textproduct: Wakefield

WHAT HAS CHANGED

No significant changes

KEY MESSAGES

1) Following a brief period with seasonable temperatures through Tuesday, a major heat wave is likely beginning Wednesday, peaking Thursday through Saturday, before breaking down later next weekend. This has the potential to be the most significant in both magnitude and duration since July 2012 for most of the CWA. Shower/thunderstorm chances remain very low through Friday morning.

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

DISCUSSION

As of 245 PM EDT Monday...

KEY MESSAGE 1...Following a brief period with seasonable temperatures through Tuesday, a major heat wave is likely beginning Wednesday, peaking Thursday through Saturday, before breaking down later next weekend. This has the potential to be the most significant in both magnitude and duration since July 2012 for most of the CWA. Shower/thunderstorm chances remain very low through Friday morning.

High pressure is gradually building down into the region from New England this afternoon. Temperatures are seasonably cool and in the lower 80s, with dew points a bit more comfortable than the past few days (upper 60s). A shower or two remains possible through the afternoon hours today, mainly W of I-95, where a subtle moisture axis/theta-e ridge is located. Warming trend begins Tuesday with highs well into the upper 80s-lower 90s, except at the coast where onshore flow favors mid 80s.

Ensembles have remained consistent at building an anomalously strong upper ridge from the TN/lower OH Valley Tuesday, slowly drifting E- NE to the central Appalachians and Mid-Atlantic Thu-Fri, and slowly breaking down from the north over the Holiday weekend. While there remain some subtle differences in the precise location, confidence is high that this setup will lead to a significant heat wave for the local area, potentially the most widespread and of longest duration since July 2012. Given a strong consensus for H5 heights >595 dm and 850 mb temps of 21-23C, highs at or above 100 F are likely, especially Thursday through Saturday. With temperatures this high, do expect dew points to mix out quite a bit inland. This could put a cap on the higher- end heat index scenarios, but we are still likely to be near Extreme Heat Warning criteria. The weak sfc pressure gradient will also tend to allow for some aftn seabreeze development, locally bringing steady or falling late day temperatures for the immediate coast. However, these slightly lower temperatures at the immediate coast will be coupled with higher dew points, and several of the shorter-range models are beginning to hone in on 70s dew points during peak heating for SE VA and areas adjacent to the Chesapeake Bay. Therefore, heat indices in these areas are likely to be similar, or even higher, than inland locations. Regardless, the latest forecast shows heat indices of 105- 110 F fairly widespread for Thursday through Saturday (with pockets of 110+ possible). The general trend is that the northern areas of the CWA will probably be the hottest Thu-Fri, and the southern areas peak Fri-Sat. Regarding any potential headlines, it remains a bit too early to refine down the exact details. It does appear that a Heat Advisory might be needed for inland/northern portions of the area Wednesday (while S/SE areas will tend to see peak heat indices at or below 100F). Confidence is quite high in eventually needing Extreme Heat Watches for at least the Thursday-Friday timeframe (potentially lingering into Saturday). However, will hold off on any watches at this point after collaborating with our neighboring offices. Also confidence is generally higher in the temperature forecast and somewhat lower in the dew point/apparent T forecast given most cases with 100+ temps tend to see dew points briefly fall at peak heating, especially farther inland. Either way, the bottom line is that preparations should be made now for a period of very hot temperatures/heat indices late next week.

The only real opportunity for showers and storms in this pattern would be with seabreeze-initited convection along the coast. These large heat domes also bring a risk of "ring of fire" type convective complexes, i.e., thunderstorm clusters riding the northern periphery of the ridge. However, with the heat ridge centered over western VA/eastern KY, this does not appear very likely. PoPs are negligible Wednesday and Thursday, with 15-30% PoPs by late Friday as the ridge starts to break down and seabreeze convection becomes increasingly likely. This will all be better resolved as we get closer.

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

The ensembles are in decent agreement that the ridge starts to break down late Friday/Sat, with reinforcing troughing/shortwaves gradually turning the flow aloft to the W-NW late in the weekend and beyond. It looks like a slow process, so temperatures likely stay above normal through Sunday 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.

AVIATION /18Z MONDAY THROUGH SATURDAY/

As of 125 PM EDT Monday... Fairly widespread low-level cloud cover is noted on visible satellite imagery this afternoon. However, gradual clearing is expected through the afternoon with most locations improving to VFR, though ECG could stay MVFR. Skies trending toward SKC tonight, but will need to watch for patchy fog development inland. Some model guidance is also hinting at low- end MVFR or even IFR CIGs in the vicinity of ECG late this evening into tonight. VFR areawide after 12/13z Tuesday. 5-10 kt E-NE winds this afternoon become 5 kt or less 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 Monday...

Key Messages:

- Benign marine conditions are expected to prevail through much of the week.

- Moderate Rip Risk for all beaches through this evening, and for VA Beach/Eastern Currituck tomorrow.

Northeast winds around 10-15 kt prevail across the waters this afternoon with weak low pressure off the Carolina coast and weak high pressure to our north. Seas have built to 3-4 ft in response to the slightly elevated NE winds. Winds diminish by a few knots tonight (especially north) as the weak sfc high builds toward the waters. Could see seas build a bit more south of Cape Henry as NE winds of 10-15 kt will persist through the night. Not expecting seas to hit SCA criteria nearshore...though expect to see 5 ft seas offshore (20-60 NM). Winds diminish to ~10 kt tomorrow and veer to the E then SE during the aftn/evening. Winds become S-SW on Wednesday. Looking ahead, sub-SCA conditions prevail through the remainder of the work week with S-SW winds between 10-15 kt and seas of 2-3 ft nearshore.

Rip Currents: Continued with the moderate rip current risk for all beaches through this evening due to onshore flow and 9-10 sec periods. For Tuesday, a low rip risk are forecasted for the northern beaches with a moderate risk for VA Beach/Eastern Currituck due to onshore flow and waves around 3 ft. By Wednesday, a low rip risk returns for all beaches.

CLIMATE

Record Highs later next 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 next 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...None. NC...None. VA...None. MARINE...None.