textproduct: Wakefield

WHAT HAS CHANGED

High confidence for a major winter storm this weekend and very cold temperatures well into next week. Recent model guidance continues to show more mixed precipitation and freezing rain than pure snow. Wintry precip now extends well into early Monday morning and icing totals have increased. Additionally, a Cold Weather advisory continues for the entire area Friday night into Saturday morning as wind chills drop to the single digits or low-end negatives for far northern portions.

KEY MESSAGES

1) High confidence in a major winter storm impacting the region with increasing confidence regarding the precipitation types. Users should continue to keep a very close eye on the forecast over the coming days.

2) A Cold Weather Advisory remains in effect for the entire forecast area Friday night into Saturday morning ahead of the winter storm as wind chills drop to the single digits or low-end negatives behind a strong Arctic front.

3) A prolonged period of very cold temperatures is expected beginning Saturday AM and persisting much of next week with the potential for temperatures to remain below freezing for several days. Impacts from the winter storm are likely to last well into next week due to the very cold temperatures.

DISCUSSION

As of 240 AM EST Friday...

KEY MESSAGE 1...High confidence in a major winter storm impacting the region with increasing confidence regarding the precipitation types. Users should continue to keep a very close eye on the forecast over the coming days.

Winter Storm Watches remain unchanged with this forecast cycle. One last day of milder temperatures expected today ahead of the Arctic cold frontal passage tonight into early Saturday. An inverted trough sets up over the southeast US with CAD developing over the local area as strong high pressure (1045+ mb) builds over the Midwest and moves east Saturday. The cold front that moves through the area will stall over the southeast CONUS and a low pressure will form along it in the Gulf, then move toward the Appalachian mountains. A secondary low will form off the Carolina coast and move to the northeast. There will be ample Pacific and Gulf moisture feeding into the area with P-WATs 200-300% above normal. Forecast storm total QPF is well above 2" for most of the region with some areas above 2.5".

00z guidance has trended a bit slower with the onset of wintry precipitation across the region with little in the way of accumulation or impacts during the daylight hours of Saturday. It will be very cold ahead of the incoming storm with high temps in the low to mid 20s for most of the area and upper 20s to low 30s for far SE portions. QPF ramps up quickly after sunset from west to east as moisture aloft moves in from the south and west and overruns the very cold surface layer. Still expecting the initial precip type to be snow for most of the area but recent guidance suggests sleet will quickly mix in across the southern third of the area, potentially lifting northward to near the I-64 corridor by around midnight. Freezing rain will also mix in across the southern half of the area early Sunday morning. Still some uncertainty regarding the depth of the warm nose aloft with the GFS/GEFS maintaining the colder temps aloft for longer vs the ECMWF/EPS, which quickly strengthens the above freezing layer. The result is more snow and sleet on the GFS/GEFS and more freezing rain on the ECMWF/EPS. The differences with respect to the thermal profiles aloft decrease with time into Sunday morning with mixed precip indicated across all of our area before sunrise. The majority of the snow and sleet accumulations will occur overnight with the highest snow/sleet totals still expected across the north and northwest portions of the area. Snow/sleet totals drop off quickly with southeastward extent. It now appears that significant warm air at the surface and aloft will spread inland on Sunday with roughly the eastern third of the CWA, switching precip to plain rain during the afternoon Sunday. This area includes all of NE NC, Hampton Roads and the VA/MD Eastern Shore. Warming temps aloft will favor a corridor of significant to potentially catastrophic freezing rain accrual after the initial snow and sleet, mainly along and near the I-85 and I-95 corridors. Thermal profiles favor more sleet to the west and north of the main freezing rain corridor. Of note on the last few model cycles is the fact that significant QPF remains after sunset on Sunday with precip lingering well into Monday morning. This precip will likely end as light snow but not before additional significant ice accrual. Impacts from freezing rain compound rapidly (exponentially) as accrual increases above 0.25". The current forecast now has ice totals >0.5" from near Tappahannock southeastward into the Richmond Metro, Chesterfield, the Tri-Cities, Emporia, and South Hill, resulting in major travel impacts as well as widespread and long-lasting power outages. Absolutely not out of the question for portions of this area to see greater than 0.75" of freezing rain.

Everyone should take note and continue preparations for a significant icing/snow event with moderate to major (potentially extreme) impacts increasingly likely from this storm. In addition, after effects from the storm will last well into the work week due to very cold temperatures.

KEY MESSAGE 2...A Cold Weather Advisory remains in effect for the entire forecast area Friday night into Saturday morning ahead of the winter storm as wind chills drop to the single digits or low-end negatives behind a strong Arctic front.

Ahead of the major winter storm, a strong cold front will move across the region early Friday, bringing an Arctic airmass to the area. Behind the front, northerly winds will be breezy overnight and into the early morning at around 10-15 mph with gusts to 25 mph. This combined with temperatures in the teens will allow wind chills to drop to the low-end negatives for northern portions of the area to near 10F in NE NC. Cold Weather Advisories have been issued for the entire forecast area from late Friday evening through Saturday morning.

KEY MESSAGE 3...A prolonged period of very cold temperatures is expected beginning Saturday AM and persisting much of next week with the potential for temperatures to remain below freezing for several days. Impacts from the winter storm are likely to last well into next week due to the very cold temperatures.

Behind the winter storm this weekend, strong high pressure (1030+ mb) from the Canadian plains will shift over the SE CONUS with potent upper level troughing. The combination of these features will keep very cold temperatures over the area through much of next week. This, along with any snowpack, will likely keep high temperatures below freezing for an extended period of time. Low temperatures Tuesday night/Wednesday AM will likely be the coldest we have seen in some time, with readings ranging from around 0 across the NW Piedmont, to single digits for much of the inland forecast area, and teens closer to the coast/SE. These cold temperatures, combined with a W to NW breeze, will result in wind chills ranging from -10 to -5 inland and 0 to 10 across the southeast and along the coast. Extreme Cold headlines will likely be needed for a majority of the area with Cold Weather Advisories elsewhere. Overnight lows in the single digits and teens will be common for the remainder of the week. Long term model guidance is showing the potential for another Arctic blast by midweek, potentially sending our high temperatures back into the 20s by Thursday and overnight lows into the mid to lower single digits.

This prolonged period of very cold temperatures behind the winter storm could be quite dangerous for those without power. It is important that all take precautions in event that power is unable to be restored in a timely manner.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

As of 1210 PM EST Friday...

VFR conditions are expected to prevail through the TAF period. Mid to high level clouds will continue to pass through this afternoon as a weak disturbance passes to our south. Can't rule out a few light showers across NE NC/ECG this afternoon into tonight. Winds remain light and generally out of the NNW inland and NE along the coast for the remainder of the daytime hours. A strong cold front will then push through switching winds out of the NNW/N after 02/03Z and increasing speeds to 12-18kt with gusts up to 20-25kt. The strongest winds are expected along the coast, where gusts up to 30kt are possible, including ORF. Winds will remain gusty through the rest of the TAF period. Clouds will increase throughout the day on Saturday ahead of the incoming storm system.

Outlook: Winter weather is expected to move in later Saturday through Sunday night across all terminals, with a more prolonged period of winter weather likely at RIC, SBY, and PHF. Significant CIG and VIS restrictions are anticipated. Precip is expected to initially start as SN, possibly becoming +SN overnight/early Sunday. A changeover to sleet and freezing rain will overspread the terminals throughout the day on Sunday resulting in ice accumulations on most surfaces. Plain rain may eventually occur at ORF/ECG, but uncertainty regarding winter impacts there is higher. An extended period of degraded flight conditions is expected to continue through Sunday night.

MARINE

As of 345 AM EST Friday...

Key Messages:

- Gale Warnings remain in effect tonight for the Chesapeake Bay and coastal waters south of Cape Charles Light (and have been added for the Currituck sound). A Small Craft Advisory is in effect elsewhere.

- Strong winds continue Sunday (NE to E) as developing coastal low pressure slowly lifts NE offshore, shifting to the NW Monday with high pressure gradually building on from the SW. Sub-SCA conditions prevail today well out ahead of approaching arctic high pressure. Strong cold air advection develops this evening as a secondary/reinforcing cold front crosses the area. NNW winds are forecast to increase to 25-30 kt w/ gusts to 35 kt over the bay, southern coastal waters, and Currituck sound, with SCA conditions farther NE along the middle and upper Atlantic coast and over the rivers.

Winds decrease below Gale thresholds Saturday morning, but will remain solid SCA, and Gales will likely need to be replaced by SCA for a time over the Gale Warning area. Extended the SCA headlines through 4th period/early Sunday morning for the lower James and northern coastal waters (but have the headline ending in the upper rivers Sat aftn given a 6-12 hr lull). It appears that at least SCA conditions persist into early next week, with low-wnd Gales again possible Mon night on the back side of the departing low through sunrise Tuesday. Waves and seas will build along with the stronger winds early Saturday and likely peak on Sunday in the 3-5 ft and 6-9 ft ranges, respectively. Freezing spray has been added to the MD and most of the VA waters tonight into Saturday, and will be needed Monday night and Tuesday as Arctic high pressure quickly builds across the eastern CONUS.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...Cold Weather Advisory from 8 PM this evening to 10 AM EST Saturday for MDZ021>025. Winter Storm Watch from Saturday afternoon through Monday afternoon for MDZ021>025. NC...Cold Weather Advisory from 8 PM this evening to 10 AM EST Saturday for NCZ012>017-030>032-102. Winter Storm Watch from Saturday afternoon through Monday afternoon for NCZ012>014-030-031. VA...Cold Weather Advisory from 8 PM this evening to 10 AM EST Saturday for VAZ048-060>062-064>069-075>090-092-093- 095>100-509>525. Winter Storm Watch from Saturday afternoon through Monday afternoon for VAZ048-060>062-064>069-075>090-092-093- 095>100-509>525. MARINE...Gale Warning from 10 PM this evening to 7 AM EST Saturday for ANZ630>634. Small Craft Advisory from 10 PM this evening to 1 PM EST Saturday for ANZ635>637. Small Craft Advisory from 7 PM this evening to 7 AM EST Sunday for ANZ638-650-652-654. Gale Warning from 10 PM this evening to 10 AM EST Saturday for ANZ656-658.