####018009048#### FXUS62 KRAH 160151 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 950 PM EDT Thu May 15 2025 .SYNOPSIS... Upper level disturbances moving atop an upper level ridge building across the SE US will support mainly diurnal showers and storms and unseasonably hot temperatures to end the work week. A series of cold fronts will move through the region over the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 950 PM Thursday... The Severe Thunderstorm Watch has been cancelled for the entire forecast area. Showers and thunderstorms across the eastern portion of the forecast area have fallen apart. However, several runs of the HRRR show the potential for some showers to move into western portions of the forecast area late tonight toward sunrise, and have added some slight chance pops to account for that. In addition, some patchy fog cannot be ruled out considering there has not been a change in airmass and there is plentiful low level moisture. Lows will be in the mid and upper 60s. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 230 PM Thursday... * A conditional risk of severe storms will exist across the nrn half of cntl NC on Fri, based on lower predictability, mesoscale influences from upstream convection across the lwr OH Valley today- tonight. 12Z guidance this morning continues to highlight an uncertain forecast wrt to convection Friday. An upstream, decaying MCS is still forecast by several models (e.g. NamNest, HRRR, NSSL) to cruise across the mountains and foothills early Friday morning. Strong sfc gusts (possibly 35 to 45 kts) associated with it's cold pool still look plausible early to mid Friday morning across the northern Piedmont. This scenario would favor less convective potential later Friday afternoon, as lingering cooler air and cloud debris limit sfc heating across northern areas. Alternatively, the FV3 and ARW CAMs continue to simulate the morning MCS further north into Virginia. This scenario would favor strong heating across all of central NC and the development of strong CAPE by Friday afternoon. Any convection that develops in this environment would favor explosive updrafts and supercells capable of large hail and damaging wind gusts. Given this potential scenario, the SPC has introduced a Marginal Risk for severe storms over our northern tier of counties. However, given some models limit afternoon convection, decided to maintain just slight chance PoPs across generally northern locations Friday afternoon and evening. During the overnight hours, yet another round of upstream, decaying MCSs are forecast to move into the mountains and foothills through sunrise. Like clockwork, there is little guidance consensus on the evolution of these features. However, its worth noting that some CAMs do indicate the potential for another round of strong sfc gusts embedded within associated cold pools early Saturday morning. Worth watching for sure. && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 355 PM Thursday... The mid/upper low and occluded surface low will track east across southern Ontario/Quebec and the Great Lakes on Saturday and Saturday night, dragging a cold front to the south that will pass through central NC during the afternoon and evening. Model guidance indicates an MCS will approach from the TN Valley on Friday night, but weakening significantly as it crosses the Appalachians and approaches central NC on Saturday morning, with outflow surging out ahead of it. Models struggle with depicting the strength and timing of these MCS's, especially this far out, and that will be critical for the severe storm threat later in the day. A weaker MCS that passes through earlier on Saturday would favor more daytime heating and destabilization compared to vice versa. The NAM Nest is the only high-res guidance that goes out this far, and it does depict ample instability resulting in a broken line of showers and storms developing along the cold front from Saturday mid-afternoon into the evening. However, lower-res guidance is mostly dry, and moisture with the front does not look impressive, as the flow aloft is from a westerly direction. Furthermore, we will only get weak upper forcing with the low tracking so far to our north. GFS/ECM/CMC ensemble mean QPF continues to trend drier and is less than a tenth of an inch. So while convective coverage is still unclear, think it should be pretty isolated, and only have slight to low chance POPs. Still, there is a conditional threat of a few strong to severe storms with large hail and damaging winds developing along and ahead of the front, as surface-500 mb bulk shear will be as high as 40-50 kts. Also can't rule out some strong cold pool induced wind gusts with what is left of that MCS on Saturday morning. Saturday's temperatures may be kept down in the morning by outflow and clouds from the system, but we should still get good surface heating in the afternoon as clouds break and we get strong SW winds ahead of the front (gusting up to 20-30 mph even outside of any storms). So forecast highs are still mid-80s to lower-90s, not quite as warm as Friday, but heat indices in the mid-to-upper-90s will still be possible in the SE. The mid-level flow will turn NW from Sunday into Tuesday, as we are caught between the low slowly drifting east over New England and the Canadian Maritimes and ridging that strengthens and builds east from the MS Valley to the Deep South and TN Valley. At the surface, a backdoor cold front looks to move through central NC on Sunday night. This front then looks to lift back slowly north on Monday and Tuesday, and latest guidance has trended toward the front lingering more on top of our region instead of to our SW. Precipitation chances could be enhanced by a series of MCS's that move overtop the ridge and through the southern Mid-Atlantic. So expect gradually increasing shower and storm chances each day, but there is still plenty of uncertainty. The next mid/upper low will move east from the Central Plains on Tuesday, but models disagree on the pattern evolution after. The GFS picks it up by a northern stream low over the Great Lakes and is more progressive, while the ECMWF keeps the systems separate and thus hangs them back longer. This will have a big impact on precipitation chances as well as temperatures, but it looks like an associated cold front will move through sometime Wednesday or Thursday. For now have POPs increasing to high chance to likely on Wednesday, decreasing somewhat on Thursday as the GFS and most of its ensembles are dry by then while the ECMWF and CMC are still wet. As cool high pressure extends south from the Hudson Bay into the Eastern US, expect at least slightly cooler temperatures from Sunday into Tuesday with highs mainly in the 80s and lows in the upper-50s to mid-60s. Dew points will be more tolerable compared to now, generally mid-50s to lower-60s. A sharp drop to below-normal temperatures should occur late next week once the Wednesday/Thursday cold front moves through. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 755 PM Thursday... 24 hour TAF period: Aside from an isolated shower or two east of KRWI, the remainder of the eve/night should be largely dry and VFR. However, cannot rule out some sub-VFR vsbys invof KRWI, where a storm occurred earlier this aft. Winds should become light and variable tonight, then generally wswwd at 5-10 kts Fri aft. Beyond 12Z Fri: Low confidence forecast as there is still a fair deal of uncertainty wrt a potential MCS, expected to intensify and move ewd across the mid-MS valley tonight. Some guidance suggest the MCS could hold together as it moves across the mountains and into the Triad as early as noon, tracking ewd along and north of I-85 through the aft/early eve. Other guidance has the MCS decaying as it moves across the mtns and keeps convection largely suppressed owning to a fair deal of debris cloudiness from the decaying MCS moving across the area early/mid day. Given the uncertainty, will keep TAFs at one line for now, but a period of storms/restrictions may need to be added for Fri aft/eve with later forecast issuances. Outlook: Chances for diurnal isolated to scattered showers and storms will continue through much of the period. Morning fog and low stratus will be possible each morning, especially in areas that received significant rainfall the previous day. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CBL NEAR TERM...Green SHORT TERM...Luchetti LONG TERM...Danco AVIATION...KC/CBL ####018006367#### FXUS61 KGYX 160152 AAB AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 952 PM EDT Thu May 15 2025 .SYNOPSIS... A weak pattern with low pressure offshore will support humid conditions and hit and miss showers this evening and again Friday afternoon and evening. through Friday. Unsettled weather continues for the weekend as a more robust system brings widespread showers and thunderstorm chances by Saturday Night. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Update...Most coastal ASOS/AWOS sites have dropped to 1/2 mile visibility or lower at this hour. I do not anticipate visibility to improve overnight...so I have issued a dense fog advisory thru mid morning. Previous discussion...Clouds have steadily lifted north capping temps for southern counties particularly where seabreeze has kicked in. With moisture pooling we are seeing hit/miss showers with instability sufficient enough to support a few bolts of lightning. Once daytime heating ends all shower activity will cease. Another weak upper ridge moves over the area, leading to a lull in activity and more stable conditions overnight. As a result, expect stratus and areas of fog to develop after dark, particularly near the coast. Visibilities could drop to 1/2 mile or less at times, so locally dense possible. Fog will be less impactful inland, but will expect some reduction in visibilities. Clouds and humidity levels will keep lows in the 50s overnight. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Stratus/fog will dissipate through morning, though clouds are likely to linger longer near the coast while breaking inland by late morning. High temperatures will be mainly in the 70s and a bit muggy. With the area remaining moist and warm in the wake of a warm front passage, additional showers and thunderstorms will be possible late afternoon and evening as that weak upper ridge and its associated subsidence depart to the east. The progression of the warm front could serve as a focus for convective initiation, and any storms that do form could produce locally heavy rainfall. Forcing overall looks modest with ridging not far away no notable shear. Thinking it will be just unsettled with scattered to widespread showers, primarily in the afternoon with a few thunderstorms mixed. PWATs have increased to around 1.25-1.5" with surface dewpoints in the upper 50s to low 60s, supporting some good rain makers and if movement is slow there could be some spotty accumulations around 1". Showers diminish in coverage with the loss of daytime heating Friday Night, but still cannot rule out some light showers through the night. Mild pattern continues with low to mid 60s for lows. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Key Points: -Rainy weekend ahead, with most consistent rainfall expected from heavy showers Saturday afternoon. -Showery conditions on Sunday with widespread light rain north of the mountains. -Showery weather wraps up Monday evening, with a drier Tuesday/Wednesday. -Unsettled weather returns for the end of next week. Details: An upper-level low moves across New England on Saturday. A dying surface low looks to bring a couple rounds of showers across northern New England on Saturday. The first round exits the region Saturday morning, with showers generally pretty spotty in nature as the associated occluded front falls apart. As the low moves closer, another round of showers associated with a stronger occluded front develop to the west, moving into New Hampshire by the afternoon. These showers are more organized, and may move across NH and ME quickly. Guidance is still a bit uncertain on the timing, with the ECMWF indicating an earlier arrival and the NAM suggesting showers arrive later on in the evening. Areas that see repeat activity could accumulate 1 to 2 inches of rainfall, but the majority of the region will see amounts around an inch. Flooding is not expected at this time. Sunday, the center of the low moves across northern NH and ME, allowing for more light rain Sunday with some showers also making down to the rest of NH and Maine. The low may hover over NH and ME for a while, continuing the showers possibly through Monday evening. Conditions should dry out at least a little by Tuesday as the aforementioned low moves off into the Atlantic. The end of the week may feature unsettled weather as another upper-level low moves in from the southwest. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Short Term...Hit/miss showers this evening expected to skirt most airports but given their spotty coverage they are not likely to cause impacts at terminals. Coverage will drop off after dark when a stratus/fog deck builds in overnight. IFR to LIFR conditions likely at most terminals, with dense fog at RKD and near 1/2sm conditions at nearby airports. Long term...Restrictions may be down during showers, a few thunderstorms and rain that will be moving through the area Saturday through Monday. At this time, the best chances to see reduced restrictions look to arrive Saturday evening as a front moves across the NH and ME. && .MARINE... Short Term...Latest obs show SE winds 5 kt with seas >2 ft this afternoon. Light winds expected through tonight, supportive of more fog. Similar pattern expected Fri, SE 5 kt early increasing to S at 10 kt. Fog conditions likely to linger under humid conditions into Friday night. Long Term...Southeasterly flow at 8-14kts expected on Saturday. A low moves across the area, shifting winds to the southwest at 7-10kts by Sunday. As the low continues to move out to sea, winds shift to northwesterlies at 11-17kts by Monday, with winds staying there through Wednesday morning. Seas of 2-4ft are expected Saturday through Wednesday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Dense Fog Advisory until 9 AM EDT Friday for MEZ018>028. NH...Dense Fog Advisory until 9 AM EDT Friday for NHZ014. MARINE...None. && $$ NEAR TERM...Legro SHORT TERM...Jamison LONG TERM...Palmer