textproduct: Wakefield

WHAT HAS CHANGED

Updated the 06z/01 TAF

Extreme Heat Watches have been expanded to to the VA Eastern Shore and Mecklenburg County. Otherwise, no major changes have been made to the forecast.

Moderate Rip Risk for northern beaches today.

KEY MESSAGES

1) A major heat wave is likely beginning today, peaking Thursday through Saturday, before breaking down by late this weekend. This has the potential to be the most significant in both magnitude and duration since July 2012 for most of the CWA.

2) Temperatures gradually trend closer to normal late in the Holiday weekend and beyond, along with a more unsettled pattern.

DISCUSSION

As of 405 AM EDT Wednesday...

KEY MESSAGE 1...A major heat wave is likely beginning today, peaking Thursday through Saturday, before breaking down by late this weekend. This has the potential to be the most significant in both magnitude and duration since July 2012 for most of the CWA.

The 00z/01 ensemble guidance continues to remain in decent agreement on a anomalously strong upper level ridge building across the eastern half of the United States starting today and then breaking down by the Holiday Weekend. There continues to remain subtle differences in exact location of the location of the ridge, nevertheless, confidence continues to remain high that this will lead to a significant heat wave for the local area, potentially the most widespread and of longest duration since July 2012.

Today will be first day of the prolonged heat wave as the upper level ridge slowly propagates eastward and continues to strengthen. While at the surface High pressure will be firmly in control allowing for strong diurnal heating under mostly clear skies. This will allow for temperatures inland to rise in the middle to upper 90s especially along and west of I-95. While closer to the coast and across the SE, temperatures will be in the lower 90s. Dew points are forecasted to be in the upper 60s across the coast and SE but, will remain steady in the low 70s west of I-95. This will lead to Heat Indices in the triple digits across the west with some areas approaching 105F+. The highest confidence for these areas are across portions of the Piedmont and the far northwest where Heat Advisories remain in effect through this evening.

Thursday through Saturday, Ensembles show a 594dm upper level ridge and 850 temps of 21-24C, leading to increasing confidence that some areas could see temperatures at or above 100F, especially Thursday through Saturday. If temperatures reach this high, expect the dew points to mix out inland. This could potentially put a cap on the higher- end heat index scenarios, however, Heat Indices are likely to be close to Extreme Heat Warning criteria. Along the coastal zones adjacent to the bay and SE, there could likely be seabreeze development due to the weak pressure gradient at the surface. This will allow for slightly lower temps but higher dews. This will still lead to similar Heat Indices. At this time Thursday and Friday continue to have the highest confidence on Heat Indices nearing or just slightly above 110F. However, there is not enough confidence in any upgrade to a warning at this time. This is due to dew points potentially mixing out and causing Heat Indices to be below warning criteria. However, there is potential that both the VA Eastern Shore and Mecklenburg County could potentially near 110 Heat Index Friday and decided to add them to the Extreme Heat Watch for Friday. Will also note, that Friday currently looks to be the hottest day of the week with the possibility of widespread heat headlines as Heat Indices will likely be 105-110F+.

Saturday's temperatures are somewhat more uncertain at this time as the ridge begins to break down with multiple shortwaves moving through that could potentially lead to increased cloud cover and higher chances for showers and thunderstorms. If showers and storms do not fire temperatures could be just as high as Friday along with widespread Heat Indices of 105-110F+. With the possibility of these showers and storms the Heat Watch will not be expanded through Saturday at this time.

Will also make a quick note about low temperatures tonight through Saturday night. They will likely be in the low to middle 70s, with urban areas 75-80, allowing for little relief from the heat during the day.

KEY MESSAGE 2...Temperatures gradually trend closer to normal late in the Holiday weekend and beyond, along with a more unsettled pattern.

The ridge continues to break down Sunday, as multiple shortwaves gradually turn the flow aloft to the W-NW late in the weekend and beyond. It continues to look like a slow process, so temperatures likely stay above normal through Monday into but with higher chances for aftn/evening tstms. With a very favorable thermodynamic environment in place, severe thunderstorms of the pulse variety, plus possibly upstream MCS activity moving this way from the NW, would be on the table. With these daily chances in thunderstorms it could put a cap on how high temperatures climb Sunday and Monday. Both of these days temps have a solid chance of reaching potential heat headlines but with thunderstorm chances it could make issuing heat headlines difficult as time approaches. Otherwise, by next week temperatures look to return to normal.

AVIATION /07Z WEDNESDAY THROUGH SUNDAY/

As of 1253 AM EDT Wednesday... VFR conditions will prevail through the 06z TAF period at all terminals, with mostly clear skies expected. SE-S winds at ~5 kt will prevail through much of tonight, becoming S-SW by Wednesday morning. A few gusts to 15-20 kts are possible at SBY by mid- morning tomorrow. FEW aftn cumulus is possible, otherwise it should remain clear outside of high clouds.

Outlook: VFR conditions will continue through most of this week as high pressure builds S across the area and then settles offshore. Other than isolated showers/storms, mostly dry conditions are expected through the upcoming week.

MARINE

As of 325 AM EDT Wednesday...

Key Messages:

- Sub-SCA marine conditions are expected to prevail through the week, with winds becoming southerly starting tonight.

High pressure has become centered offshore, but is still ridging into southern VA and northern NC early this morning, with low pressure across Canada. Winds are now mainly from the south, with somewhat higher speeds across the northern waters (farther removed from the sfc high). Seas are 2-3 ft, and waves in the Bay ~1-2 ft. Later today, the sfc low across Canada shifts east, leading to a modest tightening up of the pressure gradient, which will lead to an increase in S-SE winds this aftn/evening. Along with some diurnal backing to SSE in the late afternoon/evening, conditions may get close to SCA levels in the Bay for a few hrs. While a few gusts to 20 kts are likely in the Bay, have opted not to issue any SCAs as it will be marginal and of short- duration. Waves in the Bay will briefly build up to 2-3 ft this evening, before dropping back to 1-2 ft overnight. Seas across the nearshore coastal waters will average 2-3 ft (but may briefly build to 3-4 ft off the eastern shore tonight with the increased S-SE flow. A similar pattern prevails Thu-Fri, but the pressure gradient is forecast to be slightly weaker so sub- SCA conditions continue with seas only 2-3 ft and waves 1-2 ft or less.

Rip Currents: Decided to add the northern beaches to a Moderate rip risk today as winds become S-SE and increase (in addition to the Moderate for VA Beach and Currituck NC), though both will be somewhat marginal with nearshore seas 2-3 ft. By Thursday, a low rip risk returns for all beaches and continues through the end of the week.

CLIMATE

Record Highs later this week:

- Site: Wed 7/1 Thu 7/2 Fri 7/3 Sat 7/4

- RIC: 102/1945 100/1953 100/1954 100/2002 - ORF: 100/1901 100/1901 99/1954 98/1997 - SBY: 98/2012 99/2014 98/1954 100/1919 - ECG: 101/2012 97/1953 98/1954 100/1997

Record High Mins later this week:

- Site: Thu 7/2 Fri 7/3 Sat 7/4

- RIC: 76/2014 77/2014 77/1900 - ORF: 78/2018 78/2014 79/2012 - SBY: 77/1968 76/2014 78/2012 - ECG: 76/2014 78/2014 78/2012

AKQ WATCHES/WARNINGS/ADVISORIES

MD...Extreme Heat Watch from Thursday morning through Friday evening for MDZ021>024. NC...None. VA...Extreme Heat Watch from Thursday morning through Friday evening for VAZ048-061-062-064-068-069-075>078-081>086- 090-509>523. Heat Advisory from 11 AM this morning to 8 PM EDT this evening for VAZ048-060>062-064-067>069-509>511. Extreme Heat Watch from Friday morning through Friday evening for VAZ060-065>067-079-080-087>089-092-097>100-524-525- 528>531. MARINE...None.