textproduct: Newport/Morehead City

WHAT HAS CHANGED

New set of Extreme Heat Warnings and Heat Advisories issued for all of eastern NC tomorrow.

KEY MESSAGES

1) Hot and humid temps persist across ENC into late in the week.

2) Subdued risk of showers and thunderstorms today with a modest uptick in risk overnight. Climo precip chances expected tomorrow and Wednesday.

3) Next front tracks across the area later in the week, ushering in a pattern change of relatively cooler but continued unsettled conditions.

DISCUSSION

KEY MESSAGE 1...Latest surface analysis this afternoon reveals a surface trough straddling the mid-Atlantic and Carolina coasts with a more defined cold front beginning to push across New England, the Midwest and the lower Mississippi Valley. Our area and much of the southeastern CONUS remains in the grip of a very hot and humid airmass, with temps climbing into the mid 90s and Tds, especially along the coast, hovering around 80. This has already yielded multiple readings of HI values between 110-115 especially for coastal locales. Today's headlines remain unchanged and in effect until 8 PM LT.

Aforementioned front well to our north will not arrive in our area until tomorrow evening, leaving the region once again in the same airmass. Unlike today where there will be little to no relief provided by convection, tomorrow will be a bit more active day and many areas could be convectively cooled by evening. Still, at least some period of HI of 110-115 is likely especially along the seabreeze with widespread 105-110 values elsewhere. A new set of Extreme Heat Warnings and Heat Advisories have been issued areawide for tomorrow.

Front will be stalled along the coast Wed and into Thursday. Cooler northeasterly flow will likely keep the most oppressive heat at bay from the Outer Banks and Albemarle Peninsula, but areas south of US 264, and particularly south and west of US 70, will likely still see an elevated risk of HI between 105-110 each afternoon. A more widespread cooldown is likely Friday into the weekend as a stronger cold front nears.

KEY MESSAGE 2...With little upper level support aloft, not expecting much if any convective development this afternoon. Latest satellite imagery strongly hints this, which has shown at best only slightly agitated cu fields along pinned sound and sea breezes. Cannot completely rule out one or two showers or rumbles of thunder, but opted to remove mentionable PoPs out of the forecast. Slightly better chances are expected tonight as scattered convection upstream gradually organizes into clusters and push eastward ahead of a more robust S/W pushing into SW Virginia per RAP mesoanalysis. There will be a modest uptick in forecast effective shear as this activity approaches ENC (up to 25-30 kt), but quick return of convective inhibition will prove hostile to its sustainment. CAMs suggest decaying activity potentially impacting areas from New Bern north, and opted to keep slight chance to chance PoPs for this after into the overnight hours. Deterministic and AI NWP guidance do not support an appreciable severe threat.

Climo PoPs return Tuesday and Wednesday as frontal boundary finally nears the area and stalls, providing an extra focal point for lift. For Tuesday, despite poor shear high PWATs exceeding 2.25" expected and a stronger cell could pose an isolated wet microburst threat. Otherwise, overall severe threat is low - less than 5%.

KEY MESSAGE 3...Stronger front is likely to approach the region and stall late week and into the weekend as part of a pattern change CONUS-wide, serving to both offer a reprieve from oppressive heat and humidity and a chance of strong to severe thunderstorms as shear increases alongside the boundary with stronger troughing. Given how far out this is, there are still several details to hammer out but will be monitoring trends in the forecast for any adjustments in timing and strength of this front in the coming days. NCAR medium-range AI NWP guidance continues to suggest at least modest probabilities (around 5%) of an environment favorable for strong to severe convection.

AVIATION /18Z MONDAY THROUGH SATURDAY/

VFR conditions prevail this afternoon under mainly sunny skies but oppressive heat. Far more subdued conditions expected this afternoon with only an isolated shower or thunderstorm possible, mainly along pinned sea and sound breezes and likely well away from TAF terminals. Slight chance (20-30%) that upstream convection developing across western NC holds together as it approaches the area after 00z, although waning instability will likely aid in their decay. Did put in a brief PROB30 for PGV to account for this risk.

Difficult to ascertain a low stratus and fog risk as it will be dependent on convection evolution through tonight, but with calm winds and very humid conditions would not be surprised to see some patchy instances of patchy fog early Tues AM.

Outlook (Tuesday through Friday): Expecting primarily VFR conditions through Thurs. The lone exceptions would be under isolated to widely scattered diurnally driven seabreeze shower and thunderstorm activity each day. No significant fog or low stratus concerns each night either but trends will have to be monitored in case the threat increases in the coming days. Yet another front begins to approach from the west Friday once again bringing increased shower and thunderstorm risks as well as increasing risks for sub-VFR conditions.

MARINE

Area observations show elevated southwest winds across area waters in a tight thermal gradient, sustained 10-15 kt with gusts up to 20 kt. A few isolated gusts to 25 kt are possible, most likely in the waters around Diamond Shoals, but frequency and coverage is too low to warrant headlines this afternoon.

Winds ease tonight as front slowly approaches from the north and west tomorrow. S to SW winds will persist for Onslow and Raleigh Bays, but north of Cape Hatteras winds will gradually veer north and northeasterly as boundary sags southward. Overall, winds should not push seas beyond the 3-4 ft range. Waters remain shower and thunderstorm free today, but will likely see an uptick of activity overnight, especially north of Cape Hatteras, as mid-level disturbance and associated activity originating in western NC makes its way east. Most likely time for develop is after 06z Tues.

Outlook (Tuesday through Friday): Benign boating conditions persist into Wed with eyes to next potential SCA late next week with a stronger frontal boundary. Each day will bring a low to moderate risk (20-40%) of showers and thunderstorms to area waters, with increasing chances into the weekend.

CLIMATE

Record High temps for 08/17 (Monday)

LOCATION TEMP/YEAR New Bern 96 / 1988 (KEWN ASOS) Cape Hatteras 93 / 2021 (KHSE ASOS) Greenville 99 / 1988 (COOP - Not KPGV AWOS) Morehead City 93 / 1984 (COOP - Not KMRH ASOS) Kinston 101 / 1938 (COOP - Not KISO AWOS) Jacksonville 97 / 1995 (NCA ASOS)

MHX WATCHES/WARNINGS/ADVISORIES

NC...Heat Advisory until 8 PM EDT this evening for NCZ029-044>047- 079>081-091-203>205. Heat Advisory from 11 AM to 8 PM EDT Tuesday for NCZ029- 044>046-079-080-091-092-193-203>205. Extreme Heat Warning from 11 AM to 8 PM EDT Tuesday for NCZ047- 081-090-094-194>196-198-199. Extreme Heat Warning until 8 PM EDT this evening for NCZ090- 092-094-193>196-198-199. MARINE...None.