####018007109#### FXUS63 KJKL 040350 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 1150 PM EDT Fri May 3 2024 .KEY MESSAGES... - Shower and thunderstorm potential returns to the forecast through the next 7 days. - Cooler than in recent days, but temperatures are forecast to be above normal through the next 7 days. && .UPDATE... Issued at 1150 PM EDT FRI MAY 3 2024 Scattered showers are found through eastern Kentucky along with a potential for a stray thunderstorm. Have updated the forecast mainly to fine tune the PoPs and thunder chances through the rest of the night per radar and CAMs trends. Did also include the latest obs and tendencies for the T/Td grids. These adjustments have been sent to the NDFD and web servers along with a freshening of the zones and SAFs. UPDATE Issued at 745 PM EDT FRI MAY 3 2024 23Z sfc analysis shows low pressure having moved a little closer to the area from the west and this has pushed the protective area of high pressure out of Kentucky. Accordingly, return flow moisture has helped fuel showers across the region today along with a few thunderstorms. Currently, the best batch of convection is west of the I-75 corridor. This is expected to drift east with time - but weaken. The extra clouds around today along with the showers have kept temperatures on the cooler side compared to yesterday. The latest obs have temperatures generally in the upper 60s to lower 70s. Meanwhile, amid light and variable winds, dewpoints have moistened into the low to mid 60s for most spots. Have updated the forecast mainly to fine tune the PoPs and thunder chances through the night per radar and CAMs trends. Did also add in the latest obs and tendencies for the T/Td/Sky grids. These adjustments have been sent to the NDFD and web servers along with a freshening of the zones, SAFs, and HWO. && .SHORT TERM...(This evening through Saturday night) Issued at 332 PM EDT FRI MAY 3 2024 An active pattern remains across the Bluegrass State through the short term. Large upper low/trough configuration remains over the far northern US and south-central Canada with an active jet stream from the Central Plains to Upper Great Lakes region. Meanwhile, upper ridging remains persistent along the East Coast, and will begin to move offshore Saturday night as the aforementioned upper low begins to move northeast toward eastern Canada at that time. This leaves eastern Kentucky under the influence of a moist and active regime with periodic shortwave disturbances moving across the region through Saturday evening. Currently a disturbance is beginning to exit to the east this afternoon, but will be followed by another tonight into Saturday morning that will bring another round of showers and possibly a few thunderstorms. Models suggest low-level instability is somewhat lacking but there is sufficient elevated instability to warrant a few claps of thunder from time to time, especially west of I-75. Fog formation overnight will be dependent on any lulls in precipitation as well as any potential partial clearing. Lows tonight will range from the mid-50s in the cooler sheltered valleys to lower 60s elsewhere. Another disturbance appears to be well-timed with any daytime heating to help produce more widespread showers and thunderstorms Saturday. Given high PoPs and cloud cover through the day temperatures will struggle to reach the current forecast highs of upper 70s. PoPs gradually lower through Saturday evening through the overnight as a trailing shortwave crosses the area with shortwave ridging building in from the southwest after midnight. Sky cover will likely trend downward but this would likely then promote fairly widespread fog formation late Saturday night into Sunday morning, especially in the river valleys. Expect forecast lows Saturday night similar to tonight's forecast, with mid 50s to lower 60s. .LONG TERM...(Sunday through Friday) Issued at 540 PM EDT FRI MAY 3 2024 The models generally agree on a fairly stagnant long wave pattern across the CONUS through the majority of next week. A seasonably strong 500 mb low pressure system will start out over the West Coast early Sunday morning, before swinging east, residing over the northern Rockies/northern High Plains by early Tuesday. This feature will then elongate and gradually dampen with time as it moves over the Upper Midwest, with a broad positively tilted trough aligning from the Great Lakes back through the Desert Southwest. This will keep west to west southwest flow across the Ohio and Tennessee valleys aloft, with several progressive short wave troughs to move through the region at times. At the surface, a quasi-stationary front will be aligned just north of the area through early next week, before a cold front approaches by the end of the next work week. This will all result in unsettled weather across eastern Kentucky through the long term forecast, with daily chances of showers and thunderstorms. Have generally stayed a bit below the blended guidance on PoPs for the days where the overall forcing is weaker and/or less certain, as it is known to overdo more diurnally influenced convection. At this time, rain chances look to peak on Monday (80-90%), and then again on Thursday (70-80%), with better forcing at play. The rest of the period will feature chance PoPs (30-60%). Temperatures will average 5-10 degrees above normal, with lows mainly in the lower 60s, while highs range from the upper 70s to lower 80s most days. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 815 PM EDT FRI MAY 3 2024 Occasional showers will continue through much of the period, though nailing down timing at any one TAF location is difficult. Models seem to move a decent chance for convection east through the evening - fading out after midnight. Accordingly have carried some prevailing showers - thunderstorms included at SME initially - across the aviation forecast area into the night. Any storm could produce locally heavy rainfall and gusty winds, along with brief periods of MVFR or IFR visibilities. MVFR CIGs will also be possible at times this evening during peak shower/thunderstorm activity and again into dawn across the northern terminals. If shower activity and thicker clouds taper off sufficiently overnight we will likely see at least some fog develop at some of the TAF sites. Conditions improve Saturday morning with still a decent chance for storms from midday on, though. Winds will be light at less than 10 kts and generally out of the south to southwest through the forecast period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...CMC LONG TERM...GEOGERIAN AVIATION...CMC/GREIF ####018005529#### FXUS65 KRIW 040351 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 951 PM MDT Fri May 3 2024 .KEY MESSAGES... - Snow ends this afternoon, with a clearing sky overnight. Patchy fog is possible (20%) for basins and near Casper due to recent moisture (snow). - High pressure Saturday brings warmer temperatures and dry weather. Warmer Sunday. - Gusty south wind Sunday. Gusts 30 to 50 mph for most of the area. Strongest winds over southern Sweetwater County, with high winds (gusts greater than 58mph) likely (80%). Impacts to I-80 and South Pass due to strong crosswinds. - Precipitation moves in Sunday, with widespread precipitation Monday. Snow levels drop to around 6000 feet. Cool and unsettled weather pattern through next week. && .DISCUSSION... Issued at 1238 PM MDT Fri May 3 2024 Snow has been falling across the area this morning as a cold front passes through. As the sun rises through the afternoon, any snow that has accumulated on grass should melt quickly. Clouds linger through the rest of the day, limiting high temperatures today. Many places peak in the upper 40s today, with the Bighorn Basin seeing a few places hit 50. These temperatures are roughly 10 degrees below normal. Any remaining precipitation comes to an end by around 03Z (9pm). As the trough moves eastward tonight, transitory ridging builds in for the weekend. Starting with Saturday, the day brings warm temperatures and a mainly clear sky (a stark difference from today). High temperatures for many reach the mid-to-upper 60s, with a few places hitting 70. A slight breeze develops in the afternoon (10-25 mph gusts), but should otherwise be a good day for any outdoor activities or chores. The high pressure shifts eastward for Sunday as a potent upper-level low swings into the northern California area. This brings a tight pressure gradient, as well as a 100 knot jet positioned into southern Sweetwater County. A strong south wind develops after sunrise, and especially for the afternoon and evening across Sweetwater County, northward into most of the CWA (exception being far northwest Wyoming). Where the exit region of the jet is (southern Sweetwater County), gusts up to 70 mph are possible if the upper levels are able to fully mix down. Shift of tails highlights this area in the 90th percentile. Elsewhere, widespread gusts 35 to 50 mph occur. Being a south wind, roads like I-80, South Pass/Red Canyon, and US-26 will be impacted as strong crosswinds occur. Precipitation chances move into western Wyoming Sunday morning, spreading east of the Divide for the afternoon and evening, with about a 20% chance of thunderstorms. Snow levels begin around 9000 feet Sunday, but drop to roughly 6000 feet through Monday morning. Therefore, lower elevations are expected to receive mostly rain from this system. That upper-level low moves into the Utah/Idaho/Wyoming area Sunday night and into Monday. Winds begin to shift to a more southwesterly direction, decreasing the gusts some from the day, but gusty winds continue through the night, especially from Sweetwater County up through Natrona County. For Monday, the center of the low is projected to move across Wyoming, then traveling northeastward near the Montana/North Dakota border. The GFS and ECMWF vary a bit in placement on this. Widespread precipitation occurs Monday. The heaviest precipitation will be where favored upslope occurs. Currently, this would be for the Bighorn Mountains and Johnson County, but as mentioned, there is still some uncertainty in exact storm track, which could alter where the best precipitation totals are favored. Will need to watch closely the next few days on where models agree on the storm track. The low is slow to move, as ridge over the eastern half of the country keeps it mostly in place. This would keep precipitation chances over the area Tuesday, especially over the northern half of Wyoming. Currently, models are keeping the influence of the low through Friday, so a cool, cloudy, and unsettled next week is in store. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 949 PM MDT Fri May 3 2024 Showers have ended this evening and skies have steadily been clearing. The trend of clearing skies will continue tonight, with mostly clear skies expected through Saturday morning. Patchy fog is the only hazard tonight/Saturday morning due to the recent moisture and clearing skies. Terminals with a chance of patchy fog are KCPR/KRIW. The better chance (50%) is at KCPR, so have MVFR VIS and FEW003 from 10Z-15Z/Sat. At KRIW kept VCFG as it is less likely (30%) to occur/impact the terminal. The prevailing wind will be light and variable at most terminals tonight before becoming southerly late Saturday morning. High clouds (SCT200) will pass overhead Saturday afternoon, with increasing cloud cover heading into Saturday evening. All terminals will have prevailing VFR conditions through the TAF period, with the exception of KCPR due to fog. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Wittmann AVIATION...Rowe