textproduct: Wakefield

WHAT HAS CHANGED

Updated aviation discussion.

KEY MESSAGES

1) Slow-moving front passes through today bringing storm chances to portions of the area.

2) Looking more unsettled and potentially cooler next week as low pressure develops.

DISCUSSION

As of 300 AM EDT Friday...

KEY MESSAGE 1...Slow-moving front passes through today bringing storm chances to portions of the area.

Early morning radar shows a few light showers persisting across the Northern Neck, Middle Peninsula, and Eastern Shore. They should dissipate and move offshore in the next hour or two, but don't be surprised if you get a few spits of rain if you're in these locations this morning. Surface analysis currently has a cold front draped across the Northeast down across the Ohio River Valley and into the eastern Plains. This front is expected to continue slowly dropping south across our local area through the day today. Since this front will take most, if not the whole day to pass through, raised high temperatures a couple of degrees for most everyone. The forecast now has highs topping out in the mid 80s across the far north with upper 80s to 90 degrees for the I-64 corridor and south into NE NC. Dewpoints will be in the lower 70s, so it will feel a bit sticky outside with heat indices in the lower to mid 90s across the south. Dewpoints will try to drop into the 60s for northern locations overnight as high pressure briefly extends down from southeastern Canada, allowing for low temperatures to bottom out in the mid 60s. Upper 60s are expected across central and southern localities, with 70s along the coast.

With the front over VA today, it will be a moister airmass in place. PWATS are currently rising to over 2" as of this writing and could reach 2.25" across the S/SE this afternoon. Scattered showers and storms are forecast to develop this afternoon into the evening hours. Hi-res guidance continues to focus on our southwestern counties (Prince Edward, Lunenburg, Mecklenburg, etc) having the better chance at storms. SPC has nudged a Marginal Risk for severe weather up against southwestern Mecklenburg County. While the threat looks fairly low due to shear and CAPE values being unimpressive, can't totally rule out an isolated strong wind gust if storms are able to become organized. With the front not expected to totally clear our forecast area, there could be some lingering showers and storms into the late evening and early overnight hours.

KEY MESSAGE 2...Looking more unsettled and potentially cooler next week as low pressure develops.

The aforementioned cold front will drop south of our area into NC/SC on Saturday. Broad surface high pressure will move east across southeastern Canada and New England before sliding offshore Sunday morning. This will allow for a mostly benign mid-September Saturday with high temperatures in the upper 70s to around 80 degrees for western locations and the Eastern Shore, with lower 80s for eastern VA and northeast NC. Northeasterly winds could become a bit breezy for eastern and coastal locations. This east/northeasterly surface flow will also keep cloud cover overhead through the day. Can't totally rule out an isolated shower, but chances are on the low end. Winds will turn more southerly on Wednesday allowing for warmer air to return. Highs will be in the mid to upper 80s. Could start to see some rain chances push back into northern counties late in the day as shortwaves ride along the flow.

A more unsettled pattern sets its eyes on the eastern US for the new work week. At the surface, a large ridge of high pressure will set up over eastern Canada and into New England. This will keep persistent onshore flow going, resulting in continuing rain chances each day. If this comes to fruition, Monday may be our last day with widespread temperatures in the 80s for the forecast period. By late Tuesday into Wednesday, models agree that low pressure will develop aloft in the Great Lakes Region before potentially churning down into the northern Mid-Atlantic. Meanwhile at the surface, we could be dealing with a coastal low pressure developing offshore as well. This would create windy conditions across our marine and coastal locations, possibly for multiple days. Coastal flooding will also be something to watch by mid-week thanks to the elevated consistent onshore flow. WPC has added a Slight Risk of Excessive Rainfall for southern/southeastern portions of the area both Monday and Tuesday as moisture will be in abundance and there won't be much flow to make things move much. WPC is also leaning hard on a cold air damming situation keeping high temperatures in the 60s Wednesday (70s near the coast), but think that may be a bit too low for the current time of year. Regardless, there's agreement that temperatures will likely drop below normal for mid to late week with rain chances sticking around.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

As of 630 AM EDT Friday...

VFR conditions prevail across the terminals for much of the 12z/18 TAF period. A frontal boundary crosses the area today, shifting winds from SSW to N/NE by mid morning. SCT-BKN cumulus is expected to develop across the terminals by late morning and persist through the afternoon. This should mainly be VFR, though brief high-end MVFR CIGs are possible. Rain chances are generally under 20% for the terminals, as much of the SHRA/TSRA activity associated with the front will remain confined to the SW of the terminals. May have some SHRA linger into the overnight as well.

Outlook: VFR conditions are expected to prevail through the weekend, though periodic MVFR CIGs are possible with the onshore flow. Another cold front slowly crosses the region Monday into Tuesday as high pressure builds across northern New England and Atlantic Canada. This will bring more unsettled conditions with degraded flight conditions through at least mid-week.

MARINE

As of 300 AM EDT Friday..

Key Messages:

- Mainly sub-SCA conditions are forecast through the weekend, though a period of low-end SCAs due to 5 foot seas is possible from Saturday-Saturday night across the SE VA/NE NC coastal waters. Elevated NE to E winds prevail later today through Saturday night in the wake of a cold front.

- Decent model consensus that strong high pressure becomes locked in place across eastern Canada/northern New England next week, bringing several days of onshore flow and the potential for strong SCAs or Gales. SCA level winds are forecast by Monday night/Tuesday, with the highest winds likely occurring between Tuesday night and Thursday. A cold front is approaching from the north early this morning, with SW winds around 10 kt over the waters. The front is progged to cross the waters later this morning, with winds becoming N-NE at 10-15 kt by late today in the wake of the front. A slightly stronger push of CAA arrives tonight/Sat, which will allow wind speeds to increase to ~15 kt with gusts to 20 kt as the wind direction gradually veers from the NE tonight to ENE on Saturday. Winds become southerly later Saturday night into Sunday and decrease to 10-15 kt. While wind speeds are expected to remain just below SCA criteria through the weekend, the onshore flow will likely allow seas to build to ~5 ft by Saturday (especially S of Cape Charles), with 4-5 ft seas persisting through Sat night. Will continue to monitor, but it appears that SCAs may be needed for the SE VA/NE NC coastal waters and perhaps the mouth of the bay (for 3-4 ft waves).

By late Monday or Tuesday, winds become NE again as strong sfc high pressure builds across eastern Canada (normalized anomalies are >2 std dev for the sfc high). The stronger CAA likely holds off until Wednesday/Thursday as low pressure potentially deepens off the Mid- Atlantic or SE coast. SCA level winds are expected by Tuesday, with a greater increase in NE winds by Tue night/Wed (and continuing through Thu) due to the combination of stronger CAA and a tightening pressure gradient between the high to our north and deepening low pressure to our SE. While this is still several days out and there is some degree of uncertainity with respect to the exact position of synoptic features, there is quite strong consensus amongst the Euro, GFS, and Canadian ensembles in the general pattern. At least strong SCAs appear probable from Tuesday night-Thursday, with a decent chance of frequent gale force gusts, so we will continue to monitor the trends as this gets closer in time.

The rip current risk will be low today, with a Moderate risk for Saturday and Sunday as the flow becomes onshore once again. Hazardous surf conditions are likely next week with the prolonged onshore flow.

AKQ WATCHES/WARNINGS/ADVISORIES

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