textproduct: NWS Wilmington

WHAT HAS CHANGED

Aviation discussion updated with the issuance of the 00Z TAFS.

KEY MESSAGES

1) Summerlike Bermuda high pressure will maintain southerly winds and unseasonably warm weather throughout the week.

2) The next cold front may arrive late Sunday accompanied by an increased chance of showers or t-storms.

DISCUSSION

KEY MESSAGE 1: Summerlike Bermuda high pressure will maintain southerly winds and unseasonably warm weather throughout the week.

An expanding upper level ridge off the Southeast coastline this week will support Bermuda High Pressure at the surface in a pattern that looks straight out of July. True, parameters like surface and 850 mb temperatures and 500 mb heights aren't at mid summer levels, but the overall pattern is very summerlike.

Forecast 500 mb heights near 5840 meters Thursday and Friday are above the 90th percentile for this time of year for both the Charleston and Morehead City upper air sites. A subsidence inversion between 7500-12000 feet AGL should cap off surface- based convection beginning Wednesday, meaning any isolated showers that can form later this week should remain shallow with little to no potential for lightning.

Inland forecast highs are in the 80-85 range each day through Sunday. Coastal areas should remain ~5 degrees cooler due to onshore synoptic flow supplemented by the daily seabreeze circulation each afternoon. This is still 6-12 degrees above normal for this time of year.

KEY MESSAGE 2: The next cold front may arrive late Sunday accompanied by an increased chance of showers or t-storms.

For a weather event seven days out, there is surprising model agreement with the timing of the next front coming up Sunday night April 5/6. An upper low centered near the Great Lakes on Sunday (Easter) should swing an upper trough across the Carolinas Sunday into Sunday night, potentially advecting a swath of Gulf moisture overhead and breaking down the ridge aloft enough to allow convection to develop along and ahead of the front. Current forecasts have 40-50 percent rain chances developing Sunday into Sunday night as this front approaches.

It's too early to get a clear handle on whether any severe weather potential will exist with this front. Forecast modest mid and upper wind speeds (strongest on the Canadian, weakest on the GFS) currently don't argue for this being a good severe weather setup, but these details will become more clear in the days ahead.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

VFR to dominate thruout the 24 hr period. The only exception will be a small window between 09z and 12z when reduced vsby from patchy fog in tempo groups may occur across the far inland terminals. Will advertise periodic onshore movement of scu/ac 5000-7500 ft agl across the coastal terminals tonight. With another cu field at 5000-7000 ft agl dominating the midday thru early evening hrs of Tue. High pressure centered well offshore from the Carolinas will ridge back to the W/SW across the area thru the end of the week. Looking at synoptic SSE-SSW flow thru the period, dependent on where the oscillating sfc ridge axis sets up shop across the Carolinas. Speeds generally 10 kt or less during the day and AOB 4 kt at night. This flow will become enhanced by the aftn thru early evening sea breeze with coastal terminals generally running 10-15kt g20kt.

Extended Forecast...Generally VFR conditions thru the period, although potential for early morning fog/stratus Wed/Thu/Fri mainly across the inland terminals. Sea fog may become an issue beginning for the coastal terminals toward the end of the week and weekend.

MARINE

Through Tuesday...Return flow around high pressure extending in from the east to northeast will maintain a mainly onshore southeast to southerly wind remaining around 10 kt. Potential for some higher gusts will exist mainly nearshore as sea breeze kicks in the afternoon. Seas will basically remain in the 2 to 4 ft range.

Tuesday night through Saturday...Bermuda High Pressure will maintain a south to southeasterly wind across the Carolina coastal waters through the remainder of the week. Wind speeds should average 10 kt or less, with the exception of the nearshore waters each afternoon and evening when seabreeze winds will locally increase this to around 15 knots.

With the overall weather pattern looking like something straight out of summer, we anticipate a smattering of showers developing for the second half of the week. Forecast low and mid level wind directions argue for the biggest shower threat to remain near Cape Fear where some Gulf Stream showers could survive the journey northwestward across the cooler shelf waters. Forecast seas also look like summer with an 8 second southeast swell expected to dominate the sea state through the end of the week.

ILM WATCHES/WARNINGS/ADVISORIES

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