Swell Matrix

Area Forecast Discussion

National Weather Service Newport/Morehead City Nc

339 am EDT Mon apr 24 2017

Synopsis

A complex low pressure system will impact Eastern North Carolina today into Tuesday. High pressure in the central Atlantic will build in Wednesday through Friday.

Near Term

Through today As of 330 AM Mon, Latest analysis shows upper low over AL/GA/TN this morning, with 1016mb sfc low over coastal GA, and associated warm front lifting through the NC offshore waters. Closed upper low will pivot into southern GA and SC today as strengthening surface low re-develops off the SC coast late today and tonight. Latest radar imagery shows shower activity blossoming right along the coast and offshore early this morning. Have seen a few lightning strikes offshore, and will continue to monitor convection along the coast this morning for potential spin ups moving onshore as instability increases. Main precip threat is along the coast this morning, becoming more widespread this afternoon and evening with deep moisture feed from the E/SE, combined with increasing lift and moisture transport. Spc has most of the area outlooked in Marginal Risk for severe storms. An isolated strong thunderstorm will be possible with the potential for damaging wind gusts, hail and/or a tornado. The Flash Flood Watch continues late today and tonight, includes all but the far northern counties and Outer Banks. Low level thickness values and widespread clouds/precip support highs in the upper 60s/mid 70s today, coolest inland where NE/E winds will persist through the day.

Short Term

Tonight As of 330 AM Mon, Stacked low will continue to lift along the Carolina coast tonight, with widespread showers and isolated thunderstorms. Spc keeps most of the area in a Marginal Risk for severe wx, with modest instability, 0-6km shear increasing to 30-40kt, and good low level helicity. An isolated strong thunderstorm will be possible with the potential for damaging wind gusts, hail and/or a tornado. Nssl WRF shows area of organized convection developing over coastal SC/SE NC early evening, then pushing NE through ENC late evening and overnight. Flash Flood Watch continues, with periods of heavy rainfall likely. Latest guidance suite does keep the heavier rainfall S/SW of the area tonight, but could still see storm total 2-4" with locally higher amounts 5", especially across the W/SW zones where the watch remains in place as PWAT values climb to above 1.5". Expect precip to taper off early Tuesday morning, from SW to NE. Strong winds will develop tonight along the coast as low lifts northward. Issued Wind Advisory for the Outer Banks, with gusts up to 50 mph.

Long Term

Tuesday through Sunday As of 245 AM Mon, Stacked low pressure will lift NE across the region Tue. Main precip band will shift offshore during the morning with some dry slotting aloft spreading in. Cool temps aloft will lead to rapid CU development if get any Sun with sct shra and few tsra expected rest of the day. Given cool temps aloft some hail could develop with stronger storms. High will be in the 75 to 80 dgr range most areas. Will cont to have some wraparound shra Tue night espcly cst as the low drifts offshore. Drier air will spread in Wed as the low departs with no precip expected and highs reaching upr 70s/lower 80d inland to mid/upr 70s cst.

Warm and mainly dry weather expected rest of the period as ridging aloft develops over the area with low lvl SW flow around offshore high press. Cant rule out isold late day TSRA along sea breeze inland but overall not expecting much precip. With good deal of Sun shld see highs 85 to 90 inland to upper 70s low 80s coast Thu through Mon. Lows will be mainly in the 60s with some coastal sites holding in the lower 70s at times.

Rain Forecast

As of 330 AM Mon, Flash flood watch continues for W/SW sections of the CWA as this area has best chance of seeing storm total 2-3 inches of rain with locally higher amounts up to 5 inches. Latest guidance suite does show the area of heaviest rain remaining S/SW of the area late today and tonight, though will keep watch in place. Heaviest rain is expected late today and overnight, as low strengthens and moves along the Carolina coast.

Aviation

07z Monday through Friday Through tonight As of 330 AM Mon, Widespread IFR/LIFR ceilings remain locked in this morning, with sub-VFR conditions expected through the bulk of the period. Forecast soundings and high res NARRE guidance show ceilings lifting later this morning and early afternoon, esp for OAJ/EWN as warm front lifts through the terminals. Low confidence on when exactly IFR ceilings lift to MVFR or possibly VFR, at this time think between 15-18z for the inland sites. Pgv/iso could remain locked in with IFR ceilings through most of today. Widespread showers and isolated thunderstorms today and tonight, with periods of moderate to heavy rainfall. Isolated thunderstorms could become strong to severe. Wind gusts 20-25 mph today and tonight.

Tue through Fri As of 245 AM Mon, Expect pds of sub VFR Tue into Tue night as shra and a few TSRA cross assoc with stacked low pres. Drier air will start spread in Wed and shld see VFR. Vfr will cont Thu and Fri as summer time pattern develops with offshore high pres leading to warm SW flow over the region. An isold aftn/evening tsra poss along sea breeze but majority of time will be dry.

Marine

Through tonight As of 330 AM Mon, Latest obs show NE/SE winds 10-20kt with seas 5-7 feet. A complex low pressure system will impact the waters through the period, with dangerous boating conditions developing this afternoon and tonight. A warm front will lift north through the waters this morning, as associated low pressure area tracks through the SE. The low is forecast to move along the NC coast tonight into Tuesday. Main change on this forecast package was to upgrade northern waters and Albemarle Sound/Alligator River to gales, and inland rivers to SCA. Gale warnings continue for the coastal waters and Pamlico Sound. Conditions will deteriorate quickly this afternoon and evening, with SE/E winds increasing to 20-30kt, with gusts 40-50 kt, strongest across the outer central waters, peaking tonight. Nwps shows seas building to 8-15 feet. Issued high surf advisory north of Cape Lookout, for rough surf and minor beach erosion.

Tue through Fri As of 245 AM Mon, Stronger winds will be NE of region by Tue morn with flow become S/SW 10 to 15 kts as low press lift NE just inland. Winds become more W Tue night into Wed morn as low lifts NE of region. Pred SW flow 10 to 15 kts then expected later Wed into Fri as high pres offshore becomes dominant feature.

Despite diminishing winds seas will remain elevated thru mid week. Seas Tue morn 6 to 10 ft will grad diminish to 5 to 7 feet by later Wed. Thu thru Fri expect 3 to 5 foot seas with SW winds chop and lingering swell.

Watches, Warnings, Advisories

Nc, flash flood watch from 2 pm EDT this afternoon through Tuesday morning for ncz044-079-080-090>095-098. Beach hazards statement from 8 am EDT this morning through this evening for ncz095-098-103-104. High surf advisory from 5 pm this afternoon to 8 am EDT Tuesday for ncz095-103-104. Wind advisory from 7 pm this evening to 6 am EDT Tuesday for ncz103-104. Marine, small craft advisory from 4 pm this afternoon to 5 am EDT Tuesday for amz136-137. Gale warning from 5 pm this afternoon to 7 am EDT Tuesday for amz135-152-154. Gale warning from 11 pm this evening to 7 am EDT Tuesday for amz130-131-150. Gale warning from 5 pm this afternoon to 2 am EDT Tuesday for amz156-158.

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