Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/18/20

Area Forecast Discussion
National Weather Service La Crosse WI
1050 PM CDT Fri Jul 17 2020 .SHORT TERM...(This evening through Saturday) Issued at 240 PM CDT Fri Jul 17 2020 Lots of active weather to discuss in the short term! Ridging continues to amplify in the low levels with broad southerly flow pumping increasing heat and humidity into the region. Quite a stark contrast as you step outside this afternoon compared to yesterday with dewpoints having jumped a good 10 to 15+ degrees in the last 24 hours, currently sitting in the lower 70s across the majority of the forecast area. And thanks in part to that heat-loving, humidity- breathing Midwest corn, the muggy-meter will continue to climb a bit more over the next 24 hours. Air you can wear, soupy, yucky (however you choose to describe it)...any similar descriptors will be applicable heading into Saturday as dewpoints climb into the mid to upper 70s. Of course that sets the stage for occasional shower and storm chances as the weekend gets underway. The increase in low level moisture today has favored development of a pretty expansive cumulus field across the area. A warm front lifting through northern Clark and Taylor counties has an accompanying band of higher MLCAPEs up to 2500 J/kg per RAP analysis. Already seeing some agitated cu and some weak radar echoes developing along this boundary thanks to associated weak fgen. As a result, a broken line of showers and storms will be possible through late afternoon in this area, but not expecting this activity to get out of hand. For tonight, all eyes will be on MCS already developing over North Dakota at this hour. Still considerable uncertainty as to how this storm complex will evolve heading into tonight as it matures into a bowing line crossing into northern MN and eventually northern WI late tonight. CAMs are still split as to whether this system stays mainly over northern WI or if it expands further south and perhaps dives a little more southeastward into our area. Earlier HRRR runs trended a little more northward, and recent runs have consistently taken this complex just by or clipping our far north. ESRL HRRR, RAP, and ARW have the MCS clipping areas north of I-94. Meanwhile 17.12Z NAMnest, NMM, and NSSL WRF show a greater southward development that cuts through a greater extent of our forecast area. Needless to say, still quite a murky picture, but am inclined to lean towards the more northern solutions as the favored outcome given the HRRR`s earlier trend and hour-by-hour consistency. Yes, greater instability will reside farther south, but there will also be considerable capping developing over our area due to elevated warm layer building into the region. So not convinced the southern solutions will manifest, but would like to see more agreement among the CAMs before writing this idea off completely. For now, retained highest PoPs north of I-90 and particularly north of I-94. This will also be an area with plenty of deep layer shear in the vicinity of the MCS to sustain it. Damaging winds will be the main threat, but can`t rule out some isolated hail and perhaps a brief tornado (impressive 0-1km shear and hodograph curvature). Timing would be late tonight towards daybreak Saturday, roughly between 3am-7am, but this too will need to be refined as mesoscale details are resolved. Saturday`s main story will be the heat and humidity. Very muggy morning lows of around 70 to the mid 70s will give a head start to the day`s building heat, with afternoon temperatures climbing into the low to mid 90s across most of the area. Exactly how hot it gets will depend on whether we have any lingering widespread cloud cover from the morning MCS, but models have been trending optimistic for a decent amount of sunshine and a toasty southwest breeze. Expecting peak heat index of generally 100-105 degrees for most of the area, with some of the typical hot spots perhaps in the 105-110 range for a brief time. So heat advisory for majority of the area (minus Taylor County where heat index will be 95-100) remains unchanged. Looks like stout low level capping in place through the day, so not expecting any convective activity until round 2 of storms in the evening (read on below for details). .LONG TERM...(Saturday night through Friday) Issued at 240 PM CDT Fri Jul 17 2020 A cold front will approach the area Saturday night, bringing another round of more widespread showers and storms to the area through the overnight hours. Due to very humid conditions lingering into the evening hours, CAPE values of 3000-4000+ J/kg will be likely ahead of the front. Shear will also be plentiful, with around 50 kts between 0-6 km, though the 17.12Z GFS keeps the better shear behind the front. There are some differences still with exact timing that storms will develop and move into the local area as the very warm temperatures will keep the area capped off through late Saturday night. The general consensus is that storms will develop over central Minnesota sometime late Saturday afternoon into early evening and progress east with the front, reaching parts of southeast Minnesota and western into central Wisconsin sometime between 03-06Z. Storm mode will initially be discrete before becoming more linear in nature as it moves into the local area. Primary hazards will be damaging winds and large hail. However, with 0-1 km shear of 15-25 kts, an isolated tornado cannot be ruled out in any discrete storms, though the shear appears to be more speed driven with surface winds mostly out of the southwest. Heavy rainfall is also a concern, especially across parts of central Wisconsin where very heavy rain occurred earlier this week. Precipitable water values look to be near the climatological max nearing 2 inches or slightly above and very deep warm cloud depths of 4 km will allow any stronger storms to drop a lot of rain very quickly. Depending on how the MCS plays out tonight, will need to keep an eye on the flooding potential ahead of the second round of storms expected Saturday night, though storms overall look to be relatively progressive. Little relief in temperatures Saturday night, with values ranging from the upper 60s to 70s - much of the area will stay in the 70s to 80s prior to midnight. Continued warmth on Sunday with highs in the 80s, though it will not feel nearly as warm as Saturday thanks to lower dewpoints arriving behind the frontal passage. Surface high pressure builds in from the west throughout the day on Sunday, keeping things mostly dry. Flow aloft will be mostly zonal for the beginning of next week before transitioning to more northwesterly by midweek as high pressure ridging builds out west. Occasional chances for showers and storms appear likely, with the most notable possibly being Tuesday night or Wednesday as a more potent shortwave trough moves through. Pretty good model agreement that ridging will move overhead by the end of next week, which may bring another period of above normal temperatures to the area. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1050 PM CDT Fri Jul 17 2020 Will be watching the evolution of a complex of storms across central MN as it moves ESE overnight. For now, confidence in storms impacting KRST/KLSE is low enough to omit from the TAFs during the 07-12Z time frame, but trends will be monitored. Otherwise, expect mainly VFR conditions although patchy MVFR ceilings can`t be ruled out overnight. Southerly winds will gust up to 25 kts at times on Saturday. Another round of storms is possible Saturday night with a cold front passing through the area. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Heat Advisory from 1 PM to 8 PM CDT Saturday for WIZ029-032>034- 041>044-053>055-061. MN...Heat Advisory from 1 PM to 8 PM CDT Saturday for MNZ079-086>088- 094>096. IA...Heat Advisory from 1 PM to 8 PM CDT Saturday for IAZ008>011-018- 019-029-030. && $$ SHORT TERM...Kurz LONG TERM...NMB AVIATION...JM
Area Forecast Discussion
National Weather Service Denver/Boulder CO
809 PM MDT Fri Jul 17 2020 .UPDATE... Issued at 757 PM MDT Fri Jul 17 2020 Subtropical moisture moving across the area, led to high based showers and a few tstms, over the higher terrain and along portions of the I-25 corridor. Meanwhile, outflow boundaries have triggered additional activity further east, over the plains, but most of this will end by 10 pm. Otherwise, with lingering clouds overnight, lows will be very mild. && .SHORT TERM...(This evening through Saturday) Issued at 255 PM MDT Fri Jul 17 2020 So far this afternoon, convection has been spotty and weak in the mountains and mainly dying as showers come off the foothills. Dewpoints have dropped into the 30s with resultant very little CAPE less than 600j/kg. Latest HRRR continues to show some weak convection moving onto the plains this evening with main impact of gusty winds with inverted type v soundings. Saturday will be another hot one with readings around 100 on the plains. Could see at least a tied record at Denver, with the old record of 99 degrees. Like today, any convection will be weak, high based with mainly gusty winds with showers. There is expected cold front which will be entering the far northeast corner towards supper time Saturday evening. Could see a few stronger storms there with convergence and higher influx of low level moisture. .LONG TERM...(Saturday night through Friday) Issued at 255 PM MDT Fri Jul 17 2020 A cold front will push down into the forecast area Saturday evening, increasing precipitable water values and CAPE, with upslope flow that may keep convection going through the evening. Could see some stronger storms over the far northeastern plains where CAPE values of 1400-2000 j/kg will have a bit of CIN to overcome as the sun goes down. Upslope flow will continue Sunday and PW values expected to increase over an inch over the plains, while the mountains remain around 0.5-0.7 inches. While temperatures will be 5 to 10 degrees cooler (mainly over the plains), a shortwave trough moving east across the Northern Rockies will aid in lift to increase storm coverage. The added moisture over the plains and the sun`s heating will aid in producing mixed layer CAPE values upwards of 3000 J/kg over the far northeastern plains, along with 40 kts of bulk shear. Will see a chance of severe storms Sunday evening out near the NE border. Yet another shortwave trough over the Northern Rockies and a bit of a northeasterly surge into the plains Monday will keep another day of scattered to numerous showers and storms. Cooler temperatures will lead to weaker CAPE, and the combination of weaker shear will allow for weaker storms. The upper high will begin to move from the Four Corners area Tuesday, increasing heights over the state, yet another surface northeasterly surge will keep a chance of storms across the area. The upper high will then transition east to be positioned over the southern and southeastern states through the rest of the week. This will allow for southwesterly flow into the state, which will bring a warming trend as well as subtropical moisture into the area. A thermal trough over the plains will likely keep most of the showers and storms over the high country, with isolated activity over the plains. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 757 PM MDT Fri Jul 17 2020 High based showers will continue for the next hour or so with brief gusts up to 30 mph. Winds will remain southwest to south overnight. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...RPK SHORT TERM...Entrekin LONG TERM...Kriederman AVIATION...RPK
Area Forecast Discussion
National Weather Service Dodge City KS
522 PM CDT Fri Jul 17 2020 ...Updated Aviation... .SHORT TERM...(This evening through Saturday) Issued at 233 PM CDT Fri Jul 17 2020 A mid level trough was in place over eastern Colorado this afternoon. ahead of the trough southerly winds were common across western KS. Weal 850 mb moisture transport was still in place from around Garden City eastward, and temperatures were looking slower to rise in many areas likely due to the rainfall overnight and to a lesser extent areas of cloudiness. Recent HRRR runs have explicitly developed convection in a NE-SW oriented line southwest of Dodge City, possible associated with an area of low level convergence and very high theta-e. The NMM nits at it as well although the HiRES models do seem to struggle with the same scenario. Given the state of the atmosphere the last few nights we went ahead and added slight chance precipitation TSRA over some southeast counties for he late overnight hours. Any storms that pops up could easily produce a few tenths of an inch of localized rain. In the closer term - the western edge of the heat advisory may have trouble reaching the criterion apparent T of 105, however the higher dew points in the 70s farther west will give it a shot. Have trimmed off the western 2/3rds of the advisory for this afternoon. .LONG TERM...(Saturday night through Friday) Issued at 233 PM CDT Fri Jul 17 2020 Saturday there will be a better setup for thunderstorms as a cold front begins to push southward out of Nebraska and convection at some point is likely to unzip near the cold front dryline interface in northern Kansas...and southwest along the convergence axis toward the Liberal area. With the possibility of a stalled front on Sunday, the pops are even higher. No period of he extended appears definitively dry although by Thursday and Friday it looks like we will be under deeper southwest flow, dryer air and capping for possible a stretch of days. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 514 PM CDT Fri Jul 17 2020 VFR conditions are expected for all terminals this TAF period. Strong SSW winds will combine with the nocturnal low level jet to produce strong S to SW wind shear overnight at all terminals in the 03-14Z time frame. After 14Z, the wind shear is expected to relax, however, strong SSW winds will persist throughout the day tomorrow. && .PRELIMINARY POINT TEMPS/POPS... DDC 76 104 72 93 / 10 10 20 20 GCK 74 104 71 91 / 0 10 20 30 EHA 73 101 69 97 / 10 10 30 20 LBL 75 103 71 98 / 10 10 30 20 HYS 75 102 71 88 / 10 10 30 20 P28 76 103 74 97 / 20 10 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM CDT this evening for KSZ090. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...Springer
Area Forecast Discussion
National Weather Service Grand Rapids MI
1152 PM EDT Fri Jul 17 2020 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 333 PM EDT Fri Jul 17 2020 -Rounds of storms possible over the weekend -Some storms could be strong to severe, especially late Saturday night into Sunday. -Hot and humid weekend; less humid early next week && .DISCUSSION...(This evening through next Friday) Issued at 333 PM EDT Fri Jul 17 2020 -- Rounds of storms possible over the weekend -- Active thunderstorm/MCS pattern quite possible this weekend, with the potential for damaging wind gusts, power outages, isolated large hail, and heavy downpours. Current thinking is that late Saturday night into early Sunday will be the most active period since that`s when the cold front will be coming through. However timing/location of events in MCS patterns can be very challenging since each MCS can influence/alter the downstream environment and future convective development. All eyes tonight will be on the bow echo expected to track through nrn MN into nw WI, where the SPC has a MDT risk of svr wx. This feature will need to be closely watched since it could easily curve southeast and begin impacting west central Lwr MI after daybreak Saturday. While the mid level flow would suggest an easterly trajectory of this feature across upr MI and far nrn Lwr MI, the deep layer thickness/thermal progs very much suggest a southeast trajectory, with areas north of I-96 possibly seeing a morning convective event. This conundrum is quite evident in the various CAMs and HRRR ensembles, with various solutions of how upstream convection will behave very late tonight into early Saturday. The solutions range from 1) All convection remaining to our north, to 2) our nw/nrn cwfa being impacted by a bowing segement, to 3) a few clusters of storms developing southeast of the main MCS along the warm advection wing in the early morning. And to make matters worse, we have one model, the 12Z NAMNest, indicating new clusters of storms developing directly overhead late Saturday afternoon after 21Z, presumably from remnant outflow from the early morning convection. This solution is an outlier, and we tend to believe most of Saturday afternoon and evening will be dry since we should be fully in the capped warm sector. Highest pops and best potential for strong to severe storms impacting a larger portion of our area is Saturday night and Sunday morning. New strong to svr storms that form over nrn WI and nrn LWR MI Sat evening are expected to eventually propagate southward into our higher instability air with capes over 2500 J/KG. If a large MCS impacts the area Saturday night/early Sunday, new convection on Sunday will probably develop south and east of our area. If that MCS doesn`t occur or is focused farther north and west, then Sunday could be an active day especially south and east of GRR. -- Hot and humid weekend; less humid early next week -- While heat indices will be 95-100 this weekend, especially in southern sections, the passage of a cold front late Sunday will bring in less humid air to start next week. That front could bounce back north Tue-Wed briefly and bring another round of storms before returning south of the area again. && .AVIATION...(For the 06Z TAFS through 06Z Sunday) Issued at 1145 PM EDT Fri Jul 17 2020 VFR conditions will continue at all the terminals through late Saturday evening. South to southwest winds will increase to 10-15 kts with gusts to around 20 kts Saturday and some higher gusts to near 25 kts possible at KMKG. Isolated storms are possible Saturday afternoon but there is not enough potential to warrant mention in any of the terminal forecasts. There is a chance for thunderstorms by early Sunday morning but only after 06Z Sunday. && .MARINE... Issued at 333 PM EDT Fri Jul 17 2020 Will be issuing a Small Craft Advisory and Beach Hazard Statement for Grand Haven northward, to be in effect starting 8am Saturday. This is for the increasing south-southwest flow (15-25 kts) that develops after a warm front lifts north through the area. The south side of south piers will be most dangerous such as at Pere Marquette Park in Muskegon and Grand Haven State Park, however the highest waves (near 5 feet) should be north of Whitehall. Once any morning/midday clouds and shower/storms get out of the way, beach populations will likely swell Saturday given the hot and humid weather. Strong longshore and structural currents can pull swimmers into deeper water and high waves can sweep people off piers, so "steer clear of the pier"! These marine headlines will be out through midnight Saturday, but will probably need to be extended and expanded southward for Sunday with the flow turning more westerly with time. There is a good deal of uncertainty in how convective events will play out over the weekend, but obviously thunderstorms will be a hazard on Lake Michigan at times over the weekend - especially late Saturday night. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement from 8 AM EDT Saturday through Saturday evening for MIZ037-043-050. LM...Small Craft Advisory from 8 AM Saturday to midnight EDT Saturday night for LMZ847>849. && $$ SYNOPSIS...Meade DISCUSSION...Meade AVIATION...Laurens MARINE...Meade
Area Forecast Discussion
National Weather Service New Orleans LA
324 PM CDT Fri Jul 17 2020 .SHORT TERM... Today and tomorrow, drier conditions will persist due to dominant higher pressure over the area. Southeasterly surface winds will act to enhance the moisture in the environment. Consequently, a shower or two is possible, especially during peak heating hours tomorrow, but chances are low. Cloud cover will be increasing as we move into the weekend. MSW .LONG TERM... Overall, a typical summertime pattern will dominate Sunday through the end of next week. Surface southeasterly and easterly winds will help to enhance the moisture and warm air advection into the area. Scattered showers and thunderstorms will be possible daily, especially during the afternoon and early evening hours. These storms could have locally heavy rainfall at times where they do occur, especially if any training develops or if storms build over one area for a long time. These storms also will have the potential for frequent lightning and gusty winds in their vicinity. Waterspouts could also be possible if these storms form over the marine waters. MSW && .AVIATION... VFR CAVOK condiitions expected at all terminals next 24-30 hours with light and variable to SE wind. Isolated nature of any convection too low to mention explicitly in TAFs at this time. RR && .MARINE... Winds will be calm (<15 knots) and southeastery to easterly through the next week. Wave heights will correspond to the wind speeds. MSW && .PRELIMINARY POINT TEMPS/POPS... MCB 74 92 74 92 / 10 20 10 30 BTR 74 93 75 92 / 10 20 10 40 ASD 74 93 75 92 / 10 20 10 50 MSY 78 91 78 90 / 10 20 10 60 GPT 76 89 77 89 / 10 20 10 30 PQL 73 93 74 92 / 10 20 10 30 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$
Area Forecast Discussion
National Weather Service Lubbock TX
658 PM CDT Fri Jul 17 2020 .AVIATION... VFR conditions will continue for all TAF sites for the next 24 hours. Storms currently in New Mexico are not expected to directly affect TAF sites. Density altitude is currently around 6500ft. && .PREV DISCUSSION... /issued 239 PM CDT Fri Jul 17 2020/ SHORT TERM... Hot temperatures are once again in place across the region but not quite as hot as previous days. Main forecast concern for tonight is the possibility of isolated thunderstorms near or along the TX/NM state line that could push into our western zones. Visible and Water Vapor satellite imagery shows a slight northeast component to the mid and upper-level flow which could favor steering any storms that develop towards the area. However, models have backed off considerably with generating precipitation in eastern New Mexico and now only the RAP and HRRR are generating storms. Convective parameter fields are looking pretty poor for convection with MLCAPE values at or below 250 J/kg and a strong cap in place. With the preponderance of models remaining dry and meager instability, will keep PoPs out of the forecast for tonight. Biggest question remains how strong the ridge will be tomorrow across the area and how that may impact high temperatures. The ridge will remain overhead but will start to weaken through the day. Thickness values and H850 temps are pretty much unchanged from today so it remains possible that we could see another day of highs at the century mark for Lubbock and most of the forecast area but a few pockets of 98-99 as well. Will keep things on the warmer side of guidance as uncertainty about any cloud cover (looks like we should remain clear to mostly clear) or changes in boundary layer moisture favor going slightly warmer. Jordan LONG TERM... More seasonable temperatures (mid to upper 90`s) are expected for the majority of next week as upper level ridging weakens across the area. Unfortunately, this weak ridging will remain in place across much of the southern U.S. hence limiting the rainfall potential across the area. Monsoonal moisture will continue to be advected into NM during this time period which may set the stage for a few bouts of activity across primarily the southwestern Texas Panhandle. The best shot at precipitation appears to be Sunday evening as a weak shortwave rounds the ridge to the north. This feature should provide enough additional lift for widespread convection to develop across NM which may then move into the southwest Texas Panhandle into the northern South Plains. But each evening through at least Tuesday there will be a chance at seeing activity from NM drift east into our region. This activity will be dissipating as it moves east, therefore it may not make it very far into our forecast area. /WCI && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 14/58/10
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
702 PM CDT Fri Jul 17 2020 .UPDATE... Issued at 701 PM CDT Fri Jul 17 2020 Updated for Aviation Discussion below. && .SHORT TERM...(This evening through Saturday night) Issued at 255 PM CDT Fri Jul 17 2020 Main concern is the potential for severe convection tonight, particularly from late evening into the overnight hours north of I-94, with some concern of excessive heat Saturday afternoon and additional severe weather potential late Saturday afternoon into Saturday night. Short term CAM guidance is in good agreement on a forward propogating MCS impacting the region tonight, but there remains disagreement on where it will track (and to a lesser extent, the timing). The environment will definitely be supportive of strong to severe convection, with heat and moisture surging into the region, and current MLCAPE values AOA 3000 J/KG along and south of I-94. Visible satellite does a nice job of highlighting where the best instability is present in terms of the currently observed cu field. Some convection has already fired in North Dakota, and additional activity will develop to its south and southwest as the shortwave trough in eastern Montana moves eastard. In addition to the instability, wind fields will be supportive of maintining a forward propogating system as it moves into Minnesota tonight, with 0-3 km bulk shear forecast AOA 35 kt across northern and central Minnesota. The main question/issue is how far south activity will track. The HRRR has been one of the more northern solutions, but has trended a bit south with each run through the day. The NAMNest is a southern outlier, with the various other CAMs generally falling in between. Would initially expect things to track eastward with a bit of a dive (and/or southward development) later this evening, with the southern end of the strongest activity near I-94. Damaging wind gusts will be the main concern across our area, with widespread damaging winds a likelihood along the axis of where the primary bowing portion of the MCS ultimately tracks. We should see the bulk of any lingering cloud cover from tonight`s system exit the area Saturday morning, allowing for temperatures to climb into the 90s while dewpoints remain in the 70s. This will result in heat indices from 100-110 across much of the area, and wet bulb globe temperatures maxing out in the mid 80s. Excessive heat warnings and watches cover much of the area (generally near and south of where the frontal boundary is expected to be by mid afternoon). We will see convection develop along the boundary during the mid to late afternoon hours then shift east through the evening as the upper trough moves in and helps push the front east into Wisconsin. Damaging wind gusts and large hail would appear to be the primary concerns given what looks to be a lack of good low level directional and speed shear in the forecast profiles. .LONG TERM...(Sunday through Friday) Issued at 255 PM CDT Fri Jul 17 2020 With significant weather in the short term, stuck pretty close to the consensus NBM guidance for the remainder of the forecast period. Low amplitude troughing looks to remain in place through the first part of the week, with ridging developing over the center of the CONUS once again during the latter half of the week. The upper jet axis will loiter nearby and just north for much of the week, with the baroclinic zone lifting northward through the area during the Thursday/Friday time frame. Several weak shortwaves will move through the region over the course of the week, and after some initial subsidence and dry air Sunday into Monday it looks like we`ll have sufficient moisture and instability for some PoPs through much of the remainder of the week. Given some disagreement in the model guidance, this results in chance PoPs across much of the area from Tuesday through Friday, and at this point there isn`t enough confidence to go dry for many specific periods of time over that span. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 701 PM CDT Fri Jul 17 2020 Incoming storms tonight is the concern, and winds could be very strong. Timing looks to be a bit earlier than previously thought based on short term models and current trends. Storms do appear to be taking somewhat of a turn to the southeast, so only KRWF may escape the storms. Have added low level wind shear in the southwest since storms may avoid that area. After that, a quiet day before more storms fire up later Saturday afternoon ahead of and along the front. KMSP... Will bring in storms a little earlier than before, now about 06Z, and it could even wind up being 05Z. At this point it looks like storms will sweep across MSP, with potential for 40-50 knots or more. Then another round of storms developing after 22z. /OUTLOOK FOR KMSP/ Sunday...VFR. NW wind 10 to 15 kts. Monday...VFR. W wind 5 kts. Tuesday...MVFR possible. Chc TSRA. SE wind 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...Heat Advisory from 11 AM to 9 PM CDT Saturday for Chippewa-Dunn- Eau Claire-Pepin-Pierce-St. Croix. MN...Excessive Heat Warning from 11 AM to 9 PM CDT Saturday for Blue Earth-Brown-Carver-Dakota-Hennepin-Le Sueur-Martin-McLeod- Nicollet-Ramsey-Redwood-Renville-Rice-Scott-Sibley-Waseca- Watonwan. Heat Advisory from 11 AM to 9 PM CDT Saturday for Anoka-Chippewa- Chisago-Faribault-Freeborn-Goodhue-Isanti-Kandiyohi-Lac Qui Parle-Meeker-Sherburne-Steele-Washington-Wright-Yellow Medicine. && $$ UPDATE...TDK SHORT TERM... LONG TERM... AVIATION...TDK
National Weather Service Morristown TN
913 PM EDT Fri Jul 17 2020 .UPDATE... EVENING UPDATE. && .DISCUSSION... Isolated to widely scattered showers and thunderstorms early this evening with the greatest coverage over northeast Tennessee. Airmass will slowly stabilize with loss of daytime heating. Isolated storms will be possible through around midnight, otherwise, patchy fog is expected again early Saturday morning. Made some minor adjustments to hourly temperatures. Have a great night. && .AVIATION... 00Z TAF DISCUSSION. Isolated showers and thunderstorms are developing near/over the TAF sites early this evening. With the loss of daytime heating these storms will dissipate soon after sunset. For Tonight, MVFR fog is possible at TRI between 08-13Z with potential of IFR ceilings due to low cloud development. Otherwise, VFR conditions anticipated. For Saturday, widely scattered afternoon/evening storms are expected generally after 18Z. Outside of storms, ridging will keep winds light and less than 10kts throughout the forecast. && .PREV DISCUSSION... /ISSUED 258 PM EDT Fri Jul 17 2020/ SHORT TERM (This Afternoon through Saturday)... Most locations as of 2 pm are already in the low to mid 90s with heat indices around 100 degrees for a good portion of the southern Tennessee Valley. Seeing these higher heat indices due to the elevated surface dewpoints in the upper 60s to low 70s for most locations. These warm temperatures are from the ridge aloft with 500 mb heights in the 594-596 dm range. Current water vapor imagery and RAP upper air analysis does indicate a weak shortwave trough to the north across KY/IN/OH. At the surface, there is a E-W stalled frontal boundary across KY. This boundary is more of a wind shift with little to no difference in surface temperature or dewpoint along the boundary. Convection has develop along this boundary this afternoon. Satellite imagery indicates convective initiation from KY to the west into N AR and MO. Water vapor imagery depicts dry air in the mid-levels across the forecast area. Mid-level lapse rates are weak with high heights and warm air aloft. Could see some minor heights falls later this afternoon and evening with the shortwave from KY but these will not be that impressive. Overall, expect the best chances for showers and storms will be for locations north of I- 40 and in the higher elevations. These locations will have slightly better convergence and some very weak synoptic lift. SBCAPE values will range from around 500-1500 J/Kg with 0-6 km deep layer shear of less than 10 kts. Therefore, do not expect any strong to severe storms. Expect any ongoing convection will come to an end near sunset with the loss of daytime heating. There could be some areas of patchy fog near sunrise, especially for areas that experience rainfall later this afternoon and evening. The upper level ridge will be centered over the Tennessee River Valley on Saturday. Temperatures are forecast to be a degree or two warmer than today with most locations climbing into the low to mid 90s. Heat indices for the southern and central Tennessee Valley will range from 100-105 degrees. PW values will range from around 1.5-1.8 inches. These values are near the 75th percentile for mid- July. However, with the ridge overhead, there will not be any synoptic support but could see a few isolated to scattered afternoon showers/storms with best chances across the higher elevations. Again, not expect any strong or severe storms with warm temperatures aloft and weak mid-level lapse rates. The main concern in the short- term forecast period will be the continued heat. MA LONG TERM (Saturday Night through Friday)... Key Messages: 1. Very hot and humid through early next week with only isolated afternoon/evening thunderstorms. 2. Slightly cooler mid to late week with greater coverage of thunderstorms. Discussion: Saturday night through Monday Night... Generally quiet weather is expected this period with very hot and humid conditions as an elongated mid/upper ridge stretches from the 4 corners through the SE CONUS with 592-595 H5 heights centered over the TN Valley and southern Appalachians. A large Bermuda surface high will maintain southerly low-level flow under the mid/upper ridge continuing to pump high Td air into the region. This low-level moisture combined with strong boundary layer heating each afternoon will yield 2000-2500 J/Kg MLCAPE, but mid level capping from the ridge overhead should keep diurnal convection isolated to higher elevations. Used chance PoPs over the plateau and eastern mountains Sunday and Monday afternoons with slight chance in the valley. Convection will quickly wane after sunset. Went slightly above NBM guidance due to the antecedent dry soils with highs in the mid/upper 90`s S and low/mid 90`s N, which will give heat indices near advisory criteria (105) over the S Plateau and S/central valley. Tuesday and Tuesday Night... Heights slowly begin to fall during this period as a mid/upper shortwave trough moves across the upper Midwest into the Great Lakes causing some suppression of the S CONUS ridge. This will cause a quasi-stationary front in the lower Great Lakes to begin to slowly push southward. This front will be active with convection as ripples of energy in the zonal flow traverse the boundary. Virtually all of the forcing is N of our region during this time, but moisture beginning to pool ahead of the boundary, continued southerly flow, strong diurnal heating, and possible outflow boundaries reaching the region will allow for better coverage of afternoon/evening convection. The highest coverage will continue to be in the plateau and eastern mountains where chance to likely PoPs were utilized with chance elsewhere. The increased convection will temper highs slightly with low/mid 90`s S and generally low 90`s N. Given the high Td`s, heat indices will still approach 105 in the S Plateau and S valley. The convection will again dissipate after sunset with just slight chance PoPs retained in the mountains. Wednesday through Friday... This period will finally see a bit of a pattern change as the aforementioned shortwave energy carves out a broad but fairly shallow trough over the NE U.S, at least temporarily. This will push the frontal boundary southward while stalling in the vicinity of the lower OH valley. The lower heights above a continued moist and unstable boundary layer, along with the surface front just to our N, will allow for fairly widespread convection each afternoon, so have chance to likely PoPs with the highest over the higher elevations. Of these three days, I have the greatest coverage Thursday since the deterministic GFS suggests that the front could push through the S Appalachians, however, the GEFS, CMCE, and EPS ensemble means and the deterministic ECMWF have a shallower trough keeping the boundary just N. Nevertheless, there is an increasingly strong signal that this front will begin to retreat back N Friday as southern CONUS ridging rebuilds ahead of renewed western CONUS troughing. Highs will be cooler Wed through Fri with upper 80`s/low 90`s. RG && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 75 97 75 97 75 / 20 20 10 20 10 Knoxville McGhee Tyson Airport, TN 73 95 74 96 73 / 20 30 10 20 10 Oak Ridge, TN 73 96 73 96 73 / 20 30 10 20 10 Tri Cities Airport, TN 69 91 70 93 70 / 20 50 10 30 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$
Area Forecast Discussion
National Weather Service Riverton WY
532 PM MDT Fri Jul 17 2020 .SHORT TERM...This evening through Saturday night Issued at 250 PM MDT Fri Jul 17 2020 19Z radar, satellite and HRRR output indicates that a weak short wave was moving east-southeast through southern Wyoming, with widely scattered showers/storms developing across mainly Sweetwater county. Expect precip to continue to develop to the northeast toward Natrona county, weaken and dissipate by around 00Z this evening. Due to the pressure gradient between the mid level ridge and short wave, winds have picked up at most locations and will continue with red flag warnings that will remain in effect for much of central Wyoming until 02Z tonight. The short term models continue to indicate that a weak frontal boundary will shift southeast into the forecast area after 06Z tonight. This system will filter in some slightly cooler air especially into northern and into central sections by 12Z Saturday. RH values will be slightly higher on Saturday across the area, but still expect enough potential for critical values to be met across portions of central Wyoming. Borderline red flag fire weather conditions will be prevalent in Fremont county and will likely need to update for Saturday by this evening. Dry conditions will continue through Saturday night with temps expected to fall about five degrees cooler by Sunday morning. .LONG TERM...Sunday through Friday Issued at 250 PM MDT Fri Jul 17 2020 Sunday will see another shortwave transit the more zonal flow with convection possible mainly for the Bighorns and Johnson County, and maybe into Natrona County. That will repeat on Monday and again Tuesday, although with less coverage of showers each day. The zonal flow will continue through mid week with the models all indicating transitory shortwaves, mainly across the north, dropping across eastern portions of the forecast area. Wednesday through Friday the models are showing increased mid and high level moisture, however, they are not in very good agreement on the timing or amplitude of these waves. We will keep PoPs on the lower side. Temperatures are not going to fluctuate much from day to day through the long term, with humidity also hitting at low levels. && .AVIATION...For the 00Z TAFS through 00Z Sunday A line of showers and thunderstorms near KJAC will gradually end by 02Z. Additional virga showers along the Sweetwater/Fremont County line will end by this time as well. Otherwise, VFR conditions will continue across the area through the end of the forecast period. A cold front will make its way through northern Wyoming after 06Z tonight and into central Wyoming by around 12Z Saturday. Winds will increase again after 15Z Saturday for most areas. Conditions will remain dry across the area Saturday. && .FIRE WEATHER... Issued at 250 PM MDT Fri Jul 17 2020 A weak cold front will move south into the region by Saturday morning, with a gusty north to northwest breeze expected in portions of central and southern Wyoming. This, combined with low humidity will continue to bring elevated to critical fire weather to portions of central and into southern Wyoming. Mixing and smoke dispersal will be generally good to excellent. Otherwise, fire weather concerns should ease on Saturday following the cold front passage with somewhat cooler temperatures and higher humidity. && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 8 PM MDT this evening for WYZ280-281-285- 288-289-300. Red Flag Warning until 8 PM MDT Saturday for WYZ283. && $$ SHORT TERM...Troutman LONG TERM...Swanson AVIATION...Troutman/LaVoie FIRE WEATHER...Troutman