Key MESSAGE 1, Minor tweaks were made to the forecast for this weekend and a few minor things will need to be monitored today as well. For today, we will have a weak mid level shortwave lift north across the area later this morning into this afternoon which could spark a few isolated showers, mainly along our far western Coastal Plain. Otherwise, will continue to monitor the development of a passing coastal low this weekend which will bring some very beneficial rainfall to much of the area. Otherwise guidance remains in good agreement with a low pressure system passing just off the coast Saturday bringing much needed rainfall to the region. Upper level low sitting over eastern Canada this weekend will act to deepen an incoming positively tilted trough as it moves across the Mid-Atlantic Sat into Sun. Associated mid level shortwave strengthens as it nears and pushes off the coast this weekend as it rounds the base of this deepening trough. At the same time, a progressive southern stream jet stream will bring a second, slightly weaker shortwave across the Deep South and Southeast eventually merging with the northern stream shortwave. At the surface this will kick off cyclogenesis off the Southeast coast on Sat along a stalled frontal boundary located to the south of NC. As the two aforementioned shortwaves merge this low will begin to deepen as it tracks NE'wards along the OBX Sat afternoon and evening bringing widespread rainfall to ENC with highest rainfall amounts currently forecast along and east of Hwy 17. Probabilities for at least an inch of rainfall are still high, and decreased a tad inland. While NBM probs for precip greater than one inch inland are greater than 70%, HREF probs are closer to 10-50% inland. With the best moisture, instability, and forcing along the coast and offshore, the current thinking is rainfall totals inland will trend towards the lower end of guidance. Chances for precip > 1" along the coast S of Oregon Inlet are now 70-90%, decreasing a bit to 20-50% inland west of hwy 17.
As far as convection is concerned, currently most of the instability remains offshore with northerly flow keeping profiles more stable over land. This should keep rainfall rates low enough to preclude any flash flooding threat, especially when paired with the drought conditions in place. While there is still some uncertainty with how strong the low will get as it passes by the OBX on Sat, current thinking is the low remains above 1000 mb as it passes by the area before deepening further and at a much quicker pace to the north and east of the area.
KEY MESSAGE 2, The next timeframe we are monitoring will be mid to late week next week. A cold front moves across the Eastern Seaboard, with an upper level trough digging towards the Mid-Atlantic and SE. There remains a fair amount of uncertainty with the timing, as ECMWF has the frontal passage coming through Thu morning into the afternoon, and the GFS has the frontal passage Wed night/Thu morning and the Canadian has the front moving through THursday night. Ensemble probs for PWATs greater than 1.5" ahead of this front remain around 30-50%. If the model consensus shifts to the afternoon Thursday, and the upper level support remains just as impressive, instability would be maximized and we would have to start thinking about severe potential. Machine learning severe probs are highest in the Mid-Atlantic and SE US Thursday. At this point there is enough uncertainty to just take a wait and see approach.
12z Friday through Tuesday Flight conditions will remain VFR through the rest of the day with winds veering from NE to SE. Cloud cover will increase throughout the day as well, becoming OVC by tonight with CIGs lowering to around MVFR around midnight. Pops will start to increase along the southern coast this afternoon/early evening, spreading north overnight as a low approaches the area. As showers and thunderstorms overspread the area tonight and into Saturday, further reductions in VIS and CIGs are expected. The heaviest rainfall will occur near the coast Saturday morning with CIGs potentially lowering to IFR.
Outlook: Conditions will continue to deteriorate into Saturday as widespread rain, low VIS, and low CIGs overspread ENC. Periods of moderate to heavy rain are possible, especially within thunderstorms, which will be most likely near the coast. Vfr conditions will return Sunday and continue into early next week.
A northerly surge of winds is gradually making its way south across our waters this morning with light N'rly winds at about 5 kts ahead of the surge becoming N-NE at 15-20 kts with a few gusts up to 25 kts at times directly behind this surge. Much of the HiRes guidance continues to suggest any 25+ kt gusts we are currently seeing will be short lived in nature precluding additional small craft issuance outside of the central waters where seas are forecast to build to 4-7 ft while seas remain 3-5 ft elsewhere along the coast. Winds will gradually ease through the morning and into the afternoon to 5-10 kts and veer to an E and eventually a SE direction out ahead of an approaching low to the south. Seas along the coast will also lower down to 3-5 ft briefly ending SCA conditions across the central waters. However, as the aforementioned low begins to approach from the south and deepens winds will increase to 10-20 kts with our next round of small craft conditions then expected later Saturday as the low makes its closest point of approach.
Outlook: The aforementioned low will pass across or just south of the waters Saturday afternoon into Sunday bringing our next round of SCA's. For now it looks like outside of any thunderstorms that impact the waters which could bring locally enhanced winds and seas, winds will remain around 20-25 kts with gusts up around 30 kts with a few gusts up near 35 kts especially across the waters outside of 20 NM. For now it appears gusts would be infrequent enough and isolated enough to preclude any gale products but will have to monitor trends today to make sure it stays that way.
Nc, beach hazards statement through this evening for ncz203-205. Marine, small craft advisory until 6 pm EDT this evening for amz152- 154.
