Key MESSAGE 1, Little change to the forecast reasoning with medium range guidance continuing to converge on a solution for the mid to late-week period, but notable differences remain. Where guidance is fairly well clustered is with an amplified upper trough that will be shifting east out of the Central U.S. While there is still some potential for a cutoff low to develop, most guidance have now trended towards more of a progressive and open wave as it moves through the Eastern U.S. Guidance differs on the timing, which leads to differences in precipitation placement, temperatures, etc. But, most guidance is now centering on the best chance of showers and thunderstorms coming Thursday and/or Friday. Of note, some guidance are showing anomalous moisture and higher-than-normal instability for early November. This would support the potential of some higher rainfall rates and totals should this materialize. It may even support at least a marginal risk of strong to severe thunderstorms. While there is some synoptic support for this potential, machine learning guidance doesn't show that strong of a signal. It's something worth keeping an eye on as the evolution of the upper level, and surface, pattern become more clear.
The other aspect of the forecast that appears to be coming more clear this week is the potential for above to well above normal temperatures, especially Wednesday and Thursday. While record highs may not be broken, warming low-level thicknesses in advance of the approaching trough should support highs warming into the 70s, with some low 80s possible inland. Meanwhile, overnight lows are forecast to be closer to our normal highs for this time of year. Some record warm lows may be in jeopardy. For reference, normal highs are around 70 in early November, with normal lows in the 40s inland and 50s along the coast.
14z Monday through Friday Forecast confidence is moderate to high over the next 24 hours.
Widespread mid and high clouds will accompany a slow-moving upper level trough as it continues to advance east across ENC through today. Some -SHRA may accompany this feature as well, especially during the daylight hours (when moisture and lift will be maximized). Significant reductions to VIS are not expected with any SHRA activity, though.
Later this evening and tonight, some mid and upper level drying may scour out some of the extensive cloudiness of late. Should this occur, it could support slightly better radiational cooling conditions and an increased risk of BR/MIFG/FG development. The latest short-term guidance continue to show modest probabilities of this occurring (30-50% chance). There is still some uncertainty regarding how much clearing will actually occur, so no sub-VFR conditions have been introduced into the TAFs just yet. At face value, guidance favors KOAJ, KPGV, and KISO for the best chance to see a period of reduced VIS.
Outlook: Coastal troughing near ENC may support periods of low CIGs and SHRA along the coast, mainly impacting KMRH. With increased low- level moisture, there may also be a nightly risk of BR/MIFG/FG at all TAF sites. Later in the week, a slow-moving frontal system may lead to a risk of TSRA and a more appreciable risk of sub-VFR conditions.
A pinched surface gradient remains in place between a coastal troughing offshore and a strong surface high anchored over the Mid-Atlantic States. Latest obs show NE-E winds 10-20 kt gusting 20-25 kt across the outer central and southern waters, with seas 3-5 ft nearshore and 4-6 ft offshore. Gradients will continue to grad relax through today.
Outlook: Coastal troughing is forecast to remain in place through at least the middle of the week, with the strongest gradient and highest winds focused across the central and southern waters. The coastal trough may drift inland by Wednesday with more of a dominant easterly flow developing for most waters. The flow then begins to become southeasterly by Thursday in the wake of the inland-advancing coastal trough. Guidance continue to keep probs for 25kt+ winds low through Thursday. However, there is a broad signal for low pressure development over the Southwest Atlantic later in the week. Should this occur, there may be an accompanying risk of 6 ft+ long-period swell development.
Nc, none. Marine, none.
