textproduct: Wakefield

WHAT HAS CHANGED

Confidence has increased in severe weather this afternoon.

KEY MESSAGES

1) Scattered showers and storms are expected today into tonight. Storms may be strong to severe with damaging wind gusts, locally heavy rainfall, and isolated large hail possible.

2) Cooler temperatures are expected early next week with a brief warmup by midweek.

DISCUSSION

As of 425 AM EDT Saturday...

KEY MESSAGE 1...Scattered showers and storms are expected today into tonight. Storms may be strong to severe with damaging wind gusts, locally heavy rainfall, and isolated large hail possible.

Aloft, the ridge remains in place across the central CONUS with a trough across coastal New England gradually pushing west towards the local area today. This will allow for the amplified belt of NW/NNW flow aloft to remain centered from Ohio into VA and NC. Similar to yesterday, this will place a large portion of the local area under a favorable corridor for storms. At the surface, a cold front was located north of the local area and will gradually move south through the day. The most notable change from yesterday has been that the FROPA looks to be slower. WPC places the cold front from central VA into SE VA this afternoon with the front lingering across a portion of the local area into the evening before eventually moving south into NC. Given the slower FROPA, the warm sector will likely remain across at least the SW half of the area and could extend even farther NE. The 00z CAMs were in general agreement that storms currently across the southern Great Lakes into Ohio will become an MCS and follow the NW flow aloft towards the Appalachians by late morning. There are two main scenarios afterwards. The first possibility is that the MCS holds together as it crosses the mountains and restrengthens east of the mountains as a line of storms with straight-line winds moving across the local area. The second option is that the MCS breaks apart once it reaches the mountains and the remnant vorticity helps a combination of supercells and multicells form across the local area this afternoon. These storms would be capable of both damaging winds and large hail. In either case, confidence has increased in severe storms today across much of the area. The most likely timeframe for severe weather looks to be 2-10 PM. However, some CAMs have convection as early as 10 AM with others showing some severe potential lingering into the evening. The severe potential tapers off overnight, however, scattered showers or storms will continue to be possible through the night across southern portions of the area.

Environmentally, HREF shows CAPE of 1000-2000 J/kg across the area with lower values across the Northern Neck and Eastern Shore. Meanwhile, shear of 35-45 kt overlaps the instability, creating a favorable balance for severe weather. Additionally, the general model consensus is for mid-level lapse rates of 6-6.5C this afternoon which adds confidence in severe weather. Given the increasingly favorable parameters for severe weather, SPC has expanded the slight risk (level 2/5) to now include the I-64 corridor and locations south. The marginal (level 1/5) risk has also been expanded and now includes the Northern Neck and Virginia Eastern Shore. Damaging winds are the primary hazard, however, given the favorable shear and mid-level lapse rates, large hail will also be possible if supercells are realized (as opposed to line segments). In fact, if a discrete supercell were to form, hail larger than 1 inch in diameter (potentially up to ping ball sized) isn't out of the question. The best chance for this is if a supercell is able to latch onto the cold front since the front could be oriented NW to SE which follows the NW flow aloft. Additionally, while tornadoes are unlikely given weak 0-1 km SRH, a tornado cannot be ruled out if a supercell is able to interact with the cold front given lower LCLs. Will note that the limiting factors for today's severe threat are the potential for lingering stability (CIN) from yesterday's convection and northerly surface winds. However, given a lack of cloud cover this morning, destabilization (and the erosion of any lingering CIN) appears likely.

Severe weather will not be the only potential hazard. WPC has also expanded the slight risk for excessive rainfall (ERO) today to include the I-64 corridor and locations to the south given the potential for heavy rain and localized flooding. Given the shear in place, individual showers/storms should be moving (as opposed to being stationary) which should help limit the flooding potential outside of training. However, heavy rain rates within storms and localized training of storms could allow for localized flooding, mainly across urban areas. Shower/storm chances decrease Sun (15-40% PoPs) with most convection likely confined to the far southern portions of the area (or remaining south altogether). Beyond Sun, dry conditions are expected early next week, potentially continuing into midweek.

KEY MESSAGE 2...Cooler temperatures are expected early next week with a brief warmup by midweek.

Highs today will be cooler than yesterday with highs in the mid 80s NE to low-mid 90s SW with most locations in the upper 80s to lower 90s. These cooler temps will allow for a heat indices in the mid 80s NE to around 100F SW. As such, while another hot day is expected across southern portions of the area, additional Heat Advisories do not appear to be warranted at this time. Behind the cold front, highs will be notably cooler Sun into Mon with highs in the low-mid 80s area-wide as cool high pressure builds in from the north. The ridge potentially builds back in (at least briefly) by the middle to later part of next week with highs back in the low-mid 90s possible by Thu. However, confidence is low at this time given a plethora of shortwaves between now and then.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

As of 705 AM EDT Saturday...

Mostly clear skies continue early this morning apart from patchy fog and low CIGs near RIC and locations north until around 13z. Cloud cover increases from NW to SE later this morning into this afternoon with ~5000 ft CIGs due to CU as an MCS approaches from the west. A mixture of SCT and BKN CU are then expected from this afternoon into tonight. Additionally, scattered showers and storms are expected to move into the area from early to late afternoon from NW to SE. Gusty winds and large hail are possible with stronger storms (along with VIS reductions). Storms taper off this evening. However, scattered showers will continue to be possible overnight. A cold front slowly crosses the area today into tonight. Behind the front and in the rain- cooled air, low stratus and fog will be possible tonight. IFR CIGs and or VIS will be possible. Otherwise, Winds remain N around 5-7 kt today, gradually becoming NE this afternoon into tonight behind the cold front. Winds become light and variable tonight.

Outlook: Mainly dry/VFR Sunday through Tuesday behind the front, though brief MVFR CIGs are possible near the coast with NE flow.

MARINE

As of 230 AM EDT Saturday...

Key Messages:

- Cold front pushes through today turning winds north/northeasterly. Evening thunderstorm chances continue with gusty winds possible.

- Northeasterly winds and seas will increase Sunday into Monday as high pressure builds in from the north.

West/northwesterly winds are breezy across the waters this morning with most sites reporting 10-15kt with gusts to 15-20kt. These winds will turn northerly and subside below 10kt after daybreak as a cold front pushes south across the area, then become east-northeasterly this afternoon. There will be another chance for thunderstorms later today with the threat of gusty erratic winds. Waves in the Bay are 1- 2ft with seas around 2ft persisting into Sunday morning.

A stronger push of CAA arrives by Sunday as high pressure builds in from the north. This will result in northeasterly winds becoming 15- 20kt during the day on Sunday and continuing into Monday. A few gusts to 25kt are possible across the southern waters. Seas will also build to 3-4ft across the north (up to 5ft offshore) and 4-5ft for the south (up to 6ft further offshore of NC). Waves in the mouth of the Bay will increase to 3-4ft as well Sunday night. Local wind probabilities have decreased, highlighting that the winds will be marginal in regards to needing a SCA - will keep an eye on trends for the lower Bay as they would be closest to wind thresholds. SCAs are more likely for the coastal waters off the NC coast for elevated seas.

There is a Low Rip Current Risk today for all beaches. Rip Risk becomes Moderate on Sunday as onshore winds and waves build, then High for southern beaches on Monday and Moderate persisting for the north.

AKQ WATCHES/WARNINGS/ADVISORIES

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