####018007453#### FXUS61 KCTP 160845 AFDCTP Area Forecast Discussion National Weather Service State College PA 445 AM EDT Fri May 16 2025 .SYNOPSIS... * Periods of rain and thunderstorms through Saturday with some potential for localized damaging winds and flooding downpours * Temperatures trend warmer Friday and Saturday with a notable uptick in humidity to end the week * Breezy, cooler, and much drier (less humid) end to the weekend with rain-free conditions into early next week && .NEAR TERM /THROUGH TONIGHT/... Pockets of locally dense fog and low visibility could make driving conditions hazardous through sunrise across the central and eastern portion of the forecast area. Will be considering SPS/DFA based on latest ASOS/RWIS visibility trends. Overnight convection/MCS has been confined largely to the Lake Erie vicinity. Although the intensity varies from model to model, the latest hires guidance is in agreement with convection expanding to the southeast across the Allegheny Front through 12Z/8AM and eventually shifting eastward across central PA through midday. We are monitoring storm clusters tracking southeast from near Erie, PA. Brief gusty winds and small hail may be possible for the next hour or so with this cell as it continues to move southeast toward Warren County. Additional thunderstorms may develop later this morning along/ahead of the MCS, but the overall environment should remain unsupportive of an organized severe threat. Therefore, a watch is not anticipated per recent SPC MCD #804. A Flood watch remains in effect for Somerset and Bedford counties, although confidence in heavy rain potential has been steadily decreasing early this morning based on short term model and radar trends. In the wake of the AM convection, the afternoon t-storm setup looks more nebulous given the absence of a strong forcing mechanism. There will be plenty of instability available (MLCAPE 1000-2000 J/kg) with cloud breaks yielding strong sfc heating within a very moist (mid- summerlike) boundary layer comprised of Td in the 65-70F range over south central PA. The lack of deep layer shear suggests the primary threat this afternoon could be isolated downburst wind gusts/hail or drenching downpours which could result in localized flooding -- particularly in areas that have been hit the hardest over the last few days. Max temps will be +7-15 degrees above mid May climo with highs in the 75-85F range. While the D1 SLGT risk outlook area covering south central PA does capture the best (albeit isolated) strong/severe storm potential prior to 00Z/8PM, one has to think that it may be drawn with eye toward downstream evolution of projected bowing segment tracking eastward from the Ohio Valley late tonight into the predawn hours Saturday (00-12Z Saturday window). This area appears to be on the far northern periphery of whatever linear feature emerges based on recent HRRR/RRFS model runs. Therefore, the precip fcst for tonight is highly uncertain. Lows tonight in the 55-65F range will be very mild at +15-20F above the historical average. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... A cold front will traverse the CWA by Saturday evening and likely be accompanied by scattered showers and few t-storms. The best svr potential will be ahead of the front over the eastern 1/4 of the forecast area where the HREF shows best instability collocated with more favorable 0-6km shear profiles. SPC expanded the SLGT risk farther to the north with the initial D2 outlook, however there remains some questions around the quality of the much weaker buoyancy vs. Friday. The strong shear could offset that to some extent, and cooling temps aloft could help in increasing the potential for strong/damaging wind gusts. A cooler, cyclonic/NW flow pattern persists for the remainder of the weekend. Sunday looks rather breezy with frequent 25-35 mph wind gusts. Max temps cool down by ~10 degrees across the board day over day with fcst highs in the 60-75F range. There may even be some lingering or diurnal showers Sunday PM especially in the northern tier beneath the pocket of coldest temps aloft. NW breeze should gradually weaken Sunday night with lows in the 45-55F range or within a few degrees of climo. && .LONG TERM /MONDAY THROUGH THURSDAY/... Dry conditions continue into the beginning of the long-term period as an upper-level ridge supplies fair conditions through Tuesday afternoon. Increasing moisture on Tuesday leads to a notable uptick in cloud cover for the second half of the day for most, especially across the Laurel Highlands as the next system pulls closer to the region. Temperatures for Monday and Tuesday are expected to trend slightly below seasonal averages, especially during the daytime hours. Model guidance promotes two different solutions for the area of low pressure approaching central Pennsylvania in the late Tuesday/early Wednesday timeframe. ECMWF/GDPS guidance tend to keep the approaching area of low-pressure west of the area for quite longer and does keep highest chances for precipitation until Wednesday afternoon/evening. Recent GFS/UKMET guidance outline a solution where the surface low-pressure dive further south and station over MD by Wednesday morning, allowing for precipitation chances to increase Tuesday night into Wednesday morning across the area. Given some model differences, have stuck close to NBM guidance while also trimming back timing on precipitation slightly due to some low-level drier air in place. After precipitation onset, generally expect showers to continue through the end of the long-term period given favorable moisture and lift associated with the area of low- pressure. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... Fog and lowered cigs starting to affect multiple TAF sites as temperatures cool over moist ground/lower levels. Once formed expect conds to persist much of the overnight. Next concern for overnight will be a line of thunderstorms that are expected to move through the region in the 09-14Z timeframe. PROB30 groups have been added to all sites except MDT and LNS to highlight the most likely timeframe for impacts. These thunderstorms will likely be weakening as they move in from the west and encounter a more stable environment, but we can't rule out a few strong wind gusts, especially at western airfields. Conditions gradually improve during the late morning Friday behind the line of storms, but additional thunderstorms will likely develop Friday afternoon/evening. Outlook... Sat...Showers/storms especially in the afternoon. West winds gusting 30-35 kts. Sun...Some improvement, as a series of cold fronts move southeast of the area. Mon...Mainly dry with VFR conditions. Tue...VFR with scattered showers across the west late. && .CTP WATCHES/WARNINGS/ADVISORIES... A flood watch is in effect form late tonight through Friday morning for Somerset and Bedford counties. && $$ SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Steinbugl LONG TERM...Beaty AVIATION...Bauco/Gartner ####018003714#### FXUS65 KGGW 160846 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 246 AM MDT Fri May 16 2025 .DISCUSSION... KEY MESSAGES: - Rain, heavy at times continues this morning near the ND border and moves to the east this afternoon. - Lows tonight will be near freezing along the ND and parts of the Canadian border. - Next large rain system looks to arrive Sunday afternoon and remains over the area through Monday night. Heaviest rain is expected to be south of the Missouri River. WEATHER PATTERN OVERVIEW: Strong northern plains cyclone has occluded overnight. That means that it will begin weakening and then will push off to the east during the day today. But rain and strong winds over the eastern zones will continue most of today with the rain diminishing this afternoon and the winds diminishing this evening. Rainfall amounts have been as high as 1.6 inches in the Sidney area as of 2 am Friday. Strong surface pressure gradient with this system will keep NW winds going today and winds will diminish this afternoon in the west and this evening in the east. Will keep the Lake Wind Advisory in effect for Fort Peck Lake until 6 pm today. Weak waves in quasi-zonal flow aloft could bring some light rain to the western zones at times between this afternoon and Saturday night. The next deep upper trough/low moves into western Montana Saturday night and moisture associated with this system moves into eastern Montana during the day on Sunday. The models/ensembles track the upper low to the south of the forecast area Sunday night and Monday while bringing deep moisture into the area on SE flow aloft. The heaviest rain is expected to be south of the Missouri River. The probability of 0.50 inch rain varies from 30 percent NE to 70 percent SW with this system. The system moves to the east Monday night. Weak systems will bring frequent chances for light rain Tuesday and beyond. FORECAST CONFIDENCE & DEVIATIONS: High confidence in the rain in the east this morning and the gusty NW winds today. Low confidence in any showers occuring in the west between this afternoon and Saturday night. High confidence in the rain coming Sunday and Sunday night with low confidence in rainfall amounts. Went slightly higher than the NBM for winds today and slightly lower than the NBM for lows in the east tonight where clear skies are expected. Also, added patchy fog in the east late tonight and Saturday morning when moist ground, light winds and clear skies should allow fog to develop. No other changes for now. && .AVIATION... UPDATED: 0830z FLIGHT CAT RANGE: VFR west and MVFR east this morning becoming VFR in all areas this afternoon. VFR tonight except in areas of fog which could be as low as LIFR at times. . Strong storm system over the eastern Dakotas will keep strong NW winds in place today along with steady rain this morning east of a KOLF- KMLS line. Rain will gradually diminish from west to east starting in the late morning and will end at KGDV and KSDY this afternoon. KSDY, KGDV and KOLF could have fog after 06z tonight with reduced visibility. Winds: NW 15 to 30 knots today with gusts as high as 45 knots. NW winds will diminish starting in the late afternoon and will become light and variable by 06z tonight. && .GGW WATCHES/WARNINGS/ADVISORIES... Lake Wind Advisory until 6 PM MDT this evening for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone- Petroleum. && $$ weather.gov/glasgow ####018005679#### FXUS64 KSHV 160846 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 346 AM CDT Fri May 16 2025 ...New SHORT TERM, LONG TERM... .SHORT TERM... (Friday through Saturday) Issued at 323 AM CDT Fri May 16 2025 Main story in the short-term portion of the forecast revolves around the threat for strong to severe thunderstorms. Radar imagery is showing some thunderstorms ongoing across Arkansas early this morning with some light rain showers showing up across our far northern zones. Nothing to be too concerned about right now, but something to keep our eye on for sure. Our eyes will mainly be hyper focused on the threat of severe thunderstorms this afternoon. Very moist air will be in place across our region today with dewpoints in the lower to mid 70s. Storms will have a hard time developing through the early afternoon hours with some decent capping in place. However, as we move later into the afternoon and early evening hours this cap should begin to break as a mid-level jet moves eastward. As a result, thunderstorms will begin to develop across northeast Texas and southwest Oklahoma. Short range guidance is hit or miss on the exact location of the worst of the storms and how they continue into the evening. However, any storms that do develop should be capable of producing large hail and damaging winds with some very large hail in some of the more intense supercell structures. Because of this, we have a Slight Risk for severe thunderstorms painted across much of the area. Thunderstorms should diminish some heading into the overnight hours giving us a short break before our next round develops late Saturday afternoon and continues into the evening hours. Right now it looks like storms will develop initially along a dryline across north-central Texas that will congeal into an MCS as it moves east through our area. Typically with these types of systems, the initial threat will be for very large hail with any supercells that develop before it congeals into an MCS and then once this happens the main threat will transition to a wind threat across the area. I think there will be more of a tornado threat across far northeast Texas as storms initially develop as well, but this should diminish some as things start to take on the MCS form. That being said, can't ever rule out a tornado in these parts with any types of thunderstorms that move through. As for temperatures...it is going to be warm, muggy and uncomfortable through Saturday as our bodies try to adjust to the warmth again. /33/ && .LONG TERM... (Saturday Night through Friday) Issued at 323 AM CDT Fri May 16 2025 There remains some threat for strong to severe thunderstorms across the northern half of the forecast area on Sunday. That being said, trends are showing that the worst of the storms will be well to the west of our area, but we do remain in a Marginal Risk from SPC across the northern half for Sunday. Rinse and repeat for Monday and Tuesday, although at this timeframe, confidence becomes less on the strength and location of the thunderstorms, so we will need to continue to monitor the forecast for the potential of severe weather through the middle of the week. Our final system for the week looks to come on Tuesday night into Wednesday morning as a cold front moves through the area. This will bring us some cooler temperatures for the end of the week with highs returning to the 70s and 80s. Enjoy it while you can, it is only a matter of time before the unbearable heat returns. With all these chances of rain, the 7-day QPF amounts will be highest across northeast Texas, southeast Oklahoma and southwest Arkansas where some widespread 2-3 inches will be possible. With all this coming over the span of 4-5 days, there shouldn't be any widespread flooding concerns at this time. /33/ && .AVIATION... (06Z TAFS) Issued at 1201 AM CDT Fri May 16 2025 Starting the TAF period with VFR conditions but that will be temporary with widespread MVFR ceilings expanding northward from SE TX/S LA overnight towards sunrise this morning. Those MVFR ceilings will quickly scatter out and/or become low VFR ceilings with plenty of mid and high clouds above these ascending lower ceilings. Did introduce VCTS to the TYR/TXK terminals only by 17/00z this evening to account for upstream convection perhaps impacting our far western and northwestern terminals towards the tail end of the TAF period. Look for S so SSW winds by mid morning through the late afternoon hours sustained near 10-14kts with gusts upwards of 25kts until they decouple after 17/00z. 13 && .SPOTTER INFORMATION STATEMENT... Issued at 415 AM CDT Thu May 15 2025 Spotter activation may be needed late this afternoon through this evening northwest of the Interstate 30 corridor of extreme Northeast Texas, Southeast Oklahoma, and Southwest Arkansas, should any isolated storms develop. && .PRELIMINARY POINT TEMPS/POPS... SHV 93 75 93 74 / 10 40 30 50 MLU 93 75 93 73 / 10 30 30 40 DEQ 88 64 87 67 / 30 30 30 60 TXK 91 70 91 71 / 30 40 40 60 ELD 92 69 91 70 / 20 50 30 60 TYR 92 72 90 72 / 20 40 40 40 GGG 92 72 91 72 / 10 40 30 50 LFK 93 74 94 73 / 10 10 10 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ SHORT TERM...33 LONG TERM....33 AVIATION...13 ####018011193#### FXUS63 KSGF 160847 AFDSGF Area Forecast Discussion National Weather Service Springfield MO 347 AM CDT Fri May 16 2025 .KEY MESSAGES... - There is a Moderate Level (4 of 5) Risk for severe weather today, mainly along and east of Highway 65 and before sunset. Very large hail to the size of softballs, damaging winds up to 80 mph, and tornadoes will be possible. - 40-60% chance for showers and thunderstorms Saturday night into Sunday morning. A Marginal Level (1 of 5) Risk exists for a few thunderstorms may become capable of producing wind gusts up to 60 mph and hail up to the size of quarters. - The unsettled weather pattern will continue across the area early next week. This includes the potential for strong to severe thunderstorms in addition to localized heavy rainfall and flooding. Uncertainty remains in the exact details. && .SHORT TERM /THROUGH SATURDAY/... Issued at 345 AM CDT Fri May 16 2025 Current water vapor imagery depicts a very potent upper-level low sitting over the northern Plains states, with a solid 100-110 kt jet core stretched from the Four Corners Region, across the Central Plains, and into the Great Lakes region. A shortwave is noted within this flow across the OK/TX panhandles. Associated with this feature, a surface low is developing and will be our main weather-maker for today. Meanwhile, surface obs depict a cold front slowly clearing across southeast Missouri. Mid-60s dewpoints ahead of the front in Oregon/Shannon Counties is allowing for 500-1000 J/kg of MUCAPE. Radar imagery and IR satellite show developing showers along this frontal boundary. With 60-70 kts of effective bulk shear within this region, a strong thunderstorm or two could brush portions of Oregon County going through this morning. Otherwise, temperatures across our area are dropping to the middle 50s behind the cold front. Moderate (4 of 5) Risk for severe weather today: The aforementioned shortwave and associated surface low over the panhandles will translate into our western CWA this morning. Associated mass response will increase wind speeds to 15-20 mph with gusts up to 30 mph at times. This will quickly advect middle to upper 60 dewpoints and middle 80s temperatures up into our region. This, along with cooler temperatures aloft, will greatly destabilize the atmosphere with the HREF mean at 3000-4000 J/kg of MLCAPE beneath 60-70 kts of deep layer shear-- a volatile environment for sure. As the cold front plows through this air mass, scattered severe thunderstorms are expected to develop. Below are some when, where, what, and uncertainty details. Timing: Two main timeframes are noted. First, between 10 AM and 3 PM along the cold front just as unstable air gets advected in front. If storms develop during this time period, they would progress west to east quickly, outpacing the front. Then, a second window of redevelopment along the front is possible between 3-6 PM. Location: The first timeframe (10 AM - 3 PM) of development appears to be somewhere between the I-49 and Highway 65 corridors when CAMs first start dissolving the cap ahead of the cold front. These storms would move west to east through midday and clear the eastern Ozarks after 3 PM. The second timeframe (3-6 PM) would again be along the front during peak heating. During this timeframe, the front should be across the eastern Ozarks. All storms should be out of the area by 7 PM. Hazards: The main hazard is very large hail up to the size of softballs. Secondary hazards are very strong wind gusts up to 80 mph, and a few tornadoes. CAM soundings fully support very large hail. In addition to the very strong instability and shear, soundings depict 7-8 C/km mid-level lapse rates, >40000 ft ELs and strong ventilation at that level, and modest storm relative inflow and sub-hail growth zone CAPE. This all leads to a large hail parameter of 20-30 which based on research supports hail greater than 3.5 inches. Indeed, SPC's experimental outlook places the eastern Ozarks in a "double hatching" which signifies higher confidence in the occurrence of very large hail. The strong instability and kinematics will also support strong RFDs and/or bowing segments with wind gusts up to 80 mph. There is a tornado threat as low- level shear approaches 20-25 kts with LCL heights below 500m. However, as the day goes on, hodographs become more straight with southwesterly surface winds and 0-1 km SRH values of 100-150 m2/s2. This is certainly sufficient for tornadoes, but the threat is a bit lower than hail. Uncertainty: Hi-res guidance has been a tad bearish in the coverage of storms, with some runs of the HRRR keeping most of our area dry for the entire period. This seems a tad odd given the modeled uncapped environment, decent forcing from convergence along the cold front, and no real indication of subsidence aloft. Therefore, expectations is for at least scattered storm development during the time periods mentioned above. Indeed, other HREF members do have storm development, especially across the eastern Ozarks in the afternoon. The most bullish member is the NAM with storms developing along I-49. Though forecast soundings from this member depict a stout cap that others do not depict. Therefore, there's still some uncertainty in exact extent of coverage, but expectation is still for scattered storms. And when storms go, it will not take much for them to become severe, perhaps significantly severe. Negative vorticity advection behind the clearing shortwave and sinking air within the cooler air mass will keep us dry tonight into Saturday. Lows tonight will be in the lower to middle 50s. Highs Saturday will be in the middle to upper 70s (around 80 near the southern border). && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 345 AM CDT Fri May 16 2025 Marginal (1 of 5) Risk for severe weather Saturday night: Another shortwave will start translating eastward into the TX/OK panhandle region Saturday evening. This will begin lifting the trailing surface cold front back north as an effective warm front, keeping low temperatures in the upper 50s to lower 60s Saturday night. Thus, relatively strong 850 mb warm air advection above the surface front could trigger some showers and thunderstorms Saturday night into Sunday morning. RAP forecast soundings during this time period show 500-1000 J/kg MUCAPE, largely within the hail growth zone. Effective bulk shear within this profile looks to be in the 35-45 kt range. Thus, some marginally strong to severe storms would be possible with hail up to quarter size being the main hazard. However, inverted-V soundings above the developing nocturnal inversion could allow for wind gusts up to 60 mph as well. Additional chances for severe weather and heavy rain: Daily chances for severe weather and heavy rain continue through the weekend and early next week as ensembles depict the broader synoptic pattern to retain persistent southwesterly flow with embedded shortwaves traversing within the jet. With this pattern, a rather sharp dryline will be in place across central KS/OK/TX Sunday and Monday. The surface warm front is progged to be placed in a west-east fashion across north KS/MO. This will allow for a broad moist and very unstable region east of the dryline and south of the warm front, including our area. The NBM mean has 2000-4000 J/kg across our area. The GEFS even suggests values up to 5000-6000 J/kg. Global model ensembles also place 35-45 kts of deep layer shear over this airmass. This is sparking 0.7-0.9 Extreme Forecast Index values for CAPE-Shear combo (with some shifting of the tail suggesting the chance for a more volatile environment). NSSL, NCAR, and CSU machine learning models are all picking up on this environment and placing enhanced severe probabilities in our area, especially west of Highway 65. For example, the NSSL GEFS machine learning model gives a 30-45% chance of areas west of Highway 65 to see some sort of severe weather watch Sunday and Monday. Early MPAS/RRFS CAM signals point to storms firing along the dryline in Kansas and Oklahoma during the afternoons of Sunday and Monday. These then progress eastward, evolving into an MCS over time, which fits the general evolution of May severe storms. Therefore, the main severe risk for us will be Sunday and Monday night and come from the evolution of these storms as they progress west to east. If an MCS becomes the main mode, wind and tornadoes would be the main hazards. If confluence bands happen to develop out ahead of the dryline, there is a scenario where supercells could develop in our CWA, allowing for all hazards to be present. Tuesday, more of a longwave trough is forecast to kick through, finally getting rid of the unstable airmass. Since a cold front will be associated with this system moving through, a greater (or at least more widespread) severe threat for our CWA appears possible Tuesday. There are still some subtle differences in timing and trough shape between the global ensembles, so details will need to be worked out. However, strong instability and kinematics associated with the system points to a severe threat Tuesday as well. It is also worth noting that with any thunderstorm complex Sunday and Monday, with southwesterly flow, any line that orients southwest to northeast could bring the potential for a slowing system and training heavy thunderstorms. With ESATs suggesting >99th percentile moisture in place, any training thunderstorms could lead to flash flooding. The best chance would be Sunday night and Monday night with any slowing thunderstorm complex. Cooler late next week: With the main system finally moving through, temperatures will cool down into the middle to upper 60s next Wednesday and Thursday. A signal for another storm system exists for next Friday as highs warm into the lower 70s, however, model certainty is low at this time. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 200 AM CDT Fri May 16 2025 Medium-high confidence in VFR conditions prevailing through the entire TAF period. Main concern is for southwesterly to westerly winds between 14-00Z along and behind a fropa. Sustained winds of 15-20 kts and gusts up to 25-30 kts at times. There is a low (<30%) chance for an isolated thunderstorm to develop within the vicinity of a TAF site between 14-18Z. If a storm were to impact a TAF site, very large hail, frequent lightning, strong downbursts, and reduced visibilities from heavy rainfall would all be possible hazards. && .SGF WATCHES/WARNINGS/ADVISORIES... KS...None. MO...None. && $$ SHORT TERM...Price LONG TERM...Price AVIATION...Price