textproduct: Wakefield

WHAT HAS CHANGED

Precipitation (and snowfall) amounts have slightly increased for Sunday, though uncertainty remains given marginal temperature conditions which could limit accumulations.

KEY MESSAGES

1) Milder temperatures make a brief return today, especially across southeast Virginia and northeast North Carolina. There remains a chance for light rain or a rain/snow mix this morning across northern portions of our area.

2) Snow or a mix of rain and snow remains possible Sunday, with mainly rain expected for southeast Virginia and northeast North Carolina where a few wet snowflakes could mix in as precipitation ends late Sunday afternoon and early Sunday evening. The best chance for any (light) snowfall accumulation remains from central Virginia into the Northern Neck and Eastern Shore.

3) A strong push of Arctic air arrives for early next week, with below normal temperatures to continue through the first half of next week. Tuesday is expected to be the coldest day, with single digit wind chills possible Tuesday morning.

DISCUSSION

As of 215 AM EST Saturday...

KEY MESSAGE 1...Milder temperatures (mid 30s) are present over the area this morning with light southerly flow and modest warm advection. Mid-level cloud cover increases over the next several hours as a shortwave trough lifts through the OH Valley. Some light precipitation is also expected for northern portions of our forecast area through this early afternoon as an associated (weak) cold front lifts NE. Thermal profiles from the hi-res guidance suggest some snow or sleet could mix in with the rain across the far northern tier of the AKQ CWA, mainly from Louisa to Caroline to Dorchester County MD. This would be very brief and generally confined to the morning hours. No accumulation is expected. Otherwise, temps today will be milder, especially for SE VA and NE NC. Highs range from the upper 40s W/NW to 50s E/SE. Lower 60s are even possible for far SE VA and NE NC.

The first part of tonight will likely remain mostly dry as the initial shortwave lifts NE through interior New England and a vigorous upper trough digs into the Deep South. Lows range through the 30s to lower 40s.

KEY MESSAGE 2...The upper trough pushes E Saturday night into Sunday with low pressure developing off the Carolina coast and tracking NE Sunday. A period of snow continues to look likely Sunday, particularly for interior portions of NE NC and southern VA into central VA, the Middle Peninsula and Northern Neck, and Eastern Shore. Uncertainty is higher across SE VA and NE NC due to conflicting model guidance and generally warmer temps. Still, a transition to snow is expected at the very least by the evening and early overnight periods for these areas.

Most data continues to suggest this will not be a major or impactful snow event. However, there unfortunately remains quite the large spread in potential outcomes across the model guidance. The NW trend seen in the QPF field by the previous forecaster has generally continued with the latest 00z model suite. Both the EPS and GEFS have also increased probs for 1" and 3" and they are notably higher than the yesterday's 12z guidance. The placement of the higher probs shows significant variance between these two modeling systems, however. The EPS places the higher probs across coastal locations and the Eastern Shore; oppositely, the GEFS is displaced further N and E with near-zero probs in NE NC. The deterministic models also trended higher with snow totals, particularly the 00z GFS, with shorter-range guidance, such as the high-res NAM and regional CMC, also trending upward. The NBM, which generally runs a model cycle or two behind, is in closer agreement to the GEFS scenario, but is not nearly as high as the deterministic GFS solution. Regardless, surface temperatures still appear to be marginal and heavily dependent on wet bulb and column-cooling effects (vs precip moving into a cold antecedent airmass). Most models show temps near to slightly above 32F when snow is falling, and coupled with poor ascent in the DGZ (particularly NW) and warmer ground temps, suggests snow may have trouble accumulating. Would expect any accums to be mostly confined to grassy and elevated surfaces and not roadways. For now, the current official forecast is for 1.0-1.5" of snow over the Eastern Shore, with a few tenths to less than 1" for the Piedmont, central VA, and SE VA, and no accumulation expected for those near the Albemarle Sound. A reasonable worst case scenario would be 2-3" for the MD Eastern Shore, and 1-2" back through most of central/eastern VA and NE NC. However, as we've seen with the 00z guidance, adjustments to the official forecast may by needed over the next few updates. Colder and drier air arrives from NW- SE later Sunday evening bringing a rapid end to the snow or rain/snow mix. Will also have to monitor for any freezing of a residual wet/slushy surfaces overnight Sunday.

KEY MESSAGE 3...A strong push of Arctic air arrives for early next week behind a secondary dry cold front, with below averages temperatures to continue through the first half of next week.

Arctic air arrives Monday night behind the secondary cold front. Frigid temperatures are expected for at least the first half of next week, with the coldest air occurring Monday night, Tuesday, and into early Wednesday morning. EPS/GEFS show 2m temperature anomalies 15F to nearly 20F degrees below average. Overnight lows in the upper teens to mid 20s are expected Sunday night, and primarily teens Monday/Tuesday night. Cold Weather Advisories are possible Mon night given forecast wind chills in the single digits across the N and W. While day-time temps will be rather chilly each day Monday through Wednesday, Tuesday is forecast to be the coldest day with highs struggling to make it above freezing.

Temperatures may attempt to moderate a bit by the middle and end of the week as the upper flow turns more zonal. Low-end precip chances also return by Thursday.

AVIATION /07Z SATURDAY THROUGH WEDNESDAY/

As of 1235 AM EST Saturday...

VFR conditions are expected to prevail through the 06z TAF period. Through the rest of the early morning hours, expect LLWS at RIC, SBY, and PHF as a low-level jet passes overhead. This threat should diminish after 14z. Otherwise, winds should avg S/SSW ~10 kt this morning. Clouds increase in coverage from W to E through this afternoon with a mixture of stratus and cirrus. Light rain or a rain/snow mix (PoPs 40% or less) is also possible early this morning in the Piedmont, but should remain NW of all terminals. Intermittent MVFR CIGs are also possible in these showers, but coverage is too low for any prevailing groups. Winds become SW 10-15 kt with gusts up to 20-25 kt this afternoon, diminishing this evening into tonight.

Outlook: More widespread flight restrictions are anticipated by Sunday as rain, and likely some snow as well, overspreads the region.

MARINE

As of 215 AM EST Saturday...

Key Messages:

- Small Craft Advisories are in effect for the Chesapeake Bay, lower James River, and northern coastal waters this morning.

- Benign, sub-SCA conditions are expected this afternoon through the daylight hours of Monday, with another round of SCAs possible Monday night into Tuesday.

Early this morning, low pressure (~993 mb) is centered over the Great Lakes with a cold front extending south, roughly just west of the Appalachian mountains. Meanwhile, high pressure (~1025 mb) is centered over northern Florida and will continue to drift east this morning. SW winds have increased this morning (due to a tightening pressure gradient), with wind speeds averaging 5 to 20 knots and gusts ~25 knots. The pressure gradient begins to slacken as we approach sunrise, with winds gradually diminishing through this morning and eventually falling below SCA criteria by mid to late morning. SCAs remain in effect for the Chesapeake Bay, lower James River, and coastal waters north of Cape Charles Light. Due to the increasing winds, seas have built to 3 to 5 feet (locally 6 feet out 20 nm off the MD Eastern Shore) and waves in the Chesapeake Bay have built to 3 to 4 feet. Sub-SCA conditions return this afternoon and are expected to persist through Sunday and the daylight hours of Monday before another cold front crosses the waters and brings the potential for SCA conditions back to the area Monday night into Tuesday.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 10 AM EST this morning for ANZ630>632-634-650-652. Small Craft Advisory until 4 AM EST early this morning for ANZ638. Small Craft Advisory until 7 AM EST this morning for ANZ654.