textproduct: Wakefield

WHAT HAS CHANGED

Winter Storm Watch upgraded to Warning in Hampton Roads and northeast North Carolina. Forecast snowfall amounts continue to decrease for the northern half of the area with a tightening gradient for the higher amounts. Cold Weather Advisory issued for late tonight through Saturday. A Coastal Flood Watch has been issued for portions of far SE VA and NE NC for Sunday morning.

KEY MESSAGES

1) High confidence that a strong winter storm impacts the region Friday night into Sunday. Significant accumulating snowfall and blowing and drifting snow due to strong winds are expected. The highest confidence is across south and southeastern portions of the area. There will likely be a very sharp gradient in total snowfall amounts, roughly along the US-360 corridor (potentially through the Richmond Metro).

2) Moderate to locally Major coastal flooding is expected with the high tide cycle Sunday morning for portions of Hampton Roads and NE NC; a Coastal Flood Watch has been issued.

3) Well below normal temperatures remain through early next week, keeping localized impacts (i.e icy roads) in place through the weekend. The coldest air wind chills are expected Saturday night into Sunday morning and an Extreme Cold Watch has been issued for the entire forecast area. A Cold Weather Advisory is in effect tonight for portions of the Maryland and Virginia Eastern Shore.

DISCUSSION

As of 330 AM EST Friday...

KEY MESSAGE 1...High confidence that a strong winter storm impacts the region Friday night into Sunday. Significant accumulating snowfall and blowing and drifting snow due to strong winds are expected. The highest confidence is across south and southeastern portions of the area. There will likely be a very sharp gradient in total snowfall amounts, roughly along the US-360 corridor (potentially through the Richmond Metro).

Guidance continues to dial in on the track of the low pressure system. Seeing reduced spread between the main global models and their ensembles with respect to low centers, which would have the low hug the southern NC coast before continuing NE and straying further offshore as it passes by VA. The main mode of disagreement continues to be the battle zone between drier air from the N/NW associated with a very strong area of high pressure (~1045 mb) over the Plains, and the intense low pressure system developing off the SE coast late Friday night/Saturday. There is still quite a bit of spread in the models regarding snowfall totals as a result, especially with how far north/northwest the snow makes it. The NAM and HRRR keep measurable snowfall S/SE of the Richmond metro, whereas the global models take measurable snow north of the I-64 corridor and up the Eastern Shore as well. A very tight gradient is likely with this system, which is well depicted in the high-res guidance. Unfortunately this also means than any subtle shift in storm track could mean the difference between and inch of snow and 6 inches of snow for areas along that northern edge of the snowfall. Ensembles further support the notion of the higher snowfall totals hugging the coast. For example, the 50%+ probs for 6" (which realistically is more like 9" since SLR will be higher than 10:1) from the Euro Ens are limited to OBX and Virginia Beach. In response to these trends, the forecast snow totals have leaned into the tighter gradient and shifted the highest total from being generally across the south to being in the southeast. Now forecasting 8-10" (locally to 12") for south-side Hampton Roads and far NE NC, 5-8" for Mecklenburg over to the peninsula, and tapering to 1-3" for Cumberland through the RIC metro and NE to the Eastern Shore. Expect that this gradient will tighten further in the next few forecast cycles. Went ahead and upgraded the Winter Storm Watch to a warning for the highest confidence areas: NE NC and Hampton Roads (including Southampton and Isle of Wight). The rest of the Winter Storm Watch remains unchanged. Will also note that there is high confidence in very strong winds occuring along the coast Sat night into Sunday morning with gusts of 50-60mph. In addition to the potential to damage trees/powerlines, this could create blizzard conditions for the coastal counties. Therefore, kept the blizzard wording from the watch in the warning for these zones.

Regarding the potential for overrunning snowfall this afternoon: the CAMs have mostly backed off on any appreciable snowfall during the day today. Kept chances in for south-central VA, but it generally looks to remain west of the FA. That said, cannot rule out a few tenths of an inch. As for the timing of the rest of the snow, expecting snow to gradually push N into the area late Friday night. Likely PoPs enter the southern edge of the FA Sat morning and slowly push N through the day. Snow continues through Sat night with highest confidence in the south/southeast and along the coast. Snow comes to an end from W to E Sunday morning.

Please keep a close eye on the forecast over the next 24 hours, with forecast confidence remaining below average for this timeframe. A ~50 mile shift in the coastal low will have drastic impacts to the final snowfall amounts. Additional messaging and headlines will need adjustments over the next few forecast cycles.

KEY MESSAGE 2...Moderate to locally major tidal flooding is expected with the high tide cycle early Sunday, primarily across southside Hampton Roads and the Atlantic coast of NE NC. Deepening sfc low pressure will be pushing farther off the NC and VA coast early Sunday, with strong N winds becoming NNW. This wind direction as the high tide cycle approaches favors the greatest impacts on the Atlantic facing portions of VA Beach and Currituck NC and these areas (as well as Northampton VA for Kiptopeke) have been included in a Coastal Flood Watch for widespread moderate to locally major tidal flooding. Minor flooding is likely into the lower James and a little farther up the Bay but this will be handled w/ Coastal Flood Advisories as needed. Well up the Bay, water levels will be much lower due to the strong N winds.

KEY MESSAGE 3...Well below normal temperatures remain through early next week, keeping localized impacts (i.e icy roads) in place through the weekend. The coldest air wind chills are expected Saturday night into Sunday morning and an Extreme Cold Watch has been issued for the entire forecast area. A Cold Weather Advisory is in effect tonight and tomorrow for the entire area leading up to the Extreme Cold Watch.

Friday will see highs struggle to get out of the mid 20s for much of the northern two-thirds of the area. Saturday will be even colder with highs in the low to mid 20s for most. Winds chills will be near zero across the north and 5-10 degrees to the south. While there may be a few hours during the day Sat where wind chills are above criteria, went ahead and issued a Cold Weather Advisory for the entire area starting tonight and lasting until the Extreme Cold Watch starts. The Extreme Cold Watch has been maintained for Saturday night into Sunday morning where the combination of a strong N to NW wind and air temperatures in the low to mid teens will result in wind chills as low as 0 to 10 below.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

As of 1210 PM EST Friday...

Mainly VFR conditions expected to prevail through tonight and into early Sunday morning. There is a chance for some -SN across south- central VA this afternoon/evening, which as of now would miss the main terminals and be more towards FVX/AVC area. Light NE winds of 5-10kt through tonight before beginning to increase with gusts to 20-25kt for eastern terminals after ~12Z. Deteriorating conditions will spread north/eastward across the terminals closer to daybreak. Have included MVFR CIGs at ORF/ECG after 06Z/Sat. PROB30s remain for all terminals except SBY for SN and lower VIS starting ~12-14Z. Highest confidence in seeing snow during this TAF period is at ECG after 12Z.

Outlook: A winter storm will continue to impact the area Saturday night into Sunday morning. The greatest impacts are expected Saturday evening through Sunday morning. At this time, periods with +SN and low VSBYs are most likely, along with elevated to strong northerly winds, at ORF and ECG Sat night through Sunday morning. Can expect gusts of 40 kt+ closer to the coast with inland terminals likely to see gusts to around 30 kt. Winds become NW Sunday and remain elevated but flight restrictions should drop off as SN ends (though BLSN may be an issue). Otherwise mostly clear with gradually diminishing winds into Monday.

MARINE

As of 255 AM EST Friday...

- Ramp up Small Craft Advisories are in effect from late tonight-Saturday as conditions begin to deteriorate ahead of the main storm.

- Confidence remains high in high-end Gale to Storm conditions this weekend as a strong coastal low develops off the Carolinas. Storm Warnings have been issued for the coastal waters south of Cape Charles, where confidence in storm conditions is highest and onset time is earliest (Saturday evening).

- Freezing spray and high seas are expected this weekend as well. A Heavy Freezing Spray Watch has been issued for the bay, Lower James, and northern two coastal zones for Saturday night into Sunday morning, when accretion rates could reach 2 cm/hour for a few hours.

High pressure is beginning to build toward the waters with N-NW winds of ~15 kt with gusts up to 20 kt. Seas are 2-3 ft, and as expected, light freezing spray is occurring with accretion rates on the order of 0.25-0.40 cm/hour. No advisories right now as accretion rates aren't expected to reach moderate levels until Sat night.

Strong high pressure builds south from the northern Plains into the Gulf today into Sat. All eyes will then turn to a coastal low, which begins to form off the SE CONUS coast late Friday before gradually deepening on Saturday. Then, the low is progged to rapidly deepen to a very impressive 970-980mb as it moves to a position 100-200 miles east of the VA/NC coast by Sunday morning. Sub-advisory conditions are expected from today through part of tonight. Then, NE winds increase to ~20 kt by 12z/7 AM Sat before becoming 20-30 kt with gusts to 35 kt by Saturday afternoon. Ramp up SCAs have been issued for all marine zones to account for this. Marine conditions will rapidly deteriorate Saturday night as the low deepens to below 980mb. The 00z/30 guidance is starting to come into agreement with a slightly farther south track than was expected 24-36 hours ago. Still, very dangerous marine conditions are expected Saturday night into Sunday with winds becoming N then NNW and increasing to 30-40 kt north/35-45 kt south. There is still a moderate to high potential for storm conditions across most of the waters (highest confidence south of Windmill Pt/Chincoteague). The worst conditions are expected from midnight- noon on Sunday. Confidence in storm conditions has increased enough to upgrade to Storm Warnings for the southern two coastal zones and Currituck Sound (onset time is also slightly earlier here with storm conditions starting late Sat evening). Local wind probs for 48 kt gusts have increased to 60-95% across these zones, hence the upgrade to a warning after collaboration with MHX. Will leave the Storm Watches up elsewhere with Gale Watches for the upper rivers. The probability for 48 kt gusts remains 30-60% across the Ches Bay (much higher across the Lower Bay with lower probs around Tangier) and 40- 60% across the northern Coastal Waters north of Cape Charles Light. Seas build to 8-12 ft across the northern coastal waters and 10-15+ feet across the southern coastal waters (highest across the NC coastal waters) given the strong winds. Additionally, given the high probability for snow (potentially heavy), periods of zero visibility are increasingly likely across the coastal waters Sat into Sun. Lastly, periods of light freezing spray will continue through Saturday before a period of moderate to occasionally heavy freezing spray is expected Saturday night through Sunday morning with the very strong winds/CAA on the back side of the low. With water temps already in the mid 30s across the bay and likely the very nearshore nrn coastal waters, have issued a Heavy Freezing Spray Watch here as water temps will likely cool by another degree or two with air temps potentially in the upper teens Sun AM. Winds become NW behind the low and gradually diminish Mon. Sub-advisory winds return Monday evening and continue through the middle of the week.

CLIMATE

Record Low Max Temperatures for Sat Jan 31:

- RIC: 23 (1948) - ORF: 25 (1936) - SBY: 24 (2019) - ECG: 29 (1965)

Daily Record Snowfall for Sat Jan 31 and Sun Feb 1:

- Date: Sat Jan 31 Sun Feb 1

- RIC: 7.0" (1948) 3.1" (1948) - ORF: 4.0" (1980) 4.0" (1910) - SBY: 4.0" (2010) 4.0" (1962) - ECG: 5.0" (1980) 7.0" (1948)

AKQ WATCHES/WARNINGS/ADVISORIES

MD...Cold Weather Advisory from 1 AM Saturday to 1 AM EST Sunday for MDZ021>025. Extreme Cold Watch from late Saturday night through Sunday morning for MDZ021>025. Winter Storm Watch from Saturday morning through Sunday afternoon for MDZ023>025. NC...Cold Weather Advisory from 1 AM Saturday to 1 AM EST Sunday for NCZ012>017-030>032-102. Extreme Cold Watch from late Saturday night through Sunday morning for NCZ012>017-030>032-102. Winter Storm Warning from 4 AM Saturday to 7 PM EST Sunday for NCZ012>017-030>032-102. Coastal Flood Watch from late Saturday night through Sunday afternoon for NCZ102. VA...Cold Weather Advisory from 1 AM Saturday to 1 AM EST Sunday for VAZ048-060>062-064>069-075>090-092-093-095>100- 509>525. Extreme Cold Watch from late Saturday night through Sunday morning for VAZ048-060>062-064>069-075>090-092-093- 095>100-509>525. Winter Storm Warning from 4 AM Saturday to 7 PM EST Sunday for VAZ092-093-095>098-523>525. Coastal Flood Watch from late Saturday night through Sunday afternoon for VAZ095-097-098-100. Winter Storm Watch from 7 PM EST this evening through Sunday afternoon for VAZ060-061-066>069. Winter Storm Warning from 7 PM this evening to 1 PM EST Sunday for VAZ065-079-087. Winter Storm Watch from late tonight through Sunday afternoon for VAZ076>078-080>083-085-512>520-522. Winter Storm Warning from 1 AM Saturday to 1 PM EST Sunday for VAZ084-086-088>090. Winter Storm Warning from 1 AM Saturday to 7 PM EST Sunday for VAZ099-100. MARINE...Small Craft Advisory from 7 AM to 7 PM EST Saturday for ANZ630- 631-635>637-650-652-654. Storm Watch from Saturday evening through Sunday evening for ANZ630>632-634-638-650-652-654. Heavy Freezing Spray Watch from late Saturday night through Sunday morning for ANZ630>632-634-638-650-652. Small Craft Advisory from 1 AM to 7 PM EST Saturday for ANZ632>634-638-656-658. Storm Warning from 7 PM Saturday to 1 PM EST Sunday for ANZ633. Gale Watch from Saturday evening through Sunday evening for ANZ635>637. Storm Warning from 7 PM Saturday to 4 PM EST Sunday for ANZ656- 658.