textproduct: NWS Wilmington

WHAT HAS CHANGED

Heat Advisory in effect for much of the forecast area today. Small Craft Advisory in effect for all waters today.

KEY MESSAGES

1) Heat Advisory in effect today with additional advisories possible early this week.

2) Periods to monitor for enhanced precip chances are Sunday night/Monday afternoon and Wednesday/Thursday ahead of cold fronts. These fronts will also bring a low risk for thunderstorms containing strong to locally damaging wind gusts.

DISCUSSION

KEY MESSAGE 1...Heat Advisory in effect today with additional advisories possible early this week.

Mid-upper ridging will be nudged southward today as a trough passes by to the north. Remnant dry air and subsidence will still have some influence on today's weather, supporting another abnormally warm day with isolated pop-up showers and storms offering little relief due to their small size and short-lived nature. Although the leftover drier air aloft will help to knock dew points down into the low-mid 70s inland of the sea breeze during the afternoon, max temperatures in the middle 90s still support heat indices reaching around or above 105F in many locations. Nevertheless, moisture pooling ahead of a stalling cold front will help to increase moisture aloft and should result in more clouds than on Saturday, which could prevent some areas from reaching the 105F heat index criteria.

Additional very warm and humid days will follow into the first half of the new week as the aforementioned stalled front lifts back northward on Monday. Additional Heat Advisories may be necessary depending on the anticipated coverage of showers and storms and associated cloud cover, which will affect max temperatures and prevent dew points from dropping as much during the afternoon.

KEY MESSAGE 2...Periods to monitor for enhanced precip chances are Sunday night/Monday afternoon and Wednesday/Thursday ahead of cold fronts. These fronts will also bring a low risk for thunderstorms containing strong to locally damaging wind gusts.

As a trough axis passes to the north today, a cold front will settle southward into North Carolina and stall. Guidance tools and ensemble systems show the forecast area being on the southern fringes of greater precip coverage over Sunday night, with our northern tier of counties (Pender through Marlboro) having the best relative chances for scattered showers or storms to nose down from the north. There is also a low risk for strong to locally damaging wind gusts from storms this afternoon and evening. With weak lingering troughing in place and the front lifting back northward, isolated to scattered pop-up showers and storms appear likely on Monday.

As troughing becomes reinforced over the eastern CONUS during midweek, a stronger cold front is progged to push southward during the Wednesday/Thursday timeframe. This is likely to enhance precip coverage into the scattered to numerous realm, even during the overnight hours. How far south this front reaches before stalling, and when this occurs, carries low confidence as guidance tools remain mixed with respect to its position, so this will need to be monitored as shower and storm coverage could be enhanced into next weekend if the front is stalled along the coast as opposed to further offshore over the Gulf Stream. In addition, this front is expected to bring a risk for thunderstorms with strong to locally damaging wind gusts on Wednesday, along with a threat for localized flash flooding from heavy storms tracking over the same area multiple times. The flash flooding threat will persist if the front stalls along or just inland of the coast.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Except for a low probability of MVFR ceilings briefly this morning along the coast, VFR conditions should continue through the morning hours. By early afternoon (18z) there is a low to moderate potential for isolated showers or thunderstorms to develop with impacts possible at KLBT and KILM. Moderate southwest winds inland will be enhanced by the seabreeze with sustained winds increasing to 15-20 kt along the coast with gusts to 25 kt expected.

A slightly better potential exists for convection to impact the KLBT airport after sunset (01z) this evening. Scattered showers or thunderstorms could continue developing across southeastern North Carolina overnight, but confidence in timing is too low to include in the TAFs.

Extended Forecast... With a front stalled to the north, isolated to scattered showers and storms are anticipated Monday afternoon into the night with brief periods of MVFR or IFR restrictions possible. Confidence in showers/storms materializing is moderate to high, but confidence in the coverage is low. Forecast storm chances decrease on Tuesday, leaving a low risk for transient MVFR or IFR restrictions in convection. An approaching strong cold front will bring increased thunderstorm chances for Wednesday and Thursday.

MARINE

Sunday through Thursday... Steady south to southwest winds are expected through most of the period with daily enhancements nearshore due to the sea breeze. In addition, an approaching cold front will help tighten the pressure gradient today and again from Tuesday through Wednesday, warranting Small Craft Advisories for both periods. Seas remain elevated through today in the 3-5 ft range in the 0-20nmi zones and 5-6 ft in the 20-60nmi zones. Seas subside somewhat for the Sunday night into early Tuesday period before rising again to 4-6 ft in the 0-20nmi zones and 6-7 ft in the 20- 60nmi zones between late Tuesday and Wednesday night before subsiding on Thursday in tandem with weakening winds. The area of interest for possible tropical development in the northeast Gulf now carries an invest number (91L) and a 60% chance of formation through 48 hrs. Model guidance keeps this low in the Gulf due to an incoming strong cold front which stalls offshore on Thursday.

EQUIPMENT

A number of equipment issues have arisen this morning: - KCRE ASOS rain gauge is out of service. For climate record purposes, KMYR is the primary backup site for precipitation totals. - KLBT ASOS has only been intermittently transmitting observations this morning. The last full METAR was at 0656z, with a dozen or so 5-minute obs getting through since. - KLTX radar is suffering pedestal issues requiring frequent resets.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Heat Advisory from 11 AM this morning to 7 PM EDT this evening for NCZ087-096-099-105>110. Beach Hazards Statement through this evening for NCZ106-108. SC...Heat Advisory from 11 AM this morning to 7 PM EDT this evening for SCZ017-023-024-033-054-058-059. Beach Hazards Statement through this evening for SCZ054-056. MARINE...Small Craft Advisory until 4 AM EDT Monday for AMZ250-252. Small Craft Advisory from noon today to 9 PM EDT this evening for AMZ254-256.