textproduct: Newport/Morehead City

WHAT HAS CHANGED

Raised pops for tonight but kept the thunder chances low.

Updated aviation 00Z aviation fcst.

KEY MESSAGES

1) Slow-moving front to impact temps, clouds, and fog potential through Sunday morning.

2) An unsettled pattern persists through much of next week with multiple opportunities for showers and thunderstorms.

DISCUSSION

KEY MESSAGE 1...A notable late-season cold air damming setup has led to a slowed northward progression of a warm front through ENC thus far today. As of 2pm, the front stretched from Kenansville to Washington. North of the front, temps were holding in the 60s and low 70s, while to the south it was in the upper 70s to mid 80s. Guidance is mixed on how far north the front will get, and it's possible it will stall over, or near, the coastal plain after sunset. North of where it stalls, another round of low clouds and fog will be possible tonight into Sunday morning. This front will also be a focus for enhanced convergence and an increased risk of showers and thunderstorms. Regardless of where it stalls tonight, the consensus is that it will lift fully north of the area by Sunday afternoon.

KEY MESSAGE 2...Upper level ridging over the Eastern U.S. and troughing across the Central U.S. will keep a southwesterly flow regime anchored across the Southeast over the next several days. The airmass within this regime will be characterized by a deep layer of moisture with PWATs consistently at, or above, 1.75", and moderate instability (500-1500j/kg MLCAPE). Meanwhile, each day looks to feature various sources of low- level and upper level forcing, with day-to-day variations that are not always modeled well. The theme here is that each day will likely carry a higher-than-climo risk of convection, but no one day looks like a complete washout. There are a couple of important items worth noting over the next few days, each highlighted below.

1) Severe thunderstorm potential. Deep layer shear will be weak through this weekend, but is forecast to improve some next week as we get a subtle glancing influence of stronger mid-upper level westerly flow. This may especially be the case Monday- Thursday, and machine learning and analog guidance continue to show a marginal severe thunderstorm signal. Additionally, tonight through Sunday, an MCV lifting out of Georgia is forecast to support an enhancement to the LLJ, and in tandem with the various surface boundaries in place, may provide just enough low-level turning for a brief landspout/tornado potential. This risk may be the highest during the day Sunday when 3CAPE is maximized along the seabreeze or any other surface boundary.

2) Heavy rain potential. An increasingly moist airmass combined with periods of moderate instability and increased convergence and low- mid level forcing should support very heavy rainfall rates at times. There may be just enough flow to prevent training or slower-moving convection, but at least some minor hydro impacts may develop where rainfall rates are maximized, especially for urban/poor drainage areas. Of note, some guidance suggests rainfall amounts of 3"+ may occur where the deepest convection materializes.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

The SHRA risk looks to ramp up again tonight into Sunday, with thunderstorms becoming a concern again for Sunday esp as the day goes on a sfc heating builds, but confidence is low to moderate regarding the location and timing of these heavier showers and storms. Will handle TSRA threat on Sunday with a prob30 fcst.

Otherwise, the other aviation forecast challenge will be the progression of a slow-moving warm front. The front currently stretches from KDPL to KOCW, and is forecast to move north of KISO and KPGV by 00z this evening. The front may continue north overnight or it may stall. The strength of the high over New England suggests the most likely scenario is for it to stall, which would then lead to another round of IFR/LIFR CIGs tonight along and north of where the front is. Confidence in IFR/LIFR conditions is the highest at KISO and KPGV, with a lower risk to the south. Regardless of where the front stalls, it should lift north of all TAF sites on Sunday with all areas under srly flow.

Outlook (Monday through Thursday): An unsettled weather pattern will continue into mid week with multiple opportunities for sub- VFR conditions in SHRA and TSRA. A nightly risk of low CIGs and VIS appears plausible as well. Drier conditions look to arrive by Thursday.

MARINE

A warm front is forecast to lift fully north of the area by Sunday afternoon. Prior to then, northeast winds will continue for waters north of the front, which should primarily be north of Oregon Inlet. Some patchy marine fog will be possible at times north of the front as well. Once the front moves through, south to southwest flow is expected to prevail, with improved visibilities. For inland rivers and sounds, there will be a continued risk of thunderstorms through Sunday.

Meanwhile, a persistent and longer fetch of northeasterly flow north of the front has led to building northeasterly swell, with seas of 4- 6ft currently being measured off the OBX. This increased swell of 9- 10s is expected to linger through Sunday, then gradually start to lay down on Monday. A Small Craft Advisory is in effect for the nearshore coastal waters through Sunday evening/night to account for this.

Outlook: A more typical summertime pattern is expected to close out the Memorial Day weekend, continuing into at least the middle of next week. Within this regime, there should be a daily building of winds and seas for the nearshore coastal waters and the inland rivers and sounds thanks to a strengthening thermal gradient. Occasional 25kt winds are expected during those times. There will also continue to be an increased risk of thunderstorms, but no all- day washouts are expected.

MHX WATCHES/WARNINGS/ADVISORIES

NC...Beach Hazards Statement until 8 PM EDT this evening for NCZ203- 205. MARINE...Small Craft Advisory from 7 AM to 10 PM EDT Sunday for AMZ150. Small Craft Advisory until 6 AM EDT Monday for AMZ152-154.