####018008503#### FXUS61 KALY 031410 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 1010 AM EDT Fri May 3 2024 .SYNOPSIS... High pressure over the region this morning will shift eastward to the New England coast during the afternoon. This high will provide continued dry conditions through tonight. The high will only move slightly east off the coast through Saturday, with a frontal system slowly approaching from the west. Clouds will increase on Saturday, with chances for showers developing west of the Hudson Valley. Showers will become more likely by Sunday as the system tracks east across the area with cool temperatures. && .NEAR TERM /THROUGH TONIGHT/... Just some thin high clouds over most of eastern NY but there are some more widespread lower clouds along the New England border into western New ENgland due to light winds from the south and east. The clouds in western New England are slowly eroding and there will be some periods of sun later today in those areas. Lots of sun in eastern NY through the this high clouds. 12Z area soundings show mixing potential supports current forecasted high temperatures across the region. Just minor adjustments to temperatures and sky cove through this afternoon. PREVIOUS DISCUSSION: Surface high pressure over the region this morning slides east into New England this afternoon, with an upper level ridge axis moving overhead through the day. This will result in continued dry conditions, with just some increasing high level clouds. Patchy low stratus clouds in place across northern/eastern parts of the area should mix out by late morning. A cooler onshore SE flow will keep temperatures cooler than that past few days. Highs will be mainly in the 60s to lower 70s. Upper level ridge axis gradually shifts east of the area tonight, as a weak disturbance approaching from the west slightly flattens out the ridge. High/mid level clouds will increase thicken from west to east, with a few sprinkles possible west of the Hudson Valley. Dry low levels should preclude any measurable rainfall. With mostly cloudy skies lows will be somewhat mild in the mid 40s to lower 50s. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... Saturday looks to be the pick of the weekend days in terms of mostly dry weather with near normal temperatures. The surface high is forecast to remain positioned off the New England coast, while ridging aloft is re-established across the Northeast. A slow-moving frontal system will continue to gradually inch eastward from the Great Lakes. The front may get close enough to provide enough forcing for scattered showers mainly west of the Hudson Valley during the afternoon. Highs looks to be close to normal ranging from the upper 50s in the higher terrain to upper 60s in valleys. Better moisture(PWAT anomalies increasing to +1 to +2 STDEV) and forcing start to arrive Sat night, especially late in the overnight, as the upper ridge axis breaks down with a stronger short wave moving in from the west. Will mention likely PoPs west of the Hudson Valley and chance east. Lows will be mainly in the 40s to near 50. Southerly flow increases ahead of the front as it advances into western NY on Sunday. Moisture will continue to surge northward ahead of the boundary, with the aforementioned short wave trough aloft moving eastward across the region. This will result in showers likely across the entire area for much of the day. With the clouds/showers around and a persistent low level S-SE breeze, it will be a cool/raw day with highs only in the 50s with even some 40s in the highest elevations. Rainfall amounts generally look to be around 0.50-1.00", with the max focused on the Mohawk Valley and southern Adirondacks. These rainfall amounts will not cause any hydro concerns. The surface front and short wave aloft move into New England Sun night, with showers tapering off from west to east mainly during the evening. At this time it appears the overnight hours should be mainly dry with high pressure building from the west and a developing W-NW flow ushering in drier air. Lows expected to be similar to recent nights with mid 40s to lower 50s. && .LONG TERM /MONDAY THROUGH THURSDAY/... Long term begins at 12z Monday with the cold front departing off to our east. There could be a few lingering showers around during the morning, especially across western New England, but overall we should see a drying trend as we head through the day. Monday afternoon through Tuesday, upper ridging amplifies to our west with upper troughing to our north in southeast Canada. This will lead to upper confluence near our region and allow a ridge of high pressure to build in from the northwest. With large-scale subsidence, Monday afternoon through Tuesday should be dry. With cold/dry advection and deep mixing behind the front, we bumped temperatures up a few degrees above NBM guidance. Highs Monday and Tuesday will range from upper 60s in the high terrain to mid/upper 70s for the valleys. Lows Monday night will be mainly in the 40s to 50s. Tuesday night through Thursday night...A warm front approaches from the southwest Tuesday night or Wednesday, bringing with it a chance for some showers. However, the exact timing of the warm front remains uncertain at this time. Beyond that, we get into a pattern with broad, positively tilted upper troughing over the center of the country and flat upper ridging to our east. This puts our region in an area of deep, persistent SW flow aloft. With an active jet stream to our west/northwest, there will be several disturbances aloft tracking through our area over the middle to end of next week. While it is too early to specifically time out any of these features, Wednesday through the end of next week looks to be unsettled, so will mention chance PoPs for the entirety of the second half of the long term period. Some thunder may be possible depending on the timing of these disturbances relative to peak daytime heating. With persistent southwest flow and warm advection, highs each day will be in the 60s to 70s with overnight lows in the 40s to 50s. The second half of the week also looks more humid compared to Monday and Tuesday. For days 8-14, we may remain in an unsettled pattern with the CPC expecting above normal precip and near normal temperatures. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... Through 12z Saturday...Mainly VFR conditions as of 6:15 AM EDT except at PSF where MVFR cigs are in place due to low stratus. The low stratus will continue to impact the terminals through the next few hours with some MVFR cigs, but has not been able to expand southwestwards as rapidly as previously expected. Will continue tempo groups through 13-14z to highlight the possibility of MVFR cigs, but all TAF sites should see improvement back to VFR conditions by 14z. VFR conditions then continue through at least midnight tonight with FEW to SCT mid and high clouds around. Overnight tonight, southeasterly winds may allow for more low stratus to develop, especially at ALB/PSF/POU. Will refine the timing and cigs associated with this low stratus with future TAF issuances. Winds will be from the east at 5 kt or less through early to mid- morning, then becoming southeasterly at 5-10 kt from mid to late morning through the remainder of the TAF period at ALB and through around 6z tonight at GFL/PSF/POU, then becoming light and variable at these 3 sites through the end of the TAF period. Outlook... Saturday Night: Moderate Operational Impact. Chance of SHRA. Sunday: High Operational Impact. Likely SHRA. Sunday Night: Moderate Operational Impact. Chance of SHRA. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: Moderate Operational Impact. Chance of SHRA. Wednesday: High Operational Impact. Likely SHRA...TSRA. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...JPV NEAR TERM...NAS/JPV SHORT TERM...JPV LONG TERM...Main AVIATION...Main ####018005833#### FXUS65 KTFX 031415 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 815 AM MDT Fri May 3 2024 .SYNOPSIS... One more cool and showery day is expected today before milder temperatures move in for the weekend. Another cool and wet Pacific weather system impacts North-central and Southwest Montana Sunday through at least mid next week, with the most significant precipitation and coolest temperatures expected Monday through Wednesday. && .UPDATE... A cool northwesterly flow aloft will continue to support scattered rain and snow showers through the day today, primarily across Central and North-central Montana. No significant changes were needed with the update this morning. -AM && .AVIATION... 520 AM MDT Fri May 3 2024 (03/12Z TAF Period) North Central (KCTB KHVR) and the plains of Central Montana (KGTF KLWT): Northerly upslope flow will continue widespread mountain-top obscuring low VFR/high MVFR ceilings through at least 15Z. However, lingering light snow along north-facing slopes (mainly east of KGTF into the KLWT area) will keep conditions there as IFR, obscuring those mountains. High pressure will start moving into the area from the west after 15Z, decreasing the snow and allowing broken ceilings to lift to at least low VFR levels with partial clearing starting after 18Z. However, weak instability during the afternoon may cause isolated to scattered light snow showers to form again between 19Z and 00Z, possibly causing periods of MVFR conditions. Southwest Montana (KBZN KEKS KWYS): VFR conditions are expected to continue through at least 04/12Z. Broken ceilings will continue through at least 18Z, then partial clearing is expected after 18Z. -Coulston Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 520 AM MDT Fri May 3 2024/ The latest satellite and meso-analysis shows abundant cloud cover within a northwesterly flow aloft. Light snow showers have been ongoing all night, mostly over the northerly upslope areas adjacent to the Little Belt, Highwood, and Snowy Mountains. This shower activity will more or less persist through this afternoon with the continued northwesterly flow, though accumulation amounts will generally be negligible. Transient ridging builds in tonight for clearing skies with temperatures bottoming out in the 20s for most locations. Patchy fog development can be expected in spots, but shouldn't be a widespread problem. With one more day of ridging aloft, Saturday should be the driest day over next week while temperatures climb to near of slightly above average. 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 && .PRELIMINARY POINT TEMPS/POPS... GTF 50 26 63 42 / 30 0 0 10 CTB 49 26 59 37 / 20 0 0 10 HLN 54 31 68 44 / 10 0 0 10 BZN 51 28 66 41 / 10 0 0 10 WYS 46 20 60 36 / 0 0 0 30 DLN 52 30 65 44 / 10 0 0 40 HVR 50 27 63 39 / 40 0 0 0 LWT 42 23 59 37 / 40 0 0 10 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls ####018009726#### FXUS63 KLMK 031415 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 1015 AM EDT Fri May 3 2024 .KEY MESSAGES... * Widespread showers with isolated embedded thunderstorms this morning. Scattered thunderstorms possible this afternoon. * Probability of thunder is 15-25% in the morning, increasing to 40-50% this afternoon even as rain chances decrease. * Showers and thunderstorms will be more scattered on Saturday, though forecast confidence in exact timing and coverage remains low. * Increasing potential for strong to severe thunderstorms and flooding next Tuesday through Thursday, though confidence is still low. && .UPDATE... Issued at 1014 AM EDT Fri May 3 2024 Regional radar mosaic shows the early morning widespread precip shield is shifting off to our east as expected, with some scattered showers in the wake. Precip coverage will diminish for the midday hours, with only some scattered showers expected across the area as the cold front continues to approach from the west-northwest. Around or shortly after 18z, we should begin to see additional scattered showers and storms fire up in a marginally unstable but moist environment. Soundings continue to support slow moving and unorganized convection this afternoon with skinny CAPE profiles and weak shear. However, PWATs are already 1.5" across the forecast area this morning, and those will persist for the rest of today. As a result, heavy rain and lightning will be the main threats with scattered storms this afternoon. Probability of thunder increases to 40-50% after 18z and will diminish this evening as peak heating is lost. Forecast is in great shape and no changes are planned at this time. && .SHORT TERM /THROUGH TONIGHT/... Issued at 326 AM EDT Fri May 3 2024 Warm advection/isentropic lift have spawned a band of light to moderate showers ahead of the incoming cold front. Precip shield is just starting to expand east of the I-65 corridor, but very few lightning strikes have been observed as instability is lacking thus far. Expect this band to push through most of the area by mid-morning, with a minimal break before the weak cold front comes in from the W- NW in the afternoon. Not looking for much of an opportunity to warm up, but in a muggy air mass with PWATs near 1.5 inches, sfc temps in the mid 70s are all that's needed for some marginal instability. Wind speeds are generally 25 kt or less in fairly deep SW flow, so not enough shear to support storm organization. Long story short, there's a slight (15-20%) chance for embedded thunder in the band of showers this morning, with scattered (~30% coverage) thunderstorm development possible in the afternoon. We are not expecting an all- day rain, but brief moderate rainfall is possible in any of the heavier showers or thunderstorms. Precip chances taper down this evening and overnight given the lack of heating or identifiable sources of lift. However, in the increasingly moist environment it won't take much, so will hold at least a slight chance through the night. Better chances will be east of I-65 and south of the Bluegrass Parkway into south-central Kentucky, where we could see a weak impulse lifting NE from the Deep South. Forecast confidence is high that we'll see showers at some point. At best medium confidence in thunder, as well as any specific timing. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Issued at 326 AM EDT Fri May 3 2024 Saturday and Saturday Night... Saturday's forecast continues to look tricky as far as precipitation chances are concerned, with forecast confidence in timing and coverage of showers and thunderstorms remaining low. The synoptic scale pattern for Saturday and much of the weekend will not be dissimilar to a typical mid-late summer pattern, with positive height anomalies stretching across much of the eastern one-third of the CONUS and better dynamic support from faster flow aloft remaining well to the northwest of the Ohio Valley. The front which will bring increased chances for rain later today will dissipate before clearing the region, leaving a moist unstable airmass in place for the day on Saturday. 00Z HREF mean sfc dewpoint progs are in the mid 60s Saturday afternoon, with mean PW values ranging from 1.25-1.5", with slightly lower values in southern IN. A combination of hi-res and global model sounding progs show anywhere from 1000-2000 J/kg SBCAPE, and forecast highs on Saturday are expected to exceed convective temperatures. However, as referenced above, there will be a lack of large-scale dynamic support, and convective initiation will likely be determined by the existence/location of differential heating boundaries and other gradients on the mesoscale and smaller. Due to the inherent lack of predictability of these factors, the best forecast still looks to be for a broad area of chance to likely PoPs Saturday afternoon, with lower probabilities along and north of the Ohio River, and higher probabilities south of the western KY/Bluegrass Parkways. The chance for thunderstorms will be closely tied to PoPs, as the amount of available instability will mean that any area of convection strong enough to produce rain will have a roughly equal chance to produce thunder. Severe thunderstorms are not expected on Saturday, as weak flow aloft results in only 5-15 kt of effective bulk shear (depending on model), with garden-variety thunderstorms expected. Finally, any storms which do form will be fairly slow movers, with cloud layer mean winds supporting storm motions from WSW to ENE around 15 mph. A more organized wave of showers and embedded thunderstorms is expected late Saturday night into Sunday morning as another decaying mid-level disturbance and sfc cold front falls apart in the vicinity of the Ohio Valley. Once again, weak flow aloft will curtail any severe potential, and precipitation coverage along the front will decrease as it crosses the region from west to east. Sunday and Next Week... A prolonged period of active weather looks likely over the next 5-7 days with global ensemble guidance in relatively good agreement on the large scale pattern across North America. For Sunday into Monday, the upper level trough over the north central U.S. and Canada will lift east-northeast into eastern Canada, with upper level ridging setting up across much of the eastern CONUS in its place. The trough's northeastward exit will mean that the humid and warm air mass over the central and eastern CONUS will continue with little modification, meaning that diurnally-driven showers and thunderstorms would be expected to continue. Additionally, transient mid-level perturbations within large scale SW flow are expected to swing through the Ohio Valley Sunday into Monday, bringing temporarily enhanced waves of precipitation. These showers and storms would largely be sub-severe and disorganized, as flow aloft will still be too weak to support an organized severe threat. Temperatures will remain above normal, particularly nighttime lows, which will be held higher by elevated low-level moisture content. The severe potential is expected to increase for Tuesday through the middle portion of next week, as upper troughing over the western half of the CONUS ejects into the central Plains, increasing large- scale baroclinicity and, by extension, the strength of the flow aloft across the Mississippi and Ohio Valleys. At this time, confidence in specific threats and timing is very low; however, many ensemble/machine learning/analog severe convection forecasting tools indicate elevated potential for severe weather across our region next Tuesday-Thursday. With several rounds of heavy rain/storms expected over the next week, flooding potential will also need to be monitored, especially the later we go into next week. At this time, HEFS/NAEFS guidance indicate most rivers should remain below action stage; however, these models will not resolve convectively enhanced rainfall totals well, and they still show rising levels over the next 5-8 days. && .AVIATION /12Z TAFS THROUGH 18Z SATURDAY/... Issued at 713 AM EDT Fri May 3 2024 Look for intermittent rain with occasional restrictions to MVFR cig/vis this morning. Heavier showers could result in brief IFR but uncertainty of timing means we won't include it in the TAF. The steadier precip comes to an end midday or just after, but we could still see scattered convection as the front moves in this afternoon. Only terminal that we included TS was SDF from 18-22Z, and that's a low enough probability to handle with VCTS/CB mentions. Precip chances are low enough tonight to keep the TAFs free of precip. However a stalled boundary and a moist air mass will be favorable for fog/stratus toward Sat morning. Have included IFR cig/vis for BWG after 08Z, with MVFR conditions expected at SDF and LEX for the same time frame. Forecast confidence is medium at best. Winds could go light/variable for a substantial portion of the TAF period with the front hung up across the area. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE...CJP SHORT TERM...RAS LONG TERM...CSG AVIATION...RAS