Key message 1, A series of weak shortwaves rotating around an upper low centered north of the Great Lakes will push across the area over the next couple of days. An initial shortwave and attendant low pressure system will move out of the mid-Mississippi Valley and push northward through the Ohio Valley today. Short term models continue to show meager rain chances with better forcing tracking north of the area but still could see a couple rounds of showers possible with this system this afternoon and evening. Spc continues a day 1 outlook for a Marginal Risk of severe storms (level 1 of 5) across the Mid-Atlantic states, including ENC. Instability remain rather meager through much of the day but most HiRes models show an increase to around 500-1000 J/kg this evening, along with an increase in shear and low level helicity, although forcing for ascent will be weakening during this same time. If thunderstorms do develop this evening, they will have the capability of becoming supercells bringing a risk of strong winds, hail and isolated tornadoes.
Another shortwave will move off of the SC/GA coast on Thursday. Models not in best agreement and somewhat disorganized across our forecast area on the northern fringe of any precipitation. Pops have decreased some with the better chance along the southern coastal sections.
KEY MESSAGE 2, Our next chance for significant rainfall will be on Saturday as a low pressure develops off of the southeast coast and works its way over eastern NC. As this is happening an upper level low centered over Ontario and Quebec will work to deepen an upper level trough that will begin to push a supporting wave out of Texas which will eventually elongate into the frontal system that will accompany the coastal low. The merged systems will push through Saturday night into Sunday and move offshore but not before some significant rainfall with at least the southern half of the area having a 50% chance of at least an inch of rainfall.
As far as convection is concerned, currently most of the instability remains offshore but strong deep layer shear could help sustain any convection that initiates. Still a lot of uncertainty in the models regarding how strong the low will get and will have to monitor as the system gets closer.
06z Wednesday through Sunday Mainly VFR through this morning, then probs for MVFR cigs inc through the day. Some IFR fog has developed at KEWN, but an inc in high clouds should prevent this fg from becoming prevailing or widespread. Some spotty showers may afflict the terminals through the day today and into the evening, but fcst models have really backed off on QPF today, and thus will handle with just a VCSH mention. Mvfr cigs should prevail into tonight as well, with a chance of some lowering to IFR after around midnight.
Outlook (Thursday through Sunday): Back to mainly VFR Thu into Fri, then conditions deteriorate Fri night through Sat as widespread rain with lowered cigs afflict ENC. Winds generally in the 5-15 kt range through the rest of the week. The low pres area clears out by Sunday with return to VFR.
Currently seeing light winds less than 15 kt across the waters, mainly out of the east, with seas around 3-5 ft, except 5-7 ft across the central waters. Winds will gradually increase to around 10-20 kt this afternoon and evening as low pressure passes north of the area, then will become NW to N late tonight behind a cold front. Could see a few gusts to 25 kt tonight with best chances over the Gulf Stream waters, but most areas should remain below SCA criteria. Wave guidance continues to show seas up to 6-7 ft across the central waters through Thursday night and have extended the SCA here through that time.
Outlook: Another low pressure system may pass across or just south of the waters late in the week which could bring another chance for small craft advisory criteria to be met Saturday into Sunday.
Nc, beach hazards statement through this evening for ncz203-205. Marine, small craft advisory until 6 am EDT early this morning for amz150. Small craft advisory until 6 am EDT Friday for amz152-154.
