textproduct: NWS Wilmington

WHAT HAS CHANGED

No significant changes have been made to the forecast at this time.

KEY MESSAGES

1) Inland portions of the eastern Carolinas should see their longest heat wave of the year so far with five consecutive days of 90 degree heat expected Sunday through Thursday.

2) Rain chances should increase late this week as a front stalls near the Carolinas.

DISCUSSION

KEY MESSAGE 1...Inland portions of the eastern Carolinas should see their longest heat wave of the year so far with five consecutive days of 90 degree heat expected Sunday through Thursday.

Deep subsidence developing in the vicinity of a 500 mb ridge along the NC coast should lead to sunshine and warming temperatures for the first half of the coming week. 850 mb temperatures should creep up to +17C to +18C at times, at or above the 90th percentile climatological values for this time of year at both the CHS and MHX upper air sites. This should support inland high temperatures near 90 on Sunday, then in the lower 90s Monday through Thursday. This is also largely supported by statistical guidance and multimodel ensemble blends.

So far this year, our longest streak of 90+ degree or hotter heat (four days) occurred April 15-18 at both Florence and Lumberton. This coming heat event should eclipse that duration by one day in both locations. Heat indices could reach as high as the mid 90s Wednesday and Thursday.

With Bermuda high pressure remaining offshore and a light to moderate southerly synoptic wind in place, coastal cities (Georgetown, Myrtle Beach, Southport, and Wilmington) should remain significantly cooler than inland locations. Nearshore ocean water temperatures near 70 degrees should warm by several degrees over the next week, but even then will help provide up to 10 degrees of free, natural cooling to the coast.

KEY MESSAGE 2...Rain chances should increase late this week as a front stalls near the Carolinas.

After peaking near 5900 meters Monday and Tuesday, 500 mb heights should begin to fall later in the week as the upper level ridge is attacked by a weak cutoff trough over the western Atlantic and a series of stronger shortwaves traversing through the central Appalachians and Northeast. A surface low supported by the first of these shortwaves will move eastward across Quebec on Wednesday, pushing a surface cold front southward into the Carolinas Thursday. The boundary should remain quasi- stationary Friday into Saturday and should lead to scattered to numerous showers and thunderstorms.

The NBM may be too optimistic with its high coverage of measurable precipitation (60-80 percent) Friday and Saturday, but this still looks like our best chance for measurable precipitation since the thunderstorms we had last Monday. Severe drought continues across portions of the Carolinas and six-month rainfall has only been 50 to 70 percent normal, almost ten inches below normal at Myrtle Beach.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

VFR conditions are expected through the valid taf period. Some guidance suggests low clouds/br inland overnight. Confidence in that is low as dewpoints this afternoon have been steady or falling over much of the area despite light s to se flow. There is a nod to this possibility in the forecast for FLO as more guidance is suggestive of low clouds and fog there vs. other terminal sites.

Extended Forecast... Predominantly VFR through Wednesday though morning fog potential should increase through Wednesday as low moisture increases. An approaching front could bring restrictions in scattered showers and storms Thursday.

MARINE

Through Monday...Within 20 NM, light S TO SW winds are expected through period with seas of 2 to 3 feet.

From 20 to 60 NM out, generally expecting s winds less than 15 KT with seas of 3 to occasionally 4 feet.

Monday night through Thursday...Bermuda high pressure will remain over the western Atlantic through the period with generally light southerly winds expected. Seabreeze enhancement nearshore could locally increase nearshore wind speeds to around 15 knots from mid afternoon through early evening each day.

Changes should arrive on Thursday as a cold front approaches from the north and stalls somewhere across the eastern Carolinas. Shower and thunderstorm potential should tick up as the ridge aloft decays away and the front acts as an additional trigger for storm development. At this time we're continuing to forecast a southerly wind throughout Thursday, but we'll need to closely watch just how far south the front may move.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Coastal Flood Advisory from 7 PM to 10 PM EDT this evening for NCZ106-108-110. Coastal Flood Advisory from 9 PM this evening to midnight EDT tonight for NCZ107. SC...Coastal Flood Advisory from 6 PM to 10 PM EDT this evening for SCZ054-056. MARINE...None.