textproduct: Wakefield

WHAT HAS CHANGED

No significant changes to the forecast today.

Trended temperatures lower for Sunday.

KEY MESSAGES

1) Showers and storms increase in coverage this afternoon and especially this evening, pushing eastward to the coast tonight into early Sunday morning. Low pressure offshore then allows for cool and dreary conditions Sunday, with lingering rain along the coast. Drying out and becoming milder Monday.

2) There are several opportunities for (mainly light) rainfall next week with near average temperatures in the 70s.

DISCUSSION

As of 255 AM EDT Saturday...

KEY MESSAGE 1...Showers and storms increase in coverage this afternoon and especially this evening, pushing eastward to the coast tonight into early Sunday morning. Low pressure offshore then allows for cool and dreary conditions Sunday, with lingering rain along the coast. Drying out and becoming milder Monday.

The backdoor cold front which sparked scattered showers and storms yesterday has wavered a bit back N this morning. Observations place it roughly along the I-64 corridor or perhaps a bit SW. Regardless, outside of very isolated sprinkles in the Piedmont, most of the area is dry and mild under a variably cloudy sky.

The front will remain relatively stationary for the morning and afternoon hours today. Temperatures could be a challenge today as there will likely be a large range with this front in place. The Eastern Shore looks to stay in the upper 50s-mid 60s, with very warm temps (well into the 80s) developing W of the Chesapeake Bay. By the mid-late afternoon, there is high confidence in showers and storms moving in from the W as a wave of low pressure rides SE along the front, with a stronger cold front serving to advance the precip eastward to the coast by this evening into tonight. Several of the hi-res models also show some activity initiating off the front itself this afternoon as a weak shortwave and pressure falls overspread the area. In terms of the thunderstorm potential, instability (overall) is quite meager given meager lapse rates aloft and rather poor sfc moisture quality. However, similar to yesterday, most models show locally enhanced dew points and instability in the vicinity of the lingering stationary front this afternoon, which is progged to reside in the vicinity of the I-64 corridor. Based on a few model soundings, the best storm potential is roughly from Williamsburg northwestward into RIC and our wrn/NW Piedmont counties, on the warm side of the boundary. One more thing to watch for will be locally enhanced low-level shear with the front in place and the approaching low feature. While highly conditional, some CAMs are hinting at a supercell or two trying to ride the boundary E and SE. If this were to materialize, there would be an isolated damaging wind and/or large hail threat. The tornado threat appears very low due to the high-based nature of the convection. Again, this is very conditional and would be confined to a small area. SPC has no svr wx threat highlights for our area at this time. Showers move eastward to the coast this evening and tonight, with the storm threat diminishing with the loss of heating. Aerial QPF should average around a half inch or so though locally higher amounts of 1"+ are possible in areas that see several rounds of convective activity. While beneficial, this is unlikely to make a meaningful dent in the ongoing drought conditions.

The front and low pressure system move offshore Sunday. However, the sfc low will slow down and modestly deepen as a cutoff low develops aloft. This will allow sfc high pressure to reinforce and strengthen to our N. Therefore, expect a cool, dreary, and potentially wet day Sunday with a cold air damming setup. The highest PoPs are along the coast of SE VA and NE NC. A tightened pressure gradient will also allow for breezy conditions along the immediate coat. Have significantly undercut the NBM (which struggles in CAD) and trended temperatures lower. Depending on the exact configuration of the sfc pattern, particularly where the low resides, Monday could also end up being cooler and cloudier than shown in the forecast. This bears watching though most guidance is at least a few degrees warmer. The best shot for sunshine and warmth would be well inland and especially W of I-95.

KEY MESSAGE 2...There are several opportunities for (mainly light) rainfall next week with near average temperatures in the 70s.

Troughing may develop over most of the CONUS by the middle the later half of next week, with several fronts and disturbances potentially passing through the region. The latest CPC outlook favors slightly above average rainfall in the 6-10 day period. 12z operational and ensemble guidance shows another round of mainly light precip on Tuesday with a potentially more substantial slug of moisture expected late Wednesday. Specifics beyond this time are uncertain but chance PoPs are in place through most of the week. Temperatures generally hover around average for mid-late Spring with variable cloudiness.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

As of 630 AM EDT Saturday...

VFR and variable mid-level cloudiness to start off the 12z TAF period. While VFR should continue at most terminals through this morning and afternoon, MVFR CIGs are likely to develop over the next few hours at SBY and persist through most of the day. In terms of rain chances, expect dry conditions through at least the early afternoon. Low pressure then approaches from the west this afternoon and evening, bringing increasing chances of showers and embedded tstms from W to E. While svr wx is generally not expected, a few storms could produce frequent lightning, gusty winds, and reduced VSBY. Most of the widespread rainfall holds off until after 00z for the coastal terminals. Winds average E to ESE ~10 knots through a majority of the forecast period, becoming gusty to 20-25 kt at SBY this afternoon. Widespread low-end MVFR or IFR restrictions (mainly due to CIGs) are expected after 00z at SBY and after ~08z at RIC, ORF, PHF, and ECG.

Outlook: MVFR to IFR CIGs linger through most of the day Sunday due to moist, onshore flow. Model trends have been for lingering clouds near the coast Monday, which could lead to continued flight restrictions. Inland locations should dry out with primarily VFR.

MARINE

As of 400 AM EDT Saturday...

Key Messages:

- Small Craft Advisories have been issued for this afternoon for the Chesapeake Bay north of New Point Comfort and the Coastal Waters north of Cape Charles. Easterly winds increase to around 20 kt this afternoon ahead of developing low pressure and its associated cold front.

- Solid SCA conditions expected late tonight through Monday evening, as low pressure deepens offshore. Gusts to Gale Force will be possible over the coastal waters Sunday into Sunday night. Gale Watches have been issued for all coastal waters north of the VA-NC border from Sunday morning through Sunday evening.

- Nuisance to low-end minor coastal flooding is possible for communities along the lower Chesapeake Bay and tidal VA Rivers. Up to 1 foot of inundation above ground level is possible.

Latest analysis reveals a backdoor cold front which has meandered back north into the local area. As of this writing, the front was extending NW from the NE NC coast to the lower Bay and farther NW of the local waters back into the eastern Great Lakes. On the cool side of the boundary, E-SE winds of 10-15 kt prevail over most of the waters, albeit with stronger winds at elevated terminals that are more effectively tapping into the stronger momentum transfer within the onshore flow regime. On the warm side of the boundary, SSE flow is noted across the far southern waters, with speeds closer to 5-10 kt.

Developing low pressure over the interior northeast will dive SE toward the local area later today, with the attending, trailing cold front crossing the local waters late tonight. Tightening pressure gradient will serve to allow onshore (E-SE) flow to increase to ~20 kt with gusts to 25 kt over the coastal waters N of Cape Charles during the day. The highest winds will be over the MD coastal waters. In addition to the Small Craft Advisory for the Atlantic coastal waters north of Cape Charles, have added an SCA for the Ches Bay north of New Point Comfort for this afternoon and tonight. Here, E-SE winds increase to 15 to 20 kt, with gusts to ~25 kt. Farther south, winds veer around to the SSW over the lower bay and southern coastal waters late this afternoon and this evening, in response to the low pressure system diving SW of the local waters.

Overall timing has slowed slightly regarding the low pressure system as it deepens and pushes offshore of the VA Capes and Delmarva coast on Sunday. This will allow the front to drop SE offshore of the local waters, with the resultant compressing pressure gradient/strong isallobaric forcing quickly ramping up N-NE winds and gusts to 20-25 kt with gusts to 30 kt by mid to late morning on Sunday. High-resolution CAMs continue to show a period of 25-30 kt winds possible over the coastal waters (w/ gusts to 35-40 kt highest offshore) from Sunday morning (far north) through the first part of Sunday night. Occasional gale force gusts are possible on the bay (especially near the mouth of the bay) during this time. Local wind probabilities for Gale Force Gusts (34 kt+) have dropped slightly and have also trended a bit later in time, owing to the slower frontal progression. At this time, Gale force gust (34kt) probabilities are roughly 40-70% across the Atlantic coastal waters N of the VA-NC border, highest toward the outer portion of the nearshore zones and in the 20-60NM offshore waters. Given the trends, not confident enough to add Gale Warnings at this time. Therefore, in collaboration with neighboring offices, have maintained Gale Watches for now for all ocean zones out to 60nm from Sunday morning-late Sunday evening for these zones (not including NE NC) and pushed start of Gale Watch to Sunday afternoon and evening south of Parramore Island. Have filled in SCA over the rest of the Chesapeake Bay, E VA rivers, and Currituck Sound starting Sunday morning, and maintained the ramp up SCA for ANZ654. Winds diminish a few knots Sun night-Mon as the low pulls farther offshore. Have only issued SCA through Sunday night for now, but solid SCA conditions with N-NE winds appear likely to persist through Monday aftn/early evening for all waters. Sub-SCA winds finally return on Tuesday.

Seas currently 2-3 ft will build to 3-4 ft S/5-6 ft N this afternoon, before building to 8-14 ft (highest 60NM offshore) by late Sunday. Waves on the bay currently 1-2 ft, but gradually build to 3-6 ft (highest at the mouth) by late Sunday. Seas slowly diminish early next week, but 5 ft seas could persist nearshore through midweek. High Surf Advisories are also quite likely to be needed Sunday and Monday.

Regarding the coastal flood potential, tidal anomalies of 0.5 to 1 ft above normal steadily increase late Sunday and Monday, owing to strong high pressure building to the north and deepening low pressure exiting NE offshore of the Delmarva. The compressing pressure gradient will bring an increasingly strong NNE flow Sunday afternoon into Monday morning wave action/increasing seas (due to both wind waves and swell). Tidal sites in the lower Chesapeake Bay, lower James River will have the best chance for minor tidal flooding impacts with the Sunday night/early Monday morning high tide cycle, with tides remaining elevated into early Tuesday. At Sewells Point, the 50th percentile value per ETSS for the Sun evening tide (4.3ft MLLW) is into action stage and near/just below minor flood, with the 90th percentile value (4.5ft MLLW) at low-end Minor. A similar story at Lynnhaven (4.3ft 50th percentile, 4.6ft 90th), with the latest forecast coming in just below minor thresholds. Will continue to monitor trends over the next 12-24 hours. It is certainly possible that a localized round or two of coastal flood Advisories could be needed for areas in the lower bay/tidal James Sunday afternoon/evening.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 1 PM this afternoon to 6 AM EDT Monday for ANZ630-631. Small Craft Advisory from 6 AM Sunday to 6 AM EDT Monday for ANZ632-634>637-639. Small Craft Advisory from 10 AM Sunday to 6 AM EDT Monday for ANZ633. Small Craft Advisory from 10 AM this morning to 7 AM EDT Sunday for ANZ650-652. Gale Watch from Sunday morning through Sunday evening for ANZ650-652-680-682. Small Craft Advisory from 1 PM this afternoon to noon EDT Sunday for ANZ654. Gale Watch from Sunday afternoon through Sunday evening for ANZ654-656-684-686.