Key MESSAGE 1, A subtle upper level trough and associated weak shortwave will track SE'wards from the Ohio RIver Valley and just to the south of ENC across SC and GA tonight. At the same time, low level moisture is advected in from the south and west as PWATs increase from 0.85 inches which was noted on this mornings sounding to ~1 inch tonight. While there will still likely be some dry air aloft, steepening lapse rates especially along our SW'rn zones, and elevated forcing from the incoming shortwave could result in some isolated showers and maybe a rumble of thunder or two. Hi-res guidance such as the HRRR, FV3, AND WRF ARW do pick up on this low end chance and given at least some semblance of consistency with this signal, have included SChc PoPs in our SW'rn zones mainly after about 9/10PM. Otherwise lows remain rather warm tonight with lows in the 50s given scattered cloudcover and weak warm air advection.
KEY MESSAGE 2, Temperatures likely peak on Sunday across ENC with near record to potentially record high temperatures. Upper level that had been overhead in previous days finally pushes offshore and low level E to NE'rly flow from Sat becomes SW'rly allowing for warm air advection to begin in earnest. This will also allow for above normal low level thicknesses across the region for the time of year and therefore very warm temperatures on Sunday. Dry conditions expected with temps reaching well into the 80s across our interior zones and 70s along the coast. Once again, did manually bring up temps for NOBX Sunday with SW flow bringing a warmer continental airmass over the NOBX area so relied more on MOS guidance as compared to the NBM as the NBM typically under does these regimes. This results in mid-upper 70s across the NOBX. Some inland locales could exceed their record temps for the day so a CLIMATE section has been kept in place for Sunday.
KEY MESSAGE 3, An upper level trough dives south from the central Canadian Provinces and into the Ohio River Valley and Northeast, extending as far south as the Mid-Atlantic on Mon and into Tue. Its associated mid level shortwave rounds the base of this trough at the same time. At the surface this brings a backdoor cold front quickly through the area on Mon. Moisture remains lacking with this front, but still have a chance to see some isolated to widely scattered showers as the front moves through Mon morning/Mon afternoon so kept the 20-40% chance of showers in the forecast. While instability is rather low it is not zero as the front moves through keeping a low end thunder threat in place. Right now with much of the guidance bringing a slightly earlier frontal passage, thus limiting instability think there is currently a less than 20% chance at seeing thunderstorms with the frontal passage. So once again kept thunderstorms out of the forecast for now. The main sensible weather with this front will be a rapid increase of northerly winds behind it with temps dropping through the afternoon and into evening. If this front were to blow through in the morning, we would have had some fire weather concerns with stronger winds and drier air moving in, but an afternoon progression prevents any fire issues outside of the wind switch.
18z Saturday through Thursday VFR conditions are present this afternoon and are expected to continue through the TAF period with mostly mid and high levels clouds around.
Skies are mostly clear this afternoon as a trough moves through the Carolinas. A few isolated showers or thunderstorms are possible as this trough swings through late this evening, but this activity should mostly be west of the TAF sites, with KOAJ and KISO having the best, albeit slim chance. High pressure builds in from the south overnight and through tomorrow with dry and mostly sunny conditions expected.
Outlook: The next chance of sub-VFR conditions comes Monday as yet another cold front moves through. A TSRA risk may accompany this front as well. Gusty north to northeast winds (20-25kt) are expected with this front as well.
High pressure centered to the south in the Gulf will move little, while a weak low pressure system well to the north in the Great Lakes gradually tracks E'wards tonight into the Northeast. At the same time, previously mentioned cold front continues to slowly drop south and will eventually stall and dissipate over the area tonight. This has resulted in widespread light winds, generally 5-10 kts varying in direction from south to north with the southern waters seeing SW'rly winds still, while across the northern waters NE'rly winds are noted. Winds are forecast to become light and variable tonight before becoming S'rly across all waters on Sunday at 5-15 kts. Seas will lower to 2-4 ft during this timeframe. Then as we get into Sunday night the pressure gradient will tighten with the approach of a cold front increasing SW'rly winds to 15-20 kts with gusts up to 25-30kts along the Gulf Stream, and 4-7 ft seas. This will bring a return of the small craft advisories to our coastal waters south of Oregon Inlet where the warmer Gulf Stream Waters are.
Outlook: On Monday, SW winds increase further to 15-25 kts, with some 30+ kt winds possible on the Gulf Stream waters, ahead of approaching cold front. Front passes through Mon afternoon with stout 25-35 kt northerly winds developing in its wake through Mon night into Tue, with seas rapidly building to 6-9 ft behind the front later Monday. Gale force gusts not out of the question, particularly on the Gulf waters. By Tuesday evening conditions ease and more benign boating conditions are forecast by midweek as high pressure ridging builds in from the north and west.
Nc, none. Marine, small craft advisory from 8 pm Sunday to 8 pm EDT Tuesday for amz152-154-156-158.
