textproduct: Wakefield

WHAT HAS CHANGED

Updated key messages and main discussion. In general, probabilities remain low for accumulating snowfall across northernmost counties N of Richmond to Salisbury tonight and early Wed. However, probabilities for 1" of snow have increased slightly across far southern VA and NE NC for the tail end of the system Wednesday evening-Wednesday night.

KEY MESSAGES

1) Temperatures will warm into the 40s today, but a weak system could bring up to an inch of snow from Louisa County to the Maryland Eastern Shore tonight.

2) Another shortwave crosses the area Wednesday night. Snow amounts have continued to trend slightly upward, with a 50-75 mile wide band of 1-2" of snow possible somewhere from central VA to northern NC. At this time, it looks like the most likely location for this band (if it were to materialize) is in far south/southeast VA and NE NC.

3) Another influx of Arctic air will bring sharply colder temperatures late this week into next weekend.

DISCUSSION

As of 230 AM EST Tuesday...

KEY MESSAGE 1....Temperatures will warm into the 40s today, but a weak system could bring up to an inch of snow from Louisa County to the Maryland Eastern Shore tonight.

The moderating trend in temps continues today with weak southwesterly flow in advance of our next system. This will feel practically summer-like after the past ten days with highs in the 40s and some more substantial melting of snow/ice. A weak shortwave and its attendant cold front are progged to quickly cross the area tonight. Some very light overrunning precip pushes into the area as early as this evening, but this shouldn't amount to much. While a widespread 0.01-0.10" of liquid equivalent precip is likely tonight- early Wed, ensemble probs for > 0.10" are 20-30% at best across the area. P-type should be mainly rain for most of the area initially, with thermal profiles supporting snow at the onset (likely between 10 PM-1 AM) along and north of a Louisa-Colonial Beach-Ocean City line. Off and on light precip then continues through the night before mid-level drying ensues from west to east between 4-8 AM Wed AM as the first shortwave exits the area. Areas mainly NNE of Richmond could see a changeover to snow late tonight and Wed morning before precip ends. Snow amounts up to an inch are forecast across far northern portions of the FA, with amounts of 1-2" not completely out of the question on the MD Eastern Shore in a reasonable worst case scenario. Though some of the models have little to no snow tonight and ensemble probs for an inch remain no higher than 10-30%. With low dropping into the upper 20s north, the snow could cause minor travel impacts if at least 0.5-1" falls. Certainly not enough confidence in amounts of 1"+ to issue an advisory with this forecast package, but will continue to monitor.

KEY MESSAGE 2...Another shortwave crosses the area Wednesday night. Snow amounts have continued to trend slightly upward, with a 50-75 mile wide band of 1-2" of snow possible somewhere from central VA to northern NC. At this time, it looks like the most likely location for this band (if it were to materialize) is in far south/southeast VA and NE NC.

The front from the initial shortwave and any light precipitation becomes (temporarily) suppressed to the south during the day Wed. Another trailing southern stream shortwave is expected to cross the area Wednesday night. In response, weak sfc low pressure is progged to develop along that front before tracking offshore of the NC coast by early Thursday AM. If that trailing southern stream shortwave can amplify enough, a second round of precipitation would likely overspread portions of the area Wednesday afternoon before pushing offshore early Thursday morning. The most likely area to see precip is S of I-64 and E of I-95. Weak low-level CAA will be ongoing throughout the day on Wed (with a stronger push of CAA expected Wed evening/night). Highs Wed will struggle to get out of the mid-upper 30s. So while precip may initially be rain during the aftn, it should change over to snow across all areas (including NE NC) from N- S Wednesday evening/night. If that shortwave does become amplified enough, a narrow zone of mid-level frontogenesis would traverse the area and could lead to a 4-6 hour period of light to occasionally moderate snow. Temps should drop into the upper 20s to around 30F by Wed night when the precip is falling (guidance shows colder temps during the precip but often overestimates that initial push of stronger CAA). Therefore, 1-2" could definitely fall in a 50-75 mile wide band somewhere between central VA and northern NC. The 00z/03 global models and ensembles continue to show 30-50% probs for 1" of snow with 10-20% probs for 3" across far southern VA and NE NC. Some of the CAMs have come in farther north with the swath of accumulating snow Wed night (and have 1-2" amounts in the RIC Metro/Peninsulas). As for the forecast, have gone with the a blended approach showing amounts just above 1" across portions of SE VA and interior NE NC. Of course this forecast will change in the next 12- 24 hours. Also, a slightly more or less amplified shortwave could easily mean the difference between no snow anywhere and 2"+. So it's still not a sure thing attm.

KEY MESSAGE 3...Another influx of Arctic air will bring sharply colder temperatures late this week into next 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. Another clipper system for Friday night and Saturday may bring some additional light wintry precipitation, a light rain/snow mix if there is enough lingering moisture, but there is high confidence that it will usher in a reinforcing shot of colder air. This will result in another cold (though mainly dry!) weekend into early next week.

AVIATION /07Z TUESDAY THROUGH SATURDAY/

As of 1240 AM EST Tuesday...

VFR conditions prevail through this evening, with degraded conditions expected to overspread the terminals tonight. High clouds will increase today before thickening and lowering this aftn/evening in advance of a shortwave. That shortwave moves through the region tonight with the trailing cold front dropping through the area early Wednesday morning. A period of light snow with IFR VSBYs is possible at SBY between 04-10z, with light rain changing to a rain/snow mix at RIC, and mainly rain in SE VA/NE NC. CIGs drop to MVFR at all terminals tonight, with IFR CIGs possible by 09-12z Wed. Light/calm winds become WSW 5-10 kt late this morning into the aftn.

Sub-VFR CIGs likely prevail through the day on Wed (though SBY could rise to VFR) as it temporarily dries out. A secondary wave of low pressure follows later Wednesday into Wednesday night and this could bring a period of light snow (mainly to PHF/ORF/ECG) and additional sub-VFR conditions. VFR Thursday to Saturday with a strong but dry cold front crossing the region Friday night.

MARINE

As of 215 PM EST Monday...

Key Messages:

- SCAs remain in effect for the ocean through early tonight.

- Lighter winds and calmer marine conditions expected for most of this week, though low-end SCAs are possible Wednesday night/Thursday morning.

Significantly improved marine conditions are noted across the marine area this afternoon. Winds have generally diminished to 10-15 kt, though remain elevated to 15-20 kt 10-20 nm from shore on the ocean. Small Craft Advisories for the Chesapeake Bay expired at 1 PM, with SCAs continuing on the coastal waters due to elevated seas. In fact, buoy observations offshore of srn VA and NC are still reporting a 6- 9 ft significant wave height. Much lighter winds are expected this evening through Wednesday (generally 5-10 kt) as high pressure settles south of the region. Seas and waves in the bay will also diminish further. A weak area of low pressure and an associated cold front will move through later Wednesday. CAA behind the front could lead to marginal SCA conditions (with northerly winds) Wednesday night into Thursday morning. A strong cold front could then bring SCA or gale conditions by the weekend.

The Low Water Advisory for the Currituck Sound has been extended into this evening.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Low Water Advisory until 4 PM EST this afternoon for ANZ633. Small Craft Advisory until 7 AM EST this morning for ANZ658.