Key MESSAGE 1, There will be daily chances for showers and thunderstorms into at least mid week. Latest mid level water vapor imagery shows an upper level trough currently digging across the Ohio River Valley and into the Tennessee River Valley this afternoon and this will be our main weather maker for the next few days. The aforementioned upper trough will eventually stall across the Tennessee River Valley on Monday and move little into midweek. This will keep S to SW'rly flow aloft which will continue to advect in ample moisture from the Gulf and this will also result in several mid level shortwaves transiting around the base of this trough and across the Carolinas. The first shortwave is currently exiting the area this afternoon with the next shortwave forecast to track across the area Mon morning with yet another forecast to track across the area on Tue. At the surface, closed low in the Midwest will gradually shift E'wards into the Ohio River Valley today with its associated surface front stalling just to the west. These features, in addition to the sea breeze each afternoon/evening, will be the main forcing present for a notable increase in precip chances.
Ongoing shower and thunderstorm activity is forecast to gradually decrease in coverage this evening as the aforementionedshortwave pulls away from the area. Instability and shear has not been overly impressive today as MLCAPE values have remained around 1000-2000 J/kg and shear has remained below 20 kts which has limited storm organization. However, PWATs have shot up to above 2" as moisture has pooled across ENC as a result of the moisture transport from the Gulf today. With a deep warm cloud layer, and long skinny CAPEs heavy rainfall rates have been the norm this afternoon within shower and tstm activity. Luckily storm motion has been rather fast so not expecting any significant hydro issues this afternoon and early evening.
However, as we get into tonight and Monday, The next in a series of shortwaves moves through the area. With slightly better forcing, paired with another night/day of long skinny CAPEs and PWATs north of 2" brings yet another threat of heavy rainfall and potential for flash flooding, especially east of Hwy 17. A Flood Watch remains in effect for coastal NC, starting at 11 PM tonight and ending 5 PM Monday. Href and REFS probs of >1" of rain are over 40% the flood watch region, increasing to 50-70% for Hatteras Island, Ocracoke, Carteret county, and coastal Onslow county. Reasonable worst case scenarios show 2-4" of rain in the Flood Watch region, although higher values are possible where heavy rain rates linger with slow storm motions.
We remain in a Slight (level 2/5) Excessive Rain Outlook for tonight and into Monday with best chances at seeing flash flooding likely along Hwy 17 and points east.
Beyond Monday, the trough/low is still expected to linger to our west until eventually it gets picked up and shifted to our north by another trough moving through the Great Lakes region. As a result, daily elevated precip chances continue through mid-week with a low end risk for flash flooding. By the end of the week it looks like we return back to climo or below climo PoPs as a lack of mid level shortwaves or significant forcing will be noted across ENC though we do begin to warm back up with temps returning to the upper 80s to low 90s inland and mid 80s along the OBX.
18z Sunday through Friday A mix of VFR and MVFR conditions are noted across ENC this afternoon as scattered showers and thunderstorms have continued to impact the region. Expect this to continue over the next 1-3 hours before shower and tstm activity briefly abates as the area will remain between mid level shortwaves. However, as we get into tonight sub-VFR chances (MVFR to IFR ceilings) increase further as low level moisture continues to build. Coastal routes could see heavy showers and thunderstorms Sunday night into Mon morning, further reducing VIS and CIG with these sub- VFR conditions then persisting through much of Mon morning. In addition to all of this breezy winds will continue across the area with gusts up around 20 kts possible into 00Z before winds ease. Don't expect strong winds tonight into Mon.
Outlook (Mon afternoon through Friday): Periods of sub-VFR ceilings/vis are possible Monday afternoon into Wednesday as ENC enters into a more unsettled period of weather with daily chances for showers and thunderstorms with a stalled upper trough off to the west. Precip chances and thus the threat for sub-VFR conditions look to decrease beyond Wed.
Once again no significant changes to the marine forecast as 15-25 kt S-SW winds and gusts up to 25-30 kts are currently ongoing across our waters this afternoon bringing small craft advisory conditions to the area waters. Seas have jumped to 4-7 ft already across the area along the coastal waters. Expect elevated winds and seas to continue across our waters into tonight with only the inland rivers likely falling below SCA thresholds as the gradient remains pinched across ENC between a stalling front to the west and a ridge of high pressure to the east. Conditions do finally ease through the day on Monday with winds falling to 10-15 kts with gusts up to 20 kts and seas falling back down to 3-5 ft by Mon night ending the SCA threat for our waters. Sunday night a shortwave moves through, with shower and thunderstorm chances increasing substantially along the coast. There is still a threat of some low-end gusty winds, heavy rain, and lightning with convection Sunday night into Monday.
Outlook (Monday night through Friday): Expect more benign winds and seas from Tue onwards (5-10 kt winds and 2-4 ft seas) as weak high pressure builds over the area. In addition to the above, elevated chances for showers and thunderstorms will remain possible into midweek.
Nc, flood watch from 11 pm EDT this evening through Monday afternoon for ncz047-081-092-094-194>196-198-199-203>205. Beach hazards statement until 8 pm EDT this evening for ncz195- 196-199-204-205. Marine, small craft advisory until 8 pm EDT Monday for amz131-135-150- 230-231. Small craft advisory until 8 pm EDT this evening for amz136- 137. Small craft advisory until 11 pm EDT Monday for amz152-154-156- 158.
