####018008179#### FXUS62 KFFC 170727 AFDFFC Area Forecast Discussion National Weather Service Peachtree City GA 327 AM EDT Sat May 17 2025 ...Morning Area Forecast Discussion... .SHORT TERM... (Today through Sunday) Issued at 322 AM EDT Sat May 17 2025 Key Messages: - A line of thunderstorms will advance through far north Georgia during the early morning hours ahead of a cold front. A few storms within this line could become severe. - Scattered thunderstorms are expected this afternoon and evening in portions of central Georgia in a warm/humid environment and along the stalled frontal boundary. - Showers and thunderstorms return on Sunday, with isolated strong to severe storms possible. The possibility of an MCS entering the area will need to be monitored. As the morning begins, a line of thunderstorms is advancing southward through middle Tennessee ahead of a cold front. The progression of the line has slowed a little bit compared to the previous forecast, though a few isolated storms have begun to enter the far northwestern corner of the forecast area. By the time storm arrive in the far northern tier by around 4 AM EDT, SBCAPE and MUCAPE values around 1000-1500 J/kg will still be present. Furthermore, 0-1 km shear ahead of the cold front will range from 30- 35 kts and 0-1 km storm relative helicity values will range from 150 to as high as 250 m2/s2. Considering these factors, isolated storms ahead of the line may become supercellular, capable of producing a brief tornado and strong wind gusts. It will also be likely to see a few stronger storms embedded within the greater line, with bowing segments capable of producing damaging wind gusts and brief tornadoes, as well. By sunrise, the line is anticipated to be roughly parallel to the north ATL metro. At this point, the cold front will become more elongated from west to east, at which point it will begin to stall and storms will steadily weaken. Showers and thunderstorms will work their way southward through the metro area during the early and mid morning hours. By the early afternoon, the front is expected to stall in an area between the metro area and a line from Columbus to Macon. The passage of the cold front will only have a minor impact on high temperatures this afternoon. Highs in north Georgia are forecast to rise into the mid to upper 80s in all but the far northeastern mountains (which will be slightly cooler). To the south of the front, highs in central Georgia will rise into the low to mid 90s once again today. These highs will range from about 5-9 degrees above daily averages. The frontal boundary is expected to provide a focus for convective development during the afternoon and evening hours. While may hi-res solutions keep convective development sparse in the vicinity of the front, this very well may be underdone given strong destabilization to the south of the front. SBCAPE values between 2000-3000 J/kg will still allow for the development of isolated to scattered thunderstorms in the afternoon hours. With deep layer bulk shear of 45-55 kts, some of the storms that develop will have the potential to become supercellular and produce damaging wind gusts and hail. Because of this, the SPC has maintained a Day 1 Marginal Risk (level 1 of 5) for severe weather. Precipitation is expected to gradually come to an end in the hours following sunset with the loss of diurnal heating. The frontal boundary will still be in place across central Georgia on Sunday morning. At this time, a 500 mb ridge will advance across the Great Plains. A quickly moving shortwave will move across the Southeast on the eastern side of the ridge pattern, where it will then overrun the front on Sunday morning into the afternoon. Chances for showers and thunderstorms will increase accordingly, with scattered showers and a few isolated thunderstorms during the morning and more numerous showers and thunderstorms in the afternoon. The greatest chances for showers and thunderstorms are forecast to be in the far west/northwest portions of the forecast area where isentropic lift will be most aligned with the stalled surface boundary. Forcing along the front will be weak at this point, but SBCAPE values ranging from around 1000 J/kg in far north Georgia to 2000 J/kg in south-central Georgia and a moderately sheared environment will allow for isolated thunderstorms to become strong to severe in the afternoon and capable of producing strong wind gusts. Another variable that will warrant monitoring as we get closer in time is the formation and evolution of any MCSs that develop upstream overnight into Sunday morning. An MCS entering central Georgia during the afternoon could find itself in a highly favorable environment for downstream growth and propagation, which would lead to a more widespread wind threat. Ample uncertainty remains in this scenario at this time. King && .LONG TERM... (Sunday night through Friday) Issued at 322 AM EDT Sat May 17 2025 Key Messages: - Warm to hot. Highs in the upper 80s and low 90s, with a potential cool down around mid-week. - Small chance of severe weather Sunday afternoon. Main hazard is damaging winds. There is a marginal (level 1 of 5) risk of severe. Risk tappers off into the evening. Thunderstorms may continue into the evening hours on Sunday with whatever instability may remain through central Georgia. Entering the overnight hours, the subtropical ridge rebounds northward as the upper level shortwave moves out of the area. Thunderstorm activity should shift northward through this timeframe, though overall activity will be significantly reduced. With the terminus of the subtropical thermal ridge across north Georgia, diurnal thunderstorms activity can be expected each afternoon Mon and Tuesday ahead of our next system. As we get into the Wednesday timeframe, a more robust upper level trough will descend into the area bringing a cold front and more widespread showers and thunderstorms. Currently limited to no severe weather is anticipated with this due to the strength of the thermal ridge, however will definitely keep an eye on it as we get into the near term. Temperatures behind the front will be cool for this time of year with highs in the 70s and (hopefully) drier conditions. SM && .AVIATION... (06Z TAFS) Issued at 131 AM EDT Sat May 17 2025 Broken upper level cloud deck is in place across the majority of the forecast area as the period begins. A line of SHRA/TSRA is approaching far north Georgia, as it advances southward towards the metro area, lower clouds between 025-040 are anticipated to develop. A TEMPO for TSRA is in place from 12-15Z to account for the line of storms at ATL, with storms expected to clear out by 15Z. MVFR ceilings and visibility restrictions will be possible immediately behind the line from 15-17Z at ATL, with conditions steadily improving thereafter. Winds will be SW to W through the period between 5-10 kts, with occasional gusts up to 20 kts in the afternoon. //ATL Confidence...06Z Update... High confidence on all elements. King && .PRELIMINARY POINT TEMPS/POPS... Athens 86 66 85 65 / 50 0 30 10 Atlanta 87 68 85 68 / 60 10 50 10 Blairsville 81 59 79 59 / 50 10 30 20 Cartersville 87 64 85 65 / 60 10 50 20 Columbus 89 69 90 68 / 40 10 40 0 Gainesville 85 66 84 66 / 50 0 40 10 Macon 90 68 90 68 / 50 10 40 0 Rome 88 64 85 65 / 50 10 50 20 Peachtree City 87 66 87 66 / 60 10 50 10 Vidalia 92 72 91 70 / 30 20 30 10 && .FFC WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...King LONG TERM....SM AVIATION...King ####018007317#### FXUS64 KCRP 170730 AFDCRP Area Forecast Discussion National Weather Service Corpus Christi TX 230 AM CDT Sat May 17 2025 ...New SHORT TERM, LONG TERM, MARINE, FIRE WEATHER... .SHORT TERM... (Today through Sunday) Issued at 210 AM CDT Sat May 17 2025 Key Messages: - Major to extreme risk of heat-related impacts over inland Coastal Plains and Brush Country, moderate risk east - Moderate risk of rip currents this weekend Unseasonably warm temperatures, especially out west, will continue this weekend with highs peaking around 105 over the Rio Grande Plains and lows tonight in the mid to upper 70s. HREF/REFS probability of apparent temperatures reaching 110 or greater (Heat Advisory criteria) is less today than yesterday, with only a few splotches across the Brush Country and southern Coastal Plains containing a less than 20% chance. This guidance did well yesterday and therefore will continue to hold off on a Heat Advisory. However, there still remains a moderate risk of heat-related impacts over the Coastal Plains, and a major to extreme risk over the Brush Country as feels-like temperatures range from 100-110. Please continue to practice heat safety, limit outdoor exposure, take frequent breaks, and drink plenty of water. A mid-level shortwave stretching from North Texas to eastern Mexico combined with moisture pooling near the 99th percentile in front of a dryline provides an opportunity for showers and thunderstorms to develop west of the Rio Grande this afternoon. We'll have to closely monitor the progression of the shortwave and dryline but if any convection does linger into South Texas (20-30% chance) it would most likely be between 6pm - midnight tonight over the Brush Country. There is a greater chance where conditions are more favorable north into the San Antonio and Hill Country area. Storms originating in Mexico can struggle to maintain intensity into the Rio Grande Plains as we get further into the night and lose instability. && .LONG TERM... (Sunday night through next Friday) Issued at 210 AM CDT Sat May 17 2025 Key Messages: - Heat Risk remaining at Major/Extreme Monday, but decreasing from Tuesday. - Low chances (10-20%) for rainfall Wednesday along the Rio Grande. Out ahead of the upper-level trough that will move from the Intermountain West and into the Central Plains, a surface low will form over southern Colorado and slowly move eastward through the day. A front will extend south from this surface low through the Texas Panhandle and into the Edwards Plateau. Out ahead of this front, southerly winds will continue to feed Gulf-rich moisture. Temperatures Monday afternoon will continue to climb into the 100s across the relatively less-moist airmass over the Rio Grande Plains and into the 90s along the Coastal Bend and into the Victoria Crossroads. Heat indices Monday afternoon will span from the 110- 115F range across the Brush County and in the low 100s elsewhere, leading to a Major/Extreme Heat Risk. The aforementioned front will move through South Texas on Tuesday, with winds switching from a southeasterly direction to more easterly. PoPs do increase with the frontal passage, but unfortunately ensemble models continue to place much of South Texas in 10-15% PoPs. By Wednesday, a coastal trough will remain over northern Mexico and along the Mexican Gulf coastline. This zone of convergence and higher PWATs (1.7"-1.8") in the RGV will allow for showers to form along the Rio Grande and into the northern Mexican states. Webb County will be in the northern periphery of this area, thus giving them the best chance for precipitation 15-20% on Wednesday. That said, the NBM is still showing medium chances (30- 50% chance) of rainfall in excess of one hundredth for Laredo. Surface winds will continue to remain easterly through Thursday afternoon, allowing the Heat Risk to fall to Minor/Moderate. Thursday night, winds will switch to be more southeasterly, increasing heat indices back into the low 100s by Saturday. && .AVIATION... (06Z TAFS) Issued at 1044 PM CDT Fri May 16 2025 Aviation conditions will continue to deteriorate through the night to a mixture of MVFR/IFR levels due to low ceilings and patchy fog development. These poor aviation conditions will likely persist through the mid to late morning hours, before lifting back to VFR in the afternoon. Winds will become light overnight, but breezy conditions will return to the forecast by Saturday afternoon with gusts to 20-25 knots. Winds are forecast to the decouple by the evening hours on Saturday. && .MARINE... Issued at 210 AM CDT Sat May 17 2025 Moderate (BF 4) south to southeasterly winds will continue through tonight before increasing slightly to a moderate to fresh breeze (BF 4-5) Sunday with seas 4 to 5 feet. Moderate to fresh (BF 4-5) southeasterly winds will increase seas to 5-6 ft on Monday. Closer to the barrier islands, winds will gust up to BF 6 at times, resulting in choppy conditions over the inland bays. By Tuesday, winds will shift to be more easterly at gentle to moderate strength (BF 3-4) with seas decreasing to 3-4 ft by Thursday. Thursday night, winds will switch to be more onshore and increasing to moderate strength (BF 4). && .FIRE WEATHER... Issued at 210 AM CDT Sat May 17 2025 Minimum relative humidity this weekend will remain around 30% or greater, negating elevated fire weather conditions across South Texas. Surface southeasterly winds will only range from 10-20 mph as well. There is a low (20-30%) chance of showers and thunderstorms moving into the Brush Country from Mexico tonight. Energy Release Component is forecast to increase to above the 97th percentile immediately along the Rio Grande, while generally remaining above the 80th percentile across the Brush Country. Min relative humidity on Monday will bottom out to 15-20% across the Rio Grande Plains, and down to 10-20% on Tuesday with the frontal passage, while remaining in the 20-40% range across the Brush Country. Given this, an elevated fire risk will be contained to Webb County through Tuesday. From Wednesday, drier easterly winds will reduce Min RH's across the northern Brush Country and Victoria Crossroads to 20-30% through Thursday. 20-ft winds are looking to be weak across much of South Texas, limiting the fire risk through next weekend. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 91 78 90 78 / 0 10 0 0 Victoria 93 76 92 76 / 0 0 0 0 Laredo 104 78 104 80 / 0 30 0 0 Alice 99 76 97 77 / 0 30 0 0 Rockport 88 78 87 79 / 0 0 0 0 Cotulla 105 77 105 78 / 10 30 0 0 Kingsville 95 77 94 77 / 0 10 0 0 Navy Corpus 86 79 86 80 / 0 0 0 0 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...EMF/94 LONG TERM....AE/82 AVIATION...ANM/88