Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/13/24


Area Forecast Discussion
National Weather Service La Crosse WI
1033 PM CDT Fri Jul 12 2024 .KEY MESSAGES... - Multiple rounds of storms from Saturday through Monday night. Some storms will be strong to severe with damaging wind gusts being the primary threat. Higher probabilities for severe weather are late Saturday and Monday. - Hot and humid 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 are expected by Tuesday for much of the upcoming week with highs in the middle to upper 70s. && .DISCUSSION... Issued at 121 PM CDT Fri Jul 12 2024 Storm Chances Tonight and Tomorrow Morning: As we head into the overnight hours and tomorrow morning, a more zonal mid-level flow pattern takes shape as a broader ridge builds to the west. Consequently, guidance increases theta-e in the low- levels as this pattern change occurs. This theta-e advection with increasing MLCAPE (1500-3000 J/kg in the 12.09z RAP) by mid morning would suggest some convective initiation. However, with fairly meager effective bulk shear (20 kts or less in the 12.09z RAP), would not expect cells to be able to maintain in an organized manner. Furthermore, with the relatively weaker forcing regime, the latest CAMs generally have minimal convective coverage. However, given the more robust instability, particularly later in the morning, decided to hold onto some precipitation chances (15-25% chance) during this timeframe. Given the robust instability later into the morning and afternoon would not be able to completely rule out some gusty winds or small hail if any stronger cells manifest, mainly across. Severe Potential for Saturday through Monday: A challenging forecast lies ahead for the weekend and early next week as a few rounds of storms will be possible with some severe weather potential. As we head into Saturday evening, guidance depicts a robust thermal ridge beginning to advect into our region with a more stout cap inversion in place where the 700mb 12C isotherm can reach. As this occurs, guidance depicts a marginally increasing low-level jet with accompanying 850mb moisture transport pushing into northwestern WI/eastern MN, which almost all of the CAMs agree will be an instigating mechanism to develop an MCS later Saturday along with a subtle piece of shortwave energy. The main conundrums with this setup are the difference is the uncertainty in timing for when this MCS gets going and exactly how far northeast the thermal ridge axis is able to build into our local area which would be important for how strong the cap ends up. Another consideration as well is a secondary nose of 850mb moisture transport that develops through southern/central WI during the evening that may try to instigate some discrete convection ahead of the aforementioned MCS as shown in the past couple HRRR runs. While shear profiles are fairly lackluster, fairly robust MUCAPE (3000-4000 J/kg) in the 12.09z RAP would indicate more pulse convection with maybe some hail in stronger updrafts. Overall, would say confidence for seeing this MCS is higher along and north of the I-94 corridor with confidence decreasing south and west where probabilities in the grand ensemble (GEFS/EC ensemble/Canadian ensemble) begin to increase for 700mb temps of 12C or greater (60-80% over NE IA). However, changes in how the thermal ridge manifests will have implications for both timing and location of this convective complex. Generally though, would expect damaging wind gusts would be the primary concern with the 12.12z HRRR Neural Network Probabilities showing higher probabilities (40-60% chance within 40 km of a point) for 50 kt wind gusts around the I-94 corridor and lower probabilities further south and west. Rainfall amounts in the 12.12z HREF probabilities for 1" or greater are fairly modest (40-60% chance) across north-central Wisconsin, with the ensemble max having localized amounts of around 2-3". However, with the fairly progressive nature of this event would expect flooding concerns to be fairly isolated. Sunday generally has trended more on the marginal side for any severe weather with the aforementioned thermal ridge firmly in place with a strong cap noted across much of the region. With the general absence of any pieces of shortwave energy, the main forcing mechanism for any convection during the day on Sunday would be residual outflow boundaries from prior convection overnight Saturday. But again with still remaining questions for how Saturday night convection will manifest, confidence still remains low for convective trends on Sunday. Overall would anticipate with the stronger cap that a drier trend would be more likely to resolve but will hold onto some precipitation chances for now. We keep this unsettled pattern continuing into Monday and Monday night as deterministic guidance (12.12z NAM/GFS/EC) hints at some shortwaves in the flow along the southern periphery of a broad upper- level synoptic trough diving south from Canada. Thermodynamics with any convective system that may occur is challenging as the previously mentioned cap begins to wane throughout the day with increasing destabilization. Consequently, if the forcing regime is more favored during the morning hours would keep convection elevated with a tendency to be more surface-based during the afternoon/evening where the 12.12z NAM/GFS tries to erode the cap which would favor the potential for damaging wind gusts with the lack of a stable layer. Overall, shear profiles in deterministic guidance with the 12.12z NAM having 50-60 kts of 0-6km shear by 21z Monday. Therefore, would think better organization with storms would be possible later into the day. Certainly a very tricky forecast across the board and will have to monitor how the convective allowing models trend over the next couple of days. Heat this Weekend: With the aforementioned thermal ridge building into our area this weekend, zonal to northwesterly flow coupled with south/southwesterly surface flow will allow temperatures to trend above normal for the weekend and Monday. Sunday currently appears to be the warmest of the three days with the 12.13z NBM having a 25th to 75th percentile spread for highs at La Crosse of 92 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. Certainly will be one of the hotter days we have had so far this summer. 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 lower to upper 90s. Drier, Cooler by Tuesday Through The End of the Week: As the aforementioned broader upper-level trough begins to pivot eastward towards the middle of the week, northerly flow will help aid in cooler air to be advected into our region. Guidance generally agrees that temperatures will trend above normal with the 12.12z grand ensemble (GEFS/EC ensemble/Canadian ensemble) having an inter- quartile range of 73 to 77 degrees for highs on Wednesday at La Crosse with similar degree of confidence throughout the rest of the week. Additionally, with subsidence under a broad surface high pressure that the 12.12z GFS/EC pushes into our region during the second half of the week, would expect minimal precipitation chances from Wednesday through Friday. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1028 PM CDT Fri Jul 12 2024 VFR expected through most, if not all of the TAF period. Initial calm conditions at 13.06Z TAF issuance with SCT-FEW mid level deck spread from southwest to northeast early this morning. Subsequent impacts will be the potential for a line of storms this afternoon and evening. Highest confidence, albeit limited, has a line sagging south through the Upper Mississippi River Valley into the evening hours. Highest confidence remains farther north, north of the Interstate 94 corridor. Therefore, most likely locally impacted small airport would be KMDZ. Farther south towards KBCK is where confidence wanes. Given the low confidence, have not included in either TAF (KLSE/KRST) at this time. Primary hazard would be damaging winds with a secondary hazard of large hail possible. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Naylor AVIATION...JAR
Area Forecast Discussion
National Weather Service Binghamton NY
759 PM EDT Fri Jul 12 2024 .SYNOPSIS... Rain showers and a few isolated thunderstorms develop this evening and overnight mainly across NE PA and into the Southern Tier. Hot and humid conditions are expected through this weekend with heat indices approaching 100 degrees in the afternoon. && .NEAR TERM /THROUGH SATURDAY NIGHT/... 745 PM Update... Latest radar, satellite and model data is trending a touch east with the rain and clouds with the coastal trough overnight into Saturday. Adjusted sky cover, PoPs and QPF to show this trend. Currently clouds are in place over the Catskills, Poconos and portions of the Mohawk Valley/eastern Central NY. A few rain showers are on radar east-southeast of Scranton across the Poconos of NE PA. The HRRR and 3km NAM keep this general theme going all night, with the highest PoPs now in the forecast right along our CWA border for locations such as Hazleton--Daleville and Milford PA. Further back to the north and west expect partly cloudy skies overnight, with patchy for development and perhaps a slow moving pop up shower. By daybreak Saturday and through much of the day, the main area of rain now looks to be east of our forecast area with just a slight chance for a pop up shower or thunderstorm. Morning clouds east of Binghamton gradually giveway to mainly sunny skies. Overall, for much of the area it is shaping up to be a nice Saturday weather-wise for mid-July. It will be very warm with highs in the 80s to near 90 and rather humid conditions. 530 PM update... With some tropical moisture streaming northward and a 500 mb shortwave moving through tonight there will be some scattered rain showers and isolated thunderstorms developing after sunset. The best chances are in NEPA into the Southern Tier of NY as that is where the deepest moisture is. Despite a through moving through tonight, tomorrow is looking warmer as there will be less clouds around and warmer air begins to advect in aloft. Chances of showers and and thunderstorms will return in the afternoon with the heat and humidity leading to some instability. && .SHORT TERM /SUNDAY THROUGH MONDAY/... 520 PM update... Weak zonal flow on Sunday with warm air aloft will lead to warmer high temperatures and dew points near 70 so heat indices will rise into the 90s to near 100 in some of the deeper river valleys of NEPA. With the zonal flow, upstream MCS`s in the northern plains could lead to quick moving embedded shortwaves that could trigger thunderstorms if an MCS can form tomorrow. Right now chances of precipitation were kept low given the uncertainty in the evolution of the convection tomorrow. Monday is looking hot as well with similar highs as Sunday but dew points will be 3 to 5 degrees higher making it more muggy. Once again with the heat and humidity, instability develops across the region and upstream convection could supply a trigger to get convection going in the afternoon. Shear is fairly weak, only around 20 knots but given the high instability, there is a threat for a few microburst if thunderstorms are able to develop. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... 520 PM update... The heat continues into Tuesday with potentially the warmest temperatures and highest dew points. Much of the region reaches the mid 90s to mid 100s for the heat index. There is potential for it to be a little cooler if an approaching shortwave can speed up and provide more clouds as well as develop showers and thunderstorms earlier in the day. As the shortwave moves through Tuesday night into Wednesday, there will be good chances for widespread showers and thunderstorms. Shear does increase to 30 to 35 knots in ensemble means so timing of the passage will have to be watched. Once the shortwave passes east mid week, cooler and drier air advects in helping make for a better end to the week with seasonable temperatures, lower dew points, and mostly sunny skies. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... VFR conditions at most terminals expected through 6Z tonight though AVP will likely have some showers around through most of the night. Fog begins to develop after 6Z with AVP and ELM with the best chance at seeing fog if the skies remain clear at ELM and if there ends up being more rain at AVP. BGM may see some rain showers late that could cause some MVFR restrictions. Tomorrow is looking VFR at all terminals once the fog clears in the morning. Outlook... Saturday night...Patchy valley fog may bring occasional restrictions, especially at KELM. Otherwise mainly VFR. Sunday...Mainly VFR. Monday through Wednesday...Scattered showers and thunderstorms may bring occasional restrictions; otherwise mainly VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...AJG/MWG NEAR TERM...AJG/MJM/MWG SHORT TERM...AJG/MWG LONG TERM...AJG/MWG AVIATION...AJG
Area Forecast Discussion
National Weather Service Bismarck ND
1015 PM CDT Fri Jul 12 2024 .KEY MESSAGES... - Isolated to scattered severe storms are possible across all of western and central North Dakota tonight. Hail to the size of golf balls and winds up to 70 mph will be the main hazards. - Very warm temperatures through the weekend, with a Heat Advisory in Dickey and LaMoure counties 1 PM to 8 PM Saturday. - Isolated to scattered severe storms are possible late Saturday afternoon and into the night. Hail to the size of golf balls and damaging winds up to 70 mph will be the main hazards. A tornado or two is possible northwest. - Isolated to scattered severe storms will be possible once again on Sunday. && .UPDATE... Issued at 1015 PM CDT Fri Jul 12 2024 Removed Hettinger, Stark, Dunn and Ward counties from the Severe Thunderstorm Watch. Currently have two severe thunderstorm warnings out and overall the severe threat has diminished somewhat, but still existent. Currently watching a stronger warned supercell in Oliver county moving southeast toward eastern Morton and western Burleigh counties. Will also need to continue to monitor convection in northeastern Montana that is approaching northwest ND. UPDATE Issued at 820 PM CDT Fri Jul 12 2024 Quick update to adjust pops to better match radar trends, blended with most recent model guidance. UPDATE Issued at 736 PM CDT Fri Jul 12 2024 Severe thunderstorm watch #521 has been issued for most of central and part of southwest ND, in effect until midnight CDT. Also adjusted key messages to reflect larger hail and wind potential with these storms tonight. UPDATE Issued at 723 PM CDT Fri Jul 12 2024 Severe thunderstorm watch for much of central ND will be issued shortly, after coordination with SPC. There has been a slight uptick in convection over the past hour or two with 3 storms currently having severe thunderstorm warnings in place. Water vapor imagery shows flattened broad scale ridge in place with an embedded shortwave trough nearing the MT/ND border, and likely supporting convective trends. SPC mesoanalysis continues to show MLCAPE of 3000-4500 J/KG with the most recent convection firing along the CAPE gradient coincident with a weak frontal boundary. The HRRR continues to carry the convection eastward through the state tonight, but continues to be uncertainty in how it will actually evolve. Bulk shear (0-6km) continues to range 30-40kts, mainly across the west. && .DISCUSSION... Issued at 345 PM CDT Fri Jul 12 2024 Currently mostly clear skies are found across the state, with some diurnal cumulus in the James River Valley. Scattered thunderstorms have developed in far northwest North Dakota along a weak surface front. Ahead of this front is a surface trough orientated north/south across the west central part of the state. Aloft the ridge is still flattening with a small shortwave in eastern Montana. This wave will move east through the evening, combining forces with the cold front, kicking off convection. At the surface with this wave is much drier dew points. Currently dew points in North Dakota are in the 60s and 70s. With these higher dew points CAPE values are very high, however the is a strong cap in place, via our morning soundings. This would be why there is no diurnal cumulus elsewhere. Models have a pseudo-dry line moving in from Montana behind the cold front this evening that storms will form on. As of 3pm CT there`s a storm trying to go up in southern Dunn county. This will be a good indicator on the status of the cap. This storm so far has only produced a quick weak tornado, no hail. Most CAMs are very different a few isolated cells turning into an organized line moving through the state, then the rest of them keep the isolated cells. So if the line happens wind will be more of a concern, especially with dew points dropping. That will make an inverted V sounding, which is ideal for severe wind. Otherwise if isolated cells, it will mostly be hail around 1 inch. Shear is not very high, it looks to be around 20kts. CAPE is much high in the moist air but then drops off rapidly west of the river where the storms will be forming. Confidence in the storm mode is relatively low for a few hours before the event unfortunately. The forecast may have lower PoP values than expected because of this uncertainly in storm mode and timing. The general timing for the main show is 23z (starting in the west) to around 08z (ending in the east). Wildfire smoke will continue to affect the upper atmosphere, really just affecting the color of the clear sky you see. Saturday is more of the same with possible severe storms. SPC has a slight risk (level 2/5) across most of the area. Most CAMs have a line moving in from Montana around 02z. CAPE looks to be around 1500 J/kg with shear values around 40kts. 0-3km shear is around 30kts, so wind will be a bigger concern if the storm mode is a line, otherwise hail would be bigger in size around golf balls. Sunday another chance of severe storms are possible. SPC has a marginal from Williston to Bismarck over to the Red River Valley. There is also a slight risk in the north central down through Harvey and east. Currently for Sunday CAPE and shear is very high in the slight risk area. We`ll see how that evolves. Saturday will be the warmest day with the highest humidity. The James River Valley will be the warmest spot. We have issued a Heat Advisory for just Dickey and LaMoure counties from 1pm to 8pm Saturday for heat index values as high as 103 degrees. The ridge through the weekend will continue to flatten and turn zonal with slight waves of energy moving through. High temperatures through the weekend will slowly cool to the 80s by Monday as a front and wave dip down from Canada. Temperatures look to stay in the 80s with a big upper low spinning farther up in Canada before dipping into the Great Lakes Wedneday. This will put us in northerly flow, aiding to the slightly cooler temps. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 647 PM CDT Fri Jul 12 2024 The main issue involves scattered thunderstorms, some severe slowly moving through western and north central ND. Already updated KMOT for a thunderstorm moving through the area, and another thunderstorm approaching KDIK. Otherwise, due to overall coverage kept VCTS in the other locations. && .BIS WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 1 PM to 8 PM CDT Saturday for NDZ048-051. && $$ UPDATE...JNS DISCUSSION...Smith AVIATION...JNS
Area Forecast Discussion
National Weather Service Charleston SC
1007 PM EDT Fri Jul 12 2024 .SYNOPSIS... A weak front will meander across the area through Saturday. Atlantic high pressure will then rebuild across the area while a surface trough exists inland Sunday through the middle of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Per recent SPC mesoanalysis, still a bit of instability out there (in excess of 2K J/Kg MLCAPE) and limited CINH with spotty convection continuing to bubble up along any random boundary. SPC RAP forecasts do show increasing CINH as we get into the overnight hours suggesting inland convection will eventually fizzle out. But PoPs were held through the evening and into the early overnight hours accordingly. Meanwhile, some additional showers/storms could continue or develop off the Charleston coast throughout the night, some of which could skirt the Charleston County coastal areas. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... Saturday: Aloft, a mid-lvl ridge will gradually strengthen across the Southeast United States. At the sfc, weak low pressure across southern areas should gradually nudge west during the day while a weak front/stalled boundary lingers nearby. The pattern will favor a slightly weaker onshore wind compared to the previous day, but will continue to advect moisture characterized by PWATs in excess of 2.0 inches across a large portion of the area. An afternoon sea breeze interacting with a the nearby front/boundary should become the main focusing point for afternoon convection, with greatest precip coverage across the Tri-County Area away from the beaches mid-late afternoon. Coverage and intensity of rainfall should be less than the previous day with subtle forcing in place, and precip totals should generally average around 1/2 inch or less. However, a few locations could see slightly higher precip amounts during a thunderstorm. Expect precip coverage to quickly diminish during evening hours with the loss of diurnal heating. Outside/before precip, warm and humid conditions are anticipated across the area, with a few locations potentially experiencing heat index values between 105-109 for an hour or two along and east of the I-95 corridor, mainly across Southeast South Carolina early to mid afternoon. Some uncertainty in the duration of highest heat index values comes into question given precip developing across the same area by peak diurnal heating hours. However, sfc temps should still peak in the mid-upper 90s away from the coast alone, warmest across Southeast Georgia. Overnight lows will remain mild, generally in the mid 70s inland to upper 70s/lower 80s near the coast. Sunday and Monday: Aloft, mid-lvl ridging will persist, but show a slightly weaker signal while a series of subtle h5 shortwave pass along the base of a low amplitude trough across the Mid-Atlantic states. At the sfc, what is left of weak sfc low pressure and a nearby front dissipates with the pattern becoming more summerlike in nature with lee troughing across the Midlands and high pressure extending across the western Atlantic. These features should provide sufficient forcing and/or a focusing mechanism for afternoon convection in a moist environment (PWATs around 2 inches) just inland to the area, before a westerly flow between the mid-upper trough to the north and a ridge to the southwest nudges activity across the local area. Some enhancement along a sea breeze shifting inland is possible each day, at least in regards to carrying chances of showers and thunderstorms across the entire area. A stronger thunderstorm can not be ruled out, but overall organized severe weather potential remains low. Outside of precip, conditions will become quite warm, with afternoon highs in the mid-upper 90s away from the coast. A few locations could even touch 100 degrees far inland each afternoon. The combination of a weak downsloping wind aloft and low-lvl mixing during the afternoon should lower sfc dewpts across areas experiencing the warmest temps well inland, but many areas could experience heat index values that support Heat Advisories each afternoon, mainly along and east of the I-95 corridor. Overnight lows will remain mild, generally in the mid 70s inland to upper 70s/lower 80s near the coast. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Ridging will gradually build across the Southeast United States, while weak shortwave energy ripples across the Mid-Atlantic states along the southern periphery of a mid-level trough. At least scattered showers and thunderstorms will be possible each afternoon, typical of a summerlike pattern. Outside of precipitation, hot and humid conditions are forecast into mid week. Heat Advisories could be required Tuesday through Thursday, until a front approaches the area late week with greater shower/thunderstorm coverage locally. Heat Index values could even approach Excessive Heat Warning criteria (113F) across portions of the forecast area on Tuesday and Wednesday. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Showers and thunderstorms have diminished greatly across the region, although showers may continue to percolate through the evening hours. Also, there could be some additional showers and thunderstorms that persist or develop off the Charleston coast that make a run toward the coast overnight through early Saturday. However, chances are too low to include in the terminal forecasts at this juncture. Saturday will see another round of showers and thunderstorms develop in the afternoon and the latest forecast will feature VCSH from 18Z onward. Extended Aviation Outlook: Scattered afternoon showers/thunderstorms could produce tempo flight restrictions at CHS/JZI/SAV terminals each afternoon through early next week. && .MARINE... Tonight: South to southeast winds are favored through tonight as weak low pressure and an associated surface boundary shifts further inland. Speeds will be in the 10-15 kt range. Seas will average 2-4 feet, with some 5 footers across the outer portions of the Charleston County nearshore waters. Saturday through Tuesday: A pinched gradient could develop over the marine waters through early next week as high pressure persists across the western Atlantic and a trough lingers inland. However, conditions are expected to remain below Small Craft Advisory criteria. In general, southerly winds will be in place with temporary increases to around 15 kt, mainly near the coast where sea breeze circulations develop, then shift inland. Seas will range between 2-4 ft. Rip Currents: Moderate SSE swell directed mainly north of Cape Fear will work into Charleston County coast today. The modest increase in swell will bump the rip current risk to Moderate for the Charleston County beaches. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...Adam/ETM SHORT TERM...DPB LONG TERM...DPB AVIATION...Adam/DPB/ETM MARINE...DPB/ETM
Area Forecast Discussion
National Weather Service Cheyenne WY
942 PM MDT Fri Jul 12 2024 .KEY MESSAGES... - Very hot temperatures are likely across all of southeast Wyoming and the western Nebraska Panhandle this weekend through early next week. A Heat Advisory has been issued for portions of southeast Wyoming Friday afternoon, and for all areas east of the Laramie Range for this weekend. - Widespread precipitation possible Monday and Tuesday with a brief cooldown Monday through Wednesday. Warmer, drier conditions return Thursday onward. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 216 PM MDT Fri Jul 12 2024 Most likely looking at a quiet, but hot afternoon and evening across the CWA. Hi-Res guidance has trended precipitation chances down from earlier runs. Lack of any real cumulus field across the plains and high terrain is also indicative of decreased precipitation chances. There is a bit of a cumulus field over and south of the Black Hills, which could lead to a Dawes County clipper later this afternoon and again later tonight per the HRRR. As usual with such hot and dry conditions, the main concern with any storms will be strong gusty winds. Cannot rule out wind gusts over 60 MPH with storms. Models continue to remain in excellent agreement regarding hot temperatures over the weekend. The next few days will be some of the hottest of the season thus far, with many locations in the running to break a few records. Over the next day or so, the upper-level high over the Great Basin will gradually shift eastward, settling over Colorado by Sunday. Compared to previous runs, both the GFS and ECMWF have trended 700 mb temperatures down slightly. Ranging from roughly +16C to +20C, temperatures will of course still be very hot, with afternoon highs in the 90s to low 100s. Saturday potentially could be the hottest day of the weekend, as models show the warmest 700 mb air in place during this time. Less afternoon cloud cover will also likely lead to warmer temperatures Saturday afternoon. Heat Advisories remain in place for much of southeast Wyoming and the Nebraska panhandle through the weekend. Aside from the heat, precipitation chances could be possible Saturday and Sunday. Decreased PoPs Saturday afternoon as the HRRR was not showing much in the way of convection across the CWA. Model soundings from the GFS also paint a very dry picture during the day Saturday. Very profound inverted-v profiles and lack of any decent mid-level moisture could lead to the development of high based clouds, but not much else. Precipitation chances look a bit better later Sunday afternoon. Increased mid-level moisture will lead to more cloud cover on Sunday, with models showing increased chances for scattered convection. && .LONG TERM /MONDAY THROUGH FRIDAY/... Issued at 216 PM MDT Fri Jul 12 2024 The upper-level ridge that has been impacting the region and bringing in near-record high temperatures will begin to breakdown starting Monday. An upper-level trough is progged to propagate eastward along the United States/Canada border, forcing the ridge to weaken an be pushed back to the west throughout the day. A 594dam high will remain centered across the Four Corners region, ushering in Monsoonal moisture around the high and into southeast Wyoming and western Nebraska. As the ridge weakens and the high is pushed over the Four Corners region, zonal flow will develop overhead with a 500mb shortwave pushing through. Atmospheric moisture will increase significantly as upper-level southwesterlies and surface southeasterlies bring in Monsoonal and Gulf moisture. PW values will surge to over an inch for western Nebraska and most of southeast Wyoming. A weak cold front associated with the upper-level trough will slide across the region and interact with well above average PW values and southeasterly flow, leading to the development of showers and thunderstorms. With PW values well over an inch and weak steering flow, heavy rainfall is possible on Monday with the passage of the cold front. Some strong storms may be possible as modest instability will exist across the region. This setup will need to continued to monitored to assess the threat of severe weather for Monday. Increased cloud cover is expected as well due to the additional moisture across the region. High temperatures will be in the mid-80s to mid-90s area wide. Slightly cooler temperatures are forecast for Tuesday behind the passing cold front on Monday. Highs are progged to be in the low-80s to low-90s area wide. The upper-level ridge will attempt to redevelop and restrengthen west of the CWA, but the 500mb high remains in place across the Four Corners region and slightly wobbles back to the west. The continued presence of the high over this region will favor Monsoonal moisture being advected into the region for another day. Similar to Monday, surface southeasterlies will advect in additional Gulf moisture leading the PW values once again above an inch for the Nebraska Panhandle and far southeast Wyoming. A 700mb trough off to the northeast will lead to northwesterly flow at this level and slightly cooler temperatures as cooler air moves into the region. With a few passing 500mb vorticity maxima, showers and thunderstorms are favored for Tuesday once again. Steering flow will be weak again, leading to the potential for heavy rainfall across the region for Tuesday. Severe weather may be more favored for Tuesday as more MLCAPE will be available across the Nebraska Panhandle. However, forcing across the region will be slightly weaker as a very week cool front pushes through. For the remaining long term forecast, the upper-level ridge will continue to try to build across the western CONUS with primarily northwesterly flow over the region Wednesday through the weekend. The ridge is progged to strengthen and move easterly throughout the latter half of the week. Therefore, a warm up is expected beginning Thursday and continuing through the weekend. Next weekend does not look as hot as what is currently ongoing across southeast Wyoming and western Nebraska, but temperatures will be back into the 80s and 90s everywhere. With the ridge moving back overhead, precipitation chances will begin to decrease for the latter half of the week. Some daily chances for a shower or thunderstorm off the higher terrain exist, but coverage will be much less than what is expected Monday and Tuesday. Wednesday will be the coolest day of the week with highs in the upper-70s to mid-80s area wide. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 938 PM MDT Fri Jul 12 2024 West northwest flow aloft will continue. Mostly clear skies will prevail, with periods of scattered to broken clouds from 10000 to 12000 feet. Expect occasional thunderstorms at Chadron until 08Z, producing wind gusts to 40 knots and ceilings near 8000 feet. Winds will gust to 23 knots at the Wyoming terminals from 15Z to 00Z. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Heat Advisory from 10 AM Saturday to 8 AM MDT Monday for WYZ101-102-107-108-118-119. NE...Heat Advisory from 8 AM Saturday to 8 PM MDT Monday for NEZ002- 003-019>021-054-055-095-096. && $$ SHORT TERM...SF LONG TERM...AM AVIATION...RUBIN
Area Forecast Discussion
National Weather Service Sioux Falls SD
1035 PM CDT Fri Jul 12 2024 .KEY MESSAGES... - Wildfire smoke continues to stream overhead through the weekend into early next week. Surface impacts are currently not expected. - Showers and thunderstorm chances are low tonight through the weekend. However, if a storm is able to develop, strong to severe storms may occur. - Temperatures and dew points increase for the weekend. Heat Advisory in effect for Saturday. Moderate (40%-60%) chance of exceeding criteria Sunday. - Unsettled pattern continues early next week, with periodic shower and storm chances. Temperatures near climatological averages. && .DISCUSSION... Issued at 239 PM CDT Fri Jul 12 2024 CURRENTS THROUGH TONIGHT: Additional diurnal cumulus clouds have developed today, with hazy skies due to continued wildfire smoke. We`ve climbed into the 80s and with dew points in the 60s to lower 70s, heat indices are in the lower 90s for some folks. Showers have been trying to develop but are struggling due to the cap and lack of moisture. Winds increased through the early afternoon with now southerly winds gusting to around 30 mph. Gusts taper off after sunset, with southerly winds around 5-10 mph overnight. Although a couple of hi-res models hint at valley fog developing, think winds remain just strong enough overnight to preclude development. Lows tonight "drop" into the upper 60s and lower 70s. Capping in place should keep us dry overnight, but can`t entirely rule out a very isolated storm. THIS WEEKEND: With the ridge in place over the southern US, our flow pattern generally remains west-northwesterly through the weekend. Not only does this allow the heat and humidity to build (more on that in a minute), we`ll see hazy skies continue as wildfire smoke streams eastward. The HRRR guidance brings in some periodic higher concentrations through the weekend, but with the strong inversion limiting mixing and low level southerly flow, impacts at the surface are not expected. Guidance has underdone dew points for today so with that in mind, have continued to try to trend those values up. Combined with above average temperatures (highs in the 90s), have issued a Heat Advisory for the entire area for Saturday afternoon and evening with heat index values near/above 100 degrees F. Models did come in cooler for Sunday, but think this is due to the models struggling with convection. Bumped up the NBM a couple of degrees closer to the previous forecast using some of the NBM 75th; however, held off on a headline for now to determine if the "cooler" temps are a trend in the models or a fluke this run. Headline or now, hot and humid again Sunday, with highs near/in the 90s. Lows through the weekend in the upper 60s to lower 70s. We`ll also be keeping an eye on convective chances through the weekend with a few waves moving through (continued disagreement in the models in timing/location). 925/850 mb temperatures both in the 20-30 degree C range leads to a stout capping inversion. Once again this afternoon, CAMs continue to struggle with evolution and development of convection through the weekend. Again, think that capping will prevent most development in our area, and also cause storms which advect into our area to struggle. However, robust instability thanks to the heat and humidity, increasing shear, and steep mid level lapse rates would all favor strong to severe storms *if* a storm can develop. Ping pong ball sized hail, wind gusts to 70 mph, and locally heavy rain are the main hazards although again, convective chances are very low. Given the heat, humidity, and isolated storm risk, folks with outdoor or travel plans should keep an eye on the forecast for the latest information. Plan now for heat impacts and have a plan in case storms develop. MONDAY ONWARD: High pressure continues to spin over the southwestern US through at least the middle of next week. Upper troughs and stronger waves toward mid week bring a return to more northwesterly flow aloft than the westerly flow we will see over the weekend. This will likely keep periodic rain and storm chances around, but should allow temperatures to moderate back to near climatological normals. After Monday, highs return to the lower/mid 80s (possible as cool as the mid 70s for some) and lows fall into the 50s and 60s. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1034 PM CDT Fri Jul 12 2024 Showers and thunderstorms remain across portions of North Dakota and western South Dakota this evening. Think any storm that progresses east/southeast will encounter more stable air and thus diminish. It is possible that some weaker showers could last into KHON but confidence is too low to include in KHON`s TAF as of now. Also think tomorrow will continue to be dry given continued capping but will monitor trends. Light southeasterly winds are expected to persist through the night before turning southerly by tomorrow afternoon. The southerly winds will finish out the TAF period. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Heat Advisory from 1 PM to 8 PM CDT Saturday for SDZ038>040- 050-052>071. MN...Heat Advisory from 1 PM to 8 PM CDT Saturday for MNZ071-072- 080-081-089-090-097-098. IA...Heat Advisory from 1 PM to 8 PM CDT Saturday for IAZ001>003- 012>014-020>022-031-032. NE...Heat Advisory from 1 PM to 8 PM CDT Saturday for NEZ013-014. && $$ DISCUSSION...SG AVIATION...Meyers
Area Forecast Discussion...CORRECTED
National Weather Service Hastings NE
903 PM CDT Fri Jul 12 2024 ...Key Messages and Short Term Update... .KEY MESSAGES... - Spotty thunderstorm chances (15-20%) late tonight into early Sat AM, but severe threat looks low (SPC has recently removed a formal Marginal Risk from our coverage area) - Dangerous heat expected this weekend, with a Heat Advisory in effect from 1pm Saturday through 8pm Sunday. - Widespread heat index values of 100-110 degrees on Saturday and Sunday. Heat index values over 100 possible across portions of the area on Monday. - Cooler temperatures and precipitation chances (15-55%) return by the middle of next week. && .UPDATE... Issued at 830 PM CDT Fri Jul 12 2024 -- Some fresh thoughts regarding thunderstorm/fog potential overnight (and summary of forecast updates made since main "afternoon package" was issued earlier this afternoon): - Thunderstorm potential: Not surprisingly, SPC has recently removed their Marginal Risk of severe storms from our entire coverage area (CWA) for the rest of tonight on their latest update. Here at the local level, we fully support this, as although there are a few stronger storms ongoing well to our northwest in NW Neb at this time (with more probably developing into that area yet this evening), the vast majority of this activity is expected to focus at least slightly off to our west as it rides south- southeastward into early Sat AM. In addition, with warmer air aloft directly overhead versus last night (700 millibar temps 12-14C), capping overnight will be quite strong to any lower- level parcels. That being said, latest RAP suggests that especially western parts of our CWA could realize modest available elevated instability of 500+ J/kg late tonight into Sat AM (rooted mainly up around 700 millibars/10K ft. AGL), which could MAYBE support a few sneaky stronger storms especially well after midnight to around 8-9 AM Saturday (main hazards gusty winds to around 50 MPH and possible weak heat bursts...lesser threat of smaller hail). As a result of above reasoning: Have "reworked" our overnight forecast a bit to remove all pre- midnight thunderstorm chances, while expanding post-midnight slight chances (20%) to include the majority of our CWA (except a few far northeast/east-central counties which appear least favored). For now, have not extended any formal thunderstorm chance beyond 7 AM, and will defer to overnight shift to decide if it`s warranted. - Fog potential: Much as was the case yesterday evening (for Friday AM), we are not expecting any kind of widespread and/or dense fog situation overnight into Sat AM, and most models/guidance indicate only weak signals for even light fog. That being said, the very high dewpoints/humidity levels are hard to ignore, with even late- night dewpoints expected to drop no lower than mid-upper 60s especially in north-northeast portions of our CWA. While winds will not be truly calm (should be 5+ MPH most places, and there could be some passing mid-high level clouds (both mitigating factors to a more widespread/dense fog situation), the aforementioned copious low level moisture, along with signals of a weak warm front setting up late tonight near I-80, suggest that counties especially along/north of I-80 are most favored to see at least patchy light fog development (if not more "areas" in nature especially in favored low-lying and valley areas, near rivers etc.). As a result of above reasoning: Have at least introduced basic "patchy fog" potential to several counties mainly along/north of I-80 mainly for the 3-9 AM time frame. This also aligns well with latest 21Z SREF visibility progs, which also highlights our northern counties for the overall-highest (20-40%) chances for visibility dropping to 1 mile or less a few hours either side of sunrise. && .DISCUSSION... Issued at 308 PM CDT Fri Jul 12 2024 This Afternoon and Overnight... Highs this afternoon have climbed into the upper 80s to upper 90s with heat index values in the mid to upper 90s. Portions of north central Kansas will have heat index values top out around 100 degrees. Thunderstorms are expected to develop over western Nebraska this afternoon and move east into the area during the evening-overnight hours. Overall thunderstorm coverage is expected to be fairly isolated, with most HREF members showing only isolated coverage. Thunderstorms will weaken as they move east with a loss of daytime heating and increasing capping. Instability and shear will be sufficient for a few strong to severe thunderstorms, capable of producing damaging wind gusts and large hail. Scattered showers and thunderstorms chances shift east overnight, ending by sunrise on Saturday. Saturday through Monday... The biggest concern for the forecast period is the potentially dangerous heat this weekend. A Heat Advisory has been issued for the entire forecast area from 1pm Saturday through 8pm Sunday. Temperatures will increase across the area on Saturday, with highs in the mid 90s (north) to mid 100s (south). Heat index values of 100- 105 degrees are expected across most of the area on Saturday. Lows Saturday night are expected to remain in the 70s for most areas, providing limited relief from heat overnight. The hottest day of the forecast period will be on Sunday, as highs soar into the upper 90s (north) to mid 100s (south-southwest). Heat index values of 105 to 110 degrees are expected across the area. An approaching trough will bring a cold front into the area on Monday. The exact timing of this front is still uncertain, however areas behind the cold front will see cooler temperatures with highs in the low 90s. Areas that remain south of the front through the late afternoon hours will see another day with highs in the upper 90s to mid 100s and heat index values over 100 degrees. Areas north of I-80 are the most likely areas to see the cold front pass through by the mid afternoon hours. Areas along and south of the NE/KS border are the most likely to not see the cold frontal passage until the evening hours. Heat headlines will likely be needed for portions of the area on Monday, though it will depend on the timing of the front. Mostly dry weather is expected this weekend, though an isolated thunderstorm may impact northern portions of the area Sunday night. Overall, potentially dangerous heat is expected across the area this weekend and into Monday. Heat index values over 100 degrees are expected across the area on Saturday and Sunday, and a portion of the area on Monday. Those with outdoor activities this weekend will want to take precautions to avoid heat related illnesses. Monday night onwards... Thunderstorm chances (15-30%) return to the area Monday evening- overnight. Cooler temperatures are expected on Tuesday, with highs in the 80s across north central Nebraska and in the low 90s across north central Kansas. A welcome break from the heat will arrive by the middle of the week. Highs in the upper 70s to low 80s are expected across the area on Wednesday and Thursday. Scattered precipitation chances (15-55%) continue across the area Tuesday through Thursday, with the highest chances (35-55%) occurring Tuesday night. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 722 PM CDT Fri Jul 12 2024 For KGRI/KEAR Airports: - General overview: Unless some "sneaky" sub-VFR visibility and/or ceiling manages to develop late overnight in light fog, confidence is high in VFR conditions throughout. There is also an outside chance for a passing, high-based shower/weak thunderstorm at some point late overnight into early Sat morning, but this is deemed a low probability (only 10-20%). Winds should not be a significant issue throughout, with sustained speeds mainly at-or-below 10KT and direction mainly somewhere between east-southeasterly and southerly. - Ceiling/visibility/precipitation/thunderstorm details: Starting with light fog potential: While nearly all models/guidance are currently very pessimistic that much of any fog will develop overnight (possibly slightly more favored 25+ miles north of KGRI/KEAR), am a bit concerned that some "sneaky" sub-VFR visibility could indeed materialize given such high humidity levels in the presence of light south- southeast breezes. As a result, will at least "hint" at this potential with a low-end VFR "6SM BR" focused 09-13Z. Outside of any light fog potential, however, confidence is high in VFR with only varying degrees of passing mid-high level clouds. As for rain/thunderstorm potential: A few higher-res models suggest that especially the 09-13Z time frame could also bring the potential for a few very spotty, high-based showers or non-severe storms. However, with this chance deemed no higher than 10-20% have omitted from TAF inclusion. - Winds (including weak LLWS potential): No significant issues foreseen here, as sustained speeds through the period should average near-to-below 10KT, although direction will fluctuate somewhat between east-southeasterly (mainly overnight) and more southerly (mainly Saturday daytime). Regarding weak low level wind shear (LLWS) potential: It appears some fairly weak LLWS could occur tonight mainly 06-10Z as winds within the lowest 1,500 ft. AGL increase to around 30KT out of the south-southwest. However, with shear magnitude between the surface and this level currently expected to top out closer to 25KT than 30+KT, have opted against formal TAF inclusion. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Heat Advisory from 1 PM Saturday to 8 PM CDT Sunday for NEZ039>041-046>049-060>064-072>077-082>087. KS...Heat Advisory from 1 PM Saturday to 8 PM CDT Sunday for KSZ005>007-017>019. && $$ UPDATE...Pfannkuch DISCUSSION...Davis AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Grand Junction CO
529 PM MDT Fri Jul 12 2024 .KEY MESSAGES... - Near-record daytime temperatures are expected today and Saturday especially in the lower valleys. - Afternoon showers and thunderstorms will develop over higher terrain each day throughout the seven-day forecast with an increase in coverage expected early next week. - Temperatures remain elevated beyond the weekend, but some relief is expected from cloud cover and shower activity as monsoonal moisture is forecast to return early next week. && .SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 314 PM MDT Fri Jul 12 2024 High pressure continues to sit to our west, directing a northerly flow across the area. This is allowing the heat dome to persist, with warm air advection to continue through the weekend as the high pressure shifts directly overhead by Saturday. Near record high temperatures are possible across the area with triple digit heat across eastern Utah and west-central Colorado valleys, in fact we are already there this afternoon. The Heat Advisory remains in effect through Saturday and made no changes to the coverage area or timing due to the uncertainty of sub-tropical moisture return on Sunday and what kind of impact increased clouds and storm activity will have on the high temperatures for Sunday. This is something for later shifts to re-evaluate. In this heat, make sure to limit your exposure and stay hydrated. Storms continued to develop again across the southern mountains like yesterday, except a little bit further west across the Abajos and La Sals. The HRRR seemed to have a better handle on the timing and coverage of storms so nudged the PoP fields towards the HRRR as well as hi-res WRF to better reflect these trends in the forecast. Storms were hot to begin with on radar but have since cooled down, but gusty outflow winds of 40 to 50 mph and lightning appear to be the primary concerns. The air mass is very dry as evidenced by our 12Z GJT inverted V sounding and relative humidity in the single digits to teens in the lower valleys. These storms also have a tendency to drift into the adjacent southern valleys but are collapsing as they do, so again, gusty outflow winds will be common. Storms appear to be driven by daytime heating, steep lapse rates upwards of 9C/km, quite a bit of DCAPE and a little bit of shear, so small hail is also possible. Storm activity should die down by sunset with a similar story expected for Saturday with highs a bit hotter than today and similar storm coverage over the high terrain with high pressure directly overhead. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 314 PM MDT Fri Jul 12 2024 By Sunday the high pressure that has been bringing all the heat will be centered roughly over the Four Corners. This means Sunday is likely to be yet another scorcher, especially for the desert valleys where highs in the low 100s are once again forecast. That said, by Sunday we are also expected to tap into a plume of monsoonal moisture rotating around the high, with PWATs forecast to climb to 100-150% of normal. This will lead to increased storm coverage over the higher terrain, and an increase of clouds overall, which may put a slight damper on temperatures, but only by a few degrees compared to the days previous. In addition, the prolonged period of hot and dry weather prior to this monsoonal push means surface levels will be extremely dry and will take some time to moisten. Therefore, the main threats with any storms will be gusty outflow winds and lightning, with the potential for some small hail or a very brief downpour. A trough dropping through the Northern Plains Monday into Tuesday will nudge the high back westward somewhat, cutting us off from the moisture plume once more. The moisture that did advect in on Sunday and Monday will stick around for a bit, being recycled each afternoon and leading to daily showers and thunderstorms favoring the terrain. This increased storm coverage should continue to nudge temperatures down a few degrees through the week. Highs on Sunday and Monday will run around 10 degrees above normal, dropping to around 5 degrees above normal by mid to late week. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 529 PM MDT Fri Jul 12 2024 Radar trends have been decreasing over the 4 Corners area after some stronger storms dropping some decent rainfall and gusty winds. Higher based virga or isolated showers are dropping through northern portions of Utah and Colorado which could push out some stronger winds through sunset. Otherwise VFR and light winds can be expected overnight with another round of showers and storms forming again in the heat of the day on Saturday. Gusty winds remain the main threat to aviation interests. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Heat Advisory until 9 PM MDT Saturday for COZ006. UT...Heat Advisory until 9 PM MDT Saturday for UTZ024-027-029. && $$ SHORT TERM...MDA LONG TERM...BGB AVIATION...TGJT
Area Forecast Discussion
National Weather Service Green Bay WI
1039 PM CDT Fri Jul 12 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - Isolated showers/storms will be possible through this evening. While severe weather is not expected, any storms could produce locally heavy downpours. - A few rounds of strong to severe storms are possible from Saturday through Monday. The mostly likely times are Saturday night, and again Monday afternoon/evening. However, there is still high uncertainty. - Warmer and more humid conditions arrive Saturday through Monday. Heat index values in the 90s are expected over central, east central and parts of far northeast WI Sunday into Monday. && .DISCUSSION... Issued at 401 PM CDT Fri Jul 12 2024 Short Term...Tonight and Saturday Main forecast concerns for the short-term will revolve around severe weather potential and building heat and humidity. Best timing for anything severe looks to be late Saturday evening and into the overnight, although CAMs are currently showing a variety of different scenarios that could play out. Showers/storm potential this afternoon/evening... Mid-level capping and dry air intrusion from high pressure situated over Michigan`s lower peninsula have kept shower activity at bay through the early afternoon. However, decent moisture and instability (~2,000 J/kg CAPE) have sustained a mid-level cu field across the entirety of the CWA. Some pulse showers/storms may be possible into this evening, although dynamics don`t look too impressive 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 given PWATs of 1.25" and weak storm motion. Fog/smoke... Some patchy ground fog will be possible tomorrow morning, especially in areas if/where any rain falls today. Some elevated Canadian wildfire smoke was also observed across the upper Midwest, enough to create hazy conditions. While areas of thicker smoke will remain off to our northeast, even a thin layer of smoke may be enough of a hindrance to prevent us from reaching convective temperatures later this afternoon and evening. Saturday severe weather potential... Most likely solution currently shows a complex of storms coming down from the northwest late Saturday evening into early Sunday morning, mainly before 12Z. Main source of discrepancy between CAM guidance centers around shower/storm activity earlier in the day as weak shortwave energy treks across the Great Lakes. The HRRR solution favors convection developing off to our west along the axis of greatest instability Saturday afternoon before dissipating as it encounters drier air over central Wisconsin. Other short-range models show more isolated/pop-up activity during peak heating. There are some questions as to whether or not this will hinder the east/southeast progression of the MCS later in the evening, with the most recent suite of CAM guidance favoring a slightly later arrival than was shown this morning. Current thinking is that any organized storms would be hard to come by earlier in the day due to the influence of dry air from departing high pressure and low- level capping. Inverted-V soundings indicate locally damaging winds as the primary severe threat for Saturday evening, while mid-level lapse rates and wet bulb zero heights favor hail as a secondary threat. Otherwise, persistent southerly flow looks to make this weekend rather unpleasant as temperatures climb into the low 90s and a surge of low-level moisture brings dewpoints up into the low 70s. The combination of heat and humidity will result in heat indices potentially reaching the mid 90s tomorrow, and flirting with heat advisory criteria on Sunday. A persistent southeast lake breeze will keep temperatures along the lakeshore slightly cooler. Long Term...Saturday Night Through Friday The focus is on the first 48 hours or so of the long-term forecast with the potential for multiple rounds of convection. Heat and humidity will also be a concern during this time. Saturday night...Already starting out with high uncertainty at 00Z/Sun. Some indication thunderstorms or a convective system could be moving across the area at this time, or it could have dissipated already (as discussed above). Regardless, attention will quickly turn to a compact shortwave coming through Saturday night. This is more likely to generate a thunderstorm complex across northern Minnesota Saturday evening, which tracks into Wisconsin overnight (timing window anywhere from 9PM to 6PM across the forecast area). Placement is uncertain, but generally favors a southeast movement across most of the forecast area. Damaging winds would be the main threat, with smaller potential for large hail and localized heavy rain/flooding. Sunday...A morning break from convection, however the heat and humidity build during this time. Dew points rise into the lower 70s for most of central and east-central WI (in the mid-60s across north- central WI). High temps forecast in the mid 80s to low 90s will yield heat index values as high as 95 to 100 across central and east-central WI. However, temps could be impacted slightly by any lingering clouds or smoke aloft, along with any isolated thunderstorms. While most models favor a cap holding off any thunderstorms, and there is limited upper level dynamics, will want to watch for any meso scale interactions which could lead to some isolated thunderstorm potential. A lot of CAPE will be in place, so anything which does develop could become severe. Monday...Once again looking at significant moisture with dew points in the low 70s, and afternoon highs in the low 80s, and increasing instability. There are more dynamics at play, leading to somewhat higher confidence for thunderstorms. A surface cold front, along with mid-level shortwave, and RRQ of upper jet will all serve as larger scale lifting mechanisms. Timing and details are less certain given the prior activity. Tuesday through Friday...Quieter and more seasonable temperatures settle into the region. && .AVIATION...for 06Z TAF Issuance Issued at 1039 PM CDT Fri Jul 12 2024 VFR conditions are expected tonight and Saturday. Satellite imagery indicates some Canadian wildfire smoke is aloft, which may cause some hazy conditions at times. Surface winds are expected to be light through the TAF period. Thunderstorms are possible Saturday afternoon and evening as a thunderstorm complex develops across Minnesota and tracks east through the region. CAMs models are in poor agreement regarding exact timing of this complex; however, there appears to be enough of a chance (30 percent) across central and north-central Wisconsin to include a PROB30 group in this set of TAFs for AUW/CWA/RHI. Further east confidence is too low to include at this time. Any thunderstorms would likely reduce conditions to MVFR or IFR at times. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Goodin/KLJ AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
931 PM EDT Fri Jul 12 2024 .SYNOPSIS... Drier conditions return this weekend, lingering into early next week as high pressure builds across the area. This will allow hot weather to return with afternoon highs climbing into the upper 90s and lower 100s east of the mountains. A pattern change is expected mid-week into next weekend as a cold front stalls across the area and brings above normal rain chances and cooler weather. && .NEAR TERM /THROUGH SATURDAY/... As of 930 PM EDT Friday: Isolated showers developed over the southern NC Foothills and central NC mountains along the Blue Ridge Escarpment within the last hour and a half thanks to ENE`ly flow. These showers are starting to lose steam and are trying to fall apart as they slowly sink southward. With convection remaining mostly stationary, the main concern with any lingering cells continues to be heavy rainfall. Once winds toggle more north the next few hours, convection development should end. Seeing cloud cover bank up along the Blue Ridge Escapement tonight thanks to the ENE`ly flow as well so increased cloud cover across these locations. Lows tonight will end up around 3-5 degrees above climo. Otherwise, a surface boundary stretched across the Coastal Plain of the Carolinas will have a weak surface low ride along the boundary will slowly lifting north through the period. Most of the area will be on the subsident side of the low and thus, limiting shower and thunderstorm potential west of the boundary. The surface wave will lift northeast of the CWA overnight as the mid/upper-level low gets absorbed by the upper troughiness over the northeastern CONUS. Summertime regime will be in store for Saturday as weak high pressure sets up over the CWA, while the Bermuda High re-establishes its position over the western Atlantic and slowly turns surface winds back out of the south-southwest by the end of the forecast period. With 594-596 dm thicknesses in place, and dewpoints ranging from the upper 60s to lower 70s, expect a few locations south and east of I-85 to see heat indices climb into the low 100s. Highs should end up around 3-5 degrees above climo. CAMs are not in good agreement regarding the overall coverage of showers and thunderstorms Saturday afternoon/early evening. Both the HRRR and NAMNest show convection first developing over the mountains by Saturday afternoon before pushing east the rest of the day. However, the NAMNest depicts a broken line of isolated convection while the HRRR depict widely scattered convection. Thus, capped PoPs to slight chance (25% or less) area-wide for now. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 224 PM Friday: Broad upper troughing will be draped from the Northern Plains across the Great Lakes and into New England. Farther west, a stout 600dam upper ridge will be parked over the Four Corners region with broad ridging extending across the Southern Plains and into the Lower Mississippi Valley. Ridging is forecast to build east through the later half of the weekend and into the start of the new week with heights rising across the Southern Appalachians along with an uptick in low-level temperatures. This will support rather hot temperatures with afternoon highs climbing into the low to upper 90s on Sunday and mid 90s to low 100s on Monday. Any good news, though, is that the frontal boundary that has been waffling across the I-77 corridor is forecast to shift back east as flow shifts to out of the west/northwest. This will shunt higher dewpoints and richer moisture into the Coastal Plain with dewpoints able to mix out more efficiently each afternoon. This will in turn help keep heat indices in check with low 100s along and south of I- 85 on Sunday. While dewpoints will remain relatively low on Monday, temperatures in the upper 90s to low 100s will be hot enough that even lower end dewpoints could end up supporting heat indices near advisory criteria (105 degrees) and a heat advisory may ultimately be needed. Subsidence from the upper ridge and a lack of deeper moisture will preclude diurnal convection across much of the area, but an isolated shower and/or thunderstorm cannot be completely ruled out across the mountains. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 232 PM Friday: The blowtorch will continue as we head into mid week, especially on Tuesday, as the 850mb temperatures peak near 24 C. This will support at least one more day of hot weather with afternoon highs once again peaking in the mid 90s to low 100s. A potent upper trough is also progged to swing across the Northern Plains and into the Great Lakes on Tuesday with an attendant surface cold front dropping across the Midwest. Surface high pressure will have also shifted offshore with low-level flow backing to out of the south. This will allow for gradual moisture return into the area off the Gulf of Mexico and eventually the Atlantic Ocean. PoPs slowly return on Tuesday, but most of this activity may remain just south of the area within the initial moisture return across the Deep South into Georgia. A noticeable pattern change is still on tap for Wednesday into next weekend as the upstream frontal boundary approaches and then eventually stalls across the area as the upper trough lifts across the Ohio Valley into New England. Lingering low- level warmth may result in one last day of heat concerns on Wednesday, but this will be conditional with PoPs quickly ramping back up within the leading edge of moisture return. A more robust afternoon cumulus field and an early start to diurnal pulse convection may limit heating and preclude the need for heat products, but this will have to be assessed closer to the day. By Thursday into next weekend, guidance continues to depict the frontal boundary stalling either across or near the forecast area as the front becomes oriented parallel to upper westerlies with the parent trough lifting out of New England. This will result in above average PoPs each day in the likely to categorical range, which will hopefully bring much needed rainfall and cooler temperatures to the area. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... At KCLT and elsewhere: Have some scattered SHRA lingering across western NC as of 01Z but this activity should dissipate in the next hour or so. Removed VCSH at KHKY as -RA has dissipated around the terminal. Did add a TEMPO at KAVL as an isolated shower (which is also leading to low-end wind gusts) developed right over the terminal. Otherwise, VFR should prevail at most locations through the TAF period (outside of convection), with the exception of both KCLT and KHKY. Both of these terminals have the potential to see lowering CIGS and VSBYS overnight thanks to lingering low-level moisture. KCLT is already starting to see an MVFR CIG develop as of 01Z. The NBM has backed off on cloud coverage overnight and shows only FEW to SCT clouds through daybreak Saturday. This lines up well with the HRRR but both the NAM and CONSShort are forecasting BKN to OVC cloud cover. Thus, trended down cloud cover slightly compared to the previous TAF update. Maintained an MVFR CIG at KCLT from 09Z-15Z (BKN012) but also mentioned SCT005. For KHKY just went SCT023 from 09Z-13Z. Went ahead and maintained the MVFR fog mention at both KCLT and KHKY based on the latest model VSBY guidance. Drier conditions can be expected tonight into Saturday morning, but isolated SHRA/TSRA may develop Saturday afternoon and evening. However, the latest high-res model guidance is not in great agreement regarding the overall coverage of diurnal SHRA/TSRA. Thus, went with dry conditions across the terminals for Saturday with confidence too low on whether convection will track directly over a terminal. Winds will gradually decrease in speed through this evening, remaining NE east of the mountains. Winds east of the mountains will then turn more N/NW overnight into Saturday morning. Winds east of the mountains will then gradually turn WSW/SW Saturday afternoon. Wind speeds will be lighter on Saturday compared to today. A VFR cumulus field will develop on Saturday afternoon/early evening. Outlook: Isolated showers and thunderstorms are expected mainly over the mountains Sunday into early next week. A cold front will approach out of the northwest middle of next week before tracking into the western Carolinas late next week. This will increase shower and thunderstorm chances across all of the terminals. Morning fog/low stratus will be possible each morning, especially across the mountain valleys and for areas that received heavy rainfall the day prior. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...AR/TW NEAR TERM...AR/CAC SHORT TERM...TW LONG TERM...TW AVIATION...AR
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
953 PM EDT Fri Jul 12 2024 .KEY MESSAGES... - Hotter conditions make a comeback as we move into the weekend and for next week. - The next significant chance of rain will hold off until the middle of next week. && .UPDATE... Issued at 953 PM EDT FRI JUL 12 2024 We have had some persistent showers and occasional thunderstorms that have been forming along and ahead of an eastward advancing outflow boundary. Given this updated to keep PoPs going for a small portion of the areas mainly along and north of the Mountain Parkway this evening. Some of these showers are producing brief heavy rainfall of three quarters of an inch to one inch an hour rates at times. Other than the PoPs no bigger changes are needed for this update. UPDATE Issued at 713 PM EDT FRI JUL 12 2024 We have had a few more showers that have develop further east than expected. This could perhaps be an additional outflow boundary that was undiagnosed. Either way opted to add in 15 or less PoP in areawide for a few hours this evening. Outside this only minor update to add in the latest obs and trends. UPDATE Issued at 551 PM EDT FRI JUL 12 2024 A weak wave is noted in the mid-levels toward SE Missouri. This has helped sparked off showers and a few thunderstorms across western and central parts of Kentucky this afternoon. An outflow off these storms is noted on satellite and WSR-88D data this afternoon tracking slowly east toward parts of eastern Kentucky. This has been aiding is developing a few showers and thunderstorms at times as it tracks east. Given this opted to keep 15 or less PoP right along our CWA border through the late afternoon hours. These are expected to relent through the evening, but HRRR (which has been verifying the best lately) has this going a little longer into the evening. This trend will be monitored for future updates. Outside this is a fairly minor update. && .SHORT TERM...(This evening through Saturday night) Issued at 312 PM EDT FRI JUL 12 2024 The 15Z surface analysis continues to show high pressure situated over much of the eastern CONUS. A weak surface low remains present over the Central Plains with a surface boundary extending into the Ohio Valley. In eastern Kentucky, high pressure remains dominate with mostly sunny skies. Radar has been a little active over the last hour or so with pop-up showers developing along and southwest of the Mountain Parkway. These showers pulse up quickly then dissipate. Isolated showers will be possible over the next few hours before diminishing after sunset. Aloft, a trough continues to be situated over the Great Lakes. The CWA is presently situated at the base of the trough as it continues to pivot northeastward out of the area. This trough is helping trigger the shower activity across the area today but as the trough exits and daytime heating wanes, those showers will cease to exist. For the overnight, mostly clear skies will exist and allow for radiational cooling in the river valleys. Thus allowing for the development of areas of valley fog through the early morning hours of Saturday. Saturday brings about another hot and humid day as surface high pressure remains overhead. Aloft, west to northwesterly flow will usher in a drier airmass thus limiting the potential for shower activity but cannot rule out a stray shower Saturday afternoon. Overnight Saturday brings around another mostly clear night with areas of valley fog that`ll burn of early Sunday morning. Overall, the period will be mostly dry aside from a few isolated showers or storms with passing clouds. Highs are forecast to be in the mid to upper-80s into the lower-90s today before climbing into low to mid-90s for Saturday. Overnight lows will remain mild across the area too, as lows tonight will drop into the mid to upper-60s for tonight and again Saturday night. .LONG TERM...(Sunday through Friday) Issued at 432 PM EDT FRI JUL 12 2024 There is reasonable agreement among models up until about mid week. We should reside near the southern edge of the westerlies aloft on Sunday. Our surface air mass is expected to modify to dew points in the 65-70 range by then, with strong sun pushing highs to about 90 or a little warmer. The resulting forecast soundings show ample instability. The question is whether or not there will be any feature on which convection can focus. Being at the southern edge of the westerlies aloft could provide something (perhaps a MCS remnant), and a 20% POP was used. After this, the faster flow aloft retreats to our north and northeast, and with this a dry forecast was used for Monday. However, heat will remain. After this, a large scale upper trough will be dropping southeast out of Canada toward the Great Lakes and Ohio Valley. It will result in geopotential height falls over our region for Tuesday, and increasing mid/upper level flow by Wednesday along with further height falls. The trough will also support a cold front which is expected to approach Tuesday night and reach KY on Wednesday. Low level flow ahead of the front will bring higher dew points off the gulf into our area. The approaching upper level trough and increasing dew points may allow for a few showers/thunderstorms on Tuesday and Tuesday night. However, the highest POP looks like Wednesday as the front arrives, and likely category was used area wide. Model agreement drops off after this point with regard to frontal progression. The 12Z run of the GFS takes the front far enough to our south to allow for dry weather here on Thursday and Thursday night. The ECMWF is slower, with precip lingering longer, especially in our southeast counties. A model blend being used will take the differences into account in its averaging. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 1905 PM EDT FRI JUL 12 2024 We are seeing VFR conditions prevail over the TAF sites to begin the period. The guidance continues to be bold with the fog development tonight at some of the TAF sites, but not sure how extensive this will be given the previous nights have been lack luster. We are see more low to mid-level clouds than we saw yesterday which would lead to less fog concerns. The one issue would be any showers that can develop this afternoon could cause more localized issues outside of the typical river valley fog. Given this will lean toward mainly MVFR fog at SME/LOZ/SYM late tonight between 8Z and 10Z. This will lift around 13Z to 14Z Saturday morning. Then we will see VFR conditions prevail through the remainder of the TAF period. The winds will remain light and variable through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...DJ SHORT TERM...VORST LONG TERM...HAL AVIATION...DJ
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
557 PM CDT Fri Jul 12 2024 .KEY MESSAGES... - Hot and humid this weekend with the potential for several conditional chances for strong to severe thunderstorms Saturday through Monday. - Slight Risk (2 of 5) of Severe Weather Saturday. All hazards will be possible if thunderstorms develop, best chance along and north of I-94. - Cooler, drier pattern after Monday. && .DISCUSSION... Issued at 222 PM CDT Fri Jul 12 2024 Rest of Today... Diurnal cumulus clouds this afternoon forming below an upper level inversion. With this inversion in place thunderstorm activity should be capped this afternoon and evening. Continued southerly flow will advect warmer and more moist air into the Upper Midwest tonight. Subtle curvature aloft could produce enough lift for some thunderstorm late tonight. Saturday... Continued from the Rest of Today discussion CAMs continue to show a line of storms forming Saturday morning. The best chances will be to north of I-94. But some solutions like the 12Z HRRR and NAM Nest have taken this farther south. Continued advection will bring us our hottest day of the year, especially over western Minnesota where heat index values will be over 100. Widespread heat index values above 90 expected and over 95 in the Twin Cities metro. Little recovery from heat stress expected overnight with lows only in the lower to mid 70s. This will be especially pronounced in the core Twin Cities where the urban heat island will help keep overnight temperatures elevated, which is why the Heat Advisory extends overnight into Sunday. As mentioned in the previous discussion the environment will be favorable for thunderstorms. Above normal precipitable water will allow for high rain rates, but flow should be fast enough to avoid much of a flooding risk. On the severe side CAPE is very high with multiple CAM soundings showing values in excess of 3000 J/kg and some as high as 5000 J/kg. The question is when CI will occur. Forcing suggests later in the day and surface cooling could cause issues with surface based convection. The timing in most CAMs also suggests more of an evening timing after peak surface heating. The boundary layer up into around 850 mb thanks to the WAA will take longer to cool such that a cap could form. Shear is sufficient for strong to severe storms. Mid level lapse rates will support upward motion, but low level lapse rates will depend on the time of day. As the surface cools it will make the low level lapse more complicated. SPC continues to have a slight risk (2 of 5) with all severe hazards possible. Summary of this day, hot and humid with both early day and late day thunderstorm chances (better severe chances with the late round). Sunday... The heat will shift south and east on Sunday with lower, but still hot temperatures over western Minnesota. With temperatures remaining hot in the morning there will be little recovery from heat stress. A shortwave on Sunday will give another chance for thunderstorms and with the warmth still around plenty of instability. This will be another day to watch out for, but this forecast is dependent on how Saturday plays out. This could be just as hot if not hotter than Saturday for the Twin Cities depending on where and when storms occur. Also how worked over the atmosphere gets on Saturday will be key for storm chances on Sunday. Ensembles highlight variable storm chances for Sunday and we might not have high confidence until Saturday afternoon on which direction the forecast goes. Regardless it will be a hot day with another chance for thunderstorms. It is just how hot and will storms form that are the questions. Monday... The peak of the heat will be past us on Monday, but it will still be hot but likely sub-advisory heat. This looks to be the best synoptic setup of the next three days based on the jet streak and 500 mb shortwave. Just less instability and a shear setup more dependent on speed shear. Once again this day will be dependent on the weekend days before and how the atmosphere evolves. Tuesday through Thursday... On the back side of Monday`s wave cooler and drier move into the Upper Midwest. Highs will be in the mid 70s to lower 80s, which after a weekend of 90s will be quite a cool down. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 557 PM CDT Fri Jul 12 2024 Light southerly winds and mostly clear skies for much of the night. Low chance for TS is expected late tonight across western MN, then expanding eastward Saturday morning. There remains low confidence in the development of this TS, spatial extent, and timing. Therefore, maintained the PROB30 for all TAF sites. KMSP...No concerns tonight, then chance of TS late Saturday morning into the early afternoon. /OUTLOOK FOR KMSP/ SUN...VFR, chc -TSRA/MVFR. Wind S 5-10 kts. MON...VFR, chc -TSRA/MVFR. Wind W 5-10 kts. TUE...VFR, Wind NW 5-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...Heat Advisory from 1 PM to 8 PM CDT Saturday for Brown- Chippewa-Lac Qui Parle-Redwood-Renville-Stevens-Swift- Watonwan-Yellow Medicine. Heat Advisory from 2 PM Saturday to 8 PM CDT Sunday for Anoka- Carver-Dakota-Hennepin-Ramsey-Scott-Washington. WI...None. && $$ DISCUSSION...NDC AVIATION...Borghoff
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
854 PM EDT Fri Jul 12 2024 ...New UPDATE... .UPDATE... Issued at 832 PM EDT Fri Jul 12 2024 Did wind up having a few isolated showers develop over the terrain of the plateau late this afternoon and early evening. Those are on the decline now and do not expect any further development. Wouldn`t be surprised to have a similar scenario tomorrow as well. Upper heights will rise tomorrow, but there`s a subtle shortwave moving into western Kentucky this evening that will continue to shift eastward tonight and through the day tomorrow. That could hamper the effects of rising heights enough for there to be another instance of some isolated showers over the higher terrain of the plateau and certainly the Appalachians. That said, steering flow, albeit weak, would likely keep any mountain convection on mainly the NC side of things so the plateau may have relatively speaking better odds. In any case, not enough confidence in this low-impact aspect of the forecast (nearly all areas will be dry) to consider making edits at this time. Also made some slight adjustments to temperatures and dewpoints through roughly midnight to account for current trends. Blended in some of the latest HRRR which is slightly slower to cool temps off and bring dewpoints up. Nothing significant though, and the forecast seems to be in good shape otherwise. && .SHORT TERM... (This evening through Saturday) Issued at 329 PM EDT Fri Jul 12 2024 Key Messages: 1. The area is likely to stay dry with even hotter temperatures on Saturday in the mid to upper 90s across most of the area. This Evening/Tonight Currently this afternoon, weak upper troughing is centered to our west with surface high pressure. Model sources indicate lower than average PWAT values for mid July, around or even below 1 inch. Weak flow from the N to NE has been around 5 to 10 kts and will continue overnight. PoPs are low, however some scattered showers are possible in our northeastern counties, due to fairly subtle surface troughing to our east. Patchy fog is certainly possible in the northeast, but continued dry air will limit development. With how dry conditions are today, many places will likely drop into the 60s by the morning. Tomorrow Hot and dry conditions will continue as 500mb heights rise to around 5,940m. Dew points and PWATs are slightly higher, but much of the region can still expect below average moisture. Winds become northwesterly Saturday afternoon and evening. Model agreement indicates MLCAPE values slightly higher than today with most areas around 500 J/kg. Orographic lift from northwesterly flow could bring isolated convection along the mountains, but this potential is very limited due to continued dry air and subsidence. 850mb temperatures will rise beyond 20 Celsius, which suggests that many areas will rise well into the 90s. However, heat index values shouldn`t be too much higher because of drier air due to the deep mixing and subsidence. && .LONG TERM... (Saturday night through next Friday) Issued at 329 PM EDT Fri Jul 12 2024 Key Messages: 1. Warming trend continues this weekend into early next week, with the potential for record breaking daily high temperatures for the start of the work week. 2. Outside of an isolated high elevation shower/storm, mostly dry conditions are expected through the middle of next week. 3. Chances of precipitation begin to increase by late next week as a weakness in the ridge develops. Discussion: Ridging will continue to dominate our weather through the weekend and middle part of next week. This will result in continued dry weather, sunshine, and warm 850mb temperatures around 22 to 25 deg C across the Southern Appalachians and Tennessee Valley. Based on these warm boundary layer temperatures, most model and statistical guidance is placing max temperatures in the upper 90s to lower 100s across the region which would be near record max high temperatures. A few isolated showers or thunderstorms may be able to develop across the higher elevations due to the differential heating along the high terrain, but probabilities are less than 20 percent. Lack of deep moisture and continued ridging will limit instability for convection. This hot and dry pattern will likely exacerbate drought conditions over the coming week. By late next week, a weakness in the ridge is expected to develop across the Mississippi Valley with increased convective coverage. The question is how much convection will make it into our area with continued ridging across the Southeast limiting the eastern progression of precipitation. There are signals that perhaps we get some relief with precipitation in the week two period, as seen in the latest CPC 6 to 14 day outlooks, but confidence is low. At this point, chances for meaningful rainfall coverage and amounts is not very high over the next 7 days. Daily Record High Maximum Temperatures Date Chattanooga Knoxville Tri-Cities Oak Ridge 07-12 104(1930) 104(1930) 93(1993) 100(1980) 07-13 105(1980) 100(1936) 96(1993) 100(1980) 07-14 103(1954) 101(1954) 98(1954) 101(1954) 07-15 103(1977) 98(1995) 96(1995) 100(1980) 07-16 105(1980) 100(1980) 100(1988) 103(1980) 07-17 103(1980) 101(1980) 94(1980) 103(1980) && .AVIATION... (00Z TAFS) Issued at 756 PM EDT Fri Jul 12 2024 Light winds and FEW060-070 will prevail through the period at all sites. Likely see an ISOLD SHRA or two over the terrain of the mountains or plateau again tomorrow afternoon and evening, but doubt they would influence any terminals so will leave all sites dry. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 97 72 98 75 / 0 0 0 0 Knoxville McGhee Tyson Airport, TN 93 69 95 72 / 0 0 0 0 Oak Ridge, TN 95 69 95 71 / 0 0 0 0 Tri Cities Airport, TN 92 64 92 67 / 0 0 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...CD LONG TERM....JB AVIATION...CD
Area Forecast Discussion
National Weather Service Raleigh NC
730 PM EDT Fri Jul 12 2024 .SYNOPSIS... Areas of low pressure will ripple along a quasi-stationary front over the Piedmont through tonight. The front will weaken and dissipate over the region this weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 730 PM Friday... Latest radar scans showing a few MCVs moving over the area. The main one could be seen across over the Northern Piedmont swirling over Vance, Warren and Franklin counties. The bulk of the rain is over the Coastal Plain and Northeastern Piedmont. While areas are expected to briefly dry out, another round of showers and storms are expected to develop later tonight. The heavy rain threat and flooding threats will continue into the overnight hours. Thus, the Flood Watch for most of NC will not be cancelled early. Latest model guidance is showing the best chance for redevelopment anywhere along and east of the US1 corridor. Lingering showers overnight should be pushing near the coast by sunrise as dry air moves into the region. Lows overnight will range from low to mid 70s. As of 218 PM Friday... * Flood Watch remains in effect for all but the far western Piedmont counties until midnight tonight * Potential exits for localized 4+ inches of rainfall over portions of the Piedmont and Coastal Plain Sfc analysis this afternoon shows the sfc boundary stretching from the southern Piedmont northeast through the northern Coastal Plain. This area continues to see the strongest convection and rain rates. A MCV was observed spinning over the Sandhills/central Piedmont when looping radar scans. This feature, along with the instability axis east of the boundary will continue to shift northeast over time through this evening. Latest high-res ensemble guidance (HREF/REFS/WoFS) all suggest the possibility of higher rainfall rates falling first over the southern/central Piedmont the next few hours, before pivoting up into the northern Coastal Plain later this evening. There is a signal for localized amounts as high as 5 inches in these areas. Given the high rain rates thus far, the continued highly anomalous moisture flux, and some reports of flooding, will continue the Flood Watch through midnight tonight. The bulk of the rain will pull north overnight tonight, but latest runs of the HRRR do maintain the potential for some linger showers/storms over our central/northern Piedmont. Overall though, most of the rain should be north of our area through sunrise tomorrow. Overnight lows will remain in the mid 70s with patchy fog possible. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... As of 218 PM Friday... While the sfc/mid-level low will have pulled bulk of the precipitation north of our area by 12Z Saturday, anomalous moisture will linger especially along and east of US-1. As such, additional showers and a few storms will likely develop Saturday afternoon along the dissipating frontal boundary. Highest chances will focus further east. Flash flooding potential should be limited Saturday, but we are still outlooked in a Marginal ERO from WPC across eastern areas. FFG should be a bit lower given the heavy rain on Friday, and thus urban areas could be susceptible to flash flooding. Although, overall coverage should be more limited compared to Friday. Temperatures will rise back into the lower to mid 90s, peaking across the far southwestern Piedmont. Dew points will likely max in the 70s again Saturday afternoon (highest to the east). However, some fleeting wnwly flow aloft may introduce a bit of mixing (especially out west where it will be hottest). Thus, heat indices should stay below advisory criteria. Warm overnight lows in the lower to mid 70s is expected. && .LONG TERM /SUNDAY THROUGH FRIDAY... As of 252 PM Friday... ...Dangerous Heat Returns Sunday Through the Middle Part of Next Week... ...Pattern change with trough developing to our west (Ohio Valley into the TN Valley) late week into next weekend brings threat of a stalling front and heavy rain/cooling temperatures... The main weather story will be the return of dangerous heat beginning Sunday and peaking Monday and Tuesday. Heights continue to rise Monday and Tuesday. The low level flow is forecast to be more westerly. Heat Advisory criteria looks likely to be met in the southern and eastern areas where index values should reach and exceed 105 Sunday and Monday even with some mixing out of the dew points in the afternoon, then possibly Excessive Heat Warning criteria of 110 on Tuesday and Wednesday as the heat wave peaks. Actual highs should reach the mid 90s to lower 100s Monday, Tuesday, and possibly Wednesday. Lows in the mid 70s to lower 80s. Both could challenge daily records. There is only a small chance of PM storms Monday and Tuesday. The chance of mainly afternoon and evening thunderstorms returns Wednesday especially in the west. All areas have a good chance to likely Thursday and Friday as a cold front will approach from the NW. Highs will "cool" into the lower to mid 90s Thursday and 80s by Friday. A potential wet period with less heat late next week into the weekend. && .AVIATION /23Z FRIDAY THROUGH WEDNESDAY/... As of 705 PM Friday... TAF period: While most terminals are reporting VFR conditions around 00Z, widespread ceiling restrictions will develop overnight. While RWI has a narrow window for dropping to LIFR ceilings, there is high confidence in all other terminals dropping to 500 ft ceilings or lower. Coverage of showers and thunderstorms has dropped a little bit more quickly than anticipated, and a VCSH/VCTS mention should be enough at most sites. The low ceilings should begin to lift shortly after sunrise Saturday, and all sites should return to VFR conditions by Saturday afternoon. A chance of thunderstorms will return to RDU/FAY/RWI Saturday afternoon. Outlook: Morning low stratus and/or fog will be possible again Sun morning mainly at RWI and FAY, followed by primarily hotter and mainly dry, VFR conditions until the next front settles into the region late Wed through Thu. && .CLIMATE... Record High Temperatures: July 15: KGSO: 97/1974 KRDU: 99/1997 July 16: KGSO: 99/1915 KRDU: 101/1887 KFAY: 103/1937 Record High Minimum Temperatures: July 12: KGSO: 76/2011 KRDU: 78/2011 KFAY: 80/1935 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 && .RAH WATCHES/WARNINGS/ADVISORIES... Flood Watch from midnight EDT tonight through Friday evening for NCZ007>011-022>028-039>043-074>078-083>086-088-089. && $$ SYNOPSIS...MWS NEAR TERM...CA/Luchetti SHORT TERM...Luchetti LONG TERM...Badgett AVIATION...Green/MWS CLIMATE...RAH
Area Forecast Discussion
National Weather Service Sacramento CA
202 PM PDT Fri Jul 12 2024 .SYNOPSIS... Hot and dry weather will continue through Saturday with Moderate to Extreme HeatRisk persisting across much of the region. Elevated fire weather conditions will also continue. Isolated thunderstorm chances today-Sunday, mainly along the Sierra crest, best chances from US-50 southward. Cooler temperatures on Sunday and into next week. && Key Points - Long-duration, dangerous heat event persists through Saturday, followed by some cooling over the weekend into next week. - Chances of showers/isolated T-storms along the Sierra Crest today through the weekend. - Red Flag Warning has been issued for Fire Zones 221 and 269 for elevations greater than 6000 feet. .Discussion... Another hot day in store for interior NorCal today. At the time of this writing, it is 106 F at our Downtown Sacramento weather observation site, and the temperature is forecast to climb to around 110 as we move into the peak heating hours. Tomorrow we expect a slight cooldown across the central Sacramento Valley, Delta, and northern San Joaquin Valley with highs in the 90s to 105, with the coolest temperatures in the Delta thanks to onshore flow. The Heat Advisory for the Delta and Sierra, as well as the Excessive Heat Warnings for the Valley and Foothills remain in effect until 9PM PDT tomorrow night. We are still under the influence of a broad area of high pressure in the Four Corners region and will remain affected by the high pressure until at least Sunday night. Monsoonal moisture is embedded within the high pressure, and is beginning to move into our area this afternoon. Some flashes of lightning have been observed this afternoon, mainly in far southeastern Tuolumne County just east of Hetch Hetchy. This activity is moving off to the northeast and out of our coverage area, however an isolated shower or thunderstorm cannot be ruled out the remainder of the day in the far southeastern sections of the forecast area. Tomorrow, temperatures will cool as monsoonal moisture will advect into interior NorCal, bringing some high clouds and possible sprinkles across the Valley. Some Hi-Res Convective Allowing Models (CAMS) such as the NAM and HRRR reveal the potential for thunderstorms across the Sierra crest, with the best chances south of HWY-50 tomorrow and Sunday. Forecast soundings suggest a north-northeast steering current, so any storms that develop could drift along the Sierra crest. Current National Blend of Models probabilities for thunderstorms are around a 15-30% chance for tomorrow and Sunday. With the elevated ERC values in the Sierra and the potential for dry thunderstorms, a Red Flag Warning has been issued for Fire Zones 221 and 269 for elevations above 6000 feet beginning tomorrow at 5AM PDT and lasting through Sunday at 8PM PDT. Weak off-shore troughing develops Sunday as well and will promote more onshore flow into the Delta and central Sacramento Valley, which will help lower temperatures across the region. Confidence has increased in relatively cooler temperatures as we move into the next work week, with the return to near-normal highs. Moderate HeatRisk will persist across the region beginning Sunday. Upper level heights will remain in a westerly flow pattern, so the relative cool down is expected to persist as we move into the extended period. Latest HeatRisk: wpc.ncep.noaa.gov/heatrisk/ Heat Safety Tips: weather.gov/safety/heat && .EXTENDED DISCUSSION (Tuesday THROUGH Friday)... Tuesday and Wednesday, we will still have westerly flow aloft which will promote more onshore flow and help us remain near normal temperature wise. Widespread Minor and isolated Moderate HeatRisk return, which will be a welcome relief after our record- setting heat wave. Forecast high temperatures are currently 90-100, with the warmest temperatures in the northern Sacramento Valley. Thursday and Friday, a ridge of high pressure will once again try to build in over the Four Corners region, which will increase high temperatures around the area again, but at this time, will not compare to our latest heat event. Minor to Moderate HeatRisk will remain in the forecast, and high temperatures are forecast to be in the low 90s to around 105, with the Delta being the coolest and the northern Sacramento Valley once again being the warmest. && .AVIATION... VFR conditions next 24 hrs, except local MVFR possible vicinity isolated thunderstorms northern Sierra 22Z until about 02Z Saturday. Surface wind gusts generally below 12 knots except southwest wind gusts 15-20 knots vicinity west Delta after 00Z Saturday. && .STO WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 9 PM PDT Saturday for Central Sacramento Valley-Motherlode-Mountains Southwestern Shasta County to Western Colusa County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Northern San Joaquin Valley- Shasta Lake Area / Northern Shasta County-Southern Sacramento Valley. Heat Advisory until 9 PM PDT Saturday for Burney Basin / Eastern Shasta County-Carquinez Strait and Delta-West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park. Red Flag Warning from 5 AM Saturday to 8 PM PDT Sunday for Northern Sierra Including the Tahoe and ElDorado NF/S West of the Sierra Crest-Stanislaus NF West of the Sierra Crest. && $$
Area Forecast Discussion
National Weather Service Tucson AZ
227 PM MST Fri Jul 12 2024 .SYNOPSIS...Excessive heat continues across parts of southeast Arizona this evening with temperatures then moderating over the weekend into next week. Today and Saturday storms will mainly be confined to the White Mountains and central/western Pima County. Sunday into next week storm coverage will increase to cover most of southeast Arizona with typical monsoon threats. && .DISCUSSION...Sky has started to fill up with cumulus clouds with some taller build ups. It is enough for the radar to pick up returns in the Southeast Arizona. Latest RAP analysis has CAPE values 500-1000 J/Kg, DCAPE close to 1900 J/KG, and the primary moisture is sitting over Tucson to the west. The forecast for the rest of the afternoon is still on track to have mainly isolated thunderstorms around Tucson and a isolated-scattered towards the western part of Pima County. The CAMs depict a more down-ish day with only a handful of thunderstorms, but with the current trend of the moisture slowly moving out to the west with dry air filling behind it, it can help trigger some thunderstorms around Tucson and the Sky Islands. Based on the storm environment, the storms will struggle to maintain itself a little bit initially, but it could gain better organization more into western Pima County due to better shear environment. Plus, better chances for storms in the western Pima County. Heat will remain this afternoon. The Excessive Heat Warning will expire at 8 PM MST tonight. Overnight lows will be elevated again for tomorrow morning. For the weekend, temperatures will trend down a bit through the weekend. Moderate Heat risk is expected Saturday through most of the new week. The High Pressure Center will transit away from the Great Basin region and position itself over the Four Corners. Thunderstorm chances will remain around Saturday, similar to this afternoon chances and coverage. By Sunday, the high pressure will be in an ideal position to bring more moisture back into the region and resulting in better chances for thunderstorms and showers. The ensembles show PWATS climbing back to 1.2-1.4 range on Sunday and more on Monday; 1.4-1.8 inches with a few members 1.8-2.0 inches. With this forecast package, Sunday and Monday will be more up days for the monsoon with Monday being the better day for thunderstorms out of the two days based on the latest ensemble models. After that, it will be day-to-day variability of thunderstorms which we will have a better understanding by the end of the weekend. Temperatures next week will be around normal for the fist part of the week and then trending back to the hot side by the end of the week. && .AVIATION...Valid through 14/00Z. SCT-BKN clouds at 8k-12k ft AGL thru 13/04Z and again aft 13/18Z. Diminishing cloud cover aft 13/04Z and generally clear skies/SKC conditions between 13/07Z and 13/18Z. Isold/SCT TSRA/SHRA thru 13/04Z and again aft 13/19Z, mainly across central/western Pima County and in the White Mountains. MVFR conditions in TSRA, with mountain obscurations, vsby reductions and wind gusts to 40+ knots. Outside of TSRA, SFC wind ELY/SELY at 8-14 kts with occasional gusts to 22 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Through Saturday, the best chances for storms will be in central/western Pima County and in the White Mountains with the main threats being strong winds and locally heavy rainfall. Moisture increases on Sunday into next week leading to an expected increase in storm coverage and heavier rainfall. Minimum relative humidities through Sunday will range from 12 to 20 percent in the lower elevations and 15 to 30 percent in mountain areas. Humidity values increase Sunday into next week as greater moisture returns. Away from thunderstorms, expect 20-foot winds to generally be 15 mph or less, with afternoon/early evening gusts to 20-25 mph and light winds overnight. Wind direction will be east/southeast through Saturday, becoming westerly through the middle of next week. && .TWC WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM MST this evening for AZZ504>506. && $$ Public...Strongman Aviation...Zell Fire Weather....Zell Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Las Vegas NV
1240 PM PDT Fri Jul 12 2024 .SYNOPSIS...One last day of excessive heat today as the pattern begins to shift towards a monsoonal one. Expecting a first taste this afternoon with strong thunderstorm outflow winds probable in Mohave County and on the area lakes. Temperatures cool slightly this weekend as storms become more numerous. Rain chances become more isolated next week as drier air filters in from the west. && .SHORT TERM...through the weekend. The day is finally here! The final day of this excessive, extreme, historic (insert your favorite descriptor) heatwave is upon us. Highs today will once again threaten daily records at several climate sites, but some relief is on the way. Monsoonal moisture and more widespread convection/clouds tomorrow will bring temperatures down sufficiently to allow the heat headlines to expire. That being said, it is still going to be hot, with temperatures remaining above normal through the weekend. Now, let`s talk about storms. The 500mb high that has long been positioned just to our west or practically overhead is finally beginning to move to the Four Corners area. Positioned just to our north today, there isn`t much southerly component in the flow aloft, thus moisture remains rather meager today. However, there will be just enough to spark thunderstorms in eastern Mohave County this afternoon, with slightly greater coverage than we saw yesterday. Like yesterday, the very dry low-levels will make strong outflow winds the primary hazard with any convection. Latest HREF shows 750-1000 J/kg of surface-based CAPE atop 2000+ J/kg of DCAPE, suggesting an environment rather favorable for strong thunderstorm outflow. And indeed, the CAMs have latched on to this potential, with the HREF showing 30-60% chances of 40+ mph wind gusts over central Mohave County and all the way to the I-15 corridor in southern Nevada. What the outflow does when it gets to the Las Vegas Valley is more uncertain. Some guidance has it kicking off additional storms on the terrain surrounding the valley, while others do not. This will be something to watch in subsequent model runs and as the actual convection evolves this afternoon. Should storms fire in the Las Vegas vicinity, strong winds will be possible in the valley. In terms of rainfall, not expecting much. HREF ensemble max 3-hr QPF tops out at ~0.5" on some of the high terrain in Mohave County, but the ensemble mean remains less than 0.1". Southeasterly winds aloft within the high`s anticyclonic flow will usher in better moisture tomorrow and Sunday as it shifts east. Latest EPS mean PWAT has values of 0.75"+ across much of the area, with the 1.00"-1.50" values largely confined to the southern half of the CWA. This moisture combined with slight cooling aloft will yield CAPE values of 250-1000 J/kg for most of the area. Despite the increase in moisture, low levels will remain relatively dry as temps stay above normal. 12z HRRR soundings show DCAPE of 1500-2200 J/kg from Bishop to Needles, suggesting strong outflow winds will continue to be the primary hazard. Any flash flood potential is confined to eastern Mohave County where WPC maintains a marginal risk for excessive rainfall this weekend. In the Sierra and Owens Valley, the combination of dry low levels, cured fuels, and scattered thunderstorms will yield high fire danger this weekend. Due to this threat, a Red Flag Warning is in effect for the area Saturday and Sunday. .LONG TERM...Monday through Thursday. Monsoonal moisture from the weekend will linger to start the work week, but a slight westerly component in the winds aloft will gradually push the moisture eastward through mid-week. As a result, PoPs of 20+ percent, which exist on the high terrain from the Spring Mountains and points east on Monday, become confined to eastern Lincoln and Mohave Counties Tuesday - Thursday. Main concerns with most storms will be gusty outflow winds and dry lightning, though convection in Mohave County and the Lower Colorado River Valley will have the potential to produce isolated flash flooding due to the greater PWAT values. Latest WPC ERO gives paints this area with marginal risk of excessive rain (at least 5% chance of occurring) on Monday. For areas along and west of I-15, temperatures remain above normal, though not expecting the blistering heat we`ve seen this week. Highs across the Mojave Desert are forecast to be in the 100-115 range, with lows in the 80s across our lower deserts and 60s/70s in our northern locations. Combined, this should yield widespread Moderate HeatRisk through the week. && .AVIATION...For Harry Reid...For Harry Reid...Light east winds will become southeast this afternoon. 15-20KT gusts are possible with the southeast winds, especially after 21Z. There is a low chance for convection to impact the terminals directly today with a 20% probability for thunderstorms between 01Z to 05Z. However, watching the potential for strong outflow winds from distance thunderstorms to push through this evening. If these winds were to reach the terminals, it would be between 01Z-04Z, likely as an east or southeast wind. Gusts over 35KT are possible with these winds. After 06Z, a quiet night with dry conditions and light diurnal winds tonight through Saturday morning are expected. Convection will develop again Saturday afternoon after 20Z in and around the terminals with chances for thunderstorm at the terminal higher Saturday compared to today, around 40%-50%. Any thunderstorms could bring lightning, brief rain, and sudden gusty winds. Will need to watch the potential for more gusty outflow winds Saturday afternoon from distant thunderstorms in the late afternoon and evening, which are possible but confidence is too low for outflows at the terminal to include them in the current TAF package. Outside of convective influence, expecting breezy south to southwest winds Saturday afternoon with a moderate (40%-50%) chance for gusts over 20KT. Occasional SCT clouds around 15fkt-20kft are expected through the TAF period. For the rest of southern Nevada, northwest Arizona and southeast California...Scattered thunderstorms will develop this afternoon in western Arizona and southern Clark County. The highest risk for thunderstorms will be in Mohave County as well as the Spring Mountains and the terrain in far southern Clark County. Any thunderstorms may produce lightning, brief rain, CIGs to 10kft, and sudden gusty winds. Watching for an outflow to move out of northern Mohave County this evening through southern Nevada, potentially making it as far as Death Valley. There is a 40%-60% risk for sudden gusty winds over 35KT through MOhave County and the northern Colorado River Valley between 00Z-03Z, with lower chances around 20%- 30% in the southern Colorado River Valley, southern Clark County, and southeast Inyo County. COnvection and the threat for sudden gusty winds will dissipate after 04Z and a dry night with diurnal wind trends is expected tonight. Outside of the potential convection- winds today will favor the south to southeast wind speed around 10KT and occasional gusts up to 20KT this afternoon. At KBIH, gusty west winds are possible after 21Z. Winds will become light and diurnal overnight and continue through Saturday morning. More widespread scattered thunderstorms are possible Saturday afternoon across much of the region, which could bring additional gusty outflow winds and lightning to the area. && .CLIMATE...Numerous climate locations have a forecast high temperature and/or forecast warm low temperature within 3 degrees of the daily record. The table below shows the daily record maximum temperature and the year the record was last set. An asterisk (*) denotes which records are in jeopardy (within 3 degrees of the forecast). MAX FRI, JUL 12 RECORD (Yr) Las Vegas 114(2003)* Bishop 108(2020)* Needles 124(1925) Daggett 115(2021)* Kingman 111(2020) Desert Rock 112(2021)* Death Valley 130(1913)* The table below shows the daily record warm minimum temperature and the year the record was last set. An asterisk (*) denotes which records are in jeopardy (within 3 degrees of the forecast). WARM MIN FRIDAY, JUL 12 RECORD (Yr) Las Vegas 94(2020)* Bishop 69(1990)* Needles 96(2021)* Daggett 87(2012)* Kingman 80(2021)* Desert Rock 83(2023) Death Valley 107(2012) && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ DISCUSSION...Woods AVIATION...Nickerson For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter