textproduct: Wakefield

WHAT HAS CHANGED

Extreme Heat Warnings have been issued for portions of SE VA including Tidewater as Heat Indices of 110 or greater are expected. Otherwise no major changes have been made to the forecast.

Updated Equipment section and aviation discussion.

KEY MESSAGES

1) Major heat wave will continue today through Sunday, 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 345 AM EDT Thursday...

KEY MESSAGE 1...A major heat wave continues into the weekend with the hottest conditions likely Thursday through Saturday. This has the potential to be the most significant in both magnitude and duration since July 2012 for most of the CWA.

An anomalously strong upper level ridge continues to remain dominant across the eastern half of the United States today before starting to break down by late this Holiday weekend. Confidence continues to remain high that this ridge 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 where temperatures could potentially peak in the triple digits. This is due to the 594dm upper level ridge standing firm over the eastern United States and 21-24C 850mb temps. At the surface. high pressure will remain in control keeping the area dry under mostly clear skies. With strong diurnal heating occuring under a moist environment (DP upper 60s to low 70s) this could potentially lead to Heat Indices of 105-110+F. The greatest threat for Heat Indices of 110+ are along and north of US-460 and MD Eastern Shore (excluding the MD beaches) where Extreme Heat Warnings remains in effect for today. Will note that the greatest confidence in 110F+ is across the east-central Virginia where high temperatures mixed with higher DP are expected. Elsewhere there is the question of mixing. If dew points mix out enough temperatures could potentially reach tipple digits, however, the Heat Indices could fall shy of 110. The greatest confidence for diurnal temperatures reaching triple digits is across the NW portion of the CWA where DP are likely to mix out. Elsewhere, a mix of high DP and high temps will lead to Heat Indices of 105+ and Heat Advisories are in effect. Will not that the MD beaches could potentially be added later this morning but them and the NC beaches maybe shy of 105 Heat Index. Nevertheless it will be a hot and humid day.

Friday continues to look to be the hottest day as the ridge is at its full strength and high pressure continues to remain dominant over the area. The hot and humid airmass will continue to be locked in place. Friday there is high confidence that a majority of the area could see Heat Indices of 100 or greater especially adjacent to bay. A majority of the area along and north of US-460 and MD Eastern Shore (excluding the MD beaches) were already in a warning, but, during this forecast update there has been high enough confidence in the forecast to now upgrade portions of SE VA including Tidewater from a watch to an Extreme Heat Warning as Heat Indices of greater 110 are now expected. Continued to leave Greensville county and west, NE NC, and the MD Eastern Shore in a watch for now because they may not reach Heat Indices of 110 or greater. However, it looks to be solid Heat Advisory criteria with Indices of 105+.

Saturday's temperatures continues to remain 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 highest confidence of 110+ adjacent to the bay and along the SE coast. With the possibility of these showers and storms the Heat Watch will not be expanded through Saturday at this time. The Heat Wave looks to have its potential last stand Sunday with temperatures potentially reaching upper 90s to triple digits. But, just like Saturday there is the uncertainty with cloud cover, showers, and storms.

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.

By Friday there is the potential for showers and thunderstorms across the Far NW and down into the RIC Metro. Latest 00z CAMS remain in disagreement with each other. Some are overdoing convection while some have none at all. Under a very hot and humid airmass there will be a slight chance of storms in the afternoon. The greatest confidence in storm development would be off the higher terrain to the NW and these storms will need to ride their outflow to maintain themselves as there will be very little upper level support. These will be your normal summertime thunderstorms Friday and will be very brief but could pose the risk of damaging winds as DCape values are expected to be greater than 1500J/kg. Will note that there is the potential that the urban heat island could also help initiate showers and storms in the afternoon but confidence is not as high as the NW. Saturday and Sunday are the next true best chance of thunderstorms models continue to hint on cluster of storms moving off the higher terrain and pushing south. These storms could pose the risk of damaging winds as the hot and humid airmass remains in place. By early next week the upper level flow turns more NW as the ridge breaks down. As this occurs this could potentially bring rounds of showers and thunderstorms and possibly a brief period of severe weather back across the area. In addition, temperatures will likely fall back to seasonable early next week as the ridge breaks down.

AVIATION /12Z THURSDAY THROUGH MONDAY/

As of 635 AM EDT Thursday... VFR conditions with mostly clear skies will prevail through the 12z TAF period. Some showers have initiated along a boundary oriented along the VA Eastern Shore. They are in close proximity to ORF so decided to add a VCSH from 12-14z. Otherwise s-sw winds prevail today between 5-10 kt then become variable tonight.

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 330 AM EDT Thursday...

Key Messages:

- Sub-SCA marine conditions are expected to prevail through the weekend, with mainly southerly winds.

High pressure remains centered well off the mid-Atlantic coast, with low pressure across eastern Canada. S-SW winds are a bit elevated early this morning at 10-15 kt with gusts of 15-20 kt, but should drop off to 5-10 kt by later this morning, before shifting to S-SE at around 10 kt later in the day and into the evening. Seas are 2-3 ft, with waves in Bay ~2 ft. The gradient is expected to further weaken over the next 1-2 days as there will generally just be a lee trough across interior VA and broad sfc high pressure over Bermuda. Some diurnal wind speed and direction variability as mentioned above is likely to prevail for the next several days (mainly S-SW in the morning, becoming S-SE in the late aftn/evening). Isolated showers on the Ocean early on will dissipate through sunrise w/ generally nothing additional expected until later Friday (and this would be a low probability). Isolated/widely scattered storms over the weekend into early next week would be the only thing that would lead to brief higher winds. Waves in the Bay will remain between 1-2 ft, and seas across the nearshore coastal waters will be 2-3 ft today, dropping off to 1-2 ft Friday-Saturday.

Rip Currents: Low rip current risk today through Saturday as nearshore waves drop to ~2ft. Will continue to mention the longshore currents for today.

CLIMATE

Record Highs:

- Site: Thu 7/2 Fri 7/3 Sat 7/4 Sun 7/5

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

Record High Mins:

- Site: Thu 7/2 Fri 7/3 Sat 7/4 Sun 7/5

- RIC: 76/2014 77/2014 77/1900 79/2012 - ORF: 78/2018 78/2014 79/2012 80/1999 - SBY: 77/1968 76/2014 78/2012 81/2012 - ECG: 76/2014 78/2014 78/2012 77/2024

EQUIPMENT

KAKQ radar is down due to mechanical issues without an estimated time of return.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...Extreme Heat Warning from 10 AM this morning to 8 PM EDT Friday for MDZ021>024. NC...Heat Advisory from 10 AM this morning to 8 PM EDT this evening for NCZ012>017-030>032. Extreme Heat Watch from Friday morning through Friday evening for NCZ012>017-030>032. VA...Extreme Heat Warning from 10 AM this morning to 8 PM EDT Friday for VAZ048-060>062-064-067>069-075>078-080>086- 088>090-509>523. Heat Advisory from 10 AM this morning to 8 PM EDT this evening for VAZ065-066-079-087-092-097>100-524-525-528>531. Extreme Heat Watch from Friday morning through Friday evening for VAZ065-066-079-087-099-100. Extreme Heat Warning from 10 AM to 8 PM EDT Friday for VAZ092- 097-098-524-525-528>531. MARINE...None.