textproduct: Wakefield

WHAT HAS CHANGED

Extreme Heat Warnings have been issued for Thursday and Friday generally along and north of US-460. Heat Advisories have been issued Thursday across the rest of the area (excluding the MD Beaches and Currituck Outer Banks) with Extreme Heat Watches in effect for those areas on Friday.

Updated Equipment section.

KEY MESSAGES

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.

2) Storm chances gradually increase this weekend into early next week.

3) Temperatures gradually trend closer to normal next week.

DISCUSSION

As of 345 PM EDT Wednesday...

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.

Latest analysis depicted a strong (596dm) ridge centered over E KY, WV, NE TN, NW NC, and W VA this afternoon with high pressure underneath the ridge. This has allowed for temps to rise into the mid 90s NW to the mid-upper 80s SE with dew points in the upper 60s to mid 70s (as of 230 PM). Heat indices were around 105-106F across the Piedmont to Chesterfield County with lower values east of I-95. Expect temps to continue to rise into the upper 90s NW to the upper 80s to lower 90s SE later this afternoon with heat indices around 105-106F spreading east towards the Richmond Metro and interior portions of the Northern Neck. As such, Heat Advisories remain in effect for those locations.

Model guidance continues to remain in strong agreement regarding very hot temperatures given the anomalously strong upper level ridge building across the eastern half of the United States through Sat. At this point it's not a matter of if it is going to get hot for several days but a matter of fine-tuning the exact temperatures and dew points. As such, confidence continues to remain very high that this significant heat wave will continue into the weekend. Additionally, this setup has the potential to be the most widespread and of longest duration heatwave since July 2012.

The hottest conditions arrive tomorrow into Sat (potentially lasting into Sun) with virtually all guidance showing the potential for widespread highs above 100F (especially on Fri and Sat). In fact, a local tool calculating max temp from thickness depicts up to 101- 102F across a large portion of the FA Fri and Sat. This is quite impressive and lends additional confidence to the very high temps from deterministic models and the NBM. Nevertheless, still think the NBM is a bit too high for temps (Fri and Sat). As such, have highs around 99-101F across the NW half of the FA with 90s SE Thu and 99- 102F for most Fri and Sat. Will note that a few locations may reach 103F+ Fri. Uncertainty in temps increases a bit Sat and even more for Sun given the potential for convection. If convection does not occur, highs could reach above 100F Sat and even Sun. Overnight lows may struggle to drop below 80F in urban areas and along the middle Ches Bay/ Eastern Shore Thu and Fri nights, resulting in little relief in the heat overnight. Given the forecasted temps, multiple daily record highs are at risk of being broken (mainly Thu- Sat). See climate section below for more information.

Additionally, if temps reach this high, dew points could mix out (more than most models show) inland. This could potentially put a cap on the higher-end heat index scenarios. Regardless, widespread heat indices of 105-110F+ are likely from Thu-Sat (potentially lingering into Sun). However, newer model guidance (such as the 12z MET) show dew points potentially remaining in the mid 70s into Fri afternoon. If dew points trend higher than Fri would easily be able to reach heat indices of 110F+ area-wide. Will also note that wet bulb globe temps (WBGT) around 90F are possible generally along and north of US-460 on Thu and up to 90-91F across most of the area Fri (89-90F Sat). The combination of very high temps, heat indices, the duration of the heatwave, and the increase in outdoor activity due to the holiday weekend have all factored in to the warning/watch decisions. As such, have issued an Extreme Heat Warning for Thu and Fri from Prince Edward County eastward to Sussex County and then northeast into the MD Eastern Shore where confidence is highest in reaching heat indices around 110F (or higher) Thu and Fri. For the remainder of the FA (excluding the MD beaches and Currituck Outer Banks) have Heat Advisories for Thu and Extreme Heat Watches for Fri. Additional consideration was given to extending the watches and warnings through Sat, however, after coordination with neighboring offices, have decided to hold off for this update given aforementioned uncertainties regarding convection. Nevertheless, additional heat products will be needed on Sat (high confidence) and may be needed on Sun (moderate confidence). For the MD beaches and Currituck Outer Banks, heat indices look to remain at or below 100F Thu but increase to 105-109F Fri and perhaps into Sat. As such, these areas will likely need Heat Advisories on Fri and perhaps Sat but look to remain below Extreme Heat Warning criteria.

KEY MESSAGE 2...Storm chances gradually increase this weekend into early next week.

Given the strong ridge over the region, subsidence should keep most areas dry through Fri night. However, the RRFS and FV3 show the potential for lee trough convection late Fri afternoon into Fri evening. While this scenario is unlikely given the aforementioned subsidence, it cannot be ruled out. Additionally, given the high temps/dew points, any storms that form would have the potential to produce gusty winds. For now, SPC has only far northern portions of the FA under a Marginal (level 1/5) risk for severe storms Fri given the low confidence in convection (~15% PoPs). However, will have to monitor trends to see if higher PoPs are needed in the Piedmont. A better chance for isolated to scattered showers or storms arrives late Sat afternoon into Sat evening with the highest confidence across the Piedmont (30-45% PoPs). Confidence decreases farther south. The EURO, GFS, and 12km NAM show the potential for cluster of storms developing Sat. If this solution is correct, strong winds would be possible with the storms (especially if an MCS forms). As such, we will continue to monitor and severe probs may be needed as we get closer.

The ridge breaks down Sun into Mon with NW flow developing aloft as a new ridge strengthens across the west-central CONUS. It is not uncommon for heatwaves to end with severe weather. As such, will have to monitor conditions into early next week for the possibility of strong to severe storms. For now, PoPs increase to 40-50% Sun, 50- 60% Mon, 45-60% Tue, and 25-45% Wed.

KEY MESSAGE 3...Temperatures gradually trend closer to normal next week.

The ridge continues to break down next week across the Eastern CONUS as a new ridge strengthens across the central/west-central CONUS. This should place the local area in NW flow which should lead to near normal temps and an unsettled pattern. Given the potential for convection each day, confidence in temps is low from Mon onwards. If convection does occur, temps will likely not be as hot as the NBM shows, particularly Mon.

AVIATION /19Z WEDNESDAY THROUGH MONDAY/

As of 125 PM EDT Wednesday... VFR conditions will continue through the TAF period, with mostly clear skies and S-SW winds prevailing. A few gusts to 15-20 kts are possible this afternoon/evening at SBY, otherwise winds will range from 6-12 kts.

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 245 PM EDT Wednesday...

Key Messages:

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

High pressure remains the dominant feature across the area this afternoon. Winds are S-SW at 10-15 kts across the local waters. A few areas of 15-20 kts are being measured in the northern waters, though this is not widespread. Seas are 2-3 ft, and waves in the Bay ~1-2 ft. This regime of southerly winds will continue through the rest of the week and into the weekend, with generally sub-SCA conditions prevailing. S-SW winds will show some diurnal backing to SSE in the late afternoon/evening each day. With the southerly winds, there may be some channeling effects within the Bay and across the nearshore coastal waters, increasing winds to 10-15 kts during the afternoon. While a few gusts may reach 18-20 kts mainly late this afternoon into this evening this evening, have opted not to issue any SCAs for the Bay because it is so marginal and short- duration. The gradient across the area will relax through the week and into the weekend, so winds in these areas should continue to stay below SCA-criteria. Waves in the Bay will remain between 1-2 ft, and seas across the nearshore coastal waters will be 2-3 ft for the duration of the week.

Rip Currents: Continued with the moderate rip current risk for all beaches for the remainder of today, with the mention of S-N longshore currents due to wind direction (parallel to the shore) and speed. Have decided to go with a low rip risk for all beaches starting tomorrow through the remainder of the week. Though wave periods will be 7-9 seconds, winds will not be quite as strong and will remain parallel to the shore, and seas will average around 2-3 ft. Will continue to mention the longshore current for at least tomorrow.

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

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 Thursday to 8 PM EDT Friday for MDZ021>024. NC...Heat Advisory from 10 AM to 8 PM EDT Thursday 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 Thursday 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 to 8 PM EDT Thursday for VAZ065-066- 079-087-092-097>100-524-525-528>531. Extreme Heat Watch from Friday morning through Friday evening for VAZ065-066-079-087-092-097>100-524-525-528>531. Heat Advisory until 8 PM EDT this evening for VAZ048-060>062- 064-067>069-075-076-509>517-519-521-522. MARINE...None.