textproduct: Wakefield

WHAT HAS CHANGED

Shower chances have increased for Thursday. Confidence remains high in a prolonged period of low temperatures near or below freezing beginning Friday night and continuing into early next week.

KEY MESSAGES

1) Scattered showers are possible on Thursday as a series of cold fronts approaches.

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

DISCUSSION

As of 230 PM EDT Wednesday...

KEY MESSAGE 1...Scattered showers are possible on Thursday as a series of cold fronts approaches.

Afternoon sfc analysis depicted high pressure over the area with mostly sunny skies and temps as of 130 PM in the upper 60s to mid 70s across most of the area and mid 60s across the Eastern Shore. Well to the west, a shortwave trough aloft was digging into western portions of the Midwest. Cloud cover increases tonight into Thursday morning as the shortwave approaches. Given partly cloudy skies tonight, lows will be "mild" in the mid-upper 40s for most of the area and lower 50s along the coast.

The shortwave moves into the local area Thursday morning, allowing for an increase in cloud cover as well as a few isolated to scattered light showers. The 12z HRRR and RRFS were in agreement regarding these morning showers with the initial shortwave. As such, have increased PoPs to 30-45% Thursday morning in a SW-NE orientation across the NW half of the FA. These showers will likely be light and brief with a break in the precip likely from mid-late morning into early afternoon on Thursday. Breaks in the cloud cover are expected behind the first round of showers. This will help temperatures to warm into the upper 60s to lower 70s with dew points in the low-mid 50s for most (locally upper 40s). Given the low dew points, instability is expected to remain low with around 500 J/kg of SBCAPE in the afternoon. However, given the strong trough over the area brining with it cool temps aloft, mid-level lapse rates increase to around 7 C/km (potentially up to 7.5 C/km for some). Low- level lapse rates will be even higher with most models showing lapse rates of >9 C/km. These lapse rates combined with the afternoon clearing, a secondary piece of vorticity, and a cold front should allow for scattered afternoon showers to develop in the lee of the Appalachians and move east across the local area. The HRRR and RRFS both show this convection. As such, confidence has increased in afternoon showers. As such, have increased PoPs to 30-60% in the afternoon with the best chance north of US-460 in the mid-late afternoon. Additionally, while severe weather is not expected, gusty winds will likely accompany the stronger showers. Pea-sized hail and a few rumbles of thunder are even possible.

Any stronger showers should end quickly after sunset with the loss of diurnal instability. However, both the HRRR and RRFS show lingering, light stratiform precipitation (likely a combination of drizzle and light rain) continuing into Thursday night behind the cold front. The best chance for this is across central VA. Any lingering showers likely end for most areas Thursday night with a few lingering showers possible across the Eastern Shore early Friday morning. While several rounds of showers are possible Thursday, overall rainfall totals are still expected to remain light with <0.2" expected for most locations. Locally higher rainfall totals of 0.25-0.5" are possible across portions of central VA where showers train over the same areas. Even so, rainfall totals will be light. Unfortunately, this looks to be the last chance of rain over the next week or more.

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

The anomalously strong trough remains centered over the region through Saturday before gradually moving offshore. However, troughing will persist through at least early next week. As such, expect the coldest air of the season beginning Friday and continuing through early next week. Each night (beginning Friday night), widespread lows near or below freezing are expected inland with some locations dropping into the upper 20s a few nights. Therefore, widespread frost and freeze conditions are expected which will bring the end to the growing season for most locations away from the coast. A hard freeze (lows at or below 28F) is even possible for some. While the growing season has already ended for our Piedmont counties, Freeze Watches will likely be needed in future updates across most of the remaining inland areas for Friday night/Saturday morning. Near and along the coast, NW winds remain elevated enough to keep temperatures from cooling below freezing. Instead, lows in the upper 30s to lower 40s are expected for these areas. Highs each day from Friday through early next week likely remain in the 50s (low-mid 50s for most). However, cannot rule out a few locations struggling to reach above the upper 40s across far northern portions of the area (mainly the lower MD Eastern Shore) Friday and Saturday.

Additionally, NW winds will be breezy behind the cold front(s) with gusts up to 20-25 mph inland and 25-30 mph along the coast possible Friday and Saturday. While winds will diminish each night (especially inland), the wind will make it feel even colder. The coldest wind chills look to be Friday night into Saturday morning an well as Saturday night into Sunday morning when it will feel like the upper 20s for most of the area (locally mid 20s).

AVIATION /19Z WEDNESDAY THROUGH MONDAY/

As of 1235 PM EST Wednesday...

VFR conditions prevail through the 18z TAF period. High clouds gradually increase in coverage later this afternoon into tonight. CIGs lower Thursday morning as a shortwave approaches (6000-10000 ft CIGs). Additionally, a brief period of isolated to scattered showers is possible Thursday morning with scattered Thursday afternoon showers likely. Confidence is low in exact placement and timing of the morning showers. As such, have only added VCSH to RIC and SBY for now. Shower chances continue into Thursday night. However, primarily VFR conditions are favored apart from a brief VIS drop below VFR with some of the showers. Otherwise, winds remain generally light and variable through Thursday morning. Winds become WSW/W ~10 kt with gusts up to 15-20 kt late Thursday afternoon into Thursday evening.

Outlook: Some sub-VFR conditions are possible overnight Thursday night into Friday morning due primarily to MVFR CIGs, however, VIS may briefly drop in showers as well. Gusty NW winds are likely behind the cold front through the weekend.

MARINE

As of 230 PM EDT Wednesday...

Key Messages:

- Small Craft Advisory conditions are likely beginning Thursday night and continuing through much of the weekend.

- The strongest northwest winds are expected Saturday afternoon into Saturday night, with a low probability of gales force gusts over the outer coastal waters.

Relatively benign marine conditions will continue tonight through much of tomorrow, with winds generally remaining below SCA criteria. Conditions deteriorate late Thursday night into Friday as a strong cold front crosses the waters and northwest winds increase in its wake.

A prolonged period of SCA conditions is expected late Thursday through at least Sunday morning cold air advection and a tightening pressure gradient result in gusty northwest winds. There may be a relative lull in the winds Friday afternoon/evening before winds increase again Friday night into Saturday. The strongest winds are currently forecast from Saturday afternoon 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 60 nm. The latest 12z GFS and ECMWF remain in fairly good agreement, showing peak 925 mb winds generally around 25 to 30 knots. Additionally, ensemble probabilities for gale force gusts have decreased compared to previously runs. Notably, the EPS (which had been the highest) trended down to ~40% (at most) 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 more likely outcome.

The pressure gradient remains tight into Sunday, with SCA conditions potentially lingering through Sunday morning and potentially into Sunday afternoon before winds/seas gradually subside. Small Craft Advisories will likely be needed with subsequent forecast packages.

AKQ WATCHES/WARNINGS/ADVISORIES

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