Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/14/24


Area Forecast Discussion
National Weather Service La Crosse WI
654 PM CDT Sat Jul 13 2024 .KEY MESSAGES... - Rounds of storms this afternoon through Monday night. Some storms will be strong to severe this afternoon through tonight with damaging wind gusts being the primary threat. Large hail and heavy rain are also possible. Isolated strong storms are possible Sunday with increasing probabilities for strong to severe storms on Monday. - Hot and humid conditions continue this weekend with highs in the upper 80s and lower 90s. Widespread heat indices in the middle to upper 90s with some areas reaching 100 on Sunday. - Cooler and drier conditions beginning Tuesday and into much of the upcoming week with high temperatures as low as the middle to upper 70s by the middle of the week. && .DISCUSSION... Issued at 253 PM CDT Sat Jul 13 2024 Storms, Some Severe This Afternoon Through Tonight: As we continue through the afternoon and evening, a messy interplay of subtle mesoscale thermodynamic features and lifting mechanisms will need to be monitored closely. While the overall conceptual model for today remains vaguely similar with the thermal ridge trying to build in leading to a developing cap. The wrinkle being thrown into this is the convective system throughout the morning and afternoon that pushed through northern portions of the region earlier this morning which leaves some questions for how much instability has been worked over and if any outflow propagation could mitigate the capping we could see later this afternoon and evening leading to some different potential scenarios. With the convection spreading through portions of north-central WI and initiating across portions of MN, observing a fairly worked over atmosphere in these areas leading to relatively limited instability. This in combination with the increasing 700mb temperatures further southwest will setup a fairly sharp MUCAPE gradient later this evening shown in the 13.15z RAP. With this in place, some of the CAMs would suggest a cluster of storms to be able to develop with a very weak nose of 850mb moisture transport (the 13.12z HRRR and ARW are good examples of this). With roughly 25-40 kts of bulk shear and fairly robust MLCAPE (2000-4000 J/kg) present in the 13.15z RAP, would think in this scenario that storm mode would take on a multi-cell, perhaps supercellular configuration as it progresses through with mainly a damaging wind and large hail threat. Would not be able to completely rule out an isolated tornado with some low-level curvature in the KRST 13.17z RAP sounding if this scenario unfolds. The 13.12z ARW family really likes to portray this scenario as well with little development of an MCS later tonight with the shortwave passage, likely due to convective contamination upstream. Not ruling out that the previously forecasted MCS would still manifest in this scenario. However, with downstream convection messing with overall thermodynamics, would have serious implications for this overnight MCS potential as it would have minimal instability to work with. Either way, will need watch this convection over MN closely over the next few hours as the CAMs all disagree with how to handle it. Another possibility, is more development of the thermal ridge leading to the previously mentioned capping inversion further through the local area, similar to previous forecast iterations. Looking at 700mb temps in the 07.12z HREF would suggest keeping the 10-12 C temps southwest of the I-94 corridor. This can be shown with the current probabilities for 10 C temps or greater along the I-90 corridor of 40 to 70%. Additionally, will need to watch how much instability manages to entrain itself across this region with fairly substantial contamination has occurred from ongoing convection across northern WI. Assuming that enough instability is present, damaging wind gusts would be the primary threat with an organized MCS pushing through roughly the I-94 corridor tonight with lower confidence in it organizing further southwest. The degree to which the cap builds in would determine the southwestern extent of this MCS overnight. Widespread rainfall amounts of 0.5 to 1" would be expected with this MCS with locally as high as 2-3" possible per the 13.12z HREF ensemble max for QPF through Sunday morning. However, with the progressive nature of these storms would expect any flooding concerns to be very isolated. The key takeaways from all of this would be that much of how the cap and convection early in day affected it will determine how convection will manifest later this evening and into the overnight. Two scenarios are present with an MCS overnight within the vicinity of the I-94 corridor being one possibility. However, uncertainty remains in exactly how far northeast the cap develops through the evening and overnight and if instability has been mitigated due to earlier convection. Additionally, will need to be vigilant for a secondary scenario with severe storms this evening if any outflow boundaries from ongoing convection in central MN can manifest anything. Damaging wind gusts will be a threat with both scenarios but large hail cannot be ruled out with any quasi-discrete convection when also considering mid-level lapse rates of around 7C/km. Additional Storms, A Few Strong to Severe into Monday: Sunday continues to trend more on the conditional side for any severe weather with the aforementioned cap firmly in place during the morning. With the lack of any shortwave energy, the main forcing mechanism for any convection during the day on Sunday would be residual outflow boundaries from prior convection overnight Saturday. While the cap does try to erode towards peak heating, would say that you are less likely to have any residual outflow boundary later into the day with the MCV associated with tonight`s convection well south and east. Overall would anticipate with the stronger cap earlier in the day and lack of forcing later into the day would enable a drier trend but will hold onto some precipitation chances (15-30% chance) when considering how much instability will be present (4000-5000 J/kg of MLCAPE in the 13.15z RAP), not much would be needed to initiate convection. Further potential for strong to severe storms are possible Monday and Monday night as additional pieces of weak shortwave energy push through the region during the afternoon/evening hours dragging a surface cold front along with it. Instability ahead of the boundary looks fairly solid with MLCAPE values of 3000-4000 J/kg and more robust shear profiles relative to this weekend in the 13.12z NAM which would be fairly favorable for more organized severe storms along this boundary. With the cap still a question as shown earlier in the day in the 13.12z NAM but does try to erode by mid-day. Consequently, the SPC has a Slight Risk (Threat level 2 of 5) for their day 3 outlook to address this potential. Heat Continues Through Monday: With the aforementioned warmer air aloft building overnight and into Sunday, zonal to northwesterly flow aloft coupled with south/southwesterly surface flow will allow temperatures to trend above normal for the weekend and Monday. Sunday likely will trend warmer than today with 13.13z NBM having a 25th to 75th percentile spread for highs at La Crosse of 90 to 94 degrees. With southerly flow helping aid dewpoints in the lower to middle 70s on Sunday, pretty good consensus that heat indices will near 100 degrees for some locations for Sunday. Could still see some storms on Sunday with any residual outflow boundaries that may be present so still some potential for temperatures to remain cooler if storms develop, but overall would expect temperatures to trend warmer in either case. Saturday and Monday will likely trend warmer as well however, with convection around probably will trend slightly cooler but still above normal with heat indices in the 90s for most. Drier, Cooler by Tuesday Through The End of the Week: As we head into Tuesday, northerly flow will help aid in cooler air to be advected into our region behind a cold front that progresses through our region aided by a shortwave late Monday. Consequently, t he 13.00z grand ensemble (GEFS/EC ensemble/Canadian ensemble) generally trend temperatures below normal, having an inter-quartile range of 72 to 77 degrees for highs on Wednesday at La Crosse with similar degree of confidence throughout the rest of the week. Additionally, as a surface high pressure pushes into the region mid- week shown in the 13.12z GFS/EC/NAM, would expect minimal precipitation chances from Wednesday through Friday. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 628 PM CDT Sat Jul 13 2024 Ongoing strong to severe storms extend through much of the Upper Mississippi River Valley. Both TAF sites (KLSE/KRST) have and will be impacted over the next few hours. Isolated severe storm situated near KRST has had a slow storm motion so have kept TS till 05Z. Subsequent storms expected overnight. Limited confidence for storms. If they do form, expect a northwest to southeast motion late tonight into early tomorrow morning. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Naylor AVIATION...JAR
Area Forecast Discussion
National Weather Service Burlington VT
711 PM EDT Sat Jul 13 2024 .SYNOPSIS... Scattered showers and isolated thunderstorms this afternoon will diminish this evening for a quiet, yet mild and foggy night. Hot temperatures up to the lower 90s are once again expected Sunday through Tuesday along with increasing humidity, before a cold front on Wednesday brings another round of rainfall to the region. Following the frontal passage, a return of cooler and less humid air is expected. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 704 PM EDT Saturday...Best forcing associated with weak short wave energy has shifted east of our fa, along with highest concentration of showers with embedded rumbles. Going fcst has this trend covered very well with clearing skies anticipated with building 1020mb high pres. These clearing skies wl result in areas of dense fog, especially northern Dacks and valleys of central/northern VT, including the NEK and CT River Valley. All covered well with no changes needed. Previous discussion below: A modest mid-level shortwave passing north of the Canadian border combined with our continued humid airmass was enough to spark some showers and thunderstorms off the lake breeze this morning which drifted into Vermont and intensified to just below severe limits earlier this afternoon. As of writing this, lightning has become much more isolated to nearly none, but scattered showers continue to shift eastward through eastern Vermont. This activity should continue east of the region while waning through sunset and a quiet yet muggy night is expected thereafter. Fog is once again likely in the favored river valleys after midnight through sunrise, and lows will be similar to last night ranging through the 60s with locally some mid/upper 50s in the Adirondacks. For Sunday, a weak ridge aloft and surface high pressure will keep the region dry. A very isolated shower can`t be ruled out, but the chance of that is 10% or less and not worth worrying about. 925mb temps will once again be on the rise to neat +23C so widespread highs in the mid to upper 80s is likely with some lower 90s possible, especially in the lower Connecticut River Valley. Dewpoints will be slightly lower than today in the upper 50s to mid 60s so heat indices won`t be in the dangerous category. Of additional note will be the chance for some Canadian wildfire smoke to be aloft towards evening based on the latest HRRR forecast. No pollutants are expected at the ground, but may make for an interesting sunset. Finally for Sunday night, another weak to moderate shortwave is progged to move into the eastern Great Lakes increasing the chance for showers across northern New York after midnight. Elsewhere the night should be dry with increasing clouds leading to lows warmer than the previous night in the mid 60s to around 70. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 317 PM EDT Saturday...The Champlain and Connecticut River Valleys could very well be in the middle of a heatwave by Monday. Models have been very consistent placing a strong high pressure over New England, with 850 temperatures reaching up to 25c on Monday. Humidity levels will exasperate the problem, leading to a concerning situation in terms of heat risk. We are also tracking the chance of showers or thunderstorms. The thermodynamic profile is favorable for development, but we will lack the shear required to truly allow for severe storm development. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 317 PM EDT Saturday...Our heat will peak on Tuesday, with temperatures climbing an addition degree or two with dewpoints at or above 70 in many locations, this combination would push heat index values above 95F and reach advisory criteria. Tuesday is also more favorable for thunderstorms than the previous days as our shear profile increases. By Wednesday afternoon, we will get our long awaited cold front, knocking 10F off our temperatures. A line of showers will sweep by along with the front, with pwats up near 1.75" these storms will be efficient rain makers and we are under a marginal ERO for the day. The good news is the storms will move by quickly, and we`ll be a week removed from the recent flooding giving the soils and rivers some time to recover. Following the cold front, our temperatures will inch back up but we should have a very pleasant weekend in store. && .AVIATION /23Z SATURDAY THROUGH THURSDAY/... Through 00Z Monday...Aviation challenge is areal coverage of fog/br and timing the development. Highest probability (70-80%) of fog with LIFR/VLIFR is at SLK/MPV btwn 06-11z Sunday. Used tempo groups to indicate developing fog/br btwn 03/04z and 05/06z, before transitioning to prevailing groups. Given rainfall today at PBG and some fog last night, feel intervals of fog is possible (30-40%) at PBG overnight, with slightly higher confidence in IFR and fog at EFK. Elsewhere, <30% confidence in fog development so have not placed in tafs attm. Winds are light and variable overnight into Sunday. Outlook... Sunday Night: VFR. Slight chance SHRA. Monday: VFR. Chance RA, Chance TSRA. Monday Night: VFR. Chance RA, Chance TSRA. Tuesday: Mainly VFR, with local MVFR possible. Chance RA, Slight chance TSRA. Tuesday Night: Mainly VFR, with local MVFR possible. Chance RA, Slight chance TSRA. Wednesday: Mainly MVFR, with areas VFR possible. Chance RA, Slight chance TSRA. Wednesday Night: Mainly VFR, with local MVFR possible. Slight chance RA. Thursday: Mainly VFR, with local MVFR possible. NO SIG WX. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...Lahiff/Taber SHORT TERM...Langbauer LONG TERM...Langbauer AVIATION...Taber
Area Forecast Discussion
National Weather Service Cheyenne WY
549 PM MDT Sat Jul 13 2024 .KEY MESSAGES... - Very hot temperatures will continue through Monday. Heat Advisories remain in effect for the High Plains along and east of I-25. - Increased precipitation chances and cooler temperatures are expected late Monday through Wednesday. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 215 PM MDT Sat Jul 13 2024 Hot and breezy for some areas this afternoon. Seeing critical fire weather conditions over the south Laramie Range and western Laramie County. Getting wind gusts of 30 to 35 mph over the Summit at Pumpkin Vine...Vedauwoo...the UPR sites and Summit. For western Laramie County...Cheyenne is hitting as well as Bear Creek and Otto. Will keep current RFWs going as they are. For Converse and Niobrara Counties...humidities are finally starting to get down near critical and wind gusts are up near 20 mph. Still have time for these two zones to verify. HRRR and RAP simulated radar showing isolated storms developing this afternoon and continuing through mid evening. Can`t really rule out isolated thunderstorms late this afternoon and evening...so followed their guidance on timing/locations. High based storms will likely create wind gusts to 60 mph across the Panhandle. Have forecast DCAPEs up near 1500-1700 J/KG...so a few severe wind gusts are possible. SPC has a Marginal Risk for severe thunderstorms over the Panhandle this afternoon/evening. Increasing PWATs Sunday should lead to a greater coverage of convection Sunday afternoon/evening. These storms will once again be high based. Mid crew may want to consider fire weather headlines for dry thunderstorms for Sunday with these high based storms. Finally get a good surge of monsoonal moisture Monday with PWATS over an inch in the Panhandle and near .9 inch here at Cheyenne. Continued high PoPs for Monday afternoon and evening where we could see storms producing moderate to heavy rainfall. Forecast soundings showing long skinny CAPE profiles indicating heavy rainfall. Forecast storm motions are in the 20-30 kt range...but if we get training storms...then flash flooding could become an issue. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Issued at 215 PM MDT Sat Jul 13 2024 Unsettled weather is expected in the long term forecast, with the next upper level feature centering itself across the Four Corners by the early morning hours on Tuesday and persisting through the remainder of the period. Before the onset of an emerging Omega Block pattern, strong moisture return and several shortwave disturbances propagating within the flow will result in numerous storms to develop across the region on Tuesday afternoon and evening. PWATs continue to look good, with values ranging from 0.75 to 0.92 inches and hovering around the 75th to 90th percentiles for this time of year. Some locally higher PWATs anomalies are currently in the forecast with upwards of 1.20 inches possible for the far counties in the Nebraska Panhandle that will need to be monitored through the weekend and into the early portions of next week. For Wednesday and onward, Deterministic and Ensemble model guidance has remained consistent over the last few days, with good model agreement and placing an Omega Blocking pattern just slightly off centered across the CONUS. As a result, should see the dome of high pressure become much more cemented in place and stretching across the Four Corners and into the Western Seaboard. Storm chances still continue throughout the week, as shortwave disturbances continue to undercut the main ridge. However, due to the positioning of the blocking pattern, will not see the stronger moisture as will possibly be observed on Tuesday. Nevertheless, will need to continue to monitor thunderstorm potentials the throughout the week, especially for the Nebraska Panhandle where better atmospheric dynamics will likely be present. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 538 PM MDT Sat Jul 13 2024 A few isolated high-based showers are moving through the area this evening, and may bring localized gusty winds to terminals over the next 1-3 hours. Otherwise, good aviation conditions through the night and Sunday morning, before another round of showers and possibly a few thunderstorms develops early Sunday afternoon. This activity may be a little more widespread than the last few days. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Heat Advisory until 8 AM MDT Monday for WYZ101-102-107-108-118- 119. Red Flag Warning until 8 PM MDT this evening for WYZ417-418- 429-430. NE...Heat Advisory until 8 PM MDT Monday for NEZ002-003-019>021-054- 055-095-096. && $$ SHORT TERM...GCC LONG TERM...MRD AVIATION...MN
Area Forecast Discussion
National Weather Service Quad Cities IA IL
644 PM CDT Sat Jul 13 2024 .KEY MESSAGES... - A Heat Advisory is in effect until 8 PM this evening for the counties roughly along and south of I-80 for peak heat indices of 100 to 105 F. - The heat continues for Sunday and Monday with peak heat indices between 100 to 110 F. - Organized thunderstorms are possible late tonight with a cluster of storms moving in from the north/northwest. This could bring gusty winds and heavy rainfall. Additional rounds of scattered storms are possible Sunday and Monday. - Moderate to major river flooding continues on the Mississippi River with most sites crested or cresting in the coming days. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 230 PM CDT Sat Jul 13 2024 Late This afternoon through Tonight: SPC mesoanalysis had a mid-level vorticity max over Minnesota/Wisconsin with a southwesterly LLJ to the south across the Mid to Upper Mississippi Valley. Warm air advection on the nose of the 850mb jet has kicked off a few scattered showers and storms across the far eastern portion of the area, mainly from near Freeport down toward Princeton. Much of this activity should shift to the east of the area by the late afternoon hours. Heading into late this evening and the overnight, confidence remains low on the potential for convection. Latest HRRR runs hold the organized storms well to our north across Minnesota and Wisconsin, while the NAMnest drops a line of storms in from the north after midnight. Will maintain 20-40% chances in the forecast through the overnight, highest across the NE portion of outlook area. If storms do manage to drop southeastward into the local area tonight, the primary threats would be strong winds and frequent lightning. Moderate MUCAPE and modest deep layer shear would be supportive of strong to severe storms, which is in line with SPC`s Slight Risk across the north and northeast, and Marginal Risk to the south. Sunday: Low chances for showers and storms will continue through the day with potential for scattered strong to severe storms developing during the late afternoon and evening. Confidence is low on this late PM development; however with a very unstable air mass due to the hot/humid conditions, presence of any low- level outflow boundaries, and potential for a mid- level wave to roll west to east across the area, the threat for at least scattered strong/severe storms will have to be monitored closely. Highs in the upper 80s to lower 90s are forecast, with dewpoints in the lower to mid 70s. Heat indices are forecast in the upper 90s to near 105 degrees (highest south of I-80). Through early next week, 850mb temperatures are forecast to be 24 to 27C, which is strongly supportive of excessive heat. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 230 PM CDT Sat Jul 13 2024 The hot weather will continue on Monday with chances for scattered showers and storms as a cold front gradually drops in from the north. Models continue to show a strong EML, but the frontal position could serve to erode that with time, especially after dark. The ample CAPE over 3000 J/KG would support strong storms, as would the increasing shear from the westerly flow aloft. For now, pops are in the 30-60% range by Monday night. Tuesday is a transition day into the far cooler air in the extended. Highs will be rather warm, but with decreasing humidity and gusty winds, the heat stress will be decreasing through the day. Wednesday though Saturday continue to look very pleasant, with highs in the 70s to low 80s, and lows in the 50s! && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 631 PM CDT Sat Jul 13 2024 VFR conditions are forecast through the period. A prob30 group was placed in the TAFs for both KDBQ and KMLI between 9 and 13z on Sunday for a potential line of thunderstorms that is forecast to sink southward across the area during the morning. MVFR visibilities are possible with this line of storms as it sinks southward. Winds will turn to the southwest after 15z Sunday with speeds of 10 to 20 knots. && .HYDROLOGY... Issued at 938 AM CDT Sat Jul 13 2024 The crest on the Mississippi River is now between Keithsburg, IL and Gladstone, IL (L/D 18). Upstream of New Boston (L/D 17) river levels continue to fall. New Boston and Keithsburg are just starting to show signs of falling. As the broad crest continues to attenuate, areas from Gladstone downstream to Gregory Landing should begin a very broad crest over the next day or two. Tributary Rivers: On the lower Cedar River near Conesville, IA, minor flooding continues. Over the next 24 to 36 hours the flooding is forecast to end. The lower Wapsipinicon River near Dewitt, IA will remain in moderate flood through mid-day Sunday before falling into minor flood. A fairly rapid drop in water levels will commence Sunday afternoon and night as backwater effects from the Mississippi River decrease. Minor flooding continues on the lower Iowa River at Oakville due to backwater effects from the Mississippi. With the broad crest on the Mississippi now just south of Keithsburg, IL, water levels on the lower Iowa River will slowly fall to and then remain around flood stage over the next four days. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Heat Advisory until 8 PM CDT this evening for IAZ063>065-067- 068-076>078-087>089-098-099. IL...Heat Advisory until 8 PM CDT this evening for ILZ015-016- 024>026-034-035. MO...Heat Advisory until 8 PM CDT this evening for MOZ009-010. && $$ SHORT TERM...Uttech LONG TERM...Ervin AVIATION...Cousins HYDROLOGY...08
Area Forecast Discussion
National Weather Service Glasgow MT
134 PM MDT Sat Jul 13 2024 .DISCUSSION... AFTERNOON UPDATE: A corridor extending from the Glasgow area southeastward toward Glendive was upgraded to an Enhanced area of severe weather by the SPC earlier this morning. Given morning CAMS mostly showing similar solutions to this afternoon`s convection, SPC felt necessary to upgrade for the risk of large hail (in excess of 2 inches) and severe, damaging winds (possibly as high as 90 mph). For those present in and around Fort Peck Lake for the Gov Cup Walleye Tournament, sudden and erratic wind direction/speed changes are possible generally from a time range of 3pm to 6pm. Afterward, most of the CAMS show a linear MCS forming from the merging of previously discrete supercells. This appears to really look more like a bowing structure as the storms approach the I-94 corridor. Plenty of hazards in play tonight. More info to come as needed. Remain weather aware! -Enriquez PREVIOUS DISCUSSION: KEY MESSAGES: 1) Thunderstorms are expected this afternoon and evening. Some will become severe with damaging winds and large hail. Timing will range around 2PM to 11PM over the bulk of northeast Montana. 2) Hot conditions will continue into the weekend with the heat advisory extended in the far south into Saturday. WEATHER PATTERN OVERVIEW: Upper ridge will remain in place over the western half of the CONUS for the next several days. A cold front will arrive Sunday evening and drop temps off about 5-10 degrees through Wednesday. Heat will be back in sway by late next week with 100s creeping back in as the ridge to the west reestablishes itself. FORECAST CONFIDENCE & DEVIATIONS: The heat advisory currently for the bottom third of counties for Saturday has been left up due to momentum, but the cold air from the thunderstorms outflow yesterday has backed temps off for Saturday to a max of around 97 degrees which is probably too low for it. In addition, there is a chance that widespread thunderstorms in the early afternoon may produce enough cloud coverage to take the impact edge off the highs as well. Will be giving the day shift a chance to let it ride and the option to cancel it early if things do not look to be going that way. While Sunday does have temps reaching up to 100 degrees before the front arrives that evening, there is cooler temperatures Saturday night which will allow for some recovery in the heat risk. Therefore, will be delaying issuing an extension for Sunday for now. Keeping an eye to smoke models has allowed for some haze to sneak into the area over the next couple days. Air quality only remains moderate but will need to be monitored through the next several days. CAMs models for thunderstorms this afternoon have spread out the area being affected toward the south by about a county and half compared to 24 hours ago. They have also clumped the initiation of the storms around Noon to an hour or two after. However, there is an outlier in the HRRR which doesn`t bring storms through till nearly 6PM. It looks like mesoscale details such as lingering outflow boundaries from yesterday will be the deciding factor for this afternoon and this is adding quite a bit of uncertainty to timing and spatial placement of storms in addition to the strength of the heat. First 24 hours of PoPs were again updated to include a 50/50 blend of the SREF NPoP along with the NBM PPI01 in order to capture the afternoon thunderstorms better with the marginal threat for severe weather in the area. This bumped PoPs up from a meager 20%-30% to nearly 60% around the most certain areas. First 48 hours ended up getting a bump with the shrink stretch tool over the CWA for afternoon highs and overnight lows, as RTMA/URMA map passes are continuing to miss, skip, or average out ASOS/AWOS highs by roughly 2 to 4 degrees and this is clearly biasing baseline NBM downward compared to the reality of these 100 degree+ extremes which have occured over the last 2 days. GAH && .AVIATION... LAST UPDATE: 1930Z FLIGHT CAT RANGE: VFR - MVFR DISCUSSION and WINDS: Storms are again expected this afternoon and evening. Initially, discrete supercells can be expected across Phillips and Valley Counties. As the storms approach KGGW and surrounding areas (3pm to 5pm), the main threat will be large hail in excess of 2 inches and damaging winds. As the storm approaches KSDY and KGDV, the outflow associated with these storms will cause erratic and gusty winds possible in excess of 60 kt (5pm to 8pm). Winds after the storms will light and variable (after midnight local time), becoming more NW`ly Sunday afternoon at 5 to 10kt. DENSITY ALTITUDE: Afternoon highs could break 100 degrees in some places through Sunday. This will make for less dense air and lead to a need for increased power and longer runway takeoffs. -Enriquez && .GGW WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 9 PM MDT this evening for Garfield-Petroleum- Prairie. && $$ weather.gov/glasgow
Area Forecast Discussion
National Weather Service Green Bay WI
1043 PM CDT Sat Jul 13 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - Isolated strong to severe storms into early this evening with another possible round of strong to severe thunderstorms overnight tonight. Damaging winds are primary hazard. Smaller chance of storms on Sunday, then additional strong to severe storms on Monday as cold front crosses. Overall confidence on details for the rounds of storms is low to medium. - Warmer and more humid conditions through Monday. Heat index values in the 90s are expected over central, east central and parts of far northeast WI Sunday into Monday. Heat indices could approach advisory criteria for a time in the afternoon across the southern CWA on Sunday. Thunderstorm development and clouds could also provide relief from the heat at times. - Cooler and drier conditions expected mid-late next week. && .DISCUSSION... Issued at 312 PM CDT Sat Jul 13 2024 Short Term...Tonight and Sunday Main forecast concerns will once again revolve around severe weather potential for later this evening and overnight. Unfortunately, most CAMs seemed to mishandle the MCV over Minnesota as well as the concurrent line of elevated storms out over western Wisconsin. A variety of different potential scenarios will thus result in another low confidence forecast. Convective trends... An elevated line of storms continued to ride along a gradient of 850 mb moisture and mixed layer CAPE throughout the early afternoon, although dry air intrusion and slight capping kept it at bay as it moved east. What comes next is still up in the air. Decent instability (~1,500 J/kg CAPE) may be enough to generate some pulse storms later this afternoon, although coverage will likely be isolated given the absence of any surface features or triggers to focus convection. This being said, anything that does go up may have the potential to produce brief heavy downpours/microbursts as evidenced by inverted-V soundings and appreciable downdraft CAPE (~1,000 J/kg). Regardless, high convective temperatures and low-level capping will be negating factors for storm generation. Severe weather potential... CAMs still seem to be on different pages with how convection will pan out later this evening and overnight. Although confidence is increasing in the passage of an MCS overnight, still some concerns with how the latest suite of CAMs have struggled to initialize. The HRRR is definitely the most aggressive solution thus far, developing an organized squall line across central Minnesota late this evening before diving it down across the forecast area overnight. This scenario would likely result in a damaging wind threat, especially as a nocturnal LLJ builds in across northern Wisconsin at the base of an upper-level shortwave. Mid-level lapse rates and wet bulb zero heights would support hail as a secondary threat. Heavy rainfall will also be possible, although current thinking is that storm motion will be quick enough to limit widespread flooding concerns. Additionally, a brief spin-up cannot be ruled out with this type of storm mode. Fog/smoke... Depending on what time storms exit the area, some patchy fog will be possible across portions of central to north- central Wisconsin Sunday morning. Dewpoint depressions at or near zero combined with light winds and recent rain will create conditions favorable for ground fog. Will need to monitor for areas of potentially dense fog on Lake Michigan Sunday morning given water temperatures in the low to mid 60s and increasing dewpoints. The RAP and HRRR continue to show areas of elevated smoke across the upper Midwest through the weekend. As a plume of thicker smoke makes its way across the US/Canada border and spreads over Lake Superior Sunday night into Monday morning, visibility reductions and health concerns may come into play toward the end of the forecast period. Otherwise, will have to see whether or not thinner smoke coverage today will affect temperatures later this afternoon. Even a fluctuation of a degree or two might be enough of a hindrance to prevent us from reaching convective temperatures this afternoon and evening. Temperatures... Persistent southerly flow will advect in a true summer airmass as temperatures climb into the low 90s and a surge of low-level moisture brings dewpoints up into the low 70s. Sunday will likely be the warmest day with heat indices ranging from the mid to upper 90s. Suspect that we will stay just below heat advisory criteria given the effect of trailing cloud cover and precip, as well as short temporal span. This being said, the occasional 100 heat index reading would not be out of the question if temperatures/dewpoints trend higher than what we`re currently seeing. Long Term...Sunday Night Through Saturday Rounds of strong to severe storms on Monday with heat and humidity breaking by Tuesday. Sunday night...Relative lull expected most of the night. May still be isolated to scattered storms early on over southern area as weaker shortwave shifts by mainly to the south. Late Sunday night another shortwave could bring small chance of storms into western cwa late. Ahead of the primary cold front, so a warm/muggy night is in store, especially for the Fox Valley to the lakeshore. Monday...Still shaping up to be potential severe weather day. The hot and humid airmass from the weekend will still be present, providing the instability before a cold front sweeps across the region in the afternoon. Bulk shear during this period will be sufficient, with values around 40 to 50 knots as strong shortwave works through which would support organized, relatively fast moving convection. Though some storms could occur early on, stronger risk for severe will be as the cold front arrives Monday afternoon. Potential for an organized and fast moving convective system is certainly there, but details still need to be sorted out. If this occurs, damaging wind gusts will once again be the primary convective threat. Rest of the forecast...Behind the active weather Monday, northwest flow returns. Temperatures will drop to below normal, with highs back in the 70s for the middle of the week. This forecast may still see occasional showers across the north as weak impulses cross far northern WI, but nothing as active as today through Monday is expected to be. && .AVIATION...for 06Z TAF Issuance Issued at 1043 PM CDT Sat Jul 13 2024 Thunderstorms developing across Minnesota have recently been progged by the CAMs models to mainly miss the area, and the TAF sites, tracking through western Wisconsin during the overnight hours into Sunday morning. Given the drier trend with the CAMs models, and the atmosphere being worked over across the region, will pull the precipitation from the TAFs with this issuance. Some low clouds may linger early in the TAF period behind the departing precipitation, but should dissipate within a few hours. The rest of the TAF period later on Sunday should be quiet with VFR conditions expected as most models focus additional showers and thunderstorms south of the area Sunday afternoon and evening. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Goodin/JLA AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Grand Rapids MI
1003 PM EDT Sat Jul 13 2024 .KEY MESSAGES... - Round of Thunderstorms Possible Overnight into Early Sunday - Late Sunday Storms Possible Mainly Near/South of I-96 - Strong to Severe Storm Chances Monday - Dry and Cooler End of the Week && .UPDATE... Issued at 1003 PM EDT Sat Jul 13 2024 Storms approaching the western shore of Lake Michigan will continue to work toward lower Michigan over the next few hours. A southern surge toward Milwaukee and northern Illinois starting to drive the risk for severe weather overnight a little further south. Best instability at mid lake closer to South Haven and points south and this should be where our greatest risk for any severe winds are well after midnight. Overall severe risk seems pretty low for most of west Michigan overnight. Still watching though the impact the trailing MCV in Southwest Minnesota will have on storms by Sunday morning that could lead to increased risk of heavier showers persisting over the same areas. && .DISCUSSION... Issued at 315 PM EDT Sat Jul 13 2024 - Round of Thunderstorms Possible Overnight into Early Sunday The first period of interest to watch will be late tonight into Sunday morning. While severe weather is unlikely, thunderstorms containing heavy downpours and some locally gusty winds are possible. An isolated instance of damaging wind gusts around 60 mph is possible mainly across the lakeshore counties. An MCV is moving through north central WI this afternoon. Additional scattered storms are occuring in MN. The primary feature to watch into this evening and tonight will be where the MCV goes and what, if any, additional storm development could occur along, ahead of, and/or behind this feature. The 12z CAMs depict various outcomes, with some suggesting little to no thunderstorm activity overnight into Sunday morning, but the HRRR often has a superior handle on convective mode and timing (and will also give a nod to the 00z NAM 3km, which did well with location and extent of storms in MN this morning). The MCV will head into an unstable environment in eastern WI albeit with weak deep layer shear. In Michigan, our deep layer shear looks poor even at 06z (less than 20 kts), but does bump up to around 30 kts by 12z as we do see a modest 30kt LLJ aim toward the region. Around and after 06z, the HREF 4hr max dBZ with neighborhood probability for over 40 dBZ (within 20 km of a point) tops out around 50% across the CWA, indicating that a fair amount of the membership has heavier storm activity over us but a fair amount doesn`t. Again, am leaning on the better performing guidance for this forecast period. Given the orientation of the MUCAPE gradient overnight, could envision storm activity across northeastern and east central Wisconsin moving E/SE over Lake Michigan and into west central Lower Michigan, with additional backbuilding thunderstorms possibly occurring as the LLJ feeds them. Will also be watching for MCS development likely across MN overnight that could catch up to existing activity in WI and press toward Lake Michigan, arriving mid morning Sunday. If this scenario occurs, some heavy amounts of rain with localized street/poor drainage flooding is not out of the question. While some gusty winds could occur (primarily 40-50 mph), the 24 hr HREF LPMM tells the bigger story that the late night and morning storms could easily lay down 1" or more in spots. While location and geographic coverage is tough to pin down, the favored area is the lakeshore but this does extend toward US 131 also. - Late Sunday Storms Possible Mainly Near/South of I-96 Better upper level synoptic support will be in place Sunday evening and night as an upper jet with left exit region divergence moves in. At 500 mb, another shortwave trough is shown in WI at 00z Monday and a LLJ of 35-40 kts is forecast to move over northern IN. A stationary boundary is slated to be draped over the state during this time as well. Deep layer shear around 30 kts with SBCAPE of 2500 J/kg and PWATs of 1.8"-2.0" should be supportive for thunderstorms especially toward late afternoon and evening, and given the stronger wind fields aloft there is a better risk for damaging wind gusts and hail especially from I-96 to the south. The storms will be efficient rain producers, with yet another risk for 1" or more of rain in spots. - Strong to Severe Storm Chances Monday Another hot and humid day Monday with 850mb temps at 20C and dewpoints surging into the mid 70s. A mid-level wave will push a cold front through the region Sunday afternoon to Tuesday morning while a warm front extends from MN/IA eastward towards northern IL. To our west, thunderstorm activity will start off north of the warm front and along/ahead of the cold front and will track eastwards into WI and MI. Across our area substantial instability will build to 3000+ J/kg with PWATs surging to 2+ inches ahead of the front with bulk shear to 40 to 50 knots. Much of the setup will be resultant on how prior convection evolves Saturday night and Sunday night, therefore a fair amount of uncertainty exists on where the exact corridor of thunderstorm activity will track. However, generally the most likely corridor looks to be upstream convection across MN/IA/WI propagating toward southwest Michigan during the late afternoon to evening hours. Damaging wind gusts are the primary threat. - Dry and Cooler End of the Week Upper troughing settles in over the region and cold air advection brings in more comfortable conditions. Surface high pressure will scour out any lingering moisture, so expect dewpoints back into the 50s. Plenty of sunshine into the end of the week apart from typical diurnal cumulus. High temps in the 70s starting Wednesday. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 702 PM EDT Sat Jul 13 2024 A complicated aviation forecast is in store for the next 24 hours. Currently widespread VFR conditions are ongoing with scattered diurnal cumulus and high clouds across West Michigan. After 06z tonight, the remnants of a convective system approach the area bringing mid-level to high clouds across the area. Conceptually, the decaying line of storms that has developed across WI and MN will ride the instability gradient into SW Michigan. However spread across solutions in coverage and strength of storms is high. Will leave the current forecast as is with VCTS from 07z-14z at MKG, AZO, BTL, and GRR. MVFR visbys are possible in any storms. The HRRR guidance shows secondary development occuring behind the line, however confidence in this scenario is to low to include. Will reevaluate TAFs after the 00z suite of CAM guidance comes in and amend if confidence grows in storm placement and timing. Mostly cloudy skies with clouds above 10kft expected tomorrow after storms end with south-southwest winds of 10-15 knots gusting to 25 knots. Weak signal for additional storms to develop near AZO and BTL after 20z Sunday, however this is low confidence as it depends on how morning storms go. Will leave this scenario out of the TAFs but reevaluate and amend as needed. && .MARINE... Issued at 303 PM EDT Sat Jul 13 2024 Little wave action is expected for the remainder of today and tonight given light winds. However, waves do look to pick up into the 2-3 ft range Sunday as southwest winds increase to 10-20 kts. At this point it does not look like winds will be strong enough or waves high enough to reach SCA. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Air Quality Alert until midnight EDT Sunday night for MIZ050-056- 057-064-071. MARINE...None. && $$ UPDATE...Maczko DISCUSSION...Hoving AVIATION...Thomas MARINE...Hoving
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
805 PM CDT Sat Jul 13 2024 .KEY MESSAGES... - Hot and humid weather will prevail Sunday and Monday...with afternoon heat index values peaking above 100 degrees both days. - The primary focus for thunderstorms and potential severe weather will remain north of central Illinois for the next couple of days. As a cold front drops southward, the chances for storms will increase markedly by Tuesday. - Below normal temperatures will return by the middle and end of next week as highs drop back into the upper 70s and lower 80s Wednesday through Saturday. && .UPDATE... Issued at 804 PM CDT Sat Jul 13 2024 Main forecast concern this evening is with the potential for a line of storms to dig south into portions of central Illinois overnight. As of 8pm this evening, QLCS is in place across portions of central and southern WI and extrapolation of this line brings it into the northern counties of the ILX CWA around or just after midnight tonight. RAP suggests that maintenance of this line of storms is plausible with veering LLJ focused mainly across IA/MO but broad WAA providing moderately strong instability across central Illinois late into the evening. RAP shows MUCAPE in excess of 3000 J/kg still in place at midnight tonight, albeit diminishing. Given the orientation of the LLJ, Corfidi vectors suggest that portions of the storm will be moving almost due south from its current location. After midnight, gradually diminishing MLCAPE, increasing MLCIN, and deep layer shear of 20 kt or less should result in a lowering severe weather threat with time, but a lingering wind threat could reach into portions of central Illinois before this occurs, especially near and north of the I-74 corridor. It`s important to note that a number of CAMs including recent runs of the HRRR keep this activity just off to our north, so there is some lingering uncertainty on the evolution of this system which bears close watching over the next few hours. Deubelbeiss && .SHORT TERM...(Tonight and Sunday) Issued at 247 PM CDT Sat Jul 13 2024 Isolated convection will develop across central Illinois over the next couple of hours then linger until shortly before sunset. After a period of warm/dry weather this evening, attention will turn to developing thunderstorms well to the N/NW of the area across Minnesota/northern Iowa. CAMs continue to be in disagreement...with the HRRR keeping the convection to the north across Wisconsin and perhaps far northern Illinois late tonight. Meanwhile the NAM/WRF-ARW/HRW NSSL all suggest the storms will take a more southerly trajectory and spill into the NW KILX CWA shortly after midnight. Given the current synoptic pattern featuring a prominent upper ridge centered over the Desert Southwest and downstream weak troughing across the Great Lakes/Ohio River Valley, the more southerly trajectory seems plausible. As a result, have introduced 30-40 PoPs mainly for locations north of I-72 late tonight into early Sunday morning. The convection will track further E/SE and dissipate after sunrise, followed by a partly to mostly sunny and hot day. Thanks to at least partial sunshine and SW winds increasing to 10-15mph, high temperatures on Sunday will top out in the lower to middle 90s. With dewpoints in the lower to middle 70s, corresponding heat index values will climb into the 100-105 degree range by afternoon. While there is still some uncertainty about early morning convection potentially keeping the N/NE CWA slightly cooler than forecast, think the prevailing SW winds during the afternoon will cause temps to climb above 90 degrees even at Bloomington/Champaign/Danville. Have therefore opted to issue a Heat Advisory for all of central and southeast Illinois from Sunday afternoon through Monday afternoon. Barnes .LONG TERM...(Monday through Next Saturday) Issued at 247 PM CDT Sat Jul 13 2024 Another round of nocturnal convection will likely develop Sunday night...this time across Wisconsin/northern Illinois into northern Indiana. Will maintain low chance PoPs along/north of I-74 accordingly, but think the bulk of the activity will remain just N/NE of the area. As thermal ridging develops ahead of an approaching cold front, high temperatures on Monday will climb a couple degrees higher than Sunday into the middle 90s. This will result in afternoon heat index readings peaking in the 105-110 degree range, warranting the continuation of the Heat Advisory. As a deep upper low currently over northern Saskatchewan/Manitoba digs southward, it will push a cold front toward central Illinois Monday night into Tuesday. Given high dewpoint air pooling ahead of the boundary and increasing deep-layer wind shear associated with the approaching upper wave, will need to keep an eye out for potential severe weather...particularly Tuesday afternoon/evening as the front sags southward. If frontal timing remains the same, may also need to consider extending the Heat Advisory through Tuesday afternoon for locations south of I-70. Once the front passes, a significantly cooler and less humid airmass will arrive for the middle and end of next week. High temperatures will drop back into the upper 70s and lower 80s while overnight lows will dip into the 50s and lower 60s Wednesday through Saturday. Barnes && .AVIATION... (For the 00z TAFs through 00z Sunday Evening) Issued at 624 PM CDT Sat Jul 13 2024 Low pressure will remain west of the terminals through the period with a modest S/SW breeze through the period, at least outside the influence of any thunderstorms. Storms are ongoing across portions of northern Illinois as well as a line of storms from SE MN across central WI. This more northern line of storms may push south into central Illinois late tonight into Sunday morning. It remains unsure how far south the line will reach, but a prob30 accounts for the potential of it reaching the I-74 corridor in a weakening phase. Expect SW winds to begin gusting around 20 kt mid to late Sunday morning. Deubelbeiss && .ILX WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 1 PM Sunday to 8 PM CDT Monday for ILZ027>031- 036>038-040>057-061>063-066>068-071>073. && $$
Area Forecast Discussion
National Weather Service North Platte NE
632 PM CDT Sat Jul 13 2024 .KEY MESSAGES... - There is little change in the predicted heat Sunday except that high cloudiness Sunday may affect afternoon temperatures. - Heavy thunderstorms are possible late Tuesday and the potential for severe weather appears low. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 403 PM CDT Sat Jul 13 2024 A plume of upper level moisture residing across ID/NV/UT this afternoon will move east into wrn/ncntl Nebraska late tonight and remain across the region during the day Sunday and Sunday night. The 500-300mb RH in the RAP model is the basis for isolated POPs until Sunday evening when deepening moisture will increase rain chances to 30-40 percent across ncntl Nebraska. Severe weather chances tonight through Sunday night will favor wind gusts over hail and the area to watch Sunday will be north central Nebraska where MLCAPE increases to 3000J/KG accompanied by effective shear near 45kts. The HREF shows storm development across the ncntl zone Sunday evening. Otherwise, the models favor the super heated air across wrn Nebraska for high based (500mb) storm development late in the afternoon throughout the evening. The temperature forecast Sunday could be in jeopardy given the expected increase in cloud cover which could limit vertical mixing below the targeted h700mb level. There is weak sfc low pressure across the Dakotas to produce westerlies of just 10 to 15 kts at h850-700mb. A warm front/dryline bulge should move east to near highway 83 Sunday afternoon. 100s are in place across many areas west of 83. H700mb temperatures should rise to 16-17C across the west which is favorable for 100s. Given the potential for cloudiness at times, the temperature forecast is modest and uses the short term model blend. It is near or slightly warmer than the NBM 50th. The latest forecast Sunday continues the Heat Advisory across all of wrn and ncntl Nebraska. This might be generous across the Sandhills where heat indices are projected to remain below the 100F threshold. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 403 PM CDT Sat Jul 13 2024 Temperatures aloft at h700mb will begin to cool with the arrival of a cold front Monday but the models are waiting until late Tuesday aftn/Tuesday night to ignite thunderstorms. Chance/low- end likely POPs are in place and moisture will have pooled to around 1.50 inches of PWAT. Moisture transport will be very modest and gradual. The overall severe weather potential Tuesday appears to be low for this forecast for a few reasons. Wrn/ncntl Nebraska will be post- frontal-a back door cold front will move through Monday and become stationary across the cntl high Plains Tuesday. Sfc temperatures will be cool. Winds aloft will be 25-45 kts at h500-300mb- which is weak for severe weather. Storm development is expected across the Laramie ranges and this storm activity will move east into a moist but more stable environment. The NAM soundings show mid-level lapse rates which are nearly moist adiabatic. So, for now it appears weather conditions will favor ordinary thunderstorms. The upper level ridge of high pressure producing record heat across the wrn U.S. will amplify north into wrn Canada Wednesday through Saturday. This will place wrn/ncntl Nebraska in a strong northwest or even north flow aloft. The models are signaling an increase in moisture next Saturday and this is occurring from subtropical sources and nrn stream sources. Rain chances are isolated to low-end chance and later forecasts will raise the POP if warranted. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 632 PM CDT Sat Jul 13 2024 VFR conditions are expected to continue through western and north central Nebraska tonight through tomorrow evening. Isolated to scattered thunderstorms will be possible this evening across portions of northern Nebraska, the Sandhills, and the Panhandle. Have omitted thunder from the TAFs at this time, as confidence remains low in thunder in vicinity of the terminals. Otherwise, winds remain light and variable through tomorrow afternoon, with few to scattered passing high clouds. && .LBF WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 7 PM CDT /6 PM MDT/ Sunday for NEZ004>010- 022>029-035>038-056-094. Heat Advisory until 7 PM CDT /6 PM MDT/ Monday for NEZ057>059- 069>071. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Richie
Area Forecast Discussion
National Weather Service Marquette MI
740 PM EDT Sat Jul 13 2024 .KEY MESSAGES... - Seasonably warm this afternoon with a 20-30% chance of showers/thunderstorms over the west. - 40-60% chance of showers and thunderstorms this evening into overnight hours. Marginal risk (category 1 out of 5) of severe thunderstorms for most of the UP. Slight risk (category 2 out of 5) for the far west. Main threats are large hail and damaging winds. - Chances (20-40%) for thunderstorms along lake breeze boundaries Sunday. - Marginal risk (category 1 out of 5) of severe thunderstorms Monday. - Cooling and drying trend into the midweek portion of next week with the arrival of high pressure. && .UPDATE... Issued at 739 PM EDT Sat Jul 13 2024 Ongoing showers and severe thunderstorms in central Wisconsin should continue pressing southeast through the evening. Some sprinkles/light rain may fall in and around Menominee, but otherwise, mostly dry conditions are now expected for the next few hours. Current satellite analysis shows what appears to be a stable strato layer of clouds over western Upper Michigan, implying a more stable atmosphere. East of this area, a north south boundary is apparent on radar through Marquette County. This boundary may be the focus for some late evening convection, but this is very uncertain. East of the boundary, SPC Mesoanalysis shows very little instability, and without any real shear to speak of, I`m skeptical about any organized development. With this being said, the HRRR, which has been the most consistent hourly CAM this afternoon/evening so far, is insistent on scattered showers and storms developing around 4-7z along and just east of this boundary. Will continue to maintain low POPs elsewhere in the western Upper Michigan given the continued uncertainty in this forecast. Upstream in northwest Minnesota, some convection has been observed. If upscale development continues as the HRRR implies, development would congeal into a bowing segment as it tracks southeast into western WI after midnight eastern time. If this development occurs as stated, main risk area for strong thunderstorms would be in areas bordering the Michigan/Wisconsin stateline. However, timing suggests even strong storms may be hard to realize. && .SHORT TERM /THROUGH TONIGHT/... Issued at 1235 PM EDT Sat Jul 13 2024 Upper air consists of an anticyclone centered around the Four Corners and a cutoff low over northern SK/MB. Belt of seasonably fast zonal flow between these two features is diffluent over the local area. Several small areas of convection are noted in this diffluent zone - one in far SW ON, one in northern MN, and one in northern WI. These are being fed by modest SW winds at 850 mb and are located in an area of steep midlevel lapse rates. These lapse rates weaken with eastward extent, and as a result, there is uncertainty whether the lead convective cluster over northern WI will make it into the western UP this afternoon. This cluster has outperformed CAM depictions of it so far, leading to greater than normal uncertainty in its evolution. Have expanded 20-40% PoPs over the far west for mid-afternoon to account for this. Severe risk appears low given paltry bulk shear if storms do indeed unfold this afternoon. Otherwise, a few showers are firing up along the lake breeze in northeast Alger/northern Luce County. Isolated ts possible here this afternoon. Similar low predictability exists in the overnight hours with any MCS activity due to wide variance in CAM output and tendency for better instability to be located SW of the local area. As a result, early afternoon forecast update went with a more broad-brush approach to PoPs in the 50-60% range for the overnight hours. Severe risk (large hail/damaging winds) does still exist mainly for the western half of the UP if an outflow-dominant MCS does develop given respectable convective parameters (1000-2500 J/kg MUCAPE), although deep shear is a bit lacking at less than 30 kt. Otherwise, the other concern is the heat with temps on track to reach the mid-80s to near 90 (warmest in downslope zones near Lake Superior), although dewpoints should mix out a bit in the warmest areas with humidity contribution to apparent temps negligible. && .LONG TERM /SUNDAY THROUGH SATURDAY/... Issued at 353 PM EDT Sat Jul 13 2024 Aloft, the path of most prominent troughs and ridges is well to the north over Canada, leaving the Upper Great Lakes in a primarily zonal pattern through this weekend. This will lead to the primary driver of sensible weather to be weak shortwave impulses in the zonal flow. While the synoptic forcing may be weak and ambiguous, hot and muggy conditions this weekend will allow for instability to grow, allowing for the potential for strong to severe thunderstorms over the weekend and to begin next week, especially in the form of MCS`s. High pressure then settles over the region by Tuesday, allowing for a cooler dry period towards the middle and late week period next week. Sunday, clearing via subsidence following lingering convection from the day prior will allow for some clearing skies. This will lead to a pretty warm day, with highs around 80 except in the south central where highs could approach 90, though the 00Z LREF only gives about a 10% chance of exceeding 90. Moisture values increase as well, with the PWATs exceeding 1.5 inches representing the 90th percentile of climatology by GRB and APX sounding climatology. Dew points are forecast to be approaching 70 for at least some period of time for much of the UP, with the highest chances (30-70%) of exceeding a muggy 70 being the south-central and the east. Monday looks to be similarly warm, though lower chances of dew points being oppressively high. These hot and humid summertime conditions will be accompanied with westerly to west-northwesterly flow at 500mb, which will allow for some minor shortwaves to progress through the region. One of these shortwaves looks to pass just south of the MI/WI state line on Sunday. While mesoscale ridging will act to keep larger-scale thunderstorms away from the UP, the mid 60s+ dew points and 1000- 2000 J/kg of only weakly capped SBCAPE combine for a climatologically favorable setup for convection over the UP. With the southwesterly surface flow contrasting the west-northwest flow aloft, directional shear will be present, though speed shear will be somewhat lacking. Regardless, shear will be present enough to help maintain whatever thunderstorms do initiate, so if enough lake- breeze convergence zones can lift parcels enough to realize the instability, severe weather is still a possibility for Sunday primarily along the lake breeze in the east. Monday, another shortwave passes from west to east across the UP starting in the west in the early morning hours and progressing east throughout the day. Instability does not look as strong with this wave, with the 12Z GEFS mean around 1000 J/kg, but forcing is much better, so thunderstorms are expected with a few being potentially strong to severe, consistent with the SPC Marginal Risk (category 1 of 5). By Tuesday, broad troughing aloft shifts from northern Ontario towards the East Coast and ridging fills in behind. As a result of the advancing ridging, high pressure to around 1020mb will keep weather quiet through at least the end of the week. A cooling trend is also expected to accompany the arriving ridging as north and northwest flow will bring highs only in the upper 60s and low 70s Tuesday through Thursday. Temperatures rebound in the late week towards more seasonably summer temperatures. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 723 PM EDT Sat Jul 13 2024 Upstream convection continues to struggle as it approaches Upper Michigan. Recent satellite imagery suggests a mostly capped environment over western Upper Michigan, which suggests the main concern for convective development will be late evening over central Upper Michigan and then upstream in Minnesota. The former may support some thunderstorms in and around KSAW while the latter would be a concern overnight as it tracks southeast for KCMX/KIWD. This generally matches recent HRRR runs, but it should be stated that there is still a good bit of uncertainty in this. Outside of convection, VFR conditions are expected. && .MARINE... Issued at 353 PM EDT Sat Jul 13 2024 Southerly winds remain below 20 kts today as the pressure gradient stays light. South winds increase tonight over the east to near 20 kts with a 15-25% chance for gusts reaching 25 kts tonight ahead of the next disturbance. Some strong to severe storms are possible tonight, especially across western Lake Superior. The main threats are damaging winds, but large hail is also possible. Another round of storms is expected Monday into Monday night as a low pressure system moves through the area. Patchy dense fog is also a possibility in the wake of any precipitation. Following the Monday/Monday night low presusure`s cold front, west winds increase to around 20 kts across much of the lake Monday night and Tuesday. As high pressure begins to build in mid next week, winds look to fall back below 20 kts, remaining light through the remainder of the forecast period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ UPDATE...JTP SHORT TERM...Thompson LONG TERM...GS AVIATION...JTP MARINE...GS
Area Forecast Discussion
National Weather Service Pocatello ID
932 PM MDT Sat Jul 13 2024 .UPDATE... Evening update to expire the Red Flag Warning for FWZ 475 and 476 and to cancel the Heat Advisory and Excessive Heat Warning. The latest forecast remains on track as increasing monsoonal moisture continues to build in tonight into Sunday and Monday. Isolated to scattered mostly dry thunderstorms are expected as a result with temperatures seeing a gradual cooling trend, falling below headline level levels but still above normal for this time of year. MacKay && .PREV DISCUSSION... /issued 240 PM MDT Sat Jul 13 2024/ SHORT TERM...Tonight through Sunday Night. Early afternoon satellite imagery shows a strong H5 ridge of high pressure overhead centered over the Four Corners region which will continue to bring hot and very dry conditions to our region. Also worth mentioning is the increase in wildfire smoke and haze overhead which will continue to lead to smoky and hazy skies with the current air quality generally in that "moderate" category. Weak monsoon moisture transport over SRN Idaho associated with moisture working clockwise around this area of high pressure has led to an uptick in clouds with radar imagery showing predominantly clouds and or virga so far this afternoon with the closest thunderstorms down in NRN Utah and Nevada. The HREF model probability of thunder through tonight shows less than a 10% chance across our entire region with around a 10-20% chance along the Utah, but we will see that very isolated 5-10% chance today dependent on if we see any organization. High temperatures today will be in the 90s to low 100s before temperatures slightly cool for Sunday by around 3-5 degrees as a shortwave trough ushers in more isolated to scattered coverage of thunderstorms for Sunday. As a result, the current HEAT ADVISORIES and EXCESSIVE HEAT WARNINGS remain on track to expire tonight in coordination with our neighboring offices. As that aforementioned H5 shortwave trough passes overhead for Sunday, PWATs around 0.30-0.60" on Saturday will increase to 0.60- 1.00" on Sunday which will lead to an uptick in shower and thunderstorm potential regionwide. The HREF model picks up on this increasing trend showing a 30-60% chance of thunder for everywhere outside the CNTRL Mountains where a 10-30% chance will exist. The convective environment Sunday afternoon will support around 300-700 J/kg of SBCAPE, 20-30 kt 0-6 km shear, and 8-9 degree/km 700-500 mb lapse rates. As a result, the primary hazards tomorrow will center around gusty outflow winds and any new fire starts given PWATs will be in that typical range we see a mix of wet and dry storms. Outside the CNTRL Mountains, the HREF model shows a 50-70% chance of winds greater than 34 mph with ensemble maximum wind gusts in that 40-60 mph range given elevated DCAPE. Very isolated showers and storms will continue overnight Sunday into Monday as a secondary H5 shortwave building in early next week helps to keep convection going. MacKay LONG TERM...Monday through next Saturday. The continued heat will be the main long term impact through next Saturday. A weak upper level short wave riding on top of the ridge will bring the coolest day of the period on Monday with highs in the lower 90s low elevations and mid 70s to mid 80s in the mountains. Will also have isolated thunderstorms with the system mainly in the mountains. The ridge axis rebuilds over Idaho Tuesday and remains overhead with weak oscillations east and west into next weekend. Some moisture may get trapped in the region and isolated showers and thunderstorms are in the blended data daily, but significant rainfall is not expected and nearly all activity forecast for the central, southern and eastern mountains. High temperatures will remain well above normal with low elevations mid to upper 90s and mountains lower 80s to lower 90s in the Tuesday through Saturday time period. Monday will be the breeziest day with up valley 10 to 20 mph sustained and gusts 20 to 30 mph in the Snake River Plain. With the building upper level ridge much lighter winds expected Tuesday through Saturday. GK AVIATION...For the 18Z TAFS through 18Z Sunday. Will have VFR through Sunday with mainly mid level and high cloud cover as some monsoonal moisture continues to push in from the southwest. Extremely dry so do not have and thunder in the TAFs today in vicinity, but will be a much better chance late Sunday afternoon. Winds generally around 10 knots this afternoon at all sites with some occasional gusts up to 20 knots. Expect similar winds Sunday afternoon. GK FIRE WEATHER... Under the continued influence of a H5 ridge of high pressure centered over the Four Corners Region, hot and very dry conditions continue today with breezy wind gusts peaking around 25-35 mph. As a result, a RED FLAG WARNING is in effect for FWZ 475 and 476 with near critical to critical fire weather conditions possible elsewhere given a very dry air mass in place with winds approaching or reaching critical levels at times. While we are seeing an increase in clouds today on the leading edge of some weak monsoon moisture transport, conditions will remain dry outside of a very isolated 5- 10% chance of thunderstorms this afternoon and evening. Attention tomorrow turns to an approaching H5 shortwave trough lifting NE out of the Great Basin. This trough will help to introduce a NBM 15-35% chance of thunderstorms everywhere outside the CNTRL Mountains where a 10-25% chance will exist. The HREF model is a bit more aggressive with these probabilities, putting about a 30-60% everywhere outside the CNTRL Mountains where a 10-30% chance exists. A mix of isolated to scattered wet and mostly dry thunderstorms are expected tomorrow with a RED FLAG WARNING in effect for FWZ 413 and 427 given the best scattered coverage of storms in theses areas. Elsewhere however, we are also continuing to monitor the potential for expansion of this RFW dependent on further forecasts but keep in mind isolated wet and dry thunderstorms will be possible regionwide tomorrow. The primary hazards with storms tomorrow will center lightning and outflow wind gusts to around 40-60 mph. 30 Thunderstorm chances will continue again into Monday before decreasing in coverage and shifting SE for Tuesday as a slightly cooler air mass settles in early next week. The majority of long range model guidance continues to show a ridge of high pressure building back in by midweek next week which will lead to a warming trend as conditions remain mostly dry. We are still expected afternoon isolated showers and thunderstorms each day through much of next week with a focus over the higher terrain. MacKay AIR QUALITY... Wildfire smoke from regional wildfires across the Intermountain West continues to lead to degraded air quality in that "Moderate" to "Unhealthy for Sensitive Groups" category across much of SRN Idaho. The latest HRRR smoke model keeps wildfire smoke in our area through the weekend which will continue to lead to hazy and smoky skies overhead below about 500 mb. MacKay && .PIH WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from noon Sunday to midnight MDT Sunday night for IDZ413-427. && $$
Area Forecast Discussion
National Weather Service Raleigh NC
940 PM EDT Sat Jul 13 2024 .SYNOPSIS... A strong subtropical ridge will remain over the Southeast through early to mid-week. && .NEAR TERM /THROUGH TONIGHT/... As of 940 PM Saturday... No convection developed along the Coastal Plain this afternoon. As the HRRR correctly predicted, there are some high-based showers to the northwest of the Triad that are slowly moving southeast. However, the 00Z Greensboro sounding showed greatest saturation at around 15 kft, and RH values below 80% from 11 kft to the surface. With automated observations in the area showing cloud heights no lower than 7 kft, and large surface dewpoint depressions, think that these showers are likely virga, with precipitation evaporating before it reaches the ground. Will not make any changes to the forecast at this time, which has the chance for rain ending now. Cannot rule out some patchy fog northeast of the Triangle, where the greatest rainfall occurred over the last 48 hours and is the location where the wind is the most likely to go calm. Lows will range from the upper 60s near the VA/NC border to the mid 70s around Fayetteville. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... As of 257 PM Saturday... Steady warming trend begins Sun with temperatures rising into the mid/upper 90s and heat index values ranging from around 100 to near 105. A lee trough will develop over western NC in between an area of high pressure over the LA riding up into the Ohio Valley and the anchored Bermuda High in the Atlantic. This will prompt mostly southwesterly flow at the surface up through 850mb and advect in warmer temperatures aloft (850mb 19 to 21C). This will support temps rising into the mid/upper 90s through the early afternoon. Point soundings indicate some relatively drier air aloft that will mix down to the surface and keep surface dew points in mid 60s (W) to low 70s (E). This should temper heat indices a bit, but still reach around 100 to near 105 degrees. Isolated locations will likely reach 105 during the afternoon for a brief time, but areal coverage and confidence is low enough to not preclude a heat advisory at this time. Some isolated to scattered showers/storms will be possible Sun afternoon within a hot and humid airmass. Greatest coverage will likely be along the lee trough in the western Piedmont as a low amplitude shear axis sags over the area as well as along the seabreeze, with subsequent showers/storms possible along convective outflows. Severe potential remains low as deep layer shear remains weak (around 20 kts) and warm/dry air aloft will work to combat sustained deep convection. Isolated strong winds cannot be ruled out if deeper convection is able to develop with a deeply mixed boundary layer and DCAPE > 1000 J/kg in place. && .LONG TERM /MONDAY THROUGH SATURDAY/... As of 257 PM Saturday... The main weather story for Monday and Tuesday will be the intense heat, given the pattern which features weak ridging and flow aloft, coupled with H8 temp anomalies of 4-6 deg C above normal. This will result in highs in the upper-90s both days, and some low-100s can`t be ruled out. Heat indices of 105+ are expected from the Triangle eastward on Monday, perhaps reaching as far west as the Triad by Tuesday. In terms of precip chances those days... coverage should be isolated at best both days given the overall weak forcing over the region. PoPs will increase on Wednesday as heights begin to fall in advance of a trough moving across the Great Lakes. With increasing flow above the BL, expect to see the Piedmont trough sharpen and improved low level convergence and subsequent outflow boundaries should be the primary lifting mechanisms for increased shower activity. Shower and thunderstorm activity, which may begin by early afternoon, may help keep high temps limited to the lower 90s. Rain chances will continue to increase, with well-above climo PoPs by Thursday and for Friday and possibly Saturday as well as the aforementioned trough pushes a cold front into the Mid Atlantic and Carolinas regions before stalling over us. That boundary, coupled with another plume of deep moisture will likely result in several rounds of heavy rains. However, that will also keep temps limited to near-climo values. && .AVIATION /00Z SUNDAY THROUGH WEDNESDAY/... As of 725 PM Saturday... A few isolated showers along along the slopes of the Appalachian Mtns have been drifting east toward the Piedmont but have been diminishing quickly. One shower popped up SW of GSO earlier, so another shower in the vicinity of INT/GSO cannot be ruled out through around 02Z based on some hires guidance, but after that no showers are expected overnight. VFR will generally prevail everywhere, with the lone and temporary exception most likely being at RWI where some brief MVFR vsbys are more probable (but still low confidence) after 06Z. A similar day is expected on Sunday, with isolated showers and storms developing over western NC and perhaps impacting INT/GSO late in the afternoon. The seabreeze could trigger a storm near FAY but is less likely and will not be mentioned in the TAF for FAY. Outlook: Isolated afternoon storms could result in sub-VFR conditions at TAF sites early this week, but otherwise VFR conditions are expected until the next front settles into the region with higher chances of convection and flight restrictions late Wed-Thu. && .CLIMATE... Record High Temperatures: July 14: KRDU: 101/1954 July 15: KGSO: 97/1974 KRDU: 99/1997 July 16: KGSO: 99/1915 KRDU: 101/1887 KFAY: 103/1937 July 17: KRDU: 100/1887 KFAY: 102/1932 Record High Minimum Temperatures: July 13: KGSO: 75/2017 KRDU: 78/2017 KFAY: 78/2017 July 14: KGSO: 77/1981 KRDU: 77/2017 KFAY: 80/2017 July 15: KGSO: 74/2019 KRDU: 76/1992 KFAY: 78/2015 July 16: KGSO: 75/2010 KRDU: 77/2010 KFAY: 78/1992 July 17: KGSO: 75/2013 KRDU: 80/1887 KFAY: 77/2019 July 18: KGSO: 76/1986 KRDU: 79/1887 KFAY: 77/2019 July 19: KGSO: 75/2016 KFAY: 77/2023 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...Green SHORT TERM...Swiggett LONG TERM...np AVIATION...BLS CLIMATE...RAH
Area Forecast Discussion
National Weather Service Topeka KS
638 PM CDT Sat Jul 13 2024 .KEY MESSAGES... - Showers and storms may redevelop overnight. Confidence is low due to the low predictability of the pattern. - Heat Advisory remains in effect through Monday for triple digit heat. - Below normal temperatures are forecast for Wednesday through Friday. && .DISCUSSION... Issued at 225 PM CDT Sat Jul 13 2024 19Z water vapor showed the upper ridge centered over the four corners region with northwest flow still over the central plains. There were some elevated showers over south central NEB associated with a subtle wave within the flow. Surface obs showed low pressure over northwest KS. This has kept a gusty south wind across the forecast area as temps warm through the 90s. For tonight through Sunday, the models have struggled with the subtle nature of the pattern and the elevated convection the past couple night. While it hasn`t been perfect, the upglide/saturation on the 315K to 320K isentropic surfaces seemed to provide some idea of where the elevated showers were going to be. With models and water vapor showing shortwave energy remaining weak, think this may be the better clue as to where storms form. With the signal for tonight is not quite as clear on the isentropic surfaces, the NAM and RAP hint at a band of saturation along with some upglide over northeast and east central KS through the overnight period, and have added a slight chance POP to the forecast. This is a low confidence forecast given the limited predictability. If this activity develops, is will probably fall apart by mid morning as the upglide falls apart. By Sunday afternoon models advect a stout EML over the forecast area with 700MB temps increasing between 13C and 16C. This will likely prevent any surface based convection and mid levels are forecast to dry out as the upper ridge propagates east reducing the potential for elevated precip into Sunday evening. So attention turns to the heat. The is good agreement among the operational solutions and the NBM for triple digit heat to continue spreading east through Monday. Even with dewpoint temps mixing out across central KS, air temps and apparent temps look to be around 105 degrees for Sunday and Monday. So will maintain the heat advisory as is. The GFS and ECMWF continue to bring a weak frontal boundary into the forecast area Monday night. Curiously though there is not a lot of convection with the boundary, probably due to the very warm mid level temps with the EML. The NBM has better chances for showers and storms Tuesday night when models prog some shortwave energy moving along the boundary. Still temps for Tuesday should be a little cooler, though parts of east central KS may still be dealing with heat indicies around 100. Models show northwest flow redeveloping for the end of the week and below normal temps as a modified Canadian airmass moves into the Upper Midwest. This seems to be handled by the blend and have not made any changes from the NBM. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 633 PM CDT Sat Jul 13 2024 TAFs are mainly driven by wind for the 00Z period. Gusts should subside with sunset and resume after sunrise Sunday. A 40-45 kt LLJ will become established tonight, but the increase will be gradual through 2kft AGL so have not included LLWS. Confidence remains too low to include mention of TS with chances only around 15 percent late this evening and tonight. && .TOP WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM CDT Monday for KSZ008-KSZ009-KSZ010- KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-KSZ026-KSZ034- KSZ035-KSZ036-KSZ037-KSZ038-KSZ039-KSZ040-KSZ054-KSZ055-KSZ056- KSZ058-KSZ059. && $$ DISCUSSION...Wolters AVIATION...Teefey