textproduct: Wakefield

WHAT HAS CHANGED

Updated the aviation discussion.

KEY MESSAGES

1) A series of cold fronts bring the potential for two waves of isolated to scattered showers today. Otherwise, mild temperatures remain through this afternoon with dropping temperatures late.

2) Much cooler temperatures arrive Friday into early next week with below freezing overnight temperatures likely inland.

DISCUSSION

As of 240 AM EST Thursday...

KEY MESSAGE 1...A series of cold fronts bring the potential for two waves of isolated to scattered showers today. Otherwise, mild temperatures remain through this afternoon with dropping temperatures late.

Fairly quiet weather-wise across the forecast area this morning. Nighttime microphysics satellite imagery shows some passing mid-high clouds, though they should scatter out over the next few hours. Observations near the coast of ern/SE VA and NE NC also depict some patchy ground fog. This is likely due to the higher dew points and calm winds. Most guidance does not develop widespread fog and the current thinking is it remains patchy through sunrise.

A large upper trough and associated sfc low and cold front will bring the potential for a few rounds of isolated to widely scattered showers today. The first round, where PoPs are 20-30%, occurs this morning with an initial vorticity lobe and shortwave aloft. The late morning and early afternoon hours then look to be dry for most. Clouds are also expected to briefly scatter out during this time, allowing for one last day of mild temps. Forecast highs are generally in the mid to upper 60s, with a few ~70 F readings possible in SE VA and NE NC. The second round of showers follows along the cold front late this afternoon and evening. This is when a few heavier/stronger cores could develop given steep lapse rates and cool temps aloft. This combination allows for up to ~500 J/kg of sfc- based CAPE. In addition, can't rule out some sporadic lightning strikes or small hail in the heaviest cores. The best potential for this late-day activity is from the nrn Piedmont into the nrn portions of the RIC metro, the Northern Neck, and Eastern Shore. However, slight chc PoPs extend roughly to the NC/VA border. These showers won't be efficient rainfall producers and still don't expect much in the way of measurable rainfall. Totals up to a tenth of an inch are possible, but this would be highly localized. Gusty NW winds overspread the area late tonight into early Friday behind the fronts. Overnight lows generally in the mid 40s and, despite the cold advection, went a few degrees above the NBM given the likely- mixed BL and lingering clouds.

KEY MESSAGE 2...Much cooler temperatures arrive Friday into early next week with below freezing overnight temperatures likely inland.

An anomalously strong (-2 to -3 st dev) upper trough settles over the area Friday into the weekend. Following the initial push of cold advection behind the cold front, this trough will allow for chilly temps at least through early next week. Highs Friday range from the low-mid 50s N/NW to mid-upper 50s S/SE, under partly and mostly sunny skies, respectively. The coolest night of the season so far is likely on the way Friday night, though there is some disagreement across the guidance on exactly how cold it gets. Most of the hi-res and statistical corrections show widespread lows in the low-mid 30s, while the NBM is chillier. A continuing N-NW wind, especially near the coast, could prevent ideal radiating conditions from developing. Regardless if widespread readings below freezing occur, it'll still be quite chilly given the breeze. There is not enough confidence in any Freeze Watches for Friday night at this time. Highs Saturday will be more typical of winter, with temps only peaking the in the low-mid 50s. Portions of the lower MD Eastern Shore could struggle to get out of the 40s. Continued cold advection, a compressed pressure gradient, and a well-mixed BL will allow for gusty NW winds for most of the day...to 20-25 mph inland and 25-30 mph near the coast and on the Eastern Shore.

The coolest overnight temps are expected Saturday and Sunday nights. This is when widespread (away from the immediate coast) overnight freezes are likely. Lows inland generally in the upper 20s to lower 30s, with mid to upper 30s at the immediate coast. Freeze Watches (and eventually Freeze Warnings) are likely for localities still in the growing season during this period, though it's a bit early to issue these being mostly >48 hrs out. Daytime highs Sunday into early next week look to remain in the 50s with potentially a modest warming trend by mid-late week. Despite the cool temps, there should be plenty of sunshine. Winds also gradually relax, but remain a bit breezy near the coast.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

As of 1245 PM EST Thursday...

Cloud cover is expected to gradually increase in coverage from west to east this afternoon ahead of a cold front with SCT-BKN mid-level clouds (6000-8000 ft CIGs) expected. Isolated to scattered showers are possible as well along and ahead of the cold front. However, confidence in showers is quite low at any given terminal. As such, have added PROB30s to RIC/SBY/PHF to account for this possibility. Even with the showers, VIS and CIGs may remain VFR. Cannot completely rule out an isolated shower at ORF/ECG, but confidence was too low to reflect in the TAF. The showers move offshore by this evening with SCT-BKN sky cover continuing through the night. MVFR CIGs (1500-2500 ft CIGs) are possible at SBY beginning after 6-7z Sat and continuing through the remainder of the 18z TAF period. Otherwise, winds of ~10 kt with gusts up to 15-20 kt become NW Fri.

Outlook: VFR conditions are favored from Saturday into next week with gusty NW winds expected behind the cold front.

MARINE

As of 240 AM EST Thursday...

Key Messages:

- Small Craft Advisory conditions develop tonight over the Bay, and are likely over most of the marine area Friday afternoon and evening through much of the weekend.

- The strongest northwest winds are expected Saturday afternoon into Saturday night. A few gusts to Gale Force are possible over the offshore waters during this same period.

Latest obs showing S-SE winds 5-10 kt over the waters early this morning. Waves 1 ft, seas 1-2 ft. Conditions deteriorate late tonight into Friday, as a cold front approaches from the west this afternoon, and crosses the waters this evening. Winds veer around to the S-SW today, gradually increasing this afternoon and peaking this evening in the immediate wake of the front. On the coastal waters, gusts to 25-30 kt and building wind waves late tonight into Friday morning will drive seas up into the 3-5 ft range north of Chincoteague. SCA have been issued for our northern waters for Friday. Meanwhile, SCA have been issued for the Chesapeake Bay tonight into Friday afternoon/early evening, ending first over the lower bay as the pressure gradient slowly and briefly slackens. However, that lull will be short-lived, as another dry front crosses later Friday into Saturday, with a prolonged period of SCA conditions then expected from Friday night through much of the weekend, as cold air advection and a re-tightening pressure gradient result in gusty northwest winds. The strongest winds are currently forecast from Saturday through Saturday night, with northwest winds of 20 to 25 knots and gusts to 30 knots across much of the waters. Occasional gusts to 35 knots are possible out across the outer coastal waters, mainly out 50-60 nm.

The latest 00z/12 GFS and ECMWF remain in fairly good agreement, showing peak 925 mb winds generally around 25 to 30 knots Saturday. Additionally, ensemble probabilities for gale force gusts continue to steadily decrease compared to previously runs. Notably, the EPS (which had been the highest) trended down to ~20-30% for the far outer coastal waters. While a few gale force gusts remain possible, confidence in frequent gale conditions is low, with widespread SCA conditions the far more likely outcome.

The pressure gradient remains compressed into Sunday, with SCA conditions likely to linger through Sunday morning and potentially into Sunday afternoon before winds/seas gradually subside. Small Craft Advisories will likely be needed with subsequent forecast packages for most of the waters from Friday afternoon/evening well into the upcoming weekend. Winds veer around to the NNW early next week, with waves/seas also subsiding below SCA thresholds by later Sun night into Monday.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 10 PM this evening to 7 PM EST Friday for ANZ630-631. Small Craft Advisory from 10 PM this evening to 10 AM EST Friday for ANZ632-634. Small Craft Advisory from 6 AM to 7 PM EST Friday for ANZ650- 652.