in coverage early this evening, with that trend expected to continue through the evening as we lose daytime heating and stabilize the environment. Locally heavy rainfall (isolated point totals of 2.5-3.5" in about a 90-minute period) was again the main culprit through the afternoon and early evening hours. Later tonight, as showers become quite isolated, areas of stratus and fog should develop once again, within a very moist boundary layer with light flow. Lows by daybreak will range from the upper 50s over parts of the Alleghenies to the mid 60s in the Middle and Lower Susquehanna Valleys. Previous discussion... Numerous showers and scattered TSRA were rapidly developing across the southern third of the state and drifting slowly to the north and NW across the CWA, beneath the mid and upper level thermal trough. Similar convective evolution with respect to timing of initiation and the areal coverage of convection is expect this afternoon. Sfc based cape is lagging friday though, by a few to several hundred j/kg as low cloud cover and fog was more extensive and thicker this morning. 17Z run of the HRRR and the 12Z HREF favors the greatest amount of SHRA/TSRA across the Lower Susq Valley (and Laurel Highlands) through 21Z, then outflow boundaries and newly ramped up sfc cape values help to shift the main threat for rain to a corridor from Scent PA to the Middle and West Branch Susq Valley late this afternoon and early this evening. The pulse and transient multi-cell nature of the convection will afford little organized training for heavy rain, though some locations that experience a few TSRA could end up with over one inch of rain - which is still comfortably below 1 and 3 hour flash flood guidance of 1-1.5 inches and 2.5-3.5 inches respectively. mid afternoon temps are quite similar to Fri, and perhaps a bit across the NW. Highs will range from the low to mid 70s over much of the Laurels, to the low 80s across the Middle Susq Valley. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... 1030 pm Sunday update... No substantial forecast changes were noted during this period from the previous update. On Sunday, the pesky cutoff low and shear axis extending northward is expected to edge eastward towards the coastal plain. As a result, although afternoon/early evening convection is again expected, coverage should be a bit less than the last couple of days (more hit and miss) and also centered a little farther east (more across our Susquehanna Valley zones). Given slightly building heights aloft as well, afternoon highs should be a few degrees above those of Saturday (highs generally in the 80-85 range). By Monday, although the aforementioned cutoff low should be even less of an influence, we should see some height falls edge into the Commonwealth from west-east, with a weak surface front pushing towards the eastern Great Lakes region. Proximity of these two features should lead to a resurgence again of diurnally enhanced showers and thunderstorms. Previous discussion... Loss of sunlight on this, the longest day, will allow for fizzle quickly this evening. Fog and low stratus is expected once again tonight/Sun AM in the areas where it rains this aftn and evening. The center/axis of the upper low should be to the east of the area on Sunday, but a weakness/trof will lag back to the west. This makes it possible for a repeat of our daily shot of diurnal convection. Less forcing means perhaps even more-scattered/isolated convection than Sat. However, the overall pattern does shift in an additional way for Sunday. A long-wave trough approaches from the west. Shortwave troughiness may meet up in good timing to enhance things, or miss timing and have a quieter day since there might be a tiny bit of ridging overhead. High temps Sunday appear to be a few degrees warmer in many locations, though the Laurels could see a jump in max temps by 5 to 8 deg F. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Medium range guidance pushes a cold front through the region either Tuesday night or early Wednesday in association with approaching upper level trough. This timing supports likely convection across the western half of the state Tuesday PM, with the focus of showers/storms shifting to southeast Pa Wednesday. After a long stretch of warm/humid conditions, the latest NAEFS and ECENS both support a return to near seasonal temperatures and much lower chances of rain late next week (finally providing a break in the daily tstm activity), as surface ridging builds in behind cold front. However, passage of upper trough justifies maintaining low POPs of a PM shower/storm Thursday and Friday. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Isolated convection is quickly dissipating this evening with the loss of daytime heating. With light winds, we will likely see low clouds and fog develop again overnight, especially in areas that received rain today. Fog will dissipate and low clouds will lift and scatter out by mid to late morning Sun. The rest of the day should be partly sunny. A few stray showers may develop by late afternoon or early evening, but showers should be much less numerous than they were Fri or Sat. Outlook... Mon...AM low cigs/showers possible NW Mtns. Isolated PM tsra impacts possible. Tue...AM low cigs possible N Mtns. Scattered PM tsra impacts possible. Wed...AM low cigs/fog possible W Mtns. Isolated PM tsra impacts possible southeast Pa. Thu...AM low cigs/fog possible. Mainly VFR PM. && .CLIMATE... Astronomical summer began at 5:43 p.m. on Saturday, June 20. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Jurewicz/Lambert SHORT TERM...Jurewicz/Lambert/RXR LONG TERM...RXR/Colbert AVIATION...Colbert CLIMATE...Lambert
Area Forecast Discussion
National Weather Service Goodland KS
450 PM MDT Sat Jun 20 2020 .SHORT TERM...(This evening through Sunday) Issued at 240 PM MDT Sat Jun 20 2020 Overview: Cyclonic flow aloft (assoc/w a broad upper trough over the Central/Northern CONUS) will prevail today -- transitioning to NW flow aloft on Sunday. Through Tonight: Simulated reflectivity forecasts via the HRRR and NAM NEST suggest that broad cyclonic flow aloft, DPVA attendant a small amplitude wave therein (progressing eastward from CO into Western KS), weak low-level convergence invof a modest dryline, and a moderately unstable airmass characterized by 1500-2000 J/kg mlcape -- will foster the development of isolated convection along/south of I-70 by 21-23Z, though development may be more likely invof a line extending from Tribune-Gove City-Hill City -- where a relatively robust Cu field is already evident via visible satellite imagery. While modest (20-30 kt) effective deep layer shear suggests multicellular organization (initially, at least) -- the presence of (1) moderate instability and (2) strengthening deep layer shear later this afternoon (30-40 kt by ~00Z) -- appears supportive of supercells. With this in mind, an isolated potential for severe hail and damaging winds will exist late this afternoon, mainly between 22-02Z along/south of a line from Tribune-Gove City-Hill City where deeper low-level moisture (10-12C H85 dewpoints) is more likely to foster deep/established updrafts. Sun-Sun Night: Small amplitude shortwave energy progressing ashore the PAC NW this aft/eve is progged to track ESE-SE through the Northern Rockies (tonight) into the Central Plains (Sunday). Simulated reflectivity forecasts via the HRRR/NAM NEST suggest that DPVA attendant the aforementioned shortwave energy and low- level convergence invof a SSW-NNE oriented dryline will aid in convective development by early-mid afternoon (~20Z) -- somewhere along/east of a line from Leoti-Oakley-Oberline -- with activity growing upscale into a squall line /MCS/ that progresses southeast into South-Central KS (late afternoon) and Northern OK (evening). Steep mid-level lapse rates (8-8.5 C/km) and rich low-level moisture on the eastern periphery of the dryline will foster strong diurnal destabilization (2500-3500 J/kg mlcape).. amidst strong (1300-1600 J/kg) dcape and modest (25-35 kt) deep layer shear. Though discrete updrafts may briefly be present at onset, rapid upscale growth along a consolidating cold pool suggests that damaging winds will be the primary hazard, with destructive straight-line winds possible as the MCS matures and propagates downstream into South-Central KS and Northern OK during the late aft/eve. .LONG TERM...(Monday through Saturday) Issued at 203 PM MDT Sat Jun 20 2020 At the start of the forecast period, an upper trough will be centered over Nebraska and the Dakotas as it continues on its eastward progression across the northern half of the nation. The Tri-State area will be under northwest flow aloft with an upper ridge over the Western CONUS. Temperatures on Monday will be in the mid-80s in the northern part of the Tri-State area and the upper 80s to low 90s in the southern part. A trough on the lee side of the Rockies will provide some lift in the region which could help in shower and thunderstorm development in the afternoon and evening hours. At the moment, CAPE values appear to be low and lapse rates are not looking all that great. Severe weather is not anticipated with any storms that develop at this time. A cold front will swing south, into the Central High Plains through the day on Tuesday. Cooler air filtering in behind the front will cool our temperatures down a few degrees. High temperatures will range from the upper 70s to mid-80s. A few showers and thunderstorms may be possible. A gradual warming trend will begin Wednesday, continuing into the weekend. A flattening ridge will move over the Rockies and into the Central High Plains through the week. As the ridge moves over the area, flow will become zonal across the Tri-State area. A closed upper low will be in place over the Great Lakes for much of the week, eventually beginning to move off to the northeast on Thursday as another upper trough pushes eastward over the Western CONUS. The GFS and ECMWF continue to disagree on the timing of the progression of the closed low with the ECMWF having the more aggressive ejection northeastward. The lee trough over Eastern Colorado will remain in place through Friday before lifting to the northeast, across Nebraska on Friday. Models are suggesting a closed low developing at the 850mb level as the system moves out of the area. Shower and thunderstorm chances are possible each day, though confidence remains low on area coverage, so have opted to keep PoPs low for the time being. Temperatures heading into the weekend will return to the low to mid- 90s for highs and the low to mid-60s for lows. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 450 PM MDT Sat Jun 20 2020 For KGLD and KMCK, vfr conditions expected through the period. Southerly winds 10kts or less at taf issuance will continue overnight then steadily veer to the southwest at similar speeds Sunday morning then west in the 15z-18z timeframe. For the afternoon winds continue to veer to the northwest and approach 12kts in the latter half of the afternoon. At this time any convection will be east of the terminals Sunday afternoon. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...VINCENT LONG TERM...AW AVIATION...99
Area Forecast Discussion
National Weather Service Northern Indiana
746 PM EDT Sat Jun 20 2020 .SYNOPSIS... Issued at 746 PM EDT Sat Jun 20 2020 A few showers are expected through early tonight, primarily along and west of US 31. Look for an increase in the chances for showers and thunderstorms Sunday afternoon, with even more numerous showers and storms Monday into Tuesday. Highs will remain in the 80s with lows generally in the 65 to 70 degree range through Tuesday, then a bit cooler and less humid for the remainder of the workweek ahead. && .SHORT TERM...(This Evening through Sunday) Issued at 216 PM EDT Sat Jun 20 2020 Latest RAP analysis has 500mb ridge axis over the area this afternoon as water vapor imagery showing eastward shift of upper low to the mid-Atlantic region. Focus in the short term will be on short wave energy ejecting out of the central plains from the base of closed low centered over Manitoba along with associated surface frontal wave moving out of Iowa. Best chances for organized convection will be to our west in more favorable unstable environment and aided by forcing from aforementioned synoptic features. As pointed out in previous discussion...antecedent dry/drought conditions hampering weak SW flow from increasing boundary layer moisture. Latest HRRR forecast soundings once again showing afternoon mixing increasing dew point depressions over the next few hours dropping dewpoints into the mid 50s. This will limit diurnal instability going into the evening hours and confine chance PoPs to western CWA tonight. Similar setup for Sunday but with a little better moisture return ahead of slow moving cold front. This should prevent dewpoints from mixing out and thereby provide better afternoon instability and better chances for showers and thunderstorms. && .LONG TERM...(Sunday Night through Saturday) Issued at 216 PM EDT Sat Jun 20 2020 Forecast period to begin with longwave trough axis shifting eastward toward the great lakes region. Short wave energy ejecting out ahead of this will bring some modest forcing into the region and will combine with a little better moisture return on SW flow in the low levels. The added low level moisture will result in better instability with CAPES reaching 2000J/kg across much of the area. Still an overall weak flow/low shear environment so expect scattered discreet to multi-cluster storms popping up Monday afternoon that could transition into a more organized linear mode Monday night into Tuesday morning as cold front approaches from the west. Strong signal among the ensemble members centered around Monday night so likely/cat PoPs are in order. Upper low then settles into southern Ontario mid week as cold front continues to push south into the TN valley bringing cooler but still seasonable temps to the region and generally dry weather through the end of the work week. A transition to a more zonal flow with modest/gradual height rises should bring a warming trend heading into next weekend. Low chances for precip also come back into play as return flow on backside of surface ridge will begin northward push of frontal boundary. && .AVIATION...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 745 PM EDT Sat Jun 20 2020 Primarily VFR through the period. Minor shortwaves approaching late this evening from east central Illinois northeast into northwest Indiana supporting some shower/isolated thunderstorms west of KSBN. Given anticipated diurnal nature of activity will only mention vicinity showers and KSBN. Steep low level lapse rates will quickly stabilize with loss of heating. A more substantive shortwave over northwest Arkansas/Missouri Ozarks will shift east-northeast through the Ohio Valley by Sunday afternoon. While primary focus with this feature will remain south of terminals, still ample afternoon MLCAPE to 1500 j/kg and erasure of surface based convective inhibition will likely lead to isolated to scattered thunderstorms across northern Indiana, sufficient chances for a TEMPO inclusion at this time. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...Murphy SHORT TERM...JAL LONG TERM...JAL AVIATION...Murphy Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1044 PM CDT Sat Jun 20 2020 .UPDATE... Issued at 919 PM CDT Sat Jun 20 2020 Showers and thunderstorms activity has mostly diminished from earlier today. There remains some showers over southeast Missouri that will continue into the overnight hours ahead of a vort max seen on the water vapor imagery currently over northern Arkansas. The RAP shows this vort moving slowly northeast into the western Ohio Valley overnight so will continue with scattered showers and thunderstorms to the south and east of the St. Louis metro area. Rest of going forecast still looks good and made little changes to it. Britt && .SHORT TERM... (Through Late Sunday Afternoon) Issued at 252 PM CDT Sat Jun 20 2020 An upper level trough over the eastern Plains will move east into the Mississippi Valley by 12Z Sunday morning. This wave is helping to ignite convection across central and eastern Missouri this afternoon. The weak and diffuse front stalled over western Missouri is helping to provide a focus for thunderstorm development as well. SPC mesoanalysis shows 1500-2000 J/Kg MLCAPE and up to around 25 kts of effective bulk shear. This is good enough for organized clusters of storms. 600-700 Joules of DCAPE are also available for downdraft production, but mid level lapse rates are not that impressive, so wind continues to be the primary threat with this afternoon/evening`s storms. Can`t rule out a few hail reports with the strongest storms though. Most of the convection should weaken and dissipate this evening with the loss of daytime heating, but some storms may linger overnight across parts of the eastern Ozarks and southwest Missouri. Original thinking for the past couple of days was that the combination of this afternoon`s/evening`s convection and the upper level trof would be push the front to the southeast down across southern Missouri or northern Arkansas. The latest short range guidance basically just washes the front out overnight tonight as southerly flow increases ahead of the next upstream short wave. This will mean it should be warmer and more humid than originally forecast. have bumped up temperatures a bit to around 90 for most locations, and afternoon dew point forecast into the mid and upper 60s. The warm and humid air could produce a few afternoon thunderstorms, however short range guidance is showing some weak low level short wave ridging moving through the Mid Mississippi Valley which looks like it will suppress convection. Carney .LONG TERM... (Sunday Night through Next Saturday) Issued at 252 PM CDT Sat Jun 20 2020 The upper level low currently over south central Canada is forecast to deepen and drift southeast into the northern Great Lakes Region by midweek. This gradually amplifies the upper level flow and and will turn the flow to the northwest. Monday should continue to be warm and humid ahead of the cold front which will be driven south by the aforementioned amplified flow, and a short wave rippling through the base of the upper trough will likely set off another round of convection. Timing and coverage is uncertain at this point, but it does look like there will be some fairly widespread rain. The cold front should move through on Monday night and cooler/drier air will move into the Mid Mississippi Valley. Temperatures will dip to near or just a few degrees below normal in the low to mid 80s. Northwest flow aloft reigns through Thursday when the next upper level ridge begins building into the Mississippi Valley from the west, and temperatures rise again into the mid and upper 80s. Carney && .AVIATION... (For the 06z TAFs through 06z Sunday Night) Issued at 1035 PM CDT Sat Jun 20 2020 Light showers will continue around the St. Louis area terminals and points south and east through 10Z with mainly VFR conditions. Otherwise dry and VFR conditions are expected through the remainder of the TAF period. Winds are expected to remain light. SPECIFICS FOR KSTL: Light showers will continue around the terminal through 10Z with mainly VFR conditions. Then dry and VFR conditions are expected through 06Z on Sunday night before there will be additional chances for showers and thunderstorms. Winds are expected to remain light. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1104 PM CDT Sat Jun 20 2020 .UPDATE... Issued at 846 PM CDT Sat Jun 20 2020 Main change to the forecast for the rest of tonight was to start increasing mention of the dense fog threat in west central WI. For example, EAU received 0.25" of rain through the afternoon, with the temperature as we near sunset just 64 degrees. Clearing skies are working across our WI counties now and with sunset occurring shortly, we expect areas out toward Eau Claire, Ladysmith, and Rice Lake to quickly cool past their cross-over temperatures, with fog becoming locally dense in spots overnight. As for thunderstorms coming out of the Dakotas, they are running out of the reservoir of MUCAPE and will continue their weakening trend as they move into our western CWA. The RAP shows the MUCAPE tongue that has fed these storms weakening considerably as it moves east, so like the going forecast, with it looking unlikely any activity makes it as far east as St. Cloud and Redwood Falls this evening. && .SHORT TERM...(This evening through Sunday night) Issued at 254 PM CDT Sat Jun 20 2020 Widespread showers across western Wisconsin will continue eastward late this afternoon. Meanwhile, a band of thunderstorms across eastern North Dakota will also head eastward through the evening. They may become more numerous south into South Dakota late this afternoon, and then may pose a threat to western MN this evening. They should be on a weakening trend after sunset with the loss of instability and it`s likely they will completely dissipate before reaching St. Cloud and Redwood Falls. Aside from the possibility for a few rogue showers or storms overnight, it should be dry for the vast majority until at least late Sunday morning. Increasing theta-e throughout the day with a cold front slowly sagging southeast across the CWA will spark thunderstorm development during the afternoon. Lapse rates continue to look poor, so CAPE shouldn`t be too impressive. Up to 2000 J/kg are possible across far southern MN where rich low level moisture coincide with slightly better mid level lapse rates. SPC has upgraded this area to a slight risk. 0-6 km bulk shear of 30-40 kts could allow a few supercells to develop where the best pockets of instability develop. Otherwise, CAMs favor short line segments along the cold front, capable mostly of wind damage. The severe threat will diminish Sunday evening, but shower and thunderstorm chances will continue into Monday as the front continues to limp through. .LONG TERM...(Monday through Saturday) Issued at 254 PM CDT Sat Jun 20 2020 The best chances for storms Monday will be across southern MN into western WI. The front will clear the area Monday evening. A large trough will spin multiple weak disturbances across the region Tuesday and Wednesday. Coupled with modest daytime heating, isolated to scattered showers and thunderstorms are likely to develop each afternoon. This trough will clear to the east late week, but several waves continuing eastward across the northern CONUS will keep chances for storms in our future into next weekend. Temperatures will warm back into the 80s as heights rise following the departure of the deeper trough from midweek. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1104 PM CDT Sat Jun 20 2020 Four concerns remain this period. 1) how far convection that came in from the Dakotas makes it into MN this evening, 2) potential for dense fog at EAU, 3) threat for light showers as early as Sunday morning, and 4) threat for another round of thunderstorms late Sunday afternoon. So we`ll tackle all of those briefly. 1) Not much change in thought with these storms outrunning their instability and weakening to not much more than showers over western MN. One cell just snuck north of AXN and still do not expect activity to reach even STC/RWF 2) Confidence has increased that EAU will see dense fog tonight. Just a question of how long it takes to form, but current TAF may be to slow to get it going. 3) Shortwave energy will be moving across central/southern MN Sunday morning. This looks to result in mainly mid level clouds and trend with models has been to produce less activity with this energy, so continued to keep things dry through the morning. 4) For the late afternoon TS threat, kept similar timing to what 00z TAFs had. Still a good deal of spread in the models with where/when storms develop, so stuck with prob30s for now. Front will be diffuse, but greatest threat for TS by 00z should be from south central MN up toward the Twin Cities given expected frontal placement. KMSP...Greatest TS threat still looks to be in the 22z to 04z window. Some threat for MVFR cigs exists for after 6z Monday, but will wait a bit longer before including those in the TAF for Monday morning. /OUTLOOK FOR KMSP/ Mon...VFR. Chc aftn SHRA/TSRA. Wind NW 10 kts. Tue...VFR. Chc aftn SHRA/TSRA. Wind NW 10 kts. Wed...VFR. Chc aftn SHRA/TSRA. Wind WNW 10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ UPDATE...MPG SHORT TERM...Borghoff LONG TERM...Borghoff AVIATION...MPG
Updated for aviation forecast discussion.

&& .SHORT TERM...(Tonight through Monday night) Issued at 336 PM CDT Sat Jun 20 2020 Isolated afternoon showers and thunderstorms continue to develop along decent southwest to northwest CAPE gradient within a 0-2 km moisture convergence zone along the western limb of the narrow and departing ridge axis. Given the sharp low level lapse rates, parcel mixing of dry air aloft and downward momentum, a few of the thunderstorms may produce wind gusts in excess of 40 knots this afternoon before coming outflow dominated. The Storm Prediction Center, in their 3 pm CDT update, added a small part of southeast MO/southwest IL in a Marginal Risk for severe thunderstorms to account for isolated strong wind gusts and hail potential. With the loss of daytime heating, coverage should diminish slightly over southeast MO, southwest IL, and west KY. However, with the continued eastward progression of the western Arkansas low/MCV toward the WFO PAH forecast area this evening and overnight, may see an uptick in convective activity in the aforementioned area around midnight. The high resolution CAM guidance has been having trouble resolving the recent convection. Utilized a blend of the Canadian, GFS, and RAP guidance for short term convective trend tonight through Sunday night. An ageostrophic response and development of a weak LLJ and increased instability aloft with the low/trough axis/MCV moving over the WFO PAH forecast area overnight should increase the coverage of shower and thunderstorm activity over the eastern part of the area after 3 am CDT. Stabilization and loss of larger scale lift should inhibit the redevelopment of widespread convection behind the trough during the afternoon and evening hours on Sunday. This trend is a little faster than what has been advertised the last few days with most of the emphasis on thunderstorms in the afternoon and evening hours. The next shortwave rotates around the primary synoptic scale low in south central Canada late Sunday night. Increased rain chances again during the morning hours on Monday, gradually decreasing coverage during the evening over the southern half of the WFO PAH forecast area. Kept near categorical PoPs near the stalled out frontal boundary over the northwest 1/3 of the area (southern IL and southeast MO) where lift is maximized. Given the higher precipitable water and more efficient rainfall rates, may need to monitor for isolated overland flooding issues on Monday. The WFC QPF branch has the WFO PAH forecast area in a marginal coverage for excessive rainfall. .LONG TERM...(Tuesday through Saturday) Issued at 336 PM CDT Sat Jun 20 2020 The long term forecast begins with ongoing showers and storms throughout the Quad State region. A cold frontal passage just NW of the CWA will slowly advance through the Quad State Tuesday through the evening. Precipitation chances will be highest during the day, then trend downwards overnight. Lingering precip on Wednesday is most likely in the Kentucky Pennyrile region. Behind the front cloud cover will diminish and dew points will drop on the order of 10 degrees. Mostly sunny and less humid conditions continue into Thursday. The GFS produces a weak shortwave that could bring a showers/storms to the area Thursday afternoon, though with little agreement from other models, precip chances are kept as a slight chance. Low pressure between the Great Lakes and Hudson Bay will start shifting eastward Thursday night allowing for a more zonal upper- level flow. High pressure settles into the southeast behind the stalled out cold front that had crossed the Quad State Tuesday. This will bring a more southerly surface flow from the Gulf to the Quad State for the end of the week. Models disagree on development towards the end of the forecast period. The GFS is more focused on developing shortwave energy in the Plains moving towards the Great Lakes while the ECMWF produces more Gulf Coast precipitation that could be drawn northward. In some manner, a boundary is likely to form during the weekend connecting these features, but with limited certainty on relative strength, NBM slight chance to chance PoPs are held onto for the end of the forecast period. With widespread rain coverage ahead of the front on Tuesday, highs are likely to be limited to the lower 80s. Post-frontal, Tuesday and Wednesday nights will be in the low to mid 60s. For the end of the week temperatures and humidity will start to climb again, to the upper 80s for highs and upper 60s for lows. && .AVIATION... Issued at 625 PM CDT Sat Jun 20 2020 Monitoring scattered thunderstorm activity that could impact SEMO/SIL/W. KY terminals early this evening. After that, there could be a bit of a lull before more widespread activity is expected overnight tonight and into the day on Sunday. MVFR ceiling and visibility are forecast during that time, as another round of showers and isolated storms moves through the area from west to east. While the activity will likely exit southeast MO by 12Z, it will take until later in the day for the activity to exit KOWB. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$