Swell Matrix

Area Forecast Discussion

National Weather Service Newport/Morehead City Nc

1002 am EDT Wed Jun 19 2024

Synopsis

High pressure dominates through Thursday resulting in dry and warm conditions. Coastal troughing may bring some showers to the region late in the week into the weekend. A steady increase in heat and humidity is expected over the next several days with "feels like" temperatures potentially reaching the triple digits on Sunday.

Near Term

Rest of today As of 10 AM Wed, No significant changes to the forecast for the rest of today as ENC continues to warm up with temps already in the 80s across most locations. Expect a continued warm and dry trend through the rest of today with a deck of fair weather cumulus expected to increase in coverage through the afternoon.

Prev Disc, Another day of pleasant weather is in store as surface high pressure and the mid-upper ridge remain dominant over ENC. Weak surface troughing will setup this afternoon, which could support a few sprinkles, but chances are low given the weak forcing and strong subsidence. Highs will max out around 90 across the inner coastal plain with the coast and OBX reaching the mid- upper 80s. With dew points in the low 60s, minimum RHs will be around 35-40% (see Fire Weather section for details).

Short Term

Tonight As of 4 AM Wednesday, Mild overnight temps return ranging from the low-mid 60s across the inner coastal plain to low 70s along the OBX. Fog seems unlikely given greater cloud cover and unlikelihood that we'll reach crossover temps. Low stratus seems more probable given our continued onshore flow and increase in low- level moisture.

Long Term

Thursday through Tuesday As of 230 AM Wednesday,

- Elevated fire weather concerns continue into this weekend

- Building heat and humidity this weekend into early next week

- Increased thunderstorm risk early next week

Synoptic Summary: Surface and upper level ridging are forecast to remain in place through the end of the work week. Ridging then begins to break down over the weekend and into next week as upper level troughing develops from the Great Lakes into the Eastern U.S.

Thursday: A moist easterly flow and modest WAA may support a few westward-moving coastal showers, especially Thursday morning (similar to what has been observed early this morning). Rainfall amounts look to be very light, but given a consistent signal in deterministic guidance, I felt it worth a low-end chance mention along the southern OBX/Crystal Coast area. Otherwise, Thursday should be the last day of near normal temperatures thanks to lower thicknesses in the continued easterly low-mid level flow.

Friday-Sunday: Medium range guidance continue to insist that the upper level pattern will begin to change during this time. As upper level ridging breaks down, and as the surface high shifts offshore, a moistening return flow is forecast to develop. Within this flow, low-level thicknesses will begin to increase as well. This will lead to a steady increase in the heat and humidity, starting Friday, and most likely peaking on Sunday. By Sunday, dewpoints in the 70 and highs in the 90s is expected to support "feels like" temperatures rising into the 100-105 degree range. This has been consistently supported by both deterministic and ensemble guidance, and we'll plan to begin messaging this impact in the HWO and other public- facing products.

Despite increasing moisture, warm temps aloft will support a notable cap through at least Saturday. This combined with limited forcing should keep the risk of showers and thunderstorms at a minimum. Any chance of showers should be confined to the daily seabreeze. On Sunday, less of a cap is expected, and we should see a little more activity on the seabreeze (but probably still isolated in coverage).

Lastly, a tightening pressure gradient within the developing lee- trough will support increasing south to southwest winds by Sunday. Ensemble guidance suggests dewpoints will mix out across the coastal plain as the winds and mixing increase, and this seems reasonable given the dry pattern of late, and very dry soils. With this in mind, the overlap of lower RH and breezy conditions should support a continued elevated fire weather risk.

Monday-Wednesday: Deterministic and ensemble guidance continue to show a moderate to strong signal for deeper moisture reaching Eastern NC within the continued southerly low-mid level flow. This in tandem with the seabreeze, a glancing shortwave, and possibly a cold front dropping into the area is expected to support an increased thunderstorm risk, especially on Monday. The overlap of moderate instability and modest deep layer shear could also support a marginal severe thunderstorm risk.

Dewpoints are expected to peak during this time, with a subsequent peak in humidity values. Afternoon highs are less certain, though, due to the potential for increased convective activity. However, given the boundary layer moisture in place, "feels like" temperatures could make a run at 100+ where sufficient heating can occur. Right now, Monday looks to carry the greatest risk of heat- related impacts.

Aviation

14z Wednesday through Sunday Through Wed As of 7:20 AM Wednesday, VFR conditions are expected with diurnal cu developing in the afternoon. After the loss of peak heating, coverage will diminish to mostly clear skies as we head into the overnight hours. Overnight, some low stratus clouds may advect inland given persistent easterly flow and increasing low-level moisture.

Wednesday night through Sunday As of 230 AM Wednesday,

- Sub VFR CIGs possible (40-60% chance) along the coast Thursday

- Breezy southerly winds Sunday and Monday

- Increased TSRA risk Monday

A moist easterly flow may continue to support isolated SHRA activity along the coast on Thursday, along with SCT/BKN low CIGs. This appears most likely along the coast, with less of a risk inland. Drier air then works back in Friday into Saturday, with less of a risk of SHRA or sub-VFR conditions. Breezy southerly winds are likely Sunday into Monday (60-80% chance). Increasing moisture within the southerly flow is also expected to lead to an increased TSRA risk, especially by Monday.

Marine

Through Wednesday As of 4 AM Wednesday, Seas are building across the outer waters due to the distant tropical wave and extended period of easterly flow that we've been experiencing. The outer waters south of Oregon Inlet are expected to build to 6 ft by this afternoon, so a SCA has been issued for these zones through 11 PM tonight. The wind field will remain easterly at 10-15 kt with gusts near 20 kt south of Cape Hatteras.

Wednesday night through Sunday As of 230 AM Wednesday,

- Elevated wind and seas possible Sunday - Monday (40-60% chance)

- Increased thunderstorm risk on Monday

Continued easterly flow is expected to continue to support seas of 4- 6 ft on Thursday. Seas then slowly lay down to 2-4 ft as we move into the weekend thanks to a weakening of the easterly flow. Light south winds of 5-15 kt Friday and Saturday increase to 15-25kt Sunday into Monday, along with seas once again building to 4-6 ft. A few showers will be possible on Thursday, and again on Monday. The greatest risk of thunderstorms is expected Sunday night into Monday.

Watches, Warnings, Advisories

Nc, none. Marine, small craft advisory from 3 pm this afternoon to 11 pm EDT Thursday for amz152-154-156-158.

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