textproduct: NWS Wilmington

WHAT HAS CHANGED

Aviation discussion updated with 00Z TAF issuance.

Previous... Discussions updated. Temperatures for late week have been reduced slightly to account for an ongoing warm high temperature bias.

KEY MESSAGES

1) Increasingly hot and humid conditions are expected through late week with very limited chances for showers or storms.

2) Low rain chances during the week become elevated over the weekend ahead of a cold front.

DISCUSSION

KEY MESSAGE 1... Increasingly hot and humid conditions are expected through late week with very limited chances for showers or storms.

KEY MESSAGE 1 DESCRIPTION...Mid-upper ridging will remain in control this week with its axis staying west of the area while high pressure dominates offshore around Bermuda. As the ridge strengthens on Thursday and shifts towards the area on Friday, temperatures are expected to rise well-above normal, with low-mid 90s expected away from the coast on Thursday and mid-upper 90s on Friday. The sea breeze will offer relief closer to the coast. However, as the flow aloft becomes more westerly on Friday, expect the sea breeze to have a harder time shifting inland, allowing for even coastal areas to reach the low 90s. Although instability will increase as temperatures rise, no more than isolated pop-up showers and storms are expected through the end of the week, as dry air and subsidence aloft inhibit development. Heat index values should reach the upper 90s to low 100s on Thursday and at least into the low 100s inland on Friday. Whether dew points stay high enough to support 105F or greater for 2+ hours during the afternoon is questionable as model guidance this time of year tends to overestimate dew points.

The ridge axis is expected to be shoved eastward Friday night into Saturday as a cold front approaches from the northwest. Although temperatures will still end up well-above normal on Saturday due to the ridge axis being nearby, increased afternoon cloudiness and isolated to widely scattered showers/storms should generally prevent max temperatures from reaching the same levels as those seen on Friday, although this may be only 1-3F lower. By Sunday, the ridge axis should be far enough offshore and the front should be over or near the area, providing scattered showers and storms and some relief from the heat.

KEY MESSAGE 2... Low rain chances during the week become elevated over the weekend ahead of a cold front.

KEY MESSAGE 2 DESCRIPTION... With a mid-upper ridge axis west of the area, the coverage of showers and storms should remain isolated through the end of the week. However, guidance tools are hinting at a somewhat higher coverage of convection over the western half of the forecast area on Thursday as a weak shortwave trough comes in and helps out the surface trough over the Piedmont region. Although sufficient instability will be present for thunderstorms, forecast soundings depict a considerable amount of dry air in the mid-upper troposphere, which will inhibit development and keep coverage limited.

Over the weekend, the mid-upper ridge axis will shift eastward as a surface cold front pushes southeast. This front will slow down as it moves east of the Appalachians into the ridge, but its presence should increase the coverage of afternoon showers and storms to scattered for both Saturday and Sunday. As is typical for fronts this time of year, it should stall near or over the area before lifting back northwestward on Sunday. Thereafter, guidance tools diverge in the handling of upstream troughing, which should bring another cold front and increased rain chances into the area early next week.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Plenty of low level moisture avbl as a relatively stationary frontal boundary draped across the area is progged to basically dissipate overnight into Wed. Sfc ridging will extend across the area from the offshore high during Wed. The sfc ridge axis will drop south of the area by late Wed followed by the development of the sfc Piedmont trof. With continued dry air aloft, any convection that develops thru sunset will be shallow based. Too isolated to include in any of the terminals. Looking at low stratus or stratus fractus again tonight thru 14Z Wed, likely in the MVFR category but possibly dipping into the IFR category, especially inland terminals. After 14Z, will see sct/bkn cu that may initially lie in MVFR category but should lift to 3500-4500 ft by midday the latest. Have included/continued a prob30 tstorm group for LBT only during the 18Z-24Z time line. Winds generally SE-S 5 kt or less into the overnight. Further veering to SW 5 to 10 kt by mid to late daytime Wed morning and thru the remainder of the day. exception will be the coastal terminals where an active aftn/evening sea breeze will back winds to the S 10-15 kt.

Extended Forecast...MVFR/IFR ceilings possible again early Thu morning from stratus. Flight Restrictions from widely scattered afternoon/evening storms are possible each day through Friday, mainly inland, before an incoming front likely brings a greater coverage of showers and storms over the weekend. Otherwise VFR.

MARINE

High pressure shifting off the Mid-Atlantic coast today will result in winds veering from easterly this afternoon to southerly tonight. As this high shifts towards Bermuda, expect southwesterly winds by early Thursday with speeds between 10-20 kts through Friday night as a Piedmont trough sets up and tightens the pressure gradient against the high. With very warm temperatures on land, expect a healthy sea breeze to develop as well, and result in gusty south to SSE winds near the coast which can top out around 20-25 kts during the afternoon. As a cold front shifts in from the northwest and the Bermuda high moves away, winds slacken over the weekend.

Seas will run generally 1-3 ft in the 0-20nmi zone and 2-4 ft in the 20-60nmi zone. An easterly 8 sec swell will predominantly contribute to the wave spectrum through Wednesday with waves of 2-3 ft before subsiding to 1-2 ft on Thursday and 1 ft or less from Friday onward. Enhanced winds over Thursday and Friday will lead to wind waves contributing 2-3 ft (3-4 ft) waves in the 0-20nmi (20-60nmi) zones during those days. Lingering southerly wind waves of 1-3 ft will continue on Saturday with a 1 ft or less easterly swell.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...None. MARINE...None.