Swell Matrix

Area Forecast Discussion

National Weather Service Newport/Morehead City Nc

1000 pm EDT Fri Mar 23 2018


High pressure will build in from the northwest tonight then move offshore Saturday. Low pressure will cross south of the area Saturday night. High pressure will build in from the north later Sunday through early next week as low pressure moves well offshore.

Near Term

Overnight As of 10 PM Fri, No changes needed with updated. Temps on their way towards freezing and are currently in the 35-40 degree range.

Previous discussion, As of 730 PM Fri, Ongoing fcst in good shape. Should see a sharp diurnal dropoff in temps tonight with very light winds and clr skies, so lowered hourly temps this evening with temps dropping to freezing around or after midnight for location away from the immediate beaches. Therefore fz warning for Carteret/Onslow still in good shape.

Previous discussion, As of 245 PM Fri, Latest sfc analysis shows 1044mb high pressure centered over south/central Canada, extending southward into the SE US. Mostly sunny skies across the region this afternoon, though could see scattered stratocu develop across the northern tier late this afternoon and this evening. Another cold night expected with good radiational cooling expected, given high pressure overhead and light winds. Low temps generally in the lows to mid 30s. Issued another Freeze Warning for inland portions of Carteret and Onslow counties, where the growing season has already begun.

Short Term

Saturday As of 245 PM Fri, High pressure weakens and shifts off the coast Saturday ahead of the approaching low pressure system from the west. Moisture continues to increase through the day as the low pressure area moves eastward. Still looks like most of the precip will hold off until afternoon, taking awhile to moisten the column. Adjusted pops slightly based on latest guidance, increasing pops inland late afternoon and early evening. The best chance for precip occurs Saturday night when isentropic lift and moisture are maximized. Another cool day with temps well below normal, highs in the upper 40s to low 50s.

Long Term

Saturday night through Friday As of 330 AM Friday, Saturday night through Sunday, A complex forecast this weekend and two systems phase across the region. A southern stream shortwave and sfc low pressure across the central Plains approaches from the west while a northern stream shortwave digs south across the mid-Atlantic with cold Canadian high pressure building in from the north.

The low will weaken as it approaches the area as it encounters the high wedging into the region but then redevelops off the coast as it encounters good baroclinicity invof the Gulf Stream. Precip amounts have increased some with generally a quarter to three quarters of an inch possible. Models continue to suggest the potential for wintry precip along and north of where the 850 mb through is progged to be, which is mainly across the northern tier, and have added rain or snow to the grids north of the Pamlico River. Not including any accumulation at this time as sfc temps will be above freezing but if precip rates are high enough could see minor accumulation on grassy/elevated surfaces. Temps continue below normal this period with highs Saturday in the mid 40s NE coastal sections to mid 50s south. Lows Saturday night expected in the mid 30s to around 40 and continued cool Sunday with highs in the mid to upper 40s most areas with lower 50s possible southern sections.

Monday through Thursday, A blocking pattern develops early to mid week as the upper trough lifts out early next week and becomes a vertically stacked low across the NW Atlantic while longwave ridging builds along the eastern seaboard. The upper ridge will maintain dry conditions while sfc high pressure continued to wedge in from the north keeping cool temps to the area Monday. The high weakens as we move into mid-week with the airmass gradually modifying, however how quickly it modifies will depend on the position and track of the cut-off low off the coast. Models are still not in good agreement with the movement of the upper low with the ECMWF still farther south and closer to the coast bringing us prolonged northerly winds across the region and cooler temps into mid week while the GFS is farther offshore allowing the high to push south faster bringing greater warming as we move into mid week. Could see temps into the upper 60s/lower 70s as early as Wednesday and mid to upper 70s Thursday if the GFS verifies, while the ECMWF is about 10 degrees cooler during the mid-week period.


02z Saturday through Wednesday Through Saturday As of 730 PM Fri, High confidence for VFR through the first 3/4 of the TAF period. Winds become light/var overnight with only some sct cirrus at best. Rain chances increase Sat afternoon with ceilings gradually lowering to MVFR in the afternoon. May be some sleet pellets falling as early as 21-22Z as temps aloft will be supportive of the sleet.

Saturday night through Wednesday As of 330 AM Friday, A weak low pressure area will move across the area Saturday night and expect IFR or below much of the overnight. The low pressure area pulls away from the area Sunday but lingering low level moisture may continue to bring sub-VFR conditions into Sunday. Expect pred VFR Sunday night through Tuesday.


Through Saturday As of 730 PM Fri, Allowed SCA to expire as seas have dropped below 6 ft for central waters. No other changes made. As of 245 PM Fri, Latest obs show N/W winds 5-15 kt, strongest across the outer central waters, with seas still 4-7 ft north of Ocracoke and 2-4 ft south. Extended SCA north of Ocracoke through early this evening for lingering elevated seas, but may be able to cancel early for the very northern waters. High pres will continue to build in from the NW tonight, weakening and moving off the coast Saturday, as an area of low pressure approaches from the west. N/NW winds expected to pick up to 10-20 kt tonight and early Sat morning, then becoming variable NE/E 5-10 kt Sat afternoon. Seas shld avg 3 to 5 feet north and central to 2 to 4 feet S late tonight, subsiding to 2-4 ft north and central to 1-3 ft Sat afternoon.

Saturday night through Wednesday As of 345 AM Friday, A weak area of low pressure approaches from the west and passes south of the area Saturday night.

NE winds begin to increase after midnight Saturday night as low pressure low deepens off the coast as it moves away from the area and reach 20-30 kt Sunday afternoon through Monday morning. Meso models are on the stronger side of the models and indicate a period of Gale Force winds possible, mainly coastal waters south of Oregon Inlet and perhaps portions of the Pamlico Sound. Seas build quickly Sunday as low pressure deepens off the coast, reaching around 7-10 ft north and 5-9 ft south by Monday.

The low pressure system stalls across the NW Atlantic as we move into mid week and there is a lot of uncertainty how far offshore this low will be and ultimately the wind direction and speeds across the coastal waters. Will continue to advertise N/NE winds around 10-20 kt Tuesday but if the low pulls farther offshore winds may weaken through the afternoon. The low will continue to bring large swells into the coastal waters and seas will potentially be around 8-12 ft or higher across the northern waters and 4-8 ft southern waters into mid-week.

Watches, Warnings, Advisories

Nc, freeze warning from 2 am to 9 am EDT Saturday for ncz095-098. Marine, none.

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