Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/15/20

Area Forecast Discussion
National Weather Service Des Moines IA
300 PM CDT Fri Aug 14 2020 .DISCUSSION.../Tonight through Friday/ Issued at 256 PM CDT Fri Aug 14 2020 Summary... Primary forecast concerns will be over the next 6 to 12 hours with the potential for strong to severe storms, including damaging winds and hail as threats. More details in the sections below. The remainder of the forecast will remain on the quieter, a bit cooler, and much less humid side with northwest upper level flow prevailing and only periodic chances for a shower/storm or two. Today through Tonight... Mid and upper level troughing continues to work its way across the Dakotas and into Minnesota this afternoon, including a surface low reflection sliding NE currently positioned in the ND/SD/MN tri-state border region, yielding a surface cold front stretching back to the S/SW. Ahead of the cold front, a remnant elevated outflow/gravity wave continues to kick off scattered showers and the odd lightning strike or two, but being away from the bulk of the forcing and support will continue to predominantly struggle as it continues into western Iowa. Back along the approaching front, deep convection has begun to initiate in the Sioux City and will be the area to watch. Across the state, established southerly flow kept the region on the warm and humid side with temperatures in the mid 80s and dew points regularly into the low 70s. Ultimately, the question is whether or not we have enough support for severe storms late this afternoon and evening. Let`s take a look... With the warm and humid conditions established, and a degree of moisture pooling ahead of the front, MUCAPE values in excess of 4000 J/kg and MLCAPE values in excess of 2500 J/kg respectively have been established across W/NW IA by mid afternoon today. Generally, forcing will not be in question either with a potent cold front, attached to the parent surface low north of the region, that will traverse the state through the evening. Shear profiles are at least marginally supportive with effective shear depictions remaining in the 30-35 kt range. The better veering profiles reside north of the area, yielding environmental 0-3km SRH values around or less than 150 m2/s2, especially as you work south. Areas of steep lapse rates in excess of 8 deg C/km continue to suggest at least some large hail potential, especially should storms efficiently tap into available shear. Strong winds may also be seen with drier low-mid levels and DCAPE values in 1000 J/kg. Working against severe potential are depictions of convection ahead of the better/most supportive 0-3km and 0-6km shear profiles and shear vectors losing orthogonal position through the event. Additionally there are continued depictions of a stronger EML within HRRR family than originally anticipated by overnight and early morning synoptic and hi-res models, suggesting more of a broken line of convection versus traditional QLCS. Overall, anticipate broken line segments of convection to work their way across the state through the late afternoon and evening hours, with the best severe potential over the northwest third of the area, lining up well with existing SPC Day One Outlook. A few cells may be able to efficiently take advantage of the anticipated effective shear profiles and yield periods of severe hail and winds. Otherwise, expect majority of the activity to be sub- severe. As the convection and front work into central Iowa, waning instability will reduce the severe threat further, especially on the hail side, but stronger winds could continue into the evening. While severe threat into central and eastern Iowa will reduce through the evening, given the continuing recovery efforts from the Monday derecho, recovery crews and the public will want to keep an eye out on vulnerable trees, power poles, etc... as they may be susceptible to additional damage from sub-severe winds, let alone severe winds, given their already weakened nature. Saturday through Friday... Expected weather becomes much more comfortable, and predominantly quiet through the rest of the forecast. Why? A large 500mb high will develop over the SW US and result in amplified western CONUS ridging that will yield prevailing NW flow over the region. Other than periodic shortwaves yielding lower end shower/storm chances at times, a dry forecast will prevail much of the time. && .AVIATION.../For the 18Z TAFS through 18Z Saturday afternoon/ Issued at 1238 PM CDT Fri Aug 14 2020 Main concerns predominantly over the next 12 hours with potential for MVFR and brief IFR conditions due to TSRA opportunities at all sites. KFOD/KMCW/KALO most likely to see impacts, with more uncertainty at KDSM and KOTM with potential for storms to be more scattered in nature at the latter locations. With frontal passage, winds will quickly shift from S/SW to NW with gusts persisting to around 15-20 kts behind the front before subsiding towards the early morning hours. Once storms pass through concurrent with the front, remainder of TAFs will be VFR. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Curtis AVIATION...Curtis
Area Forecast Discussion
National Weather Service Green Bay WI
1028 PM CDT Fri Aug 14 2020 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Saturday Issued at 257 PM CDT Fri Aug 14 2020 The latest RAP analysis and satellite/radar imagery show low pressure over the eastern Dakotas and a cold front extending from the low southwest across the central Plains. Strong to severe convection continues ahead of the low over northern Minnesota, though has been weakening over the past few hours. A much more stable airmass prevails across the eastern half of Wisconsin, as evident by little in the way of cu formation. As the front slides across the region tonight, forecast concerns mainly revolve around thunderstorm potential. Tonight...The cold front will continue to march east and move into central and north-central WI after midnight. Widespread thunderstorms are expected to develop along the front this afternoon before they push into western Wisconsin this evening. With diminishing instability and upper level forcing lifting off to the northeast, the short range models continue to show convection diminishing as it approaches north-central to central WI shortly after midnight. Still though, most unstable capes up to 1000 j/kg could lead to an isolated strong storm persisting into north-central WI. Probably the most significant threat would be heavy rainfall. Convection should continue to diminish along the front into northeast WI by 12z. A widespread low overcast deck will likely move into the area behind the front. Even though winds will shift to the northwest, the clouds should keep temps mild. Lows ranging from the upper 50s to middle 60s. Saturday...The front will continue to move east over northeast Wisconsin in the morning before exiting by midday or early afternoon. Some guidance indicates that a few strong cells could develop late in the morning along the lakeshore areas before the front departs. Not sure if there will be enough time to destabilize in the morning, especially since cloud cover should be plentiful. Will show a slight uptick in precip chances, but the unfavorable timing will keep any severe threat as very low. With partial clearing in the afternoon, temps to warm into the middle 70s to near 80, which is about 5 degrees cooler than today. .LONG TERM...Saturday Night Through Friday Issued at 257 PM CDT Fri Aug 14 2020 Looks like a seasonable weather pattern setting up for next week with a western ridge and eastern trough producing a northwest upper flow across the Great Lakes. This should result in pleasant summer weather with a few days slightly cooler than normal and a couple days a little above normal by the end of next week. There could be a shower or thunderstorm during the middle of the week as a shortwave moves through the upper flow. The models forecast the upper flow to flatten out towards the end of the work week, with a chance of showers or thunderstorms ahead of another cold front. && .AVIATION...for 06Z TAF Issuance Issued at 1025 PM CDT Fri Aug 14 2020 A cold front continues to slowly approach from the west. The front will bring an increase and lowering of the clouds as is pushes into the area. Some convection will accompany the front into the area overnight, but it will be weakening. The likelihood of thunder occurring at the western TAF sites has increased, and timing is now clearer, so will include a TEMPO group for the thunder there. It looks less likely in the east, so will continue with just SHRA in the eastern TAF sites with the 06Z issuance. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......RDM AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Huntsville AL
942 PM CDT Fri Aug 14 2020 .NEAR TERM...(Rest of tonight) Issued at 942 PM CDT Fri Aug 14 2020 Warm upper level ridging remained over the Desert SW, while upper troughing was amplifying over eastern CONUS. A weak upper level low within the troughing over the IN/OH border had trough extending towards the Tennessee Valley. A vorticity maxima over western Tennessee featured an area of showers and thunderstorms, moving to the SE. This activity per the new NAM, along with hourly updates from the RAP and HRRR had it gradually dissipating as it nears the forecast area - with it generally gone after 2-3 AM. Given uncertainty with this convection, left rain chances as is for tonight. Will revisit this and raise rain chances for our NE areas if the storms and other newer guidance keeps it going. The rest of the forecast output looked okay for now. .SHORT TERM...(Saturday through Sunday night) Issued at 242 PM CDT Fri Aug 14 2020 Much of the central and western part of the forecast area may be completely dry on Saturday in the wake of the trough passage. Our eastern counties may experience a few more showers and thunderstorms, mainly through early afternoon. However, coverage should not be widespread. With afternoon mixing, dew points should lower below 70 degrees in many areas. The more noticeably airmass change will occur after a cold front drops southeast on Sunday. So, one more muggy day is expected just ahead of the front Sunday. Isolated thunderstorms are possible, but with a more limited deep moisture profile and generally weak QG forcing, will keep PoPs/coverage more limited. Will not rule out a strong storm or two, but this doesn`t appear to be a linear/widespread convective event. Noticeably drier air will arrive by Monday morning when lows should dip into the 60s areawide except near the larger lakes still retaining warmth. Went 1-2 degrees above suggested blends for highs Saturday and Sunday. .LONG TERM...(Monday through Thursday) Issued at 242 PM CDT Fri Aug 14 2020 General pattern of ridging over the western CONUS will lead to general troughiness over the eastern CONUS. This will lead to northwesterly flow bringing drier air into the Tennessee Valley through the first half of next week. This will limit the shower and thunderstorm potential, with mostly dry weather Monday and Tuesday. Both the GFS and ECMWF show a secondary wave developing, bringing a low pressure system down out of Oklahoma into the Mississippi River Delta region midweek. This will lift a warm front north and southerly flow will bring back moisture to the Tennessee Valley maybe as early as Wednesday, but more likely on Thursday. This will lead to increasing shower and thunderstorm chances again later next week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 637 PM CDT Fri Aug 14 2020 Broad weak surface low pressure over the region will slowly move eastward into Sat. Despite its presence, cooler conditions and a more stable environment should result in shower activity diminishing this evening. Late night stratus and/or fog formation is possible across the area in the predawn hours and on Sat. Stayed with low IFR CIGs at KHSV, and LIFR CIGS and MVFR fog at KMSL. Conditions should improve within a few hours of sunrise, with VFR condition expected thereafter. Light winds this evening and in the overnight, should become NW, increasing into the 5-10 kt range from the mid morning into the afternoon. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...17 LONG TERM...McCoy AVIATION...RSB For more information please visit our website at
National Weather Service Charleston WV
1150 PM EDT Fri Aug 14 2020 .SYNOPSIS... Heavy rain heading into Saturday with a slow moving disturbance. Another round of thunderstorms ahead of a cold front Sunday night. Drier for early next week. && .NEAR TERM /THROUGH SATURDAY/... As of 1145 PM Friday... Adjusted PoPs down with less coverage per latest radar imagery. Rainfall activity seems to diminish considerably, and seems like the RAP model have a good handle of the current situation. Coverage and intensity of showers and storms return by Saturday morning. Rest of forecast remains on track. As of 850 PM Friday... Based on latest discussion from WPC, which focuses on the possibility for increased activity overnight across parts of VA into WV due to enhanced convergence along a boundary along higher terrain counties and overrunning, elected to go ahead and expand the FFA into much of WV counties. Was generous in areal coverage due to the uncertainty in where heaviest rains may occur, and the fact that soils are primed from recent rainfall events. As of 630 PM Friday... Tweaked pop grids to add more coverage cross southeast Ohio zones and lowered hourly temperatures in rain cooled locations. Otherwise, forecast still looks to be on track. Many of the slow moving storms this evening have produced a good 2 inches or more of QPF in spots. Fortunately, most of this has hit in our drier areas. The flash flood watch will remain in effect across southern zones through at least late this evening, with the other watch progged to take effect late tonight across southeast Ohio and adjacent WV counties as low level forcing takes hold in vcnty of a surface low. Models seem to be struggling a bit with placement of heavier precipitation tonight, but some of the CAM`s seem to still be hitting the Ohio Valley region the hardest, so will leave the watch as is. Additional rounds of showers and storms will develop once again Saturday afternoon. As of 145 PM Friday... Clearing skies coupled with increasing influence from an approaching upper level disturbance will spawn scattered showers and thunderstorms again this afternoon and evening. The main threat with any slow moving storms developing afternoon will be locally heavy rain. Did elect to hoist a flash flood watch across our eastern Kentucky, southwest West Virgina and Southwest Virginia counties in collaboration with our neighbors for this early activity. While widespread issues are not expected, rainfall over the last few days has tempered flash flood guidance in these locations in a spotty fashion with isolated high water impacts possible under persistent cells producing 1 to 2 inch per hour rainfall rates. The larger concern will be potentially very heavy and persistent rainfall associated with a developing low level circulation forming in response to a weakly phased shared energy area at H250. While instability is not terribly impressive, synoptically forced, near tropical columns coupled with very slow storm motion with significant training potential may yield local rain accumulations in excess of 3 inches across portions of the Middle Ohio Valley early Saturday morning through early afternoon. While flash flood guidance in this area is generally on the higher end, thunderstorms yesterday along with potential additional showers and storms this afternoon will somewhat temper these values. Have issued another flash flood watch from late tonight through early Saturday afternoon for locations with the highest confidence of slow moving storms along the track of the low level circulation. This may eventually need to be expanded further east or south, but confidence levels in flooding impacts are lower with storm motions accelerating. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 228 PM Friday... While the majority of heavy precipitation should taper off Saturday night into Sunday as an upper level trough departs to the east of the area, some showers and perhaps a few embedded storms may linger into Sunday afternoon, particularly in the mountains. Otherwise, expecting highs on Sunday to be in the low to mid 80s across the lowlands and 60s to mid 70s in the higher elevations. By Sunday night, a line of showers and thunderstorms is expected to approach western portions of the CWA as a low pressure system across southern Ontario pushes a cold front across the Ohio Valley. While this activity should be weakening by the time it reaches our area due to decreasing instability late Sunday evening into the overnight hours, a few stronger storms may be able to move into portions of our southeast OH counties if enough instability can hang on by the time the front arrives. Regardless, any threat for stronger storms should be isolated at most Sunday night before precipitation fizzles out during the overnight hours as the better upper support will be north of the area. While Monday should be mainly dry as surface high pressure across the Upper Midwest builds into the area, upper troughing aloft may support a few showers and isolated storms in the mountains Monday afternoon and evening. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 228 PM Friday... Upper air pattern early next week features strong upper ridging across the Intermountain West and broad troughing across much of the Great Lakes and Ohio Valley. This pattern will support a WNW flow aloft across the region in the early to middle portions of the work week with embedded shortwaves triggering occasional chances for showers and storms through mid week. By the end of the week, there is some uncertainty in where an upper level closed low may develop with models for now placing this feature generally across the lower Mississippi Valley. Ahead of this feature, southwesterly flow is expected to be on the increase and may reach into our area depending on the placement of the upper low, so for now have used a consensus blend of PoPs in the forecast through the end of the period until better model agreement occurs as precipitation chances could increase by late week. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... As of 730 PM Friday... Showers, along with isolated thunderstorms will continue through at least 03Z when a decrease in activity will be noted. However, post rain fog and stratus is expected, with widespread MVFR and areas of IFR or worse conditions expected to develop, particularly after 06-09Z. Focus then shifts to the potential for a period of heavy rainfall and embedded thunderstorms across much of southeast Ohio and WV counties closer to the Ohio River, generally in the 06-15Z time period. Expect areas of LIFR or worse conditions in this rainfall. Some improvement expected after 15Z across the area, however, widespread MVFR, and possibly local IFR conditions will continue to linger for much of the remainder of the TAF period. Showers and thunderstorms will redevelop again, mainly after 18Z, and mainly south of the Ohio River. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing, duration, and extent showers and storms may vary from forecast. Extent of post rain fog and or stratus overnight tonight may vary from forecast. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SAT 08/15/20 UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 EDT 1HRLY 23 00 01 02 03 04 05 06 07 08 09 10 CRW CONSISTENCY M H M L L L L L M H M H HTS CONSISTENCY H H H H L H H H H M M H BKW CONSISTENCY M M H H M M L L L M M M EKN CONSISTENCY H H H H L M L L L M L H PKB CONSISTENCY H H H H H H H M H H H M CKB CONSISTENCY H H H H H H H H M M L H AFTER 06Z SUNDAY... Rounds of showers and thunderstorms possible Saturday evening and night with additional brief IFR restrictions. Areas of IFR fog possible Monday and Tuesday mornings. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flash Flood Watch through Saturday afternoon for WVZ006>011- 014>020-027>032-039-040-517>526. Flash Flood Watch until 2 AM EDT Saturday for WVZ005-013. OH...Flash Flood Watch through Saturday afternoon for OHZ067-075- 076-083>087. KY...Flash Flood Watch through Saturday afternoon for KYZ101. Flash Flood Watch until 2 AM EDT Saturday for KYZ102-103-105. VA...None. && $$ SYNOPSIS...JP/RG NEAR TERM...ARJ/JP/SL SHORT TERM...RG LONG TERM...RG AVIATION...SL
Area Forecast Discussion
National Weather Service Las Vegas NV
819 PM PDT Fri Aug 14 2020 .SYNOPSIS...Excessive heat lasting through the weekend, and through the bulk of next week due to a pungent ridge of high pressure. Isolated, dry afternoon thunderstorms possible over the southern Sierra as well as the higher elevations of south-central Nevada and northwest Arizona. Otherwise, clear skies with light afternoon breezes prevail. && .UPDATE...The isolated thunderstorms that formed from the Morongo Basin, northwest across the western Mojave Desert then north up the southern Sierra already dissipated leaving behind an orphaned anvil here and there. monitoring wildfires via satellite showed that the Lake Fire is burning the hottest. Vertically integrated smoke product from the HRRR indicates smoke/haze spreading out across across parts of Inyo, southern Nye, Clark and San Bernardino Counties tonight. Updated to adjust POPs/Weather grids the rest of tonight, otherwise no changes. && .DISCUSSION...Today through Thursday. The heat is here. That said, there aren`t many changes to the forecast to highlight. We have an Excessive Heat Warning now in effect for much of the region including southern Nevada, southeastern California and northwestern Arizona through Wednesday night. In addition, we have a Heat Advisory now in effect for the Spring Mountains and Sheep Range of Clark County through Wednesday night. What is the difference? Why are there two different heat-related headlines? We want to emphasize something... It`s going to be hot - even by Desert Southwest standards. We`re expecting record-breaking temperatures for mid- August this week as we ramp up for an incredibly climatologically abnormal heat event. Though we`re relatively accustomed to heatwaves here and there, the distinction is that those typically range from 2 to 4 days in length. The heatwave for which we`re currently gearing up is looking like a week-long affair. That said, the inclination is going to be to head up to the mountains or other regions of higher terrain. Though, sure, temperatures will be "cooler" than the valleys, their temperatures are still forecast to be well-above their seasonal normals, providing little relief. For this reason, we hoisted a Heat Advisory for the Clark County mountains. In addition to the higher terrain not cooling down, neither will the overnight/morning low temperatures, which are also expected to be record-breaking. The unfortunate result of having nearly a week of excessively hot temperatures with little-to-no elevation nor diurnal (nighttime)-derived cool downs will be a stark increase in heat- related illnesses, or worse, if precautions are not taken. We strongly urge you to limit time spent outdoors. If this can`t be done, take frequent breaks in the shade or in the A/C, hydrate frequently, and wear light-colored, loose-fitting clothing. Heat is the #1 weather-related killer. Let`s, as a community, team together to beat the heat. What does this look like? Check on family, friends, and neighbors who fit into sensitive population categories such as the elderly, sick, or children. Urge the homeless to seek out or help point them to cooling shelters. Leave items essential to your trip in the back seat such as a purse, wallet or cell phone to remind yourself to never leave a child or pet in a vehicle unattended. Without A/C, vehicles can reach fatal temperatures. Remind or let those know who may be without internet or cable that temperatures this week will be dangerous. Other than the heat, today through the weekend may be accompanied by smokey skies for some, most notably in San Bernardino and southern Clark counties due to fires in southern California as well as the Baja including the Lake Fire and Ranch2 Fire. Populated the forecast using HRRR Smoke. Additionally, isolated convection is possible today over the Sierra Mountains as well as the higher terrain of south-central Nevada and northwestern Arizona. This convection will likely take the form of dry thunderstorms, with primary impacts being associated winds and potential fire starts. As mentioned in the previous briefing, this persistent, strong ridge of high pressure will greatly limit instability potential. However, the ECMWF Ensemble and GEFS members continue to allude to upper-level moisture getting trapped under this ridge. Coupled with modest instability from daytime heating, this could be enough for daily, isolated dry thunderstorms in the higher terrain through the week. && .CLIMATE... DAILY RECORD HIGH MAXIMUM TEMPERATURES TDY 8/14 SAT 8/15 SUN 8/16 MON 8/17 Las Vegas, NV 111 (2016)* 111 (2002)* 113 (1939)* 111 (1939)* Bishop, CA 106 (2002) 105 (2002)* 106 (1994)* 106 (2015)* Barstow, CA 112 (2002)* 112 (2002)* 114 (1994)* 111 (2015)* Needles, CA 117 (2012)* 118 (2019)* 118 (2015)* 117 (1892)* Kingman, AZ 109 (1933) 106 (1933)* 110 (1933)* 106 (2001)* Death Valley 124 (2002) 124 (2002)* 125 (1994)* 124 (2001)* DAILY RECORD HIGH MINIMUM TEMPERATURES SAT 8/15 SUN 8/16 MON 8/17 TUE 8/18 Las Vegas, NV 86 (2016)* 88 (2008)* 89 (2015)* 86 (2018)* Bishop, CA 65 (1958) 67 (1992) 65 (1992)* 67 (1970) Barstow, CA 83 (1996)* 81 (1994)* 82 (2012)* 80 (2001)* Needles, CA 92 (1962)* 93 (1892)* 94 (1903) 91 (2018)* Kingman, AZ 78 (1972)* 77 (1917)* 81 (1903)* 80 (2001) Death Valley 97 (2008)* 98 (2008)* 99 (2013)* 98 (2013)* *-Current forecast may be close to current record values. && .AVIATION...For McCarran...Light and variable winds continue this afternoon. A brief period of gusts to 15-18 kts out of the southwest is possible this afternoon but confidence is low at the terminal. After sunset winds will be generally light and variable with a general favoring from the southwest overnight. Light, diurnal trends expected tomorrow with VFR cloud cover expected to clear out through the afternoon. For the rest of southern Nevada, northwest Arizona and southeast California...For the Las Vegas Valley sites, gusty west- southwesterly winds will pick up this afternoon, with speeds 8-12 kts expected and gusts to 20 kts possible. KBIH could experience southerly wind gusts to 20 kts as well this afternoon, with gusts areawide dying down after sunset. Elsewhere, diurnal trends with speeds generally below 10 kts expected through the forecast period. Cloud cover will continue to clear out this afternoon, with no operationally significant cloud cover expected through the TAF period. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Pierce DISCUSSION/AVIATION...Varian For more forecast information...see us on our webpage: or follow us on Facebook and Twitter