textproduct: Wakefield

WHAT HAS CHANGED

Updated Discussion, including 06z TAFS.

Have lowered high temperatures again through Friday due to areas of smoke from Canadian wildfires that will remain across the area.

KEY MESSAGES

1) While very warm/hot conditions prevail, waves of smoke from Canadian wildfires will push into the area, and will likely suppress daytime high temperatures through Friday.

2) Thunderstorm chances increase this weekend, bringing the potential for locally heavy rain, along with very warm and humid conditions persisting into early next week.

DISCUSSION

As of 305 AM EDT Thursday...

KEY MESSAGE 1...While very warm/hot conditions prevail, waves of smoke from Canadian wildfires will push into the area, and will likely suppress daytime high temperatures through Friday.

Waves of dense smoke aloft emanating from wildfires over west- central Ontario will get funneled south toward the area once again today. Manually added "haze" wording to the gridded database encompassing all zones today, following closely with the HRRR-Smoke and RRFS vertically integrated smoke forecasts, which have been handling current conditions well.

As we saw yesterday, a hazy, milky sky from vertically integrated smoke can cause quite a reduction in afternoon temperatures. Because the NBM and MOS don't ingest real-time wildfire data, they treat the column as completely clear, creating a substantial warm bias. The rest of the 00z guidance displays a highly bimodal spread for max temperatures, ranging from the upper 80s to low 90s in the HRRR-Smoke/RRFS suites to near 100F in the GFS/ECMWF. We are leaning heavily on the HRRR- Smoke and RRFS for this package, which are some of the few members within the guidance envelope to explicitly model smoke. The latest guidance from these models vertically integrated smoke fields shows another dense concentration of smoke aloft today. Have therefore played up the haze and smoky overcast. Weaker vertical mixing under the thick smoke plume aloft will cap temperatures a bit more while also keeping dewpoints higher. As a result, high temperatures have been lowered a few degrees on average from the previous forecast, running a good 4-5 degrees below the NBM/MOS. Meanwhile, dewpoints have been increased toward the high end of the guidance envelope today. Highs will generally cap in the low-to-mid 90s, with heat indices staying right around 100F. Additionally, Air Quality Alerts are in effect for the Richmond Metro, Hampton Roads, and the Lower Maryland Eastern Shore for today.

Some CAMs show weak convection developing to our north along the weakening cold front and potentially reaching the MD Eastern Shore counties before weakening. While this remains a low- probability scenario, a 20% PoP still seems reasonable and has been maintained.

On Friday, we should see a higher concentration of both vertically-integrated and sfc-based smoke filtering into much of the CWA. This should result in more haze and at least some visibility restrictions in smoke and quite possibly even lower air quality. More Air Quality Alerts appear possible, and we will continue to monitor this potential. Due to this, have manually lowered high temperatures for Friday by several degrees. Somewhat lower dewpoints look to filter in from the north, keeping heat indices below 100F for much of the region. The exception could be across NE NC, where we could still see heat indices up to 105F if the smoke remains farther north, or at least comes in later in the day as presently modeled. Additional isolated showers and storms firing along the piedmont trough and riding along the weakening ridge could conceivably make it into the area before weakening, but chances are again very low. Kept PoPs at 20%.

KEY MESSAGE 2...Thunderstorm chances increase this weekend, bringing the potential for locally heavy rain, along with very warm and humid conditions persisting into early next week.

The upper level ridge continues to gradually break down over the weekend, as upper troughing re-establishes itself over the northern Mid-Atlantic and northeast CONUS. As low pressure tracks from the eastern Great Lakes into New England, it will send its attendant cold front south toward the local area this weekend. Ahead of the front, a series of shortwaves will track across the area from Saturday through Monday. As is typically the case this time of year, it now seems likely that the slowing/weakening front will become hung up and linger across our area into Monday.

While considerable uncertainty remains regarding the exact timing and coverage of storms, the upper flow turning WNW-NW over a hot, increasingly humid, and moisture-pooled boundary layer (PWs increasing AOA 2") will set up a climatologically favored pattern for locally heavy rainfall and downbursts. Moisture pooling along the slow-moving boundary beneath steep mid-level lapse rates will favor a hot, muggy, high-DCAPE setup capable of producing isolated to scattered damaging wind gusts and potentially some instances of flash flooding in urban or flood prone areas each day this weekend, with this activity potentially lingering into Monday. Deep-layer shear is respectable just ahead of the front in the 25-35 kt range for Saturday. This could support some convective line segments, again depending on the timing of the upper support. It is likely that due to weakening shear, the main threat later in the weekend would be heavy rainfall along the sagging/weakening frontal boundary, and Hampton Roads has been included with a Marginal Risk in the latest Day 4 ERO from WPC.

High temperatures trend a bit cooler with the increasing PWs and cloud cover. However, with that comes higher dewpoints. This appears especially likely across SE VA and NE NC, where max heat indices will likely linger near 105 F through Sunday, if not Monday.

AVIATION /12Z THURSDAY THROUGH MONDAY/

As of 625 AM EDT Thursday...

Mainly VFR conditions prevail across all terminals through the 12z TAF period with smoke from Canadian wildfires remaining aloft (~25 k ft). Winds will generally be light from the S-SW. There is some potential for reduced VSBYs in near sfc smoke mainly at SBY and perhaps RIC later this morning and this afternoon. There is also a slight chc for evening tstms at SBY toward the end of the TAF period, but chances remain low enough to hold out mention for now. Elsewhere, all terminals could potentially see reduced VSBYs in near sfc smoke by Friday.

Outlook: Higher chances for SHRA/TSRA are expected Sat aftn/evening and again Sunday.

MARINE

As of 240 AM EDT Thursday...

- Sub-Small Craft Advisory marine conditions persist through Saturday. Southerly flow becomes E-NE 10-15 kt behind a weak boundary Friday.

- Potential for marginal Small Craft Advisory conditions in elevated southerly flow Saturday night into Sunday.

Sub-SCA conditions will continue as high pressure is located near the area through Saturday. Winds are currently W-SW 10-15 kt early this morning. There will be a slight relax late morning and afternoon before winds increase again overnight to 10-15 kt out of the SW. A weak boundary will cross the area late Thursday night/early Friday morning, shifting winds out of the E-NE at 10-15 kt on Friday. Gusts to 20 kt are possible for the coastal waters north of Cape Charles with this boundary, but conditions look to remain sub-SCA for all waters.

Confidence is rising in southerly flow increasing Saturday night into Sunday morning ahead of the next frontal system. The local wind probs shows a 90% chance of gusts to 18 kt across all waters and a 60-70% chance of gusts to 25 kt across the coastal waters (30% chance for the lower Ches. Bay). Waves and seas will remain ~1 ft and ~2 ft, respectively. A brief increase to 3+ ft seas is possible Friday with the NE winds, with a further increase to 3-5 ft with the S winds on Saturday/Sunday.

There is a low risk of rip currents across all beaches today and Friday. Depending on the strength of the NE winds Friday (and the resultant seas and nearshore waves), a moderate rip could eventually be required.

CLIMATE

As of 420 AM EDT Thursday...

- Record Highs:

- Today 7/16 Fri 7/17

- RIC: 101 (1980) 100 (1980) - ORF: 102 (1879) 100 (1887) - SBY: 99 (1915) 99 (2012) - ECG: 98 (1995) 99 (1942)

- Record High Mins:

- Today 7/16 Fri 7/17

- RIC: 77 (1983) 77 (2025) - ORF: 80 (1995) 80 (2024) - SBY: 78 (2024) 80 (1983) - ECG: 79 (2012) 80 (2019)

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...None.