####018004980#### FXUS65 KTFX 032055 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 255 PM MDT Fri May 3 2024 .SYNOPSIS... Lingering showers and snow showers will be around through the early evening ahead of a mild and dry Saturday. Precipitation chances will return Sunday into much of next week, with potential for an impactful spring system over the middle of next week. && .DISCUSSION... Through Saturday... Transient shortwave ridging is beginning to build in across the Northern Rockies between one upper disturbance exiting eastward across Southern Canada and another approaching the Pacific NW. Lingering northwesterly flow aloft will combine with daytime heating to result in rain and snow showers the remainder of this afternoon and early evening, primarily across the plains. Clearing skies and light winds tonight will allow for patchy fog formation into Saturday morning, but is not expected to pose many impacts at this time. Saturday looks to be a pleasant day as the aforementioned ridge moves overhead, with the only potential blemish being breezy easterly to southeasterly winds across the plains in the afternoon. Daytime highs look to rise to near to a touch above average in most areas. -AM Saturday night into next week... Deep southerly flow aloft develops over Southwest MT Saturday night ahead of a closed low moving onto the Pacific NW coast. This system will trek eastward into S ID on Sunday, placing the Northern Rockies on the ascent side of the system for northward expansion of shower and isolated thunderstorm activity, though temperatures will remain near average for one more day. H700 flow slows down by Sunday afternoon and MU CAPE looks to be around 100 to 300 J/kg (highest southwest MT), so not expecting anything beyond general thunderstorm risks at this time. Ensembles remain in decent agreement with the aforementioned closed low swinging NE into E MT and slowing down some Monday through early Thursday. Although, there are differences on the precise path of the low, most favor cool, wet, and windy periods during this timeframe. According to the NAEFS Standardized Anomaly, H700 temperatures are forecast to be around -8C for much of this event, which would support mountain accumulating snow, but mostly rain at lower elevations. Current probabilistic forecasts for rainfall highlight the eastern portions of North-central MT with the highest chances (50 to 70%) for 1 inch of rainfall during the 72 hr period ending next Thursday at 6 am, with nearly all locations in the CWA standing at least a 50% for a quarter inch of rainfall for the same time period. The one drier exception looks to be southwestern valleys from Dillon to the Three Forks area. As mentioned earlier, thermodynamic profiles should confine accumulating snow to mountain areas, with the Little Belts and the Madison/Gallatin ranges seeing 60% + chances for 8 inches of snow or more Monday through Thursday, with most of it falling Tuesday night into Wednesday. H700 flow on the backside of this low will be at or above the 30 to 40 kt range for an extended period, resulting in gusty to at times strong northwesterly surface winds. While all days Monday through Wednesday look to be on the windier side, Tuesday is being singled out by the EC Extreme Forecast Index and NBM probabilistic forecasts as the windiest day overall, with many locations seeing 70% + chances for wind gusts above 40 mph. Drier and milder conditions move in for Thursday and Friday of next week, though around 50% of the ensembles support weaker troughing remaining in place for non-zero chances for precipitation and near average temperatures heading into next weekend. - RCG && .AVIATION... 1111 AM MDT Fri May 3 2024 (03/18Z TAF Period) Primary concerns through this TAF period will be for lingering low clouds and rain/snow showers, primarily across the plains this afternoon and early evening. Looking ahead toward Saturday, VFR conditions prevail, with a breezy easterly to southeasterly wind developing across the plains by late morning. Mountains will be obscured through the afternoon today across Central and North- central Montana. -AM Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 26 64 42 63 / 20 0 10 40 CTB 26 60 37 59 / 20 0 10 30 HLN 31 69 44 69 / 10 0 10 60 BZN 25 67 42 65 / 10 0 10 70 WYS 19 60 36 52 / 10 0 30 90 DLN 30 66 43 60 / 10 10 40 70 HVR 25 64 39 71 / 20 0 0 20 LWT 23 59 36 65 / 20 0 10 30 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls ####018005445#### FXUS66 KSTO 032056 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 156 PM PDT Fri May 3 2024 .SYNOPSIS... DRY AND WARM WEATHER TODAY WITH LOCALLY BREEZY NORTHERLY WINDS. ACTIVE WEATHER RETURNS THIS WEEKEND AS A WEATHER SYSTEM MOVES INTO THE AREA BRINGING SHOWERS, MOUNTAIN SNOW, ISOLATED THUNDERSTORMS, GUSTY WINDS AND MUCH COOLER TEMPERATURES. && Sunny and pleasant conditions prevail across interior NorCal this afternoon, with some breezy northerly winds being observed in the Valley. Our next weather system is approaching the area from the Gulf of Alaska and is expected to bring widespread rain showers, mountain snow, isolated thunderstorms, gusty southwest winds, and much cooler temperatures on Saturday. Model guidance shows an anomalously deep and cold closed low moving into the PacNW Saturday morning. Precipitation first looks to begin in far northwestern California early Saturday morning then spread inland throughout the day. Latest forecast rainfall totals remain around 0.50" to 1.30" inches for the Valley and around 1" to 3" inches in the foothills and mountains. With the track of the low forecast to move over northern part of California, there will be a risk of isolated thunderstorms to develop Saturday afternoon and evening. There exists a 15-25% probability of thunderstorm development, with the better chances north of I-80. Any thunderstorms that do form could bring locally heavy rainfall, dangerous lightning, gusty winds, small hail, and possible funnel clouds. The Winter Weather Advisory has been upgraded to a Winter Storm Warning, with the timeframe remaining the same, from 11 AM Saturday until 8 AM PDT Sunday. Snow, heavy at times, is expected mainly for elevations higher than 5000 feet. Total snow accumulations forecast are around 5 to 12 inches, with locally higher amounts at the highest elevations. NBM probabilities of exceeding 12" inches of snowfall are at around 60-80% along the I-80 corridor. Winds will also be gusting from 30 to 50 mph out of the southwest. Snow levels will be at around 4000-5000 feet Saturday afternoon, and lower as the system moves through the area to around 3000 feet on Sunday. Snowfall rates of 1-2" inches per hour are possible, mainly from around 10 AM to 10 PM Saturday as the bulk of the precipitation moves through. Snow covered roads, reduced visibilities, and chain controls are all likely. If you must travel this weekend, make sure to check road conditions at quickmap.dot.ca.gov before heading out. Gusty winds will also begin to develop later tonight through Saturday as the system moves closer to the area. The NBM projects around a 55-90% probability of wind gusts greater than 40 mph in the northern/central Sacramento Valley and northeast foothills. Today is a great day to secure any loose outdoor items to prepare for the potential of gutsy winds. Precipitation should move through the area relatively quickly, with most of the heavier rain/snow ending by Sunday morning. A noticeable sensible weather impact from this system will be the drop in high temperatures around the region. Saturday, we can expect temperatures to be around 10-20 degrees cooler than today's high temps. Sunday we will start to slightly recover temperature wise as the closed low moves further off to the east, with highs in the mid 60s for the Valley and mid 30s to low 50s for higher elevations. Monday, our high temperatures will climb back into the low 70s for the Valley, with off-shore ridging beginning to develop in the Pacific. && .EXTENDED DISCUSSION (Tuesday THROUGH Friday)... Broad upper level troughing from the Pacific Northwest toward the central Plains looks to remain in place through midweek. This will induce continued northwesterly flow across interior NorCal during the extended forecast period. A reinforcing shortwave looks to travel through this flow pattern Tuesday into Wednesday, gradually deepening the trough (and potentially retrograding it) through the late week period. While precipitation impacts look to remain displaced to the north and east of the region, this pattern looks favorable for northerly surface winds to set up from Tuesday through Friday of next week. Exact details such as timing and magnitude of the winds is still somewhat uncertain, but ensemble guidance is coming into agreement on a dry, warm, and windy pattern setting up mid to late next week. Strongest winds, with gusts to 40 mph or greater, are expected on Wednesday and Thursday, with still breezy to locally gusty winds on Tuesday and Friday respectively. && .AVIATION... VFR conditions over interior NorCal until around 08z Saturday then areas of MVFR/IFR becoming widespread as weather system moves into the area. Local LIFR over mountains in precipitation. For the Valley, surface winds at or below 12 knots until around 08z, then southerly winds of 15-30 knots with local gusts 40 knots possible. Over the mountains, southwesterly wind gusts of 40-50 knots possible. && .STO WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 11 AM Saturday to 8 AM PDT Sunday for West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park. && $$ ####018008743#### FXUS64 KBMX 032058 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 358 PM CDT Fri May 3 2024 ...New LONG TERM... .SHORT TERM... (This evening through Saturday) Issued at 145 PM CDT FRI MAY 3 2024 Key Messages: - Chances for showers and some thunderstorms will increase through the afternoon, becoming widespread late this evening through much of the overnight hours. - Storm motions are fairly slow with rain rates in excess of an inch per hour, areas that receive multiple rounds of heavy rain could experience ponding or water with limited potential for highly localized flooding. - Patchy fog may develop overnight due to the widespread heavy rainfall. This afternoon. A shortwave trough is positioned over the Lower Mississippi River Valley Region at midday while mid-level ridging was located over much of Florida and the Bahamas. A diffuse thermal gradient was observed in surface analysis across the northern third of the area where a weak boundary remains present. Through the morning and into midday, this feature has acted as a focus for persistent and additional development of shower and some thunderstorm activity. A cold front was analyzed from Northern Michigan that extended southwest across the Mid Mississippi River Valley and further southwest into Northern Texas. Expect rain chances through mid afternoon to continue to be maximized generally north of the Interstate 20 corridor with an additional area for increase across our western counties as activity continues to develop just head of a convective cluster of showers and thunderstorms that continues to move east across much of Mississippi. This activity is moving about 20 mph, which is slow enough to drop heavy rainfall as rain rates are in excess of an inch per hour to our west currently. There will be limited potential for some ponding of water and perhaps localized flooding if an urban or low-lying area experiences persistent or multiple rounds of heavy rainfall over time this afternoon into tonight. From mid afternoon through early evening, widespread showers and isolated thunderstorms will develop and move into the area from the west with the greatest coverage across the northern and western portions of the area. Winds will be from the southwest at 6-12 mph. Highs will range from around 80 far northwest to near 90 far southeast. Tonight. The mid-level shortwave will move over the are overnight, continuing to support showers with some thunderstorms across the northeast and central portions of the area. This activity will become more confined through the early pre-dawn hours on Saturday across our northeast and far eastern counties. With shower activity tapering off in the pre-dawn hours, low- level moisture will be high and some patchy fog is anticipated, especially for areas that receive heavier rainfall this afternoon through late tonight. Winds will be generally from the south to southwest overnight with speeds from 3-6 mph. Low temperatures will be in the lower to mid 60s areawide. Saturday. The mid-level shortwave will move east over Georgia by early afternoon while a weaker shortwave moves over the Mid-South Region toward mid afternoon on Saturday. A surface cold front will move east, extending from near Chicago and extending southwest across the Ozarks and into the Southern Plains by Saturday evening. A few remnant outflow boundaries from previous convection may remain across the area during the day, providing low-level convergence forcing to permit continued chances for showers and some thunderstorms. The better chance appears to be across the northeast half of the area, but at least isolated showers and storms are expected to develop across the rest of the area through the afternoon hours as the pattern remains unsettled with sufficient heat and humidity to support shower and thunderstorm development. Winds will be from the southwest at 5-10 mph. High temperatures will range from the low 80s northeast to near 90 southwest and far southeast. 05 && .LONG TERM... (Saturday night through next Thursday) Issued at 345 PM CDT FRI MAY 3 2024 Long term forecast is on track today, with no significant changes needed. There will be several opportunities for rain, especially across the north through the week. Expect warm temperatures as well, with lower 90s for at least the southern half of the area by Wednesday. 14 Previous long-term discussion: (Saturday night through next Thursday) Issued at 253 AM CDT FRI MAY 3 2024 Weak quasi-zonal flow aloft continues Sunday, with yet another convectively enhanced shortwave/MCV moving in from the Plains during the late afternoon and evening hours. PWATs around 1.8 inches will be favorable for scattered to numerous showers and storms developing with daytime heating, highest chances north. The shortwave appears a touch slower than previously forecast and have raised PoPs Sunday evening. Shortwave ridging in advance of the shortwave trough should allow temperatures to warm into the mid to upper 80s ahead of convection. A deep trough will eject across the Central and Northern Plains Monday with ridging building ahead of it. The prior weak shortwave may still be close enough to some of the northeastern counties to enhance diurnal convection there. The deep trough remains across the north-central CONUS on Tuesday as ridging builds over the Southeast CONUS. Strengthening low-level southwesterly flow will cause efficient mixing and warming temperatures/lowering dew points especially across the southeast half of the area, suppressing convection. But moisture pooling ahead of a stalled frontal boundary may remain sufficient for isolated to scattered convection in the northwest counties. Wednesday and Thursday a trough with a strong positive tilt will extend from the Great Lakes to the Four Corners while subtropical ridging strengthens over the Gulf. The tightening mid-level height gradient between these two features will result in strengthening WSW flow aloft. A quasi-stationary frontal boundary will reside across the Mid-South with several waves of low pressure riding along it. A strong EML will result in a very unstable air mass south of the front with strong deep layer shear as well. An early spring heatwave with near record highs looks likely across the southern counties. Will have to watch any convective disturbances skirting near the northern counties along the northern fringes of the warmer 700mb temperatures given a conditionally favorable environment for severe storms. 32/Davis && .AVIATION... (18Z TAFS) Issued at 1244 PM CDT FRI MAY 3 2024 Clouds will continue to increase from the west and southwest through the afternoon. Showers with some storms will continue to develop across portions of the north and west portions of the area through mid afternoon, potentially affecting our northern terminals through late afternoon. More widespread showers and storms are moving east across Mississippi and will bring widespread chances for showers and storms late this afternoon and through the late evening hours. Lingering showers with a few storms will remain most persistent across the central and eastern counties overnight through late Saturday morning with lower chances to the south and west. 05 && .FIRE WEATHER... Periods of showers and storms are forecast through Sunday. Given the scattered nature of the activity, rain amounts will average near one-half inch, with higher amounts where thunderstorms track. With increasing moisture, minimum RH values will be above 40 percent each afternoon. 20-foot winds should average less than 10 mph from the south to southwest, though could gust to around 25 mph and be variable in direction in or near thunderstorms. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 64 81 61 85 / 70 60 30 60 Anniston 63 82 63 85 / 70 60 30 60 Birmingham 65 82 65 85 / 70 50 20 60 Tuscaloosa 65 86 65 87 / 70 40 20 50 Calera 65 85 65 85 / 70 40 20 50 Auburn 65 85 65 85 / 50 40 30 50 Montgomery 66 87 65 88 / 60 40 20 40 Troy 65 88 64 88 / 40 40 20 30 && .BMX WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...05 LONG TERM....14 AVIATION...05 ####018004239#### FXUS64 KJAN 032059 CCA AFDJAN Area Forecast Discussion National Weather Service Jackson MS 300 PM CDT Fri May 3 2024 ...New DISCUSSION... .DISCUSSION... Issued at 245 PM CDT Fri May 3 2024 Tonight through Sunday night...Isolated to scattered showers and thunderstorms are occuring across much of the area this afternoon, and this will continue before ending from west to east early this evening. Skies may clear some overnight, and with good radiational cooling patchy areas of dense fog will be possible early on Saturday. An HWO graphic will be issued for this potential. Another short wave will move into the area Saturday afternoon and this will kick off another round of shower's and storms. With a little better lapse rate/instability on Saturday, a strong to possibly severe storm cannot be ruled out Saturday afternoon. Little will change on Sunday as moisture continues and yet another in a series of short waves move across the area. Drier air begins to move into the area Sunday night. Highs through the weekend will be in the 80s, with overnight lows in the mid 60s./15/ Monday into Friday...the overall forecast for next week remains similar. Focus will be well above normal/heat early into mid week, potential for severe storms mainly in the Thu-Fri periods, then followed by a marked cool down. The driver for the increasing warmth will be with a pattern shift to more of a ridge influence with the ridge axis over us Mon, then the ridge shifting eastward as we see a powerful system dive across the Rockies and Central Plains. We will be on the western periphery of the low level ridge/high and that will provide a decent S/SW lower level flow to bring in moisture and those well above normal lower level temps. Additionally, we will see capping in play which will keep rain/storm chances more in check. There's some 20-30% type PoPs for Mon-Wed, but this is more due to model variability and I expect this to lower some. The exception could be in the far N, where more proximity to the better lift could allow for better chances. As for severe weather potential...this is mainly looking like potential for a round or two sometime in the Thu/Fri periods. PoPs have come in higher which fits and will follow. Look for chances to continue to increase for a particular period as better timing starts to work itself out. Like yesterday and prev guidance, uncertainty is pretty decent on specifics and timing, which is often the case at day 6-7. However, the pattern and consistency for the needed ingredients (instability, steep lapse rates, moisture, shear, lift) continue to show up. I'll also add, later Wed night is a period to watch as well as there will likely be severe activity on-going to our NW/N which could migrate down into some of our northern area. Lastly, the ingredients I noted are all reaching very solid levels and fitting of a potentially upper end type event(s). Details will determine the type of severe, but at this time, confidence is on wind/hail. In the wake of this system, the trends are for a solid front/trough passage for the weekend which would bring much cooler conditions to the area. /CME/ && .AVIATION... (18Z TAFS) Issued at 146 PM CDT Fri May 3 2024 A mix of VFR/MVFR/IFR conditions prevail across TAF sites this afternoon and this will continue through much of the day as showers/thunderstorms move across the area. The bulk of the storms will move east of the area this evening, but expect stratus/fog to develop overnight after 09-10Z with sites becoming IFR/LIFR. /15/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 82 64 86 66 / 80 10 40 30 Meridian 85 63 88 65 / 70 30 40 30 Vicksburg 81 64 86 67 / 80 10 40 30 Hattiesburg 84 65 88 66 / 50 10 30 10 Natchez 80 64 86 65 / 60 10 40 30 Greenville 80 66 84 67 / 60 20 40 40 Greenwood 81 65 84 67 / 80 30 40 40 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ 15/CME/