####018005338#### FXUS65 KCYS 162041 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 241 PM MDT Fri May 16 2025 .KEY MESSAGES... - Seasonable temperatures into this weekend with isolated thunderstorms returning on Saturday. - Active weather pattern late this weekend and possibly early next week as another Pacific storm system impacts the region. There is a chance for strong to severe thunderstorms on Sunday across the eastern plains. - Drier weather with a slow warming trend for mid to late next week. && .SHORT TERM /THROUGH SATURDAY/... Issued at 237 PM MDT Fri May 16 2025 Afternoon visible satellite reveals a broad deck of flat cumulus cloud cover over much of the CWA as transient ridging and cool air aloft continue over the CWA. This cloud cover has kept afternoon high temperatures somewhat cooler than expected by a few degrees. Gusty northwest flow also remains in place along the backside of the departing low pressure to the east, with some obs sites along and east of the Laramie Range reporting wind gusts upwards of 45 mph. As this low pressure center continues to pull away and daytime heating and surface mixing is lost, winds will diminish overnight and a majority of the convective-based cloud cover will dissipate. Expect another cool overnight with lows generally at or slightly below average for mid-May. On Saturday the transient ridge will slide east into the high plains as a deep trough dives into the Great Basin/Four Corners region. While heights aloft will continue to rise a bit through the day, surface flow will quickly change to southeasterly upslope throughout the afternoon with typical terrain-based convergence patterns setting up. With a bit of mid-level moisture increases noted after 21z and strong daytime heating, a few very high-based convective showers and possibly some thunder are possible along and east of the Laramie Range, despite surface dewpoints generally progged to only reach the upper 30s by late afternoon. Farther west, some additional showers and weak thunderstorms will likely form off of the higher terrain of the Sierra Madre and Snowy Ranges. Later in the evening/overnight period, there is some concern for low stratus/fog in the NE panhandle and Southeast Wyoming as deeper moist upslope flow returns ahead of the trough. Forecast confidence remains high throughout the short-term with minimal adjustments made to forecast grids. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 237 PM MDT Fri May 16 2025 Sunday begins with low pressure at the surface in the Central/Southern Plains and a secondary system moving into the Wyoming area while at the upper levels a stout Pacific trough will progress towards the Plains and split off into a closed low. Once again the environment will be mostly marginal for severe activity, but a modestly unstable environment including MUCAPE anywhere between 750-1500 J/kg alongside Effective Shear values of 20-40 knots should be enough to fuel stronger thunderstorm activity, primarily impacting the southeastern corner of Wyoming and the southern and central Panhandle of Nebraska. Some stout capping and CIN will need to be overcome however, precluding a stronger threat for severe activity, but any storms that can get going will have the potential for all severe hazards with the strongest risk in Cheyenne County, NE. Plentiful moisture alongside this expected activity could also bring widespread wetting rains, with 0.5-1.5 inches possible from I-25 eastwards, but amounts could be locally heavier or lighter depending on where the strongest storms form and how the evolve. Moving ahead to the start of the week, on the backside of this system another day of precipitation for most of the region is likely but this time only rain and some mountain snow is likely, with amounts around 0.2-0.75 inch expected from the days precipitation. Some light precipitation may linger into Tuesday as this system slowly evolves eastwards across the Mississippi River Valley, but by the middle of the week a flat ridging pattern should evolve, allowing us to warm back into the 70s by Thursday. An isolated shower or storm daily may occur from some weaker embedded systems progressing through the region, but analysis of the ensemble clusters shows that the ridge will continue to build through Thursday and may continue into next weekend. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1147 AM MDT Fri May 16 2025 MVFR to VFR conditions will continue today over CDR as light precipitation moves east and our low pressure system departs today. Expect improving sky conditions through the day here. Elsewhere, VFR is expected with mid-level clouds expected to reach SCT or BKN coverage through the day, but clouds will quickly diminish around sunset. Westerly winds will gust upwards of 30kts at RWL and LAR and possibly BFF/CYS before dropping off this evening. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...MAC LONG TERM...CG AVIATION...WFO-RIW ####018003205#### FXUS63 KFGF 162042 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 342 PM CDT Fri May 16 2025 .KEY MESSAGES... - Winds gusts of 50 mph are possible along and west of the Red River Valley today. A wind advisory is in effect through late this evening. - Near freezing temperatures are possible in portions of northeastern North Dakota tonight and Saturday morning. A frost advisory is in effect tonight into Saturday morning. Additional freezing temperatures are possible Saturday night into Sunday morning. && .DISCUSSION... Issued at 342 PM CDT Fri May 16 2025 ...Synopsis... Widespread cloud cover remains in place this afternoon across much of the Northern Plains and Upper Midwest. A cut off H5 upper low is moving very slowly to the east, with scattered showers expected to continue intermittently through early this evening. Ridging begins to build into the Central Plains this weekend, with the axis being somewhat limited by short residence time ahead of another system. This will bring rain chances back into the area Monday into Tuesday. Weak ridging builds back into the area by mid week with additional rain chances returning Thursday into Friday. ...Wind Gusts up to 50 mph Today... Pressure rises and weak CAA will contribute to strong north winds through the remainder of the afternoon into the early evening. Sustained winds will continue to range from 20 to 25 mph with gusts up to 50 mph. Winds are expected to slowly diminish this evening as the upper low moves to the east. ...Near Freezing Temps Possible Tonight into Saturday Morning... Colder air continues to work into the area tonight into Saturday. Near freezing temperatures are possible, especially for the Devils Lake Basin and areas northward to the International Border. There remains some uncertainty regarding cloud cover, with most guidance keeping at least a scattered cloud deck over the area through much of the night. This will serve to inhibit temperatures from falling into the upper 20s, although isolated cooler spots may see a brief period of colder temps. The current expectation brings widespread low to mid 30s into the area. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1220 PM CDT Fri May 16 2025 IFR conditions prevail at KGFK with MVFR ceilings at all other TAF sites. Look for more widespread IFR ceilings heading into the late afternoon and overnight hours, along with scattered light showers and gusty north winds. Sustained winds will range from 15 to 25 knots with gusts up to 38 knots. Slow improvement is expected Saturday morning, with ceilings expected to climb into MVFR territory across most areas. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Wind Advisory until 1 AM CDT Saturday for NDZ006>008-014>016- 024-026>030-038-039-049-052>054. Frost Advisory from 2 AM to 10 AM CDT Saturday for NDZ006>008- 014>016-054. MN...Wind Advisory until 1 AM CDT Saturday for MNZ001>004-007. && $$ DISCUSSION...Lynch AVIATION...Lynch ####018007507#### FXUS63 KLMK 162043 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 443 PM EDT Fri May 16 2025 .KEY MESSAGES... * SIGNIFICANT SEVERE WEATHER OUTBREAK POSSIBLE LATE THIS AFTERNOON INTO THIS EVENING. * All severe weather hazards are on the table, including damaging winds, large hail, tornadoes, and torrential rainfall. A few strong tornadoes and instances of very large hail are possible. && .SHORT TERM /THROUGH SATURDAY/... Issued at 443 PM EDT Fri May 16 2025 A significant severe weather outbreak is forecast across the western Ohio Valley this afternoon and tonight. Currently across our region, earlier clouds and rain have moved out and we've begun to heat up. Temperatures were generally in the upper 70s to the lower 80s across the region with the urban heat island in the lower 80s. Satellite imagery shows where buoyancy is located, which is just south of the I-64 corridor where the cloud field clearly shows horizontal convective rolls indicative of strong deep layer shear. ACARS soundings out of SDF show that CINH is just about eliminated while BNA is free and clear of any capping. We've seen some convection try to fire down in the Lake Cumberland area. This is in area of localized surface mass convergence. An outflow boundary from previous convection extending east into JKL's area will likely continue to wash out with time. Convection down there has continued to struggle. There appears to be a boundary extending from roughly Somerset northwestward to about Owensboro. Latest WoFS runs along with the operational HRRR suggest that some isolated-scattered convection may try and get going along that boundary. If so, model proximity soundings would suggest supercellular development posing an all hazard risk. The main severe weather risk will come later this evening as an impressive band of supercells across western IL and eastern MO works eastward into southern IN and western KY. We're still seeing a bit of variance in trying to time this stuff through the region. So for this update, it appears that this activity would move into our western area by early evening and then into the I-65 corridor by mid- evening. This activity could surge a bit more as the cold pool gets more established and it can get into the Bluegrass/Lexington area by mid-late evening. This line will be capable of producing damaging swaths of wind. Wind gusts of 65-75 mph will be possible with this line, especially in the apex of the surges. QLCS tornadoes are likely as well as the low-level jet axis will increase across the region this evening resulting in very favorable hodographs. Large hail will be possible within the squall line as well. However, the larger hail will be more confined to any discrete supercell. Plentiful CAPE in the 0-15C layer and steep low-mid level lapse rates suggests that 1-2.5 inch hail could occur. Later tonight, there is a possibility that the squall line could become more east-west oriented down across southern KY. If this were to occur, training of heavy convection would occur resulting in an increased flood risk. Given the rainfall this morning and the possibility of this scenario playing out, a Flash Flood Watch was issued earlier today to cover this threat. Most of the convective activity with the line should exit our area in the 1-2 AM EDT time frame. Bottom line, significant severe weather is possible late this afternoon and this evening. Make sure you have multiple ways to receive warnings and a plan in place should a warning be issued! Drier, cooler and less humid weather is expected for Saturday with highs in the lower-mid 70s over southern IN and upper 70s to lower 80s down across southern KY. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Issued at 443 PM EDT Fri May 16 2025 Saturday Night through Monday Night... Dry conditions are expected Saturday night with lows in the upper 50s to around 60. For Sunday, we'll see some weak ridging build in from the west. A low-level flow will allow for some moisture return across western and southern KY could result in some scattered showers. Highs on Sunday will be in the upper 70s with a few 80s down across southern KY. By Sunday night, upper level ridging will build slightly more northward into the region. A warm frontal boundary is expected to lift northward through the region bringing additional showers and storms to the region. Lows Sunday night will be in the upper 50s north of the front, but south of the front overnight lows will be in the low-mid 60s. By Monday and into Monday night, the warm front is likely to stall out across the region with areas of showers and storms. Model soundings do show some instability and adequate shear for organized storms. Though, the best shear/instability remains well west of our region. ML guidance agrees with this, but does have some low probabilities out in our western area. Highs will range from the mid-upper 70s over the Bluegrass to the lower 80s over the southwest area. Lows Monday night will be in the 60s. Tuesday through Friday... Upper level low over the northern Plains will get into a Rex block type pattern by late Tuesday and into Wednesday. Aforementioned warm front will remain in our region and will serve as a focus for additional shower and thunderstorm development. Some strong/severe storms are possible as the low and frontal boundary pass through the region. Highs Tuesday will be in the upper 70s to the lower 80s with overnight lows in the upper 50s/lower 60s. Highs Wednesday look to be cooler with readings in the upper 60s to lower 70s. Upper low looks to move from the Midwest into the Great Lakes region by Thursday with the Ohio Valley remaining in a cool cyclonic flow. We'll likely need to keep some scattered showers in at least for Thursday with drier weather for Friday. Highs both days will be in the upper 60s to the lower 70s with overnight lows in the upper 40s to the lower 50s. && .AVIATION /18Z TAFS THROUGH 00Z SUNDAY/... Issued at 109 PM EDT Fri May 16 2025 Early morning convection is finally pushing to the east of the region. VFR conditions are expected this afternoon with a period of sun/clouds with gusty southwest winds. Next wave of vigorous storms is expected to arrive this evening. The overall convective evolution remains challenging as scattered supercells will be possible across central KY while a large squall line moving in from the west. For now, have largely updated the previous TAF to keep storms in the region beginning around 23Z with the bulk of it occurring between 16/23Z-17/05Z. Given the extensive squall line and expected wind field, have opted to use VRB25G50 in the TAF as the squall line passes through. Most convection should be east of the terminals by 17/06Z, with light SW winds and high cigs for Saturday morning. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...Flood Watch until 4 AM EDT /3 AM CDT/ Saturday for KYZ026>028- 039>041-045>049-053>057-061>067-070>078-081-082. IN...None. && $$ SHORT TERM...MJ LONG TERM....MJ AVIATION.....MJ ####018003810#### FXUS65 KREV 162043 AFDREV Area Forecast Discussion National Weather Service Reno NV 143 PM PDT Fri May 16 2025 .KEY MESSAGES... * For today, near average temperatures, light breezes, and a slight chance for showers and thunderstorm in the eastern Sierra. * A weekend storm will impact the Sierra and western Nevada bringing an increased likelihood of cooler conditions, gusty winds, light rain and mountain snow showers. * Warmer and drier conditions return next week for the 7-10 day outlook. && .DISCUSSION... Today will be the warmest day over the next two days as we'll have yet another cool weekend. We'll have some isolated showers and thunderstorms along the Sierra crest this afternoon (15% chance). The SPC has the Sierra crest under general thunderstorms today, although from looking at the CAMs, I don't see too much of a lightning threat today. SBCAPE is only around 300-400 J/kg and not much upper level support for these storms to really develop and mature. Winds this afternoon will be fairly light as well, only about 10 mph out of the west. Looking ahead to tomorrow and the reason why it's going to cool down this weekend, is because of another spring low diving south just east of the Sierra over western NV. This trough will pack some upper level diffluence and slightly more CAPE (500-600 J/kg) to give a little more strength to the storms. Storm coverage will progress from NE CA (50-60% showers, 30% lightning), to western NV (60-70% showers, 20-30% lightning), down through northern Mineral Co (40% chance, 20% lightning). Less intense showers will pop up over the Sierra crest, so be aware that there's still a 20% chance for showers and 10% chance for lightning Saturday afternoon up there. Winds will also be a nuisance tomorrow afternoon, gusting up to 30- 40 mph out of the NW, while Sierra ridges will be gusting to 70-80 mph. DCAPE looks to be around 600-900 J/kg, so expect outflow gusts around these storms to be up to 40 mph. Strong winds remain likely this weekend, with westerly gusts on Saturday shifting to northerly on Sunday. Saturday's winds appear to be driven by stronger mid-level flow, with soundings continuing to hint at a mountaintop inversion that could enhance surface gusts. Expect widespread gusts of 35-45 mph, with 50+ mph possible in wind-prone areas, especially south of US-50 along US-395 and US-95. Choppy lake waters are likely, especially on Pyramid Lake, Saturday afternoon. The low then moves out on Sunday, leaving high temperatures the coolest they'll be for the next 7 days. Lower valleys top out in the upper 60's and Sierra valleys upper 50's. Winds will increase Sunday as well, a stiff N-NW flow with gusts up to 30-35 mph in the afternoon across western NV. A warming trend will commence Monday and push high temperatures into the mid-80's by Wednesday. Zonal flow will persist throughout this week, keeping us dry and high temperatures in the 80's through Friday. -Justin && .AVIATION... There's a 10-15% chance for showers and thunderstorms near KTRK/KTVL/KMMH this afternoon. Winds will be light and mainly from the west today, with gusts up to 12 kts at all area terminals in the afternoon. Another storm is on the horizon for the weekend with more winds, light valley rain, and light mountain snow. There is an increased trend for LLWS and mountain turbulence concerns starting early Saturday morning continuing into Monday morning. -Justin/McKellar && .REV Watches/Warnings/Advisories... NV...Lake Wind Advisory from 11 AM to 8 PM PDT Saturday NVZ004. CA...None. && $$ ####018005869#### FXUS65 KGJT 162045 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 245 PM MDT Fri May 16 2025 .KEY MESSAGES... - Warm and dry conditions will continue through Saturday, with isolated afternoon showers limited to the higher terrain north of I-70. - Critical fire weather conditions are expected Saturday afternoon across east-central and southeast Utah where the Fire Weather Watch has been upgraded to a Red Flag Warning. - The next storm will move in Sunday, bringing cooler and wetter conditions through Tuesday, as well as mountain snow. && .SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 245 PM MDT Fri May 16 2025 Remnant moisture and a weak shortwave moving across the north (more a wiggle in the near zonal flow) will keep isolated to scattered showers with a few thunderstorms in the picture this afternoon across the northern mountains. So far today, not much is happening outside of a few virga showers but a lot less than activity than the last couple days. Temperatures are already about 5 degrees warmer than yesterday and highs are expected to be closer to normal today and about 5 degrees above normal on Saturday as southwest flow increases ahead of an incoming low pressure trough dropping into the Great Basin from the Pacific Northwest. Enough mixing and warm air advection will allow highs to push towards 80 degrees in the Grand Valley with some lower desert valleys in eastern Utah pushing low to mid 80s, while the remaining lower valleys look to see highs well into the 70s. This warm bump is all before the much cooler airmass arrives on Sunday with the incoming low pressure trough. Southwest winds will gust 25 to 35 mph across east-central to southeast Utah and southwest Colorado on Saturday, with relative humidity also dropping into the teens and single digits, resulting in critical fire weather conditions. Decided to upgrade the Fire Weather Watch to a Red Flag Warning on Saturday for the zones where fuels are considered critical at this time, which includes east-central and southeast Utah (Utah Fire Zones 490 and 491). Regardless of fuel status, caution is urged and outdoor burning is not recommended given the drier and breezy to windy conditions. Precipitation may increase across eastern Utah Saturday night but the latest model guidance seems to be coming around to holding off on the majority of widespread precipitation until Sunday. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Issued at 245 PM MDT Fri May 16 2025 A deep upper-level trough will move overhead on Sunday, bringing widespread precipitation across the CWA along with another bout of strong wind gusts upwards of 35 mph. Temperatures behind the associated slow-moving cold front will drop high temperatures on Sunday 10-15 degrees below normal, though there is little clarity on how much this will bolster snow accumulations considering the uncertainty on how quick the front will move. Should frontal passage occur late morning/early afternoon, cooler temperatures may yield lower snow levels and higher accumulations as opposed to a mid-afternoon frontal passage during peak heating. Deterministic models are siding with the latter at the moment, resulting in modest snow accumulations of 2-4" over the San Juans, central Colorado mountains, and the Grand Mesa, and higher accumulations of 6-10" over the eastern Uintas. Uncertainty grows on Monday as a northern closed low descends southwards through the trough. Lacking moisture with this low (PWAT's 90-130% of normal) will result in primarily orographically-driven showers, though the further reduced temperatures associated with the system would favor more mountain snow and valley rain as snow levels drop to around to 7.5-8.5 kft. The rapidly evolving upper-level pattern regarding the slow- moving trough and the southwards-moving closed low leaves the early-week weather difficult to pinpoint. One way or another, widespread precipitation favoring higher terrain where orographics can better support storms is expected to occur. However, timing and intensity remains unclear, and future forecast discussions should provide more clarity on the details as more short-range model guidance becomes available. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1121 AM MDT Fri May 16 2025 Gusts of 20-30 mph are likely at all terminals across the region between now and sunset before becoming mostly light and terrain-driven overnight. Cigs are likely to drop throughout the afternoon, with KASE and KEGE expected to drop below ILS breakpoints. && .FIRE WEATHER... Issued at 245 PM MDT Fri May 16 2025 Critical fire weather conditions are expected across east- central and southeast Utah as well as west-central and southwest Colorado. The only area that is currently seeing critical fuels though is east-central and southeast Utah (Utah Fire Weather Zones 490 and 491). Therefore, the Fire Weather Watch has been upgraded to a Red Flag Warning for the areas where fuels are critical and conditions look to be met. This Red Flag Warning is in effect Saturday from noon to 8 pm MDT. Critical fire weather concerns lessen Sunday through mid week as we welcome the arrival of a cooler and wetter storm system. However, dry and warmer weather looks to return by late next week which could lead to elevated fire weather concerns. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...Red Flag Warning from noon to 8 PM MDT Saturday for UTZ490-491. && $$ SHORT TERM...MDA LONG TERM...BW AVIATION...TGJT FIRE WEATHER...TGJT