textproduct: Wakefield

WHAT HAS CHANGED

A Winter Weather Advisory has been issued from interior NE NC to portions of Hampton Roads from 6 PM this evening through tonight. Not everywhere in the advisory area will likely see 1"+ totals, but a ~50 mile wide band of 1-2" of snow is possible from interior NE NC to Hampton Roads.

KEY MESSAGES

1) Another shortwave crosses the area tonight. Snow amounts remain similar to the previous cycle, with a ~50 mile wide band of 1-2" of snow possible, most probable somewhere from interior NE NC to Chesapeake/VA Beach.

2) A clipper system may bring light snow to parts of the area Friday before another influx of Arctic air brings sharply colder temperatures this weekend.

DISCUSSION

As of 210 AM EST Wednesday...

KEY MESSAGE 1...Another shortwave crosses the area tonight. Snow amounts remain similar to the previous cycle, with a ~50 mile wide band of 1-2" of snow possible, most probable somewhere from interior NE NC to Chesapeake/VA Beach.

A weak shortwave is crossing the area early this morning. At the surface, a cold front is entering far northern portions of the FA. Light precipitation (mainly rain) has been falling the past couple of hours, tough a brief period of light snow is possible on the MD Eastern Shore between now and 4 AM.

The front from the initial shortwave and any light precipitation becomes (temporarily) suppressed to the south during the day today. Another trailing southern stream shortwave is expected to cross the area tonight. In response, weak sfc low pressure is progged to develop along that front before tracking offshore of the NC coast by early Thursday AM. The 00z models are consistent in showing a somewhat sheared out shortwave, but there is good agreement in a second round of precip across S/SE VA and NE NC from early this evening through part of tonight. Again, the amplitude of the shortwave will be critical in determining how far north the precip gets (and how intense it is as well). Areas north of a Lunenburg- Petersburg-Williamsburg line likely see little to no additional precip after this morning. The main forecast challenge is to determine whether there will be a narrow (~50 mile wide) swath of 1- 2" snow totals on the northern flank of the precip shield. If that does occur, determining exact location is not a sure thing given how narrow we expect the area of snow to be.

Weak low-level CAA will be ongoing today with highs only in the mid- upper 30s to around 40F. It may very well be dry throughout the day with mostly cloudy-overcast skies. Precip is expected move back into southern VA/NE NC during the aftn-early evening. P-type will initially be rain, but is expected to gradually change over to snow from north to south between 6 PM-2 AM. Precip should change over to snow across all areas (including NE NC) tonight, though accums may be tough to come by closer to the Albemarle Sound (i.e. Edenton to Currituck County) where temps struggle to drop below freezing until after the precip ends. Most of the models (aside from the GFS/GEFS) show a zone of mid-level frontogenesis moving across the area tonight, which would lead to a 4-6 hour period of light to occasionally moderate snow. Several models still try to depict light ice accumulations in southern VA and NE NC which is unlikely in this pattern and not supported by a closer look at model soundings. Though can't rule out a bit of freezing drizzle as precip ends and we lose saturation from 700-500mb. Will continue to show sleet mixed in with snow for a few hrs across southern VA/NE NC, but will continue to not mention any freezing rain at this time. Temps should drop into the upper 20s to lower 30s tonight when the precip is falling (guidance shows colder temps during the precip but often overestimates that initial push of stronger CAA). Most of the CAMs as well as global models/ensembles show a band of 1-2" across far SE VA and interior NE NC. The 00z/04 global ensembles (aside from the GEFS) continue to show 40-60% probs for 1" of snow with little to no 3" probs across far southern VA and NE NC. This assumes a 10:1 ratio which may be on the high side, especially in the 1-2 hrs after the initial changeover to snow. While there is uncertainty, went ahead with a Winter Weather Advisory for interior NE NC and SE VA from Emporia to Norfolk/Newport News/Hampton/VA Beach. And did not include Chowan to Currituck given that temps likely don't fall enough to get appreciable accums across the majority of those counties. Of course this forecast could definitely change even today given the (very) small scale nature of the potential snow. Also to reiterate, a slightly more or less amplified shortwave could easily mean the difference between little to no snow anywhere and 2"+. So it's still not a sure thing even though an advisory has been issued (and fully expect that not everywhere in the advisory area sees 1"+ totals).

KEY MESSAGE 2...A clipper system may bring light snow to parts of the area Friday before another influx of Arctic air brings sharply colder temperatures this weekend.

Cold high pressure builds east on the heels of the departing system as well as a deep trough aloft, ushering in another cold airmass for the late week period into next weekend. A clipper system crosses the area Friday afternoon through Friday night. This system could bring light snow to the area, with the best chances north of I-64 (and especially across northern portions of the FA). Global ensembles have a mean of a few tenths of an inch, with no higher than 10-30% probs for 1" across far northern portions of the area. While it likely won't snow everywhere on Friday, there is high confidence that the clipper system will usher in a reinforcing shot of colder air. This will result in another cold (though mainly dry) weekend into early next week with temperatures well below normal. While much colder than normal area-wide, the setup will really favor the coldest conditions over the NE with highs only in the 20s Sat-Sun, as south central VA and interior NE NC see highs into the upper 30s/lower 40s. Wind chill values worthy of Cold WX headlines are likely over the NE but more uncertain elsewhere.

AVIATION /08Z WEDNESDAY THROUGH SUNDAY/

As of 1245 AM EST Wednesday...

VFR conditions prevail at this hour but degraded conditions are expected by later this morning. There is still the potential for light snow at SBY with MVFR or IFR VSBYs from now-10z, with nothing more than light rain with no VSBY restrictions elsewhere. CIGs drop to MVFR at all terminals by 08-11z, with IFR CIGs expected by 10-12z at RIC and SBY and spreading further southeast after 12z. MVFR to IFR CIGs then prevail through much of the day at all sites outside of SBY, which likely improves to VFR by the afternoon. Precipitation chances increase late in the day across the SE terminals (highest PoPs are at ORF/ECG) as another wave of low pressure approaches. Precip likely begins as a rain/sleet/snow mix at PHF/ORF between 22-01z before changing to all snow by 02-03z. Precip likely ends at PHF by 03-06z but could hang on at ORF until 07-08z. At ECG, rain is expected before changing to snow after 04-06z. IFR VSBYs are likely in any snow this evening-tonight. Winds become NE and increase to ~10 kt later this morning through the remainder of the period.

Outlook: VFR Thursday into Friday morning. A strong cold front crosses the region Friday into Friday night, bringing the potential for additional rain or snow showers and potential sub- VFR conditions. Gusty winds are likely behind the front this weekend.

MARINE

As of 315 AM EST Wednesday...

Key Messages:

- Small Craft Advisories have been issued for the Chesapeake Bay, Lower James River, and coastal waters south of Parramore Island from this evening into Thursday night.

- Confidence continues to increase in the potential for strong Gale conditions and perhaps even Storm conditions from late Friday night through Saturday night behind a strong cold front.

- Low Water Advisories have been extended through 7 AM today for the Currituck Sound.

Latest surface analysis depicted a stationary front south of the local waters with a weak cold front north of the local waters early this morning. This weak cold front pushes south across the region later this morning with a weak surface low riding along it. Most of the model guidance keeps winds sub-SCA behind the front through this afternoon. However, a few gusts up to 20 kt are possible this afternoon. A second surface low moves from west to east across the Carolinas late this afternoon into tonight. This low is expected to be stronger than the first, allowing for stronger CAA across the local waters. As such, expect N/NNE winds to increase to 15-20 kt with gusts up to 25 kt across the Ches Bay, Lower James, and coastal water south of Parramore Island. The strongest winds are expected to be across the NC coastal waters and Currituck Sound where gusts up to 30 kt are possible. Meanwhile, waves and seas build to 3-4 ft and 4-6 ft (highest across the southern waters) respectively. As such, SCAs have been issued for these areas beginning this evening. Winds become N Thu, diminishing to sub-SCA criteria by Thu night. However, seas remain elevated across the southern coastal waters (particularly the NC coastal waters) until Fri morning. As such, SCAs remain in effect through Thu night for this area. Winds likely remain below SCA criteria north of Parramore Island with wind probs for 25 kt gusts averaging less than 40%. Additionally, snow is possible across the Ches Bay and northern coastal waters with rain across the southern coastal waters later this afternoon through tonight. Rain may mix with or change over to snow even across the southern coastal waters tonight. Any snow has the potential to reduce visibility.

Winds briefly diminish Thu night into early Fri night before a strong cold front crosses the local waters Fri night. Strong CAA is expected behind this front with NW winds quickly increasing to 30-40 kt with gusts up to 45 kt. Wind probs for sustained 34 kt winds were 80-100% across the Ches Bay and coastal waters with probs for 43 kt gusts generally 80-100% as well. Additionally, probs for 48 kt gusts were 40-60%. As such, confidence is high in strong Gale conditions from late Fri night through Sat night with low-moderate confidence in Storm conditions. Will note that both the GFS and EURO have 35-40 kt sustained winds across the local waters, adding further confidence. Additionally, while wind probs are lowest across the NC coastal waters, the aforementioned models both have sustained Gale conditions there as well. Gale (or Storm) Watches will likely be needed later this afternoon or tonight with the decision to go with Gale or Storm watches likely influenced by what the 12z models show. However, it is a bit too early to issue them at the moment given that Gale conditions don't begin until the very end of the sixth period.

Given the strong winds and cold temps, moderate freezing spray is also likely Sat and Sun. Heavy freezing spray is also possible if winds continue to trend stronger. As such, Freezing Spray Advisories or Heavy Freezing Spray Warnings will likely be needed as we get closer. Additionally, given the strong winds, waves and seas are expected to build to 5-7 ft and 6-10 ft (potentially higher) respectively this weekend.

Otherwise, the water levels of the Currituck Sound continue to show low water levels with some gauges showing around two feet below normal water levels. However, most gauges have begun to show signs of improvement. As such, have extended the Low Water Advisory through 7 AM. Will note that given the strong NW winds this weekend, another period of low water levels appears likely for the Currituck Sound.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...Winter Weather Advisory from 6 PM this evening to 7 AM EST Thursday for NCZ012>014-030. VA...Winter Weather Advisory from 6 PM this evening to 4 AM EST Thursday for VAZ087-092-093-095>098-524-525. MARINE...Small Craft Advisory from 10 PM this evening to 6 PM EST Thursday for ANZ630. Small Craft Advisory from 10 PM this evening to 10 PM EST Thursday for ANZ631-632-634-638-654. Low Water Advisory until 7 AM EST this morning for ANZ633. Small Craft Advisory from 10 PM this evening to 1 AM EST Friday for ANZ633. Small Craft Advisory from 10 PM this evening to 6 AM EST Friday for ANZ656-658.