Key message 1,
Latest mid level water vapor imagery shows an upper level trough currently stalling across the Ohio River Valley and into the Tennessee River Valley and this will be our main weather maker for the next few days. 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. A shortwave is tracking across the area this morning with yet another forecast to track across the area on Tue. At the surface, closed low looks to be over the Great Lakes region as it slowly shifts NC and becomes separated from the parent trough.
Here in ENC, a narrow, scattered line of convection with brief heavy downpours is moving through the region along the aforementioned shortwave, with stratiform rain behind it. In the next 6 hours, This scattered band should push offshore with additional convection near Charleston progressing NE'ward near Cape Fear and approaching the CWA. There is uncertainty if the storms near Charleston keep their structure through time due we have CIN developing with the light rain spreading over ENC right now and the shortwave over SC weakening as it approaches NC.
With the more progressive nature of the scattered line moving through ENC and lighter, stratiform rain behind it, flash flooding potential has gone down drastically in the next 3 hours. While the environment is very favorable with PWATs over 2.2" and long, skinny CAPEs, the lack of substantial forcing and shear has thrown a wrench in the flooding potential. Have decided to keep the Flood Watch in effect until 5 PM despite the reduced potential, as it will only take one boundary in a very messy regime to set up shop for torrential downpours and localized flash flooding to occur. Have trended down in QPFs with the decreased potential with this update, from 1-3" in the flood watch area, to 1-1.5 inches. Obx from Oregon Inlet down to Ocracoke has the benefit of being in closer proximity to the gulf stream convection, so if any outflow or boundary shifts westward over OBX, that could be a focus for persistent convection later today.
This afternoon through mid-week there continue to be be daily chances for heavy showers and thunderstorms. Seeing how this morning is playing out, it seems like any additional shortwaves along a weakening trough may not be enough to provide enough storm coverage for flooding potential. However, as the trough weakens in the coming days the sea breeze may become the dominant forcing mechanism, and be the focus for minor flooding potential going forward through mid-week.
We remain in a Slight (level 2/5) Excessive Rain Outlook for today with best chances at seeing flash flooding likely along Hwy 17 and points east. We are in a Marginal (level 1/5) ERO for Tuesday for the entirety of eastern NC.
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.
03z Monday through Friday Sub-VFR chances (MVFR to IFR ceilings) increase through the morning further as low level moisture continues to build. Coastal routes could see heavier bouts of showers early this morning, further reducing VIS and CIG with these sub- VFR conditions then persisting through much of Mon morning. Don't expect strong winds today outside of any convectively driven gusts. Vcts once again as we build daytime heating by Mon afternoon.
Outlook (Mon night through Friday): Periods of sub-VFR ceilings/vis are possible 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.
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 peaked at to 5-9 ft across the area along the coastal waters. Expect elevated winds and seas to continue across our waters into the morning hours, gradually easing through the day today. Winds forecast to fall 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. There is still a threat of some low-end gusty winds, heavy rain, and lightning with convection today.
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 through Monday afternoon for ncz047-081-092-094- 194>196-198-199-203>205. Beach hazards statement from 8 am EDT Monday through Monday evening for ncz195-196-199-204-205. Marine, small craft advisory until 5 pm EDT Monday for amz131-230-231. Small craft advisory until 8 pm EDT Monday for amz135-150. Small craft advisory until 11 pm EDT Monday for amz152-154-156- 158.
