FXUS62 KRAH 180523 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 120 AM EDT Mon May 18 2026 .WHAT HAS CHANGED... * No significant changes. && .KEY MESSAGES... As of 120 AM Monday... 1) Hot and mainly dry through Wednesday. 2) Increasingly unsettled starting Wed night, with highest rain chances expected to be Thu. Low confidence in high temps Thu and Fri. && .DISCUSSION... As of 120 AM Monday... KEY MESSAGE 1... Hot and mainly dry through Wednesday. Still anticipate multiple days of anomalously hot temperatures. Mid- upper level troughing from Saskatchewan/Manitoba down through the N Plains and Rockies will ensure maintenance of strong ridging over and off the Southeast coast through midweek (although this is complicated by a weak but persistent upper low NW of the Bahamas). The LREF continues to show 500 mb heights over NC reaching the 95th- 99th percentile into Wed. Meanwhile, at the surface, Bermuda high pressure continues to extend westward across NC, keeping low level moisture return limited, with deep mixing each day and minimal cloudiness overall. Multi-model low level thicknesses continue to be around 20 m above normal today through Wed, supporting highs from around 90 to the mid 90s given high insolation. Early-day dewpoints in the 60s are likely to mix out and drop into the 50s during the hottest parts of each day, which should keep heat index values from rising into the triple digits. However, this kind of early-season heat can still be unexpectedly dangerous, as people have not yet become acclimated to the hot weather. The daily experimental Heat Risk is expected to peak at Moderate (level 2 of 4) today through Wed, indicating that this kind of heat is quite unusual for this time of year and has historically led to high levels of heat illness, with sensitive individuals and those without adequate cooling particularly vulnerable. And with just a modest breeze and lots of sunshine each day, the WBGT index will also be elevated, so spending time in the shade is encouraged, especially for those working or exercising outdoors. KEY MESSAGE 2... Increasingly unsettled starting Wed night, with highest rain chances expected to be Thu. Low confidence in high temps Thu and Fri. Confidence is high that the southern Canada portion of the mid-upper level trough will shift E over Ontario/Quebec and far E Canada Tue through Thu, allowing a cool surface high to spread across the N Great Lakes and St Lawrence Valley, reinforced by confluent flow aloft over the Northeast, which will help push a backdoor front southward into NC Thu. Precisely when this front arrives will drive both Thu high temps and precip chances. The deterministic GFS and ECMWF have trended toward a slightly slower arrival in their last few runs and are a bit slower than the latest LREF mean, indicating that at least our southern areas will likely stay in the warm sector longer, suggesting highs in the low 90s. Northern areas, especially near the VA border, have the largest temp spread among deterministic models and ensemble members, including the NBM's 15-20 degree 25th- 75th percentile spread for highs at Roxboro. Expect highs in the lower to upper 80s N of Hwy 64, but confidence in temps at any particular location is low. By Fri morning, the front is expected to settle across the S Piedmont and S Sandhills through the S/E Coastal Plain as the surface high center shifts ESE over the Northeast states, setting up a short-lived cold-air damming scenario, with stability reinforced by overrunning flow (albeit shallow) atop the wedging ridge. Highs NW of Hwy 1 are likely to be no warmer than the 70s, with some upper 60s for highs expected in the far N and NW Piedmont, while the far SE CWA should reach the low 80s. The greatest uncertainty with Fri high temps, however, will be through the heart of the CWA, including in the Triangle, as temps will depend on where the wedge boundary sets up. This high to our N and NE will be transitory, and as such we should see this wedge dissolve by Sat, leading to rebounding temps back to near to above normal values by the weekend as mid-upper ridging builds back over the Carolinas. Regarding pops, the highest rain chances look to be with and just behind the front, peaking Thu afternoon and night with an uptick in moist upglide, especially over the NW CWA within the deepest overrunning flow. Overall, the chance for showers and isolated to scattered storms will be above climatology Thu through the upcoming weekend, as our 925-850 mb flow strengthens from the SE and S, drawing in both Gulf and Atlantic moisture while weak perturbations ride within the SW flow from N Mexico and the TX Gulf Coast into the Carolinas. Coverage should be highest overall from the NW Piedmont to our W, where PW is expected to be highest within low level confluent flow and beneath weak DPVA and minor jet streaks to force ascent. Isolated pockets of heavy rain can't be ruled out, although generally speaking, these high pops are good news for our drought- ravaged region. && .AVIATION /05Z MONDAY THROUGH FRIDAY/... As of 1250 AM Monday... TAF period: With high pressure offshore, the forecast should be quiet with VFR almost a certainty. The one exception will be around sunrise at FAY, where yesterday there was an MVFR ceiling for about 90 minutes, and vertical soundings show this should be a possibility again this morning. Otherwise, conditions should be mostly clear with southwest wind. Outlook: MVFR ceilings will be possible briefly at FAY and RWI Tuesday and Wednesday mornings, otherwise dry VFR conditions are forecast through Wednesday. The chance of rain will increase from northwest to southeast Wednesday night, with restrictions and showers expected Thursday and Friday. && .CLIMATE... Record High Temperatures: May 18: KGSO: 95/1911 KRDU: 95/1906 KFAY: 96/1911 May 19: KGSO: 96/1911 KRDU: 95/1962 KFAY: 96/2022 May 20: KGSO: 95/1917 KRDU: 96/2022 KFAY: 99/2022 Record High Minimum Temperatures: May 18: KGSO: 70/2015 KRDU: 72/1896 KFAY: 71/2018 May 19: KGSO: 68/2018 KRDU: 70/2022 May 20: KGSO: 68/2022 KRDU: 69/2019 KFAY: 71/2022 May 21: KGSO: 67/2022 KRDU: 71/1898 KFAY: 71/2025 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Hartfield AVIATION...Green