####018008293#### FXUS62 KRAH 201042 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 616 AM EDT Tue May 20 2025 .SYNOPSIS... A backdoor cold front will stall over NC this morning then lift back to the north tonight as a warm front. An upper trough and surface cold front will move across central NC Wednesday, and will be followed by a cooler and less humid air mass that will build in gradually from the northwest Thursday through the weekend. && .NEAR TERM /TODAY THROUGH TONIGHT/... As of 240 AM Tuesday... As of 06Z, the sfc features included a lingering stationary boundary to our south over SC and a backdoor front near the VA/NC border which is denoted by a north wind shift and lower dwpts north of it. This backdoor front is slowly drifting south. Aloft, a broad trough is located over the Plains while a shortwave ridge downstream of it is crossing the Appalachians attm. The backdoor front is progged to continue drifting south across the state this morning into the afternoon hours, and with a slightly cooler airmass behind it, today's highs will range from the upper 70s north near the VA border to the mid 80s south near the SC border. High pressure north of the backdoor front will briefly build into central NC from the north this morning but will be short-lived as the progressive upper pattern shifts east, and so too will the high pressure. Once the high moves offshore, winds will gradually become SE this afternoon then more southerly this evening and tonight. Thus, look for the boundary to lift back to the north this evening and tonight as a warm front out ahead of the approaching trough. The latest HREF members continue to show isold to scattered showers/ tstms developing along and just south of this warm front during the evening hours which will then lift toward the NNE as the warm front advances northward. Then later overnight as the aforementioned upper trough approaches, a band of prefrontal convection is depicted by many of the HREF members moving across central NC generally in the 06-12Z timeframe. Forecast soundings do show >=500J/kg CAPE above the typical nighttime low level inversion. That coupled with >40kt bulk shear suggest the potential for isold severe storms tonight with either batch of showers/tstms, but esp later overnight with the prefrontal band. As noted in SWODY1, the primary hazards would be wind and hail, but there is a 2% area for the tornado threat mainly across the western half of central NC. Lows tonight in the 60s. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... As of 315 AM Tuesday... * Two rounds of showers and storms, early Wed morning and again Wed afternoon/evening, will bring a conditional risk for strong to severe thunderstorms. An area of convection, forced by embedded MCVs leaking across the NC mountains early Wed morning, will likely be ongoing somewhere over the county warning area and is expected to continue towards the coast through daybreak. All hazards will be possible, with perhaps a slight edge towards brief tornadoes with this area of convection, but generally a weakening trend is expected. A primary surface low is expected to be positioned over the OH Valley Wed morning with secondary cyclogenesis beginning along a warm front draped near the NC/VA border. The biggest uncertainty is when secondary cyclogenesis develops along the warm front and how quickly it moves towards the coast. This uncertainty is pretty typical with cyclogenesis based solely on jet dynamics. There has been a noticeable slowing and westward trend among the GEFS surface low locations Wed afternoon as well as hi-res guidance being split into a faster/eastern or slower/western solutions. This will have a significant impact on the available low-lvl moisture and resultant MLCAPE that develops during the afternoon hours. This will likely be the biggest discriminator in the character of convection Wed afternoon (or any at all) as a significant amount of dry air aloft will suppress deep convection, especially if instability is on the weaker side (< 1000 J/kg). If deep convection were to develop, point soundings suggest mostly unidirectional flow leading to long-straight hodographs which would favor initially a risk for large hail but a transition to mainly a wind threat as dry air aloft and modest low-level lapse rates would favor cool downdrafts and expanding cold pools. This is far from a certainty and is highly conditional on the weak surface low location and all the ingredients coming together during the afternoon hours. As such, if the slower/western surface low and greater instability solution continues to trend more likely, an upgrade to a slight risk would be needed. High temps will range from upper 70s along and north of the warm front to low 90s across the Sandhills and southern Coastal Plain. &&. .LONG TERM /THURSDAY THROUGH MONDAY/... As of 315 AM Tuesday... * A reinforcing cold frontal passage late Thursday will bring cooler and dry conditions through Saturday. * Precipitation chances increase Sun into Mon, but forecast confidence in timing is low. The arrival of a Canadian maritime airmass has trended slower as surface flow remains generally out of the west as the coastal low deepens and lifts towards the Northeast coast. This has resulted in warmer afternoon temperatures and low chances for showers/storms to remain in the forecast for Thursday. Ahead of the front, H5 temperatures around -20C (well below the 10th percentile of GSO climatology) will contribute to steep mid-level lapse rates. Even though dew points will be in the low 50s, this should still result in around 500 J/kg of MLCAPE during the afternoon and support isolated to scattered showers as 40 to 60m height falls spread across the region. NWP guidance suggest rapid deepening of the coastal low and broad high pressure settling into the Mid- Mississippi Valley will finally turn the surface winds out of the northwest and usher in the Canadian maritime airmass into the area Thursday evening with CAA continuing overnight. Cooler and drier weather is expected to continue through at least Saturday when highs are forecast to be 5 to 10 degrees below normal. Forecast confidence greatly decreases Sun and into early next week with considerable timing differences on the strength and departure of the broad troughing over the eastern CONUS. Using cluster analysis, the most-likely solution (consisting of 29 out of 100 members) keeps the broad trough over the eastern CONUS and generally northerly flow into the southern Mid-Atlantic, potentially favoring cooler weather continuing for Memorial Day. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... As of 616 AM Tuesday... Through 12Z Wednesday: VFR conditions with ample mid and high clouds moving across the Carolinas attm will continue to be the case through at least the daytime today. A warm front will approach and lift NEWD across central NC late today and tonight. Flt conditions are expected to fall to IFR or worse after 06Z tonight with fog and low cigs with dwpts surging in the wake of the warm fropa. In addition, a pre-frontal band of showers and possibly and isold tstms may move in during the late overnight hours. Will include this activity as well. Winds will be light from the NE through about 18Z before becoming SE 10kt or less. Outlook: Showers and tstms will increase in coverage after 06Z Wednesday as a prefrontal trough moves across the area. Look for sub-VFR conditions as this activity moves across the area. Isolated showers/tstms and sub-VFR conditions will be possible again during the daytime Wednesday. VFR conditions will then return for the latter portion of the week. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...np NEAR TERM...np SHORT TERM...Swiggett LONG TERM...Swiggett AVIATION...np ####018007021#### FXUS62 KILM 201043 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 643 AM EDT Tue May 20 2025 .SYNOPSIS... A warm front will lift north across the area this evening followed by a cold front Wednesday, with scattered storms this afternoon through midday Wednesday. Slightly cooler and less humid air is slated for the late week period and into the weekend. Unsettled weather may return Sunday into next week. && .NEAR TERM /THROUGH TONIGHT/... Shortwave ridge at 5h slips east today, helping bump a stalled front north, into the forecast area this afternoon. Big jump in low level moisture with the boundary, so unlike the last few days there will be an abundance of deep moisture. Boundary layer humidity increases by some 20-30% compared to Mon afternoon leading to a significant increase in SBCAPE today. Much of the forecast area will see SBCAPE in the neighborhood of 1500-2000 J/kg with portions of SC seeing values over 2000 J/kg. Mid-level lapse rates increase a bit in the afternoon as heights fall slightly. There is a noticeable low level moisture gradient and partial thickness packing moving north into South Carolina in afternoon. This is likely where the first storms will develop. These gradients lift north from late afternoon into the evening, steered inland by the afternoon sea breeze. Best storm coverage will be across most of the SC counties (away from the immediate coast) and inland NC counties. The more stable marine layer will limit convection across coastal NC counties. The 270-280 storm motion may lead to some convection moving across coastal NC in the evening, although it would be in a weakening state. Area has been highlighted in a marginal risk by SPC and an isolated strong/severe storm cannot be ruled out, but with limited storm coverage and environmental parameters on the lower end of severe thresholds the overall threat appears to rather limited. Coverage will be somewhat held back by the lack of strong forcing. The front itself is weak and the only PVA is shifted north of the area by midday as the ridge axis shifts east. Diurnal heating and convergence where the sea breeze meets the front will be the main forcing mechanism for the initial storms. Other storms will likely develop off the outflow from the first round, but coverage will be scattered at best. Temperatures will range from near normal along the coast, mainly due to the sea breeze, to slightly above normal inland. Front lifts north of the area this evening leaving the region in the warm sector. Cannot rule out an isolated shower closer to the front overnight, although chances are slim. The lack of forcing and surface based instability suggests it will be a dry, but very warm night. Lows could be 10 or more degrees above normal. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... A secondary surface low will be moving across NC on Wednesday, with attending cold front approaching our area during the day. Primary window for scattered storms will be Wednesday morning through midday before subsidence from NVA and abundant dry air aloft (RH ~5% above 700mb) moves in from the west in the afternoon. Clearing skies Wednesday afternoon will allow temps to reach into low 90s, with MEX guidance hinting at a chance of 95F highs, as well as deep mixing leading to breezy wind gusts. Cold front will move across late Wednesday with dropping dewpoints Wednesday night and lows in the low 60s. Relatively quiet day Thursday with highs in the mid 80s and another day of breezy conditions. A second cold front looks to make its way through the Carolinas late on Thursday, with cooler and drier air behind it. Have lowered pops a little due to lingering dry air aloft, but have maintained slight chance for northern and coastal areas late Thursday due to front and PVA across NC. Low temps Thursday night will drop below normal into the mid to upper 50s. && .LONG TERM /FRIDAY THROUGH MONDAY/... Quiet with below normal temps forecasted for Friday and Saturday as high pressure briefly builds in from the north. Unsettled weather may return Sunday and Monday as increased moisture is advected over a mid-level ridge to the south and guidance shows a series of surface lows moving across the Southeast. Still a wide range of solutions shown in ensemble guidance so pops are rather limited with only a slight warming trend in the forecast. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... High confidence in VFR through 18Z. Scattered showers and thunderstorms will develop across inland South Carolina this afternoon then expand north into the early evening hours. Best chances will be at FLO and LBT with coverage between 30-40%. Sea breeze will result in east winds and stable marine layer for the coastal terminals. Storm motion will move storms that develop toward the coastal terminals, but the marine layer will limit any possible impact at CRE/ILM/MYR. Isolated showers and thunderstorms will be possible after 06Z as a cold front slowly approaches from the west. Best chances will be along the coast with ILM favored. Extended Outlook...Low confidence in brief IFR/MVFR from storms through midday Wednesday. High confidence in VFR Wednesday night through Saturday. && .MARINE... Through Tonight...Brief, weak northeast surge this morning with front slipping to the south. Sea breeze quickly dominates the wind field with onshore flow developing by early afternoon. The front returns north late in the day with southwest flow developing by midnight and increasing to around 15 kt in the predawn hours of Wed. Seas around 2 ft today build to 2-3 ft tonight once southwest flow sets up. Pretty chaotic mix of waves today with a northeast wind wave developing in the morning before a southerly wind wave takes shape tonight. A southeast swell will be present through the end of tonight. Wednesday through Saturday...Southwest winds prevail Wednesday, with gusts up to 25 kts late afternoon/evening hours, before a cold front moves across the waters late Wednesday. Seas increase to 3-5 ft for Wednesday evening due to strengthened S wind wave mixing with 1-2 ft SE swell. Winds turn briefly offshore Wednesday night before SW flow returns Thursday ahead of a second cold front. West-northwest winds dominate Thursday night through Saturday, with strongest speeds around 15 kts Thursday night behind the front. Seas 3-4 ft Wed night through Thursday night lower to around 2 ft for Friday and Saturday. && .ILM WATCHES/WARNINGS/ADVISORIES... NC...None. SC...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...III SHORT TERM...VAO LONG TERM...VAO AVIATION...III MARINE...III/VAO ####018005047#### FXUS64 KSHV 201043 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 543 AM CDT Tue May 20 2025 ...New UPDATE... .UPDATE... Issued at 540 AM CDT Tue May 20 2025 We have cancelled the Severe Thunderstorm Watch that was in effect till 8:00 AM as severe storms have come to an end or moved out of the watch area. That being said, there is still a boundary that is draped from where the Louisiana/Texas/Arkansas state lines connect southwest to northern Smith county. The HRRR continues to indicate that some additional convection could get going along this boundary this morning, however, should anything develop we are thinking that they should remain sub-severe. Discussion for the rest of the day can be found below on our severe potential for this afternoon. /33/ && .SHORT TERM... (Tuesday through Wednesday) Issued at 237 AM CDT Tue May 20 2025 We are currently tracking a few areas of thunderstorms this morning across portions of northeast Texas, southeast Oklahoma and southwest Arkansas. Latest short range models suggests these storms will continue to push slowly to the east through the rest of the night and even into the morning hours. A Severe Thunderstorm Watch was issued for much of northeast Texas, portions of northern Louisiana, southwest Arkansas, and southeast Oklahoma through 8am. Despite how long these storms can survive through our area, models indicate that we will see some redevelopment along and ahead of a cold front passing through the area by later this afternoon and into the early evening hours across northern and central Louisiana and portions of south central Arkansas. Because of this, there remains a Slight Risk currently painted along and east of a line from Natchitoches Parish in Louisiana northward into Columbia and Nevada counties in southern Arkansas. While all modes of severe weather will be possible, the probabilities are much lower than what we have seen the past couple days. Nonetheless, it is important to remain vigilant with any thunderstorm development today. The good news is that once things finally push east of the area we will move into a more dry and seasonable regime starting on Wednesday. Temperatures will remain in the lower 80s to lower 90s across the area, which is roughly around 5 degrees above normal. /33/ && .LONG TERM... (Wednesday Night through Tuesday) Issued at 237 AM CDT Tue May 20 2025 Dry and somewhat seasonable conditions will remain in place for Thursday and Friday with highs in the lower 80s to lower 90s while Saturday will be slightly warmer as a warm front lifts north through the area. Rain chances return to the area on Friday and Saturday, but only across our far northern zones where the warm front slows down at, and the chances will remain fairly low for our area. More widespread showers and thunderstorms are expected on Sunday and into Sunday night as moisture increases. By Monday morning, a cold front will begin to approach from the northwest, and slowly move through the region into Tuesday. This will bring additional thunderstorm chances to the area on both days, along with some below normal temperatures, talking highs potentially in the mid 70s to mid 80s across the region on Tuesday. Granted there are many days between here and there for things to change some. /33/ && .AVIATION... (06Z TAFS) Issued at 1223 AM CDT Tue May 20 2025 Look for MVFR ceilings to quickly overspread our entire airspace in advance of a convective line of storms that will precede a cold front moving into our region from the I-35 Corridor. Tried to time this convective line through our airspace later this morning and through the afternoon, followed by a return to VFR conditions with a wind shift. Look for reduced VSBYS and stronger wind gusts with any organized strong to severe line of storms that impacts our terminals later this morning and through the day. 13 && .SPOTTER INFORMATION STATEMENT... Issued at 237 AM CDT Tue May 20 2025 Spotter activation will be needed this morning across northeast Texas, far northern Louisiana, southwest Arkansas, and southeast Oklahoma. Additional thunderstorms this afternoon and evening may require additional activation across northern Louisiana and south central Arkansas where a Slight Risk is in place. && .PRELIMINARY POINT TEMPS/POPS... SHV 91 63 91 66 / 30 0 0 0 MLU 91 63 88 65 / 20 10 0 0 DEQ 82 55 86 59 / 30 0 0 0 TXK 87 60 89 63 / 50 0 0 0 ELD 88 57 89 61 / 50 0 0 0 TYR 85 61 88 65 / 30 0 0 0 GGG 87 60 89 64 / 30 0 0 0 LFK 91 62 91 66 / 10 0 0 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ SHORT TERM...33 LONG TERM....33 AVIATION...13