yoda

3k NAM looks a bit better too

DCA around 0.35" QPF

I like hour 21 on the soundings near DCA

I didn't remember what the new terminology was for certain amounts

F....

Long and well written afternoon AFD from LWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 243 PM EST Thu Jan 18 2024 .SYNOPSIS... A pair of low pressure systems over the Ohio River Valley and off the Southeast Coast will affect the Mid-Atlantic through Friday. Arctic high pressure will build in the wake of these lows this weekend as they merge offshore. High pressure will then settle south of the area early next week. && .NEAR TERM /THROUGH FRIDAY/... High pressure has departed off the East Coast into the western Atlantic Ocean as of mid afternoon. Low pressure was moving from the mid Mississippi River Valley up the Ohio River Valley, with a second area of low pressure off the coast of GA/SC moving northeastward. Aloft, a ridge axis was moving eastward across the western CONUS approaching Idaho, an upper-level low was moving offshore of Newfoundland, and a trough with a few embedded vort maxes was in between moving southeastward into the Midwest. This pattern is typically favorable for accumulating snowfall over the Mid-Atlantic given sufficiently cold temperatures (which are firmly in place). The flow is progressive, and this lends to a quick-moving system, with phasing/stronger deepening of low pressure not occurring until the system is well offshore. Still, PVA from multiple shortwaves, LFQ of a strong (150+ kt) upper jet, and modest WAA will result in a period of snow across the region. Given the strong dynamics aloft, an inverted trough axis will likely develop well to the NW of the offshore low. With the cold airmass and a deepening DGZ to around 150 mb, snowfall in some areas may very well overperform beneath wherever this trough axis sets up (could be as far north as central NJ, or as far south as northern/central MD). Confidence remains low in the exact placement of the heaviest QPF/snow, as these mesoscale features typically have lower predictability. In terms of sensible weather... Flurries may develop as early as nightfall along and west of the Allegheny Front, and by mid to late evening elsewhere as the column gradually saturates with the lead wave pushing across. Accumulating snow most likely holds off until just after midnight over the Alleghenies, and the pre-dawn hours further east toward the metro areas/I-95 corridor. This initial snow will be largely jet induced as the LFQ dynamics move atop moistening low levels. The strongest lift overlays the DGZ for a brief (1-3 hr) window east of the mountains from just before dawn through the first half of the morning commute. Given cold temperatures and moderate snowfall rates which may briefly exceed 0.5 in/hr, this will likely lead to a very slippery Friday morning commute. From late morning into the early afternoon, the mid-level trough axis sharpens and takes on a negative tilt overhead. This is a period of greater uncertainty, as the exact placement of this trough axis will dictate the placement of enhanced precipitation/snow. This is also the period where the DGZ is at its deepest (per BUFKIT), and the most likely time period for overperforming snowfall. Bands of snow spawned by these types of features can be narrow but produce much higher snowfall on a localized basis, so it bears close monitoring. As confidence in the placement of this banding increases, areas of northern/northeast MD may need to be upgraded to a Winter Storm Warning. But confidence in the placement of higher totals was a bit too low to upgrade with the Thursday afternoon forecast package. Lingering low-level moisture, increasing MUCAPE in the BL (stretching up into a lowering DGZ), and lift via continued PVA ahead of a trailing wave, could cause at least scattered snow shower activity to linger through late Friday afternoon or later. These may add another coating to an inch in isolated spots where snow showers are heavier or more persistent. Low temperatures tonight will range from around 20 over the higher ridges of the Alleghenies, to around freezing over southern MD. Temperatures will likely rise to or just above freezing along and southeast of a line from near Baltimore and along the immediate northern bay shore, across far northern VA, to the lower elevations of the central Shenandoah Valley on Friday. Further north and west, temperatures will hold between 25-30 degrees (20-25 mountains)

Second one is different... the one for N MD

URGENT - WINTER WEATHER MESSAGE National Weather Service Baltimore MD/Washington DC 227 PM EST Thu Jan 18 2024 MDZ004>006-008-011-507-508-190330- /O.CON.KLWX.WW.Y.0009.240119T0900Z-240120T0600Z/ Frederick MD-Carroll-Northern Baltimore-Cecil-Southern Baltimore- Northwest Harford-Southeast Harford- 227 PM EST Thu Jan 18 2024 ...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 4 AM FRIDAY TO 1 AM EST SATURDAY... * WHAT...Snow expected. Total snow accumulations of 2 to 4 with localized amounts around 5 inches. * WHERE...Portions of north central, northeast and northern Maryland. * WHEN...From 4 AM Friday to 1 AM EST Saturday. * IMPACTS...Plan on slippery road conditions. The hazardous conditions will impact the Friday morning and evening commute.

URGENT - WINTER WEATHER MESSAGE National Weather Service Baltimore MD/Washington DC 227 PM EST Thu Jan 18 2024 DCZ001-MDZ013-014-503>506-VAZ053-054-501-505-506-526-190330- /O.CON.KLWX.WW.Y.0009.240119T0900Z-240120T0000Z/ District of Columbia-Prince Georges-Anne Arundel- Northwest Montgomery-Central and Southeast Montgomery- Northwest Howard-Central and Southeast Howard-Fairfax- Arlington/Falls Church/Alexandria-Northern Fauquier- Western Loudoun-Eastern Loudoun-Northwest Prince William- 227 PM EST Thu Jan 18 2024 ...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 4 AM TO 7 PM EST FRIDAY... * WHAT...Snow expected. Total snow accumulations of 1 to 3 with localized amounts upwards of 4 inches in the northern and western suburbs of Washington D.C. * WHERE...Portions of central Maryland, The District of Columbia and northern Virginia. * WHEN...From 4 AM to 7 PM EST Friday. * IMPACTS...Plan on slippery road conditions. The hazardous conditions will impact the Friday morning and evening commute. PRECAUTIONARY/PREPAREDNESS ACTIONS... Slow down and use caution while traveling. When venturing outside, watch your first few steps taken on steps, sidewalks, and driveways, which could be icy and slippery, increasing your risk of a fall and injury.

WWAs up for the rest of the LWX CWA that didn't have one earlier

This snippet was in the AFD from LWX as well this morning There are indications of CSI banding moving from south to north Friday morning, so areawide there could be brief reductions in visibilities coupled with higher snowfall rates. Given cold roads, travel could be slick/difficult Friday morning.

Georgetown isn't

NAM'D

I guess LWX is going to wait till after the 12z suite to put out WWAs for i66 corridor and north?

Slight south shift/increase in snow totals

12z UKIE 1-2 for most of the region

Close up view

12z RGEM

00z Euro is 2-4 across the region

Banned right before the biggest storm of the season... wow

For Randy - because I remember him posting this gif before a long time ago

For reference

Gimme 2-4/3-5