Marine Weather and Tide Forecast for Columbia, SC

KEY MESSAGES
1) Rain chances increase Wednesday with a few snow showers possible early Thursday.

2) Dry, gusty winds expected Thursday with an enhanced fire danger risk.

3) Cold weather continues into the weekend. Temperatures near cold weather advisory Friday morning.

DISCUSSION
Key Message 1: Rain chances increase Wednesday with a few snow showers possible early Thursday.

Ahead of a deep digging trough across the central US, a strong cold front and associated surface low will track into the Ohio Valley, and then up the east coast throughout Wednesday and Thursday. Ahead of this front, broad but fairly weak moisture advection will overspread the area with PWAT's climbing to near 1.0". HRRR members have trended a bit wetter with these prefrontal showers but still keep rain chances generally less 50% and very light QPF totals; best time period for rain showers is generally between 12-6pm Wednesday, focused along the I95 corridor. Overnight, the cold front will cross the area with notable CAA developing behind it and the upper vort max and enhanced lapse rates will pivot closer shortly after. Residual moisture, frontogenetic forcing, and very steep lapse rates below 700mb, cannot rule out some snow showers across the Midlands early Thursday morning; while the HRRR remains a major outlier, the positioning of the trough axis and frontal forcing nearly always over-performs guidance, especially when guidance shows non-zero CAPE in the near surface layer. Temps will be borderline and any showers would be brief, so impacts are expected to be minimal at this time.

Key Message 2: Dry, gusty winds expected Thursday with an enhanced fire danger risk.

Overall, not much change in the thinking for the cold advection regime on Thursday and potential fire danger. Behind the front, a very dry air mass will move into the area with rapidly decreasing dew points throughout the morning. Guidance often struggles in not dropping dew points fast enough behind strong fronts so will favor lower ends of the distribution. Therefore relative humidity will likely drop to 20-25 percent Thursday afternoon. However, the general trend continues among the blend members in weaker wind gusts Thursday afternoon. Probability of wind gusts greater than 30 mph remains around 30-40 percent.
While the threat has decreased slightly, there remains potential for Red Flag Warning criteria.

Key Message 3: Cold weather continues into the weekend. Temperatures near cold weather advisory Friday morning.

After 24-36 hours of strong cold advection behind the aforementioned front, near cold weather criteria low temps are expected early Friday. With high pressure settling nearby, decent radiational cooling should enhance the advected cold airmass and drop temps down into the upper 10's in most spots early Friday; NBM members now show a 50-80% chance of sub-20 F temps in the morning, with wind chills a bit lower. It still looks borderline if we will need a cold weather advisory product for Friday but guidance should come into a clear in the next cycle or two.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
VFR conditions are generally forecast to continue through the period, with some uncertainty emerging at the end of the TAF period.

Skies are clear and winds are generally light & out of the southwest across the area as westerly flow aloft ahead of our next system increases. Confidence is high that VFR conditions will continue through at least the next 12 hours but probably longer than that as low and mid level moisture is really lacking right now. This will change tomorrow as the synoptic pattern begins to favor light shower development across the area, beginning between 13z and 15z across the area. These should fall out of a mid-level deck as low-level moisture doesn't look like it will become too robust until later in the period. The most widespread showers should occur at the Augusta and Orangeburg sites, with CAE/CUB seeing lower coverage overall. The rain is generally expected to diminish in coverage by the afternoon but light showers are likely to still be hanging around out there as moisture increases ahead of an approaching front. This is where the uncertainty regarding ceiling restrictions comes into play as guidance seems pretty locked in on MVFR or IFR cigs developing near or just before/after 00z Thursday. Not totally sold on this scenario given how dry we are currently but have it signaled as a possibility in the TAFs.

EXTENDED AVIATION OUTLOOK...A mid-week system moving through could bring brief restrictions late Wednesday into Thursday, although confidence is low due to limited moisture. Strong gusty winds expected on Thursday.

CAE WATCHES/WARNINGS/ADVISORIES
SC...None.
GA...None.