Weather with Bill Evans

Good Day On This Friday December 5, 2022 High pressure moves across the region today and then slides away to the northeast tonight. An extensive frontal system with a broad area of low pressure approaches for Tuesday into Wednesday, before exiting to the east Wednesday night. High pressure overhead for Thursday gives way to another low pressure system that may pass over, or just to the south of the area Thursday night through Friday night. High pressure may then briefly return for next weekend into early next week. High pressure will be directly over the area this morning providing clear skies and seasonable temperatures. By this afternoon some high clouds begin to streak in from the west, but look for a mostly sunny day overall with temperatures climbing to seasonable levels. Most daytime highs will be in the middle to upper 40s, with perhaps a few 50 degree readings across southeastern sections on a light southerly wind. For tonight as high pressure slides away to the northeast look for clouds to increase. The clouds should start to lower and thicken later at night. The temperature forecast tonight is a bit tricky, especially initially as a light onshore flow and some weak warm advection attempts to get going. Before the increased cloud cover can take hold temperatures should drop with some radiational cooling during the evening, especially away from the coast. This should be short lived though as the synoptic flow begins to increase later at night with clouds lowering and thickening. Before the mid deck can thicken with respect to clouds, some patchy fog could form across far northeastern zones. Confidence is low, but some patchy fog is possible for the late evening and closer to midnight before the column moistens higher up, especially further northeast. In any event, the night should remain primarily dry as slight chance PoPs have been introduced just before daybreak across western areas, but this is a minimal chance. Initially temperatures will be in the lower 30s across portions of Orange County, but the expectation is temperatures should begin to climb towards daybreak just before any precipitation moves in. Lows will be mainly in the 30s, with some lower 40s in the metro. On Tuesday the frontal system off to the west will slowly make its way east. The model consensus is delaying the progression of the rain compared to previous runs. Thus slight chance to chance PoPs begin the day across most of the area, with likely PoPs being introduced in the morning across far western sections. As temperatures warm quickly on a SE flow regime, look for precip to be in the liquid form across the entire area. Likely and categorical PoPs then progress east later in the day and towards evening across eastern most sections. The best lift and forcing occurs towards the late evening and overnight / early Wed AM across the area. This is when about 3/4 inch to an inch of rain is most likely to occur. The rain will be steady and rainfall rates won`t be high enough with this rainfall being of long enough duration to preclude any flooding concerns. This will be a stratiform rain with lighter and more intermittent rain to follow for much of the day on Wednesday and Wednesday evening. It will be much milder for Tuesday night with temperatures rising mostly into the lower and middle 50s, with only a few upper 40s across western portions of Orange County. On Wednesday due to a southerly flow look for temperatures to average more than 10 degrees above normal region wide, with mostly middle and upper 50s. As the front gets further east Wednesday night the area will gradually dry out with cloud cover still lingering throughout the night. Colder air will slowly work into the region from west to east closer to daybreak on Thursday. Broad confluent flow aloft on Thursday gives way to a shortwave ejecting from the Central Plains on Friday and traversing the area over the weekend. Amplifying ridging aloft looks to then return by weekend`s end into early next week. At the surface, high pressure to the north on Thursday heads off to into northeast Canada while a surface low associated with the aforementioned shortwave develops over the OH Valley by Friday morning. Some increase in model divergence noted here with the 00Z cycle from the global suite. The EC, and many of its ensemble members keep stronger ridging to the north in place longer than its counterparts, and as a result move a weaker surface low to our south through the Mid-TN valley and offshore by Saturday afternoon. On the other hand, the GFS maintains a stronger surface low with the Canadian high retreating quicker, with the low and associated system passing over the area by Friday night into Saturday. Many of the GEFS members also agree with this scenario. So, still plenty of uncertainty for the weekend with this low confidence forecast. Have decreased NBM PoPs a bit for this Friday-Sunday period, keeping slight chance in for the duration. With respect to ptypes, thermal profiles suggest a mainly rain event save for interior CT and northern parts of the Hudson Valley, where cold air at the onset Friday may result in some snow showers mixing in at times. High temperatures will be above normal on Thursday, with a return to near or slightly below normal for the rest of the period. Sub-SCA conditions are expected through tonight as high pressure slides across and east of the waters. Seas and winds nudge up into Tuesday and Tuesday night with marginal small craft conditions possible for a time with winds gusting at or just above 20 kts on the ocean with 4 ft seas. Small craft conditions will be more likely during the first half of Wednesday on the ocean with seas averaging closer to 5 ft. The winds will then shift offshore and become more west, and eventually northwest at around 10 to 15 kt Wednesday night Sub small craft conditions are likely to return to the ocean as seas subside to closer 4 ft late Wednesday night into early Thursday morning. NE winds then increase Thursday night into Saturday with a return to SCA conditions at least on the ocean waters. Non-ocean waters should see sub-criteria conditions through the entire period. Despite rainfall amounts of around an inch during midweek, no hydrologic concerns are expected through the period as this is expected to be a longer duration rain event.