textproduct: NWS Wilmington

WHAT HAS CHANGED

Aviation discussion updated for 18Z TAFs.

Cold frontal passage timing has slowed slightly into early Sunday morning.

KEY MESSAGES

1) Warming temperatures, low daytime relative humidity, and zero rain chances through at least Saturday morning will lead to intensifying drought and fire weather concerns through the week.

2) No significant impact on drought conditions expected despite best rain chances/amounts in quite some time this weekend and early next week.

DISCUSSION

KEY MESSAGE 1...Warming temperatures, low daytime relative humidity, and zero rain chances through at least Saturday morning will lead to intensifying drought and fire weather concerns through the week.

Weak ridging aloft will support surface high pressure off the Southeast Coast through early Saturday, maintaining dry weather and gradually warming temperatures each day. Strong April sun will mix down dry air from within the subsidence inversion aloft, plunging inland dewpoints down into the 40s Thursday and Friday afternoons with minimum relative humidity expected to bottom out in the 20-25 percent range.

Above normal 850 mb temps should support high temperatures in the mid to upper 80s through Saturday, with moderate to strong seabreezes keeping coastal highs 5-10 degrees cooler.

Drought continues to worsen across the Carolinas as the last measurable rain occurred two and a half weeks ago on April 5-6. Two- month rainfall totals have only been 30-50 percent of normal, and six month accumulated rainfall is 6 to 10 inches below normal. Increasing plant transpiration as we move deeper into spring is leading to rapid decreases in soil moisture. The USGS Waterlevel Dashboard site shows local river levels have been steadily decreasing since March and about half of our gauges are at their lowest ever recorded stages for this date.

Lastly, HRRR surface smoke fields show that trajectories originating from the large wildfire east of Valdosta, GA will be pointed northward across the eastern Carolinas on Thursday. While the sky will likely have a smoky haze to it across our entire area, the SC Dept of Environmental Services is forecasting adverse air quality across Georgetown and Williamsburg counties. An Air Quality Alert is being issued for these two counties through late Thursday evening.

KEY MESSAGE 2...No significant impact on drought conditions expected despite best rain chances/amounts in quite some time this weekend and early next week. A frontal system will drag a cold front through early Sunday morning. Another approaching frontal system could drag the front back north as a warm front Monday into Tuesday with the system's cold front approaching towards the end of the period. These features will keep at least low rain chances in the forecast Saturday onwards with best chances Saturday night and Tuesday morning due to the frontal passages. Expected rainfall amounts have increase slightly, with the NBM indicating a ~40-50% chance of at least 0.5" for Saturday night/Sunday and no change to the chances for similar amounts Tuesday/Tuesday night (~20-30%). While total rainfall through the period has increased slightly to widespread amounts ~0.25" and some spots near 0.5", these still likely won't do much to improve the ongoing drought. According to our climate sites, we're 0% of our normal rainfall (~1-1.5") for the past 2 weeks. Embedded thunderstorms are possible with both frontal passages, but severe weather is not expected at this time. The frontal passage on Tuesday appears more favorable for low severe chances, but it is still uncertain at this time.

AVIATION /00Z THURSDAY THROUGH MONDAY/

VFR with light west winds that could veer and increase slightly tomorrow afternoon in a seabreeze, though the circulation will be largely pinned to the coast. Smoke from the large south Georgia wildfire will be transported northward across the Carolinas on Thursday but at this time vsby restrictions appear to remain confined well to our SW.

Extended Forecast...VFR conditions should prevail through at least midday Saturday. Showers associated with an approaching cold front could bring MVFR conditions Saturday afternoon through Sunday. Northeasterly wind gusts to 25 knots are possible behind the front Monday.

MARINE

Through Thursday...High pressure off the coast will maintain a southwesterly synoptic wind through Thursday. A shortwave diving southeastward off New England tonight will induce a wave of low pressure to develop along the Mid Atlantic coast, streaking eastward and away from land tonight. This low will tighten the pressure gradient as far south as the Carolinas, leading to near-Small Craft Advisory conditions north of Cape Fear tonight. GFS Marine MOS Guidance at Wrightsville Beach suggests seabreeze-enhanced winds could reach as high as 23 knots early this evening before diminishing overnight.

Winds should have a slightly more westerly direction Thursday as the low streaks away from the Mid Atlantic coast, but by afternoon the seabreeze should still result in southerly winds nearshore with speeds locally increasing to 15-20 kt in the afternoon.

Thursday Night through Monday...Offshore high pressure will prevail through Saturday with S to SW flow ~10-15 kts. The winds will shift to out of the NE with a cold frontal passage early Sunday morning, winds and seas failing to meet Small Craft Advisory criteria. These conditions will hold through Monday with a shift to the SE Monday night. Seas 2-4 ft.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...Air Quality Alert until midnight EDT Thursday night for SCZ039- 055-056. MARINE...None.