textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 06z TAF.

KEY MESSAGES

- 1) Breezy and very warm conditions continue through Friday.

- 2) Rain chances slowly increase on Friday as a front approaches, with better chances for rain on Saturday and Saturday night.

- 3) Cold and dry conditions develop early next week.

DISCUSSION

KEY MESSAGE #1: Breezy and very warm conditions continue through Friday.

Deep and persistent southwesterly flow has allowed our weather to have a touch of spring in it. Highs have been in the 70s the last two days, and we are forecasting highs in the mid 70s to low 80s today and tomorrow! Heights are relatively high for this time of year but low-level temps are very anomalously warm. 850 hPa temps are 95th-98th percentile in the LREF mean data, which should yield very warm temps. ECE EFI guidance shows values of 0.6-0.7 today and 0.8-0.9 tomorrow, both with low shift of tails values. So we can expect anomalously warm temps that probably won't be breaking records, which makes sense. Lots of clouds are expected to be around today and Friday, with showers possible both days (esp. Friday morning). This will likely hinder us from reaching whatever our ceiling for high temps would be otherwise. Still, expecting well above normal temps both days. Winds will also be breezy as a tight pressure gradient is expected to remain in place ahead of the approaching cold front.

KEY MESSAGE #2: Rain chances slowly increase on Friday as a front approaches, with better chances for rain on Saturday and Saturday night.

Guidance continues to hone in on a solution to this weekend's major weather question - rain, rain amounts, and rain timing. Ensemble spread is lower than it was 24 hours ago, and the deterministic models continue to align more closely. The larger scale expectation for this weekend is that weakening front will approach the area on Friday, with increasingly high PWs ahead of it. Guidance continues to paint a low QPF/high PoP scenario on Friday, with scattered showers expected through the day ahead of the front. Don't really think everyone will see rain as the front itself will be weakening & the synoptic forcing should be moving well to our north. The progression of this front is important to the rain chances this weekend. It looks to be the focus for a batch of heavier rain on Saturday evening into Sunday morning a trough deepens through the OH Valley and forces a surface low to develop along the front and push into the Atlantic. Strong moisture advection associated with a strong 850 hPa jet is expected to arrive during the day on Saturday; the location of the weakening front will help dictate where the heaviest rain falls. Overall, it looks like totals should be 0.25"-0.5" as this system traverses the region. LREF clusters are all showing about a 30-50% chance of 0.5" or more of total rainfall with this, which will be beneficial considering the drought conditions. There is still some uncertainty with this overall, though, as the parent system driving this is quite complex & guidance has tended to amplify these systems gradually as we approach them of late. So, given our proximity to robust PWs, it would not surprise me if we saw over forecast rain totals tick up slightly over the next couple of days.

KEY MESSAGE #3: Cold and dry conditions develop early next week.

A potent upper trough is expected to dominate the weather across the Eastern CONUS early next week. At the surface, a cold and dry air mass will move in behind the departing weekend system with below normal temperatures favored. Monday looks to be the coldest day of the next seven follow by a gradual warm up towards the middle of next week. Monday may also be breezy due to a tight pressure gradient but winds should be lighter Tuesday and Wednesday as surface high pressure moves in from the west.

AVIATION /06Z THURSDAY THROUGH MONDAY/

VFR conditions continue but MVFR ceilings are expected to develop near daybreak, continuing much of the morning before scattering out.

Winds have fallen to around 3-5 kts out of the southwest and will likely remain here much of the night. Satellite and recent observations show SCT to BKN mid level clouds between 5000 ft and 8000 ft filling back in and this deck is expected to gradually lower near/after daybreak with MVFR ceilings developing between 12-14z generally. Confidence has increased enough to add a predominant group for MVFR ceilings at CAE/CUB (already have one for AGS/DNL), and a TEMPO group for OGB has been added with guidance suggesting a couple periods of these ceilings here as well. The latest HRRR and HREF guidance is a bit more aggressive in terms of showing stratus closer to 700-1000ft rather than 1500-2500ft, but probabilities for this remain too low to add into the TAF at this time and confidence in these lower ceilings developing is low. MVFR ceilings are expected to continue until 17-19z generally where a couple stray rain showers cannot be ruled out mainly near AGS/DNL/OGB. Stratus is expected to gradually scatter out through the day but a BKN VFR deck around 5000 ft may linger into the evening hours. During the evening, cirrus may continue to move in before ceilings may begin to fall again during the next TAF period.

For winds, after 16-18z winds remain out of the southwest but pick up to 7-12 kts with gusts up to 20 kts possible much of the day before diminishing during the evening to around 4-8 kts, possibly becoming a bit more south-southwesterly.

EXTENDED AVIATION OUTLOOK...High low level moisture will bring chances for morning fog/stratus through this weekend. The next main rain chance and associated restrictions is expected to move in on Friday and again on Saturday, possibly continuing into Sunday.

CAE WATCHES/WARNINGS/ADVISORIES

SC...None. GA...None.