textproduct: Newport/Morehead City

WHAT HAS CHANGED

A Heat Advisory has been issued for southern sections of ENC for today.

A Flood Watch has been issued for portions of ENC for today and tonight.

The risk of severe weather has slightly increased for today.

KEY MESSAGES

1) Dangerous heat to last one more day, especially south of HWY 70.

2) An active pattern is expected through Saturday, including a risk of strong to severe thunderstorms, heavy rain, and flooding.

DISCUSSION

KEY MESSAGE 1...Light southerly flow in advance of an approaching cold front will help hold dewpoints in the mid to upper 70s through this afternoon. While there is some uncertainty regarding the placement of the front, and when convection gets going, it appears there will be an opportunity for sufficient heating south of HWY 70, supporting highs in the low to mid 90s and heat indices of 105-107 degrees. In light of this, a small Heat Advisory has been issued for late this morning into this afternoon. Along the Crystal Coast, heat indices may hold around 105 degrees through early this evening. North of the coast, an increased risk of convection and clouds should begin to lower the heat risk a bit earlier (ie. 3-5pm inland vs 7-8pm along the coast).

KEY MESSAGE 2...Over the next couple of days, it appears that various mesoscale features will heavily dictate where the risk of severe thunderstorms and flooding will be focused. In light of that, it's important to keep in mind that some fluctuations in the risk areas are probable as the convective evolution becomes more clear.

Mesoscale features aside, the pattern checks several boxes for heavy rain rates, flooding, and severe weather. A high PWAT airmass is already in place, and will remain so through Saturday with values of 2-2.25" forecast. Meanwhile, heating of a very moist boundary layer should yield moderate to strong instability both today and Saturday. Today, in particular, MLCAPE is forecast to reach at least 2000- 3000j/kg, with some areas potentially exceeding 3000j/kg. Deep layer shear is forecast to be marginal, but may reach 20-25kt near a front that is forecast to stall across the area today. That should support a somewhat improved potential for storm organization. Consequently, the combination of strong instability and modest shear should support the potential for some rotating updrafts capable of hail up to around quarter size. Strong updrafts and enhanced stretching in the vicinity of various mesoscale boundaries may also support a brief/weak tornado risk. The most likely threat, though, is damaging, waterloaded downdrafts of 40-60 mph. Lastly, the combination of strong instability and an anomalously moist airmass should support the potential of 2-3"/hr rainfall rates. While thunderstorms are likely to propagate along various outflows and mesoscale boundaries, those rates should support a risk of flooding of urban and poor drainage areas, with an associated risk for flash flooding. This risk looks to be the highest in some of the more urbanized areas from Jacksonville to New Bern and north through Kinston and Greenville.

Now the complicated part. Guidance differ on the placement of the cold front and various outflow boundaries noted on radar and satellite this morning. The general consensus appears to be for the cold front to stall from near Kenansville east to near New Bern. Today's forecast and messaging is heavily dependent on that location. For example, there should be a maximum in low- level convergence where the seabreeze interacts with the front, and is where rainfall rates and amounts could potentially reach 2-5". If the front ends up further north, the heavy rain footprint would follow suite, and vice-versa. To try to best capture the various scenarios, a targeted Flood Watch has been issued covering the Greenville to Jacksonville to New Bern corridor where the risk of flooding appears to be the highest. Of note, the immediate Crystal Coast was left out as that area may tend to be in the shadow of the seabreeze, with lower rainfall totals. North and east of the watch area, instability and forcing may not be as high, which should also keep rainfall rates and amounts lower. Stay tuned as we continue to refine the areas at greatest risk for severe weather and flooding.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

A front is slowly settling south into North Carolina at this time, and it is forecast to stall west to east from near KCLT east through near KEWN. Guidance differ on where it will stall, but where it ends up is where the greatest risk of TSRA is expected to be through tonight. Additionally, the TSRA risk will likely be enhanced by an upper level wave moving east-northeast out of the Southern Appalachians this morning. This wave will move across the area later today and tonight. Through tonight, TSRA will be capable of LIFR VIS, gusty/erratic winds of 40-50kt, and hail up to 1" in diameter.

Of note, early this morning there will be a risk of low stratus with IFR/MVFR conditions. This risk may lessen some during the day, then return tonight in the wake of any TSRA activity. The potential exists for areas of LIFR conditions in low CIGs tonight.

Outlook: An increased TSRA risk is expected to last into Saturday with similar impacts as Friday. The TSRA risk should take a step down on Sunday, but the risk isn't low either. It may not be until Monday before the risk substantially lowers.

MARINE

A cold front is moving slowly south through the northern waters early this morning, and should eventually stall around Cape Hatteras. North of the front, a modest northerly flow of 5-15kt can be expected. South of the front, a south to southeast flow of 5-15kt is forecast. Because of the light winds, seas should hold around 2ft through tonight.

Along the front there will be an enhanced risk of thunderstorms, the strongest of which will be capable of 40-50kt winds, hail, and waterspouts.

Outlook: An active thunderstorm pattern is expected to last into at least Saturday, with a somewhat lower risk by Sunday and Monday. A more dominant southerly flow is expected to become established on Saturday and last into Sunday. A cold front then moves through late Sunday with a west to northwest wind shift. Seas build to 3-5ft on Saturday, then lay down to 2-3ft by late Sunday as winds also lay down. Light winds and reduced seas are then expected into the middle of next week.

MHX WATCHES/WARNINGS/ADVISORIES

NC...Flood Watch from 11 AM EDT this morning through Saturday morning for NCZ044-079-080-090>092-094-193-194-198. Heat Advisory from 11 AM this morning to 8 PM EDT this evening for NCZ090-092-094-193>196-198-199. MARINE...None.