Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/25/20

Area Forecast Discussion
National Weather Service Cheyenne WY
556 PM MDT Fri Apr 24 2020 .SHORT TERM...(This evening through Saturday) Issued at 311 PM MDT Fri Apr 24 2020 Weather Impact Summary: Ongoing scattered showers and isolated thunderstorms are occurring across High Plains of SE WY and NE Panhandle. Some of the deeper showers and thunderstorms have produced pea-sized hail and wind gusts of 40 mph. These stronger isolated showers will continue through about 8pm and decrease in coverage and intensity thereafter. Weather Details: MLCAPE values near 300-600 J/KG and steep mid- level lapse rates under embedded weak H7-H3 vorticity impulses is supporting scattered to numerous shower and isolated thunderstorm activity this afternoon. Instability will wane through the early evening hours and overall coverage will slowly decrease through the evening and overnight. Some light residual precipitation could linger across the higher terrain through early Saturday morning due to weak orographics but amounts will be light and no impacts are expected. For Saturday - slightly stronger ridging and warmer H7 temperatures will shift east across WY and NE. While some very isolated showers will be possible along the southern Laramie Mountains and foothills, much less coverage is expected tomorrow vs. today given lower instability and slightly increased subsidence. Saturday will start the warming trend into the back half of the weekend and into next week. .LONG TERM...(Sunday night through Thursday) Issued at 300 AM MDT Fri Apr 24 2020 Long range models for next week continue to show a warmer and more pleasant weather pattern across the Front Range with low chances for precipitation until the end of the week. Northwest flow aloft this weekend will become more westerly on Monday as a Pacific disturbance aloft rapidly moves eastward embedded in the westerly flow. Outside of some showers or thundershowers Monday and Monday night, this system will have little impact over southeast Wyoming and western Nebraska. All models then show a high amplitude upper level ridge axis developing over the western third of the United States by midweek, allowing 700mb temperatures to increase between 5c to 12c. Expect daytime temperatures in the 70s for most of the week with a brief cool down on Tuesday. Highs on Thursday may even reach the low to mid 80s for the eastern plains, east of the Laramie Range, as the upper level ridge axis nudges east of Front Range during the day. Past Thursday, noting an increase in llvl instability and a greater potential for afternoon/evening showers and thunderstorms under southwest flow aloft later in the week. Started increasing POP next Friday with models in pretty good agreement. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 553 PM MDT Fri Apr 24 2020 Showers and isolated weak/brief thunderstorms coming down the northwesterly flow will gradually diminish through 03Z. Still some potential (especially over the Nebraska Panhandle) of getting a gust to near 40 kts out of some of this activity judging from the boundary layer profiles, but chances of anything stronger right now look to remain low. IC and CC lightning activity also dropping gradually as well where currently noted in far eastern Wyoming and the western Panhandle. Looks like a similar pattern tomorrow, but as the HRRR and the NAM-Nest suggests less coverage with midlevel temperatures warming up a bit as ridging works in from the west. So, resultant forecast keeps all TAF locations in VFR through the next 24 hours with the exception of Laramie where we may get some fog and lower ceilings down to MVFR toward morning. && .FIRE WEATHER... Issued at 311 PM MDT Fri Apr 24 2020 No fire weather concerns today and next several days with non-critical winds and humidity levels. Precipitation today will wane this evening with a drier and warmer weekend ahead. Will need to keep watch of next Tuesday and Wednesday for critical relative humidity levels but winds should remain below 20-25 mph. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...JSA LONG TERM...TJT AVIATION...Garmon FIRE WEATHER...JSA
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1108 PM EDT Fri Apr 24 2020 .AVIATION... High pressure with dry northerly flow has largely scattered out low clouds tonight with VFR conditions expected to prevail through this morning and afternoon. There will be some mid to high cloud streaming over the region associated with various waves moving across the plains and into the Midwest. Strengthening low pressure system to our south will lift into the Ohio Valley bringing a low chance for light rain showers during the afternoon for the southern terminals. Will leave mention of showers out for now due to the amount of low level dry air that is maintained across the area in the lowest 5kft that may result in mostly virga. The best chance at any rain showers will likely come in the evening with the closer approach of the low pressure system and again confined to the southern terminals, which still may hold to the south. Prolonged period of N-NE winds will continue with a gradual increase in gust potential resulting from the tightening pressure gradient during the evening as well. DTW THRESHOLD PROBABILITIES... * Low for ceiling below 5000 feet through this morning. && .PREV DISCUSSION... Issued at 343 PM EDT Fri Apr 24 2020 DISCUSSION... Residual low level stability that developed from low level cold advection in recent days has been perpetuated over Southeast Michigan today with cold stable flow off of Lake Huron. Not much synoptic scale forcing for surface anticyclone exists at this time with upper level confluence having pushed eastward and straight neutral flow trajectories through the lowest 10 kft agl. This is not totally trivial as the cloud trends today have been a function of the amount of lower tropospheric stability with trapped moisture below inversion. The 24.12Z KDTX RAOB was a tell this morning with high RH below 9.0 kft agl and deep saturation from the surface through 2.5 kft agl. Surprising then to see the amount of clearing that developed midday. The relatively dry RAP based soundings support a cumulus response this afternoon with daytime heating and increased insolation. Combination of high cloud and afternoon cumulus on satellite holding firm with the sky fraction this afternoon. An extremely busy 500mb vorticity chart is in place over much of North America. Suppressed geopotential heights exist over the southern 1/2 of the contiguous United States with zonal flow throughout much of the northern half of North America. What this has led to is a weekend forecast period that has been difficult to forecast for. The low predictability has arisen from the multitude of shortwaves "advecting" through the flow and the models difficulty in handling the phasing/separation of the shortwaves. As for the sensible weather forecast for Southeast Michigan this weekend there are a couple of features to key off of. The first is the secondary jet streak set to develop directly overhead of Southeast Michigan tonight. Recent model trends suggest that right entrance region dynamics and associated frontogenetic/inverted trough response is now farther to the south and southwest. The result of this is a less progressive solution in lifting midlevel fgen into the cwa during the day Saturday. The second item to key off of is the stout, organized dry air feed that will remain directed at the area. Survey of model soundings show less saturation and moisture in the lowest 10 kft agl, especially in the NAM soundings. For this issuance, decided to go with broadbrush chance PoPs to account for midlevel fgen, and likely virga activity south of I 69 late Saturday afternoon Model consensus exists that keeps northern sharp edge to deformation forcing mainly south of Southeast Michigan Saturday night and Sunday. NWP is showing a good signal for enhanced AVA dipole and assoicated deep subsidence settling across Southeast Michigan. Surface ridging is expected again with cold stable flow off of Lake Huron which will result in relatively decent day. Questions still exist on the amount of high cloud that will persist over the area, but all in all a decent Spring days expected both Sunday and Monday. The next chance for precipitation will come Monday night and Tuesday as warm advection ramps up across the area. Difficult to project coverage of precipitation at this time as area will largely be under the influence of very strong anticyclonic flow. MARINE... Winds will gradually diminish this evening across the central Great Lakes given an increasingly diffuse pressure field and stable nocturnal low-levels. Dry conditions persist through the night with rain chances steadily rising on Saturday as a plume of moisture associated with a strengthening low pressure system lifts into the lower Ohio Valley. Flow will hold in the northeast quadrant for most of Saturday with speeds AOB 15 knots. Stronger winds are expected late Saturday night and Sunday as the northwest corner of the tighter pressure gradient clips the southern waterways as the low tracks northeast. This will likely lead to a period of 25-30 knot gusts and higher wave action until late Sunday night. Dry weather Sunday afternoon will then continue through Monday night as high pressure west of Lake Michigan briefly takes control. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....AA DISCUSSION...CB MARINE.......KK You can obtain your latest National Weather Service forecasts online at
National Weather Service Jackson KY
815 PM EDT Fri Apr 24 2020 .UPDATE... Issued at 755 PM EDT FRI APR 24 2020 Hourly grids were updated based on recent observations and satellite and model trends. Cumulus and stratocu linger across the region with some cirrus passing overhead as well and sky cover was increased a bit over the next couple of hours. Overall, no substantial changes were needed at this time. && .SHORT TERM...(This evening through Saturday night) Issued at 430 PM EDT FRI APR 24 2020 Late this afternoon, an upper level trough is nearing the mid Atlantic coast and continues to depart to the northeast. A pattern of a broad trough from the central to eastern Conus is in place with this trough being downstream of a ridge the axis of which is near the west coast of the Conus. Also moving within the upper level trough was a shortwave over the Plains. At the surface, an area of low pressure was centered over eastern OK with a warm front extending into the Gulf of Mexico and a cold front trailing into central TX. Locally weak high pressure between a departing system and the system to the southwest was building into the area. Low level moisture lingers with some breaks in the cumulus and stratocumulus. A few sprinkles were still occurring from Pike County southwest to Harlan County. This evening and tonight, some further clearing is expected and window of mostly clear skies may be experienced across portions of the area by late evening into the start of the overnight. As the low level flow becomes northeast to east the clearing may slow in the Big Sandy region or clouds might advect back in. Winds are expected to slacken overnight and where skies can clear fog may form in valleys considering the recent wet weather. Patchy fog or even areas of valley fog were used to cover this. Clouds will increase later tonight as the next system approaches and this may tend to lead to the valley fog dissipating toward sunrise. Valley locations should experience lows in the mid 40s with upper 40s expected elsewhere. Clouds will thicken and lower further on Saturday as the low pressure system and upper level trough move from the mid MS Valley into the lower OH Valley. Models are rather consistent with isentropic lift/warm advection leading to one or more bands of showers or an area of showers that moves across the southern portions of the area late in the morning to midday and then into the central and northern portions of the area from midday through the afternoon. Behind the initial isentropic lift/warm air advection band of showers, instability will increase as mid level lapse rates approach or possibly exceed 7C/km near peak solar insolation as the low tracks into central KY. Bulk layer shear of 30 to 40KT is forecast in the models with MUCAPE of about 1000 to 1500 J/KG in the west and south. This could set the stage for a couple of clusters or discrete cells that could exhibit some updraft rotation and produce hail, gusty winds, and or brief heavy rain. HREF probabilities point toward locations near the TN border over to the KY/TN/VA tri state area having the greatest chance for a stronger storm or two. Convective allowing models from 18Z such as the NAMMEST and HRRR have a few updraft helicity swaths extending into mainly the southern counties. The 12Z HREF UH probs are generally greatest near the TN border. If enough instability is realized, an isolated severe thunderstorm or two may occur late in the afternoon or early in the evening. The surface low should move slowly to the mid OH Valley through around dawn on Sunday with the upper level trough axis moving into the area on Saturday night. Even after the threat for thunderstorms diminishes with lessing instability on Saturday evening, cooling aloft will lead to the continued threat of rain showers for Saturday night. Another wetting and soaking rain is expected with this system. Around a half of an inch of rain is expected from Saturday into Saturday night with additional showers early in the long term period on Sunday. .LONG TERM...(Sunday through Friday) Issued at 240 PM EDT FRI APR 24 2020 The period begins with vertically stacked low pushing northeast of Kentucky. We will see wrap around moisture leading to rain on Sunday especially in northeast Kentucky, as this system departs to the east. The guidance continues to lean toward dry weather returning Monday, as high pressure and shortwave upper level ridging briefly build in from the west. Another more amplified wave progresses toward the area bringing another shot of rain beginning Tuesday night, and the chances of rain will go into Thursday as closed upper low pushes across the Ohio Valley. The peak chances for showers and some thunderstorms will be Wednesday, as a cold front is set to cross the Bluegrass State. This could lead to a few strong storms under a strongly sheared environment, but the MUCAPE looks more marginal right now. However, the steeping mid level lapse rates may be able to help the marginal CAPE. The timing of the front may also be a bit quick for better building of instability. The GEFS CIPS analog does have a signal in the area, but plenty enough uncertainty to leave any mention out of the HWO for now. Finally this amplified system will slowly push across the Ohio Valley and this will keep cool rain going through Thursday into Thursday night. Then yet another surface high pressure and more amplified upper level ridge will push toward the Ohio Valley Friday, but some left over isolated northwest flow showers remain possible before this builds into eastern Kentucky. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 800 PM EDT FRI APR 24 2020 Mostly VFR was observed across the region with some localized IFR or MVFR in the southeast portions of the area in the KSJS vicinity. Weak high pressure will cross the area tonight, with another low pressure system entering the OH Valley. Some stratocu redevelopment may occur in the Big Sandy region near KSJS and some deeper river valley fog generally not affecting the TAF sites. Otherwise, mid level clouds should increase, thicken and lower from southwest to northeast generally after 12Z with one or more bands of showers spreading across the area. Some brief MVFR is possible as these pass. Overall, mainly VFR is expected to remain until the end of the period at the TAF sites, but MVFR should move into the northwest near KSYM late. Isolated thunder is also possible after 18Z, but confidence and coverage is not great enough to include at this time. Winds will average northeast through 0Z at less than 10KT, before becoming light and variable. East southeast to southeast winds will increase between 12Z and 18Z into the 5 to 10KT range. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...JP LONG TERM...DJ AVIATION...JP
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
1045 PM CDT Fri Apr 24 2020 ...New AVIATION... .SHORT TERM... (This evening through Saturday) Issued at 236 PM CDT Fri Apr 24 2020 An upper trough currently across the Central High Plains will be digging into Oklahoma in the next few hours and through the evening hours, providing the upper support for storms to begin firing up soon across portions of northcentral into eastcentral Oklahoma. Meanwhile, a surface low will continue to be pushed across southern Oklahoma and into southeastern Oklahoma as the afternoon progresses, while this systems breezy cold front nearly along the I-44 corridor will continue to move through. So far, radar has been showing scattered light rain showers near the front across northcentral Oklahoma, with isolated storms just outside our CWA in Osage County. Expecting more convection to develop further southward along the surface boundary and become more linear in shape across portions of eastcentral Oklahoma. Latest HRRR seems to have a good handle on these storms, becoming more intense as develop across southeast Oklahoma. As the surface low settles into southeast Oklahoma, expecting the midlevel to cool and strongly destabilize, with MUCAPE values approaching 3000 J/kg. Conditions will be favorable for supercells to develop across portions of southeast Oklahoma late in the afternoon as the surface boundary starts to move in, with large hail and severe wind gusts as the main hazard. Expecting this system to move through our far eastern CWA and further into southeast Oklahoma by the evening hours. Being on the back side of the cold front, tonight should be dry and a little bit cooler and breezy as we tap into air originating from the Central High Plains. Saturday will be dry and mild with seasonably average temperatures. && .LONG TERM... (Saturday night through next Thursday) Issued at 146 PM CDT Fri Apr 24 2020 Models continue to show WNW or NW upper flow for the region for much of next week with a trough digging into the eastern U.S. with an upper low in the Great Lakes/Ohio Valley area. Models then show the upper ridge shifting east across the southern Plains late next week. Models also show a cold front moving across the area Tuesday. Disturbances moving through the WNW/NW flow could lead to off and on shower and thunderstorm chances. The most likely or consistent time frame for showers/storms has been Monday and Tuesday, especially on Tuesday with the front moving across the area. Enough instability could be around for some strong to severe storms to be possible. Near or above average temperatures are expected Sunday through next week. && .AVIATION... (06Z TAFS) Issued at 1023 PM CDT Fri Apr 24 2020 VFR conditions expected. Mainly light to moderate northerly winds will continue into tomorrow, with winds becoming light and variable by end of forecast period. LLWS will be included from KPNC down to KOKC/KOUN first part of forecast with strong northerly flow just off the deck due to strong cyclogenesis over Missouri. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 50 71 48 75 / 0 0 0 0 Hobart OK 47 73 47 78 / 0 0 0 0 Wichita Falls TX 49 75 48 80 / 0 0 0 0 Gage OK 44 71 45 79 / 0 0 0 0 Ponca City OK 49 70 44 75 / 0 0 0 0 Durant OK 52 73 50 77 / 0 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$ SHORT TERM...03 LONG TERM....68 AVIATION...11