Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/07/23

Area Forecast Discussion
National Weather Service La Crosse WI
739 PM CDT Sat May 6 2023 .DISCUSSION...(This evening through Saturday) Issued at 220 PM CDT Sat May 6 2023 Key Messages: - Another round of showers, storms this evening - a few could be strong. Isolated severe not out of the question, but a lot of uncertainties that would have to play out "just right" for severe to be realized this far north (locally that would be northeast IA/southwest WI) - Second round of showers and storms Monday afternoon into Monday night. Severe is possibility depending on how far north surface boundary lifts northward. At this time...not expecting any widespread severe for forecast area Tonight and Monday * ANOTHER ROUND OF SHOWERS AND STORMS THIS EVENING: some could be strong with small hail. While organized severe weather is not expected, as isolated severe risk does exist - mainly northeast IA/southwest WI if uncertainties in the forecast play out just right. An upper level shortwave trough was triggering showers and storms across northern IA/southern MN early this afternoon, on the edge of the elevated instability gradient. CAMS models continue to blossom this convection through the rest of the afternoon hours, spreading it east/northeast with the elevated instability following suit. Stout cap per bufkit soundings should inhibit any sfc based convection, but 500-1000 J/kg of MUCAPE to play with, enough for a few storms. Some shear to work with in the 1-7km layer that, coupled with the CAPE, could bear out a few stronger storms with small hail. That said, the low level jet is expected to kick off more convection across southeast IA by mid evening. These storms will be able to tap much more instability and could start out sfc based, but likely become more elevated as the push northward. With more favorable instability, good elevated wind shear, and in a plume of low level moisture transport, these storms would pose a higher threat to become severe. The near term guidance is at odds with how far northward this convection could make it - but the latest HRRR suggests parts of northeast IA/southwest WI could be on the northward fringe. Timing would be late evening. It`s a scenario to keep an eye on, but with a lot of uncertainties that would have to come together to pan out. All and all, widespread showers and storms are expected from late afternoon through the evening, a few could be strong, with most of the activity exiting into eastern WI after 06z. Sunday night into Tuesday Next shortwave trough moves along of surface boundary over Iowa late Monday afternoon into Monday night. Main concern will be how far north surface boundary lifts north for potential storms to be severe over the far southern forecast area. The 06.12z GFS/NAM suggest 0- 6km most unstable CAPE 100-1500 j/kg over the southern forecast with the higher elevated CAPE over southern Iowa. Shear looks to be marginal with 0-3km around 25 knots. However models do differ on how far north surface boundary lifts north into Iowa. At this isolated storm is possible to become severe. If surface front lifts further north...southern area of forecast may see a few more severe storms and the main threats would be damaging winds and hail. With boundary nearly stationary across southern Iowa Monday and the combination of weak forcing/moisture convergence across forecast area. This will linger showers and the potential for scattered storms during the daytime hours Monday. Storms are not expected to be severe...due to the weak forcing and instability along/north of the surface boundary. Surface ridge builds into the northern parts of the forecast area and moisture transport/convergence weakens considerably over the forecast area during the day Tuesday. Shower/storm chances diminish across the forecast area and are confined over northern parts of the forecast area. Tuesday night into Saturday Main forecast concerns through the forecast period Tuesday night through Saturday are shower/storm chances through the period. An active weather pattern continues through the forecast the latest ensembles/deterministic models suggest southwesterly flow aloft across the central United States. Pieces of energy embedded in the southwesterly flow aloft will move into the Upper Midwest/Upper Great Lakes. This will produce periodic chances for showers/storms through much of the period. The ensembles/deterministic models indicate one or two days could be dry. However...timing of the pieces of energy and the potential for a day or two of dry weather is the main issue during the forecast period. Temperatures will be above normal...with highs climbing into the upper 60s to 70s through much of the forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 738 PM CDT Sat May 6 2023 CIGS: MVFR/IFR/LIFR conditions look to continue through this evening and overnight. Current observations show some lifting of ceilings just south/southeast of KLSE, but guidance would suggest enough low level moisture to allow MVFR ceilings to fill back in. With this, have kept KLSE at MVFR for now this evening and will monitor trends. Some improvement looks possible Sunday morning/afternoon. WX/Vsby: Showers with some storms have continued this evening, with CAMS models suggesting these showers will continue to develop across the area. Looking at latest trends in CAMs there was lower confidence in spatial coverage of the showers/storms especially at KLSE, although guidance does still suggest rain will move east of KLSE around 06Z. Much of the thunder/lightning so far has remained with the storms north/northeast of KRST/KLSE this evening, but satellite will be closely monitored if tempo groups may need to be added. Continued the lower visibility with the potential for fog, especially west of the Mississippi River. Winds: Winds look to become light and variable through the overnight, with winds remaining less than 10 kts through the day Sunday. && .HYDROLOGY... Issued at 220 PM CDT Sat May 6 2023 Levels along the Mississippi River continue to fall and all the sites that remain in flood are now only experiencing minor flooding. While on and off rain is expected for the next couple of days, it will not be enough to prevent the river from continuing to fall. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ DISCUSSION...DTJ/Rieck AVIATION...EMS
Area Forecast Discussion
National Weather Service Boston/Norton MA
944 PM EDT Sat May 6 2023 .SYNOPSIS... Beautiful weather with warm afternoons continue Sunday and Monday with dry weather persisting...outside of a period of showers that may impact mostly interior southern New England. Dry weather returns Monday and Tuesday outside a spot shower Tuesday evening, but a backdoor cold front will cast a cool spell on southern New England mid week, with temps just below average for early May. Warm and dry conditions redevelop to round out the week and start next weekend, though a few showers can`t be ruled out sometime Friday evening. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 10 PM Update... Forecast remains mostly on track at this our. Temperatures have been a bit slow to fall after a warm day, so made some slight changes to the near-term temperature forecast to reflect latest trends and observations. Otherwise no major changes are needed with this update. 410 PM Update... * Dry & tranquil tonight with overnight lows in the 40s to lower 50s A ridge of high pressure will remain in control of our weather tonight. Mainly clear skies with winds becoming light/calm after sunset coupled with a dry airmass in place will yield a good night of radiational cooling. Overnight low temps should bottom out in the lower to middle 40s in the normally coolest outlying locations...while the urban Heat Island of Boston will only drop into the lower/middle 50s. Might be a touch of brief very localized patchy ground fog late in the typically prone locations...but certainly nothing widespread. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Highlights... * Beautiful Sunday with just mid-high clouds & highs in the 70s * Round of showers possible Sun night...greatest risk interior MA/CT Details... Sunday... Another beautiful day is on tap to close out the weekend on Sunday. We will remain in dry northwest flow aloft with 925T generally in the +14C/+15C range by late in the day. There will be some mid-high clouds especially across the interior during the second half of the day...but still expect plenty of sunshine. This coupled with a dry/well mixed atmosphere in place will result in afternoon highs into the middle 70s across much of the region. A few degrees cooler in the high terrain and parts of the Cape/Islands...but still a beautiful day. Winds will generally in the 10 to 15 mph range. Sunday night... The synoptic pattern favors MCS development during the day Sunday across the eastern Great Lakes and into parts of the Appalachians. This is on the eastern edge of the upper level ridge axis. The biggest uncertainty is how far east this MCS and its associated precipitation shield make it. The NAM/HRRR guidance are furthest east and most aggressive bringing a period widespread rain to the region on the order of 0.25 to 0.50". Most of the other guidance is further west/light with the precipitation. This will result in a round of lighter showers...confined to mainly our interior zones with little or no rain at all across eastern MA. We are favoring the shield of showers being further west & lighter than what the NAM & HRRR depict. The reasoning is that these MCS/s tend to gravitate further southwest towards the greater instability. So thinking is a round of light showers may impact our region...mainly across our interior zones. Overnight low temps should generally be in the upper 40s to the lower 50s. && .LONG TERM /MONDAY THROUGH SATURDAY/... Highlights * Mild and Dry Monday * Potential for back door cold front to drop temperatures just below normal mid week; outside chance for a shower south of I-90 * Mild temperatures return to round out the week/start next weekend Monday... As we remain just east of the ridge centered over the Ohio Valley, scattered showers early Monday morning will give way to rapid clearing by late Monday morning, setting up for another mild, dry day! Given persistent NW, downsloping, flow and the fact that temperatures overachieved today (Saturday), we opted to bump temperatures up a bit compared to NBM, as the previous shift did, across the interior for Monday afternoon. Highs will likely range in the mid to upper 70s away from the coast. Boundary layer winds appear to be just high enough to stave off a seabreeze, but we would be remiss to not at least mention that seabreeze development is possible along the immediate coastline, which could potentially snarl the temperature forecast across coastal Massachusetts with much cooler highs than forecast thanks to still chilly SSTs. Hi-res guidance over the next 48 hours will be especially helpful in determining sea breeze potential! Opted to lower temperatures overnight Monday into Tuesday given solid radiational cooling conditions develop. With that said, mid to high cloud cover, mainly south of I-90, could have an impact on overnight lows. Tuesday and Wednesday... Retrograding low pressure across the Canadian Maritimes will introduce a back door cold front to southern New England on Tuesday and Wednesday. Temperatures will be highly dependent on how far southwest the low wiggles, but anticipating slightly below normal temperatures are on the table; in the upper 50s/low to mid 60s, given flow will be more northerly than northeasterly. Additionally, there is a shot for a few showers Tuesday afternoon into Wednesday morning as weak shortwave/potential MCS feature dives to our southwest along the spine of the ridge. Given the best instability is located well to our south, anticipating that we won`t see much more that a spot shower, with the best chance for precipitation being across CT. Thursday and Beyond... Above normal temperatures return Thursday under sunny skies as the ridge finally builds east into our area as the persistent mid level low over the Canadian Maritimes pulls east. Warming temps aloft will build in from the west, allowing highs to warm well into the 70s Friday; a reading of 80 can`t be ruled out! Warm and mainly dry trend looks to continue into the weekend, though some global guidance, namely the GFS, hints at some shower activity Friday evening thanks to a weak "last-gasp" shortwave rotating around the departing low to our east. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 00z TAF Update... Tonight...High Confidence. VFR. Winds becoming light from a WNW direction and may eventually completely decouple in the typically prone spots overnight. Some radiation fog is possible at Valley terminals such as Orange and Barnes-Westfield if winds go calm overnight; the best chance for any patchy fog will be between 09-12Z, with any FG/BR burning off quickly after sunrise. Confidence in fog formation is low, with high confidence that there will be NO fog at our the more commercial terminals of BOS, PVD, and BDL. Sunday...High Confidence. VFR. WNW winds 5 to 15 knots becoming WSW late. Sunday night...Moderate Confidence. Mainly VFR but a period of MVFR conditions are possible in a round of showers. Greatest risk for this will be across interior MA & CT. Calm/light W winds. KBOS Terminal...High confidence in TAF. VFR through the period. Winds from the NW becoming more WNW and W for Sunday. Winds 10-15kt should be strong enough to stave off a seabreeze Sunday. Clouds will increase but CBs will stay above about 6000ft, thus, no impact to flight categories expected. Slight chance of light rain showers after 02Z Monday. KBDL Terminal...High confidence in TAF. VFR through 00Z Monday, chance for MVFR after 00Z in rain showers. Winds go near calm overnight before becoming about 10 kt Sunday from the W/WNW. Shower activity will pick up after 00Z Monday, with light rain expected at the terminal. Rain will end, and any subsequent MVFR will become VFR, by 12Z Monday. Outlook /Monday through Thursday/... VFR. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight through Sunday night...High Confidence. Weak pressure gradient will keep both winds and seas below small craft advisory levels through Sunday night. Winds will generally be from a WSW direction with some gusts between 15 and 20 knots at times. Excellent Vsbys the majority of the time too. Outlook /Monday through Thursday/... Monday through Monday Night: Winds less than 25 kt. Tuesday: Winds less than 25 kt. Slight chance of rain showers. Tuesday Night through Thursday: Winds less than 25 kt. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Frank/KS NEAR TERM...RM SHORT TERM...Frank LONG TERM...KS AVIATION...Frank/KS MARINE...Frank/KS
Area Forecast Discussion...Updated
National Weather Service Billings MT
805 PM MDT Sat May 6 2023 .UPDATE... Updated PoPs this evening for current trends. Upper shortwave within the mean S/SW flow is moving across central zones at this time creating low level frontogenesis from Musselshell southward toward Colstrip. Some thunderstorms have recently developed in this area in response, and are pretty healthy with radar indicating small hail (.25-.5 ins). They appear anchored along that frontogenesis zone and may produce some heavy rain as well before shifting E/NE. Heavy rain was reported near Brandenburg earlier with small hail blanketing nearby hills. Small hail and lots of rainfall in the Broudus vicinity as well today. BT && .DISCUSSION... Tonight through Sunday Night... Shortwave lifting thru northeast WY along with convergent low level winds and 200-500 j/kg of mlcape is producing areas of showers and isolated thunderstorms near Sheridan and mainly east of Rosebud County...though some notable cu are starting to develop west of this area. The risk of t-storms with brief heavy rain and small hail (NOT severe) will remain focused over our east over the next several hours (through ~05z). Western convection will be isolated and generally weaker, but may impact some outdoor activities so stay weather-aware. Satellite imagery shows the next shortwave of interest over northern NV. After evening convection dissipates, late tonight and Sunday morning should be dry, then the next round of showers & storms begins...likely by midday or early afternoon as forcing from the aforementioned wave will be increasing by then. Tomorrow`s convection should offer an equal opportunity for our entire cwa, and will again potentially produce brief heavy rain and small hail. Wet bulb zero heights as low as 7000-8000 feet will keep any hail quite small, and the high terrain of the Beartooth-Absaroka and Crazy Mtns above 8000 feet should pick up a little snow accumulation (something like 1-3", which is near the NBM mean). High temps tomorrow should reach the 60s across the area...warmest in the east. One final thing to watch: precip in our east followed by at least partial clearing overnight, and persistent light/easterly surface winds, will yield a risk of fog across the east half of our forecast area. Last several HRRR runs are highly suggestive of this, and have added patchy fog east of Billings from 09-15z early Sunday. JKL Monday night through Friday... The latter part of the week continues to the focus of the long term forecast as a low moves through the Rockies and into the Central Plains. The models have continued shift the track of the low around, with varying impacts on the placement of precipitation. Given this uncertainty, have maintained a more broadbrush approach to precip and precip chances. However, it should be noted that the NBM probability for at least 1 inch of rain over 72 hours through Friday night has increased across much of southern Montana. Guidance 24 hours ago was generally in the 40 to 50 percent range, but that has increased to 60 to 80 percent. Much of the increase has been as members of both the GFS and ECMWF systems have taken a much more favorable more northerly and westerly track. This places the best chance for precip from South Central Montana down along the Bighorn Mountains. Continue to monitor the forecast for the latest as the models start to converge towards a more certain solution. Otherwise, still expecting relatively seasonal temperatures through the extended. There will continue to be periods of showers and embedded thunderstorms ahead of the low pressure system, as energy moves out of the Great Basin and up into the Northern Rockies. Reimer && .AVIATION... Isolated to scattered showers & t-storms will impact the region late this afternoon/evening. Greatest coverage will be along and east of a line from KSHR-KMLS...and this is where pockets of MVFR- IFR are most likely in any heavier showers. Convection will be isolated to the west. Storms could produce erratic outflow gusts to 35 knots. VFR will prevail, but mountains will be occasionally obscured. Expect VFR and little to no shower activity late tonight and Sunday morning...but by midday tomorrow the next round of scattered showers & t-storms begins. Local MVFR-IFR in brief heavy rain and small hail are possible w/ Sunday`s storms, which may impact all TAF sites. Mountains will be frequently obscured in rain/snow showers tomorrow. JKL && .PRELIMINARY POINT TEMP/POPS... Sun Mon Tue Wed Thu Fri Sat ----------------------------------------------------------- BIL 043/065 044/067 043/071 047/068 051/063 051/064 049/070 26/T 53/W 13/W 37/T 88/W 66/W 44/W LVM 037/061 036/063 038/065 039/063 044/061 044/065 044/070 36/T 33/W 23/W 27/T 77/W 55/W 33/W HDN 040/066 041/067 040/072 045/071 050/063 049/064 048/069 26/T 54/W 13/W 37/T 88/W 77/W 45/W MLS 044/066 044/062 043/072 050/072 053/065 051/064 051/068 25/T 66/T 12/W 36/T 88/T 76/W 44/W 4BQ 040/067 042/064 040/072 049/071 052/064 050/064 049/065 36/T 65/T 12/W 36/T 88/T 77/T 54/W BHK 042/065 040/062 038/070 047/070 049/067 048/066 046/067 34/T 56/T 12/W 46/T 88/T 77/W 54/W SHR 036/063 036/063 039/069 041/065 045/059 044/059 044/063 16/T 54/T 12/T 37/T 89/T 77/W 55/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Columbia SC
800 PM EDT Sat May 6 2023 .SYNOPSIS... Dry air in place over the region tonight. Atlantic high pressure builds into the region during the early to middle part of next week, with temperatures expected to be well above normal and a chance of daily afternoon and evening showers and thunderstorms. Cooler and drier conditions expected by Thursday following the passage of a cold front. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... With a lack of upper level support and loss of daytime heating, measurable rainfall is not expected tonight. Mid level dry air will also hinder deep convection, so if anything we would only see an isolated sprinkle. Low level moisture will be relatively high tonight, so we`ll see some strato-cu clouds at times. Lows will mainly be in the mid 50s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/... Sunday and Sunday night...Upper ridge appears a little more flat. Surface ridge off the coast with southwest flow in the low levels. This will result in an increase in moisture with precipitable water increase to around 1.30 inches across the region. Warm advection noted so temps a few degrees warmer...Highs in the low to mid 80s. Instability expected to be limited through the day...maybe increase a bit late in the Piedmont and north Midlands. A weak short wave trough may come over the ridge late in the afternoon although think main upper level dynamics will stay to the north. To complicate things a bit more, a mesoscale convective system may develop upstream in the Ohio Valley then move east- southeast. The convection is more likely to move across North Carolina by late in the day or main short wave trough passes by to the north. But some of the CAMS, especially the HRRR suggest this convection may slide into at least the northern Midlands by evening, so included a pop there and also focused mainly in Piedmont. The models also suggest convection may slide south west of the area. Confidence is quite low on development of convection late in the /evening, but with limited instability, will continue low pops north and west as the convection is more likely to decay near the area. Warmer overnight with clouds and increased moisture...lows in the low to mid 60s. Monday...A more robust short wave trough may ride over the flat ridge in the afternoon or evening. Moisture increases again with precipitable water to perhaps 1.75 inches. Instability appears stronger...with SB CAPE near 1000 J/kg near the NC/SC border along with some low level convergence. Low to mid level lapse rates appear steep with strong diabatic heating expected and warm advection...highs in the mid to upper 80s. So went with scattered mainly afternoon convection with slightly higher pops in the north Midlands. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Ridging builds over the eastern two thirds of the Lower 48 for much of the week ahead. South Carolina is forecast to generally be on the leading edge of this ridge, which will help to bring unseasonably warm temperatures to the region through midweek. Several fast moving shortwaves are expected to pass over the forecast area this week, bringing daily chances for afternoon showers or storms. A weak cold front is anticipated to move through midweek, allowing temperatures to cool off slightly for the end of the work week. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... Some drier mid level air will move over the region tonight allowing clouds to dissipate, although some low level moisture remains in place and there could be some areas of stratocumulus clouds. Low probability of some fog development but for now will limit to favored AGS. Winds will be light and variable to calm then pick up from the south by 15z Sunday. Clouds should become broken VFR by late morning with low level moisture in place and surface heating. EXTENDED AVIATION OUTLOOK...Mainly VFR Sunday, with a slight chance of showers or an isolated thunderstorms late Sunday/Sunday evening. Scattered showers and thunderstorms Monday/Tuesday. Some uncertainty with the timing of a cold front Wed, passage by Thursday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service Des Moines IA
646 PM CDT Sat May 6 2023 ...Updated for the 00z Aviation Discussion... .DISCUSSION.../Tonight through Saturday/ Issued at 222 PM CDT Sat May 6 2023 Key Messages: - Conditional chance for storms, possibly severe far south this evening. - Dense fog could develop overnight. - Another chance for strong to severe storms Sunday afternoon and night. - Mainly quiet and mild next week. An active weather pattern will continue through Sunday night across the area. Surface low pressure is located over northeast Kansas this afternoon with a warm front extending east towards the Kansas City and St. Louis metros. This boundary will lift some into this evening as the upper level flow becomes a bit more southwesterly as a short wave passes through the region. The warm front will likely stall near to just south of Iowa before retreating back south as the current surface low washes out and new cyclogenesis takes over in western Kansas. For Iowa, an elevated mixed layer (EML) has been expanding into central Iowa and model solutions continue to be different in the evolution of the EML with the HRRR continuing to be the most robust developing convection along the warm front in northern Missouri with some expansion into south central Iowa this evening. ACARS soundings a various points across the region continue to show an increasingly stout EML capping the region. Cloud cover is mixed across that area of interest and actually have backed high temperatures off a few degrees north of the warm front. Should convection not develop with diurnal heating and forcing, the low level jet is not overly impressive and with the primary kinematic energy with the passing short wave well north of the warm front, confidence in storms let along areal coverage is not high. In a worst case scenario should the capping break, conditions are favorable for a few supercells capable of large hail and possibly tornadoes in vicinity of the warm front with increasing curvature in the low level hydrographs and potential for streamwise vorticity ingestion. Otherwise regarding storms, the overnight should be generally quiet outside what is mentioned above. The other weather concern overnight is the increasing potential for fog and potentially dense fog. The greatest chances should be along and north of Interstate 80 and possibly southward into the Nishnabotna Valley. The fog may take some time to dissipate into Sunday. On Sunday, the warm front will advance back north. For EML will either still be in place or become re-established and keep any surface based activity to a minimum though there is some potential of convective elements to overtop the EML with elevated thunderstorms possible as the day goes on. Eventually, stronger forcing and eroding capping may lead to thunderstorms to develop later Sunday afternoon with additional activity overnight. Again, supercells would be possible near the warm front which could include all phases of severe weather potential though development still is conditional on the EML eroding. Storms overnight could become linear as they move out of Nebraska and would bring an attendant damaging wind threat though the 0-3 km theta-e differences of less than 20C are not overly favorable for established cold pools. Mild and spring like conditions will continue for much of next week. After Sunday night, a transition to more westerly/zonal upper level flow early in the week to ridging by mid-week. No single focused period for precipitation during this period though residual chances are still in the forecast at times. An upper level low will lift into the western High Plains towards the end of the week which often would lead to storms in Iowa but this system eventually drifts north and shears out into next weekend so it may not have much impact on the state. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 638 PM CDT Sat May 6 2023 An area of stratus and fog in northern IA are creating MVFR and IFR conditions, with occasional drops into LIFR. This stratus and associated fog is currently eroding from the west, but will expand south and west again when temperatures cool this evening. This will result in worsening conditions statewide, with widespread IFR ceilings and low visibility likely at all sites at some point through the night. In addition to stratus, showers and thunderstorms are expected to develop south over the next few hours, potentially impacting KDSM and KOTM. Confidence is low in the exact location and time storms will initiate, with higher confidence for storms at KOTM and less at KDSM. Therefore, will watch radar trends closely this evening and update TAFs accordingly. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Donavon AVIATION...Dodson
Area Forecast Discussion
National Weather Service Quad Cities IA IL
620 PM CDT Sat May 6 2023 ...AVIATION UPDATE... .SYNOPSIS... Issued at 250 PM CDT Sat May 6 2023 Warm front was located in northern KS to northern MO into middle TN with temps well into the 80s to lower 90s to the south, while dewpoints were well into the 60s to lower 70s. In the dvn cwa temps were in the mid 60s to mid 70s, with dewpoints in the upper 50s to lower 60s. && .SHORT TERM...(This evening through Sunday) Issued at 250 PM CDT Sat May 6 2023 Key messages: 1) SLGT risk (level 2 of 5) for all of the cwa this evening/tonight. 2) Main threats damaging winds, large hail and possible tornadoes. Details: Late afternoon and tonight: Capping inversion seen on 12z/06 DVN sounding suppressing convection this afternoon. Then CAM`s (esp HRRR) consistent in showing a weakening cap and thunderstorms developing later this evening and into tonight as a 40 LLJ kicks in increasing the lift/shear. The main threats will be large hail where elevated storms north of the warm front fire up. If storms can become surface based then tornadoes and damaging winds will also be a threat. A mild night expected with lows well in the mid 50s to mid 60s. Sunday: During the day the capping inversion looks to suppress convection once again. Very warm and humid conditions expected ahead of a digging trough in the Rockies and low pressure in ND. Record or near record highs expected at some locations and as of now Burlington and Moline have the best opportunity (see climate section below). Highs will be in the 80s to near 90. .LONG TERM...(Sunday night through Saturday) Issued at 250 PM CDT Sat May 6 2023 Key messages: 1) Enhanced risk (level 3 of 5) for severe storms Sunday evening and Sunday night. Main risk damaging winds. 2) Marginal risk (level 1 of 5) for Monday in our far south. 3) Warm week ahead with thunderstorm chances returning again late in the week. Sunday evening and Sunday night: Models show a disturbance in the flow arriving with an increase in mid level winds. This will increase the damaging wind risk with the potential for 75+ mph winds, when you add the SBCAPE of 4000-5000 J/kg into the mix. HRRR consistent in showing an intense severe squall line rapidly moving eastward into the dvn cwa late in the evening into the overnight hours. Scattered severe storms are also likely in the evening before the line arrives. Besides the damaging wind threat the risks also include tornadoes and large hail. Monday: A cold front arrives pushing the thunderstorm threat southward and there is still a severe threat (marginal risk) in our far southern counties. It will be cooler with highs in the upper 60s north to upper 70s south. Tuesday through Saturday: Persistent deep trough in the Rockies with a zonal to southwest flow aloft will keep our area in a warm regime with daily highs in the 70s to lower 80s. Thunderstorm chances return late in the week into next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 616 PM CDT Sat May 6 2023 A warm, moist air mass is over the region tonight and Sunday, with thunderstorms possible tonight, and again towards Sunday evening. The exact timing of storms and coverage is very challenging, with tonight`s storms uncertain on how widespread they will be on the latest trends. Even if storms are more isolated, the MVFR clouds should once again spread over the area, possibly with some IFR/MVFR visibility as well in the late night and morning hours Sunday. By mid to late morning Sunday, a VFR period may arrive as we heat up and develop a south wind again. A line of severe storms may move into eastern Iowa during the late afternoon and evening Sunday. ERVIN && .CLIMATE... Issued at 250 PM CDT Sat May 6 2023 Record High Temperatures for Sunday May 7, 2023 Burlington 88 1934 Cedar Rapids 98 1896 Dubuque 91 1896+ Moline 88 1965+ && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...Haase SHORT TERM...Haase LONG TERM...Haase AVIATION...Ervin CLIMATE...Haase
National Weather Service Kansas City/Pleasant Hill MO
635 PM CDT Sat May 6 2023 .Discussion... Issued at 400 PM CDT SAT MAY 6 2023 Key Messages: - Warm Temperatures Continue - Showers and Thunderstorms Next Few Days - Large Amounts of Timing and Storm Mode Uncertainty Discussion: Mid to upper-level ridge axis is starting to move into the Great Lakes Region this afternoon. The trough over the western CONUS that has been parked there for quite some time remains in place and continues to blast short-waves across the region. The southwesterly H5 flow around 70 kts has promoted stronger CVA across most of the Plains to Upper Mississippi River Valley. This has phased well with WAA across the Plains and has allowed a surface cyclone to deepen. Throughout this afternoon, the warm front with this system has made it up to about the Hwy. 36 corridor. The early convection in northeast Missouri helped to stall this boundary somewhat, but is once again on the move. Main question will be how far north does it travel. The H5 trough over the western CONUS is not making a whole lot of progress, thus at some point overnight the warm front likely stalls out. As the low-level WAA has continued this afternoon, it looks like we have had an area of weak subsidence emanate from the mid-levels that have cleared up skies, as well a drier air around the 700mb moving in. As a result, insolation has increased boundary destabilization this afternoon, and satellite imagery continues to show some developing cumulus fields. The EML just above 700mb though appears to be capping the cumulus field at the moment. Visible imagery is showing wave like structure this afternoon, indicating vertical motion is hitting a cap but wind shear remains moderately strong. With the warm front near by as well as pressure falls associated with the surface low, there is a decent amount of forcing around that could favor precipitation later this evening and perhaps into the overnight hours. The CAMs continue to remain all over the place with respect to solutions this evening (and this propagates into the Sunday and Monday forecast as well). The main issue this evening and into the overnight hours will be how robust the boundary layer mixing is. Dewpoint depressions are around 15F along the warm front at the moment, and may continue to increase over the next couple of hours. With drier air coming in at 700mb, this may hinder the moisture supply that is available. Since The 14z-19z cycles of the HRRR have been developing a discrete supercell after 00z this evening across northern Missouri, tied closely to the warm front. Other than that though, the HRRR is rather dry. Meanwhile, the 12z NSSL-WRF has scattered activity north of Hwy. 36 between 00-06z this evening, and the 4km NAM-NEST lights up a line across Central Missouri. This kind of spread in the solutions is the cause behind tonight`s large amount of uncertainty, and thus a POP forecast that bounces around quite a bit trying to reflect what the atmosphere could be capable of. The following details are conditional on the forcing being able to overcome the drier CBL and the capping in place. Most of this will pertain to northern Missouri this evening. Mid-level lapse rates will be around 8.0 C/km in the vicinity of the warm front and remnant outflow boundary, which will support stronger updrafts with parcels that are mechanically lifted to their LFC. There is plenty of deep layer shear available to support an initial supercell storm mode for stronger updrafts, and enough cyclonic shear in the first 0-3km to support stronger mesocyclone development. There is also a fair amount of cyclonic shear in the lowest 0-1km and even 0-500m layer featuring around 150 m^2/s^2 of SRH in these layers, a decent streamwise component. Therefore, if a supercell develops, such as what the HRRR has been suggesting since 14z this afternoon, could be capable of producing a tornado. So far the LCLs in northern Missouri have been around 800-900m. However, watching the airmass come in from Central Kansas and continued mixing for the next few hours, we may see those LCLs jump to over 1000m, which will start to get in a territory that often hinders tornado development. In addition, the stronger shear may also support larger hail in conjunction with the steep mid-level lapse rates. If a supercell develops and the storm-relative inflow is just right, there may be enough dry air to allow for a deeper hail embryo growth zone that could result in larger hail. And finally, a supercell could produce a stronger cold pools resulting in damaging winds. If we continue to see surface dewpoints decrease and LCLs increase, would expect mainly a hail and wind threat. As the LLJ ramps up this evening, if we see a more a multi-cell initiation, the storms would congeal and develop a stronger cold pool, resulting mainly in wind threat. The NAM-NEST seems to want to favor this solution, though will mention that the NAM-NEST likely maintains it for too long. Multi cells may have the thermodynamics to briefly produce hail as well with these lapse rates. Depending on how quickly the shear is realized will depend on how long multi cells would last and remain discrete. Overall, a robust storm can`t be ruled out this evening, but confidence in these severe details is very low given how conditional initiation is to begin to with. Sunday, the surface cyclone continues northward but another vorticity maximum ejects off the main trough and PV anomaly over the west coast. This will result in another area of surface cyclogenesis across the Plains and continue an afternoon of pressure fall trends. Low-level flow will maintain a meridional component to it which should maintain stronger theta-e advection and an unstable airmass. The main question with instability though will be Saturday Night`s convection activity (or perhaps lack there of) and how well the boundary layer will be able to recover. There could also be the question of remnant outflow boundaries, or if the current warm front stalls somewhere over the area. Mid-level lapse rates should remain healthy (at least 7.5 C/km or greater) ahead of the developing cyclone. There has been a decent trend within the CAMs to develop a complex of thunderstorms over southeast Nebraska late tomorrow in the afternoon, and eventually form a line across the IA-MO border. However, if the boundary remains in place and there is enough boundary layer recovery, a few discrete storms could be possible as well. The stronger H5 flow remains in place maintaining the deep layer shear and ability for convection to organize. Given that tomorrow`s setup will largely depend on tonight`s outcome, will not dive too deep into the mesoscale details. The shear and instability tomorrow though if fully realized can present all hazard types with supercells, and another wind threat if a bowing segment line were to develop. Stay tuned for mesoscale analysis updates tomorrow when the forecast can be refined. Most of the severe weather threat would be north of Hwy. 36. However, thunderstorms are possible across most of the forecast area on Sunday, and may have potential for produce severe wind gusts and larger hail. Monday, another short-wave ejects from the main trough over the west and we continue to see stronger theta-e advection into the area. Basic thunderstorm ingredients come together once again, and with deep layer shear still in place potential for organized activity. This is highlighted by the Day 3 Slight Risk along Interstate 70 for Missouri into extreme eastern Kansas. Like with the Sunday event depending on Saturday Night activity, Monday activity may depend on Sunday activity with respect to thermodynamic recovery. At this point, it is hard to try to discuss more mesoscale details for this threat. For the rest of the week, temperatures will remain well above normal. Eventually the trough over the western CONUS will start to propagate toward central CONUS. This will bring additional rain shower and thunderstorm potential later this week. && .Aviation...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 635 PM CDT SAT MAY 6 2023 VFR conditions are expected through the forecast. Storms this evening will stay north of a boundary that`s noted from north of St. Joe to CDJ and then arching to the southeast and then south. Drier air south of this boundary will inhibit convection further south, but keep conditions VFR. Winds should switch to the north overnight as the surface low moves northeast of the area. But winds will increase from the south to southwest again later tomorrow morning. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...Krull Aviation...CDB
For this long-term forecast discussion, the main focus will be on very
unsettled weather pattern that is anticipated to take shape during the
middle of next week. This pattern looks to bring us our first potential larger severe weather event of the season, and there is the possibility that this turns into a larger, multi-day event. More details on this below. Beginning with Tuesday, the general favorable weather pattern for active weather will begin to take shape. However, I do think the active weather may hold off another day before becoming a problem for the High Plains. An upper level ridge will form over the Great Plains, and an upper level trough will be digging into the western United States. This will set the stage for return flow across the High Plains, bringing warmer temperatures but more importantly, a return of moisture from the Gulf of Mexico. A lead disturbance should eject across the High Plains during the afternoon hours, which will cause some showers and storms to fire. Some of these storms could certainly be severe with SBCape of 1000-2500 j/kg, lapse rates of 7-8.5 C/km, and 0-6 km bulk shear of 35- 50 kts present during the afternoon hours. There are some concerns about where the surface features will take shape as it does appear that a warm front will be present over parts of western Kansas, but that front may remain to our south, reducing our risk. Other members of forecast guidance suggest this warm front will be draped across our forecast area, which would increase our severe weather chances. Upper level support/lift is also not terribly supportive of widespread severe weather, so while I do think there could be some strong/severe storms on Tuesday, I wouldn`t plan on it being an outbreak type day. For Wednesday, a much more substantial severe weather threat may take shape across the High Plains. In the upper levels, the trough digging into the western United States will begin to cut off and take on a negative tilt, a favorable upper level pattern for severe weather across the Great Plains. At the surface, a low pressure will form in eastern Colorado in lee of the Rockies. In addition, there may be at least a couple surface boundaries to work with...a dryline which is held west across eastern Colorado, and then a lingering warm front draped through western Kansas and southwest Nebraska. Further, with storms forecast on Tuesday, there may also be remnant convective outflow boundaries. Winds at low levels will be from the southeast, continuing to pump moisture into the Tri-State Region. Aloft, winds will be from the southwest and increasing in strength. This combination of warmth, moisture flow, and turning and strengthening of the winds as you go up in the atmosphere spells a favorable severe weather threat. Severe weather parameters definitely show that with widespread SBCape of 1500-2000 j/kg, lapse rates of 7.5-8 C/km, 0-6 km bulk shear of 40- 50 kts, sizable 500 mb height falls, LCLs less than 1500m, and PWATs of 1.0 inches or so, or in the 90th percentile. What these parameters mean, along with the orientation of the anticipated surface fronts compared to the upper level forcing/shortwave, is that an outbreak of severe storms/supercells is certainly possible. These storms would be capable of all modes for severe weather and, depending on storm movement and where previous storms produced rainfall, the possibility of a flash flooding report or two. Won`t get too excited about the flash flooding threat though with widespread extreme to exceptional drought conditions continuing across western Kansas and into southwestern Nebraska. Wednesday definitely is a day that bears watching for most of us, especially if that dryline starts the event in eastern Colorado, allowing storms to move across the entire area rather than just part of it. On Thursday, a similar environmental setup is anticipated although the surface and upper level features will be slightly different with their locations. At the surface, the dryline will have moved into the Tri- State Region, setting up somewhere in southwestern Nebraska and northwestern Kansas. On average, currently the guidance suggest this dryline would be around Highway 25, setting up locations east of there for another potential volatile day of storms. Aloft, the upper level low should be slightly further northeast...moving into eastern Wyoming and western Nebraska. This upper level low positioning is usually not terribly favorable for severe weather across our forecast area, but the surface features, instability, and wind/wind shear parameters would suggest that severe weather should be anticipated once again. In fact, wind shear parameters are even stronger on Thursday with 0-6 km bulk shear possibly reaching around 70 kts, quite a substantial projection. Therefore, once again given all the data, another day of supercells is possible for Thursday, but this time only half the area or so would be impacted. With the dryline solidly into the forecast area, will need to also be aware of the potential for fire weather conditions to develop behind the dryline, generally west of Highway 25. On Friday and into the weekend, the upper level low will begin to weaken and shift northeast. This should reduce our threat for severe weather, though it may lead to a continuation of precipitation chances depending on the surface features and upper level disturbances that move across the area. In the end, the main message is to pay close attention to the forecasts for Tuesday, Wednesday, and Thursday, but in particular Wednesday and Thursday as these days could come with a significant severe weather threat, the first bigger threat of the year. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 915 PM MDT Sat May 6 2023 VFR conditions prevail at both terminals. The surface low becomes positioned over our area overnight, with winds becoming light and variable. Potential MCK could see some slight reductions to visibility in patchy fog Sunday morning, generally between 11Z and 15Z. Shortly after sunrise, around 15Z, winds favor having a more northerly component around 5-10 knots sustained. Isolated severe thunderstorms capable of producing large hail and damaging winds cannot be ruled out at either terminal late in the TAF period (22Z Sun - 02Z Mon). Low confidence w/regard to whether or not storms would impact GLD and/or MCK - will update with future TAF issuance as needed. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...Trigg LONG TERM...RRH AVIATION...CC/Vincent
Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
1153 PM EDT Sat May 6 2023 .Mesoscale Update... Issued at 1153 PM EDT Sat May 6 2023 A quasi-elevated supercell over Fountain County is exhibiting a persistent high reflectivity core aloft and three-body scatter spike. High confidence in large hail with this storm currently. RAP proximity sounding shows 45 knots of effective shear and sufficiently steep lapse rates to contribute to a decent amount of instability. Additional convective cells have increased over the last hour in a north-northwest to south-southeast band at the leading edge of strengthening low-level jet and associated moisture/theta-e advection. Convective and associated hail threat is likely to persist and expand eastward into the night as low-level jet/moisture advection expands eastward. Meanwhile, convection over western Illinois may continue to organize reaching western Indiana around or just before 4:00am. The downstream environment is favorable for it to maintain and potentially grow. More on this potential in subsequent updates as we continue to watch trends in observational data. && .Forecast Update... Issued at 1005 PM EDT Sat May 6 2023 Main updates of concern will be on the warm air advection precip/iso- convection that is slowly sliding east/northeast across Central Indiana this evening. Flow is uniform from the southeast in the low-levels, with a strengthening meridional flow assisting to transport additional moisture through the column. This is presently being observed with rising dewpoints across Central/Southern Indiana. Coupled with this has been gusty winds between 18-24kts, and is expected to persist through the overnight hours. Aloft there is presently enough ascent to parcels that they continue to moisten and encounter some elevated instability that is allowing stronger vertical ascent. Fortunately the potential for upscale growth along this leading nose does not appear to be favorable; however, there is strong enough lift to allow some lightning to develop. Expect the nose of the precip/iso- convection to continue to slide east/northeast with minimal coverage through early morning hours Sun. The next focus will be on the developing complex well upstream in Iowa/Missouri that is progged by several guidance members to slide east overnight. The expectation is that the upstream convection will continue to observe some upscale growth as it slides east into extreme Western Illinois, and will be in some decaying state as it arrives in West Central Indiana around 9-11Z. So for the overnight forecast, have held onto the original forecast as there isn`t much indication that we need to deviate at this time. && .Short Term...(This evening through Sunday) Issued at 216 PM EDT Sat May 6 2023 Tonight. A conditional severe weather risk is in place for tonight with the potential for a decaying complex of storms to impact the area late into the overnight hours. As of early afternoon, a lone storm had moved into western Illinois and defied the CAMs to maintain longer than expected, but details of this storm and any impacts to Indiana are covered in the mesoscale discussion above. By later this evening convective initiation is expected across northern Missouri into Iowa with upscale growth into a line by the time it reaches northwestern Illinois. It will then move into a gradually more stable environment. Model soundings show that any convection that arrives to the northwestern counties would be elevated in nature with MUCAPE values in excess of 1000 J/kg but a stout cap at 3kft. Current thoughts are that there may be some elevated showers and storms that initiate ahead of the line in the area of stronger WAA but that the most potent portion of the storms would arrive towards daybreak with a messy nature and severe weather being unlikely. If the storms build a stronger cold pool earlier in the night, they will likely arrive earlier than daybreak and have a higher chance of severe weather as it shifts southward to feed on the residual instability. Large hail looks to be the primary threat, but even with the cap, an isolated wind gust is possible as well. Sunday. Showers and storms may then continue into the morning hours from any overnight convection, but expect that much of the day will be dry with gradually clearing skies as the convective debris dissipates. A residual outflow boundary will settle somewhere across the southern counties and perhaps as far south as the Ohio River which would be the focus point for the next round of convective initiation. Current thoughts are that the southwestern counties have a small threat for storms with better chances further southwest. Additional storms are possible into the overnight hours but will be covered in the long term section below. && .Long Term...(Sunday night through Saturday) Issued at 216 PM EDT Sat May 6 2023 Sunday Night Through Tuesday. The messy pattern continues into the long term period as better chances for storms arrive to central Indiana Sunday night into Monday. There remains a lot of uncertainty as to how the storms tonight may settle any outflow boundaries, which would then be areas of focus for additional development. Running off the expected scenario where convection moves in late tonight and early tomorrow, the threat looks conditional to unlikely for Sunday night with the outflow boundary south of Indiana and any convection being a decaying complex that moves into the northwestern counties during the overnight hours. Better chances for severe storms from this system would be earlier in the day and across Iowa and northern Illinois. Weak northwesterly flow will continue to develop into the work week with additional low confidence potentials for storm complexes Monday and Monday night. The cap looks weaker Monday which may interact with the Sunday night outflow boundary to allow for storms during the daytime hours Monday and possibly again during the overnight hours. Current thoughts on the Monday storms would be that the best chance for severe would be if storms fire during the afternoon with the southeastern counties looking to be where the best chance for surface convergence associated with the remnant boundary will be in place. Lesser chances for storms are expected for Tuesday as conditions begin to flip, but there remains a lot of uncertainty as to how things Monday would impact weather for Tuesday. Above normal temperatures are expected through the period, but clouds may end up keeping conditions closer to normal at times. Wednesday Through Saturday. Forecast confidence Wednesday into the weekend begins to increase as the weather pattern becomes more synoptically driven. Weak high pressure will be in place on Wednesday with drying aloft allowing for the skies to clear from the last few days of occasional storms. By Thursday a closed low will eject from eastern Colorado and begin to track to the northeast with modest Gulf flow into the lower Ohio Valley. It`s possible a weak storm complex could form Thursday night, but think the better chances for any impact from that will be further south. By Saturday a cold front associated with the aforementioned low pressure system will approach the area with increasing chances for precipitation. && .Aviation...(00Z TAF Issuance) Issued at 755 PM EDT Sat May 6 2023 Impacts: -Occasional wind gusts to 20kts thru eve, shift to SW after 12Z. -Conditional TSRA threat late tonight/early tomorrow -MVFR to briefly IFR cigs after 07Z through 15Z. Discussion: Minimal changes to prior aviation forecast. Increased cloud cover continues to be floating overhead with some spotty lower CIGs already arriving. To the west along a warm frontal boundary, a few showers have already developed and are lifting north/northeast. Current timing would indicate the widely scattered coverage to arrive over Central Indiana roughly around 6Z; however, the expected increase in coverage and intensity remains minimal. Expect this precip to continue to be very minimal in coverage. A conditional threat for storms is in place for tonight, but confidence in potential and timing of storms is low. Put in a Prob30 group during the expected best chance for storms but they could arrive early. Any vsby restrictions would be during that period of storms. Winds will become southwesterly after daybreak with improving cigs into the morning hours. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale...BRB Update...Beach Short Term...White Long Term...White Aviation...Beach
National Weather Service Jackson KY
1137 PM EDT Sat May 6 2023 .UPDATE... Issued at 1137 PM EDT SAT MAY 6 2023 Convection that moved into the southwest portion of the CWA has weakened although there are upstream showers in portions of central KY. Thunderstorms are upstream over portions of the IN and the midwest. At least some showers or sprinkles may affect portions of the south or southwest over the next couple hours, but the attention continues to turn toward the potential for upstream convection to grow upscale overnight and approach eastern KY near or a couple of hours after dawn on Sunday and then move south and southeast into the are around an upper level ridge. Some of the convective allowing model runs have this scenario to a degree with some weakening the convection more than others. There is the potential for a gusty line or line segments of convection near the leading edge during the morning into the afternoon. The degree of cloud cover and possible morning timing of arrival lead to low confidence in the degree of instability and overall for this scenario, but at this point it appears that strong to damaging wind gusts would be the primary threat from any stronger thunderstorms on Sunday along with brief heavy downpours. At this point, we have opted to add a gusty winds attribute to thunderstorms in the weather grids on Sunday. Later shifts will continue to monitor this potential. UPDATE Issued at 850 PM EDT SAT MAY 6 2023 An area of showers and some embedded thunder has moved across the OH River from Indiana and into the Louisville Metro area southwest to the Hardinsburg area. Much of the convective allowing model guidance and guidance in general over the past few hours has not handled the timing of this activity well. The 23Z HRRR take the activity into the southwest portion of the area and it diminishes. Mesoanalysis has mid level lapse rates around 7C/km across western portions of the CWA over the next few hours. Meanwhile a moisture gradient and instability gradient generally lies from near the SDF Metro area toward the Cumberland Plateau of TN, with higher PW and ThetaE generally west and southwest of the CWA. There is uncertainty as to how far this activity might hold together, but assuming that it lingers after sunset and holds together at least to an extent, it may approach Pulaski County around 2Z and then work across the southwest portion of the area through around 6Z. Pops over the next 6 hours or so were adjusted to account for this with slight chance used due to uncertainty as to how far the activity holds together with pops then blended toward previous pops for late tonight when additional and more than likely more widespread activity should approach from the northwest. Other generally minor adjustments to grids have been made based on satellite and observation trends. && .SHORT TERM...(This evening through Sunday night) Issued at 359 PM EDT SAT MAY 6 2023 Key Messages: 1. After dry weather this evening and most of tonight, a mesoscale convective system (MCS) is expected to drop across eastern Kentucky on Sunday with widespread showers and thunderstorms. 2. Rainfall may be locally heavy Sunday and isolated high water issues cannot be ruled out under the most persistent activity. 3. Another MCS may impact eastern Kentucky Sunday night into Monday morning, but its track will likely depend, at least in part, upon the evolution of the prior MCS. Analysis: After one more mild and mostly sunny late spring day, a transition to unsettled weather is in store as we head deeper into the short-term forecast period. At 1955z, temperatures around the forecast area are mostly in the mid to upper 70s, though a few of the warmest valley locations have eclipsed the 80 degree mark, courtesy ample sunshine mixed with a few mid/high clouds and sparse fair weather cumulus. The latest analysis shows the surface high pressure responsible for our recent stretch of pleasant weather now departing off the Atlantic Seaboard ahead of a 500H ridge axis aligned from the Lower Mississippi Valley to Lower Great Lakes. The first of several upper level disturbances riding over the ridge is now situated near/over Illinois. At the surface, a sluggish warm front resides across the mid-Mississippi to mid-Tennessee valleys. This frontal zone will become the preferred corridor for multiple MCSs as boundary tries to lift northeastward from later tonight through the first portion of the long-term forecast period. Guidance, even the CAMS, continues to struggle with the evolution of the first MCS as it organizes well north of the Ohio River late tonight. Some guidance, including the 12z HRRR/ARW/NSSL, suggests a lead cluster of decaying convection riding southeast earlier in the night, potentially laying out a convective outflow boundary. Therefore, a low chance PoP is in the forecast tonight to cover this possibility before PoPs rise sharply from northwest to southeast on Sunday morning with the arrival of first MCS. Much of the hi-res guidance shows most of bowing portion of the MCS moving into West Virginia Sunday morning while eastern Kentucky lies on the upshear side of the MCS. If this occurs, our area would be favored for seeing convection line out ~ NW-SE while interacting with one or more convective outflows. The messy/semi- linear convective mode and expected poor alignment with the 0-3 km shear vector will diminish the threat for severe weather (though briefly strong winds or large hail cannot be ruled out with a stronger storm). Additionally, PWATs rising to around the 90th percentile relative to climatology along with robust moisture transport and tall, skinny CAPE profiles support the potential for locally heavy rainfall. Given dry antecedent conditions, low streamflows, and active vegetative growth, substantial rainfall amounts (FFG is generally 2 to 3.5 inches in a 3-hour period) will be needed before high water issues arise. Such amounts could theoretically be achieved in a few isolated spots (as per the 12z HREF 3-hr QPF ensemble max values), leading to localized high water concerns; but, for the vast majority, this will be a beneficial wetting rain. Another subtle disturbance further cuts into the 500H ridge Sunday evening and night, likely initiating another southeastward dropping MCS. The track of this second MCS will be highly dependent upon the placement of outflows from earlier convection. Additional MCSs are probable during the first part of the long- term as well. If these systems impact a particular location multiple times, high water issues will become more probable with time. Tonight`s temperatures will be milder than the previous night, ranging mainly in the 50s to around 60. Maximum temperatures on Sunday should be cooler than today, mainly mid 70s, courtesy abundant cloud cover and rainfall. Mild conditions will continue Sunday night with minimum temperatures in the lower 60s for most locations. .LONG TERM...(Monday through Saturday) Issued at 325 PM EDT SAT MAY 6 2023 Global model guidance and most CAMs indicate convection, possibly an MCS, ongoing across at least near or over parts of the area to start the extended period Monday morning, as a mid-level disturbance and southwesterly low- to mid-level flow pushes 60s dewpoints into the region, resulting in increased instability with CAPE values possibly as high as 1500 J/kg. Assuming models are handling the situation sufficiently, a brief period of partial clearing and more stable conditions for the early afternoon period in the immediate wake of this convection gives way to increasing strong warm advection and instability mid- to late afternoon and a return of shower and thunderstorm chances later Monday afternoon into Monday night and extending through much of Tuesday as a cold front approaches from the north. Models also indicate the low-level and mid-level flow becoming becoming largely unidirectional and west-northwesterly (more oriented perpendicular to terrain) while also increasing in strength Monday night into Tuesday, which is somewhat concerning for the potential for flooding concerns given precipitable water values approaching 1.25 to possibly as high as 1.5 inches during this time. WPC currently has a Marginal Risk for flash flooding for the CWA for Monday and Monday night, and would expect there is potential for this to be extended through Tuesday by tomorrow`s forecast issuance. An upgrade to a Slight Risk is possible particularly if previous round of convection occur across the region Sunday through the first half of Monday. Increasing shear values along with moderate instability Tuesday along and ahead of the passing cold front may also yield a risk for strong to severe storms Tuesday, with strong winds the primary threat. Though there are timing differences between global models, there is agreement in a more tranquil period of weather Wednesday with cold advection behind the cold front. This drier weather may extend through much of Thursday as well, but a low pressure system moving from the southern Rockies northeast to the Upper Mississippi River Valley will begin to result in increasing moisture and instability and returning chance PoPs Friday into next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 835 PM EDT SAT MAY 6 2023 VFR conditions are generally expected to prevail through at least 12Z and perhaps as late as 15Z, as high pressure departs and a warm front lifts into our region. A cluster of convection may impact southwestern portions of the forecast area during the first 6 hours of the period, but due to uncertainty as to how far southeast it will hold together, confidence remained only high enough to mention VCSH at KSME and KLOZ. However, a larger cluster of showers and storms, dropping from northwest to southeast along the front, appears likely to arrive toward 12Z and then move across the region for most of if not all of the remainder of the period. VCTS has been to the TAFs for several hours on Sunday, generally between about 11Z and 20Z for the anticipated activity. Besides the threat for lightning, this second area of convection on Sunday will likely bring at least brief periods of sub-VFR CIGs and or vis in the strongest activity and could be preceded and/or attended by strong and erratic wind gusts. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...GEERTSON LONG TERM...GEERTSON/CASSELL AVIATION...JP
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
737 PM CDT Sat May 6 2023 .MESOSCALE DISCUSSION... Issued at 737 PM CDT Sat May 6 2023 Regional satellite and radar imagery depicts a compact region of scattered elevated thunderstorms near Bloomington and Gibson City, which are gradually moving east-northeast at 35 mph. Recent RAP guidance suggests the thunderstorms are being maintained by low-level convergence at the nose of a 40-45kt 925-850mb low- level jet sampled nicely by the KILX VWP. After sunset, the low- level jet should intensify encouraging a gradual uptick in coverage of scattered thunderstorms into northeastern Illinois and northwestern Indiana (along and east of I-55). Steep mid-level lapse rates sampled near 8-8.5 K/km by the KILX RAOB will support occasional production of pea to penny size hail and lightning strikes as the thunderstorms continue east-northeastward. These thunderstorms are not the focus for the overnight period. Meanwhile, a cluster of supercells continues to move eastward just south of the Iowa/Missouri border near an effective warm front modified by a complex of storms that moved through central Illinois earlier today. With recent satellite imagery depicting increasing updraft vigor and width with each supercell, it seems plausible they will "grow upscale" into a compact complex over the next few hours and at least partially intercept the intensifying low-level jet as they move into central Illinois. In other words, additional thunderstorm development to the north and near the Quad Cities may be less organized and in lower coverage, leading to a lower coverage and/or intensity of storms in northern Illinois overnight. Even with a lower coverage and perhaps less organization to thunderstorms locally overnight, steep mid-level lapse rates will still support a damaging hail threat. The peak thunderstorm window remains roughly midnight to 5 am. Updated products will be sent soon. Borchardt && .SHORT TERM... Issued at 247 PM CDT Sat May 6 2023 Through Sunday night... Challenging forecast the next 36 hours as we get into somewhat of a "ring of fire"-esk pattern, more reminiscent of mid summer than early May. The result will be multiple chances of thunderstorms, some possibly severe, along with a threat of heavy rainfall. Unfortunately, timing and location of best precip and storm chances remains nebulous, tied to small, difficult to resolve waves and how they potentially get enhanced/altered by subsequent convection. This afternoon, a small convective complex continues to dive south across downstate IL, riding the instability gradient safely away from our area. To our northwest, water vapor imagery shows a pair of vort maxes approaching the crest of the ridge axis across the northern Plains and into the Upper Mississippi Valley. Weak surface low associated with the lead wave was located over NE KS early this afternoon. This low will track to near GRB by 12z Sunday. As it does so, it should drag a convectively enhanced baroclinic zone north as a warm front. The very warm, seasonably humid, and moderately to strongly unstable air mass across the eastern Plains will spread east and northeast across our CWA tonight into Sunday. A preponderance of the CAM guidance tonight suggests convection will affect our CWA. Details in how this convection develops and evolves is unclear, with a couple different plausible scenarios (or a combination of both) possible... 1) severe t-storms develop over IA late this afternoon and evening near northward advancing warm front, with these storms congealing into MCS and propagating into our CWA late this evening into the overnight hours with a continued potential for locally damaging winds and some instances of severe hail. 2) convection develops this evening over northern IL and/or southern WI as nocturnal low level jet develops and lifts parcels isentropically to their LFC where they can take advantage of the very steep lapses rates and moderately strong shear. In this scenario, the more intense storms would pose mainly a threat for hail with a much lower damaging wind threat. Strong, pronounced EML across the region is providing for steep lapse rates and enhancing instability, but also resulting in strong capping inversion for boundary layer parcels. Water vapor imagery early this afternoon shows a subtle shortwave moving across IA and MO now, likely aiding the down state MCS, but timing of this wave looks poor for CI along the warm front over IA later this afternoon and raises doubts about scenario one occurring. That same subtle wave looks to be over western IL by early-mid evening, which could lend some support to elevated storms forming this evening (a la scenario 2) over our particularly eastern portions of our CWA. Given the spread in guidance and strong EML, cannot completely discount the possibility of CI failing in IA later today and convection forming mainly east of our CWA this evening given the nose of the LLJ and max theta-e advection quickly shifts east of our CWA. For now, putting more stock in something like scenario 1 and 2 described above, but the potential failure mode has led me to keep pops no higher than likely tonight. Any convection over our CWA late tonight should quickly exit stage right by early Sunday morning as LLJ further veers and weakens. Any convective cold pool left behind is likely to mix out and allow for a warm and humid day Sunday across most of the CWA, with strong cap expected to keep precip chance quite low. Weak sfc low near GRB to start the day Sunday will track east across the lake into lower Michigan. The front associated with this low will begin to sag south during the day Sunday, however, the very cold (relative to air over land) marine layer should lake charge this cold front, allowing it to accelerate down the surge inland during the late afternoon. Temps right at the shore will drop into the 50s behind this "pneumonia front", with the temp fall more muted with inland extent. While confidence in the details is low, convectively undisturbed areas should see a large moderate to strongly unstable air mass develop upstream across the eastern Plains to the mid-Mississippi Valley Sunday. There is a pretty coherent signal in guidance that a shortwave trough will ripple east leading to intense convection developing over IA during the day Sunday. It seems likely that this convection will evolve into one or two MCSs that would then potentially track across or nearby our CWA Sunday night. This convection would pose a threat of both severe weather and heavy rainfall/flash flooding, but the details of where still it affects still need to be worked out. Certainly looks like the threat increases as you head west, but at this distance, the threat looks like it could extend east across our CWA. - Izzi && .LONG TERM... Issued at 300 PM CDT Sat May 6 2023 Monday through Saturday... Key Forecast Message: * Showers with a threat for additional thunderstorms on Monday, some of which may caused heavy downpours and localized flooding Much of how Monday plays out will hinge on the footprint of convection Sunday night into the early morning hours leading up to 12z Monday. The effects of prior and potential lingering convection on the rest of the day`s evolution are needless to say uncertain. With a signal that the overnight activity could linger into the morning, even if on a weakening trend, maintained the fairly high PoPs Monday morning. With confidence in thunderstorm coverage on the lower side, only have chance wording there. How much instability can rebuild Monday afternoon is also lower confidence, though the 12z model cycle generally points toward higher potential instability residing generally south of I-80. A plume of steep mid-level lapse rates will advect back in on Monday afternoon. This will certainly make the answer to the destabilization question an important one, as deep layer bulk shear is forecast to be supportive of storm organization. PWATs on the order of 150-180% of normal and deep layer steering flow parallel to the warm front expected to be draped across the area could yield some training potential if deep moist convection does occur. WPC`s updated day 3 level 1 (marginal) risk area for excessive rainfall is indicated in our south of I-80 locations in line with where the stronger instability may develop. We should be able to refine the currently broad-brushed likely PoPs and chance thunder Monday PM once Sunday night-Monday AM`s trends become more clear. Temperature wise on Monday, the marine influence appears likely to extend fairly far inland again near and north of the warm front, with upper 50s-mid 60s close to the shore and mid-upper 60s several miles inland. Well inland, forecast highs in the 70s appear reasonable, with thermal profiles supportive of 80+F south if there`s enough insolation. There is now good agreement in surface high pressure and drier easterly flow prevailing Tuesday through Thursday. Thus as things stand now, look for primarily rain-free conditions in that period. Temperatures will be pleasantly warm inland and notably cooler near the lake given persistent onshore flow. How long the dry high pressure influence holds on is uncertain, so some low PoPs come back into the picture by next Friday. Another fairly active stretch could take hold whether that starts Friday or Saturday. Castro && .AVIATION... For the 00Z TAFs... The primary aviation weather concerns through the 00Z TAF period are as follows: * The potential for a few thunderstorms late this evening and into the overnight with accompanying MVFR cigs * A lake breeze expected Sunday afternoon abruptly turning westerly winds northeasterly * The possibility of additional thunderstorms Sunday evening A system of showers and thunderstorms is expected to develop and move over the terminals late this evening into the overnight. Our best storm chances look to be between roughly 07-09Z over the Chicagoland terminals. During this time, it`s also not out of the question to see a stronger storm move through. However, there is still a good deal of uncertainty as to whether the bulk of the storms may decide to miss us to the south. Late this evening into the early overnight, some models want to throw up a couple of scattered showers and lighter storms ahead of the main swath of storms and drop them on the metro beginning as early as around 03Z. For now, we`re keeping a close eye on how the newly-developed storms out west evolve. As we do over the next several hours, confidence in how things will play out tonight will steadily build. MVFR cigs are also expected to move in late this evening and stick around through the night. We should be back to VFR by Sunday morning, possibly even several hours earlier than the 15Z timing that`s currently in the TAF. Meanwhile, gusty SSE winds will slowly subside over the next several hours dropping to closer to 10 kt by late this evening. A few near-20 kt gusts may continue to sneak in from time to time overnight. Direction will back to SW overnight tonight. Westerly winds near or under 10 kt will then take us through the first half of the day before a lake breeze is expected to move over in the mid-afternoon turning winds to northeasterly. Additionally, the last few hours of the TAF period include a potential for some scattered thunderstorms late Sunday evening. Doom && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
906 PM EDT Sat May 6 2023 ...New UPDATE... .UPDATE... Issued at 859 PM EDT Sat May 6 2023 An upper ridge of high pressure will remain across the Tennessee valley with a series of waves riding on top of this ridge producing areas of convection. First small area of showers and possibly a thunderstorm is currently located over northern KY. This area of storms continues to weaken with latest HRRR dissapating these showers before reaching east TN/southwest VA. Partly/mostly cloudy sky antipated overnight. Overall, current forecast looks good. For Sunday, another wave will approach the region with boundary layer southerly flow across the lower Ohio/Tennessee valley producing isentropic lift. Another area of showers and storms will likely be moving toward the region during the afternoon. Main concern with these storms will be strong and gusty winds. && .SHORT TERM... (This evening through Sunday) Issued at 315 PM EDT Sat May 6 2023 Key Messages: 1. Confidence is high that some MCS activity will affect the forecast area during the short term period. Also, confidence has increased that some damaging wind threat will accompany these storms. 2. However, confidence on timing and placement of any MCS that moves through is still fairly low. Discussion: Upper ridging will extend from the central Gulf coast up through the Ohio valley during the short term period. At the surface, high pressure will remain situated along the coast of the Carolinas, with a surface low over the northern plains and upper midwest. Warm and moist advection will continue across the forecast area as a result of broad southwesterly surface flow across the deep south in this surface pattern. Overall, this dirty ridge type pattern will almost certainly produce some MCS activity that will make its way southeast from Kentucky towards our forecast area. This is all well agreed upon in the short term. The uncertainty, of which there is a great deal, revolves around timing and location of rain chances due to the incoming MCS activity late tonight or Sunday. Currently there`s a cluster of thunderstorms to the northeast of St Louis, which various runs of CAM guidance has resolved and show diving southeast through southern Indiana later this evening and into Kentucky. There`s mixed reviews about whether this makes it into our area or not, but do have this reflected in PoP grids before daybreak tomorrow morning, aligning fairly well with the 12z HRRR and ARW guidance. Most all guidance develops another cluster of storms well to our northwest during the day tomorrow and brings that towards the forecast area towards the end of the short term period. Have modeled PoPs accordingly. With regards to severe weather chances, there`s uncertainty there too. Forecast soundings as well as SPC HREF guidance show respectable instability tomorrow, with MUCAPE values north of 1,000 to 1,500 J/kg and HREF probabilities of greater than or equal to 1,000 J/kg exceeding 70-80 percent during the day tomorrow. Any MCS moving in during the pre-dawn hours will likely be in a decaying state and not pose much of a damaging wind threat. But the same cannot be said for the remainder of the day given those forecast instability values. Damaging winds will be the primary threat from any MCS activity. SPC expanded the Day 2 marginal risk area to cover our entire CWA because of the forecast instability and also uncertainty in exactly where these will track. Most guidance indicates any MCS activity will enter generally somewhere near the confluence of the TN, KY, and VA borders, and have a SSE movement. && .LONG TERM... (Sunday night through next Saturday) Issued at 315 PM EDT Sat May 6 2023 Key Messages: 1. Unsettled pattern continues, with periods of showers/storms Sunday night through Tuesday. 2. Drier mid-week, with a return of PoPs late week into the weekend. 3. Above normal temperatures expected throughout the week. Discussion: Weak ridging will be of influence across the southeastern CONUS, with broad troughing digging into the northern corners Sunday night. Overall, this looks like a pattern in which ridge riding MCSs are favored. In fact, many of the short to mid-range models contain some variation of an MCS or two traversing across the region, however, uncertainty increases when trying to pick apart the finer details such as timing and spatial coverage. The 12Z HRRR suggest storms will move through during the overnight hours. With weak synoptic forcing(i.e no significant jet streaks or divergence aloft) this does not look to be a scenario supportive of widespread nocturnal severe weather but some isolated strong to damaging wind gusts cannot be ruled out if a trend as such pans out. Other HREF members struggle to hold activity together as well as the HRRR into the overnight. Model derived soundings paint MLCAPEs generally around the 700- 1000J/kg range Monday. Given the presence of some mid/low level dry air, DCAPEs are forecast to be around ~500-700J/kg. Shortwave impulses cresting the ridge and the perhaps any lingering outflow boundaries keep the potential for storms continuing into the work week. There still remains uncertainty with timing given the more coarse resolution models and their struggle with smaller scale CI features mentioned above. However, if convection develops in the afternoon cannot rule out a few stronger or severe storms once again. This does look to be conditional on the terms that any early morning cloud cover/activity does not inhibit afternoon destabilization. Even greater destabilization is suggested by both NAM and GFS soundings heading into Tuesday. If they hold consistent, MLCAPEs will reach 1500J/kg or greater with DCAPEs in excess of 1000J/kg. However, increasing subsidence aloft as a sharpening ridge slowly meanders eastward should hinder vertical development. The potential for any additional stronger to severe storms will be something to keep an eye on for Tuesday afternoon but does not look too promising at this time. With the convective nature and PWATS in excess of 1.2 inches throughout this Sunday night - Tuesday timeframe, isolated flooding could develop in any locations that see training stronger activity. Ridging continues to build in mid-week, with increasing deep nwly flow. This should bring a relatively drier period with continued above normal temperatures. Broad troughing digs into the northern Great Lakes late week and into the weekend, flattening the ridge overhead. Chance PoPs return as a result. && .AVIATION... (00Z TAFS) Issued at 652 PM EDT Sat May 6 2023 Main concern during the TAF period is timing of showers and thunderstorms Sunday afternoon. Using HREF and latest HRRR runs will call for storms at TRI (19-20Z), TYS (20-21Z), and CHA (around 21Z). Otherwise, VFR conditions with winds becoming breezy out of the southwest tomorrow ahead of the broken line of convection. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 61 84 64 81 / 10 50 50 70 Knoxville McGhee Tyson Airport, TN 58 81 63 76 / 10 60 60 70 Oak Ridge, TN 59 80 62 77 / 10 60 60 70 Tri Cities Airport, TN 53 77 60 73 / 20 70 60 70 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...DH LONG TERM....KRS AVIATION...DH
Area Forecast Discussion
National Weather Service Nashville TN
833 PM CDT Sat May 6 2023 ...New UPDATE... .UPDATE... Issued at 824 PM CDT Sat May 6 2023 Currently no radar echoes are showing up in Middle Tennessee, and we expect very little activity until tomorrow afternoon. Overnight, the HRRR develops an MCS over IL/IN right along a warm front, and the remnants of this complex are projected to turn southward and cross into Middle Tennessee around 18Z tomorrow. In the meantime, an upper ridge situated over Middle Tennessee this evening looks to flatten out during the next several hours as the upper flow becomes more zonal. We also expect plenty of CAPE (~2200 J/kg, according to the NBM) to develop in the warm air mass tomorrow afternoon, so the atmosphere seems primed to support convective activity tomorrow afternoon and evening. In the near term, no forecast changes are planned. && .SHORT TERM... (This afternoon through Monday Night) Issued at 203 PM CDT Sat May 6 2023 Upcoming weather pattern leans toward an mcs northwesterly flow regime through this weekend. This is a little early for this type of pattern even though we are nearing the end of the organized severe weather Spring season. That said, a quasi stationary frontal boundary will setup across the midwest. A Strong southerly humid fetch will be in play south of the boundary with decent 850 mb mags. The upper levels will feature some ripples within the southwesterlies. As those components come together, mcs formation can be expected over the next several days. The first of 3 mcs systems will most likely stay to our north and east overnight. However low pops will still be in play, mainly for after midnight. Then on Sunday, another system will develop along the aforementioned boundary, with thermals sending the activity on a better trajectory to reach the mid state. Looks like pops will increase into the likely zone for late Sunday afternoon and through the evening. Rainfall amounts with this 2nd system look like 1/2 or so for most areas, but some localized 1-2 inch amounts cannot entirely be ruled out. System #3 will impact the area late Sunday night and into Monday morning. Depending on how worked over the airmass is, we could see some additional tstms for Monday afternoon as well. As for any severe potential, SPC has just upgraded our entire area to a marginal risk for that 2nd mcs which again, is scheduled for late Sunday afternoon and through the evening. As for the Monday mcs, the marginal covers our extreme north currently but that may very well be moved southward on the next update. So in a nutshell, a low end severe threat looks to be in play for Sunday evening and again on Monday. Straightline winds and hail will be the main threats. Mid level capes of 1000 j/kg and ml laps rates of 7.5C or so look to be in play by late Sunday afternoon. && .LONG TERM... (Tuesday through next Saturday) Issued at 203 PM CDT Sat May 6 2023 In the extended forecast, The boundary which served as the mcs catalyst in the short term period will finally move south and push through on Tuesday. Shower and tstm chances will continue although it just looks like general thunderstorms at this time. The boundary will work north as a warm front on Wednesday with the warmth and humidity sticking around. A fairly potent short wave on Thursday will act to cool the mid and upper levels and enhance our convective chances a bit. Pops will then back off as we reach the weekend. For the extended temperatures, with elevated humidity levels and the tendency for the mid state to remain south of the boundary features, you can expected above normal temperatures. That equates to lows 60 to 65 and highs generally 80 to 85. && .AVIATION... (00Z TAFS) Issued at 632 PM CDT Sat May 6 2023 VFR conditions are expected through the overnight hours. The gusts will cease, but S/SSW winds will remain 5-10 kts overnight. Some MVFR Cu could develop during the early to mid morning hours that could impact CKV/SRB/CSV. Ceilings should improve to VFR by 18z. There`s a lot of uncertainty regarding storm chances and timing late in the taf period. At this point, VCTS was included at all taf sites to highlight the potential for storms late in the afternoon. Winds will increase to around 10 kts late in the morning with some gusts to around 20 kts through the mid afternoon hours. && .PRELIMINARY POINT TEMPS/POPS... Nashville 66 87 66 84 / 20 70 90 90 Clarksville 66 87 66 85 / 30 70 80 80 Crossville 59 77 60 75 / 20 70 90 90 Columbia 64 85 64 84 / 20 70 80 80 Cookeville 62 80 62 77 / 20 70 90 90 Jamestown 59 78 60 76 / 20 70 90 90 Lawrenceburg 64 84 64 82 / 20 60 80 80 Murfreesboro 63 85 63 82 / 20 70 90 90 Waverly 64 84 64 84 / 20 70 70 70 && .OHX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......Rose SHORT TERM...21 LONG TERM....21 AVIATION.....Reagan
Area Forecast Discussion
National Weather Service New York NY
1025 PM EDT Sat May 6 2023 .SYNOPSIS... High pressure will settles over the area into Sunday morning. Multiple weak disturbances will move across Sunday night into Monday night as a weak cold front stalls to the south, and as weak low pressure moves along the front Monday night into Tuesday night. A trailing upper level disturbance may linger into Wednesday. High pressure will dominate from Wednesday night into Friday. The high will then weaken on Friday, which may allow a back door cold front to approach from the north and a weak frontal system from the southwest next weekend. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Some mid level clouds have developed across portions of the region this evening but are expected to scatter out and further decrease overnight. Made slight adjustments with hourly temperatures and dewpoints to better match observed trends. Otherwise, the forecast remains on track. Temperatures should cool decently into the overnight with weak high pressure moving overhead and thus a light pressure gradient with very little wind. Look for low temperatures to get a touch below normal, outside of the urban locations especially. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/... Look for plenty of sunshine in the morning with temperatures warming similar to what they did on Saturday. But with weak high pressure migrating east and dissolving look for more of a sea breeze component to the flow towards mid day to get underway, especially away from the coast. Also, upper and mid level moisture begins to advect in from the west in advance of a quick moving shortwave from the lower lakes and Ohio Valley. Towards late day look for an elevated overcast to develop, with the cloud deck lowering across western and southwestern sections very late in the day. The day should remain primarily dry, however a few sprinkles or light showers may get into far SW sections by early evening, and this possibility is being covered with slight chance PoPs. Temps will be similar to the previous day with perhaps western / inland locations being a few degrees warmer with 850 mb temps slightly warmer, and coastal locations being a few degrees cooler with more of a sea breeze influence into the afternoon on more of a S to SW component to the sfc wind. Overall temps look to average 5 degrees or so above normal. Sunday night look for light showers to overspread the area. Dynamics are weak with this system, so nothing more than perhaps a light wetting of the ground at most. Most of the guidance continues to show that much of the QPF occurs takes place during the first half of the night, with not much after 8-9z. Although the latest 12z run of the HRRR is showing the potential for the light rain to linger closer to 10-12z. Liquid amounts look to be light with amounts under a quarter inch. With cloud cover in place temps will a touch milder than previous nights, and average near normal. In the wake of the shortwave translating east and the weak sfc boundary getting through, look for the lower portion of the column to dry out Mon morning. The region should quickly get into a good deal of clear skies, especially across northern and western sections by mid morning. The remainder of Monday should feature a good deal of sunshine as a deep layered NW flow regime takes shape in response to an upper level low dropping into the Labrador region of Canada. Thus dry and cold advection win out, at least for the day on Monday. With deep layered mixing on an offshore flow look for temperatures to warm into the 70s, with a few upper 70s possible as temperatures average above normal everywhere. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... To start, the area will be on the SW fringe of a departing upper low over the Canadian Maritimes, with cyclonic flow aloft and embedded shortwave disturbances passing through. These should initiate weak cyclogenesis along a frontal boundary to our south and may throw sct showers into the area from late Mon night into Tue night, especially for NYC metro/Long Island daytime Tue into Tue evening. A trailing shortwave trough may lead to continued isolated/sct showers into daytime Wed, attm capping PoP for that at 20. Temps during this time frame will run a little below avg. Wed night through daytime Fri look dry and warmer with heights rising aloft and sfc high pressure building in. Temps could reach 80 in NE NJ and the interior CT river valley Fri and possibly on Sat depending on how far south a back door cold front drops in the wake of an upper trough diving SE across New England Fri night or Sat, which looks uncertain. A frontal system to the SW may also start to make an approach beginning Sat night, but this too is uncertain and is more likely than not to be delayed compared to NBM fcst. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... High pressure continues to build into the area overnight and then south and east of the area on Sunday. VFR conditions are expected through Sunday. Chances for MVFR are forecast Sunday night as rain showers move in from the west. NW to SW flow near 5-7 kts will decrease with winds becoming variable in direction for terminals outside of NYC tonight. NYC terminals winds expected to eventually become NW around 5 kts overnight. WNW to W winds under 10 kt Sunday morning will become S-SW in the afternoon near 10-12 kt. Winds will increase to near 15 kt for some coastal terminals by late Sunday afternoon with some gusts up to 20 kt. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Timing of southerly wind direction Sunday could be off by a few hours. ...OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... Sunday Night: Rain showers with MVFR possible. Monday: VFR. Slight chance of showers and MVFR late at night. Tuesday: Chance of showers with MVFR. Wednesday: Mainly VFR. Slight chance of showers with possible MVFR during the day. Thursday: VFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/ && .MARINE... Winds diminish late this evening, with a light W to NW flow prevailing overnight into Sunday morning. Toward Sunday afternoon winds should become more SW-S with a few gusts for the south shore bays and the ocean waters approaching 20 kt at times. Sub SCA conditions will prevail into Monday, with winds becoming briefly more N-NW in the AM, then more SW on the ocean in the afternoon. Continued quiet cond longer term from Mon night through Fri with a weak pressure gradient in place for wind waves, and no appreciable incoming swell. && .HYDROLOGY... No hydrologic concerns exist through the period. && .TIDES/COASTAL FLOODING... For the Sunday evening / night high tide cycle with an easterly swell the western south shore bays of mainly Nassau and perhaps a few gauges in Queens will approach minor coastal flood benchmarks. This possibility also exists for Fairfield, CT gauges along western LI Sound. At this time it appears that any exceedance of minor thresholds would be under 2/10ths of a foot, thus a statement may be needed for these locations at some point and will be evaluated in subsequent cycle(s). && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JE/BG NEAR TERM...JE/BG/JM SHORT TERM...JE LONG TERM...BG AVIATION...JM MARINE...JE/BG HYDROLOGY...JE/BG TIDES/COASTAL FLOODING...
Area Forecast Discussion...UPDATED
National Weather Service Paducah KY
857 PM CDT Sat May 6 2023 .UPDATE... Issued at 856 PM CDT Sat May 6 2023 Low level moisture continues to increase as its advected in from the south and southwest. Dewpoints are in the mid to upper 60s area-wide at this hour. Capping inversion from ridging aloft kept a lid on things today but that looks to change in the coming hours. HRRR over the last few runs liked to upscale ongoing convection over northcentral MO into an MCS that moves southeast into SWIN and vicinity by 10-11 am while the NAM pushes the shortwave responsible for convection in TX/OK into the area by about 12`ish. The 00z HRRR seems to like a little of both. Either way once the upper level pattern switches from the current more hostile ridging to even a weak shortwave like what is over Texas expect we will see an uptick in convection and made some PoP adjustments to increase them through the midday hour a bit as even the GFS has dewpoints in the low 70s by noon tomorrow. This gives us about 2500-3000 J/kg of MLCAPE although deep and low level wind shear is quite weak. Pulse/slow-moving storms that may become severe with a wind/hail risk and heavy rain from training convection still appears quite possible. UPDATE Issued at 622 PM CDT Sat May 6 2023 Updated for 00z TAFs && .SHORT TERM...(Tonight through Monday night) Issued at 253 PM CDT Sat May 6 2023 The main focus of the short-term portion of the forecast will be the potential scattered showers and thunderstorms at almost any given time with increasing moisture and instability. Overall forecast confidence is lower than average through much of the period; however, confidence does increase to some extent as a cold front sinks through the area Monday into Monday night. Much of this forecast period will have to be monitored closely for changes in model/radar trends along with changes in severe weather potential each day. Into this evening: An elevated supercell/cluster of storms that has been persistent through the morning into this afternoon across central Illinois is expected to continue to drift to the east/southeast into early this evening. The storm has been following the instability gradient, which has been gradually lifting to the northeast across the area. This may end up keeping the storms easterly component in tact for a bit longer. There is plenty of instability around for the storm to work with and shear values are analyzed around 40kts. Capping across the area has limited development away from that storm and will is likely to keep the storm from becoming surface based; however, large hail will be possible from the cluster of storms into this evening. The greatest threat area in the CWA will likely be up near Edwards and Wabash counties in IL and Gibson and Pike counties in southwest IN. Tonight through Sunday night: Upper level ridging across the Quad State is expected to gradually weaken/flatten through this time period. This will likely be a result of a shortwave drifting across southern MO into the area Sunday into Sunday evening. There are still significant differences on how the convective evolution plays out with this feature as well as where exactly the feature tracks. Continued the trend of keeping scattered showers and thunderstorms going across the area through much of this time period; however, there will likely be more coverage on Sunday than there was across the area today. Again, that will be a result of the ridge weakening and the cap weakening. It does look like there may be some low-level outflow boundaries around that may act as the trigger for late morning and early afternoon focus, but where those set up will be the main concern for increasing pops. Strong to severe thunderstorms will be possible by Sunday afternoon/evening as instability values are progged to be around 2000-3000 J/kg with shear up to 40 kts once again. The main threat will be very heavy rainfall, large hail and damaging winds. In fact, the SPC has now place much of the Quad State in a Marginal Risk of severe weather for Sunday. Again, still a lot of uncertainty on how this unfolds. Highs will be in the mid 80s for Sunday. Lows will be mainly in the mid to upper 60s. Monday into Monday night: Models continue to show the cold front north of the area drifting south through the day Monday into Monday night. This may help to focus more showers and thunderstorms across the area through this time period, but the exact timing an placement of the front will also be largely influenced by MCS development and outflow from those events. Did trend shower and thunderstorms chances up across most of the area for late Monday afternoon into Monday evening. Instability values are expected to be around 3000- 4000 J/kg across the Quad State; however, the strongest shear looks to be just north of the area across central IL into central MO. That area is where the SPC has highlighted the Slight Risk of severe weather. Most of the Quad State is in the Marginal Risk as the frontal boundary sags south. Any of the storms would have the potential to produce very heavy rainfall, damaging winds and hail Monday afternoon into Monday evening. Highs are expected to warm into the mid to possibly upper 80s! Lows will be mainly int he 60s. .LONG TERM...(Tuesday through Saturday) Issued at 253 PM CDT Sat May 6 2023 The synoptic setup will remain quite unsettled with daily chances for showers and thunderstorms along with above normal temperatures. Although confidence in the forecast is lower than average, periods of dry weather are still likely through the week. For Tuesday, a cold front will slowly move south of the FA. Pcpn chances remain possible, especially in the afternoon across western Kentucky towards the KY/TN border as there is some uncertainty in how quickly the front clears. The 12z deterministic GFS which is a bit slower shows MLCAPE values of 2000 to 3000 J/kg and lapse rates of 7.0 to 7.5 C/km, but meager deep-layer shear of 20 to 30 kts. Any storms that develop will have the potential to produce frequent lightning and heavy downpours. As sfc high pressure builds over the Great Lakes region, drier air will filter in behind the front by Tuesday night. High temps will reach the low to mid 80s with lows falling into the upper 50s to lower 60s. With that said, an upper-level ridge will provide some relief from the humidity and pcpn chances on Wednesday as a trough digs across the western CONUS. Have limit NBM PoPs to only a slight chance given the FA will be directly beneath the ridge axis. As a 500 mb disturbance rounds the ridge Thursday afternoon ahead of a closed low the ejects across the central CONUS, pcpn chances begin to increase once again with daily chances peaking Friday and Saturday afternoon. Differences in model guidance make it hard to pinpoint exact timing of convection, but intervals of dry weather are still likely. Highs each day will remain above normal in the low to mid 80s with lows falling into the low to mid 60s. && .AVIATION... Issued at 622 PM CDT Sat May 6 2023 Through the evening expecting some of the 3000-3500 ft cu/stratus to dissipate with prevailing VFR through the next few hours. A couple of showers/thundershowers are departing SWIN to the east. No additional convective development is expected for the next few hours. Another surge of lower level moisture is expected overnight and a 1700-2500 ft cloud deck is likely to develop in the pre dawn hours. That deck may lift above 3000 by late morning, but shower and thunderstorm chances will increase through the day. Have PROB30 groups at each site for the times convection is most likely but it could be a bit earlier. Several models show slow moving/persistent storms through the afternoon and will need to be alert for that possiblity and extended degraded flying conditions. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...JGG SHORT TERM...KC LONG TERM...DW AVIATION...JGG
Area Forecast Discussion
National Weather Service Pendleton OR
813 PM PDT Sat May 6 2023 .SHORT TERM UPDATE...Scattered showers and thunderstorms developed this afternoon across central and north central Oregon ahead of an approaching negative tilt shortwave. Storms have been relatively weak, although small hail and heavy rain have accompanied some of the storms. Many automated stations over the southern Blues, Ochocos, and central Oregon have measured 0.2-0.6" of rain. Although showers continue on radar, the lightning activity is waning. Water vapor loops show the shortwave parked over far southern Oregon, and the trough will gradually lift north tonight. This will keep showers south of the Washington border tonight and most of Sunday. The best chance (40-60%) will be from the Blue Mtns eastward on Sunday. The shortwave trough will stretch apart as it encounters a split flow over far northern OR. Any threat of thunderstorms will be over far NE OR over Wallowa County with a slight chance (20%). CAMS have less than 200 J/kg of both SBCAPE and MUCAPE over Wallowa County, and the HRRR seems to be the only member of HREF advertising high reflectivity potential in NE OR. Only a few minor adjustments were made to the forecast, including removing thunderstorms in a few zones for the rest of tonight. Wister/85 && .PREV DISCUSSION... /issued 335 PM PDT Sat May 6 2023/ SHORT TERM...Monday, an upper closed low will swing through the large scale trough and across the PacNW through Monday night, resulting in the best day for widespread rain showers and widely scattered embedded thunderstorms. Monday looks to be the best day of instability support through the period, with MUCAPE values around 1000 J/kg and moderate lower to mid level lapse rates across the eastern mountains. However, wind shear aloft will again be limited, but still expect thunderstorms to develop mainly across the eastern Basin and eastern mountains through the afternoon and early evening. Locally breezy winds will also develop and persist as the upper low tracks over the forecast area through Monday evening. Hydrology concerns have continued to decrease across the region as heavier precipitation has either been isolated, or has been falling to the south of the region. However, snowmelt will continue to lead to high rises on area streams and rivers, with portions of the Grande Ronde, Naches, and Imnaha rivers expected to be in or near bankfull. A river flood warning for the John Day River at Service Creek will continue through the mid week as it runs at minor flood stage. Lawhorn/82 LONG TERM...Tuesday through Saturday...Models are in good agreement through the long term period. Initially, a trough will be over the west coast with a weak low pressure center either over our area or near the Washington/Oregon coast. This will give us showery weather Tuesday. By Wednesday, the trough will have deepened all the way into Arizona while the weak low pressure will move into the Canadian Rockies. this will give us more showery weather Wednesday though QPF amounts look to be very light. Wednesday night and Thursday, the trough will move east and another upper low and trough will be strengthening in the Gulf of Alaska. The circulation around this low will see a southwest flow into our area and start building a ridge over the Pacific Northwest. This will give us dry and warmer weather. The ridge will remain over our area through the rest of the long term period and will steadily strengthen. This will give us dry weather and a warming trend with temperatures rising from the 50s and 60s Tuesday to the mid 70s to upper 80s by Saturday. The Extreme Forecast Index indicates little in the way of unusual weather in the long term. The most unusual indicator is -0.63 for low temperatures Wednesday morning and that is highlighted mainly over the Oregon Cascades and not over the rest of the area. Cluster analysis shows only minor differences between the models on Tuesday. On Wednesday there are some disagreements about the depth of the trough over the area and the strength and location of the developing ridge off the coast, though it should not affect the forecast too significantly. Thursday through Saturday, models are in agreement in having a ridge overhead though they have differences about the strength of the ridge, with the ECMWF having most ensemble members favoring the stronger ridge while the GFS is weakest. Cluster phase space analysis shows above normal spread in the model ensemble members though deterministic runs are well centered with their respective ensemble means. Overall forecast confidence is average. Tuesday will start with a trough over the west coast centered just offshore. Models agree in having a weak closed low a few hundred miles off the Pacific Northwest coast and a second weak closed low over our area. This will give us a chance of mountain rain showers and a slight chance of lower elevation rain showers. Models also have a slight chance of thunderstorms over the northern Blue Mountains and Wallowa County in the afternoon. Rain amounts will be up to two tenths of an inch in the eastern mountains and less than a tenth of an inch elsewhere. Most locations will have just a hundredth or two of rain. Snow levels will be around 4500 feet so the higher mountains could get an inch or two of snow. Highs will be in the upper 50s and 60s with upper 40s to mid 50s in the mountains. Rain will end Tuesday evening as the trough axis moves ashore and then east of our while with the weak lows overhead weakening to the point of dissipating. Lows will be in the upper 30s to mid 40s with upper 20s to mid 30s in the mountains. On Wednesday, a ridge will be building off the Pacific Northwest coast and the trough axis will move into eastern Nevada and Utah though a weak circulation will remain over northern Washington. this will allow a chance of rain showers over the eastern mountains though amounts will be barely measurable. Temperatures will be about 5 degrees warmer than Tuesday. Thursday and Friday will have a large upper low in the Gulf of Alaska and another low in eastern Montana and Wyoming. This will promote the strengthening of the ridge which will move ashore over our area. This will give us dry weather with temperatures in the 70s with 60s in the mountains Thursday and in the upper 70s to mid 80s with upper 60s to mid 70s in the mountains Friday. The ridge will strengthen further by Saturday and temperatures will warm to the 80s with 70s in the mountains. Perry/83 AVIATION...00Z TAFs...Scattered showers and thunderstorms are in central OR with one currently at RDM. These have been weak garden variety storms but enough to have small hail covering the ground. OCNL CG strikes have been observed with these storms. The negative tilt shortwave will spread showers to NE OR and SE WA early Sunday morning. Any t-storms will be isolated and will end by midnight. Showers will reduce CIGS and VSBYS, and confidence was high enough to include MVFR conditions at BDN, RDM, PDT and ALW. Other TAF sites will show VFR. Winds over the next 24 hours will mainly come from the WSW 8-13 kts with gusts 20-25 kts. Wister/85 && .PRELIMINARY POINT TEMPS/POPS... PDT 45 61 41 64 / 20 30 20 70 ALW 48 65 46 69 / 10 20 10 70 PSC 50 69 47 72 / 10 10 10 30 YKM 45 67 44 68 / 10 10 0 40 HRI 48 67 44 69 / 20 20 10 50 ELN 44 63 42 66 / 0 10 10 30 RDM 39 58 38 54 / 70 20 20 70 LGD 42 56 39 62 / 40 50 30 80 GCD 40 56 37 58 / 80 60 30 90 DLS 48 66 47 66 / 20 20 10 50 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...85 LONG TERM....83 AVIATION...85
Area Forecast Discussion
National Weather Service Shreveport LA
1000 PM CDT Sat May 6 2023 ...New UPDATE... .UPDATE... Issued at 937 PM CDT Sat May 6 2023 As of 9:45PM CDT, southerly winds prevail as cloud tops from showers and thunderstorms to our west drift eastward. Most short- term guidance indicates that tonight`s round of showers and thunderstorms over north central Texas is expected to linger once again as it moves into east Texas with remnants potentially drifting into our zones overnight. With forecast grids already accounting for this potential, no additional edits were necessary at this time. /16/ && .SHORT TERM... (This evening through Sunday Night) Issued at 235 PM CDT Sat May 6 2023 Subsidence behind the passing MCS overnight has started to become replaced by a developing cu field as post frontal gulf moisture resurges northward. Dew point values have continued to slowly increase across the region following the vertical mixing this morning which helped to provide some relief. To the west, a rinse and repeat setup will be underway once more as dryline initiated convection across central TX this afternoon will translate east into the evening, and overnight. Similar to previous afternoon solutions, hi-res guidance paints the image of a developing MCS that enters the western zones of the FA late tonight and into early Sunday AM, fizzling out ahead of sunrise. A slight risk is present across our extreme western zones including counties in E/TX and SE/OK, with a small marginal risk further east into SW/AR. A general thunder risk exists everywhere else. Primary concerns with this, similar to previous nights events, will be damaging winds and some hail. By Sunday morning, as the MCS decays, RAP analysis continues to highlight sufficient 925mb RH values to get a handle on the idea for low cloud coverage to be in place through the morning and afternoon. Even though the ridging pattern will still remain in place aloft, guidance continues to point out small perturbations within the flow that would be just enough support to help kick off diurnal afternoon/evening convection given some sfc warming and scattering of the ceilings. Given the enhanced low level coverage tomorrow, this may support temperatures trending a few degrees cooler than this afternoon, but regardless of the coverage, a warm Sunday with plenty of humidity looks to be back on the menu. Heat index values pushing the low 90s should not be ruled out. Looking to Sunday evening, the aforementioned developing diurnal convection looks possible ahead of and carrying over after sunset. Conditions should dry out though overnight, ahead of Monday morning. For temperatures through the period, given the passing sfc boundary, southerly sfc flow will support summer-like afternoon highs and warmer overnight lows. This evening, expect a similar output to last as lows fall into the upper 60s and low 70s. Given the moisture resurgence resulting in higher dew points, humidity will sick around through the overnight. As previously mentioned, highs on Sunday may fair a few degrees cooler than today given cloud coverage. Regardless, highs in the upper 80s are be expected ahead of overnight lows in the upper 60s and low 70s into Monday AM. RK && .LONG TERM... (Monday through next Friday) Issued at 235 PM CDT Sat May 6 2023 An unsettled and uncertain pattern will continue through at least the end of the upcoming work week. Southwesterly flow aloft will persist over the region bringing a series of weak upper disturbances across the forecast area. Despite the lack of well-defined surface synoptic features to help focus convective development, scattered showers and thunderstorms will be possible every day. The greatest convective coverage will be from the afternoon through the early evening hours during peak diurnal instability. Thunderstorms should gradually diminish during the nighttime hours, but the how long convection will last into the night or early morning hours on any given day is very uncertain. The southwesterly flow aloft will amplify somewhat and large scale forcing will increase over the region during the latter half of the week as a strong upper trough moves across the Northern CONUS. Therefore, our best rain chances will generally be during the afternoons of Wednesday, Thursday, and Friday. Thunderstorms are most likely northwest of a line from Lufkin to El Dorado where ascent and instability should be maximized with the arrival of thunderstorms approaching from Oklahoma and Texas. Given the very warm temperatures and the unstable atmosphere that will be in place, severe weather cannot be ruled out on any day. Damaging winds and large hail will be the primary threats. In addition, if a location experiences multiple locally heavy rain events from the daily thunderstorm complexes, isolated flooding issues could become a concern late in the week. Temperatures will remain very warm during the first half of the work week. Most locations should warm well into the 80s. Portions of Louisiana and Southern Arkansas that remain mostly-precip free could warm into the lower 90s during the afternoons. Combined with the humidity, this will result in high index values in the lower to mid 90s. For Wednesday through Thursday, the higher rain chances and associated cloud cover should help to cool temperatures down a few degrees. However, this was not reflected in the NBM, which kept afternoon highs relatively steady and even warmed them some. The NBM was by far the hottest guidance compared to the other models. Therefore, I trend afternoon highs below the NBM Wednesday through Friday by generally using a blend of the NBM and the NBM 25th percentile. CN && .AVIATION... (00Z TAFS) Issued at 624 PM CDT Sat May 6 2023 For the 07/00Z TAF update, VFR vis/cigs will continue through 07/05Z before the next round of -TSRA/-RA that is expected to linger across the airspace with MVFR/IFR through 07/12Z before dissipating. VFR vis/cigs are expected to return by 07/18Z as cloud decks lift and scatter once again. /16/ && .PRELIMINARY POINT TEMPS/POPS... SHV 70 87 71 88 / 30 40 20 40 MLU 69 87 70 87 / 20 30 20 40 DEQ 67 84 67 86 / 40 40 20 20 TXK 70 86 70 88 / 30 40 20 30 ELD 67 86 68 87 / 20 40 20 30 TYR 70 87 71 89 / 60 50 20 30 GGG 70 85 70 87 / 40 40 20 40 LFK 71 87 71 88 / 30 40 10 40 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ SHORT TERM...16 LONG TERM....09 AVIATION...16
Area Forecast Discussion
National Weather Service San Angelo TX
630 PM CDT Sat May 6 2023 ...New AVIATION... .SHORT TERM... (This evening through Sunday) Issued at 211 PM CDT Sat May 6 2023 ...Scattered strong to severe thunderstorms expected to develop across northern and eastern portions of West Central Texas this afternoon into this evening... Satellite and radar images indicate some convection...mostly elevated...developing across extreme southeast portions of the CWA this afternoon. The latest HRRR progs convective initiation across the northern and western counties between now and this evening...mainly along the surface dryline. The dryline will be a focus for showers and thunderstorms to develop this afternoon into this evening and it appears the strongest convection will be across the Big Country region this evening. SPC continues to advertise a slight to enhanced risk of severe weather across the northern and eastern portions of the CWA for this afternoon and evening. The main hazards are very large hail (up to baseball size possible) and damaging winds (60 to 80 mph) but an isolated tornado cannot be ruled out. Southwest flow aloft will continue to bring weak upper level impulses across portions of northwest Texas tonight into tomorrow. The dryline will continue to provide a focus for showers and thunderstorms to develop across portions of west central Texas Sunday afternoon. SPC has a marginal to slight risk of severe weather across northern and eastern portions of the CWA tomorrow. Large hail and damaging winds will be the main weather hazards for && .LONG TERM... (Sunday night through next Friday) Issued at 211 PM CDT Sat May 6 2023 ...Hot and unsettled pattern to continue for the foreseeable future... Not a whole lot of change from the previous long-term forecast. The mid level ridge that has been the key player in our storm chances the past few days will continue to drift off to the east. By Monday the area will be in generally quasi-zonal flow with a broad, mid- level trough beginning to take shape off of the west coast. This will allow flow over our area to transition back into weak southwest flow. This overall setup will help to continue the hot and unsettled pattern we`ve been seeing over the past few days. Surface winds out of the south will help to keep a moist boundary layer in place. This, in turn, will allow the dryline to continue to take shape and mix east during the day. Monday and Tuesday will see this dryline activity allowing for chances of strong to severe storms with large to very large hail being the main hazard along with damaging winds. With continued moisture and afternoon highs expected to be in the 90s, SBCAPE values will be in the 2000-3000 J/kg range each afternoon with steep low level lapse rates. As these storms are generally expected to be high based, the tornado threat will remain limited with a greater straight line wind threat from potential downbursts. Activity these days currently looks to be more isolated/scattered in nature and will greatly depend on both the shortwave disturbances that move overhead as well as how far east the dryline can mix through the day. The aforementioned mid-level trough will begin to move east into the Western CONUS late Monday before pushing north and east into the Central Rockies by late Tuesday into Wednesday. The trough is expected to deepen into a low and stall out over the north central Rockies. This will put our area in weak south to southwest flow for the end of the week and into the weekend. This will also usher in some mid-level height falls, allowing temperatures a cool a few degrees back into the 80s and lower 90s, starting on Wednesday. Global models have backed off on precipitation chances for the end of the work week, especially on Friday, so we have followed suite with the forecast. That being said, both show very wet weekends with highly saturated atmospheric profiles and widespread showers and storms. With very little synoptic convergence expected, the current thought is that showers will be influenced by perturbations in the flow aloft. We are optimistic that this will hold true as much of the area is still in desperate need for rain but it`s certainly not a guarantee. We will keep a close eye on the end of the week but overall the warm and unsettled pattern that is typical for spring down here will continue for the foreseeable future. && .AVIATION... (00Z TAFS) Issued at 619 PM CDT Sat May 6 2023 Thunderstorms developing over KABI at 2330Z will move northeast, with strong gusty winds up to 40 KTS and IFR visibilities in heavy rain. Storm should be east by 2Z. MVFR visibilities otherwise return after midnight and continue through midmorning. && .PRELIMINARY POINT TEMPS/POPS... Abilene 67 93 65 97 / 50 30 20 10 San Angelo 68 95 64 99 / 40 20 10 10 Junction 68 94 64 97 / 20 20 10 20 Brownwood 65 91 64 95 / 50 20 20 10 Sweetwater 66 94 65 97 / 20 30 10 0 Ozona 69 92 63 95 / 10 10 0 10 Brady 67 91 65 94 / 30 20 10 20 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...61 LONG TERM....50 AVIATION...04
...Update to aviation forecast discussion...

.DISCUSSION... Issued at 252 PM CDT Sat May 6 2023 Key Points: - Near-record temperatures continue this afternoon and Sunday afternoon. - Severe storms possible across portions of northern Kansas Sunday evening and into Monday morning. - Active weather pattern continues into next week with persistent rain chances. Mid-level water vapor imagery this afternoon shows the synoptic omega block beginning to break down as the upper low over the PNW moves south down the west coast, and the other low moving northeast towards Nova Scotia. The upper ridge axis has shifted into the Mississippi valley region as southwest flow has continued to pump in very warm air into the central Plains. Under ample insolation and persistent WAA, temperatures in northeastern Kansas this afternoon have climbed into the upper 80s with continued warming expected through the daylight hours. Further details on near-record high temperatures can be found below in the Climate section. A surface low has slowly moved over the area today and will slowly veer winds towards the west then to the north as it progresses east overnight tonight. This wind shift will be short-lived as winds return back to the south by Sunday AM ahead of the next lee cyclone. By Sunday, another warm day will be expected as WAA, BL mixing, and lots of sunshine will raise temperatures into the low to mid 90s again. Low level moisture will stay near-stationary in far eastern Kansas, making it feel a bit humid when compared to central Kansas where deeper mixing and the passage of a dry line should drop afternoon RH values. Attention then turns to a threat of severe weather, mainly across portions of northern Kansas. CAMs have continued to depict an MCS developing ahead of a diffuse upper-level vorticity max embedded in southwesterly flow Sunday afternoon in south-central Nebraska. At this time, there still seems to be a large degree of uncertainty due to a few factors: how far north the warm front lifts throughout the day Sunday, where the boundary stalls during the late afternoon, and where the nose of the LLJ will end up. The NAM and the Euro are the furthest south with their solutions and thus bring severe weather more into our area than other model guidance. Solutions such as the HRRR and ARW keep the boundary further north of the area with convective development and propagation north and east as well. Regardless, if convection can develop along the boundary, parameters such as MUCAPE of 4000 J/kg, 0-6 bulk shear around 40 knots, and curved hodographs could lead to all modes of severe weather with large hail and strong winds being the biggest threats. By Monday and into next week, the active summer-like pattern continues with persistent precipitation chances almost everyday. The best chance for rain appears to come Wednesday as a boundary stalls over the area with waves of energy continuing to pass overhead. Another upper low will dig out of the PNW with additional chances for rain and storms for the later half of the week. Temperatures will remain consistent throughout the week and in the 80s before a cooler pattern begins to set up by the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 619 PM CDT Sat May 6 2023 Following the dryline passage, winds will continue to veer to the northwest and weaken over the next few hours. However after midnight they will veer back to the southeast, eventually becoming southerly 10 to 15 kts by tomorrow morning. VFR conditions persist, with just a few high clouds from remnant thunderstorm anvils over Oklahoma. Any shallow fog or mist looks to stay to our northeast. && .CLIMATE... Issued at 254 PM CDT Sat May 6 2023 Topeka Record High Temperatures Forecast Record Year Saturday (5/6) 95 92 1916 Sunday (5/7) 93 94 1934 Concordia Record High Temperatures Forecast Record Year Saturday (5/6) 91 94 1955 Sunday (5/7) 94 99 2014 && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Griesemer AVIATION...Reese CLIMATE...Griesemer
Area Forecast Discussion
National Weather Service Tulsa OK
744 PM CDT Sat May 6 2023 ...New UPDATE... .UPDATE... Issued at 744 PM CDT Sat May 6 2023 Theme of going forecast left unchanged this evening. Cluster of storms over western north TX beginning to show some eastward advance, falling in line with what CAMs have been suggesting earlier today. The near term PoPs were adjusted downward and then trended closer to going forecast later this evening to better line up with storm timing. Latest HRRR still shows some potential for severe gusts into SE OK later tonight along surging consolidated cold pool from the storms. As previous shift mentioned, there remains potential for strong to near severe gusts well away from the stronger convection as forecast soundings show saturation aloft and a deep dry EML beneath (onion profile). Tried to incorporate some of this potential into the wind gust grids. Typically, a necessary ingredient for severe wind potential in these scenarios is a strong LLJ, which will be lacking tonight. Keep slight chance to chance PoPs from the blend later tonight into early Sunday with some potential for elevated storms continuing. Lacy && .SHORT TERM... (Through tonight ) Issued at 225 PM CDT Sat May 6 2023 Warm and humid conditions supporting a strongly unstable airmass across the region this afternoon. Storms are expected to develop across NW TX into far S OK by late afternoon. Relatively weak steering flow and an eventual increase in the low level jet yields slow eastward storm motions. The result is an eventual upscale expanding convective cluster than could organize into a more forward propagating system and move into SE OK by late evening through the early morning hours. Several guidance sources indicate conditions favorable for strong winds well removed from the strongest storms and fcst soundings suggest profiles supportive of these evaporatively aided winds. Should this develop this pockets of stronger winds may persist into the overnight hours. Additionally, elevated convection may not entirely wane overnight and low chances of persistent storms will be retained through Sunday morning. && .LONG TERM... (Tomorrow through Saturday) Issued at 225 PM CDT Sat May 6 2023 Isolated to scattered early day convection may be ongoing Sunday primarily across SE OK through western AR. By afternoon focus will again turn to areas across western OK and NW TX as storms develop along the dryline. These storms will likely spread slowly eastward and possibly into the local forecast area with a gradual weakening trend. The forecast become more uncertain by Monday but the idea of a weak frontal boundary and associated storms moving into the region Monday night into Tuesday remains present and the forecast continues to favor this scenario. Thereafter the flow aloft becomes notably weaker across the southern Plains. Various scenarios exist for potential weak upper low centers meandering across the region amidst a moist airmass. The pattern, while nondescript, will support daily shower and storm chances through the remainder of the week. Severe weather chances will remain low given the weak flow. && .AVIATION... (00Z TAFS) Issued at 628 PM CDT Sat May 6 2023 Main issue in the near term will be thunderstorm potential across southeast OK and potentially western AR. Storms currently over NW TX will continue to move east-northeast, potentially reaching KMLC by around 03-04z, with gusty sfc winds. Potential is more uncertain farther east into Arkansas later tonight into early Sunday morning. Also potential for MVFR ceilings to spread into SE OK early Sunday morning for a few hours, with VFR prevailing otherwise. && .PRELIMINARY POINT TEMPS/POPS... TUL 67 87 67 87 / 30 20 20 20 FSM 68 86 68 87 / 30 30 20 20 MLC 67 85 66 86 / 50 30 20 10 BVO 63 87 62 87 / 20 20 20 20 FYV 65 84 65 84 / 30 30 20 20 BYV 67 83 67 84 / 20 30 20 30 MKO 66 84 67 84 / 30 30 20 20 MIO 68 85 67 85 / 30 30 20 30 F10 66 85 66 86 / 40 20 20 10 HHW 66 82 66 84 / 60 30 30 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...07 LONG TERM....07 AVIATION...14