Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/05/24


AREA FORECAST DISCUSSION
National Weather Service Albany NY
1020 PM EDT Sat May 4 2024 .SYNOPSIS... As a storm system approaches from the west, rain will overspread the area late tonight and continue through much of the day on Sunday, with much cooler temperatures. Clouds will break for some sun on Monday with milder temperatures returning to the region. Warm and sunny weather is expected on Tuesday before the threat for showers returns to the region for Wednesday and into the latter portion of the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... .UPDATE...As of 1020 PM EDT, light rain showers and overcast skies are moving into the region from the southwest, although surface dewpoint depressions greater than 10 degrees persist outside of the southern Mid-Hudson Valley and eastern Catskills; even Poughkeepsie ASOS is still reporting an 11F dewpoint depression as of 10 PM EDT. As the column saturates, light precipitation will begin to reach the ground through the overnight period and will continue for much of the day on Sunday resulting in a soaking rain for most of the region. With only minor updates made to the arrival time of rain showers overnight, the forecast remains largely on track; see previous discussion below... .PREV DISCUSSION [0730 PM EDT]...At the surface, high pressure (around 1030 hpa) is exiting off the coast of Maine and will continue to slowly depart off to the east tonight. Meanwhile, a slow moving frontal boundary is located over the Upper Midwest and Great Lakes and it will be heading towards the area for tonight into Sunday. Visible satellite shows a mostly cloudy sky over the region, with the most breaks for far southern areas. Skies will continue to be mostly cloudy through the evening with some occasional breaks, but sky cover will start to lower and thicken for tonight as the storm system approaches from the west. A few light sprinkles and brief showers can be seen on radar across central New York, with a few of these already sneaking into the Adirondacks. Through the evening hours, a brief shower can`t be ruled out for western areas, but most of the area will be staying dry this evening, as the best forcing continues to remain off to the west. As the ridge axis continues to depart off to the east tonight, warm advection thanks a southerly low level jet around 30 kts will allow for a period of fairly steady rain showers to spread towards the area for the late night hours. 18z HRRR suggest this will be spreading across southern and western areas after midnight and expanding northeast across the area for the late night hours. Rainfall looks fairly light in intensity overall, but all areas will be see rainfall by daybreak, with up to a quarter inch of rainfall occurring by sunrise Sunday. Southerly winds will be starting to pick up by the late night as well, especially in the larger north-south valleys. After another mild and comfortable day, temps will drop this evening and will continue to fall for tonight with the rain spreading into the area. Most areas will see lows in the mid to upper 40s (some spots may bottom out right around 50). && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... As the frontal boundary slowly approaches from the west, most of Sunday looks to be fairly wet and damp with periods of showers through the entire day, with the steadiest and heaviest rainfall across northern and western areas. Temps will be held down and steady due to the persistent clouds and precip, with most spots being held into the lower to middle 50s through the day. Overall, additional precip on Sunday will be one third to two thirds of an inch of rainfall. While this won`t be enough to cause any hydro issues (especially within greenup starting to occur), it still make for some wet and soggy conditions outdoors. Although the steadiest precip will be done for Sunday evening, some showers may still linger into Sunday night as the main frontal boundary crosses the area from west to east overnight. Otherwise, it will remain cloudy and damp with some patchy fog and temps in the upper 40s. On Monday, clouds will eventually break for some sun by the mid to late morning hours. A stray shower or sprinkle is still possible for some high terrain or eastern areas, but most spots should be dry on Monday. Temps will be mild once again, especially once the sun returns by Monday afternoon, when temps should reach back into the 70s for valley areas. Quiet weather will continue into Monday night, with skies becoming mainly clear and lows falling into the 40s. && .LONG TERM /TUESDAY THROUGH SATURDAY/... The long term period will begin will high pressure and upper level ridging close to the area on Tuesday. This should allow for a nice day with plenty of sun and rather mild temps. Many valley areas may reach into the mid to upper 70s on Tuesday afternoon. However, the quiet and pleasant weather will only be short lived, as the ridge will be breaking down for the middle to latter portion of the week. The first in a series of shortwaves will be moving across the area on Wednesday. Guidance suggest a wave of low pressure will be tracking over or just north of the area. As a result, a period of showers is expected for Wednesday and some thunder will be possible as well (especially southern areas). It should still be fairly mild with temps in the 60s and 70s once again. Behind this initial disturbance, additional storms are expected to impact the region, as an upper level trough sets up over the Northeast and disturbances rotate across the region. With more wet weather expected for Thursday through the weekend, will continue to go with chc to likely POPs each day. A few additional rumbles of thunder are possible from time to time as well, although it will depend on just how much instability is available. Temps still look close to normal, with highs in the 60s and overnight lows in the 40s to near 50 through the late week and no threat for any frost/freeze in areas where the growing season has begun. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... Through 00Z Monday...VFR conditions expected to initially prevail at all terminals, before vsbys/cigs trend downward to MVFR and possibly IFR late tonight into early Sunday morning as showers arrive. Current cigs at 4-6 kft will slowly lower while coverage increases, reaching MVFR levels and becoming ovc by around 10Z at ALB/GFL/POU and possibly a few hours earlier, before 06Z, at PSF. Shower coverage increases from southwest to northeast, with MVFR vsbys during rain showers after 10Z Sun along the Hudson Valley, and by 12- 14Z farther east at PSF. Cigs may continue to trend downward, possibly reaching IFR levels after 15Z Sun. MVFR/IFR conditions within rain showers will then continue through the remainder of the period to 00Z Mon. Southeast winds around 10-15 kt are expected throughout the period at all terminals. Occasional gusts of 15-20 kt are additionally possible at ALB/PSF. Late in the period, after 15Z Sun, winds will begin to shift slightly out of the south to southeast. Low-level wind shear may approach 30 kt out out of the south-southwest across the region after 12-15Z Sun, but is at this point expected to remain below thresholds. Outlook... Sunday Night: High Operational Impact. Breezy. Likely 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. Wednesday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Thursday: High Operational Impact. Likely SHRA. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Frugis NEAR TERM...Frugis/Picard SHORT TERM...Frugis LONG TERM...Frugis AVIATION...Picard
Area Forecast Discussion
National Weather Service La Crosse WI
1046 PM CDT Sat May 4 2024 .KEY MESSAGES... - Fog possible tonight along and east of the Mississippi River. - An active stretch of weather from Monday night through at least Thursday as multiple rounds of showers move through. Severe weather risk for Tuesday is trending south. && .DISCUSSION... Issued at 200 PM CDT Sat May 4 2024 TONIGHT: fog, frost? With a day of wetting rains saturating the boundary layer and clouds not slated to clear until near or after sundown, decent setup for fog. Add in diminishing winds and the potential increases. Short term models aren`t overly enthusiastic on the widespread possiblity for thick/dense fog though. HREF and RAP hold any "thicker" type fog to the I-94 corridor northward. Can`t rule out a thin fog layer in the river layers too, ala what occurred a couple days ago. Will hold with some mention of fog mostly along, east of the Mississippi river for now. In addition, passage of a cold front will bring in colder air with lows expected to bottom out in the upper 30s to lower 40s. Some potential for frost in low lying areas as a result, mostly in central and north-central WI. Not widespread enough, nor high enough confidence, to warrant a frost adv at this time. Active Weather Pattern Next Week: Shortwave ridging will be over the area through Monday. Warm southerly flow and increasing PWATs are expected out ahead of a low moving through the Upper Plains. Temperatures in the low 70s expected. An 850mb jet with winds between 30 and 45 kts will be over our area during the late evening on Monday and overnight period into Tuesday. Convection across the Plains is expected to begin Monday afternoon and push eastward throughout the day. Moisture transport increases late in the day on Monday across eastern Minnesota and Iowa. As the storms push eastward into Wisconsin, even though shear and life potential increases, instability will decrease. Thus the severe threat with this first round of storms is low. Another factor that plays into the severe threat is timing. These storms will push through the overnight period, so daytime heating and the gradually weakening warm sector will help to minimize the severe threat. After this first round moves out by early Tuesdsay afternoon, model guidance continues to show another round of storms forming over Iowa as a shortwave pushes around the main low. While this wave does look stronger with higher CAPE and lift potential, moisture advection is weaker and so is the low-level shear. Even though the ingredients are there to at least have some thunderstorm development, the biggest inhibitors for development is that environment will probably be worked over the morning thunderstorms and that the warm sector will be further southeast of our area. At the moment, southeastern Iowa and northern Illinois will have the better chances at afternoon thunderstorm development. From Wednesday through the rest of the week, this shortwave becomes a cutoff low and the original low weakens and gets absorbed by the new low. This cutoff low will be over the Upper Midwest providing the area with northwest flow and periodic chances for precipitation to occur. With this flow pattern, temperatures will cool down and remain in the low to mid 60s from Thursday through the weekend. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1045 PM CDT Sat May 4 2024 Main aviation forecast question for this TAF period revolves around fog potential towards daybreak at LSE. Rainfall earlier today combined with clear skies and light winds will prove favorable, but the highest likelihood for fog development looks to be along and north of I-94 in Wisconsin. Models have struggled with recent post-rain fog events and are not very supportive for fog at LSE late tonight, but observed dewpoint depressions are dropping at this hour, so trends suggest the possibility exists. Will introduce MVFR visibility (20% probability) in the 06Z TAF, but confidence is only medium in overall fog potential and how low visibility might drop. Right now there is a small (10-15%) chance for IFR visibility at LSE by daybreak and possibly some accompanying low stratus if this full-on fog development scenario would pan out. Otherwise VFR conditions for the TAF sites with light winds under 10 knots, fluctuating between westerly and southerly as high pressure drifts overhead. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Cecava/Rieck AVIATION...Kurz
Area Forecast Discussion
National Weather Service Goodland KS
1003 PM MDT Sat May 4 2024 .KEY MESSAGES... - Monday will see a chance for severe thunderstorms east of Highway 25 in northwest Kansas and southwest Nebraska from the late morning to mid afternoon hours. - Also on Monday, for areas west of Highway 25 near critical to critical fire weather conditions will be likely during the afternoon due to low humidity and gusty west winds. Some patchy blowing dust will also be possible. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 130 PM MDT Sat May 4 2024 High pressure in control today with light winds and mostly sunny skies. Tonight, return flow around the high begins with increasing southeasterly winds. Stratus will develop by 12z in the Kansas and Colorado border area, with perhaps some patchy fog, expanding across much of the area through the morning. HRRR suggests the low clouds will be slow to erode through Sunday afternoon in central and eastern portions of the area, potentially impacting temperatures. Hard to find much support for lower temperatures in guidance, so will only tweak temperatures down a few degrees in eastern areas. It will also be windy with south to southeast winds gusting over 40 mph in western areas by the afternoon as a trough deepens in eastern Colorado. Lows tonight will be in the lower 40s and highs on Sunday in the 60s in the aforementioned cooler areas to the lower 70s in western areas with some afternoon sun. Sunday night will see those winds continue to increase. Models may be over mixing, particularly the GFS, but still going to be breezy to windy south winds through the night. Upper trough axis will be in central Colorado by early Monday morning. May see scattered showers begin to develop overnight Sunday with an isolated thunderstorm or two with favorable MUCAPE. As upper trough lifts into the Nebraska panhandle Monday morning westerly winds will overspread the area aloft and at the surface. Dry line will race eastward in the morning and by 18z probably be all the way to Highway 83. There is a short window, between about 16z and 20z, when the dry line may still be in the area and thunderstorms may initiate. Forecast soundings from the NAMnest, which initiates storms on the dry line in the eastern six counties, shows around 1500 j/kg of SBCAPE and 60 kts of 0-6km shear, which should be sufficient for a severe risk of large hail, damaging winds and perhaps a tornado. Meanwhile, west of the dry line it will be dry and windy with a risk for critical fire weather conditions. Lowest humidity will be south of Interstate 70 and west of Highway 25 with high probabilities for relative humidity of 15% or lower and for wind gusts of 25 mph or higher. However, models not in the best of agreement on potential for meeting high wind warning criteria. NBM probabilities for gusts of 55 mph or greater are generally confined to Colorado during the morning at 20-30 percent, decreasing in the afternoon. Finally, low level lapse rates west of the dry line are favorable for blowing dust, but wind gusts a bit lacking, and recent rainfall may negate some of the potential as well. Precipitation should be done for the area by Monday afternoon. Highs will be in the lower 70s and lows Monday night ranging from the upper 30s in Colorado to the lower 40s in eastern areas. On Tuesday, the upper low will be in the northern plains with zonal flow across the central plains. It will be breezy to windy and dry. Critical fire weather conditions may be met once again, but potentially more widespread compared to Monday with just about the entire area dropping into the teens for humidity in the afternoon. High temperatures will be in the 70s and lows Tuesday night ranging from the middle 30s in Colorado to the lower 40s in eastern areas. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Issued at 130 PM MDT Sat May 4 2024 Upper low in the northern plains will be the dominant feature Wednesday through Friday. Occasional shortwave energy rotating around it will bring low chances for showers and thunderstorms. However, moisture will be lacking, dew points in the 20s on Wednesday and 30s on Thursday and Friday, so no severe storms are anticipated. With those low dew points on Wednesday and continued gusty west to northwest winds may see another day of critical fire weather across parts of the area. Highs will be mainly in the 60s and lows in the 30s and 40s each day. By Saturday appears the upper low will finally lose its influence over the area with shortwave ridging ahead of the next system in the Great Basin. Temperatures will warm up slightly with highs in the 60s and 70s with only low chances for an afternoon shower or thunderstorm with a weak wave coming over the ridge. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1002 PM MDT Sat May 4 2024 For KGLD, conditions start as VFR through about 08z Sunday, then transition to MVFR with 5-6sm in fog and ceilings around BKN015-025. VFR do not return until 03z Monday onward. Winds, southeast 10-15kts, increasing to around 25-35kts from 17z Sunday onward. For KMCK, VFR conditions through much of the forecast period, with MVFR ceilings(BKN015-020) working into the area by 00z Monday. Winds, southeast 10-15kts through 17z Sunday, then increasing to around 20-30kts. LLWS 00z-06z Monday 160@45kts. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ SHORT TERM...24 LONG TERM...24 AVIATION...JN
Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1028 PM CDT Sat May 4 2024 .KEY MESSAGES... - Scattered thunderstorms will develop this afternoon west of Interstate 57, mainly between 3pm and 9pm. The potential severe weather hazards include hail to the size of ping pong balls and damaging wind gusts up to 60 mph. - Confidence is medium that hazardous weather will occur both Tuesday and Wednesday as a pair of disturbances track across the region, bringing periods of thunderstorms. && .UPDATE... Issued at 807 PM CDT Sat May 4 2024 A cold front is working across central Illinois this evening with a line of showers and thunderstorms preceding the front. In addition, a gust front has surged ahead of the leading edge of storms and is kicking up some dust resulting in lowered visibility in some areas. Overall, the severe threat has diminished from earlier and will continue to trend down, but will need to continue to monitor for a stronger storm or two over the next couple hours. Gusts of 40 to 50 mph will be possible in spots with the strongest storms. Leading edge of the storms should clear the forecast area by around 1000/1030 pm with precip chances ending altogether in the following hour or two. Behind the front, breezy northwest winds are overspreading the Illinois River Valley with upstream dewpoints in the 40s expected to work across at least the Illinois River Valley through the night. Deubelbeiss && .DISCUSSION... Issued at 141 PM CDT Sat May 4 2024 ********************************************************************* Today`s Severe Weather Potential: ********************************************************************* Up until this point, two limiting factors for afternoon convective coverage has been the idea that deep-layer shear is somewhat underwhelming (30 kts or less), and that synoptic forcing atop the cold front is somewhat nebulous. If true, then updrafts may struggle to get organized or struggle to stay organized -- thus limiting the severe risk. However, we have recalibrate our expectations due to a decaying MCV currently lifting across northeast Missouri. MCVs notoriously augment forcing and vertical wind profiles, and it bears watching over the next couple hours. If this feature can hold together as it crosses the mid-Mississippi Valley, then convective coverage should become greater than previously anticipated. A quick glance at the RAP-derived parameter space suggests the mesoscale environment this afternoon will be sufficiently unstable as steepening 0-3 km lapse rates and good solar insolation work to erode convection inhibition. SBCAPE values are now progged to be 2000-2500 J/kg ahead of the cold front; which is a notable increase from yesterday`s modeled instability. This all adds up to increased confidence in severe weather coverage this afternoon and early evening in areas west of I-55. The primary severe weather hazards are still hail and wind, and recent HRRR guidance suggests that the latter could be the more formidable feature as cold pools strengthen ahead of the front. Any attendant flash flood risk with storm activity looks low. The 3- hr flash flood guidance in areas west of I-55 is currently between 1.5" - 2.0". When overlaying the HREF 3-hr PMM QPF, this same area only achieves 0.5" - 1.0". It`s at least worth noting that recent runs of the HRRR offer a couple localized QPF pockets of 1.75", but any flash flooding that occurs would be the exception and not the rule. Our expectation is still for severe convection to fade after sunset, as the lack of an appreciable LLJ will make it difficult for storms to maintain their punch. ********************************************************************* Tuesday-Wednesday Severe Weather Potential: ********************************************************************* A seasonable and otherwise low-drama forecast has been drawn up for Sunday and Monday, but concern quickly focuses on the convective potential unfolding during the Tuesday-Wednesday timeframe. Global deterministic guidance continues to resolve a synoptic pattern favorable for a multi-day severe weather outbreak, and this signal is reflected in other analogs (CIPS) and machine learning tools (CSU MLP Severe). In a sentence or two, we`re monitoring the evolution of what looks to be a deepening upper-level low positioned over the Northern Plains by Monday night, with a strong jetcore nosing into the Mid- Mississippi Valley above multiple shortwaves traversing meridional flow. This combination of strong forcing, strong kinematics, and favorable thermodynamics evolving in deep southwest flow could lead to widespread severe weather within a broadening warm sector. Our confidence at this time is only medium, as we cannot possibly imagine how certain mesoscale processes (convective feedback, debris, outflow boundaries, etc) evolve in time and space. But, the synoptic setup currently being modeled for Tuesday-Wednesday is concerning. When leveraging our 100-member ensemble comprised of the GEFS, EPS, and CMCE to assess a favorable parameter space for supercell development (SBCAPE > 1000 J/kg, SBCINH > -75 J/kg, and bulk shear > 40 kts), we see a 50-70% chance of achieving these conditions on Tuesday in areas along and south of I-72. When looking toward Wednesday, we see probabilities of 50-60% in areas south of I-72. And so while the emphasis appears to currently favor the southern half of our CWA on both days, our confidence is only medium. The severe weather outlook will undoubtedly change in coming days, so do check back. MJA && .AVIATION... (For the 06z TAFs through 06z Sunday Night) Issued at 1028 PM CDT Sat May 4 2024 A cold front has pushed across central Illinois leaving NW winds in its wake. NW winds in place overnight will veer to the NE Sunday morning and east Sunday evening. MVFR ceilings are expected to develop across portions of the area, mainly along and east of I-55 overnight into Sunday morning, but any ceilings should scatter back to VFR by around midday Sunday. Deubelbeiss && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Jackson MS
1033 PM CDT Sat May 4 2024 ...New MESOSCALE UPDATE... .MESOSCALE UPDATE... Issued at 1030 PM CDT Sat May 4 2024 Rest of tonight... Evening RAP analysis/GOES East water vapor imagery westerly flow aloft across the region, with dwindling rain chances. Stronger shortwave ascent is again leading to ascent & GOES East infrared imagery indicate MCS/cold cloud tops across the southern Plains. PWs have come up across the region but most convection has died down. Clouds will gradually fill in from the west, with rain after daybreak, but moist southeasterly boundary layer flow will pick up before then. Lows will fall into the mid-upper 60s, with crossover temps not as as much as last night & focused more into southern-southeast MS. This pattern supports low stratus & dense fog developing overnight across the Hwy 84 to I-59 corridors. HREF probs >15-30% expanding up to near the I-20 corridor, but some concerns with clouds lingering & high clouds later decrease some confidence. Convective allowing models (CAMs) indicate potential for areas of dense fog across the Pine Belt, mainly focused along & southeast of a line from Lincoln, Lawrence, Simpson, Smith, Jasper & Clarke counties in MS. Added a "Limited" in HWO graphics for patchy dense fog. Can`t rule out it expanding further north & being more areal coverage. Some HREF probs are hitting pretty hard in the 35-50% range in the Jefferson Davis to Jones & Marion to Forrest corridor. Held off on any "Elevated" or dense fog advisory for now. Updates are out. /DC/ && .DISCUSSION... Issued at 253 PM CDT Sat May 4 2024 Tonight through Sunday...Isolated showers/storms will be possible into the early evening hours, but will dissipate with skies becoming partly cloudy overnight. A short wave will move into the area on Sunday with more scattered showers/storms Sunday afternoon and evening. With decent instability, afternoon heating and at least some flow, strong to possibly severe storms will be possible mainly for areas along and north of the Natchez Trace Corridor. A graphic has already been issued for this potential. Highs will range from around 80 in the west to the upper 80s in the east. The storms will move east of the area during the evening hours. /15/ Monday through Saturday: As a closed low pressure system cuts off over the Northern High Plains through the early part of the work week, upper-level flow over the Southern CONUS will increase. Ripples in the flow interacting with a warm, moist air mass over the Gulf Coast will continue to support mainly diurnal showers and thunderstorms through midweek. Thursday into Friday, ridging over the eastern CONUS is expected to flatten and allow for shortwave energy to eject east across the Midwest and Great Lakes region. A cold front pushing south into our forecast area during this time frame will be a focus for additional shower and thunderstorm activity, eventually yielding to cooler and drier air with high pressure coming out of the Plains. /NF/ && .AVIATION... (00Z TAFS) Issued at 753 PM CDT Sat May 4 2024 Other than a few storms on the edges of the area in the northwest MS and southern MS, expect dissipation over the next hour or so. Some MVFR vsby due to BR are psbl around the area, with LIFR low stratus/dense fog expected overnight at HBG/PIB & psbl at MEI. Onset timing looks to be around 05/08-10Z before lifting to VFR flight categories around 05/14-15Z. Light southerly sfc winds will persist, sustained up to 10mph & brief higher gusts up to 15mph. Some light SHRA & iso TSRA are psbl Sunday aftn, with highest confidence for introduction at GLH & GWO for the 00Z TAF cycle. There are low probs at GTR, JAN, HKS & HEZ after 05/20-21Z through the end of the period. /DC/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 65 84 67 86 / 20 50 30 30 Meridian 64 88 65 88 / 20 50 30 30 Vicksburg 66 83 66 86 / 10 50 30 30 Hattiesburg 66 88 68 88 / 20 30 10 20 Natchez 66 83 66 86 / 20 50 20 30 Greenville 67 80 68 84 / 10 60 60 30 Greenwood 66 83 67 85 / 10 70 60 40 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ DC/NF/DC
Area Forecast Discussion
National Weather Service Lake Charles LA
1007 PM CDT Sat May 4 2024 ...New UPDATE... .UPDATE... Issued at 1002 PM CDT Sat May 4 2024 Area radar shows a couple of thunderstorms moving into Hardin and Jefferson county at this time, with more activity back to our west. Short term models are still in good agreement with shower and thunderstorm activity increasing further after midnight (mainly for SE TX), followed by another MCS feature moving across the region tomorrow around sunrise. Therefore, only made some small changes to the hourly POP forecast over the remainder of the overnight period, just to fall more in line with current radar and CAMs trends. Otherwise, the forecast is on track. 17 && .SYNOPSIS... Issued at 356 PM CDT Sat May 4 2024 Scattered convection continues to develop across the area this afternoon in response to a subtle disturbance passing over the region. This activity continues to develop in a very moist airmass, with PWATs around 1.70 inches (around the 90th percentile per SPC Climo). Given the considerable moisture, some storms could be capable of producing heavy rainfall and very high rain rates, potentially aggravating ongoing flooding across SE TX. So far today, a few small cells have produced heavy rains, yielding increased flows per FLASH data, but convection has not been particularly robust and the generally progressive nature has helped limit flash flooding. Otherwise, the rainy pattern is expected to persist with another disturbance moving into the region tonight into Sunday. A Flood Watch has been issued for our SE TX Counties, as any additional rain over the saturated ground will contribute further to ongoing flooding. 24 && .SHORT TERM... (Tonight through Monday night) Issued at 356 PM CDT Sat May 4 2024 This afternoon`s convection is expected to diminish by early this evening. The next round of showers and storms will be forming across TX and moving into the area later tonight after midnight. Rain chances will expand and increase from west to east overnight into Sunday. PWATs are progged to remain elevated across the region (peaking between 1.6 and 1.7 inches, or slighter higher). Sufficient lift, instability and deep layer shear will support organization and strong updrafts to allow for both heavy rainfall and a low end severe threat. A few isolated storms could produce a damaging wind gust or two as well as some marginally severe hail, although convection will likely weaken as it progresses east. SPC has outlined a MRGL risk for severe weather given this scenario. The more impactful threat however continues to be the potential for heavy rainfall over an area that is already saturated, with moderate to major river flooding ongoing. WPC has outlined much of our SE TX areas with a MDT risk for excessive rainfall tonight into Sunday. The HRRR, ARW and HREF show some of the highest rainfall accumulations across Tyler, Hardin and Jefferson Counties (areas that have already received between 8 and 12 inches of rain over the past week). At this time, blended guidance and WPC suggest area totals of 1 to 3 inches of rain across this area, but localized higher totals of up to 6 inches will certainly be possible (possibly higher if some guidance members verify). There is still some uncertainty when the rain chances will finally begin to decrease as the HRRR and ARW suggest one last cluster of convection will move through early Sunday evening. Rain chances should begin to diminish after midnight Sunday night, but some low chances will develop again with daytime heating on Monday. 24 && .LONG TERM... (Tuesday through next Friday) Issued at 356 PM CDT Sat May 4 2024 At the start of the extended period low pressure will be across the northern plains with weak ridging across the northern gulf coast into the Atlantic. This is anticipated to produce dry but breezy conditions across the local area for Tuesday and Wednesday. Temperatures are also expected to run several degrees above climo normals for the date. Late in the week, an upper trough and associated surface low will move across the upper midwest and Great Lakes region. This may push a cold front to the gulf coast by Friday, however ahead of the boundary, compressional heating may nudge high temperatures in the 90s north of I-10 Thursday afternoon. Showers and storms may be possible along the boundary, but overall coverage is only forecast to be in the 10 to 30% range at the current time. Drier and cooler temperatures are forecast to filter in behind the boundary for the weekend. 05 && .AVIATION... (00Z TAFS) Issued at 638 PM CDT Sat May 4 2024 Generally VFR will transition to MVFR/IFR later this evening with increasing risk for Iso/Sct convection. Probabilities further increase after midnight and early morning hours, especially for KBPT and eventually KLCH. Later in the morning and early afternoon probabilities will rise for locales east of KLCH. Better timing and impacts for TAF locales will be issued later this evenign with updated high reoslution modeling. && .MARINE... Issued at 356 PM CDT Sat May 4 2024 A light to moderate onshore flow and seas two to four feet will prevail for much of the upcoming week. Scattered showers and storms are again expected to develop tonight into Sunday, then diminishing Sunday night with rain chances remaining limited through the week. 24 && .HYDROLOGY... Issued at 356 PM CDT Sat May 4 2024 River flooding is expected to persist for several days, and additional rainfall on Sunday may extend or worsen conditions within area basins. Moderate to Major Flooding continues within the Neches River basin, with major flooding occurring or forecast on the Village Creek near Kountze, the Pine Island Bayou at Sour Lake and at the Neches River Saltwater Barrier. Moderate flooding is also expected along the Sabine River from Bon Wier to Deweyville. Further east, flooding remains in minor category along the Calcasieu River. Please monitor updated forecasts via the NWS AHPS website and/or the new NWS NWPS webpage (https://water.noaa.gov/) as the river flood threat continues. 24 && .PRELIMINARY POINT TEMPS/POPS... AEX 67 82 66 85 / 30 60 20 30 LCH 71 83 71 84 / 20 40 20 20 LFT 71 85 72 86 / 10 40 20 20 BPT 72 82 71 84 / 30 50 20 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...Flood Watch through Sunday evening for TXZ180-201-259>262-515- 516-615-616. GM...None. && $$ SHORT TERM...24 LONG TERM....05 AVIATION...24
Area Forecast Discussion
National Weather Service Louisville KY
1110 PM EDT Sat May 4 2024 .KEY MESSAGES... * Isolated to scattered showers and thunderstorms are forecast this afternoon. Slow moving storm motion and moderate to heavy rain expected with any storm. * Isolated showers and thunderstorms are expected on Sunday before widespread rain chances return Sunday night into Monday. * Potential for multiple rounds of strong to severe storms next Tuesday through Thursday. Although confidence in timing remains low, all severe hazards will be possible. * Elevated flooding potential will exist where repeated rounds of heavy rainfall occur next week. && .UPDATE... Issued at 1109 PM EDT Sat May 4 2024 Over the past 90 minutes or so, there has been an uptick in thunderstorm activity across our westernmost counties, where latest SPC mesoanalysis delineates 500-1000 J/kg MLCAPE. It is also noteworthy that there are where the greatest amount of convection is currently ongoing has largely been rain-free this afternoon, and a relative minimum in CIN is observed in these areas. Finally, outflow from storms along the frontal boundary farther west has likely spurred this development to some extent, providing just enough mechanical lifting to raise initially stable parcels to their LFC. Over the next few hours, would expect convective activity to spread eastward across southern IN and west central KY, gradually diminishing after midnight as instability continues to wane. The only notable changes to the going forecast were tweaks to PoP grids over the next 3-6 hours. Otherwise, the forecast remains on track at this time. && .SHORT TERM /THROUGH TONIGHT/... Issued at 348 PM EDT Sat May 4 2024 ========== Rest of This Afternoon ========== Fairly moist atmosphere over the area, with precipitable waters around the 90th percentile. Storms have developed in this humid airmass, with best convective development where the MLCAPE per SPC mesoanalysis is over 1000 J/kg. Louisville ACARS most recent sounding shows a couple of small inversions, at ~800 mb and 700 mb, which may be inhibiting deeper development over the city. HRRR sounding forecast represents these inversions well and keep them in place through the afternoon. Thus will keep the best chances for storms east of the i-65 corridor. ========== Tonight ========== Showers/Storms from the afternoon should steadily decrease this evening. Cannot rule out some isolated development in the moist airmass. Should be another mild night as dewpoints remain elevated and lows by Sunday morning should be in the low 60s. Model progs keep clouds around overnight and thicken/lower them during the morning hours. ========== Sunday =========== How long those low clouds hang around in the morning and early afternoon hours will have a direct influence on afternoon convection. Have bumped PoPs down a touch, with the better chances south and east of a Russellville to Bardstown to Frankfort line. Some CAM`s have gone dry for the afternoon, but given potential for some breaks in clouds and precipitable waters still above normal, though not as much, feel prudent to keep in some storm chances. Temperatures should rise into the 80`s for most places. && .LONG TERM /SUNDAY THROUGH SATURDAY/... Issued at 348 PM EDT Sat May 4 2024 Synopsis...A multi-day severe weather episode will be possible by the middle of the next week as an upper-level trough evolves and amplifies over the central US and eastern CONUS upper ridge axis transitions from the Great Lakes to the Mid Atlantic/Southeast US. The timing for best chances of severe weather will be tied to the progression of periodic, mid-level shortwave troughs rounding the base of the large through and embedded upper low. Eventually, continuous ejection of strong shortwave troughs will carry the main upper low energy towards the eastern CONUS while deeply amplifying once again due to further reinforcement from upstream Canadian troughing. Model Evaluation/Confidence...Confidence in large-scale features continue to be medium to high with expected decreasing confidence in timing and intensity of shortwaves ejecting ahead of the main upper low. The timing differences in incoming strong mid-level forcing could lead to great variability in convective intensity, coverage, and maintenance based on a potential onset time around sunset (both Tuesday and Wednesday) and the resultant distribution/amount of available daytime instability. Also, it is too early to pinpoint specifics about meso features that would certainly play an important role in initiation convection, such as the position of the residual outflow boundary on Tuesday afternoon/evening or the effect of previous convection and the interaction with approaching frontal wave on Wednesday. In any case, machine learning derived guidance has been consistently highlighting elevated probabilities of severe weather across the region for Tuesday and Wednesday, with a recent trend for higher probabilities for Wednesday. Sun Night - Monday...Increased shower activity along with some isolated storms are likely Sun night into Monday morning as a southern-stream shortwave trough moves from the southern Plains to the lower Ohio Valley. A combination of increased moisture advection and potentially slow storm motions/backbuilding could result in isolated accumulations over half an inch or more. On the other hand, warming mid-level temperatures and decreasing instability will limit thunder chances and promote more of a low-centroid type of storms. The vorticity wave will push a frontal wave stalled across the region to the north, so will keep mentioning reduced PoPs during the afternoon and evening. Tuesday - Thursday...Daily severe weather chances appear to focus around sunset and overnight every day. For Tuesday, a weakening cold front will move into the forecast area Tuesday morning and early afternoon and although there will be an increase in showers during the morning, it seems that forcing will subside substantially to reinvigorate convection. Nonetheless, the residual outflow boundary will establish somewhere along the Wabash Valley and into central Indiana, which could be the mesoscale focus for convection late in the afternoon and early evening as a surface low (ejecting across the Upper Midwest) drags a cold front to the southeast. Based on current guidance, highest severe probs will be close to the outflow boundary further north with a decreasing trend in convective intensity as it approaches southern Indiana and north-central Kentucky. On the other hand, Wednesday looks more threatening as the front will be located closer to the forecast area and the second mid- level shortwave energy brings a surface low across the Wabash Valley and IN. Therefore, forcing will be significantly higher amid a moderately high unstable warm sector and sufficient deep-layer shear for organized, spinning updrafts. All severe hazards are on the table as well as a risk of flooding given the possibility of repeated rounds of heavy rainfall. Friday - Sunday...Amplifying trough over the eastern CONUS will push the cold frontal and associated unsettled weather activity south of the forecast area. As a result, rain and storm chances will decrease during the day on Friday with breezy NW winds and persistent low- level cloud cover the rest of the day. Temperatures during the weekend seems to fall near or slightly below normal under light NW breeze and partly to mostly skies. A more stable airmass will indicate dry conditions for Saturday and Sunday. && .AVIATION /00Z TAFS THROUGH 06Z MONDAY/... Issued at 802 PM EDT Sat May 4 2024 We currently have a line of thunderstorms in central Illinois. The line is oriented north to south and will continue traveling to the east. The line is expected to impact the area of HNB and could make it to SDF later tonight. Ceilings around convection have been bouncy, but later tonight/ early tomorrow morning, expecting MVFR to IFR stratus to develop over southern Indiana and central Kentucky. Ceilings during this time could also see some jumping around between VFR and IFR levels. Winds will remain light and slowly begin veering towards the west tomorrow. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE...CSG SHORT TERM...RJS LONG TERM...ALL AVIATION...KDW
Area Forecast Discussion
National Weather Service Memphis TN
945 PM CDT Sat May 4 2024 ...New UPDATE... .UPDATE... Issued at 929 PM CDT Sat May 4 2024 Fairly quiet this evening as mid level shortwave ridging spreads into the region ahead of the next disturbance moving toward the Arklatex. Fog is the main concern once again this evening. Best chances appear to be across the TN River Valley and NE MS where dewpoint depressions are already 1 degree or less. Confidence is not quite as high as last evening since the HRRR has not really jumped on board yet. Ongoing forecast handles it well and we will monitor fog development for potential Dense Fog Advisory later tonight. The next disturbance will swing through on Sunday afternoon with numerous showers and thunderstorms. A few severe storms are possible with gusty winds and large hail. && .SYNOPSIS... Issued at 326 PM CDT Sat May 4 2024 Warm and humid conditions will support scattered to numerous showers and thunderstorms through the middle of next week. A few severe thunderstorms will possible on Sunday, as an upper level disturbance lifts from Texas into the lower Mississippi River Valley. Severe thunderstorm chances will increase by midweek, ahead of a deep upper level low pressure system moving through the Great Plains and mid-Mississippi River Valley. A cold frontal passage on will bring cooler and less humid conditions to the Midsouth by next weekend. && .DISCUSSION... (This evening through next Friday) Issued at 326 PM CDT Sat May 4 2024 An active weather pattern is ahead for the Midsouth through the middle of next week. A convectively- enhanced shortwave will lift from west central Texas into the western Ozarks by midday Sunday. Mixed layer CAPE over the Midsouth will increase to 1000-1500 J/kg. 0-6km bulk shear will prevail at 20-30kt, relatively modest but about double that of today. This will support a marginal severe threat by midmorning Sunday. Damaging winds, hail and heavy rainfall appear to be the primary threats. Given the projected timing of the shortwave, storms should exit and/or diminish by Sunday evening. Monday should be relatively quiet under shortwave ridging. But the ridge axis will be east of the area Monday evening, opening the door for storms to enter the Midsouth from southern AR, aided by a 40kt low level jet. Severe thunderstorms are appearing more likely Tuesday and Wednesday, aided by height falls associated with a deepening northern branch longwave trough over the western two-thirds of the CONUS. Low level return flow will strengthen in response, driving surface dewpoints to around 70F over the Midsouth. The increased low level moisture will drive surface-based CAPE in excess of 2500 J/kg Tuesday afternoon, accompanied by 0-6km bulk shear around 45kt north of I-40. With strong southerly flow continuing, the lower atmosphere should recover Wednesday from Tuesday night storms. An upper level trough axis, pendant from a closed low over eastern Nebraska, will pivot through the Ozarks Wednesday afternoon and evening, driving height falls and enhancing frontal convergence over the lower Ohio River Valley and Midsouth. Surface-based CAPE will peak around 3000 J/kg Wednesday afternoon, before moderating below a still impressive 1500-2000 J/kg Wednesday evening. GFS and ECMWF mean 700-500mb lapse rates are progged at an impressive 8 C/km Wednesday afternoon and evening. Given the projected CAPE, this would be supportive of very large hail, at least during the afternoon. Given the tendency for prefrontal veering of low level winds, convection may transition to a linear mode Wednesday evening, perhaps reducing the large hail and tornado threat, but enhancing the flash flooding threat. Projected PWAT is around 2 inches, about as high as it gets this time of the year. Quieter weather should prevail Thursday, following the passage of the convectively-reinforced cold front. Another cold frontal passage appears likely on Friday, as a deep longwave trough sets up briefly over the eastern CONUS. This should bring relatively cool and dry conditions to the Midsouth next weekend. PWB && .AVIATION... (00Z TAFS) Issued at 710 PM CDT Sat May 4 2024 Near term aviation concerns pertain to the development of reduced visibilities, ceilings, and possible fog overnight as winds go calm and variable. High resolution CAM guidance depicts a line of showers and thunderstorms that will move through the airspace sometime tomorrow afternoon. Have elected to use a PROB30 for now with respect to this situation until further details can be resolved. && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$ PUBLIC FORECAST...SJM AVIATION...JPR
Area Forecast Discussion
National Weather Service Shreveport LA
1044 PM CDT Sat May 4 2024 ...New UPDATE... .UPDATE... Issued at 1033 PM CDT Sat May 4 2024 Not much change from previous forecast for this evening into the overnight hours. A large complex of showers and thunderstorms have formed across portions of West and North-Central Texas. The HRRR, which seems to have a good handle on this set-up, continues to suggest this complex will form into a MCS and shift eastward towards the region during the overnight hours. Can`t rule out an isolated strong to severe thunderstorm, with damaging winds and large hail being the primary threat. Moderate to heavy rainfall can also be expected. Although WPC has a Moderate Risk for excessive rainfall across portions of Deep East Texas and a Slight Risk for a large portion of the region, decided to hold off on a Flash Flood watch at this time. RFC Flash Flood Guidance suggest we can handle the expected amount of QPF, but this will need to be monitored closely. Otherwise, expect overnight lows in the mid to upper 60s. /20/ && .SHORT TERM... (This evening through Sunday Night) Issued at 310 PM CDT Sat May 4 2024 A few showers and thunderstorms will persist through early this evening, mainly across portions of Angelina, San Augustine, and Sabine Counties along a stalled surface boundary. Most of the heavier storms should remain south of the CWA. Farther north, more isolated convection associated with a shortwave trough approaching the Mississippi River should exit the area by early this evening. In fact, most of the ongoing precip should end by sunset. However, this break will only be temporary. Another complex of strong to severe thunderstorms is expected to develop across West Texas this evening and tonight as the next shortwave trough strengthens while ejecting northeast across Texas and towards the ArkLaTex. The HRRR and HREF have tended to perform the best over the last couple of days, so this forecast more closely follows those models versus the NAM, GFS, and ECMWF. This is also results and earlier time of arrival of the leading edge of the storms into Southeast Oklahoma and East Texas, which should be between 05z-09z (midnight-4 AM CDT)tonight/Sunday morning. This complex should weaken somewhat with eastward extent across the forecast area Sunday morning, but an isolated severe weather threat cannot be ruled out. Damaging winds and large hail should be the main threat. The forecast becomes more uncertain after mid to late Sunday morning. The HRRR suggests a notable lack of convection across most of the CWA with the exception of the far northern and far southern zones, probably because the atmosphere should be worked over. However, there may be some recovery during the day, which should allow for renewed, and likely more scattered development. This is most likely across Southeast Oklahoma, Southwest Arkansas, and Northeast Texas where lift will be maximized with the shortwave trough. Farther south, a series of thunderstorms complexes with the potential to produce locally heavy rain is possible as a secondary wave in the flow aloft moves across Southeast Texas. Current thinking is that most of this convection should remain just south of the CWA. It is somewhat concerning, and worth noting, that the NAM brings this heavy rain threat into Deep East Texas Sunday afternoon, which would increase the risk for flooding. There is a moderate risk for excessive rainfall in portions of Deep East Texas on Sunday per WPC. For our area, this appears to be associated mainly with the morning convection. While locally heavy rain is possible, the risk for flooding is expected to be short-lived and localized at this time, especially as compared to areas just south and southwest. Therefore, we opted to forego issuing a Flood Watch. Overall, an additional 1 to 3 inches of rainfall, with locally higher amounts, are possible through Sunday evening in Deep East Texas. Rain chances should finally diminish from southwest to northeast Sunday night and early Monday morning. CN && .LONG TERM... (Monday through next Friday) Issued at 310 PM CDT Sat May 4 2024 Strong southwesterly flow aloft associated with a powerful upper low across the Northern Plains combined with a deep low-level southerly flow will keep a rather abundant pool of moisture throughout the atmospheric column. With a cold front northwest of the area, this will keep near daily chances for scattered convection in the forecast for much of next week. Sufficient instability and deep layer shear will also result in at least some threat for severe storms each day. The highest rain chances and corresponding chances for severe weather should be Wednesday and possibly into Thursday as a cold front finally approaches and moves across the area. The greatest coverage and best rain chances can be expected in the afternoons and evenings. Surface ridging should finally build into the area by Friday and into Saturday providing enough subsidence and dry air advection to bring most of our rain chances to an end. While the deterministic GFS and ECMWF remove all chances for rain, the ensembles and the NBM still keep some light QPF and slight chances for rain in the forecast as one more shortwave trough dives south along the Mississippi River to start the weekend. With the strong southerly surface flow at the beginning of the week, strong warm air advection can also be expected. With showers and thunderstorms being more of a scattered nature, temperatures will be able to climb ever upwards. Confidence continues to increase regarding unseasonably high temperatures, especially next Tuesday through Thursday. NBM probabilities of high temperatures of at least 90 deg F are now on the order of 80 to 90 percent in some portions of Louisiana by Wednesday. With peak heat index values near the century mark, the hot and humid conditions will be more typical of mid June versus early May. CN && .AVIATION... (00Z TAFS) Issued at 707 PM CDT Sat May 4 2024 Skies are anticipated to fall overnight, as clouds and rain move back into the region by tomorrow morning. Widespread MVFR and IFR CIGS should return by 05/10z, with RA and SHRA following shortly after. There is a chance for some thunderstorms tomorrow afternoon, but confidence was not high enough to introduce TS at this time. /44/ && .PRELIMINARY POINT TEMPS/POPS... SHV 69 79 68 85 / 70 100 30 40 MLU 69 80 66 86 / 20 60 40 40 DEQ 67 73 63 80 / 70 100 30 30 TXK 69 75 66 84 / 70 100 40 40 ELD 68 76 63 83 / 30 80 40 40 TYR 68 79 68 85 / 90 80 20 20 GGG 69 78 67 84 / 90 100 20 30 LFK 68 80 68 86 / 80 100 10 20 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ SHORT TERM...09 LONG TERM....09 AVIATION...44