textproduct: Wakefield

WHAT HAS CHANGED

Enhanced risk for severe storms introduced for the Northern Neck and lower MD Eastern Shore this afternoon and evening

KEY MESSAGES

1) A dangerous heat wave continues through this weekend. Peak heat indices today will again approach or exceed 110 degrees.

2) Severe storms may produce widespread damaging winds this afternoon and evening, particularly from the Richmond metro northeastward into the Northern Neck and lower Maryland Eastern Shore. An Enhanced (level 3 out 5) severe storm risk has been introduced for these areas with a Slight or Marginal risk elsewhere. Additional strong-severe storms are possible Sunday and Monday.

3) Temperatures gradually trend closer to normal by early next week, with the potential for unsettled weather.

DISCUSSION

As of 245 AM EDT Saturday...

KEY MESSAGE 1...A dangerous heat wave continues through this weekend. Peak heat indices today will again approach or exceed 110 degrees.

An anomalously strong ~594 dm ridge is centered over the NC Coastal Plain this morning. This will keep the very hot wx in place for the Fourth of July holiday. However, as the ridge gradually breaks down, the chance for thunderstorms will return to the forecast. Don't expect these storms to have much impact on the peak heat indices today as strong heating of an already moist airmass (dew points this morning in the mid-upper 70s) will allow temps and heat indices to quickly surge once the sun rises this morning. Our current forecast has widespread heat indices of 108+ deg F by 11 AM, well before any storms would form. The core of the heat (and the highest heat indices) will be similarly placed to yesterday, generally from central VA eastward into the Tidewater and Chesapeake Bay vicinity. These areas are likely to see high temperatures around 100 degrees and dew points in the 70s, yielding heat indices of 110-114 F. Extreme Heat Warnings remain unchanged and are in effect for our entire CWA, minus the NC and MD beaches where Heat Advisories are in effect. If storms/outflow push through the area later this afternoon and evening, welcome relief from the heat would occur. Therefore, all headlines are progged to expire at 8 PM this evening.

The ridge will shift southward and break down further Sunday. Regardless, we are still likely to see continued hot temperatures, albeit a few degrees cooler than the previous days. Highs generally in the mid-upper 90s range, potentially nearing 100 F in the urban Richmond corridor. Peak heat indices will tend to fall shy of 110 F so do not currently anticipate additional warnings for Sunday. Heat Advisories are likely for most, if not all, of the forecast area, however. Additional showers/storms could also provide relief by the evening. A few degrees cooler again on Monday with highs "only" in the lower 90s. Additional heat headlines are possible in NE NC but relatively widespread cloud cover and afternoon convection should preclude widespread 105+ heat indices and advisories for our VA and MD counties.

KEY MESSAGE 2...Severe storms may produce widespread damaging winds this afternoon and evening, particularly from the Richmond metro northeastward into the Northern Neck and lower Maryland Eastern Shore. An Enhanced (level 3 out 5) severe storm risk has been introduced for these areas with a Slight or Marginal risk elsewhere. Additional strong-severe storms are possible Sunday and Monday.

As the ridge slowly breaks down today, there will likely be just enough forcing/ascent to support more widespread thunderstorm development later this afternoon. Storms will be favored to initiate in the vicinity of the lee trough in the afternoon and move east or northeast into the evening hours, including (likely) through portions of our CWA. There remains lingering questions on coverage and how exactly the storms will evolve and this is reflected in the varied solutions among the near- term CAMs. Regardless of the specifics, very strong instability will be in place for any storm to utilize with with SBCAPE in excess of 3000 J/kg. Additionally, mid-level lapse rates will be unusually steep (> 7 C/km), supportive of robust/intense updrafts. The degree of the wind threat will be dependent on potential clustering/upscale growth and cold pool development. Should a robust cold pool develop, significant/widespread damaging winds are on the table given a very favorable near- surface thermodynamic environment with DCAPE in excess of 1500 J/kg and steep low-level rates. There could also be some higher-end severe gusts in excess of 70 mph. The best potential for this enhanced damaging wind threat would be north and especially northeast of the Richmond metro, especially on the Northern Neck and into the lower MD Eastern Shore. This is where an Enhanced (level 3/5) risk has been introduced by the Storm Prediction Center, driven by a 45% wind probability. While coverage will be tend lower with southward extent (where Slight and Marginal Risks are delineated), the aforementioned environment is supportive of severe wx areawide. Unfortunately, these storms have the potential to interfere with afternoon/evening festivities associated with the Fourth of July and users should closely monitor the evolving weather today, have backup plans in place, and have multiple ways to receive warnings. As is typical in any summer storm, frequent lightning and heavy rain are also expected in storms today- tonight.

Additional threats of strong-severe storms are on the table both Sunday and Monday, with higher confidence in more widespread coverage Monday as a shortwave trough approaches the area. Damaging wind gusts, heavy rainfall, and frequent lightning will be the primary storms threats. SPC has a slight risk across the N Sunday.

KEY MESSAGE 3...Temperatures gradually trend closer to normal by early next week, with the potential for unsettled weather.

The ridge becomes shunted to our south beyond Monday, with the upper- level flow turning quasi-zonal. This pattern is very typical for the middle of summer with daily chances for showers and storms expected in the midst of surface troughing and weak disturbances passing through aloft. Temperatures will also trend back toward seasonal norms for most of next week, generally in the lower 90s.

AVIATION /09Z SATURDAY THROUGH WEDNESDAY/

As of 545 AM EDT Saturday... Flight conditions will generally be VFR through the Fourth of July. Sunny/mostly sunny skies are expected this morning into the first part of the afternoon, with just FEW-SCT CU developing during peak heating. By later this afternoon, tstm chances increase, especially north of RIC-SBY line. Given the hot and humid airmass, strong-severe gusts, frequent lightning, heavy rain, and VSBY reductions are possible in storms. The best potential (30-40% chance) is after 20z at RIC and after 23z at SBY. Will continue to handle with PROB30 groups for the time being. Mainly dry conditions expected for PHF, ORF, and ECG. Winds today avg 5-10 kt out of S-SW, though ORF may become E-NE this afternoon.

Outlook: Outside of continuing chances for showers/storms and localized flight restrictions, VFR prevails through the weekend into early next week.

MARINE

As of 245 AM EDT Saturday...

Key Messages:

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

- Elevated wind gusts from strong thunderstorms are possible during afternoon and evening hours today and Sunday.

High pressure continues to extend from the Southeast to off the Mid- Atlantic coast early this morning. The wind is generally SW 5-10kt and ~10kt offshore. Seas are ~2ft with ~1ft waves in the Ches. Bay. High pressure remains in vicinity of the Southeast coast through at least early next week allowing for continued, mainly light, southerly flow. Some diurnal wind speed and direction variability is likely to prevail for the next few days (mainly S-SW overnight into the morning, becoming S-SE in the late aftn/evening with a slight increase in speed). Isolated to widely scattered tstms this weekend into early next week would be the only thing that would lead to brief higher winds and waves, with strong tstm wind gusts possible today and Sunday, primarily from mid-aftn through early evening. Any stronger wind gusts will be handled with SMWs. Seas will be ~2ft through the weekend, with 1ft to occasionally 1-2ft waves in the Ches. Bay. A very weak cold front may settle into the Carolinas by the middle of next week, but sub-SCA conditions are expected to continue.

CLIMATE

Record Highs:

Salisbury, MD (SBY) set a new record high yesterday (7/3) of 101, breaking the old record of 98 from 1954. A new record high minimum temp of 77 was also set, breaking the old record of 76 from 2014.

Norfolk, VA (ORF) tied the record high yesterday (7/3) of 99, which was set in 1954.

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

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

Record High Mins:

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

- RIC: 77/2014 77/1900 79/2012 - ORF: 78/2014 79/2012 80/1999 - SBY: 76/2014 78/2012 81/2012 - ECG: 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 until 8 PM EDT this evening for MDZ021>024. Heat Advisory until 8 PM EDT this evening for MDZ025. NC...Extreme Heat Warning until 8 PM EDT this evening for NCZ012>017-030>032. Heat Advisory until 8 PM EDT this evening for NCZ102. VA...Extreme Heat Warning until 8 PM EDT this evening for VAZ048- 060>062-064>069-075>090-092-097>100-509>525-528>531. MARINE...None.