textproduct: Newport/Morehead City

WHAT HAS CHANGED

Lowered temps today given the most recent trends especially across the N'rn tier.

KEY MESSAGES

1) Stalled front to lead to increasingly unsettled weather into this weekend.

2) Typical summertime pattern develops by next week with a daily thunderstorm risk and warming temperatures.

DISCUSSION

KEY MESSAGE 1... Low stratus continues to hang around as a weak CAD setup has taken hold of eastern NC this morning limiting how warm we have been able to get so far today. Temps this morning have come in cooler than initially forecast ranging from the mid 60s to low 70s this morning for the most part. Expect the coolest temps to be found along our N'rn tier with highs in the lower 80s along the far southern zones of the CWA and mid 70s further north.

Prev Disc...Analysis of winds and dewpoints suggests the surface frontal boundary is currently draped over the northern tier of the CWA, south of the Albemarle Sound but north of the Neuse. The associated showers and thunderstorms however are still stalled to the north and west behind the front. This may be due to the ridging aloft over eastern NC blocking the precip from following the weakening surface front, in addition to a loss of daytime heating removing the fuel for downstream development. As the morning progresses, precip will slowly weaken to the NE while a coastal trough offshore brings scattered showers to coastal areas. In addition, low stratus behind the front could lower, bringing chances of dense fog to inland locales during the early morning hours. Given low probs elected to keep this out of the fcst, but it will be worth monitoring as the morning progresses. Thunder chances pick up late morning through the afternoon hours along and south of the front, but remain low north of the front as E/NE winds keep conditions more stable. With the front sitting just north of the Crystal Coast tomorrow, the sea breeze should initiate, quickly colliding with the front in the afternoon. This will create a locally enhanced region of convection, with higher coverage and QPF totals expected. With the loss of daytime heating tonight I expect coverage and intensity of convection to wane, much like we are seeing to our north and east right now. Saturday the front slowly shifts back north, overlapping with daytime heating. This will bring yet another round of convection focused along the front and sea breeze Saturday.

Deep layer shear beneath ridging aloft points towards a reduced risk of thunderstorm organization. At large, this should also lead to a reduced risk of severe thunderstorms. The one exception is during peak heating each day as steepening low- level lapse rates in a high PWAT airmass may support some water- loaded downdrafts capable of 40- 50 mph wind gusts and minor tree damage. This may especially be the case right along wherever the front sets up each day, as the area along the front will have the strongest convergence and "best" shear.

PWATs increasing to 1.75"-2.00" within a weakly-steered environment should support periods of heavy rain. The recent stretch of dry weather and ongoing drought should help to offset any hydro concerns. However, if heavy rain trains over any one area, especially urban areas, then a low-end flooding risk could materialize.

KEY MESSAGE 2...Once this weekend's front lifts north, ENC will get back into a typical late-spring/early summer pattern characterized by moderate instability and weak to moderate deep layer shear. Convective initiation should primarily be seabreeze-driven. Given the expected shear/instability combo, there should be a daily risk of marginally severe thunderstorms, especially from Monday onwards. This potential is also supported by both machine learning and analog guidance.

Near-climo temperatures are expected during this time, with highs in the mid to upper 80s inland, and low to mid 80s along the coast. It should be noted that while the forecast will reflect an increased chance of showers and thunderstorms on Memorial Day, an all-day washout is not expected. It will be more unsettled than what we have seen the past few weeks, though.

AVIATION /14Z FRIDAY THROUGH TUESDAY/

A slow-moving cold front is settling south into ENC, approaching the Crystal Coast. No mention of thunder in the fcst early this morning, as activity is mainly diurnally driven, but may cont to see some sct showers around coastal terminals. Cigs are dropping to IFR behind the front from north to south. The low clouds will continue shifting south through the early morning hours before some daytime heating helps raise ceilings to more MVFR levels. It is worth noting that guidance may be too quick to improve conditions, especially with the front expected to stall over ENC. so there is a degree of uncertainty to the end time of IFR conditions. Along and north of wherever the front stalls is where the greatest risk of IFR, or lower, conditions is expected. Along the front and sea breeze Friday there is a risk of thunderstorms. Have handled this with a PROB30 for TSRA in the afternoon hours. Thunder chances quickly diminish after sunset with loss of daytime heating. Friday night, sub-VFR chances increase once again, with fog possible in areas that see rainfall today and have calm winds under the stalled front.

Outlook (Saturday through Tuesday): A stalled frontal boundary will support a continued risk of ocnl sub-VFR conditions and on and off shra with some thunder, esp during the afternoon to early evening time frames with the sea breeze active each day with warm, moist airmass in place. Winds will be light, generally in the 5-15 kt range.

MARINE

A weak cold front is sliding slowly south into ENC tonight, with north or northeast winds developing behind it. Guidance suggests the front will stall around the central waters, with the northerly winds being focused primarily across the northern rivers/sounds/coastal waters. A weaker gradient along the front should keep the risk of 25kt winds lower for those waters. Along the front there will be a continued risk of thunderstorms. In addition to the cold front, a thermal gradient of sorts is setting up along and west of the Gulf Stream, bringing scattered showers and chances of thunder for warm Gulf Stream waters. The cold front will remain stalled across the area through Saturday morning.

Outlook: A cold front will remain stalled across the area through Saturday morning. The front will then shift north as a warm front Saturday afternoon, leaving behind a more typical summerlike pattern.

MHX WATCHES/WARNINGS/ADVISORIES

NC...None. MARINE...None.