textproduct: Wakefield

WHAT HAS CHANGED

- Shower chances increased a bit W of the bay today. - Rainfall has trended later Saturday, likely persisting into Saturday night and Sunday morning. - Rainfall amounts have also trended higher (to 0.5-1", with locally higher amounts) Saturday-Sunday.

KEY MESSAGES

1) Widely scattered showers (and potentially a storm) develop this afternoon, especially east of I-95 and north of I-64. Otherwise, another very warm day is expected, especially west of the Chesapeake Bay.

2) Rain chances increase later Saturday into Saturday night as a cold front and wave of low pressure move into the region. Showers linger along the coast Sunday, along with cooler conditions for the entire area. Dry weather makes a comeback Monday.

3) There are several opportunities for rainfall next week as an unsettled pattern potentially develops.

DISCUSSION

As of 310 AM EDT Friday...

KEY MESSAGE 1...Widely scattered showers (and potentially a storm) develop this afternoon, especially east of I-95 and north of I-64. Otherwise, another very warm day is expected, especially west of the Chesapeake Bay.

Early morning analysis places a backdoor cold front just NE of the forecast area. Locally, temperatures are quite mild for April's standards, under a mostly clear sky and light south wind. The backdoor cold front will slowly drop S/SW today, first pushing through the Eastern Shore later this morning and then further inland by the afternoon. Ahead of the boundary, temperatures are likely to increase well into the 80s, before dropping later in the afternoon. Temperatures warm in the 70s on the Eastern Shore this morning and likely drop into the 60s by the afternoon.

Short-term convective-allowing models continue to depict widely scattered showers in the vicinity of the front this afternoon. This is where some moisture pooling and slightly higher dew points should reside. The highest coverage is currently favored along and just W of the Chesapeake Bay and especially in the sector bounded E of I-95, N of I-64, and W of the Chesapeake Bay. Here, PoPs are 30-40%. While instability is generally weak, forecast soundings do show a few hundred J/kg of MLCAPE (generally between 700-500 mb, just above the deep boundary layer) where those higher dew points likely reside. Thus, a rumble or two of thunder, small hail, and gusty winds could also occur. Severe wx, however, is not expected. Well inland, a very deeply-mixed boundary layer will develop with high- based cumulus around 8000-10000 ft. Therefore, think the showers shown in the CAMs in these areas (mainly from I-95 and points W) are likely overdone given the degree of dry air at the surface. Rainfall amounts will be very low for those lucky enough to see a shower or two, generally on the order of a trace to a few hundredths.

KEY MESSAGE 2...Rain chances increase later Saturday into Saturday night as a cold front and wave of low pressure move into the region. Showers linger along the coast Sunday, along with cooler conditions for the entire area. Dry weather makes a comeback Monday.

Dry conditions are likely for most of the area through at least Saturday morning. Rain chances increase substantially later in the the day as low pressure tracks along an approaching cold front. A few storms are also possible in the vicinity of the low and front, but instability is quite meager. There have been a few notable trends with the 00z model guidance this morning. First, the system has trended slower, with most of the precip now favored in the second half of the day and especially Saturday evening and Saturday night. Second, most guidance now depicts a slightly deeper low closer to the coast Sunday. This could cause wet and cool conditions for most of the area Sunday with brisk N/NE flow off the water, especially near the coast. Lastly, and perhaps most significantly, an upward adjustment in QPF is now reflected in most deterministic and ensemble guidance, including the NBM. Probabilities for 0.25" and 0.5" have increased two fold compared to this time yesterday. Any convective enhancement would also favor higher totals and this aligns well with the now ~10-30% probs for 1". Aerial QPF from our forecast now depicts 0.5-1" for the entire area. Still, this is far from a drought-buster given the substantial rainfall deficits across our area. Quite a large range in temps Saturday, with highs varying between the upper 80s in the far south and as low as the mid 60s on the MD Eastern Shore.

As mentioned above, the delayed passage of this system will likely allow showers, overcast skies, and breezy conditions to linger (at least) near the coast Sunday. High temperatures range from the mid 50s to lower 60s. If clouds and onshore flow persist for most of the day, there is some potential for temperatures to be lower than currently forecast. The low pressure system in question pulls further away from the coast Monday, with high pressure also nudging down in the Mid-Atlantic. This favors dry wx and moderating temps.

KEY MESSAGE 3...There are several opportunities for rainfall next week as an unsettled pattern potentially develops.

Troughing may develop over most of the CONUS by the middle the later half of next week, with several fronts and disturbances passing through. Therefore, there are several opportunities for beneficial rainfall next week in the midst of this potentially unsettled pattern and the latest CPC outlook favors slightly above average rainfall in the 6-10 day period. Better late than never for those April showers! Beyond the weekend, the next chance for measurable rainfall occurs as early as Tuesday along a cold front. 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 /07Z FRIDAY THROUGH TUESDAY/

As of 130 AM EDT Friday...

VFR conditions prevail for the 06z/25 TAF period. Primarily SKC through most of this morning, outside of widely scattered mid- level clouds. CU likely increases quickly after 17z or so this afternoon as a deeply-mixed boundary layer interacts with a backdoor cold front. Model guidance continues to hint at isolated to scattered showers (and potentially a rumble or two of thunder). The "highest" coverage currently looks to be just W of the Chesapeake Bay although most terminals have a low-end chance. Have included PROB30 groups to address this potential. Otherwise, light and variable winds increase out of NW in the morning and then E-NE later in the period as the front pushes inland.

Outlook: Low pressure tracks along the front Saturday afternoon into Saturday night, bringing an increased chance of showers and flight restrictions. High pressure builds to the N Sunday with an onshore component to the wind persisting along the coast, which could result in persistent lower CIGs. VFR and dry conditions return by Monday.

MARINE

As of 245 AM EDT Friday...

Key Messages:

- Mainly sub-SCA conditions are expected to prevail through Saturday, though a brief surge of gusty NE winds is expected this afternoon into this evening as a front drops south over the waters.

- Solid SCA conditions expected Saturday night and Sunday as low pressure deepens offshore. Gusts to Gale Force will be possible over the coastal waters Sunday into Sunday afternoon, with the best chances of these gusts occurring over the northern waters north of Parramore Island.

High pressure is centered off the SE coast early this morning. Latest obs reflect SSW winds ~10 kt. Waves were around 1 ft with seas 2-3 ft offshore. Given very weak synoptic flow regime in place, expect local sea/bay breeze circulations to dominate late this morning into the early afternoon. By mid to late afternoon, a second area of high pressure centered to our north builds down the northeast coast and drive a cold front south across the local waters into early this evening. E winds briefly increase to 10-15 kt late this afternoon and this evening with gusts to 20 kt, mainly nearshore across the southern Ches Bay, and adjacent rivers, and the Atlantic coast of the Eastern Shore as the front into the region. A few spotty showers or even an isolated storm are possible along and ahead of the frontal boundary, and could result in briefly gusty winds given the very dry low level airmass.

The trailing cold front crosses the waters Saturday afternoon and evening, with weak surface low lifting NE along the front into Sat night. The low pressure actually deepens after the front is farther offshore later Saturday night into Sunday, with the deepening low quickly lifting off the MD/DE coast overnight. E winds still look to strengthen and become NE with time early Sunday morning. SCA headlines may be needed for northern zones Saturday morning, but are more likely for the Bay and coastal waters Saturday night into Sunday behind the front. By Sunday, Local wind probabilities for Gale Force Gusts to 34kt have trended a bit higher (50-70%) across the coastal waters, with the best chances north of Parramore Island, increasing to 60-80+% Sunday afternoon into early Sun evening, and will therefore need to keep an eye on Gale headline potential as we get closer, again mainly over the northern and central coastal zones and 20-60 NM waters.

Waves build Saturday night and Sunday to 3-4 ft, before falling back to 2-3 ft on Monday. Seas will be highly dependent on the location and strength of offshore low pressure. Still expect seas to increase to ~7-9 ft N and 5-8 ft S by early Sunday evening with heights slowly falling off through the day Monday. High pressure briefly dominates Monday night into early Tuesday before the next system approaches from the west.

AKQ WATCHES/WARNINGS/ADVISORIES

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