719 FXUS61 KLWX 041451 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 951 AM EST Tue Dec 4 2018 .SYNOPSIS... High pressure will build eastward through the mid-week. An upper level disturbance will traverse the region on Wednesday. Another cold front will cross the area late in the work week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Continued cold air advection this morning has brought party to mostly cloudy skies to the area under northwest flow. Upslope snow showers are tapering off this morning, and should shut off completely by midday. Persistent northwest flow will continue to promote some level of cloud cover through much of the day, but based on satellite trends, am favoring more partly sunny skies as opposed to mostly sunny by this afternoon. Highs today forecast to top out in the upper 30s in the Highlands to the middle 40s further east in the metro areas. Aside from a few minor tweaks to the current forecast, no major changes needed at this time. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... Northern stream shortwave energy will be emerging from the midwest tonight and crossing the forecast area Wednesday. Although moisture will be in short supply, vigorous vorticity advection and favorable jet support suggests that PoP forecast Wednesday should be on the high side of envelope. Temperatures would support either snow or rain/snow mix. Confidence on accumulations still low; have placed 30 PoPs to about DCA/EZF. Flurries (or melting snow) looking more likely. High pressure will cross the area Thursday with zonal flow aloft. That will provide a better chance at benign, albeit still cold, conditions. && .LONG TERM /FRIDAY THROUGH MONDAY/... High pressure will build into the region Friday and Friday night. Dry and chilly conditions expected through the period. High temperatures only reaching the middle to upper 30s along and west of the Blue Ridge and across the Mason-Dixon region. Lows Friday night will be in the middle 20s and near 30 along the Chesapeake Bay. High temperatures, Saturday and Sunday, will only reach the upper 30s to near 40. A potential winter storm could develop over interior portions of the Southeast U.S. and slide across parts of the mid- Atlantic during the weekend. Models have trended the storm track and the potential for the heaviest snow to the south and southwest of our region Sunday through early Monday. Exactly where the winter storm tracks and the heaviest snow sets up remains still quite uncertain. We are still 5 to 6 days away from such a storm. When you look at the average of the current GFS and EURO model snowfall output, it says possible snow accumulations could reach as far north as I-66 with the heaviest snow accumulations along I-64 and the Charlottesville vicinity and areas south and southwest toward Roanoke and Richmond and the North Carolina border. The Canadian model is really hitting us hard with heavy snowfall across much of our region. This model seems to be the outlier at this time. Looking back on last Friday night, the EURO model had greater D.C. receiving over 6 inches of snow, while the GFS model had us not getting any snow. Then, Saturday night, the EURO had D.C. getting between 3 to 6 inches of snow, while the GFS got on board the snow train giving us around 3 inches. As for Sunday night, the EURO had us snow-free, while the GFS was giving us around 6 inches. Currently, neither the EURO nor the GFS is giving us any snow in the greater D.C., while keeping the heaviest snow confined to an area from the central Shenandoah Valley and south and southeast toward the North Carolina border. The bottom line is that 2 of our big player models are flip-flopping on storm track and snow amounts. For now, we will leave chance POPs of snow and/or rain and snow for Sunday through Monday. As this winter storm exits late in the day Monday into Monday night, high pressure will become reinforced Monday night and Tuesday. Drier and cold conditions expected and perhaps a gusty northwest wind as well. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... VFR conditions expected today at all terminals with northwest winds 10-15 knots, gusting upwards of 20 knots through early afternoon. Winds will abate late this afternoon and through tonight as high pressure builds into the region. Clouds will be thickening tonight in advance of a shortwave Wed. MVFR possible beyond scope of current TAF. There may also be a few flurries, or even a period of light snow midday. The intensity of projected snow (emphasis on light) and air temperatures suggest accumulations unlikely. However, confidence on specifics rather low this far out. Building high pressure Thursday suggest VFR will prevail, extending through Saturday. && .MARINE... Northwest winds with cold air advection will bring SCA gusts to the main stem of the Bay and Tidal Potomac through early this afternoon. As high pressure builds over the waters through tonight, winds will abate and thus no headlines expected at this time. Surface high pressure suggests that additional Advisories remain unlikely for the rest of the week. && .CLIMATE... Rainfall totals continue to creep upward, with Baltimore setting the annual record already. Here are the current rankings for wettest year on record (through December 2nd): Washington DC area (DCA) 1. 61.33 inches (1889) 2. 60.83 inches (2003) 3. 60.78 inches (2018) 4. 60.09 inches (1878) Weather records for the Washington DC area have been kept at what is now Ronald Reagan Washington National Airport (DCA) since 1945. Precipitation records observed downtown extend the period of record back to 1871. Baltimore MD area (BWI) 1. 65.67 inches (2018) 2. 62.66 inches (2003) Weather records for the Baltimore MD area have been kept at what is now Baltimore-Washington International Thurgood Marshall Airport (BWI) since 1950. Precipitation records observed downtown extend the period of record back to 1871. Dulles VA area (IAD) 1. 65.67 inches (2003) 2. 61.30 inches (2018) 3. 59.05 inches (1972) Weather records have been kept at what is now Washington Dulles International Airport (IAD) since 1960. NOTE: All climate data are considered preliminary until reviewed by the National Centers for Environmental Information (NCEI). && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 2 PM EST this afternoon for ANZ531>534-537-539>543. Small Craft Advisory until 11 AM EST this morning for ANZ530- 538. && $$ SYNOPSIS...HTS NEAR TERM...BKF/HTS SHORT TERM...HTS LONG TERM...KLW AVIATION...BKF/HTS/KLW MARINE...BKF/HTS/KLW CLIMATE...LWX